Multidimensional simulations of fuel rod appendage effects on pressure drop and heat transfer in an annulus flow

International Nuclear Information System (INIS)

Banas, A.O.; Carver, M.B.; Leung, J.C.H.; Bromley, B.P.

1992-10-01

The general purpose computational fluid dynamics code, Harwell-FLOW3D, has been used to simulate the effects of fuel rod obstructions on pressure drop and heat transfer in single phase turbulent flows in a concentric annular channel. The results of two and three dimensional simulations are reported for obstructions approximating the geometry of bearing pads used in 37 element CANDU fuel bundles. Pressure drop penalty and augmentation of heat transfer have been quantified and correlated with the obstruction geometrical parameters and the dimensionless numbers representing operating conditions. The predicted effects on pressure drop have been compared with several experimental correlations, yielding good agreement. The methodology presented offers results that can be used directly as input into thermalhydraulic analyses in subchannel and system codes. (Author) (23 figs., 15 refs.)

Effectiveness of mesenchymal stems cells cultured by hanging drop vs. conventional culturing on the repair of hypoxic-ischemic-damaged mouse brains, measured by stemness gene expression

Directory of Open Access Journals (Sweden)

Lou Yongli

2016-01-01

Full Text Available In this study, we investigated the therapeutic effects of Human Mesenchymal Stem Cells (hMSCs cultured by hanging drop and conventional culturing methods on cerebellar repair in hypoxic-ischemic (HI brain injured mice. Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR was used to analyze the expression levels of three stemness genes, Oct4, Sox2 and Nanog, and the migration related gene CXCR4. MSC prepared by hanging drop or conventional techniques were administered intranasally to nine day old mice, and analyzed by MRI at day 28. Results indicate that the MSCs, especially the hanging drop cultured MSCs, significantly improved the mice’s cerebellar damage repair. MSCs derived from the hanging drop culture were smaller than those from the conventional culture. The gene expression levels were significantly increased for the MSCs derived from the hanging drop culture. The mechanism might relate to the fact that the hanging drop cultured MSCs can be kept in an undifferentiated state, resulting in its higher expression level of migration receptor of CXCR4.

Finite Element Simulations of Two Vertical Drop Tests of F-28 Fuselage Sections

Science.gov (United States)

Jackson, Karen E.; Littell, Justin D.; Annett, Martin S.; Haskin, Ian M.

2018-01-01

In March 2017, a vertical drop test of a forward fuselage section of a Fokker F-28 MK4000 aircraft was conducted as part of a joint NASA/FAA project to investigate the performance of transport aircraft under realistic crash conditions. In June 2017, a vertical drop test was conducted of a wing-box fuselage section of the same aircraft. Both sections were configured with two rows of aircraft seats, in a triple-double configuration. A total of ten Anthropomorphic Test Devices (ATDs) were secured in seats using standard lap belt restraints. The forward fuselage section was also configured with luggage in the cargo hold. Both sections were outfitted with two hat racks, each with added ballast mass. The drop tests were performed at the Landing and Impact Research facility located at NASA Langley Research Center in Hampton, Virginia. The measured impact velocity for the forward fuselage section was 346.8-in/s onto soil. The wing-box section was dropped with a downward facing pitch angle onto a sloping soil surface in order to create an induced forward acceleration in the airframe. The vertical impact velocity of the wing-box section was 349.2-in/s. A second objective of this project was to assess the capabilities of finite element simulations to predict the test responses. Finite element models of both fuselage sections were developed for execution in LS-DYNA(Registered Trademark), a commercial explicit nonlinear transient dynamic code. The models contained accurate representations of the airframe structure, the hat racks and hat rack masses, the floor and seat tracks, the luggage in the cargo hold for the forward section, and the detailed under-floor structure in the wing-box section. Initially, concentrated masses were used to represent the inertial properties of the seats, restraints, and ATD occupants. However, later simulations were performed that included finite element representations of the seats, restraints, and ATD occupants. These models were developed to more

Electromagnetic Drop Scale Scattering Modelling for Dynamic Statistical Rain Fields

OpenAIRE

Hipp, Susanne

2015-01-01

This work simulates the scattering of electromagnetic waves by a rain field. The calculations are performed for the individual drops and accumulate to a time signal dependent on the dynamic properties of the rain field. The simulations are based on the analytical Mie scattering model for spherical rain drops and the simulation software considers the rain characteristics drop size (including their distribution in rain), motion, and frequency and temperature dependent permittivity. The performe...

Drop Spreading with Random Viscosity

Science.gov (United States)

Xu, Feng; Jensen, Oliver

2016-11-01

Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.

Electrohydrodynamics of a viscous drop with inertia.

Science.gov (United States)

Nganguia, H; Young, Y-N; Layton, A T; Lai, M-C; Hu, W-F

2016-05-01

Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.

Capillary Thinning of Particle-laden Drops

Science.gov (United States)

Wagoner, Brayden; Thete, Sumeet; Jahns, Matt; Doshi, Pankaj; Basaran, Osman

2015-11-01

Drop formation is central in many applications such as ink-jet printing, microfluidic devices, and atomization. During drop formation, a thinning filament is created between the about-to-form drop and the fluid hanging from the nozzle. Therefore, the physics of capillary thinning of filaments is key to understanding drop formation and has been thoroughly studied for pure Newtonian fluids. The thinning dynamics is, however, altered completely when the fluid contains particles, the physics of which is not well understood. In this work, we explore the impact of solid particles on filament thinning and drop formation by using a combination of experiments and numerical simulations.

O the Electrohydrodynamics of Drop Extraction from a Conductive Liquid Meniscus

Science.gov (United States)

Wright, Graham Scott

This thesis is concerned with the use of an electric field in the extraction of liquid drops from a capillary orifice or nozzle. The motivating application is ink jet printing. Current drop-on-demand ink jets use pressure pulses to eject drops. Literature on electrostatic spraying suggests that by using an electric field, drops could be produced with a wider range of sizes and speeds than is possible with pressure ejection. Previous efforts to apply electric spraying to printing or similar selective coating tasks have taken an experimental approach based on steady or periodic spraying phenomena, without attempting cycle -by-cycle drop control. The centerpiece of this thesis is a simulation tool developed to explore such possibilities. A simplified analytic model is developed as a preliminary step, yielding formulas for force and time scales that provide an appropriate basis for nondimensionalization of the governing differential equations; important dimensionless parameters are identified. The complete self-consistent model permits simulation of meniscus behavior under time -varying applied voltage or pressure, with the electric field solution continually updated as the surface changes shape. The model uses a quasi-one-dimensional hydrodynamic formulation and a two-dimensional axisymmetric boundary element solution for the electric field. The simulation is checked against experimental results for meniscus stability, resonant modes, and drop emission under electric field. The simulation faithfully captures important qualitative aspects of meniscus behavior and gives reasonable quantitative agreement within the limitations of the model. Insights gained in simulation point the way to a successful laboratory demonstration of drop extraction using a shaped voltage pulse. Drop size control is pursued in simulation using pressure and voltage pulses both alone and in combination, for both light and viscous liquids. Combining pressure and field pulses is shown to be

Temporal sequencing of throughfall drop generation as revealed by use of a large-scale rainfall simulator

Science.gov (United States)

Nanko, K.; Levia, D. F., Jr.; Iida, S.; SUN, X.; Shinohara, Y.; Sakai, N.

