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1.
Benzion Barlev 《Geoforum》1974,5(3):37-44
Empirical investigations have demonstrated that the location effects of business taxation and of inter-area tax differentials are not of major importance. This paper attempts to explain the above results by showing that the uncertainty involved in predicting future tax rates and tax differentials nullifies their location effects. It is then shown, both theoretically as well as empirically, that reducing the uncertainty of future tax benefits has a significant effect on industrial location patterns. 相似文献
2.
基于多元地学大数据的三维成矿预测方法是开展深部找矿预测的新方法和新手段,也是当前成矿预测领域的研究热点之一。然而,大数据具有高维、混杂、非精确等特点,其分析处理过程面临多重不确定性。多元地学大数据整合是三维成矿预测的最终环节,其存在的不确定性将直接作用于预测结果,影响进一步的找矿应用和风险评估。本文以宁芜盆地钟姑矿田为例,从大数据思维出发,定量分析和度量预测要素和数学模型在数据整合过程中存在的不确定性及对三维成矿预测结果的影响。结果显示,断裂构造、背斜轴部等预测要素的不确定性对三维成矿预测结果的影响最为强烈;数据整合模型中,较之Logistic回归模型和证据权重模型,神经网络模型可能具有更高的不确定性程度。进一步工作可通过增强上述预测要素的可靠性和有效性、采用更多的数据整合模型进行更为全面的不确定性分析和评价,以获得更为可靠的三维成矿预测成果,从而降低成矿预测和找矿勘探风险。 相似文献
3.
Sustainable management of groundwater resources is vital for development of areas at risk from water-resource over-exploitation. In northeast Thailand, the Phu Thok aquifer is an important water source, particularly in the Thaphra area, where increased groundwater withdrawals may result in water-level decline and saline-water upconing. Three-dimensional finite-difference flow models were developed with MODFLOW to predict the impacts of future pumping on hydraulic heads. Four scenarios of pumping and recharge were defined to evaluate the system response to future usage and climate conditions. Primary model simulations show that groundwater heads will continue to decrease by 4–12?m by the year 2040 at the center of the highly exploited area, under conditions of both increasing pumping and drought. To quantify predictive uncertainty in these estimates, in addition to the primary conceptual model, three alternative conceptual models were used in the simulation of sustainable yields. These alternative models show that, for this case study, a reasonable degree of uncertainty in hydrostratigraphic interpretation is more impactful than uncertainty in recharge distribution or boundary conditions. The uncertainty-analysis results strongly support addressing conceptual-model uncertainty in the practice of groundwater-management modeling. Doing so will better assist decision makers in selecting and implementing robust sustainable strategies. 相似文献
4.
The effectiveness of aquifer remediation is typically expressed in terms of a reduction in contaminant concentrations relative
to a regulated maximum contaminant level (MCL), and is usually confirmed by sparse monitoring data and/or simple model calculations.
Here, the effectiveness of remediation is re-examined from a more thorough risk-based perspective that goes beyond the traditional
MCL concept. A methodology is employed to evaluate the health risk to individuals exposed to contaminated household water
that is produced from groundwater. This approach explicitly accounts for differences in risk arising from variability in individual
physiology and water use, the uncertainty in estimating chemical carcinogenesis for different individuals, and the uncertainties
and variability in contaminant concentrations within groundwater as affected by transport through heterogeneous geologic media.
A hypothetical contamination scenario is developed as a case study in a saturated, alluvial aquifer underlying an actual Superfund
site. A baseline (unremediated) human exposure and health risk scenario, as induced by contaminated groundwater pumped from
this site, is predicted and compared with a similar estimate based upon pump-and-treat exposure intervention. The predicted
reduction in risk in the remediation scenario is not an equitable one—that is, it is not uniform to all individuals within
a population and varies according to the level of uncertainty in prediction. The importance of understanding the detailed
hydrogeologic connections that are established in the heterogeneous geologic regime between the contaminated source, municipal
receptors, and remediation wells, and its relationship to this uncertainty is demonstrated. Using two alternative pumping
rates, we develop cost-benefit curves based upon reduced exposure and risk to different individuals within the population,
under the presence of uncertainty. 相似文献
5.
