Evolution of pore structure and hydraulic conductivity of randomly distributed soluble particle mixture

The plane strain behavior of particulate mixtures containing soluble particles was investigated by conducting both laboratory tests and numerical analysis. To perform the laboratory experiments, soluble mixtures were prepared using photoelastic disks and ice disks with diameters in the ratios (D_{ice disk}/D_{photoelastic disk}) of 0.5 and 0.7, and the evolution of the force chain and pore structure was monitored during the dissolution of the ice disks. Subsequently, numerical analysis was conducted by using the 2‐dimensional discrete element method for the soluble mixtures, and it was compared with the experimental results. Additionally, parametric studies were implemented by varying the particle size ratios between the soluble and non‐soluble particles and the volumetric fraction of the soluble particles. The results of the laboratory experiments and numerical analysis demonstrate that (1) after the dissolution of the soluble particles, the pore fabric of the specimens changed, resulting in a force chain changes, local void increases, and coordination number decreases; (2) the effects of soluble particles on the macro‐behaviors of the mixtures could be divided into 3 zones based on the particle size ratios between the soluble and non‐soluble particles and volumetric fraction of soluble particles. These zones were as follows: (Zone 1)—with a small total soluble volume, slight decrease in the in situ lateral pressure (K₀), and minor increase in the hydraulic conductivity (k); (Zone 2)—with a moderate soluble particle; the dissolution generated a honey‐comb particle structure; (Zone 3)—the total soluble volume was very large, and the high volumetric fraction of the dissolving particle collapsed the pore structure, decreasing in the in situ lateral pressure (K₀) but increasing the hydraulic conductivity (k). The horizontal stress returned to almost the original level, and the internal arching formation increased significantly with the hydraulic conductivity (k).     

基于稀少控制点的SPOT5卫星立体条带影像的生产应用研究

随着相关技术的发展,高分辨率卫星遥感影像在测绘产品生产中的应用越来越广泛和深入。本文主要通过西部无图区测图的应用实践,讨论利用有理多项式方法、基于稀少控制点纠正的SPOT5HRS立体条带影像的测图生产情况,并对DLG、DEM等产品进行精度检测;同时与传统的航摄方法进行对比,分析其生产效率等情况。     

单侧控制条件下SPOT5 HRG影像的定向试验

高分辨率卫星影像已经成为获取地理信息的重要数据源,而其定向是一项关键技术。本文利用单侧不同数量及分布的控制点对SPOT5 HRG影像进行了定向试验,探讨了在单侧控制条件下SPOT5 HRG影像的定向精度情况,为地面控制点获取较困难地区的影像定向提供了一条参考途径。     

格点同化对大气波导数值模拟的影响

利用NCEP再分析资料为背景场及常规的探空资料和地面资料,以2005年6月2日出现在黄海海域的大气波导为例,运用中尺度数值模式MM5,设计了2种初始场不同的数值模拟试验:1)NCEP资料;2)NCEP资料和常规探空资料。研究结果表明:格点同化能够改善大气波导的MM5数值模拟结果,提高MM5的大气波导参数模拟精度;在大气波导分布上,格点同化对陆地大气波导影响较大,对于海上的模拟区域分布几乎没有影响。     

Tidal estuary width convergence: Theory and form in North Australian estuaries

In order to better understand the relations between tidal estuary shape and geomorphic processes, the width profiles of 79 tidal channels from within 30 estuaries in northern Australia have been extracted from LANDSAT 5 imagery using GIS. Statistics describing the shape and width convergence of individual channels and entire estuaries (which can contain several channels) are analysed along with proxies for the tidal range and fluvial inputs of the estuaries in question. The width profiles of most individual channels can be reasonably approximated with an exponential curve, and this is also true of the width profiles of estuaries. However, the shape of this exponential width profile is strongly related to the mouth width of the system. Channels and estuaries with larger mouths generally exhibit a more pronounced ‘funnel shape’ than those with narrower mouths, reflecting the hydrodynamic importance of the distance over which the channel or estuarine width converges. At the estuarine scale, this ‘convergence length’ also tends to be higher in estuaries which have larger catchments relative to their size. No clear relation between the estuarine width convergence length and tidal range could be discerned within the Northern Australian estuaries although, when these data are combined with data from other studies, a weak relationship emerges. Copyright © 2010 John Wiley & Sons, Ltd.     

2008年汶川8.0级地震地表位移场的模拟——映秀-北川断裂逆冲兼右旋走滑错动形成的地表位移场

基于Yoshimitsu Okada及Steketee的断裂位错模型,从理论上反演了汶川地震时龙门山中央主断裂中段附近区域(距离断裂30km)内由断裂逆冲兼右旋错动形成的地表位移场的空间演化,包括地表垂直和水平位移场的基本特征。模拟表明了断裂错动过程中近断裂区域地表位移场的空间演化情况,而该空间演化情况通过野外科考和有限的GPS测站数据是无法细致描述的。文中将模拟结果与野外地表破裂带的科考成果进行比较,发现两者在变化趋势上近似表现一致;且位移场在离开断裂出露处迅速衰减的特征与现有研究成果一致;同时模拟结果也表明位移场的衰减速度在下盘强于上盘。模拟结果最终表明:断裂错动形成的地表垂直位移存在较大的空间不均匀性且较大的幅值主要集中于断裂的两端,即映秀和北川附近,垂直和水平位移场在断裂端部的变化都强于断裂的中部;地表垂直位移沿走向的变化在断裂上盘强于下盘;水平位移除了在断裂两端变化比较剧烈外,在空间上分布比较均匀;总体上,除断裂端部外位移场的幅值在上盘大于下盘。     

地震应急现场无线通信设备与现场有线网络环境集成通信方案探讨

通过对汶川8.0级地震现场工作的经验总结,提出在保障"十五"期间配备的地震应急现场技术系统可用的前提下,扩展地震应急现场设备的使用范围,对地震应急现场无线通信设备与现场有线网络环境集成通信方案进行测试和探讨,以便在复杂的现场环境下多一种通信方式选择。     

Statistical Optimization of Anaerobic Biological Processes for Dye Treatment

In the present study both the synthetic media composition as well as some process parameters in the anaerobic decolorization of Reactive Black 5 (RB5) by activated sludge were studied and optimized using statistical design of experiments (DOEs). Statistical analysis of the results of Plackett–Burman DOE showed that the addition of Mn or Fe, or increase in concentration of Mg, had a positive effect on the anaerobic decolorization efficiency whereas the effect of increase in concentration of glucose, ammonium chloride, and calcium chloride was negative. The effect of change in the concentration of glucose, mixed liquor suspended solid (MLSS), and RB5 on the anaerobic decolorization efficiency and rate and chemical oxygen demand (COD) removal was studied using central composite design methodology. Statistical analysis of the data showed that all the factors had significant effect on both the dye decolorization efficiency and rate. The interaction of glucose with MLSS and with dye and the interaction of MLSS with glucose and with dye were significant when the response was decolorization efficiency and rate, respectively. When COD removal was the response, the effect of change in glucose and MLSS concentration and the interaction between these two factors had statistically significant effect on the response.     

The response of annual runoff to the height change of the summertime 0℃ level over Xinjiang

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960–2002, the variance of the summertime 0℃ level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0℃ level height in Xinjiang correlates well with that of the annual river runoff, especially since the early 1990s, but it differs from region to region, with both the average height of the 0℃ level and runoff quantity significantly increasing over time in the Altay- Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0℃ level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0℃ level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.