Unsteady transport of viscous incompressible semi-fluid mixtures in pipes

10.12737/6498 ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. 72-77 ◽  
Author(s):  
Асадуллин ◽  
Nail Asadullin ◽  
Асадуллин ◽  
Linar Asadullin
Keyword(s):  
Work Experience ◽  
High Viscosity ◽  
Shear Stresses ◽  
Flow Cells ◽  
Design Elements ◽  
Fluid Mixtures ◽  
Reduce Energy Consumption ◽  
Reliable Design ◽  
Two Phases ◽  
Sanitary Conditions

Currently, a pressure method of transportation of semi mixtures in pipes is widespread. Work experience and research into the hydro-plants showed that this method of transportation is the most economical, is simple and highly reliable design elements, improve sanitary conditions and makes it possible to automate the process of transportation. One way to reduce energy consumption in transportation is the use of high-viscosity fluids transient driving modes - in particular the imposition of the vibration of a moving stream. Isotropic effects of vibration, consisting in the relative motion of a structured environment, leads to the destruction of bonds in the structure, reduce friction, the yield stress, which creates conditions of flow at low shear stresses. The article deals with the unsteady flow cells were obeying the law, which is quite accurately described by the Bingham-Shvedova. First, a simplified model of the motion-phase environment, based on the model adopted by a new one which took into account two phases of the transported medium. We received instantaneous velocity over the pipe section, which further enable us to obtain their average instantaneous value.

Psychiatry Transcript Annotation: Process Study and Improvements

2021 ◽  
Vol 10 (1) ◽  
pp. 71-75
Author(s):  
Srinivasan Sridhar ◽  
Nazmul Kazi ◽  
Indika Kahanda ◽  
Bernadette McCrory
Keyword(s):  
Mental Health ◽  
Work Experience ◽  
Phase 1 ◽  
Kappa Statistics ◽  
Phase 2 ◽  
Rater Reliability ◽  
Standard Data ◽  
Annotation Process ◽  
Data Collection Process ◽  
Two Phases

Background: The demand for psychiatry is increasing each year. Limited research has been performed to improve psychiatrist work experience and reduce daily workload using computational methods. There is currently no validated tool or procedure for the mental health transcript annotation process for generating “gold-standard” data. The purpose of this paper was to determine the annotation process for mental health transcripts and how it can be improved to acquire more reliable results considering human factors elements. Method: Three expert clinicians were recruited in this study to evaluate the transcripts. The clinicians were asked to fully annotate two transcripts. An additional five subjects were recruited randomly (aged between 20-40) for this pilot study, which was divided into two phases, phase 1 (annotation without training) and phase 2 (annotation with training) of five transcripts. Kappa statistics were used to measure the inter-rater reliability and accuracy between subjects. Results: The inter-rater reliability between expert clinicians for two transcripts were 0.26 (CI 0.19 to 0.33) and 0.49 (CI 0.42 to 0.57), respectively. In the pilot testing phases, the mean inter-rater reliability between subjects was higher in phase 2 with training transcript (k= 0.35 (CI 0.052 to 0.625)) than in phase 1 without training transcript (k= 0.29 (CI 0.128 to 0.451)). After training, the accuracy percentage among subjects was significantly higher in transcript A (p=0.04) than transcript B (p=0.10). Conclusion: This study focused on understanding the annotation process for mental health transcripts, which will be applied in training machine learning models. Through this exploratory study, the research found appropriate categorical labels that should be included for transcripts annotation, and the importance of training the subjects. Contributions of this case study will help the psychiatric clinicians and researchers in implementing the recommended data collection process to develop a more accurate artificial intelligence model for fully- or semi-automated transcript annotation.

Turbulent flow drag reduction and degradation with dilute polymer solutions

1970 ◽  
Vol 43 (4) ◽  
pp. 689-710 ◽  
Author(s):  
R. W. Paterson ◽  
F. H. Abernathy
Keyword(s):  
Molecular Weight ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Average Molecular Weight ◽  
Experimental Studies ◽  
Polymer Degradation ◽  
High Viscosity ◽  
Turbulent Pipe Flow ◽  
Shear Stresses ◽  
Flow Drag

Experimental studies of drag reduction and polymer degradation in turbulent pipe flow with dilute water solutions of unfractionated polyethylene oxide are described. Drag reduction results indicate that the magnitude of the reduction cannot be correlated on the basis of weight average molecular weight, rather the phenomenon depends strongly on the concentration of the highest molecular weight species present in the molecular weight distribution. Polymer degradation in turbulent flow is found to be severe for high molecular weight polymers causing appreciable changes in drag reduction and molecular weight with the duration of flow. Data indicates that drag reduction exists in the limit of infinite dilution suggesting that the phenomenon is due to the interaction of individual polymer molecules with the surrounding solvent and that the extent of reduction is relatively independent of pipe diameter when a comparison is carried out at equal solvent wall shear stresses. Consideration of the high viscosity obtained with solutions in an irrotational laminar flow field suggests this is due to polymer molecule deformation and that this phenomenon is central to the mechanism of turbulent flow drag reduction.

