The Role of Nowcast and Forecast Input Parameters for Range Dependent Transmission Models

2002 ◽  
pp. 547-554
Author(s):  
Janice S. Sendt ◽  
Adrian D. Jones ◽  
Jarrad R. Exelby
Keyword(s):  
Input Parameters ◽  
Transmission Models

scholarly journals THE LUCK IN “TALENT VERSUS LUCK” MODELING

2020 ◽  
Vol 23 (03) ◽  
pp. 2050007
Author(s):  
SEAN ELVIDGE
Keyword(s):  
Mean Value ◽  
Maximum Amount ◽  
Random Numbers ◽  
Individual Parameter ◽  
Input Parameters ◽  
The Mean ◽  
Model Variability ◽  
The Impact ◽  
The Relationship

This paper further investigates the Talent versus Luck (TvL) model described by [Pluchino et al. Talent versus luck: The role of randomness in success and failure, Adv. Complex Syst. 21 (2018) 1850014] which models the relationship between ‘talent’ and ‘luck’ on the impact of an individuals career. It is shown that the model is very sensitive to both random sampling and the choice of value for the input parameters. Running the model repeatedly with the same set of input parameters gives a range of output values of over 50% of the mean value. The sensitivity of the inputs of the model is analyzed using a variance-based approach based upon generating Sobol sequences of quasi-random numbers. When using the model to look at the talent associated with an individual who has the maximum capital over a model run it has been shown that the choice for the standard deviation of the talent distribution contributes to 67% of the model variability. When investigating the maximum amount of capital returned by the model the probability of a lucky event at any given epoch has the largest impact on the model, almost three times more than any other individual parameter. Consequently, during the analysis of the model results one must keep in mind the impact that only small changes in the input parameters can have on the model output.

Modelling of tribological responses of composites using integrated ANN-GA technique

2020 ◽  
pp. 002199832096052
Author(s):  
Santanu Sardar ◽  
Swati Dey ◽  
Debdulal Das
Keyword(s):  
Optimization Technique ◽  
Matrix Composites ◽  
Large Numbers ◽  
Wide Range ◽  
Input Parameters ◽  
Input Variables ◽  
Velocity Input ◽  
Abrasive Size

In the present article, artificial neural networks (ANNs) and genetic algorithm (GA) methodology were integrated to model tribological characteristics of stir-cast Al-Zn-Mg-Cu matrix composites under two-body abrasion considering large numbers of experimentally generated results. Tribo-responses of wear rate (Wrt), coefficient of friction (COF) and roughness of abraded surface (RAS) were evaluated under wide range of intrinsic ( i.e., particle quantity) and extrinsic ( i.e., abrasive size, load, distance and velocity) input parameters. Characteristics of Wrt, COF and RAS are often mutually contradictory in nature and so, multi-objective optimization technique becomes imperative for selection and design of machine components. Accordingly, those were optimized through Pareto solutions. Sensitivity of different factors was analyzed on each of the tribo-performances and validated via experimental evidences. Amongst the input variables, particle quantity and abrasive size dominated significantly over other variables except load which imparted modest influences. The role of various input parameters was explained through determination of different micromechanisms via exhaustive post wear characterizations, microstructural and surface topography attributes. Lowest values of Wrt and COF with a modest value of RAS were identified at 15 ± 2 wt.% particle quantity.

scholarly journals Transmission models for the fish pathogen Ichthyophonus: synthesis of field observations and empirical studies

2019 ◽  
Vol 76 (4) ◽  
pp. 636-642 ◽  
Author(s):  
Richard M. Kocan
Keyword(s):  
Empirical Studies ◽  
Large Fish ◽  
Fish Pathogen ◽  
Free Living ◽  
Saltwater Fish ◽  
Mode Of Transmission ◽  
Infected Prey ◽  
Transmission Models ◽  
Inshore Migration

Empirical studies have demonstrated that Ichthyophonus is transmitted among piscivores via consumption of infected prey; however, this unidirectional mode of transmission from small to large fish cannot sustain Ichthyophonus within a population. To circumvent this problem, Ichthyophonus evolved an infective waterborne cell that has been shown to infect both fresh- and saltwater fish. Successful transmission of Ichthyophonus via a waterborne stage is linked to the proximity of infected and susceptible individuals, a condition met when the two groups occupy the same habitat. It is posited that this occurs during annual inshore migrations when herring (Clupea spp.) enter areas occupied by infected demersal predators. A plausible transmission scenario is that during inshore excursions, planktivores are exposed to infective waterborne cells shed by demersal piscivores. Once planktivores are infected, the parasite is recycled when consumed by predators. This model is supported by reports of ichthyophoniasis increasing in herring populations at the time of inshore migration. The possible role of an intermediate host for Ichthyophonus, as well as evidence for a free-living stage in its life cycle, is presented.