2017-12-01

Scientists have been interested in throughfall drop size and its distribution because of its importance to soil erosion and the forest water balance. An indoor experiment was employed to deepen our understanding of throughfall drop generation processes to promote better management of forested ecosystems. The indoor experiment provides a unique opportunity to examine an array of constant rainfall intensities that are ideal conditions to pick up the effect of changing intensities and not found in the fields. Throughfall drop generation was examined for three species- Cryptomeria japonica D. Don (Japanese cedar), Chamaecyparis obtusa (Siebold & Zucc.) Endl. (Japanese cypress), and Zelkova serrata Thunb. (Japanese zelkova)- under both leafed and leafless conditions in the large-scale rainfall simulator in the National Research Institute for Earth Science and Disaster Resilience (Tsukuba, Japan) at varying rainfall intensities ranging from15 to 100 mm h-1. Drop size distributions of the applied rainfall and throughfall were measured simultaneously by 20 laser disdrometers. Utilizing the drop size dataset, throughfall was separated into three components: free throughfall, canopy drip, and splash throughfall. The temporal sequencing of the throughfall components were analyzed on a 1-min interval during each experimental run. The throughfall component percentage and drop size of canopy drip differed among tree species and rainfall intensities and by elapsed time from the beginning of the rainfall event. Preliminary analysis revealed that the time differences to produce branch drip as compared to leaf (or needle) drip was partly due to differential canopy wet-up processes and the disappearance of branch drips due to canopy saturation, leading to dissimilar throughfall drop size distributions beneath the various tree species examined. This research was supported by JSPS Invitation Fellowship for Research in Japan (Grant No.: S16088) and JSPS KAKENHI (Grant No.: JP15H05626).

Effectiveness of mesenchymal stems cells cultured by hanging drop vs. conventional culturing on the repair of hypoxic-ischemic-damaged mouse brains, measured by stemness gene expression

OpenAIRE

Lou Yongli; Guo Dewei; Zhang Hui; Song Laijun

2016-01-01

In this study, we investigated the therapeutic effects of Human Mesenchymal Stem Cells (hMSCs) cultured by hanging drop and conventional culturing methods on cerebellar repair in hypoxic-ischemic (HI) brain injured mice. Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to analyze the expression levels of three stemness genes, Oct4, Sox2 and Nanog, and the migration related gene CXCR4. MSC prepared by hanging drop or conventional techniques were adminis...

Simulation of the Initial 3-D Instability of an Impacting Drop Vortex Ring

DEFF Research Database (Denmark)

Sigurdson, Lorenz; Wiwchar, Justin; Walther, Jens Honore

2013-01-01

, a Rayleigh centrifugal instability, or a vortex breakdown-type instability. Simulations which simply have a perturbed solitary ring result in an instability similar to that seen experimentally. Waviness of the core which would be expected from a Widnall instability is not visible. Adding an opposite......-signed secondary vortex ring or an image vortex ring to the initial conditions, to trigger a Rayleigh or breakdown respectively, does not appear to significantly change the instability from what is seen with a solitary ring. This suggests that a Rayleigh or vortex breakdown-type instability are not likely at work......Computational vortex particle method simulations of a perturbed vortex ring are performed to recreate and understand the instability seen in impacting water drop experiments. Three fundamentally different initial vorticity distributions are used to attempt to trigger a Widnall instability...

Optimal Protection of Reactor Hall Under Nuclear Fuel Container Drop Using Simulation Methods

Directory of Open Access Journals (Sweden)

Králik Juraj

2014-12-01

Full Text Available This paper presents of the optimal design of the damping devices cover of reactor hall under impact of nuclear fuel container drop of type TK C30. The finite element idealization of nuclear power plant structure is used in software ANSYS. The steel pipe damper system is proposed for dissipation of the kinetic energy of the container free fall in comparison with the experimental results. The probabilistic and sensitivity analysis of the damping devices was considered on the base of the simulation methods in program AntHill using the Monte Carlo method.

The study of the effects of sea-spray drops on the marine atmospheric boundary layer by direct numerical simulation

Science.gov (United States)

Druzhinin, O.; Troitskaya, Yu; Zilitinkevich, S.

2018-01-01

The detailed knowledge of turbulent exchange processes occurring in the atmospheric marine boundary layer are of primary importance for their correct parameterization in large-scale prognostic models. These processes are complicated, especially at sufficiently strong wind forcing conditions, by the presence of sea-spray drops which are torn off the crests of sufficiently steep surface waves by the wind gusts. Natural observations indicate that mass fraction of sea-spray drops increases with wind speed and their impact on the dynamics of the air in the vicinity of the sea surface can become quite significant. Field experiments, however, are limited by insufficient accuracy of the acquired data and are in general costly and difficult. Laboratory modeling presents another route to investigate the spray-mediated exchange processes in much more detail as compared to the natural experiments. However, laboratory measurements, contact as well as Particle Image Velocimetry (PIV) methods, also suffer from inability to resolve the dynamics of the near-surface air-flow, especially in the surface wave troughs. In this report, we present a first attempt to use Direct Numerical Simulation (DNS) as tool for investigation of the drops-mediated momentum, heat and moisture transfer in a turbulent, droplet-laden air flow over a wavy water surface. DNS is capable of resolving the details of the transfer processes and do not involve any closure assumptions typical of Large-Eddy and Reynolds Averaged Navier-Stokes (LES and RANS) simulations. Thus DNS provides a basis for improving parameterizations in LES and RANS closure models and further development of large-scale prognostic models. In particular, we discuss numerical results showing the details of the modification of the air flow velocity, temperature and relative humidity fields by multidisperse, evaporating drops. We use Eulerian-Lagrangian approach where the equations for the air-flow fields are solved in a Eulerian frame whereas

Calculation of drop course of control rod assembly in PWR

International Nuclear Information System (INIS)

Zhou Xiaojia; Mao Fei; Min Peng; Lin Shaoxuan

2013-01-01

The validation of control rod drop performance is an important part of safety analysis of nuclear power plant. Development of computer code for calculating control rod drop course will be useful for validating and improving the design of control rod drive line. Based on structural features of the drive line, the driving force on moving assembly was analyzed and decomposed, the transient value of each component of the driving force was calculated by choosing either theoretical method or numerical method, and the simulation code for calculating rod cluster control assembly (RCCA) drop course by time step increase was achieved. The analysis results of control rod assembly drop course calculated by theoretical model and numerical method were validated by comparing with RCCA drop test data of Qinshan Phase Ⅱ 600 MW PWR. It is shown that the developed RCCA drop course calculation code is suitable for RCCA in PWR and can correctly simulate the drop course and the stress of RCCA. (authors)

