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The Utilization of Ultrasound-guided Biopsy in the Management of Ovarian Tumors
Vlasák, Pavel ; Presl, Jiří (advisor) ; Fínek, Jindřich (referee) ; Zikán, Michal (referee)
Study objectives: To compare the diagnostic reliability, accuracy and safety of ultrasound-guided biopsy and ascites puncture in patients with primarily inoperable malignant tumor of the ovary. Study design: Retrospective and prospective data analysis Settings: Department of Obstetrics and Gynecology, Medical Faculty and Teaching Hospital in Pilsen Methods: We retrospectively analyzed a group of patients with primarily inoperable ovarian tumor, who underwent an ascites puncture with subsequent cytologic examination as a part of tumor verification before neoadjuvent chemotherapy commencement. The results were compared to a group of patients, who underwent an ultrasound-guided biopsy with subsequent histopathologic examination for determining of their diagnosis. We compared the adequacy, i.e. possibility to verify biologic nature, origin and histologic subtype of the tumor, accuracy, i.e. agreement between the result of the diagnostic method and final postoperative histology, and safety, i.e. recorded complications of the procedure. To validate the result of this comparative study we prospectively evaluated a group of patients where both methods were used. Results: In the ascites puncture group, a total of 55 procedures were performed. Adequate sample was obtained in in all patients and one severe...
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Flow behaviour of sand-water mixture in horizontal and inclined pipes
Vlasák, Pavel ; Chára, Zdeněk ; Matoušek, Václav ; Kesely, Mikoláš ; Krupička, Jan ; Konfršt, Jiří ; Mildner, Michael
Pipelines transporting slurries in different industrial applications often contain inclined sections. The effect of pipe inclination, slurry concentration and mean velocity on the flow behaviour, deposition\nlimit velocity, and internal structure of a settling slurry was studied in an experimental pipe loop of inner diameter D = 100 mm. The slurry consisted from water and a narrow particle size distribution sand of mean diameter d50 = 0.55 mm. The experiments focused on the effects of the pipe inclination on solids distribution and deposition limit velocity. The concentration distribution in pipe cross-section was studied with application of a gamma-ray densitometer. The study revealed the stratified flow pattern of the medium sand-water mixture in inclined pipe sections. Experimental results show that the degree of the slurry stratification decreased with an increasing angle of inclination in the ascending pipe sections. The slurry stratification affected the deposition limit velocity. Mean in situ concentration for the descending flow was always lower than that for the ascending flow. The deposition limit in ascending pipe, in comparison with that in a horizontal pipe, slightly increased up to inclination angle about +25°, and then remained practically constant. For negative pipe inclination over – 30° no deposition limit was observed.
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18th International Conference on Transport & Sedimentation of Solid Particles
Sobota, J. ; Vlasák, Pavel ; Matoušek, Václav
The Proceedings comprise text of 50 oral contributions dealing with two-phase and multiphase flows, Newtonian and non-Newtonian flows, designing, optimization and operation of hydrotransport and pneumotransport systems, wear and corrosions, pumps and valves, sediment transport in rivers and water reservoirs, hydraulic storage of tailings, sedimentation and thickening, methods and techniques of measurement, instrumentation for laboratory, field and industrial systems.
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Effect of pipe inclination on local concentration and flow behaviour of settling slurry
Vlasák, Pavel ; Chára, Zdeněk ; Matoušek, Václav ; Kesely, Mikoláš ; Konfršt, Jiří ; Mildner, Michael
Settling slurry, consisted from narrow-graded sand of mean particle diameter 0.87 mm and water, was investigated on an experimental pipe loop of inner diameter 100 mm. The investigation was focused on the effect of the pipe inclination, slurry concentration, and velocity on concentration distribution, and deposition limit. The settling slurries tend to stratify, a layered structure is typical for a settling slurry flow. Slurry stratification is sensitive to pipe inclination, and differs for the positive and negative pipe inclination. Deposition limit increases with pipe inclination up to about 25°, and then remain nearly constant.
