scholarly journals Sensitivity Analysis of a Phenomenological Thrombosis Model and Growth Rate Characterisation

2021 ◽  
Author(s):  
Gian Marco Melito ◽  
Alireza Jafarinia ◽  
Thomas Hochrainer ◽  
Katrin Ellermann
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Thrombosis Model

Flow Unsteadiness and Stability Characteristics of Low-Re Flow Past an Inclined Triangular Cylinder

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Wei Zhang ◽  
Hui Yang ◽  
Hua-Shu Dou ◽  
Zuchao Zhu
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Unsteady Flow ◽  
Maximum Velocity ◽  
Flow Patterns ◽  
Wake Flow ◽  
Near Wake ◽  
Flow Unsteadiness ◽  
Flow Past ◽  
Far Wake

The present study investigates the two-dimensional flow past an inclined triangular cylinder at Re = 100. Numerical simulation is performed to explore the effect of cylinder inclination on the aerodynamic quantities, unsteady flow patterns, time-averaged flow characteristics, and flow unsteadiness. We also provide the first global linear stability analysis and sensitivity analysis on the targeted physical problem for the potential application of flow control. The objective of this work is to quantitatively identify the effect of cylinder inclination on the characteristic quantities and unsteady flow patterns, with emphasis on the flow unsteadiness and instability. Numerical results reveal that the flow unsteadiness is generally more pronounced for the base-facing-like cylinders (α → 60 deg) where separation occurs at the front corners. The inclined cylinder reduces the velocity deficiency in the near-wake, and the reduction in far-wake is the most notable for the α = 30 deg cylinder. The transverse distributions of several quantities are shifted toward the negative y-direction, such as the maximum velocity deficiency and maximum/minimum velocity fluctuation. Finally, the global stability and sensitivity analysis show that the spatial structures of perturbed velocities are quite similar for α ≤ 30 deg and the temporal growth rate of perturbation is sensitive to the near-wake flow, while for α ≥ 40 deg there are remarkable transverse expansion and streamwise elongation of the perturbed velocities, and the growth rate is sensitive to the far-wake flow.

Environment-specific elasticity and sensitivity analysis of the stochastic growth rate

2009 ◽  
Vol 220 (5) ◽  
pp. 605-610 ◽  
Author(s):  
Per Åberg ◽  
Carl Johan Svensson ◽  
Hal Caswell ◽  
Henrik Pavia
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Stochastic Growth ◽  
Stochastic Growth Rate

A Structured Sensitivity Analysis for a Markov Model of Accounts Receivable

1995 ◽  
Vol 10 (3) ◽  
pp. 643-653 ◽  
Author(s):  
Robert E. Stanford
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Loss Rate ◽  
Percentage Increase ◽  
Present Value ◽  
Accounts Receivable ◽  
Percentage Decrease ◽  
Interest Income ◽  
The Stability ◽  
Bad Debt

We develop algebraic methods for a general sensitivity analysis of the classic Cyert-Davidson-Thompson model of a system of accounts receivable, and use the resulting analytical relationships to investigate the stability of estimates for the losses from doubtful accounts (bad debts) and the present value of interest income generated by charges to the accounts. The limits of applicability of our results are examined by means of a comprehensive numerical analysis of the realizable values of the coefficients in the derived relationships from a four-state model. It was found that neither bad debt losses nor interest income are overly sensitive, in general, to changes in the probabilities of transition between the account age categories, but that some of these probabilities are more critical than others. It was also found that a given percentage increase in the new charge growth rate usually produces approximately the same percentage decrease in the bad debt loss rate.

