一种用于海底类型聚类的新方法

By using sonar imaging, this paper presents a new algorithm for the clustering of seabed types based on the self-organizing feature maps （SOFM） neural network. The theory as well as data processing is studied in detail. Some valuable conclusions and suggestions are given     

Influence of heterogeneity on unsaturated hydraulic properties: (1) local heterogeneity and scale effect

Spatial heterogeneity is ubiquitous in nature, which may significantly affect the soil hydraulic property curves. The models of a closed‐form functional relationship of soil hydraulic property curves (e.g. VG model or exponential model) are valid at point or local scale based on a point‐scale hydrological process, but how do scale effects of heterogeneity have an influence on the parameters of these models when the models are used in a larger scale process? This paper uses a two‐dimensional variably saturated flow and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil flume under a constant head boundary condition. By changing different numerical simulation block sizes, a quantitative evaluation of parameter variations in the VG model, resulting from the scale effects, is presented. Results show that the parameters of soil hydraulic properties are independent of scale in homogeneous media. Parameters of α and n in homogeneous media, which are estimated by using the unsaturated hydraulic conductivity curve (UHC) or the soil water retention curve (WRC), are identical. Variations of local heterogeneities strongly affect the soil hydraulic properties, and the scale affects the results of the parameter estimations when numerical experiments are conducted. Furthermore, the discrepancy of each curve becomes considerable when moisture content becomes closer to a dry situation. Parameters estimated by UHC are totally different from the ones estimated by WRC. Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluation of the effect of river style framework on water quality: application of geomorphological factors

The Tarwal River basin with an area of 6560.20 km² is located in the eastern part of Iranian Kurdistan Province. This river crosses the Qorveh and Dehgolan plains and joins the Ghezel Ozan River in Zanjan Province. The importance of this river as a source for drinking water and agricultural and industrial uses in the region necessitates the need for research in this field. The main purpose of this study is to identify the natural features of the riverbed from the perspective of river geomorphology and to investigate their impact on water quality and river self-purification capacity. To achieve this, the river style framework was employed. To investigate the effects of each style framework on the river, a total of 20 samples from the entrance and outlet of styles were obtained using Impact Assessment method and sampling standards which were later analyzed for their quality parameters including T, pH, EC, TDS, TSS, Na, Ca, Mg, K, Cl, F, NO₂, NO₃, SO₄, PO₄, DO, COD and BOD. The results indicated that the changes in the styles lead to changes in water quality and the impact of each style is greater on the physical parameters than the chemical parameters. The river self-purification capacity varied depending on the style. The maximum and the minimum self-purifications occurred in fine-grained Anabranching and low-sinuosity fine-grained styles, respectively.     

中国西北内陆盆地水分垂直循环及其生态学意义

中国西北内陆盆地中的地下水系统,对维系其浅表水分、热量、盐分均衡以及地表的生态平衡、土壤的资源属性和局部地域气候相对稳定性具有不可或缺的调节作用,这种调节作用是通过饱和带水、包气带水(土壤水)、近地表大汽水和植物体内水("四水")之间的垂直循环来实现的.目前的相关研究主要侧重于地下水与地表植被类型间对应关系的统计分析,较少涉及水分运移的机制;而以水分垂直循环的动力学机制为研究对象的SPAC系统(土壤-植物-大气连续体),则对地下水的重视程度不够,且存在着尺度转换的困难,更为完整的应该是GSPAC系统(地下水-土壤-植物-大气连续体).干旱区内陆盆地地下水生态效应的研究需要开展以下的工作:"四水"垂直循环的动力学过程与机制研究,尤其是饱水带-包气带界面水、汽、热转化过程的研究;人类活动影响下地下水系统演化特征的研究,它不仅是实现水分垂直循环研究的最终目的——水资源合理开发利用的中间环节,更是将"四水"垂直循环这一微观水文循环过程与区域水文循环过程相结合,实现尺度转化的关键所在.     