Emulsion Design. Analysis of Drop Deformations in Mixed Flows

DEFF Research Database (Denmark)

Egholm, Runi Ditlev

2008-01-01

. Furthermore wall effects are also investigated by varying the size of the computational domain which consists of a box with variable mesh size. In the center of the domain, where the drop resides, the mesh consists of a fine region whereas closer to the walls the elements gradually increase in size. Tests...... by the drop in the rotor-stator device is emulated in the computational box used for carrying out drop shape simulations. Comparison of simulated and experimentally obtained deformations show that in general the agreement is acceptable on a qualitative level. However, the simulations predict deformations...... there is a relaxation in the flow field. Furthermore we observe that for small viscosity ratios (A ~ 0.1) tip streaming is predominant while for larger viscosity ratios either binary or capillary break-up is predominant....

Numerical Simulations of the Impact and Spreading of a Particulate Drop on a Solid Substrate

Directory of Open Access Journals (Sweden)

Hyun Jun Jeong

2012-01-01

Full Text Available We present two-dimensional numerical simulations of the impact and spreading of a droplet containing a number of small particles on a flat solid surface, just after hitting the solid surface, to understand particle effects on spreading dynamics of a particle-laden droplet for the application to the industrial inkjet printing process. The Navier-Stokes equation is solved by a finite-element-based computational scheme that employs the level-set method for the accurate interface description between the drop fluid and air and a fictitious domain method for suspended particles to account for full hydrodynamic interaction. Focusing on the particle effect on droplet spreading and recoil behaviors, we report that suspended particles suppress the droplet oscillation and deformation, by investigating the drop deformations for various Reynolds numbers. This suppressed oscillatory behavior of the particulate droplet has been interpreted with the enhanced energy dissipation due to the presence of particles.

Drop impact splashing and air entrapment

KAUST Repository

Thoraval, Marie-Jean

2013-03-01

Drop impact is a canonical problem in fluid mechanics, with numerous applications in industrial as well as natural phenomena. The extremely simple initial configuration of the experiment can produce a very large variety of fast and complex dynamics. Scientific progress was made in parallel with major improvements in imaging and computational technologies. Most recently, high-speed imaging video cameras have opened the exploration of new phenomena occurring at the micro-second scale, and parallel computing allowed realistic direct numerical simulations of drop impacts. We combine these tools to bring a new understanding of two fundamental aspects of drop impacts: splashing and air entrapment. The early dynamics of a drop impacting on a liquid pool at high velocity produces an ejecta sheet, emerging horizontally in the neck between the drop and the pool. We show how the interaction of this thin liquid sheet with the air, the drop or the pool, can produce micro-droplets and bubble rings. Then we detail how the breakup of the air film stretched between the drop and the pool for lower impact velocities can produce a myriad of micro-bubbles.

Some flow characteristics of conventional and tapered high-pressure-drop simulated seals

Science.gov (United States)

Hendricks, R. C.

1979-01-01

The leak rates through shaft seals with large pressure drops were simulated using gaseous hydrogen, or nitrogen flowing through an annulus with a nonrotating centerbody. The flows were choked. For concentric or eccentric position of the rotor and parallel or convergent tapered flow passages, data and analysis revealed that mass flux or leak rate can be determined from a relation whose normalizing parameters depend on the thermodynamic critical constants of the working fluid and an average flow area expressed in terms of the inlet and exit cross-sectional areas. Using these normalized relations, the flow data for parallel and three convergent, tapered, shaft-seal configurations are in good agreement. Generalization to any simple gas or gas mixtures is implied and demonstrated in part.

Some flow characteristics of conventional and tapered high pressure drop simulated seals

Science.gov (United States)

Hendricks, R. C.

1979-01-01

The leak rates through shaft seals with large pressure drops were simulated using gaseous hydrogen, or nitrogen flowing through an annulus with a nonrotating centerbody. The flows were choked. For concentric or eccentric position of the rotor and parallel or convergent tapered flow passages, data and analysis revealed that mass flux or leak rate can be determined from a relation whose normalizing parameters depend on the thermodynamic critical constants of the working fluid and an average flow area expressed in terms of the inlet and exit cross-sectional areas. Using these normalized relations, the flow data for parallel and three convergent tapered shaft seal configurations are in good agreement. Generalization to any simple gas or gas mixture is implied and demonstrated.

OncoSimulR: genetic simulation with arbitrary epistasis and mutator genes in asexual populations.

Science.gov (United States)

Diaz-Uriarte, Ramon

2017-06-15

OncoSimulR implements forward-time genetic simulations of biallelic loci in asexual populations with special focus on cancer progression. Fitness can be defined as an arbitrary function of genetic interactions between multiple genes or modules of genes, including epistasis, restrictions in the order of accumulation of mutations, and order effects. Mutation rates can differ among genes, and can be affected by (anti)mutator genes. Also available are sampling from simulations (including single-cell sampling), plotting the genealogical relationships of clones and generating and plotting fitness landscapes. Implemented in R and C ++, freely available from BioConductor for Linux, Mac and Windows under the GNU GPL license. Version 2.5.9 or higher available from: http://www.bioconductor.org/packages/devel/bioc/html/OncoSimulR.html . GitHub repository at: https://github.com/rdiaz02/OncoSimul. ramon.diaz@iib.uam.es. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press.

45-FOOT HIGH DROP TOWER

Data.gov (United States)

Federal Laboratory Consortium — The Drop Tower is used to simulate and measure the impact shocks that are exerted on parachute loads when they hit the ground. It is also used for HSL static lift to...

Silicon-Based Asymmetric Add-Drop Microring Resonators with Ultra-Large Through-Port Extinctions

International Nuclear Information System (INIS)

Xi, Xiao; Yun-Tao, Li; Yu-De, Yu; Jin-Zhong, Yu

2010-01-01

We theoretically simulate and experimentally demonstrate ultra-large through-port extinctions in silicon-based asymmetrically-coupled add-drop microring resonators (MRs). Through-port responses in an add-drop MR are analyzed by simulations and large extinctions are found when the MR is near-critically coupled. Accurate fabrication techniques are applied in producing a series of 20 μm-radii add-drop microrings with drop-side gap-widths in slight differences. A through-port extinction of about 42.7 dB is measured in an MR with through- and drop-side gap-width to be respectively 280nm and 295nm. The large extinction suggests about a 20.5 dB improvement from the symmetrical add-drop MR of the same size and the through-side gap-width. The experimental results are finally compared with the post-fabrication simulations, which show a gap-width tolerance of > 30 am for the through-port extinction enhancement

Effects of pressure drop and superficial velocity on the bubbling fluidized bed incinerator.

