Sensitivity Analysis of a Priori Power Indices

2014 ◽  
pp. 464-473
Author(s):  
František Turnovec ◽  
Jacek Mercik
Keyword(s):  
Sensitivity Analysis ◽  
A Priori ◽  
Power Indices

A Priori Assessment of Adipose Tissue Mechanical Testing by Global Sensitivity Analysis

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Hosein Naseri ◽  
Håkan Johansson
Keyword(s):  
Sensitivity Analysis ◽  
Adipose Tissue ◽  
Soft Tissues ◽  
Global Sensitivity Analysis ◽  
A Priori ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Material Parameters ◽  
Global Sensitivity ◽  
Indentation Tests

In modeling the mechanical behavior of soft tissues, the proper choice of an experiment for identifying material parameters is not an easy task. In this study, a finite element computational framework is used to virtually simulate and assess commonly used experimental setups: rotational rheometer tests, confined- and unconfined-compression tests, and indentation tests. Variance-based global sensitivity analysis is employed to identify which parameters in different experimental setups govern model prediction and are thus more likely to be determined through parameter identification processes. Therefore, a priori assessment of experimental setups provides a base for systematic and reliable parameter identification. It is found that in indentation tests and unconfined-compression tests, incompressibility of soft tissues (adipose tissue in this study) plays an important role at high strain rates. That means bulk stiffness constitutes the main part of the mechanism of tissue response; thus, these experimental setups may not be appropriate for identifying shear stiffness. Also, identified material parameters through loading–unloading shear tests at a certain rate might not be reliable for other rates, since adipose tissue shows highly strain rate dependent behavior. Frequency sweep tests at a wide-enough frequency range seem to be the best setup to capture the strain rate behavior. Moreover, analyzing the sensitivity of model parameters in the different experimental setups provides further insight about the model itself.

scholarly journals Retrieval of Canopy component temperatures through Bayesian inversion of directional thermal measurements

2009 ◽  
Vol 6 (2) ◽  
pp. 3007-3040 ◽  
Author(s):  
J. Timmermans ◽  
W. Verhoef ◽  
C. van der Tol ◽  
Z. Su
Keyword(s):  
Sensitivity Analysis ◽  
Surface Temperature ◽  
A Priori ◽  
Inversion Method ◽  
Success Rates ◽  
Brightness Temperatures ◽  
Ill Posed ◽  
Priori Information ◽  
The Individual ◽  
High Level

Abstract. In remote sensing evapotranspiration is estimated using a single surface temperature. This surface temperature is an aggregate over multiple canopy components. The temperature of the individual components can differ significantly, introducing errors in the evapotranspiration estimations. The temperature aggregate has a high level of directionality. An inversion method is presented in this paper to retrieve four canopy component temperatures from directional brightness temperatures. The Bayesian method uses both a priori information and sensor characteristics to solve the ill-posed inversion problem. The method is tested using two case studies: 1) a sensitivity analysis, using a large forward simulated dataset, and 2) in a reality study, using two datasets of two field campaigns. The results of the sensitivity analysis show that the Bayesian approach is able to retrieve the four component temperatures from directional brightness temperatures with good success rates using multi-directional sensors (ℜspectra≈0.3, ℜgonio≈0.3, and ℜAATSR≈0.5), and no improvement using mono-angular sensors (ℜ≈1). The results of the experimental study show that the approach gives good results for high LAI values (RMSEgrass=0.50 K, RMSEwheat=0.29 K, RMSEsugar beet=0.75 K, RMSEbarley=0.67 K), but for low LAI values the measurement setup provides extra disturbances in the directional brightness temperatures, RMSEyoung maize=2.85 K, RMSEmature maize=2.85 K. As these disturbances, were only present for two crops and can be eliminated using masked thermal images the method is considered successful.

scholarly journals Retrieval of canopy component temperatures through Bayesian inversion of directional thermal measurements

