scholarly journals Delayed Leidenfrost phenomenon during impact of elastic fluid droplets

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200556
Author(s):  
Purbarun Dhar ◽  
Soumya Ranjan Mishra ◽  
Ajay Gairola ◽  
Devranjan Samanta
Keyword(s):  
Weber Number ◽  
Polymer Concentration ◽  
Time Period ◽  
Increasing Trend ◽  
Viscoelastic Effects ◽  
Critical Weber Number ◽  
Leidenfrost Temperature ◽  
Elastic Fluids ◽  
The Impact

This article highlights the role of non-Newtonian (elastic) effects on the droplet impact phenomenon at temperatures considerably higher than the boiling point, especially at or above the Leidenfrost regime. The Leidenfrost point (LFP) was found to decrease with an increase in the impact Weber number (based on the velocity just before the impact) for fixed polymer (polyacrylamide) concentrations. Water droplets fragmented at very low Weber numbers (approx. 22), whereas the polymer droplets resisted fragmentation at much higher Weber numbers (approx. 155). We also varied the polymer concentration and observed that, up to 1000 ppm, the LFP was higher than that for water. This signifies that the effect can be delayed by the use of elastic fluids. We have shown the possible role of elastic effects (manifested by the formation of long lasting filaments) during retraction in the increase of the LFP. However, for 1500 ppm, the LFP was lower than that for water, but had a similar residence time during the initial impact. In addition, we studied the role of the Weber number and viscoelastic effects on the rebound behaviour at 405°C. We observed that the critical Weber number up to the point at which the droplet resisted fragmentation at 405°C increased with the polymer concentration. In addition, for a fixed Weber number, the droplet rebound height and the hovering time period increased up to 500 ppm, and then decreased. Similarly, for fixed polymer concentrations like 1000 and 1500 ppm, the rebound height showed an increasing trend up to certain a certain Weber number and then decreased. This non-monotonic behaviour of rebound heights was attributed to the observed diversion of the rebound kinetic energy to rotational energy during the hovering phase. Finally, a relationship between the non-dimensional Leidenfrost temperature and the associated Weber and Weissenberg numbers is developed, and a scaling relation is proposed.

scholarly journals Viscoelastic effects on the jetting–dripping transition in co-flowing capillary jets

2008 ◽  
Vol 610 ◽  
pp. 249-260 ◽  
Author(s):  
J. M. MONTANERO ◽  
A. M. GAÑÁN-CALVO
Keyword(s):  
Dispersion Relation ◽  
Weber Number ◽  
Temporal Stability ◽  
Temporal Analysis ◽  
Viscoelastic Effects ◽  
Critical Weber Number ◽  
Lateral Mode ◽  
Spatio Temporal ◽  
Capillary Jets ◽  
Axisymmetric Perturbations

Linear hydrodynamics stability analysis is used to determine the influence of elasticity on the jetting–dripping transition and on the temporal stability of non-axisymmetric modes in co-flowing capillary jets. The critical Weber number for which axisymmetric perturbations undergo a transition from convective to absolute instability is calculated from the spatio-temporal analysis of the dispersion relation for Oldroyd-B liquids, as a function of the density and viscosity ratios, and the Reynolds and Deborah numbers. Elasticity increases the critical Weber number for all cases analysed and, consequently, fosters the transition from jetting to dripping. The temporal analysis of the dispersion relation for them= 1 lateral mode shows that elasticity does not affect its stability.

scholarly journals Assessing the Impact of Corporate Governance on Non-Performing Loans: Empirical Analysis of the Listed Commercial Banks of Pakistan

2019 ◽  
Vol IV (III) ◽  
pp. 188-196
Author(s):  
Ihtesham Khan ◽  
Muhammad Ilyas ◽  
Shehzad Khan
Keyword(s):  
Corporate Governance ◽  
Banking Industry ◽  
Annual Reports ◽  
Governance System ◽  
Nonperforming Loans ◽  
Time Period ◽  
Corporate Governance System ◽  
The Impact ◽  
Code Compliance

Financial crisis shows the ambiguous role of the corporate governance system. Hence, the main purpose of this paper is to assess the impact of corporate governance on Non-performing loans of the banking industry of Pakistan. The time period selected from 2006 to 2016 and source of data is annual reports of respective banks and the World Bank. In order to explain the relationship between the governance system and non-performing loans used descriptive, correlational and panel data analyses. The results revealed a negative and significant effect of corporate governance on nonperforming loans of sample firms of the study. Therefore, suggested for the banking industry of Pakistan to implement and make sure their reports according to corporate governance code compliance to control non-performing loans.

