排序方式： 共有52条查询结果，搜索用时 187 毫秒
1.
VGI and crowdsourced data credibility analysis using spam email detection techniques 总被引：2，自引：0，他引：2
Volunteered geographic information (VGI) can be considered a subset of crowdsourced data (CSD) and its popularity has recently increased in a number of application areas. Disaster management is one of its key application areas in which the benefits of VGI and CSD are potentially very high. However, quality issues such as credibility, reliability and relevance are limiting many of the advantages of utilising CSD. Credibility issues arise as CSD come from a variety of heterogeneous sources including both professionals and untrained citizens. VGI and CSD are also highly unstructured and the quality and metadata are often undocumented. In the 2011 Australian floods, the general public and disaster management administrators used the Ushahidi Crowd-mapping platform to extensively communicate flood-related information including hazards, evacuations, emergency services, road closures and property damage. This study assessed the credibility of the Australian Broadcasting Corporation’s Ushahidi CrowdMap dataset using a Naïve Bayesian network approach based on models commonly used in spam email detection systems. The results of the study reveal that the spam email detection approach is potentially useful for CSD credibility detection with an accuracy of over 90% using a forced classification methodology. 相似文献
2.
The metalized quartz veins is located 5 km west of the Iraqi-Iran border in the Qandil range. The quartz veins included sulfide and oxide ore minerals which mostly occur in the form of open-space filling texture. The polymetallic mesothermal quartz veins are hosted by marble and phyllite rocks. Within these veins, multiphase, open-space filling and crustiform, bedding to massive textures with pyrite, sphalerite, galena, chalcopyrite,galena, sphalerite, tenorite, azurite, and malachite are observed. Selected samples were analyzed by using ore microscopy and electron probe micro analyzer (EPMA) and scanning electron microscope (SEM). Ore minerals show replacement textures. The paragenesis diagram was made from a careful study of polished sections and three stages have been identified including pre-stage mineralization, mineralization, and post-mineralization stages.Fluid inclusion microthermometric analysis of 15 primary inclusions of quartz veins indicated that ore mineralization at the studied area were formed by a mesothermal, low to medium density, and dilute NaCl-type fluid system. The source of the fluid is mostly metamorphic which became mixed with other fluids later. Hydrothermal fluids of the selected studied area were classified into two groups based on microthermometry study; the first group had a higher homogenization temperature (335.5 to 386.8 °C) than the second group (194.1 to 298.5 °C), with a small difference in salinity between them. Nearly each group has different complexes including chloride and sulfide complexes respectively. The results of stable sulfur isotope of the ore minerals (chalcopyrite and sphalerite) confirmed the sedimentary and/or metamorphic origin of the ore mineralization. 相似文献
3.
Recently, groundwater vulnerability assessment of coastal aquifers using the GALDIT framework has been widely used to investigate the process of groundwater contamination. This study proposes multi-attribute decision-making (MADM) entropy and Wilcoxon non-parametric statistical test methods to improve the vulnerability index of coastal aquifers. The rates and weights of this framework were modified using Wilcoxon non-parametric and entropy methods, respectively, and a combined framework of GALDIT-entropy, Wilcoxon-GALDIT, and Wilcoxon-entropy was obtained. Pearson correlation coefficients between the mentioned vulnerability indices and total-dissolved solids (TDS) of 0.51, 0.66 and 0.75, respectively, were obtained. According to the results, the Wilcoxon-entropy index had the highest correlation with TDS. Generally, it can be concluded that the proposed frameworks provide a more accurate estimation of vulnerability distribution in coastal aquifers. 相似文献
4.