Science.gov (United States)

Wang, Feng-Jehng; Chen, Suming; Lei, Perng-Kwei; Wu, Chung-Hsing

2007-12-01

Since performance and operational conditions, such as superficial velocity, pressure drop, particles viodage, and terminal velocity, are difficult to measure on an incinerator, this study used computational fluid dynamics (CFD) to determine numerical solutions. The effects of pressure drop and superficial velocity on a bubbling fluidized bed incinerator (BFBI) were evaluated. Analytical results indicated that simulation models were able to effectively predict the relationship between superficial velocity and pressure drop over bed height in the BFBI. Second, the models in BFBI were simplified to simulate scale-up beds without excessive computation time. Moreover, simulation and experimental results showed that minimum fluidization velocity of the BFBI must be controlled in at 0.188-3.684 m/s and pressure drop was mainly caused by bed particles.

A deformable surface model for real-time water drop animation.

Science.gov (United States)

Zhang, Yizhong; Wang, Huamin; Wang, Shuai; Tong, Yiying; Zhou, Kun

2012-08-01

A water drop behaves differently from a large water body because of its strong viscosity and surface tension under the small scale. Surface tension causes the motion of a water drop to be largely determined by its boundary surface. Meanwhile, viscosity makes the interior of a water drop less relevant to its motion, as the smooth velocity field can be well approximated by an interpolation of the velocity on the boundary. Consequently, we propose a fast deformable surface model to realistically animate water drops and their flowing behaviors on solid surfaces. Our system efficiently simulates water drop motions in a Lagrangian fashion, by reducing 3D fluid dynamics over the whole liquid volume to a deformable surface model. In each time step, the model uses an implicit mean curvature flow operator to produce surface tension effects, a contact angle operator to change droplet shapes on solid surfaces, and a set of mesh connectivity updates to handle topological changes and improve mesh quality over time. Our numerical experiments demonstrate a variety of physically plausible water drop phenomena at a real-time rate, including capillary waves when water drops collide, pinch-off of water jets, and droplets flowing over solid materials. The whole system performs orders-of-magnitude faster than existing simulation approaches that generate comparable water drop effects.

Drop tests of the Three Mile Island knockout canister

International Nuclear Information System (INIS)

Box, W.D.; Aaron, W.S.; Shappert, L.B.; Childress, P.C.; Quinn, G.J.; Smith, J.V.

1986-09-01

A type of Three Mile Island Unit 2 (TMI-2) defueling canister, called a ''knockout'' canister, was subjected to a series of drop tests at the Oak Ridge National Laboratory's Drop Test Facility. These tests were designed to confirm the structural integrity of internal fixed neutron poisons in support of a request for NRC licensing of this type of canister for the shipment of TMI-2 reactor fuel debris to the Idaho National Engineering Laboratory (INEL) for the Core Examination R and D Program. Work conducted at the Oak Ridge National Laboratory included (1) precise physical measurements of the internal poison rod configuration before assembly, (2) canister assembly and welding, (3) nondestructive examination (an initial hydrostatic pressure test and an x-ray profile of the internals before and after each drop test), (4) addition of a simulated fuel load, (5) instrumentation of the canister for each drop test, (6) fabrication of a cask simulation vessel with a developed and tested foam impact limiter, (7) use of refrigeration facilities to cool the canister to well below freezing prior to three of the drops, (8) recording the drop test with still, high-speed, and normal-speed photography, (9) recording the accelerometer measurements during impact, (10) disassembly and post-test examination with precise physical measurements, and (11) preparation of the final report

Simulated breeding with QU-GENE graphical user interface.

Science.gov (United States)

Hathorn, Adrian; Chapman, Scott; Dieters, Mark

2014-01-01

Comparing the efficiencies of breeding methods with field experiments is a costly, long-term process. QU-GENE is a highly flexible genetic and breeding simulation platform capable of simulating the performance of a range of different breeding strategies and for a continuum of genetic models ranging from simple to complex. In this chapter we describe some of the basic mechanics behind the QU-GENE user interface and give a simplified example of how it works.

Synthesis of sheath voltage drops in asymmetric radio-frequency discharges

International Nuclear Information System (INIS)

Yonemura, Shigeru; Nanbu, Kenichi; Iwata, Naoaki

2004-01-01

A sheath voltage drop in asymmetric discharges is one of the most important parameters of radio-frequency capacitively coupled plasmas because it determines the kinetic energy of the ions incident on the target or substrate. In this study, we developed a numerical simulation code to estimate the sheath voltage drops and, consequently, the self-bias voltage. We roughly approximated general asymmetric rf discharges to one-dimensional spherical ones. The results obtained by using our simulation code are consistent with measurements and Lieberman's theory

Electrohydrodynamics of suspension of liquid drops in AC fields

Science.gov (United States)

Abdul Halim, Md.; Esmaeeli, Asghar

2012-11-01

Manipulation of liquid drops by an externally applied electric field is currently the focus of increased attention because of its relevance in a broad range of industrial processes. The effect of a uniform DC electric field on a solitary drop is well studied; however, less is know about the impact of electric field on suspension of liquid drops, and very little information is available on the impact of AC field on a single or a suspension of drops. Here we report the results of Direct Numerical Simulations of electrohydrodynamics of suspension of liquid drops. The governing equations are solved using a front tracking/finite difference technique, in conjunction with Taylor's leaky dielectric model. The imposed electric potential comprises of two parts, a time-independent base and a time-dependent part. The goal is to explore the relative importance of these two components in setting the statistically steady state behavior of the suspension. To this end, we report the results of three sets of simulations, where (i) the time-dependent part act as a perturbation on the base potential, (ii) the two components are of the same order, and (iii) the time-dependent part is much larger than the base potential. The problem is studied as a function of the governing nondimensional parameters.

Insights from the pollination drop proteome and the ovule transcriptome of Cephalotaxus at the time of pollination drop production.

