scholarly journals Three-Dimensional Stochastic Seepage Field Analysis of Multimedia Embankment

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaoming Zhao ◽  
Shiyu Shang ◽  
Yuanlin Yang ◽  
Mingming Hu
Keyword(s):  
Hydraulic Conductivity ◽  
Random Field ◽  
Three Dimensional ◽  
Mean Value ◽  
Field Analysis ◽  
Anisotropy Ratio ◽  
Seepage Field ◽  
The Monte Carlo Method ◽  
Total Head ◽  
The Mean

The soil hydraulic conductivity of an embankment has strong spatial variability due to the spatiotemporal variation, both natural and artificial. The strong randomness of the hydraulic conductivity can be expressed by the coefficient of variation (COV) and the fluctuation scale θ. Moreover, different coefficients of variation and fluctuation scales correspond to different random field structures. To study the characteristics of the three-dimensional stochastic seepage field in an embankment under different COVs and fluctuation scales, we generate a three-dimensional random field of the hydraulic conductivity of multimedia embankment based on the local average subdivision technique. In particular, a calculation method for a three-dimensional random seepage field based on the Monte Carlo method combined with a three-dimensional multimedia random field and a deterministic analysis is proposed. The results showed that after three thousand realizations and considering the randomness of the hydraulic conductivity, the position of the free surface of each section in the embankment differed. The mean value of the total head decreased when the COV increased. Furthermore, when the COV was small, the change in the total head with anisotropy ratio was not evident, while the COV was large. The mean value of the total head increased with the anisotropy ratio. When the anisotropy ratio increased, the mean value of the standard deviation of the total head increased first and then decreased.

On the envelope of a Gaussian random field

1978 ◽  
Vol 15 (3) ◽  
pp. 502-513 ◽  
Author(s):  
R. J. Adler
Keyword(s):  
Random Field ◽  
Spectral Theory ◽  
Gaussian Random Field ◽  
Sample Path ◽  
Mean Value ◽  
Two Dimensional ◽  
Qualitative Information ◽  
The Mean

For homogeneous, two-dimensional random field ξ(t), t ∈ R2 we develop the ‘half' spectral theory sufficient to rigorously define its envelope η (t). We then specialise to the case of ξ Gaussian, which implies η is Rayleigh, and consider the mean value of a certain characteristic of the sets {t:η(t) ≧ u} (u ≧ 0). From this we deduce some qualitative information about the sample path behaviour of the Rayleigh field η .

Three-Dimensional Seepage Analysis and Seepage Control System Optimization of a Hydropower Project

2012 ◽  
Vol 468-471 ◽  
pp. 2433-2436
Author(s):  
Wen Ting Zhan ◽  
Qing Xu
Keyword(s):  
Control System ◽  
Three Dimensional ◽  
System Optimization ◽  
Field Analysis ◽  
Hydropower Project ◽  
Seepage Field ◽  
Seepage Analysis ◽  
Dam Foundation ◽  
Seepage Control ◽  
Water Head

The study is conducted for the 3-D seepage field analysis and the seepage control measurements optimization of a hydropower project, which is located in Sichuan Province, China. The seepage control measurements are introduced in this paper. An equivalent method is adopted to simulate drainage holes and the approach of determining equivalent permeability coefficient is presented. The 3-D seepage field with seepage control system is analyzed comprehensively by the water head contours, uplift on the dam foundation, and so on. The necessities of setting the grouting curtain and the drainage holes are discussed respectively. Further the optimal design of the grouting curting and drainage holes of the dam foundation is studied. The results show that special attention should be paid to ensure the well-operation of the seepage control system and the optimization of decreasing the depth of the drainage curtains and grouting curtains properly can be considered.

scholarly journals On the zeroth law of turbulence for the stochastically forced Navier-Stokes equations

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Yat Tin Chow ◽  
Ali Pakzad
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Energy Dissipation Rate ◽  
Mean Value ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Additional Hypothesis ◽  
The Mean ◽  
Deterministic Force ◽  
Martingale Solutions

<p style='text-indent:20px;'>We consider the three-dimensional stochastically forced Navier–Stokes equations subjected to white-in-time (colored-in-space) forcing in the absence of boundaries. Upper bounds of the mean value of the time-averaged energy dissipation rate are derived directly from the equations for weak (martingale) solutions. This estimate is consistent with the Kolmogorov dissipation law. Moreover, an additional hypothesis of energy balance implies the zeroth law of turbulence in the absence of a deterministic force.</p>

scholarly journals Wits Appraisal of a Qatari Male Population: A Comparative Study. Part II

2020 ◽  
Vol 2 (6) ◽  
Author(s):  
Hayder A. Hashim ◽  
Najat Al-Sayed ◽  
Ayah AL-Qaisi
Keyword(s):  
Three Dimensional ◽  
Mean Value ◽  
Cone Beam ◽  
Facial Appearance ◽  
Male Population ◽  
Significant Difference ◽  
The Mean ◽  
Age Range ◽  
Relationship Of ◽  
Gender Specific