Grinding-Induced Residual Shear Stresses

2006 ◽  
Vol 524-525 ◽  
pp. 685-690 ◽  
Author(s):  
Brando Okolo ◽  
Alexander Wanner
Keyword(s):  
Single Phase ◽  
Ion Beam ◽  
Pearlitic Steel ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Focussed Ion Beam ◽  
Two Phases ◽  
Grinding Machine ◽  
Penetration Depths

Pearlitic steel and pure tungsten specimens were ground using a table-type grinding machine. The thin surface layers affected by the grinding process were characterized using focussed ion beam milling and microscopy. The strongly graded zone altered due to severe plastic deformation and recrystallisation was found to be less than 3m thick. The microstructure in that zone depends on the grinding parameters. Using synchrotron X-ray diffraction, the residual stresses were measured for penetration depths ranging from 0.25 m to 9 m. Based on the approach by Dölle and Hauk, the residual shear stresses were separated from the residual normal stresses. In pearlitic steel, residual shear stresses of opposite sign were observed in the two phases (ferrite and cementite) and found to be compensating each other, while shear stresses were proved to be absent in single-phase tungsten. These results underline that residual shear stresses caused by severe plastic shear deformation exist only as micro-stresses.

Experiments on gravitational phase separation of binary immiscible fluids

2007 ◽  
Vol 591 ◽  
pp. 289-319 ◽  
Author(s):  
MISUZU SATO ◽  
IKURO SUMITA
Keyword(s):  
Phase Separation ◽  
Viscosity Ratio ◽  
Lower Boundary ◽  
Vertical Gradient ◽  
High Viscosity ◽  
Visual Observation ◽  
Immiscible Fluids ◽  
Water Mixture ◽  
Separation Rate ◽  
Two Phases

We conduct experiments on gravitational phase separation of binary immiscible fluids using an oil–water mixture and study how the volumetric and viscosity ratios of the two phases control the separation process. First, we change the volumetric fraction of the two phases. We find that the initial phase separation rate depends strongly on the volumetric ratio of the two phases, and can be modelled by a buoyancy-driven permeable flow using the Blake–Kozeny–Carman permeability formula. Next, we change the viscosity ratios of the two fluids, and we find that there are two distinct regimes with different styles of phase separation. Small viscosity ratio (<100) cases are characterized by a sharp lower boundary and a vertically homogeneous mixture layer. On the other hand, high viscosity ratio (>100) cases are characterized by a diffuse lower boundary and a large vertical gradient of porosity. A polyhedral foam structure develops at the top of the mixture layer which is slow to rupture and to transform into a uniform oil layer. These differences can be interpreted to arise from a faster coalescence rate relative to the separation rate at high viscosity ratios. We simultaneously measured electrical resistivity in order to monitor the temporal change of the mean porosity in the mixture layer. The measurements were found to be consistent with the visual observation.

scholarly journals DEVELOPMENT AND VALIDATION OF A LEADERSHIP TRAINING PROGRAM FOR NURSES

2019 ◽  
Vol 28 ◽  
Author(s):  
Beatriz Gonçalves Martins ◽  
Lais Marques Coelho e Silva ◽  
Beatriz Rodrigues Bispo dos Santos Capaccioli ◽  
Vanessa Ribeiro Neves ◽  
Alexandre Pazetto Balsanelli
Keyword(s):  
Training Program ◽  
Leadership Training ◽  
Work Experience ◽  
Teaching Experience ◽  
Cross Sectional Study ◽  
Second Phase ◽  
Nursing Administration ◽  
Cross Sectional ◽  
Two Phases ◽  
Teaching Learning

ABSTRACT Objectives: To identify strategies that facilitate the development of leadership, correlating them with characterization of variables, and to create and validate a leadership training program for nurses. Method: developed in two phases. First: a cross-sectional study, performed in a general hospital in São Paulo, Brazil. The 70 nurses in the sample had at least three months of work experience in the institution. An instrument was used to collect data with characterization variables (gender, age, postgraduate, work shift and length of working career and contact with the theme of leadership) and collection of suggested strategies to develop more prominent leadership in the literature. Data were collected (February-April 2016) and analyzed descriptively. The Mann-Whitney and Kruskal Wallis tests were used to verify the correlations (p<0.05). Second phase: validation study of the program using the Delphi technique, from March to June 2017. Following the construction of the program, and considering the results obtained in the first phase, judges were selected with the following criteria: to be a nurse, researcher in leadership and nursing administration, with article publications in the last five years and teaching experience. Results: the strategies indicated in the first phase were: performance of experienced leaders as facilitators in the teaching-learning process (the highest scores were given by men; p=0.033) and establishment of partnerships between university and hospital (the largest choice was made by young nurses, p=0.019). In the second phase, a content validity index of 0.81 was reached, considered satisfactory. Conclusion: the program can be applied, and future studies will evaluate its effectiveness.

