Spatio-temporal Web Performance Forecasting with Sequential Gaussian Simulation Method

2012 ◽  
pp. 111-119 ◽  
Author(s):  
Leszek Borzemski ◽  
Anna Kamińska-Chuchmała
Keyword(s):  
Simulation Method ◽  
Sequential Gaussian Simulation ◽  
Web Performance ◽  
Spatio Temporal ◽  
Performance Forecasting ◽  
Gaussian Simulation

scholarly journals Spatio-Temporal Change and Pollution Risk of Agricultural Soil Cadmium in a Rapidly Industrializing Area in the Yangtze Delta Region of China

2018 ◽  
Vol 15 (12) ◽  
pp. 2743 ◽  
Author(s):  
Xianghua Xu ◽  
Jiaying Qian ◽  
Enze Xie ◽  
Xuezheng Shi ◽  
Yongcun Zhao
Keyword(s):  
Potential Risk ◽  
Agricultural Soil ◽  
Sequential Gaussian Simulation ◽  
Rapid Urbanization ◽  
Pollution Risk ◽  
Soil Cadmium ◽  
Rapid Industrialization ◽  
Spatio Temporal ◽  
Major Attention ◽  
Gaussian Simulation

The impacts of rapid industrialization on agricultural soil cadmium (Cd) accumulation and their potential risks have drawn major attention from the scientific community and decision-makers, due to the high toxicity of Cd to animals and humans. A total of 812 topsoil samples (0–20 cm) was collected from the southern parts of Jiangsu Province, China, in 2000 and 2015, respectively. Geostatistical ordinary kriging and conditional sequential Gaussian simulation were used to quantify the changes in spatial distributions and the potential risk of Cd pollution between the two sampling dates. Results showed that across the study area, the mean Cd concentrations increased from 0.110 mg/kg in 2000 to 0.196 mg/kg in 2015, representing an annual average increase of 5.73 μg/kg. Given a confidence level of 95%, areas with significantly-increased Cd covered approximately 12% of the study area. Areas with a potential risk of Cd pollution in 2000 only covered 0.009% of the study area, while this figure increased to 0.75% in 2015. In addition, the locally concentrating trend of soil Cd pollution risk was evident after 15 years. Although multiple factors contributed to this elevated Cd pollution risk, the primary reason can be attributed to the enhanced atmospheric deposition and industrial waste discharge resulting from rapid industrialization, and the quick increase of traffic and transportation associated with rapid urbanization.

Application of Facies-Controlled Modeling in Physical Property Modeling – A Case of Tuo 128 Block

2012 ◽  
Vol 248 ◽  
pp. 129-132 ◽  
Author(s):  
Bin Tian Tan ◽  
Yong Bei Cui ◽  
Xue Li ◽  
Hong Bing Zhao ◽  
Feng Hua Wang
Keyword(s):  
Physical Property ◽  
Sedimentary Facies ◽  
Simulation Method ◽  
Production Performance ◽  
Sequential Gaussian Simulation ◽  
Porosity And Permeability ◽  
Property Modeling ◽  
Reservoir Description ◽  
Log Interpretation ◽  
Gaussian Simulation

The foundation and core of the phased modeling non-homogeneous modeling, Shengtuo oilfield geological modeling of the low porosity and permeability reservoir description of the characteristics of data is small, the accuracy is low, uncertainty factors. Using phased stochastic modeling techniques, log interpretation, based on data combined with core analysis, production performance and other known information, the sedimentary facies model as constraints holes, seepage property modeling to reduce the reservoir description is not uncertainty, combined with sequential Gaussian simulation method to establish a geological model of the actual production status of the oil region, the geological basis for the block rational development decisions and improve the effect of oilfield development.

scholarly journals Conditional Stochastic Simulations of Flow and Transport with Karhunen-Loève Expansions, Stochastic Collocation, and Sequential Gaussian Simulation

2014 ◽  
Vol 2014 ◽  
pp. 1-21 ◽  
Author(s):  
Mina E. Ossiander ◽  
Malgorzata Peszynska ◽  
Veronika S. Vasylkivska
Keyword(s):  
Simulation Method ◽  
Stochastic Simulations ◽  
New Method ◽  
Sequential Gaussian Simulation ◽  
Covariance Operator ◽  
Stochastic Collocation ◽  
Flow And Transport ◽  
Statistical Estimates ◽  
Gaussian Simulation ◽  
Permeability Field

We derive a new method of conditional Karhunen-Loève (KL) expansions for stochastic coefficients in models of flow and transport in the subsurface, and in particular for the heterogeneous random permeability field. Exact values of this field are never known, and thus one must evaluate uncertainty of solutions to the flow and transport models. This is typically done by constructing independent realizations of the permeability field followed by numerical simulations of flow and transport for each realization and assembling statistical estimates of moments of desired quantities of interest. We follow the well-known framework of KL expansions and derive a new method that incorporates known values of the permeability at given locations so that the realizations of the permeability field honor this data exactly. Our method relies on projections to an appropriate subspace of random weights applied to the eigenfunctions of the covariance operator. We use the permeability realizations constructed with our stochastic simulation method in simulations of flow and transport and compare the results to those obtained when realizations are constructed with sequential Gaussian simulation (SGS). We also compare efficiency and stochastic convergence with that of stochastic collocation.