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Effect of pipe inclination on flow behaviour of fine-grained settling slurry
Vlasák, Pavel ; Chára, Zdeněk ; Matoušek, Václav ; Konfršt, Jiří ; Kesely, Mikoláš
The effect of flow parameters of fine-grained settling slurry on the pressure drop-velocity relationship, deposition limit velocity and local concentration distribution was studied in an experimental pipe loop of inner diameter D = 100 mm with inclinable pipe sections for pipe inclination ranging from – 45° to +45°. The slurry consisted from water and narrow particle size distribution glass beads of mean diameter d50 = 0.18 mm. The concentration distribution was studied with application of a gamma-ray densitometry. The deposition velocity was defined as the flow velocity at which stationary deposit started to be formed at the pipe invert. The study revealed the stratified flow pattern of the studied slurry in inclined pipe sections, for slurry velocities below to the deposition limit sliding or stationary bed were created in ascending pipe sections. For low pipe inclination ( < ± 25°) the effect of inclination on local concentration distribution was not significant. Mean transport concentration for descending flow was lower than that for the ascending flow Deposition limit in inclined pipe was slightly lower than that in horizontal pipe. Frictional pressure drops in ascending pipe were higher than that in descending pipe, the difference decreased with increasing velocity and inclination.
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Settling slurry flow near deposition velocity in inclined pipe of negative slope
Kesely, Mikoláš ; Matoušek, Václav ; Vlasák, Pavel
Pipe flow of sand-water slurry (settling slurry) is sensitive to pipe inclination. The effect of the angle to which the partially stratified flow is inclined from the horizontal has been subject to investigation in numerous studies. However, almost all of them focus on ascending flows, i.e. flows inclined to positive angles of inclination. It is well known that settling slurry flows inclined to negative slopes (descending flows) differ from those inclined to positive slopes, particularly at velocities near the deposition limit. The deposition limit velocity is the flow velocity at which stationary deposit starts to be formed at the bottom of the pipe. We investigate the effect of the negative slope on pipe flow near deposition limit velocity in the broad range of inclination angles. Besides the deposition limit, we focus on the distribution of solids across the pipe cross section. We combine experimental approach with mathematical modelling. Our new experiments with medium-to-coarse sand (mass-medium grain size 0.87 mm) in a 100-mm pipe inclined from 0 to -45 degree provide suitable data for a validation of predictions of our layered model for partially stratified flows in inclined pipes.
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Experimental investigation of settling slurry flow in inclined pipe sections
Vlasák, Pavel ; Chára, Zdeněk ; Matoušek, Václav ; Kesely, Mikoláš ; Konfršt, Jiří
Narrow particle size distribution glass beads-water slurry flow in the pipe sections of different inclination were investigated on an experimental pipe loop of inner diameter D = 100 mm. The study refers to the effect of pipe inclination and slurry velicity on local concentration distribution, pressure drop-velocity relationship, and deposition limit. The study revealed that the glass beads-water mixtures in the inclined pipe sections were significantly stratified: the solid particles moved principally close to the pipe invert, and for flow velocities close to the deposition limit sliding bed or stationary deposit is created even in inclined pipe sections.
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Flow of heterogeneous slurry in horizontal and inclined pipes
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří ; Kysela, Bohuš
Narrow particle size distribution heterogeneous slurries were investigated on an experimental pipe loop with the horizontal and inclined pipe sections of inner diameter 100 mm. The investigation was focused on the effect of the pipe inclination, average slurry velocity and overall concentration and on the local concentration distribution, pressure drop, deposition limit and carrier liquid-particle slip velocity. The local concentration distribution was studied with the application of a gamma-ray densitometer. Mixture flow-behaviour and particles motion were investigated in a pipe viewing section. The study revealed that the heterogeneous slurries in the horizontal and inclined pipe sections were significantly stratified, the solid particles moved principally close to the pipe invert, and particle saltation becomes the dominant mode of particle conveying for higher and moderate flow velocities. Carrier liquid-particle slip velocity depends not only on the mixture velocity, but also on particle position in the pipe cross-section. The effect of pipe inclination on the frictional pressure drop in inclined pipe sections depends on mixture velocity, in ascending pipe section decreases with increasing mixture velocity and in descending pipe section the frictional pressure drop gradually decreased with increasing pipe inclination.
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Concentration distribution and slip velocity of coarse-particle-water mixture in horizontal and inclined pipe sections
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří
Narrow particle size distribution basalt pebbles of mean particle size 11.5 mm conveyed by water in the pipe sections of different inclination were investigated on an experimental pipe loop of inner diameter D = 100 mm. Mixture flow-behaviour and the concentration distribution were studied in a pipe viewing section and with the application of a gamma-ray densitometer. The study refers to the effect of mixture velocity, overall concentration, and angle of pipe inclination on chord-averaged concentration profiles and local concentration maps. The study revealed that the coarse particle-water mixtures in the inclined pipe sections were significantly stratified, the solid particles moved principally close to the pipe invert, and for higher and moderate flow velocities particle saltation becomes the dominant mode of particle conveying.
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