A Comparison of Phase Doppler Analyzer (Dual-PDA) and Optical Patternator Data for Twin-Fluid and Pressure-Swirl Atomizer Sprays

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Ariel R. Muliadi ◽  
Paul E. Sojka ◽  
Yudaya R. Sivathanu ◽  
Jongmook Lim
Keyword(s):  
Drop Size ◽  
Dynamic Range ◽  
Arrival Rate ◽  
Drop Diameter ◽  
Volume Flux ◽  
Velocity Correlation ◽  
Significant Drop ◽  
Spatially Resolved ◽  
The Mean ◽  
Swirl Atomizer

The goal of this study was to determine when patternation information derived from Phase Doppler Analyzer (Dantec Dynamics, Skovlunde, Denmark, dual-PDA) measurements of volume flux, drop velocity, and mean size agreed with corresponding values measured using an optical patternator (Enurga, Inc., West Lafayette, IN, SetScan OP-600). To achieve this, data from each instrument were transformed into spatially resolved absorptances (equivalent to drop surface area per unit spray volume) and compared. Key conclusion is absorptance agreement to within 20% in many cases. However, discrepancies between phase Doppler analyzer (PDA)-calculated and optical patternator-measured absorptances become larger as the drop arrival rate increases, as the mean drop size decreases, and when a significant drop size-velocity correlation is present. These discrepancies are attributed to an underestimation of the volume flux (which becomes more important with increasing droplet arrival rate), an over-reporting of the mean drop diameter (which is the result of the restrictive data acquisition scheme applied when ensuring mass closure for the PDA measurements), the limited PDA dynamic range (which can preclude simultaneously accounting for both the largest and smallest drops in the spray), and by the optical patternator’s number-density based measurement scheme (which will not yield the same results as the flux-based PDA when a drop size-velocity correlation is present).

Comparison of Particle Dynamics Analyzer (PDA) and SetScan Optical Patternator Results

2007 ◽  
Author(s):  
Ariel R. Muliadi ◽  
Paul E. Sojka ◽  
Yudaya R. Sivathanu ◽  
Jongmook Lim
Keyword(s):  
Drop Size ◽  
Dynamic Range ◽  
Arrival Rate ◽  
Particle Dynamics ◽  
Drop Diameter ◽  
Volume Flux ◽  
Velocity Correlation ◽  
Significant Drop ◽  
Spatially Resolved ◽  
The Difference

The primary goal of this study was to determine when patternation information derived from Particle Dynamics Analyzer (Dantec Dynamics dual-PDA) measurements of volume flux, velocity and mean drop size agreed with corresponding values measured using an optical patternator (En’Urga, Inc SetScan OP-600). To achieve this, data from each instrument was transformed into spatially resolved absorptances (equivalent to drop surface area per unit volume) and compared. The secondary goal of this study was to explain the cause of any discrepancies in comparison of the two absorptance sets when they occurred. Key conclusions drawn from this study are: absorptance agreement to within 20% can be achieved in many cases; however, the difference between the PDA-calculated and optical patternator-measured absorptances becomes larger as the drop arrival rate increases, as the drop size decreases, and when a significant drop size-velocity correlation is present. These discrepancies are attributed to an underestimation of the volume flux (which becomes more important with increasing droplet arrival rate), an over-reporting of the mean drop diameter (which is the result of the restrictive data acquisition scheme applied when ensuring mass closure), the limited PDA dynamic range (which can preclude simultaneously accounting for both the largest and smallest drops in the spray), and by the optical patternator’s number-density based measurement scheme (which will not yield the same results as the flux-based PDA when a drop size-velocity correlation is present).

scholarly journals Atomization of Water Jets and Sheets in Axial and Swirling Airflows

1979 ◽  
Author(s):  
R. D. Ingebo
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Drop Size ◽  
Unit Area ◽  
Water Flow Rate ◽  
Orifice Diameter ◽  
Drop Diameter ◽  
Water Jets ◽  
Test Conditions ◽  
The Mean