Science.gov (United States)

Pirone-Davies, Cary; Prior, Natalie; von Aderkas, Patrick; Smith, Derek; Hardie, Darryl; Friedman, William E; Mathews, Sarah

2016-05-01

Many gymnosperms produce an ovular secretion, the pollination drop, during reproduction. The drops serve as a landing site for pollen, but also contain a suite of ions and organic compounds, including proteins, that suggests diverse roles for the drop during pollination. Proteins in the drops of species of Chamaecyparis, Juniperus, Taxus, Pseudotsuga, Ephedra and Welwitschia are thought to function in the conversion of sugars, defence against pathogens, and pollen growth and development. To better understand gymnosperm pollination biology, the pollination drop proteomes of pollination drops from two species of Cephalotaxus have been characterized and an ovular transcriptome for C. sinensis has been assembled. Mass spectrometry was used to identify proteins in the pollination drops of Cephalotaxus sinensis and C. koreana RNA-sequencing (RNA-Seq) was employed to assemble a transcriptome and identify transcripts present in the ovules of C. sinensis at the time of pollination drop production. About 30 proteins were detected in the pollination drops of both species. Many of these have been detected in the drops of other gymnosperms and probably function in defence, polysaccharide metabolism and pollen tube growth. Other proteins appear to be unique to Cephalotaxus, and their putative functions include starch and callose degradation, among others. Together, the proteins appear either to have been secreted into the drop or to occur there due to breakdown of ovular cells during drop production. Ovular transcripts represent a wide range of gene ontology categories, and some may be involved in drop formation, ovule development and pollen-ovule interactions. The proteome of Cephalotaxus pollination drops shares a number of components with those of other conifers and gnetophytes, including proteins for defence such as chitinases and for carbohydrate modification such as β-galactosidase. Proteins likely to be of intracellular origin, however, form a larger component of drops

Analysis of DCI cask drop test onto reinforced concrete pad

International Nuclear Information System (INIS)

Ito, C.; Kato, Y.; Hattori, S.; Shirai, K.; Misumi, M.; Ozaki, S.

1993-01-01

In a cask-storage facility, a cask may be subjected to an impact load as a result of a free drop onto the floor because of cask mishandling. We performed drop tests of casks onto a reinforced concrete (RC) slab representing the floor of a facility as well as simulation analysis [Kato et al]. This paper describes the details of the FEM analysis and calculated results and compares them with the drop test results. (J.P.N.)

Enhanced intelligent water drops algorithm for multi-depot vehicle routing problem.

Science.gov (United States)

Ezugwu, Absalom E; Akutsah, Francis; Olusanya, Micheal O; Adewumi, Aderemi O

2018-01-01

The intelligent water drop algorithm is a swarm-based metaheuristic algorithm, inspired by the characteristics of water drops in the river and the environmental changes resulting from the action of the flowing river. Since its appearance as an alternative stochastic optimization method, the algorithm has found applications in solving a wide range of combinatorial and functional optimization problems. This paper presents an improved intelligent water drop algorithm for solving multi-depot vehicle routing problems. A simulated annealing algorithm was introduced into the proposed algorithm as a local search metaheuristic to prevent the intelligent water drop algorithm from getting trapped into local minima and also improve its solution quality. In addition, some of the potential problematic issues associated with using simulated annealing that include high computational runtime and exponential calculation of the probability of acceptance criteria, are investigated. The exponential calculation of the probability of acceptance criteria for the simulated annealing based techniques is computationally expensive. Therefore, in order to maximize the performance of the intelligent water drop algorithm using simulated annealing, a better way of calculating the probability of acceptance criteria is considered. The performance of the proposed hybrid algorithm is evaluated by using 33 standard test problems, with the results obtained compared with the solutions offered by four well-known techniques from the subject literature. Experimental results and statistical tests show that the new method possesses outstanding performance in terms of solution quality and runtime consumed. In addition, the proposed algorithm is suitable for solving large-scale problems.

Inferring Drosophila gap gene regulatory network: Pattern analysis of simulated gene expression profiles and stability analysis

OpenAIRE

Fomekong-Nanfack, Y.; Postma, M.; Kaandorp, J.A.

2009-01-01

Abstract Background Inference of gene regulatory networks (GRNs) requires accurate data, a method to simulate the expression patterns and an efficient optimization algorithm to estimate the unknown parameters. Using this approach it is possible to obtain alternative circuits without making any a priori assumptions about the interactions, which all simulate the observed patterns. It is important to analyze the properties of the circuits. Findings We have analyzed the simulated gene expression ...

SELANSI: a toolbox for simulation of stochastic gene regulatory networks.

Science.gov (United States)

Pájaro, Manuel; Otero-Muras, Irene; Vázquez, Carlos; Alonso, Antonio A

2018-03-01

Gene regulation is inherently stochastic. In many applications concerning Systems and Synthetic Biology such as the reverse engineering and the de novo design of genetic circuits, stochastic effects (yet potentially crucial) are often neglected due to the high computational cost of stochastic simulations. With advances in these fields there is an increasing need of tools providing accurate approximations of the stochastic dynamics of gene regulatory networks (GRNs) with reduced computational effort. This work presents SELANSI (SEmi-LAgrangian SImulation of GRNs), a software toolbox for the simulation of stochastic multidimensional gene regulatory networks. SELANSI exploits intrinsic structural properties of gene regulatory networks to accurately approximate the corresponding Chemical Master Equation with a partial integral differential equation that is solved by a semi-lagrangian method with high efficiency. Networks under consideration might involve multiple genes with self and cross regulations, in which genes can be regulated by different transcription factors. Moreover, the validity of the method is not restricted to a particular type of kinetics. The tool offers total flexibility regarding network topology, kinetics and parameterization, as well as simulation options. SELANSI runs under the MATLAB environment, and is available under GPLv3 license at https://sites.google.com/view/selansi. antonio@iim.csic.es. © The Author(s) 2017. Published by Oxford University Press.

Evaporation of a sessile water drop and a drop of aqueous salt solution.

Science.gov (United States)

Misyura, S Y

2017-11-07

The influence of various factors on the evaporation of drops of water and aqueous salt solution has been experimentally studied. Typically, in the studies of drop evaporation, only the diffusive vapor transfer, radiation and the molecular heat conduction are taken into account. However, vapor-gas convection plays an important role at droplet evaporation. In the absence of droplet boiling, the influence of gas convection turns out to be the prevailing factor. At nucleate boiling, a prevailing role is played by bubbles generation and vapor jet discharge at a bubble collapse. The gas convection behavior for water and aqueous salt solution is substantially different. With a growth of salt concentration over time, the influence of the convective component first increases, reaches an extremum and then significantly decreases. At nucleate boiling in a salt solution it is incorrect to simulate the droplet evaporation and the heat transfer in quasi-stationary approximation. The evaporation at nucleate boiling in a liquid drop is divided into several characteristic time intervals. Each of these intervals is characterized by a noticeable change in both the evaporation rate and the convection role.

Rod-drop analysis in fast and thermal spectra

International Nuclear Information System (INIS)

Broccoli, U.

1988-01-01

The application of Carpenter's method to power profiles resulting from simulated or real rod-drop events has been tested. The conditions which allow the errors to be reduced to a minimum are highlighted. The results obtained show a good agreement with simulated and experimental data. (author). 1 ref., 21 figs, 6 tabs

Shuttlecock Velocity of a Badminton Drop Shot

Directory of Open Access Journals (Sweden)

Ampharin Ongvises

2013-01-01

Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

Shuttlecock Velocity of a Badminton Drop Shot

Directory of Open Access Journals (Sweden)

Ampharin Ongvises

2013-12-01

Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

An AMOLED AC-Biased Pixel Design Compensating the Threshold Voltage and I-R Drop

Directory of Open Access Journals (Sweden)

Ching-Lin Fan

2011-01-01

Full Text Available We propose a novel pixel design and an AC bias driving method for active-matrix organic light-emitting diode (AM-OLED displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs. The proposed threshold voltage and I-R drop compensation circuit, which comprised three transistors and one capacitor, have been verified to supply uniform output current by simulation work using the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE simulator. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<0.7% and low voltage drop of VDD power line. The proposed pixel circuit effectively enables threshold-voltage-deviation correction of driving TFT and compensates for the voltage drop of VDD power line using AC bias on OLED cathode.

