基于GIS的祁连山生态敏感性评价

以遥感数据为基础数据源研究祁连山的生态环境特点和主要生态问题,并结合客观条件及评价因子的选取需具有代表性、可计量性的原则,选取气候舒适度指数、土地沙化指数、土地盐碱化指数、水土流失指数和生物多样性指数共5项评价因子对祁连山生态敏感性进行综合评价。运用GIS技术在单因子评价的基础上,再利用空间叠加分析功能和重分类工具进行多因子综合评价,划分5类生态敏感等级,由大到小依次为高敏感性、较高敏感性、中等敏感性、较低敏感性和低敏感性。结果表明,祁连山生态敏感性空间分异明显,高敏感性地区主要分布在祁连山西部地区,低敏感性地区主要分布在东部地区。生态敏感性总体都处于中等偏低的水平上,其中,中等以下的地区占研究区总面积的69.7 8%,高敏感性、较高敏感性占研究区的30.2 2%,表明对于祁连山的生态保护还是卓有成效的,但一些地区还存在不少问题,导致生态敏感性偏高。因此,未来对于祁连山生态环境保护任务依然艰巨,对于高敏感性区域的西部地区应该进行严格保护和生态治理,对于低敏感性区域的东部地区要持续加强生态保护,减少人为活动影响。     

Validity and consistency assessment of accident analysis methods in the petroleum industry

Background. Accident analysis is the main aspect of accident investigation. It includes the method of connecting different causes in a procedural way. Therefore, it is important to use valid and reliable methods for the investigation of different causal factors of accidents, especially the noteworthy ones. Objective. This study aimed to prominently assess the accuracy (sensitivity index [SI]) and consistency of the six most commonly used accident analysis methods in the petroleum industry. Methods. In order to evaluate the methods of accident analysis, two real case studies (process safety and personal accident) from the petroleum industry were analyzed by 10 assessors. The accuracy and consistency of these methods were then evaluated. The assessors were trained in the workshop of accident analysis methods. Results. The systematic cause analysis technique and bowtie methods gained the greatest SI scores for both personal and process safety accidents, respectively. The best average results of the consistency in a single method (based on 10 independent assessors) were in the region of 70%. Conclusion. This study confirmed that the application of methods with pre-defined causes and a logic tree could enhance the sensitivity and consistency of accident analysis.     

基于直觉模糊集的城市供水安全预警评价模型

为了更好地评价城市供水安全预警的等级,基于直觉模糊集理论,建立城市供水安全预警评价模型。模型选取12个评价指标构成属性集,预警等级划分标准构成评价等级集,再将二者转换为直觉模糊数,以此构成直觉模糊决策矩阵,并综合主、客观权重的优势得到组合权重,以此计算样本综合值,最后分析指标权重变化对于评价结果影响的灵敏度。实例计算结果表明:基于直觉模糊集的城市供水安全预警评价与可拓物元分析法的结果总体接近,2006—2009年供水安全预警等级处于重警或中警等级,2009年以后预警等级降低并基本稳定在无警这一等级。不同指标的敏感性分析有助于提高权重的准确性。     

基于F-R-M法的刚构-连续梁桥施工期结构强度风险分析

为了解决刚构-连续梁桥施工过程中的风险问题,提出了一种神经网络与有限元结合的定量风险分析方法（F-R-M法）。以八盘峡黄河特大桥为工程背景建立有限元模型,运用参数敏感性分析确定出最不利施工阶段的结构强度主要风险随机变量,然后以蒙特卡洛原理为基础,通过径向基（RBF）神经网络计算结构失效概率,最后对桥梁施工风险进行定量分析。结果表明:该桥在最大悬臂状态下,结构应力仿真次数超过 1 000 万次时,梁体在最大悬臂端应力失效概率仅约为 1.17×10-5,失效概率极低。基于参数敏感性的F-R-M法可以快速、较高精度地对高速铁路刚构-连续梁桥施工期结构强度风险进行定量分析。     

凝聚炸药的冲击起爆

分析了飞片在炸药内产生高压区的行为，导出高压区中热点发生热爆炸的临界条件；讨论了高压区中侧向能量分配对热点传播的影响，得到了适应性更加广泛的凝聚炸药冲击起爆判据；利用这一判据，对实验结果给予了理论解释。     

