土木工程结构鲁棒控制的发展

评述了结构控制的发展,指出发展结构鲁棒控制策略的重要性。重点评述了结构双重调谐质量阻尼器(DTMD)和多重双重调谐质量阻尼器(MDTMD)的控制策略,提出了需进一步发展主动双重调谐质量阻尼器(ADTMD)和主动多重双重调谐质量阻尼器(AMDTMD)控制策略、此外,评述了结构鲁棒控制的设计准则与高层建筑和大跨桥梁在风与地震作用下的统一自适应主动鲁棒控制策略。     

尺度理论视角下的“一带一路”战略解读

目前,“一带一路”已成为中国的核心发展战略之一。借鉴尺度重构和尺度政治理论,分析“一带一路”战略的内涵、影响和风险。研究发现“一带一路”战略重构了现有的国家角色和地域形式,催生了以跨国基础设施为基础、以资本和经贸合作为支撑的新尺度。该尺度一方面被国际和国内的资本和权力关系不断重构,另一方面也在重构着现有的权力关系和资本积累过程。还从尺度政治视角出发探讨了“一带一路”战略中的风险因素。在国际层面,中国既面临着基于多边国际关系和地方抵抗的尺度上推力量,也面临着基于旧有边界和尺度化表达的尺度下推因素。在国内,“一带一路”战略既面临着地方政府基于政策争夺和地方保护主义产生的重复建设问题,也存在疆独势力等通过国际联系复杂化地方趋势的风险。为了更好地推行“一带一路”战略,中国必须积极应对这些尺度政治的挑战,深入研究尺度政治的机制和破解之道,努力化解海外投资、国际合作和地方治理中的风险。     

Factors driving riverbed scouring and sedimentation in the Bayangaole to Toudaoguai reaches of the Upper Yellow River

The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole (Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10⁸ m³, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient < 0.007 kg·s·m^–6 and a flow discharge > 700 m³·s^–1. The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m³·s^–1 and a comprehensive incoming sediment coefficient < 0.005 kg·s·m^–6. The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10⁸ t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most.     

Natural background levels and threshold values for groundwater in fluvial Pleistocene and Tertiary marine aquifers in Flanders,Belgium

Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve, and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed. This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL) for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers, high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial anthropogenic inputs of these parameters.     

地球化学样品中硒的循序提取技术

研究开发了一种硒的循序偏提取步骤，将地球化学样品中的硒选择性地循序提取到六个“操作上”定义的相态中：水溶性硒（水提取）；吸附在氧化矿物和粘土矿物上配位可交换的亚硒酸根离子（０．１ｍｏｌ／ＬＫＨ２ＰＯ４提取）；与有机质结合的硒（０．１ｍｏｌ／ＬＮａ４Ｐ２Ｏ７提取）；与铁锰铝氧化物和碳酸盐结合的硒（４．０ｍｏｌ／ＬＨＣｌ提取）；硫化物中的硒（ＫＣｌＯ３＋浓ＨＣｌ提取）；硅酸盐残渣中以副矿物和被硅质包裹的硒微粒存在的硒（ＨＦ＋ＨＮＯ３＋ＨＣｌＯ４强混合酸溶解）。对提取步骤的可行性和实用性作了详细的讨论。     

利用高光谱对生物变量进行估计

该文分析了非光合背景物质—土壤光谱信号的特点 ,认为利用对光谱信号进行一阶导数的运算就能对混合光谱中的土壤光谱信号进行压缩 ,由此而得到的生物指数如LAI、SApar等的估计值更能客观地反映实际 ,这对于利用成象光谱进行环境应用有很大的实用价值。     

The role of dynamic transport in the formation of the inverted charge structure in a simulated hailstorm

The inverted charge structure formation of a hailstorm was investigated using the Advanced Weather Research and Forecasting(WRF-ARW) model coupled with electrification and discharge schemes. Different processes may be responsible for inverted charge structure in different storms and regions. A dynamical-derived mechanism of inverted charge structure formation was confirmed by the numerical model: the inverted structure was formed by strong updraft and downdraft under normal-polarity charging conditions such that the graupel charged negatively in the main charging region in the middle-upper level of the cloud. The simulation results showed the storm presented a normal charge structure before and after hail-fall; while during the hail-fall stage, it showed an inverted charge structure—negative charge region in the upper level of the cloud and a positive charge region in the middle level of the cloud—appearing at the front edge near the strong updraft in the hailstorm. The charging processes between the two particles mainly occurred at the top of the cloud, where the graupel charged negatively and ice crystals positively due to the strong updraft. When the updraft air reached the top of the storm, it would spread to the rear and front. The light ice crystals were transported backward and forward more easily. Meanwhile, the positively charged ice crystals were transported downward by the frontal subsidence, and then a positive charge region formed between the ?10 and ?25°C levels. Subsequently, a negative charge region materialized in the upper level of the cloud, and the inverted charge structure formed.     

New classes of spectral densities for lattice processes and random fields built from simple univariate margins

Quasi arithmetic and Archimedean functionals are used to build new classes of spectral densities for processes defined on any d-dimensional lattice \mathbbZ^d{\mathbb{Z}^d} and random fields defined on the d-dimensional Euclidean space \mathbbR^d{\mathbb{R}^d}, given simple margins. We discuss the mathematical features of the proposed constructions, and show rigorously as well as through examples, that these new classes of spectra generalize celebrated classes introduced in the literature. Additionally, we obtain permissible spectral densities as linear combinations of quasi arithmetic or Archimedean functionals, whose associated correlation functions may attain negative values or oscillate between positive and negative ones. We finally show that these new classes of spectral densities can be used for nonseparable processes that are not necessarily diagonally symmetric.     

From global to local: Testing the potential of cross-scaling in global data sets

The present study investigates the potential of readily available and easily accessible global data sets to understand regional/local level interactions in wetland systems. The biogeographical zones of India were used a base-frame to select three sites. The study well fits the interests of National Wetland Committee of India to investigate and document fundamental information on wetland extent/distribution. The national partnership with SACON represents this interest. SACON commenced the inland wetland inventory module at national scale using geospatial data, although the provincial scale analysis is underway. In addition, the global irrigated area mapping (GIAM-IWMI) project generated multi-scalar spatial outputs for irrigated/rain-fed areas. With the existing information base, a multi-level geospatial analysis using Arc GIS algorithmic modelling was used to derive comprehensive appraisal of wetland systems complementing the data from GIAM and SACON. It was observed that the overlap between the two layers was 58 percent for Gujarat and 10 percent in Tamil Nadu. In Krishna basin the wetland’s cover 1.04 million hectare excluding the rice agro-ecosystem. The difference in the biogeography of the case sites governs the gradient of information derived from both data layers. Additionally, the global lakes and wetlands database (GLWD) database added thematic information on coastal wetlands. In summary we describe the cross-scaling the global data layers to compliment the regional/national level monitoring assignments.