scholarly journals A New Dynamic Prediction Model for Underground Mining Subsidence Based on Inverse Function of Unstable Creep

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hua Cheng ◽  
Liangliang Zhang ◽  
Longhui Guo ◽  
Xiaojian Wang ◽  
Shilong Peng
Keyword(s):  
Analogical Reasoning ◽  
Underground Mining ◽  
Inverse Function ◽  
Empirical Method ◽  
Creep Model ◽  
Model Parameters ◽  
Subsidence Basin ◽  
Fitting Method ◽  
Relative Standard ◽  
Improved Model

In this study, an improved Knothe time function model is established via analogical reasoning from a phenomenological perspective, based on an inverse “Hohai creep model” function, in accordance with the antisymmetric relationship between the unstable creep curve and surface dynamic subsidence curve. An empirical method and fitting method are proposed to determine the parameters of the improved model based on the availability of measured field data. The accuracies of the two models are compared with monitored data from eight monitoring points in the main strike profile of the Guotun coal mine subsidence basin. The results show that the improved model can more accurately reflect the dynamic process of surface subsidence. The average relative standard deviation of the improved model is only 4.9%, which is far lower than the 23.1% associated with the Knothe model. This verifies the improved model’s accuracy and reliability. The model parameters for different monitoring stations obtained using the fitting method are similar, which shows that the model parameters are regular and can be easily applied.

scholarly journals Application of the Improved Knothe Time Function Model in the Prediction of Ground Mining Subsidence: A Case Study from Heze City, Shandong Province, China

2020 ◽  
Vol 10 (9) ◽  
pp. 3147
Author(s):  
Liangliang Zhang ◽  
Hua Cheng ◽  
Zhishu Yao ◽  
Xiaojian Wang
Keyword(s):  
Underground Mining ◽  
Shandong Province ◽  
Surface Subsidence ◽  
Time Function ◽  
Relative Standard Error ◽  
Function Model ◽  
Dynamic Surface ◽  
Probability Integral Method ◽  
Relative Standard ◽  
Improved Model

Taking into account the inadequacy of the Knothe time function model to predict the dynamic surface subsidence caused by underground mining, a new hypothesis is proposed, and the improved Knothe time function model is established. Theoretical analysis shows the improved model agrees well with surface subsidence dynamic change, velocity change, and acceleration change rules. Combined with field measured data, the probability integral method, dual-medium method, and least square method are adopted to determine the time influence parameter C and the model order n. Based on monitoring data from four monitoring stations in the Guotun coal mine subsidence basin strike main profile from Heze city, Shandong Province, China, the accuracies of the Knothe time function and improved model are compared and analyzed. Results show the improved model can accurately describe the dynamic surface subsidence process and subsidence velocity with mining time. The average relative standard error between the predicted and measured values is only 4.8%—far lower than the Knothe time function model is 23%, verifying the improved model’s accuracy and reliability.

Strategies to Enhance the Performance of Gaussian Mixture Model Fitting for Uncertainty Quantification by Conditioning to Production Data

2021 ◽  
Author(s):  
Guohua Gao ◽  
Jeroen Vink ◽  
Fredrik Saaf ◽  
Terence Wells
Keyword(s):  
Gaussian Mixture Model ◽  
Mixture Model ◽  
History Matching ◽  
Gaussian Mixture ◽  
Model Parameters ◽  
Gaussian Component ◽  
Large Set ◽  
Cpu Time ◽  
Fitting Method ◽  
New Strategies