遥感数据专题分类不确定性评价研究：进展、问题与展望 总被引：7，自引：1，他引：7
从遥感数据中提取专题类别信息是当前遥感数据最主要的应用领域之一。由于遥感分类专题信息广泛应用于各种领域，其数据质量受到越来越多的关注。不确定性是评价分类专题类别数据质量最主要的方面。回顾了遥感数据专题分类不确定性评价方法的历史，总结了当前各种评价方法及其指标体系，将这些方法归结为基于误差矩阵的方法、模糊评价方法、像元尺度上的不确定性评价方法和其它方法四大类。对每一类不确定性评价方法及其指标体系的优点和缺点进行了分析和总结，指出从理论方法研究方面，需要优先发展独立于分类方法的像元尺度上的遥感分类不确定性评价模型与指标体系，以及统一的遥感数据分类不确定性评价模型体系研究；在应用研究方面，需要加强优化空间采样设计和不确定性评价过程标准化研究。 相似文献
6.
Pinnaduwa H. S. W. Kulatilake Jinyong Park Pirahas Balasingam Sean A. Mckenna 《Geotechnical and Geological Engineering》2007,25(1):79-102
A 1 km square regular grid system created on the Universal Transverse Mercator zone 54 projected coordinate system is used
to work with volcanism related data for Sengan region. The following geologic variables were determined as the most important
for identifying volcanism: geothermal gradient, groundwater temperature, heat discharge, groundwater pH value, presence of
volcanic rocks and presence of hydrothermal alteration. Data available for each of these important geologic variables were
used to perform directional variogram modeling and kriging to estimate geologic variable vectors at each of the 23949 centers
of the chosen 1 km cell grid system. Cluster analysis was performed on the 23949 complete variable vectors to classify each
center of 1 km cell into one of five different statistically homogeneous groups with respect to potential volcanism spanning
from lowest possible volcanism to highest possible volcanism with increasing group number. A discriminant analysis incorporating
Bayes’ theorem was performed to construct maps showing the probability of group membership for each of the volcanism groups.
The said maps showed good comparisons with the recorded locations of volcanism within the Sengan region. No volcanic data
were found to exist in the group 1 region. The high probability areas within group 1 have the chance of being the no volcanism
region. Entropy of classification is calculated to assess the uncertainty of the allocation process of each 1 km cell center
location based on the calculated probabilities. The recorded volcanism data are also plotted on the entropy map to examine
the uncertainty level of the estimations at the locations where volcanism exists. The volcanic data cell locations that are
in the high volcanism regions (groups 4 and 5) showed relatively low mapping estimation uncertainty. On the other hand, the
volcanic data cell locations that are in the low volcanism region (group 2) showed relatively high mapping estimation uncertainty.
The volcanic data cell locations that are in the medium volcanism region (group 3) showed relatively moderate mapping estimation
uncertainty. Areas of high uncertainty provide locations where additional site characterization resources can be spent most
effectively. The new data collected can be added to the existing database to perform future regionalized mapping and reduce
the uncertainty level of the existing estimations. 相似文献
7.
Effect of uncertainty in land use, damage models and inundation depth on flood damage estimates 总被引：8，自引：2，他引：6
With the recent transition to a more risk-based approach in flood management, flood risk models—being a key component in flood
risk management—are becoming increasingly important. Such models combine information from four components: (1) the flood hazard
(mostly inundation depth), (2) the exposure (e.g. land use), (3) the value of elements at risk and (4) the susceptibility
of the elements at risk to hydrologic conditions (e.g. depth–damage curves). All these components contain, however, a certain
degree of uncertainty which propagates through the calculation and accumulates in the final damage estimate. In this study,
an effort has been made to assess the influence of uncertainty in these four components on the final damage estimate. Different
land-use data sets and damage models have been used to represent the uncertainties in the exposure, value and susceptibility
components. For the flood hazard component, inundation depth has been varied systematically to estimate the sensitivity of
flood damage estimations to this component. The results indicate that, assuming the uncertainty in inundation depth is about
25 cm (about 15% of the mean inundation depth), the total uncertainty surrounding the final damage estimate in the case study
area can amount to a factor 5–6. The value of elements at risk and depth–damage curves are the most important sources of uncertainty
in flood damage estimates and can both introduce about a factor 2 of uncertainty in the final damage estimates. Very large
uncertainties in inundation depth would be necessary to have a similar effect on the uncertainty of the final damage estimate,
which seem highly unrealistic. Hence, in order to reduce the uncertainties surrounding potential flood damage estimates, these
components deserve prioritisation in future flood damage research. While absolute estimates of flood damage exhibit considerable
uncertainty (the above-mentioned factor 5–6), estimates for proportional changes in flood damages (defined as the change in
flood damages as a percentage of a base situation) are much more robust. 相似文献
8.
