国外生态阈值研究进展及启示

生态阈值是促使生态系统属性发生突变的环境变量的值,20世纪70年代以来在国外生态学界掀起研究热潮.通过详细总结国外生态阈值研究内容、研究方法与成果实践应用状况,反映出生态阈值研究对于理解生态系统转变过程、制定生态标准以及实施环境管理决策具有重要支撑意义;强调生态阈值研究应以正确把握时间和空间尺度、理解系统要素相互作用机制及阈值检测数学模型的生态学意义为前提;由于背景干扰和人为压力增加了物种及其生态系统的敏感性,迄今只有少量的带有阈值的标准和制度尝试性应用于国外资源环境管理实践领域.结合当前国内生态环境管理标准制定的科技支撑需求,建议谨慎将国内外阈值研究成果应用于国内管理实践,同时针对国内重点地区突出的生态环境问题开展生态阈值研究,以夯实"三线一单"资源环境管理制度科学基石,提升生态学研究实践应用价值.      

核-壳型纳米双金属微粒的研究进展

纳米材料以其独特的性质，在光学、化工、环保、陶瓷、生物和医药等诸多方面具有广泛的应用价值。而纳米金属材料的表面包覆和修饰是21世纪纳米材料科学的一个新的研究方向。文中比较系统地综述了核-壳型纳米双金属微粒制备方法的研究进展，包括还原化学镀法、共沉淀法等，简要分析了各类制备方法的基本原理、特点及适用的范围，并在此基础上讨论了核-壳型纳米双金属粉末的未来研究发展方向。     

趋势面拟合法在煤矿瓦斯地质变量预测中的应用研究

从瓦斯地质学的观点出发,将反映煤层瓦斯基本参数的空间变化规律看做是与其赋存地质条件密切相关的连续函数。结合趋势面拟合及其模型优化的原理和方法分析得出了淮北矿业集团公司芦岭煤矿井田范围内瓦斯含量的变化及分布与其位置坐标的对应数值关系,依据该数值关系可对矿井深部采场和未开采区域实施比较准确、可靠的定量瓦斯预测。该方法也适用于其他具有相似特征的瓦斯地质变量分析。     

21世纪西部发展旅游业的资源观

丰富独特的自然景观和浓郁多彩的人文风情是西部地区发展旅游业的强大基础，但它们不能直接决定旅游业的发展水平。只有把旅游资源开发成旅游者需要的旅游产品，才能实现旅游资源的价值，发展西部旅游业。旅游产品的开发能力构成旅游地的核心竞争能力，西部只有提高旅游产品的开发能力，才能适应旅游市场的变化，不断开拓新的市场，促进旅游业水平的提高。在对西部旅游资源进行综合利用和深度开发的同时，还要注重资源的保护，进行“绿色开发”和“绿色经营”，实现资源的可持续利用。     

Diagnostic variables as predictors of ecological risk

The state of an ecosystem may be represented by a multidemensional state vector,x. The goal of ecosystem management is to insure that the ecosystem remains within some setX of acceptable states, such thatx X. Since ecosystem management decisions must be based on limited knowledge, a small number of diagnostic variables must be found which accurately reflect ecosystem state. If the vector of diagnostic variables, , is found to be within a specified set , the state vectorx is predicted to be withinX. The selection and use of such diagnostic variables is examined in the context of an aquatic ecosystem simulation model. Techniques used in searching for diagnostic criteria include multiple linear regression, discriminant analysis, and visual inspection of graphical data displays. The adequacy of a diagnostic criterion as a predictor of ecological risk is demonstrated to be a function of the associated rates of type I and type II statistical errors. A simple cost-benefit analysis is undertaken to illustrate one approach for choosing an optimal balance between these error rates.     

GOES IR AND DUMMY VARIABLE TECHNIQUES FOR LOW TEMPERATURE ASSESSMENT IN FLORIDA1

ABSTRACT: Geostationary Operational Environmental Satellite (GOES) thermal infrared (IR) data were used to study regional cold nocturnal temperature fluctuations that are important in assessing citrus freeze damage. Dummy variables techniques were used to analyze the temperature difference between the east and west sides of Central Florida, which was obtained from both ground measurement minimum temperature (T_GMM) and the GOES mean temperature (T_GOES) on low-temperature nights. The low temperature pattern, which was closely related to the citrus freeze damage pattern in Central Florida, was identified by GOES thermal IR data but not by conventional ground measurements. The low surface temperature in the west side and east side appears to be attributable to differences in soil types, water tables, and drainage classes in both regions.     

MEASUREMENT OF ENVIRONMENTAL TRADE-OFFS AND PUBLIC POLICY: A CASE STUDY1

ABSTRACT: The search for an adequate methodology to quantify environmental trade-offs led to a simulation technique, the Priority Evaluator Technique (PET). The PET was applied to determine values and trade-off preferences for environmental variables related to a proposed reservoir project. The PET simulates real world situations and allows the respondents to evaluate their preferences within a fixed cost framework. It systematically checks the respondents's perception of the existing conditions and compares the changes sought. From the responses obtained via interviewing, one can establish the extent to which respondents are satisfied with the prevailing conditions, the magnitude and direction of changes sought, the quality trade-offs, and the relative value of different situations. The PET is flexible and can accommodate alternative planning decisions, prices, incomes, and end factors. The promise shown by this application of the PET should encourage further exploration and evaluation.     

火灾时人员疏散开始时间范围的研究

火灾中人员疏散的开始时间是一个受多方面因素影响的随机量。现行的火灾数值模拟计算中常将它处理成一常量，显然与实际不符。该项研究采用统计理论的正态分布函数，建立了一个随机数学模型，研究火灾中人员疏散开始时间的范围，结合实例数据，似合出一通用公式实现定量研究。     

测震数字化观测系统前台机维护的研究

随着地震台站数字化和计算机网络技术的使用，对地震台数字化系统的维护提出了更高的要求。而数字化观测系统前台机的正常与否是整个数字化的核心，前台机的安全和维护工作的成败直接影响数字资料的质量和产出。本文针对在实际工作中所遇到的各种问题，结合地震台的实际情况，归纳和总结了一些方法和见解，提出一些切合实际的解决方法，希望对兄弟台站测震数字化系统的维护有所帮助。     

地下水环境评价中分布参数随机性的空间统计分析

地下水环境评价中各种空间分布参数往往具有复杂的不确定性，对分布参数空间变化的二重性特征进行了分析，论述了空间分布参数统计分析的原理与方法。由于所采用的方法能够弥经典概率统计方法对地下水环境评从价中空间分布参数随机性分析的不足。