Does Barite Scale Deposit at a Kinetic Stable Flow?

2020 ◽  
Author(s):  
Alex Yi-Tsung Lu ◽  
Samridhdi Paudyal ◽  
Saebom Ko ◽  
Chong Dai ◽  
Bingjei Ouyang ◽  
...  
Keyword(s):  
Scale Deposit ◽  
Stable Flow

RELAÇÃO VAZÃO x PRESSÃO EM MICROASPERSORES DAN 2001 SOB CONDIÇÃO ADVERSA DE OPERAÇÃO

Irriga ◽  
2003 ◽  
Vol 8 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Marco Antonio Fonseca Conceição ◽  
Rubens Duarte Coelho
Keyword(s):  
Hydraulic Performance ◽  
Sao Paulo ◽  
The Self ◽  
São Paulo ◽  
Flow Curves ◽  
Pressure Flow ◽  
Adverse Condition ◽  
Irrigation Time ◽  
E Mail ◽  
Stable Flow

RELAÇÃO VAZÃO x PRESSÃO EM MICROASPERSORES DAN 2001 SOB CONDIÇÃO ADVERSA DE OPERAÇÃO  Marco Antônio Fonseca ConceiçãoEmbrapa Uva e Vinho, Estação Experimental de Jales, Jales, SP. CP 241. CEP 15700-000.E-mail: [email protected] Duarte CoelhoDepartamento de Engenharia Rural, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP. CP 09, CEP 13418-900.E-mail: [email protected]  1 RESUMO  Alguns microaspersores possuem membranas que regulam a sua pressão de operação, mantendo a vazão praticamente estável dentro de uma faixa de pressão na rede hidráulica. Operadores de irrigação no campo, muitas vezes com baixo nível de instrução e sem orientação profissional qualificada, visando reduzir problemas de entupimento ou para diminuir o tempo de irrigação, costumam retirar as membranas autocompensantes para aumentar a vazão do emissores, o que pode comprometer o desempenho hidráulico do sistema. Para avaliar o efeito da retirada da membrana  sobre as vazões dos microaspersores, no presente trabalho determinou-se as relações entre pressão e vazão para sete bocais do microaspersor DAN 2001, operando na ausência da membrana autocompensante. As curvas pressão-vazão sem as membranas autocompensantes apresentaram comportamento potencial com expoentes variando entre 0,58 e 0,64. As vazões dos microaspersores sem as membranas aumentaram de forma inversamente proporcional aos diâmetros dos emissores, quando comparadas às vazões nominais com as membranas.  UNITERMOS: Hidráulica, irrigação, microaspersão.  CONCEIÇÃO, M.A.F.; COELHO, R.D. FLOW X PRESSURE RELATIONSHIP FOR DAN 2001 MICROSPRINKLERS UNDER ADVERSE CONDITION  2 ABSTRACT  Many types of microsprinklers have a self-compensating membrane to regulate their pressure, keeping a stable flow. Many producers usually take the membranes off to reduce clogging problems  or irrigation time. This procedure could endanger the system hydraulic performance. To evaluate the effect of taking off the self-compensating membrane from microsprinklers it was determined, in the present work, the pressure-flow relationship for seven Dan 2001 microsprinkler nozzles operating without the membrane. The pressure-flow curves presented a potential behavior with the exponents varying from 0.58 to 0.64. Microsprinkler flows without the membranes increased inversely proportional to the emitter diameters, comparing to the nominal flows using the membranes.  KEYWORDS: Hydraulic, irrigation, microsprinkler.

Substantiation the machine with a basket for the application of mineral fertilizers and other bulk materials with the upper arrangement of the feeding device

2019 ◽  
pp. 37-43
Author(s):  
Fesenko, H.
Keyword(s):  
Fat Body ◽  
Mineral Fertilizer ◽  
The Body ◽  
Mineral Fertilizers ◽  
Analytical Mechanics ◽  
Bulk Materials ◽  
The Stability ◽  
Working Bodies ◽  
The Relationship ◽  
Stable Flow

Purpose. Increasing the uniformity of distribution of mineral fertilizers and other bulk materials due to the stability of their feed from the body to the spreading working bodies using the top feeder. Methods. The following methods are used to achieve this aim: the method of comparing the differences between individual groups of fertilizers, the method of analyzing the properties of a new technical system, the method of functional inventiveness, and the methods of theoretical and analytical mechanics. Results. The traction body of the conveyor of the upper feed of the body fat body machine for mineral fertilizers and other bulk materials was substantiated and the relationship between the height of its scrapers and the distance between them was established, as well as the nature of the mineral fertilizer pressure on the curvilinear wall of the body. In addition, the design of the advanced body fertilizer spreader is justified, which ensures a stable flow of fertilizers from the body due to the improvement of the top feeder. Conclusions. Because of the conducted researches, the advantages of machines equipped with top feeder are found. They create the conditions for the forced feeding mineral fertilizers and other loose materials from the container to the distribution bodies, which is a prerequisite for their evenness on the surface. With this, the imperfection of known machines with the top feeder constrains their introduction into agricultural production. On this account, a more thoroughly constructed solution of the body feeder of the top feed is substantiated, in which the conveyor provides a stable supply of fertilizers from the body with reduced energy consumption during operation. Keywords: analysis, feed, upper device, conveyor, stability, fertilizers, flow ability, body.

