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Sample records for inverted bubbly slug

  1. The cultivation of Anabaena variabilis in a bubble column operating under bubbly and slug flows.

    Science.gov (United States)

    Yoon, Jong Hyun; Choi, Shin Sik; Park, Tai Hyun

    2012-04-01

    In a bubble column reactor with an inner diameter of 6cm and a height of 63cm for the culture of cyanobacteria two different shapes of bubbles can be generated, resulting in bubbly flow or slug flow. Growth of Anabaena variabilis under slug flow (1.9g/l/day) was 1.73 times higher than that under bubbly flow (1.1g/l/day) when the specific irradiation rate was maintained above 10μmol/s/g dry cell. Although a stepwise increase in superficial gas velocity enhanced the average cell growth rate under bubbly flow by 1.57 times, the average cell growth rate during the deceleration phase under bubbly flow (1.98g/l/day) was 0.61 times smaller than that under slug flow (3.22g/l/day). These results demonstrate that the bubble shape in the slug flow was advantageous in regards to the radial circulation of cells.

  2. Experimental investigation of the effect of liquid viscosity on slug flow in small diameter bubble column

    Directory of Open Access Journals (Sweden)

    Azzopardi Barry John

    2012-04-01

    Full Text Available The effect of liquid viscosity on slug flow in a 50 mm diameter bubble column was investigated experimentally using air-silicone oil as operating fluid with silicone oil of viscosities 5, 100, 1000 and 5000 mPa.s. Data was collected using Electrical Capacitance Tomography (ECT, a non-intrusive advanced instrumentation measuring technique and the high Speed Video Camera, through which the slug parameters such as length of Taylor bubbles and liquid slug, void fraction in Taylor bubbles and liquid slug, slug frequency, film thickness and pressure gradient in the slug, were measured and analyzed. The analysis was done using the void fraction time series, probability density function and power spectral density plots. Superficial gas velocities of 0.02≤Ugs≤0.361 m/s were used in the experiment. It was also observed that as viscosity increases, slug frequency, structure velocity, length of liquid slug, void fraction in liquid slug and void fraction in Taylor bubbles decreases; while the length of Taylor bubble, film thickness and pressure gradient in the slug increases.

  3. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

    Science.gov (United States)

    McQuillen, J.

    2000-01-01

    The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and

  4. Two phase flow bifurcation due to turbulence: transition from slugs to bubbles

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2015-09-01

    The bifurcation of slugs to bubbles within two-phase flow patterns in a minichannel is analyzed. The two-phase flow (water-air) occurring in a circular horizontal minichannel with a diameter of 1 mm is examined. The sequences of light transmission time series recorded by laser-phototransistor sensor is analyzed using recurrence plots and recurrence quantification analysis. Recurrence parameters allow the two-phase flow patterns to be found. On changing the water flow rate we identified partitioning of slugs or aggregation of bubbles.

  5. Testing for Nonlinearity in Dynamic Characteristics of Vertical Upward Oil-Gas-Water Three-phase Bubble and Slug Flows

    Institute of Scientific and Technical Information of China (English)

    朱雷; 金宁德; 高忠科; 杜萌; 王振亚

    2012-01-01

    Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.

  6. Bubbly, Slug, and Annular Two-Phase Flow in Tight-Lattice Subchannels

    Directory of Open Access Journals (Sweden)

    Horst-Michael Prasser

    2016-08-01

    Full Text Available An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI, Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1 a vertical channel modeling a pair of neighboring subchannels; and (2 an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of 16 × 64 measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

  7. Effect of Gas- and Liquid-injection Methods on Formation of Bubble and Liquid Slug at Merging Micro T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Kyoung [Kyungnam Univ., Changwon (Korea, Republic of); Lee, Chi Young [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2016-04-15

    In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions 600 μm × 600 μm was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T{sub g}as-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T{sub l}iquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T{sub l}iquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T{sub g}as-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

  8. 3-dimensional Simulation of an Air-lift Pump from Bubbly to Slug Flow

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hongrae; Jo, Daeseong [Kyungpook National Univ, Daegu (Korea, Republic of)

    2015-10-15

    The air-lift pump has been used in various applications with its merit that it can pump up without any moving parts. E.g. coffee percolator, petroleum industry, suction dredge, OTEC i.e. ocean thermal energy conversion and so on. By the merit, it has high durability for high temperature water or vapor, and fluid-solid mixture like waste water, muddy water and crude, which cause problems when it's pumped up with general pumps. In this regard, the air-lift pump has been one of the most desirable technology. A typical air-lift pump configuration is illustrated in Figure 01. The principle of this pump is very simple. When air is injected from the injector at bottom of a submerged tube, i.e., air bubbles are suspended in the liquid, the average density of the mixture in the tube is less than that of the surrounding fluid in the reservoir. Then hydrostatic pressure over the length of the tube is decreased. This buoyancy force causes a pumping action. The comparison of the simulated results, experimental result, and theoretical result is been able by data shown as Figure 04. They have similar trends but they also have a little differences because there are some limits of simulating the flow regimes. At the different flow condition, different coefficients for friction factor or pressure drop should be used, but this simulation uses a laminar condition and the theoretical equations are valid only for slug regime where the air flow rate is lower than the other regimes. From these causes, the differences has arisen, and difference comes bigger as the air flow rate increases, i.e., becoming annular flow regime or churn flow regime.

  9. On the interaction of Taylor bubbles rising in two-phase co-current slug flow in vertical columns: turbulent wakes

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, A.M.F.R.; Campos, J.B.L. [Centro de Estudos de Fenomenos de Transporte, Universidade do Porto Rua (Portugal); Coelho Pinheiro, M.N. [Dept. de Engenharia Quimica, Politecnico de Coimbra (Portugal)

    2001-12-01

    An experimental study on the interaction between Taylor bubbles rising through a co-current flowing liquid in a vertical tube with 32 mm of internal diameter is reported. The flow pattern in the bubble's wake was turbulent and the flow regime in the liquid slug was either turbulent or laminar. When the flow regime in the liquid slug is turbulent (i) the minimum distance between bubbles above which there is no interaction is 5D-6D; (ii) the bubble's rising velocity is in excellent agreement with the Nicklin relation; (iii) the experimental values of the bubble length compare well with theoretical predictions (Barnea 1990); (iv) the distance between consecutive bubbles varied from 13D to 16D and is insensitive to the liquid Reynolds number. When the flow regime in the liquid slug is laminar (i) the wake length is about 5D-6D; (ii) the minimum distance between bubbles above which there is no interaction is higher than 25D; (iii) the bubble's rising velocity is significantly smaller than theoretical predictions. These results were explained in the light of the findings of Pinto et al. (1998) on coalescence of two Taylor bubbles rising through a co-current liquid. (orig.)

  10. Two new disposable bioreactors for plant cell culture: The wave and undertow bioreactor and the slug bubble bioreactor.

    Science.gov (United States)

    Terrier, Bénédicte; Courtois, Didier; Hénault, Nicolas; Cuvier, Arnaud; Bastin, Maryse; Aknin, Aziz; Dubreuil, Julien; Pétiard, Vincent

    2007-04-01

    The present article describes two novel flexible plastic-based disposable bioreactors. The first one, the WU bioreactor, is based on the principle of a wave and undertow mechanism that provides agitation while offering convenient mixing and aeration to the plant cell culture contained within the bioreactor. The second one is a high aspect ratio bubble column bioreactor, where agitation and aeration are achieved through the intermittent generation of large diameter bubbles, "Taylor-like" or "slug bubbles" (SB bioreactor). It allows an easy volume increase from a few liters to larger volumes up to several hundred liters with the use of multiple units. The cultivation of tobacco and soya cells producing isoflavones is described up to 70 and 100 L working volume for the SB bioreactor and WU bioreactor, respectively. The bioreactors being disposable and pre-sterilized before use, cleaning, sterilization, and maintenance operations are strongly reduced or eliminated. Both bioreactors represent efficient and low cost cell culture systems, applicable to various cell cultures at small and medium scale, complementary to traditional stainless-steel bioreactors.

  11. Ringiculid bubble snails recovered as the sister group to sea slugs (Nudipleura)

    Science.gov (United States)

    Kano, Yasunori; Brenzinger, Bastian; Nützel, Alexander; Wilson, Nerida G.; Schrödl, Michael

    2016-08-01

    Euthyneuran gastropods represent one of the most diverse lineages in Mollusca (with over 30,000 species), play significant ecological roles in aquatic and terrestrial environments and affect many aspects of human life. However, our understanding of their evolutionary relationships remains incomplete due to missing data for key phylogenetic lineages. The present study integrates such a neglected, ancient snail family Ringiculidae into a molecular systematics of Euthyneura for the first time, and is supplemented by the first microanatomical data. Surprisingly, both molecular and morphological features present compelling evidence for the common ancestry of ringiculid snails with the highly dissimilar Nudipleura—the most species-rich and well-known taxon of sea slugs (nudibranchs and pleurobranchoids). A new taxon name Ringipleura is proposed here for these long-lost sisters, as one of three major euthyneuran clades with late Palaeozoic origins, along with Acteonacea (Acteonoidea + Rissoelloidea) and Tectipleura (Euopisthobranchia + Panpulmonata). The early Euthyneura are suggested to be at least temporary burrowers with a characteristic ‘bubble’ shell, hypertrophied foot and headshield as exemplified by many extant subtaxa with an infaunal mode of life, while the expansion of the mantle might have triggered the explosive Mesozoic radiation of the clade into diverse ecological niches.

  12. Bubbling bed catalytic hydropyrolysis process utilizinig larger catalyst particles and small biomass particles featuring an anti-slugging reactor

    Energy Technology Data Exchange (ETDEWEB)

    Marker, Terry L.; Felix, Larry G.; Linck, Martin B.; Roberts, Michael J.

    2016-12-06

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  13. Bubbling bed catalytic hydropyrolysis process utilizing larger catalyst particles and smaller biomass particles featuring an anti-slugging reactor

    Science.gov (United States)

    Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

    2014-09-23

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  14. Bubbling bed catalytic hydropyrolysis process utilizinig larger catalyst particles and small biomass particles featuring an anti-slugging reactor

    Science.gov (United States)

    Marker, Terry L.; Felix, Larry G.; Linck, Martin B.; Roberts, Michael J.

    2016-12-06

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  15. Bubbles

    DEFF Research Database (Denmark)

    Dholakia, Nikhilesh; Turcan, Romeo V.

    2013-01-01

    A goal of our ongoing research stream is to develop a multidisciplinary metatheory of bubbles. In this viewpoint paper we put forward a typology of bubbles by comparing four types of assets – entertainment, commodities, financial securities (stocks), and housing properties – where bubbles could a...

  16. Two-phase slug flow in vertical and inclined tubes

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    Gas-liquid slug flow is investigated experimentally in vertical and inclined tubes.The non-invasive measuremnts of the gas-liquid slug flow are taken by using the EKTAPRO 1000 High Speed Motion Analyzer.The information on the velocity of the Talyor bubble,the size distribution of the dispersed bubbles in the liquid slugs and some characteristics of the liquid film around the Taylor bubble are obtained.The experimental results are in good agreement with the available data.

  17. Initiation of slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Hanratty, T.J.; Woods, B.D. [Univ. of Illinois, Urbana, IL (United States)

    1995-12-31

    The initiation of slug flow in a horizontal pipe can be predicted either by considering the stability of a slug or by considering the stability of a stratified flow. Measurements of the shedding rate of slugs are used to define necessary conditions for the existence of a slug. Recent results show that slugs develop from an unstable stratified flow through the evolution of small wavelength waves into large wavelength waves that have the possibility of growing to form a slug. The mechanism appears to be quite different for fluids with viscosities close to water than for fluids with large viscosities (20 centipoise).

  18. Minimum slugging velocity in fluidized beds containing vertical rods

    Energy Technology Data Exchange (ETDEWEB)

    Coronella, C.J.; Lee, S.Y.; Seader, J.D. (University of Utah, Salt Lake City, UT (United States). Dept. of Chemical Engineering)

    1994-09-01

    A new method for determining the onset of slugging in fluidized beds is presented. Pressure-drop fluctuations, measured from below the distributor to the gas exit line, are transformed to the frequency domain by the power spectral desity function (PSDF). The dominant frequency of the PSDF corresponds to the eruption frequency of bubbles or slugs. A fluidized bed is in the slugging regime when this dominant frequency, f[sub d], remains constant with changing gas velocity. This method is an improvement over previous methods because of the simple nature of the apparatus required, and because it is possible to locate the pressure probes so that they do not interfere with the fluidization or undergo rapid wear from the constant particle movement. This method was used to determine the gas velocity corresponding to the transition from the bubbling to the slugging regime for a 10cm diameter bed of sand fluidized with air and containing three 1.9cm diameter vertical rods at 5.2cm centre-to-centre triangular spacing and extending the length of the bed, and to compare the results with those from the same bed without any internal rods. The presence of the vertical rods inhibited the onset of the slugging regime, and significantly extended the bubbling regime to higher gas velocities. 32 refs., 12 figs.

  19. A heat transfer model for slug flow boiling within microchannels

    Science.gov (United States)

    Magnini, Mirco; Thome, John

    2016-11-01

    We propose a novel physics-based model for the fluid mechanics and heat transfer associated with slug flow boiling in horizontal circular microchannels, to update the widely used three-zone model for the design of multi-microchannel evaporators. The flow is modelled as the cyclic passage of a liquid slug, an elongated bubble which traps a thin liquid film against the channel wall, and a dry vapor plug. The capillary flow theory, extended to incorporate evaporation effects, is applied to estimate the bubble velocity along the channel. A liquid film thickness prediction method considering bubble proximity effects, which may limit the radial extension of the film, is included. Theoretical heat transfer models accounting for the thermal inertia of the liquid film and for the recirculating flow within the liquid slug are utilized. The heat transfer model is compared to experimental data taken from three independent studies: 833 slug flow boiling data points covering R134a, R245fa and R236fa and channel diameters from 0.4 mm to 1 mm. The new model predicts more than 80% of the database to within +/- 30 % and it represents an important step toward a complete physics-based modelling of bubble dynamics and heat transfer within microchannels under evaporating flow conditions.

  20. Influence of the initial conditions for the numerical simulation of two-phase slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Pachas Napa, Alex A.; Morales, Rigoberto E.M.; Medina, Cesar D. Perea

    2010-07-01

    Multiphase flows in pipelines commonly show several patterns depending on the flow rate, geometry and physical properties of the phases. In oil production, the slug flow pattern is the most common among the others. This flow pattern is characterized by an intermittent succession in space and time of an aerated liquid slug and an elongated gas bubble with a liquid film. Slug flow is studied through the slug tracking model described as one-dimensional and Lagrangian frame referenced. In the model, the mass and the momentum balance equations are applied in control volumes constituted by the gas bubble and the liquid slug. Initial conditions must be determined, which need to reproduce the intermittence of the flow pattern. These initial conditions are given by a sequence of flow properties for each unit cell. Properties of the unit cell in initial conditions should reflect the intermittence, for which they can be analyzed in statistical terms. Therefore, statistical distributions should be obtained for the slug flow variables. Distributions are complemented with the mass balance and the bubble design model. The objective of the present work is to obtain initial conditions for the slug tracking model that reproduce a better adjustment of the fluctuating properties for different pipe inclinations (horizontal, vertical or inclined). The numerical results are compared with experimental data obtained by PFG/FEM/UNICAMP for air-water flow at 0 deg, 45 deg and 90 deg and good agreement is observed. (author)

  1. Hydrodynamics of gas-liquid slug flow along vertical pipes in turbulent regime-An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Mayor, T.S.; Ferreira, V.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal); Campos, J.B.L.M. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal)], E-mail: jmc@fe.up.pt

    2008-08-15

    An experimental study on free-bubbling gas-liquid (air-water) vertical slug flow was developed using a non-intrusive image analysis technique. The flow pattern in the near-wake of the bubbles and in the main liquid between bubbles was turbulent. A single correlation for the bubble-to-bubble interaction is proposed, relating the trailing bubble velocity to the length of the liquid slug ahead of the bubble. The proposed correlation is shown to be independent of column diameter, column vertical coordinate, superficial liquid and gas velocities and the velocity and length of the leading bubble. Frequency distribution curves, averages, modes and standard deviations are reported, for distributions of bubble velocity, bubble length and liquid slug length, for each experimental condition studied. Good agreement was found between theoretical predictions and experimental results regarding the upward velocity of undisturbed bubbles, in a 0.032 m internal diameter column. A considerable discrepancy was found, though, for a 0.052 m internal diameter column. The acquired experimental data are crucial for the development and validation of a robust slug flow simulator.

  2. Three-dimensional numerical simulations of three-phase slug flows in horizontal pipes

    Science.gov (United States)

    Wang, Yan; Yang, Junfeng; Matar, Omar

    2015-11-01

    One of the most common flow regimes in pipelines is that of slug flow: slug bodies corresponding to alternating blocks of aerated liquid which bridge the pipe, separated by elongated bubbles; the latter ride atop a liquid layer. The slugs travel at velocities that exceed the mixture superficial velocity; this can potentially cause structural damage, particularly at pipe bends and junctions. Two-phase slug flows have received considerable attention in the literature both experimentally and computationally but there has been very little work carried out on three-phase slugging. In the present work, the evolution of oil-water-air three-phase slug flow in a horizontal cylindrical pipe is investigated using two-dimensional and three-dimensional computational fluid dynamics simulations. The parameters characterising three-phase slug flow, e.g. slug length, propagation velocity, and slug formation frequency, are determined for various gas and liquid superficial velocities for a given pipe geometry. The results of this work are compared to available experimental data and numerical solutions based on approximate, one-dimensional models relying on the use of empirical correlations. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  3. Development of Liquid Slug Length in Gas-Liquid Slug Flow along Horizontal Pipeline: Experiment and Simulation%水平管内气液段塞流液塞长度发展规律的实验和模拟研究

    Institute of Scientific and Technical Information of China (English)

    王鑫; 郭烈锦; 张西民

    2006-01-01

    The liquid slug length distribution is crucial for designing the downstream processing system with multiphase pipeline. Experiments were conducted in a 133m long horizontal test loop. The measurements were performed by conductivity probes to determine the liquid slug length distribution. The data covered both the slug and plug flow regimes. From experimental results, the mean liquid slug lengths were relatively insensitive to gas and liquid flow rates in the higher mixture velocity range. But in the lower mixture velocity range, the mean liquid slug length decreased and then increased with mixture velocity. It shows that the development length of slug flow was longer than χ/D=1157. A slug tracking model was adapted to study the evolution of liquid slug length distribution in a horizontal pipeline. In the present model, the wake effect of elongated bubble and the pressure drop due to acceleration are taken into account and random slug lengths are introduced at the entrance. The results of the model are compared with the measured slug length distributions of slug flow regime. It shows that the predicted mean and maximum slug lengths are in agreement with the experimental data at x/D=1157 and the form of the slug length distributions is also predicted well by the model.

  4. Dynamics of a two-phase flow through a minichannel: Transition from churn to slug flow

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2016-04-01

    The churn-to-slug flow bifurcations of two-phase (air-water) flow patterns in a 2mm diameter minichannel were investigated. With increasing a water flow rate, we observed the transition of slugs to bubbles of different sizes. The process was recorded by a digital camera. The sequences of light transmission time series were recorded by a laser-phototransistor sensor, and then analyzed using the recurrence plots and recurrence quantification analysis (RQA). Due to volume dependence of bubbles velocities, we observed the formation of periodic modulations in the laser signal.

  5. Transitional Criterion From Bubbly Flow to Slug Flow in Vertical Rectangular Channels Based on Drift-flux Model%基于漂移流模型的矩形通道内泡状流-弹状流转变准则

    Institute of Scientific and Technical Information of China (English)

    闫超星; 阎昌琪; 孙立成; 王洋

    2013-01-01

    以空气和水为工质,对竖直向上矩形通道(40 mm ×1.41 mm ,40 mm ×10 mm)两相流流型特性进行了可视化研究。气液相表观速度分别为0.01~0.59 m/s和0.02~3.72 m/s。基于3个经典的泡状流向弹状流转变准则,考虑矩形通道的尺寸效应,导出了泡状流向弹状流转变时的临界空泡份额为0.23。以窄边宽度2.5 mm为界,将矩形通道分为小通道和常规通道两类,对泡状流向弹状流转变准则进行修正,修正准则能很好地预测实验值。为进一步验证修正准则的准确性和适用性,将修正准则与Mishima、Wilmarth和Sadatomi等的实验数据进行了对比,结果显示修正准则同样具有较好的预测效果。%A visualized study of flow patterns was carried out for air-water two-phase flow in two narrow rectangular ducts (40 mm × 1.41 mm , 40 mm × 10 mm ) respectively .The superficial velocity ranges of air and water were 0.01-0.59 m/s and 0.02-3.72 m/s .Based on three classical criteria on transition from bubbly flow to slug flow ,critical transition void fraction 0.23 was deduced by introducing the effect of channel size .The rectangular ducts were classified as small channel (s≤2.5 mm) and conventional channel (s>2.5 mm) ,based on which a modified transition criterion for bubbly flow to slug flow was proposed .The modified criterion shows a good agreement with the experimental data from this study .Experimental data from Mishima ,Wilmarth and Sadatomi etc .were also collected to further evaluate the accuracy and applicability of the modified criterion ,showing a good prediction to these experimental data as well .

  6. Experiments on the transition from stratified to slug flow in multiphase pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Kristiansen, Olav

    2004-12-01

    Severe slugging is reported from some field operations, where an increase in the production rate leads to a transition from steady stratified flow to slug flow in the pipeline. The slugs can be longer than anticipated for hydrodynamic slugging and the flow transients can then be a limitation for the production capacity. The objective was to perform a study on the flow pattern transition from stratified to slug flow. A particular point of interest was the possible occurrence of metastable flow and large initial slugs at elevated pressures. New data have been acquired in an experimental investigation of the transition from stratified to slug flow in horizontal and near-horizontal pipes at atmospheric and pressurised conditions. The experiments were performed with two-phase gas liquid and three-phase gas-liquid-liquid flows. Two flow facilities were used the NTNU Multiphase Flow Laboratory (short flow loop) and the SINTEF Multi-phase Flow Laboratory (long flow loop). Hold-up and pressure drop were measured, and flow patterns were determined visually and by evaluation of hold-up time traces. The following parameters were varied: 1) Inlet flow condition by variation of inlet pipe inclination. 2) System pressure (gas density). 3) Test section inclination (horizontal and near-horizontal). 4) Water cut. 5) Gas and liquid flow rates. 6) Pipe length. Slug flow or stratified flow was introduced upstream to promote either early or delayed transition to slug flow in the test section. A time series analysis was performed on the hold-up time traces, and average and distribution slug characteristics are reported, e.g. slug frequency, bubble propagation velocity, slug fraction, slug length, and growth rate. The results have been compared with steady state model predictions. The work consists of the following parts. 1) An initial study was performed at atmospheric air-water conditions in a short pipe. 2) Experiments at atmospheric and elevated pressures were performed in the medium

  7. Characterization of SLUG microwave amplifiers

    Science.gov (United States)

    Hoi, I.-C.; Zhu, S.; Thorbeck, T.; McDermott, R.; Mutus, J.; Jeffrey, E.; Barends, R.; Chen, Y.; Roushan, P.; Fowler, A.; Sank, D.; White, T.; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Kelly, J.; Megrant, A.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Vainsencher, A.; Wenner, J.; Martinis, J. M.

    2015-03-01

    With the rapid growth of superconducting circuits quantum technology, a near quantum-limited amplifier at GHz frequency is needed to enable high fidelity measurements. We describe such an amplifier, the SQUID based, superconducting low inductance undulatory galvanometer (SLUG) amplifier. We measure the full scattering matrix of the SLUG. In particular, we measure both forward and reverse gain, as well as reflection. We see 15dB forward gain with added noise from one quanta to several quanta. The -1 dB compression point is around -95 dBm, about two orders of magnitude higher than that of typical Josephson parametric amplifiers. With these properties, SLUG is well suited for the high fidelity, simultaneous multiplexed readout of superconducting qubits.

  8. Interfacial area, velocity and void fraction in two-phase slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Kojasoy, G. [Univ. of Wisconsin, Milwaukee, WI (United States); Riznic, J.R. [Atomic Energy Control Board, Ottawa (Canada)

    1997-12-31

    The internal flow structure of air-water plug/slug flow in a 50.3 mm dia transparent pipeline has been experimentally investigated by using a four-sensor resistivity probe. Liquid and gas volumetric superficial velocities ranged from 0.55 to 2.20 m/s and 0.27 to 2.20 m/s, respectively, and area-averaged void fractions ranged from about 10 to 70%. The local distributions of void fractions, interfacial area concentration and interface velocity were measured. Contributions from small spherical bubbles and large elongated slug bubbles toward the total void fraction and interfacial area concentration were differentiated. It was observed that the small bubble void contribution to the overall void fraction was small indicating that the large slug bubble void fraction was a dominant factor in determining the total void fraction. However, the small bubble interfacial area contribution was significant in the lower and upper portions of the pipe cross sections.

  9. High-resolution slug testing.

    Science.gov (United States)

    Zemansky, G M; McElwee, C D

    2005-01-01

    The hydraulic conductivity (K) variation has important ramifications for ground water flow and the transport of contaminants in ground water. The delineation of the nature of that variation can be critical to complete characterization of a site and the planning of effective and efficient remedial measures. Site-specific features (such as high-conductivity zones) need to be quantified. Our alluvial field site in the Kansas River valley exhibits spatial variability, very high conductivities, and nonlinear behavior for slug tests in the sand and gravel aquifer. High-resolution, multilevel slug tests have been performed in a number of wells that are fully screened. A general nonlinear model based on the Navier-Stokes equation, nonlinear frictional loss, non-Darcian flow, acceleration effects, radius changes in the wellbore, and a Hvorslev model for the aquifer has been used to analyze the data, employing an automated processing system that runs within the Excel spreadsheet program. It is concluded that slug tests can provide the necessary data to identify the nature of both horizontal and vertical K variation in an aquifer and that improved delineation or higher resolution of K structure is possible with shorter test intervals. The gradation into zones of higher conductivity is sharper than seen previously, and the maximum conductivity observed is greater than previously measured. However, data from this project indicate that well development, the presence of fines, and the antecedent history of the well are important interrelated factors in regard to slug-test response and can prevent obtaining consistent results in some cases.

  10. Drift flux model as approximation of two fluid model for two phase dispersed and slug flow in tube

    Energy Technology Data Exchange (ETDEWEB)

    Nigmatulin, R.I.

    1995-09-01

    The analysis of one-dimensional schematizing for non-steady two-phase dispersed and slug flow in tube is presented. Quasi-static approximation, when inertia forces because of the accelerations of the phases may be neglected, is considered. Gas-liquid bubbly and slug vertical upward flows are analyzed. Non-trivial theoretical equations for slip velocity for these flows are derived. Juxtaposition of the derived equations for slip velocity with the famous Zuber-Findlay correlation as cross correlation coefficients is criticized. The generalization of non-steady drift flux Wallis theory taking into account influence of wall friction on the bubbly or slug flows for kinematical waves is considered.

  11. Algebraic model for bubble tracking in horizontal gas-liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Felipe G.C. de; Tisserant, Hendy R. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Morales, Rigoberto E.M. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais; Mazza, Ricardo A.; Rosa, Eugenio S. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2008-07-01

    The current work extends the concept of unit-cell applied in gas-liquid slug flow models to predict the evolution of the gas and liquid flow properties along a horizontal pipe. The motivation of this model is its simplicity, easiness of application and low computational cost. It is a useful tool of reference data generation in order to check the consistency of numerical slug tracking models. The potential of the model is accessed by comparing the gas bubbles and liquid slug sizes, the translational bubble velocity and the pressure drop against experimental data. (author)

  12. Injection of Nucleate-Boiling Slug Flows into a Heat Exchange Chamber in Microgravity

    Science.gov (United States)

    2015-06-01

    AFRL-AFOSR-UK-TR-2015-0029 Injection of nucleate- boiling slug flows into a heat exchange chamber in microgravity Jaume...2015 2. REPORT TYPE Final Report 3. DATES COVERED (From – To) 20 March 2012 – 19 March 2015 4. TITLE AND SUBTITLE Injection of nucleate- boiling ...method to produce controlled boiling through a localized nucleation cavity feeding a capillary crossflow forming regular trains of bubbles. The main

  13. Detection of Gas Slugs in Heat Pipes

    Science.gov (United States)

    Jones, J. A.

    1985-01-01

    Temperature sensing system detects presence of gas slugs in heat pipes. System designed for operation between zero and 70 degrees C and detects noncondensable pockets of gas that result from decomposition of ammonia cooling fluid. Slugs 1 in. (25mm) in length detected.

  14. Simultaneous PIV and pulsed shadow technique in slug flow: a solution for optical problems

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, S. [Karman Institute for Fluid Dynamics, Chaussee de Waterloo 72, B-1640, Rhode Saint Genese (Belgium); Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Sousa, R.G.; Pinto, A.M.F.R.; Campos, J.B.L.M. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Riethmuller, M.L. [Karman Institute for Fluid Dynamics, Chaussee de Waterloo 72, B-1640, Rhode Saint Genese (Belgium)

    2003-12-01

    A recent technique of simultaneous particle image velocimetry (PIV) and pulsed shadow technique (PST) measurements, using only one black and white CCD camera, is successfully applied to the study of slug flow. The experimental facility and the operating principle are described. The technique is applied to study the liquid flow pattern around individual Taylor bubbles rising in an aqueous solution of glycerol with a dynamic viscosity of 113 x 10{sup -3} Pa s. With this technique the optical perturbations found in PIV measurements at the bubble interface are completely solved in the nose and in annular liquid film regions as well as in the rear of the bubble for cases in which the bottom is flat. However, for Taylor bubbles with concave oblate bottoms, some optical distortions appear and are discussed. The measurements achieved a spatial resolution of 0.0022 tube diameters. The results reported show high precision and are in agreement with theoretical and experimental published data. (orig.)

  15. Experimental Study on Rising Velocity of Different Nitrogen Bubbles in of Circular Pipe

    Science.gov (United States)

    Zhang, Hua; Liu, Yiping; Wang, Jing

    2007-06-01

    Nitrogen bubble rising velocity in bottom of circular pipe has been studied by virtual experiment with high-speed camera. The obtained images are processed systematically. Based on Cole's and Mendelson's empirical formula of bubble rising velocity, fitting formula of nitrogen bubble rising velocity in bottom of circular pipe has been acquired through analyzing nitrogen bubble rising velocity. The treatment results of experimental data show that the rising velocity is related with the diameter of bubbles. And rising velocity of slug bubble is relative to L/D and change law is found. Through this experiment, we research rising velocity's change law, which is the spade work to study propagation mechanism of nitrogen slug bubble in circular pipe.

  16. Science Bubbles

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Pedersen, David Budtz

    2013-01-01

    Much like the trade and trait sof bubbles in financial markets,similar bubbles appear on the science market. When economic bubbles burst, the drop in prices causes the crash of unsustainable investments leading to an investor confidence crisis possibly followed by a financial panic. But when...... bubbles appear in science, truth and reliability are the first victims. This paper explores how fashions in research funding and research management may turn science into something like a bubble economy....

  17. Fern and bryophyte endozoochory by slugs.

    Science.gov (United States)

    Boch, Steffen; Berlinger, Matthias; Fischer, Markus; Knop, Eva; Nentwig, Wolfgang; Türke, Manfred; Prati, Daniel

    2013-07-01

    Endozoochory plays a prominent role for the dispersal of seed plants, and dispersal vectors are well known. However, for taxa such as ferns and bryophytes, endozoochory has only been suggested anecdotally but never tested in controlled experiments. We fed fertile leaflets of three ferns and capsules of four bryophyte species to three slug species. We found that, overall, spores germinated from slug feces in 57.3% of all 89 fern and in 51.3% of all 117 bryophyte samples, showing that the spores survived gut passage of slugs. Moreover, the number of samples within which spores successfully germinated did not differ among plant species but varied strongly among slug species. This opens new ecological perspectives suggesting that fern and bryophyte endozoochory by gastropods is a so-far-overlooked mode of dispersal, which might increase local population sizes of these taxa by spore deposition on suitable substrates.

  18. Shell tension forces propel Dictyostelium slugs forward.

    Science.gov (United States)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2012-12-01

    The Dictyostelium slug is an excellent model system for studying collective movements, as it is comprised of about 10(5) cells all moving together in the same direction. It still remains unclear how this movement occurs and what the physical mechanisms behind it are. By applying our recently developed 3D traction force microscopy, we propose a simple explanation for slug propulsion. Most of the forces are exerted by the sheath surrounding the slug. This secreted shell is under a rather uniform tension (around 50 mN m(-1)) and will give rise to a tissue under pressure. Finally, we propose that this pressure will naturally push the slug tip forwards if a gradient of shell mechanical properties takes place in the very anterior part of the raised tip.

  19. Shell tension forces propel Dictyostelium slugs forward

    Science.gov (United States)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2012-12-01

    The Dictyostelium slug is an excellent model system for studying collective movements, as it is comprised of about 105 cells all moving together in the same direction. It still remains unclear how this movement occurs and what the physical mechanisms behind it are. By applying our recently developed 3D traction force microscopy, we propose a simple explanation for slug propulsion. Most of the forces are exerted by the sheath surrounding the slug. This secreted shell is under a rather uniform tension (around 50 mN m-1) and will give rise to a tissue under pressure. Finally, we propose that this pressure will naturally push the slug tip forwards if a gradient of shell mechanical properties takes place in the very anterior part of the raised tip.

  20. OIL SLUGS FOR PRODUCTION OF PISTON RING

    Directory of Open Access Journals (Sweden)

    V. F. Bevza

    2008-01-01

    Full Text Available The developed technological process of continuously cyclic casting by frosting allows to receive high-quality hollow cylindrical slugs of cast iron for production of critical parts. 

  1. Gas slug ascent through rheologically stratified conduits

    Science.gov (United States)

    Capponi, Antonio; James, Mike R.; Lane, Steve J.

    2016-04-01

    Textural and petrological evidence has indicated the presence of viscous, degassed magma layers at the top of the conduit at Stromboli. This layer acts as a plug through which gas slugs burst and it is thought to have a role in controlling the eruptive dynamics. Here, we present the results of laboratory experiments which detail the range of slug flow configurations that can develop in a rheologically stratified conduit. A gas slug can burst (1) after being fully accommodated within the plug volume, (2) whilst its base is still in the underlying low-viscosity liquid or (3) within a low-viscosity layer dynamically emplaced above the plug during the slug ascent. We illustrate the relevance of the same flow configurations at volcanic-scale through a new experimentally-validated 1D model and 3D computational fluid dynamic simulations. Applied to Stromboli, our results show that gas volume, plug thickness, plug viscosity and conduit radius control the transition between each configuration; in contrast, the configuration distribution seems insensitive to the viscosity of magma beneath the plug, which acts mainly to deliver the slug into the plug. Each identified flow configuration encompasses a variety of processes including dynamic narrowing and widening of the conduit, generation of instabilities along the falling liquid film, transient blockages of the slug path and slug break-up. All these complexities, in turn, lead to variations in the slug overpressure, mirrored by changes in infrasonic signatures which are also associated to different eruptive styles. Acoustic amplitudes are strongly dependent on the flow configuration in which the slugs burst, with both acoustic peak amplitudes and waveform shapes reflecting different burst dynamics. When compared to infrasonic signals from Stromboli, the similarity between real signals and laboratory waveforms suggests that the burst of a slug through a plug may represent a viable first-order mechanism for the generation of

  2. Vapor Bubbles

    Science.gov (United States)

    Prosperetti, Andrea

    2017-01-01

    This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

  3. Bubble coalescence

    NARCIS (Netherlands)

    Orvalho, Sandra; Ruzicka, Marek C.; Olivieri, Giuseppe; Marzocchella, Antonio

    2015-01-01

    The goal of this study is to present new experimental data on the effect of the bubble approach velocity and liquid viscosity on pairwise bubble coalescence. Measurements were performed to investigate the dynamics of bubble coalescence under well-defined laboratory conditions. Air and pure

  4. Bubble rupture in bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Chen Rouxi

    2015-01-01

    Full Text Available As the distinctive properties and different applications of nanofibers, the demand of nanofibers increased sharply in recently years. Bubble electrospinning is one of the most effective and industrialized methods for nanofiber production. To optimize the set-up of bubble electrospinning and improve its mass production, the dynamic properties of un-charged and charged bubbles are studied experimentally, the growth and rupture process of a bubble are also discussed in this paper.

  5. Determination of slug permeability factor for pressure drop prediction of slug flow pneumatic conveying

    Institute of Scientific and Technical Information of China (English)

    Shengming Tan; Kenneth C.Williams; Mark G.Jones; Tobias Krull

    2008-01-01

    Current models for pressure drop prediction of slug flow pneumatic conveying in a horizontal pipeline system assume some type of steady state conditions for prediction,which limits their capability for increased predictive accuracy relative to experimental data.This is partly because of the nature of slug flow pneumatic conveying system,which,as a dynamic system,never becomes stable.By utilising conservation of mass (airflow),a dynamic pressure analysis model is proposed on the basis of the derivative of the upstream pressure behaviour.The rate of air permeation through slug,one of the important factors in the conservation model,is expressed as a function of a slug permeability factor.Other factors such as slug velocity,slug length and the fraction of stationary layer were also considered.Several test materials were conveyed in single-slug tests to verify the proposed pressure drop model,showing good agreement between the model and experimental results.

  6. Bubble systems

    CERN Document Server

    Avdeev, Alexander A

    2016-01-01

    This monograph presents a systematic analysis of bubble system mathematics, using the mechanics of two-phase systems in non-equilibrium as the scope of analysis. The author introduces the thermodynamic foundations of bubble systems, ranging from the fundamental starting points to current research challenges. This book addresses a range of topics, including description methods of multi-phase systems, boundary and initial conditions as well as coupling requirements at the phase boundary. Moreover, it presents a detailed study of the basic problems of bubble dynamics in a liquid mass: growth (dynamically and thermally controlled), collapse, bubble pulsations, bubble rise and breakup. Special emphasis is placed on bubble dynamics in turbulent flows. The analysis results are used to write integral equations governing the rate of vapor generation (condensation) in non-equilibrium flows, thus creating a basis for solving a number of practical problems. This book is the first to present a comprehensive theory of boil...

  7. Inverted Order

    Institute of Scientific and Technical Information of China (English)

    贺文婷

    2015-01-01

    This paper discusses the issue related to Inverted Order. There are two forms of Inversion, which are Partial Inversion and Complete Inversion. I analyze three main reasons of Inversion and its usages in details. And what’s more, under what conditions should we use Inverted construction? How can we distinguish the different usages of Complete Inversion and Partial Inversion? In this paper, I will talk more details about Inversion.%本篇论文讨论有关倒装语序的问题。倒装有两种形式,即部分倒装和完全倒装。文中分析了倒装的三个原因及其用法。具体的,在什么情况下需要使用倒装结构?我们如何区分完全倒装和部分倒装的不同用法?本篇论文将作具体阐述。

  8. Bubble, Bubble, Toil and Trouble.

    Science.gov (United States)

    Journal of Chemical Education, 2001

    2001-01-01

    Bubbles are a fun way to introduce the concepts of surface tension, intermolecular forces, and the use of surfactants. Presents two activities in which students add chemicals to liquid dishwashing detergent with water in order to create longer lasting bubbles. (ASK)

  9. Exploring Bubbles

    Science.gov (United States)

    O'Geary, Melissa A.

    Bubbles provide an enjoyable and festive medium through which to teach many concepts within the science topics of light, color, chemistry, force, air pressure, electricity, buoyancy, floating, density, among many others. In order to determine the nature of children's engagement within a museum setting and the learning opportunities of playing with bubbles, I went to a children's interactive museum located in a metropolitan city in the Northeastern part of the United States.

  10. Antigravitating bubbles

    CERN Document Server

    Barnaveli, A T; Barnaveli, Andro; Gogberashvili, Merab

    1995-01-01

    We investigate the gravitational behavior of spherical domain walls (bubbles) arising during the phase transitions in the early Universe. In the thin-wall approximation we show the existence of the new solution of Einstein equations with negative gravitational mass of bubbles and the reversed direction of time flow on the shell. This walls exhibit gravitational repulsion just as the planar walls are assumed to do. The equilibrium radius and critical mass of such objects are found for realistic models.

  11. Bubble diagnostics

    Science.gov (United States)

    Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.

    2003-01-01

    The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.

  12. In situ visualization study of CO 2 gas bubble behavior in DMFC anode flow fields

    Science.gov (United States)

    Yang, H.; Zhao, T. S.; Ye, Q.

    This paper reports on a visual study of the CO 2 bubble behavior in the anode flow field of an in-house fabricated transparent Direct Methanol Fuel Cell (DMFC), which consisted of a membrane electrode assembly (MEA) with an active area of 4.0 × 4.0 cm 2, two bipolar plates with a single serpentine channel, and a transparent enclosure. The study reveals that at low current densities, small discrete bubbles appeared in the anode flow field. At moderate current densities, a number of gas slugs formed, in addition to small discrete bubbles. And at high current densities, the flow field was predominated by rather long gas slugs. The experiments also indicate that the cell orientation had a significant effect on the cell performance, especially at low methanol flow rates; for the present flow field design the best cell performance could be achieved when the cell was orientated vertically. It has been shown that higher methanol solution flow rates reduced the average length and the number of gas slugs in the flow field, but led to an increased methanol crossover. In particular, the effect of methanol solution flow rates on the cell performance became more pronounced at low temperatures. The effect of temperature on the bubble behavior and the cell performance was also examined. Furthermore, for the present flow field consisting of a single serpentine channel, the channel-blocking phenomenon caused by CO 2 gas slugs was never encountered under all the test conditions in this work.

  13. Dynamics of Bubbles Rising in Finite and Infinite Media

    Energy Technology Data Exchange (ETDEWEB)

    C.C. Maneri; P.F. Vassallo

    2000-10-27

    The dynamic behavior of single bubbles rising in quiescent liquid Suva (R134a) in a duct has been examined through the use of a high speed video system. Size, shape and velocity measurements obtained with the video system reveal a wide variety of characteristics for the bubbles as they rise in both finite and infinite media. This data, coupled with previously published data for other working fluids, has been used to assess and extend a rise velocity model given by Fan and Tsuchiya. As a result of this assessment, a new rise velocity model has been developed which maintains the physically consistent characteristics of the surface tension in the distorted bubbly regime. In addition, the model is unique in that it covers the entire range of bubble sizes contained in the spherical, distorted and planar slug regimes.

  14. INTRODUCED LAND SNAILS AND SLUGS IN COLOMBIA.

    Science.gov (United States)

    Hausdorf, BERNHARD

    2002-05-01

    Twelve species of introduced land molluscs, including seven slug species, have been found in the cold zone above 2000 m altitude in the Departamentos Cundinamarca and Boyacá, and the Distrito Especial in Colombia. The introduced land molluscs remain generally restricted to disturbed environments, from which native species are often absent. Most recorded species originated from Europe. Deroceras laeve has been present in Colombia for more than a century, whereas the other species are probably more recent introductions. The records of Boettgerilla pallens, which is indigenous to the Caucasus and has spread over Europe only during the last decades, demonstrates that the process of introduction of alien molluscs is continuing.

  15. Hydrodynamic models for slurry bubble column reactors

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D. [IIT Center, Chicago, IL (United States)

    1995-12-31

    The objective of this investigation is to convert a {open_quotes}learning gas-solid-liquid{close_quotes} fluidization model into a predictive design model. This model is capable of predicting local gas, liquid and solids hold-ups and the basic flow regimes: the uniform bubbling, the industrially practical churn-turbulent (bubble coalescence) and the slugging regimes. Current reactor models incorrectly assume that the gas and the particle hold-ups (volume fractions) are uniform in the reactor. They must be given in terms of empirical correlations determined under conditions that radically differ from reactor operation. In the proposed hydrodynamic approach these hold-ups are computed from separate phase momentum balances. Furthermore, the kinetic theory approach computes the high slurry viscosities from collisions of the catalyst particles. Thus particle rheology is not an input into the model.

  16. Bubbling Threat

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The shift of China’s monetary policy stance from "moderately loose" to "prudent" in 2011 indicates curbing inflation and asset bubbles have become the Central Government’s top priority. But is China’s bubble problem short-term or long-term? Is it only monetary or related to economic structure? Is it the cause of China’s economic imbalance or the result? And what kind of deep-rooted problems in the macro economy does it reflect? All these questions call for deep thought,said Zhang Monan,a

  17. Slug tests in the presence of background head trends.

    Science.gov (United States)

    Ostendorf, David W; DeGroot, Don J

    2010-01-01

    We extend Bouwer and Rice (1976) slug test theory to incorporate background head trends that may be important in incompressible material of low permeability k. The extension, which features a convolution integral of the background head, is closed form for linear trends. A sensitivity study suggests that a rising background head can diminish the head changes associated with a slug-out test and underestimate k if it is ignored, as does falling background trend with a slug-in test. A falling background head can reinforce slug-in test head change and, if ignored, can overestimate k, as does a rising background head with a slug-out test. The simple extension is verified by field tests in glacial till and stratified drift deposits in eastern Massachusetts.

  18. SLUG: A New Way to Stochastically Light Up Galaxies

    Science.gov (United States)

    Fumagalli, M.; da Silva, R.; Krumholz, M.; Bigiel, F.

    2011-06-01

    We present SLUG, a new code to "Stochastically Light Up Galaxies". SLUG populates star clusters by randomly drawing stars from an initial mass function (IMF) and then following their time evolution with stellar models and an observationally-motivated prescription for cluster disruption. For a choice of star formation history, metallicity, and IMF, SLUG outputs synthetic photometry for clusters and field stars with a proper treatment of stochastic star formation. SLUG generates realistic distributions of star clusters, demonstrating the range of properties that result from finite sampling of an IMF and a random distribution of ages. The simulated data sets provide a quantitative means to address open problems in studies of star formation in galaxies and clusters, such as a test for IMF variations that are suggested by the systematic deficiency in the Hα/UV ratio in outer disks or in dwarf galaxies. SLUG will be made publicly available through the website: http://sites.google.com/site/runslug/.

  19. Leverage bubble

    Science.gov (United States)

    Yan, Wanfeng; Woodard, Ryan; Sornette, Didier

    2012-01-01

    Leverage is strongly related to liquidity in a market and lack of liquidity is considered a cause and/or consequence of the recent financial crisis. A repurchase agreement is a financial instrument where a security is sold simultaneously with an agreement to buy it back at a later date. Repurchase agreement (repo) market size is a very important element in calculating the overall leverage in a financial market. Therefore, studying the behavior of repo market size can help to understand a process that can contribute to the birth of a financial crisis. We hypothesize that herding behavior among large investors led to massive over-leveraging through the use of repos, resulting in a bubble (built up over the previous years) and subsequent crash in this market in early 2008. We use the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles and behavioral finance to study the dynamics of the repo market that led to the crash. The JLS model qualifies a bubble by the presence of characteristic patterns in the price dynamics, called log-periodic power law (LPPL) behavior. We show that there was significant LPPL behavior in the market before that crash and that the predicted range of times predicted by the model for the end of the bubble is consistent with the observations.

  20. Gas-Liquid Slug Flow in Microchannels

    Science.gov (United States)

    Guenther, Axel; de Mas, Nuria; Jhunjhunwala, Manish; Schmidt, Martin A.; Jensen, Klavs F.

    2003-11-01

    Slug flow is not only an attractive regime for conducting gas-liquid reactions in microchemical systems. It also provides a normal velocity that enhances liquid mixing for high Peclet number flows, e.g. for particle synthesis. We previously extended the flow regime diagrams initially obtained for micro heat-exchangers to the liquid deficient conditions relevant to microreactors. We use silicon-based single microchannels with rectangular and triangular cross-section and hydraulic diameters of 40-400 microns that are capped with Pyrex to provide for optical access. Ethanol, water, toluene, and nitrogen are the working fluids. Superficial velocities are varied between 0.01 and 10 m/s for the gas and 0.001 and 1 m/s for the liquid with corresponding Capillary and Bond numbers between 0.001 and 0.01. We complement pulsed-laser fluorescence microscopy and confocal scanning microscopy with a non-intrusive optical sensor to monitor the transient flow at sampling rates of 10 kHz. Interfacial area, void fraction, slug velocity U_s, and the transversal velocity component introduced by internal circulation in the liquid are determined. For comparable Peclet numbers, the transverse velocity between channel wall and center is lO0.1 U_s and allows for shorter mixing lengths than reported for micromixers with patterned walls. Gas and liquid are completely separated on-chip subsequent to the mixing step.

  1. Buddly, slug, and annular two-phase flow in tight-lattice subchannels

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, Horst-Michael; Bolesch, Charistian; Cramer, Kerstin; Papadopoulos, Petros; Saxena, Abhishek; Zboray, Robert [ETH Zurich, Dept. of Mechanical and Process Engineering (D-MAVT), Zurich (Switzerland); Ito, Daisuke [Kyoto University, Research Reactor Institute, Osaka (Japan)

    2016-08-15

    An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ) and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI), Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1) a vertical channel modeling a pair of neighboring subchannels; and (2) an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of 16 × 64 measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

  2. [The expression of transcription factors Snail and Slug in epithelial-mesenchymal transition of human lens epithelial cells induced by transforming growth factor-β2].

    Science.gov (United States)

    Wang, Y N; Pei, C; Qin, L; Li, J M; Yi, J L; Chen, L

    2016-04-11

    To investigate the expression of transcription factors snail and slug in epithelial mesenchymal transition (EMT) of human lens epithelial cells (HLEC) induced by transforming growth factor-β2 (TGF-β2). Experimental research. HLEC were treated with different concentrations of TGF-β2 (1.0 and 10.0 μg/L) for different time. The morphological changes were observed under inverted microscope. The expression and cellular localization of snail and slug were evaluated by immunofluorescence. Expressions of snail, slug, E-Cadherin and α-SMA were further determined by Western blot analysis. Single factor analysis of variance, rank sum test and Pearson correlation were used for statistical analysis. Cultured HLEC were polygonal monolayer cells with tight intercellular adhesion closely and patchy distribution. After treatment of different doses of TGF-β2 for 24 h, HLEC became isolated, exhibited long spindle-like shape as fibroblastic phenotype. The immunofluorescence staining indicated that snail and slug were localized in the nuclei. The expressions of snail and slug appeared to be positive correlative to TGF-β2 dose (snail protein expression: 0.74±0.16, 1.13±0.03, 1.54±0.18 and slug protein expression: 1.96±0.02, 3.12±0.09, 4.07±0.12 in HLEC treated with 0.1, 1.0 and 10 μg/L TGF-β2 respectively) (χ(2)=9.62,P=0.022;F=241.10,Psnail and slug in HLEC were also increased with extending duration of TGF-β2 (1.0 μg/L). The expression levels of both proteins were modestly up-regulated at 8 hours, robustly increased at 24 h, reached peak at 48h and began to decline at 72 h (snail protein expression: 0.90±0.13, 1.43±0.14, 1.96±0.27, 1.57±0.16 and slug protein expression: 0.91±0.36, 1.24±0.16, 2.44±0.26, 1.43±0.16 in HLEC treated with 1.0 μg/L TGF-β2 for 8 h, 24 h, 48 h and 72 h respectively) (F=12.49,P=0.001;F=14.03,Psnail and slug might be time and dose-dependently involved in in-vitro TGF-β2-induced EMT of HLEC. (Chin J Ophthalmol, 2016, 52: 285-290).