Meal fatty acids and postprandial vascular reactivity

2007 ◽  
Vol 35 (3) ◽  
pp. 451-453 ◽  
Author(s):  
K.G. Jackson ◽  
C.K. Armah ◽  
A.M. Minihane
Keyword(s):  
Fatty Acids ◽  
Vascular Reactivity ◽  
Vascular Dysfunction ◽  
Postprandial Lipaemia ◽  
Fasted State ◽  
Important Target ◽  
Time Period ◽  
The Impact ◽  
Progression Of Atherosclerosis

With increasing recognition of the pivotal role of vascular dysfunction in the progression of atherosclerosis, the vasculature has emerged as an important target for dietary therapies. Recent studies have indicated that chronic fatty acid manipulation alters vascular reactivity, when measured after an overnight fast. However, individuals spend a large proportion of the day in the postprandial (non-fasted) state. Several studies have shown that high fat meals can impair endothelial function within 3–4 h, a time period often associated with peak postprandial lipaemia. Although the impact of meal fatty acids on the magnitude and duration of the postprandial lipaemic response has been extensively studied, very little is known about their impact on vascular reactivity after a meal.

Reassessing the Impact of Risk Management Capabilities on Firm Value: A Stakeholders Perspective

2020 ◽  
Vol 6 (2) ◽  
pp. 81
Author(s):  
Asad Khan ◽  
Muhammad Ibrahim Khan ◽  
Niaz Ahmed Bhutto
Keyword(s):  
Risk Management ◽  
Value Creation ◽  
Firm Value ◽  
Positive Impact ◽  
Financial Firms ◽  
Management Capability ◽  
Time Period ◽  
Management Capabilities ◽  
The Impact

Despite the pivotal role of risk management very limited research is carry out on the issue of firm’s risk management capability and value creation. This study aims to analyze the impact of firms risk management capabilities on firm performance and cost. Using panel data technique a sample of 301 non financial firms was analyzed for the time period on five years starting from 2011 to 2015. We assert that effective risk capabilities have positive impact on all stakeholders. The effective risk management capabilities guarantee more resilience to exogenous and endogenous risks. Our findings will have a significant impact on existing literature, by extending the existing knowledge of firm’s risk management capabilities into the domain of diverse stakeholders and resources adjustment.

scholarly journals Frequency of Dental Caries in Four Historical Populations from the Chalcolithic to the Middle Ages

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
A.-M. Grimoud ◽  
S. Lucas ◽  
A. Sevin ◽  
P. Georges ◽  
O. Passarrius ◽  
...  
Keyword(s):  
Middle Ages ◽  
Food Access ◽  
Middle Age ◽  
Population Sample ◽  
Historical Period ◽  
South West ◽  
Time Period ◽  
Carious Lesions ◽  
The Impact

The majority of dental carie studies over the course of historical period underline mainly the prevalence evolution, the role of carbohydrates consumption and the impact of access to dietary resources. The purpose of the present investigation was to compare population samples from two archaeological periods the Chacolithic and Middle Age taking into account the geographical and socio economical situation. The study concerned four archaelogical sites in south west France and population samples an inlander for the Chalcolithic Age, an inlander, an costal and urban for the Middle Age. The materials studied included a total of 127 maxillaries, 103 mandibles and 3316 teeth. Data recorded allowed us to display that the Chalcolithic population sample had the lowest carie percentage and the rural inlander population samples of Middle Age the highest; in all cases molars were teeth most often affected. These ones differences could be explained according to time period, carious lesions were usually less recorded in the Chalcolithic Age than the Middle because of a lesser cultivation of cereals like in les Treilles Chacolithic population sample. In the Middle Age population samples, the rural inland sample Marsan showed the highest frequency of caries and ate more cereal than the coastal Vilarnau and the poor urban St Michel population samples, the first one ate fish and Mediterranean vegetal and fruits and the second one met difficulties to food access, in both cases the consumption of carbohydrates was lesser than Marsan population sample who lived in a geographical land convice to cereals cultivation.