Multicriteria sensitivity analysis as a diagnostic tool for understanding model behaviour and characterizing model uncertainty 总被引：1，自引：0，他引：1 
下载免费PDF全文
下载免费PDF全文 Complex hydrological models are being increasingly used nowadays for many purposes such as studying the impact of climate and land‐use change on water resources. However, building a high‐fidelity model, particularly at large scales, remains a challenging task, due to complexities in model functioning and behaviour and uncertainties in model structure, parameterization, and data. Global sensitivity analysis (GSA), which characterizes how the variation in the model response is attributed to variations in its input factors (e.g., parameters and forcing data), provides an opportunity to enhance the development and application of these complex models. In this paper, we advocate using GSA as an integral part of the modelling process by discussing its capabilities as a tool for diagnosing model structure and detecting potential defects, identifying influential factors, characterizing uncertainty, and selecting calibration parameters. Accordingly, we conduct a comprehensive GSA of a complex land surface–hydrology model, Modélisation Environmentale–Surface et Hydrologie (MESH), which combines the Canadian land surface scheme with a hydrological routing component, WATROUTE. Various GSA experiments are carried out using a new technique, called Variogram Analysis of Response Surfaces, for alternative hydroclimatic conditions in Canada using multiple criteria, various model configurations, and a full set of model parameters. Results from this study reveal that, in addition to different hydroclimatic conditions and SA criteria, model configurations can also have a major impact on the assessment of sensitivity. GSA can identify aspects of the model internal functioning that are counter‐intuitive and thus help the modeller to diagnose possible model deficiencies and make recommendations for improving development and application of the model. As a specific outcome of this work, a list of the most influential parameters for the MESH model is developed. This list, along with some specific recommendations, is expected to assist the wide community of MESH and Canadian land surface scheme users, to enhance their modelling applications. 相似文献
5.
Enhanced identification of a hydrologic model using streamflow and satellite water storage data: A multicriteria sensitivity analysis and optimization approach 总被引：1，自引：0，他引：1 下载免费PDF全文
下载免费PDF全文 Fuad Yassin Saman Razavi Howard Wheater Gonzalo Sapriza‐Azuri Bruce Davison Alain Pietroniro 《水文研究》2017,31(19):3320-3333
Hydrologic model development and calibration have continued in most cases to focus only on accurately reproducing streamflows. However, complex models, for example, the so‐called physically based models, possess large degrees of freedom that, if not constrained properly, may lead to poor model performance when used for prediction. We argue that constraining a model to represent streamflow, which is an integrated resultant of many factors across the watershed, is necessary but by no means sufficient to develop a high‐fidelity model. To address this problem, we develop a framework to utilize the Gravity Recovery and Climate Experiment's (GRACE) total water storage anomaly data as a supplement to streamflows for model calibration, in a multiobjective setting. The VARS method (Variogram Analysis of Response Surfaces) for global sensitivity analysis is used to understand the model behaviour with respect to streamflow and GRACE data, and the BORG multiobjective optimization method is applied for model calibration. Two subbasins of the Saskatchewan River Basin in Western Canada are used as a case study. Results show that the developed framework is superior to the conventional approach of calibration only to streamflows, even when multiple streamflow‐based error functions are simultaneously minimized. It is shown that a range of (possibly false) system trajectories in state variable space can lead to similar (acceptable) model responses. This observation has significant implications for land‐surface and hydrologic model development and, if not addressed properly, may undermine the credibility of the model in prediction. The framework effectively constrains the model behaviour (by constraining posterior parameter space) and results in more credible representation of hydrology across the watershed. 相似文献
6.
We present a simple modelling method to estimate the volume of available groundwater in the freshwater lens of atoll islands under steady-state conditions. Model inputs include annual rainfall depth, island width for cross-sections along the length of the island, aquifer hydraulic conductivity, and depth to the contact between the upper sand aquifer and the lower limestone aquifer. The methodology is tested for nine islands of varying size in the Maldives and Micronesia. Sensitivity analysis indicates that lens volume on large islands typically is governed by the depth to the discontinuity, whereas lens volume for smaller islands is governed by rainfall rate and hydraulic conductivity. Volume curves, which relate lens volume to lens thickness, are developed for each of the nine islands and for three generic island shapes to allow rapid estimation of lens volume given field-estimated lens thickness. The methods presented in this study can be used for any small atoll island. 相似文献
7.
