Left ventricle motion modeling and analysis by adaptive-size physically based models

1992 ◽  
Author(s):  
Wen-Chen Huang ◽  
Dmitry B. Goldgof
Keyword(s):  
Left Ventricle ◽  
Motion Modeling ◽  
Modeling And Analysis ◽  
Physically Based ◽  
Physically Based Models

scholarly journals On the residual strength of aging cast iron trunk mains: Physically-based models for asset failure

2016 ◽  
Vol 663 ◽  
pp. 204-212 ◽  
Author(s):  
Azadeh Fahimi ◽  
Timothy S. Evans ◽  
Jeff Farrow ◽  
David A. Jesson ◽  
Mike J. Mulheron ◽  
...  
Keyword(s):  
Cast Iron ◽  
Residual Strength ◽  
Physically Based ◽  
Physically Based Models

scholarly journals Performance of the dynamically dimensioned search algorithm: influence of parameter initialization strategy when calibrating a physically based hydrological model

2017 ◽  
Vol 49 (4) ◽  
pp. 971-988 ◽  
Author(s):  
Franck Lespinas ◽  
Ashu Dastoor ◽  
Vincent Fortin
Keyword(s):  
Search Algorithm ◽  
Low Cost ◽  
Initial Parameter ◽  
Cost Strategy ◽  
Physically Based ◽  
Physically Based Models ◽  
Calibration Solution ◽  
Low Cost Strategy ◽  
Parameter Values ◽  
Initialization Strategy

Abstract This study presents an evaluation of the performance of the dynamically dimensioned search (DDS) algorithm when calibrating the hydrological component of the Visualizing Ecosystems for Land Management Assessments (VELMA) ecohydrological model. Two calibration strategies were tested for the initial parameter values: (1) a ‘high-cost strategy’, where 100 sets of initial parameter values were randomly chosen within the overall parameter space, and (2) a ‘low-cost strategy’, where a unique set of initial parameter values was derived from the available field data. Both strategies were tested for six different values of the maximum number of model evaluations ranging between 100 and 10,000. Results revealed that DDS is able to converge rapidly to a good parameter calibration solution of the VELMA hydrological component regardless of the parameter initialization strategy used. The accuracy and convergence efficiency of the DDS algorithm were, however, slightly better for the low-cost strategy. This study suggests that initializing the parameter values of complex physically based models using information on the watershed characteristics can increase the efficiency of the automatic calibration procedures.

scholarly journals Evaluating performances of simplified physically based models for landslide susceptibility

2015 ◽  
Vol 12 (12) ◽  
pp. 13217-13256 ◽  
Author(s):  
G. Formetta ◽  
G. Capparelli ◽  
P. Versace
Keyword(s):  
Landslide Susceptibility ◽  
Goodness Of Fit ◽  
Shallow Landslides ◽  
Model Parameters ◽  
Test Case ◽  
Susceptibility Analysis ◽  
Physically Based ◽  
Private And Public ◽  
Physically Based Models

Abstract. Rainfall induced shallow landslides cause loss of life and significant damages involving private and public properties, transportation system, etc. Prediction of shallow landslides susceptible locations is a complex task that involves many disciplines: hydrology, geotechnical science, geomorphology, and statistics. Usually to accomplish this task two main approaches are used: statistical or physically based model. Reliable models' applications involve: automatic parameters calibration, objective quantification of the quality of susceptibility maps, model sensitivity analysis. This paper presents a methodology to systemically and objectively calibrate, verify and compare different models and different models performances indicators in order to individuate and eventually select the models whose behaviors are more reliable for a certain case study. The procedure was implemented in package of models for landslide susceptibility analysis and integrated in the NewAge-JGrass hydrological model. The package includes three simplified physically based models for landslides susceptibility analysis (M1, M2, and M3) and a component for models verifications. It computes eight goodness of fit indices by comparing pixel-by-pixel model results and measurements data. Moreover, the package integration in NewAge-JGrass allows the use of other components such as geographic information system tools to manage inputs-output processes, and automatic calibration algorithms to estimate model parameters. The system was applied for a case study in Calabria (Italy) along the Salerno-Reggio Calabria highway, between Cosenza and Altilia municipality. The analysis provided that among all the optimized indices and all the three models, the optimization of the index distance to perfect classification in the receiver operating characteristic plane (D2PC) coupled with model M3 is the best modeling solution for our test case.