Abstract When formulating history matching within the Bayesian framework, we may quantify the uncertainty of model parameters and production forecasts using conditional realizations sampled from the posterior probability density function (PDF). It is quite challenging to sample such a posterior PDF. Some methods e.g., Markov chain Monte Carlo (MCMC), are very expensive (e.g., MCMC) while others are cheaper but may generate biased samples. In this paper, we propose an unconstrained Gaussian Mixture Model (GMM) fitting method to approximate the posterior PDF and investigate new strategies to further enhance its performance. To reduce the CPU time of handling bound constraints, we reformulate the GMM fitting formulation such that an unconstrained optimization algorithm can be applied to find the optimal solution of unknown GMM parameters. To obtain a sufficiently accurate GMM approximation with the lowest number of Gaussian components, we generate random initial guesses, remove components with very small or very large mixture weights after each GMM fitting iteration and prevent their reappearance using a dedicated filter. To prevent overfitting, we only add a new Gaussian component if the quality of the GMM approximation on a (large) set of blind-test data sufficiently improves. The unconstrained GMM fitting method with the new strategies proposed in this paper is validated using nonlinear toy problems and then applied to a synthetic history matching example. It can construct a GMM approximation of the posterior PDF that is comparable to the MCMC method, and it is significantly more efficient than the constrained GMM fitting formulation, e.g., reducing the CPU time by a factor of 800 to 7300 for problems we tested, which makes it quite attractive for large scale history matching problems.

scholarly journals Study on creep performance of launch canister under long-term storage

2019 ◽  
Vol 43 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Cun-Gui Yu ◽  
Tong-Sheng Sun ◽  
Guang-Yuan Xiao
Keyword(s):  
Residual Deformation ◽  
Bottom Layer ◽  
Tensile Creep ◽  
Creep Model ◽  
Model Parameters ◽  
Creep Tests ◽  
Software Environment ◽  
Long Term Storage ◽  
Term Storage

In this paper, the creep performance of a multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey–Norton model, a creep model for the frame material of a launch canister was established. Constant stress tensile creep tests under different stress levels at room temperature were carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with the original support pad was used. Therefore, a position adjustment program of the support pad was put forward. The residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.

scholarly journals Incremental model breakdown to assess the multi-hypotheses problem

2018 ◽  
Vol 22 (8) ◽  
pp. 4565-4581 ◽  
Author(s):  
Florian U. Jehn ◽  
Lutz Breuer ◽  
Tobias Houska ◽  
Konrad Bestian ◽  
Philipp Kraft
Keyword(s):  
Hydrological Modeling ◽  
Model Performance ◽  
Complex Model ◽  
Model Parameters ◽  
Objective Functions ◽  
Final Model ◽  
Incremental Model ◽  
Model Efficiency ◽  
Improved Model ◽  
Model Structures

Abstract. The ambiguous representation of hydrological processes has led to the formulation of the multiple hypotheses approach in hydrological modeling, which requires new ways of model construction. However, most recent studies focus only on the comparison of predefined model structures or building a model step by step. This study tackles the problem the other way around: we start with one complex model structure, which includes all processes deemed to be important for the catchment. Next, we create 13 additional simplified models, where some of the processes from the starting structure are disabled. The performance of those models is evaluated using three objective functions (logarithmic Nash–Sutcliffe; percentage bias, PBIAS; and the ratio between the root mean square error and the standard deviation of the measured data). Through this incremental breakdown, we identify the most important processes and detect the restraining ones. This procedure allows constructing a more streamlined, subsequent 15th model with improved model performance, less uncertainty and higher model efficiency. We benchmark the original Model 1 and the final Model 15 with HBV Light. The final model is not able to outperform HBV Light, but we find that the incremental model breakdown leads to a structure with good model performance, fewer but more relevant processes and fewer model parameters.

Modeling and Simulation of Creep Crack Growth in High Chromium Steels

2014 ◽  
Author(s):  
Nicola Bonora ◽  
Luca Esposito ◽  
Simone Dichiaro ◽  
Paolo Folgarait
Keyword(s):  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Chromium Steel ◽  
Creep Model ◽  
Model Parameters ◽  
Approximate Methods ◽  
High Chromium ◽  
Creep Crack ◽  
Wide Range