Axial and swirling airflows were used to break up water jets and sheets into sprays of droplets to determine the overall effects of orifice diameter, weight flow of air, and the use of an air swirler on fineness of atomization as characterized by mean drop size. A scanning radiometer was used to determine the mean drop diameter of each spray. Swirling airflows were produced with an axial combustor, 70-deg brake angle, air swirler. Water jets were injected axially upstream, axially downstream and cross stream into the airflow. In addition, pressure atomizing fuel nozzles which produced a sheet and ligament type of breakup were investigated. Increasing the weight flow rate of air or the use of an air swiler markedly reduced the spray mean drop size. Test conditions included a water flow rate of 68.0 liter per hour and airflow rates (per unit area) of 3.7 to 25.7 g per square cm per sec, at 293 K and inlet-air static pressures of 1.01 × 105 to 1.98 × 105 N/m2.

scholarly journals Parameterization of the Sedimentation of Raindrops with Finite Maximum Diameter

2012 ◽  
Vol 140 (5) ◽  
pp. 1589-1602 ◽  
Author(s):  
Corinna Ziemer ◽  
Ulrike Wacker
Keyword(s):  
Distribution Function ◽  
Drop Size ◽  
Size Distribution Function ◽  
Cloud Microphysics ◽  
Maximum Diameter ◽  
Drop Diameter ◽  
One Dimensional ◽  
Drop Mass ◽  
Mathematical Problems ◽  
The Mean

In common cloud microphysics parameterization models, the prognostic variables are one to three moments of the drop size distribution function. They are defined as integrals of the distribution function over a drop diameter ranging from zero to infinity. Recent works (by several authors) on a one-dimensional sedimentation problem have pointed out that there are problems with those parameterization models caused by the differing average propagation speeds of the prognostic moments. In this study, the authors propose to define the moments over a finite drop diameter range of [0, Dmax], corresponding to the limitation of drop size in nature. The ratios of the average propagation speeds are thereby also reduced. In the new model, mean particle masses above a certain threshold depending on Dmax lead to mathematical problems, which are solved by a mirroring technique. An identical, one-dimensional sedimentation problem for two moments is used to analyze the sensitivity of the results to the maximum drop diameter and to compare the proposed method with recent works. It turns out that Dmax has a systematic influence on the model’s results. A small, finite maximum drop diameter leads to a better representation of the moments and the mean drop mass when compared to the detailed microphysical model.

scholarly journals Experimental Study of the Spray Characteristics of a Research Airblast Atomizer

1985 ◽  
Author(s):  
Waldo A. Acosta
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Atmospheric Pressure ◽  
Mass Velocity ◽  
Drop Size ◽  
Unit Area ◽  
Drop Diameter ◽  
Flow Conditions ◽  
Air Mass ◽  
The Mean

An experimental study of airblast atomization was conducted using an especially designed atomizer in which the liquid first impinges on a splash plate, then is directed radially outward and is atomized by the air passing through two concentric, vaned swirlers that swirl the air in opposite directions. The effect of flow conditions, air mass velocity (mass flow rate per unit area, ρAUA) and liquid to air ratio on the mean drop size was studied. Seven different ethanol solutions were used to simulate changes in fuel physical properties. The range of atomizing air velocities was from 30 to 80 m/s. The mean drop diameter was measured at ambient temperature (295 K) and atmospheric pressure.

Evaluation of Spray Characteristics in Pharmaceutical Tablet Coating Processes: The Influences of Drum Rotational Speed and Drying Air Flow Rate

2009 ◽  
Author(s):  
Ariel R. Muliadi ◽  
Paul E. Sojka
Keyword(s):  
Drop Size ◽  
Air Flow ◽  
Air Pressure ◽  
Volume Flux ◽  
Supply Rate ◽  
Drop Velocity ◽  
Pan Coater ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