Study of Influence of Regional Geodynamic Background on Strata Behaviors in China's Tongxin Mine

Strata behaviors are mainly affected by regional geodynamic background. The influence of rock mass stress and energy distribution on strata behaviors in the Tongxin mine is studied in terms of regional tectonic movement, seismic activity and tectonic stress field. The results show that the extrusion lifting movement of Kouquan fault adjacent to the Tongxin mine results in the stress concentration in the rock of the Carboniferous coal bed and accumulation of a large amount of elastic energy and forms structural background of Tongxin mine. Due to various seismic activities in the mine area, the strain energy is known to reach much higher levels, up to 0.5×10⁸ J^1/2. Since the stratigraphic structure is sensitive to the mining operation, the strain energy could cause strong strata behaviors. A special geological structure model of the Tongxin mine is established based on the geodynamic division method. The distribution of regional structure stress field is determined by the rock mass stress analysis system. Based on this model, Tongxin mine is divided into five areas with high stress, eight areas with low stress and eight areas with gradient stress. The strong strata behaviors mostly occur in high stress areas. These results could provide guidance to predict the strength of regional or mine pressure and control strata behavior in different areas.     

Output-only identification of the modal and physical properties of structures using free vibration response

The viability of a complete structural characterization of civil structures is explored and discussed. In particular, the identification of modal (i.e. natural frequencies, damping ratios and modal shapes) and physical properties (i.e. mass and stiffness) using only the structure’s free decay response is studied. To accomplish this, modal analysis from free vibration response only (MAFVRO) and mass modification (MM) methodologies are engaged along with Wavelet based techniques for optimal signal processing and modal reconstruction. The methodologies are evaluated using simulated and experimental data. The simulated data are extracted from a simple elastic model of a 5 story shear building and from a more realistic nonlinear model of a RC frame structure. The experimental data are gathered from shake table test of a 2-story scaled shear building. Guidelines for the reconstruction procedure from the data are proposed as the quality of the identified properties is shown to be governed by adequate selection of the frequency bands and optimal modal shape reconstruction. Moreover, in cases where the structure has undergone damage, the proposed identification scheme can also be applied for preliminary assessment of structural health.     

A contrast of two typical LUCC processes and their driving forces in oases of arid areas: A case study of Sangong River Watershed at the northern foot of Tianshan Mountains

Aerial photographs taken in 1978 and 1987, Landsat TM images in 1998 as well as soil, hydrology and socio-economic data for the oases in Sangong River Watershed were processed by Remote Sensing (RS) and Geographic Information System (GIS). There are two typical agricultural land uses in oases, Farm-based Land Use with large-scale intensified agricultural activities (FLU) and Household Responsibility-based Land Use with small-scale activities (HRLU). The Index Model of Land Use/Land Cover Change (LUCC), Weighted Index Sum (WIS) and logistic stepwise regression model were established to contrast the two typical LUCC processes and their driving forces. The land use patterns were dominated by cropland and grassland for the entire region, and cropland, residential and industrial land were increasing stably. In the HRLU areas, woodland and grassland declined dramatically, but in the FLU areas, grassland decreased only by 12.0%, whereas woodland increased by 13.7%. LUCC was stronger in the earlier stage (1978–1987) than in the later stage (1987–1998) for the entire region. LUCC was more intense in the HRLU areas than in the FLU areas during the entire period (1978–1998). Policy was a key factor in the land use change, and water resources were a precondition in land use. Under the control of policy and water resources, the main human driving factors included population and economy, and the main natural restrictions were soil fertility and groundwater depth. Human driving factors controlled the land change in the HRLU areas, but natural restriction factors dominated in the FLU areas. In the mean time, intensification of LUCC in the region had some spatiotemporal implications with a fluctuation of impact factors.     

Engagement in the Third U.S. National Climate Assessment: commitment,capacity, and communication for impact

This paper examines the dynamics of energy investments and clean energy Research and Development (R&D) using a scenario-based modeling approach. Starting from the global scenarios proposed in the RoSE model ensemble experiment, we analyze the dynamics of investments under different assumptions regarding economic and population growth as well as availability of fossil fuel resources, in the absence of a climate policy. Our analysis indicates that economic growth and the speed of income convergence across countries matters for improvements in energy efficiency, both via dedicated R&D investments but mostly through capital-energy substitution. In contrast, fossil fuel prices, by changing the relative competitiveness of energy sources, create an economic opportunity for radical innovation in the energy sector. Indeed, our results suggest that fossil fuel availability is the key driver of investments in low carbon energy innovation. However, this innovation, by itself, is not sufficient to induce emission reductions compatible with climate stabilization objectives.     

南秦岭金龙山微细浸染型金矿成矿时代

 金龙山金矿带是南秦岭新发现的卡林型金矿带,主要产于上泥盆统南羊山组细碎屑岩—碳酸盐岩建造中,在上泥盆统冷水河组、下石炭统碳酸盐建造中也有产出,可分为明显受断裂控制的脉型金矿化和受有利岩性及小规模断裂、节理控制的浸染型矿化。