scholarly journals Flow and Thermal Properties of Stevia Powder

2018 ◽  
Vol 21 (2) ◽  
pp. 51-55 ◽  
Author(s):  
Ajit K. Mahapatra ◽  
Agnes J. Kapsoiyo ◽  
Sierra C. Birmingham ◽  
Daniel Ekefre ◽  
Bipul K. Biswas
Keyword(s):  
Thermal Properties ◽  
Internal Friction ◽  
Polynomial Regression ◽  
Stevia Rebaudiana ◽  
Calorific Value ◽  
Flow Index ◽  
Published Data ◽  
Mean Flow ◽  
Angle Of Internal Friction ◽  
The Mean

Abstract Stevia (Stevia rebaudiana Bertoni) has recently received a lot of attention as a sweetener due to its taste and low calorific value. Flow and thermal properties of foods play a significant role in the quantitative analysis of unit operations in the food industry. However, there are no published data available on flow and thermal properties of stevia powder. Powder Flow Tester and KD2 Pro Thermal Properties Analyzer were used to determine the flow and thermal properties of stevia powder, respectively, at different moisture contents (4.96%, 9.68%, 13.99%, 20.08%, and 25.79%, w.b.). Mean angle of internal friction of stevia powder ranged from 41.13° to 46.3°. The mean effective angle of internal friction ranged from 47.8° to 52.5° and the mean flow index ranged from 0.27 to 0.48. Mean thermal conductivity of stevia powder ranged from 0.091 W·m-2·K-1 to 0.115 W·m-2·K-1. Mean thermal diffusivity ranged from 0.103 mm2·s-1 to 0.121 mm2·s-1 and mean volumetric specific heat ranged from 0.865 MJ·m-3·K-1 to 1.019 MJ·m-3·K-1. Polynomial regression models were developed to predict flow and thermal properties of stevia powder using moisture content of stevia powder.

scholarly journals A Comparative Analysis of the Flow Properties between Two Alumina-Based Dry Powders

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Milene Minniti de Campos ◽  
Maria do Carmo Ferreira
Keyword(s):  
Internal Friction ◽  
Moisture Content ◽  
Ceramic Powder ◽  
Morphological Characteristics ◽  
Angle Of Repose ◽  
Wall Friction ◽  
Flow Index ◽  
Alumina Powder ◽  
Flow Properties ◽  
Angle Of Internal Friction

We measured and compared the flow properties of two alumina-based powders. The alumina powder (AP) is irregularly shaped and has a smooth surface and moisture content of 0.16% (d.b.), and the ceramic powder (CP), obtained after atomization in a spray dryer, is spherical and has a rough surface and moisture content of 1.07%. We measured the Hausner ratio (HR), the static angle of repose (AoR), the flow index (FI), the angle of internal friction, and the wall's friction angle. The properties measured using aerated techniques (AoR and HR) demonstrated that AP presents true cohesiveness (and therefore a difficult flow), while CP presents some cohesiveness and its flow might be classified as half way between difficult and easy flow. Their FI values, which were obtained using a nonaerated technique, enable us to classify the alumina as cohesive and the ceramic powder as an easy-flow powder. The large mean diameter and morphological characteristics of CP reduce interparticle forces and improve flowability, in spite of the higher moisture content of their granules. The angles of internal friction and of wall friction were not significantly different when comparing the two powders.

scholarly journals Reliability of the mean flow index (Mx) for assessing cerebral autoregulation in healthy volunteers

2021 ◽  
Vol 9 (12) ◽  
Author(s):  
Markus H. Olsen ◽  
Christian G. Riberholt ◽  
Ronni R. Plovsing ◽  
Kirsten Møller ◽  
Ronan M. G. Berg
Keyword(s):  
Healthy Volunteers ◽  
Cerebral Autoregulation ◽  
Flow Index ◽  
Mean Flow ◽  
The Mean

Reliability and validity of the mean flow index (Mx) for assessing cerebral autoregulation in humans: A systematic review of the methodology

2021 ◽  
pp. 0271678X2110525
Author(s):  
Markus Harboe Olsen ◽  
Christian Gunge Riberholt ◽  
Jesper Mehlsen ◽  
Ronan MG Berg ◽  
Kirsten Møller
Keyword(s):  
Systematic Review ◽  
Cerebral Autoregulation ◽  
Reliability And Validity ◽  
Flow Index ◽  
Mean Flow ◽  
Optimal Method ◽  
Discriminatory Ability ◽  
Wide Range ◽  
Repeatability And Reproducibility ◽  
The Mean