In this study, drop size, velocity, and volume flux for sprays produced by a pharmaceutical nozzle (Spraying Systems 1/4-JAU-SUE15A-PA67288–45°-SS) were characterized using a Fiber-PDA system (Dantec). Spraying was performed in a 120 cm (24 in) diameter tablet pan-coater (Accela-Cota Model 10, Thomas Engineering, UK). The separate influences of drum rotational speed and drying air flow rate were studied by making measurements at four different pan-coater operating conditions: stationary drum with drying air turned on/off, and 8 rpm rotating drum with drying air turned on/off. For each case, four different spraying conditions (liquid supply rate and atomizing air pressure) were used. PDA scans were performed along the spray semi-major and semi-minor axes at two different axial distances (7.5 and 10 cm) from the atomizer tip. Results were as follows. When both the drying air and drum rotation were absent, increasing liquid supply rate while operating the atomizer at the lower of two atomizing air pressures decreased drop size. The opposite occurred when operating at the higher of the two atomizing air pressures. This suggests that the nozzle operated as a simplex pressure-swirl atomizer at lower levels of atomizing air pressure, but as an air-assist atomizer at higher levels of atomizing air pressure. Regardless, liquid supply rate had no significant effect on drop velocity. In contrast, a decrease in atomizing air pressure or an increase in axial distance always led to an increase in drop size and a decrease in drop velocity. Supplying drying air to the pan-coater resulted in up to a 6 m/s increase in drop velocity, but had mixed effects on drop size. When the spray gun was operated as an air assist atomizer, supplying drying air to the drum led to an increase in D32. The reverse was observed when the gun operated as a simplex pressure-swirl atomizer. These two observations are most evident when operating at the lower liquid supply rate (70 g/min), suggesting that they may have arisen from drop evaporation. Increasing the drying air supply rate also reduced spray extent and volume flux magnitude. Adding drum rotation to the process generally led to (i) increased drop size and (ii) increased drop velocity. (i) likely arose from the transport of small drops away from the spray zone, while (ii) likely resulted from changes in droplet trajectories. Both are the result of the gas-phase swirling motion that is due to the drum rotation. (i) was most noticeable when the nozzle was operated as an air-assist atomizer. In addition, drum rotation decreased spray volume flux magnitude at the spray center, but increased it at other locations, essentially making the spray more dumbbell-shaped. Finally, the influence of drum rotation on drop velocity diminished when drying air flow was included. This was because the drying air momentum helped the drops oppose the effects of the swirling flow induced by the drum rotations.

Differentiating Freezing Drizzle and Freezing Rain in HRRR Model Forecasts

2021 ◽  
Author(s):  
Sarah Tessendorf ◽  
Allyson Rugg ◽  
Alexei Korolev ◽  
Ivan Heckman ◽  
Courtney Weeks ◽  
...  
Keyword(s):  
Drop Size ◽  
Prediction Models ◽  
Water Drop ◽  
Weather Prediction ◽  
Supercooled Liquid ◽  
Drop Diameter ◽  
Aircraft Icing ◽  
Freezing Rain ◽  
Primary Focus

AbstractSupercooled large drop (SLD) icing poses a unique hazard for aircraft and has resulted in new regulations regarding aircraft certification to fly in regions of known or forecast SLD icing conditions. The new regulations define two SLD icing categories based upon the maximum supercooled liquid water drop diameter (Dmax): freezing drizzle (100–500 μm) and freezing rain (> 500 μm). Recent upgrades to U.S. operational numerical weather prediction models lay a foundation to provide more relevant aircraft icing guidance including the potential to predict explicit drop size. The primary focus of this paper is to evaluate a proposed method for estimating the maximum drop size from model forecast data to differentiate freezing drizzle from freezing rain conditions. Using in-situ cloud microphysical measurements collected in icing conditions during two field campaigns between January and March 2017, this study shows that the High-Resolution Rapid Refresh model is capable of distinguishing SLD icing categories of freezing drizzle and freezing rain using a Dmax extracted from the rain category of the microphysics output. It is shown that the extracted Dmax from the model correctly predicted the observed SLD icing category as much as 99% of the time when the HRRR accurately forecast SLD conditions; however, performance varied by the method to define Dmax and by the field campaign dataset used for verification.

scholarly journals Adaptive Image Enhancement Using Entropy-Based Subhistogram Equalization

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Liyun Zhuang ◽  
Yepeng Guan
Keyword(s):  
Image Enhancement ◽  
Dynamic Range ◽  
State Of The Art ◽  
Image Database ◽  
Input Image ◽  
Public Image ◽  
Contrast Enhanced ◽  
Quantitative Results ◽  
The Mean ◽  
Visual Assessments