scholarly journals Establishment of IDF-curves for precipitation in the tropical area of Central Africa - comparison of techniques and results

2004 ◽  
Vol 4 (3) ◽  
pp. 375-387 ◽  
Author(s):  
B. Mohymont ◽  
G. R. Demarée ◽  
D. N. Faka
Keyword(s):  
Return Period ◽  
Central Africa ◽  
Tropical Region ◽  
Data Sets ◽  
Physically Based ◽  
Physically Based Models ◽  
Comparison Of Techniques ◽  
Idf Curves ◽  
Intensity Duration Frequency ◽  
Technique Comparison

Abstract. The establishment of Intensity-Duration-Frequency (IDF) curves for precipitation remains a powerful tool in the risk analysis of natural hazards. Indeed the IDF-curves allow for the estimation of the return period of an observed rainfall event or conversely of the rainfall amount corresponding to a given return period for different aggregation times. There is a high need for IDF-curves in the tropical region of Central Africa but unfortunately the adequate long-term data sets are frequently not available. The present paper assesses IDF-curves for precipitation for three stations in Central Africa. More physically based models for the IDF-curves are proposed. The methodology used here has been advanced by Koutsoyiannis et al. (1998) and an inter-station and inter-technique comparison is being carried out. The IDF-curves for tropical Central Africa are an interesting tool to be used in sewer system design to combat the frequently occurring inundations in semi-urbanized and urbanized areas of the Kinshasa megapolis.

scholarly journals Calibration of physically based models: back to basics?

2003 ◽  
Vol 5 (4) ◽  
pp. 233-244 ◽  
Author(s):  
Vincent Guinot ◽  
Philippe Gourbesville
Keyword(s):  
Hydrological Model ◽  
Flash Flood ◽  
Model Parameters ◽  
Model Structure ◽  
Ungauged Catchments ◽  
Model Response ◽  
Physically Based ◽  
Physically Based Models ◽  
Extreme Hydrological Events ◽  
Main Factor

The modelling of extreme hydrological events often suffers from a lack of available data. Physically based models are the best available modelling option in such situations, as they can in principle provide answers about the behaviour of ungauged catchments provided that the geometry and the forcings are known with sufficient accuracy. The need for calibration is therefore limited. In some situations, calibration (seen as adjusting the model parameters so that they fit the calculation as closely to the measurements as possible) is impossible. This paper presents such a situation. The MIKE SHE physically based hydrological model is used to model a flash flood over a medium-sized catchment of the Mediterranean Alps (2820 km2). An examination of a number of modelling alternatives shows that the main factor of uncertainty in the model response is the model structure (what are the dominant processes). The second most important factor is the accuracy with which the catchment geometry is represented in the model. The model results exhibit very little sensitivity to the model parameters, and therefore calibration of these parameters is found to be useless.

scholarly journals Picturing and modeling catchments by representative hillslopes

2017 ◽  
Vol 21 (2) ◽  
pp. 1225-1249 ◽  
Author(s):  
Ralf Loritz ◽  
Sibylle K. Hassler ◽  
Conrad Jackisch ◽  
Niklas Allroggen ◽  
Loes van Schaik ◽  
...  
Keyword(s):  
Expert Knowledge ◽  
Water Dynamics ◽  
Rainfall Runoff ◽  
Data Set ◽  
Physically Based Model ◽  
Optimal Representation ◽  
Physically Based ◽  
Physically Based Models ◽  
Streamflow Data ◽  
Runoff Events

