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Robert G. Hahn - One of the best experts on this subject based on the ideXlab platform.

  • Continuous versus Intermittent Flow irrigation in transurethral resection of the prostate.
    Urology, 1994
    Co-Authors: Jan Ekengren, Robert G. Hahn
    Abstract:

    Abstract Objective. We compared fluid absorption, blood loss, and immediate postoperative complications in transurethral resection of the prostate (TURP) performed with the continuous Flow and the Intermittent Flow irrigation techniques. We also studied pressure conditions under which fluid absorption occurs when continuous Flow irrigation is used. Methods. One experienced urologic surgeon performed TURP in 40 patients using suprapubic drainage of the bladder and in 40 other patients using the Intermittent-filling technique. Fluid absorption was measured by the ethanol method every ten minutes. The intravesical pressure was recorded continuously in 23 of the patients with suprapubic drainage. Results. Fluid absorption was more common when suprapubic drainage was used (P Conclusions. Continuous Flow irrigation promoted fluid absorption, which occurred at lower pressures than commonly believed. With respect to other parameters, we found no superiority of one irrigating technique over the other.

Hamid Naderan - One of the best experts on this subject based on the ideXlab platform.

  • Experimental study of condensation heat transfer for R141b in Intermittent Flow regime within a smooth horizontal tube
    Experimental Thermal and Fluid Science, 2019
    Co-Authors: Hamed Nasrfard, Hassan Rahimzadeh, A. Ahmadpour, Hamid Naderan
    Abstract:

    Abstract This study investigates condensation of R141b in an 8 mm ID horizontal smooth tube. Condensation of R141b is conducted at an average saturation temperature of 40 ° C with mass fluxes ranging from 40 to 400 kg m−2 s−1. The plant runs with low vapor quality of refrigerant where Intermittent Flow is expected to be the dominant Flow regime. Visualization images presented for Intermittent Flow regime. Observation results compared with four types of Flow regime map and a modified version of El Hajal-Thome map is presented. Condensation heat transfer coefficient in Intermittent zone is evaluated. Comparison between the available experimental data and the values predicted by the most popular and current correlations for condensation heat transfer in horizontal tubes are reported. Finally, a new correlation is proposed to predict condensation heat transfer coefficient within Intermittent region.

Francesco Versino - One of the best experts on this subject based on the ideXlab platform.

  • Intermittent Flow regime of water/gas emissions as sinkhole trigger in alluvial plains: a study case at S. Vittorino plain (Rieti, Italy)
    Environmental Earth Sciences, 2015
    Co-Authors: Mario Voltaggio, Massimo Spadoni, Francesco Versino
    Abstract:

    A case of natural Intermittent Flow regime (slug/churn) of a CO_2-enriched spring water is discussed as an example of trigger process for the collapse of sinkholes. The hydrodynamic regime of the spring, situated in the area of S. Vittorino alluvial plain (Rieti, Italy), was investigated by monitoring acoustic emission, carrying out geochemical analyses and installing a sedimentation trap during a long-lasting phase of slug Flow regime followed by a churn Flow phase. The slug and churn Flows can erode and transport upward fine and medium size particles of sand, progressively removing them from some underground shallow sandy levels where the groundwater mixes with gas of deep crustal origin to form the Intermittent Flow that can be observed at the surface. The slug Flow regime was characterized by a stable slugging frequency whose value is in agreement with the estimated superficial velocities of Taylor bubbles and liquid slugs. The transition from the slug to the churn Flow regime, the latter characterized by an increase of gas flux and by more severe erosion, was also observed during our study. In a span of 15 years, the transport of sand upward could produce a collapse volume similar to those of the sinkholes that recently originated in the same area. The study of such multiphase Flows prolonged over time could help to monitor and prevent the sinkhole formation process.

  • Intermittent Flow regime of water gas emissions as sinkhole trigger in alluvial plains a study case at s vittorino plain rieti italy
    Environmental Earth Sciences, 2015
    Co-Authors: Mario Voltaggio, Massimo Spadoni, Francesco Versino
    Abstract:

    A case of natural Intermittent Flow regime (slug/churn) of a CO2-enriched spring water is discussed as an example of trigger process for the collapse of sinkholes. The hydrodynamic regime of the spring, situated in the area of S. Vittorino alluvial plain (Rieti, Italy), was investigated by monitoring acoustic emission, carrying out geochemical analyses and installing a sedimentation trap during a long-lasting phase of slug Flow regime followed by a churn Flow phase. The slug and churn Flows can erode and transport upward fine and medium size particles of sand, progressively removing them from some underground shallow sandy levels where the groundwater mixes with gas of deep crustal origin to form the Intermittent Flow that can be observed at the surface. The slug Flow regime was characterized by a stable slugging frequency whose value is in agreement with the estimated superficial velocities of Taylor bubbles and liquid slugs. The transition from the slug to the churn Flow regime, the latter characterized by an increase of gas flux and by more severe erosion, was also observed during our study. In a span of 15 years, the transport of sand upward could produce a collapse volume similar to those of the sinkholes that recently originated in the same area. The study of such multiphase Flows prolonged over time could help to monitor and prevent the sinkhole formation process.

Ran Suo - One of the best experts on this subject based on the ideXlab platform.

  • Enhancement reagents for simultaneous vapor generation of zinc and cadmium with Intermittent Flow system coupled to atomic fluorescence spectrometry
    Analytica Chimica Acta, 2004
    Co-Authors: Hanwen Sun, Ran Suo
    Abstract:

    Abstract Simultaneous vapor generation of zinc (Zn) and cadmium (Cd) was evaluated by atomic fluorescence spectrometry coupled with an Intermittent Flow vapor generation system. Some complexing reagents, surfactant and transition metal ions were respectively tested as enhancement reagents. Experiments showed that an appropriate amount of 8-hydroxyquinoline or phenanthroline and nickel ion simultaneously, effectively improved the vapor generation efficiency of Zn and Cd. The volatile species generation was presumed to be a hydrogenation process interpreting how the enhancement reagents played an important role in vapor generation. Additionally, due to the instability of volatile species, reaction temperature, rapid and sufficient mixing of reagents and rapid separation of the volatile species from liquid phase were also crucial. The method of simultaneous determination of Zn and Cd by Intermittent Flow vapor generation led to the development of atomic fluorescence spectrometry. The detection limits (3 σ b ) were 1.6 μg l −1 for Zn and 0.01 μg l −1 for Cd and the relative standard deviations were 3.6% for Zn (50 μg l −1 , n =11) and 1.7% for Cd (2 μg l −1 , n =11) respectively. Results for the determination of Zn and Cd have been confirmed by the analysis of CRMs with good agreement between the certified and found values.

Wei Zeng - One of the best experts on this subject based on the ideXlab platform.