Interpreting Orthogonal Triple-Wire Data From Very High Turbulence Flows

1994 ◽  
Vol 116 (3) ◽  
pp. 463-468 ◽  
Author(s):  
P. K. Maciejewski ◽  
R. J. Moffat
Keyword(s):  
Velocity Vector ◽  
Single Point ◽  
Correlation Coefficients ◽  
Time Correlation ◽  
Wire Probe ◽  
High Turbulence ◽  
Unbiased Estimates ◽  
Mean Vector ◽  
Very High ◽  
Instantaneous Velocity Vector

For turbulence intensities of up to 30 percent, an orthogonal triple-wire probe can be used to make accurate measurements of the instantaneous velocity vector. Above this limit difficulties arise in the interpretation of the data due to the problem described as rectification. This paper presents a means by which data from an orthogonal triple-wire probe may be interpreted for single point measurements in Gaussian turbulence with intensity up to 50 percent resulting in unbiased estimates of the velocity mean vector, Reynolds stress tensor, and time correlation coefficients.

Investigation of the Tip Clearance Flow Inside and at the Exit of a Compressor Rotor Passage—Part II: Turbulence Properties

1983 ◽  
Vol 105 (1) ◽  
pp. 13-17 ◽  
Author(s):  
A. Pandya ◽  
B. Lakshminarayana
Keyword(s):  
Tip Clearance ◽  
Leakage Flow ◽  
Ensemble Averaging ◽  
Tip Clearance Flow ◽  
Wire Probe ◽  
Wall Boundary Layer ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
High Turbulence ◽  
Very High

The flow in the tip clearance region of a compressor rotor is highly turbulent due to the strong interaction of the leakage flow with the annulus wall boundary layer. This paper deals with the turbulence properties of the flow in the tip clearance region of a moderately loaded compressor rotor. The experimental results reported in this paper were obtained using a two-sensor hot-wire probe in combination with an ensemble averaging technique. Blade-to-blade distribution of the axial and tangential turbulence intensities at various radial locations and ten axial locations (four inside the blade passage and the remaining six outside the passage) were derived from this data. Isointensity contours in the clearance region at various radial locations were also obtained from the experimental data. A region of very high turbulence intensities was indicated at the half-chord location from these results. The turbulence intensity profiles also indicated that the leakage flow travels toward the midpassage before rolling up. The turbulence is almost isotropic beyond three-quarter chord downstream of the trailing edge.

Controlled Release of Metformin Hydrochloride I. In vitro Release from Physical Mixture Containing Xanthan Gum as Hydrophilic Rate Retarding Polymer

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Mashkura Ashrafi ◽  
Jakir Ahmed Chowdhury ◽  
Md Selim Reza
Keyword(s):  
Controlled Release ◽  
Xanthan Gum ◽  
In Vitro Release ◽  
Correlation Coefficients ◽  
High Ratio ◽  
Water Soluble ◽  
Metformin Hydrochloride ◽  
Model Drug ◽  
Very High

Capsules of different formulations were prepared by using a hydrophilic polymer, xanthan gum and a filler Ludipress. Metformin hydrochloride, which is an anti-diabetic agent, was used as a model drug here with the aim to formulate sustained release capsules. In the first 6 formulations, metformin hydrochloride and xanthan gum were used in different ratio. Later, Ludipress was added to the formulations in a percentage of 8% to 41%. The total procedure was carried out by physical mixing of the ingredients and filling in capsule shells of size ‘1’. As metformin hydrochloride is a highly water soluble drug, the dissolution test was done in 250 ml distilled water in a thermal shaker (Memmert) with a shaking speed of 50 rpm at 370C &plusmn 0.50C for 6 hours. After the dissolution, the data were treated with different kinetic models. The results found from the graphs and data show that the formulations follow the Higuchian release pattern as they showed correlation coefficients greater than 0.99 and the sustaining effect of the formulations was very high when the xanthan gum was used in a very high ratio with the drug. It was also investigated that the Ludipress extended the sustaining effect of the formulation to some extent. But after a certain period, Ludipress did not show any significant effect as the pores made by the xanthan gum network were already blocked. It is found here that when the metformin hydrochloride and the xanthan gum ratio was 1:1, showed a high percentage of drug release, i.e. 91.80% of drug was released after 6 hours. But With a xanthan gum and metformin hydrochloride ratio of 6:1, a very slow release of the drug was obtained. Only 66.68% of the drug was released after 6 hours. The percent loading in this case was 14%. Again, when Ludipress was used in high ratio, it was found to retard the release rate more prominently. Key words: Metformin Hydrochloride, Xanthan Gum, Controlled release capsule Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