Cerebral autoregulation is a complex mechanism that serves to keep cerebral blood flow relatively constant within a wide range of cerebral perfusion pressures. The mean flow index (Mx) is one of several methods to assess dynamic cerebral autoregulation, but its reliability and validity have never been assessed systematically. The purpose of the present systematic review was to evaluate the methodology, reliability and validity of Mx. Based on 128 studies, we found inconsistency in the pre-processing of the recordings and the methods for calculation of Mx. The reliability in terms of repeatability and reproducibility ranged from poor to excellent, with optimal repeatability when comparing overlapping recordings. The discriminatory ability varied depending on the patient populations; in general, those with acute brain injury exhibited a higher Mx than healthy volunteers. The prognostic ability in terms of functional outcome and mortality ranged from chance result to moderate accuracy. Since the methodology was inconsistent between studies, resulting in varying reliability and validity estimates, the results were difficult to compare. The optimal method for deriving Mx is currently unknown.

Engineering properties of cotton stalks (Gossypium hirsitum L.)

2015 ◽  
Vol 49 (5) ◽  
Author(s):  
Gagandeep Kaur Sidhu ◽  
Sandhya
Keyword(s):  
Thermal Properties ◽  
Calorific Value ◽  
Mean Value ◽  
Ash Content ◽  
Engineering Properties ◽  
Equivalent Diameter ◽  
True Density ◽  
Cotton Stalk ◽  
Cotton Stalks ◽  
The Mean

Different physical and thermal properties of chaffed and ground cotton stalks were evaluated. The moisture content of chaffed and ground cotton stalk was 10.01 and 12.31% respectively. The size of chaffed cotton stalk was 40.3 mm, whereas the equivalent diameter of chaffed and ground cotton stalk was estimated as 30.5 and 4.5 mm respectively. The mean value of bulk density of chaffed and ground cotton stalks was 206.16 and 217.30 kg/m<sup>3</sup>, whereas true density varied between 727.70 and 313.60 kg/m<sup>3</sup>. The porosity of chaffed cotton stalks was estimated to be greater than ground cotton stalks. Angles of repose for chaffed and ground cotton stalks were 43.18 and 34.35<sup>o</sup> respectively. The coefficient of internal friction for ground cotton stalks was 0.85, whereas coefficient of external friction for chaffed and ground cotton stalks was estimated to be 0.54 and 0 .68 respectively. The calorific value of chaffed and ground cotton stalks came out to be 16.70, 16.79MJ/kg respectively. Ash content of both chaffed and ground cotton stalks were almost same i.e. 6.93 and 6.87 % respectively.

Simple explicit model of liquid mean flow in region above axial impeller

1985 ◽  
Vol 50 (11) ◽  
pp. 2396-2410
Author(s):  
Miloslav Hošťálek ◽  
Ivan Fořt
Keyword(s):  
Vortex Flow ◽  
Flow Model ◽  
Quantitative Agreement ◽  
Mean Flow ◽  
Flat Bottom ◽  
Proposed Model ◽  
Minimum Number ◽  
The Mean ◽  
Model Equations ◽  
Radial Circulation

The study describes a method of modelling axial-radial circulation in a tank with an axial impeller and radial baffles. The proposed model is based on the analytical solution of the equation for vortex transport in the mean flow of turbulent liquid. The obtained vortex flow model is tested by the results of experiments carried out in a tank of diameter 1 m and with the bottom in the shape of truncated cone as well as by the data published for the vessel of diameter 0.29 m with flat bottom. Though the model equations are expressed in a simple form, good qualitative and even quantitative agreement of the model with reality is stated. Apart from its simplicity, the model has other advantages: minimum number of experimental data necessary for the completion of boundary conditions and integral nature of these data.

scholarly journals Technical note: Inherent benchmark or not? Comparing Nash–Sutcliffe and Kling–Gupta efficiency scores

2019 ◽  
Vol 23 (10) ◽  
pp. 4323-4331 ◽  
Author(s):  
Wouter J. M. Knoben ◽  
Jim E. Freer ◽  
Ross A. Woods
Keyword(s):  
Time Series ◽  
Coefficient Of Variation ◽  
Ad Hoc ◽  
Model Performance ◽  
Technical Note ◽  
Mean Flow ◽  
Model Adequacy ◽  
Robust Model ◽  
The Mean ◽  
Adequacy Assessment