Drop jumping. II. The influence of dropping height on the biomechanics of drop jumping

NARCIS (Netherlands)

Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce

First drop dissimilarity in drop-on-demand inkjet devices

International Nuclear Information System (INIS)

Famili, Amin; Palkar, Saurabh A.; Baldy, William J. Jr.

2011-01-01

As inkjet printing technology is increasingly applied in a broader array of applications, careful characterization of its method of use is critical due to its inherent sensitivity. A common operational mode in inkjet technology known as drop-on-demand ejection is used as a way to deliver a controlled quantity of material to a precise location on a target. This method of operation allows ejection of individual or a sequence (burst) of drops based on a timed trigger event. This work presents an examination of sequences of drops as they are ejected, indicating a number of phenomena that must be considered when designing a drop-on-demand inkjet system. These phenomena appear to be driven by differences between the first ejected drop in a burst and those that follow it and result in a break-down of the linear relationship expected between driving amplitude and drop mass. This first drop, as quantified by high-speed videography and subsequent image analysis, can be different in morphology, trajectory, velocity, and volume from subsequent drops within a burst. These findings were confirmed orthogonally by both volume and mass measurement techniques which allowed quantitation down to single drops.

From nuclei to liquid drops

Energy Technology Data Exchange (ETDEWEB)

Menchaca-Rocha, A.; Huidobro, F.; Michaelian, K.; Perez, A.; Rodriguez, V. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica; Carjan, N. [Bordeaux-1 Univ., 33 - Gradignan (France). Centre d`Etudes Nucleaires

1995-12-31

Collisions of symmetric mercury-drop pairs have been studied experimentally as a function of impact parameter, in a relative-velocity range going from a coalescence-dominated region to interactions yielding several residues. The experiments are compared with predictions of a dynamical model used in nuclear physics. The time evolution of the shapes is well reproduced by the simulation. (authors). 8 refs., 3 figs.

Scaling during capillary thinning of particle-laden drops

Science.gov (United States)

Thete, Sumeet; Wagoner, Brayden; Basaran, Osman

2017-11-01

A fundamental understanding of drop formation is crucial in many applications such as ink-jet printing, microfluidic devices, and atomization. During drop formation, the about-to-form drop is connected to the fluid hanging from the nozzle via a thinning filament. Therefore, the physics of capillary thinning of filaments is key to understanding drop formation and has been thoroughly studied for pure Newtonian fluids using theory, simulations, and experiments. In some of the applications however, the forming drop and hence the thinning filament may contain solid particles. The thinning dynamics of such particle-laden filaments differs radically from that of particle-free filaments. Moreover, our understanding of filament thinning in the former case is poor compared to that in the latter case despite the growing interest in pinch-off of particle-laden filaments. In this work, we go beyond similar studies and experimentally explore the impact of solid particles on filament thinning by measuring both the radial and axial scalings in the neck region. The results are summarized in terms of a phase diagram of capillary thinning of particle-laden filaments.

Rehme correlation for spacer pressure drop compared to XT-ADS rod bundle simulations and water experiment

International Nuclear Information System (INIS)

Batta, A.; Class, A.; Litfin, K.; Wetzel, T.

2011-01-01

The Rehme correlation is the most common formula to estimate the pressure drop of spacers in the design phase of new bundle geometries. It is based on considerations of momentum losses and takes into account the obstruction of the flow cross section but it ignores the geometric details of the spacer design. Within the framework of accelerator driven sub-critical reactor systems (ADS), heavy-liquid-metal (HLM) cooled fuel assemblies are considered. At the KArlsruhe Liquid metal LAboratory (KALLA) of the Karlsruhe Institute of Technology a series of experiments to quantify both pressure losses and heat transfer in HLM-cooled rod bundles are performed. The present study compares simulation results obtained with the commercial CFD code Star-CCM to experiments and the Rehme correlation. It can be shown that the Rehme correlation, simulations and experiments all yield similar trends, but quantitative predictions can only be delivered by the CFD which takes into account the full geometric details of the spacer geometry. (orig.)

Potential drop crack measurement systems for CANDU components

Energy Technology Data Exchange (ETDEWEB)

Sahney, R [Carleton Univ., Ottawa, ON (Canada)

1994-12-31

A project to develop an automated crack measurement system for CANDU pressure tube burst testing is currently underway. The system will utilize either Direct Current Potential Drop (DCPD) or Alternating Current Potential Drop (ACPD) techniques for crack measurement. The preliminary stage of the project involves testing and comparison of both ACPD and DCPD methods on a Zr - 2.5% Nb alloy plate with saw cuts (used to simulate cracks). Preliminary results show that both ACPD and DCPD techniques are capable of detecting cracks; further testing is in progress to determine the ability of each of the two systems to make accurate crack depth measurements. This paper will describe the two potential drop techniques and will present test results from the experimental program. (author). 10 refs., 7 figs.

A highly accurate boundary integral equation method for surfactant-laden drops in 3D

Science.gov (United States)

Sorgentone, Chiara; Tornberg, Anna-Karin

2018-05-01

The presence of surfactants alters the dynamics of viscous drops immersed in an ambient viscous fluid. This is specifically true at small scales, such as in applications of droplet based microfluidics, where the interface dynamics become of increased importance. At such small scales, viscous forces dominate and inertial effects are often negligible. Considering Stokes flow, a numerical method based on a boundary integral formulation is presented for simulating 3D drops covered by an insoluble surfactant. The method is able to simulate drops with different viscosities and close interactions, automatically controlling the time step size and maintaining high accuracy also when substantial drop deformation appears. To achieve this, the drop surfaces as well as the surfactant concentration on each surface are represented by spherical harmonics expansions. A novel reparameterization method is introduced to ensure a high-quality representation of the drops also under deformation, specialized quadrature methods for singular and nearly singular integrals that appear in the formulation are evoked and the adaptive time stepping scheme for the coupled drop and surfactant evolution is designed with a preconditioned implicit treatment of the surfactant diffusion.

