scholarly journals Comparisons of Two Approaches for Geotechnical Model Calibration with Scarce Data

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yuanxin Lei ◽  
Huifen Liu ◽  
Zhixiong Lu
Keyword(s):  
Model Calibration ◽  
Mean Squared Error ◽  
Mean Value ◽  
Measured Data ◽  
Empirical Parameter ◽  
Soil Nail ◽  
Parameter Values ◽  
Correction Terms ◽  
Geotechnical Model ◽  
Scarce Data

Geotechnical models are usually built upon assumptions and simplifications, inevitably resulting in discrepancies between model predictions and measurements. To enhance prediction accuracy, geotechnical models are typically calibrated against measurements by bringing in additional empirical or semiempirical correction terms. Different approaches have been used in the literature to determine the optimal values of empirical parameters in the correction terms. When measured data are abundant, calibration outcomes using different approaches can be expected to be practically the same. However, if measurements are scarce or limited, calibration outcomes could differ significantly, depending largely on the adopted calibration approach. In this study, we examine two most commonly used approaches for geotechnical model calibration in the literature, namely, (1) purely data-catering (PDC) approach, and (2) root mean squared error (RMSE) method. Here, the purely data-catering approach refers to selection of empirical parameter values that minimize coefficient of variation of model factor while maintains its mean value of one, based solely on measured data. A real case of calibrating the Federal Highway Administration (FHWA) simplified facing load model for design of soil nail walls is illustrated to thoroughly elaborate the differences in practical calibration and design outcomes using the two approaches under scarce data conditions.

scholarly journals Multi-step building energy model calibration process based on measured data

2021 ◽  
Vol 252 ◽  
pp. 111380
Author(s):  
José Eduardo Pachano ◽  
Carlos Fernández Bandera
Keyword(s):  
Model Calibration ◽  
Building Energy ◽  
Measured Data ◽  
Energy Model ◽  
Calibration Process

scholarly journals CALCULATION OF CONTROL AND ACCEPTABLE LEVELS OF RADIATION FACTORS FOR NUCLEAR PROPULSIONS

2019 ◽  
Vol 5 (2) ◽  
pp. 76-82
Author(s):  
B. I. Zhabrunov ◽  
A. A. Kern ◽  
A. S. Tazov ◽  
B. V. Kutashov
Keyword(s):  
Lower Limit ◽  
Radiation Safety ◽  
Power Level ◽  
Test Procedure ◽  
Mean Value ◽  
Measured Data ◽  
Reactor Power ◽  
Radiation Factor ◽  
Measuring Range ◽  
Acceptable Error

In accordance with requirements of regulatory and guideline documents on radiation safety for controlled radiation factors for the purposes of operating control, controlled and acceptable levels are established. Any excess of these levels requires the determination of the causes and implementation of actions designed to eliminate the excess. The paper presents the method of calculation of these levels and establishing the levels in practice at the present time, disadvantages of accepted regulations are analyzed. It was shown that existing documents do not take into account some circumstances that define the radiation safety test procedure. In a number of measured control points of the radiological situation and staff radiation exposure, the values of controlled parameters are independent of reactor system mode. In the same points that show the dependence of measured data on a reactor power level, values of controlled parameters may also depend on a mode of pumps and purification system. Furthermore, real-time measurements review has showed that beyond the range of lower limit of measuring range of verification means in the range with nonspecified error, the measured data variance is described by mean value and acceptable error. At the same time, a mean value may be a lower order to lower limit of measuring range. Setting a value of controlled level equal to a sum of a mean of double or tripled root-mean-square deviation depending on the accepted confidence level, a possibility of earlier detection of controlled level excess emerges. In this situation, an exact absolute value of a controlling parameter is not essential as that radiation factor level poses no hazard to life. It is important to capture the onset of significant increase of radiation factor i.e. change of radiological situation.

Multi-Objective Engineering Design Via Computer Model Calibration

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Carl Ehrett ◽  
D. Andrew Brown ◽  
Evan Chodora ◽  
Christopher Kitchens ◽  
Sez Atamturktur
Keyword(s):  
Computer Model ◽  
Model Calibration ◽  
Material Design ◽  
Fine Tuning ◽  
Tuning Parameter ◽  
Design Problems ◽  
Multi Objective ◽  
Performance Targets ◽  
Calibration Techniques ◽  
Parameter Values

Abstract Computer model calibration typically operates by fine-tuning parameter values in a computer model so that the model output faithfully predicts reality. By using performance targets in place of observed data, we show that calibration techniques can be repurposed for solving multi-objective design problems. Our approach allows us to consider all relevant sources of uncertainty as an integral part of the design process. We demonstrate our proposed approach through both simulation and fine-tuning material design settings to meet performance targets for a wind turbine blade.