Flow Field on Helodeck of a Frigate: A Review

2019 ◽  
Vol 161 (A4) ◽  
Keyword(s):  
Flow Field ◽  
Numerical Solutions ◽  
Offshore Structures ◽  
High Speeds ◽  
High Turbulence ◽  
The Subject ◽  
Offshore Industry ◽  
The Military ◽  
Very High ◽  
Made In

The various functions desired from a frontline warship such as a frigate, corvette or a destroyer, coupled with the requirement of very high speeds and economic viability restricting the size, necessitates a very dense arrangement of weapons and sensors on the top deck and superstructure. Accordingly, Navies across the world have faced several problems with respect to functions for which a good aerodynamic design for these structures is essential. Major issues include smoke nuisance created due to impinging of the ship's exhaust gases on to the top deck leading to possible suction by engine intakes and high turbulence in the ship's air-wake leading to ship aircraft interface concerns. The flow field on the helodeck is extremely complex due to its geometry and interaction with the wake of the ship’s superstructure. A knowledge of this complexity is essential for ensuring safe helo operations on the helodeck. The problem of ship helicopter interaction has hogged the lime light in recent times, due to rising demand for design of warships for increased stealth, especially in the past two decades. Consequently, several researchers in countries with advanced Navies have invested considerable resources towards evolving both experimental and numerical solutions for the problem. However, given the military nature of the operations, open literature on the subject containing details of such research, which can be used as reference material for present work, are limited. Considering the complexities involved in the problem, an attempt has been made in this paper to holistically review the widely scattered and limited literature in this field. A good amount of literature on marine helo applications emerge from the offshore industry. Keeping in mind that the fields of warship design and offshore structures are dissimilar and have their peculiar problems, informed conclusions have been made in drawing lessons from available literature.

Evaluation of Precipitation Forecast from Global Forecast System Over Transboundary Rivers in Africa

2021 ◽  
Author(s):  
Haowen Yue ◽  
Mekonnen Gebremichael
Keyword(s):  
Correlation Coefficients ◽  
Precipitation Forecast ◽  
Nile River ◽  
Lead Times ◽  
General Tendency ◽  
Global Forecast System ◽  
Forecast System ◽  
Transboundary River Basins ◽  
Unbiased Estimates ◽  
Good Agreement

<p>This study evaluates the short-to-medium range precipitation forecasts from Global Forecast System for 14 major transboundary river basins in Africa against GPM IMERG “Early”, IMERG “Final”, and CHIRPSv2 products. Daily precipitation forecasts with lead times of 1-day, 5-day, 10-day, and 15-day and accumulated precipitation forecasts with periods of 1-day, 5-day, 10-day, and 15-day are investigated. The 14 selected basins are (1) Senegal; (2) Volta; (3) Niger; (4) Chad; (5) Nile; (6) Awash; (7) Congo; (8) Omo Gibe; (9) Tana; (10) Pangani; (11) Zambezi; (12) Okavango; (13) Limpopo and (14) Orange. For each basin, several sub-basins are defined by the major dams in the basin. Our preliminary results in the Nile river basin show that in terms of temporal variability, there was a good agreement between the forecasted and observed accumulated precipitation on a 15-day basis. When compared to IMERG “Final”, the correlation coefficients of accumulated GFS forecasts scored as high as 0.75. Thus, GFS products provide relatively reliable accumulated precipitation forecasts. However, the precipitation forecasts were mostly biased: they tend to overpredict rainfall for the eastern part of the Nile river, underestimate rainfall for the northern part of the Nile river and produce almost unbiased estimates for the southern part of the river. Additionally, GFS forecasts have a general tendency to underpredict the area of precipitation across the Nile basin. Although the performance of GFS varies at different locations, the GFS precipitation forecasts can be a good reference to dam operators in Africa. </p>

scholarly journals Interrelationship of linear dimensions as growth corollary of pama croaker Otolithoides pama in the Bay of Bengal

2021 ◽  
Vol 32 (2) ◽  
pp. 287-292
Author(s):  
ZOARDER FARUQUE AHMED ◽  
MST. KANIZ FATEMA ◽  
UMME HABIBA AZ ZOHORA ◽  
MANSURA AKTER JOBA ◽  
FERDOUS AHAMED
Keyword(s):  
Bay Of Bengal ◽  
Correlation Coefficients ◽  
Future Research ◽  
Strongly Correlated ◽  
Regression Analyses ◽  
Allometric Growth ◽  
Linear Dimensions ◽  
Length Relationship ◽  
Gender Categories ◽  
Very High