Introduction: Cephalometric analysis aims to determine skeletal and dental relationships. The ANB angle, initially suggested by Rediel and applied by Steiner. is the most used angle in establishing the anteroposterior relationship of the mandible to the maxilla. However, limitations to the accuracy of the ANB angle for this purpose have been reported. To avoid these potential sources of inaccuracy a diagnostic tool was introduced by Jenkins and later modified by Jacobson and became known as the “Wits appraisal”. Aims: The aim of this study was to establish the Wits appraisal value in a sample of Qatari males, a group which had not previously been studied in this context, and to compare the findings with those from racially and ethnically differing groups as reported in the literature. Materials and Methods: The sample consisted of 28 lateral cephalometric radiographs of Qatari males with an age range of 15 to 32 years, presenting with a well-balanced facial appearance and an acceptable profile. Results: The mean value of the Wits appraisal for Qatari males in the present study was 0.50 ± 2.96. This differed at a statistically significant level from the mean value in the Jacobson study with no gender significant difference noted. On the other hand, significant differences were found when compared with previous reports on different races. Conclusion: The Wits appraisal value for the Qatari male population studied was 0.5±2.96, a result which is significantly higher than that reported in Jacobson’s study. This study revealed that the Wits appraisal is not ethnicity or gender-specific, and therefore cannot be used to differentiate between different ethnic groups. However, it can find application as an alternative to the ANB angle in the treatment of borderline cases. The application of cone beam computed tomography (CBCT) will enhance the diagnosis and treatment of cases by yielding three-dimensional views.

scholarly journals COMPARISON OF RETINAL NERVE FIBER LAYER THICKNESS BETWEEN EMMETROPES AND HIGH MYOPES

2019 ◽  
Vol 3 (9) ◽  
Author(s):  
Neha Yadav
Keyword(s):  
High Myopia ◽  
Thickness Measurement ◽  
Mean Value ◽  
Analysis Of Covariance ◽  
Field Analysis ◽  
P Value ◽  
Fiber Layer ◽  
Cross Sectional ◽  
Rnfl Thickness ◽  
The Mean

Background: The present study aims to compare RNFL thickness of high myopes of > - 6D and compare with emmetropic patients, so as to interpret and distinguish the physiological changes of high myopia from accompanying diseases in such individuals. Methods: This was a prospective cross-sectional study. All subjects underwent a full ophthalmic examination, refraction and visual field analysis. Optical coherence tomography was used for RFNL thickness measurement. The mean peripapillary RNFL thickness between groups was compared using both analysis of variance and analysis of covariance. Results: The mean value of average RNFL thickness in both groups was found to be 85.40 in group 1 and 99.34 in group 2. P value was 0.0001, showing that there was significant statistical difference between both the groups and average RNFL thickness was thinner in myopic group. Conclusion: RNFL was found to be significantly thin in high myopia. Keywords: RNFL thickness, Myopia, Emmetropes

On the envelope of a Gaussian random field

1978 ◽  
Vol 15 (03) ◽  
pp. 502-513 ◽  
Author(s):  
R. J. Adler
Keyword(s):  
Random Field ◽  
Spectral Theory ◽  
Gaussian Random Field ◽  
Sample Path ◽  
Mean Value ◽  
Two Dimensional ◽  
Qualitative Information ◽  
The Mean

For homogeneous, two-dimensional random field ξ(t), t ∈ R 2 we develop the ‘half' spectral theory sufficient to rigorously define its envelope η (t). We then specialise to the case of ξ Gaussian, which implies η is Rayleigh, and consider the mean value of a certain characteristic of the sets {t:η(t) ≧ u} (u ≧ 0). From this we deduce some qualitative information about the sample path behaviour of the Rayleigh field η .

scholarly journals Comparison of Valgus Correction Angle between Patients with Developmental Dysplasia Hip and Normal Volunteers Measured by Three-Dimensional Reconstruction and X-Ray

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Aobo Zhang ◽  
Qing Han ◽  
Bingpeng Chen ◽  
Chenyu Wang ◽  
Xue Zhao ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Mean Value ◽  
Normal Group ◽  
Correction Angle ◽  
X Ray ◽  
Normal Volunteers ◽  
Significant Difference ◽  
The Mean ◽  
Valgus Correction Angle

Background and purpose. A new method of three-dimensional (3D) reconstruction technology was used to take place of X-ray in measuring valgus correction angle (VCA) of both DDH patients and normal volunteers to improve precision. Two different ways to define VCA according to the various conditions of patients were compared and analyzed. Methods. Bilateral VCA of 50 DDH patients and 56 normal volunteers were measured by Mimics software in the 3D method and X-ray in 2D. Two VCA (the upper VCA and the lower VCA) were measured in both two methods. Every VCA was measured by observer A and observer B for twice separately. The statistical analyses of the differences were calculated among the measurements of the VCA. Results. The mean value of the upper VCA measured in 3D was 4.95°±0.76° in DDH group and 5.56°±0.62° in the normal group with significant difference (t=−6.457, p<0.01). The VCA of DDH group and normal group measured by 3D was larger than 2D, both the upper VCA and the lower VCA. The differences indicated statistically significant. The mean value of lower VCA was 0.60° smaller than the mean value of upper VCA in normal volunteers. The mean value of the lower VCA was 0.58° larger than the mean value of the upper VCA in DDH patients. Conclusions. Compared to X-ray, 3D reconstruction technology is more accurate without conventional limitations. The lower VCA of DDH patients should be regarded as the femoral intramedullary guide angle in TKA, especially for patients with femoral deformities.