  3. Bubble Drag Reduction Requires Large Bubbles

    Science.gov (United States)

    Verschoof, Ruben A.; van der Veen, Roeland C. A.; Sun, Chao; Lohse, Detlef

    2016-09-01

    In the maritime industry, the injection of air bubbles into the turbulent boundary layer under the ship hull is seen as one of the most promising techniques to reduce the overall fuel consumption. However, the exact mechanism behind bubble drag reduction is unknown. Here we show that bubble drag reduction in turbulent flow dramatically depends on the bubble size. By adding minute concentrations (6 ppm) of the surfactant Triton X-100 into otherwise completely unchanged strongly turbulent Taylor-Couette flow containing bubbles, we dramatically reduce the drag reduction from more than 40% to about 4%, corresponding to the trivial effect of the bubbles on the density and viscosity of the liquid. The reason for this striking behavior is that the addition of surfactants prevents bubble coalescence, leading to much smaller bubbles. Our result demonstrates that bubble deformability is crucial for bubble drag reduction in turbulent flow and opens the door for an optimization of the process.

  4. Bubble drag reduction requires large bubbles

    CERN Document Server

    Verschoof, Ruben A; Sun, Chao; Lohse, Detlef

    2016-01-01

    In the maritime industry, the injection of air bubbles into the turbulent boundary layer under the ship hull is seen as one of the most promising techniques to reduce the overall fuel consumption. However, the exact mechanism behind bubble drag reduction is unknown. Here we show that bubble drag reduction in turbulent flow dramatically depends on the bubble size. By adding minute concentrations (6 ppm) of the surfactant Triton X-100 into otherwise completely unchanged strongly turbulent Taylor-Couette flow containing bubbles, we dramatically reduce the drag reduction from more than 40% to about 4%, corresponding to the trivial effect of the bubbles on the density and viscosity of the liquid. The reason for this striking behavior is that the addition of surfactants prevents bubble coalescence, leading to much smaller bubbles. Our result demonstrates that bubble deformability is crucial for bubble drag reduction in turbulent flow and opens the door for an optimization of the process.

  5. Blowing bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Casteel, K.

    1999-04-01

    The article, based on a series of interviews with column flotation equipment suppliers, reviews and comments on the progress of bubble generator design. Developments mentioned include the Air/Water sparger from Cominco, the SparJet and SlamJet from CPT, the CISA sparger from Sevala CISA, Microcel flotation columns from Birtley Engineering, Flotaire column flotation cells from LMC International, and the Variable Gap Sparger from MinnovEX. 1 fig., 2 photo.

  6. Expanding Taylor bubble under constant heat flux

    Science.gov (United States)

    Voirand, Antoine; Benselama, Adel M.; Ayel, Vincent; Bertin, Yves

    2016-09-01

    Modelization of non-isothermal bubbles expanding in a capillary, as a contribution to the understanding of the physical phenomena taking place in Pulsating Heat Pipes (PHPs), is the scope of this paper. The liquid film problem is simplified and solved, while the thermal problem takes into account a constant heat flux density applied at the capillary tube wall, exchanging with the liquid film surrounding the bubble and also with the capillary tube outside medium. The liquid slug dynamics is solved using the Lucas-Washburn equation. Mass and energy balance on the vapor phase allow governing equations of bubble expansion to be written. The liquid and vapor phases are coupled only through the saturation temperature associated with the vapor pressure, assumed to be uniform throughout the bubble. Results show an over-heating of the vapor phase, although the particular thermal boundary condition used here always ensures an evaporative mass flux at the liquid-vapor interface. Global heat exchange is also investigated, showing a strong decreasing of the PHP performance to convey heat by phase change means for large meniscus velocities.

  7. Wall—Liquid Mass Transfer for Taylor Bubbles Rising Through Liquid in a Vertical Tube

    Institute of Scientific and Technical Information of China (English)

    YUNJunxian; SHENZiqiu; 等

    2002-01-01

    Wall-liquid mass transfer for Taylor bubbles rising through liquid column in vertical tubes is an important and fundamental topic in industrial processes.In this work,the characteristics of wall-liquid mass transfer for this special case of slug flow were studied experimentally by limiting diffusion current technique (LDCT). Based on the experimental results and the analysis of hydrodynamic mechanisms,it was proposed that four different zones exist,i.e.the laminar falling film zone,the turbulent falling film zone,the wake region and the remaining liquid slug zone.The corresponding correlations for all these zones were developed.

  8. Slug control system; Sistema de controle de golfadas

    Energy Technology Data Exchange (ETDEWEB)

    Borges Filho, Alvaro de Miranda; Meira, Marco Antonio Alves de; Vaz, Celio Eduardo Martins [PETROBRAS, Macae, RJ (Brazil). Unidade de Negocios da Bacia de Campos

    2004-07-01

    Due to the characteristics of flow, gas can separate from oil in the pipelines and risers that link subsea manifolds to production offshore platforms, forming liquid and gas slugs in the production separator. Liquid slugs can cause overflow in the separators. Gas slugs can cause burning in the flare due to the limitation in the turbo-compressors acceleration. In both cases the consequences are loss of production or shut-downs. This paper presents a Slug Control System designed to attenuate severe gas and liquid flow variations. The system consist of a control valve installed in the separator inlet, transmitters, a controller, control algorithm and a monitoring station. This system is operating since October 2003 in a production offshore platform, in Campus Basin, Brazil, with excellent results, reducing the gas burning in 45% without oil production loss. (author)

  9. The potential for slug control with ferric phosphate

    OpenAIRE

    Horgan, A R

    2006-01-01

    Slug and snail damage, especially on young plants can mean serious economic loss for growers. Organic growers have in the past had few, if any, effective products to use for their control. Now ferric phosphate has recently gained organic status from the Organic Farmers and Growers organisation. Its unique mode of action, environmental profile and effectiveness against a range of slug and snail species will make this a first choice for all organic growers. The eventual breakdown components iro...

  10. Fully developed turbulence in slugs of pipe flows

    Science.gov (United States)

    Cerbus, Rory; Liu, Chien-Chia; Sakakibara, Jun; Gioia, Gustavo; Chakraborty, Pinaki

    2015-11-01

    Despite over a century of research, transition to turbulence in pipe flows remains a mystery. In theory the flow remains laminar for arbitrarily large Reynolds number, Re. In practice, however, the flow transitions to turbulence at a finite Re whose value depends on the disturbance, natural or artificial, in the experimental setup. The flow remains in the transition state for a range of Re ~ 0 (1000) ; for larger Re the flow becomes fully developed. The transition state for Re > 3000 consists of axially segregated regions of laminar and turbulent patches. These turbulent patches, known as slugs, grow as they move downstream. Their lengths span anywhere between a few pipe diameters to the whole length of the pipe. Here we report Stereo Particle Image Velocimetry measurements in the cross-section of the slugs. Notwithstanding the continuous growth of the slugs, we find that the mean velocity and stress profiles in the slugs are indistinguishable from that of statistically-stationary fully-developed turbulent flows. Our results are independent of the length of the slugs. We contrast our results with the well-known work of Wygnanski & Champagne (1973), whose measurements, we argue, are insufficient to draw a clear conclusion regarding fully developed turbulence in slugs.

  11. Fama on Bubbles

    DEFF Research Database (Denmark)

    Engsted, Tom

    2016-01-01

    While Eugene Fama has repeatedly expressed his discontent with the notion of an “irrational bubble,” he has never publicly expressed his opinion on “rational bubbles.” On empirical grounds Fama rejects bubbles by referring to the lack of reliable evidence that price declines are predictable. Howe...... component in stock market valuation ratios, consistent with a rational bubble....

  12. Next Generation Inverter

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zilai [General Motors LLC, Detroit, MI (United States); Gough, Charles [General Motors LLC, Detroit, MI (United States)

    2016-04-22

    The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).

  13. Inverted organic photosensitive devices

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Stephen R.; Bailey-Salzman, Rhonda F.

    2016-12-06

    The present disclosure relates to organic photosensitive optoelectronic devices grown in an inverted manner. An inverted organic photosensitive optoelectronic device of the present disclosure comprises a reflective electrode, an organic donor-acceptor heterojunction over the reflective electrode, and a transparent electrode on top of the donor-acceptor heterojunction.

  14. Slug down-regulation by RNA interference inhibits invasion growth in human esophageal squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Zhang Shaoyan

    2011-05-01

    Full Text Available Abstract Background Esophageal squamous cell carcinoma (ESCC is one of the most aggressive carcinomas of the gastrointestinal tract. We assessed the relevance of Slug in measuring the invasive potential of ESCC cells in vitro and in vivo in immunodeficient mice. Methods We utilized RNA interference to knockdown Slug gene expression, and effects on survival and invasive carcinoma were evaluated using a Boyden chamber transwell assay in vitro. We evaluated the effect of Slug siRNA-transfection and Slug cDNA-transfection on E-cadherin and Bcl-2 expression in ESCC cells. A pseudometastatic model of ESCC in immunodeficient mice was used to assess the effects of Slug siRNA transfection on tumor metastasis development. Results The EC109 cell line was transfected with Slug-siRNA to knockdown Slug expression. The TE13 cell line was transfected with Slug-cDNA to increase Slug expression. EC109 and TE13 cell lines were tested for the expression of apoptosis-related genes bcl-2 and metastasis-related gene E-cadherin identified previously as Slug targets. Bcl-2 expression was increased and E-cadherin was decreased in Slug siRNA-transfected EC109 cells. Bcl-2 expression was increased and E-cadherin was decreased in Slug cDNA-transfected TE13 cells. Invasion of Slug siRNA-transfected EC109 cells was reduced and apoptosis was increased whereas invasion was greater in Slug cDNA-transfected cells. Animals injected with Slug siRNA-transfected EC109 cells exhihited fewer seeded nodes and demonstrated more apoptosis. Conclusions Slug down-regulation promotes cell apoptosis and decreases invasion capability in vitro and in vivo. Slug inhibition may represent a novel strategy for treatment of metastatic ESCC.

  15. Modular inverter system

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Mingyao; Hu, Haibing; Kutkut, Nasser; Batarseh, Issa; Shen, John; , Bkayrat, Raed

    2017-08-01

    A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled.

  16. An invasive slug exploits an ant-seed dispersal mutualism.

    Science.gov (United States)

    Meadley Dunphy, Shannon A; Prior, Kirsten M; Frederickson, Megan E

    2016-05-01

    Plant-animal mutualisms, such as seed dispersal, are often vulnerable to disruption by invasive species. Here, we show for the first time how a non-ant invasive species negatively affects seed dispersal by ants. We examined the effects of several animal species that co-occur in a temperate deciduous forest-including native and invasive seed-dispersing ants (Aphaenogaster rudis and Myrmica rubra, respectively), an invasive slug (Arion subfuscus), and native rodents-on a native myrmecochorous plant, Asarum canadense. We experimentally manipulated ant, slug, and rodent access to seed depots and measured seed removal. We also video-recorded depots to determine which other taxa interact with seeds. We found that A. rudis was the main disperser of seeds and that A. subfuscus consumed elaiosomes without dispersing seeds. Rodent visitation was rare, and rodent exclusion had no significant effect on seed or elaiosome removal. We then used data obtained from laboratory and field mesocosm experiments to determine how elaiosome robbing by A. subfuscus affects seed dispersal by A. rudis and M. rubra. We found that elaiosome robbing by slugs reduced seed dispersal by ants, especially in mesocosms with A. rudis, which picks up seeds more slowly than M. rubra. Taken together, our results show that elaiosome robbing by an invasive slug reduces seed dispersal by ants, suggesting that invasive slugs can have profound negative effects on seed dispersal mutualisms.

  17. Secondary oil recovery process. [two separate surfactant slugs

    Energy Technology Data Exchange (ETDEWEB)

    Fallgatter, W.S.

    1969-01-14

    Oil recovery by two separate surfactant slugs is greater than for either one alone. One slug contains a surfactant(s) in either oil or water. The other slug contains surfactant(s) in thickened water. The surfactants are sodium petroleum sulfonate (Promor SS20), polyoxyethylene sorbitan trioleate (Tween 85), lauric acid diethanolamide (Trepoline L), and sodium tridecyl sulfate polyglycol ether (Trepenol S30T). The thickener is carboxymethyl cellulose (Hercules CMC 70-S Medium thickener) or polyvinyl alcohol (Du Pont Elvanol 50-42). Consolidated sandstone cores were flooded with water, followed with Hawes crude, and finally salt water (5 percent sodium chloride) which recovered about 67 percent of the crude. A maximum of 27.5 percent of the residual oil was recovered by surfactant(s) in oil or water followed by fresh water, then surfactant(s) plus thickener in water followed by fresh water. Either surfactant slug may be injected first. Individually, each of the surfactant slugs can recover from about 3 to 11 percent less residual oil than their total recovery when used consecutively.

  18. Modelling of slug dissipation and generation in a hilly-terrain pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.-Q.; El-Safran, E.M.; Jayawardena, S.S.; Redus, C.L.; Brill, J.P. [University of Tulsa (United States). Dept. of Petroleum Engineering

    2000-07-01

    Hilly-terrain pipelines consist of interconnected horizontal, uphill and downhill sections. Slug flow experiences a transition from one state to another as the pipe inclination angle changes. Normally, slugs dissipate if the upward inclination becomes smaller or the downward inclination becomes larger, and slug generation occurs vice versa. Appropriate prediction of the slug characteristics is crucial for the design of pipeline and downstream facilities. In this study, slug dissipation and generation in a valley pipeline configuration (horizontal-downhill-uphill-horizontal) were modeled by use of the method proposed by Zhang et al. The method was developed from the unsteady continuity and momentum equations for slug flow by considering the entire film zone as the control volume. Computed results are compared with experimental measurements at different gas-liquid flow rate combinations. Good agreement is observed for the change of slug body length to slug unit length ratio. (author)

  19. Simulation of horizontal slug-flow pneumatic conveying with kinetic theory

    Institute of Scientific and Technical Information of China (English)

    GU Zhengmeng; GUO Liejin

    2007-01-01

    Wavelike slug-flow is a representative flow type in horizontal pneumatic conveying.Kinetic theory was introduced to establish a 3D kinetic numerical model for wavelike slug gas-solid flow in this paper.Wavelike motion of particulate slugs in horizontal pipes was numerically investigated.The formation and motion process of slugs and settled layer were simulated.The characteristics of the flow,such as pressure drop,air velocity distribution,slug length and settled layer thickness,and the detailed changing characteristics of slug length and settled layer thickness with air velocity were obtained.The results indicate that kinetic theory can represent the physical characteristics of the non-suspension dense phase flow of wavelike slug pneumatic conveying.The experiment in this paper introduced a new idea for the numerical calculation of slug-flow pneumatic conveying.

  20. Challenges in Slug Modeling and Control for Offshore Oil and Gas Productions: A Review Study

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2017-01-01

    the state-of-the-art related to analysis, detection, dynamical modeling and elimination of the slug within the offshore oil & gas Exploration and Production (E&P) processes. Modeling of slugging flow has been used to investigate the slug characteristics and for design of anti-slug control as well, however...... most models require specific facility and operating data which, unfortunately, often is not available from most offshore installations. Anti-slug control have been investigated for several decades in oil & gas industry, but many of these existing methods suffer the consequent risk of simultaneously...... reducing the oil & gas production. This paper concludes that slug is a well defined phenomenon, but even though it has been investigated for several decades the current anti-slug control methods still have problems related to robustness. It is predicted that slug-induced challenges will be even more severe...

  1. A new general pressure-analysis procedure for slug tests

    Energy Technology Data Exchange (ETDEWEB)

    Peres, A.M.M.; Onur, M.; Reynolds, A.C. (Univ. of Tulsa, OK (United States))

    1993-12-01

    A new analysis procedure for determining formation flow capacity and skin factor from slug-test data is presented. The procedure arises from exact deconvolution equations that convert measured slug-test pressure data into equivalent pressure and pressure-derivative responses that would be obtained if the well were produced at a constant surface flow rate. The converted data then can be analyzed by use of existing wellbore-storage and skin type curves for the particular reservoir or well model represented by the field data. For cases where the slug test is short, the authors show that flow rate convolution can be incorporated to improve analysis reliability. The analysis procedures do not require direct knowledge of the sandface flow rate.

  2. Cost effective solar Inverter

    Directory of Open Access Journals (Sweden)

    Nagarathna M

    2015-06-01

    Full Text Available Solar energy the most efficient, eco-friendly and abundantly available energy source in the nature. It can be converted into electrical energy in cost effective manner. In recent years, the interest in solar energy has risen due to surging oil prices and environmental concern. In many remote or underdeveloped areas, direct access to an electric grid is impossible and a photovoltaic inverter system would make life much simpler and more convenient. With this in mind, it is aimed to design, build, and test a solar panel inverter. This inverter system could be used as backup power during outages, battery charging, or for typical household applications. The main components of this solar system are solar cell, dc to dc boost converters, and inverter. Sine wave push pull inverter topology is used for inverter. In this topology only two MOSFETs are used and isolation requirement between control circuit and power circuit is also less which helps to decrease the cost of solar inverter.

  3. Slug to churn transition analysis using wire-mesh sensor

    Science.gov (United States)

    H. F. Velasco, P.; Ortiz-Vidal, L. E.; Rocha, D. M.; Rodriguez, O. M. H.

    2016-06-01

    A comparison between some theoretical slug to churn flow-pattern transition models and experimental data is performed. The flow-pattern database considers vertical upward air-water flow at standard temperature and pressure for 50 mm and 32 mm ID pipes. A briefly description of the models and its phenomenology is presented. In general, the performance of the transition models is poor. We found that new experimental studies describing objectively both stable and unstable slug flow-pattern are required. In this sense, the Wire Mesh Sensor (WMS) can assist to that aim. The potential of the WMS is outlined.

  4. Slug promotes survival during metastasis through suppression of Puma-mediated apoptosis.

    Science.gov (United States)

    Kim, Seaho; Yao, Jiahong; Suyama, Kimita; Qian, Xia; Qian, Bin-Zhi; Bandyopadhyay, Sanmay; Loudig, Olivier; De Leon-Rodriguez, Carlos; Zhou, Zhen Ni; Segall, Jeffrey; Macian, Fernando; Norton, Larry; Hazan, Rachel B

    2014-07-15

    Tumor cells must overcome apoptosis to survive throughout metastatic dissemination and distal organ colonization. Here, we show in the Polyoma Middle T mammary tumor model that N-cadherin (Cdh2) expression causes Slug (Snai2) upregulation, which in turn promotes carcinoma cell survival. Slug was dramatically upregulated in metastases relative to primary tumors. Consistent with a role in metastasis, Slug knockdown in carcinoma cells suppressed lung colonization by decreasing cell survival at metastatic sites, but had no effect on tumor cell invasion or extravasation. In support of this idea, Slug inhibition by shRNA sensitized tumor cells to apoptosis by DNA damage, resulting in caspase-3 and PARP cleavage. The prosurvival effect of Slug was found to be caused by direct repression of the proapoptotic gene, Puma (Bbc3), by Slug. Consistent with a pivotal role for a Slug-Puma axis in metastasis, inhibition of Puma by RNA interference in Slug-knockdown cells rescued lung colonization, whereas Puma overexpression in control tumor cells suppressed lung metastasis. The survival function of the Slug-Puma axis was confirmed in human breast cancer cells, where Slug knockdown increased Puma expression and inhibited lung colonization. This study demonstrates a pivotal role for Slug in carcinoma cell survival, implying that disruption of the Slug-Puma axis may impinge on the survival of metastatic cells.

  5. Is a combination of different natural substances suitable for slug (Arion spp.) control?

    Energy Technology Data Exchange (ETDEWEB)

    Laznik, Ž.; Trdan, S.

    2016-11-01

    In a laboratory study we investigated the contact and barrier efficacy of different natural substances (wood ash, sawdust, hydrated lime, and diatomaceous earth) against slugs of the genus Arion, an important agricultural pest. Natural substances were tested individually and in combination with each other. The experiment was carried out in plastic petri dishes and in glass insectaria. Moistened tampons and fresh leaves of lettuce were placed into both experimental arenas. The slugs were starved for 48 hours prior to the experiment. Six categories of behaviour were identified for slugs in the presence of the natural substances: (1) slug survived the experiment, (2) slug died during the experiment, (3) slug crossed the barrier, (4) slug did not cross the barrier, (5) slug fed on the lettuce, and (6) slug did not feed on the lettuce. The effect of different treatments (natural substances) was significant. The results of our study have shown that hydrated lime had the best contact efficacy on slugs (the mortality of slugs was 100%), both individually and in combination with other substances. The treatments with hydrated lime also proved to be the most efficient barrier preventing slugs from feeding on lettuce. Hydrated lime shows great potential in Arion control in our investigation; however, further research is needed to investigate the practical value (how to avoid the problem when the substance becomes wet), safety and economics of hydrated lime used in this way. (Author)

  6. Internal Representation and Memory Formation of Odor Preference Based on Oscillatory Activities in a Terrestrial Slug

    Science.gov (United States)

    Sekiguchi, Tatsuhiko; Furudate, Hiroyuki; Kimura, Tetsuya

    2010-01-01

    The terrestrial slug "Limax" exhibits a highly developed ability to learn odors with a small nervous system. When a fluorescent dye, Lucifer Yellow (LY), is injected into the slug's body cavity after odor-taste associative conditioning, a group of neurons in the procerebral (PC) lobe, an olfactory center of the slug, is labeled by LY. We examined…

  7. Improved inverted Stepanov apparatus

    Science.gov (United States)

    Berkman, S.; Temple, H. E.

    1979-01-01

    Modifications in inverted Stepanov process improve heat transfer and energy efficiency in growing silicon ribbon crystals. Using system, silicon is directly heated by induction, minimizing heat transfer and contamination problems.

  8. Y-source inverter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang;

    2014-01-01

    This paper introduces a new 3-phase Y-source inverter whose gain is presently not matched by classical impedance-network-based inverters operating at the same duty ratio. The proposed network uses a tightly coupled transformer with three windings. By squeezing the shoot-through range while keeping....... This design flexibility was proven mathematically, and is supported by simulations carried out to prove the concept and validate the analysis....

  9. SLUG promotes prostate cancer cell migration and invasion via CXCR4/CXCL12 axis

    Directory of Open Access Journals (Sweden)

    Uygur Berna

    2011-11-01

    Full Text Available Abstract Background SLUG is a zinc-finger transcription factor of the Snail/Slug zinc-finger family that plays a role in migration and invasion of tumor cells. Mechanisms by which SLUG promotes migration and invasion in prostate cancers remain elusive. Methods Expression level of CXCR4 and CXCL12 was examined by Western blot, RT-PCR, and qPCR analyses. Forced expression of SLUG was mediated by retroviruses, and SLUG and CXCL12 was downregulated by shRNAs-expressing lentiviruses. Migration and invasion of prostate cancer were measured by scratch-wound assay and invasion assay, respectively. Research We demonstrated that forced expression of SLUG elevated CXCR4 and CXCL12 expression in human prostate cancer cell lines PC3, DU145, 22RV1, and LNCaP; conversely, reduced expression of SLUG by shRNA downregulated CXCR4 and CXCL12 expression at RNA and protein levels in prostate cancer cells. Furthermore, ectopic expression of SLUG increased MMP9 expression and activity in PC3, 22RV1, and DU-145 cells, and SLUG knockdown by shRNA downregulated MMP9 expression. We showed that CXCL12 is required for SLUG-mediated MMP9 expression in prostate cancer cells. Moreover, we found that migration and invasion of prostate cancer cells was increased by ectopic expression of SLUG and decreased by SLUG knockdown. Notably, knockdown of CXCL12 by shRNA impaired SLUG-mediated migration and invasion in prostate cancer cells. Lastly, our data suggest that CXCL12 and SLUG regulate migration and invasion of prostate cancer cells independent of cell growth. Conclusion We provide the first compelling evidence that upregulation of autocrine CXCL12 is a major mechanism underlying SLUG-mediated migration and invasion of prostate cancer cells. Our findings suggest that CXCL12 is a therapeutic target for prostate cancer metastasis.

  10. Semistar Invertibility on Integral Domains

    Institute of Scientific and Technical Information of China (English)

    Marco Fontana; Giampaolo Picozza

    2005-01-01

    A natural development of the recent work about semistar operations leads to investigate the concept of "semistar invertibility". Here, we show the existence of a "theoretical obstruction" for extending many results, proved for star-invertibility, to the semistar case. For this reason, we introduce two distinct notions of invertibility in the semistar setting (called *-invertibility and quasi-*-invertibility), we discuss the motivations of these "two levels" of invertibility and we extend, accordingly, many classical results proved for the d-, v-, t- and w-invertibility.

  11. Propylene polymerization in a circulating slugging fluidized bed reactor

    NARCIS (Netherlands)

    Putten, van Inge Cornelia

    2004-01-01

    The work presented in this thesis is concerned with research on the riser of a circulating fluidized bed system for olefin polymerization. In the riser section, fluidization takes place in the transporting slugging mode and polymer particles are produced in the riser in a non-isothermal way. Propert

  12. Modeling cross-hole slug tests in an unconfined aquifer

    CERN Document Server

    Malama, Bwalya; Brauchler, Ralf; Bayer, Peter

    2016-01-01

    A modified version of a published slug test model for unconfined aquifers is applied to cross-hole slug test data collected in field tests conducted at the Widen site in Switzerland. The model accounts for water-table effects using the linearised kinematic condition. The model also accounts for inertial effects in source and observation wells. The primary objective of this work is to demonstrate applicability of this semi-analytical model to multi-well and multi-level pneumatic slug tests. The pneumatic perturbation was applied at discrete intervals in a source well and monitored at discrete vertical intervals in observation wells. The source and observation well pairs were separated by distances of up to 4 m. The analysis yielded vertical profiles of hydraulic conductivity, specific storage, and specific yield at observation well locations. The hydraulic parameter estimates are compared to results from prior pumping and single-well slug tests conducted at the site, as well as to estimates from particle size ...

  13. Modeling cross-hole slug tests in an unconfined aquifer

    Science.gov (United States)

    Malama, Bwalya; Kuhlman, Kristopher L.; Brauchler, Ralf; Bayer, Peter

    2016-09-01

    A modified version of a published slug test model for unconfined aquifers is applied to cross-hole slug test data collected in field tests conducted at the Widen site in Switzerland. The model accounts for water-table effects using the linearized kinematic condition. The model also accounts for inertial effects in source and observation wells. The primary objective of this work is to demonstrate applicability of this semi-analytical model to multi-well and multi-level pneumatic slug tests. The pneumatic perturbation was applied at discrete intervals in a source well and monitored at discrete vertical intervals in observation wells. The source and observation well pairs were separated by distances of up to 4 m. The analysis yielded vertical profiles of hydraulic conductivity, specific storage, and specific yield at observation well locations. The hydraulic parameter estimates are compared to results from prior pumping and single-well slug tests conducted at the site, as well as to estimates from particle size analyses of sediment collected from boreholes during well installation. The results are in general agreement with results from prior tests and are indicative of a sand and gravel aquifer. Sensitivity analysis show that model identification of specific yield is strongest at late-time. However, the usefulness of late-time data is limited due to the low signal-to-noise ratios.

  14. Modelling Morphogenesis: From Single Cells to Crawling Slugs

    NARCIS (Netherlands)

    Savill, N.J.; Hogeweg, P.

    2002-01-01

    We present a three-dimensional hybrid cellular automata (CA)/partial differential equation (PDE) model that allows for the study of morphogenesis in simple cellular systems. We apply the model to the cellular slime mold Dictyostelium discoideum "from single cells to crawling slug". Using simple loca

  15. Brut: Automatic bubble classifier

    Science.gov (United States)

    Beaumont, Christopher; Goodman, Alyssa; Williams, Jonathan; Kendrew, Sarah; Simpson, Robert

    2014-07-01

    Brut, written in Python, identifies bubbles in infrared images of the Galactic midplane; it uses a database of known bubbles from the Milky Way Project and Spitzer images to build an automatic bubble classifier. The classifier is based on the Random Forest algorithm, and uses the WiseRF implementation of this algorithm.

  16. Fama on bubbles

    DEFF Research Database (Denmark)

    Engsted, Tom

    Eugene Fama has repeatedly expressed his discontent with the notion of an irrational bubble. However, he has never publicly expressed his opinion on rational bubbles. This is peculiar since such bubbles build naturally from the rational efficient markets paradigm that Fama strongly adheres to...

  17. Simulation of horizontal pipe two-phase slug flows using the two-fluid model

    Energy Technology Data Exchange (ETDEWEB)

    Ortega Malca, Arturo J. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica. Nucleo de Simulacao Termohidraulica de Dutos (SIMDUT); Nieckele, Angela O. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica

    2005-07-01

    Slug flow occurs in many engineering applications, mainly in the transport of hydrocarbon fluids in pipelines. The intermittency of slug flow causes severe unsteady loading on the pipelines carrying the fluids, which gives rise to design problems. Therefore, it is important to be able to predict the onset and development of slug flow as well as slug characteristics. The present work consists in the simulation of two-phase flow in slug pattern through horizontal pipes using the two-fluid model in its transient and one-dimensional form. The advantage of this model is that the flow field is allowed to develop naturally from a given initial conditions as part of the transient calculation; the slug evolves automatically as a product of the computed flow development. Simulations are then carried out for a large number of flow conditions that lead a slug flow. (author)

  18. Measurement of the recoalescence flux into the rear of a Taylor bubble

    Science.gov (United States)

    Delfos, R.; Rops, C. M.; Kockx, J. P.; Nieuwstadt, F. T. M.

    2001-05-01

    Most of the theoretical models on vertical slug flow assume the mass balance of a Taylor bubble to depend only on the incoming gas flux at the top of the Taylor bubble and on the outgoing entrainment flux at the bottom. This means that the recoalescence flux, which is defined as the fraction of the entrainment flux that coalesces back into the bubble, is neglected. Only in Fernandes et al. [AIChE J. 29, 981 (1983)] is a model proposed for this recoalescence flux but their model has never been verified by measurements. Therefore, we set out in the present research to measure and quantify the recoalescence flux. Our experiments have been carried out in a recirculating flow facility with a vertical cylindrical test section with inner diameter Di=100 mm. In this test section a Taylor bubble is kept at a fixed vertical position by a constant downward liquid flow ΨL. A continuous stream of small helium bubbles is injected into the wake of the Taylor bubble. The recoalescence flux is then determined by measuring the concentration of helium in the Taylor bubble. Our experiments show that there is a recoalescence flux and that in general it cannot be neglected in the mass balance of the Taylor bubble. The total gas loss from the Taylor bubble, Ψin, and the recoalescence flux Ψrec increase both strongly with the Taylor bubble length, LTB. The fraction of entrained bubbles that recoalesces back into the Taylor bubble increases from 10% of the entrainment flux at LTB=60 cm (λG=Ψin/ΨL=4%) to 45% at LTB=91 cm (λG=11%).

  19. PWM inverter technology

    Science.gov (United States)

    Perra, Andre

    1992-04-01

    The use of pulse-width-modulated (PWM) inverter technology by on-line uninterruptible power supplies (UPSs) of 250 VA-750 kVA rating improves transient performance, lowers harmonic distortion, and enhances nonlinear load performance. An account is presently given of the means employed for optimization of a PWM inverter used in a multi-kHz UPS. By using computer modeling to optimize the feedback control loop, the best level of response was furnished, while minimizing switching losses and achieving the highest level of efficiency.

  20. Experiments performed with bubbly flow in vertical pipes at different flow conditions covering the transition region: simulation by coupling Eulerian, Lagrangian and 3D random walks models

    Science.gov (United States)

    Muñoz-Cobo, José; Chiva, Sergio; El Aziz Essa, Mohamed; Mendes, Santos

    2012-08-01

    Two phase flow experiments with different superficial velocities of gas and water were performed in a vertical upward isothermal cocurrent air-water flow column with conditions ranging from bubbly flow, with very low void fraction, to transition flow with some cap and slug bubbles and void fractions around 25%. The superficial velocities of the liquid and the gas phases were varied from 0.5 to 3 m/s and from 0 to 0.6 m/s, respectively. Also to check the effect of changing the surface tension on the previous experiments small amounts of 1-butanol were added to the water. These amounts range from 9 to 75 ppm and change the surface tension. This study is interesting because in real cases the surface tension of the water diminishes with temperature, and with this kind of experiments we can study indirectly the effect of changing the temperature on the void fraction distribution. The following axial and radial distributions were measured in all these experiments: void fraction, interfacial area concentration, interfacial velocity, Sauter mean diameter and turbulence intensity. The range of values of the gas superficial velocities in these experiments covered the range from bubbly flow to the transition to cap/slug flow. Also with transition flow conditions we distinguish two groups of bubbles in the experiments, the small spherical bubbles and the cap/slug bubbles. Special interest was devoted to the transition region from bubbly to cap/slug flow; the goal was to understand the physical phenomena that take place during this transition A set of numerical simulations of some of these experiments for bubbly flow conditions has been performed by coupling a Lagrangian code, that tracks the three dimensional motion of the individual bubbles in cylindrical coordinates inside the field of the carrier liquid, to an Eulerian model that computes the magnitudes of continuous phase and to a 3D random walk model that takes on account the fluctuation in the velocity field of the

  1. Role of the Slug Transcription Factor in Chemically-Induced Skin Cancer

    Directory of Open Access Journals (Sweden)

    Kristine von Maltzan

    2016-02-01

    Full Text Available The Slug transcription factor plays an important role in ultraviolet radiation (UVR-induced skin carcinogenesis, particularly in the epithelial-mesenchymal transition (EMT occurring during tumor progression. In the present studies, we investigated the role of Slug in two-stage chemical skin carcinogenesis. Slug and the related transcription factor Snail were expressed at high levels in skin tumors induced by 7,12-dimethylbenz[α]anthracene application followed by 12-O-tetradecanoylphorbol-13-acetate (TPA treatment. TPA-induced transient elevation of Slug and Snail proteins in normal mouse epidermis and studies in Slug transgenic mice indicated that Slug modulates TPA-induced epidermal hyperplasia and cutaneous inflammation. Although Snail family factors have been linked to inflammation via interactions with the cyclooxygenase-2 (COX-2 pathway, a pathway that also plays an important role in skin carcinogenesis, transient TPA induction of Slug and Snail appeared unrelated to COX-2 expression. In cultured human keratinocytes, TPA induced Snail mRNA expression while suppressing Slug expression, and this differential regulation was due specifically to activation of the TPA receptor. These studies show that Slug and Snail exhibit similar patterns of expression during both UVR and chemical skin carcinogenesis, that Slug and Snail can be differentially regulated under some conditions and that in vitro findings may not recapitulate in vivo results.

  2. Inverter communications using output signal

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Patrick L.

    2017-02-07

    Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.

  3. Microfluidic bubble logic.

    Science.gov (United States)

    Prakash, Manu; Gershenfeld, Neil

    2007-02-09

    We demonstrate universal computation in an all-fluidic two-phase microfluidic system. Nonlinearity is introduced into an otherwise linear, reversible, low-Reynolds number flow via bubble-to-bubble hydrodynamic interactions. A bubble traveling in a channel represents a bit, providing us with the capability to simultaneously transport materials and perform logical control operations. We demonstrate bubble logic AND/OR/NOT gates, a toggle flip-flop, a ripple counter, timing restoration, a ring oscillator, and an electro-bubble modulator. These show the nonlinearity, gain, bistability, synchronization, cascadability, feedback, and programmability required for scalable universal computation. With increasing complexity in large-scale microfluidic processors, bubble logic provides an on-chip process control mechanism integrating chemistry and computation.

  4. Tribonucleation of bubbles

    CERN Document Server

    Wildeman, Sander; Sun, Chao; Lohse, Detlef; Prosperetti, Andrea

    2016-01-01

    We report on the nucleation of bubbles on solids that are gently rubbed against each other in a liquid. The phenomenon is found to depend strongly on the material and roughness of the solid surfaces. For a given surface, temperature, and gas content, a trail of growing bubbles is observed if the rubbing force and velocity exceed a certain threshold. Direct observation through a transparent solid shows that each bubble in the trail results from the early coalescence of several microscopic bubbles, themselves detaching from microscopic gas pockets forming between the solids. From a detailed study of the wear tracks, with atomic force and scanning electron microscopy imaging, we conclude that these microscopic gas pockets originate from a local fracturing of the surface asperities, possibly enhanced by chemical reactions at the freshly created surfaces. Our findings will be useful either for preventing undesired bubble formation or, on the contrary, for "writing with bubbles," i.e., creating controlled patterns ...

  5. Characterizating Multi-layered Coastal Aquifer using Pneumatic Slug Tests

    Science.gov (United States)

    Malama, B.; Abere, M.; Mikenna, M.

    2016-12-01

    Results of pneumatic slug tests conducted in a monitoring wells of a shallow aquifer on the California Central Coast are presented. The aquifer is in the Los Osos groundwater basin on the California Central Coast, a semi-closed near-triangular groundwater basin bounded to the north and south by impermeable igneousbed rock and to the west by the Pacific Ocean. The groundwater basin is a multi-layered system comprising a perched, near-surface semi-confined, and a deep confined aquifer. The unincorporated community of Los Osos is wholly dependent on the groundwater basin that is threatened with seawater intrusion and nitratecontamination. The slug tests reported here were performed in the perched and semi-confined aquifers as part of a seawater intrusion characterization study. The semi-confined and confined aquifers show evidence of seawater intrusion with upconing in some deep aquifer municipal wells. The upconing has beeninterpreted by previous studies as evidence of preferential flow through a high permeability channel. The objective of the work was to test this hypothesis by mapping the horizontal and vertical spatial variability of hydraulic parameters across the basin and establish the extent of the high permeability unit.Here only preliminary results of slug tests conducted across the basin for vertically averaged hydraulic parameters are reported. The results provide an indication of the horizontal variability of hydraulic parameters. An additional study will be performed to characterize the vertical variability to investigate the probableexistsence of a high permeability channel.

  6. Bubbles and market crashes

    CERN Document Server

    Youssefmir, M; Hogg, T; Youssefmir, Michael; Huberman, Bernardo; Hogg, Tad

    1994-01-01

    We present a dynamical theory of asset price bubbles that exhibits the appearance of bubbles and their subsequent crashes. We show that when speculative trends dominate over fundamental beliefs, bubbles form, leading to the growth of asset prices away from their fundamental value. This growth makes the system increasingly susceptible to any exogenous shock, thus eventually precipitating a crash. We also present computer experiments which in their aggregate behavior confirm the predictions of the theory.

  7. Bubble-sweeping mechanisms

    Institute of Scientific and Technical Information of China (English)

    WANG; Hao; (王; 昊); PENG; Xiaofeng; (彭晓峰); WANG; Buxuan; (王补宣); LEE; Duzhong; (李笃中)

    2003-01-01

    A series of subcooled boiling experiments was conducted on very small platinum wires having diameters of 0.1 and 0.025 mm. Vapor bubbles were visually observed to sweep back and forth along the wires in the experiments. The dynamic characteristics of bubble-sweeping phenomenon are described, and the induced bubble interaction and nonlinear growth are investigated to understand the boiling heat transfer mechanisms. An unsymmetrical temperature model is proposed to explain the physical mechanism.

  8. Quasi-Y-source inverter

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has d...

  9. Inverting the Linear Algebra Classroom

    Science.gov (United States)

    Talbert, Robert

    2014-01-01

    The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…

  10. Control of Cascaded Multilevel Inverters

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Abstract-A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one DC voltage source. This new inverter can operateas a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-fre-quency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation resuits demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering). Index Terms-Cascaded inverter, multilevel inverter, three-level inverter.

  11. Numerical Studies On Bubble Pump With Alternate Working Fluids

    Directory of Open Access Journals (Sweden)

    L. Bruno Augustin

    2013-10-01

    Full Text Available The importance of energy conservation in the context of growing global population and dwindling fossil fuel resources cannot be overemphasized. Energy can be conserved by using it more efficiently. The energy spent for an application should be of the correct amount and type. It would make more sense to spend heat energy for heating rather than the high grade electricity as most of the electric power in the world is generated from driving heat engines, for which heat is supplied from the combustion of fossil fuels. At the same time, depletion of these conventional resources also poses a serious problem in meeting energy requirements. In this paper, the bubble pump, which is an integral part of diffusion- absorption refrigeration system, has been investigated numerically .A thermally driven bubble pump, which can be powered by solar thermal energy, is used to lift the liquid. The bubble pump runs on solar energy and reduces the amount of energy spent by replacing the compressor in conventional vapour absorption refrigeration system. As a result of the absence of any mechanical moving part, the refrigerator is silent and very reliable in addition to an economical and environmental friendly device. The concept of such a pump is already in existence but optimization studies are yet to be extensively investigated. This paper deals with the comparison of various parameters of the bubble pump using water and Nonane as the working fluid. Numerical simulation of the bubble pump is carried out using simple numerical equations which assume slug flow in the bubble pump. The mass flow rate, the sensible heating time and position of heating element are varied and the effect it has on diameter of the pipe, pumping ratio and the heat required is studied for both the working fluids

  12. Online Slug Detection in Multi-phase Transportation Pipelines Using Electrical Tomography

    DEFF Research Database (Denmark)

    Pedersen, Simon; Mai, Christian; Hansen, Leif

    2015-01-01

    Slugging flow in offshore oil & gas multi-phase transportation pipelines cause big challenges as the flow regime induces flow and pressure oscillations in the multi-phase pipelines. The negative impacts of the most severe slugs are significant and thus the elimination of slugging flow....... Based on the results the study concludes that the ERT is able to detect the slug very well when the oil and water is well mixed. Furthermore the traditional pressure transmitters have the limitation that pressure variations can be caused by other operating conditions than slug, such as change...... in the back pressure from control valves. The biggest limitation using ERT is the lack of ability to distinguish between gas and oil, and thus the ERT can only be used as an effective slug detect measurement when the oil-to-water ratio is low....

  13. Slug control in Australian canola: monitoring, molluscicidal baits and economic thresholds.

    Science.gov (United States)

    Nash, Michael A; Thomson, Linda J; Hoffmann, Ary A

    2007-09-01

    Exotic slugs have become serious pests of canola, at establishment, in Southern Australian high-rainfall cropping zones. Slugs were monitored using relatively inexpensive 300 mm x 300 mm terracotta tiles acting as refuges. An investigation was made of the effects of the time of application of chelated iron baits on the slug species Deroceras reticulatum Müller and Lehmannia nyctelia Bourguignat. Baits reduced the number of surface-active slug species. A single application at sowing provided greater efficacy than one application before sowing, and efficacy was comparable with that of two applications. Canola seedling densities showed a negative response to D. reticulatum numbers; the presence of even one individual per refuge trap reduced seedling numbers below optimum densities. Thistles and other vegetation were associated with increased numbers of slugs. European guidelines for slug monitoring and damage appear to be at least partly applicable to Australian conditions.

  14. Bubble and drop interfaces

    CERN Document Server

    Miller

    2011-01-01

    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  15. Physics of bubble oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Lauterborn, Werner; Kurz, Thomas [Third Physical Institute, University of Goettingen (Germany)

    2010-10-01

    Bubbles in liquids, soft and squeezy objects made of gas and vapour, yet so strong as to destroy any material and so mysterious as at times turning into tiny light bulbs, are the topic of the present report. Bubbles respond to pressure forces and reveal their full potential when periodically driven by sound waves. The basic equations for nonlinear bubble oscillation in sound fields are given, together with a survey of typical solutions. A bubble in a liquid can be considered as a representative example from nonlinear dynamical systems theory with its resonances, multiple attractors with their basins, bifurcations to chaos and not yet fully describable behaviour due to infinite complexity. Three stability conditions are treated for stable trapping of bubbles in standing sound fields: positional, spherical and diffusional stability. Chemical reactions may become important in that respect, when reacting gases fill the bubble, but the chemistry of bubbles is just touched upon and is beyond the scope of the present report. Bubble collapse, the runaway shrinking of a bubble, is presented in its current state of knowledge. Pressures and temperatures that are reached at this occasion are discussed, as well as the light emission in the form of short flashes. Aspherical bubble collapse, as for instance enforced by boundaries nearby, mitigates most of the phenomena encountered in spherical collapse, but introduces a new effect: jet formation, the self-piercing of a bubble with a high velocity liquid jet. Examples of this phenomenon are given from light induced bubbles. Two oscillating bubbles attract or repel each other, depending on their oscillations and their distance. Upon approaching, attraction may change to repulsion and vice versa. When being close, they also shoot self-piercing jets at each other. Systems of bubbles are treated as they appear after shock wave passage through a liquid and with their branched filaments that they attain in standing sound fields. The N-bubble

  16. Hydraulic Tomography and High-Resolution Slug Testing to Determine Hydraulic Conductivity Distributions - Year 1

    Science.gov (United States)

    2005-12-01

    the addition into a well of a known volume of water or a physical slug. More recently, pneumatic methods have become popular ( Zemansky and McElwee...and Zemansky , 2000), (Sellwood, 2001) and (Ross, 2004)]. The aquifer material at GEMS exhibits linear and non-linear responses to slug testing...1976; Zurbuchen et al., 2002; and Zemansky and McElwee, 2005). Slug tests have been a common method for obtaining information about the hydraulic

  17. Kinetics of gravity-driven slug flow in partially wettable capillaries of varying cross section

    Science.gov (United States)

    Nissan, Alon; Wang, Qiuling; Wallach, Rony

    2016-11-01

    A mathematical model for slug (finite liquid volume) motion in not-fully-wettable capillary tubes with sinusoidally varying cross-sectional areas was developed. The model, based on the Navier-Stokes equation, accounts for the full viscous terms due to nonuniform geometry, the inertial term, the slug's front and rear meniscus hysteresis effect, and dependence of contact angle on flow velocity (dynamic contact angle). The model includes a velocity-dependent film that is left behind the advancing slug, reducing its mass. The model was successfully verified experimentally by recording slug movement in uniform and sinusoidal capillary tubes with a gray-scale high-speed camera. Simulation showed that tube nonuniformity has a substantial effect on slug flow pattern: in a uniform tube it is monotonic and depends mainly on the slug's momentary mass/length; an undulating tube radius results in nonmonotonic flow characteristics. The static nonzero contact angle varies locally in nonuniform tubes owing to the additional effect of wall slope. Moreover, the nonuniform cross-sectional area induces slug acceleration, deceleration, blockage, and metastable-equilibrium locations. Increasing contact angle further amplifies the geometry effect on slug propagation. The developed model provides a modified means of emulating slug flow in differently wettable porous media for intermittent inlet water supply (e.g., raindrops on the soil surface).

  18. Stability of stratified flow and slugging in horizontal gas-liquid flow

    Institute of Scientific and Technical Information of China (English)

    GU Hanyang; GUO Liejin

    2005-01-01

    A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous KelvinHelmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted.

  19. A new index for precise design and advanced operation of mass transfer in slug flow

    OpenAIRE

    Aoki, Nobuaki; Tanigawa, Shin; Mae, Kazuhiro

    2011-01-01

    Slug flow, one of the ordered multi-phase flow patterns in a small channel, has the advantage of the enhancement of mixing in each phase and mass transfer between two phases due to the internal circulation flow. To form stable slug flow, the throughput of order of μL min−1 has been employed. To use slug flow in industrial scale, however, controlled and high throughput mass transfer and an index for design of a channel with slug flow are required. To address this requirement, we examined the i...

  20. Prospects for bubble fusion

    Energy Technology Data Exchange (ETDEWEB)

    Nigmatulin, R.I. [Tyumen Institute of Mechanics of Multiphase Systems (TIMMS), Marx (Russian Federation); Lahey, R.T. Jr. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1995-09-01

    In this paper a new method for the realization of fusion energy is presented. This method is based on the superhigh compression of a gas bubble (deuterium or deuterium/thritium) in heavy water or another liquid. The superhigh compression of a gas bubble in a liquid is achieved through forced non-linear, non-periodic resonance oscillations using moderate amplitudes of forcing pressure. The key feature of this new method is a coordination of the forced liquid pressure change with the change of bubble volume. The corresponding regime of the bubble oscillation has been called {open_quotes}basketball dribbling (BD) regime{close_quotes}. The analytical solution describing this process for spherically symmetric bubble oscillations, neglecting dissipation and compressibility of the liquid, has been obtained. This solution shown no limitation on the supercompression of the bubble and the corresponding maximum temperature. The various dissipation mechanisms, including viscous, conductive and radiation heat losses have been considered. It is shown that in spite of these losses it is possible to achieve very high gas bubble temperatures. This because the time duration of the gas bubble supercompression becomes very short when increasing the intensity of compression, thus limiting the energy losses. Significantly, the calculated maximum gas temperatures have shown that nuclear fusion may be possible. First estimations of the affect of liquid compressibility have been made to determine possible limitations on gas bubble compression. The next step will be to investigate the role of interfacial instability and breaking down of the bubble, shock wave phenomena around and in the bubble and mutual diffusion of the gas and the liquid.

  1. Inverted organic photovoltaic cells.

    Science.gov (United States)

    Wang, Kai; Liu, Chang; Meng, Tianyu; Yi, Chao; Gong, Xiong

    2016-05-21

    The advance in lifestyle, modern industrialization and future technological revolution are always at high expense of energy consumption. Unfortunately, there exist serious issues such as limited storage, high cost and toxic contamination in conventional fossil fuel energy sources. Instead, solar energy represents a renewable, economic and green alternative in the future energy market. Among the photovoltaic technologies, organic photovoltaics (OPVs) demonstrate a cheap, flexible, clean and easy-processing way to convert solar energy into electricity. However, OPVs with a conventional device structure are still far away from industrialization mainly because of their short lifetime and the energy-intensive deposition of top metal electrode. To address the stability and cost issue simultaneously, an inverted device structure has been introduced into OPVs, bridging laboratory research with practical application. In this review, recent progress in device structures, working mechanisms, functions and advances of each component layer as well their correlations with the efficiency and stability of inverted OPVs are reviewed and illustrated.