Optimal staffing of a forest fire fighting organization

1984 ◽  
Vol 14 (4) ◽  
pp. 589-594
Author(s):  
Yash P. Aneja ◽  
Mahmut Parlar
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Forest Fire ◽  
Fire Fighting ◽  
Optimal Size ◽  
Fire Occurrence ◽  
Nonlinear Programming Problem ◽  
Fire Growth ◽  
Probability Densities ◽  
Nonnegativity Constraints

This paper deals with finding the optimal size of a forest fire fighting organization. Fire occurrence and fire growth rate are assumed to be random variables with given probability densities. An objective function representing the expected cost is developed by using probabilistic arguments. The resulting nonlinear programming problem with nonnegativity constraints is solved and an extensive sensitivity analysis is presented for cost related and noncost parameters of the problem.

scholarly journals Experimental sensitivity analysis and control of thermoacoustic systems

2015 ◽  
Vol 787 ◽  
Author(s):  
Georgios Rigas ◽  
Nicholas P. Jamieson ◽  
Larry K. B. Li ◽  
Matthew P. Juniper
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Passive Control ◽  
Control Strategies ◽  
Control Device ◽  
Linear Regime ◽  
Adjoint Methods ◽  
Rijke Tube ◽  
Theoretical Predictions ◽  
And Control

In this paper, we report the results of an experimental sensitivity analysis on a thermoacoustic system – an electrically heated Rijke tube. We measure the change of the linear stability characteristics of the system, quantified as shifts in the growth rate and oscillation frequency, that is caused by the introduction of a passive control device. The control device is a mesh, which causes drag in the system. The rate of growth is slow, so the growth rate and frequency can be measured very accurately over many hundreds of cycles in the linear regime with and without control. These measurements agree qualitatively well with the theoretical predictions from adjoint-based methods of Magri & Juniper (J. Fluid Mech., vol. 719, 2013, pp. 183–202). This agreement supports the use of adjoint methods for the development and implementation of control strategies for more complex thermoacoustic systems.

scholarly journals Uncertainty and sensitivity analysis of control strategies using the benchmark simulation model No1 (BSM1)

2009 ◽  
Vol 59 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Xavier Flores-Alsina ◽  
Ignasi Rodriguez-Roda ◽  
Gürkan Sin ◽  
Krist V. Gernaey
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Monte Carlo ◽  
Carbon Source ◽  
Simulation Model ◽  
Correction Factor ◽  
Control Strategies ◽  
Hydrolysis Rate ◽  
External Carbon Source ◽  
Uncertainty And Sensitivity Analysis

The objective of this paper is to perform an uncertainty and sensitivity analysis of the predictions of the Benchmark Simulation Model (BSM) No. 1, when comparing four activated sludge control strategies. The Monte Carlo simulation technique is used to evaluate the uncertainty in the BSM1 predictions, considering the ASM1 bio-kinetic parameters and influent fractions as input uncertainties while the Effluent Quality Index (EQI) and the Operating Cost Index (OCI) are focused on as model outputs. The resulting Monte Carlo simulations are presented using descriptive statistics indicating the degree of uncertainty in the predicted EQI and OCI. Next, the Standard Regression Coefficients (SRC) method is used for sensitivity analysis to identify which input parameters influence the uncertainty in the EQI predictions the most. The results show that control strategies including an ammonium (SNH) controller reduce uncertainty in both overall pollution removal and effluent total Kjeldahl nitrogen. Also, control strategies with an external carbon source reduce the effluent nitrate (SNO) uncertainty increasing both their economical cost and variability as a trade-off. Finally, the maximum specific autotrophic growth rate (μA) causes most of the variance in the effluent for all the evaluated control strategies. The influence of denitrification related parameters, e.g. ηg (anoxic growth rate correction factor) and ηh (anoxic hydrolysis rate correction factor), becomes less important when a SNO controller manipulating an external carbon source addition is implemented.

A Sensitivity Analysis of Deriso's Delay-Difference Equation Using Simulation

1985 ◽  
Vol 42 (4) ◽  
pp. 836-841 ◽  
Author(s):  
Albert V. Tyler ◽  
Linda L. Sebring ◽  
Margaret C. Murphy ◽  
Lea F. Murphy
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Mortality Rate ◽  
Difference Equation ◽  
Class Structure ◽  
Delay Difference Equation ◽  
Age Class ◽  
True Value ◽  
Two Parameters ◽  
Delay Difference

