运用改进的D-S进行钢管焊接结构损伤识别

为了有效利用结构健康诊断中的多源不确定数据,提高损伤识别的准确率,通过改进D-S证据理论(Dempster提出由Shafer完善形成的一种推理理论)中的基本概率赋值函数和组合规则,提出了一种基于改进D-S证据理论的结构损伤识别新方法.该方法利用灰色关联理论和熵权理论处理信息源的基本概率赋值问题,利用改进的D-S组合规则处理信息源间的相关、冲突问题.通过钢管焊接结构的试验研究验证所提方法的有效性,结果表明所提出的方法优于传统的D-S损伤识别方法;相对于单一损伤信息的损伤识别而言,基于多源损伤信息能够有效降低损伤误判的可能性,获得更准确的损伤识别结果.     

基于D-S证据理论的黄土滑坡参数估计及应用

岩土参数的不确定性存在,降低了稳定性评价的可靠性,对工程安全、优化设计等方面有重要影响。而D-S证据理论提供了一种解决不确定信息的有效方法,证据理论能够对各自独立的证据加以综合给出一致性结果,并能处理具有模糊和不确定信息的合成问题,可以达到信息互补。适应各领域的人工智能和系统决策、诊断、评估等实际问题和理论基础。结合实际黄土滑坡的滑带土力学参数试验结果,基于D-S证据理论,构造了滑带土力学参数的识别框架、基本可信度分配,从主观和客观上对滑带土力学参数取值进行信度估计,滑坡滑带土力学参数信度估计值与滑带土强度参数反分析结果相吻合,表明基于D-S证据理论的黄土滑坡参数估计的有效性和可行性。     

基于D-S证据理论的黄土滑坡参数估计及应用

岩土参数的不确定性存在,降低了稳定性评价的可靠性,对工程安全、优化设计等方面有重要影响。而D-S证据理论提供了一种解决不确定信息的有效方法,证据理论能够对各自独立的证据加以综合给出一致性结果,并能处理具有模糊和不确定信息的合成问题,可以达到信息互补。适应各领域的人工智能和系统决策、诊断、评估等实际问题和理论基础。结合实际黄土滑坡的滑带土力学参数试验结果,基于D-S证据理论,构造了滑带土力学参数的识别框架、基本可信度分配,从主观和客观上对滑带土力学参数取值进行信度估计,滑坡滑带土力学参数信度估计值与滑带土强度参数反分析结果相吻合,表明基于D-S证据理论的黄土滑坡参数估计的有效性和可行性。     

基于D-S证据理论的地震多属性融合方法在煤层气富集区预测中的应用(英文)

D-S证据理论为融合不确定信息提供了一条很好的思路。本文提出将D-S证据理论用于地震多属性融合的方法,首先在钻孔实测煤层气含量值的指导下优选对煤层气含量值变化敏感的地震属性,然后基于D-S证据理论对优选的地震属性进行融合处理,并将融合结果用于煤层气富集区的预测。实际应用效果表明:预测结果与钻孔实测煤层气含量值基本吻合,本文提出的基于D-S证据理论的地震多属性融合方法用于预测煤层气富集区是可行的。     

地震预测的信度方法

概率论与数理统计一直是地震预测中处理不确定性的主要方法，但这一方法也有其局限性。为此我们引进了一种新的不确定性处理方法——证据理论的信度方法。此前，该方法在地震预测中的应用还未见报道。本文首先介绍了信任函数及其在地震预测中的应用方法，包括问题表达和信息综合两个方面，并提出了加权的D—S规则。然后简单讨论了联合信任函数的定义和计算公式，并通过与概率方法的比较，说明了这一方法在地震预测中的应用价值。研究结果表明，利用信度方法处理地震预测中的不确定性问题有其独特的优点。     

关于地震预报研究问题的一些思考

针对地震预报研究的有关问题，提出在继续推进地震短临预报科学研究的同时，应重视并加强长期地震预测研究工作，并将其作为地震预报的一个组成部分；调整地震预报科研课题的组织形式，加强对区域性，地区性地震预报方法，前兆机理及其理论模式的探索研究；加密重点监视防御区的地震台网及前兆观测台点，淘汰低效能的前兆观测手段或台项；努力提高地震预报队伍的素质，培养和造就高级预报人材。     

中强地震前地震拟合优度的异常特征及在地震预报中的应用

引用地震拟合优度r值，对华北地区18次中强地震前地震拟合优度r值与地震活动的关系进行了分析和研究，总结出了中强地震前地震拟合优度r值的异常特征，并把该方法应用到了河南及其邻区的中等地震预报中，制定了预报规则，进行了预测内符检验和预报评分。结果表明，该方法是一种有效的中期地震预报方法，尤其对弱震区中等地震的预报具有推广应用价值。     

地震学界近期提出的地震预报理论和方法

近期，地震学家对地震预报理论和监测预报方法从不同的角度进行了探索，取得了新进展，本文对外电、外刊报道的地震预报理论和预报方法作了介绍。     

VAN地震预报的统计检验：评述和思考

参与争论的文章表明，是否不同类型的地震都应被认为是成功预报的正确考虑是统计检验ＶＡＮ地震预报方法的关键问题之一，其他问题涉及ＶＡＮ预报是否曾经反推调整规则以拟合数据，如何检验ＶＡＮ预报的意义以及拒绝该零假设的依据，这一问题的观点不同，说明地震学界需要一套评估地震预报方法的基本方案。     

地震预报专家系统ESEP 3.0中的知识表示方法

知识表示是专家系统建造中的一个关键环节，知识表示方法的好坏直接关系到系统的智能水平和解决问题的能力。在地震预报专家系统ESEP3．0中有多种知识表示方法，本文介绍了该系统的结构知识、地震学和前兆预报知识、机器学习知识、综合预报知识、确定异常证据可信度知识以及支持知识等多种知识表示方法，提出了确定异常证据可信度模型。这些知识表示方法可以很好地表示各类地震预报知识。     

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.