scholarly journals Manning's roughness coefficient determination in laboratory experiments using 2D modeling and automatic calibration

2020 ◽  
pp. 22-33
Author(s):  
Basile Lavoie ◽  
Tew-Fik Mahdi
Keyword(s):  
Experimental Data ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Roughness Coefficient ◽  
Automatic Calibration ◽  
Test Cases ◽  
Data Sets ◽  
Step Method ◽  
Numerous Data

Reliable experimental data are essential for choosing and validating numerical models. Although numerous data sets have been presented in the literature, few have been made widely available to the scientific community. Additionally, these experimental data sets have generally given little attention to the determination of Manning's roughness coefficients. This paper addresses these two issues. Three channel configurations are studied: a flatbed channel, a channel with a triangular sill and a channel with a triangular abutment. Three increasing permanent discharges are used for each configuration, leading to nine test cases. The Manning's coefficients are determined using three methods: the traditional step method, automatic calibration, via a 2D hydrodynamic model, considering theoretical value intervals and automatic calibration ignoring these intervals. The results show that automatic calibration with theoretical value intervals is advantageous compared to the step method. Automatic calibration ignoring theoretical intervals yields low errors but unphysical values; therefore, it is not recommended.

scholarly journals Roughness of Fracture Surfaces in Numerical Models and Laboratory Experiments

2021 ◽  
Author(s):  
Steffen Abe ◽  
Hagen Deckert
Keyword(s):  
Numerical Simulations ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Stress Conditions ◽  
Roughness Coefficient ◽  
Confining Stress ◽  
Rock Samples ◽  
Fracture Surfaces ◽  
Wide Range ◽  
Hurst Exponents

Abstract. We investigate the influence of stress conditions during fracture formation on the geometry and roughness of fracture surfaces. Rough fracture surfaces have been generated in numerical simulations of triaxial deformation experiments using the Discrete Element Method and in laboratory experiments on limestone and sandstone samples. Digital surface models of the rock samples fractured in the laboratory experiments were produced using high resolution photogrammetry. The roughness of the surfaces was analyzed in terms of absolute roughness measures such as an estimated joint roughness coefficient (JRC) and in terms of its scaling properties. The results show that all analyzed surfaces are self-affine, but with different Hurst exponents between the numerical models and the real rock samples. Results from numerical simulations using a wide range of stress conditions to generate the fracture surfaces show a weak decrease of the Hurst exponents with increasing confining stress and a larger absolute roughness for transversely isotropic stress conditions compared to true triaxial conditions. Other than that, our results suggest that stress conditions have little influence on the surface roughness of newly formed fractures.

Determination of the critical O2 delivery from experimental data: sensitivity to error

1988 ◽  
Vol 64 (5) ◽  
pp. 2074-2082 ◽  
Author(s):  
R. W. Samsel ◽  
P. T. Schumacker
Keyword(s):  
Experimental Data ◽  
Experimental Error ◽  
Polynomial Regression ◽  
Regression Line ◽  
Real Data ◽  
Data Sets ◽  
Regression Techniques ◽  
O2 Delivery ◽  
Single Regression

Normally, metabolic need determines tissue O2 consumption (VO2). In states of reduced supply, VO2 declines sharply below a critical level of O2 delivery (QO2 = blood flow X arterial O2 content). Although several investigators have measured a critical O2 delivery in whole animals or in isolated tissues, there is no general agreement over how to determine the critical point from a collection of real data. In this study, we compare three algorithms for finding the critical O2 delivery from a set of experimental data. We also present a technique for estimating the effect of experimental error on the precision of these algorithms. Using 16 data sets collected in normal dogs, we compare single-line, dual-line, and polynomial regression algorithms for identifying the critical O2 delivery. The dual-line and polynomial regression techniques fit the data better (mean residual square deviation 0.024 and 0.031, respectively) than the single-regression line approach (0.110). To investigate the influence of experimental error on the derived critical QO2, we used a Monte Carlo technique, repeatedly perturbing the experimental data to simulate experimental error. We then calculated the variance of the critical QO2 frequency distribution obtained when the three algorithms were applied to the perturbed data. By this analysis, the dual-line regression technique was less sensitive to experimental error than the polynomial technique.