2009 ◽  
Vol 13 (7) ◽  
pp. 1249-1260 ◽  
Author(s):  
J. Timmermans ◽  
W. Verhoef ◽  
C. van der Tol ◽  
Z. Su
Keyword(s):  
Sensitivity Analysis ◽  
A Priori ◽  
Inversion Method ◽  
Success Rates ◽  
Brightness Temperatures ◽  
Single Temperature ◽  
Ill Posed ◽  
Priori Information ◽  
The Individual ◽  
High Level

Abstract. Evapotranspiration is usually estimated in remote sensing from single temperature value representing both soil and vegetation. This surface temperature is an aggregate over multiple canopy components. The temperature of the individual components can differ significantly, introducing errors in the evapotranspiration estimations. The temperature aggregate has a high level of directionality. An inversion method is presented in this paper to retrieve four canopy component temperatures from directional brightness temperatures. The Bayesian method uses both a priori information and sensor characteristics to solve the ill-posed inversion problem. The method is tested using two case studies: 1) a sensitivity analysis, using a large forward simulated dataset, and 2) in a reality study, using two datasets of two field campaigns. The results of the sensitivity analysis show that the Bayesian approach is able to retrieve the four component temperatures from directional brightness temperatures with good success rates using multi-directional sensors (Srspectra≈0.3, Srgonio≈0.3, and SrAATSR≈0.5), and no improvement using mono-angular sensors (Sr≈1). The results of the experimental study show that the approach gives good results for high LAI values (RMSEgrass=0.50 K, RMSEwheat=0.29 K, RMSEsugar beet=0.75 K, RMSEbarley=0.67 K); but for low LAI values the results were unsatisfactory (RMSEyoung maize=2.85 K). This discrepancy was found to originate from the presence of the metallic construction of the setup. As these disturbances, were only present for two crops and were not present in the sensitivity analysis, which had a low LAI, it is concluded that using masked thermal images will eliminate this discrepancy.

scholarly journals An Empirical Comparison of the Performance of Classical Power Indices

2002 ◽  
Vol 50 (1) ◽  
pp. 1-22 ◽  
Author(s):  
Dennis Leech
Keyword(s):  
A Priori ◽  
Power Indices ◽  
Power Structures ◽  
Empirical Comparison ◽  
Shareholder Voting ◽  
Banzhaf Index ◽  
Weighted Voting ◽  
Voting Power ◽  
Relative A Priori ◽  
New Algorithms

Power indices are general measures of the relative a priori voting power of individual members of a voting body. They are useful for both positive and normative analysis of voting bodies particularly those using weighted voting. This paper applies new algorithms for computing the rival Shapley-Shubik and Banzhaf indices for large voting bodies to shareholder voting power in a cross section of British companies. Each company is a separate voting body and there is much variation in ownership between them resulting in different power structures. Because the data are incomplete, both finite and ‘oceanic’ games of shareholder voting are analysed. The indices are appraised, using reasonable criteria, from the literature on corporate control. The results are unfavourable to the Shapley-Shubik index and suggest that the Banzhaf index much better reflects the variations in the power of shareholders between companies as the weights of shareholder blocs vary.

Investitionsverhalten und Liquiditätsrestringiertheit. Eine Sensitivitätsanalyse / Investment Behaviour and Liquidity Constraints. A Sensitivity Analysis

2000 ◽  
Vol 220 (3) ◽  
pp. 257-283
Author(s):  
Andreas Behr ◽  
Egon Bellgardt
Keyword(s):  
Sensitivity Analysis ◽  
Cash Flow ◽  
A Priori ◽  
Liquidity Constraints ◽  
Sich Eine ◽  
Investment Behaviour

