Erosion in Swirl-Inducing Pipes

2002 ◽  
Author(s):  
R. J. K. Wood ◽  
T. F. Jones ◽  
J. Ganeshalingam
Keyword(s):  
Sliding Wear ◽  
Computational Models ◽  
Particle Distribution ◽  
Impact Angle ◽  
Pumping Power ◽  
Particulate Flows ◽  
Flow Loop ◽  
Erosion Models ◽  
The Mean ◽  
The Impact

Swirl inducing pipes are proposed for the alleviation of problems of poor particle distribution and sliding wear, particularly at downstream bends and elbows. In a well-designed conventional pipeline, the mean axial velocity to assure good dispersion of particles is much greater than the velocity required to merely transport the slurry. This gives the impetus to design swirl-inducing pipes which allow for reduced pumping power, and reduced erosion, while efficiently maintaining suspension at strategic points. This paper covers research that has been aimed at producing good distribution of particles at relatively low velocities, by applying swirl induction. Computational models for the impact velocity and impact angle in a bend have been successfully applied to the flow field and validated by experiments in a perspex flow loop including electrical resistance tomography (ERT) to confirm the placement of particle burdens. Particle impact parameters from this work have been used as inputs to erosion models to predict wall wastage rates in bends and the location of damage from well distributed and swirling particulate flows.

Analysis of Erosion and Failure in the Sudden Expansion Fracturing Tubing of Deep Gas Wells

2010 ◽  
Author(s):  
Yan Xu ◽  
Zunce Wang ◽  
Sen Li ◽  
Fengxia Lv ◽  
Yuejuan Yan ◽  
...  
Keyword(s):  
Impact Angle ◽  
High Rate ◽  
Sudden Expansion ◽  
Gas Wells ◽  
Gas Well ◽  
Erosion Models ◽  
Fluid Theory ◽  
Simulation Results ◽  
The Impact ◽  
Two Fluid

With the increasing of flow rate during fracturing in deep gas well, the erosion of fracturing tubing is an issue of immense concern to the industry. Based on the Euler-Euler two–fluid theory, the numerical simulations have been performed to predict the flow field in the sudden expansion fracturing tubing. The velocity distributions and sand concentration profiles are obtained, and the simulation results show that separation and reflux come into being in the sudden expansion fracturing tubing when pumping sand slurries at high rate, and the sand concentration increases at some regions. The erosion and failure of the fracturing tubing are relevant to the sand concentration, the velocity and the impact angle. The erosion model was established with the erosion experiment, and the numerical simulation results were used to describe the erosion rate of sudden expansion fracturing tubing according to the established erosion models. The mainly erosion region obtained through the simulation is basically agree with the failure region of tubing during fracturing in deep gas wells.

A New Methodology for Erosion Prediction Using Eulerian-Eulerian CFD Models

2015 ◽  
Author(s):  
Gianandrea V. Messa ◽  
Irene Ingrosso ◽  
Stefano Malavasi
Keyword(s):  
Fluid Dynamic ◽  
Fluid Phase ◽  
Impact Angle ◽  
Solid Particles ◽  
Dynamic Parameters ◽  
Gas Industry ◽  
Erosion Prediction ◽  
Cfd Models ◽  
Erosion Models ◽  
The Impact

The erosion of a surface caused by the impact of solid particles dragged by a fluid is a serious concern in the oil&gas industry. At present, the erosion prediction is performed using algebraic erosion models which express the volume of eroded material per impact as a function of the mass of the abrasive particles as well as of fluid dynamic parameters (such as the impact velocity and the impact angle of the eroding particle) and properties of the materials involved in the process. The fluid dynamic parameters are, in turn, evaluated using Eulerian-Lagrangian CFD models which interpret the fluid phase as a continuous mean and follow the trajectories of all the particles. However, the huge computational burden makes it difficult, or even precludes, to adopt this approach in many flows of engineering interest. An innovative methodology is proposed for estimating the parameters required as input by the erosion models using computationally cheaper Eulerian-Eulerian CFD models which solve for the average properties of the ensamble of particles. The good results obtained when predicting the erosion caused the by impingement of an abrasive jet against a surface make the application of this methodology to more complex flows very promising.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Sound Production Treatment for Acquired Apraxia of Speech: An Examination of Dosage in Relation to Probe Performance

2020 ◽  
pp. 1-16
Author(s):  
Julie L. Wambaugh ◽  
Lydia Kallhoff ◽  
Christina Nessler
Keyword(s):  
Retrospective Analysis ◽  
Sound Production ◽  
Apraxia Of Speech ◽  
Practice Schedule ◽  
Practice Schedules ◽  
Baseline Performance ◽  
The Mean ◽  
Number Of Treatment ◽  
The Impact