A novel image enhancement approach called entropy-based adaptive subhistogram equalization (EASHE) is put forward in this paper. The proposed algorithm divides the histogram of input image into four segments based on the entropy value of the histogram, and the dynamic range of each subhistogram is adjusted. A novel algorithm to adjust the probability density function of the gray level is proposed, which can adaptively control the degree of image enhancement. Furthermore, the final contrast-enhanced image is obtained by equalizing each subhistogram independently. The proposed algorithm is compared with some state-of-the-art HE-based algorithms. The quantitative results for a public image database named CVG-UGR-Database are statistically analyzed. The quantitative and visual assessments show that the proposed algorithm outperforms most of the existing contrast-enhancement algorithms. The proposed method can make the contrast of image more effectively enhanced as well as the mean brightness and details well preserved.

scholarly journals Performance Modelling of Health-care Service Delivery in Adekunle Ajasin University, Akungba-Akoko, Nigeria Using Queuing Theory

2020 ◽  
pp. 119-127
Author(s):  
Orimoloye Segun Michael
Keyword(s):  
Health Care ◽  
Service Delivery ◽  
Queuing Theory ◽  
Health Care Service ◽  
Health Centre ◽  
Arrival Rate ◽  
Queuing System ◽  
Service Rate ◽  
Suitable Model ◽  
The Mean

The queuing theory is the mathematical approach to the analysis of waiting lines in any setting where arrivals rate of the subject is faster than the system can handle. It is applicable to the health care setting where the systems have excess capacity to accommodate random variation. Therefore, the purpose of this study was to determine the waiting, arrival and service times of patients at AAUA Health- setting and to model a suitable queuing system by using simulation technique to validate the model. This study was conducted at AAUA Health- Centre Akungba Akoko. It employed analytical and simulation methods to develop a suitable model. The collection of waiting time for this study was based on the arrival rate and service rate of patients at the Outpatient Centre. The data was calculated and analyzed using Microsoft Excel. Based on the analyzed data, the queuing system of the patient current situation was modelled and simulated using the PYTHON software. The result obtained from the simulation model showed that the mean arrival rate of patients on Friday week1 was lesser than the mean service rate of patients (i.e. 5.33> 5.625 (λ > µ). What this means is that the waiting line would be formed which would increase indefinitely; the service facility would always be busy. The analysis of the entire system of the AAUA health centre showed that queue length increases when the system is very busy. This work therefore evaluated and predicted the system performance of AAUA Health-Centre in terms of service delivery and propose solutions on needed resources to improve the quality of service offered to the patients visiting this health centre.

P–328 Dienogest significantly decreases the size of the cyst and alters Anti-Müllerian Hormone concentration in patients with endometrioma

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
E Karataş ◽  
B E Temiz ◽  
S Mumusoglu ◽  
H Yarali ◽  
G Bozdag
Keyword(s):  
Primary Outcome ◽  
Statistical Significance ◽  
Mean Difference ◽  
Secondary Outcome ◽  
Control Group ◽  
Significant Drop ◽  
Mean Size ◽  
The Mean ◽  
Respective Figure

