Mapping of radioactive contamination with predetermined confidence level

Standard approaches to the construction of maps of radioactive contamination do not provide errors in map data, so such maps do not, in fact, guarantee the accuracy of the map information. In this paper, based on the fact that the characteristics of radioactive contamination at a particular point in the territory have a lognormal probability distribution, a methodology for creating maps with a guaranteed confidence level of the provided information has been proposed and tested. There are considered two ways of creating maps, based on the results of "direct" measurements of radioactive contamination characteristics and in the combination of "direct" and "indirect" measurements of values statistically related to the mapping characteristic. The approaches and use of kriging methods proposed in the article allow to create maps with a given level of confidence and, accordingly, to take into account the risks caused by the uncertainty of measurements of radioactive contamination characteristics and uncertainty of their approximation.

Cartographing of "spots" of radioactive pollution

The methodology was proposed and the algorithm was developed for mapping and delineating the "spots" of radioactive contamination territory by the 137Cs. The methodology is based on the principle of multi-stage (successive approximations) widely used in geological surveys. Herewith, the 137Cs contamination density at each point is considered as a random variable with a lognormal probability distribution. The implementation of the algorithm is based on optimization of the number of sampling points necessary for estimating the density of soil contamination with a given relative error at the identification of a "spot" of contamination. The results of testing the algorithm confirmed the effectiveness and stability of its operation, as well as the simplicity of practical application. The proposed methodology makes it possible to substantially minimize the costs of field work for sampling soil and measuring the content of radionuclides in them.

Probabilistic estimation of glacier volume and glacier bed topography: the Andean glacier Huayna West

Glacier retreat will increase sea level and decrease fresh water availability. Glacier retreat will also induce morphologic and hydrologic changes due to the formation of glacial lakes. Hence, it is important not only to estimate glacier volume, but also to understand the spatial distribution of ice thickness. There are several approaches for estimating glacier volume and glacier thickness. However, it is not possible to select an optimal approach that works for all locations. It is important to analyse the relation between the different glacier volume estimations and to provide confidence intervals of a given solution. The present study presents a probabilistic approach for estimating glacier volume and its confidence interval. Glacier volume of the Andean glacier Huayna West was estimated according to different scaling relations. Besides, glacier volume and glacier thickness were estimated assuming plastic behaviour. The present study also analysed the influence of considering a variable glacier density due to ice firn densification. It was found that the different estimations are described by a lognormal probability distribution. Considering a confidence level of 90%, the estimated glacier volume is 0.0275 km3 ± 0.0052 km3. Considering a confidence level of 90%, the estimated glacier thickness is 24.98 m with a confidence of ±4.67 m. The mean basal shear stress considering plastic behaviour is 82.5 kPa. The reconstruction of glacier bed topography showed the future formation of a glacier lake with a maximum depth of 32 m.

A sheet erodibility parameter for water erosion modeling in regions with low intensity rain

Soil erodibility reflects the soil effect on the detachment process by rainfall and runoff; an evaluation of this parameter for single storm events was carried out using natural runoff plot data collected for two rainfall seasons in northern Iraq. The region is characterized by a semiarid Mediterranean-type climate with normal rainfall intensity below 20 mm/h and dominant sheet erosion on agricultural land. The plots were three 30 × 3 m and three 10 × 3 m, in fallow, situated on a 6% uniform slope; the soil at the site has a silty clay loam texture and belongs to the Calciorthid suborder. Sheet erosion rate was assumed linearly proportional to the storm power and the sheet flow power; a steady-state turbulent and kinematic sheet flow was also assumed. The results indicated a dominant detachment by rainfall with a substantial variability in storm by storm calculated sheet erodibility. The two-parameter lognormal probability distribution fitted the obtained sheet erodibility values reasonably well. Using this probability distribution, a representative sheet erodibility value of 0.056 × 10−3kg/J was obtained for use at the experimental site.

Human Response Is Lognormal; Plan on Waiting If You Want Reliability

Human response times fit a lognormal probability function, which poses severe constraints on the time a system designer must allow to accommodate a significant fraction of respondents; for example, 6 standard deviations for 95% confidence and 11 standard deviations for 99% confidence. When a human operates in series with machine elements, there may be no justification for demanding a quick response from the machine.