Purpose This study was designed to examine the association of dosage and effects of Sound Production Treatment (SPT) for acquired apraxia of speech. Method Treatment logs and probe data from 20 speakers with apraxia of speech and aphasia were submitted to a retrospective analysis. The number of treatment sessions and teaching episodes was examined relative to (a) change in articulation accuracy above baseline performance, (b) mastery of production, and (c) maintenance. The impact of practice schedule (SPT-Blocked vs. SPT-Random) was also examined. Results The average number of treatment sessions conducted prior to change was 5.4 for SPT-Blocked and 3.9 for SPT-Random. The mean number of teaching episodes preceding change was 334 for SPT-Blocked and 179 for SPT-Random. Mastery occurred within an average of 13.7 sessions (1,252 teaching episodes) and 12.4 sessions (1,082 teaching episodes) for SPT-Blocked and SPT-Random, respectively. Comparisons of dosage metric values across practice schedules did not reveal substantial differences. Significant negative correlations were found between follow-up probe performance and the dosage metrics. Conclusions Only a few treatment sessions were needed to achieve initial positive changes in articulation, with mastery occurring within 12–14 sessions for the majority of participants. Earlier occurrence of change or mastery was associated with better follow-up performance. Supplemental Material https://doi.org/10.23641/asha.12592190

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

(Preprint)

2018 ◽  
Author(s):  
Natalia Banasik ◽  
Dariusz Jemielniak ◽  
Wojciech P?dzich
Keyword(s):  
Medical Condition ◽  
Extended Period ◽  
Well Being ◽  
Marginal Effect ◽  
Life Duration ◽  
Significant Difference ◽  
The Mean ◽  
Academic Teachers ◽  
Length Of Life ◽  
The Impact

BACKGROUND There have been mixed results of the studies checking whether prayers do actually extend the life duration of the people prayed for. Most studies on the topic included a small number of prayers and most of them focused on people already struggling with a medical condition. Intercessory prayer’s influence on health is of scholarly interest, yet it is unclear if its effect may be dependent on the number of prayers for a named individual received per annum. OBJECTIVE We sought to examine if there is a noticeable increased longevity effect of intercessory prayer for a named individual’s well-being, if he receives a very high number of prayers per annum for an extended period. METHODS We retrieved and conducted a statistical analysis of the data about the length of life for 857 Roman Catholic bishops, 500 Catholic priests, and 3038 male academics from the US, France, Italy, Poland, Brazil, and Mexico. We obtained information for these individuals who died between 1988 and 2018 from Wikidata, and conducted an observational cohort study. Bishops were chosen for the study, as they receive millions of individual prayers for well being, according to conservative estimates. RESULTS There was a main effect for occupation F(2, 4391) = 4.07, p = .017, ηp 2 = .002, with pairwise comparisons indicating significant differences between the mean life duration of bishops (M=30489) and of priests (M=29894), but none between the academic teachers (M=30147) and either of the other groups. A comparison analysis between bishops from the largest and the smallest dioceses showed no significant difference t(67.31)=1.61, p = .11. Our main outcome measure is covariance of the mean length of life in each of the categories: bishops, priests, academic teachers, controlled for nationality. CONCLUSIONS The first analysis proved that bishops live longer than priests, but due to a marginal effect size this result should be treated with caution. No difference was found between the mean length of life of bishops from the largest and the smallest dioceses. We found no difference between bishops and male academics. These results show that the impact of intercessory prayers on longevity is not observable.

scholarly journals Mean Empirical Likelihood Inference for Response Mean with Data Missing at Random

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hanji He ◽  
Guangming Deng
Keyword(s):  
Empirical Likelihood ◽  
Missing At Random ◽  
Confidence Regions ◽  
Likelihood Inference ◽  
High Dimensional ◽  
Finite Sample ◽  
The Mean ◽  
Data Missing ◽  
Consistency And Asymptotic Normality ◽  
The Impact

We extend the mean empirical likelihood inference for response mean with data missing at random. The empirical likelihood ratio confidence regions are poor when the response is missing at random, especially when the covariate is high-dimensional and the sample size is small. Hence, we develop three bias-corrected mean empirical likelihood approaches to obtain efficient inference for response mean. As to three bias-corrected estimating equations, we get a new set by producing a pairwise-mean dataset. The method can increase the size of the sample for estimation and reduce the impact of the dimensional curse. Consistency and asymptotic normality of the maximum mean empirical likelihood estimators are established. The finite sample performance of the proposed estimators is presented through simulation, and an application to the Boston Housing dataset is shown.