scholarly journals A critical analysis of electrospray techniques for the determination of accelerated rates and mechanisms of chemical reactions in droplets

2020 ◽  
Vol 11 (48) ◽  
pp. 13026-13043
Author(s):  
Grazia Rovelli ◽  
Michael I. Jacobs ◽  
Megan D. Willis ◽  
Rebecca J. Rapf ◽  
Alexander M. Prophet ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Spectrometry ◽  
Reaction Kinetics ◽  
Chemical Reactions ◽  
Critical Analysis ◽  
Numerical Models ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Prior Literature

The application of Electrospray and Electrosonic Spray Ionization Mass Spectrometry (ESI-MS and ESSI-MS) to study accelerated reaction kinetics in droplets is examined using numerical models, new experimental data, and prior literature.

scholarly journals Comparison of Hydraulic Conductivity Values Obtained from Empirical Formulae and Laboratory Experiments

2020 ◽  
Vol 68 (4) ◽  
pp. 669-678
Author(s):  
Mario Hala ◽  
Lubomír Petrula ◽  
Zakaraya Alhasan
Keyword(s):  
Experimental Data ◽  
Hydraulic Conductivity ◽  
Laboratory Experiments ◽  
Internal Erosion ◽  
Variable Porosity ◽  
Groundwater Flow Regime ◽  
Series Of Experiments ◽  
Different Grain Size ◽  
Good Agreement

Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtain relevant statistical sets. In this paper, the experimental data are discussed and compared with hydraulic conductivities obtained from 6 empirical formulae recommended in a previous study. The comparison showed that some empirical formulae provide a good agreement with the experimental data (the most precise were formulae published by Terzaghi and by Sauerbrey). However, some formulae showed high deviation from measured data (formula published by Zamarin).

Behavior of Flexible Buried Pipes Under Geocell Reinforced Subbase Subjected to Repeated Loading

2018 ◽  
Vol 9 (1) ◽  
pp. 22-41 ◽  
Author(s):  
Mohammed Yousif Fattah ◽  
Waqed Hammed Hassan ◽  
Sajjad Emad Rasheed
Keyword(s):  
Experimental Data ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Repeated Loading ◽  
Sand Layer ◽  
Medium Sand ◽  
Buried Pipe ◽  
Buried Pipes ◽  
3D Numerical Model ◽  
Geocell Reinforcement

The present article constitutes an experimental investigation of the behavior of buried PVC pipes. A number of laboratory experiments were conducted using PVC pipes which were buried in a medium sand layer, below a subbase layer, reinforced with geocells. They were subject to repeated dynamic load amplitudes of 0.5 and 1 ton and loading frequencies of 0.5, 1 and 2 Hz, to study the effects of the geocell reinforcement layer, in terms of the amount of stress reaching the pipe crown and the vibration of the pipe. A 3D numerical model was also developed to investigate the performance of the geocell above the buried pipe. The predicted characteristics of the buried pipes were validated using the experimental data. The results showed that geocell reinforcement decreases both crown vibration by 35%, and the vertical pressure reaching the pipe by 41%. The numerical models have a good fit with the experimental work results, both confirming that geocell reinforcement has a significant role to play regarding increasing the safety of pipes.

scholarly journals Roughness of fracture surfaces in numerical models and laboratory experiments

Solid Earth ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 2407-2424
Author(s):  
Steffen Abe ◽  
Hagen Deckert
Keyword(s):  
Numerical Simulations ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Stress Conditions ◽  
Roughness Coefficient ◽  
Confining Stress ◽  
Rock Samples ◽  
Fracture Surfaces ◽  
Wide Range ◽  
Hurst Exponents