Drop Performance Test of CRDMs for JRTR

Energy Technology Data Exchange (ETDEWEB)

Choi, Myoung-Hwan; Cho, Yeong-Garp; Chung, Jong-Ha [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Jung-Hyun [POSCO Plandtec Co. Ltd, Ulsan (Korea, Republic of); Lee, Kwan-Hee [RIST, Pohang (Korea, Republic of)

2015-10-15

The drop test results of CRDMs with AC-type electromagnet show that the initial delay times are not satisfied with the requirement, 0.15 seconds. After the replacement of the electromagnet from AC-type to DCtype, the drop times of CARs and accelerations due to the impact of moving parts are satisfied with all requirements. As a result, it is found that four CRDMs to be installed at site have a good drop performance, and meet all performance requirements. A control rod drive mechanism (CRDM) is a device to control the position of a control absorber rod (CAR) in the core by using a stepping motor which is commanded by the reactor regulating system (RRS) to control the reactivity during the normal operation of the reactor. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the performances such as the stepping, drop, endurance, vibration, seismic and structural integrity for active components. Especially, the CAR drop curves are important data for the safety analysis. This paper describes the test results to demonstrate the drop performances of a prototype and 4 CRDMs to be installed at site. The tests are carried out at a test rig simulating the actual reactor's conditions.

Vortex-ring-induced large bubble entrainment during drop impact

KAUST Repository

Thoraval, Marie-Jean

2016-03-29

For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

A novel approach to simulate gene-environment interactions in complex diseases

Directory of Open Access Journals (Sweden)

Nicodemi Mario

2010-01-01

Full Text Available Abstract Background Complex diseases are multifactorial traits caused by both genetic and environmental factors. They represent the major part of human diseases and include those with largest prevalence and mortality (cancer, heart disease, obesity, etc.. Despite a large amount of information that has been collected about both genetic and environmental risk factors, there are few examples of studies on their interactions in epidemiological literature. One reason can be the incomplete knowledge of the power of statistical methods designed to search for risk factors and their interactions in these data sets. An improvement in this direction would lead to a better understanding and description of gene-environment interactions. To this aim, a possible strategy is to challenge the different statistical methods against data sets where the underlying phenomenon is completely known and fully controllable, for example simulated ones. Results We present a mathematical approach that models gene-environment interactions. By this method it is possible to generate simulated populations having gene-environment interactions of any form, involving any number of genetic and environmental factors and also allowing non-linear interactions as epistasis. In particular, we implemented a simple version of this model in a Gene-Environment iNteraction Simulator (GENS, a tool designed to simulate case-control data sets where a one gene-one environment interaction influences the disease risk. The main aim has been to allow the input of population characteristics by using standard epidemiological measures and to implement constraints to make the simulator behaviour biologically meaningful. Conclusions By the multi-logistic model implemented in GENS it is possible to simulate case-control samples of complex disease where gene-environment interactions influence the disease risk. The user has full control of the main characteristics of the simulated population and a Monte

Study of Fast Transient Pressure Drop in VVER-1000 Nuclear Reactor Using Acoustic Phenomenon

Directory of Open Access Journals (Sweden)

Soroush Heidari Sangestani

2018-01-01

Full Text Available This article aims to simulate the sudden and fast pressure drop of VVER-1000 reactor core coolant, regarding acoustic phenomenon. It is used to acquire a more accurate method in order to simulate the various accidents of reactor core. Neutronic equations should be solved concurrently by means of DRAGON 4 and DONJON 4 coupling codes. The results of the developed package are compared with WIMS/CITATION and final safety analysis report of Bushehr VVER-1000 reactor (FSAR. Afterwards, time dependent thermal-hydraulic equations are answered by employing Single Heated Channel by Sectionalized Compressible Fluid method. Then, the obtained results were validated by the same transient simulation in a pressurized water reactor core. Then, thermal-hydraulic and neutronic modules are coupled concurrently by use of producing group constants regarding the thermal feedback effect. Results were compared to the mentioned transient simulation in RELAP5 computer code, which show that mass flux drop is sensed at the end of channel in several milliseconds which causes heat flux drop too. The thermal feedback resulted in production of some perturbations in the changes of these parameters. The achieved results for this very fast pressure drop represent accurate calculations of thermoneutronic parameters fast changes.

Fundamental investigation on electrostatic travelling-wave transport of a liquid drop

International Nuclear Information System (INIS)

Kawamoto, Hiroyuki; Hayashi, Satoshi

2006-01-01

Basic research has been carried out on the transport of a liquid drop and a soft body in an electrostatic travelling field. A conveyer consisting of parallel electrodes was constructed and a four-phase electrostatic travelling wave was applied to the electrodes to transport the drop on the conveyer. The following were clarified by the experiment. (1) Drops and soft bodies can be transported by virtue of the travelling wave in an insulative liquid that is insoluble to the drop, because the drop was charged on the conveyer by friction and driven by the Coulomb force. (2) A drop that covered less than three arrays of the parallel electrode can be transported in the travelling wave field. (3) A threshold voltage exists for the transport. (4) Although the transport was possible not only for insulative but also for conductive drops, the insulative drop can be transported efficiently. (5) The modes of transport can be classified into three categories, namely, a synchronous region where the motion of the liquid drop is in synchrony with the travelling wave, a delayed response regime, and a regime where transport does not occur. (6) Mixing of drops for a chemical reaction was demonstrated on the conveyer with scroll electrodes. A simple model was proposed to simulate the dynamics of the drop in the electrostatic travelling field

Drop Impact Dynamics with Sessile Drops and Geometries: Spreading, Jetting, and Fragmentation

Science.gov (United States)

Tilger, Christopher F.

The tendency of surface tension to cause small parcels of fluid to form into drops allows convenient packaging, transport, dispersal of liquid phase matter. Liquid drop impacts with solids, liquids, and other drops have realized and additional future applications in biological, manufacturing, heat transfer, and combustion systems. Experiments were conducted to investigate the dynamics of multiple drop collisions, rather than the most-studied phenomenon of single drop impacts. Additional drop impacts were performed on rigid hemispheres representing sessile drops, angled substrates, and into the vertex of two tilted surfaces arranged into a vee shape. A qualitative inspection of drop-sessile drop impacts shows distinct post-impact shapes depending on the offset distance between the drops. At intermediate offset distances, distinct jets issue from the overlap region between the two drops projected areas. These jets are observed to reach their maximum extent at a critical offset distance ratio, epsilon epsilon ˜ 0.75-0.80, with substrate contact angle and W e having a lesser effect. Capillary waves that traverse the sessile drop after collision cause a lower aspect ratio liquid column to emanate from the sessile drop opposite the impact. In order to better understand the jetting phenomenon seen in the offset drop-sessile drop impacts, simpler solid geometries are investigated that elicit a similar behavior. Solid hemispheres do not show the singular jetting observed in the fluidic case, however, a simple vee formed by two intersection planar substrates do jet in a similar fashion to the fluidic case. A geometric model with partnered experiments is developed to describe the bisymmetric spread of an impacting drop on an angled substrate. This geometric model is used to guide a time of arrival based model for various features of the drop impact, which is used to predict jetting in various vee channel experiments.