  2. Turbulence, bubbles and drops

    NARCIS (Netherlands)

    Veen, van der Roeland Cornelis Adriaan

    2016-01-01

    In this thesis, several questions related to drop impact and Taylor-Couette turbulence are answered. The deformation of a drop just before impact can cause a bubble to be entrapped. For many applications, such as inkjet printing, it is crucial to control the size of this entrapped bubble. To study t

  3. Bubbles in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Lin, Jun

    2015-01-01

    Strain-induced deformations in graphene are predicted to give rise to large pseudomagnetic fields. We examine theoretically the case of gas-inflated bubbles to determine whether signatures of such fields are present in the local density of states. Sharp-edged bubbles are found to induce Friedel...

  4. Evaporation, Boiling and Bubbles

    Science.gov (United States)

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  5. Evaporation, Boiling and Bubbles

    Science.gov (United States)

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  6. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light ten

  7. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light

  8. Bubble collision with gravitation

    CERN Document Server

    Hwang, Dong-il; Lee, Wonwoo; Yeom, Dong-han

    2012-01-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  9. The E-cadherin repressor slug and progression of human extrahepatic hilar cholangiocarcinoma

    Directory of Open Access Journals (Sweden)

    Wang Xin-sheng

    2010-07-01

    Full Text Available Abstract Objectives This study explored the expression and function of Slug in human extrahepatic hilar cholangiocarcinoma (EHC to identify its role in tumor progression. Methods The expression of Snail and Slug mRNA in 52 human tissue samples of EHC was investigated. The mRNA of Snail and Slug were quantified using reverse transcriptase-PCR, and correlations with E-cadherin expression and clinicopathological factors were investigated. We then investigated transfection of Slug cDNA in endogenous E-cadherin-positive human EHC FRH0201 cells, selectively induced the loss of E-cadherin protein expression, and then small interfering RNA (siRNA for inhibition of Slug expression in endogenous Slug-positive human EHC QBC939 cells, selectively induced the loss of Slug protein expression. A Boyden chamber transwell assay was used for invasion. Results Slug mRNA was overexpressed in 18 cases (34.6% of EHC compared with adjacent noncancerous tissue. E-Cadherin protein expression determined in the same 52 cases by immunohistochemistry was significantly down-regulated in those cases with Slug mRNA overexpression (P = 0.0001. The tumor and nontumor ratio of Slug mRNA was correlated with nodal metastasis(p = 0.0102, distant metastasis (p = 0.0001and Survival time(p = 0.0443. However, Snail mRNA correlated with neither E-cadherin expression nor tumor invasiveness. By inhibiting Slug expression by RNA interference, we found that reduced Slug levels upregulated E-cadherin and decreased invasion in QBC939 cell. When the QBC939 cells was infected with Slug cDNA,, significant E-cadherin was downregulated and increased invasion in QBC939 cell. Conclusions The results suggested that Slug expression plays an important role in both the regulation of E-cadherin expression and in the acquisition of invasive potential in human EHC. Slug is possibly a potential target for an antitumor therapy blocking the functions of invasion and metastasis in human EHCs.

  10. Seed consumption and dispersal of ant-dispersed plants by slugs.

    Science.gov (United States)

    Türke, Manfred; Heinze, Eric; Andreas, Kerstin; Svendsen, Sarah M; Gossner, Martin M; Weisser, Wolfgang W

    2010-07-01

    In beech-dominated forests in Central Europe, many spring geophytes show adaptations to seed dispersal by ants (myrmecochory). Ants, however, can be rare in such moist forests. Motivated by observations of slug feeding on seeds we investigated the seed consumption of two plant species, Anemone nemorosa and Asarum europaeum, by slugs, in a series of experiments. In a seed predation experiment in a beech forest, we found that seed removal was strongly reduced when gastropods were excluded from the seed depots. The contribution of insects, including ants, and rodents to seed removal was relatively less but differed between May and July. In the laboratory, slug species, in particular Arion sp., consumed seeds of both plant species. Slugs either consumed the elaiosomes of seeds or swallowed seeds intact. Swallowed seeds were defecated undamaged and germinated as well as control seeds when buried overwinter, indicating the potential for seed dispersal by slugs. We also recovered seeds of myrmecochores in the faeces of several slugs caught in forests. In a slug release experiment in the forest, slugs moved up to 14.6 m (mean 4.4 m) in 15 h, which is the median gut passage time of seeds based on measurements made in the laboratory. We also found that when slug-defecated seeds were offered to rodents, these were less attractive than control seeds, suggesting that passage through the slug gut reduces seed predation risk. Our results demonstrate that slugs are significant consumers of elaiosomes or entire seeds of ant-dispersed plants and that they can function as seed dispersers of these plants.

  11. Effect of bubble size on nanofiber diameter in bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Ren Zhong-Fu

    2016-01-01

    Full Text Available Polymer bubbles are widely used for fabrication of nanofibers. Bubble size affects not only bubble's surface tension, but also fiber's morphology. A mathematical model is established to reveal the effect of bubble size on the spinning process, and the experiment verification shows the theoretical analysis is reliable.

  12. A Study of Heat Transfer and Flow Characteristics of Rising Taylor Bubbles

    Science.gov (United States)

    Scammell, Alexander David

    2016-01-01

    Practical application of flow boiling to ground- and space-based thermal management systems hinges on the ability to predict the systems heat removal capabilities under expected operating conditions. Research in this field has shown that the heat transfer coefficient within two-phase heat exchangers can be largely dependent on the experienced flow regime. This finding has inspired an effort to develop mechanistic heat transfer models for each flow pattern which are likely to outperform traditional empirical correlations. As a contribution to the effort, this work aimed to identify the heat transfer mechanisms for the slug flow regime through analysis of individual Taylor bubbles.An experimental apparatus was developed to inject single vapor Taylor bubbles into co-currently flowing liquid HFE 7100. The heat transfer was measured as the bubble rose through a 6 mm inner diameter heated tube using an infrared thermography technique. High-speed flow visualization was obtained and the bubble film thickness measured in an adiabatic section. Experiments were conducted at various liquid mass fluxes (43-200 kgm2s) and gravity levels (0.01g-1.8g) to characterize the effect of bubble drift velocityon the heat transfer mechanisms. Variable gravity testing was conducted during a NASA parabolic flight campaign.Results from the experiments showed that the drift velocity strongly affects the hydrodynamics and heat transfer of single elongated bubbles. At low gravity levels, bubbles exhibited shapes characteristic of capillary flows and the heat transfer enhancement due to the bubble was dominated by conduction through the thin film. At moderate to high gravity, traditional Taylor bubbles provided small values of enhancement within the film, but large peaks in the wake heat transfer occurred due to turbulent vortices induced by the film plunging into the trailing liquid slug. Characteristics of the wake heat transfer profiles were analyzed and related to the predicted velocity field

  13. Tandonia kusceri (Pulmonata: Milacidae, a slug new for Slovakia

    Directory of Open Access Journals (Sweden)

    Ondřej Korábek

    2016-07-01

    Full Text Available Tandonia kusceri (Wagner, 1931 is reported from Slovakia for the first time. The slug was found in the Ružinov and Petržalka housing estates, Bratislava, in 2014 and 2015, respectively. Our observations suggest that the species is well established in the Slovak capital. This finding calls for verification of some of the older reports of a similar species Tandonia rustica beyond the eastern border of its native range. Owing to unresolved taxonomic issues, the name T. kusceri should be applied only tentatively.

  14. EFFECTS OF BAITS AND BAIT ALTERNATIVES ON SLUG MORTALITY, EGG PRODUCTION, AND SEEDLING SURVIVAL

    Science.gov (United States)

    Two non-bait slug control formulations that are not attractive to earthworms including Durham 3.5 and 7.5 (3.5 and 7.5%, metaldehyde, respectively) and SlugFest AWF (all-weather-formula, 25%, metaldehyde), a liquid spray product were investigated for their efficacy in reducing egg fecundity and slu...

  15. Long liquid slugs in stratified gas/liquid flow in horizontal and slightly inclined pipes

    NARCIS (Netherlands)

    Kadri, U.

    2009-01-01

    Long liquid slugs reaching several hundreds pipe diameter may appear when transporting gas and liquid in horizontal and near horizontal pipes. The long slugs cause system vibration and separation difficulties that may lead to operational failures. Identifying and predicting the time and length scale

  16. Long liquid slugs in stratified gas/liquid flow in horizontal and slightly inclined pipes

    NARCIS (Netherlands)

    Kadri, U.

    2009-01-01

    Long liquid slugs reaching several hundreds pipe diameter may appear when transporting gas and liquid in horizontal and near horizontal pipes. The long slugs cause system vibration and separation difficulties that may lead to operational failures. Identifying and predicting the time and length scale

  17. Transformation of a Water Slug in Free Fall Under the Conditions of Exposure to an Air Flow Orthogonal to the Direction of the Slug Motion

    Science.gov (United States)

    Volkov, R. S.; Zabelin, M. V.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-07-01

    An experimental study has been made of the influence of an orthogonal (side) air flow propagating with a velocity to 5 m/s on the phases of transformation of a water slug with an initial volume of 0.05-0.5 liter in free fall from a height of 3 m. Use was made of Phantom V411 and Phantom Miro M310 high-speed video cameras and a Tema Automotive software system with the function of continuous tracking. The laws of retardation of the phases of transformation of the water slug from the instant of formation to that of formation of a droplet cloud under the action of the air flow orthogonal to the direction of the slug motion, and also of the deceleration, removal, and destruction of the droplets and fragments of water separating from the slug surface, have been established.

  18. Delaying Modified QUICK Scheme and its Application in Slug Flow

    Institute of Scientific and Technical Information of China (English)

    LU Yuan-Wei; HE An-Ding; WANG Yue-She; ZHOU Fang-De

    2001-01-01

    Calculations of several classic questions in numerical heat transfer with delaying modified QUICKscheme show good agreement with benchmark. Combining volume of fluid model with the well known SIMPLEC method, the reasonable Taylor bubble shape has been obtained by using delaying modified QUICK scheme and donoracceptor scheme of inteffacial advection respectively. At the same time the stream field and the liquid film thickness around the Taylor bubble have been well figured out.

  19. Asymmetrical Γ-Source Inverters

    DEFF Research Database (Denmark)

    Wei, Mo; Poh Chiang, Loh; Blaabjerg, Frede

    2014-01-01

    , inverters with coupled transformers have been introduced, but they usually lead to high turns ratio, and hence many winding turns, at high gain. An alternative would then be the asymmetrical Γ-source inverters proposed in this paper, whose gain is raised by lowering their turns ratio toward unity. The input...... current drawn by the proposed inverters is smoother and, hence, more adaptable by the source. Theories and experimental results have been presented in this paper for validating the concepts proposed....

  20. Gas cooled traction drive inverter

    Science.gov (United States)

    Chinthavali, Madhu Sudhan

    2013-10-08

    The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.

  1. Gas cooled traction drive inverter

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, Madhu Sudhan

    2016-04-19

    The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.

  2. Noise and Directionality in a SLUG Microwave Amplifier for Superconducting Qubit Readout

    Science.gov (United States)

    Thorbeck, Ted; Zhu, Shaojiang; Leonard, Edward; McDermott, Robert

    2015-03-01

    Josephson parametric amplifiers have been widely used for low-noise dispersive readout of superconducting qubits. However, multiple stages of cryogenic isolation are required to protect the qubit from the strong microwave pump tone and from the high temperature noise of downstream gain stages. We want to remove circulators and isolators from the measurement chain because they are bulky, expensive, and magnetic. The SLUG (superconducting low-inductance undulatory galvanometer) is a microwave amplifier that achieves broad bandwidth, low added noise, and high gain. In this talk we discuss measurements of the SLUG added noise (less than photon system added noise). We describe theoretical and experimental investigations of the SLUG reverse isolation. Finally, we discuss backaction of the SLUG on the measured qubit, and we present strategies for the suppression of SLUG backaction.

  3. Fabrication of rare-earth bearing fuel slug by injection casting method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Hwan; Song, Hoon; Kim, Hyung Tae; Kim, Ki Hwan; Lee, Chan Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Herein, U.10wt%Zr fuel slugs containing 0, 3, and 7 wt%RE were prepared by an injection casting method and their characteristics were evaluated. The as-cast fuel slugs were generally sound and fabricated to the full length of the mold. However, the increased amount of the charged RE noticeably deteriorated the quality of the casting components such as melting crucible. Chemical analysis of the U.10Zr and U.10Zr.3RE slugs showed that the target composition was matched to within 1.0 wt%. In contrast, the composition of the U.10Zr.7RE fuel slug differed by as much as 4.6 wt% from the target. Therefore, more protective casting variables should be considered, when casting high RE-bearing fuel slugs. KAERI seeks to develop and demonstrate the technologies needed to transmute the long-lived transuranic actinide isotopes in spent nuclear fuel into shorter-lived fission products.

  4. Relationships Between Aphids (Insecta: Homoptera: Aphididae) and Slugs (Gastropoda: Stylommatophora: Agriolimacidae) Pests of Legumes (Fabaceae: Lupinus).

    Science.gov (United States)

    Kozłowski, Jan; Strażyński, Przemysław; Jaskulska, Monika; Kozłowska, Maria

    2016-01-01

    Lupin plants are frequently damaged by various herbivorous invertebrates. Significant among these are slugs and aphids, which sometimes attack the same plants. Relationships between aphids, slugs and food plant are very interesting. Grazing by these pests on young plants can lead to significant yield losses. There is evidence that the alkaloids present in some lupin plants may reduce grazing by slugs, aphids and other invertebrates. In laboratory study was analyzed the relationships between aphid Aphis craccivora and slug Deroceras reticulatum pests of legumes Lupinus angustifolius. It was found that the presence of aphids significantly reduced slug grazing on the plants. The lupin cultivars with high alkaloid content were found to be less heavily damaged by D. reticulatum, and the development of A. craccivora was found to be inhibited on such plants.

  5. Embedded EZ-Source Inverters

    DEFF Research Database (Denmark)

    Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede

    2010-01-01

    of embedded EZ-source inverters that can produce the same gain as the Z-source inverters but with smoother and smaller current/voltage maintained across the dc input source and within the impedance network. These latter features are attained without using any additional passive filter, which surely...... is a favorable advantage, since an added filter will raise the system cost and, at times, can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage- and current-type inverters with each of them tested...

  6. Embedded EZ-Source Inverters

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Gao, F.

    2008-01-01

    -voltage oscillations to the system. Therefore, Z-source inverters are in effect safer and less complex, and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family of embedded EZ...... since an added filter will raise the system cost, and at times can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage and current-type inverters with each of them tested experimentally using a number...

  7. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.

  8. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.

  9. An Experimental Study of the Flowrate Transients in Slug Flow

    Institute of Scientific and Technical Information of China (English)

    HELimin; CHENZhenyu; 等

    2002-01-01

    An investigation of the characteristics of flowrate transients within slug flow was conducted in a largescale outdoor testing facility.The test section consisted of a 378m long,7.62cm diameter stainless steel pipe. Air and water were used as the test fluids.The response to a change of flowrate o either phase or two phases was measured using a series of pressure transducers and differential pressure transducers.An increase or decrease in gas flowrate caused a pressure overshoot above the value at new steady state or led to a pressure undershoot to form a temporary stratified flow.Pressure waves existed in the pipeline,spreading from the entrance to the exit.The magnitude of pressure overshoot in “up-gas”transient or of pressure undershoot and period of the temporary stratified flow in “Down-gas” transient are related to the change of gas flowrate and the distance away from the entrance.In contrast,the change in liquid flowrate was accommodated by smooth transitions between the corresponding steady states,and only one obvious change was found in the slug frequency.According to experimental results,the pressure overshoot,pressure undershoot and the pressure wave propagation were analyzed,and the phenomena were explained reasonably.Some correlations for the calculation of the pressure overshoot and undershoot were proposed.

  10. Chemistry in Soap Bubbles.

    Science.gov (United States)

    Lee, Albert W. M.; Wong, A.; Lee, H. W.; Lee, H. Y.; Zhou, Ning-Huai

    2002-01-01

    Describes a laboratory experiment in which common chemical gases are trapped inside soap bubbles. Examines the physical and chemical properties of the gases such as relative density and combustion. (Author/MM)

  11. Chemistry in Soap Bubbles.

    Science.gov (United States)

    Lee, Albert W. M.; Wong, A.; Lee, H. W.; Lee, H. Y.; Zhou, Ning-Huai

    2002-01-01

    Describes a laboratory experiment in which common chemical gases are trapped inside soap bubbles. Examines the physical and chemical properties of the gases such as relative density and combustion. (Author/MM)

  12. Popping the Bubble

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Government adopts regulations to control real estate prices A mid concerns surrounding the presence of housing bubbles across China,the Chinese Government is taking action to secure and stabilize the real

  13. Bubble chamber: antiproton annihilation

    CERN Multimedia

    1971-01-01

    These images show real particle tracks from the annihilation of an antiproton in the 80 cm Saclay liquid hydrogen bubble chamber. A negative kaon and a neutral kaon are produced in this process, as well as a positive pion. The invention of bubble chambers in 1952 revolutionized the field of particle physics, allowing real tracks left by particles to be seen and photographed by expanding liquid that had been heated to boiling point.

  14. Bubbling Out of Control

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Jim Chanos,founder of the U.S. hedge fund Kynikos Associates,characterized the prop-erty bubble in China as "Dubai times 1,000-or worse." Many Chinese economists agree. Yi Xianrong,a senior researcher at the Institute of Finance and Banking under the Chinese Academy of Social Sciences,said the property bubble in China was far worse than the Dubai crisis in an interview with the Beijing-based International Herald Leader. Edited excerpts follow:

  15. Wall-liquid mass transfer for Taylor bubbles rising through liquid in a vertical tube%垂直管内弹状气泡上升时的壁面传质

    Institute of Scientific and Technical Information of China (English)

    贠军贤; 沈自求; 明平文

    2002-01-01

    Wall-liquid mass transfer for Taylor bubbles rising through liquid column in vertical tubes is an important and fundamental topic in industrial processes. In this work, the characteristics of wall-liquid mass transfer for this special case of slug flow were studied experimentally by limiting diffusion current technique (LDCT). Based on the experimental results and the analysis of hydrodynamic mechanisms, it was proposed that four different zones exist, i.e. the laminar falling film zone, the turbulent falling film zone, the wake region and the remaining liquid slug zone. The corresponding correlations for all these zones were developed.

  16. Advances in PV Inverters

    DEFF Research Database (Denmark)

    Anthon, Alexander

    their trade-offs. The contributions are:  • Comprehensive loss analysis and identification of major loss contributors within T-Type converter topology operating in inverter and rectifier context.  • Evaluation of the use and loss benefits of Silicon Carbide switching devices in the T-Type structure...... and new approaches are necessary. Therefore, research areas typically focus on both new topologies and utilizing more advanced semiconductor devices. To this end, semiconductor devices made of Silicon Carbide have been gaining increasing interest in the last two decades after the successful...... commercialization of high voltage power diodes. By now, the performance potential of switching devices made of Silicon Carbide is commonly accepted, though they have not found commonplace usage within commercial converter systems for several reasons, among others reliability, availability/cost and gate driver...

  17. Simulation of inverter dominated minigrids

    Energy Technology Data Exchange (ETDEWEB)

    Engler, A.; Osika, O. [Inst. fuer Solare Energieversorgungstechnik (ISET) e.V., Kassel (Germany)

    2003-07-01

    In order to assess the load flow, the transient behaviour and the stability of inverter dominated minigrids, a model for inverters and a transmission system has been developed. The inverters are represented by a frequency and voltage controlled three phase voltage source and the transmission systems consists of switches, overhead lines ({pi}-equivalent), transformers and a load. The inverters operate in parallel via the MV-distribution system and supply an active load. The contribution of each inverter is determined by the setting of the applied droops (similar to conventional power plants). Furthermore an approach for stability assessment of such systems is introduced. This research work is related to the EC-funded project MicroGrids. (orig.)

  18. Production of a high-velocity water slug using an impacting technique

    Science.gov (United States)

    Dehkhoda, S.; Bourne, N. K.

    2014-02-01

    A pulsed water jet consists of a series of discrete water slugs travelling at high velocity. Immediately after striking a target, these slugs apply high-intensity, short-duration transient stress pulses reaching an amplitude known as the water hammer pressure, followed by low-intensity, long-duration stationary stress at a lower stagnation pressure. The magnitude and duration of the water hammer and stagnation pressures are controlled by the size and quality of the water slugs. The use of water jets for rock cutting in mining operations is a centuries-old technology; however, practical methods for producing high-energy water slugs repeatedly have proven difficult. This can be partly due to the fact that the geometrical properties of a jet and so its effectiveness in creating damage is controlled and influenced by the method that is employed to generate the water slugs. This paper investigates the quality of a single water slug produced using an impacting technique where a hammer strikes a piston, resting on top of a water-filled chamber. The coherence and integrity of the jet core was of concern in this study. The impact impulse of the formed water jet was measured in a Kel-F target material using an embedded PVDF (Polyvinylidene fluoride) shock gauge. The recorded stress waveform was then used to determine the unity and endurance of the water slug stream once travelled through air.

  19. A Hydrodynamic Model for Slug Frequency in Horizontal Gas-Liquid Two-Phase Flow

    Institute of Scientific and Technical Information of China (English)

    刘磊; 孙贺东; 胡志华; 周芳德

    2003-01-01

    The prediction of slug frequency has important significance on gas-liquid two-phase flow. A hydrodynamic model was put forward to evaluate slug frequency for horizontal two-phase flow, based on the dependence of slug frequency on the frequency of unstable interfacial wave. Using air and water, experimental verification of the model was carried out in a large range of flow parameters. Six electrical probes were installed at different positions of a horizontal plexiglass pipe to detect slug frequency development. The pipe is 30 m long and its inner diameter is 24 ram. It is observed experimentally that the interracial wave frequency at the inlet is about i to 3 times the frequency of stable slug. The slug frequencies predicted by the model fit well with Tronconi (1990) model and the experimental data. The combination of the hydrodynamic model and the experimental data results in a conclusion that the frequency of equilibrium liquid slug is approximately half the minimum frequency of interfacial wave.

  20. Mathematical modelling of Liquid -Liquid extraction in the slug flow regime in a microchannel

    Science.gov (United States)

    Ramji, Sundari; Bhagavatula, Dinesh; Rakesh, Arjun; Pushpavanam, S.

    2016-11-01

    Mixing in the slug flow regime in microchannels is enhanced by the presence of internal circulations induced by shear due to wall. This helps improve mass transfer in this flow regime. We exploit the low Re characteristic of the flow and seek a numerical solution to understand the structure of the vortex patterns formed in the two phases in the slug flow regime. We study liquid-liquid extraction in the system to determine the improvement in mass transfer. The system was analyzed for two cases when there is (i) no film surrounding the slug (ii) a thin film surrounding the slug. The 2D governing equations for fluid flow are solved using two approaches: a) a stream function formulation based on finite differences b) primitive variable formulation with the Chebyshev collocation method. The effect of viscosity ratio, slug length and film thickness on the vortex structure were studied. While secondary vortices were induced in the less viscous phase in the case where the thin film is absent, they are always generated in the slug irrespective of the viscosity ratio in the case where the film is present. The species balance equation was then solved numerically using two approaches: a) an Alternating Direction Explicit method and b) the Locally One Dimensional splitting technique. The effect of varying Peclet number from 0 to 104 on the solute transfer from the slug to the continuous phase was studied. The extraction performance is analyzed in terms of extraction efficiency and mass transfer coefficient.

  1. Droplet and slug formation in polymer electrolyte membrane fuel cell flow channels: The role of interfacial forces

    Science.gov (United States)

    Colosqui, Carlos E.; Cheah, May J.; Kevrekidis, Ioannis G.; Benziger, Jay B.

    A microfluidic device is employed to emulate water droplet emergence from a porous electrode and slug formation in the gas flow channel of a PEM fuel cell. Liquid water emerges from a 50 μm pore forming a droplet; the droplet grows to span the entire cross-section of a microchannel and transitions into a slug which detaches and is swept downstream. Droplet growth, slug formation, detachment, and motion are analyzed using high-speed video images and pressure-time traces. Slug volume is controlled primarily by channel geometry, interfacial forces, and gravity. As water slugs move downstream, they leave residual micro-droplets that act as nucleation sites for the next droplet-to-slug transition. Residual liquid in the form of micro-droplets results in a significant decrease in slug volume between the very first slug formed in an initially dry channel and the ultimate "steady-state" slug. A physics-based model is presented to predict slug volumes and pressure drops for slug detachment and motion.

  2. Spatiotemporal analysis of predation by carabid beetles (Carabidae on nematode infected and uninfected slugs in the field.

    Directory of Open Access Journals (Sweden)

    Bjørn Arild Hatteland

    Full Text Available The dynamics of predation on parasites within prey has received relatively little attention despite the profound effects this is likely to have on both prey and parasite numbers and hence on biological control programmes where parasites are employed. The nematode Phasmarhabditis hermaphrodita is a commercially available biological agent against slugs. Predation on these slugs may, at the same time, result in intraguild predation on slug-parasitic nematodes. This study describes, for the first time, predation by carabid beetles on slugs and their nematode parasites on both spatial and temporal scales, using PCR-based methods. The highest nematode infection levels were found in the slugs Deroceras reticulatum and Arion silvaticus. Numbers of infected slugs decreased over time and no infected slugs were found four months after nematode application. The density of the most abundant slug, the invasive Arion vulgaris, was positively related to the activity-density of the carabid beetle, Carabus nemoralis. Predation on slugs was density and size related, with highest predation levels also on A. vulgaris. Predation on A. vulgaris decreased significantly in summer when these slugs were larger than one gram. Predation by C. nemoralis on slugs was opportunistic, without any preferences for specific species. Intraguild predation on the nematodes was low, suggesting that carabid beetles such as C. nemoralis probably do not have a significant impact on the success of biological control using P. hermaphrodita.

  3. Snails and slugs damaging the cut foliage, Cordyline fruticosa and use of biorationals towards their management.

    Science.gov (United States)

    Karthiga, S; Jegathambigai, V; Karunarathne, M D S D; Svinningen, A; Mikunthan, G

    2012-01-01

    Snails and slugs became a serious molluscan pests and damaging leaves of purple compacta, Cordyline fruticosa extensively grown for export at Green Farm Ltd, Sri Lanka. The export quality of leaves of C. fruticosa is lowered due to feeding of snails, Achantina fulica (Bowditch), Opeas pyrgula Schmacker and Boettgerx and Helix aspersa Muller and slugs incurring great loss to cut foliage industry. Paucity of information is available to understand snails and slugs damage and their host range that limits to develop suitable management practices. Therefore this study was aimed to determine damage, alternate hosts and to develop possible management practices. Snails and slugs damaged mainly fresh leaves of C. fruticosa. The severity of damage was 44.5% in infested field based on the visual rating method. Leaves of cassava, sting bean, okra, cucumber, passion fruit, papaya, Glyricidia and shoe flower were identified as alternate hosts and neem, Ixora and Dracaena spp were not served as alternate hosts. Among the plant materials tested for their repellence against snails and slugs revealed that neem seed powder was an irritant; neem leaves, mint leaves and Lantana leaves were acted as anti-feedant and Salt as chemical repellent. Among the barrier and bait experiments Bordeaux mixture exhibited a significant barrier effect against horizontal movement of snails. Baits made out of Metaldehyde bait, vegetables bait and jaggery had a strong effect in repelling the snails and slugs. Mulching with Madhuca longifolia punnac was the best to reduce the snails and slugs population compared to M. longifolia seed kernel powder. Oil from M. longifolia failed to reduce their population. Hence the results revealed that saponin containing M. longifolia punnac helped to eliminate snails and slugs when used as mulch. Metaldehyde, vegetable and jaggery baits are also useful to minimize their colonization further. Hence combination of these methods will help to prevent snails and slugs from

  4. Colliding with a crunching bubble

    Energy Technology Data Exchange (ETDEWEB)

    Freivogel, Ben; Freivogel, Ben; Horowitz, Gary T.; Shenker, Stephen

    2007-03-26

    In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda< 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.

  5. Investigation of bubble-bubble interaction effect during the collapse of multi-bubble system

    Science.gov (United States)

    Shao, Xueming; Zhang, Lingxin; Wang, Wenfeng

    2014-11-01

    Bubble collapse is not only an important subject among bubble dynamics, but also a key consequence of cavitation. It has been demonstrated that the structural damage is associated with the rapid change in flow fields during bubble collapse. How to model and simulate the behavior of the bubble collapse is now of great interest. In the present study, both theoretical analysis and a direct numerical simulation on the basis of VOF are performed to investigate the collapses of single bubble and bubble cluster. The effect of bubble-bubble interaction on the collapse of multi-bubble system is presented. The work was supported by the National Natural Science Foundation of China (11272284, 11332009).

  6. MEASUREMENT OF BUBBLE-BUBBLE INTERACTION DEPENDED ON REYNOLDS NUMBER USING STEREOSCOPIC BUBBLE-TRACKING TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    QU Jian-wu; MURAI Yuichi; YAMAMOTO Fujio

    2005-01-01

    Bubble-bubble interaction in free rising bubbly flows is experimentally investigated in the present study.The velocity vectors of the bubbles are measured by a stereoscopic bubble-tracking technique and then the relative velocity vectors of two nearest-neighbor bubbles are calculated with high statistical reliability.With the measurement data at Reynolds number ranging from 5 to 75, the vertical attraction and the horizontal repulsion are confirmed for Re<10 as known by the past study based on Navier-Stokes simulation.The new finding of the present measurement is that the bubbles of Re>30 have repulsive velocity bothin the horizontal and the vertical directions as those rise closely.Moreover, the three-dimensional structure of the bubble-bubble interaction is discussed with the data analysis of the interaction vector fields.

  7. Fermi Bubbles with HAWC

    CERN Document Server

    Solares, H A Ayala; Hüntemeyer, P

    2015-01-01

    The Fermi Bubbles, which comprise two large and homogeneous regions of spectrally hard gamma-ray emission extending up to $55^{o}$ above and below the Galactic Center, were first noticed in GeV gamma-ray data from the Fermi Telescope in 2010. The mechanism or mechanisms which produce the observed hard spectrum are not understood. Although both hadronic and lep- tonic models can describe the spectrum of the bubbles, the leptonic model can also explain similar structures observed in microwave data from the WMAP and Planck satellites. Recent publications show that the spectrum of the Fermi Bubbles is well described by a power law with an exponential cutoff in the energy range of 100MeV to 500GeV. Observing the Fermi Bubbles at higher gamma-ray energies will help constrain the origin of the bubbles. A steeper cutoff will favor a leptonic model. The High Altitude Water Cherenkov (HAWC) Observatory, located 4100m above sea level in Mexico, is designed to measure high-energy gamma rays between 100GeV to 100TeV. With...

  8. Experimental Study of Stable Surfaces for Anti-Slug Control in Multi-phase Flow

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2014-01-01

    The severe slugging flow is always challenging in oil & gas production, especially for the current offshore based production. The slugging flow can cause a lot of potential problems, such as those relevant to production safety, fatigue as well as capability. As one typical phenomenon in multi......-phase flow dynamics, the slug can be avoided or eliminated by proper facility design and control of operational conditions. Based on a testing facility which can emulate a pipeline-riser or a gas-lifted production well in a scaled-down manner, this paper experimentally studies the correlations of key...

  9. Transformerless PV inverters. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Borup, U.

    2009-12-15

    Since the start of the project the market for grid connected PV inverters have developed further. When the project started three - phase inverter were only available in high power systems. The technology developed within this project will enable three phase technology also to be implemented in string inverters for system down to 10 kW. We expect this to be very attractive due to the increased demand for symmetrical feed-in to the grid. The project relevance is therefore high and the sector continues to develop very much driven by technology. Especially the inverter technology is getting a lot of focus. The inverter systems are expected to take a much larger role in supporting the electrical grid in the future. The technology platform developed within the project is prepared to be extended with these utility functionalities. The main results of the project were: 1) A new technology concept for transformer-less inverters has been demonstrated with a number of prototypes. 2) Efficiency above 97,7% has been proven. 3) Efficiency and Maximum power point tracking has been optimized to ensure that almost all energy produced of the panels is transferred to the grid. 4) The platform is developed with a very fast control board, which enables extended functionality as demanding grid supporting functions in the future. Details about cost price and details about the control loop implementation is excluded from the report due to the competitive situation for Danfoss Solar Inverters A/S. (LN)

  10. Modulation of Current Source Inverter

    Directory of Open Access Journals (Sweden)

    Golam Reza Arab Markadeh

    2011-04-01

    Full Text Available Direct torque control with Current Source Inverter (CSI instead of voltage source inverter is so appropriate because of determining the torque of induction motor with machine current and air gap flux. In addition, Space-Vector Modulation (SVM is a more proper method for CSI because of low order harmonics reduction, lower switching frequency and easier implementation. This paper introduces the SVM method for CSI and uses the proposed inverter for vector control of an induction motor. The simulation results illustrate fast dynamic response and desirable torque and speed output. Fast and accurate response to changes of speed and load torque reference completely proves the prominence of this method.

  11. Bubble nuclei; Noyaux Bulles

    Energy Technology Data Exchange (ETDEWEB)

    Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1998-07-22

    For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.

  12. Bubble nuclei; Noyaux Bulles

    Energy Technology Data Exchange (ETDEWEB)

    Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1998-07-22

    For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.

  13. Experimantal Study on the Bubble Clustering in Bubbly Flows

    Science.gov (United States)

    Takagi, Shu; Fujiwara, Akiko; Ogasawara, Toshiyuki; Matsumoto, Yoichiro

    2003-11-01

    The statistical properties of bubbly flows and the near-wall bubble-clustering behaviors are investigated for upward flow in a rectangular channel. Bubble size, turbulent properties of liquid phase and the bubble clustering motion were measured using image-processing technique, Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV), respectively. Using 3-pentanol as a surfactant, the mono-dispersed 1mm-bubbles are generated. The mono-dispersed bubbles in upward flows accumulate near the wall and construct bubble clusters. These bubble clusters were investigated. Experimental observation showed that the size of bubble cluster can be much larger than that of the coherent structure in single phase turbulence. The clusters change their shape in time and space and these bubble motions accelerate the mean streamwise velocity near the wall due to the buoyancy effect. Thus the mean velocity profile of the liquid phase becomes flattened. It is suggested that the highly accumulated bubbles in the vicinity of the wall disturb the transport of turbulence energy produced in the wall shear layer from the central region of the channel flow. Furthermore, in the middle of channel, the fluctuations of the liquid phase are mainly generated by the bubble motions.

  14. Multivariate bubbles and antibubbles

    Science.gov (United States)

    Fry, John

    2014-08-01

    In this paper we develop models for multivariate financial bubbles and antibubbles based on statistical physics. In particular, we extend a rich set of univariate models to higher dimensions. Changes in market regime can be explicitly shown to represent a phase transition from random to deterministic behaviour in prices. Moreover, our multivariate models are able to capture some of the contagious effects that occur during such episodes. We are able to show that declining lending quality helped fuel a bubble in the US stock market prior to 2008. Further, our approach offers interesting insights into the spatial development of UK house prices.

  15. Fermi Bubbles with HAWC

    OpenAIRE

    Solares, H. A. Ayala; Hui, C. M.; Hüntemeyer, P.; collaboration, for the HAWC

    2015-01-01

    The Fermi Bubbles, which comprise two large and homogeneous regions of spectrally hard gamma-ray emission extending up to $55^{o}$ above and below the Galactic Center, were first noticed in GeV gamma-ray data from the Fermi Telescope in 2010. The mechanism or mechanisms which produce the observed hard spectrum are not understood. Although both hadronic and lep- tonic models can describe the spectrum of the bubbles, the leptonic model can also explain similar structures observed in microwave d...

  16. Resurrection of An Inverted Pendulum

    CERN Document Server

    Kim, S Y; Kim, Sang-Yoon; Hu, Bambi

    1998-01-01

    We study the bifurcations associated with stability of the inverted (stationary) state in the parametrically forced pendulum by varying the driving amplitude $\\epsilon$ and frequency $\\omega$. We first note that the inverted state is unstable for $\\epsilon=0$. However, as $\\epsilon$ is increased, the inverted state exhibits a cascade of ``resurrections,'' i.e., it becomes stabilized after its instability, destabilize again, and so forth ad infinitum for any given $\\omega$. Its stabilizations (destabilizations) occur via alternating subcritical (supercritical) pitchfork and period-doubling bifurcations. An infinite sequence of period-doubling bifurcations, leading to chaos, also follows each destabilization of the inverted state. The critical behaviors in the period-doubling cascades are also discussed.

  17. SLUG: Critical regulator of epithelial cell identity in breast development and cancer.

    Science.gov (United States)

    Phillips, Sarah; Kuperwasser, Charlotte

    2014-01-01

    SLUG, a member of the SNAIL family of transcriptional repressors, is known to play a diverse number of roles in the cell, and its deregulation has been observed in a variety of cancers including breast. Here, we focus on SLUG's role as a master regulator of mammary epithelial cell (MEC) fate and lineage commitment in the normal mammary gland, and discuss how aberrant SLUG expression can influence breast tumor formation, phenotype, and progression. Specifically, we discuss SLUG's involvement in MEC differentiation, stemness, cellular plasticity, and the epithelial to mesenchymal transition (EMT), and highlight the complex connection between these programs during development and disease progression. Undoubtedly, delineating how molecular factors influence lineage identity and cell-state dynamics in the normal mammary gland will contribute to our understanding of breast tumor heterogeneity.

  18. Experimental Study of Stable Surfaces for Anti-Slug Control in Multi-phase Flow

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Stampe, Kasper;

    2016-01-01

    Severe slugging flow is always challenging in oil & gas production, especially for the current offshore based production. The slugging flow can cause a lot of problems, such as those relevant to production safety, fatigue as well as capability. As one typical phenomenon in multi-phase flow dynamics......, the slug can be avoided or eliminated by proper facility design or control of operational conditions. Based on a testing facility which can emulate a pipeline-riser or a gas-lifted production well in a scaled-down manner, this paper experimentally studies the correlations of key operational parameters...... that the capability, performance and efficiency of anti-slug control can be dramatically improved if these stable surfaces can be experimentally determined beforehand. The paper concludes that obtaining the stable surface on the new developed map can significantly improve the production rate in a control scheme. Even...

  19. SLUG Microwave Amplifier as a Nonreciprocal Gain Element for Scalable Qubit Readout

    Science.gov (United States)

    Thorbeck, Ted; Leonard, Edward; Zhu, Shaojiang; McDermott, Robert

    Josephson parametric amplifiers for superconducting qubits require several stages of cryogenic isolation to protect the qubit from strong microwave pump tones and downstream noise. But isolators and circulators are large, expensive and magnetic, so they are an obstacle to scaling up a superconducting quantum computer. In contrast, the SLUG (Superconducting Low-inductance Undulatory Galvanometer) is a high gain, broadband, low noise microwave amplifier that provides built-in reverse isolation. Here, we describe the dependence of the SLUG reverse isolation on signal frequency and device operating point. We show that the reverse isolation of the SLUG can be as large as or larger than that of a bulk commercial isolator. Finally, we discuss the use of the SLUG to read out a transmon qubit without isolators or circulators.

  20. Review of Slug Detection, Modeling and Control Techniques for Offshore Oil & Gas Production Processes

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2015-01-01

    The current offshore oil & gas multi-phase production and transportation installations have big challenges related with the slugging flow: An unstable multi-phase flow regime where the flow rates, pressures and temperatures oscillate in the considered processes. Slug can be caused by different...... of these methods can simultaneously reduce the oil & gas production, which is a very big concern as the production rate is the key evaluation parameter for offshore production. We conclude that the slugging flow is a well-defined phenomenon, even though this subject has been extensively investigated in the past...... operating conditions and installation structures. The most severe slugs are often induced in long vertical risers or production wells, where liquid blocks gas at the riser/well base and correspondingly it causes the pressure to accumulate and hence originates the oscillating performance. There are many...

  1. Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs

    DEFF Research Database (Denmark)

    Slotsbo, Stine; Hansen, Lars Monrad; Jordaens, Kurt;

    2012-01-01

    in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but freezing of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived freezing for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived freezing......Cold tolerance and metabolic responses to freezing of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to freezing conditions simulating likely winter temperatures....... Glucose increased from about 6 to 22 µg/mg dry tissue upon freezing in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other freeze tolerant invertebrates....

  2. The Early Years: Blowing Bubbles

    Science.gov (United States)

    Ashbrook, Peggy

    2016-01-01

    Blowing bubbles is not only a favorite summer activity for young children. Studying bubbles that are grouped together, or "foam," is fun for children and fascinating to many real-world scientists. Foam is widely used--from the bedroom (mattresses) to outer space (insulating panels on spacecraft). Bubble foam can provide children a…

  3. Inverter Ground Fault Overvoltage Testing

    Energy Technology Data Exchange (ETDEWEB)

    Hoke, Andy [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chebahtah, Justin [SolarCity Corporation, San Mateo, CA (United States); Wang, Trudie [SolarCity Corporation, San Mateo, CA (United States); McCarty, Michael [SolarCity Corporation, San Mateo, CA (United States)

    2015-08-12

    This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.

  4. Motion of liquid plugs between vapor bubbles in capillary tubes: a comparison between fluids

    Science.gov (United States)

    Bertossi, Rémi; Ayel, Vincent; Mehta, Balkrishna; Romestant, Cyril; Bertin, Yves; Khandekar, Sameer

    2017-04-01

    Pulsating heat pipes (PHP) are now well-known devices in which liquid/vapor slug flow oscillates in a capillary tube wound between hot and cold sources. In this context, this paper focuses on the motion of the liquid plug, trapped between vapor bubbles, moving in capillary tubes, to try to better understand the thermo-physical phenomena involved in such devices. This study is divided into three parts. In the first part, an experimental study presents the evolution of the vapor pressure during the evaporation process of a liquid thin film deposited from a liquid plug flowing in a heated capillary tube: it is found that the behavior of the generated and removed vapor can be very different, according to the thermophysical properties of the fluids. In the second part, a transient model allows to compare, in terms of pressure and duration, the motion of a constant-length liquid plug trapped between two bubbles subjected to a constant difference of vapor pressure: the results highlight that the performances of the four fluids are also very different. Finally, a third model that can be considered as an improvement of the second one, is also presented: here, the liquid slug is surrounded by two vapor bubbles, one subjected to evaporation, the pressure in both bubbles is now a result of the calculation. This model still allows comparing the behaviors of the fluid. Even if our models are quite far from a complete model of a real PHP, results do indicate towards the applicability of different fluids as suitable working fluids for PHPs, particularly in terms of the flow instabilities which they generate.

  5. Slug controls stem/progenitor cell growth dynamics during mammary gland morphogenesis.

    Directory of Open Access Journals (Sweden)

    Mayssa Nassour

    Full Text Available BACKGROUND: Morphogenesis results from the coordination of distinct cell signaling pathways controlling migration, differentiation, apoptosis, and proliferation, along stem/progenitor cell dynamics. To decipher this puzzle, we focused on epithelial-mesenchymal transition (EMT "master genes". EMT has emerged as a unifying concept, involving cell-cell adhesion, migration and apoptotic pathways. EMT also appears to mingle with stemness. However, very little is known on the physiological role and relevance of EMT master-genes. We addressed this question during mammary morphogenesis. Recently, a link between Slug/Snai2 and stemness has been described in mammary epithelial cells, but EMT master genes actual localization, role and targets during mammary gland morphogenesis are not known and we focused on this basic question. METHODOLOGY/PRINCIPAL FINDINGS: Using a Slug-lacZ transgenic model and immunolocalization, we located Slug in a distinct subpopulation covering about 10-20% basal cap and duct cells, mostly cycling cells, coexpressed with basal markers P-cadherin, CK5 and CD49f. During puberty, Slug-deficient mammary epithelium exhibited a delayed development after transplantation, contained less cycling cells, and overexpressed CK8/18, ER, GATA3 and BMI1 genes, linked to luminal lineage. Other EMT master genes were overexpressed, suggesting compensation mechanisms. Gain/loss-of-function in vitro experiments confirmed Slug control of mammary epithelial cell luminal differentiation and proliferation. In addition, they showed that Slug enhances specifically clonal mammosphere emergence and growth, cell motility, and represses apoptosis. Strikingly, Slug-deprived mammary epithelial cells lost their potential to generate secondary clonal mammospheres. CONCLUSIONS/SIGNIFICANCE: We conclude that Slug pathway controls the growth dynamics of a subpopulation of cycling progenitor basal cells during mammary morphogenesis. Overall, our data better define a

  6. INTERRELATION OF RHOMBICITY AND OCCURRENCE OF INTERNAL CRACKS AT CONTINUOUS CASTING OF SORTED SLUG

    Directory of Open Access Journals (Sweden)

    Ju. A. Samojlovich

    2008-01-01

    Full Text Available Analysis of deformations and stresses in cross section of sorted uninterruptedly-casted slugs at their solidification and cooling within limits of crystallizer with the aim of determination of possibilities for occurrence of internal cracks of diagonal type is carried out on basis of mathematical modeling, the peculiarities of the slug skin cooling at its shrinkage and separation from crystallizer wall are revealed.

  7. Invertibility in L-Topological Spaces

    Directory of Open Access Journals (Sweden)

    Anjaly Jose

    2014-03-01

    Full Text Available In this paper, we extend the concept of invertibility to L-topological spaces and delineate its properties. Then, we study further completely invertible L-topological spaces and introduce two types of invertible L-topologies based on the inverting maps, studying their sums, subspaces and simple extensions.

  8. Understanding the bubbles

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    that are identified to exist between the Internet and housing market bubbles: uncertainty and sentiments. The iteration between uncertainty and sentiments leads to the emergence of the third commonality: residue. The residue is the difference between the actors’ overall sentiment about exaggerated future prospects...

  9. Heavy liquid bubble chamber

    CERN Multimedia

    1965-01-01

    The CERN Heavy liquid bubble chamber being installed in the north experimental hall at the PS. On the left, the 1180 litre body; in the centre the magnet, which can produce a field of 26 800 gauss; on the right the expansion mechanism.

  10. Microfluidic "blinking" bubble pump

    NARCIS (Netherlands)

    Yin, Zhizhong; Prosperetti, Andrea

    2005-01-01

    The paper reports data obtained on a simple micropump, suitable for electrolytes, based on the periodic growth and collapse of a single vapor bubble in a microchannel. With a channel diameter of the order of 100 µm, pumping rates of several tens of µl/min and pressure differences of several kPa are

  11. The Liberal Arts Bubble

    Science.gov (United States)

    Agresto, John

    2011-01-01

    The author expresses his doubt that the general higher education bubble will burst anytime soon. Although tuition, student housing, and book costs have all increased substantially, he believes it is still likely that the federal government will continue to pour billions into higher education, largely because Americans have been persuaded that it…

  12. Popping the Bubble

    Institute of Scientific and Technical Information of China (English)

    LAN XINZHEN

    2010-01-01

    @@ Amid concerns surrounding the presence of housing bubbles across China,the Chinese Government is taking action to secure and stabilize the real estate market.In the past month,the government launched a series of regulatory policies aimed at cooling the overheated market.

  13. BEBC bubble chamber

    CERN Multimedia

    1972-01-01

    Looking up into the interior of BEBC bubble chamber from the expansion cylinder. At the top of the chamber two fish-eye lenses are installed and three other fish-eye ports are blanked off. In the centre is a heat exchanger.

  14. Scanning bubble chamber pictures

    CERN Multimedia

    1974-01-01

    These were taken at the 2 m hydrogen bubble chamber. The photo shows an early Shiva system where the pre-measurements needed to qualify the event were done manually (cf photo 7408136X). The scanning tables were located in bld. 12. Gilberte Saulmier sits on foreground, Inge Arents at centre.

  15. RCP induces Slug expression and cancer cell invasion by stabilizing β1 integrin.

    Science.gov (United States)

    Hwang, M H; Cho, K H; Jeong, K J; Park, Y-Y; Kim, J M; Yu, S-L; Park, C G; Mills, G B; Lee, H Y

    2017-02-23

    Rab coupling protein (RCP)-induced tumor cell migration has been implicated in tumor pathophysiology and patient outcomes. In the present study, we demonstrate that RCP stabilizes β1 integrin leading to increased β1 integrin levels and activation of a signaling cascade culminating in Slug induction, epithelial-to-mesenchymal transition and increased invasion. Ectopic expression of RCP induced Slug expression. Silencing β1 integrin efficiently inhibited RCP-induced Slug expression and subsequent cancer cell invasion. Conversely, ectopic expression of β1 integrin was sufficient to induce Slug expression. Pharmacological inhibition of integrin linked kinase (ILK), EGFR and NF-κB, as well as transfection of a dominant-negative mutant of Ras (RasN17), significantly inhibited RCP-induced Slug expression and cancer cell invasion. Strikingly, ectopic expression of RCP was sufficient to enhance metastasis of ovarian cancer cells to the lung. Collectively, we demonstrate a mechanism by which RCP promotes cancer cell aggressiveness through sequential β1 integrin stabilization, activation of an ILK/EGFR/Ras/NF-κB signaling cascade and subsequent Slug expression.

  16. Epidermal secretions of terrestrial flatworms and slugs: Lehmannia valentiana mucus contains matrilin-like proteins.

    Science.gov (United States)

    Li, Dongmei; Graham, Lloyd D

    2007-11-01

    We describe the epidermal mucus of two types of terrestrial invertebrates: free-living flatworms (Tricladida: Terricola), and the slug Lehmannia valentiana (Gastropoda: Pulmonata). Both exhibited similar dry shear strengths (1.4-1.7 MPa). In denaturing gel electrophoresis, the protein fraction of flatworm mucus migrated mainly as a broad band (200-300 kDa). Slug mucus had a higher protein content than flatworm mucus but it contained more carbohydrate than protein, mainly as large heparan sulfate-like glycosaminoglycans. Proteins and glycosaminoglycans were both essential for the mechanical integrity of the slug hydrogel. The protein fraction of slug mucus contained approximately 12 larger proteins (30-300 kDa) and approximately 6 smaller ones (10-28 kDa). Complete cDNA clones were obtained for the slug mucus 40 kDa protein (Sm40; Genbank accession EF634345) and 85 kDa protein (Sm85; Genbank accession EF634346). Both proteins contain EGF-like repeats and von Willebrand A-domains, and therefore resemble vertebrate matrilins. Many of the larger slug mucus proteins appear to contain A-domains, and these may play a role in the unusual rheological properties of gastropod mucus.

