Polymer Solution with Very Low Relaxation Time: A Combined Numerical-Experimental Determination Strategy

2021 ◽  
Author(s):  
Guillaume Maîtrejean ◽  
Denis C D Roux ◽  
Maxime Rosello ◽  
Pascal Jay ◽  
Jean Xing ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Experimental Determination ◽  
Polymer Solution ◽  
Mixed Strategy ◽  
Numerical Approach ◽  
Physical Parameters ◽  
Test Case ◽  
Ink Jet ◽  
Elastic Polymer ◽  
Numerical Strategy

Abstract For very low relaxation time (i.e. lesser than a microsecond) viscoelastic fluid experimental determination is difficult, if not impossible. In the present work the relaxation time measurement of a weakly elastic polymer solution, too low to be measured using classical rheometry techniques, is assessed using a mixed experimental-numerical strategy. First the fluid is rheologically assessed, by measuring its shear viscosity, surface tension and density. Then the relaxation time is determined by comparing the jetting of polymer solution from a Continuous Ink-Jet (CIJ) device experimentally and numerically. The numerical approach is first validated using test case and a viscoelastic Oldroyd-B model is then used to model the experimental solution. The relaxation time is then a parameter allowing us to fit numerical simulation onto experimental results. This mixed strategy is particularly convenient for weakly elastic solution for which physical parameters can not be measured using experimental rheometry setup.

scholarly journals Flurbiprofen: A Study of the Behavior of the Scalemate by Chromatography, Sublimation, and NMR

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 543
Author(s):  
Magdalena Kwiatkowska ◽  
Alicja Wzorek ◽  
Anna Kolbus ◽  
Mariusz Urbaniak ◽  
Jianlin Han ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Preparative Thin Layer Chromatography ◽  
Transverse Relaxation Time ◽  
Size Exclusion ◽  
Test Case ◽  
Ionization Mass ◽  
Chiral Drugs ◽  
Good Test ◽  
Exclusion Chromatography ◽  
Medium Pressure Liquid Chromatography

2-(2-Fluoro-4-biphenyl) propionic acid (flurbiprofen), from the phenylalkanoic acid family of nonsteroidal anti-inflammatory drugs (NSAID’s), is currently on the pharmaceutical market as a racemate. This racemic compound was tested for its propensity to undergo the self-disproportionation of enantiomers (SDE) phenomenon by various forms of chromatography (SDEvC), such as routine gravity-driven column chromatography, medium-pressure liquid chromatography (MPLC), preparative thin-layer chromatography (PTLC), and size-exclusion chromatography (SEC), as well as by sublimation (SDEvS). Furthermore, examination by nuclear magnetic resonance (NMR) in various solvents found that flurbiprofen exhibited the phenomenon of self-induced diastereomeric anisochronism (SIDA). By measurement of the diffusion coefficient (D), the longitudinal relaxation time (T1), and the transverse relaxation time (T2) using NMR, as well as by electrospray ionization-mass spectrometry (ESI-MS) examinations, the preferred intermolecular association was found to be solvent dependent, e.g., heterochiral association was preferred in toluene, while homochiral association was preferred in more polar solvents. This study also attempted, unsuccessfully, to correlate the NMR measurements of flurbiprofen with chromatographic outcomes for the rationalization and prediction of chromatographic results based on NMR measurements. Because the intermolecular hydrogen bonding of the acid groups in flurbiprofen overwhelmingly predominates over other intermolecular interactions, flurbiprofen seemed to represent a good test case for this idea. The behavior of scalemic samples of flurbiprofen is important, as, although it is currently dispensed as a racemate, clinical applications of the R enantiomer have been investigated. SDEvC and SDEvS both have ramifications for the preparation, handling, and storage of enantioenriched flurbiprofen, and this concern applies to other chiral drugs as well.

scholarly journals Modelling of Applied Magnetic Field and Thermal Radiations Due to the Stretching of Cylinder

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1077
Author(s):  
Muhammad Tamoor ◽  
Muhammad Kamran ◽  
Sadique Rehman ◽  
Aamir Farooq ◽  
Rewayat Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Skin Friction Coefficient ◽  
Physical Parameters ◽  
Boundary Layer Equations ◽  
Convective Parameter ◽  
Momentum And Heat Transfer ◽  
Dimensional Boundary

