一种提高飞行器结构天地力学环境地面试验有效性的方法及其应用

目的研究提高飞行器结构地面试验有效性的途径。方法计算同一被试件结构在飞行状态和地面试验状态下的有限元模型,测量地面试验状态下的模态以验证有限元模型的正确性;计算各特征点(也可以是遥测点)在天地状态下的响应,用机器学习法获取各特征点的映射关系模型;基于该模型由飞行点响应(或遥测数据)确定出地面试验件对应点的响应,并用载荷反求法得到它们的等效载荷;最终确定施加在试验系统上的载荷。结果以细长体结构为例,所得到由其组成试验系统的有限元模型与实测模型之间的固有频率最大相对误差为6.76%,利用映射关系模型预测出对应点在飞行状态下的振动响应。确定了飞行状态下结构响应的特征点,由地面试验系统所对应的响应点反推出应施加的载荷为60 N。结论利用天地数值计算-地面试验验证联合法,无需在地面试验状态下刻意模拟飞行状态的边界条件,确定出所需要施加的载荷,从而提高了飞行器地面试验的有效性。     

Modeling freshwater fish distributions using multiscale landscape data: A case study of six narrow range endemics

Species distribution models (SDMs) have become integral tools in scientific research and conservation planning. Despite progress in the assessment of various statistical models for use in SDMs, little has been done in way of evaluating appropriate ecological models. In this paper, we evaluate the multiscale filter framework as a suitable theoretical model for predicting freshwater fish distributions in the upper Green River system (Ohio River drainage), USA. The spatial distributions of six fishes with contrasting biogeographies were modeled using boosted regression trees and multiscale landscape data. Species biogeography did not appear to affect predictive performance and all models performed well statistically with receiver operating characteristic area under the curve (AUC) ranging from 0.87 to 0.98. Predictive maps show accurate estimations of ranges for five of six species based on historical collections. The relative influence of each type of environmental feature and spatial scale varied markedly with between species. A hierarchical effect was detected for narrowly distributed species. These species were highly influenced by soil composition at larger spatial scales and land use/land cover (LULC) patterns at more proximal scales. Conversely, LULC pattern was the most influential feature for widely distributed at all spatial scales. Using multiscale data capable of capturing hierarchical landscape influences allowed production of accurate predictive models and provided further insight into factors controlling freshwater fish distributions.     

A statistical evaluation of the geogenic controls on indoor radon concentrations and radon risk

ANOVA is used to show that approximately 25% of the total variation of indoor radon concentrations in England and Wales can be explained by the mapped bedrock and superficial geology. The proportion of the total variation explained by geology is higher (up to 37%) in areas where there is strong contrast between the radon potential of sedimentary geological units and lower (14%) where the influence of confounding geological controls, such as uranium mineralisation, cut across mapped geological boundaries. When indoor radon measurements are grouped by geology and 1-km squares of the national grid, the cumulative percentage of the variation between and within mapped geological units is shown to be 34-40%. The proportion of the variation that can be attributed to mapped geological units increases with the level of detail of the digital geological data. This study confirms the importance of radon maps that show the variation of indoor radon concentrations both between and within mapped geological boundaries.     

Relevance for decision making of spatially explicit,participatory scenarios for ecosystem services in an area of a high current demand

Participatory ecosystem services scenarios can be used to inform decision making on the sustainable or wise use of biodiversity and ecosystem services (ES). To establish the plausibility and coherency of the recently constructed Biscay participatory scenarios, and to analyze policy options for improving sustainability of land use and the supply of ecosystem services, a spatially explicit analysis of land cover change was carried out. The modelling used an innovative methodology which included feedback from key stakeholders. Our study showed that scenario mapping can be a way of testing the credibility and internal consistency of scenarios, and a methodology for making them more coherent; it was also useful for highlighting land use trade-offs. The sustainability analysis for the ES supply side showed the benefits of promoting two land use/cover trends in the Biscay region: (i) an increase of sustainable arable land in the valley zones to reinforce biocapacity and self-provisioning while preserving agroecosystems’ ES flow; and (ii) natural forest regeneration in mountainous and other zones to increase carbon storage and sequestration while enhancing biodiversity and other ES flows. We argue that even if already protected public agro-forest lands may be the best places to start promoting these changes, additional measures are needed to involve private landowners and guarantee changes at a landscape level. Finally, we reflect on the need to make complementary analyses of ES supply and demand as a way of contributing to a broad sustainability agenda.     