  17. Integrity of high-velocity water slug generated by an impacting technique

    Science.gov (United States)

    Dehkhoda, Sevda; Bourne, Neil

    2013-06-01

    A pulsed water jet is a series of discrete water slugs travelling at high velocity. Immediately after striking a target, these slugs apply high-intensity, short-duration transient stress known as the water hammer pressure, followed by low-intensity, long-duration stationary stress at the stagnation pressure. The magnitude and duration of the water hammer and stagnation pressures are controlled by the size and quality of the water slugs. The use of water jets for rock cutting in mining operations is a centuries-old technology; however, practical methods for producing high-energy water slugs repeatedly have proven difficult. This can be partly due to the fact that the geometrical properties of a jet and so its effectiveness in creating damage is controlled and influenced by the method that is employed to generate the water slugs. This paper investigates the integrity of a single water slug produced using an impacting technique where a hammer strikes a piston, resting on top of a water-filled chamber. The coherence of the generated water pulse was of concern in this study. If repeated shock reflections within the chamber were transmitted or were carried into the internal geometry of nozzle, the emerging jet could pulsate. The impact impulse of the formed water jet was measured in a Kel-F target material using an embedded PVDF (Polyvinylidene fluoride) shock gauge. The recorded stress waveform was then used to study the quality and endurance of the water pulse stream as it travelled through air.

  18. Polymorphisms of the maternal Slug gene in fetal neural tube defects in a Chinese population

    Institute of Scientific and Technical Information of China (English)

    Li Guo; Hong Zhao; Yuheng Pei; Quanren He; Wan-I Li; Ting Zhang; Xiaoying Zheng; Ran Zhou; Jun Xie

    2010-01-01

    Several studies have demonstrated that Slug,which encodes a zinc finger of the Snail family of transcription factors,is a potential risk factor for neural tube defects.Neural tube defects tend to occur with a high rate in Shanxi province,China.The present case-control study investigated genotypic distributions and allele frequencies of Slug C1548A polymorphisms in DNA samples from59 women with a history of neural tube defect pregnancies and 73 controls during the same period from Shanxi Province,China.Results demonstrated that women with a history of neural tube defect pregnancies had significantly greater genotypic distributions of Slug AA genotypes and A allele frequencies compared with controls,and A allele Slug C1548A was a risk factor for neural tube defects(odds ratio = 3.444;95% confidence interval;2.021-5.868,P < 0.05).Three-dimensional structure prediction revealed that Slug C1548A resulted in transition of aspartic acid into glutamate at position 119.This indicated that these mutations could lead to damaged protein structure and function.These findings suggest that Slug C1548A gene polymorphism is closely related to neural tube defects in a population of Han Chinese origin from Shanxi Province,China

  19. Slug tests in wells screened across the water table: some additional considerations.

    Science.gov (United States)

    Butler, J J

    2014-01-01

    The majority of slug tests done at sites of shallow groundwater contamination are performed in wells screened across the water table and are affected by mechanisms beyond those considered in the standard slug-test models. These additional mechanisms give rise to a number of practical issues that are yet to be fully resolved; four of these are addressed here. The wells in which slug tests are performed were rarely installed for that purpose, so the well design can result in problematic (small signal to noise ratio) test data. The suitability of a particular well design should thus always be assessed prior to field testing. In slug tests of short duration, it can be difficult to identify which portion of the test represents filter-pack drainage and which represents formation response; application of a mass balance can help confirm that test phases have been correctly identified. A key parameter required for all slug test models is the casing radius. However, in this setting, the effective casing radius (borehole radius corrected for filter-pack porosity), not the nominal well radius, is required; this effective radius is best estimated directly from test data. Finally, although conventional slug-test models do not consider filter-pack drainage, these models will yield reasonable hydraulic conductivity estimates when applied to the formation-response phase of a test from an appropriately developed well.

  20. Distribution of void fraction for gas-liquid slug flow in an inclined pipe

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to investigate the effect of inclination angle on the spatial distribution of phases, experiments on gas-liquid two-phase slug flow in an inclined pipe were carried out by using the optical probe and an EKTAPRO 1000 high speed motion analyzer. It has been demonstrated that the inclination angle and the mixture velocity are important parameters to influence the distribution of void fraction for upward slug flow in the inclined pipe. At high mixture velocity, the gas phase profile is axial symmetry in the cross-section of the pipe. This is similar to that for vertical slug flow. In contrast, most of the gas phase is located near the upper pipe wall at low mixture velocity. By measuring the axial variation of void fraction along the liquid slug, it can be concluded that there is a high void fraction wake region with length of 3~4D in the front of liquid slug. In the fully developed zone of liquid slug, the peak value of the void fraction is near the upper wall.

  1. An NF-kappaB and slug regulatory loop active in early vertebrate mesoderm.

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    Full Text Available BACKGROUND: In both Drosophila and the mouse, the zinc finger transcription factor Snail is required for mesoderm formation; its vertebrate paralog Slug (Snai2 appears to be required for neural crest formation in the chick and the clawed frog Xenopus laevis. Both Slug and Snail act to induce epithelial to mesenchymal transition (EMT and to suppress apoptosis. METHODOLOGY & PRINCIPLE FINDINGS: Morpholino-based loss of function studies indicate that Slug is required for the normal expression of both mesodermal and neural crest markers in X. laevis. Both phenotypes are rescued by injection of RNA encoding the anti-apoptotic protein Bcl-xL; Bcl-xL's effects are dependent upon IkappaB kinase-mediated activation of the bipartite transcription factor NF-kappaB. NF-kappaB, in turn, directly up-regulates levels of Slug and Snail RNAs. Slug indirectly up-regulates levels of RNAs encoding the NF-kappaB subunit proteins RelA, Rel2, and Rel3, and directly down-regulates levels of the pro-apopotic Caspase-9 RNA. CONCLUSIONS/SIGNIFICANCE: These studies reveal a Slug/Snail-NF-kappaB regulatory circuit, analogous to that present in the early Drosophila embryo, active during mesodermal formation in Xenopus. This is a regulatory interaction of significance both in development and in the course of inflammatory and metastatic disease.

  2. Characteristics of bubble plumes, bubble-plume bubbles and waves from wind-steepened wave breaking

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G. de

    2007-01-01

    Observations of breaking waves, associated bubble plumes and bubble-plume size distributions were used to explore the coupled evolution of wave-breaking, wave properties and bubble-plume characteristics. Experiments were made in a large, freshwater, wind-wave channel with mechanical wind-steepened w

  3. Bubble properties of heterogeneous bubbly flows in a square bubble column: draft

    NARCIS (Netherlands)

    Bai, Wei; Deen, Niels G.; Kuipers, J.A.M.

    2009-01-01

    The present work focuses on the measurements of bubble properties in heterogeneous bubbly flows in a square bubble column. A four-point optical fibre probe was used for this purpose. The accuracy and intrusive effect of the optical probe was investigated first. The results show that the optical prob

  4. Bubble dynamics and bubble-induced turbulence of a single-bubble chain

    Science.gov (United States)

    Lee, Joohyoung; Park, Hyungmin

    2016-11-01

    In the present study, the bubble dynamics and liquid-phase turbulence induced by a chain of bubbles injected from a single nozzle have been experimentally investigated. Using a high-speed two-phase particle image velociemtry, measurements on the bubbles and liquid-phase velocity field are conducted in a transparent tank filled with water, while varying the bubble release frequency from 0.1 to 35 Hz. The tested bubble size ranges between 2.0-3.2 mm, and the corresponding bubble Reynolds number is 590-1100, indicating that it belongs to the regime of path instability. As the release frequency increases, it is found that the global shape of bubble dispersion can be classified into two regimes: from asymmetric (regular) to axisymmetric (irregular). In particular, at higher frequency, the wake vortices of leading bubbles cause an irregular behaviour of the following bubble. For the liquid phase, it is found that a specific trend on the bubble-induced turbulence appears in a strong relation to the above bubble dynamics. Considering this, we try to provide a theoretical model to estimate the liquid-phase turbulence induced by a chain of bubbles. Supported by a Grant funded by Samsung Electronics, Korea.

  5. Bubbles generated from wind-steepened breaking waves: 1. Bubble plume bubbles

    NARCIS (Netherlands)

    Leifer, I.; Leeuw, G. de

    2006-01-01

    Measurements of bubble plumes from paddle-amplified, wind stress breaking waves were made in a large wind-wave channel during the LUMINY experiment in fresh (but not clean) water. Bubble plumes exhibited considerable variability with respect to dynamics, bubble size distribution, and physical

  6. Bubble properties of heterogeneous bubbly flow in a square bubble column

    NARCIS (Netherlands)

    Bai, W.; Deen, N.G.; Kuipers, J.A.M.

    2010-01-01

    The present work focuses on the measurements of bubble properties in heterogeneous bubbly flows in a square bubble column. A four-point optical fibre probe was used for this purpose. The accuracy and intrusive effect of the optical probe was investigated first. The results show that the optical prob

  7. Bubbles generated from wind-steepened breaking waves: 1. Bubble plume bubbles

    NARCIS (Netherlands)

    Leifer, I.; Leeuw, G. de

    2006-01-01

    Measurements of bubble plumes from paddle-amplified, wind stress breaking waves were made in a large wind-wave channel during the LUMINY experiment in fresh (but not clean) water. Bubble plumes exhibited considerable variability with respect to dynamics, bubble size distribution, and physical extent

  8. Γ-source Neutral Point Clamped Inverter

    DEFF Research Database (Denmark)

    Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

    Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

  9. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  10. Photocontrol of fluid slugs in liquid crystal polymer microactuators

    Science.gov (United States)

    Lv, Jiu-An; Liu, Yuyun; Wei, Jia; Chen, Erqiang; Qin, Lang; Yu, Yanlei

    2016-09-01

    The manipulation of small amounts of liquids has applications ranging from biomedical devices to liquid transfer. Direct light-driven manipulation of liquids, especially when triggered by light-induced capillary forces, is of particular interest because light can provide contactless spatial and temporal control. However, existing light-driven technologies suffer from an inherent limitation in that liquid motion is strongly resisted by the effect of contact-line pinning. Here we report a strategy to manipulate fluid slugs by photo-induced asymmetric deformation of tubular microactuators, which induces capillary forces for liquid propulsion. Microactuators with various shapes (straight, ‘Y’-shaped, serpentine and helical) are fabricated from a mechanically robust linear liquid crystal polymer. These microactuators are able to exert photocontrol of a wide diversity of liquids over a long distance with controllable velocity and direction, and hence to mix multiphase liquids, to combine liquids and even to make liquids run uphill. We anticipate that this photodeformable microactuator will find use in micro-reactors, in laboratory-on-a-chip settings and in micro-optomechanical systems.

  11. Stability Analysis of Reactive Multiphase Slug Flows in Microchannels

    Directory of Open Access Journals (Sweden)

    Alejandro A. Munera Parra

    2014-05-01

    Full Text Available Conducting multiphase reactions in micro-reactors is a promising strategy for intensifying chemical and biochemical processes. A major unresolved challenge is to exploit the considerable benefits offered by micro-scale operation for industrial scale throughputs by numbering-up whilst retaining the underlying advantageous flow characteristics of the single channel system in multiple parallel channels. Fabrication and installation tolerances in the individual micro-channels result in different pressure losses and, thus, a fluid maldistribution. In this work, an additional source of maldistribution, namely the flow multiplicities, which can arise in a multiphase reactive or extractive flow in otherwise identical micro-channels, was investigated. A detailed experimental and theoretical analysis of the flow stability with and without reaction for both gas-liquid and liquid-liquid slug flow has been developed. The model has been validated using the extraction of acetic acid from n-heptane with the ionic liquid 1-Ethyl-3-methylimidazolium ethyl sulfate. The results clearly demonstrate that the coupling between flow structure, the extent of reaction/extraction and pressure drop can result in multiple operating states, thus, necessitating an active measurement and control concept to ensure uniform behavior and optimal performance.

  12. Preparation of inverted medium and processing in the inverted medium

    Energy Technology Data Exchange (ETDEWEB)

    Zafarullah, Ijaz [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)]. E-mail: ijaz@montana.edu; Tian Minghzen [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Chang Tiejun [The Spectrum Laboratory, Montana State University, Bozeman, MT 59717 (United States); Randall Babbitt, W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2007-11-15

    The processing of weak optical signals in spatial-spectral holographic (SSH) materials coherently inverted with optical frequency chirped pulses were investigated. Simulations and experimental studies in Tm{sup 3+}:YAG were conducted to characterize the parameters of the frequency chirped laser pulse used to invert the SSH material in order to obtain high photon echo efficiency for SSH lidar processing. Collinear and angled beam geometries and single shot and accumulated processes were investigated. Echo efficiencies as high as 450% were measured, significantly higher than the typical stimulated photon echo efficiency of 10%.

  13. Novel method for non-intrusive measurement of velocity and slug length in two- and three-phase slug flow in capillaries

    NARCIS (Netherlands)

    Wolffenbuttel, BMA; Nijhuis, TA; Stankiewicz, A; Moulijn, JA

    2002-01-01

    A method was developed for the measurement of velocity and slug length of two and three-phase flow in capillaries. The method consists of the combination of an impedance meter and two IR sensors. Non-intrusive measurement of the velocity can be performed with the IR sensors in gas-liquid and gas-liq

  14. Slug Controls Stem/Progenitor Cell Growth Dynamics during Mammary Gland Morphogenesis

    Science.gov (United States)

    Selmi, Abdelkader; Côme, Christophe; Faraldo, Maria-Luisa M.; Deugnier, Marie-Ange; Savagner, Pierre

    2012-01-01

    Background Morphogenesis results from the coordination of distinct cell signaling pathways controlling migration, differentiation, apoptosis, and proliferation, along stem/progenitor cell dynamics. To decipher this puzzle, we focused on epithelial-mesenchymal transition (EMT) “master genes”. EMT has emerged as a unifying concept, involving cell-cell adhesion, migration and apoptotic pathways. EMT also appears to mingle with stemness. However, very little is known on the physiological role and relevance of EMT master-genes. We addressed this question during mammary morphogenesis. Recently, a link between Slug/Snai2 and stemness has been described in mammary epithelial cells, but EMT master genes actual localization, role and targets during mammary gland morphogenesis are not known and we focused on this basic question. Methodology/Principal Findings Using a Slug–lacZ transgenic model and immunolocalization, we located Slug in a distinct subpopulation covering about 10–20% basal cap and duct cells, mostly cycling cells, coexpressed with basal markers P-cadherin, CK5 and CD49f. During puberty, Slug-deficient mammary epithelium exhibited a delayed development after transplantation, contained less cycling cells, and overexpressed CK8/18, ER, GATA3 and BMI1 genes, linked to luminal lineage. Other EMT master genes were overexpressed, suggesting compensation mechanisms. Gain/loss-of-function in vitro experiments confirmed Slug control of mammary epithelial cell luminal differentiation and proliferation. In addition, they showed that Slug enhances specifically clonal mammosphere emergence and growth, cell motility, and represses apoptosis. Strikingly, Slug-deprived mammary epithelial cells lost their potential to generate secondary clonal mammospheres. Conclusions/Significance We conclude that Slug pathway controls the growth dynamics of a subpopulation of cycling progenitor basal cells during mammary morphogenesis. Overall, our data better define a key mechanism

  15. Slug responses to grassland cutting and fertilizer application under plant functional group removal

    Science.gov (United States)

    Everwand, Georg; Scherber, Christoph; Tscharntke, Teja

    2013-04-01

    Current studies on trophic interactions in biodiversity experiments have largely relied on artificially sown gradients in plant diversity, but removal experiments with their more natural plant community composition are more realistic. Slugs are a major part of the invertebrate herbivore community, with some species being common pests in agriculture. We therefore investigated how strongly slugs are influenced by grassland management, plant biodiversity and composition. Here we analysed the effects of cutting frequency, fertilizer application and plant functional group composition on slug densities and their contribution to herbivory on Rumex acetosa in a removal experiment within a >100-year old grassland in Northern Germany. The experiment was laid out as a Latin rectangle with full factorial combinations of (i) plant functional group removal (3 levels) using herbicides, (ii) fertilizer application (2 levels) and (iii) cutting frequency (2 levels). The resulting 12 treatment combinations were replicated 6 times, resulting in 72 plots. We collected a total of 1020 individuals belonging to three species Arion distinctus (60.4% of individuals), Deroceras reticulatum (34.7%) and Arion lusitanicus (4.9%) using a cover board technique and additionally measured herbivore damage to R. acetosa. We found the highest slug abundance on plots with a low cutting frequency and high food resource availability (increased cover of forbs and taller vegetation). Fertilizer application had no significant effect on slug abundance, but caused higher herbivore damage to on R. acetosa, possibly as a result of increased tissue quality. The negative effect of higher cutting frequency on slug abundance was lowest in control plots with their naturally developed graminoid-forb communities (cutting reduced slug density by 6% in the control vs. 29% in herbicide plots). Our experiments therefore support the idea that more natural plant species compositions reduce the impact of disturbances (e

  16. Bubble colloidal AFM probes formed from ultrasonically generated bubbles.

    Science.gov (United States)

    Vakarelski, Ivan U; Lee, Judy; Dagastine, Raymond R; Chan, Derek Y C; Stevens, Geoffrey W; Grieser, Franz

    2008-02-05

    Here we introduce a simple and effective experimental approach to measuring the interaction forces between two small bubbles (approximately 80-140 microm) in aqueous solution during controlled collisions on the scale of micrometers to nanometers. The colloidal probe technique using atomic force microscopy (AFM) was extended to measure interaction forces between a cantilever-attached bubble and surface-attached bubbles of various sizes. By using an ultrasonic source, we generated numerous small bubbles on a mildly hydrophobic surface of a glass slide. A single bubble picked up with a strongly hydrophobized V-shaped cantilever was used as the colloidal probe. Sample force measurements were used to evaluate the pure water bubble cleanliness and the general consistency of the measurements.

  17. Slurry bubble column hydrodynamics

    Science.gov (United States)

    Rados, Novica

    Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids

  18. CRISIS FOCUS Blowing Bubbles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The Chinese stock and property markets have been outperforming expectations, fueled by an unprecedented surge in bank lending. Xie Guozhong, an economist and board member of Rosetta Stone Advisors, argues the robust Chinese economic figures are only propped up by bubbles, whose bursting will lead to a hard landing for the economy. Xie published his opinion in a related article in Caijing Magazine. Edited excerpts follow:

  19. Accelerating development of advanced inverters :

    Energy Technology Data Exchange (ETDEWEB)

    Neely, Jason C.; Gonzalez, Sigifredo; Ropp, Michael; Schutz, Dustin

    2013-11-01

    The high penetration of utility interconnected photovoltaic (PV) systems is causing heightened concern over the effect that variable renewable generation will have on the electrical power system (EPS). These concerns have initiated the need to amend the utility interconnection standard to allow advanced inverter control functionalities that provide: (1) reactive power control for voltage support, (2) real power control for frequency support and (3) better tolerance of grid disturbances. These capabilities are aimed at minimizing the negative impact distributed PV systems may have on EPS voltage and frequency. Unfortunately, these advanced control functions may interfere with island detection schemes, and further development of advanced inverter functions requires a study of the effect of advanced functions on the efficacy of antiislanding schemes employed in industry. This report summarizes the analytical, simulation and experimental work to study interactions between advanced inverter functions and anti-islanding schemes being employed in distributed PV systems.

  20. Shrinking equatorial plasma bubbles

    Science.gov (United States)

    Narayanan, V. L.; Gurubaran, S.; Shiokawa, K.; Emperumal, K.

    2016-07-01

    The formation of equatorial plasma bubbles (EPBs) associated with spread F irregularities are fairly common phenomenon in the postsunset equatorial ionosphere. These bubbles grow as a result of eastward polarization electric field resulting in upward E × B drift over the dip equator. As they grow they are also mapped to low latitudes along magnetic field lines. The EPBs are often observed as airglow depletions in the images of OI 630 nm emission. On occasions the growth of the features over the dip equator is observed as poleward extensions of the depletions in all-sky images obtained from low latitudes. Herein, we present interesting observations of decrease in the latitudinal extent of the EPBs corresponding to a reduction in their apex altitudes over the dip equator. Such observations indicate that these bubbles not only grow but also shrink on occasions. These are the first observations of shrinking EPBs. The observations discussed in this work are based on all-sky airglow imaging observations of OI 630.0 nm emission made from Panhala (11.1°N dip latitude). In addition, ionosonde observations made from dip equatorial site Tirunelveli (1.1°N dip latitude) are used to understand the phenomenon better. The analysis indicates that the speed of shrinking occurring in the topside is different from the bottomside vertical drifts. When the EPBs shrink, they might decay before sunrise hours.

  1. Inverter for Interchangeable Use as Current Source Inverter and Voltage Source Inverter for Interconnecting to Grid

    Science.gov (United States)

    Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji

    We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.

  2. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubble...

  3. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...

  4. Electrowetting of a soap bubble

    CERN Document Server

    Arscott, Steve

    2013-01-01

    A proof-of-concept demonstration of the electrowetting-on-dielectric of a sessile soap bubble is reported here. The bubbles are generated using a commercial soap bubble mixture - the surfaces are composed of highly doped, commercial silicon wafers covered with nanometre thick films of Teflon. Voltages less than 40V are sufficient to observe the modification of the bubble shape and the apparent bubble contact angle. Such observations open the way to inter alia the possibility of bubble-transport, as opposed to droplet-transport, in fluidic microsystems (e.g. laboratory-on-a-chip) - the potential gains in terms of volume, speed and surface/volume ratio are non-negligible.

  5. Measuring and modeling the bubble population produced by an underwater explosion.

    Science.gov (United States)

    Holt, Fred D; Lee Culver, R

    2011-11-01

    Underwater explosions have been studied intensively in the United States since 1941 [e.g., R. H. Cole, Underwater Explosions (Princeton University Press, Princeton, NJ, 1945), pp. 3-13]. Research to date has primarily focused on the initial shock and subsequent pressure waves caused by the oscillations of the "gas-globe" resulting from charge detonation. These phenomena have relatively short timescales (typically less than 2 s). However, after the gas-globe rises through the water column and breaks the surface, there remains behind a cloud of bubbles and perhaps debris from the explosion container which has been markedly less studied. A recent experiment measured the spatial and temporal acoustic response of the bubble cloud resulting from a 13.6 kg PBXN-111 charge detonated at 15.2 m (50 ft) depth. A directional projector was used to propagate linear frequency-modulated (5-65 kHz) and 40 kHz tonal pulses through the bubble cloud. Two hydrophone arrays were positioned so as to measure the energy lost in propagating through the bubble cloud. Three methods have been utilized to invert measurements and estimate the bubble population. The bubble population estimates have been used to develop a model for the bubble population resulting from an underwater explosion.

  6. Advanced Modular Inverter Technology Development

    Energy Technology Data Exchange (ETDEWEB)

    Adam Szczepanek

    2006-02-04

    Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high quality AC output that energy system customers demand. Today's inverters are expensive due to the cost of the power electronics components, and system designers must also tailor the inverter for individual applications. Thus, the benefits of mass production are not available, resulting in high initial procurement costs as well as high inverter maintenance and repair costs. Electricore, Inc. (www.electricore.org) a public good 501 (c) (3) not-for-profit advanced technology development consortium assembled a highly qualified team consisting of AeroVironment Inc. (www.aerovironment.com) and Delphi Automotive Systems LLC (Delphi), (www.delphi.com), as equal tiered technical leads, to develop an advanced, modular construction, inverter packaging technology that will offer a 30% cost reduction over conventional designs adding to the development of energy conversion technologies for crosscutting applications in the building, industry, transportation, and utility sectors. The proposed inverter allows for a reduction of weight and size of power electronics in the above-mentioned sectors and is scalable over the range of 15 to 500kW. The main objective of this program was to optimize existing AeroVironment inverter technology to improve power density, reliability and producibility as well as develop new topology to reduce line filter size. The newly developed inverter design will be used in automotive and distribution generation applications. In the first part of this program the high-density power stages were redesigned, optimized and fabricated. One of the main

  7. Influence of Catalysis and Oxidation on Slug Calorimeter Measurements in Arc Jets

    Science.gov (United States)

    Nawaz, Anuscheh; Driver, Dave; TerrazasSalinas, Imelda

    2012-01-01

    Arc jet tests play a critical role in the characterization and certification of thermal protection materials and systems (TPS). The results from these arc jet tests feed directly into computational models of material response and aerothermodynamics to predict the performance of the TPS in flight. Thus the precise knowledge of the plasma environment to which the test material is subjected, is invaluable. As one of the environmental parameters, the heat flux is commonly measured. The measured heat flux is used to determine the plasma enthalpy through analytical or computational models. At NASA Ames Research Center (ARC), slug calorimeters of a geometrically similar body to the test article are routinely used to determine the heat flux. A slug calorimeter is a thermal capacitance-type calorimeter that uses the temperature rise in a thermally insulated slug to determine the heat transfer rate, see Figure 1(left). Current best practices for measuring the heat flux with a slug calorimeter are described in ASTM E457 - 96. Both the calorimeter body and slug are made of Oxygen Free High Conductivity Copper, and are cleaned before each run.

  8. Evaluation of near-critical overdamping effects in slug-test response.

    Science.gov (United States)

    Weeks, E P; Clark, A C

    2013-01-01

    A slug test behaves as a harmonic oscillator, subject to both inertial effects and viscous damping. When viscous and inertial forces are closely balanced, the system is nearly critically damped, and water-level recovery is affected by inertial effects, but does not exhibit oscillation. These effects were investigated by use of type curves, generated both by modification of Kipp's (1985) computer program and by use of the Butler-Zhan (2004) model. Utility of the type curves was verified by re-analysis of the Regina slug test previously analyzed by Kipp. These type curves indicate that near-critical inertial effects result in early-time delayed water-level response followed by merger with, or more rapid recovery than, response for the fully damped case. Because of this early time response, slug tests in the moderately over-damped range are best analyzed using log-log type curves of (1 - H/H(0)) vs. Tt/r(2c). Failure to recognize inertial effects in slug test data could result in an over-estimate of transmissivity, and a too-small estimate of storage coefficient or too-large estimate of well skin. However, application of the widely used but highly empirical Hvorslev (1951) method to analyze both the Regina slug test and type-curve generated data indicate that such analyses provide T values within a factor of 2 of the true value.

  9. Snail/Slug-YAP/TAZ complexes cooperatively regulate mesenchymal stem cell function and bone formation.

    Science.gov (United States)

    Tang, Yi; Weiss, Stephen J

    2017-03-04

    Snail and Slug are zinc-finger transcription factors that play key roles in directing the epithelial-mesenchymal transition (EMT) programs associated with normal development as well as disease progression. More recent work suggests that these EMT-associated transcription factors also modulate the function of both embryonic and adult stem cells. Interestingly, YAP and TAZ, the co-transcriptional effectors of the Hippo pathway, likewise play an important role in stem cell self-renewal and lineage commitment. While direct intersections between the Snail/Slug and Hippo pathways have not been described previously, we recently described an unexpected cooperative interaction between Snail/Slug and YAP/TAZ that controls the self-renewal and differentiation properties of bone marrow-derived mesenchymal stem cells (MSCs), a cell population critical to bone development. Additional studies revealed that both Snail and Slug are able to form binary complexes with either YAP or TAZ that, together, control YAP/TAZ transcriptional activity and function throughout mouse development. Given the more recent observations that MSC-like cell populations are found in association throughout the vasculature where they participate in tissue regeneration, fibrosis and cancer, the Snail/Slug-YAP/TAZ axis is well-positioned to regulate global stem cell function in health and disease.

  10. Modelling and control of growing slugs in horizontal multiphase pipe flows

    Directory of Open Access Journals (Sweden)

    Steinar M. Elgsæter

    2006-07-01

    Full Text Available In this paper, the use of active control to restrict the length of growing slugs in horizontal pipelines is investigated. Specifically, the paper attempts to determine if such control can be attained with realistic measurements and actuators. Simulations in OLGA2000 show that a feedback controller can use measurements or estimates of slug length to control the growth of a slug in a horizontal pipeline by partially closing inlet or outlet chokes. A control-volume approach is used to develop a low-order model of inlet choke-slug growth dynamics based on mass- and impulse balances. The resulting model is a system of nonlinear differential-algebraic equations, which is suitable for observer-design. The tuned model is found to be in good agreement with experiments and OLGA2000-simulations. Linearizations of the model are found to be observable around realistic trajectories when rates and pressures at the inlet and outlet are measured. An extended Luenberger-observer is shown to give good estimates of slug length and -position in simulations even under model uncertainty.

  11. Slug tuner effect on the field stabilization of the drift tube linac

    Science.gov (United States)

    Kim, Han-Sung

    2015-02-01

    In a drift tube linac (DTL), the accelerating field is stabilized against external perturbation, through resonant coupling between each cell by using post couplers. For proper field stabilization tuning, the frequency band between the post mode and the cavity mode should be closed. In addition, the field profile along the beam axis of the highest post mode should be similar to that of the TM011 cavity mode. As a conventional method to correct the resonance frequency and to make the accelerating field flat, slug tuners are incorporated. We observed that the similarity of field profiles between the highest post mode and the TM011 cavity mode disappeared when the slug tuners were inserted too much into the DTL tank. To achieve field stabilization tuning, we limited the slug tuner insertion and used a tuning ring around each post coupler to tune the resonant frequency of the DTL tank. The details of the effect of a slug tuner on the field stabilization tuning and the solution to the resonant frequency tuning problem caused by limited slug insertion will be presented in this paper.

  12. An Investigation on the Void Fraction for upward Gas-Liquid Slug Flow in Vertical Pipe

    Institute of Scientific and Technical Information of China (English)

    夏国栋; 周芳德; 胡明胜

    2001-01-01

    In order to investigate the influence of the entrance effect on the spatial distribution of phases, the experiments on gas-liquid two-phase slug flow in a vertical pipe of 0.03m ID were carried out by using optical probes and an EKTAPRO 1000 high speed motion analyzer. It demonstrates that the radial profile of slug flow void fraction is parabolic. Influenced by the falling liquid film, the radial profile curve of liquid slug void fraction in the wake region is also parabolic. Since fully turbulent velocity distribution is built up in the developed region,the void fraction profile in this region is the saddle type. At given superficial liquid velocity, the liquid slug void fraction increases with gas velocity. The radial profiles of liquid slug void fraction at different axial locations are all saddle curves, but void fraction is obviously high around the centerline in the entrance region. The nearer the measuring station is from the entrance, the farther the peak location is away from the wall.

  13. Water slug formation and motion in gas flow channels: the effects of geometry, surface wettability, and gravity.

    Science.gov (United States)

    Cheah, May J; Kevrekidis, Ioannis G; Benziger, Jay B

    2013-08-06

    Water emerging from ∼100 μm pores into millimeter-size gas flow channels forms drops that grow and become slugs which span the flow channel. Flowing gas causes the slugs to detach and move down the channel. The effect of channel geometry, surface wettability, and gravity on the formation and motion of water slugs has been analyzed using high-speed video images of the drops and differential pressure-time traces. Drops grow and appear, assuming a sequence of shapes that minimize the total interfacial energy of the gas-liquid and liquid-solid interfaces. The drops are initially spherical caps centered on the pore (the liquid contacts one wall). Above a certain size, the drops move to the corner, forming "corner drops" (the liquid contacts two walls). Corner drops grow across the channel, evolving into partial liquid bridges (drops confined by three walls), and finally the drops span the channel cross-section forming slugs (contacting all four walls). Smaller slugs are formed in channels with hydrophobic walls than in channels with hydrophilic walls. Smaller slugs are formed in channels with curved walls than in square or rectangular channels. Slugs move when the differential gas pressure overcomes the force to move the advancing and receding gas-liquid-solid contact lines of the slugs. Residual water left behind in corners by moving slugs reduces the barriers for drops to form slugs, causing the steady-state slug volumes to be smaller than those seen at start-up in dry channels.

  14. Droplets, Bubbles and Ultrasound Interactions.

    Science.gov (United States)

    Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics.

  15. Solar Charged Stand Alone Inverter

    Directory of Open Access Journals (Sweden)

    M.Vasugi

    2014-07-01

    Full Text Available This paper deals with solar powered stand alone inverter which converts the variable dc output of a photovoltaic solar panel into ac that can be fed to loads. Stand alone inverters are used in systems where the inverter get its energy from batteries charged by photo voltaic arrays. A charge controller limits the rate at which electric current is added to or drawn from electric batteries. This charge discharge controller is needed to prevent the battery from being overcharged or discharged thus prolonging its life. The charge/discharge control is necessary in order to achieve safety and increase the capacity of the battery. The project has been tested according its operational purposes. Maximum power rating of the experimented solar charge controller is 100W according battery capacities. Cost effective solar charge controller has been designed and implemented to have efficient system and much longer battery lifetime. The dc output is given to inverter and then it is supplied to loads. This method is very cheap and cost effective.

  16. Flow in the negative wake of a Taylor bubble rising in viscoelastic carboxymethylcellulose solutions: particle image velocimetry measurements

    Science.gov (United States)

    Sousa, Renato G.; Nogueira, S.; Pinto, A. M. F. R.; Riethmuller, M. L.; Campos, J. B. L. M.

    2004-07-01

    A simultaneous technique employing particle image velocimetry (PIV) and shadowgraphy was used to study vertical slug flow in non-Newtonian fluids. Two aqueous solutions of 0.8 and 1.0 wt% carboxymethylcellulose (CMC) were studied and the flow field around individual Taylor bubbles fully characterized. The rheological fluid properties and pipe dimension yielded Reynolds numbers of 8 and 4 and Deborah numbers of 0.2 and 0.4. A negative wake was found downstream of the Taylor bubbles in both fluids. Below the bubble trailing edge, along the axis region, the fluid flows in the opposite direction to the bubble (negative wake), originating rotational liquid movements in adjacent regions. Even far downward from the bubble, rotational liquid movements are clearly seen and measured. In the 1.0 wt% CMC solution, the bubble trailing edge has the shape of a two-dimensional cusp. This two-dimensional cusp, of small dimensions, is seen in different orientations during the bubble rise-indicating a fast rotational movement. The asymmetrical shape of the trailing edge is responsible for small asymmetries in the flow in the wake region (three-dimensional flow). The asymmetrical shape associated with the rotational movement is responsible for an unsteady flow of small amplitude. In the 0.8 wt% CMC solution, the shape of the trailing edge changes during the bubble rise. An axisymmetric axial oscillation a continuous expansion and contraction of the trailing edge, is the origin of this behaviour. This oscillatory movement is responsible for an unsteady flow of small amplitude in the wake region.

  17. Bubble Size Distribution in a Vibrating Bubble Column

    Science.gov (United States)

    Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

    2016-11-01

    While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

  18. Dynamic Bubble Behaviour during Microscale Subcooled Boiling

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; PENG Xiao-Feng; David M.Christopher

    2005-01-01

    @@ Bubble cycles, including initiation, growth and departure, are the physical basis of nucleate boiling. The presentinvestigation, however, reveals unusual bubble motions during subcooled nucleate boiling on microwires 25 orl00μm in diameter. Two types of bubble motions, bubble sweeping and bubble return, are observed in theexperiments. Bubble sweeping describes a bubble moving back and forth along the wire, which is motion parallelto the wire. Bubble return is the bubble moving back to the wire after it has detached or leaping above thewire. Theoretical analyses and numerical simulations are conducted to investigate the driving mechanisms forboth bubble sweeping and return. Marangoni flow from warm to cool regions along the bubble interface is foundto produce the shear stresses needed to drive these unusual bubble movements.

  19. Applicability of slug interference tests under Hanford Site test conditions: Analytical assessment and field test evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Spane, F.A. Jr.

    1992-04-01

    Slug interference testing may be a useful technique for characterizing the hydraulic properties of high conductivity formations where problems associated with disposal of contaminated ground water make pumping tests undesirable. The suitability of the slug interference method for characterizing the unconfined aquifer at the Hanford Site was evaluated in a two-phase investigation. The first phase consisted of an analytical assessment. Slug interference responses were predicted over the range of conditions expected for the aquifer. The effects of partial penetration, delayed-yield and aquifer anisotropy on expected test results were also evaluated and possible analytical corrections are presented. The field test evaluation was conducted at a site with two observation wells and a stress well. Results verified the analytical evaluation and gave reasonable values of hydraulic conductivity and storativity. Test design considerations that optimize the observed response are discussed.

  20. The Slug Mucosal Irritation (SMI) assay: a tool for the evaluation of nasal discomfort.

    Science.gov (United States)

    Lenoir, Joke; Bachert, Claus; Remon, Jean-Paul; Adriaens, Els

    2013-09-01

    In this research project, the Slug Mucosal Irritation (SMI) assay was applied to predict nasal discomfort, investigating the correlation between responses in slugs and humans. Several SMI experiments and a Human Nose Irritation Test (HNIT) were performed with five NaCl solutions (0.4%, 1.3%, 2.6%, 5.4% and 10.4%) and two benzalkonium chloride solutions (BAC 0.02% and BAC 0.05%). In the HNIT, subjective evaluation of clinical discomfort was performed by 24 participants at several time points. Analyzes reveal that (1) a significant positive association existed between immediate stinging reaction reported by the participants and the mean total mucus production of the slugs (Spearman's Rank correlation=0.963, passay is a promising evaluation method for clinical nasal discomfort. Screening (prototype) formulations with this assay allows formula optimization prior to a clinical trial.

  1. Influence of process parameters on microstructure of semisolid A356 alloy slug cast through vertical pipe

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-rong; MAO Wei-min; PEI Sheng

    2008-01-01

    Suitable microstructures required for semisolid casting were formed by using a vertical pipe. Different lengths of vertical pipe, slug dimensions and pouring time were used to investigate their influence on the microstructure of A356 alloy. The results indicate that at the same length of the vertical pipe, the morphology of the primary α(Al) gradually deteriorates by the enlargement in the slug size, but the deteriorating speed slows down with increasing pipe length. They also reveal that the increase in the pipe length improves the microstructure, whereas no further improvement appears when the pipe length reaches a certain value. The optimum length of the pipe obtained in the present work is 430 mm. The microstructure of larger slug poured at higher pouring temperature gets worse and it can be improved by moderately elongating pouring time. The relative mechanisms were also discussed.

  2. Comparing functional similarity between a native and an alien slug in temperate rain forests of British Columbia

    Directory of Open Access Journals (Sweden)

    Mariano A. Rodriguez-Cabal

    2015-04-01

    Full Text Available The impacts of invasive alien species are greatest when they become dominant members of a community, introduce novel traits, and displace native species. Invasions by alien mollusks represent a novel context by which to compare trait differences between generalist native and introduced herbivores in terrestrial ecosystems. Here, we determined the abundance, habitat, feeding preferences, as well as the metabolic rate of the native Pacific banana slug (Ariolimax columbianus and the alien black slug (Arion rufus in the coastal forests of British Columbia, Canada. Through a series of observational and experimental studies, we found that alien slugs are more abundant, differ in their habitat preferences, and consumed more fungi (mushrooms than native banana slugs. Conversely, in an enclosures experiment we found that herbivory damage by native slugs was higher compared to enclosures with alien only and control enclosures. Finally, metabolic rates were similar for both slug species. These results suggest that alien black slugs possess a suite of traits that make them functionally different from native banana slugs.

  3. Control of slug damage to oilseed rape and wheat with imidacloprid seed dressings in laboratory and field experiments

    NARCIS (Netherlands)

    Simms, L.C.; Ester, A.; Wilson, M.J.

    2006-01-01

    Slugs are common pests of oilseed and cereal crops in Europe and are currently controlled using bait pellets that often fail to give adequate protection: Here we investigate the potential of the broad-spectrum insecticide imidacloprid, previously suggested to have activity against slugs, to control

  4. Three-phase slug flow in microchips can provide beneficial reaction conditions for enzyme liquid-liquid reactions.

    Science.gov (United States)

    Cech, Jiří; Přibyl, Michal; Snita, Dalimil

    2013-01-01

    Here, we introduce a solution to low stability of a two-phase slug flow with a chemical reaction occurring at the phase interface in a microfluidic reactor where substantial merging of individual reacting slugs results in the loss of uniformity of the flow. We create a three-phase slug flow by introducing a third fluid phase into the originally two-phase liquid-liquid slug flow, which generates small two-phase liquid slugs separated by gas phase. Introduction of the third phase into our system efficiently prevents merging of slugs and provides beneficial reaction conditions, such as uniform flow pattern along the whole reaction capillary, interfacial area with good reproducibility, and intensive water-oil interface renewal. We tested the three-phase flow on an enzyme hydrolysis of soybean oil and compared the reaction conversion with those from unstable two-phase slug flows. We experimentally confirmed that the three-phase slug flow arrangement provides conversions and pressure drops comparable or even better with two-phase liquid-liquid arrangements.

  5. 21 CFR 184.1859 - Invert sugar.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Invert sugar. 184.1859 Section 184.1859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1859 Invert sugar. (a) Invert sugar (CAS Reg. No. 8013-17-0) is an aqueous...

  6. Naturally-Forced Slug Flow Expander for Application in a Waste-Heat Recovery Cycle

    Directory of Open Access Journals (Sweden)

    Ben de Witt

    2014-11-01

    Full Text Available This paper investigates a slug-flow expander (SFE for conversion of high-pressure gas/vapor into kinetic energy of liquid slugs. The energy transfer from high-pressure to kinetic energy is quantified using thrust plate measurements. Non-dimensional thrust data is used to quantify performance by normalizing measured thrust by thrust for the same water flow rate at zero air flow rate. A total of 13 expander configurations are investigated and geometries with the shortest cavity length and the smallest exit diameter are found to result in the largest non-dimensional thrust increase. Results show that thrust augmentation increases with the initiation of slug flow in the SFE. The analysis performed on the normalized thrust readings suggested that as the water and air flow were increased to critical conditions, the liquid slugs produced by the SFE augmented the thrust measurements. The final performance evaluation was based on linear regression of the normalized thrust measurements where slug flow was generated for each SFE architecture. Greater magnitudes of the slope from the linear regression indicated the propensity of the SFE to augment thrust. This analysis confirmed that for the SFE configurations over the range of values investigated, the SFE increased thrust up to three times its original value at no air flow. Given the inherent multiphase nature of the slug-flow expander, application to systems involving expansion of wetting fluids (water as part of a waste-heat recovery system or air with water droplet formation (as part of a compressed-air energy storage system could be considered.

  7. Stable tridimensional bubble clusters in multi-bubble sonoluminescence (MBSL).

    Science.gov (United States)

    Rosselló, J M; Dellavale, D; Bonetto, F J

    2015-01-01

    In the present work, stable clusters made of multiple sonoluminescent bubbles are experimentally and theoretically studied. Argon bubbles were acoustically generated and trapped using bi-frequency driving within a cylindrical chamber filled with a sulfuric acid aqueous solution (SA85w/w). The intensity of the acoustic pressure field was strong enough to sustain, during several minutes, a large number of positionally and spatially fixed (without pseudo-orbits) sonoluminescent bubbles over an ellipsoidally-shaped tridimensional array. The dimensions of the ellipsoids were studied as a function of the amplitude of the applied low-frequency acoustic pressure (PAc(LF)) and the static pressure in the fluid (P0). In order to explain the size and shape of the bubble clusters, we performed a series of numerical simulations of the hydrodynamic forces acting over the bubbles. In both cases the observed experimental behavior was in excellent agreement with the numerical results. The simulations revealed that the positionally stable region, mainly determined by the null primary Bjerknes force (F→Bj), is defined as the outer perimeter of an axisymmetric ellipsoidal cluster centered in the acoustic field antinode. The role of the high-frequency component of the pressure field and the influence of the secondary Bjerknes force are discussed. We also investigate the effect of a change in the concentration of dissolved gas on the positional and spatial instabilities through the cluster dimensions. The experimental and numerical results presented in this paper are potentially useful for further understanding and modeling numerous current research topics regarding multi-bubble phenomena, e.g. forces acting on the bubbles in multi-frequency acoustic fields, transient acoustic cavitation, bubble interactions, structure formation processes, atomic and molecular emissions of equal bubbles and nonlinear or unsteady acoustic pressure fields in bubbly media.

  8. Single-electron differential-amplifier/inverter/non-inverter

    Science.gov (United States)

    Hung, K.-M.; Chen, C.-S.; Lin, T.-W.

    2006-07-01

    This work presents a single-electron differential amplifier (SEDA), inverter, and non-inverter based on the triple single-dopant quantum-dot (TSDQD) configuration, with new structures. The competition between the field-induced and confinement-related shifts in the wavefunction of the quantum dots yields a field-controllable spatial-displacement single-electron transistor. Deeper impurity levels in quantum dots promise a higher operating temperature and higher on/off current ratios. The I- V characteristics of the device, studied using the transfer Hamiltonian approach (THA), show that the ratio of on/off currents is >80 000 and the voltage gain is >4 eV/Ry, where V is the applied voltage.

  9. Slugging their way to immortality: driving mammary epithelial cells into a stem cell-like state.

    Science.gov (United States)

    Soady, Kelly; Smalley, Matthew J

    2012-09-10

    Delineating the molecular factors that define and maintain the mammary stem cell state is vital for understanding normal development and tumourigenesis. A recent study by Guo and colleagues identifies two master transcriptional regulators of mammary stem cells, Slug and Sox9, ectopic expression of which confers stem cell attributes on differentiated mammary epithelial cells. Slug and Sox9 expression was also shown to determine in vivo metastatic potential of human breast cancer cell lines. Understanding these factors in the context of normal lineage differentiation is an important step toward elucidating the mammary epithelial cell hierarchy and the origins of cancer stem cells.

  10. Explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den D.M.; Elwenspoek, M.

    2008-01-01

    Explosive evaporation occurs when a liquid is exposed to extremely high heat-fluxes. Within a few microseconds a bubble in the form vapour film is generated, followed by rapid growth due to the pressure impulse and finally the bubbles collapse. This effect, which already has proven its use in curren

  11. Tuning bubbly structures in microchannels.

    Science.gov (United States)

    Vuong, Sharon M; Anna, Shelley L

    2012-06-01

    Foams have many useful applications that arise from the structure and size distribution of the bubbles within them. Microfluidics allows for the rapid formation of uniform bubbles, where bubble size and volume fraction are functions of the input gas pressure, liquid flow rate, and device geometry. After formation, the microchannel confines the bubbles and determines the resulting foam structure. Bubbly structures can vary from a single row ("dripping"), to multiple rows ("alternating"), to densely packed bubbles ("bamboo" and dry foams). We show that each configuration arises in a distinct region of the operating space defined by bubble volume and volume fraction. We describe the boundaries between these regions using geometric arguments and show that the boundaries are functions of the channel aspect ratio. We compare these geometric arguments with foam structures observed in experiments using flow-focusing, T-junction, and co-flow designs to generate stable nitrogen bubbles in aqueous surfactant solution and stable droplets in oil containing dissolved surfactant. The outcome of this work is a set of design parameters that can be used to achieve desired foam structures as a function of device geometry and experimental control parameters.

  12. Bubble chamber: colour enhanced tracks

    CERN Multimedia

    1998-01-01

    This artistically-enhanced image of real particle tracks was produced in the Big European Bubble Chamber (BEBC). Liquid hydrogen is used to create bubbles along the paths of the particles as a piston expands the medium. A magnetic field is produced in the detector causing the particles to travel in spirals, allowing charge and momentum to be measured.

  13. Bubble coalescence in breathing DNA

    DEFF Research Database (Denmark)

    Novotný, Tomas; Pedersen, Jonas Nyvold; Ambjörnsson, Tobias;

    2007-01-01

    We investigate the coalescence of two DNA bubbles initially located at weak segments and separated by a more stable barrier region in a designed construct of double-stranded DNA. The characteristic time for bubble coalescence and the corresponding distribution are derived, as well as the distribu...

  14. Triangular bubble spline surfaces.

    Science.gov (United States)

    Kapl, Mario; Byrtus, Marek; Jüttler, Bert

    2011-11-01

    We present a new method for generating a [Formula: see text]-surface from a triangular network of compatible surface strips. The compatible surface strips are given by a network of polynomial curves with an associated implicitly defined surface, which fulfill certain compatibility conditions. Our construction is based on a new concept, called bubble patches, to represent the single surface patches. The compatible surface strips provide a simple [Formula: see text]-condition between two neighboring bubble patches, which are used to construct surface patches, connected with [Formula: see text]-continuity. For [Formula: see text], we describe the obtained [Formula: see text]-condition in detail. It can be generalized to any [Formula: see text]. The construction of a single surface patch is based on Gordon-Coons interpolation for triangles.Our method is a simple local construction scheme, which works uniformly for vertices of arbitrary valency. The resulting surface is a piecewise rational surface, which interpolates the given network of polynomial curves. Several examples of [Formula: see text], [Formula: see text] and [Formula: see text]-surfaces are presented, which have been generated by using our method. The obtained surfaces are visualized with reflection lines to demonstrate the order of smoothness.

  15. Squeezing through: capsule or bubble?

    CERN Document Server

    Dawson, Geoffrey

    2013-01-01

    In this fluid dynamics video, we compare the deformation of two flexible particles as they propagate through a sudden constriction of a liquid filled channel under constant-flux flow: a gas bubble, and a capsule formed by encapsulating a liquid droplet in a cross-linked polymeric membrane. Both bubble and capsule adopt highly contorted configurations as they squeeze through the constriction, exhibit broadly similar features over a wide range of flow rates, and rupture for sufficiently high flow rates. However, at flow rates prior to rupture, certain features of the deformation allow bubble and capsule to be distinguished: bubbles exhibit a tip-streaming singularity associated with critical thinning of the rear of the bubble, while the capsule membrane wrinkles under large compressive stresses induced by the constriction.

  16. Growing bubbles rising in line

    Directory of Open Access Journals (Sweden)

    John F. Harper

    2001-01-01

    Full Text Available Over many years the author and others have given theories for bubbles rising in line in a liquid. Theory has usually suggested that the bubbles will tend towards a stable distance apart, but experiments have often showed them pairing off and sometimes coalescing. However, existing theory seems not to deal adequately with the case of bubbles growing as they rise, which they do if the liquid is boiling, or is a supersaturated solution of a gas, or simply because the pressure decreases with height. That omission is now addressed, for spherical bubbles rising at high Reynolds numbers. As the flow is then nearly irrotational, Lagrange's equations can be used with Rayleigh's dissipation function. The theory also works for bubbles shrinking as they rise because they dissolve.