scholarly journals REDESAIN RAKEL DAN PEMBERIAN PEREGANGAN AKTIF MENURUNKAN BEBAN KERJA DAN KELUHAN MUSKULOSKELETAL SERTA MENINGKATKAN PRODUKTIVITAS KERJA PEKERJA SABLON PADA INDUSTRI SABLON SURYA BALI DI DENPASAR

1970 ◽  
Vol 2 (2) ◽  
pp. 15
Author(s):  
Daryono . . ◽  
I Dewa Putu Sutjana ◽  
I Made Muliarta
Keyword(s):  
Musculoskeletal Disorders ◽  
Working Conditions ◽  
Work Experience ◽  
Screen Printing ◽  
Work Productivity ◽  
Wilcoxon Test ◽  
Second Phase ◽  
Musculoskeletal Complaints ◽  
Significance Level ◽  
Two Phases

Problems ergonomics in industrial screen printing traditional fabrics such as work attitude unnatural causing musculoskeletal disorders in workers printing. To overcome these problems, especially for fabric printing activity done by redesigning Rakel research and giving active stretching. The purpose of this study was to know the effects of the using redesigning Rakel and active stretching for the fabric screen printing workers to decrease the workload, musculoskeletal disorders and increased work productivity. The study design is the design of the same subject, involving 12 workers printing male, 20-45 years old, between 1-5 years of work experience. Research into two phases. The first phase (I) subjects treated with Rakel without redesigning work and without giving active stretching. The second phase (II) subjects treated with redesigning work Rakel and giving active stretching. Among the two phases of the study, given a wash out period for 2 days and adaptation redesigning Rakel for 4 days, to eliminate carry-over effects. The workload is measured by the method of pulse 10 beats, musculoskeletal complaints measured by a questionnaire Nordic Body Map at 4 Likert scale and work productivity based on the ratio between output and input. Data were analyzed with the Shapiro-Wilk test to determine the normality of the data, paired t-test to test the significance difference variable workload and productivity of work at the significance level ? = 0.05 and Wilcoxon test for variables musculoskeletal complaints. The results showed that redesigning Rakel and provision of active stretching can reduce the workload of 30,3% (p<0.05) and lower musculoskeletal complaints by 16,9% (p<0.05) as well as increasing work productivity by 45,5% (p <0.05). It concluded that the redesign Rakel and provision of active stretching can reduce the workload and musculoskeletal disorders and increase productivity for workers printing. Suggested to the owner of a similar business industry to make good working conditions referring to ergonomic principles, so as to create safer working conditions, comfortable, healthy and productive workers.

scholarly journals Quality of information in the bidding processes to hiring engineering works at Universidade Estadual de Londrina (UEL)

2013 ◽  
Vol 7 ◽  
Author(s):  
Lucimeiry Maria Minuzzi-Nascimento ◽  
Maria Inês Tomaél
Keyword(s):  
Work Experience ◽  
Quality Of Information ◽  
Work Activities ◽  
Competitive Edge ◽  
Methodological Procedures ◽  
Two Phases ◽  
Minimal Information ◽  
Bidding Process

Information is considered a high value product, which can turn out to be the differential in an institution, and good quality of information is what distinguishes it in any administrative process, including the bidding process. This way, based in the classification of the information presented by Moresi (2000), critical, minimal and potential information, the purpose of this survey was to analyze the quality of information in the bidding processes to hiring engineering works at Universidade Estadual de Londrina (UEL). The methodological procedures were accomplished in two phases: (i) documental research and (ii) open questionnaire. The main results of the survey indicate the value of minimal information is about management information, and this was found in the bidding processes registration and identification data; the critics, that offers security to the actions with less imperfection, was found in many parts of the processes, with emphasis in the announcement, and the potential information, reputable as competitive edge, was used in selecting the winning firm, upon analysis of the presented proposal. The results of this survey provided the opportunity of discovery of aspects related to: (a) work experience - in front of the importance of ability to discern among the information which is more appropriate in the decision making process at hand; (b) the efficiency in the use, storage and information disposal, processes that lead one to find possible faults, flaws or divergent information, which have obstructed the improvement of work activities, with production of imperfect tasks that need modification in the course of their execution. Therefore, it’s thought to be appropriate to suggest the fulfillment of a research related to informational behavior of the managers involved in the elaboration of the technical chart and in the bidding processes of works at UEL, covering the hiring and contract alteration; due to what was verified in the work here presented.