Abstract. We investigate the influence of stress conditions during fracture formation on the geometry and roughness of fracture surfaces. Rough fracture surfaces have been generated in numerical simulations of triaxial deformation experiments using the discrete element method and in a small number of laboratory experiments on limestone and sandstone samples. Digital surface models of the rock samples fractured in the laboratory experiments were produced using high-resolution photogrammetry. The roughness of the surfaces was analyzed in terms of absolute roughness measures such as an estimated joint roughness coefficient (JRC) and in terms of its scaling properties. The results show that all analyzed surfaces are self-affine but with different Hurst exponents between the numerical models and the real rock samples. Results from numerical simulations using a wide range of stress conditions to generate the fracture surfaces show a weak decrease of the Hurst exponents with increasing confining stress and a larger absolute roughness for transversely isotropic stress conditions compared to true triaxial conditions. Other than that, our results suggest that stress conditions have little influence on the surface roughness of newly formed fractures.

scholarly journals Design of Blast-Loaded Glazing Windows and Facades: A Review of Essential Requirements towards Standardization

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Martin Larcher ◽  
Michel Arrigoni ◽  
Chiara Bedon ◽  
J. C. A. M. van Doormaal ◽  
Christof Haberacker ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Methods ◽  
Numerical Models ◽  
Experimental Investigations ◽  
Laminated Glass ◽  
Crucial Importance ◽  
Protection Level ◽  
Main Structure ◽  
Blast Protection

The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This paper attempts to give a first idea of a possible standardization concerning such numerical simulations. Attention is drawn to the representation of the blast loading and to the proper description of the behaviour of the material of the mentioned products, to the geometrical meshing, and to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined.

Rule-Based Mamdani-Type Fuzzy Modeling of Heating and Cooling Performances of Counter Flow Ranque-Hilsch Vortex Tubes with Different Geometric Construction for Brass

2013 ◽  
Vol 372 ◽  
pp. 346-349
Author(s):  
Dilek Nur Ozen ◽  
Adnan Berber ◽  
Kevser Dincer
Keyword(s):  
Experimental Data ◽  
Vortex Tube ◽  
Modeling Technique ◽  
Data Sets ◽  
Geometric Constructions ◽  
Counter Flow ◽  
Rule Based ◽  
Heating And Cooling ◽  
Vortex Tubes

In this study, thermal performances of counter flow Ranque-Hilsch vortex tubes were experimentally investigated and modeled with a Rule Based Mamdani-Type Fuzzy (RBMTF) modeling technique. The vortex tubes were made of brass. Diameter of vortex tube (D) was 10 mm. Length of vortex tube (L) was 10D, 11D, 12D, 13D, 14D. Input parameters (ξ, L/D) and output parameters (ΔTh, ΔTc) were described by RBMTF if-then rules. 45 experimental data sets were used in the training step. R2 for the ΔTh was found to be 99.42 % and R2 for the ΔTc was 99.66 %. The actual values and RBMTF results demonstrated that RBMTF can be successfully used for the determination of heating and cooling performances of counter flow RHVT with different geometric constructions for brass.

Direct phase determination in electron crystallography: small organic molecules

1992 ◽  
Vol 50 (2) ◽  
pp. 1166-1167
Author(s):  
Douglas L. Dorset
Keyword(s):  
Organic Molecules ◽  
Data Sets ◽  
Temperature Structure ◽  
3D Analysis ◽  
Intensity Data ◽  
Electron Crystallography ◽  
Phase Determination ◽  
Measured Intensity ◽  
3D Data

The quantitative use of electron diffraction intensity data for the determination of crystal structures represents the pioneering achievement in the electron crystallography of organic molecules, an effort largely begun by B. K. Vainshtein and his co-workers. However, despite numerous representative structure analyses yielding results consistent with X-ray determination, this entire effort was viewed with considerable mistrust by many crystallographers. This was no doubt due to the rather high crystallographic R-factors reported for some structures and, more importantly, the failure to convince many skeptics that the measured intensity data were adequate for ab initio structure determinations.We have recently demonstrated the utility of these data sets for structure analyses by direct phase determination based on the probabilistic estimate of three- and four-phase structure invariant sums. Examples include the structure of diketopiperazine using Vainshtein's 3D data, a similar 3D analysis of the room temperature structure of thiourea, and a zonal determination of the urea structure, the latter also based on data collected by the Moscow group.

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