  17. Cascaded Multicell Trans-Z-Source Inverters

    DEFF Research Database (Denmark)

    Li, Ding; Chiang Loh, Poh; Zhu, Miao

    2013-01-01

    Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must....... Simulation and experimental results have shown that the multicell inverters can produce the same high-voltage gain, while keeping currents and voltages of the components low. The inverters can also step down their output voltages like a traditional voltage-source inverter without compromising waveform...

  18. Neutral Point Clamped Npc Type Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Purohit Sadanand Chandrashekhar

    2015-08-01

    Full Text Available Concept of the multilevel inverter is same as the other inverter which is to converts Direct current DC to Alternating current AC .The inverted current can be at any vital voltage and frequency with the use of pertinent transformers switching and control circuits. From the source like batteries solar panel wind turbine or fuel cell the inverter will convert the DC electricity to AC electricity. In this modern technology Power electronics is very important where it used in a great variety of product. With the high potential in high power for industry multilevel inverter will become most popular for so many applications.

  19. Advancement in solar PV Inverter

    Directory of Open Access Journals (Sweden)

    Devendra Doda

    2012-09-01

    Full Text Available This teardown article will delve into the architectural design and components of a solar inverter card starting from the Solar panel DC inputs and working through the DC to AC conversion process to the AC output that is sent out to the power grid. Features needed to be implemented into such a design to meet various safety and other performance standards as well as stringent power company demands upon the signal that is put onto their grid will be shown. In the process, major elements and component choices made in the design of the series of solar inverters, from the EMI suppression capacitors with a special emphasis on isolation and protection, through the smart use of optically isolated MOSFETgatedrivers.

  20. Integrated Inverter And Battery Charger

    Science.gov (United States)

    Rippel, Wally E.

    1988-01-01

    Circuit combines functions of dc-to-ac inversion (for driving ac motor in battery-powered vehicle) and ac-to-dc conversion (for charging battery from ac line when vehicle not in use). Automatically adapts to either mode. Design of integrated inverter/charger eliminates need for duplicate components, saves space, reduces weight and cost of vehicle. Advantages in other applications : load-leveling systems, standby ac power systems, and uninterruptible power supplies.

  1. Experimental analysis of bubble-driven magma motion in a volcanic conduit and how it affects lava lake sustainability

    Science.gov (United States)

    Pansino, S. G.; Calder, E. S.; Menand, T.

    2013-12-01

    The effect of bubble ascent dynamics on magma motion within a conduit has not previously been well studied. Investigation of bubble dynamics is undertaken using an analogue model for magma convection in a volcanic conduit, representing the upper-most section where large bubbles or gas slugs can be present. In the experiments, bubbles rise through an initially stagnant medium in a cylindrical tube and the resulting liquid descent velocity (liquid flux) is measured. The effects of gas flux and liquid viscosity on liquid flux are determined. It is shown that liquid flux depends on gas flux and on the two-phase flow regime. The induced liquid flux is an order of magnitude higher when the two-phase flow regime is turbulent rather than laminar. For each flow regime, scaling analysis is used to describe how the liquid flux changes with gas flux (using experimentally-derived data). The liquid flux is roughly 15% of the gas flux in the turbulent regime and 1% of the gas flux in the laminar regime. These models are then applied to field and remote sensing data from selected volcanoes to determine how the magma flux estimation changes with consideration of bubble dynamics. Bubble-driven liquid motions can have a significant effect on magma convection in low-viscosity systems (less than 103 Pa*s), affecting the shallowest hundreds to tens of meters of magma in the conduit. In higher-viscosity magmas, these effects are more suppressed, causing laminar flow proportions of magma flux. Keywords: magma convection, lava lakes, bubble-driven convection, persistent volcanism, gas dynamics, two-phase flow, degassing

  2. It takes three to tango: 2. Bubble dynamics in basaltic volcanoes and ramifications for modeling normal Strombolian activity

    Science.gov (United States)

    Suckale, Jenny; Hager, Bradford H.; Elkins-Tanton, Linda T.; Nave, Jean-Christophe

    2010-07-01

    This is the second paper of two that examine numerical simulations of buoyancy-driven flow in the presence of large viscosity contrasts. In the first paper, we demonstrated that a combination of three numerical tools, an extended ghost fluid type method, the level set approach, and the extension velocity technique, accurately simulates complex interface dynamics in the presence of large viscosity contrasts. In this paper, we use this threefold numerical method to investigate bubble dynamics in the conduits of basaltic volcanos with a focus on normal Strombolian eruptions. Strombolian type activity, named after the famously episodic eruptions at Stromboli volcano, is characterized by temporally discrete fountains of incandescent clasts. The mildly explosive nature of normal Strombolian activity, as compared to more effusive variants of basaltic volcanism, is related to the presence of dissolved gas in the magma, yielding a complex two-phase flow problem. We present a detailed scaling analysis allowing identification of the pertinent regime for a given flow problem. The dynamic interactions between gas and magma can be classified into three nondimensional regimes on the basis of bubble sizes and magma viscosity. Resolving the fluid dynamics at the scale of individual bubbles is not equally important in all three regimes: As long as bubbles remain small enough to be spherical, their dynamic interactions are limited compared to the rich spectrum of coalescence and breakup processes observed for deformable bubbles, in particular, once inertia ceases to be negligible. One key finding in our simulations is that both large gas bubbles and large conduit-filling gas pockets ("slugs") are prone to dynamic instabilities that lead to their rapid breakup during buoyancy-driven ascent. We provide upper bound estimates for the maximum stable bubble size in a given magmatic system and discuss the ramifications of our results for two commonly used models of normal Strombolian type

  3. Doughnut-shaped soap bubbles

    Science.gov (United States)

    Préve, Deison; Saa, Alberto

    2015-10-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L . It is well known that the sphere is the solution for V =L3/6 π2 , and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V <α L3/6 π2 , with α ≈0.21 , such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V <α L3/6 π2 cannot be stable and should not exist in foams, for instance.

  4. Energy spectra in bubbly turbulence

    CERN Document Server

    Prakash, Vivek N; Ramos, Fabio Ernesto Mancilla; Tagawa, Yoshiyuki; Lohse, Detlef; Sun, Chao

    2013-01-01

    We conduct experiments in a turbulent bubbly flow to study the unknown nature of the transition between the classical -5/3 energy spectrum scaling for a single-phase turbulent flow and the -3 scaling for a swarm of bubbles rising in a quiescent liquid and of bubble-dominated turbulence. The bubblance parameter, b, which measures the ratio of the bubble-induced kinetic energy to the kinetic energy induced by the turbulent liquid fluctuations before bubble injection, is used to characterise the bubbly flow. We vary b from $b = \\infty$ (pseudo-turbulence) to b = 0 (single-phase flow) over 2-3 orders of magnitude: ~O(0.01, 0.1, 5) to study its effect on the turbulent energy spectrum and liquid velocity fluctuations. The experiments are conducted in a multi-phase turbulent water tunnel with air bubbles of diameters 2-4 mm and 3-5 mm. An active-grid is used to generate nearly homogeneous and isotropic turbulence in the liquid flow. The liquid speeds and gas void fractions are varied to achieve the above mentioned b...

  5. Acquired phototrophy through retention of functional chloroplasts increases growth efficiency of the sea slug Elysia viridis.

    Directory of Open Access Journals (Sweden)

    Finn A Baumgartner

    Full Text Available Photosynthesis is a fundamental process sustaining heterotrophic organisms at all trophic levels. Some mixotrophs can retain functional chloroplasts from food (kleptoplasty, and it is hypothesized that carbon acquired through kleptoplasty may enhance trophic energy transfer through increased host growth efficiency. Sacoglossan sea slugs are the only known metazoans capable of kleptoplasty, but the relative fitness contributions of heterotrophy through grazing, and phototrophy via kleptoplasts, are not well understood. Fitness benefits (i.e. increased survival or growth of kleptoplasty in sacoglossans are commonly studied in ecologically unrealistic conditions under extended periods of complete darkness and/or starvation. We compared the growth efficiency of the sacoglossan Elysia viridis with access to algal diets providing kleptoplasts of differing functionality under ecologically relevant light conditions. Individuals fed Codium fragile, which provide highly functional kleptoplasts, nearly doubled their growth efficiency under high compared to low light. In contrast, individuals fed Cladophora rupestris, which provided kleptoplasts of limited functionality, showed no difference in growth efficiency between light treatments. Slugs feeding on Codium, but not on Cladophora, showed higher relative electron transport rates (rETR in high compared to low light. Furthermore, there were no differences in the consumption rates of the slugs between different light treatments, and only small differences in nutritional traits of algal diets, indicating that the increased growth efficiency of E. viridis feeding on Codium was due to retention of functional kleptoplasts. Our results show that functional kleptoplasts from Codium can provide sacoglossan sea slugs with fitness advantages through photosynthesis.

  6. Ultraviolet Radiation and the Slug Transcription Factor Induce Proinflammatory and Immunomodulatory Mediator Expression in Melanocytes

    Directory of Open Access Journals (Sweden)

    Stephanie H. Shirley

    2012-01-01

    Full Text Available Despite extensive investigation, the precise contribution of the ultraviolet radiation (UVR component of sunlight to melanoma etiology remains unclear. UVR induces keratinocytes to secrete proinflammatory and immunomodulatory mediators that promote inflammation and skin tumor development; expression of the slug transcription factor in keratinocytes is required for maximal production of these mediators. In the present studies we examined the possibility that UVR-exposed melanocytes also produce proinflammatory mediators and that Slug is important in this process. Microarray studies revealed that both UVR exposure and Slug overexpression altered transcription of a variety of proinflammatory mediators by normal human melanocytes; some of these mediators are also known to stimulate melanocyte growth and migration. There was little overlap in the spectra of cytokines produced by the two stimuli. However IL-20 was similarly induced by both stimuli and the NFκB pathway appeared to be important in both circumstances. Further exploration of UVR-induced and Slug-dependent pathways of cytokine induction in melanocytes may reveal novel targets for melanoma therapy.

  7. Toxocariasis After Slug Ingestion Characterized by Severe Neurologic, Ocular, and Pulmonary Involvement

    OpenAIRE

    Fellrath, Jean-Marc; Magnaval, Jean-François

    2014-01-01

    Human toxocariasis is generally a benign, self-curing disease, and neurologic involvement is quite exceptional. In this study, we report a case of toxocariasis caused by ingestion of an unusual transport host, namely live slugs. The clinical picture comprised eosinophilic lung involvement with severe neurologic disorders in relation to vasculitis as well as retinal detachment.

  8. Thevetia peruviana (Family: Apocynaceae in the control of slug and snail pests

    Directory of Open Access Journals (Sweden)

    A. Panigrahi

    1994-06-01

    Full Text Available An aqueous extract prepared from Kernels of the fruit of Thevetia peruviana (Pers. Schumann (Family : Apocynaceae was found under experimental conditions, to be toxic ti the slug Laevicaulis alte (Férussac and the snail Achatina fulica Bowdich, the important agrihorticultural pests of Indo-Pacific countries. Concentrations as low as 1% (w/v killed all the slugs exposed in less than 981.00 (± SD 22.76 min, and 2% of the extract killed 100% of the slugs L. alte and 50%, 50% and 30% of the snail A. fulica in between 92.34 (± SD 6.63 - 321.33 (± SD 4.14 and 271.20 (± SD 17.54 - 298.26 (± SD 16.69 min respectively. The most effective concentration of the extract was 20%; it killed 100% of exposed slugs and snails within a short time (40-50 and 90-1440 min respectively when the extract was exposed on the soil in experimental trays or when it was applied to potato slices offered as food to the gastropods.

  9. Lactic Acid Extraction and Mass Transfer Characteristics in Slug Flow Capillary Microreactors

    NARCIS (Netherlands)

    Susanti,; Winkelman, Jozef G.M.; Schuur, Boelo; Heeres, Hero J.; Yue, Jun

    2016-01-01

    Capillary microreactors operated under the slug flow regime were investigated for the separation of lactic acid from the aqueous phase using liquid–liquid reactive extraction. The experiments were performed at a 1:1 flow ratio of the aqueous to organic phases in a setup consisting of an inlet Y-type

  10. Recreating Riser Slugging Flow Based on an Economic Lab-sized Setup

    DEFF Research Database (Denmark)

    Hansen, Lasse; Pedersen, Simon; Yang, Zhenyu;

    2013-01-01

    As a kind of periodic phenomenon, the slugging flow in the offshore oil & gas production addresses a lot of attentions, due to its limitation of production rate, periodic overload processing facilities, and even direct cause of emergent shutdown. This work studies the emulation of the riser...

  11. Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor

    Energy Technology Data Exchange (ETDEWEB)

    Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno [University of Zagreb, Zagreb (Croatia)

    2015-06-15

    Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R{sup 2}=0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k{sub L}a=4,652-1,9807 h{sup -1}.

  12. Transient drift flux modelling of severe slugging in pipeline-riser systems

    NARCIS (Netherlands)

    Malekzadeh, R.; Belfroid, S.P.C.; Mudde, R.F.

    2012-01-01

    A large number of pipelines in the petroleum industry simultaneously transport gas and liquid. Transient behaviour of multiphase flow is frequently encountered in these pipelines. A common example is severe slugging that can occur in multiphase flow systems where a pipeline segment with a downward o

  13. Velocity of large bubble in liquid-solid mixture in a vertical tube

    Energy Technology Data Exchange (ETDEWEB)

    Hamaguchi, H.; Sakaguchi, T. [Kobe Univ., Kobe (Japan)

    1995-09-01

    The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V{sub o} in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V{sup *}(=V/V{sub o}), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V{sup *} decreases linearly against the volumetric solid fraction {epsilon} of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V{sup *} and {epsilon} is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid.

  14. Investigation of liquid phase axial dispersion in Taylor bubble flow by radiotracer residence time distribution analysis

    Directory of Open Access Journals (Sweden)

    Jin J.H.

    2013-05-01

    Full Text Available A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137mBa produced from a 137Cs/137mBa radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl scintillation detectors. Validation of 137mBa in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe∼102 which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.

  15. Partial coalescence of soap bubbles

    Science.gov (United States)

    Harris, Daniel M.; Pucci, Giuseppe; Bush, John W. M.

    2015-11-01

    We present the results of an experimental investigation of the merger of a soap bubble with a planar soap film. When gently deposited onto a horizontal film, a bubble may interact with the underlying film in such a way as to decrease in size, leaving behind a smaller daughter bubble with approximately half the radius of its progenitor. The process repeats up to three times, with each partial coalescence event occurring over a time scale comparable to the inertial-capillary time. Our results are compared to the recent numerical simulations of Martin and Blanchette and to the coalescence cascade of droplets on a fluid bath.

  16. Sonochemistry and the acoustic bubble

    CERN Document Server

    Grieser, Franz; Enomoto, Naoya; Harada, Hisashi; Okitsu, Kenji; Yasui, Kyuichi

    2015-01-01

    Sonochemistry and the Acoustic Bubble provides an introduction to the way ultrasound acts on bubbles in a liquid to cause bubbles to collapse violently, leading to localized 'hot spots' in the liquid with temperatures of 5000° celcius and under pressures of several hundred atmospheres. These extreme conditions produce events such as the emission of light, sonoluminescence, with a lifetime of less than a nanosecond, and free radicals that can initiate a host of varied chemical reactions (sonochemistry) in the liquid, all at room temperature. The physics and chemistry behind the p

  17. Bubble Growth in Lunar Basalts

    Science.gov (United States)

    Zhang, Y.

    2009-05-01

    Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth

  18. Thermal Phase in Bubbling Geometries

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-Yong

    2008-01-01

    We use matrix model to study thermal phase in bubbling half-BPS type IIB geometries with SO(4)×SO(4) symmetry.Near the horizon limit,we find that thermal vacua of bubbling geometries have disjoint parts,and each part is one kind of phase of the thermal system.We connect the thermal dynamics of bubbling geometries with one-dimensional fermions thermal system.Finally,we try to give a new possible way to resolve information loss puzzle.

  19. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    spectroscopy analysis of gases liberated during heating of the glass reveals that small bubbles contain predominantly CH4, CO and CO2, whereas large bubbles bear N2, SO2 and H2S. The methodology utilised in this work can, besides mapping the bubbles in a glass, be applied to shed light on the sources of bubble...

  20. Bubble stimulation efficiency of dinoflagellate bioluminescence.

    Science.gov (United States)

    Deane, Grant B; Stokes, M Dale; Latz, Michael I

    2016-02-01

    Dinoflagellate bioluminescence, a common source of bioluminescence in coastal waters, is stimulated by flow agitation. Although bubbles are anecdotally known to be stimulatory, the process has never been experimentally investigated. This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater. Cells were stimulated by isolated bubbles of 0.3-3 mm radii rising at their terminal velocity, and also by bubble clouds containing bubbles of 0.06-10 mm radii for different air flow rates. Stimulation efficiency, the proportion of cells producing a flash within the volume of water swept out by a rising bubble, decreased with decreasing bubble radius for radii less than approximately 1 mm. Bubbles smaller than a critical radius in the range 0.275-0.325 mm did not stimulate a flash response. The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud, with lower stimulation levels observed for clouds with smaller bubbles. An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates. High air flow rates stimulated more light emission than expected, presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud. These results are relevant to bioluminescence stimulation by bubbles in two-phase flows, such as in ship wakes, breaking waves, and sparged bioreactors.

  1. Gas6 induces cancer cell migration and epithelial–mesenchymal transition through upregulation of MAPK and Slug

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yunhee [Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon (Korea, Republic of); Lee, Mira [Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon (Korea, Republic of); Kim, Semi, E-mail: semikim@kribb.re.kr [Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon (Korea, Republic of)

    2013-04-26

    Highlights: •We investigated the molecular mechanisms underlying Gas6-mediated cancer cell migration. •Gas6 treatment and subsequent Axl activation induce cell migration and EMT via upregulation of Slug. •Slug expression mediated by Gas6 is mainly through c-Jun and ATF-2 in an ERK1/2 and JNK-dependent manner. •The Gas6/Axl-Slug axis may be exploited as a target for anti-cancer metastasis therapy. -- Abstract: Binding of Gas6 to Axl (Gas6/Axl axis) alters cellular functions, including migration, invasion, proliferation, and survival. However, the molecular mechanisms underlying Gas6-mediated cell migration remain poorly understood. In this study, we found that Gas6 induced the activation of JNK and ERK1/2 signaling in cancer cells expressing Axl, resulting in the phosphorylation of activator protein-1 (AP-1) transcription factors c-Jun and ATF-2, and induction of Slug. Depletion of c-Jun or ATF-2 by siRNA attenuated the Gas6-induced expression of Slug. Slug expression was required for cell migration and E-cadherin reduction/vimentin induction induced by Gas6. These results suggest that Gas6 induced cell migration via Slug upregulation in JNK- and ERK1/2-dependent mechanisms. These data provide an important insight into the molecular mechanisms mediating Gas6-induced cell migration.

  2. A PLIC-VOF-Based Simulation of Water-Organic Slug Flow Characteristics in a T-Shaped Microchannel

    Directory of Open Access Journals (Sweden)

    Xian Wang

    2013-01-01

    Full Text Available A water-organic slug flow in a T-shaped microchannel was numerically studied due to its importance in the microreactor system. Various factors affecting the flow mode were studied, for example, channel width, fluid viscosity, interfacial tension, and inlet velocity. The volume of fluid (VOF method was used to track the liquid-liquid interface, and the piecewise-liner interface construction (PLIC technique was adopted to get a sharp interface. The interfacial tension was simulated with continuum surface force (CSF, model and the wall adhesion boundary condition was taken into consideration. The results show that strong vortexes appear in both phases at the meeting sites of main and lateral channels where an organic slug is producing. Inlet velocity influences the slug length and flow mode greatly. The ratio between the slug lengths of two phases in the main channel is almost equal to the ratio between their inlet velocities. If the slug is produced, the interfacial tension and organic viscosity have less effect on the slug length for 200 μm microchannel. The slug producing rate is much higher in a narrow channel than that in a wide channel.

  3. Bubble Dynamics and Resulting Noise from Traveling Bubble Cavitation.

    Science.gov (United States)

    1982-04-13

    has resulted in models which aqree well with bubble dynamics recorded by high speed film . Chahine, et. al. (23) incorporated asymmetric bubble...recording on the tape soundtrack . 3.8 Measurement of Gas Nuclei in Water The role of nuclei density and size in cavitation inception has been the subject...interference between the coherent background and the particle-diffracted radiation exooses photographic film in the far-field of the nuclei. This

  4. Application of Ceramic Bond Coating for Reusable Melting Crucible of Metallic Fuel Slugs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Song, Hoon; Ko, Young-Mo; Park, Jeong-Yong; Lee, Chan-Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hong, Ki-Won [Chungnam National University, Daejeon (Korea, Republic of)

    2016-10-15

    Metal fuel slugs of the driver fuel assembly have been fabricated by injection casting of the fuel alloys under a vacuum state or an inert atmosphere. Traditionally, metal fuel such as a U-Zr alloy system for SFR has been melted in slurry-coated graphite crucibles and cast in slurry-coated quartz tube molds to prevent melt/material interactions. Reactive coatings and porous coatings can be a source of melt contaminations, and fuel losses, respectively. Ceramic Y{sub 2}O{sub 3}, TiC, and TaC coating materials showed no penetration in the protective layer after a melt dipping test. However, the ceramic coating materials showed separations in the coating interface between the substrate and coating layer, or between the coating layer and fuel melt after the dipping test. All plasma-spray coated methods maintained a sound coating state after a dipping test with U-10wt.%Zr melt. A single coating Y{sub 2}O{sub 3}(150) layer and double coating layer of TaC(50)-Y{sub 2}O{sub 3}(100), showed a sound state or little penetration in the protective layer after a dipping test with U-10wt.%Zr-5wt.%RE melt. Injection casting experiments of U-10wt.%Zr and U-10wt.%Zr-5wt.%RE fuel slugs have been performed to investigate the feasibility of a reusable crucible of the metal fuel slugs. U–10wt.%Zr and U–10wt.%Zr–5wt.%RE fuel slugs have been soundly fabricated without significant interactions of the graphite crucibles. Thus, the ceramic plasma-spray coatings are thought to be promising candidate coating methods for a reusable graphite crucible to fabricate metal fuel slugs.

  5. Numerical investigation of temporal changes in volcanic deformation caused by a gas slug ascent in the conduit

    Science.gov (United States)

    Kawaguchi, Ryohei; Nishimura, Takeshi

    2015-09-01

    Strombolian type eruptions are considered to be generated by a sudden release of a large gas slug that migrates upward in the conduit filled with a low viscous basaltic magma. We examine volcano deformations caused by such a gas slug to understand the Strombolian eruption mechanism from geodetic observation data. We model spatio-temporal pressure changes in the conduit by using a gas slug ascent model presented by James et al. (2008). As a gas slug ascends in the conduit, its volume expands because of depressurization. Hence, the magma head lifts up in the conduit and the upper part of the conduit wall is stressed. In the conduit, magma pressure increases with depth according to the bulk density of magma: the gas slug part with a low density is characterized by a small pressure gradient, while the other parts, consisting of melt, are characterized by a large pressure gradient. We numerically calculate volcano deformations caused by the spatio-temporal changes of magma pressure predicted from the basic equations representing gas slug locations in the conduit. Simulation results show that the radial and vertical displacements and tilt changes indicate volcano deformations that represent the inflation originating from the stress increase at the upper part of conduit. As the gas slug reaches the shallow part of conduit, the rate of inflation observed in the radial displacement decreases, the vertical displacement starts to move downward, and the tilt turns to show down toward the crater. These deflation signals are caused by a moving deflation source in the conduit that is formed beneath the gas slug. Since these predicted features are not observed in the tilt records associated with explosions at Stromboli volcano (Genco and Ripepe, 2010), it is necessary to modify the gas slug ascent model or to introduce other mechanisms to better understand the magma dynamics of Strombolian eruption.

  6. Correlation between Slug transcription factor and miR-221 in MDA-MB-231 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Lambertini Elisabetta

    2012-10-01

    Full Text Available Abstract Background Breast cancer and its metastatic progression is mainly directed by epithelial to mesenchymal transition (EMT, a phenomenon supported by specific transcription factors and miRNAs. Methods In order to investigate a possible correlation between Slug transcription factor and miR-221, we performed Slug gene silencing in MDA-MB-231 breast cancer cells and evaluated the expression of genes involved in supporting the breast cancer phenotype, using qRT-PCR and Western blot analysis. Chromatin immunoprecipitation and wound healing assays were employed to determine a functional link between these two molecules. Results We showed that Slug silencing significantly decreased the level of miR-221 and vimentin, reactivated Estrogen Receptor α and increased E-cadherin and TRPS1 expression. We demonstrated that miR-221 is a Slug target gene, and identified a specific region of miR-221 promoter that is transcriptionally active and binds the transcription factor Slug “in vivo”. In addition, we showed that in Slug-silenced cells, wich retained residual miR-221 (about 38%, cell migration was strongly inhibited. Cell migration was inhibited, but to a less degree, following complete knockdown of miR-221 expression by transfection with antagomiR-221. Conclusions We report for the first time evidence of a correlation between Slug transcription factor and miR-221 in breast cancer cells. These studies suggest that miR-221 expression is, in part, dependent on Slug in breast cancer cells, and that Slug plays a more important role than miR-221 in cell migration and invasion.

  7. The association between bubble trails and folia: a morphological and sedimentary indicator of hypogenic speleogenesis by degassing, example from Adaouste Cave (Provence, France

    Directory of Open Access Journals (Sweden)

    Audra Ph.

    2009-07-01

    Full Text Available Bubble trails are subaqueous features in carbonate caves, which are made by the corrosion of ascending carbon dioxide bubbles.Folia are calcite deposits resembling inverted rimstone dams in saturated pools. Based on morphological studies in Adaouste Cave(Provence, France and on studies elsewhere in the world, we propose a new genetic model for folia, close to the model of Green(1991. The association of bubble trails and folia, occurring on overhanging walls, is interpreted to be an indicator of hypogenicdegassing occurring just below the water table. The association

  8. Learning control for riser-slug elimination and production-rate optimization for an offshore oil and gas production process

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2014-01-01

    Slugging flow in the offshore oil & gas production attracts lot of attention due to it's limitation of production rate, periodic overload on processing facilities, and even direct cause of emergency shutdown. This work aims at two correlated objectives: (i) Preventing slugging flow; and meanwhile......, (ii) maximizing the production rate at the riser of an offshore production platform, by manipulating a topside choke valve through a learning switching model-free PID controller. The results show good steady-state performance, though a long settling time due to the unknown reference for no slugging...

  9. The Housing Bubble Fact Sheet

    OpenAIRE

    Dean Baker

    2005-01-01

    This paper explains the basic facts about the current housing market. It lays out the evidence that the rise in housing prices constitutes a housing bubble - and explains what can be expected when it inevitably collapses.

  10. Bubble bean bags in shampoo

    CERN Document Server

    Kundu, Anup; Das, Gargi; Harikrishnan, G

    2011-01-01

    In these fluid dynamics videos, we, for the first time, show various interactions of a 'Taylor bubble' with their smaller and differently, shaped counterparts, in a shear thinning, non-Newtonian fluid, confined in a narrow channel.

  11. Inverting the central limit theorem

    CERN Document Server

    Navascues, Miguel; Villanueva, Ignacio

    2011-01-01

    The central limit theorem states that the sum of N independently distributed n-tuples of real variables (subject to appropriate normalization) tends to a multivariate gaussian distribution for large N. Here we propose to invert this argument: given a set of n correlated gaussian variables, we try to infer information about the structure of the discrete microscopic probability distributions whose convolution generated such a macroscopic behavior. The techniques developed along the article are applied to prove that the classical description of certain macroscopic optical experiments is infinitely more complex than the quantum one.

  12. Mechanisms of single bubble cleaning.

    Science.gov (United States)

    Reuter, Fabian; Mettin, Robert

    2016-03-01

    The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8substrate and remove particles without significant contact of the gas phase. (II) For small distances, γsubstrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by the jet flow and the flow induced by the bubble wall oscillation. Furthermore, the observations reveal that the extent of direct bubble gas phase contact to the solid is partially smaller than the

  13. Multilevel Inverters for Electric Vehicle Applications

    Energy Technology Data Exchange (ETDEWEB)

    Habetler, T.G.; Peng, F.Z.; Tolbert, L.M.

    1998-10-22

    This paper presents multilevel inverters as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. Diode-clamped inverters and cascaded H-bridge inverters, (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference (EMI) and common-mode voltage; and (3) make an EV more accessible/safer and open wiring possible for most of an EV'S power system. This paper explores the benefits and discusses control schemes of the cascade inverter for use as an EV motor drive or a parallel HEV drive and the diode-clamped inverter as a series HEV motor drive. Analytical, simulated, and experimental results show the superiority of these multilevel inverters for this new niche.

  14. Cascaded trans-z-source inverters

    DEFF Research Database (Denmark)

    Li, Ding; Loh, Poh Chiang; Zhu, Miao;

    2011-01-01

    Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...... the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental...

  15. Selection of Carrier Waveforms for PWM Inverter

    Institute of Scientific and Technical Information of China (English)

    陈国呈; 屈克庆; 许春雨; 孙承波

    2003-01-01

    In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonancetrigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.

  16. Doughnut-shaped soap bubbles

    CERN Document Server

    Preve, Deison

    2015-01-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume $V$ and with a fixed equatorial perimeter $L$. It is well known that the sphere is the solution for $V=L^3/6\\pi^2$, and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for $V<\\alpha L^3/6\\pi^2$, with $\\alpha\\approx 0.21$, such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtainin...

  17. Temperature measurements in cavitation bubbles

    Science.gov (United States)

    Coutier-Delgosha, Olivier

    2016-11-01

    Cavitation is usually a nearly isothermal process in the liquid phase, but in some specific flow conditions like hot water or cryogenic fluids, significant temperature variations are detected. In addition, a large temperature increase happens inside the cavitation bubbles at the very end of their collapse, due to the fast compression of the gas at the bubble core, which is almost adiabatic. This process is of primary interest in various biomedical and pharmaceutical applications, where the mechanisms of bubble collapse plays a major role. To investigate the amplitude and the spatial distribution of these temperature variations inside and outside the cavitation bubbles, a system based on cold wires has been developed. They have been tested in a configuration of a single bubble obtained by submitting a small air bubble to a large amplitude pressure wave. Some promising results have been obtained after the initial validation tests. This work is funded by the Office of Naval Research Global under Grant N62909-16-1-2116, Dr. Salahuddin Ahmed & Ki-Han Kim program managers.

  18. The effects of surfactants on the lateral migration of bubbles and the bubble clustering phenomenon in a bubbly channel flow

    Science.gov (United States)

    Takagi, Shu; Ogasawara, Toshiyuki; Matsumoto, Yoichiro

    2004-11-01

    The behaviors of bubbles in an upward channel flow are experimentally investigated. Two kinds of surfactant, 3-pentanol and Triton X-100 are added in the bubbly flow. Addition of surfactant prevents the bubble coalescence and mono-dispersed 1mm spherical bubbles were obtained, although these surfactants do not modify the single-phase turbulence statistics. At the condition of high Reynolds number (Re=8200) with 20-60ppm 3-Pentanol, bubbles migrated towards the wall. These bubbles highly accumulated near the wall and formed crescent like shaped horizontal bubble clusters of 10-40mm length. On the other hand, bubble clusters did not appear in the 2ppm Triton-X100 aqueous solution. By the addition of the small amount of Triton-X100, bubble coalescences were also preventable and the bubble size and its distribution became almost the same as in the case of 60ppm 3-Pentanol aqueous solution. However, the tendency of the lateral migration of bubbles towards the wall weakened and the bubbles did not accumulated near the wall. And this is the main reason of the disapperance of bubble cluster. We discuss this phenomenon, related to the lift force acting on bubbles and particles.

  19. Measuring online social bubbles

    Directory of Open Access Journals (Sweden)

    Dimitar Nikolov

    2015-12-01

    Full Text Available Social media have become a prevalent channel to access information, spread ideas, and influence opinions. However, it has been suggested that social and algorithmic filtering may cause exposure to less diverse points of view. Here we quantitatively measure this kind of social bias at the collective level by mining a massive datasets of web clicks. Our analysis shows that collectively, people access information from a significantly narrower spectrum of sources through social media and email, compared to a search baseline. The significance of this finding for individual exposure is revealed by investigating the relationship between the diversity of information sources experienced by users at both the collective and individual levels in two datasets where individual users can be analyzed—Twitter posts and search logs. There is a strong correlation between collective and individual diversity, supporting the notion that when we use social media we find ourselves inside “social bubbles.” Our results could lead to a deeper understanding of how technology biases our exposure to new information.

  20. FEASTING BLACK HOLE BLOWS BUBBLES

    Science.gov (United States)

    2002-01-01

    A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth. These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box. These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event. The bubble is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of gas. The brighter bubble is 800 light-years tall and 800 light-years across. The observations are being presented June 5 at the American Astronomical Society meeting in Rochester, N.Y. Both pictures were taken March 24, 1999 with the Wide Field and Planetary Camera 2. False colors were used to enhance the details of the bubbles. The red regions in the picture denote the hot gas

  1. Toward A 3-D Picture of Hydraulic Conductivity With Multilevel Slug Tests

    Science.gov (United States)

    McElwee, C. D.; McElwee, C. D.; Ross, H. C.

    2001-12-01

    The GEMS (Geohydrologic Experiment and Monitoring Site) field area has been established (in the Kansas River valley near Lawrence, Kansas) for a variety of reasons relating to research and teaching in hydrogeology at the University of Kansas. Over 70 wells have been installed for various purposes. The site overlies an alluvial aquifer with a total thickness of about 70 feet. The water table is typically about 20 feet below the surface, giving a total saturated thickness of about 50 feet. The upper part of the aquifer is finer material consisting of silt and clay. Typically, the lower 35 feet of the aquifer is sand and gravel. A number of wells through out the site are fully screened through the sand and gravel aquifer. Some of these fully screened wells are larger diameters; however, most wells are constructed of 2 inch PVC casing. Slug tests are widely used in hydrogeology to measure hydraulic conductivity. Over the last several years we have been conducting research to improve the slug test method. We have previously reported the detailed structure of hydraulic conductivity that can be seen in a 5 inch well (McElwee and Zemansky, EOS, v. 80, no. 46, p. F397, 1999) at this site, using multilevel slug tests. The existing 2 inch, fully screened wells are spread out over the site and offer the opportunity for developing a 3-D picture of the hydraulic conductivity distribution. However, it is difficult to develop a system that allows multilevel slug tests to be done accurately and efficiently in a 2 inch well. This is especially true in regions of very high hydraulic conductivity, where the water velocity in the casing will be relatively high. The resistance caused by frictional forces in the equipment must be minimized and a model taking account of these forces must be used. We have developed a system (equipment, software, and technique) for performing multilevel slug tests in 2 inch wells. Some equipment configurations work better than others. The data that we have

  2. A mini slug test method for determination of a local hydraulic conductivity of an unconfined sandy aquifer

    DEFF Research Database (Denmark)

    Hinsby, Klaus; Bjerg, Poul Løgstrup; Andersen, Lars J.;

    1992-01-01

    from level to level and thereby establish vertical profiles of the hydraulic conductivity. The head data from the test well are recorded with a 10 mm pressure transducer, and the initial head difference required is established by a small vacuum pump. The method described has provided 274 spatially......A new and efficient mini slug test method for the determination of local hydraulic conductivities in unconfined sandy aquifers is developed. The slug test is performed in a small-diameter (1 inch) driven well with a 0.25 m screen just above the drive point. The screened drive point can be driven...... distributed measurements of a local hydraulic conductivity at a tracer test site at Vejen, Denmark. The mini slug test results calculated by a modified Dax slug test analysing method, applying the elastic storativity in the Dax equations instead of the specific yield, are in good accordance with the results...

  3. Thirteen-level inverter for photovoltaic applications

    Directory of Open Access Journals (Sweden)

    Lasanthika Dissawa

    2016-03-01

    Full Text Available With the recent cost reduction and efficiency improvement of solar photovoltaic (PV cells, there is a growing interest towards PV systems in different applications. One promising application is solar PV powered electric vehicles. When they are moving on roads, the whole or some parts of the PV system might be shaded by trees, high buildings, etc.; which result in non-uniform insolation conditions. As a remedial measure, this paper presents a development of a cascaded multi-level inverter based PV system for electric vehicle applications. The basic architecture and switching of the converter switches are described. A laboratory prototype of the proposed architecture was implemented using MOSFETs and harmonic performance under different shading conditions was evaluated. It was found, that under shaded conditions, the 3rd harmonic content can increase and that it depends on the number of modules shaded and the loading condition. The shading performance, losses and power utilization of the cascaded multi-level inverter are compared with that of a conventional Pulse Width Modulated (PWM inverter architecture. The proposed inverter shows better immunity for shading than a PWM inverter. Furthermore, it was found that the switching losses of the proposed inverter are one 10th to one 20th of that of a PWM inverter. Additionally, by properly selecting the switches, it is also possible to reduce the conduction losses compared to that of a PWM inverter. Even though the power utilization is compromised at full insolation, the power utilization performance of the proposed inverter is superior under shading conditions, thus ideally suited for the selected application. As the modular nature of the proposed inverter allows cascading of more H-bridges with fewer cells, the harmonic, shading, loss and power utilization performance of the proposed inverter can be enhanced with more number of steps in the output waveform.

  4. Combination of rapamycin, CI-1040, and 17-AAG inhibits metastatic capacity of prostate cancer via Slug inhibition.

    Directory of Open Access Journals (Sweden)

    Guanxiong Ding

    Full Text Available Though prostate cancer (PCa has slow progression, the hormone refractory (HRCP and metastatic entities are substantially lethal and lack effective treatments. Transcription factor Slug is critical in regulating metastases of various tumors including PCa. Here we studied targeted therapy against Slug using combination of 3 drugs targeting 3 pathways respectively converging via Slug and further regulating PCa metastasis. Using in vitro assays we confirmed that Slug up-regulation incurred inhibition of E-cadherin that was anti-metastatic, and inhibited Bim-regulated cell apoptosis in PCa. Upstream PTEN/Akt, mTOR, Erk, and AR/Hsp90 pathways were responsible for Slug up-regulation and each of these could be targeted by rapamycin, CI-1040, and 17-AAG respectively. In 4 PCa cell lines with different traits in terms of PTEN loss and androgen sensitivity we tested the efficacy of mono- and combined therapy with the drugs. We found that metastatic capacity of the cells was maximally inhibited only when all 3 drugs were combined, due to the crosstalk between the pathways. 17-AAG decreases Slug expression via blockade of HSP90-dependent AR stability. Combination of rapamycin and CI-1040 diminishes invasiveness more potently in PCa cells that are androgen insensitive and with PTEN loss. Slug inhibited Bim-mediated apoptosis that could be rescued by mTOR/Erk/HSP90 inhibitors. Using mouse models for circulating PCa DNA quantification, we found that combination of mTOR/Erk/HSP90 inhibitors reduced circulating PCa cells in vivo significantly more potently than combination of 2 or monotherapy. Conclusively, combination of mTOR/Erk/Hsp90 inhibits metastatic capacity of prostate cancer via Slug inhibition.

  5. Slug signaling is up-regulated by CCL21/CCR7 [corrected] to induce EMT in human chondrosarcoma.

    Science.gov (United States)

    Li, Guosong; Yang, Yanjun; Xu, Siliang; Ma, Lifeng; He, Mingtang; Zhang, Ziqing

    2015-02-01

    In recent decades, the CXC chemokine receptor 7 (CCR7) [corrected] and its ligand CCL21 have been extensively reported to be associated with tumorigenesis. Meanwhile, Slug signaling induces the epithelial-mesenchymal transition (EMT) process in chondrosarcoma development. In the present study, we explored the functions of CCL21/CCR7 [corrected] in Slug-mediated EMT in the chondrosarcoma. We analyzed protein expression of CCR7 [corrected] and Slug in human chondrosarcoma samples. Effects of CCR7 [corrected] on chondrosarcoma cells were assessed by in vitro assays. Additionally, CCR7 [corrected] pathways were further investigated by pharmacological and genetic approaches. We found that the altered CCR7 [corrected] (81.7 %) and Slug (85.0 %) expression in human chondrosarcoma tissues were significantly associated with grade, recurrence, and 5-year overall survival. According to in vitro assays, CCL21 stimulation induced the expression of phosph-ERK, phosph-AKT, Slug and N-cadherin in SW1353 cells, while the expression of E-cadherin was down-regulated. Furthermore, Slug signaling modulated E- to N-cadherin switch, which was influenced by the kinase inhibitor PD98059 and LY294002. In addition, the genetic silencing of Slug inhibited the capacity of migration and invasion of SW1353 cells. In conclusion, CCL21/CCR7 [corrected] pathway activates ERK and PI3K/AKT signallings to up-regulate Slug pathway, leading to the occurrence of EMT process in human chondrosarcoma. This study lays a new foundation for molecule-targeted therapy of human chondrosarcoma.

  6. Bubble-sort图和Modified Bubble-sort图的自同构群%Automorphism Groups of Bubble-sort Graphs and Modified Bubble-sort Graphs

    Institute of Scientific and Technical Information of China (English)

    张昭; 黄琼湘

    2005-01-01

    Bubble-sort graphs and modified bubble-sort graphs are two classes of Cayley graphs which are widely studied for their application in network construction. In this paper, we determine the full automorphism groups of bubble-sort graphs and modified bubble-sort graphs.%Bubble-Sort图和Modified Bubble-Sort图是两类特殊的Cayley图,由于其在网络构建中的应用而受到广泛关注.本文完全确定了这两类图的自同构群.

  7. Spherical Solutions of an Underwater Explosion Bubble

    Directory of Open Access Journals (Sweden)

    Andrew B. Wardlaw

    1998-01-01

    Full Text Available The evolution of the 1D explosion bubble flow field out to the first bubble minimum is examined in detail using four different models. The most detailed is based on the Euler equations and accounts for the internal bubble fluid motion, while the simplest links a potential water solution to a stationary, Isentropic bubble model. Comparison of the different models with experimental data provides insight into the influence of compressibility and internal bubble dynamics on the behavior of the explosion bubble.

  8. Bubble-bubble interaction: A potential source of cavitation noise

    CERN Document Server

    Ida, Masato

    2009-01-01

    The interaction between microbubbles through pressure pulses has been studied to show that it can be a source of cavitation noise. A recent report demonstrated that the acoustic noise generated by a shrimp originates from the collapse of a cavitation bubble produced when the shrimp closes its snapper claw. The recorded acoustic signal contains a broadband noise that consists of positive and negative pulses, but a theoretical model for single bubbles fails to reproduce the negative ones. Using a nonlinear multibubble model we have shown here that the negative pulses can be explained by considering the interaction of microbubbles formed after the cavitation bubble has collapsed and fragmented: Positive pulses produced at the collapse of the microbubbles hit and impulsively compress neighboring microbubbles to generate reflected pulses whose amplitudes are negative. Discussing the details of the noise generation process, we have found that no negative pulses are generated if the internal pressure of the reflecti...

  9. Radiotherapy for inverted papilloma: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Levendag, P.C.; Annyas, A.A.; Escajadillo, J.R.; Elema, J.D. (Rijksuniversiteit Groningen (Netherlands). Academisch Ziekenhuis)

    1984-06-01

    Inverted papilloma is an infrequent tumour of the nasal cavity and paranasal sinuses associated with controversy. The incidence of carcinoma in situ associated with inverted papilloma, has not been very well documented until now. Therefore the authors present a case report characterized by an aggressive clinical behaviour, treated by extensive surgery and ultimately controlled by radiotherapy.

  10. Radiotherapy for inverted papilloma: a case report.

    Science.gov (United States)

    Levendag, P C; Annyas, A A; Escajadillo, J R; Elema, J D

    1984-06-01

    Inverted papilloma is an infrequent tumour of the nasal cavity and paranasal sinuses associated with controversy. The incidence of carcinoma in situ associated with inverted papilloma, has not been very well documented until now. Therefore, we present a case report characterized by an aggressive clinical behaviour, treated by extensive surgery and ultimately controlled by radiotherapy.

  11. Sinonasal inverted papilloma: From diagnosis to treatment.

    Science.gov (United States)

    Lisan, Q; Laccourreye, O; Bonfils, P

    2016-11-01

    Inverted papilloma is a rare sinonasal tumor that mainly occurs in adults during the 5th decade. Three characteristics make this tumor very different from other sinonasal tumors: a relatively strong potential for local destruction, high rate of recurrence, and a risk of carcinomatous evolution. Etiology remains little understood, but an association with human papilloma virus has been reported in up to 40% of cases, raising the suspicions of implication in the pathogenesis of inverted papilloma. Treatment of choice is surgery, by endonasal endoscopic or external approach, depending on extension and tumoral characteristics. Follow-up is critical, to diagnose local relapse, which is often early but may also be late. The seriousness of this pathology lies in its association with carcinoma, which may be diagnosed at the outset or at recurrence during follow-up. It is important to diagnose recurrence to enable early treatment, especially in case of associated carcinoma or malignancy. A comprehensive review of the international literature was performed on PubMed and Embase, using the following search-terms: "sinonasal" [All Fields] AND ("papilloma, inverted" [MeSH Terms] OR ("papilloma" [All Fields] AND "inverted" [All Fields]) OR "inverted papilloma" [All Fields] OR ("inverted" [All Fields] AND "papilloma" [All Fields])). We reviewed all articles referring to sinonasal inverted papilloma published up to January 2015. The present article updates the state of knowledge regarding sinonasal inverted papilloma. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. On Invertible Sampling and Adaptive Security

    DEFF Research Database (Denmark)

    Ishai, Yuval; Kumarasubramanian, Abishek; Orlandi, Claudio

    2011-01-01

    sampling algorithm A, obtain another sampling algorithm B such that the output of B is computationally indistinguishable from the output of A, but B can be efficiently inverted (even if A cannot). This invertible sampling problem is independently motivated by other cryptographic applications. We show...

  13. Circuit controls transients in SCR inverters

    Science.gov (United States)

    Moore, E. T.; Wilson, T. G.

    1964-01-01

    Elimination of starting difficulties in SCR inverters is accomplished by the addition of two taps of the output winding of the inverter. On starting or under transient loads, the two additional taps deliver power through diodes without requiring quenching of SCR currents in excess of normal starting load.

  14. Suppression of Invasion and Metastasis of Triple-Negative Breast Cancer Lines by Pharmacological or Genetic Inhibition of Slug Activity

    Directory of Open Access Journals (Sweden)

    Giovanna Ferrari-Amorotti

    2014-12-01

    Full Text Available Most triple-negative breast cancers (TNBCs exhibit gene expression patterns associated with epithelial-to-mesenchymal transition (EMT, a feature that correlates with a propensity for metastatic spread. Overexpression of the EMT regulator Slug is detected in basal and mesenchymal-type TNBCs and is associated with reduced E-cadherin expression and aggressive disease. The effects of Slug depend, in part, on the interaction of its N-terminal SNAG repressor domain with the chromatin-modifying protein lysine demethylase 1 (LSD1; thus, we investigated whether tranylcypromine [also known as trans-2-phenylcyclopropylamine hydrochloride (PCPA or Parnate], an inhibitor of LSD1 that blocks its interaction with Slug, suppresses the migration, invasion, and metastatic spread of TNBC cell lines. We show here that PCPA treatment induces the expression of E-cadherin and other epithelial markers and markedly suppresses migration and invasion of TNBC cell lines MDA-MB-231 and BT-549. These effects were phenocopied by Slug or LSD1 silencing. In two models of orthotopic breast cancer, PCPA treatment reduced local tumor growth and the number of lung metastases. In mice injected directly in the blood circulation with MDA-MB-231 cells, PCPA treatment or Slug silencing markedly inhibited bone metastases but had no effect on lung infiltration. Thus, blocking Slug activity may suppress the metastatic spread of TNBC and, perhaps, specifically inhibit homing/colonization to the bone.

  15. Differential expression of the epithelial mesenchymal transition factors Snail, Slug, Twist, TGF-β, and E-cadherin in ameloblastoma.

    Science.gov (United States)

    Kurioka, Kagami; Wato, Masahiro; Iseki, Tomio; Tanaka, Akio; Morita, Shosuke

    2017-06-01

    Epithelial mesenchymal transition (EMT), the transition of epithelial cells into motile mesenchymal cells, plays an important role in embryogenesis, cancer invasion, and metastasis. Ameloblastomas are common epithelial odontogenic tumors, occurring exclusively in the mandible with locally invasive growth. Thirty-seven ameloblastoma cases were evaluated for the involvement of EMT by immunohistochemical staining and western blotting using antibodies against Slug, Snail, Twist, TGF-β, and E-cadherin. Double immunostaining was also performed. Slug and TGF-β were expressed in the nuclei of peripheral and stellate reticulum cells of ameloblastoma nests. Twenty cases of Snail, 36 of Slug, 8 of Twist, and 19 of TGF-β showed strong expression in tumor cells in follicular and plexiform patterns. Expression of Slug and TGF-β increased in regions where the expression of E-cadherin was reduced. EMT was found to be associated with the local invasive growth of ameloblastoma. These data suggest that reduced expression of E-cadherin and over-expression of Slug, Snail, and TGF-β induce EMT. Given that ameloblastomas are characterized by local invasiveness, EMT might be related to their development. Thus, strong expression of Slug and TGF-β and reduced expression of E-cadherin might be related to the local invasiveness of ameloblastoma.

  16. A criterion for the onset of slugging in horizontal stratified air-water countercurrent flow

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Moon-Hyun; Lee, Byung-Ryung; Kim, Yang-Seok [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)] [and others

    1995-09-01

    This paper presents an experimental and theoretical investigation of wave height and transition criterion from wavy to slug flow in horizontal air-water countercurrent stratified flow conditions. A theoretical formula for the wave height in a stratified wavy flow regime has been developed using the concept of total energy balance over a wave crest to consider the shear stress acting on the interface of two fluids. From the limiting condition of the formula for the wave height, a necessary criterion for transition from a stratified wavy flow to a slug flow has been derived. A series of experiments have been conducted changing the non-dimensional water depth and the flow rates of air in a horizontal pipe and a duct. Comparisons between the measured data and the predictions of the present theory show that the agreement is within {plus_minus}8%.