scholarly journals APPLICATION OF SIMILARITY METHOD AND DIMENSIONAL ANALYSIS IN DETERMINING THE PERFORMANCE PARAMETERS OF AGITATOR PADDLES FOR CALTEX AQUATEX 3180 CUTTING OIL

2020 ◽  
Vol 6 (1) ◽  
pp. 47-54
Author(s):  
Do Thi Tam ◽  
Tran The Long ◽  
Nguyen Hoang Quan
Keyword(s):  
Dimensional Analysis ◽  
General Purpose ◽  
Cutting Fluid ◽  
Machining Processes ◽  
Input Parameters ◽  
Experimental Process ◽  
Actual Operation ◽  
Machining Operations ◽  
Similarity Method

Aquatex 3180 is the general purpose soluble oil, formulated for use in a wide variety of machining operations. In fact, the natural diffusion in the liquid is very slow, especially the mixing ratio, and the homogeneity of the solution is difficult to achieve according to the manufacturer's recommendation. Hence, the agitator is required to improve the uniformity of the solution in that the obtained cutting fluid can be effectively used in machining processes to fulfill the role of cooling and lubricating. In this work, the application of the similarity method and dimensional analysis for studying agitator model for mixing Aquatex 3180 cutting oil to build the set of input parameters in the experimental process. The results reveal that the input parameters in the study of the agitator model using 9 similarity criterions πi (i = 1 ... 9) instead of 12 independent parameters. In addition, the standard π2 can characterize the displacement properties of the fluid flow considering the influence of gravity. It means that the number of experiments reduce but still ensure that many experimental input parameters are still guaranteed, therefore ensuring proper description of the actual operation of the machine.

scholarly journals Mathematical Modelling and Tuberculosis: Advances in Diagnostics and Novel Therapies

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Alice Zwerling ◽  
Sourya Shrestha ◽  
David W. Dowdy
Keyword(s):  
Mathematical Modelling ◽  
New Technologies ◽  
Current Knowledge ◽  
Scale Up ◽  
Population Level ◽  
Decision Makers ◽  
Policy Choices ◽  
Critical Policy ◽  
Transmission Models

As novel diagnostics, therapies, and algorithms are developed to improve case finding, diagnosis, and clinical management of patients with TB, policymakers must make difficult decisions and choose among multiple new technologies while operating under heavy resource constrained settings. Mathematical modelling can provide helpful insight by describing the types of interventions likely to maximize impact on the population level and highlighting those gaps in our current knowledge that are most important for making such assessments. This review discusses the major contributions of TB transmission models in general, namely, the ability to improve our understanding of the epidemiology of TB. We focus particularly on those elements that are important to appropriately understand the role of TB diagnosis and treatment (i.e., what elements of better diagnosis or treatment are likely to have greatest population-level impact) and yet remain poorly understood at present. It is essential for modellers, decision-makers, and epidemiologists alike to recognize these outstanding gaps in knowledge and understand their potential influence on model projections that may guide critical policy choices (e.g., investment and scale-up decisions).

scholarly journals Hand-genital transmission of genital warts? An analysis of prevalence data

1995 ◽  
Vol 115 (1) ◽  
pp. 169-176 ◽  
Author(s):  
C. K. Fairley ◽  
N. J. Gay ◽  
A. Forbes ◽  
M. Abramson ◽  
S. M. Garland
Keyword(s):  
Genital Warts ◽  
Simple Explanation ◽  
Prevalence Data ◽  
Duration Of Infection ◽  
Hpv Types ◽  
Transmission Models

SummaryThe role of hand-genital transmission in the aetiology of genital warts is unclear. However this route is suggested by a number of observations including the relatively high proportion of genital warts in children which contain HPV types 1–4 (15% for children and 2% for adults). We compared two transmission models; one which assumes that hand-genital transmission occurs and one that it does not, and determined the conditions in which each model can reflect the available prevalence data. Hand-genital transmission provides a simple explanation of the observed differences in the proportions of genital warts containing HPV types 1–4 and 6/11 in children and adults. If hand-genital transmission does not occur, the observed difference could only be explained by an eightfold greater probability of transmission to children of types 1–4 than types 6/11, or by an eightfold greater duration of infection with types 1–4. Our findings provide support for the view that genital warts may be transmitted by hand-genital contact.