scholarly journals Viscous Heating Effects on Heat Transfer Characteristics of an Explosive Fluid in a Converging Pipe

2020 ◽  
Vol 64 (3) ◽  
pp. 240-247
Author(s):  
Sina Bagheri ◽  
Saeed Tavangar Roosta ◽  
Amir Heidari
Keyword(s):  
Viscous Dissipation ◽  
Temperature Rise ◽  
High Viscosity ◽  
Shear Stresses ◽  
Heat Transfer Characteristics ◽  
Heating Effects ◽  
Fluid Layers ◽  
Inlet Conditions ◽  
Explosive Properties ◽  
Viscosity Fluid

Viscous dissipation is the production of heat due to the slip of fluid layers and can raise the temperature of the fluid that is affected by high shear stresses. This raise of temperature in fluids with explosive properties can cause the explosion during the processing. The present paper investigates the temperature distribution of an explosive fluid beside the wall of a converging tube. This study has been done by using the computational fluid dynamics and OpenFOAM software. The studied cases contain the fluid with two viscosities (50 and 500 kg/m × s) and two inlet conditions (constant and developed velocity profile). The results of this study show that at the end of a converging pipe, duo to the viscous dissipation effects, the temperature rise for high viscosity fluid is more intensive and this is a dangerous fact for high viscosity explosive fluids discharging. Also, it has been considered that the constant inlet velocity is safer in comparison with the developed profile, as the slope of temperature rise is less.

Motion of a Thrombus in Blood Flow Through a Stenosed Vessel

2007 ◽  
Author(s):  
M. Tanaka ◽  
T. Ohta ◽  
Y. Hagiwara
Keyword(s):  
High Viscosity ◽  
Immersed Boundary ◽  
Droplet Shape ◽  
Pressure Drag ◽  
Fluid Resistance ◽  
Stenosed Vessel ◽  
Flow Through ◽  
Two Phases ◽  
Neutrally Buoyant ◽  
Constricted Tube

A direct numerical simulation has been conducted for a laminar flow in a constricted tube with an immiscible droplet in order to investigate the phenomena which an viscoelastic object such as a thrombus causes when it passes through a stenosed vessel. An immersed-boundary method is used for simulating the flow inside the constricted tube, while the PLIC-VOF algorithm is used for tracking the droplet interface. We have focused on a neutrally buoyant droplet of a fixed size. It is found that the droplet shape strongly depends on the capillary number, while the droplet velocity mainly depends on the viscosity ratio between two phases. The drag force (or fluid resistance) associated with the flow inside the tube is found to increase due to the presence of the droplet at low capillary numbers and at high viscosity ratios. The drag fluctuates when the droplet passes through the constricted area. This is triggered by a relatively large fluctuation in the pressure drag.

Viscosity Ratio Effect in the Emulsion Lubrication of Soft EHL Contact

2006 ◽  
Vol 128 (4) ◽  
pp. 795-800 ◽  
Author(s):  
J. de Vicente ◽  
H. A. Spikes ◽  
J. R. Stokes
Keyword(s):  
Aqueous Phase ◽  
Film Formation ◽  
High Viscosity ◽  
Two Phase ◽  
Bulk Fluid ◽  
Viscous Shear Stress ◽  
Dispersed Oil ◽  
Viscous Shear ◽  
Two Phases ◽  
Ehl Contact

Many foodstuffs and personal care products consist of two-phase systems which, during use, are rubbed between compliant biosurfaces to form thin lubricating films. It is important to understand the nature and properties of the films thus formed since these contribute to the user’s sensory perception, and thus appreciation, of the products concerned. In this paper, the lubrication properties of simple oil-in-aqueous phase emulsions are studied in a steel/elastomer “soft-EHL” contact. It is found that overall behavior is strongly dependent on the ratio of the viscosities of the two phases. When the viscosity of the dispersed oil phase is lower or comparable to that of the continuous aqueous phase, the latter enters the contact and controls film formation and friction. However, when the dispersed phase has viscosity at least four times larger than the dispersion medium, the former enters the contact and determines its tribological properties. This effect is believed occur because at high viscosity ratios the droplets are nondeformable and are thus forced into the contact inlet region, where collisions occur that result in shear-induced coalescence. Once a pool of viscous fluid is formed, the lower viscosity bulk fluid is unable to displace it because the viscous shear stress is too small, so the pool acts as a reservoir to supply the contact.

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