Growth pattern of pama croaker Otolithoides pama population in the Bay of Bengal was determinedas the corollary of relationships between standard length (SL) and total length (TL), the two most prevalentlyused linear dimensions of fin fish species. Monthly pama croaker samples were collected from the industrialfisheries in the Bay of Bengal. The length-length relationship was constructed algebraically in the form ofy=a+bx. Relationships between SL and TL for male, female and unsexed populations were separatelyestablished. Sex ratio between male and female did not deviate from the parity (?2 test; p>0.05). The SL andTL ranges of male were 7.2-22 cm and 9.5-28 cm respectively, and the SL and TL ranges of female were6.8-20 cm and 8.4-25.7 cm respectively. Intercept and slope varied monthly in all length-length relationshipsregardless of gender categories. The generalized SL-TL relationships of male, female and unsexedpopulations were TL=1.214SL+0.761(R=0.989), TL=1.212SL-0.770(R=0.990) and TL=1.203SL+0.904(R=0.987) respectively. The correlation coefficients of both monthly and generalized regression analyses ofall sex types were very high (R?0.852) which explained that the relationships between the two lengthdimensions were strongly correlated. The growth corollary appeared both as isometric and allometric formonthly populations. Allometric growth was apparent in July, August and September in all gender types,while isometric growth was deduced in other months. This study would be useful for future research in orderto make comparisons with the relevant aspects of O. pama population between years and locations in the Bayof Bengal.

GROWTH AND NUTRITION OF INFANTS

PEDIATRICS ◽  
1962 ◽  
Vol 30 (4) ◽  
pp. 639-653
Author(s):  
Roberto Rueda-Williamson ◽  
Hedwig E. Rose
Keyword(s):  
Physical Activity ◽  
Food Intake ◽  
National Research Council ◽  
Correlation Coefficients ◽  
Individual Case ◽  
Calorie Intake ◽  
Term Infants ◽  
Length Increment ◽  
Striking Change ◽  
Very High

A longitudinal study was conducted on growth and food intake of 67 unselected healthy, full-term infants from 2 to 15 months of age. The length and weight progress of infants in the study was, during the first year of life, very similar to progress as reported in an earlier study by other investigators, indicating that no striking change in size of 2-to-12-month-old infants had occurred in this area during 30 years, despite changes in feeding practices. The study infants had high calorie and very high protein intakes as compared with Recommended Allowances of the National Research Council. The question of whether some of the very high intakes seen in this study could be potentially harmful or at least beyond the range of optimum nutrition was raised. The desirability of establishing nutritional ceilings was considered. The correlation between length increment and calorie or protein intake was not significant. The correlation coefficients between weight increments and calorie intake were significant but low, indicating that other variables beside food intake influenced size and speed of growth. The correlations between iron intakes and hemoglobin levels and between fat, protein, and calorie intakes and cholesterol levels were not significant. Individual case studies indicated that the most important variables in the energy balance, beside food intake and growth, were illness and physical activity. Environment affected the balance indirectly inasmuch as it influenced physical activity.

Abstract P426: Association of Serum Soy Isoflavones with Metabolic Markers in Japanese Men and Women

Circulation ◽  
2014 ◽  
Vol 129 (suppl_1) ◽  
Author(s):  
Rhobert W Evans ◽  
Akira Sekikawa ◽  
Takashi Kadowaki ◽  
Abhishek Vishnu ◽  
Sayaka Kadowaki ◽  
...  
Keyword(s):  
Correlation Coefficients ◽  
Population Based ◽  
Japanese Women ◽  
Soy Isoflavones ◽  
Serum Samples ◽  
Japanese Men ◽  
Metabolic Markers ◽  
Men And Women ◽  
Isoflavone Concentration ◽  
Very High

Objectives: Soy isoflavones may have beneficial roles as antioxidants and phytoestrogens. Dietary intake varies widely across populations: very high in Japan but low in North America. We measured the concentrations of daidzein and genistein in the serum of Japanese men and women and evaluated their associations with metabolic markers. Methods: Serum samples were obtained from a population based sample of 94 Japanese men (mean age 45.3), and 142 Japanese women (mean age 66.6; 97% were post-menopausal). Isoflavones were analyzed after extraction and derivatization using GC-MS. Concentrations of daidzein and genistein were summed to obtain total isoflavone concentrations. Results: Isoflavone concentrations were very high among the Japanese. Median values (nM) for men: 558, 452 and 86 and for women 660, 494 and 150 (total isoflavones, genistein and daidzein, respectively). Spearman correlation coefficients for the isoflavones with multiple outcomes among Japanese men and women are shown in the table. No significant (p<0.05) associations were observed among the men but borderline negative associations were observed for total isoflavones (p=0.063) and genistein (p=0.063) with LDLc. Among women there was a significant association between total isoflavones (p=0.041) and daidzein (p=0.006) with HDLc. Borderline significant associations were also observed for total isoflavones (p=0.068) and genistein (p=0.061) with glucose. Discussion: The concentrations of isoflavones are high in the Japanese, approximately 50 times greater than those of N. Americans. Associations between the isoflavones and various outcomes were very weak for the Japanese men. This possibly reflects a plateau of isoflavone concentration has been reached that precludes observing any associations. Although, many correlations were calculated the positive associations of total isoflavones and daidzein with HDLc among women may be real. HDLc concentrations are high in Japanese women which may reflect the estrogenic actions of isoflavones.