《Chemical Geology》2006,225(1-2):1-15
Microprobe monazite dating has been increasingly used to constrain the timing of deformation and metamorphism because of the potential to date very small monazite domains (down to 5 μm or less) in structural and petrologic context. This paper presents an analytical strategy, presentation format, and error considerations for microprobe monazite dating. The strategy involves high-resolution compositional mapping to delineate compositional domains within monazite crystals. Then for each compositional domain, a series of Th, U and Pb analyses are made, and a single date and error are calculated. The number of analyses in each domain is determined by the desired statistical precision of the date. Results from several monazite grains are typically combined and, along with textural relationships, are used to build an argument that the dates constrain the age of a deformation or metamorphic event. The total error involves three components: short-term random error (dominated by counting statistical uncertainty), short-term systematic error (uncertainty in background correction, conductive coating variation, and calibration), and long-term systematic error (uncertainty in standard composition, mass absorption factors, decay constants, etc.). In homogeneous compositional domains, short-term random errors (2σ) of less than 10 m.y. can be obtained from five to ten analyses. However, short-term systematic error, mainly background estimation uncertainty, would typically result in a doubling of the magnitude of random error. Microprobe dates are presented as a single Gaussian probability distribution for each domain, along with representative compositional maps. It is recommended that a consistency standard be analyzed during each analytical session and the results be reported along with those from the unknown. This proposed strategy and format are compatible with those of other geochronological techniques; they incorporate analytical limitations associated with trace, as opposed to major element, microprobe analysis, and will allow better comparisons to be made between labs and between different geochronological techniques. 相似文献
9.
Albina I. Kuznetsova Olga V. Zarubina Olga A. Sklyarova 《Geostandards and Geoanalytical Research》2007,31(3):251-259
Reference samples of soils from the Institute of Applied Physics, Irkutsk (RIAP), the Institute of Geochemistry, Irkutsk (IGI) and the United States Geological Survey, Reston (USGS) were analysed with the aim of determining Ag, B, Ge, Mo, Sn, Tl and W abundances by an atomic emission method with air-stabilised D.C. arc excitation. Two series of reference samples of soils and bottom sediments, GSS-1-8 and GSD-1-12 (IGGE), were used to ensure the traceability link for the analytical results. Traceability was also demonstrated through the comparison of measured results by AES and ICP-MS methods. It is shown that the reference samples GSS-1-8 and GSD-1-12 satisfied the "fitness-for-purpose" criterion (uncertainty U of the certified value should be one-third to one-tenth the magnitude of routine laboratory data uncertainty S (S/U > 3-10)) and can be applied for calibrating AES techniques. 相似文献
10.
In this paper, the lumped quasi-distributed hydrological model HEC HMS is used to simulate the rainfall–runoff process of the Mekerra watershed, located in the northwest of Algeria. The model parameters’ uncertainty and the predictive intervals were evaluated with the generalized likelihood uncertainty estimation (GLUE) approach. According to the results, good simulations were obtained with different values of variables for many sets of parameters generated randomly by the Monte Carlo procedure, which is known as Equifinality. After the analysis, only the hydraulic conductivity at saturation parameter appears well defined, taking values within a limited range. In addition, results indicated that combinations of likelihood measures associated with multiple and different periods of observations reduce a posterior uncertainty of estimated parameters and predictive intervals in some degree. Overall, the GLUE analysis showed that there is a significant uncertainty associated with hydrological modelling of watershed Mekerra, to a great extent due to multiple sources of errors. 相似文献
11.
I. Lerche 《Mathematical Geology》1997,29(4):469-501
Three different types of methods are used to assess the ability to determine erosion amounts and to provide estimates of uncertainty.