Catchment-wide impacts on water quality: the use of ‘snapshot’ sampling during stable flow

1997 ◽  
Vol 199 (1-2) ◽  
pp. 121-134 ◽  
Author(s):  
R.B. Grayson ◽  
C.J. Gippel ◽  
B.L. Finlayson ◽  
B.T. Hart
Keyword(s):  
Water Quality ◽  
Stable Flow

scholarly journals Bifurcations from steady to quasi-periodic flows in a laterally heated cavity filled with low Prandtl number fluids

2018 ◽  
Vol 861 ◽  
pp. 223-252 ◽  
Author(s):  
A. Medelfef ◽  
D. Henry ◽  
A. Bouabdallah ◽  
S. Kaddeche
Keyword(s):  
Prandtl Number ◽  
Liquid Metals ◽  
Three Dimensional ◽  
Numerical Continuation ◽  
Arnoldi Method ◽  
Periodic Flows ◽  
Bifurcation Points ◽  
Prandtl Numbers ◽  
Stable Flow ◽  
Flow States

This study deals with the transition toward quasi-periodicity of buoyant convection generated by a horizontal temperature gradient in a three-dimensional parallelepipedic cavity with dimensions $4\times 2\times 1$ (length $\times$ width $\times$ height). Numerical continuation techniques, coupled with an Arnoldi method, are used to locate the steady and Hopf bifurcation points as well as the different steady and periodic flow branches emerging from them for Prandtl numbers ranging from 0 to 0.025 (liquid metals). Our results highlight the existence of two steady states along with many periodic cycles, all with different symmetries. The bifurcation scenarios consist of complex paths between these different solutions, giving a succession of stable flow states as the Grashof number is increased, from steady to periodic and quasi-periodic. The change of these scenarios with the Prandtl number, in connection with the crossing of bifurcation points, was carefully analysed.

Experimental Study on the Recirculation of Homogeneous and Stratified Fluid Layers in the Advanced Solar Pond

1994 ◽  
Vol 116 (2) ◽  
pp. 74-78 ◽  
Author(s):  
Y. Keren ◽  
H. Rubin ◽  
G. A. Bemporad
Keyword(s):  
Double Diffusion ◽  
Stratified Fluid ◽  
Experimental Investigations ◽  
Laboratory Setup ◽  
Solar Pond ◽  
Fluid Layers ◽  
Data Density ◽  
And Control ◽  
Stable Flow ◽  
Transient And Steady State

The practical possibilities of constructing and operating a stable flow of homogeneous and stratified fluid layers in a solar pond were investigated in this study. A laboratory setup was prepared to carry out the experimental investigations. Transient and steady-state conditions were analyzed. A numerical model was developed to simulate heat, salt, and momentum transfer in the water body. The model was calibrated with the experimental data. Density and temperature measurements along the laboratory setup showed the configuration to be stable in all of the conditions which were analyzed. These experimental results indicated that through a proper multiselective injection and withdrawal procedure it was possible to create and control the double-diffusion stratified fluid layers, which characterizes the advanced solar pond.

scholarly journals Steady and unsteady flow of non-newtonian fluid in curved pipe with triangular

2006 ◽  
Vol 3 (3) ◽  
pp. 470-480
Author(s):  
Baghdad Science Journal
Keyword(s):  
Unsteady Flow ◽  
Pressure Gradient ◽  
Secondary Flow ◽  
Cross Section ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Curved Pipe ◽  
First Case ◽  
Stable Flow ◽  
Flow Cross

This paper deals with numerical study of the flow of stable and fluid Allamstqr Aniotina in an area surrounded by a right-angled triangle has touched particularly valuable secondary flow cross section resulting from the pressure gradient In the first case was analyzed stable flow where he found that the equations of motion that describe the movement of the fluid

Abstract 363: Lim Domain Only 4 Is a Shear-Sensitive Protein, Playing a Critical Role in Endothelial Inflammation and Atherosclerosis

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Wakako Takabe ◽  
Chih-Wen Ni ◽  
Dong Ju Son ◽  
Noah Alberts-Grill ◽  
Hanjoong Jo
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Critical Role ◽  
Oscillatory Shear ◽  
Lim Domain ◽  
Disturbed Flow ◽  
Endothelial Inflammation ◽  
And Migration ◽  
Oscillatory Shear Stress ◽  
Stable Flow