scholarly journals Влияние коагуляции капель воды на их распределение по размерам в рабочей части аэрохолодильной установки

2019 ◽  
Vol 89 (4) ◽  
pp. 491
Author(s):  
М.В. Тимофеева
Keyword(s):  
Weber Number ◽  
Operating Regime ◽  
Motion Direction ◽  
Runge Kutta Method ◽  
Flux Motion ◽  
Ground Conditions ◽  
Air Cooler ◽  
Critical Weber Number ◽  
Polydisperse Mixture ◽  
The Impact

AbstractMathematical simulation of coagulation of droplets of finite number of size fractions of a polydisperse mixture, injected by a nozzle into the region of an air-cooler unit along air flux motion direction, was performed. Sets of differential equations describing dependences of droplet fraction concentrations, their densities, as well as masses of droplets in each fraction on time, were solved using the fourth-order Runge–Kutta method. Negligibility of the impact of heat-mass exchange between the substance of droplets and surrounding air on changing their sizes during motion from the nozzle to the operating part of the device is shown. Decomposition of droplets is not simulated, since the critical Weber number is not reached in the considered operating regime of the air-cooler. Results of simulation of droplet coagulation in turbulent air flux show that distributions of droplets by sizes near the surface of a spraying nozzle do not coincide, which proves the necessity of accounting this process in simulation of ice coating of aircrafts in ground conditions.

scholarly journals Exponential Organizations Hypergrowth Strategies and Firm Performance: The Moderating Role of Firm Size and Marketing Spending

2021 ◽  
Vol 5 (7) ◽  
pp. 112-121
Author(s):  
Hamza Tubaishat* ◽  
◽  
Refaat Faouri ◽  
Hussam Alshammari ◽  
◽  
...  
Keyword(s):  
Firm Performance ◽  
Firm Size ◽  
Business Models ◽  
International Markets ◽  
Time Period ◽  
Fixed Assets ◽  
Marketing Spending ◽  
The Impact ◽  
Moderating Role

With the increasing concerns of hypergrowth in order to compete in the international markets and survive, this study aids all firms in various industries, entrepreneurs and decision makers and draw their attention to business models and hypergrowth strategies that are applied by the fast-growing firms in the world. This study investigates the impact of hypergrowth strategy- leveraging assets that developed by Salim, (2014) and firm performance in exponential organizations; The sample size tested constituted of (34) exponential organizations form the fortune 500 and multiple regressions via Stata version 15 was applied for the time period of (2016-2019). Preliminary analysis was conducted to check the assumptions related to the regression models which include unit root, autocorrelation, residuals normality and heteroskedasticity issues. The results showed significant positive relationships between Growth in Fixed Assets (leveraging Assets strategy) and firm performance measured by ROA and ROE whereas, the moderating role of marketing spending and firm size showed insignificant impact in the relationship.

scholarly journals Exponential Organizations Hypergrowth Strategies And Firm Performance: The Moderating Role of Firm Size And Marketing Spending

2021 ◽  
Vol 5 (7) ◽  
pp. 112-121
Author(s):  
Hamza Tubaishat ◽  
Refaat Faouri ◽  
Hussam Alshammar
Keyword(s):  
Firm Performance ◽  
Firm Size ◽  
Business Models ◽  
International Markets ◽  
Time Period ◽  
Fixed Assets ◽  
Marketing Spending ◽  
The Impact ◽  
Moderating Role

With the increasing concerns of hypergrowth in order to compete in the international markets and survive, this study aids all firms in various industries, entrepreneurs and decision makers and draw their attention to business models and hypergrowth strategies that are applied by the fast-growing firms in the world. This study investigates the impact of hypergrowth strategy- leveraging assets that developed by Salim, (2014) and firm performance in exponential organizations; The sample size tested constituted of (34) exponential organizations form the fortune 500 and multiple regressions via Stata version 15 was applied for the time period of (2016-2019). Preliminary analysis was conducted to check the assumptions related to the regression models which include unit root, autocorrelation, residuals normality and heteroskedasticity issues. The results showed significant positive relationships between Growth in Fixed Assets (leveraging Assets strategy) and firm performance measured by ROA and ROE whereas, the moderating role of marketing spending and firm size showed insignificant impact in the relationship.