  17. Gas Slug Microfluidics: A Unique Tool for Ultrafast, Highly Controlled Growth of Iron Oxide Nanostructures.

    Science.gov (United States)

    Larrea, Ane; Sebastian, Victor; Ibarra, Alfonso; Arruebo, Manuel; Santamaria, Jesus

    2015-06-23

    The use of nanomaterials in real life applications is often hampered by our inability to produce them in large quantities while preserving their desired properties in terms of size, shape, and crystalline phase. Here we present a novel continuous method to synthesize nanostructures with an unprecedented degree of control regarding their properties. In particular, the excellent properties of microreactors for chemical synthesis are enhanced by the introduction of gas slugs of tailored composition. Slug dynamics accelerate mixing, reduce processing times (from hours in batch processes to minutes or even seconds), and, depending on the gas atmosphere used, allows one to accurately control the crystalline phase and shape of the resulting nanostructures. Inert (N2), oxidizing (O2), or reducing (CO, H2) gases were used, leading to different morphologies and crystalline structures in a high yield, highly reproducible fabrication process.

  18. Inverted base pavements: construction and performance

    KAUST Repository

    Papadopoulos, Efthymios

    2017-05-11

    Inverted base pavements involve a well-compacted granular aggregate base built between a thin asphalt concrete layer and a cement-treated base. Inverted base pavements can be constructed using conventional equipment and procedures but require proper quality control. This study reviews the extensive South African experience and case histories in the USA. Accumulating evidence suggests that inverted base pavements are a viable alternative and can outperform conventional pavements at a lower cost. Inverted base pavements rely on the complementary interaction between layers. The cement-treated base provides a stiff foundation for efficient compaction and constrains the deformation of the stress-sensitive granular aggregate base. The thin asphalt surface layer deforms as a membrane and develops low tensile stress. Additional large-scale field tests should be conducted to assess the performance of inverted base pavement designs in a wide range of conditions relevant to the USA.

  19. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim

    2002-01-01

    In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...... by a standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations...

  20. Leakage current measurement in transformerless PV inverters

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo

    2012-01-01

    to be used in commercial PV inverters for the measurement of leakage and fault ground currents. The German VDE0126–1–1 standard gives the limit for fault and leakage ground currents and all grid connected PV inverters have to comply with these limits and disconnect from the grid in case of a fault.......Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...

  1. Quantum Bubble Nucleation beyond WKB Resummation of Vacuum Bubble Diagrams

    CERN Document Server

    Suzuki, H; Suzuki, Hiroshi; Yasuta, Hirofumi

    1998-01-01

    On the basis of Borel resummation, we propose a systematical improvement of bounce calculus of quantum bubble nucleation rates. We study a metastable super-renormalizable field theory, D dimensional O(N) symmetric \\phi^4 model (D<4) with an attractive interaction. The validity of our proposal is tested in D=1 (quantum mechanics) by using the perturbation series of ground state energy to high orders. We also present a result in D=2 based on an explicit calculation of vacuum bubble diagrams to five loop orders.

  2. Gas Slug Microfluidics: A Unique Tool for Ultrafast, Highly Controlled Growth of Iron Oxide Nanostructures

    OpenAIRE

    Larrea, Ane; Sebastian, Victor; Ibarra, Alfonso; Arruebo, Manuel; Santamaria, Jesus

    2015-01-01

    The use of nanomaterials in real life applications is often hampered by our inability to produce them in large quantities while preserving their desired properties in terms of size, shape, and crystalline phase. Here we present a novel continuous method to synthesize nanostructures with an unprecedented degree of control regarding their properties. In particular, the excellent properties of microreactors for chemical synthesis are enhanced by the introduction of gas slugs of tailored composit...

  3. A field proof-of-concept of tomographic slug tests in an anisotropic littoral aquifer

    Science.gov (United States)

    Paradis, Daniel; Gloaguen, Erwan; Lefebvre, René; Giroux, Bernard

    2016-05-01

    Hydraulic tomography is increasingly recognized as a characterization approach that can image pathways or barriers to flow as well as their connectivity. In this study, we assess the performance of a transient analysis of tomographic slug test head data in estimating heterogeneity in horizontal hydraulic conductivity (Kh), hydraulic conductivity anisotropy (the ratio between vertical and horizontal hydraulic conductivity - Kv/Kh) and specific storage (Ss) under actual field conditions. The tomographic experiment was carried out between two wells in a moderately heterogeneous and highly anisotropic silt and sand littoral aquifer. In this field proof-of-concept, the inversion of the two-dimensional (2D) head dataset was computed with a 2D radial flow algorithm that considers Kh, Kv/Kh, Ss and wellbore storage effects. This study demonstrated that a transient analysis of tomographic slug tests is able to capture the key features of the littoral environment of the test: the vertical profiles of Kh and Kv are indeed in agreement with those from other field and laboratory tests, and Ss values exhibit physically plausible profiles. Furthermore, the simulation of independent inter-well hydraulic tests (slug and pumping tests screened over the entire aquifer) using resolved Kh, Kv/Kh and Ss tomograms produce responses very close to field observations. This study demonstrates that the effects of fine scale heterogeneity that induces K-anisotropy at larger scales can be captured through a transient analysis of tomographic slug tests, which are very difficult to quantify otherwise with conventional hydraulic tests, thus allowing a better representation of properties controlling flow and transport in aquifer systems.

  4. Gastropod seed dispersal: an invasive slug destroys far more seeds in its gut than native gastropods.

    Science.gov (United States)

    Blattmann, Tamara; Boch, Steffen; Türke, Manfred; Knop, Eva

    2013-01-01

    Seed dispersal is one of the most important mechanisms shaping biodiversity, and animals are one of the key dispersal vectors. Animal seed dispersal can directly or indirectly be altered by invasive organisms through the establishment of new or the disruption of existing seed dispersal interactions. So far it is known for a few gastropod species that they ingest and defecate viable plant seeds and consequently act as seed dispersers, referred to as gastropodochory. In a multi-species experiment, consisting of five different plant species and four different gastropod species, we tested with a fully crossed design whether gastropodochory is a general mechanism across native gastropod species, and whether it is altered by the invasive alien slug species Arion lusitanicus. Specifically, we hypothesized that a) native gastropod species consume the seeds from all tested plant species in equal numbers (have no preference), b) the voracious invasive alien slug A. lusitanicus--similarly to its herbivore behaviour--consumes a higher amount of seeds than native gastropods, and that c) seed viability is equal among different gastropod species after gut passage. As expected all tested gastropod species consumed all tested plant species. Against our expectation there was a difference in the amount of consumed seeds, with the largest and native mollusk Helix pomatia consuming most seeds, followed by the invasive slug and the other gastropods. Seed damage and germination rates did not differ after gut passage through different native species, but seed damage was significantly higher after gut passage through the invasive slug A. lusitanicus, and their germination rates were significantly reduced.

  5. Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review

    Directory of Open Access Journals (Sweden)

    Rahul Antony

    2014-10-01

    Full Text Available Mass transfer is a basic phenomenon behind many processes like reaction, absorption, extraction etc. Mass transfer plays a significant role in microfluidic systems where the chemical / biological process systems are shrinkened down to a micro scale. Micro reactor system, with its high compatibility and performance, gains a wide interest among the researchers in the recent years. Micro structured reac-tors holds advantages over the conventional types in chemical processes. The significance of micro re-actor not limited to its scalability but to energy efficiency, on-site / on-demand production, reliability, safety, highly controlled outputs, etc. Liquid-liquid two phase reaction in a microreactor system is highly demandable when both reactants are liquids or when air medium cannot be suitable. This arti-cle overviews various liquid-liquid flow regimes in a microchannel. Discussions on the hydrodynamics of flow in micro scale are made. Considering the importance of mass transfer in liquid-liquid systems and the advantage of slug regime over other regimes, the article focuses especially on the mass trans-fer between two liquid phases in slug flow and the details of experimental studies carried out in this area. The advantages of slug flow over other flow regimes in micro structured reactor applications are showcased. © 2014 BCREC UNDIP. All rights reservedReceived: 31st May 2014; Revised: 6th August 2014; Accepted: 14th August 2014How to Cite: Antony, R., Giri Nandagopal, M.S., Sreekumar, N., Rangabhashiyam, S., Selvaraju, N. (2014. Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review. Bulletin of Chemical Reaction Engineering & Catalysis,9(3: 207-223. (doi:10.9767/bcrec.9.3.6977.207-223Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6977.207-223

  6. EMT transcription factors snail and slug directly contribute to cisplatin resistance in ovarian cancer

    Directory of Open Access Journals (Sweden)

    Haslehurst Alexandria M

    2012-03-01

    Full Text Available Abstract Background The epithelial to mesenchymal transition (EMT is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers. Methods Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays. Results Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects. Conclusions This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for

  7. Fluidization behavior in a circulating slugging fluidized bed reactor. Part II: Plug characteristics

    NARCIS (Netherlands)

    Putten, van I.C.; Sint Annaland, van M.; Weickert, G.

    2007-01-01

    In the transporting square nosed slugging fluidization regime (0.4 < u0 < 1.0m/s) a bed of polyethylene powder with a low density (ρ = 900/kg/m3) and a large particle size distribution (70 < dρ < 1600µm) was operated in two circulating fluidized bed systems (riser diameters 0.044 and 0.105 m). A rel

  8. Modulation of the Proliferation and Metastasis of Human Breast Tumor Cells by SLUG (IDEA)

    Science.gov (United States)

    2007-04-01

    Biochemical and Biophysical Research Communications 353...terminal zinc-finger domains and then 662 C.K. Bailey et al. / Biochemical and Biophysical Research Communications 353 (2007) 661–664recruits either CtBP1...control); (2) blank vectors (negative control); (3 and 4) pGBKT7-hSLUG/pGADT7- hCtBP1. C.K. Bailey et al. / Biochemical and Biophysical Research Communications

  9. EMT transcription factors snail and slug directly contribute to cisplatin resistance in ovarian cancer.

    Science.gov (United States)

    Haslehurst, Alexandria M; Koti, Madhuri; Dharsee, Moyez; Nuin, Paulo; Evans, Ken; Geraci, Joseph; Childs, Timothy; Chen, Jian; Li, Jieran; Weberpals, Johanne; Davey, Scott; Squire, Jeremy; Park, Paul C; Feilotter, Harriet

    2012-03-19

    The epithelial to mesenchymal transition (EMT) is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers. Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays. Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects. This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance.

  10. Gas6/Axl pathway promotes tumor invasion through the transcriptional activation of Slug in hepatocellular carcinoma.

    Science.gov (United States)

    Lee, Hsin-Jung; Jeng, Yung-Ming; Chen, Yu-Ling; Chung, Ling; Yuan, Ray-Hwang

    2014-04-01

    Hepatocellular carcinoma (HCC) is one of the most common fatal cancers worldwide. Other than the sorafenib treatment, no effective systemic therapy has been available thus far. Most targets in molecularly targeted therapy for cancer are receptor tyrosine kinases (RTKs). Therefore, identifying activated RTKs in HCC is critical for developing new molecularly targeted therapies. Using a phospho-RTK array, we found that Axl is one of the most frequently activated RTKs in liver cancer cell lines. The knockdown of Axl by RNA interference significantly reduced cell migration and invasion in the HCC cell lines HA22T and Mahlavu. Stimulation of HCC cell lines by Axl ligand growth arrest-specific 6 (Gas6) enhanced cell migration and invasion. The Gas6/Axl pathway enhanced the expression of the epithelial-mesenchymal transition-inducing transcription factor Slug, which is essential for the invasion-promoting activity of Axl. Treating HCC cells with the Axl inhibitor bosutinib suppressed Slug expression and decreased the invasiveness of HCC cell lines. These findings indicate that Gas6/Axl regulates tumor invasion through the transcriptional activation of Slug.

  11. Differential expression of transcription factors Snail, Slug, SIP1, and Twist in ameloblastoma.

    Science.gov (United States)

    Siar, Chong Huat; Ng, Kok Han

    2014-01-01

    Epithelial-to-mesenchymal transition (EMT) via the mechanism of transcription repression is a crucial process for the induction of invasiveness in many human tumors. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behavior. Twist, an EMT promoter, has been implicated in its invasiveness. The roles of the other transcription factors remain unclarified. Four transcription factors, namely Snail, Slug, SIP1, and Twist, were examined immunohistochemically in 64 ameloblastoma [18 unicystic (UA), 20 solid/multicystic (SA), 4 desmoplastic (DA), and 22 recurrent (RA)]. All four transcription factors were differentially expressed in ameloblastoma [Snail: n = 60/64 (94%); Slug: n = 21/64 (33%); SIP: n = 18/64 (28%); Twist: n = 26/64 (41%)] (P 0.05). Intracellular protein localization was predominantly nuclear for Snail, cytoplasmic>nuclear for Slug and SIP1, and cytoplasmic/nuclear for Twist. Overexpression of Snail in most subsets (UA = 18/18; SMA = 19/20; DA = 4/4; RA = 19/22) compared with the other transcription factors (P ameloblastoma. Overexpression of Snail in most subsets suggests that this molecule is most likely the prototype transcription factor involved in inducing EMT in the ameloblastoma. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  12. Antimicrobial Potential of Bacteria Associated with Marine Sea Slugs from North Sulawesi, Indonesia

    Directory of Open Access Journals (Sweden)

    Nils Böhringer

    2017-06-01

    Full Text Available Nudibranchia, marine soft-bodied organisms, developed, due to the absence of a protective shell, different strategies to protect themselves against putative predators and fouling organisms. One strategy is to use chemical weapons to distract predators, as well as pathogenic microorganisms. Hence, these gastropods take advantage of the incorporation of chemical molecules. Thereby the original source of these natural products varies; it might be the food source, de novo synthesis from the sea slug, or biosynthesis by associated bacteria. These bioactive molecules applied by the slugs can become important drug leads for future medicinal drugs. To test the potential of the associated bacteria, the latter were isolated from their hosts, brought into culture and extracts were prepared and tested for antimicrobial activities. From 49 isolated bacterial strains 35 showed antibiotic activity. The most promising extracts were chosen for further testing against relevant pathogens. In that way three strains showing activity against methicillin resistant Staphylococcus aureus and one strain with activity against enterohemorrhagic Escherichia coli, respectively, were identified. The obtained results indicate that the sea slug associated microbiome is a promising source for bacterial strains, which hold the potential for the biotechnological production of antibiotics.

  13. Design considerations regarding slug ruptures in the intermediate power level reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pearl, W.L.; Pursel, C.A.

    1954-11-01

    The minimum shutdown time, to permit accessibility, for the Intermediate Power Reactor is estimated to be 38 hours. In case the reactor were shutdown following each rupture this long shutdown period would have serious disadvantages. The desirability of being able to make firm power commitments (independent of slug ruptures) has led to a study of the possibility of continuous operation following a rupture. There is evidence to indicate that, at the proposed water temperature, the rate of corrosion of uranium may be so high that at least a major portion of the rupture products may have entered the system before the reactor can be shutdown. A pushout of the affected column would then be a pushout of only those slugs which are still intact and the problem would still remain of removing the rupture products from the system. The first portion of this report is concerned with the rate of corrosion of a slug following rupture and the possible limitations to the principle of non-shutdown operation. These limitations include a flow stoppage by the ruptured can, undue increase in gamma activity, increased corrosion by the rupture products, and adherence of rupture products to the piping. The latter portion of the document is concerned with design considerations of the shielding and water plant so as to eliminate or minimize the effects of the introduction of rupture products into the cooling system. 7 refs., 2 figs.

  14. How safe is Bubble Soccer?

    Science.gov (United States)

    Halani, Sameer H; Riley, Jonathan P; Pradilla, Gustavo; Ahmad, Faiz U

    2016-12-01

    Traumatic neurologic injury in contact sports is a rare but serious consequence for its players. These injuries are most commonly associated with high-impact collisions, for example in football, but are found in a wide variety of sports. In an attempt to minimize these injuries, sports are trying to increase safety by adding protection for participants. Most recently is the seemingly 'safe' sport of Bubble Soccer, which attempts to protect its players with inflatable plastic bubbles. We report a case of a 16-year-old male sustaining a cervical spine burst fracture with incomplete spinal cord injury while playing Bubble Soccer. To our knowledge, this is the first serious neurological injury reported in the sport.

  15. Bursting Bubbles and Bilayers

    Directory of Open Access Journals (Sweden)

    Steven P. Wrenn, Stephen M. Dicker, Eleanor F. Small, Nily R. Dan, Michał Mleczko, Georg Schmitz, Peter A. Lewin

    2012-01-01

    Full Text Available This paper discusses various interactions between ultrasound, phospholipid monolayer-coated gas bubbles, phospholipid bilayer vesicles, and cells. The paper begins with a review of microbubble physics models, developed to describe microbubble dynamic behavior in the presence of ultrasound, and follows this with a discussion of how such models can be used to predict inertial cavitation profiles. Predicted sensitivities of inertial cavitation to changes in the values of membrane properties, including surface tension, surface dilatational viscosity, and area expansion modulus, indicate that area expansion modulus exerts the greatest relative influence on inertial cavitation. Accordingly, the theoretical dependence of area expansion modulus on chemical composition - in particular, poly (ethylene glyclol (PEG - is reviewed, and predictions of inertial cavitation for different PEG molecular weights and compositions are compared with experiment. Noteworthy is the predicted dependence, or lack thereof, of inertial cavitation on PEG molecular weight and mole fraction. Specifically, inertial cavitation is predicted to be independent of PEG molecular weight and mole fraction in the so-called mushroom regime. In the “brush” regime, however, inertial cavitation is predicted to increase with PEG mole fraction but to decrease (to the inverse 3/5 power with PEG molecular weight. While excellent agreement between experiment and theory can be achieved, it is shown that the calculated inertial cavitation profiles depend strongly on the criterion used to predict inertial cavitation. This is followed by a discussion of nesting microbubbles inside the aqueous core of microcapsules and how this significantly increases the inertial cavitation threshold. Nesting thus offers a means for avoiding unwanted inertial cavitation and cell death during imaging and other applications such as sonoporation. A review of putative sonoporation mechanisms is then presented

  16. Fine bubble generator and method

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, P.M.; Koros, R.M.

    1990-10-09

    This patent describes a method of forming fine gaseous bubbles in a liquid ambient. It comprises: forcing a gas through orifices located in the liquid ambient while simultaneously forcing a liquid through liquid orifices at a velocity sufficient to form jet streams of liquid, the liquid orifices being equal in number to the gas orifices and so oriented that each jet stream of liquid intersects the gas forced through each gas orifice and creates sufficient turbulence where the gas and jet stream of liquid intersect, whereby fine gaseous bubbles are formed.

  17. Bubble Content in Air/Hydro System--Part 1:Measurement of Bubble Content

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mechanism of bubble formation in air/hydro systems is investigated. Results presented in this paper include further insight into the mechanism of bubble formation and the measurement of bubble content. The regularity of bubble transport in the system is found, with an idea for a new method for separating gas from oil. The method has been verified experimentally with favorable results.

  18. Bubble Departure Diameter and Bubble Release Frequency Measurement from TAMU Subcooled Flow Boiling Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jun Soo [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-12-01

    The bubble departure diameter and bubble release frequency were obtained through the analysis of TAMU subcooled flow boiling experimental data. The numerous images of bubbles at departure were analyzed for each experimental condition to achieve the reliable statistics of the measured bubble parameters. The results are provided in this report with simple discussion.

  19. Bubble nucleation in an explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den D.M.; Elwenspoek, M.C.

    2008-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a temperature close to the critical temperature in a very short time. At these temperatures spontaneous nucleation takes place. The nucleated bubbles instantly coalesce forming a vapour film followed by rapid growth due to the pressure

  20. Single bubble sonoluminescence and stable cavitation

    Institute of Scientific and Technical Information of China (English)

    CHEN Qian; QIAN Menglu

    2004-01-01

    A single bubble trapped at an antinode of an acoustic standing wave field in water can emit 50ps-140ps light pulses, called "single bubble sonoluminescence" (SBSL). It arouses much interest in physical acoustics because of its highly non-linear characteristics, high concentration of energy, and stable cavitation behavior. In this paper, bubble stability, the dynamic behavior of bubbles, non-invasive measurement of driving acoustic pressure and Mie scattering method are introduced.

  1. Monetary Policy and Controlling Asset Bubbles

    OpenAIRE

    Masaya Sakuragawa

    2015-01-01

    A great concern is whether there is any means of monetary policy that works for the "leaning against the wind" policy in the bubbly economy. This paper explores the scope for monetary policy that can control bubbles within the framework of the stochastic version of overlapping-generations model with rational bubbles. The policy that raises the cost of external finance, could be identified as monetary tightening, represses the boom, but appreciate bubbles. In contrast, an open market operation...

  2. Expansion of Bubbles in Inflationary Universe

    OpenAIRE

    Mohazzab, M.; Jabbari, M. M. Sheikh; Salehi, H.

    1995-01-01

    We show that particle production during the expansion of bubbles of true vacuum in the sea of false vacuum is possible and calculate the resulting rate. As a result the nucleated bubbles cannot expand due to the transfer of false vacuum energy to the created particles inside the bubbles. Therefore all the inflationary models dealing with the nucleation and expansion of the bubbles (including extended inflation) may not be viable.

  3. Expansion of bubbles in inflationary universe

    CERN Document Server

    Mohazzab, M

    1995-01-01

    We show that particle production during the expansion of bubbles of true vacuum in the sea of false vacuum is possible and calculate the resulting rate. As a result the nucleated bubbles cannot expand due to the transfer of false vacuum energy to the created particles inside the bubbles. Therefore all the inflationary models dealing with the nucleation and expansion of the bubbles (including extended inflation) may not be viable.

  4. Radiation Damping at a Bubble Wall

    CERN Document Server

    Lee, J; Lee, C H; Jang, J; Lee, Jae-weon; Kim, Kyungsub; Lee, Chul H.; Jang, Ji-ho

    1999-01-01

    The first order phase transition proceeds via nucleation and growth of true vacuum bubbles. When charged particles collide with the bubble they could radiate electromagnetic wave. We show that, due to an energy loss of the particles by the radiation, the damping pressure acting on the bubble wall depends on the velocity of the wall even in a thermal equilibrium state.

  5. Bubble Formation in Silicon-Quartz Interface

    OpenAIRE

    Kakimoto, K.; EGUCHI, M.; Ozoe, H.

    1997-01-01

    Bubble formation at an interface between silicon melt and a quartz crucible was studied by thermodynamical calculation and visualization of bubble formation using X-ray radiography. A phase diagram of silicon-oxygen (Si-O) system is also calculated from the reported thermodynamical data. Critical temperature and radius of bubble formation at the interface was discussed.

  6. Bubble Size Distributions in Coastal Seas

    NARCIS (Netherlands)

    Leeuw, G. de; Cohen, L.H.

    1995-01-01

    Bubble size distributions have been measured with an optical system that is based on imaging of a small sample volume with a CCD camera system, and processing of the images to obtain the size of individual bubbles in the diameter range from 30 to lOOO^m. This bubble measuring system is deployed from

  7. The Effect of Grazing by the Slug Arion Vulgaris, Arion Rufus and Deroceras Reticulatum (Gastropoda: Pulmonata: Stylommatophora on Leguminous Plants and other Small-Area Crops

    Directory of Open Access Journals (Sweden)

    Kozłowski Jan

    2014-07-01

    Full Text Available Herbivorous slugs do significant damage to many species of crop plants. A laboratory study was conducted to determine the rate and extent of damage caused to 16 plant species by Arion vulgaris, Arion rufus, and Deroceras reticulatum. It was found, that levels of damage caused to young plants of Brassica napus, Sorghum bicolor, Vicia faba, and Sinapis alba by the slugs A. vulgaris, A. rufus, and D. reticulatum were similar, while levels of damage caused to the other studied plants by particular slug species differed significantly. Based on the results of the damage by the investigated slug species, plants were categorised as heavily or lightly damaged.

  8. Gas slug ascent in a stratified magma: Implications of flow organisation and instability for Strombolian eruption dynamics

    Science.gov (United States)

    Capponi, A.; James, M. R.; Lane, S. J.

    2016-02-01

    The canonical Strombolian paradigm of a gas slug ascending and bursting in a homogeneous low-viscosity magma cannot explain the complex details in eruptive dynamics recently revealed by field measurements and textural and geochemical analyses. Evidence points to the existence of high-viscosity magma at the top of the conduit of Strombolian-type volcanoes, acting as a plug. Here, new experiments detail the range of flow configurations that develop during the ascent and burst of a slug through rheologically stratified magma within a conduit. End-member scenarios of a tube fully filled with either high- or low-viscosity liquid bracket three main flow configurations: (1) a plug sufficiently large to fully accommodate an ascending gas slug; (2) A plug that can accommodate the intrusion of low-viscosity liquid driven by the gas expansion, but not all the slug volume, so the slug bursts with the nose in the plug whilst the base is still in the low-viscosity liquid; (3) Gas expansion is sufficient to drive the intrusion of low-viscosity liquid through the plug, with the slug bursting in the low-viscosity layer emplaced dynamically above the plug. We show that the same flow configurations are viable at volcanic-scale through a new experimentally-validated 1D model and 3D computational fluid dynamic simulations. Applied to Stromboli, our results demonstrate that the key parameters controlling the transition between each configuration are gas volume, plug thickness and plug viscosity. The flow processes identified include effective dynamic narrowing and widening of the conduit, instabilities within the falling magma film, transient partial and complete blockage of the conduit, and slug disruption. These complexities influence eruption dynamics and vigour, promoting magma mingling and resulting in pulsatory release of gas.

  9. Switching Characteristics of Ferroelectric Transistor Inverters

    Science.gov (United States)

    Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

    2010-01-01

    This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

  10. Static Characteristics of the Ferroelectric Transistor Inverter

    Science.gov (United States)

    Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.

  11. Dynamic behavior of gas bubble in single bubble sonoluminescence - vibrator model

    Institute of Scientific and Technical Information of China (English)

    QIAN Menglu; CHENG Qian; GE Caoyan

    2002-01-01

    Single bubble sonoluminescence is a process of energy transformation from soundto light. Therefore the motion equations of near spherical vibration of a gas bubble in anincompressible and viscous liquid can be deduced by Lagrangian Equation with dissipationfunction when the bubble is considered as a vibrator surrounded by liquid. The analyticalsolutions in the bubble expanding, collapsing and rebounding stages can be obtained by solvingthese motion equations when some approximations are adopted. And the dynamic behaviorsof the bubble in these three stages are discussed.

  12. Droplets, Bubbles and Ultrasound Interactions

    NARCIS (Netherlands)

    Shpak, O.; Verweij, M.; Jong, de N.; Versluis, M.; Escoffre, J.M.; Bouakaz, A.

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to

  13. "Financial Bubbles" and Monetary Policy

    Science.gov (United States)

    Tikhonov, Yuriy A.; Pudovkina, Olga E.; Permjakova, Juliana V.

    2016-01-01

    The relevance of this research is caused by the need of strengthening a role of monetary regulators to prevent financial bubbles in the financial markets. The aim of the article is the analysis of a problem of crisis phenomena in the markets of financial assets owing to an inadequate growth of their cost, owing to subjective reasons. The leading…

  14. Explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den D.M.; Elwenspoek, M.C.

    2007-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a very high temperature in a very short time. At these temperatures homogeneous nucleation takes place. The nucleated bubbles almost instantly coalesce forming a vapour film followed by rapid growth due to the pressure impulse and fina

  15. Bubble-Driven Inertial Micropump

    CERN Document Server

    Torniainen, Erik D; Markel, David P; Kornilovitch, Pavel E

    2012-01-01

    The fundamental action of the bubble-driven inertial micropump is investigated. The pump has no moving parts and consists of a thermal resistor placed asymmetrically within a straight channel connecting two reservoirs. Using numerical simulations, the net flow is studied as a function of channel geometry, resistor location, vapor bubble strength, fluid viscosity, and surface tension. Two major regimes of behavior are identified: axial and non-axial. In the axial regime, the drive bubble either remains inside the channel or continues to grow axially when it reaches the reservoir. In the non-axial regime the bubble grows out of the channel and in all three dimensions while inside the reservoir. The net flow in the axial regime is parabolic with respect to the hydraulic diameter of the channel cross-section but in the non-axial regime it is not. From numerical modeling, it is determined that the net flow is maximal when the axial regime crosses over to the non-axial regime. To elucidate the basic physical princi...

  16. The Big European Bubble Chamber

    CERN Multimedia

    1977-01-01

    The 3.70 metre Big European Bubble Chamber (BEBC), dismantled on 9 August 1984. During operation it was one of the biggest detectors in the world, producing direct visual recordings of particle tracks. 6.3 million photos of interactions were taken with the chamber in the course of its existence.

  17. Giant Bubble Pinch-Off

    NARCIS (Netherlands)

    Bergmann, R.P.H.M.; van der Meer, Roger M.; Stijnman, Mark; Stijnman, M; Sandtke, M.; Prosperetti, Andrea; Lohse, Detlef

    2006-01-01

    Self-similarity has been the paradigmatic picture for the pinch-off of a drop. Here we will show through high-speed imaging and boundary integral simulations that the inverse problem, the pinch-off of an air bubble in water, is not self-similar in a strict sense: A disk is quickly pulled through a w

  18. Murray Strasberg and bubble acoustics

    NARCIS (Netherlands)

    Prosperetti, Andrea

    2014-01-01

    Murray Strasberg made seminal contributions to the nucleation and acoustics of bubbles. Half a century after publication, these papers still receive a sizable number of citations every year. The talk will review this work, comment on its impact, and put Strasberg's classical results in a modern

  19. Electrolysis Bubbles Make Waterflow Visible

    Science.gov (United States)

    Schultz, Donald F.

    1990-01-01

    Technique for visualization of three-dimensional flow uses tiny tracer bubbles of hydrogen and oxygen made by electrolysis of water. Strobe-light photography used to capture flow patterns, yielding permanent record that is measured to obtain velocities of particles. Used to measure simulated mixing turbulence in proposed gas-turbine combustor and also used in other water-table flow tests.

  20. Impurity bubbles in a BEC

    Science.gov (United States)

    Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

    2013-05-01

    Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

  1. The effects of bubble-bubble interactions on pressures and temperatures produced by bubbles collapsing near a rigid surface

    Science.gov (United States)

    Alahyari Beig, Shahaboddin; Johnsen, Eric

    2016-11-01

    Cavitation occurs in a wide range of hydraulic applications, and one of its most important consequences is structural damage to neighboring surfaces following repeated bubble collapse. A number of studies have been conducted to predict the pressures produced by the collapse of a single bubble. However, the collapse of multiple bubbles is known to lead to enhanced collapse pressures. In this study, we quantify the effects of bubble-bubble interactions on the bubble dynamics and pressures/temperatures produced by the collapse of a pair of bubbles near a rigid surface. For this purpose, we use an in-house, high-order accurate shock- and interface-capturing method to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. The non-spherical bubble dynamics are investigated and the subsequent pressure and temperature fields are characterized based on the relevant parameters entering the problem: stand-off distance, geometrical configuation, collapse strength. We demonstrate that bubble-bubble interactions amplify/reduce pressures and temperatures produced at the collapse, and increase the non-sphericity of the bubbles and the collapse time, depending on the flow parameters.

  2. Inverted CERN School of Computing

    CERN Multimedia

    IT Department

    2011-01-01

      The 5th edition of the Inverted CERN School of Computing (iCSC, “Where students turn into teachers”) will take place next Thursday and Friday (3 and 4 of March) at CERN, Building 31 - IT Amphitheatre - Third Floor. Attendance is free and open to everyone. The programme is designed so that you can attend the lectures that interest you. This year highlights: Cloud Computing, Software Engineering, Cryptography Registration is not mandatory, but will allow you to obtain a copy of the full booklet (first registered, first served). Programme overview: Thursday 3 March 2011 10:00 - 10:15 Introduction School opening 10:15 - 11:10 Lecture 1 Virtualization: what it is, how it works – Luigi Gallerani 11:20 - 12:15 Lecture 2 Server Virtualization at work – Carlos Garcia Fernandez 14:00 - 14:55 Lecture 3 Unweaving Clouds: Principles and Practice – Belmiro Moreira 15:30 - 16:25 Lecture 4 Understanding Cryptography: From Caesar to Public-Key – Nicola...

  3. Simulation of bubbly flow in vertical pipes by coupling Lagrangian and Eulerian models with 3D random walks models: Validation with experimental data using multi-sensor conductivity probes and Laser Doppler Anemometry

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Cobo, Jose L., E-mail: jlcobos@iqn.upv.es [Instituto de Ingenieria Energetica, Universidad Politecnica de Valencia, Valencia (Spain); Chiva, Sergio [Department of Mechanical Engineering and Construction, Universitat Jaume I, Castellon (Spain); Essa, Mohamed Ali Abd El Aziz [Instituto de Ingenieria Energetica, Universidad Politecnica de Valencia, Valencia (Spain); Mendes, Santos [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer We have simulated bubbly flow in vertical pipes by coupling a Lagrangian model to an Eulerian one, and to a 3D random walk model. Black-Right-Pointing-Pointer A set of experiments in a vertical column with isothermal co-current two phase flow have been performed and used to validate the previous model. Black-Right-Pointing-Pointer We have investigated the influence of the turbulence induced by the bubbles on the results. Black-Right-Pointing-Pointer Comparison of experimental and computed results has been performed for different boundary conditions. - Abstract: A set of two phase flow experiments for different conditions ranging from bubbly flow to cap/slug flow have been performed under isothermal concurrent upward air-water flow conditions in a vertical column of 3 m height. Special attention in these experiments was devoted to the transition from bubbly to cap/slug flow. The interfacial velocity of the bubbles and the void fraction distribution was obtained using 2 and 4 sensors conductivity probes. Numerical simulations of these experiments for bubbly flow conditions were performed by coupling a Lagrangian code with an Eulerian one. The first one tracks the 3D motion of the individual bubbles in cylindrical coordinates (r, {phi}, z) inside the fluid field under the action of the following forces: buoyancy, drag, lift, wall lubrication. Also we have incorporated a 3D stochastic differential equation model to account for the random motion of the individual bubbles in the turbulent velocity field of the carrier liquid. Also we have considered the deformations undergone by the bubbles when they touch the walls of the pipe and are compressed until they rebound. The velocity and turbulence fields of the liquid phase were computed by solving the time dependent conservation equations in its Reynolds Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate {epsilon} transport equations

  4. Experimental study of the interaction between the spark-induced cavitation bubble and the air bubble

    Institute of Scientific and Technical Information of China (English)

    罗晶; 许唯临; 牛志攀; 罗书靖; 郑秋文

    2013-01-01

    Experiments are carried out by using high-speed photography to investigate the interaction between the spark-generated cavitation bubble and the air bubble in its surrounding fluid. Three problems are discussed in detail: the impact of the air bubble upon the development of the cavitation bubble, the evolution of the air bubble under the influence of the cavitation bubble, and the change of the fluid pressure during the development of a micro jet of the cavitation bubble. Based on the experimental results, under the condition of no air bubble present, the lifetime of the cavitation bubble from expansion to contraction increases with the increase of the maximum radius. On the other hand, when there is an air bubble present, different sized cavitation bubbles have similarity with one another generally in terms of the lifetime from expansion to contraction, which does not depend on the maximum radius. Also, with the presence of an air bubble, the lifetime of the smaller cavitation bubble is extended while that of the bigger ones reduced. Furthermore, it is shown in the experiment that the low pressure formed in the opposite direction to the cavitation bubble micro jet makes the air bubble in the low pressure area being stretched into a steplike shape.

  5. Shell correction energy for bubble nuclei

    CERN Document Server

    Yu, Y; Magierski, P; Bulgac, Aurel; Magierski, Piotr

    2000-01-01

    The positioning of a bubble inside a many fermion system does not affect the volume, surface or curvature terms in the liquid drop expansion of the total energy. Besides possible Coulomb effects, the only other contribution to the ground state energy of such a system arises from shell effects. We show that the potential energy surface is a rather shallow function of the displacement of the bubble from the center and in most cases the preferential position of a bubble is off center. Systems with bubbles are expected to have bands of extremely low lying collective states, corresponding to various bubble displacements.

  6. Robust acoustic wave manipulation of bubbly liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gumerov, N. A., E-mail: gumerov@umiacs.umd.edu [Institute for Advanced Computer Studies, University of Maryland, College Park, Maryland 20742 (United States); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Akhatov, I. S. [Center for Design, Manufacturing and Materials, Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Ohl, C.-D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Sametov, S. P. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Khazimullin, M. V. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Institute of Molecule and Crystal Physics, Ufa Research Center of Russian Academy of Sciences, Ufa 450054 (Russian Federation); Gonzalez-Avila, S. R. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2016-03-28

    Experiments with water–air bubbly liquids when exposed to acoustic fields of frequency ∼100 kHz and intensity below the cavitation threshold demonstrate that bubbles ∼30 μm in diameter can be “pushed” away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

  7. Lidar signature from bubbles in the sea.

    Science.gov (United States)

    Churnside, James H

    2010-04-12

    The lidar signature from a collection of bubbles is proportional to the volume backscatter coefficient at a scattering angle of 180 degrees . This quantity, calculated using a combination of geometric optics and diffraction, is proportional to the void fraction of the bubbles in the water for any bubble size distribution. The constant of proportionality is 233 m(-1) sr(-1)for clean bubbles, slightly less for bubbles coated with a thin layer of organic material, and as large as 1445 m(-1) sr(-1) for a thick coating of protein.

  8. Supercoiling induces denaturation bubbles in circular DNA.

    Science.gov (United States)

    Jeon, Jae-Hyung; Adamcik, Jozef; Dietler, Giovanni; Metzler, Ralf

    2010-11-12

    We present a theoretical framework for the thermodynamic properties of supercoiling-induced denaturation bubbles in circular double-stranded DNA molecules. We explore how DNA supercoiling, ambient salt concentration, and sequence heterogeneity impact on the bubble occurrence. An analytical derivation of the probability distribution to find multiple bubbles is derived and the relevance for supercoiled DNA discussed. We show that in vivo sustained DNA bubbles are likely to occur due to partial twist release in regions rich in weaker AT base pairs. Single DNA plasmid imaging experiments clearly demonstrate the existence of bubbles in free solution.

  9. Bubble Universe Dynamics After Free Passage

    CERN Document Server

    Ahlqvist, Pontus; Greene, Brian

    2013-01-01

    We consider bubble collisions in single scalar field theories with multiple vacua. Recent work has argued that at sufficiently high impact velocities, collisions between such bubble vacua are governed by 'free passage' dynamics in which field interactions can be ignored during the collision, providing a systematic process for populating local minima without quantum nucleation. We focus on the time period that follows the bubble collision and provide evidence that, for certain potentials, interactions can drive significant deviations from the free-passage bubble profile, thwarting the production of bubbles with different field values.

  10. Magnetically Coupled Impedance-Source Inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    input-to-output gain and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters, most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...

  11. Magnetically coupled impedance-source inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2012-01-01

    input-to-output gain, and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters. Most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...

  12. An equation of motion for bubble growth

    Energy Technology Data Exchange (ETDEWEB)

    Lesage, F.J. [College d' Enseignement General et Professionnel de L' Outaouais, Gatineau, Quebec (Canada). Dept. of Mathematics; Cotton, J.S. [McMaster University, Hamilton, ON (Canada). Dept. of Mechanical Engineering; Robinson, A.J. [Trinity College Dublin (Ireland). Dept. of Mechanical and Manufacturing Engineering

    2009-07-01

    A mathematical model is developed which describes asymmetric bubble growth, either during boiling or bubble injection from submerged orifices. The model is developed using the integral form of the continuity and momentum equations, resulting in a general expression for the acceleration of the bubble's centre of gravity. The proposed model highlights the need to include acceleration due to an asymmetric gain or loss of mass in order to accurately predict bubble motion. Some scenarios are posed by which the growth of bubbles, particularly idealized bubbles that remain a section of a sphere, must include the fact that bubble growth can be asymmetric. In particular, for approximately hemispherical bubble growth the sum of the forces acting on the bubble is negligible compared with the asymmetric term. Further, for bubble injection from a submerged needle this component in the equation of motion is very significant during the initial rapid growth phase as the bubble issues from the nozzle changing from a near hemisphere to truncated sphere geometry. (author)

  13. Inverted Nipple With Nipple-Sparing Mastectomy.

    Science.gov (United States)

    Yim, Ji Hong; Lee, Taik Jong

    2016-08-01

    The inverted nipple is a relatively common aesthetic problem seen by plastic surgeons. The etiologies of an inverted nipple include insufficiency of supporting tissues, hypoplasia of the lactiferous ducts, and retraction caused by fibrous bands at the base of the nipple. Many different surgical techniques have been described, either individually or in combination, but none represents a landmark strategy. In our present study, we report our experience of spontaneous improvement immediately after nipple-sparing mastectomy with simple buried interrupted sutures to maintain nipple base in inverted nipple patients. We describe our 10 years' experience in using a simple approach to correct inverted nipples after nipple-sparing mastectomy with pedicled transverse rectus abdominis myocutaneous flap reconstruction. Between January 2001 and August 2010, we observed 23 inverted nipples after nipple-sparing mastectomy by using only a buried baseline suture to tighten the base of the nipple. The follow-up period ranged from 3 to 13 years. After nipple-sparing mastectomy with tightening of the base of the nipple, improvements were seen in 18 of the 23 patients. No complications associated with surgery occurred, such as infection, depigmentation, sensory disturbance, or nipple necrosis. The simple method of baseline suturing that only tightens the nipple base with nipple-sparing mastectomy has been used in our center over a 10-year period in patients with breast cancer and an inverted nipple. The retractile duct or fibrous cord was completely cut with nipple-sparing mastectomy, and over 70% of inverted nipples in the patients were improved and maintained with only the tightening of the base of the nipple. Our results show that inverted nipple is caused by tight fibrous band or short duct rather than a lack of subareolar tissue.

  14. Inverted mesiodens--a case report.

    Science.gov (United States)

    Nikhil, S; Vineeta; Gupta, P

    1999-09-01

    A nine and a half years old female school child was examined in a during routine dental examination. The patient had swelling over maxillary midline area just near the labial frenum. Both the central incisors were in position. Radiographic examination revealed presence of an inverted supernumerary tooth between the roots of the central incisors. Surgical extraction of the supernumerary was planned. A unique case of inverted (upside down) mesiodens is presented.

  15. Digital Microfluidics with Bubble Manipulations by Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Shih-Kang Fan

    2012-03-01

    Full Text Available This paper presents basic bubble manipulations, including transporting, splitting, and merging, by dielectrophoresis (DEP in an oil environment. In our presented method, bubbles are placed between parallel plates in an oil medium of a low vapor pressure, which eliminates the possibility of changing the gaseous composition of the bubble caused by evaporation of the medium. DEP has been previously investigated to actuate dielectric droplets and is adopted here to drive the oil environment as well as the immersed bubbles between parallel plates. In our experiment, air bubbles of 0.3 ml were successfully transported in a 20 cSt silicone oil medium between a 75 mm-high parallel plate gap. In addition, 0.6 ml air bubbles were successfully split into two 0.3 ml air bubbles, and then merged again by DEP. These successful manipulations make digital gaseous lab-on-a-chip a reality.

  16. Cosmological HII Bubble Growth During Reionization

    CERN Document Server

    Shin, Min-Su; Cen, Renyue

    2007-01-01

    We present general properties of ionized hydrogen (HII) bubbles and their growth based on a state-of-the-art large-scale (100 Mpc/h) cosmological radiative transfer simulation. The simulation resolves all halos with atomic cooling at the relevant redshifts and simultaneously performs radiative transfer and dynamical evolution of structure formation. Our major conclusions include: (1) for significant HII bubbles, the number distribution is peaked at a volume of ~ 0.6 Mpc^3/h^3 at all redshifts. But, at z 10 even the largest HII bubbles have a balanced ionizing photon contribution from Pop II and Pop III stars, while at z < 8 Pop II stars start to dominate the overall ionizing photon production for large bubbles, although Pop III stars continue to make a non-negligible contribution. (6) The relationship between halo number density and bubble size is complicated but a strong correlation is found between halo number density and bubble size for for large bubbles.

  17. Bubbles generated from wind-steepened breaking waves: 2. Bubble plumes, bubbles, and wave characteristics

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G.de

    2006-01-01

    Measurements of breaking-wave-generated bubble plumes were made in fresh (but not clean) water in a large wind-wave tunnel. To preserve diversity, a classification scheme was developed on the basis of plume dimensions and "optical density," or the plume's ability to obscure the background. Optically

  18. MULTIPHASE DROPLET/SLUG BREAK-UP MECHANISM IN MICROFLUIDIC T-JUNCTIONS AT VARIOUS WEBER NUMBERS

    Directory of Open Access Journals (Sweden)

    Wan Leng (Dawn Leow

    2011-10-01

    Full Text Available Normal 0 false false false EN-MY X-NONE X-NONE The formation of immiscible liquid droplets, or slugs, in microchannels features the advantages of volume control and mixing enhancement over single-phase microflows. Although the applications of droplet-based microfluidics have been widely demonstrated, the fundamental physics governing droplet break-up remains an area of active research. This study defines an effective Weber (Weeff number that characterizes the interplay of interfacial tension, shear stress and channel pressure drop in driving slug formation in T-junction microchannel for a relative range of low, intermediate and high flow rates. The immiscible fluid system in this study consists of Tetradecane slug formation in Acetonitrile. The progressive deformation of slug interfaces during break-up events is observed. Experimental results indicate that, at a relatively low Weeff, clean slug break-up occurs at the intersection of the side and main channels. At intermediate Weeff, the connecting neck of the dispersed phase is stretched to a short and thin trail of laminar flow prior to breaking up a short distance downstream of the T-junction. At a relatively high Weeff, the connecting neck develops into a longer and thicker trail of laminar flow that breaks up further downstream of the main channel.

  19. Harmonics Study and Comparison of Z-source Inverter with Traditional Inverters

    Directory of Open Access Journals (Sweden)

    B. Justus Rabi

    2005-01-01

    Full Text Available This paper presents an Impedance Source Inverter for A.C electrical drives. The impedance source inverter employs a unique impedance network cable with inverter main circuit and rectifier. By controlling the shoot-through duty cycle, the z-source inverter system using MOSFETS provide ride-through capability during voltage sags, reduces line harmonics, improves power factor and high reliability, and extends output voltage range. Analysis, simulation, and experimental results will be presented to demonstrate these new features. It reduces harmonics, electromagnetic interference noise and it has low common mode noise.

  20. Developed ‘laminar’ bubbly flow with non-uniform bubble sizes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Bubbles with different sizes have different dynamic and kineticbehavior in a two-phase bubbly flow. A common two-fluid model based on the uniform bubble size assumption is not suitable for a bubbly flow with non-uniform bubble sizes. To deal with non-uniform bubbly flows, a multi-fluid model is established, with which bubbles are divided into several groups according to their sizes and a set of basic equations is derived for each group of bubbles with almost the same size. Through analyzing the bubble-bubble and bubble-pipe wall interactions, two new constitutive laws for the wall-force and pressure difference between the liquid phase and interface are developed to close the averaged basic equations. The respective phase distributions for each group of bubbles measured by a specially designed three-dimensional photographic method are used to check the model. Comparison between model-predicted values and experimental data shows that the model can describe laminar bubbly flow with non-uniform bubble sizes.

  1. Bubble–bubble interaction effects on dynamics of multiple bubbles in a vortical flow field

    Directory of Open Access Journals (Sweden)

    Bing Cui

    2016-02-01

    Full Text Available Bubble–bubble interactions play important roles in the dynamic behaviours of multiple bubbles or bubble clouds in a vortical flow field. Based on the Rayleigh–Plesset equation and the modified Maxey–Riley equation of a single bubble, bubble–bubble interaction terms are derived and introduced for multiple bubbles. Thus, both the Rayleigh–Plesset and modified Maxey–Riley equations are improved by considering bubble–bubble interactions and then applied for the multiple bubbles entrainment into a stationary Gaussian vortex. Runge–Kutta fourth-order scheme is adopted to solve the coupled dynamic and kinematic equations and the convergence study has been conducted. Numerical result has also been compared and validated with the published experimental data. On this basis, the oscillation, trajectory and effects of different parameters of double-bubble and multi-bubble entrainment into Gaussian vortex have been studied and the results have been compared with those of the cases without bubble–bubble interactions. It indicates that bubble–bubble interactions influence the amplitudes and periods of bubble oscillations severely, but have small effects on bubble trajectories.

  2. Suppression of cavitation inception by gas bubble injection: a numerical study focusing on bubble-bubble interaction.

    Science.gov (United States)

    Ida, Masato; Naoe, Takashi; Futakawa, Masatoshi

    2007-10-01

    The dynamic behavior of cavitation and gas bubbles under negative pressure has been studied numerically to evaluate the effect of gas bubble injection into a liquid on the suppression of cavitation inception. In our previous studies, it was demonstrated by direct observation that cavitation occurs in liquid mercury when mechanical impacts are imposed, and this will cause cavitation damage in spallation neutron sources, in which liquid mercury is bombarded by a high-power proton beam. In the present paper, we describe numerical investigations of the dynamics of cavitation bubbles in liquid mercury using a multibubble model that takes into account the interaction of a cavitation bubble with preexisting gas bubbles through bubble-radiated pressure waves. The numerical results suggest that, if the mercury includes gas bubbles whose equilibrium radius is much larger than that of the cavitation bubble, the explosive expansion of the cavitation bubble (i.e., cavitation inception) is suppressed by the positive-pressure wave radiated by the injected bubbles, which decreases the magnitude of the negative pressure in the mercury.

  3. Variable universe adaptive fuzzy control on the quadruple inverted pendulum

    Institute of Scientific and Technical Information of China (English)

    李洪兴; 苗志宏; 王家银

    2002-01-01

    This paper focuses on the control problem of the quadruple inverted pendulum by variable universe adaptive fuzzy control.First,the mathematical model on the quadruple inverted pendulum is described and its controllability is versified.Then,an efficient controller on the quadruple inverted pendulum is designed by using variable universe adaptive fuzzy control theory.Finally the simulation of the quadruple inverted pendulum is shown in detail.Besides,the experimental results on the hardware systems,i.e.real object systems,on a single inverted pendulum,a double inverted pendulum and a triple inverted pendulum are briefly introduced.``

  4. Fabrication of U-10wt.%Zr Fuel slug for SFR by Injection Casting

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Hwan; Song, Hoon; Kim, Hyung Tae; Ko, Young Mo; Kim, Ki Hwan; Lee, Chan B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    The fabrication technology of metal fuel has been developed by various methods such as rolling, swaging, wire drawing, and co-extrusion, but each of these methods had process limitations requiring an additional subsequent process, and needing the fabrication equipment is complex, which is not favorable for remote use. A practical process of metallic fuel fabrication for an SFR needs to be cost efficient, suitable for remote operation, and capable of mass production while reducing the amount of radioactive waste. Injection casting was chosen as the most promising technique, in the early 1950s, and this technique has been applied to fuel slug fabrication for the Experimental Breeder Reactor-II (EBR-II) driver and the Fast Flux Test Facility (FFTF) fuel pins. Because of the simplistic nature of the process and equipment, compared to other processes examined, this process has been successfully used in a remote operation environment for fueling of the EBR-II reactor. In this study, vacuum injection casting suitable for remote operation has been developed to fabricate metallic fuel for an SFR. Vacuum injection casting technique was developed to fabricate metallic fuel for an SFR. The appearance of the fabricated U-10wt.%Zr fuel was generally sound and the internal integrity was found to be satisfactory through gamma-ray radiography. Minimum fuel losses after casting relative to the initial charge amount of U-10wt.%Zr fuel slugs met the proposed goal of less than 0.1% fuel losses during fabrication. Modifications of the current facility system and advanced casting techniques are underway to produce higher quality fuel slugs.