The degree to which the delay-difference equation can track biomass changes of fish stocks was examined using a sensitivity analysis technique in conjunction with a simulation model having explicit age-class structure. The simplicity of the delay-difference equation results from the manner in which it subsumes age-class structure by using two parameters, one for mortality and one for growth. The changes in biomass in a simulated stock were followed closely by the equation when error-free determinations of stock parameters were transferred from the simulated stock to the equation, even when a high degree of density dependence was allowed in the growth rate, and in some cases when there were large differences in age-specific mortality in the simulated stock. When error was induced in the stock parameters, the delay-difference equation was fairly robust in estimating biomass with mortality rate and growth rate simultaneously either above the true value or below the true value. Good biomass estimates also resulted when growth rate was at the true value and mortality rate was above the true value. Poor biomass estimates resulted when mortality was overestimated while growth was underestimated, or vice versa.

Experimental Sensitivity Analysis and the Equivalence of Pulsed Forcing and Feedback Control in Thermoacoustic Systems

2017 ◽  
Author(s):  
Nicholas P. Jamieson ◽  
Matthew P. Juniper
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Feedback Control ◽  
Decay Rate ◽  
Efficient Method ◽  
Growth Rates ◽  
Decay Rates ◽  
Control Devices ◽  
Set Up ◽  
Linear Decay

We examine the shifts in linear decay rates and growth rates, with and without control devices on a simple thermoacoustic system. When the system is stable, we measure the decay rate by pulsing with a loudspeaker. This improves on the experimental techniques developed by Rigas et al. (J. Fluid Mech., 2016, vol. 787, R1 [1]) and Jamieson et al. (Int. J. Spray and Comb. Dyn., accepted, 2016 [2]), to develop a more efficient method of experimental sensitivity analysis to apply in thermoacoustic systems. When the system is unstable, we use feedback control to bring it to a non-oscillating state. We then switch off the feedback control and measure the growth rate. The results suggest that both methods are suitable for use in the experimental sensitivity analysis of thermoacoustic systems. Our experimental set up is automated and we find that we can obtain thousands of decay rates in 1/12 the time compared with the previous work.

scholarly journals Transition Dates from Earlywood to Latewood and Early Phloem to Late Phloem in Norway Spruce

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 331
Author(s):  
Jožica Gričar ◽  
Katarina Čufar ◽  
Klemen Eler ◽  
Vladimír Gryc ◽  
Hanuš Vavrčík ◽  
...  
Keyword(s):  
Climate Change ◽  
Growth Rate ◽  
Sensitivity Analysis ◽  
Norway Spruce ◽  
Radial Growth ◽  
Wood Properties ◽  
Growth Patterns ◽  
Cambial Cell ◽  
The Czech Republic ◽  
Specific Contribution

Climate change will affect radial growth patterns of trees, which will result in different forest productivity, wood properties, and timber quality. While many studies have been published on xylem phenology and anatomy lately, little is known about the phenology of earlywood and latewood formation, also in relation to cambial phenology. Even less information is available for phloem. Here, we examined year-to-year variability of the transition dates from earlywood to latewood and from early phloem to late phloem in Norway spruce (Picea abies) from three temperate sites, two in Slovenia and one in the Czech Republic. Data on xylem and phloem formation were collected during 2009–2011. Sensitivity analysis was performed to determine the specific contribution of growth rate and duration on wood and phloem production, separately for early and late formed parts. We found significant differences in the transition date from earlywood to latewood between the selected sites, but not between growth seasons in trees from the same site. It occurred in the first week of July at PAN and MEN and more than two weeks later at RAJ. The duration of earlywood formation was longer than that of latewood formation; from 31.4 days at PAN to 61.3 days at RAJ. In phloem, we found differences in transition date from early phloem to late phloem also between the analysed growth seasons; from 2.5 weeks at PAN to 4 weeks at RAJ Compared to the transition from earlywood to latewood the transition from early phloem to late phloem occurred 25–64 days earlier. There was no significant relationship between the onset of cambial cell production and the transition dates. The findings are important to better understand the inter-annual variability of these phenological events in spruce from three contrasting temperate sites, and how it is reflected in xylem and phloem anatomy.

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