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

scholarly journals Onchocerciasis control in Ghana (1974–2016)

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nana-Kwadwo Biritwum ◽  
Dziedzom K. de Souza ◽  
Odame Asiedu ◽  
Benjamin Marfo ◽  
Uche Veronica Amazigo ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Vector Control ◽  
Control Strategy ◽  
Financial Support ◽  
Control Programme ◽  
Ivermectin Treatment ◽  
Mobile Community ◽  
The Mean ◽  
The Impact ◽  
Onchocerciasis Control

Abstract Background The control of onchocerciasis in Ghana started in 1974 under the auspices of the Onchocerciasis Control Programme (OCP). Between 1974 and 2002, a combination of approaches including vector control, mobile community ivermectin treatment, and community-directed treatment with ivermectin (CDTI) were employed. From 1997, CDTI became the main control strategy employed by the Ghana OCP (GOCP). This review was undertaken to assess the impact of the control interventions on onchocerciasis in Ghana between 1974 and 2016, since which time the focus has changed from control to elimination. Methods In this paper, we review programme data from 1974 to 2016 to assess the impact of control activities on prevalence indicators of onchocerciasis. This review includes an evaluation of CDTI implementation, microfilaria (Mf) prevalence assessments and rapid epidemiological mapping of onchocerciasis results. Results This review indicates that the control of onchocerciasis in Ghana has been very successful, with a significant decrease in the prevalence of infection from 69.13% [95% confidence interval) CI 60.24–78.01] in 1975 to 0.72% (95% CI 0.19–1.26) in 2015. Similarly, the mean community Mf load decreased from 14.48 MF/skin snip in 1975 to 0.07 MF/skin snip (95% CI 0.00–0.19) in 2015. Between 1997 and 2016, the therapeutic coverage increased from 58.50 to 83.80%, with nearly 100 million ivermectin tablets distributed. Conclusions Despite the significant reduction in the prevalence of onchocerciasis in Ghana, there are still communities with MF prevalence above 1%. As the focus of the GOCP has changed from the control of onchocerciasis to its elimination, both guidance and financial support are required to ensure that the latter goal is met.

scholarly journals 996. The Potential for Reducing Opioid and Analgesic Prescriptions Via Herpes Zoster Vaccination

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S527-S527
Author(s):  
Jean-Etienne Poirrier ◽  
Justin Carrico ◽  
Jessica K DeMartino ◽  
Katherine A Hicks ◽  
Jeffrey J Stoddard ◽  
...  
Keyword(s):  
Herpes Zoster ◽  
Age Group ◽  
Opioid Prescription ◽  
Varicella Zoster ◽  
Effectiveness Model ◽  
Prescription Rates ◽  
Medication Exposure ◽  
The Mean ◽  
The Impact ◽  
Analgesic Use

Abstract Background Herpes zoster (HZ), or shingles, is a common neurocutaneous disease caused by the reactivation of latent varicella zoster virus that often includes rash and neuropathic pain that may last for months. Opioids and other analgesics may be prescribed. Recombinant zoster vaccine (RZV) is preferentially recommended for the prevention of HZ in adults aged 50 years and older. This study aimed to assess the impact of RZV vaccination on opioid and other analgesic prescription-related outcomes. Methods Estimates of analgesic prescription rates (opioids, benzodiazepines, and other analgesics) among HZ cases were established using Truven claims data from 2012-2018 for adults aged 50 years and older. HZ case avoidance with RZV vaccination was calculated using a previously published cost-effectiveness model. This data was included in a calculator assessing the impact of RZV vaccination on analgesic prescription-related outcomes (compared to no vaccination). Results Between 24.4% and 28.0% of HZ cases in the observed claims had at least one opioid prescription, dependent on age group (4.5%-6.5% and 8.6%-19.6% for benzodiazepines and other analgesics, respectively). The mean number of opioid prescriptions per person in each age group with at least one opioid prescription was between 1.7 and 1.9 (1.7-2.3 and 1.7-2.0 prescriptions for benzodiazepines and other analgesics, respectively). Assuming a 1-million-person population and 65% RZV coverage, the calculator predicts RZV vaccination will prevent 75,002 cases of HZ and will prevent 19,311 people from being prescribed at least 1 HZ-related opioid, 4,502 people from being prescribed benzodiazepines, and 12,201 people from being prescribed other analgesics. Additionally, 34,520 HZ-related opioid prescriptions will be avoided (9,413 benzodiazepine prescriptions; 22,406 other analgesic prescriptions). Conclusion HZ is associated with high levels of opioid, benzodiazepine, and other analgesic use. Primary prevention of HZ by vaccination could potentially reduce opioid and other medication exposure. Disclosures Jean-Etienne Poirrier, PhD, MBA, The GSK group of companies (Employee, Shareholder) Justin Carrico, BS, GlaxoSmithKline (Consultant) Jessica K. DeMartino, PhD, The GlaxoSmithKline group of companies (Employee, Shareholder) Katherine A. Hicks, MS, BSPH, GlaxoSmithKline (Scientific Research Study Investigator, GSK pays my company for my contractual services.) Saurabh P. Nagar, MS, RTI Health Solutions (Employee) Juliana Meyers, MA, GlaxoSmithKline (Other Financial or Material Support, This study was funded by GlaxoSmithKline.)

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