  5. Model-Free Predictive Anti-Slug Control of a Well-Pipeline-Riser

    Directory of Open Access Journals (Sweden)

    Christer Dalen

    2016-01-01

    Full Text Available Simplified linearized discrete time dynamic state space models are developed for a 3-phase well-pipeline-riser and tested together with a high fidelity dynamic model built in K-Spice and LedaFlow. In addition the Meglio pipeline-riser model is used as an example process. These models are developed from a subspace algorithm, i.e. Deterministic and Stochastic system identification and Realization (DSR, and implemented in a Model Predictive Controller (MPC for stabilizing the slugging regime. The MPC, LQR and PI control strategies are tested.

  6. Directed percolation describes lifetime and growth of turbulent puffs and slugs

    CERN Document Server

    Sipos, Maksim

    2011-01-01

    The phenomenology of pipe flow is characterized by complex turbulent structures, puffs and slugs, whose behavior is still not fully understood. In this Letter, we show that transitional turbulence in a pipe can be quantitatively modeled by directed percolation (DP). The active (turbulent) states in subcritical DP exhibit superexponentially diverging characteristic lifetime, similar to that observed of turbulent puffs. Above the percolation threshold, active (turbulent) clusters expand into the inactive (laminar) phase with a well-defined velocity whose scaling with control parameter (Reynolds number or percolation probability) is consistent with experimental results.

  7. The slug mucosal irritation (SMI) assay: development of a screening tool for the evaluation of ocular discomfort caused by shampoos.

    Science.gov (United States)

    Lenoir, Joke; Claerhout, Ilse; Kestelyn, Philippe; Klomp, Andre; Remon, Jean-Paul; Adriaens, Els

    2011-12-01

    In this research, the slug mucosal irritation (SMI) assay was applied to predict ocular discomfort caused by shampoos to investigate the correlation between responses in slugs and humans. Several SMI experiments and a human eye irritation test (HEIT) were performed with 1 artificial tear solution (ArtTear) and 5 shampoos (A-E; 5%-dilution). In the HEIT, evaluation was performed by participants and an ophthalmologist at several time points. Analyses reveal that (1) a significant positive association existed between immediate stinging reaction reported by the participants and the mean total mucus produced by the slugs (MTMP) (Spearman's Rank correlation=0.986, pSMI assay is a promising evaluation method for discomfort in the human eye. Screening prototype (eye) formulations with this assay allows formula optimization prior to a HEIT.

  8. A PHYSICAL MODEL FOR PREDICTING THE PRESSURE DROP OF GAS-LIQUID SLUG FLOW IN HORIZONTAL PIPES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A comprehensive treatment of all sources of pressure drop within intermittent gas-liquid flow is presented. A slug unit is divided into three parts and the pressure gradient of each part is calculated separately. In the mixing zone the momentum theory is employed and the mixing process between the film and slug is simulated by a two-dimensional wall jet entering a large reservoir to calculate the mixing length. The boundary layer theory is utilized to calculate the pressure drop for the slug body and the momentum equation of the film zone is integrated to calculate the pressure drop for the film zone. The pressure drop predicted in present model is in good agreement with all the measurements.

  9. Bubble entrapment through topological change

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2010-05-03

    When a viscousdrop impacts onto a solid surface, it entraps a myriad of microbubbles at the interface between liquid and solid. We present direct high-speed video observations of this entrapment. For viscousdrops, the tip of the spreading lamella is separated from the surface and levitated on a cushion of air. We show that the primary mechanism for the bubble entrapment is contact between this precursor sheet of liquid with the solid and not air pulled directly through cusps in the contact line. The sheet makes contact with the solid surface,forming a wetted patch, which grows in size, but only entraps a bubble when it meets the advancing contact line. The leading front of this wet patch can also lead to the localized thinning and puncturing of the liquid film producing strong splashing of droplets.

  10. Cavitation inception from bubble nuclei

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2015-01-01

    , and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model......The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years...

  11. Conformal gravity and "gravitational bubbles"

    CERN Document Server

    Berezin, V A; Eroshenko, Yu N

    2015-01-01

    We describe the general structure of the spherically symmetric solutions in the Weyl conformal gravity. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions, consisting of two classes, is found. The first one contains the solutions with constant two-dimensional curvature scalar, and the representatives are the famous Robertson--Walker metrics. We called one of them the "gravitational bubbles", which is compact and with zero Weyl tensor. These "gravitational bubbles" are the pure vacuum curved space-times (without any material sources, including the cosmological constant), which are absolutely impossible in General Relativity. This phenomenon makes it easier to create the universe from "nothing". The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family, which can be conformally covered by the thee-para...

  12. Armoring confined bubbles in concentrated colloidal suspensions

    Science.gov (United States)

    Yu, Yingxian; Khodaparast, Sepideh; Stone, Howard

    2016-11-01

    Encapsulation of a bubble with microparticles is known to significantly improve the stability of the bubble. This phenomenon has recently gained increasing attention due to its application in a variety of technologies such as foam stabilization, drug encapsulation and colloidosomes. Nevertheless, the production of such colloidal armored bubble with controlled size and particle coverage ratio is still a great challenge industrially. We study the coating process of a long air bubble by microparticles in a circular tube filled with a concentrated microparticles colloidal suspension. As the bubble proceeds in the suspension of particles, a monolayer of micro-particles forms on the interface of the bubble, which eventually results in a fully armored bubble. We investigate the phenomenon that triggers and controls the evolution of the particle accumulation on the bubble interface. Moreover, we examine the effects of the mean flow velocity, the size of the colloids and concentration of the suspension on the dynamics of the armored bubble. The results of this study can potentially be applied to production of particle-encapsulated bubbles, surface-cleaning techniques, and gas-assisted injection molding.

  13. Soap bubbles in paintings: Art and science

    Science.gov (United States)

    Behroozi, F.

    2008-12-01

    Soap bubbles became popular in 17th century paintings and prints primarily as a metaphor for the impermanence and fragility of life. The Dancing Couple (1663) by the Dutch painter Jan Steen is a good example which, among many other symbols, shows a young boy blowing soap bubbles. In the 18th century the French painter Jean-Simeon Chardin used soap bubbles not only as metaphor but also to express a sense of play and wonder. In his most famous painting, Soap Bubbles (1733/1734) a translucent and quavering soap bubble takes center stage. Chardin's contemporary Charles Van Loo painted his Soap Bubbles (1764) after seeing Chardin's work. In both paintings the soap bubbles have a hint of color and show two bright reflection spots. We discuss the physics involved and explain how keenly the painters have observed the interaction of light and soap bubbles. We show that the two reflection spots on the soap bubbles are images of the light source, one real and one virtual, formed by the curved surface of the bubble. The faint colors are due to thin film interference effects.

  14. Bioinspired bubble design for particle generation.

    Science.gov (United States)

    Gunduz, Oguzhan; Ahmad, Zeeshan; Stride, Eleanor; Tamerler, Candan; Edirisinghe, Mohan

    2012-02-07

    In this study, we devise a method to generate homogeneous particles from a bubble suspension, with the capability to control loading and the structure of bubbles. Ideally, a process such as this would occur at the interface between daughter bubble formation (instant) and gaseous diffusion (gradual). Interestingly, the budding mechanism in micro-organisms is one that demonstrates features of the desired phenomena (although at a much slower rate), as viruses can eject and evolve structures from their membranes. With these natural concepts, a bubble's surface can also be made to serve as a platform for particle generation, which transfers significant elements from the initial bubble coating to the newly generated structures. Here, we illustrate this by preparing coated bubbles (approx. 150 µm in diameter) using a hydrophobic polymer, which may be comparable to naturally occurring bubble coatings (e.g. organic matter forming part of bubble coatings in the sea), and dye (which can demonstrate entrapment of smaller quantities of a desired moiety) and then observe particle generation (approx. 500 nm). The process, which may be driven by a polymerosome-forming mechanism, also illustrates how additional uniform sub-micrometre-scale structures may form from a bubble's surface, which may have also previously been attributed to gas diffusion. In addition, such methods of particle formation from a bubble structure, the incorporation of chemical or biological media via an in situ process and subsequent release technologies have several areas of interest across the broad scientific community.

  15. Applicability of the black slug Arion ater for monitoring exposure to polycyclic aromatic hydrocarbons and their subsequent bioactivation into DNA binding metabolites

    NARCIS (Netherlands)

    Hamers, T.; Kalis, E.J.J.; Berg, van den J.H.J.; Maas, L.M.; Schooten, van F.J.; Murk, A.J.

    2004-01-01

    The applicability of terrestrial black slugs Arion ater (Mollusca, Gastropoda) was studied for biomonitoring environmental exposure to polycyclic aromatic hydrocarbons (PAHs). In laboratory experiments, slugs were orally exposed to benzo[a]pyrene (BaP) for a short term (3 days) or a long term (119

  16. Applicability of the black slug Arion ater for monitoring exposure to polycyclic aromatic hydrocarbons and their subsequent bioactivation into DNA binding metabolites

    NARCIS (Netherlands)

    Hamers, T.; Kalis, E.J.J.; Berg, van den J.H.J.; Maas, L.M.; Schooten, van F.J.; Murk, A.J.

    2004-01-01

    The applicability of terrestrial black slugs Arion ater (Mollusca, Gastropoda) was studied for biomonitoring environmental exposure to polycyclic aromatic hydrocarbons (PAHs). In laboratory experiments, slugs were orally exposed to benzo[a]pyrene (BaP) for a short term (3 days) or a long term (119 d

  17. Informational pathologies and interest bubbles

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Wiewiura, Joachim Schmidt

    2017-01-01

    This article contends that certain configurations of information networks facilitate specific cognitive states that are instrumental for decision and action on social media. Group-related knowledge and belief states—in particular common knowledge and pluralistic ignorance—may enable strong public...... signals. Indeed, some network configurations and attitude states foster informational pathologies that may fuel interest bubbles affecting agenda-setting and the generation of narratives in public spheres....

  18. Electrino bubbles and relational entanglement

    CERN Document Server

    Vecchi, I

    2007-01-01

    In this note, which is based and expands on some previous work, it is argued that the phenomena exhibited by bubbles forming around free electrons in liquid helium and examined by Maris in his controversial 2000 paper point to the experimental relevance of an understanding of entanglement based on the relational approach to quantum mechanics. An experiment to verify/disprove the relevant argument is suggested.

  19. BEBC Big European Bubble Chamber

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    A view of the dismantling of the magnet of BEBC, the 3.7 m European Bubble Chamber : iron magnetic shielding ; lower and upper parts of the vacuum enclosure of the magnet; turbo-molecular vacuum pumps for the "fish-eye" windows; the two superconducting coils; a handling platform; the two cryostats suspended from the bar of the travelling crane which has a 170 ton carrying capacity. The chamber proper, not dismantled, is inside the shielding.

  20. Bubble-induced cave collapse.

    Directory of Open Access Journals (Sweden)

    Lakshika Girihagama

    Full Text Available Conventional wisdom among cave divers is that submerged caves in aquifers, such as in Florida or the Yucatan, are unstable due to their ever-growing size from limestone dissolution in water. Cave divers occasionally noted partial cave collapses occurring while they were in the cave, attributing this to their unintentional (and frowned upon physical contact with the cave walls or the aforementioned "natural" instability of the cave. Here, we suggest that these cave collapses do not necessarily result from cave instability or contacts with walls, but rather from divers bubbles rising to the ceiling and reducing the buoyancy acting on isolated ceiling rocks. Using familiar theories for the strength of flat and arched (un-cracked beams, we first show that the flat ceiling of a submerged limestone cave can have a horizontal expanse of 63 meters. This is much broader than that of most submerged Florida caves (~ 10 m. Similarly, we show that an arched cave roof can have a still larger expanse of 240 meters, again implying that Florida caves are structurally stable. Using familiar bubble dynamics, fluid dynamics of bubble-induced flows, and accustomed diving practices, we show that a group of 1-3 divers submerged below a loosely connected ceiling rock will quickly trigger it to fall causing a "collapse". We then present a set of qualitative laboratory experiments illustrating such a collapse in a circular laboratory cave (i.e., a cave with a circular cross section, with concave and convex ceilings. In these experiments, a metal ball represented the rock (attached to the cave ceiling with a magnet, and the bubbles were produced using a syringe located at the cave floor.

  1. Photon Bubbles in Accretion Discs

    OpenAIRE

    Gammie, Charles F.

    1998-01-01

    We show that radiation dominated accretion discs are likely to suffer from a ``photon bubble'' instability similar to that described by Arons in the context of accretion onto neutron star polar caps. The instability requires a magnetic field for its existence. In an asymptotic regime appropriate to accretion discs, we find that the overstable modes obey the remarkably simple dispersion relation \\omega^2 = -i g k F(B,k). Here g is the vertical gravitational acceleration, B the magnetic field, ...

  2. Pellino-1 promotes lung carcinogenesis via the stabilization of Slug and Snail through K63-mediated polyubiquitination

    Science.gov (United States)

    Jeon, Yoon Kyung; Kim, Chung Kwon; Hwang, Kyung Rim; Park, Hye-Young; Koh, Jaemoon; Chung, Doo Hyun; Lee, Chang-Woo; Ha, Geun-Hyoung

    2017-01-01

    Pellino-1 is an E3 ubiquitin ligase acting as a critical mediator for a variety of immune receptor signaling pathways, including Toll-like receptors, interleukin-1 receptor and T-cell receptors. We recently showed that the Pellino-1-transgenic (Tg) mice developed multiple tumors with different subtypes in hematolymphoid and solid organs. However, the molecular mechanism underlying the oncogenic role of Pellino-1 in solid tumors remains unknown. Pellino-1-Tg mice developed adenocarcinoma in the lungs, and Pellino-1 expression was higher in human lung adenocarcinoma cell lines compared with non-neoplastic bronchial epithelial cell lines. Pellino-1 overexpression increased the cell proliferation, survival, colony formation, invasion and migration of lung adenocarcinoma cells, whereas Pellino-1 knock-down showed the opposite effect. Pellino-1 overexpression activated PI3K/Akt and ERK signaling pathways and elicited an epithelial–mesenchymal transition (EMT) phenotype of lung adenocarcinoma cells. Pellino-1-mediated EMT was demonstrated through morphology, the upregulation of Vimentin, Slug and Snail expression and the downregulation of E-cadherin and β-catenin expression. Notably, Pellino-1 had a direct effect on the overexpression of Snail and Slug through Lys63-mediated polyubiquitination and the subsequent stabilization of these proteins. Pellino-1 expression level was significantly correlated with Snail and Slug expression in human lung adenocarcinoma tissues, and lung tumors from Pellino-1-Tg mice showed Snail and Slug overexpression. The Pellino-1-mediated increase in the migration of lung adenocarcinoma cells was mediated by Snail and Slug expression. Taken together, these results show that Pellino-1 contributes to lung tumorigenesis by inducing overexpression of Snail and Slug and promoting EMT. Pellino-1 might be a potential therapeutic target for lung cancer. PMID:28009353

  3. Integrated Proteomics and Genomics Analysis Reveals a Novel Mesenchymal to Epithelial Reverting Transition in Leiomyosarcoma through Regulation of Slug*

    Science.gov (United States)

    Yang, Jilong; Eddy, James A.; Pan, Yuan; Hategan, Andrea; Tabus, Ioan; Wang, Yingmei; Cogdell, David; Price, Nathan D.; Pollock, Raphael E.; Lazar, Alexander J. F.; Hunt, Kelly K.; Trent, Jonathan C.; Zhang, Wei

    2010-01-01

    Leiomyosarcoma is one of the most common mesenchymal tumors. Proteomics profiling analysis by reverse-phase protein lysate array surprisingly revealed that expression of the epithelial marker E-cadherin (encoded by CDH1) was significantly elevated in a subset of leiomyosarcomas. In contrast, E-cadherin was rarely expressed in the gastrointestinal stromal tumors, another major mesenchymal tumor type. We further sought to 1) validate this finding, 2) determine whether there is a mesenchymal to epithelial reverting transition (MErT) in leiomyosarcoma, and if so 3) elucidate the regulatory mechanism responsible for this MErT. Our data showed that the epithelial cell markers E-cadherin, epithelial membrane antigen, cytokeratin AE1/AE3, and pan-cytokeratin were often detected immunohistochemically in leiomyosarcoma tumor cells on tissue microarray. Interestingly, the E-cadherin protein expression was correlated with better survival in leiomyosarcoma patients. Whole genome microarray was used for transcriptomics analysis, and the epithelial gene expression signature was also associated with better survival. Bioinformatics analysis of transcriptome data showed an inverse correlation between E-cadherin and E-cadherin repressor Slug (SNAI2) expression in leiomyosarcoma, and this inverse correlation was validated on tissue microarray by immunohistochemical staining of E-cadherin and Slug. Knockdown of Slug expression in SK-LMS-1 leiomyosarcoma cells by siRNA significantly increased E-cadherin; decreased the mesenchymal markers vimentin and N-cadherin (encoded by CDH2); and significantly decreased cell proliferation, invasion, and migration. An increase in Slug expression by pCMV6-XL5-Slug transfection decreased E-cadherin and increased vimentin and N-cadherin. Thus, MErT, which is mediated through regulation of Slug, is a clinically significant phenotype in leiomyosarcoma. PMID:20651304

  4. Performance analysis of new type grid-tied inverter-Aalborg Inverter

    DEFF Research Database (Denmark)

    Wu, Weimin; Wang, Zhen; Ji, Junhao;

    2014-01-01

    Aalborg Inverter is a grid-tied DC/AC inverter. In order to optimize the design, its power losses are analyzed in detail, combined with a description of the single-phase operating principle and the modulation strategy. A 2 kW / 220 V experimental prototype is constructed to verify the theoretical...

  5. Snail and Slug, key regulators of TGF-β-induced EMT, are sufficient for the induction of single-cell invasion.

    Science.gov (United States)

    Naber, Hildegonda P H; Drabsch, Yvette; Snaar-Jagalska, B Ewa; ten Dijke, Peter; van Laar, Theo

    2013-05-24

    TGF-β plays a dual role in cancer; in early stages it inhibits tumor growth, whereas later it promotes invasion and metastasis. TGF-β is thought to be pro-invasive by inducing epithelial-to-mesenchymal transition (EMT) via induction of transcriptional repressors, including Slug and Snail. In this study, we investigated the role of Snail and Slug in TGF-β-induced invasion in an in vitro invasion assay and in an embryonic zebrafish xenograft model. Ectopic expression of Slug or Snail promoted invasion of single, rounded amoeboid cells in vitro. In an embryonic zebrafish xenograft model, forced expression of Slug and Snail promoted single cell invasion and metastasis. Slug and Snail are sufficient for the induction of single-cell invasion in an in vitro invasion assay and in an embryonic zebrafish xenograft model. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Snail and Slug collaborate on EMT and tumor metastasis through miR-101-mediated EZH2 axis in oral tongue squamous cell carcinoma.

    Science.gov (United States)

    Zheng, Min; Jiang, Ya-ping; Chen, Wei; Li, Kai-de; Liu, Xin; Gao, Shi-yu; Feng, Hao; Wang, Sha-sha; Jiang, Jian; Ma, Xiang-rui; Cen, Xiao; Tang, Ya-jie; Chen, Yu; Lin, Yun-feng; Tang, Ya-ling; Liang, Xin-hua

    2015-03-30

    microRNAs(miRNAs) can regulate epithelial-mesenchymal transition (EMT) through transcription factors, however, little is known whether EMT transcription factors can modulate miRNAs and further induce EMT and cancer metastasis. Here we show that overexpression of Snail and Slug leads to a mesenchymal phenotype and morphology and enhances cell invasion along with stem cell properties in squamous cell carcinoma of oral tongue (OTSCC) cells. Repression of miR-101 expression by Snail and Slug is essential for Snail/Slug-induced malignant phenotypes. The suppression of miR-101 subsequently activates EZH2, the sole histone methyltransferase, inducing EMT, migration and invasion of OTSCC cells. Importantly, co-overexpression of Slug and Snail correlates with poor survival and elevated EZH2 expression in two independent patient cohorts of OTSCC specimens. These findings defined a Snail and Slug/miR-101/EZH2 pathway as a novel regulatory axis of EMT-mediated-microRNA signaling.

  7. Simple improvements to classical bubble nucleation models

    CERN Document Server

    Tanaka, Kyoko K; Angélil, Raymond; Diemand, Jürg

    2015-01-01

    We revisit classical nucleation theory (CNT) for the homogeneous bubble nucleation rate and improve the classical formula using a new prefactor in the nucleation rate. Most of the previous theoretical studies have used the constant prefactor determined by the bubble growth due to the evaporation process from the bubble surface. However, the growth of bubbles is also regulated by the thermal conduction, the viscosity, and the inertia of liquid motion. These effects can decrease the prefactor significantly, especially when the liquid pressure is much smaller than the equilibrium one. The deviation in the nucleation rate between the improved formula and the CNT can be as large as several orders of magnitude. Our improved, accurate prefactor and recent advances in molecular dynamics simulations and laboratory experiments for argon bubble nucleation enable us to precisely constrain the free energy barrier for bubble nucleation. Assuming the correction to the CNT free energy is of the functional form suggested by T...

  8. Single DNA denaturation and bubble dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, Ralf [Physics Department, Technical University of Munich, James Franck Strasse, 85747 Garching (Germany); Ambjoernsson, Tobias [Chemistry Department, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Hanke, Andreas [Department of Physics and Astronomy, University of Texas, 80 Fort Brown, Brownsville (United States); Fogedby, Hans C [Department of Physics and Astronomy, University of Arhus, Ny Munkegade, 8000 Arhus C (Denmark)], E-mail: metz@ph.tum.de

    2009-01-21

    While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation bubbles and selectively single-stranded DNA binding proteins.

  9. Bubbles Rising Through a Soft Granular Material

    Science.gov (United States)

    Le Mestre, Robin; MacMinn, Chris; Lee, Sungyon

    2016-11-01

    Bubble migration through a soft granular material involves a strong coupling between the bubble dynamics and the deformation of the material. This is relevant to a variety of natural processes such as gas venting from sediments and gas exsolution from magma. Here, we study this process experimentally by injecting air bubbles into a quasi-2D packing of soft hydrogel beads and measuring the size, speed, and morphology of the bubbles as they rise due to buoyancy. Whereas previous work has focused on deformation resisted by intergranular friction, we focus on the previously inaccessible regime of deformation resisted by elasticity. At low confining stress, the bubbles are irregular and rounded, migrating via local rearrangement. At high confining stress, the bubbles become unstable and branched, migrating via pathway opening. The authors thank The Royal Society for support (International Exchanges Ref IE150885).

  10. Bernoulli Suction Effect on Soap Bubble Blowing?

    Science.gov (United States)

    Davidson, John; Ryu, Sangjin

    2015-11-01

    As a model system for thin-film bubble with two gas-liquid interfaces, we experimentally investigated the pinch-off of soap bubble blowing. Using the lab-built bubble blower and high-speed videography, we have found that the scaling law exponent of soap bubble pinch-off is 2/3, which is similar to that of soap film bridge. Because air flowed through the decreasing neck of soap film tube, we studied possible Bernoulli suction effect on soap bubble pinch-off by evaluating the Reynolds number of airflow. Image processing was utilized to calculate approximate volume of growing soap film tube and the volume flow rate of the airflow, and the Reynolds number was estimated to be 800-3200. This result suggests that soap bubbling may involve the Bernoulli suction effect.

  11. Manipulating bubbles with secondary Bjerknes forces

    Energy Technology Data Exchange (ETDEWEB)

    Lanoy, Maxime [Institut Langevin, ESPCI ParisTech, CNRS (UMR 7587), PSL Research University, 1 rue Jussieu, 75005 Paris (France); Laboratoire Matière et Systèmes Complexes, Université Paris-Diderot, CNRS (UMR 7057), 10 rue Alice Domon et Léonie Duquet, 75013 Paris (France); Derec, Caroline; Leroy, Valentin [Laboratoire Matière et Systèmes Complexes, Université Paris-Diderot, CNRS (UMR 7057), 10 rue Alice Domon et Léonie Duquet, 75013 Paris (France); Tourin, Arnaud [Institut Langevin, ESPCI ParisTech, CNRS (UMR 7587), PSL Research University, 1 rue Jussieu, 75005 Paris (France)

    2015-11-23

    Gas bubbles in a sound field are submitted to a radiative force, known as the secondary Bjerknes force. We propose an original experimental setup that allows us to investigate in detail this force between two bubbles, as a function of the sonication frequency, as well as the bubbles radii and distance. We report the observation of both attractive and, more interestingly, repulsive Bjerknes force, when the two bubbles are driven in antiphase. Our experiments show the importance of taking multiple scatterings into account, which leads to a strong acoustic coupling of the bubbles when their radii are similar. Our setup demonstrates the accuracy of secondary Bjerknes forces for attracting or repealing a bubble, and could lead to new acoustic tools for noncontact manipulation in microfluidic devices.

  12. Mechanism of bubble detachment from vibrating walls

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjun; Park, Jun Kwon, E-mail: junkeun@postech.ac.kr; Kang, Kwan Hyoung [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of); Kang, In Seok [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of)

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  13. Tube erosion in bubbling fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Levy, E.K. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center; Stallings, J.W. [Electric Power Research Inst., Palo Alto, CA (United States)

    1991-12-31

    This paper reports on experimental and theoretical studies that were preformed of the interaction between bubbles and tubes and tube erosion in fluidized beds. The results are applicable to the erosion of horizontal tubes in the bottom row of a tube bundle in a bubbling bed. Cold model experimental data show that erosion is caused by the impact of bubble wakes on the tubes, with the rate of erosion increasing with the velocity of wake impact with the particle size. Wake impacts resulting from the vertical coalescence of pairs of bubbles directly beneath the tube result in particularly high rates of erosion damage. Theoretical results from a computer simulation of bubbling and erosion show very strong effects of the bed geometry and bubbling conditions on computed rates of erosion. These results show, for example, that the rate of erosion can be very sensitive to the vertical location of the bottom row of tubes with respect to the distributor.

  14. Ostwald Ripening in Multiple-Bubble Nuclei

    CERN Document Server

    Watanabe, Hiroshi; Inaoka, Hajime; Ito, Nobuyasu

    2014-01-01

    The ostwald ripening of bubbles is studied by molecular dynamics simulations involving up to 679 million Lennard-Jones particles. Many bubbles appear after depressurizing a system that is initially maintained in the pure-liquid phase, and the coarsening of bubbles follows. The self-similarity of the bubble-size distribution function predicted by Lifshitz-Slyozov-Wagner theory is directly confirmed. The total number of bubbles decreases asymptotically as $t^{-x}$ with scaling exponent $x$. As the initial temperature increases, the exponent changes from $x=3/2$ to $1$, which implies that the growth of bubbles changes from interface-limited (the $t^{1/2}$ law) to diffusion-limited (the $t^{1/3}$ law) growth.

  15. Ostwald ripening in multiple-bubble nuclei.

    Science.gov (United States)

    Watanabe, Hiroshi; Suzuki, Masaru; Inaoka, Hajime; Ito, Nobuyasu

    2014-12-21

    The Ostwald ripening of bubbles is studied by molecular dynamics simulations involving up to 679 × 10(6) Lennard-Jones particles. Many bubbles appear after depressurizing a system that is initially maintained in the pure-liquid phase, and the coarsening of bubbles follows. The self-similarity of the bubble-size distribution function predicted by Lifshitz-Slyozov-Wagner theory is directly confirmed. The total number of bubbles decreases asymptotically as t(-x) with scaling exponent x. As the initial temperature increases, the exponent changes from x = 3/2 to 1, which implies that the growth of bubbles changes from interface-limited (the t(1/2) law) to diffusion-limited (the t(1/3) law) growth.

  16. CFD Analysis of a Slug Mixing Experiment Conducted on a VVER-1000 Model

    Directory of Open Access Journals (Sweden)

    F. Moretti

    2009-01-01

    Full Text Available A commercial CFD code was applied, for validation purposes, to the simulation of a slug mixing experiment carried out at OKB “Gidropress” scaled facility in the framework of EC TACIS project R2.02/02: “Development of safety analysis capabilities for VVER-1000 transients involving spatial variations of coolant properties (temperature or boron concentration at core inlet.” Such experimental model reproduces a VVER-1000 nuclear reactor and is aimed at investigating the in-vessel mixing phenomena. The addressed experiment involves the start-up of one of the four reactor coolant pumps (the other three remaining idle, and the presence of a tracer slug on the starting loop, which is thus transported to the reactor pressure vessel where it mixes with the clear water. Such conditions may occur in a boron dilution scenario, hence the relevance of the addressed phenomena for nuclear reactor safety. Both a pretest and a posttest CFD simulations of the mentioned experiment were performed, which differ in the definition of the boundary conditions (based either on nominal quantities or on measured quantities, resp.. The numerical results are qualitatively and quantitatively analyzed and compared against the measured data in terms of space and time tracer distribution at the core inlet. The improvement of the results due to the optimization of the boundary conditions is evidenced, and a quantification of the simulation accuracy is proposed.

  17. A Review of the Multilevel Slug Test for Characterizing Aquifer Heterogeneity

    Directory of Open Access Journals (Sweden)

    Chia-Shyun Chen

    2012-01-01

    Full Text Available All aquifers are heterogeneous to a certain degree. The spatial distribution of hydraulic conductivity K(x, y, z, or aquifer heterogeneity, significantly influences the groundwater flow movement and associated solute transport. Of particular importance in designing an in-situ remediation plan is a knowledge of low-K layers because they are less accessible to remedial agents and form a bottleneck in remediation. The characterization of aquifer heterogeneity is essential to the solution of many practical and scientific groundwater problems. This article reviews the field technique using the multilevel slug test (MLST, which determines a series of K estimates at depths of interest in a well by making use of a double-packer system. The K(z obtained manifests the vertical variation of hydraulic conductivity in the vicinity of the test well, and the combination of K(z from different wells gives rise to a three-dimensional description of K(x, y, z. The MLST response is rather sensitive to hydraulic conductivity variation; e.g., it is oscillatory for highly permeable conditions (K > 5 × 10-4 m s-1 and a nonoscillatory for K < 5 × 10-4 m s-1. In this article we discuss the instrumentation of the double-packer system, the implementation of the depth-specific slug test, the data analysis methods for a spectrum of response characteristics usually observed in the field, and field applications of the MLST.

  18. Wire-mesh and ultrasound techniques applied for the characterization of gas-liquid slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Ofuchi, Cesar Y.; Sieczkowski, Wytila Chagas; Neves Junior, Flavio; Arruda, Lucia V.R.; Morales, Rigoberto E.M.; Amaral, Carlos E.F.; Silva, Marco J. da [Federal University of Technology of Parana, Curitiba, PR (Brazil)], e-mails: ofuchi@utfpr.edu.br, wytila@utfpr.edu.br, neves@utfpr.edu.br, lvrarruda@utfpr.edu.br, rmorales@utfpr.edu.br, camaral@utfpr.edu.br, mdasilva@utfpr.edu.br

    2010-07-01

    Gas-liquid two-phase flows are found in a broad range of industrial applications, such as chemical, petrochemical and nuclear industries and quite often determine the efficiency and safety of process and plants. Several experimental techniques have been proposed and applied to measure and quantify two-phase flows so far. In this experimental study the wire-mesh sensor and an ultrasound technique are used and comparatively evaluated to study two-phase slug flows in horizontal pipes. The wire-mesh is an imaging technique and thus appropriated for scientific studies while ultrasound-based technique is robust and non-intrusive and hence well suited for industrial applications. Based on the measured raw data it is possible to extract some specific slug flow parameters of interest such as mean void fraction and characteristic frequency. The experiments were performed in the Thermal Sciences Laboratory (LACIT) at UTFPR, Brazil, in which an experimental two-phase flow loop is available. The experimental flow loop comprises a horizontal acrylic pipe of 26 mm diameter and 9 m length. Water and air were used to produce the two phase flow under controlled conditions. The results show good agreement between the techniques. (author)

  19. Chondrogenic potential of human mesenchymal stem cells and expression of Slug transcription factor.

    Science.gov (United States)

    Brini, Anna T; Niada, Stefania; Lambertini, Elisabetta; Torreggiani, Elena; Arrigoni, Elena; Lisignoli, Gina; Piva, Roberta

    2015-06-01

    The scientific literature rarely reports experimental failures or inconsistent outcomes in the induction of cell differentiation; however, researchers commonly experience poor or unsuccessful responses to differentiating agents when culturing stem cells. One way of investigating the underlying reasons for such responses is to look at the basal expression levels of specific genes in multipotent stem cells before the induction of differentiation. In addition to shedding light on the complex properties of stem cells and the molecular modulation of differentiation pathways, this strategy can also lead to the development of important time- and money-saving tools that aid the efficient selection of cellular specimens--in this case, stem cells that are more prone to differentiate towards specific lineages and are therefore more suitable for cell-based therapeutic protocols in regenerative medicine. To address this latter aspect, this study focused on understanding the reasons why some human mesenchymal stem cell (hMSC) samples are less efficient at differentiating towards chondrogenesis. This study shows that analysis of the basal expression levels of Slug, a negative regulator of chondrogenesis in hMSC, provides a rapid and simple tool for distinguishing stem cell samples with the potential to form a cartilage-like matrix, and that are therefore suitable for cartilage tissue engineering. It is shown that high basal levels of Slug prevent the chondrogenic differentiation of hMSCs, even in the presence of transforming growth factor-β and elevated levels of Sox9.

  20. Drought tolerance in eggs and juveniles of the Iberian slug, Arion lusitanicus.

    Science.gov (United States)

    Slotsbo, Stine; Fisker, Karina Vincents; Hansen, Lars Monrad; Holmstrup, Martin

    2011-12-01

    The spread of invasive species is an increasing problem world wide. The invasive slug Arion lusitanicus has spread to most parts of Europe, where it often is considered as a serious pest. There is a need for better knowledge of its ecophysiology to be able to predict the effect of climatic factors, such as temperature and humidity on the population dynamics and abundance. The aim of the present study was to assemble data on the water balance and drought tolerance of eggs and juveniles of A. lusitanicus. Both eggs and juveniles had little capacity to prevent evaporative water loss and lost water when the ambient humidity fell below 99.8 and 99.5%, respectively. The water conductance of the cuticle of juveniles was 242 μg cm(-2) h(-1) mmHg(-1) and resembles that of other slug species. Both eggs and juveniles of A. lusitanicus tolerate a substantial water loss. There was no difference in water loss resistance between eggs and juveniles, but the eggs were slightly more tolerant to water loss than the juveniles. The percent water loss causing 50% mortality was 72% for the juveniles and 81% for the eggs. Despite A. lusitanicus' tolerance of substantial water loss, its survival depends on humid habitats.

  1. Congruence between starch gel and polyacrylamide gel electrophoresis in detecting allozyme variation in pulmonate land slugs.

    Science.gov (United States)

    Geenen, Sofie; Jordaens, Kurt; Castilho, Rita; Backeljau, Thierry

    2003-02-01

    The predominantly selfing slug species Arion (Carinarion) fasciatus, A. (C.) silvaticus and A. (C.) circumscriptus are native in Europe and have been introduced into North America, where each species consists of a single, homozygous multilocus genotype (strain), as defined by starch gel electrophoresis (SGE) of allozymes. In Europe, the "one strain per species" hypothesis does not hold since polyacrylamide gel electrophoresis (PAGE) of allozymes uncovered 46 strains divided over the three species. However, electrophoretic techniques may differ in their ability to detect allozyme variation. Therefore, several Carinarion populations from both continents were screened by applying the two techniques simultaneously on the same individual slugs and enzyme loci. SGE and PAGE yielded exactly the same results, so that the different degree of variation in North American and European populations cannot be attributed to differences in resolving power between SGE and PAGE. We found four A. (C.) silvaticus strains in North America indicating that in this region the "one strain per species" hypothesis also cannot be maintained. Hence, the discrepancies between previous electrophoretic studies on Carinarion are most likely due to sampling artefacts and possible founder effects.

  2. Wire-mesh and ultrasound techniques applied for the characterization of gas-liquid slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Ofuchi, Cesar Y.; Sieczkowski, Wytila Chagas; Neves Junior, Flavio; Arruda, Lucia V.R.; Morales, Rigoberto E.M.; Amaral, Carlos E.F.; Silva, Marco J. da [Federal University of Technology of Parana, Curitiba, PR (Brazil)], e-mails: ofuchi@utfpr.edu.br, wytila@utfpr.edu.br, neves@utfpr.edu.br, lvrarruda@utfpr.edu.br, rmorales@utfpr.edu.br, camaral@utfpr.edu.br, mdasilva@utfpr.edu.br

    2010-07-01

    Gas-liquid two-phase flows are found in a broad range of industrial applications, such as chemical, petrochemical and nuclear industries and quite often determine the efficiency and safety of process and plants. Several experimental techniques have been proposed and applied to measure and quantify two-phase flows so far. In this experimental study the wire-mesh sensor and an ultrasound technique are used and comparatively evaluated to study two-phase slug flows in horizontal pipes. The wire-mesh is an imaging technique and thus appropriated for scientific studies while ultrasound-based technique is robust and non-intrusive and hence well suited for industrial applications. Based on the measured raw data it is possible to extract some specific slug flow parameters of interest such as mean void fraction and characteristic frequency. The experiments were performed in the Thermal Sciences Laboratory (LACIT) at UTFPR, Brazil, in which an experimental two-phase flow loop is available. The experimental flow loop comprises a horizontal acrylic pipe of 26 mm diameter and 9 m length. Water and air were used to produce the two phase flow under controlled conditions. The results show good agreement between the techniques. (author)

  3. Hydrocarbon recovery comprising injecting a slug comprising oil soluble alkoxylated surfactants from lignin

    Energy Technology Data Exchange (ETDEWEB)

    Naae, D.G.; DaGue, M.G.; Dunn, N.G.

    1993-07-27

    A method is described of recovering hydrocarbons from an underground hydrocarbon formation penetrated by at least one injection well and at least one production well, which comprises: injecting into the formation through an injection well a surfactant slug comprising about 0.1% to about 10% by weight of oil soluble surfactants produced from lignin, said oil soluble surfactants produced by placing lignin in contact with water, converting the lignin into relatively low molecular weight lignin phenols by reducing the lignin in the presence of a reducing agent of carbon monoxide or hydrogen, said reduction occurring at a temperature greater than about 200 C and a pressure greater than about 100 psi, recovering the oil soluble lignin phenols from the reaction mixture, alkoxylating the lignin phenols by reacting the lignin phenols with an a-olefin epoxide having about 6 to about 20 carbon atoms at about 100 to about 200 C for about 1 to about 3 hours in an organic solvent, and changing the alkoxylated lignin phenols into oil soluble lignin surfactants by a reaction selected from the group consisting of sulfonation, sulfation, and alkoxysulfation; injecting into the formation through the injection well a drive fluid to push the surfactant slug towards a production well; and recovering hydrocarbons at the production well.

  4. Binary Schemes of Vapor Bubble Growth

    Science.gov (United States)

    Zudin, Yu. B.

    2015-05-01

    A problem on spherically symmetric growth of a vapor bubble in an infi nite volume of a uniformly superheated liquid is considered. A description of the limiting schemes of bubble growth is presented. A binary inertial-thermal bubble growth scheme characterized by such specifi c features as the "three quarters" growth law and the effect of "pressure blocking" in a vapor phase is considered.

  5. ACOUSTIC MEASUREMENTS BUBBLES IN BIOLOGICAL TIESSURE

    Institute of Scientific and Technical Information of China (English)

    CHAHINE Georges L.; TANGUAY Michel; LORAINE Greg

    2009-01-01

    An acoustic based instrument,the ABS Acoustic Bubble Spectrometer(R)(C)(ABS),was investigated for the detection and quantification of bubbles in biological media.These include viscoelastic media(blood),materials of varying density(bone in tissue),non-homogenous distribution of bubbles(intravenous bubbly flow),and bubbles migrating in tissue(decompression sickness,DCS).The performance of the ABS was demonstrated in a series of laboratory experiments.Validation of the code was performed using a viscoelastic polymer solution,Polyox,in which the bubble size distribution and void fraction were determined by ABS measurements and with image analysis of high speed videos.These tests showed that the accuracy of the ABS was not significantly affected by viscoelasticity for bubbles smaller than 200 microns.The ABS detection and measurement of non-homogenous bubble distributions was demonstrated using a bubbly flow through a simulated vein surrounded by tissue.The scatter of acoustic signals due to bones in the acoustic pathway was also investigated.These in-vitro experiments were done using meat(beef)as a tissue simulant.Decompression experiments were done using beef meat which was held underwater at high pressure(9.9 atm)then rapidly decompressed.Bubble size distributions and void fraction calculations in these experiments were then validated using image analysis of high speed video.In addition,preliminary experiments were performed with the US Navy Medical Research Center,demonstrating the utility of the modified ABS system in detecting the evolution of bubbles in swine undergoing decompression sickness(DCS).These results indicate that the ABS may be used to detect and quantify the evolution of bubbles in-vivo and aid in the monitoring of DCS.

  6. Curvature and bubble convergence of harmonic maps

    CERN Document Server

    Kokarev, Gerasim

    2010-01-01

    We explore geometric aspects of bubble convergence for harmonic maps. More precisely, we show that the formation of bubbles is characterised by the local excess of curvature on the target manifold. We give a universal estimate for curvature concentration masses at each bubble point and show that there is no curvature loss in the necks. Our principal hypothesis is that the target manifold is Kaehler.

  7. Shock propagation in polydisperse bubbly flows

    OpenAIRE

    Ando, Keita; Colonius, Tim; Brennen, Christopher E.

    2009-01-01

    The effect of distributed bubble size on shock propagation in homogeneous bubbly liquids is computed using a continuum two-phase model. An ensemble-averaging technique is employed to derive the statistically averaged equations and a finite-volume method is used to solve the model equations. The bubble dynamics are incorporated using a Rayleigh-Plesset-type equation which includes the effects of heat transfer, liquid viscosity and compressibility. For the case of monodispe...

  8. Finite-Amplitude Vibration of a Bubble

    Institute of Scientific and Technical Information of China (English)

    QIAN Zu-Wen; XIAO Ling

    2003-01-01

    The Rayleigh-Plesset equation for bubble vibration is modified. The numerical solution of new equation is obtained by means of the symbolic computation programme. The acceleration of the h'quid on the surface of the bubble, or pressure in the bubble, displays much intense 8-impulse with a very short duration from ns to ps. Suggestions for developing the measurements of sonoluminescence and cavitation fusion (if any) are presented.

  9. Online recognition of the multiphase flow regime and study of slug flow in pipeline

    Science.gov (United States)

    Liejin, Guo; Bofeng, Bai; Liang, Zhao; Xin, Wang; Hanyang, Gu

    2009-02-01

    single sensor performance. Among various flow patterns of gas-liquid flow, slug flow occurs frequently in the petroleum, chemical, civil and nuclear industries. In the offshore oil and gas field, the maximum slug length and its statistical distribution are very important for the design of separator and downstream processing facility at steady state operations. However transient conditions may be encountered in the production, such as operational upsets, start-up, shut-down, pigging and blowdown, which are key operational and safety issues related to oil field development. So it is necessary to have an understanding the flow parameters under transient conditions. In this paper, the evolution of slug length along a horizontal pipe in gas-liquid flow is also studied in details and then an experimental study of flowrate transients in slug flow is provided. Also, the special gas-liquid flow phenomena easily encountered in the life span of offshore oil fields, called severe slugging, is studied experimentally and some results are presented.

  10. Gas Holdups of Small and Large Bubbles in a Large-scale Bubble Column with Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    JIN Hai-bo; YANG Suo-he; ZHANG Tong-wang; TONG Ze-min

    2004-01-01

    Gas holdups of large bubbles and small bubbles were measured by means of dynamic gas disengagement approach in the pressured bubble column with a diameter of 0. 3 m and a height of 6. 6 m. The effects of superficial gas velocity, liquid surface tension, liquid viscosity andsystem pressure on gas holdups of small bubbles and large bubbles were investigated. The holdup of large bubbles increases and the holdup of small bubbles decreases with an increase of liquid viscosity. Meanwhile, the holdup of large bubbles decreases with increasing the system pressure. A correlation for the holdup of small bubbles was obtained from the experimental data.

  11. Addressable inverter matrix for process and device characterization

    Science.gov (United States)

    Buehler, M. G.; Sayah, H. R.

    1985-01-01

    The addressable inverter matrix consists of 222 inverters each accessible with the aid of a shift register. The structure has proven useful in characterizing the variability of inverter transfer curves and in diagnosing processing faults. For good 3-micron CMOS bulk inverters investigated, the percent standard deviation of the inverter threshold voltage was less than one percent and the inverter gain (the slope of the inverter transfer curve at the inverter threshold vltage) was less than 3 percent. The average noise margin for the inverters was near 2 volts for a power supply voltage of 5 volts. The specific faults studied included undersize pull-down transistor widths and various open contacts in the matrix.

  12. Radiological follow-up of inverted papilloma

    Energy Technology Data Exchange (ETDEWEB)

    Petit, P.; Vivarrat-Perrin, L.; Champsaur, P.; Juhan, V.; Chagnaud, C.; Vidal, V.; Gaubert, J.Y.; Bartoli, J.M.; Moulin, G. [Department of Radiology, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France); Dessi, P.; Zanaret, M. [Department of Head and Neck Surgery, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France)

    2000-07-01

    The aim of this study was to describe cross-sectional imaging features of recurrent papilloma of the nasal fossa and paranasal sinuses and to evaluate the role of MR and CT in the postoperative follow-up of this lesion. Magnetic resonance imaging and CT of ten patients who presented recurrence of inverted papilloma were reviewed and correlated to initial imaging, endoscopy, and surgical reports. Imaging patterns of recurrent inverted papilloma are identical to those of initial tumors and recurrence location is closely related to the site of the former lesion. Magnetic resonance is more efficient than CT for the diagnosis and evaluation of extensions. Magnetic resonance supplies the deficiencies of endoscopy in case of extensions to the frontal sinus or the lateral recess of the antrum, especially if mucosal hyperplasia or sinusitis is associated. Magnetic resonance imaging is the first imaging modality to perform in the follow-up after removal of inverted papilloma. (orig.)

  13. Power inverter implementing phase skipping control

    Science.gov (United States)

    Somani, Utsav; Amirahmadi, Ahmadreza; Jourdan, Charles; Batarseh, Issa

    2016-10-18

    A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level.

  14. An SCR inverter for electric vehicles

    Science.gov (United States)

    Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.

    1980-01-01

    An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.

  15. Spectroscopic characteristic of conical bubble luminescence

    Institute of Scientific and Technical Information of China (English)

    Chen Qi-Dai; Fu Li-Min; Ai Xi-Cheng; Zhang Jian-Ping; Wang Long

    2005-01-01

    The conical bubble sonoluminescence (CBSL) from the collapse of the bubble was observed in an improved Utube apparatus. The emitted light energy of a single CBSL flash was measured to be ~ 1.4mJ. The pulse width was about 100μs. The spectra of luminescence were continuum superimposed with the spectral bands from the excitedstate C2, CN and CH. The CBSL provides a link between the light emission of the single-bubble and the multi-bubble sonoluminescence (SBSL and MBSL).

  16. Band gaps in bubble phononic crystals

    Directory of Open Access Journals (Sweden)

    V. Leroy

    2016-12-01

    Full Text Available We investigate the interaction between Bragg and hybridization effects on the band gap properties of bubble phononic crystals. These latter consist of air cavities periodically arranged in an elastomer matrix and are fabricated using soft-lithography techniques. Their transmission properties are affected by Bragg effects due to the periodicity of the structure as well as hybridization between the propagating mode of the embedding medium and bubble resonance. The hybridization gap survives disorder while the Bragg gap requires a periodic distribution of bubbles. The distance between two bubble layers can be tuned to make the two gaps overlap or to create a transmission peak in the hybridization gap.

  17. Bubble burst as jamming phase transition

    CERN Document Server

    Nishinari, Katsuhiro; Saito, Yukiko Umeno; Watanabe, Tsutomu

    2010-01-01

    Recently research on bubble and its burst attract much interest of researchers in various field such as economics and physics. Economists have been regarding bubble as a disorder in prices. However, this research strategy has overlooked an importance of the volume of transactions. In this paper, we have proposed a bubble burst model by focusing the transactions incorporating a traffic model that represents spontaneous traffic jam. We find that the phenomenon of bubble burst shares many similar properties with traffic jam formation by comparing data taken from US housing market. Our result suggests that the transaction could be a driving force of bursting phenomenon.

  18. Living Near de Sitter Bubble Walls

    OpenAIRE

    Cho, Jin-Ho; Nam, Soonkeon

    2006-01-01

    We study various bubble solutions in string/M theories obtained by double Wick rotations of (non-)extremal brane configurations. Typically, the geometry interpolates de Sitter space-time times non-compact extra-dimensional space in the near-bubble wall region and the asymptotic flat Minkowski space-time. These bubble solutions provide nice background geometries reconciling string/M theories with de Sitter space-time. For the application of these solutions to cosmology, we consider multi-bubbl...

  19. Shock Wave Emissions of a Sonoluminescing Bubble

    CERN Document Server

    Holzfuss, J; Billó, M; Holzfuss, Joachim; Ruggeberg, Matthias; Billo, Andreas

    1998-01-01

    A single bubble in water is excited by a standing ultrasound wave. At high intensity the bubble starts to emit light. Together with the emitted light pulse, a shock wave is generated in the liquid at collapse time. The time-dependent velocity of the outward-travelling shock is measured with an imaging technique. The pressure in the shock and in the bubble is shown to have a lower limit of 5500 bars. Visualization of the shock and the bubble at different phases of the acoustic cycle reveals previously unobserved dynamics during stable and unstable sonoluminescence.

