初始涡的结构与尺度对涡旋自组织影响的研究

在涡旋自组织动力学的框架内,实施了9组积分时间为72 h的试验,分析初始涡廓线与初始涡尺度对多涡自组织的作用。试验的初始场上,存在着12个大小不等的β和γ中尺度的涡。若初始涡廓线为高斯型,则这些涡不能自组织形成一个α中尺度的涡;若初始涡廓线为双正弦型、抛物线型或压缩型,则这个α中尺度的涡可以形成。此外,涡廓线不同,三涡流型出现的时间迟早不一,较大尺度α中尺度涡出现的时间也迟早不一。同时,初始涡的半径大小也是影响自组织过程成败的一个重要因素。     

Relationships between fractal road and drainage networks in Wuling mountainous area: Another symmetric understanding of human-environment relations

Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.     

多尺度系统中台风自组织的研究

在一个4种尺度(副热带高压、台风、β中尺度涡群和γ中涡尺度)共存的系统中,用正压原始方程模式数值地研究台风自组织及其强度变化问题。结果指出:(1)由于多尺度的相互作用,在初始台风衰减的过程中,在该台风的西南方经自组织形成了一个新的台风,其尺度、强度与初始台风相同。在初始台风衰减消失后,新的台风维持一定的强度继续向偏西北方向移动。(2)初始γ中涡的个数和位置对自组织起来的台风的强度有显著影响。其影响机制是非线性相互作用的结果在不同尺度层次的传递。γ中尺度层次或γ中—β中层次的相互作用直接影响到β中层次涡作用的结果,或者使双β中涡合并,或者使双β中涡分离。β中涡层次的相互作用直接影响到台风层次———新台风自组织的过程。这种影响最后反映到自组织起来的台风的强度和路径变化的宏观行为。     

Can modelling enable us to understand the rôle of humans in landscape evolution?

Landform-evolution models have typically failed to include human actions, or have done so only in a static, scenario-based way. This failure is despite the extensive empirical data that suggest rates of soil erosion are most sensitive to anthropic pressure. The CybErosion modelling framework overcomes this limitation by using an agent-based approach to simulating the dynamic interactions of people and their landscapes. The interactions simulated relate to basic processes of food acquisition (hunting, gathering and basic agriculture) in prehistoric communities. Simulations demonstrate the value of this approach in supporting the vulnerability of landform evolution to anthropic pressures, and demonstrate the limitations of existing models that ignore human and animal agency, which are likely to produce both quantitatively and qualitatively different results. The model is also a useful heuristic tool for understanding human-landscape interactions and for suggesting directions for future research. Despite the acknowledged limitations of agent-based approaches in simulating human populations, it is suggested that further research will be fruitful, especially if combined with a range of field evidence.     

研究地震和岩石破裂现象的非线性科学方法

本文以地震孕育和岩石破裂过程的阶段(包括裂纹系形成、变形局部化和断层形成、断层活动和松弛)为线索,阐述了非线性科学方法(包括分形几何学,自组织临界现象和混沌动力学)的应用,提出了地震孕育过程和岩石破裂各阶段的普适性特征、机理和要着重研究的课题.     

地震活动的自组织和演化

通过余震活动资料,说明了地震活动中的自组织行为和分形现象.对于地震断裂系统,利用地震频度作为序参量,并应用绝热消去法建立了代表地震活动演化规律的序参量所满足的主方程.通过主方程的解,很好地解释了一次大地震过程中可能出现的各种地震活动现象和有序性变化.像许多物理系统一样,包括大地震震源在内的地震断裂系统,在临界点处涨落会自行扩大并对系统状态的突变起着举足轻重的作用.同时,要注意系统内部不可预测的行为,正确对待地震的预测和预报的含义.     

地震学中非线性预测方法的初步研究

介绍了近年来地震预测学中非线性理论和非线性方法的研究趋势和最新研究进展。在非线性数学模型的研究中，较为成功地将非线性门限模型，指数模型、具有长程关联自回归模型等应用于地震的中期预测上，在分形研究上，明确地取代了以往的一些经验结果，使对地震的活动的经验统计关系上升到分形的理论，在研究地震的动力学机制中，以多滑块－弹簧模型为代表，模拟地壳上地震断层运动机制和事实，建立了粘滑摩擦情况下的参数动力学方程。     

岩石微破裂进程的自组织临界特征探讨

运用RFPA2D作为研究手段对岩石在单轴压缩条件下破裂过程的自组织行为作了数值模拟,再现了岩石破裂过程中的应力积累(stress buildup)、应力转移(stress transference)和应力阴影(stress shadow)等“3S”现象,探讨了自组织临界特征,澄清了临界自组织现象等概念。研究结果表明,岩石破裂过程中的自组织行为是一个动态力学过程,并不一定只是在自组织临界状态点之后才发生,而是在临界状态点附近前后都能发生,只不过显现程度各有差异,临界状态点之后现象更为显著。     

Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains

A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.     

自组织竞争网络模型在地震预报研究中的应用

本文简述了自组织竞争模型的原理，研究了其在地震预报样本分类中的应用。并采用遗传算法对其网络结构参数进行优化，对输入样本参数进行优选。震例检验结果显示自组织竞争网络具有较好的分类效果，经遗传算法优化后的模型分类效果得到进一步改善。