In the situation of dynamical indicator methods, such as seismic velocity, sonic logs, density logs, or drilling exponent
methods, intrinsic assumptions and parameter values used provide only a broad statement on the resolution of uplift/erosion
events. None of the methods is more accurate, at best, to better than ± 1 km and likely much worse. For geological model procedures,
exemplified by considerations of Airy isostasy and by bed upturning near a salt dome in the Nordkapp Basin of the Barents
Sea, the uncertainties are again of the order of ± 500–1000 m. With thermal indicator procedures, the bulk of the constraint
information from available data is needed to determine paleoheat flux with little left over to constrain the erosion, implying
a minimum uncertainty of ± 500 m on erosion determinations. No method seems capable of resolving erosional events to better
than a minimum uncertainty of ± 500 m, and likely no better than ± 1 km. 相似文献
12.
Groundwater age dating with the tritium–helium (3H/3He) method has become a powerful tool for hydrogeologists. The uncertainty of the apparent 3H/3He age depends on the analytical precision of the 3H measurement and the uncertainty of the tritiogenic 3He component. The goal of this study, as part of the groundwater age-dating interlaboratory comparison exercise, was to quantify the analytical uncertainty of the 3H and noble gas measurements and to assess whether they meet the requirements for 3H/3He dating and noble gas paleotemperature reconstruction.Samples for the groundwater dating intercomparison exercise were collected on 1 February, 2012, from three previously studied wells in the Paris Basin (France). Fourteen laboratories participated in the intercomparison for tritium analyses and ten laboratories participated in the noble gas intercomparison. Not all laboratories analyzed samples from every borehole.The reproducibility of the tritium measurements was 13.5%. The reproducibility of the 3He/4He ratio and 4He, Ne, Ar, Kr and Xe concentrations was 1.4%, 1.8%, 1.5%, 2.2%, 2.9%, and 2.4% respectively.The uncertainty of the tritium and noble gas measurements results in a typical 3H/3He age precision of better than 2.5 years in this case. However, the measurement uncertainties for the noble gas concentrations are insufficient to distinguish the appropriate excess air model if the measured helium concentration is not included. While the analytical uncertainty introduces an unavoidable source of uncertainty in the 3H/3He apparent age estimate, other sources of uncertainty are often much greater and less well defined than the analytical uncertainty. 相似文献
13.
Assessing the risk of soil vulnerability to wind erosion through conditional simulation of soil water content in Sistan plain, Iran 总被引：1，自引：0，他引：1
Surface soil water content (SWC) is one of the key factors controlling wind erosion in Sistan plain, southeast of Iran. Knowledge of the spatial variability of surface SWC is then important to identify high-risk areas over the region. Sequential Gaussian simulation (SGSIM) is used to produce a series of equiprobable models of SWC spatial distribution across the study area. The simulated realizations are used to model the uncertainty attached to the surface SWC estimates through producing a probability map of not exceeding a specified critical threshold when soil becomes vulnerable to wind erosion. The results show that SGSIM is a suitable approach for modelling SWC uncertainty, generating realistic representations of the spatial distribution of SWC that honour the sample data and reproduce the sample semivariogram model. The uncertainty model obtained using SGSIM is compared with the model achieved through sequential indicator simulation (SISIM). According to accuracy plots, goodness statistics and probability interval width plots, SGSIM performs better for modelling local uncertainty than SISIM. Sequential simulation provided a probabilistic approach to assess the risk that SWC does not exceed a critical threshold that might cause soil vulnerability to wind erosion. The resulted risk map can be used in decision-making to delineate “vulnerable” areas where a treatment is needed. 相似文献
14.
Klaus Peter Jochum Matthias Willbold Ingrid Raczek Brigitte Stoll Kirstin Herwig 《Geostandards and Geoanalytical Research》2005,29(3):285-302
The USGS reference glasses GSA-1G, GSC-1G, GSD-1G, GSE-1G, BCR-2G, BHVO-2G and BIR-1G were investigated by different analytical techniques. All these materials have a geological (basaltic) matrix and are therefore useful in igneous geochemistry as matrix-matched reference materials for microanalytical techniques. The new GS glasses have trace elements in groups at concentration levels of about < 0.01, 5, 50 and 500 μg g-1 . Their major element compositions have been determined by EPMA, and trace elements have been analysed by LA-ICP-MS and two isotope dilution techniques using TIMS and ICP-MS. EPMA and LA-ICP-MS analyses indicated that the USGS reference glasses are homogeneous at the μm to mm scale with respect to major (variations < 1-2%) and most trace elements (variations 1-4%). Trace element data obtained from the different analytical techniques agreed within an uncertainty of 1-5%, indicating that between method results are comparable. Therefore, the preliminary working values for the four USGS GS glasses calculated from these data have a low level of uncertainty. 相似文献
15.