scholarly journals On the environmental zero-point problem in microevolutionary climate response predictions

2022 ◽  
Author(s):  
Rolf Ergon
Keyword(s):  
Phenotypic Plasticity ◽  
Zero Point ◽  
Mean Value ◽  
Environmental Data ◽  
Global Maximum ◽  
Point Problem ◽  
Microevolutionary Change ◽  
Mean Fitness ◽  
The Mean ◽  
Parameter Values

It is well documented that populations adapt to climate change by means of phenotypic plasticity, but few reports on adaptation by means of genetically based microevolution caused by selection. Disentanglement of these separate effects requires that the environmental zero-point is defined, and this should not be done arbitrarily. Together with parameter values, the zero-point can be estimated from environmental, phenotypic and fitness data. A prediction error method for this purpose is described, with the feasibility shown by simulations. An estimated environmental zero-point may have large errors, especially for small populations, but may still be a better choice than use of an initial environmental value in a recorded time series, or the mean value, which is often used. Another alternative may be to use the mean value of a past and stationary stochastic environment, which the population is judged to have been fully adapted to, in the sense that the mean fitness was at a global maximum. An exception is here cases with constant phenotypic plasticity, where the microevolutionary change per generation follows directly from phenotypic and environmental data, independent of the chosen environmental zero-point.

scholarly journals Determination of Earthquake Hypocenter Distribution using the Modified Joint Hypocenter Determination (MJHD) Method throughout the Palu-Koro Fault (Case Study: August-October, 2018)

2021 ◽  
Vol 873 (1) ◽  
pp. 012074
Author(s):  
Dewi Ayu Swastika ◽  
Harmita Lestari ◽  
Aulia Puji Astuti ◽  
Sabrianto Aswad ◽  
Muhammad Fawzy Ismullah Massinai
Keyword(s):  
Velocity Model ◽  
Mean Value ◽  
Time Data ◽  
Tectonic Structures ◽  
Hypocenter Determination ◽  
Joint Hypocenter Determination ◽  
Earthquake Hypocenter ◽  
Earthquake Distribution ◽  
Parameter Values

Abstract The area of Sulawesi, especially along the Palu Koro Fault, is an area that is largely influenced by the confluence and movement of plates as well as regional fault activity pathways with high levels of seismicity. Determining the location of the hypocenter accurately through relocation is required in identifying the detailed tectonic structures in the area. Relocation of the hypocenter using the Modified Joint Hypocenter Determination (MJHD) method using the IASP91 velocity model in the period August to October 2018 with the arrival time data from BMKG catalog. The results of hypocenter relocation using the MJHD method show that from 132 earthquake distribution points to 63 earthquake hypocenter points after the relocation. The change in the location of the hypocenter was much denser along the Palu Koro Fault route than before the relocation as evidenced by the mean value of rms (root mean square) before relocation was 1.31 and after relocation it became smaller (0.61). Changes in parameter values after relocation using the MJHD method caused the distribution of the earthquake hypocenter to be tighter towards the Palu Koro fault than before the relocation, where the distribution had a random and scattered pattern.

scholarly journals The chaos in calibrating crop models

2020 ◽  
Author(s):  
Daniel Wallach ◽  
Taru Palosuo ◽  
Peter Thorburn ◽  
Zvi Hochman ◽  
Emmanuelle Gourdain ◽  
...  
Keyword(s):  
Experimental Data ◽  
Model Calibration ◽  
Crop Model ◽  
Process Models ◽  
Model Parameters ◽  
Model Structure ◽  
Crop Models ◽  
Estimation Of Model Parameters ◽  
Parameter Values ◽  
Made In

Calibration, that is the estimation of model parameters based on fitting the model to experimental data, is among the first steps in essentially every application of crop models and process models in other fields and has an important impact on simulated values. The goal of this study is to develop a comprehensive list of the decisions involved in calibration and to identify the range of choices made in practice, as groundwork for developing guidelines for crop model calibration starting with phenology. Three groups of decisions are identified; the criterion for choosing the parameter values, the choice of parameters to estimate and numerical aspects of parameter estimation. It is found that in practice there is a large diversity of choices for every decision, even among modeling groups using the same model structure. These findings are relevant to process models in other fields.

