计算机安全技术

在当今信息时代，林业安全管理所需要的信息要实现网络化必须以计算机安全技术为基础。本文主要介绍了计算机安全技术所需要注意的一些问题，同时举例说明实现单机运行安全的几种方法。     

ECONOMIC COSTS AND BENEFITS OF INSTREAM FLOW PROTECTION FOR ENDANGERED SPECIES IN AN INTERNATIONAL BASIN1

ABSTRACT: The U.S. Endangered Species Act (ESA) restricts federal agencies from carrying out actions that jeopardize the continued existence of any endangered species. The U.S. Supreme Court has emphasized that the language of the ESA and its amendments permits few exceptions to the requirement to give endangered species the highest priority. This paper estimates economic costs associated with one measure for increasing instream flows to meet critical habitat requirements of the endangered Rio Grande silvery minnow. Impacts are derived from an integrated regional model of the hydrology, economics, and institutions of the upper Rio Grande Basin in Colorado, New Mexico, Texas, and Mexico. One proposal for providing minimum streamflows to protect the silvery minnow from extinction would provide guaranteed year round streamflows of at least 50 cubic feet per second in the San Acacia reach of the upper Rio Grande. These added flows can be accomplished through reduced surface diversions by New Mexico water users in dry years when flows would otherwise be reduced below the critical level required by the minnow. Based on a 44‐year simulation of future inflows to the basin, we find that some agricultural users suffer damages, but New Mexico water users as a whole do not incur damages from a policy that reduces stream depletions sufficiently to provide habitat for the minnow. The same policy actually benefits downstream users, producing average annual benefits of over $200,000 per year for west Texas agriculture, and over $1 million for El Paso municipal and industrial water users, respectively. Economic impacts of instream flow deliveries for the minnow are highest in drought years.     

泥石流输沙对小江中下游河床演变的影响

对小江中下游近90km河床及两岸泥石流进行了调查研究。得到：泥石流输沙年际和季节变化大；泥石流高强度的输沙造成小江河床特殊的平面和剖面特征；泥石流堵塞小江河道，对纵比降有再造作用；泥沙使小江河床以年均20cm～50cm速度抬升。     

黄河断流成因及人文思考

日益严峻的黄河断流现象严重地影响了黄河流域经济和社会的可持续发展，也制约了西部大开发战略的实施。在分析了黄河断流的危害、成因的基础上，提出了在工程措施之外，要从人口、法律制度、产业结构等人文因素方面入手缓解黄河断流。     

供水管线震害量化参数--渗漏面积的估算方法

为了分析管线破坏状态对震后供水管网功能的影响，首先需要对管线的震害状态进行量化。建议用管线渗漏面积标定管线的破坏状态。在管线震害分析和理论计算的基础上，提出了震后管线渗漏面积的计算方法，为进一步进行供水管网抗震分析和设计提供了研究基础。     

QUALITY OF HYDROMETEOROLOGICAL DATA IN COLD REGIONS1

ABSTRACT: Many users of hydrometeorological records are not aware of the number of inconsistencies and biases that occur in hydrometeorological records. Examples are presented illustrating how the exposures of sites for measurement of precipitation, wind, snow on the ground, and evaporation determine to a large extent how useful the records are for estimating areal conditions. For areas where precipitation in the form of snow produces a significant portion of the runoff, a smaller number of quality records may be more valuable for modeling than a much larger number of records of lower quality. Information is presented to show that the overall value of an operational hydrometeorological network is dependent upon how consistent and representative of average conditions the collected records are, especially for mountainous areas in cold regions.     

IMPACT OF COAL SURFACE MINING ON THREE OHIO WATERSHEDS - SURFACE-WATER HYDROLOGY1

ABSTRACT: A study was conducted to determine the effects of mining and reclaiming originally undisturbed watersheds on surface-water hydrology in three small experimental watersheds in Ohio. Approximately six years of data were collected at each site, with differing lengths of premining (Phase 1), mining and reclamation (Phase 2), and post-reclamation (Phase 3) periods. Mining and reclamation activities showed no consistent pattern iii base-flow, and caused slightly more frequent higher daily flow volumes. Phase 2 activities can cause reductions in seasonal variation in double mass curves compared with Phase 1. Restoration of seasonal variations was noticeably apparent at one site during Phase 3. The responses of the watersheds to rainfall intensities causing larger peak flow rates generally decreased due to mining and reclamation, but tended to exceed responses observed in Phase 1 during Phase 3. Natural Resources Conservation Service (NRCS) curve numbers increased due to mining and reclamation (Phase 2), ranging from 83 to 91. During Phase 3, curve numbers remained approximately constant from Phase 2, ranging from 87 to 91.     

神经网络及其在水库调洪演算中的应用

结合洪水灾害管理的特点建立了水库调洪演算的人工神经网络模型，阐述了其基本原理及算法，并结合某水库调洪演算实例说明了其应用。     

人为泥石流灾害严重等级的定量模糊综合评判

根据神府－东胜矿区人为泥石流的调查分析，选择１５个因素（含５个主控因素）作为其严重程度的评价因子，确定了四值逻辑（严、中、轻、否）评判的定量标准。应用模糊综合评判和分层定量模糊综合评判两种方法对该煤田６５条泥石流沟的严重等级进行综合判别，准确性达９３．１％，它为保护该地煤田建设和工农业生产提供了重要的科学依据。     

建筑火灾区域模拟竖孔流动的计算

本文根据建筑火灾双层区域模拟思想，给出其常微分控制方程组，并分析了其压力求解方法，然后，运用伯努力利方程推导了相邻房间通过矩形竖孔（门或窗）的质量流率计算公式，还讨论了竖孔流动中性面产生条件。在此基础上，结合一两房间、两孔建筑中烟气运动实例，运用Ｃ．Ｗ．Ｇｅａｒ刚性稳定算法对火灾发展及烟气流动过程进行了数值模拟；给出各竖孔中性面位置、数量和各主环境之间通过竖孔的质量流率；还给出各房间气体平均温升、