  20. Interaction of a bubble and a bubble cluster in an ultrasonic field

    Institute of Scientific and Technical Information of China (English)

    Wang Cheng-Hui; Cheng Jian-Chun

    2013-01-01

    Using an appropriate approximation,we have formulated the interacting equation of multi-bubble motion for a system of a single bubble and a spherical bubble cluster.The behavior of the bubbles is observed in coupled and uncoupled states.The oscillation of bubbles inside the cluster is in a coupled state.The numerical simulation demonstrates that the secondary Bjerknes force can be influenced by the number density,initial radius,distance,driving frequency,and amplitude of ultrasound.However,if a bubble approaches a bubble cluster of the same initial radii,coupled oscillation would be induced and a repulsive force is evoked,which may be the reason why the bubble cluster can exist steadily.With the increment of the number density of the bubble cluster,a secondary Bjerknes force acting on the bubbles inside the cluster decreases due to the strong suppression of the coupled bubbles.It is shown that there may be an optimal number density for a bubble cluster which can generate an optimal cavitation effect in liquid for a stable driving ultrasound.

  1. 液氢加注系统竖直管道内Taylor气泡的行为特性%Research on Taylor bubble's behavior in vertical tube of liquid hydrogen loading system

    Institute of Scientific and Technical Information of China (English)

    马昕晖; 徐腊萍; 陈景鹏; 宋建军

    2011-01-01

    Because of the experimental difficulty of two-phase flow in a vertical tube for liquid hydroger loading systems, a Taylor bubble movement model in vertical tube were established using modeling and simulation methods. The formation process, size and rising velocity of Taylor bubble fully developed were studied. VOF method was used to track the interface of two-phase flow and CSF model was introduced to calculate the surface tension between two phases. Simulation results show that Taylor bubble is polymerized frotr the small dispersed bubbles, the critical length of the Taylor bubble when the bubbly flow changing to slug flow is smaller than the Taylor bubble in the development, Taylor bubble fully developed is basically increasing in the uniform rate of 0.226 5 m/s.%针对液氢加注系统竖直管道内气液两相流实验化困难的问题,运用建模仿真的方法建立了竖直管道内Taylor气泡的运动模型,对Taylor气泡的形成过程、大小以及充分发展的Taylor气泡上升速度进行了研究.采用VOF方法对气液两相的交界面进行追踪,并引入CSF模型对两相间的表面张力进行计算.仿真结果表明:Taylor气泡是由弥散的小气泡聚合而成,根据泡状流向弹状流转变得出的Taylor气泡的临界长度比处于发展中的Taylor气泡长度要小,充分发展的Taylor气泡基本上以0.226 5 m/s的速度匀速上升.

  2. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory. ©2010 IEEE....... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  3. Maskless inverted pyramid texturization of silicon.

    Science.gov (United States)

    Wang, Yan; Yang, Lixia; Liu, Yaoping; Mei, Zengxia; Chen, Wei; Li, Junqiang; Liang, Huili; Kuznetsov, Andrej; Xiaolong, Du

    2015-06-02

    We discovered a technical solution of such outstanding importance that it can trigger new approaches in silicon wet etching processing and, in particular, photovoltaic cell manufacturing. The so called inverted pyramid arrays, outperforming conventional pyramid textures and black silicon because of their superior light-trapping and structure characteristics, can currently only be achieved using more complex techniques involving lithography, laser processing, etc. Importantly, our data demonstrate a feasibility of inverted pyramidal texturization of silicon by maskless Cu-nanoparticles assisted etching in Cu(NO3)2 / HF / H2O2 / H2O solutions and as such may have significant impacts on communities of fellow researchers and industrialists.

  4. Decoupling Control Strategy for Single Phase SPWM Parallel Inverters

    Institute of Scientific and Technical Information of China (English)

    Shun-Gang Xu; Jian-Ping Xu; Tai-Qiang Cao

    2009-01-01

    A decoupling control strategy of inverter parallel system is proposed based on the equivalent output impedance of single phase voltage source SPWM (sinusoidal pulse width modulation) inverter. The active power and reactive power are calculated in terms of output voltage and current of the inverter, and sent to the other inverters in the parallel system via controller area network (CAN) bus. By calculating and decoupling the circumfluence of the active power and reactive power, the inverters can share load current via the regulation of the reference-signal phase and amplitude. Experimental results of an 110V/2kVA inverter parallel system show the feasibility of the decoupling control strategy.

  5. Banana Slug

    Science.gov (United States)

    First, Lucas

    2009-01-01

    Everyone insists that a person should go to a college that is right for him/her, somewhere that fits who he/she is, a place where a they belong. There are more than 4,000 colleges and universities in this country; how will a person find the one that is right for them? In this article, the author suggests that one should follow the mascot when…

  6. Stationary bubbles: information loss paradox?

    CERN Document Server

    Domènech, Guillem

    2016-01-01

    The main purpose of this work is to build classically stationary bubbles, within the thin-shell formalism, which are unstable under quantum effects; they either collapse into a black hole or expand. Thus, the final state can be thought of a superposition of geometries. We point out that, from a quantum mechanical point of view, there is no issue with a loss of information in such configuration. A classical observer sees a definite geometry and, hence, finds an effective loss of information. Although it does not cover all possible cases, we emphasise the role of semi-classical gravitational effects, mediated by instatons, in alleviating/solving the information loss paradox.

  7. DGP with bubble of nothing

    CERN Document Server

    Izumi, Keisuke

    2014-01-01

    We construct exact solutions with the bubble of nothing in the Dvali-Gabadadze-Porrati(DGP) braneworld model. The configuration with a single brane can be constructed, unlike in the Randall-Sundrum braneworld model. The geometry on the single brane looks like the Einstein-Rosen bridge. We also discuss the junction of multi branes. Surprisingly, even without any artificial matter fields on the branes such as three dimensional tension of the codimension two objects, two branes can be connected in certain configurations. We investigate solutions of multi branes too. The presence of solutions may indicate the semiclassical instability of the models.

  8. Magma mixing enhanced by bubble segregation

    Directory of Open Access Journals (Sweden)

    S. Wiesmaier

    2015-04-01

    Full Text Available That rising bubbles may significantly affect magma mixing paths has already been demon strated by analogue experiments. Here, for the first time, bubble-advection experiments are performed employing volcanic melts at magmatic temperatures. Cylinders of basaltic glass were placed below cylinders of rhyolite glass. Upon melting, interstitial air formed bubbles that rose into the rhyolite melt, thereby entraining tails of basaltic liquid. The formation of plume-like filaments of advected basalt within the rhyolite was characterized by microCT and subsequent high-resolution EMP analyses. Melt entrainment by bubble ascent appears to be an efficient mechanism for mingling volcanic melts of highly contrasting compositions and properties. MicroCT imaging reveals bubbles trailing each other and multiple filaments coalescing into bigger ones. Rheological modelling of the filaments yields viscosities of up to 2 orders of magnitude lower than for the surrounding rhyolitic liquid. Such a viscosity contrast implies that bubbles rising successively are likely to follow this pathway of low resistance that previously ascending bubbles have generated. Filaments formed by multiple bubbles would thus experience episodic replenishment with mafic material. Inevitable implications for the concept of bubble advection in magma mixing include thereby both an acceleration of mixing because of decreased viscous resistance for bubbles inside filaments and non-conventional diffusion systematics because of intermittent supply of mafic material (instead of a single pulse inside a material. Inside the filaments, the mafic material was variably hybridised to andesitic through rhyolitic composition. Compositional profiles alone are ambiguous, however, to determine whether single or multiple bubbles were involved during formation of a filament. Statistical analysis, employing concentration variance as measure of homogenisation, demonstrates that also filaments appearing as single-bubble

  9. Neural basis of economic bubble behavior.

    Science.gov (United States)

    Ogawa, A; Onozaki, T; Mizuno, T; Asamizuya, T; Ueno, K; Cheng, K; Iriki, A

    2014-04-18

    Throughout human history, economic bubbles have formed and burst. As a bubble grows, microeconomic behavior ceases to be constrained by realistic predictions. This contradicts the basic assumption of economics that agents have rational expectations. To examine the neural basis of behavior during bubbles, we performed functional magnetic resonance imaging while participants traded shares in a virtual stock exchange with two non-bubble stocks and one bubble stock. The price was largely deflected from the fair price in one of the non-bubble stocks, but not in the other. Their fair prices were specified. The price of the bubble stock showed a large increase and battering, as based on a real stock-market bust. The imaging results revealed modulation of the brain circuits that regulate trade behavior under different market conditions. The premotor cortex was activated only under a market condition in which the price was largely deflected from the fair price specified. During the bubble, brain regions associated with the cognitive processing that supports order decisions were identified. The asset preference that might bias the decision was associated with the ventrolateral prefrontal cortex and the dorsolateral prefrontal cortex (DLPFC). The activity of the inferior parietal lobule (IPL) was correlated with the score of future time perspective, which would bias the estimation of future price. These regions were deemed to form a distinctive network during the bubble. A functional connectivity analysis showed that the connectivity between the DLPFC and the IPL was predominant compared with other connectivities only during the bubble. These findings indicate that uncertain and unstable market conditions changed brain modes in traders. These brain mechanisms might lead to a loss of control caused by wishful thinking, and to microeconomic bubbles that expand, on the macroscopic scale, toward bust.

  10. Numerical modeling of oscillating Taylor bubbles

    Directory of Open Access Journals (Sweden)

    S. Ambrose

    2016-01-01

    Full Text Available In this study, computational fluid dynamics (CFD modeling is used to simulate Taylor bubbles rising in vertical pipes. Experiments indicate that in large diameter (0.29 m pipes for an air–water system, the bubbles can rise in a oscillatory manner, depending on the method of air injection. The CFD models are able to capture this oscillatory behavior because the air phase is modeled as a compressible ideal gas. Insights into the flow field ahead and behind the bubble during contraction and expansion are shown. For a bubble with an initial pressure equal to the hydrostatic pressure at its nose, no oscillations are seen in the bubble as it rises. If the initial pressure in the bubble is set less than or greater than the hydrostatic pressure then the length of the bubble oscillates with an amplitude that depends on the magnitude of the initial bubble pressure relative to the hydrostatic pressure. The frequency of the oscillations is inversely proportional to the square root of the head of water above the bubble and so the frequency increases as the bubble approaches the water surface. The predicted frequency also depends inversely on the square root of the average bubble length, in agreement with experimental observations and an analytical model that is also presented. In this model, a viscous damping term due to the presence of a Stokes boundary layer for the oscillating cases is introduced for the first time and used to assess the effect on the oscillations of increasing the liquid viscosity by several orders of magnitude.

  11. MATHEMATICAL MODELING OF THE PROCESSES OF RADIATION-CONVECTIVE HEAT EXCHANGE AT HEATING OF STEEL SLUGS IN METHODICAL TRANSFER FURNACES

    Directory of Open Access Journals (Sweden)

    I. A. Trusova

    2010-01-01

    Full Text Available The investigations on rational placement of burner devices in reheating furnaces with mechanized sole at the example of reheating furnace of mill 850 of RUP “BMZ” and determination of their force in dependence with grade assortment and slugs dimension types are given.

  12. Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive

    NARCIS (Netherlands)

    Christa, Gregor; Zimorski, Verena; Woehle, Christian; Tielens, Aloysius G M; Wägele, Heike; Martin, William F; Gould, Sven B

    2014-01-01

    Several sacoglossan sea slugs (Plakobranchoidea) feed upon plastids of large unicellular algae. Four species--called long-term retention (LtR) species--are known to sequester ingested plastids within specialized cells of the digestive gland. There, the stolen plastids (kleptoplasts) remain photosynt

  13. Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive

    NARCIS (Netherlands)

    G. Christa (Gregor); V. Zimorski (Verena); C. Woehle (Christian); A.G.M. Tielens (Aloysius); H. Wägele (Heike); W. Martin (William); D.B. Gould (Douglas )

    2013-01-01

    textabstractSeveral sacoglossan sea slugs (Plakobranchoidea) feed upon plastids of large unicellular algae. Four species-called long-term retention (LtR) species-are known to sequester ingested plastids within specialized cells of the digestive gland. There, the stolen plastids (kleptoplasts) remain

  14. The effect of climate manipulations on the herbivory of the pest slug Deroceras reticulatum (Müller, 1774) (Pulmonata: Agriolimacidae)

    Science.gov (United States)

    El-Danasoury, H.; Iglesias-Piñeiro, J.; Córdoba, M.

    2016-10-01

    The pestiferous status of the terrestrial slug Deroceras reticulatum and the strong dependence of its biology and ecology on climatic factors have driven research on the potential responses of the slug to predicted scenarios of climate change. Here, we report two short-term experiments performed outdoors, under seminatural conditions, to assess the behavioural response of D. reticulatum to different climate manipulations in terms of herbivory, by measuring over 7 days the damage inflicted by slug populations to lettuce seedlings. The climate manipulations tested emulate predicted climatic conditions for northwest Spain, specifically winter warming and increased summer rainfall, in contrast respectively with normal winter conditions and summer without rain conditions. In a winter experiment, we compared a normal winter treatment with a winter warming treatment; with respect to the normal winter treatment, the winter warming treatment was characterised by higher temperature, lower relative humidity and the absence of rainfall. In a summer experiment, we compared a summer drought treatment with an increased summer rainfall treatment; with respect to the summer drought treatment, the increased summer rainfall treatment was characterised by the presence of rainfall, while the conditions of temperature and relative humidity were similar in both treatments. Neither winter warming nor increased summer rainfall did lead to a significant increase on the number of seedlings damaged by the slugs. However, with both treatments, we found a moderate increase on the amount of damage suffered by the seedlings. The results are discussed in the context of the potential responses of D. reticulatum to future climatic conditions.

  15. The gastropod menace: slugs on Brassica plants affect caterpillar survival through consumption and interference with parasitoid attraction

    Science.gov (United States)

    Terrestrial molluscs and insect herbivores play a major role as plant consumers in a number of ecosystems, but their direct and indirect interactions have hardly been explored. The omnivorous nature of slugs makes them potential disrupters of predator-prey relationships, as a direct threat to small ...

  16. Live Imaging of Shoot Meristems on an Inverted Confocal Microscope Using an Objective Lens Inverter Attachment

    Science.gov (United States)

    Nimchuk, Zachary L.; Perdue, Tony D.

    2017-01-01

    Live imaging of above ground meristems can lead to new insights in plant development not possible from static imaging of fixed tissue. The use of an upright confocal microscope offers several technical and biological advantages for live imaging floral or shoot meristems. However, many departments and core facilities possess only inverted confocal microscopes and lack the funding for an additional upright confocal microscope. Here we show that imaging of living apical meristems can be performed on existing inverted confocal microscopes with the use of an affordable and detachable InverterScope accessory. PMID:28579995

  17. High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

    Science.gov (United States)

    Biess, J. J.; Inouye, L. Y.; Shank, J. H.

    1974-01-01

    A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

  18. Modified Bubble Core Fields and Bubble Shape in Laser Driven Plasma

    Institute of Scientific and Technical Information of China (English)

    WU Hai-Cheng; XIE Bai-Song

    2013-01-01

    Bubble core fields as well bubble shape modification due to the nondepleted electrons inside the bubble is investigated theoretically.It is found that the slope of transverse fields are reduced significantly,however,the slope of longitudinal electric field,which plays a key role on electrons acceleration in bubble,changes little.Moreover a modified longitudinal compressed bubble shape leads to a shorter dephasing distance which makes the electrons acceleration energy reduced to some extent.As a comparison we perform particle-in-cell simulations whose results are consistent with that of our theoretical consideration.

  19. Inverted porphyrins and expanded porphyrins: An overview

    Indian Academy of Sciences (India)

    S K Pushpan; S Venkatraman; V G Anand; J Sankar; H Rath; T K Chandrashekar

    2002-08-01

    Porphyrins and metallopophyrins have attracted the attention of chemists for the past 100 years or more owing to their widespread involvement in biology. More recently, synthetic porphyrins and porphyrin-like macrocycles have attracted the attention of researchers due to their diverse applications as sensitizers for photodynamic therapy, MRI contrasting agents, and complexing agents for larger metal ions and also for their anion binding abilities. The number of -electrons in the porphyrin ring can be increased either by increasing the number of conjugated double bonds between the pyrrole rings or by increasing the number of heterocyclic rings. Thus, 22 sapphyrins, 26 rubyrins, 30 heptaphyrins, 34 octaphyrins and higher cyclic polypyrrole analogues containing 40, 48, 64, 80 and 96 systems have recently been reported in the literature. These macrocycles show rich structural diversity where normal and different kinds of inverted structures have been identified. In this review, an attempt has been made to collect the literature of the inverted porphyrins and expanded porphyrins reported until December 2001. Since the meso aryl expanded porphyrins have tendency to form both inverted and non-inverted structures more emphasis has been given to meso aryl expanded porphyrins.

  20. Strong Connections and Invertible Weak Entwining Structures

    Institute of Scientific and Technical Information of China (English)

    J.N.ALONSO (A)LVAREZ; J.M.FERN(A)NDEZ VILABOA; R.GONZ(A)LEZ RODR(I)GUEZ

    2012-01-01

    In this paper we obtain a criterion under which the bijectivity of the canonical morphism of a weak Galois extension associated to a weak invertible entwining structure is equivalent to the existence of a strong connection form.Also we obtain an explicit formula for a strong connection under equivariant projective conditions or under coseparability conditions.

  1. The inverted pendulum : A singularity theory approach

    NARCIS (Netherlands)

    Broer, H.W.; Hoveijn, I.; Noort, M. van; Vegter, G.

    1999-01-01

    The inverted pendulum with small parametric forcing is considered as an example of a wider class of parametrically forced Hamiltonian systems. The qualitative dynamics of the Poincaré map corresponding to the central periodic solution is studied via an approximating integrable normal form. At bifurc

  2. Smart Inverters for Utility and Industry Applications

    DEFF Research Database (Denmark)

    Xue, Yaosuo; Guerrero, Josep M.

    2015-01-01

    Smart inverters are emerging with increasing renewable energy and smart grid development. While the recent work reviewed mostly focuses on defining standardized control functionalities and smart grid communication protocols, we take a holistic approach in this paper and propose a holon-type smart...

  3. [Inverted papiloma and its rare forms].

    Science.gov (United States)

    Bugová, G; Jeseňák, M; Wallenfels, P; Ondrušová, B; Hajtman, A

    2014-01-01

    Authors address the issue of a frequent benign tumour of the nasal cavity and paranasal sinuses -  inverted papilloma. They analyse the available diagnostic methods and treatment options. On the background of selected case reports of a rare malignant transformation they emphasize the need for longterm dispensarization as a part of management plan for patients with this oncological disease.

  4. Solar Power Station Output Inverter Control Design

    Directory of Open Access Journals (Sweden)

    J. Bauer

    2011-04-01

    Full Text Available The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained from the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. Or the system can be used as a generator and it shall deliver energy to the supply network. Each type of the application has different requirements on the converter and its control algorithm. But for all of them the one thing is common – the maximal efficiency. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper the design of the control algorithm of the inverter for both types of inverter application – for islanding mode and for operation on the supply grid – is discussed. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.

  5. Innovative Inverted Magnetron Experiments and Theory

    Science.gov (United States)

    2015-06-01

    35   4 Table of Figures Figure 1: 3D Solidworks renderings of each RPM embodiment including: A) Type (2) with...section, and B) Longitudinal cross-section. ................................................................................ 25   Figure 24: Solidworks ...microwave power extraction led to the use of a non-inverted design. Figure 1: 3D Solidworks renderings of each RPM embodiment including: A) Type

  6. Nonlinear Bubble Dynamics And The Effects On Propagation Through Near-Surface Bubble Layers

    Science.gov (United States)

    Leighton, Timothy G.

    2004-11-01

    Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the development of nonlinear models does more than just allow quantification of the errors associated with the use of linear models. It also offers the possibility of propagation modeling and acoustic inversions which appropriately incorporate the bubble nonlinearity. Furthermore, it allows exploration and quantification of possible nonlinear effects which may be exploited. As a result, high acoustic pressure amplitudes may be desirable even in low void fractions, because they offer opportunities to gain information about the bubble cloud from the nonlinearities, and options to exploit the nonlinearities to enhance communication and sonar in bubbly waters. This paper presents a method for calculating the nonlinear acoustic cross-sections, scatter, attenuations and sound speeds from bubble clouds which may be inhomogeneous. The method allows prediction of the time dependency of these quantities, both because the cloud may vary and because the incident acoustic pulse may have finite and arbitrary time history. The method can be readily adapted for bubbles in other environments (e.g. clouds of interacting bubbles, sediments, structures, in vivo, reverberant conditions etc.). The possible exploitation of bubble acoustics by marine mammals, and for sonar enhancement, is explored.

  7. Interaction of cavitation bubbles on a wall

    NARCIS (Netherlands)

    Bremond, Nicolas; Arora, Manish; Dammer, Stephan M.; Lohse, Detlef

    2006-01-01

    We report experimental and numerical investigations on the dynamics of the cavitation of bubbles on a solid surface and the interaction between them with the help of controlled cavitation nuclei: hemispherical bubbles are nucleated from hydrophobic microcavities that act as gas traps when the substr

  8. Interacting bubble clouds and their sonochemical production

    NARCIS (Netherlands)

    Stricker, L.; Dollet, B.; Fernandez Rivas, D.; Lohse, D.

    2013-01-01

    An acoustically driven air pocket trapped in a pit etched on a surface can emit a bubble cluster. When several pits are present, the resulting bubble clusters interact in a nontrivial way. Fernández Rivas et al. [Angew. Chem. Int. Ed. 49, 9699–9701 (2010)] observed three different behaviors at incre

  9. Steady State Vapor Bubble in Pool Boiling

    Science.gov (United States)

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.

    2016-02-01

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.

  10. Simple improvements to classical bubble nucleation models

    Science.gov (United States)

    Tanaka, Kyoko K.; Tanaka, Hidekazu; Angélil, Raymond; Diemand, Jürg

    2015-08-01

    We revisit classical nucleation theory (CNT) for the homogeneous bubble nucleation rate and improve the classical formula using a correct prefactor in the nucleation rate. Most of the previous theoretical studies have used the constant prefactor determined by the bubble growth due to the evaporation process from the bubble surface. However, the growth of bubbles is also regulated by the thermal conduction, the viscosity, and the inertia of liquid motion. These effects can decrease the prefactor significantly, especially when the liquid pressure is much smaller than the equilibrium one. The deviation in the nucleation rate between the improved formula and the CNT can be as large as several orders of magnitude. Our improved, accurate prefactor and recent advances in molecular dynamics simulations and laboratory experiments for argon bubble nucleation enable us to precisely constrain the free energy barrier for bubble nucleation. Assuming the correction to the CNT free energy is of the functional form suggested by Tolman, the precise evaluations of the free energy barriers suggest the Tolman length is ≃0.3 σ independently of the temperature for argon bubble nucleation, where σ is the unit length of the Lennard-Jones potential. With this Tolman correction and our prefactor one gets accurate bubble nucleation rate predictions in the parameter range probed by current experiments and molecular dynamics simulations.

  11. Laminar separation bubbles: Dynamics and control

    Indian Academy of Sciences (India)

    Sourabh S Diwan; O N Ramesh

    2007-02-01

    This work is an experimental investigation of the dynamics and control of the laminar separation bubbles which are typically present on the suction surface of an aerofoil at a large angle of attack. A separation bubble is produced on the upper surface of a flat plate by appropriately contouring the top wall of the wind tunnel. First, a basic (unforced) separation bubble is obtained to set a benchmark for further experiments. Parametric study is done where the reference velocity is decreased to quantify its effect on the aspect ratio of the bubble. It is found that with decrease in Reynolds number, the height of the bubble increases at a greater rate than the length. This feature could be useful in characterising separation bubbles especially from the point of view of low Reynolds number aerofoil design. Artificial disturbance is introduced at two different initial amplitudes (infinitesimal and finite) upstream of separation location and hotwire anemometry is used to trace the wave packet as it is advected downstream. The evolution of wave packets is seen to take place in two distinct stages. Finite amplitude forcing causes periodic quenching of the bubble. Interestingly, even an infinitesimally small forcing is seen to modify and thereby control the separation bubble.

  12. The Physics of Foams, Droplets and Bubbles

    Science.gov (United States)

    Sarker, Dipak K.

    2013-01-01

    Foams or bubble dispersions are common to milkshakes, bread, champagne froth, shaving mousse, shampoo, crude oil extraction systems, upholstery packing and bubble wrap, whereas the term droplet is often synonymous with either a small drop of water or a drop of oil--a type of coarse dispersion. The latter are seen in butter and milk, household…

  13. Steady State Vapor Bubble in Pool Boiling.

    Science.gov (United States)

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C; Maroo, Shalabh C

    2016-02-03

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.

  14. Continuous-data FIFO bubble shift register

    Science.gov (United States)

    Chen, T. T.

    1977-01-01

    Simple loop first-in-first-out (FIFO) bubble memory shift register has continuous storage capability. Bubble shift register simplifies chip-control electronics by enabling all control functions to be alined at same bit. FIFO shift register is constructed from passive replicator and annihilator combinations.

  15. Structure of nanoscale gas bubbles in metals

    Energy Technology Data Exchange (ETDEWEB)

    Caro, A., E-mail: caro@lanl.gov; Schwen, D.; Martinez, E. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2013-11-18

    A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2γ/R, with γ the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.

  16. Probing luminescence from nonspherical bubble collapse

    NARCIS (Netherlands)

    Ohl, Claus-Dieter

    2002-01-01

    The luminescence from single laser produced cavitation bubbles for varying degrees of asphericity is investigated temporally, spatially, and spectrally. The degree of asphericity is controlled with an adjustable rigid boundary near the bubble. Temporally, single and multiple light emission events ha

  17. Targeting miR-155 suppresses proliferation and induces apoptosis of HL-60 cells by targeting Slug/PUMA signal.

    Science.gov (United States)

    Liang, Hui; Dong, Ziyan; Liu, Jiang-Feng; Chuang, Wei; Gao, Li-Zhen; Ren, Yu-Guo

    2016-10-27

    Recent studies have shown that high miR-155 expression was associated with poor prognosis in patients with acute myelogeneous leukemia (AML). Furthermore, targeting miR-155 results in monocytic differentiation and apoptosis. However, the exact role and mechanisms of miR-155 in human AML remains speculative. HL-60 cells were treated with anti-miR-155 for 72 h. Cell growth and apoptosis in vitro were detected by MTT, BrdU proliferation, colony formation and flow cytometry assay. The effect of anti-miR-155 on growth of HL-60 cells was also evaluated in a leukemia mouse model. Slug cDNA and PUMA siRNA trannsfection was used to assess the signal pathway. Different protein expression was detected by western blot assay and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assay. The results shown that targeting miR-155 resulted in a 24-fold decrease of miR-155 expression compared to negative control in the HL-60 cells. Targeting miR-155 significantly downregulated Slug and upregulated PUMA expression, and decreased HL-60 cell growth by 70% , impaired colony formation by approximately 60%, and increased HL-60 cell apoptosis by 45%. Targeting PUMA reversed miR-155 sliencing-induced proliferation and apoptosis of HL-60 cells. Restoration of Slug decreased PUMA expression. In murine engraftment models of HL-60 cells, we showed that targeting miR-155 was able to reduce tumor growth. This was accompanied with decreased Slug expression and increased PUMA expression in these tumors. Collectively, our findings strongly suggest targeting miR-155 exhibited in vivo and in vitro antileukemic activities in AML through a novel mechanism resulting in inhibition of Slug expression and increase of PUMA expression.

  18. Study on inverter fault-tolerant operation of PMSM DTC

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper presents an investigation of inverter fault-tolerant operation for a permanent magnet synchronous motor (PMSM) direct torque control (DTC) system under various inverter faults. The performance of a faulty standard 6-switch inverter driven PMSM DTC system is analyzed. To avoid the loss or even disaster caused by the inverter faults, a topology-modified inverter with fault-tolerant capability is introduced, which is reconfigured as a 3-phase 4-switch inverter. The modeling of the 4-switch inverter is then analyzed and a novel DTC strategy with a unique nonlinear perpendicular flux observer and feedback compensation scheme is proposed for obtaining a continuous, disturbance-free drive system. The simulation and experimental results demonstrate that the proposed inverter fault-tolerant PMSM DTC system is able to operate stably and continuously with acceptable static and pretty good dynamic performance.

  19. Operating temperatures of open-rack installed photovoltaic inverters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.; Wang, L.; Kurtz, S.; Wu, J.; Quan, P.; Sorensen, R.; Liu, S.; Bai, J. B.; Zhu, Z. W.

    2016-11-01

    This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.

  20. Inverter Anti-Islanding with Advanced Grid Support in Single- and Multi-Inverter Islands

    Energy Technology Data Exchange (ETDEWEB)

    Hoke, Andy

    2016-08-16

    As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1. In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2. The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness.

  1. Galactic Teamwork Makes Distant Bubbles

    Science.gov (United States)

    Kohler, Susanna

    2016-03-01

    During the period of reionization that followed the dark ages of our universe, hydrogen was transformed from a neutral state, which is opaque to radiation, to an ionized one, which is transparent to radiation. But what generated the initial ionizing radiation? The recent discovery of multiple distant galaxies offers evidence for how this process occurred.Two Distant GalaxiesWe believe reionization occurred somewhere between a redshift of z = 6 and 7, because Ly-emitting galaxies drop out at roughly this redshift. Beyond this distance, were generally unable to see the light from these galaxies, because the universe is no longer transparent to their emission. This is not always the case, however: if a bubble of ionized gas exists around a distant galaxy, the radiation can escape, allowing us to see the galaxy.This is true of two recently-discovered Ly-emitting galaxies, confirmed to be at a redshift of z~7 and located near one another in a region known as the Bremer Deep Field. The fact that were able to see the radiation from these galaxies means that they are in an ionized HII region presumably one of the earlier regions to have become reionized in the universe.But on their own, neither of these galaxies is capable of generating an ionized bubble large enough for their light to escape. So what ionized the region around them, and what does this mean for our understanding of how reionization occurred in the universe?A Little Help From FriendsLocation in different filters of the objects in the Hubble Bremer Deep Field catalog. The z~7 selection region is outlined by the grey box. BDF-521 and BDF-3299 were the two originally discovered galaxies; the remaining red markers indicate the additional six galaxies discovered in the same region. [Castellano et al. 2016]A team of scientists led by Marco Castellano (Rome Observatory, INAF) investigated the possibility that there are other, faint galaxies near these two that have helped to ionize the region. Performing a survey

  2. Tensor Effect on Bubble Nuclei

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Zhao; GU Jian-Zhong; ZHANG Xi-Zhen; DONG Jian-Min

    2011-01-01

    In the framework of the Hartree-Fock-Bogoliubov (HFB) approach with Skyrme interactions SLy5+T, SLy5+Tw and several sets of TIJ parametrizations, I.e. The Skyrme interaction parametrizations including the tensor terms, the proton density distribution in 34Si and 46Ar nuclei is calculated with and without the tensor force. It is shown that the bubble effect in 34Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in 34Si is hardly influenced by the tensor force. As to 46Ar, the SLy5+Tw parametrization favors the formation of the bubble structure due to the inversion between the 2s1/2 and 1d3/2 orbits (2s1/2-ld3/2 inversion). The inversion mechanism induced by the SLy5+Tw interaction is analyzed based on the proton single-particle spectra obtained from the SLy5 and SLy5+Tw interactions as well as the wave functions of the 2s1/2 and 1d3/2 states.%In the framework of the Hartree-Fock-Bogoliubov (HFB) approach with Skyrme interactions SLy5+ T,SLy5+ Tω and several sets of TIJ parametrizations,i.e.the Skyrme interaction pararmetrizations including the tensor terms,the proton density distribution in 34Si and 46 Ar nuclei is calculated with and without the tensor force.It is shown that the bubble effect in 34Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in 34Si is hardly influenced by the tensor force.As to 46Ar,the SLy5+ Tω parametrization favors the formation of the bubble structure due to the inversion between the 2s1/2 and 1d3/2 orbits (2s1/2-1d3/2 inversion).The inversion mechanism induced by the SLy5+ Tω interaction is analyzed based on the proton single-particle spectra obtained from the SLy5 and SLy5+ Tω interactions as well as the wave functions of the 2s1/2 and 1d3/2 states.The study of exotic nuclear structures has been a hot topic in nuclear physics.[1-4] Exotic nuclei are unstabile,superheavy nuclei,halo nuclei and so forth,whose structures are quite different

  3. Invert muds : cost and disposal roadblocks

    Energy Technology Data Exchange (ETDEWEB)

    Garritty, N. [Engineered Drilling Solutions Inc., Calgary, AB (Canada)

    2008-07-01

    Since its inception, Engineered Drilling Solutions Incorporated (EDSI) has been focused on increasing drilling performance, increasing customer satisfaction, and decreasing drilling costs. Drilling fluid accounts for only 5 per cent of the cost to drill a well. It is necessary to look at how drilling fluid affects other aspects of drilling costs. Historically, the two main barriers to drilling with invert drilling fluids have been cost and disposal. EDSI's goal was to create an economical invert drilling fluid and develop an innovative way to dispose of the cuttings created while drilling it. This presentation discussed the costs and disposal roadblocks of invert muds. It provided a brief history of oil muds and the need for a new solution to the problem. Invert issues were identified. The presentation also discussed the removal of damaging components from the system and replacement of these materials with non-damaging alternatives which have allowed for the creation of a novel oil based drilling fluid formulation. The presentation discussed the development of 4G which was prepared with the use of a patent pending process using a colloid mill. The device achieved high levels of shear and, as a result, the fluid could be prepared to the consistency of paint. The 4G formulation was modified to 4GM in order to have a fluid that provided shear thinning at the bit for faster drilling, but that would gel up to provide for great hole cleaning. Shear thinning fluid also results in less fluid being lost over the shale shakers. 4GM was shown to enhance organophilic clay performance; significantly decrease maintenance; and decrease losses over the shaker. EDSI has also patented a solution that combines recycled tires and invert drill cuttings to create a product that replaces a portion of traditional aggregate in roads in order to offset the stresses on gravel road infrastructure as well as eliminating the waste going into landfills. figs.

  4. Interacting bubble clouds and their sonochemical production

    CERN Document Server

    Stricker, Laura; Rivas, David Fernandez; Lohse, Detlef

    2013-01-01

    Acoustically driven air pockets trapped in artificial crevices on a sur- face can emit bubbles which organize in (interacting) bubble clusters. With increasing driving power Fernandez Rivas et al. [Angew. Chem. Int. Ed., 2010] observed three different behaviors: clusters close to the very pits out of which they had been created, clusters pointing toward each other, and merging clusters. The latter behavior is highly undesired for technological purposes as it is associated with a reduction of the radical production and an enhancement of the erosion of the reactor walls. The dependence on the control parameters such as the distance of the pits and the conditions for cluster-merging are examined. The underlying mechanism, governed by the secondary Bjerknes forces, turns out to be strongly influenced by the nonlinearity of the bubble oscillations and not directly by the number of nucleated bubbles. The Bjerknes forces are found to dampen the bubble oscillations, thus reducing the radical production. Therefore, th...

  5. Oscillation of large air bubble cloud

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Y.Y.; Kim, H.Y.; Park, J.K. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)

    2001-07-01

    The behavior of a large air bubble cloud, which is generated by the air discharged from a perforated sparger, is analyzed by solving Rayleigh-Plesset equation, energy equations and energy balance equation. The equations are solved by Runge-Kutta integration and MacCormack finite difference method. Initial conditions such as driving pressure, air volume, and void fraction strongly affect the bubble pressure amplitude and oscillation frequency. The pool temperature has a strong effect on the oscillation frequency and a negligible effect on the pressure amplitude. The polytropic constant during the compression and expansion processes of individual bubbles ranges from 1.0 to 1.4, which may be attributed to the fact that small bubbles oscillated in frequencies different from their resonance. The temperature of the bubble cloud rapidly approaches the ambient temperature, as is expected from the polytropic constants being between 1.0 and 1.4. (authors)

  6. Single DNA denaturation and bubble dynamics

    DEFF Research Database (Denmark)

    Metzler, Ralf; Ambjörnsson, Tobias; Hanke, Andreas

    2009-01-01

    for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation......While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration......, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments...

  7. Sea slugs, subliminal pictures and vegetative state patients: Boundaries of consciousness in classical conditioning.

    Directory of Open Access Journals (Sweden)

    Tristan A Bekinschtein

    2011-12-01

    Full Text Available Classical (trace conditioning is a specific variant of associative learning in which a neutral stimulus leads to the subsequent prediction of an emotionally charged or noxious stimulus after a temporal gap. When conditioning is concurrent with a distraction task, only participants who can report the relationship (the contingency between stimuli explicitly show associative learning. This suggests that consciousness is a prerequisite for trace conditioning. We review and question three main controversies concerning this view. Firstly, virtually all animals, even invertebrate sea slugs, show this type of learning; secondly, unconsciously perceived stimuli may elicit trace conditioning; and thirdly, some vegetative state patients show trace learning. We discuss and analyze these seemingly contradictory arguments to find the theoretical boundaries of consciousness in classical conditioning. We conclude that trace conditioning remains one of the best measures to test conscious processing in the absence of explicit reports.

  8. Study on the tuning of the DTL cavity using slug tuners

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, H. J.; Jo, Y. S.; Shim, C. B. [KAERI, Taejon (Korea, Republic of)

    2003-07-01

    20MeV DTL (Drift Tube Linac) is being developed as a low energy proton accelerator by PEFP (Proton Engineering Frontier Project). A DTL cavity consists of several tens of cells, and the errors of resonant frequency and accelerating field profile of the DTL cavity produced by machining and alignment errors can be adjusted and corrected by using slug tuners. To reduce time and effort to tune the cavity, tuning method including resonant frequency adjustment and field profile correction was developed. To validate the tuning method, numerical simulation about the first tank of the DTL was carried out. In this paper, the summary of the proposed tuning method and the simulation results are presented.

  9. SLUG - Stochastically Lighting Up Galaxies. II: Quantifying the Effects of Stochasticity on Star Formation Rate Indicators

    CERN Document Server

    da Silva, Robert L; Krumholz, Mark R

    2014-01-01

    The integrated light of a stellar population, measured through photometric filters that are sensitive to the presence of young stars, is often used to infer the star formation rate (SFR) for that population. However, these techniques rely on an assumption that star formation is a continuous process, whereas in reality stars form in discrete spatially- and temporally-correlated structures. This discreteness causes the light output to undergo significant time-dependent fluctuations, which, if not accounted for, introduce errors and biases in the inferred SFRs. We use SLUG (a code that Stochastically Lights Up Galaxies) to simulate galaxies undergoing stochastic star formation. We then use these simulations to present a quantitative analysis of these effects and provide tools for calculating probability distribution functions of SFRs given a set of observations. We show that, depending on the SFR tracer used, stochastic fluctuations can produce non-trivial errors at SFRs as high as 1 Msun/yr, and we suggest meth...

  10. A user interface for the Kansas Geological Survey slug test model.

    Science.gov (United States)

    Esling, Steven P; Keller, John E

    2009-01-01

    The Kansas Geological Survey (KGS) developed a semianalytical solution for slug tests that incorporates the effects of partial penetration, anisotropy, and the presence of variable conductivity well skins. The solution can simulate either confined or unconfined conditions. The original model, written in FORTRAN, has a text-based interface with rigid input requirements and limited output options. We re-created the main routine for the KGS model as a Visual Basic macro that runs in most versions of Microsoft Excel and built a simple-to-use Excel spreadsheet interface that automatically displays the graphical results of the test. A comparison of the output from the original FORTRAN code to that of the new Excel spreadsheet version for three cases produced identical results.

  11. Spatial variability of hydraulic conductivity of an unconfined sandy aquifer determined by a mini slug test

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Hinsby, Klaus; Christensen, Thomas Højlund;

    1992-01-01

    The spatial variability of the hydraulic conductivity in a sandy aquifer has been determined by a mini slug test method. The hydraulic conductivity (K) of the aquifer has a geometric mean of 5.05 × 10−4 m s−1, and an overall variance of 1n K equal to 0.37 which corresponds quite well to the results...... obtained by two large scale tracer experiments performed in the aquifer. A geological model of the aquifer based on 31 sediment cores, proposed three hydrogeological layers in the aquifer concurrent with the vertical variations observed with respect to hydraulic conductivity. The horizontal correlation...... length of the hydraulic conductivity has been determined for each of the three hydrogeological layers and is found to be small (1–2.5 m). The asymptotic longitudinal dispersivity of the aquifer has been estimated from the variance in hydraulic conductivity and the horizontal correlation length...

  12. Distribution and spread of the invasive slug Arion vulgaris Moquin-Tandon in Norway

    Directory of Open Access Journals (Sweden)

    Bjørn Arild Hatteland

    2013-02-01

    Full Text Available The present distribution of the invasive slug Arion vulgaris Moquin-Tandon was studied in Norway. This important pest species has spread to many parts of Europe during the last decades, inflicting damage to agriculture and domestic gardens. It was first recorded in Norway in 1988, and has since spread to many parts of the country and is now recorded in 192 municipalities. We surveyed the current distribution by sampling and gathering species records in cooperation with garden societies and local authorities. Based on these records, we present distributional data as well as relative predictions of future distributions based on geoclimatic parameters. Currently, A. vulgaris covers most of coastal southern Norway while it shows a patchy distribution in northern Norway, recorded as far north as Finnsnes in Troms County.

  13. Gas bubble dynamics in soft materials.

    Science.gov (United States)

    Solano-Altamirano, J M; Malcolm, John D; Goldman, Saul

    2015-01-01

    Epstein and Plesset's seminal work on the rate of gas bubble dissolution and growth in a simple liquid is generalized to render it applicable to a gas bubble embedded in a soft elastic solid. Both the underlying diffusion equation and the expression for the gas bubble pressure were modified to allow for the non-zero shear modulus of the medium. The extension of the diffusion equation results in a trivial shift (by an additive constant) in the value of the diffusion coefficient, and does not change the form of the rate equations. But the use of a generalized Young-Laplace equation for the bubble pressure resulted in significant differences on the dynamics of bubble dissolution and growth, relative to an inviscid liquid medium. Depending on whether the salient parameters (solute concentration, initial bubble radius, surface tension, and shear modulus) lead to bubble growth or dissolution, the effect of allowing for a non-zero shear modulus in the generalized Young-Laplace equation is to speed up the rate of bubble growth, or to reduce the rate of bubble dissolution, respectively. The relation to previous work on visco-elastic materials is discussed, as is the connection of this work to the problem of Decompression Sickness (specifically, "the bends"). Examples of tissues to which our expressions can be applied are provided. Also, a new phenomenon is predicted whereby, for some parameter values, a bubble can be metastable and persist for long times, or it may grow, when embedded in a homogeneous under-saturated soft elastic medium.

  14. Regulation of Membrane-Type 4 Matrix Metalloproteinase by SLUG Contributes to Hypoxia-Mediated Metastasis

    Directory of Open Access Journals (Sweden)

    Chi-Hung Huang

    2009-12-01

    Full Text Available The hypoxic tumor environment has been shown to be critical to cancer metastasis through the promotion of angiogenesis, induction of epithelial-mesenchymal transition (EMT, and acquisition of invasive potential. However, the impact of hypoxia on the expression profile of the proteolytic enzymes involved in invasiveness is relatively unknown. Membrane-type 4 matrix metalloproteinase (MT4-MMP is a glycosyl-phosphatidyl inositol-anchored protease that has been shown to be overexpressed in human cancers. However, detailed mechanisms regarding the regulation and function of MT4-MMP expression in tumor cells remain unknown. Here, we demonstrate that hypoxia or overexpression of hypoxia-inducible factor-1α (HIF-1α induced MT4-MMP expression in human cancer cells. Activation of SLUG, a transcriptional factor regulating the EMT process of human cancers, by HIF-1α was critical for the induction of MT4-MMP under hypoxia. SLUG regulated the transcription of MT4-MMP through direct binding to the E-box located in its proximal promoter. Short-interference RNA-mediated knockdown of MT4-MMP attenuated in vitro invasiveness and in vivo pulmonary colonization of tumor cells without affecting cell migratory ability. MT4-MMP promoted invasiveness and pulmonary colonization through modulation of the expression profile of MMPs and angiogenic factors. Finally, coexpression of HIF-1α and MT4-MMP in human head and neck cancer was predictive of a worse clinical outcome. These findings establish a novel signaling pathway for hypoxia-mediated metastasis and elucidate the underlying regulatory mechanism and functional significance of MT4-MMP in cancer metastasis.

  15. Volatile Elements Retention During Injection Casting of Metallic Fuel Slug for a Recycling Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong-Hwan; Song, Hoon; Kim, Hyung-Tae; Oh, Seok-Jin; Kuk, Seoung-Woo; Keum, Chang-Woon; Lee, Jung-Won; Kim, Ki-Hwan; Lee, Chan-Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The as-cast fuels prepared by injection casting were sound and the internal integrities were found to be satisfactory through gamma-ray radiography. U and Zr were uniform throughout the matrix of the slug, and the impurities, i.e., oxygen, carbon, and nitrogen, satisfied the specification of the total impurities of less than 2000 ppm. The losses of the volatile Mn were effectively controlled using argon over pressures, and dynamic pumping for a period of time before injection showed no detrimental effect on the Mn loss by vaporization. This result suggests that volatile minor actinide-bearing fuels for SFRs can be prepared by improved injection methods. A practical process of metallic fuel fabrication for an SFR needs to be cost efficient, suitable for remote operation, and capable of mass production while reducing the amount of radioactive waste. Injection casting was chosen as the most promising technique, and this technique has been applied to fuel slug fabrication for the Experimental Breeder Reactor-II (EBR-II) driver and the Fast Flux Test Facility (FFTF) fuel pins. Because of the simplistic nature of the process and equipment, compared to other processes examined, this process has been successfully used in a remote operation environment for fueling of the EBR-II reactor. In this study, several injection casting methods were applied in order to prepare metallic fuel for an fast reactor that control the transport of volatile elements during fuel melting and casting. Mn was selected as a surrogate alloy since it possesses a total vapor pressure equivalent to that of a volatile minor actinide-bearing fuel. U.10Zr and U.10Zr.5Mn (wt%) metallic fuels were injection cast under various casting conditions and their soundness was characterized.

  16. The role of genetic and chemical variation of Pinus sylvestris seedlings in influencing slug herbivory.

    Science.gov (United States)

    O'Reilly-Wapstra, Julianne M; Iason, Glenn R; Thoss, Vera

    2007-05-01

    This study investigated the genetic and chemical basis of resistance of Pinus sylvestris seedlings to herbivory by a generalist mollusc, Arion ater. Using feeding trials with captive animals, we examined selective herbivory by A. ater of young P. sylvestris seedlings of different genotypes and correlated preferences with seedling monoterpene levels. We also investigated the feeding responses of A. ater to artificial diets laced with two monoterpenes, Delta(3)-carene and alpha-pinene. Logistic regression indicated that two factors were the best predictors of whether seedlings in the trial would be consumed. Individual slug variation (replicates) was the most significant factor in the model; however, alpha-pinene concentration (also representing beta-pinene, Delta(3)-carene and total monoterpenes due to multicollinearity) of needles was also a significant factor. While A. ater did not select seedlings on the basis of family, seedlings not eaten were significantly higher in levels of alpha-pinene compared to seedlings that were consumed. We also demonstrated significant genetic variation in alpha-pinene concentration of seedlings between different families of P. sylvestris. Nitrogen and three morphological seedling characteristics (stem length, needle length and stem diameter) also showed significant genetic variation between P. sylvestris families. Artificial diets laced with high (5 mg g(-1) dry matter) quantities of either Delta(3)-carene or alpha-pinene, were eaten significantly less than control diets with no added monoterpenes, supporting the results of the seedling feeding trial. This study demonstrates that A. ater selectively feed on P. sylvestris seedlings and that this selection is based, in part, on the monoterpene concentration of seedlings. These results, coupled with significant genetic variation in alpha-pinene concentration of seedlings and evidence that slug herbivory is detrimental to P. sylvestris fitness, are discussed as possible evidence for A

  17. Standard inverter series of user prime s dedication for loom and fine spinning frame use. Okyakusama hyojun series shokkiyo inverter, seibokiyo inverter

    Energy Technology Data Exchange (ETDEWEB)

    Goji, T.; Iguchi, A. (Meidensha Corp., Tokyo (Japan))

    1990-09-17

    In order to response to the user's needs such as multifunction, high performance, high efficiency, high reliability, profitability, and operativity of inverters for general use, the Meiden has developed the inverters of user's dedication in the various field based on the inverters for general use. In the present report, among the various inverters, two inverters for loom and fine spinning frame uses were introduced. The specifications and special features of individual inverters were described. An addition of the inverter for loom use to the loom drive motor enabled the continuous variable speed control of weaving rate. The start-up method and the application example of the inverter were illustrated. By using THYFREC-VT86SR as an inverter for fine spinning frame use, the smooth change of speed without thread breakage was realized, which led the improvements of productivity and quality. The application of the inverter for fine spinning frame use to the existing fine spinning frames was also described. 4 figs., 2 tabs.

  18. Online Variable Topology-Type Photovoltaic Grid-Connected Inverter

    DEFF Research Database (Denmark)

    Wu, Fengjiang; Sun, Bo; Duan, Jiandong

    2015-01-01

    and H-bridge inverter under the conditions of variable output voltage and power of the PV array. It is proved that, compared with the H-bridge inverter, the operation range of the cascaded inverter is wider, whereas the total loss is larger. Furthermore, a novel online variable topology-type grid...

  19. Mobile Inverted Constructivism: Education of Interaction Technology in Social Media

    Science.gov (United States)

    Chai, Jia-Xiang; Fan, Kuo-Kuang

    2016-01-01

    The combination of social media and invert teaching is a new path to inverting interation technology education and reconstructing the curriculum of context. In this paper, based on the theory of constructivism learning, a model named Mobile Inverted Constructivism (MIC) is provided. Moreover, in view of the functional quality of social media in…

  20. Mobile Inverted Constructivism: Education of Interaction Technology in Social Media

    Science.gov (United States)

    Chai, Jia-Xiang; Fan, Kuo-Kuang

    2016-01-01

    The combination of social media and invert teaching is a new path to inverting interation technology education and reconstructing the curriculum of context. In this paper, based on the theory of constructivism learning, a model named Mobile Inverted Constructivism (MIC) is provided. Moreover, in view of the functional quality of social media in…