It is argued that the current division between field sampling and chemical analysis is counterproductive in terms of ensuring that geochemical measurement results are fit for their intended purpose. An integrated approach to the whole measurement process has many advantages including no dependence on the two assumptions that either the samples are necessarily representative if taken with a correct protocol, or that the measurement results can be assumed to be true values of chemical concentration. The measurement results then require values of measurement uncertainty, including that from sampling as well as from chemical analysis. This enables the user of the measurement results, rather than the producer, to judge their fitness for a specific purpose. Case studies are used to illustrate the practicality and benefits of this new approach, including the use of measurement results with optimal, but relatively high, levels of uncertainty to make reliable decisions. This contrasts with the traditional assumption that pursuit of the lowest possible measurement uncertainty is the best approach. 相似文献
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地下水数值模拟不确定性分析旨在提高研究区域地下水流的模拟精度。学者们将地下水数值模拟不确定性分析分为:模型的不确定性、参数的不确定性以及资料的不确定性三类,其中参数的不确定性分析在研究中是最为重要的。同时,对模型、参数、资料不确定性分析的研究进展和成果进行归纳总结,补充关于参数不确定性分析过程中的替代模型的一些研究成果以及模型不确定性分析的多模型分析;强调在地下水数值模拟的过程中,重视模型、资料的不确定性分析;展望未来,随着地下水数值模拟不确定性分析研究的深入,方法和应用会更加多样化。 相似文献
19.
Homa Razmkhah Ali Mohammad AkhoundAli Fereydoun Radmanesh Bahram Saghafian 《Arabian Journal of Geosciences》2016,9(4):323
Lack of accuracy of rainfall-runoff simulation (RRS) remains critical for some applications. Among various sources of uncertainty, precipitation plays a particular role. Rainfall rates as the main input data of RRS are of the first factors controlling the accuracy. In addition to the depth, spatial and temporal distributions of rainfall impact the flood discharge. Most of the previous studies on RRS uncertainty have ignored rainfall spatial distribution, where in large catchments, it is necessary to be modeled explicitly. Karoon III is one most important basin of the Iran because of the Karoon III dam in the outlet. In the present work, effect of spatial correlation of rainfall on HEC-HMS (SMA) continuous RRS uncertainty is evaluated using 2variate copula (2copula). Monte Carlo simulation (MCS) approach was used to consider the rainfall spatial dependence. To reduce the computational expense, sampling efficiency and convergence for MCS, Latin hypercube sampling (LHS) was used. Copula functions consider wide range of marginal probability distribution functions (PDFs), eliminating limits of regular join PDFs. For this aim, two scenarios were investigated. In the first scenario, sub-basin rainfall was considered independent, and in the second scenario, 2copula was adopted to model spatial correlation of rainfall. Dimensionless rainfall depths were calculated for each sub-basin, and the PDFs were determined. The generated random dimensionless rainfalls were reweighted and multiplied by watershed’s mean rainfall value. Stochastic Climate Library was used to generate continuous daily rainfalls. Sampling from dimensionless rainfalls using LHS algorithm, 100 runs of calibrated model-simulated 100 flows for each day following MCS, and 80 % certainty bound was calculated. Results showed that considering dependence decreased 18 % of the maximum uncertainty bound width, so the methodology could be recommended for decreasing predicted runoff error. 相似文献
20.
三维矿床地质模型的不确定性对矿山生产决策有着重要影响,正确地对矿床地质模型进行不确定性分析可以对其本身和在其基础上所做的决策作出科学评价。矿床地质模型的不确定性主要来自于建模数据和插值方法的不确定性。通过对建模数据的产生、处理过程的分析,利用处理不确定性问题的理论和方法建立建模数据的不确定性模型。通过对建模方法产生的理论误差和实测误差进行量化,实现对建模方法不确定性的定量描述。将建模数据的不确定性和建模方法的不确定性进行叠置分析,建立矿床模型的不确定性模型。以内蒙古自治区某煤矿的地质资料为例,通过不确定性分析,建立了该矿的不确定性三维矿床地质模型。 相似文献