CHEMICAL COMPOSITION OF SOFTWATER FLORIDA LAKES AND THEIR SENSITIVITY TO ACID PRECIPITATION1

ABSTRACT: Based on alkalinity data for 596 lakes, 31 percent of Florida's 7300 lakes have < 100 μeq/l alkalinity and are sensitive to acid depostion. More than two-thirds of the lakes in 12 northern Florida counties fit this criterion. Increasing aluminum and decreasing nutrient and chlorophyll a concentrations were observed with decressing pH in a survery of 20 softwater lakes. Maximum measured aluminum values (100-150 μg/L) are below levels asociated with fish toxicity. Factor analysis showed that lake chemistry was related to three principal factors, representing three major processes: watershed weathering, acidification, and nutrient inputs. An acidification index defined as the difference between excess SO₄^2- and excess (Ca²⁺+Mg²⁺) accounted for 74 percent of the variance in lake pH. Comparison of historical (late 1950a) and present data for pH, alkalinity, and excess SO₄^2- indicated loss of alkalinity (>25 μeq/L) and increase in excess SO₄^2- (16-34 μeq/L) in several softwater lakes.     

EVALUATION OF ALTERNATIVES TO THE GARRISON DIVERSION UNIT1

ABSTRACT: The Garrison Diversion Unit is a multipurpose water resources project which is currently under development for the purpose of diverting water from the Missouri River basin to irrigate farmland in North Dakota. Due to the objections raised by various interest groups, the project has recently been reviewed by the International Joint Commission. This article surveys the background to the project and the various alternatives that have been proposed. By utilizing recently developed fuzzy set techniques, the proposed alternatives are evaluated and a plausible solution is proposed. The results of the study indicate that it may be advisable to remove the Souris Loop irrigation area from the Garrison project but the environmental impacts of the study may preclude the implementation of any alternative that can affect Canada. These findings are in partial agreement with the recommendations of the International Joint Commission.     

环境污染与植物病害

本文讨论了环境污染物与植物病害的某些已知关系。污染物可以直接或通过作用于寄主植物影响病原接种体及其侵入后的扩展,影响植物体表微生物群落,改变各类有害生物的资源竞争格局,从而改变双方寄生关系的建立和发展模式,对发病率和严重度产生影响。而且,病害对植物生理状况的改变还将影响植株对污染物伤害的敏感性。污染物的这些作用都是依赖于特定植物病原组合的。     

Sources of variability in plant toxicity testing

Published literature is investigated regarding the response of plants to various substances to determine the sensitivity of agricultural plants versus other species, the similarity of effects seen at different taxonomic levels, sensitivity of plants growing outdoors versus in a greenhouse, and the sensitivity of different measurement endpoints. We find that agricultural species are not consistently more or less sensitive to the herbicides tested than non-crop species. Genus and family taxonomic groupings may show similar responses among species, but this similarity quickly decreases as the comparison progress between orders and classes. Results from field and greenhouse studies are less in agreement between studies than data from the other topics. Shoot length will be affected at concentrations lower than for other vegetative endpoints for most species tested for inorganic substances, but for organic substances root and shoot mass were more sensitive. Overall, there is no one species or endpoint that is consistently the most sensitive for all species or all chemicals in all soils, and differences in bioavailability among compounds may confound comparison of test results. Therefore, species sensitivity distributions, adjusted for bioavailability when possible, should be considered in order to better evaluate effects to non-target terrestrial plants.     

The toxicity of copper, cadmium and zinc to four different Hydra (Cnidaria: Hydrozoa)

An acute toxicity study of three metals to Hydra species carried out using two different assessment methods, (i) determination of the LC50 and (ii) measurement of progressive morphological changes, demonstrated that relative toxicity decreased from copper to cadmium with zinc the least toxic for all species. The latter method revealed more details of the effect on Hydra in terms of physical damage to the polyp but both methods indicated that H. viridissima was more sensitive to copper and cadmium than H. vulgaris¹ (Zurich strain, male clone), H. vulgaris² (a dioecious strain reproducing sexually and asexually) and H. oligactis (dioecious, reproducing sexually and asexually). The responses to zinc were similar for all Hydra. The possible role of metabolic interactions between H. viridissima and its symbiotic green algae in contributing to the greater sensitivity of this polyp is discussed.