Zusammenfassung In verschiedenen empirischen Arbeiten wird für a priori als nicht liquiditätsrestringiert klassifizierte Unternehmen ein signifikant geringerer Einfluß des Cash Flow auf die Investitionstätigkeit festgestellt. In diesem Artikel wird der Frage nach der Sensitivität dieser Befunde in verschiedener Hinsicht nachgegangen. Es werden drei unterschiedliche Operationalisierungen von Tobins Q vorgenommen sowie vier alternative a priori-Klassifikationsvariablen als Indikatoren zur Messung der Liquiditätsrestringiertheit berücksichtigt. Zudem wird die Sensitivität der Ergebnisse bezüglich der verwendeten Klassengrenzen untersucht. Für drei der vier untersuchten Klassifikationsvariablen zeigt sich, daß die als a priori nicht liquiditätsrestringiert eingestuften Sektorjahre einen signifikant geringeren Einfluß des Cash Flow auf die Investitionstätigkeit aufweisen. Zudem zeigt sich eine relativ geringe Sensitivität der Ergebnisse bezüglich der gewählten Klassifikationsgrenzen. Die Operationalisierung von Tobins Q als Renditequotient führt - im Vergleich zu der auf Bestandsgrößen beruhenden - zu weniger signifikanten Ergebnissen.

Sensitivities Analysis Using the Semi-Analytic Complex Variable Method in Fracture Mechanics

2010 ◽  
Author(s):  
Weiya Jin ◽  
Brian H. Dennis ◽  
Bo Ping Wang
Keyword(s):  
Sensitivity Analysis ◽  
Fracture Mechanics ◽  
Linear System ◽  
Complex Variable ◽  
A Priori ◽  
Computational Cost ◽  
Complex Variable Method ◽  
Variable Method ◽  
Single Edge ◽  
Perturbation Size

In fracture mechanics, due to singularity existing on the crack tip, the corresponding sensitivity analysis of Stress Intensity Factor (SIF) is not clear whether the overall finite difference (OFD) or Semi-analytical Method (SAM) can obtain accurate sensitivities. The paper proposes the Semi-analytical Complex Variable Method (SACVM) to compute sensitivities of SIF and compares the sensitivities computed by the SACVM with those computed by the OFD and SAM in Center Cracked Tension (CCT) specimen and Single Edge Notched Tension (SENT) specimen. The results reveal that the OFD obtains oscillated sensitivities because of the ill-conditioned linear system. The sensitivities computed by the OFD and SAM are sensitive to the perturbation size out of a certain range. However, this certain range varies with different variable, and is not known a priori. The proposed SACVM can always obtain accurate, consistent sensitivities with little extra computational cost than the SAM. The SACVM is not sensitive to the perturbation size and is not affected by the ill-conditioned linear system. Therefore, the SACVM is recommended to deal with sensitivity analysis in the fracture mechanics.

"Counting'' power indices for games with a priori unions

2004 ◽  
Vol 56 (1-2) ◽  
pp. 125-140 ◽  
Author(s):  
Marcin Malawski
Keyword(s):  
A Priori ◽  
Power Indices

The Birthday Problem: Bayesian Inference with Multiple Discrete Hypotheses

2019 ◽  
pp. 61-72
Author(s):  
Therese M. Donovan ◽  
Ruth M. Mickey
Keyword(s):  
Sensitivity Analysis ◽  
Bayesian Inference ◽  
Prior Distribution ◽  
Alternative Hypothesis ◽  
A Priori ◽  
Prior Probabilities ◽  
Birthday Problem ◽  
Informative Prior ◽  
Informative Prior Distribution ◽  
Alternative Hypotheses

The “Birthday Problem” expands consideration from two hypotheses to multiple, discrete hypotheses. In this chapter, interest is in determining the posterior probability that a woman named Mary was born in a given month; there are twelve alternative hypotheses. Furthermore, consideration is given to assigning prior probabilities. The priors represent a priori probabilities that each alternative hypothesis is correct, where a priori means “prior to data collection,” and can be “informative” or “non-informative.” A Bayesian analysis cannot be conducted without using a prior distribution, whether that is an informative prior distribution or a non-informative prior distribution. The chapter discusses objective priors, subjective priors, and prior sensitivity analysis. In addition, the concept of likelihood is explored more deeply.

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