Abstract Study question Does utilization of dienogest make any impact on the size of cyst and Anti-Müllerian Hormone (AMH) concentration in patients with endometrioma throughout 12-months? Summary answer Although dienogest makes a gradual reduction in the size of endometrioma cyst throughout 12-months, a significant drop in AMH serum concentration was also noticed. What is known already According to recent studies, pre-operative serum AMH levels might be illusively increased with parallel to the size of endometrioma which will be a misleading factor while deciding to operate the patient via cystectomy. Although dienogest is one of the medical options that might be commenced in patients with endometrioma cyst, there is limited data about its effect on the size of the endometrioma and hence serum AMH concentration throughout 12 months of follow up. Study design, size, duration The current observational cohort study was conducted among patients with endometrioma those treated with dienogest from January 2017 to January 2020. The primary outcome was alteration in diameter of endometrioma cyst at 6th and 12th months of treatment. Secondary outcome was alteration in serum AMH concentration in the same period. Of 104 patients treated with dienogest, 44 patients were excluded due to being treated with any type of surgical intervention during follow up period. Participants/materials, setting, methods A total of 60 patients were recruited for the final analysis. Of them, primary symptom was dysmenorrhea, chronic pelvic pain and menstrual irregularity in 16 (26.7%), 25 (41.7%) and 8 (13.3%) patients, respectively. Eighteen patients (30%) were asymptomatic. As 21 patients had bi-lateral endometrioma, size of the leading cyst was considered to be analyzed for the primary outcome measure. Paired-t test was used for comparison of numerical values and p ≤ 0.05 was taken as statistical significance. Main results and the role of chance The mean age was 31.5±8.0 years. In the time point when dienogest was started, the mean size of the endometrioma was 46.3±17.4 mm. The mean serum AMH concentration was 3.6±2.4 ng/ml. After 6 months of treatment, the mean size of the endometrioma decreased to 38.6±14.0 mm which corresponds to a mean difference of 7.8 mm (95% CI: 3.0 to 12.6; p: 0.003). The respective figure for AMH was 3.3±2.7 ng/ml which corresponds to a mean difference of 0.3 ng/ml (95% CI: –0.2 to 0.8; p: 0.23) at 6 months. After 12 months of treatment, the mean size of the endometrioma was 37.5±15.7 mm which corresponds to a mean difference of 8.9 mm (95% CI: 2.9 to 14.9; p: 0.005) at the end of 12 months. The respective figure for AMH was 2.7±1.9 ng/ml which corresponds to a mean difference of 0.9 ng/ml (95% CI: 0.1 to 1.7; p: 0.045) at the end of 12 months. The mean diameter of endometrioma and AMH concentration did not differ throughout the time period between 6th and 12th months of the treatment. Limitations, reasons for caution Although herein we present the largest data that depicts the alteration of endometrioma cyst and AMH concentration with the application of dienogest, the lack of control group is a limitation that avoids to perform any comparison. Wider implications of the findings: A shrinkage after commencement of treatment suggest that dienogest might present improvement in patients with endometrioma with respect to radiological findings, but further studies are required whether a decline in AMH concentration after 12 months refers to a genuine decrease in ovarian reserve or resolution of misleading high pre-treatment levels. Trial registration number not available

Encoder response of isolated frog muscle spindle elicited by pseudorandom noise stimuli

1986 ◽  
Vol 55 (1) ◽  
pp. 13-22 ◽  
Author(s):  
H. Querfurth
Keyword(s):  
Muscle Spindle ◽  
Action Potentials ◽  
Dynamic Range ◽  
Frog Muscle ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Pseudorandom Noise ◽  
Afferent Discharge ◽  
The Mean ◽  
Discharge Patterns

The present experiments investigated the signal transfer in the isolated frog muscle spindle by using pseudorandom noise (PRN) as the analytical probe. In order to guarantee that the random stimulus covered the entire dynamic range of the receptor, PRN stimuli of different intensities were applied around a constant mean length, or PRN stimuli of the same intensity were used while varying the mean length of the spindle. Subthreshold receptor potentials, local responses, and propagated action potentials were recorded simultaneously from the first Ranvier node of the afferent stem fiber, thus providing detailed insight into the spike-initiating process within a sensory receptor. Relevant features of the PRN stimulus were evaluated by a preresponse averaging technique. Up to tau = 2 ms before each action potential the encoder selected a small set of steeply rising stretch transients. A second component of the preresponse stimulus ensemble (tau = 2-5 ms) opposed the overall stretch bias. Since each steeply rising stretch transient evoked a steeply rising receptor potential that guaranteed the critical slope condition of the encoding site, this stimulus profile was most effective in initiating action potentials. The dynamic range of the muscle spindle receptor extended from resting length, L0, to about L0 + 100 microns. At the lower limit (L0) the encoding membrane was depolarized to its firing level and discharged action potentials spontaneously. When random stretches larger than the upper region of the dynamic range were applied, the spindle discharged at the maximum impulse rate and displayed no depolarization block or "overstretch" phenomenon. Random stretches applied within the dynamic range evoked regular discharge patterns that were firmly coupled to the PRN. The afferent discharge rate increased, and the precision of phase-locking improved when the intensity of the PRN stimulus was increased around a constant mean stretch; or the mean prestretch level was raised to higher values while the intensity of the PRN stimulus was kept constant. In the case when the PRN stimulus covered the entire dynamic range, the temporal pattern of the afferent discharge remained constant for at least 10 consecutive sequences of PRN. A spectral analysis of the discharge patterns averaged over several sequences of PRN was employed. At the same stimulus intensity the response spectra displayed low-pass filter characteristics with a 10-dB bandwidth of 300 Hz and a high-frequency slope of -12 dB/oct. Increasing the mean intensity of the PRN stimulus or raising the prestretch level increased the response power.(ABSTRACT TRUNCATED AT 400 WORDS)

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