Abstract. This study explores the suitability of a single hillslope as a parsimonious representation of a catchment in a physically based model. We test this hypothesis by picturing two distinctly different catchments in perceptual models and translating these pictures into parametric setups of 2-D physically based hillslope models. The model parametrizations are based on a comprehensive field data set, expert knowledge and process-based reasoning. Evaluation against streamflow data highlights that both models predicted the annual pattern of streamflow generation as well as the hydrographs acceptably. However, a look beyond performance measures revealed deficiencies in streamflow simulations during the summer season and during individual rainfall–runoff events as well as a mismatch between observed and simulated soil water dynamics. Some of these shortcomings can be related to our perception of the systems and to the chosen hydrological model, while others point to limitations of the representative hillslope concept itself. Nevertheless, our results confirm that representative hillslope models are a suitable tool to assess the importance of different data sources as well as to challenge our perception of the dominant hydrological processes we want to represent therein. Consequently, these models are a promising step forward in the search for the optimal representation of catchments in physically based models.

Subgrain Structures Characterized by Electron Backscatter Diffraction (EBSD)

2014 ◽  
Vol 794-796 ◽  
pp. 3-8 ◽  
Author(s):  
Sindre Bunkholt ◽  
Knut Marthinsen ◽  
Erik Nes
Keyword(s):  
Driving Forces ◽  
Electron Backscatter Diffraction ◽  
Subgrain Growth ◽  
Electron Backscatter ◽  
Physically Based ◽  
Physically Based Models ◽  
Photo Editing ◽  
Backscatter Diffraction ◽  
Ebsd Method ◽  
Made In

Subgrain structures are frequently characterized by the electron backscatter diffraction (EBSD) method, which is both accurate and provides good statistics. This is essential to better understand the subgrain growth mechanisms and e.g. establish the driving forces and motilities for comparison with physically based models. However, there is no commercially available software which can provide adequate subgrain boundary maps necessary for e.g. size and misorientation analysis. Here, a method that produces such maps utilizing only commercially available software is presented. The clue is to provide the EBSD-software with a parameter that can be used to identify all subgrains. By combining various maps exported from the EBSD-software into photo editing software, a new map is made in which all subgrain boundaries are identified. Missing and incomplete boundaries are traced manually before a reconstructed subgrain map is generated and imported back into the EBSD-software. With this method, the built-in algorithms in the EBSD-software can be readily used to e.g. characterize subgrain growth in aluminium with respect to orientation, size and misorientation.

scholarly journals From Multi-Risk Evaluation to Resilience Planning: The Case of Central Chilean Coastal Cities

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 572 ◽  
Author(s):  
Pilar Barría ◽  
María Luisa Cruzat ◽  
Rodrigo Cienfuegos ◽  
Jorge Gironás ◽  
Cristián Escauriaza ◽  
...  
Keyword(s):  
Risk Management ◽  
Disaster Risk ◽  
Two Dimensions ◽  
Urban Environments ◽  
Disaster Risk Management ◽  
Risk Level ◽  
Coastal Cities ◽  
Physically Based ◽  
Management Plans ◽  
Physically Based Models

Multi-hazard evaluations are fundamental inputs for disaster risk management plans and the implementation of resilient urban environments, adapted to extreme natural events. Risk assessments from natural hazards have been typically restricted to the analysis of single hazards or focused on the vulnerability of specific targets, which might result in an underestimation of the risk level. This study presents a practical and effective methodology applied to two Chilean coastal cities to characterize risk in data-poor regions, which integrates multi-hazard and multi-vulnerability analyses through physically-based models and easily accessible data. A matrix approach was used to cross the degree of exposure to floods, landslides, tsunamis, and earthquakes hazards, and two dimensions of vulnerability (physical, socio-economical). This information is used to provide the guidelines to lead the development of resilience thinking and disaster risk management in Chile years after the major and destructive 2010 Mw8.8 earthquake.

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