Evaluation of a NOAH-MP Land Surface Model Ensemble over the Mississippi Basin

2020 ◽  
Author(s):  
Jonas Rothermel ◽  
Maike Schumacher
Keyword(s):  
Soil Moisture ◽  
Data Assimilation ◽  
Numerical Weather Prediction ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Weather Prediction ◽  
Surface Model ◽  
Empirical Parameter ◽  
Numerical Weather ◽  
Parameter Values

<p><span>Physical-based Land Surface Models (LSMs) have deepened the understanding of the hydrological cycle and serve as the lower boundary layer in atmospheric models for numerical weather prediction. As any numerical model, they are subject to various sources of uncertainty, including simplified model physics, unknown empirical parameter values and forcing errors, particularly precipitation. Quantifying these uncertainties is important for assessing the predictive power of the model, especially in applications for environmental hazard warning. Data assimilation systems also benefit from realistic model error estimates.</span></p><p><span><span>In this study, the LSM NOAH-MP is evaluated over the Mississippi basin by running a large ensemble of model configurations with suitably perturbed forcing data and parameter values. For this, sensible parameter distributions are obtained by performing a thorough sensitivity analysis, identifying the most informative parameters beforehand by a screening approach. The ensemble of model outputs is compared against various hydrologic and atmospheric feedback observations, including SCAN soil moisture data, GRACE TWS anomaly data and AmeriFlux evapotranspiration measurements. The long-term aim of this study is to improve land-surface states via data assimilation and to investigate their influence on short- to midterm numerical weather prediction. Thus, the uncertainty of the simulated model states, such as snow, soil moisture in various layers, and groundwater are thoroughly studied to estimate the relative impact of possible hydrologic data sets in the assimilation.</span></span></p>

Lung structure parameters estimated from modeling aerosol deposition in isolated dog lungs

1989 ◽  
Vol 67 (5) ◽  
pp. 2014-2025 ◽  
Author(s):  
F. S. Rosenthal
Keyword(s):  
Experimental Data ◽  
Compartment Model ◽  
Aerosol Deposition ◽  
Mean Value ◽  
Breath Holding ◽  
Alveolar Volume ◽  
Lung Structure ◽  
Alveolar Duct ◽  
Lung Periphery ◽  
Parameter Values

A three-compartment model predicting the recovery of aerosol boli (i.e., the ratio of the number of particles expired to the number inspired) as a function of breath-holding time and bolus penetration was fitted to experimental data measured in nine isolated dog lungs. For each lung, the diameters of alveoli and alveolar ducts, as well as the volume fractions of alveoli, alveolar ducts, and airways, were determined as parameters providing the best fit. Parameter values were alveolar diameter = 0.116 +/- 0.007 (SE) mm, alveolar duct diameter = 0.284 +/- 0.015 mm, total alveolar volume/total lung capacity (TLC) = 0.68 +/- 0.02, total alveolar duct volume/TLC = 0.24 +/- 0.02, and total airway volume/TLC = 0.09 +/- 0.01. These values agreed with published values for linear dimensions and volumetric fractions in the canine lung. The mean alveolar diameter determined by the model in the nine lungs agreed closely with a mean value of 0.115 +/- 0.002 mm determined by morphometric analysis of photographs of the subpleural alveoli in the same lungs. The procedure of fitting the model to experimental data appears to have promise as a noninvasive probe of the lung periphery. However, aerosol-derived dimensions were more variable than morphometric ones, possibly because of interlung differences in aerosol distribution not accounted for in the model.

Flutter and long-wave instabilities in compliant channels conveying developing flows

1997 ◽  
Vol 331 ◽  
pp. 37-58 ◽  
Author(s):  
P. G. LAROSE ◽  
J. B. GROTBERG
Keyword(s):  
Flow Speed ◽  
Infinite Length ◽  
Wave Instability ◽  
Flutter Instability ◽  
Long Wave ◽  
Developing Flow ◽  
Theoretical Predictions ◽  
Parameter Values ◽  
Correction Terms ◽  
Special Parameter

A partially collapsed lung airway or other flexible tube is modelled as a two-dimensional channel of infinite length. We consider the linear stability of this system conveying a developing flow, analysing the full Orr–Sommerfeld system analytically for long waves and numerically for arbitrary wavelengths. We find a long-wave instability which has not been observed in previous channel studies. This long-wave instability is stabilized by increasing the elastance of the wall, but other wall properties do not affect it except in correction terms. In addition to the long-wave instability, there is the finite wavelength (flutter) instability, which, depending on the parameter values chosen, may be critical at a higher or lower flow speed than the long-wave instability. For special parameter values the long-wave and flutter instabilities are critical at the same flow speed. Comparisons with experiments show that theoretical predictions are in agreement with experimental observations.

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