最小割集在系统安全分析方法中的应用

利用事故树分析法对矿井火灾进行分析 ,结合平煤六矿建立了矿井火灾事故树。阐述了最小割集理论及其在事故分析中的作用 ,着重提出了对事故树底部事件进行排序分级的加权结构重要度分析法。该方法新颖、简洁而实用 ,为系统安全分析提供了新的方法和途径。     

地震火灾事例调查

本文介绍了世界上典型的几个地震火灾的例子,汇总了中外地震史上曾发生过的地震火灾,并且较详细地介绍了产生地震火灾的原因。     

ESTIMATING MEAN AND VARIANCE FOR ENVIRONMENTAL SAMPLES WITH BELOW DETECTION LIMIT OBSERVATIONS1

ABSTRACT: Left-censoring of data sets complicates subsequent statistical analyses. Generally, substitution or deletion methods provide poor estimates of the mean and variance of censored samples. These substitution and deletion methods include the use of values above the detection limit (DL) only, or substitution of 0, DL/2 or the DL for the below DL values during the calculation of mean and variance. A variety of statistical methods provides better estimators for different types of distributions and censoring. Maximum likelihood and order statistics methods compare favorably to the substitution or deletion methods. Selected statistical methods applicable to left-censoring of environmental data sets are reviewed with the purpose of demonstrating the use of these statistical methods for coping with Type I (and Type II) left-censoring of normally and log-normally distributed environmental data sets. A PC program (UNCENSOR) is presented that implements these statistical methods. Problems associated with data sets with multiple DLs are discussed relative to censoring methods for life and fatigue tests as recently applied to water quality data sets.     

COMPARING SOME METHODS OF ESTIMATING MEAN AREAL RAINFALL1

ABSTRACT: A comparison of 13 different methods of estimating mean areal rainfall was made on two areas in New Mexico, U.S.A., and one area in Great Britain. Daily, monthly and yearly rainfall data were utilized. All methods, in general, yielded comparable estimates, especially for yearly values. This suggested that a simpler method would be preferable for estimating mean areal rainfall in these areas.     

ASSESSMENT OF REMOTE SENSING INPUT TO HYDROLOGIC MODELS1

Remotely sensed variables such as land cover type and snow-cover extent can currently be used directly and effectively in a few specific hydrologic models. Regression models can also be developed using physiographic and snow-cover data to permit estimation of discharge characteristics over extended periods such as a season or year. Most models, however, are not of an appropriate design to readily accept as input the various types of remote sensing parameters that can be obtained now or in the future. Because this new technology has the potential for producing hydrologic data that has significant information content on an areal basis, both inexpensively and repetitively, effort should be devoted now to either modifying existing models or developing new models that can use these data. Minor modifications would at least allow the remote sensing data to be used in an ancillary way to update the model state variables, whereas major structural modifications or new models would permit direct input of the data through remote sensing compatible algorithms. Although current remote sensing inputs to hydrologic models employ only visible and near infrared data, model modification or development should accommodate microwave and thermal infrared data that will be more widely available in the future.     

水中全盐量的电导法测定

本文介绍了用电导法测定水样中全盐量的新方法，与经典的重量法相比，具有快速、简便、准确的优点。经对水样分析，结果令人满意     

Metal Concentrations, Foraging Distances, and Fledging Success of Great Blue Herons Nesting along the Hanford Reach of the Columbia River