scholarly journals Evolution and epidemic spread of SARS-CoV-2 in Brazil

2020 ◽  
Author(s):  
Darlan S. Candido ◽  
Ingra M. Claro ◽  
Jaqueline G. de Jesus ◽  
William M. Souza ◽  
Filipe R. R. Moreira ◽  
...  
Keyword(s):  
Average Distance ◽  
Virus Transmission ◽  
Joint Analysis ◽  
Epidemic Spread ◽  
Urban Centers ◽  
Genomic Dataset ◽  
Time Period ◽  
The Impact ◽  
Transmission Models

AbstractBrazil currently has one of the fastest growing SARS-CoV-2 epidemics in the world. Due to limited available data, assessments of the impact of non-pharmaceutical interventions (NPIs) on virus transmission and epidemic spread remain challenging. We investigate the impact of NPIs in Brazil using epidemiological, mobility and genomic data. Mobility-driven transmission models for São Paulo and Rio de Janeiro cities show that the reproduction number (Rt) reached below 1 following NPIs but slowly increased to values between 1 to 1.3 (1.0–1.6). Genome sequencing of 427 new genomes and analysis of a geographically representative genomic dataset from 21 of the 27 Brazilian states identified >100 international introductions of SARS-CoV-2 in Brazil. We estimate that three clades introduced from Europe emerged between 22 and 27 February 2020, and were already well-established before the implementation of NPIs and travel bans. During this first phase of the epidemic establishment of SARS-CoV-2 in Brazil, we find that the virus spread mostly locally and within-state borders. Despite sharp decreases in national air travel during this period, we detected a 25% increase in the average distance travelled by air passengers during this time period. This coincided with the spread of SARS-CoV-2 from large urban centers to the rest of the country. In conclusion, our results shed light on the role of large and highly connected populated centres in the rapid ignition and establishment of SARS-CoV-2, and provide evidence that current interventions remain insufficient to keep virus transmission under control in Brazil.One Sentence SummaryJoint analysis of genomic, mobility and epidemiological novel data provide unique insight into the spread and transmission of the rapidly evolving epidemic of SARS-CoV-2 in Brazil.

The Dynamics of Drop Impact

2002 ◽  
Author(s):  
Christophe Josserand
Keyword(s):  
Liquid Layer ◽  
Weber Number ◽  
Stokes Equations ◽  
Early Time ◽  
Mass Conservation ◽  
Viscous Effects ◽  
Time Dynamics ◽  
Similar Solutions ◽  
The Impact

Inkjet printing, rainfall, droplet collision in combustion chambers are different forms of drop impacts. The whole dynamics of these impacts is complex and remains far to be fully understood. In particular the role of the viscosity of the drop liquid is still hard to exhibit. In one hand, the early time of the impact should be considered inviscid, and viscous free calculation give a fair approximation of the short time dynamics. On the other hand, experimental evidences show that the transition between splashing dynamics and deposition is controlled by a so-called splashing parameter K = We · sqrt(Re), where the viscosity enter through the Reynolds number Re (We being the Weber number). Therefore the role of the viscosity for the early time of the impact needs to be elucidated. We will present numerical simulations of the impact of a drop on a liquid layer thanks to a volume of fluid technique (VOF), where the Navier-Stokes equations are solved for both liquid and gas phases. For a given Weber number, we will vary only the viscosity so that viscous effects can be emphasized. The calculation will also determine the relative spreading of the drop inside the liquid layer. For splashing behaviors, a jet is emitted soon after the initiation of the impact; contrarily, no jets are present when deposition happens. The pressure field and the velocity field are studied near the neck of the impact and show no specific dependance on the viscosity. However, viscous effects are observed through the diffusion of the vorticity from the interface into the liquid bulk. Therefore, the viscous length lv = sqrt(vt) controls the gradient fields at the impact and we observe that the width of the emitted jet is determined by this length. Therefore, applying mass conservation to a dynamical solution where a jet of width lv is created, we can estimate the balance between mass ejected by the falling drop with mass coming from a retracting jet. The growth of a jet is thus controlled by this mass balance and the splashing parameter law is retrieved. In particular, the viscous effects appear in the theory as a singular perturbation of the inviscid impact dynamics. Self-similar solutions of the impact are therefore considered in specific gometries. More information at http://www.lmm.jussieu.fr/MEMBRES/JOSSERAND/josserand.html.

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