Safe and accurate methods to predict creep crack growth (CCG) are required in order to assess the reliability of power generation plants components. With advances in finite element (FE) methods, more complex models incorporating damage can be applied in the study of CCG where simple analytical solutions or approximate methods are no longer applicable. The possibility to accurately simulate CCG depends not only on the damage formulation but also on the creep model since stress relaxation, occurring in the near tip region, controls the resulting creep rate and, therefore, crack initiation and growth. In this perspective, primary and tertiary creep regimes, usually neglected in simplified creep models, plays a relevant role and need to be taken into account. In this paper, an advanced multiaxial creep model [1], which incorporates damage effects, has been used to predict CCG in P91 high chromium steel. The model parameters have been determined based on uniaxial and multiaxial (round notched bar) creep data over a wide range of stress and temperature. Successively, the creep crack growth in standard compact tension sample was predicted and compared with available experimental data.

Improved Semi-Quantitative Reliability-Based Method for Assessment of Pipeline Dents With Stress Risers

2020 ◽  
Author(s):  
Amandeep Singh Virk ◽  
Doug Langer ◽  
Janine Woo ◽  
Nader Yoosef-Ghodsi ◽  
Muntaseer Kainat
Keyword(s):  
The United States ◽  
Radius Of Curvature ◽  
Pressure Cycling ◽  
Stress Risers ◽  
Fitting Method ◽  
Quantitative Analysis Method ◽  
Comprehensive Reliability ◽  
Reported Data ◽  
Improved Model ◽  
Integrity Analysis

Abstract Dents, especially those interacting with stress risers, can pose integrity threats to pipeline systems. Regulations in Canada and the United States mandate the repair of dents based on depth and interaction with stress risers, however, there have been cases in the past where dents that have passed these criteria have ended up in loss of containment. Recent industry’s recommendations regarding dent integrity analysis are predominantly based on strain, and the dent-fatigue models have been proven to be limited in their application. Additionally, these models or methodologies are generally deterministic which may not fully account for uncertainties associated with pipe properties and in-line inspection (ILI) tool measurement. Enbridge Liquid Pipelines Inc. had previously presented a framework to support system wide dent assessment with an efficient probabilistic-based calibrated semi-quantitative analysis method for dents (SQuAD), which elicits potentially injurious features from thousands of features within a system in a reasonable analysis timeframe. This paper expands on the authors’ previous work and presents several improvements that have since been made to the SQuAD model to address the limitations in the initial version of the model. The previous version of SQuAD was strain-based and did not explicitly account for pressure-cycling induced, fatigue-based failure quantitatively. An approximate circle fitting method was adopted for estimating the dent’s radii of curvature in order to calculate strains. In the improved model, filtering techniques have been employed to reduce the noise in the ILI-reported data while preserving the dent shape. Furthermore, a simplified FEA process has been developed to calculate the stresses within a dent due to pressure cycles, thus the fatigue-based Probability of Failure (PoF) of a dent can now be estimated using S-N approach. The filtered data allows for better accuracy in quantifying the radius of curvature of dents as reported by ILI tools, which are used for calculating dent strain as recommended in the updated version of ASME B31.8, Appendix R. Finally, the feasibility of applying this improved SQuAD model is discussed from an operator’s perspective. The improvements allow the enhanced SQuAD model to be used as an effective screening tool on a system-wide basis as part of a comprehensive, reliability-based dent assessment framework.

scholarly journals Features of optimization of model parameters for solving geotechnical problems

2018 ◽  
Vol 251 ◽  
pp. 02035
Author(s):  
Armen Ter-Martirosyan ◽  
Vitalii Sidorov ◽  
Lubov Ermoshina
Keyword(s):  
Laboratory Tests ◽  
Soft Soil ◽  
Degree Of Approximation ◽  
Creep Model ◽  
Soil Parameters ◽  
Model Parameters ◽  
Soil Test ◽  
Compression Tests ◽  
Software Complex ◽  
Input Parameters