Recently, we have shown that disturbed flow, characterized by low and oscillatory shear stress, caused by a partial ligation of mouse left carotid artery (LCA) rapidly induces atherosclerosis. Using the partial ligation model and genome-wide microarray study with aortic endothelial RNAs obtained directly from the flow-disturbed carotid arteries, we previously identified mechanosensitive genes in mouse endothelial RNA including LIM domain only 4 ( lmo4 ). Here we report that LMO4 is a shear-sensitive protein that regulates endothelial inflammation. Lmo4 was up-regulated by disturbed flow in mouse LCA compared to the contralateral right CA (RCA) exposed to stable flow. At protein levels, LMO4 expression was significantly higher not only in LCA in our surgical model but also in the lesser curvature (flow-disturbed and athero-prone region of mouse aortic arch) compared to the greater curvature (stable-flow and ather-protected region). In addition, immunohistochemical staining of LMO4 in human coronary arteries revealed that its expression is detectable only in intimal endothelial cells, but not in medial cells. While LMO4 is known as a potential oncogene and associated with growth, migration and invasion of breast cancer cells, its role in cardiovascular system is not known to our knowledge. We tested a hypothesis that LMO4 is a mechanosensitive gene and plays a critical role in regulation of endothelial cell biology. LMO4 protein expression was robustly induced by oscillatory shear stress (OS) compared to laminar shear (LS) in human umbilical vein endothelial cells (HUVEC). Treatment of HUVEC with siRNA against LMO4 significantly inhibited OS-induced inflammation and migration, but not apoptosis and cell cycle progression. Further, LMO4 siRNA treatment significantly blunted expression of VCAM-1 and interleukin-8 induced by OS in endothelial cells. These results suggest that LMO4 is a shear-induced gene that plays a critical role in OS-induced endothelial inflammation and migration, and potentially in atherosclerosis.

Microcirculatory effects of norepinephrine in patients with septic shock: a microdialysis study

2020 ◽  
Author(s):  
Amira Fatnassi ◽  
Chihebeddine Romdhani ◽  
Widd Kaabi ◽  
Iheb Labbene ◽  
Zied Hajjej ◽  
...  
Keyword(s):  
Septic Shock ◽  
Lactate Concentration ◽  
Inverse Correlation ◽  
Tissue Perfusion ◽  
Control Group ◽  
Adrenergic Drug ◽  
Microdialysis Study ◽  
And Control ◽  
Stable Flow ◽  
Pyruvate Ratio

Abstract Background: The management of septic shock requires the administration of an alpha-adrenergic drug such as norepinephrine, after optimization of the patient’s preload, to maintain adequate mean arterial pressure. Nevertheless, with optimal macrocirculatory parameters, alterations of tissue perfusion can occur. This study aimed to investigate the effect of norepinephrine dosage on microcirculation parameters, studied by microdialysis, in patients with septic shock. Methods: We conducted a retrospective study. We included all patients aged over 16 years in septic shock. We studied three groups (levosimendan, dobutamine, and control group). We administrated norepinephrine before inclusion, at stable flow for more than an hour. We performed hemodynamic monitoring of macrocirculation by echocardiography. We analyzed microcirculation parameters (lactate, pyruvate, and lactate/pyruvate ratio) every six hours during the first three days, by muscle microdialysis (CMA 600, CMA microdialysis AB, Stockholm, Sweden). We studied correlations between microcirculation parameters and norepinephrine doses.Results: We included thirty patients in the study (ten patients in each group). Demographic characteristics and mortality were comparable across the three groups. In total, we analyzed 390 samples of interstitial muscle fluid. We did not find any correlation between norepinephrine doses and the lactate concentration in the muscle, as well as the ratio of lactate/ pyruvate concentration in the muscle (p > 0.05) for all groups. We found a weak inverse correlation between norepinephrine doses and muscle pyruvate levels (p < 0.05) for the dobutamine group and the control group and but not for the levosimendan group.Conclusions: Noradrenaline dose has little effect on microcirculation when administered for hemodynamic optimization, as recommended by the Surviving Sepsis Campaign.

scholarly journals Continuous Free-Flow Fractionation of Cellular Constituents in Rat Bone Marrow

Blood ◽  
1965 ◽  
Vol 25 (1) ◽  
pp. 63-72 ◽  
Author(s):  
HOWARD C. MEL ◽  
LINDA T. MITCHELL ◽  
BO THORELL
Keyword(s):  
Bone Marrow ◽  
Cell Types ◽  
Single Cell Suspension ◽  
Physical Classification ◽  
Normal Rat ◽  
Good Repeatability ◽  
Different Cell Types ◽  
Stable Flow ◽  
Rat Bone

Abstract A single-cell suspension of normal rat bone marrow is prepared mechanically. This suspension is continuously fractionated in free solution, under sedimentation rate conditions, using 1 g. only. With a sample flow of 2.2 x 106 cells/minute and a 32-minute steady-state residence time in the stable-flow free boundary (STAFLO) flow-cell, the cells exit almost entirely into 7 of the 12 collection bottles. Maximum numbers of different cell types are observed, with good repeatability, in approximately descending order from top to bottom as follows: erythrocytes, "erythroblasts," "immatures," "myelocytes," and mature granulocytes. Major changes are effected relative to the starting marrow composition, and large relative enrichments are achieved for certain cell types. In addition to the rapid, mild, preparative aspect of this study, nominal sedimentation rates can be assigned for the different collection fractions, in the range of 3 x 105 to 4 x 106 svedbergs, thus making a start on this kind of simple physical classification of the cellular elements in this complex tissue.

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