scholarly journals The Role of Model Complexity and the Performance of the Selection Criteria in Asymmetric Price Transmission Models

2013 ◽  
Vol 5 (3) ◽  
pp. 157-163
Author(s):  
Henry de-Graft Acquah
Keyword(s):  
Model Selection ◽  
Price Transmission ◽  
Model Complexity ◽  
Transmission Model ◽  
Correction Model ◽  
Asymmetric Price Transmission ◽  
True Model ◽  
Data Generating Process ◽  
Transmission Models

The role of model complexity in asymmetric price transmission model selection is not well understood. In order to appreciate the role of model complexity in model selection performance, this study fits alternative asymmetric price transmission models that differ in complexity to simulated data and evaluates the ability of the model selection method to recover the true model. The results of Monte Carlo experimentation suggest that in general BIC, CAIC and DIC were superior to AIC when the true data generating process was the Manning Error Correction model (MECM). However, AIC was more successful when the true model was the Complex Error Correction Model (CECM). The tendency of the complex model (CECM) to over fit the relatively simpler true asymmetric data generating process (MECM) is minimized in larger samples. The research findings demonstrate the role of model complexity in asymmetric price transmission model comparison and selection.

scholarly journals On the Inadequacies of the Magnetic Flare Theories and the Resolution of these Problems with the Convective Flare Theory

1989 ◽  
Vol 104 (2) ◽  
pp. 365-368
Author(s):  
Attila Crandpierro
Keyword(s):  
Magnetic Field ◽  
Short Review ◽  
Acceleration Region ◽  
Input Parameters ◽  
The Magnetic Field

I give here a short review of some of the main problems of the magnetic theories for the flare origin. I point out that the magnetic theories are unable to solve the problems of the energetics, height and compactness of the acceleration region, compresslve inflows, magnetic field structures, particle numbers, preflare upflows and the global cause of the flare origin. Then I outline the convective flare theory which have proposals for the solutions of these problems. I show here what is the role of the magnetic field at flare origins in the frame of the convective flare theory. The convective flare theory gives a deeper level understanding than the magnetic theories and therefore it also can supply us with the derivation of some input parameters and assumptions used for the magnetic theories and so it offers a wider perspective to understand the physics of the explosive astrophysical processes.

scholarly journals A non-dimensional study of the flow through co-rotating discs and performance optimization of a Tesla disc turbine

2017 ◽  
Vol 231 (8) ◽  
pp. 721-738 ◽  
Author(s):  
Abhijit Guha ◽  
Sayantan Sengupta
Keyword(s):  
Performance Optimization ◽  
Radial Pressure ◽  
Dual Role ◽  
Speed Ratio ◽  
Fluid Friction ◽  
Flow Angle ◽  
Dynamic Similarity ◽  
Rotating Discs ◽  
Input Parameters

This article presents a systematic and comprehensive computational fluid dynamic study for co-rotating discs and, Tesla turbines, in which the full benefit of similitude and scaling is extracted by expressing the results and analyses in terms of carefully formulated non-dimensional numbers—five input parameters and three output parameters. The work formulates a systematic design methodology for the optimum selection of input parameters for the rotor of a Tesla disc turbine that would satisfy practical constraints and deliver high values of power and efficiency. Many subtle flow physics (e.g. the identification of dynamic similarity number, inlet tangential speed ratio and inlet flow angle as the three most important non-dimensional input parameters, the secondary role of aspect ratio as a separate quantity independent of dynamic similarity number, and, the variation in the four fundamental components of the radial pressure difference) are critically explained. The present study establishes, for the first time, that unlike the flow in a conventional turbomachine in which fluid friction plays only a detrimental role, fluid friction plays a dual role in a Tesla disc turbine—a detrimental role in increasing the radial pressure drop (thus tending to decrease the efficiency) and a beneficial role by providing the sole mechanism for power production. This dual role is comprehensively analyzed and quantified in this work. The balance between this dual role of fluid friction gives rise to the optimum values of dynamic similarity number and inlet tangential speed ratio that maximize efficiency.

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