At present, numerical methods of calculations, which are implemented in a large number of software complexes, are widely used in geotechnical practice and the definition of input parameters of the ground is very important and necessary to reflect the real work of the foundation of geotechnical structures [1-4]. There are often cases when the results obtained during laboratory tests of soils are not accepted by software complexes, errors are given, recommendations are proposed for changing the parameters in the direction of increasing or decreasing. In connection with these problems, the question arose about the need to optimize soil parameters obtained as a result of laboratory tests to compare and correct these parameters, based on the degree of approximation of model tests with laboratory tests [5]. Optimization of soil parameters can be carried out in the subroutine Soil test, incorporated in the PLAXIS geotechnical software [6]. Using the Soil test, the triaxial and compression tests are simulated based on the input parameters of the soil and the initial test data. The purpose of this study was to describe the methodology for optimizing the parameters of the Hardening Soil model and the Soft Soil Creep model using the PLAXIS 3D software geotechnical complex, as well as a comparative analysis of the results of laboratory soil tests with modeling results in software complex.

scholarly journals Nonlinear Viscoelastic–Plastic Creep Model Based on Coal Multistage Creep Tests and Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3468 ◽  
Author(s):  
Junxiang Zhang ◽  
Bo Li ◽  
Conghui Zhang ◽  
Peng Li
Keyword(s):  
Creep Behavior ◽  
Physical Property ◽  
Creep Model ◽  
Creep Process ◽  
Creep Tests ◽  
Model Based ◽  
Nonlinear Viscoelastic ◽  
Improved Model ◽  
And Control ◽  
Plastic Creep

The development of fractures, which determine the complexity of coal creep characteristics, is the main physical property of coal relative to other rocks. This study conducted a series of multistage creep tests to investigate the creep behavior of coal under different stress levels. A negative elastic modulus and a non-Newtonian component were introduced into the classical Nishihara model based on the theoretical analysis of the experimental results to propose a nonlinear viscoelastic–plastic creep model for describing the non-decay creep behavior of coal. The validity of the model was verified by experimental data. The results show that this improved model can preferably exhibit decelerating, steady state, and accelerating creep behavior during the non-decay creep process. The fitting accuracy of the improved model was significantly higher than that of the classical Nishihara model. Given that acceleration creep is a critical stage in predicting the instability and failure of coal, its successful description using this improved model is crucial for the prevention and control of coal dynamic disasters.

Kinetic study of the Jaffé reaction for quantifying creatinine in serum: 1. Alkalinity controlled with NaOH.

1987 ◽  
Vol 33 (2) ◽  
pp. 278-285 ◽  
Author(s):  
H L Pardue ◽  
B L Bacon ◽  
M G Nevius ◽  
J W Skoug
Keyword(s):  
Curve Fitting ◽  
Interactive Effects ◽  
Kinetic Behavior ◽  
Factorial Experimental Design ◽  
Fitting Method ◽  
Nonlinear Curve Fitting ◽  
Relative Standard ◽  
Standard Additions ◽  
Curve Fitting Method ◽  
Nonlinear Curve

Abstract We studied the kinetic behavior of the reaction of alkaline picrate and creatinine and evaluated a nonlinear curve-fitting method for quantifying creatinine in serum. Using a 3 X 3 factorial experimental design, we evaluated interactive effects among temperature and concentrations of creatinine, picrate, and NaOH. We found no evidence of interference by glucose or unconjugated bilirubin; the effects of the acetoacetate reaction, which is fast, are easily compensated by the curve-fitting method. The reaction with human serum albumin is very complex, but its effects are compensated by the curve-fitting method and by preparing standards containing 50 g of albumin per liter. Calibration plots are linear under a wide variety of conditions for both aqueous standards and standard additions of creatinine to pooled serum. Reproducibility studies with standards containing creatinine at 2, 10, and 20 mg/L yielded relative standard deviations (RSD) of 8.2, 2.5, and 1.3%, corresponding to absolute variations of 0.16, 0.25, and 0.26 mg/L. The average SD for 17 sera containing creatinine at 15-50 mg/L was 0.7 mg/L. The averages of ratios (as percent) of determined vs expected concentrations in 17 sera with added creatinine (7.27 mg/L) were 97.8% for aqueous standards, 99.9% for standards with added albumin.

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