太湖水污染扩散插件式模拟系统

插件式太湖水污染扩散模拟系统,基于三维水体污染扩散模型,结合GIS技术和三维可视化技术,再现了水体污染物运移扩散的时空分布特征与动态演进过程.为了保证系统的可扩展性,需要一种松散的耦合机制.插件技术可以有效地降低系统功能模块间的耦合,把插件技术引入GIS的二次开发可以赋予系统动态可扩展性.本文首先,介绍插件式系统的一般...     

盘锦湿地芦苇叶片气孔导度的模拟

基于2005年5～9月盘锦湿地芦苇叶片气体交换观测数据,针对芦苇叶片气孔导度与光合速率以及光合速率与光合有效辐射之间的关系进行分析。结果表明:芦苇叶片气孔导度与光合速率的关系可应用Ball-Berry模型描述,光合速率与光合有效辐射的关系可应用非直角双曲线光合模型描述,联合Ball-Berry模型与非直角双曲线光合模型可通过环境变量求解叶片气孔导度。模型考虑了气孔导度与光合之间的相互作用。利用实验数据对气孔导度模型验证表明,叶片气孔导度模拟值和观测值回归方程的斜率为0.95,方程决定系数R=0.82(P<0.05)。     

LUTI模型的概念结构、实现方法及发展趋势

回顾了LUTI模型概念、起源和发展过程,对模型的一般架构和实现技术方法进行了系统的总结分析,在此基础上讨论了LUTI模型发展所面临的问题与挑战。研究发现,作为模拟城市空间发展过程常用的数学模型,LUTI模型是基于城市土地利用-交通相互作用规律,从社会经济活动空间分布的角度模拟城市空间演化过程。根据LUTI模型,城市空间演化过程是土地利用系统和交通系统不断的相互作用过程,其中交通模型根据城市活动空间分布及交通设施评价城市交通状况,而土地利用模型根据交通可达性和其他影响因素预测城市空间发展趋势;城市发展过程中城市活动空间分布在交通的作用下发生改变后,将改变城市房租、交通状况等因素,进而再次导致城市活动空间分布随之变化,如此不断相互作用、趋于平衡。LUTI在国外被广泛用于城市空间政策检验、辅助决策。就LUTI模型的发展而言,已有研究更多地侧重要解决的现实问题,而对模型的理论结构关注较少,导致模型的发展滞后于城市的发展。应用中面临的诸多问题要求LUTI模型理论上的进一步突破。将LUTI的工作原理植入城市研究的背景中,旨在让读者对LUTI模型原理、结构、实现技术及面临的问题有深入了解,推进LUTI模型在中国应用与发展。     

逾渗与岩石破裂的计算机模拟研究

用计算机模拟方法研究了岩石破裂的逾渗模型，给出了在微裂隙随机分布情况下破裂集团的分布图象、破裂集团的大小分布规律、总破裂集团数、集团平均大小、ｂ值、逾渗分维Ｄ及临界情形。所得结果与其他模型和实验基本一致，表明通渗模型是描述岩石破裂扩展演化过程的一种较合适的模型。还发现了岩石破裂过程存在的两个转折点，深入研究这两个转折点附近岩石的宏观性质，可为探索地震孕育演化过程的前兆性质提供依据。     

极冰对南方涛动的影响

分析南、北极冰量与南方涛动序列作月、季和年尺度的变化过程线性相关关系，发现北极冰量与南方涛动指数是反相关关系，而南极冰量与南方涛动是正相关。比较而言，南极冰量与南方涛动的关系在月和季尺度上似乎较北极与大气的关系密切些。在各时间尺度序列中以太平洋地区南极极冰的影响表现最明显。分析发现极冰与南方涛动之间存在较复杂的非线性关系。在前期极冰的强信号寻找中，发现极冰与南方涛动在月序列的相关关系上存在周期变化现象。进一步选择相关极值的对应步长建立前期极冰状态激发大气变化的预测统计动力模式，模式对大气序列的解释方差可达０．９０以上。文中还进一步探讨了月序列存在的周期变化的共同因素的影响     

Effect of lithology and structure on seismic response of steep slope in a shaking table test

Studies on landslides by the 2008 Wenchuan earthquake showed that topography was of great importance in amplifying the seismic shaking, and among other factors, lithology and slope structure controlled the spatial occurrence of slope failures. The present study carried out experiments on four rock slopes with steep angle of 60° by means of a shaking table. The recorded Wenchuan earthquake waves were scaled to excite the model slopes. Measurements from accelerometers installed on free surface of the model slope were analyzed, with much effort on timedomain acceleration responses to horizontal components of seismic shaking. It was found that the amplification factor of peak horizontal acceleration, RPHA, was increasing with elevation of each model slope, though the upper and lower halves of the slope exhibited different increasing patterns. As excitation intensity was increased, the drastic deterioration of the inner structure of each slope caused the sudden increase of RPHA in the upper slope part. In addition, the model simulating the soft rock slope produced the larger RPHA than the model simulating the hard rock slope by a maximum factor of 2.6. The layered model slope also produced the larger RPHA than the homogeneous model slope by a maximum factor of 2.7. The upper half of a slope was influenced more seriously by the effect of lithology, while the lower half was influenced more seriously by the effect of slope structure.     

A Comparison of Conventional and Shear-Rate Dependent Mohr-Coulomb Models for Simulating Landslides

Landslides may cause many fatalities and heavy economic losses,so it is vital to understand their mechanics so as to take appropriate measures to mitigate their risk.Phenomenally,the loose soil behaves like frictional material in most circumstances,so Mohr-Coulomb type equations are often used to describe their movement.However,these models generally do not consider the influence of the shearrate on the Mohr-Coulomb friction angle,so the shear-rate dependence effect on the soil flow and landslide runout is not well understood.This paper reports on an application of the incompressible Smoothed Particle Hydrodynamics（SPH） method to the dynamics of dry granular assemblies.The traditional model with a constant friction angle is compared with the modified Mohr-Coulomb model with a variable friction angle related to the shear-rate.It is found that the shear-rate dependence effect is negligible for shallow granular flows along mild slopes.With steeper slopes of the ground and larger aspect ratios of the initial soil column,the rate-dependence effect becomes more important.     

The distribution and variability of simulated chlorophyll concentration over the tropical Indian Ocean from five CMIP5 models

Performances of 5 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating the chlorophyll concentration over the tropical Indian Ocean are evaluated. Results show that these models are able to capture the dominant spatial distribution of observed chlorophyll concentration and reproduce the maximum chlorophyll concentration over the western part of the Arabian Sea, around the tip of the Indian subcontinent, and in the southeast tropical Indian Ocean. The seasonal evolution of chlorophyll concentration over these regions is also reproduced with significant amplitude diversity among models. All of 5 models is able to simulate the interannual variability of chlorophyll concentration. The maximum interannual variation occurs at the same regions where the maximum climatological chlorophyll concentration is located. Further analysis also reveals that the Indian Ocean Dipole events have great impact on chlorophyll concentration in the tropical Indian Ocean. In the general successful simulation of chlorophyll concentration, most of the CMIP5 models present higher than normal chlorophyll concentration in the eastern equatorial Indian Ocean.     

金属矿地震勘探物理模拟实验技术

在金属矿地震勘探的物理模拟中,实验技术研究是得到可靠实验结果的重要保证.通过控制环氧基混合材料混合比的实验,形成1 600～3 200m/s的速度差异,实现了对复杂岩性的模拟.在对山地模型的采集中,采用触点控制方式实现了高程测量和数据采集同步进行.采用页面模型模拟技术,实现了对复杂模型地震波总场信号的分解和归位.