A comparison between the dynamic stability of three types of nonlinear orthotropic functionally graded plates under random lateral loads

2015 ◽  
Vol 23 (15) ◽  
pp. 2520-2537 ◽  
Author(s):  
A Asnafi ◽  
M Abedi
Keyword(s):  
Dynamic Stability ◽  
Three Dimensional ◽  
Mean Value ◽  
Functionally Graded ◽  
Kolmogorov Equation ◽  
Lateral Loads ◽  
Functionally Graded Plates ◽  
The Mean ◽  
Stochastic Loads ◽  
Stable Zone

In this manuscript, the dynamic stability and bifurcation occurrence for three famous types of plates including orthotropic sigmoid, power-law and exponential functionally graded plates under lateral stochastic loads are studied. Due to randomness, the behavior and analysis are not conventional deterministic investigation. So, the dynamic stability zone and border curves of bifurcation are evaluated using probability density function of the response. The latter is computed from a completely exact solution of the Fokker Planck Kolmogorov equation. The three dimensional dynamic stable zone and the border surfaces of bifurcation are obtained as a function of material parameter, in-plane forces and the mean value of lateral load. To generalize the results, all the parameters are transformed to some proper non-dimensional variables and then the effects of all prescribed parameters on the dynamic stability are completely discussed and compared. The comparison is done between the plates with themselves and also the corresponding homogenous plate. Finally the results are validated by the bifurcation diagrams of non dimensional deflection of plates that are obtained directly and numerically from the governing equations of plates.

Reliability Calculation of Welded Pressure Pipe with Circumferential Crack Based on 3-D Elastic-Plastic SFEM

2008 ◽  
Vol 575-578 ◽  
pp. 639-642
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Li Xing Huo ◽  
Yu Feng Zhang
Keyword(s):  
Surface Crack ◽  
Safety Assessment ◽  
Crack Depth ◽  
Three Dimensional ◽  
Bending Moment ◽  
Mean Value ◽  
Pressure Pipe ◽  
Circumferential Crack ◽  
The Mean ◽  
Welded Pipe

In this paper, the reliability of welded pressure pipe with circumferential surface crack was calculated by using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The calculation of reliability was based on three dimensional elastic-plastic stochastic finite element program which was developed by ourselves. The effects of variables such as fracture toughness, bending moment and the depth of the circumferential surface crack on the structure reliability were also discussed. The calculation results indicate that the crack depth has great effect on the reliability of the welded pipe. When the mean value of the crack depth is changed from 3mm to 7mm, the failure probability of the welded pipe will change from 10-8 to 10-2. The bending moment also has great effect on the reliability of the welded pipe. When the mean value of moment is changed from10000 N.m to 15000 N.m, the failure probability of the welded pipe increases dramatically for the same circumferential crack depth. Irrespective of the changing of moment, the pipe has higher reliability if the crack depth is less than 5mm(a/t<0.5, t is the thickness of the pipe). The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack.

scholarly journals Stochastic analysis of the hydraulic conductivity estimated for a heterogeneous aquifer via numerical modelling

2015 ◽  
Vol 368 ◽  
pp. 472-477
Author(s):  
C. Lu ◽  
Y. Zhang ◽  
L. Shu ◽  
X. Chen ◽  
S. Chen ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Karst Aquifer ◽  
Unconfined Aquifer ◽  
Pumping Tests ◽  
Heterogeneous Aquifer ◽  
The Monte Carlo Method ◽  
The Mean ◽  
Theis Solution ◽  
Observation Wells ◽  
The Impact

Abstract. The paper aims to evaluate the impacts of the average hydraulic conductivity of the heterogeneous aquifer on the estimated hydraulic conductivity using the observations from pumping tests. The results of aquifer tests conducted at a karst aquifer are first introduced. A MODFLOW groundwater flow model was developed to perform numerical pumping tests, and the heterogeneous hydraulic conductivity (K) field was generated using the Monte Carlo method. The K was estimated by the Theis solution for an unconfined aquifer. The effective hydraulic conductivity (Ke) was calculated to represent the hydraulic conductivity of a heterogeneous aquifer. The results of numerical simulations demonstrate that Ke increase with the mean of hydraulic conductivity (EK), and decrease with the coefficient of variation of the hydraulic conductivity (Cv). The impact of spatial variability of K on the estimated Ke at two observation wells with smaller EK is less significant compared to the cases with larger EK.

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