Research on Characteristics and Three-Dimension Geologic Model Building of the Chang2 Reservoir, Yanchang Formation in Zhifang Area, Zhidan Oilfield

2012 ◽  
Vol 466-467 ◽  
pp. 287-292
Author(s):  
Kun Sheng Qiang ◽  
Jian Min Wang ◽  
Xin Wen Tian ◽  
Xiu Xiang Lü ◽  
Li Wang
Keyword(s):  
Model Building ◽  
Simulation Method ◽  
Sequential Gaussian Simulation ◽  
Low Permeability ◽  
Physical Analysis ◽  
Three Dimension ◽  
Reservoir Properties ◽  
Thin Sections ◽  
Field Development ◽  
Gaussian Simulation

Through the reservoir of Chang 2 member in Zhifang area, Zhidan oilfield is typical of low porosity and low permeability reservoir rocks, using casting thin sections, scanning electron microscopy and physical analysis, etc., starting with the reservoir characteristics of Chang2 member, we have understood its causes and characteristics of low permeability. Using sequential indicator simulation and based on the target body method, we established the head of the construction of the reservoir model in Chang 2 member, using the sequential Gaussian simulation method combined with phase control principle, a model of reservoir properties in this area was established, Getting a high quality reservoir and field development and deployment of later development and further adjustments to tap the potential pratical guidance.

scholarly journals Optimal Irrigation Mode and Spatio-Temporal Variability Characteristics of Soil Moisture Content in Different Growth Stages of Winter Wheat

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1180 ◽  
Author(s):  
Yujian Yang ◽  
Yanbo Huang ◽  
Yong Zhang ◽  
Xueqin Tong
Keyword(s):  
Moisture Content ◽  
Winter Wheat ◽  
Time Domain Reflectometry ◽  
Sequential Gaussian Simulation ◽  
Growth Stages ◽  
Evolution Characteristics ◽  
Spatio Temporal ◽  
Jointing Stage ◽  
Gaussian Simulation ◽  
Different Growth Stages

To advance site-specific management of soil volumetric moisture content (VMC), this study analyzed the spatio-temporal evolution characteristics of soil VMC using the method of sequential Gaussian simulation (SGS) during the different growth stages of winter wheat. This was compared with data measured by time domain reflectometry (TDR) which is a well-established electromagnetic technique to measure soil VMC. The spatial autocorrelation coefficient of VMC indicated the strongest clustering of VMC in the tillering stage, and the least clustering of VMC in the harvest stage. A threshold of VMC in topsoil in the jointing stage of winter wheat was put forward. This threshold is 26, signifying that at a lower value, irrigation should be performed and irrigation efficiencies can be improved. Stable and sub-stable areas in the spatial variability maps of VMC were identified in the winter wheat jointing stage. Furthermore, the optimal irrigation stage was the early jointing stage, and irrigation was performed once as a guide. A loose-couple spatial model was constructed using the VMC in topsoil and the volume of water for irrigation. The VMC in the jointing stage of winter wheat was linked with efficient and water-saving irrigation.

scholarly journals Molecular Dynamics Study on the Mechanism of Nanoscale Jet Instability Reaching Supercritical Conditions

2018 ◽  
Vol 8 (10) ◽  
pp. 1714 ◽  
Author(s):  
Qingfei Fu ◽  
Yunxiao Zhang ◽  
Chaojie Mo ◽  
Lijun Yang
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Theoretical Result ◽  
Molecular Model ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Jet Instability ◽  
Subcritical Region ◽  
Thermodynamic Conditions ◽  
Spatio Temporal

This paper investigates the characteristics of a nitrogen jet (the thermodynamic conditions ranging from subcritical to supercritical) ejected into a supercritical nitrogen environment using the molecular dynamics (MD) simulation method. The thermodynamic properties of nitrogen obtained by molecular dynamics show good agreement with the Soave-Redlich-Kwong (SRK) equation of state (EOS). The agreement provides validation for this nitrogen molecular model. The molecular dynamics simulation of homogeneous nitrogen spray is carried out in different thermodynamic conditions from subcritical to supercritical, and a spatio-temporal evolution of the nitrogen spray is obtained. The interface of the nitrogen spray is determined at the point where the concentration of ejected fluid component reaches 50%, since the supercritical jet has no obvious vapor-liquid interface. A stability analysis of the transcritical jets shows that the disturbance growth rate of the shear layer coincides very well with the classical theoretical result at subcritical region. In the supercritical region, however, the growth rate obtained by molecular dynamics deviates from the theoretical result.

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