scholarly journals Topographic control of snow distribution in an alpine watershed of western Canada inferred from spatially-filtered MODIS snow products

2009 ◽  
Vol 13 (3) ◽  
pp. 319-326 ◽  
Author(s):  
J. Tong ◽  
S. J. Déry ◽  
P. L. Jackson
Keyword(s):  
Snow Cover ◽  
Correlation Coefficients ◽  
Time Correlation ◽  
Spatial Filter ◽  
Maximum Difference ◽  
Cloud Coverage ◽  
Snow Cover Extent ◽  
Snow Distribution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Snow Cover Duration

Abstract. A spatial filter (SF) is used to reduce cloud coverage in Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day maximum snow cover extent products (MOD10A2) from 2000–2007, which are obtained from MODIS daily snow cover extent products (MOD10A1), to assess the topographic control on snow cover fraction (SCF) and snow cover duration (SCD) in the Quesnel River Basin (QRB) of British Columbia, Canada. Results show that the SF reduces cloud coverage and improves by 2% the accuracy of snow mapping in the QRB. The new product developed using the SF method shows larger SCF and longer SCD than MOD10A2, with higher altitudes experiencing longer snow cover and perennial snow above 2500 m. The gradient of SCF with elevation (d(SCF)/dz) during the snowmelt season is 8% (100 m)−1. The average ablation rates of SCF are similar for different 100 m elevation bands at about 5.5% (8 days)−1 for altitudes <1500 m with decreasing values with elevation to near 0% (8 days)−1 for altitudes >2500 m. Different combinations of slopes and aspects also affect the SCF with a maximum difference of 20.9% at a given time. Correlation coefficients between SCD and elevation attain 0.96 (p<0.001). Mean gradients of SCD with elevation are 3.8, 4.3, and 11.6 days (100 m)−1 for the snow onset season, snowmelt season, and entire year, respectively. The SF decreases the standard deviations of SCDs compared to MOD10A2 with a maximum difference near 0.6 day, 0.9 day, and 1.0 day for the snow onset season, snowmelt season, and entire year, respectively.

scholarly journals Stagnation Region Heat Transfer Augmentation at Very High Turbulence Levels

2015 ◽  
Author(s):  
J. E. Kingery ◽  
F. E. Ames
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Bypass Transition ◽  
Stagnation Region ◽  
Heat Transfer Augmentation ◽  
Wide Range ◽  
High Turbulence ◽  
Very High ◽  
Turbulence Generator

A database for stagnation region heat transfer has been extended to include heat transfer measurements acquired downstream from a new high intensity turbulence generator. This work was motivated by gas turbine industry heat transfer designers who deal with heat transfer environments with increasing Reynolds numbers and very high turbulence levels. The new mock aero-combustor turbulence generator produces turbulence levels which average 17.4%, which is 37% higher than the older turbulence generator. The increased level of turbulence is caused by the reduced contraction ratio from the liner to the exit. Heat transfer measurements were acquired on two large cylindrical leading edge test surfaces having a four to one range in leading edge diameter (40.64 cm and 10.16 cm). Gandvarapu and Ames [1] previously acquired heat transfer measurements for six turbulence conditions including three grid conditions, two lower turbulence aero-combustor conditions, and a low turbulence condition. The data are documented and tabulated for an eight to one range in Reynolds numbers for each test surface with Reynolds numbers ranging from 62,500 to 500,000 for the large leading edge and 15,625 to 125,000 for the smaller leading edge. The data show augmentation levels of up to 136% in the stagnation region for the large leading edge. This heat transfer rate is an increase over the previous aero-combustor turbulence generator which had augmentation levels up to 110%. Note, the rate of increase in heat transfer augmentation decreases for the large cylindrical leading edge inferring only a limited level of turbulence intensification in the stagnation region. The smaller cylindrical leading edge shows more consistency with earlier stagnation region heat transfer results correlated on the TRL (Turbulence, Reynolds number, Length scale) parameter. The downstream regions of both test surfaces continue to accelerate the flow but at a much lower rate than the leading edge. Bypass transition occurs in these regions providing a useful set of data to ground the prediction of transition onset and length over a wide range of Reynolds numbers and turbulence intensity and scales.

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