Saman Yaghmaei-Sabegh 《Bulletin of Earthquake Engineering》2014,12(2):585-606
On August 11, 2012, East-Azerbuijan province experienced moderate-size double earthquakes, approximately 60 km northeast of the city of Tabriz. The time–frequency characteristics of ground motion records during these events which caused widespread damage to the structures are investigated in detail. Wavelet transform were applied in this study as a powerful technique to detect the transient and non-stationary features associated in amplitude and frequency of ground motions. The top four PGA ground-motion records from the first and second events were used in the analysis. As a preliminary estimates, the energy contents of horizontal and vertical components of ground-motion records related to building damages were critically evaluated and discussed at different frequency level. Results of energy distribution on pseudo-period corresponding to each decomposition level show good consistency with the level of damage in the stricken area. The focus of this study on the causes of damage considering the energy content of ground motion records is helping to improve the engineering insight in design process of earthquake-resistant buildings. 相似文献
8.
Mohammad Koneshloo Saman A. Aryana Dario Grana John W. Pierre 《Mathematical Geosciences》2017,49(8):995-1020
Realistic and accurate static geologic models are an essential element needed to predict the behavior of subsurface reservoirs and play an important role in petroleum engineering. Data used in the development of a static geologic model are gathered from various sources, such as seismic, log, and core data, each of them providing information on different physical properties of interest and with varying degrees of resolution. Compiling all data from various sources into a single representation of the subsurface formation of interest is a daily challenge for many petroleum geologists and engineers. This paper describes a framework to develop and select process-mimicking models that are consistent with available seismic attributes, namely impedance. Using a process-mimicking modeling package, 75 models of a fluvial meandering system are generated, one of which is chosen as the “true” model and masked thereafter. The implemented selection method relies on the degree of similarity in the histogram of representations of clusters of all possible patterns in the seismic impedance domain based on each process-mimicking model and that of the “true” model at several resolutions. The results demonstrate the effectiveness of the use of a weighted average divergence distance across multiple levels to select process-mimicking models that honor seismic data the best. 相似文献
9.
In conventional seismic hazard analysis, uniform distribution over area and magnitude range is assumed for the evaluation of source seismicity which is not able to capture peculiar characteristic of near-fault ground motion well. For near-field hazard analysis, two important factors need to be considered: (1) rupture directivity effects and (2) occurrence of scenario characteristic ruptures in the nearby sources. This study proposed a simple framework to consider these two effects by modifying the predictions from the conventional ground motion model based on pulse occurrence probability and adjustment of the magnitude frequency distribution to account for the rupture characteristic of the fault. The results of proposed approach are compared with those of deterministic and probabilistic seismic hazard analyses. The results indicate that characteristic earthquake and directivity consideration both have significant effects on seismic hazard analysis estimates. The implemented approach leads to results close to deterministic seismic hazard analysis in the short period ranges (T < 1.0 s) and follows probabilistic seismic hazard analysis results in the long period ranges (T > 1.0 s). Finally, seismic hazard maps based on the proposed method could be developed and compared with other methods. 相似文献
10.
An approximate‐simple method for nonlinear response estimates of reinforced concrete frames subjected to near‐field and far‐field records is presented in this paper. The approximate method is based on equivalent single‐degree‐of‐freedom and linear multi‐degree‐of‐freedom models. In this procedure, the nonlinear maximum roof displacement is estimated using an effective period factor and elastic response spectrum with an equivalent damping. The effective period factor was proposed for far‐field and near‐field ground motion records. For regions of high seismicity, the maximum roof displacement can be estimated by applying an effective period factor of 2.3 and 2.1 for near‐field and far‐field records, respectively, and 9% damped displacement response spectrum. For regions of moderate seismicity, a lower effective period factor of 1.9 and 1.8, for near‐field and far‐field records, respectively, can be applied to estimate the maximum roof displacement. A relationship between linear and nonlinear response of multi‐degree‐of‐freedom systems was also proposed to obtain estimates of the maximum inter‐story drift of nonlinear responding reinforced concrete frames. In addition, the effects of number of ground motion records used in the analyses on the scatters of results were investigated. The required number of ground motions to produce a reliable response was proposed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献