In this study, a numerical approach was adopted in order to explore the analysis of magneto fluid in the presence of thermal radiation combined with mixed convective and slip conditions. Using the similarity transformation, the axisymmetric three-dimensional boundary layer equations were reduced to a self-similar form. The shooting technique, combined with the Range–Kutta–Fehlberg method, was used to solve the resulting coupled nonlinear momentum and heat transfer equations numerically. When physically interpreting the data, some important observations were made. The novelty of the present study lies in finding help to control the rate of heat transfer and fluid velocity in any industrial manufacturing processes (such as the cooling of metallic plates). The numerical results revealed that the Nusselt number decrease for larger Prandtl number, curvature, and convective parameters. At the same time, the skin friction coefficient was enhanced with an increase in both slip velocity and convective parameter. The effect of emerging physical parameters on velocity and temperature profiles for a nonlinear stretching cylinder has been thoroughly studied and analyzed using plotted graphs and tables.

scholarly journals NETWORK MODELLING AND SEMANTIC 3D CITY MODELS: TESTING THE MATURITY OF THE UTILITY NETWORK ADE FOR CITYGML WITH A WATER NETWORK TEST CASE

2018 ◽  
Vol IV-4 ◽  
pp. 13-20 ◽  
Author(s):  
I. Boates ◽  
G. Agugiaro ◽  
A. Nichersu
Keyword(s):  
Relational Database ◽  
Data Model ◽  
Database Schema ◽  
Future Research ◽  
Physical Parameters ◽  
Test Case ◽  
Network Modelling ◽  
Complex Development ◽  
Relational Database Schema ◽  
Utility Network

<p><strong>Abstract.</strong> Recent advances in semantic 3D city modelling and a demand from utility network operators for multi-utility data models integration have contributed to the emergence of an open Application Domain Extension (ADE) of the CityGML data model tailored to multiple types of utility networks. This extension, called the Utility Network ADE, is still in active development. However, work is already well underway to create data samples and to develop methods of modelling thereupon. In this paper, a mapping of the Utility Network ADE data model to a relational database schema is introduced. A sample of a freshwater network using the Utility Network ADE and based on data from the city of Nanaimo, Canada, is also presented. This sample has also been imported into a relational database schema built upon the 3DCityDB (a database implementation of CityGML) extended with a schema of the Utility Network ADE. Further to this, a series of basic network analysis functions have been defined and implemented in SQL to interact with the database so as to carry out sample atomic processes involved in network modelling, such as reading semantic properties of elements, calculating composite physical parameters of the network as a whole, and performing simple topological routing to serve as a guiding example for further and more complex development. A brief outlook is also presented, suggesting areas with high potential for future research and development of this nascent data model.</p>

Numerical Optimization of the Thermoelectric Cooling Devices

2006 ◽  
Vol 129 (3) ◽  
pp. 339-347 ◽  
Author(s):  
Boris Abramzon
Keyword(s):  
Electric Current ◽  
Optimization Problems ◽  
Random Search ◽  
Thermal Conductance ◽  
Numerical Approach ◽  
Physical Parameters ◽  
Optimization Approach ◽  
Independent Variables ◽  
Adaptive Random Search ◽  
Optimization Search

The present study proposes a unified numerical approach to the problem of optimum design of the thermoelectric devices for cooling electronic components. The standard mathematical model of a single-stage thermoelectric cooler (TEC) with constant material properties is employed. The model takes into account the thermal resistances from the hot and cold sides of the TEC. Values of the main physical parameters governing the TEC performance (Seebeck coefficient, electrical resistance, and thermal conductance) are derived from the manufacturer catalog data on the maximum achievable temperature difference, and the corresponding electric current and voltage. The optimization approach is illustrated with several examples for different design objective functions, variables, and constraints. The objective for the optimization search is the maximization of the total cooling rate or the performance coefficient of the cooling device. The independent variables for the optimization search are as follows: The number of the thermoelectric modules, the electric current, and the cold side temperature of the TEC. Additional independent variables in other cases include the number of thermoelectric couples and the area-to-height ratio of the thermoelectric pellet. In the present study, the optimization problems are solved numerically using the so-called multistart adaptive random search method.