An ecological risk assessment of the spatial distribution of metal concentrations along the Hanford Reach of the free-flowing Columbia River in southcentral Washington, identified great blue herons, Ardea herodias, at potential risk through the ingestion of contaminated riverine biota, especially fish. We measured metal concentrations in livers of pre-flight herons from the Hanford Reach and excrement samples taken from the same nests. Nests were distributed among three colonies situated upstream and downstream from nine retired plutonium production reactors along the river where metals in reactor coolant waters had been released directly into the river or disposed to shoreline retention basins and ditches. Distances traveled by parent herons to foraging areas along the river shore were determined by visually tracking parent birds as they flew from nests to upriver and downriver foraging sites. Foraging flight distances varied between colonies with mean distances ranging between 0.7 and 3.1 km. Cadmium, Cr, and Pb concentrations were higher in excrement than in the livers of pre-flight herons but the opposite was noted for Cu, Hg, and Zn. Highest metal concentrations of Cr, Cu, Zn, Cd, and Pb, were measured in excrement taken from heron nests at the colony located upstream from all reactors. These results were consistent with metal concentrations reported in river sediment from the same regions, indicating excrement from the heron nests may be a useful indicator of dietary uptake of metals by herons. Fledging success and eggshell thickness measurements were used as an index of health of the local heron population. The results indicate that the reproductive health of great blue herons nesting along the Hanford Reach is among the highest reported in the continental United States.     

Ozone Indicators Determined at Rural Sites in the Eastern United States by two Monitoring Networks

Ozone levels at Clean Air Status andTrends Network (CASTNet) and nearby rurally-designatedState and Local Air Monitoring Stations (SLAMS) siteslocated in the eastern United States (U.S.) arecompared using daily indicators (i.e., maximum, range,and SUM06) based on hourly O₃ measurements. Comparisons are also made using monthly and summertimethree-month SUM06 determinations aggregated from dailydata. Comparison of O₃ indicators at the pairedCASTNet-SLAMS sites generally shows better agreementfor O₃ maximum than for range or SUM06. Thehighest correlation of daily O₃ indicators occursfor paired sites that are separated by less than 100miles, and the correlation diminishes with increasingseparation distance. Correlation coefficients exceed0.70 in 49% of the comparisons of maximum, in23% of range comparisons and in 5% ofSUM06 comparisons, suggesting that substitution ofSLAMS for CASTNet O₃ measurements would fail tocapture a substantial amount of the variability inO₃ indicators present at the CASTNet sites. Correlations of O₃ indicators at CASTNet andpaired nearby SLAMS sites are 0.80 in a relativelysmall number of cases. Despite the high correlationin even these cases, O₃ behavior at paired sitesis not identical and shows systematic differences thatare reflected in the O₃ minimum, hourly averageconcentrations, and the monthly and three-month SUM06. Ozone measurements at nearby rurally-designated SLAMSsites may not capture the `rural' nature of the airquality being monitored at CASTNet sites and, in mostcases, may not be sufficiently representative of theconcentration at CASTNet sites to permit O₃measurements at SLAMS sites to be used in lieu ofmeasurements at CASTNet sites. As a result, if ruralO₃ concentration data are needed, then O₃monitoring at carefully chosen, rurally representativesites is recommended.     

从非典事件看政府的危机管理制度创新

传染性非典型肺炎一度在世界各地迅速蔓延,是对政府的危机管理制度一次前所未有的严峻考验。这次非典危机也暴露出了我国政府危机管理制度存在的缺陷。我们必须抓住这个契机,进行政府危机管理制度的创新,以不断提升政府的危机管理能力。     

区域高速公路网络构建对可达性空间格局的影响——以安徽沿江地区为实证 

以安徽沿江为实证，采用加权平均旅行时间指标，分析了高速公路网构建对节点区内联系及区外联系可达性格局的影响，并以此为基础，综合分析了节点总体可达性格局的变动；随后对总体可达性的变动幅度及其相对可达性变动格局进行了探讨。结果表明：安徽沿江高速公路网络的构建显著提高了区域整体可达性，且促进了可达性的均衡化；区内联系可达性、区外联系可达性及总体可达性三者格局特征不同，路网构建所形成的影响也各有差别；东部及北部地区可达性变动幅度小于西南部地区；根据可达性系数的变化幅度及方向，可将节点归为相对可达性下降、相对可达性稳定及相对可达性上升3类。