Negotiating Indigenous knowledge at the science-policy interface: Insights from the Xáxli’p Community Forest

Despite increasing interest in learning from Indigenous communities, efforts to involve Indigenous knowledge in environmental policy-making are often fraught with contestations over knowledge, values, and interests. Using the co-production of knowledge and social order (Jasanoff, 2004), this case study seeks to understand how some Indigenous communities are engaging in science-policy negotiations by linking traditional ecological knowledge (TEK), western science, and other knowledge systems. The analysis follows twenty years of Indigenous forest management negotiations between the Xáxli’p community and the Ministry of Forests in British Columbia (B.C.), Canada, which resulted in the Xáxli’p Community Forest (XCF). The XCF is an eco-cultural restoration initiative that established an exclusive forest tenure for Xáxli’p over the majority of their aboriginal territory—a political shift that was co-produced with new articulations of Xáxli’p knowledge. This research seeks to understand knowledge co-production with Indigenous communities, and suggests that existing knowledge integration concepts are insufficient to address ongoing challenges with power asymmetries and Indigenous knowledge. Rather, this work proposes interpreting XCF knowledge production strategies through the framework of “Indigenous articulations,” where Indigenous peoples self-determine representations of their identities and interests in a contemporary socio-political context. This work has broader implications for considering how Indigenous knowledge is shaping science-policy negotiations, and vice versa.     

环境中氡的水平及其对人体危害

氡是致人体天然辐射剂量贡献最大的核素,也是肺癌发病的重要因子,是净化空气要优先考虑的问题。为此,本文报告了环境氡的水平以及它对人体产生的危害,这些知识对净化环境,保护健康有重要意义     

FLOODPLAIN DELINEATION: AN ECONOMIC APPROACH1

ABSTRACT: Errors inherent in the conputation of water surface profiles are magnified by the shallow lateral slopes typical of most flood-plains, producing significant floodplain mapping errors. An economic optimization procedure which weighs the cost of overstating the location of a floodplain boundary against the cost of understanding the location provides a means for establishing the boundary location. In most cases the cost of overstating the boundary location exceeds the cost of understating the location by several magnitudes so that the boundary location should coincide with the minimum water surface elevation which would be expected to result from a flood of specified recurrence interval.     

PROCEDURE FOR SELECTING A MINIMAL ENVIRONMENTAL IMPACT ROUTING FOR A WATER CONVEYANCE CANAL1

ABSTRACT: Several techniques for selecting a least environmental impact corridor have been proposed. Two approaches have been found workable; the computer graphics and the map overlay. This report combines features of both to determine an appropriate routing for a water conveyance canal. The study was conducted by an interdisciplinary planning team. Environmental factors were mapped and weighted on overlay maps. Alternative routes were identified and carefully studied. Several critical environmental implications were noted. Aesthetic factors, out door recreation interpretation, visitor safety and disruption of human and animal travel routes were considered and dealt with.     

Use of a geographic information system for storm runoff prediction from small urban watersheds

The use of computer-assisted map analysis techniques for prediction of storm runoff from a small urban watershed in the United States is investigated. An automated procedure for calculating input parameters for the US Soil Conservation Service (SCS) method of predicting storm runoff volume and peak timing is presented. Advanced techniques of spatial analysis are used to characterize spatial coincidence, surface configuration and effective hydrologic distance. A limited verification of the automated procedure indicates that the model reasonably characterizes water flow. A sensitivity analysis of basin disaggregation suggests that the SCS method yields increased volume and peak discharge predictions as the watershed is divided into smaller and smaller subunits. As a means to demonstrate the practical application of the automated procedure, a simulation of the effects on surface runoff for a potential residential development is presented.     

谱系填图法及其在苏州花岗岩区调中的实施效果

花岗岩类谱系填图法的指导思想,是从解体大岩基入手,建立同源岩浆演化的等级体制及其与岩石地层单位的对应关系,逐步实现按地质构造背景划分花岗岩的区划.该方法在苏州西部地区的区调工作中获得了较好的成效.从丰富多姿的侵入接触关系,建立了该区花岗岩的谱系,论证了主体花岗岩的产状是向北缓倾的岩席,进而,探讨了控岩构造和侵位机制.阐述了花岗岩与矿产的时空关系,并用热力驱动成矿说(HHP理论)解释了苏州各类高岭土矿的成因.