Sensitivity of modeled microphysics to stochastically perturbed parameters

2021 ◽  
Author(s):  
Tomislava Vukicevic ◽  
Aleksa Stankovic ◽  
Derek Posselt
Keyword(s):  
Parameter Uncertainty ◽  
Squall Line ◽  
Physical Parameters ◽  
Test Case ◽  
Modeling Framework ◽  
Water Path ◽  
Second Moment ◽  
Ensemble Simulations ◽  
Parameter Perturbations ◽  
Stochastically Perturbed

&lt;p&gt;This study investigates sensitivity of&amp;#160; cloud and precipitation parameterized microphysics&amp;#160; to stochastic representation of parameter uncertainty as formulated by the stochastically perturbed parameterization (SPP) scheme.&amp;#160; SPP is applied to multiple microphysical parameters within a lagrangian column model, used in several prior published studies to characterize &amp;#160;parameter uncertainty by means of multivariate nonlinear inversions using remote sensing observations. The 1D column microphysics model is forced with prescribed time-varying profiles of temperature, humidity and vertical velocity.&amp;#160; This modeling framework allows for investigation of the effect of changes in model physics parameters on the model output in isolation from any feedback to the cloud-scale dynamics.&lt;/p&gt;&lt;p&gt;The test case selected in this study of an idealized representation of mid-latitude squall-line convection is the same as in the prior studies. This enabled using the estimates of multi-parameter distributions from the inversions in the prior studies as the basis for setting the second-moment statistics in the SPP scheme implementation. Additionally impacts of the non-stochastic and stochastic multi-parameter representation of parameterization uncertainty on the microphysics model solution could be directly compared.&lt;/p&gt;&lt;p&gt;The sensitivity experiments with the SPP scheme involve ensemble simulations where each member is evolved with a different stochastic sequence of parameter perturbations, as is done in the standard practice with this scheme.&amp;#160; The experiments explore impacts of using different decorrelation times and different estimates of second moment statistics for the parameter perturbations.&amp;#160; These include uncorrelated perturbations between the parameters for several values of variance for each parameter and correlated perturbations based on multi-parameter empirical statistical distributions from the prior studies.&amp;#160; The selection of physical parameters for the perturbations is based on the significance of their impacts derived from the prior studies .&amp;#160;&lt;/p&gt;&lt;p&gt;The results are evaluated in terms of changes to the ensemble mean and variance of time evolving profiles of hydrometeor mass quantities, the microphysics processes within the model as well as in terms of the simulated column integral microphysics-sensitive satellite-based&amp;#160; observables. The latter include PR (Precipitation Rate) , LWP (Liquid Water Path), IWP (Ice water path), TOA-LW and TOA-SW (-Long and -Short Wave, respectively).&amp;#160; In each experiment six parameters were perturbed.&lt;/p&gt;&lt;p&gt;The analyses performed so far indicate a high sensitivity of the microphysics model to the SPP scheme. The ensemble simulations with the standard uncorrelated parameter perturbations exhibit a significant bias relative to the control simulation which uses the unperturbed parameters.&amp;#160; For the selected test case the skewness toward small parameter values in the SPP sampling based on the underlying log-normal distributions leads to less precipitating ice and more precipitating liquid and accumulated precipitation. The response is due to nonlinear relationships between the parameters and modeled microphysics output. The changes in microphysics output result in large mean changes in PR, LWP, IWP, TOA- LW and SW, suggesting a potential for using these and other microphysics sensitive satellite observations to evaluate and if needed correct properties of the underlying sampling distribution in the stochastic scheme.&amp;#160; Further analyses will be presented at the conference.&lt;/p&gt;

scholarly journals Squeal Frequency of a Railway Disc Brake Evaluation by FE Analyses

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
F. Cascetta ◽  
F. Caputo ◽  
A. De Luca
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Experimental Tests ◽  
Numerical Approach ◽  
System Stability ◽  
Brake System ◽  
Physical Parameters ◽  
Disc Brake ◽  
Complex Eigenvalues ◽  
The Stability

This paper deals with the development of a numerical model, based on the Finite Element (FE) theory for the prediction of the squeal frequency of a railway disc brake. The analytical background has been discussed and presented, as well as the most efficient methods for evaluating the system stability; the attention has been paid particularly to the complex eigenvalues method, which has been adopted within this paper to investigate the railway disc brake system. Numerical results have been compared with measurements from experimental tests in order to validate the proposed numerical approach. At the end of this work, a sensitivity analysis, aimed at understanding the effects of some physical parameters influencing the stability of the brake system and the squeal propensity, has been carried out.

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