Abstract. A traditional metric used in hydrology to summarize model performance is the Nash–Sutcliffe efficiency (NSE). Increasingly an alternative metric, the Kling–Gupta efficiency (KGE), is used instead. When NSE is used, NSE = 0 corresponds to using the mean flow as a benchmark predictor. The same reasoning is applied in various studies that use KGE as a metric: negative KGE values are viewed as bad model performance, and only positive values are seen as good model performance. Here we show that using the mean flow as a predictor does not result in KGE = 0, but instead KGE =1-√2≈-0.41. Thus, KGE values greater than −0.41 indicate that a model improves upon the mean flow benchmark – even if the model's KGE value is negative. NSE and KGE values cannot be directly compared, because their relationship is non-unique and depends in part on the coefficient of variation of the observed time series. Therefore, modellers who use the KGE metric should not let their understanding of NSE values guide them in interpreting KGE values and instead develop new understanding based on the constitutive parts of the KGE metric and the explicit use of benchmark values to compare KGE scores against. More generally, a strong case can be made for moving away from ad hoc use of aggregated efficiency metrics and towards a framework based on purpose-dependent evaluation metrics and benchmarks that allows for more robust model adequacy assessment.

scholarly journals Experimental study on the mean flow characteristics of a supersonic multiple jet configuration

2021 ◽  
Vol 108 ◽  
pp. 106377
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Characteristics ◽  
Mean Flow ◽  
The Mean

scholarly journals Modeling the Excess Velocity of Low-Viscous Taylor Droplets in Square Microchannels

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 162 ◽  
Author(s):  
Thorben Helmers ◽  
Philip Kemper ◽  
Jorg Thöming ◽  
Ulrich Mießner
Keyword(s):  
High Speed ◽  
Process Intensification ◽  
Continuous Phase ◽  
Channel Cross Section ◽  
Optimization Approach ◽  
Mean Flow ◽  
Bypass Flow ◽  
Wall Film ◽  
Proposed Model ◽  
The Mean

Microscopic multiphase flows have gained broad interest due to their capability to transfer processes into new operational windows and achieving significant process intensification. However, the hydrodynamic behavior of Taylor droplets is not yet entirely understood. In this work, we introduce a model to determine the excess velocity of Taylor droplets in square microchannels. This velocity difference between the droplet and the total superficial velocity of the flow has a direct influence on the droplet residence time and is linked to the pressure drop. Since the droplet does not occupy the entire channel cross-section, it enables the continuous phase to bypass the droplet through the corners. A consideration of the continuity equation generally relates the excess velocity to the mean flow velocity. We base the quantification of the bypass flow on a correlation for the droplet cap deformation from its static shape. The cap deformation reveals the forces of the flowing liquids exerted onto the interface and allows estimating the local driving pressure gradient for the bypass flow. The characterizing parameters are identified as the bypass length, the wall film thickness, the viscosity ratio between both phases and the C a number. The proposed model is adapted with a stochastic, metaheuristic optimization approach based on genetic algorithms. In addition, our model was successfully verified with high-speed camera measurements and published empirical data.

scholarly journals Quantifying the Effects of Wave—Current Interactions on Tidal Energy Resource at Sites in the English Channel Using Coupled Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3625
Author(s):  
Jon Hardwick ◽  
Ed B. L. Mackay ◽  
Ian G. C. Ashton ◽  
Helen C. M. Smith ◽  
Philipp R. Thies
Keyword(s):  
Wave Model ◽  
Tidal Energy ◽  
English Channel ◽  
Flow Conditions ◽  
Mean Flow ◽  
Radiation Stress ◽  
Large Wave ◽  
Stress Gradients ◽  
The Mean ◽  
Flow Power

Numerical modeling of currents and waves is used throughout the marine energy industry for resource assessment. This study compared the output of numerical flow simulations run both as a standalone model and as a two-way coupled wave–current simulation. A regional coupled flow-wave model was established covering the English Channel using the Delft D-Flow 2D model coupled with a SWAN spectral wave model. Outputs were analyzed at three tidal energy sites: Alderney Race, Big Roussel (Guernsey), and PTEC (Isle of Wight). The difference in the power in the tidal flow between coupled and standalone model runs was strongly correlated to the relative direction of the waves and currents. The net difference between the coupled and standalone runs was less than 2.5%. However, when wave and current directions were aligned, the mean flow power was increased by up to 7%, whereas, when the directions were opposed, the mean flow power was reduced by as much as 9.6%. The D-Flow Flexible Mesh model incorporates the effects of waves into the flow calculations in three areas: Stokes drift, forcing by radiation stress gradients, and enhancement of the bed shear stress. Each of these mechanisms is discussed. Forcing from radiation stress gradients is shown to be the dominant mechanism affecting the flow conditions at the sites considered, primarily caused by dissipation of wave energy due to white-capping. Wave action is an important consideration at tidal energy sites. Although the net impact on the flow power was found to be small for the present sites, the effect is site specific and may be significant at sites with large wave exposure or strong asymmetry in the flow conditions and should thus be considered for detailed resource and engineering assessments.

Sign in / Sign up

Export Citation Format

Share Document