Impact of a single drop on the same liquid: formation, growth and disintegration of jets

Science.gov (United States)

Agbaglah, G. Gilou; Deegan, Robert

2015-11-01

One of the simplest splashing scenarios results from the impact of a single drop on on the same liquid. The traditional understanding of this process is that the impact generates a jet that later breaks up into secondary droplets. Recently it was shown that even this simplest of scenarios is more complicated than expected because multiple jets can be generated from a single impact event and there are bifurcations in the multiplicity of jets. First, we study the formation, growth and disintegration of jets following the impact of a drop on a thin film of the same liquid using a combination of numerical simulations and linear stability theory. We obtain scaling relations from our simulations and use these as inputs to our stability analysis. We also use experiments and numerical simulations of a single drop impacting on a deep pool to examine the bifurcation from a single jet into two jets. Using high speed X-ray imaging methods we show that vortex separation within the drop leads to the formation of a second jet long after the formation of the ejecta sheet.

An efficient parallel stochastic simulation method for analysis of nonviral gene delivery systems

KAUST Repository

Kuwahara, Hiroyuki

2011-01-01

Gene therapy has a great potential to become an effective treatment for a wide variety of diseases. One of the main challenges to make gene therapy practical in clinical settings is the development of efficient and safe mechanisms to deliver foreign DNA molecules into the nucleus of target cells. Several computational and experimental studies have shown that the design process of synthetic gene transfer vectors can be greatly enhanced by computational modeling and simulation. This paper proposes a novel, effective parallelization of the stochastic simulation algorithm (SSA) for pharmacokinetic models that characterize the rate-limiting, multi-step processes of intracellular gene delivery. While efficient parallelizations of the SSA are still an open problem in a general setting, the proposed parallel simulation method is able to substantially accelerate the next reaction selection scheme and the reaction update scheme in the SSA by exploiting and decomposing the structures of stochastic gene delivery models. This, thus, makes computationally intensive analysis such as parameter optimizations and gene dosage control for specific cell types, gene vectors, and transgene expression stability substantially more practical than that could otherwise be with the standard SSA. Here, we translated the nonviral gene delivery model based on mass-action kinetics by Varga et al. [Molecular Therapy, 4(5), 2001] into a more realistic model that captures intracellular fluctuations based on stochastic chemical kinetics, and as a case study we applied our parallel simulation to this stochastic model. Our results show that our simulation method is able to increase the efficiency of statistical analysis by at least 50% in various settings. © 2011 ACM.

Spectrum analysis of a voltage source converter due to semiconductor voltage drops

DEFF Research Database (Denmark)

Rasmussen, Tonny Wederberg; Eltouki, Mustafa

2017-01-01

It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation....... The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added. The results of the analysis of the spectral contribution including and excluding semiconductor voltage drop reveal a good agreement between the theoretical results, simulations and laboratory...

Thermal imaging of levitated fresh and salt water drops during laser irradiation

Science.gov (United States)

Brownell, Cody; Biggs, Harrison

2017-11-01

Simulation of high energy laser propagation and scattering in the maritime environment is problematic, due to the high likelihood of turbulence, fog, and rain or sea spray within the beam path. Considering large water drops (diameters of approximately 1-mm), such as those found in a light rain, an incident high energy laser will lead to rapid evaporation of the water drop as it traverses the beam path. In this work we present surface temperature measurements of a water drop obtained using a FLIR IR camera. The drop is acoustically levitated, and subject to a continuous wave laser with a wavelength of 1070-nm and a mean irradiance of approximately 800 W/cm2. These measurements show that the steady-state surface temperature of the drop is well below the saturation temperature, and for pure substances the equilibrium temperature decreases with decreasing drop volume similar to observations with smaller aqueous aerosols. Temperature non-uniformity within the drop is also assessed from statistics of the surface temperature fluctuations. Preliminary results from irradiated salt water drops show notably different behavior from fresh water drops, including temperature spikes as the drop volume decreases and occasional nucleate boiling. Acknowledge support from ONR #N00014-17-WX-00031.

Pulverized coal burnout in blast furnace simulated by a drop tube furnace

Energy Technology Data Exchange (ETDEWEB)

Du, Shan-Wen [Steel and Aluminum Research and Development Department, China Steel Corporation, Kaohsiung 812 (China); Chen, Wei-Hsin [Department of Greenergy, National University of Tainan, Tainan 700 (China); Lucas, John A. [School of Engineering of the University of Newcastle, Callaghan, NSW 2308 (Australia)

2010-02-15

Reactions of pulverized coal injection (PCI) in a blast furnace were simulated using a drop tube furnace (DTF) to investigate the burnout behavior of a number of coals and coal blends. For the coals with the fuel ratio ranging from 1.36 to 6.22, the experimental results indicated that the burnout increased with decreasing the fuel ratio, except for certain coals departing from the general trend. One of the coals with the fuel ratio of 6.22 has shown its merit in combustion, implying that the blending ratio of the coal in PCI operation can be raised for a higher coke replacement ratio. The experiments also suggested that increasing blast temperature was an efficient countermeasure for promoting the combustibility of the injected coals. Higher fuel burnout could be achieved when the particle size of coal was reduced from 60-100 to 100-200 mesh. However, once the size of the tested coals was in the range of 200 and 325 mesh, the burnout could not be improved further, resulting from the agglomeration of fine particles. Considering coal blend reactions, the blending ratio of coals in PCI may be adjusted by the individual coal burnout rather than by the fuel ratio. (author)

Analysis of the rod drop accident for Angra-1

International Nuclear Information System (INIS)

Veloso, M.A.; Atayde, P.A.

1989-01-01

The aim of this work is to present a rod drop accident analysis for the third cycle of the Angra-1 nuclear power plant operating in the automatic control mode. In this analysis all possible configurations for dropped rods caused by a single failure in the controller circuits have been considered. The dropped rod worths, power distributions and excore detector tilts were determined by using the Siemens/KWU neutronic code system, in particular the MEDIUM2, PINPOW and DETILT codes. The transient behaviour of the plant during the rod drop event was simulated with the SACI2/MOD0 code, developed at CDTN. Determinations related to the DNBR design limit were conducted by utilizing the CDTN PANTERA-1P subchannel code. The transient analysis indicated that for dropped rod worths greater than about 425 pcm reactor trip from negative neutron flux rate will take place independently of core conditions. In the range from 0 to 425 pcm large power overshoots may occur as a consequence of the automatic control system action. The magnitude of the maximum power peaking during the event increases with the dropped rod worth, as far as the control bank is able to compensate the initial reactivity decrease. Thermal-hydraulic evaluations carried out with the PANTERA-1P code show that for all the relevant dropped rod worths the minimum DNBR will remain above a limit value of 1.365. Even if this conservative limit is met, the calculated nuclear power peaking factors, F N AH , will be at least 6% higher than the allowable F N AH -values. Therefore, the DNBR design margin will be preserved at the event of rod drop. (author)

Steam explosion studies with single drops of molten refractory materials

International Nuclear Information System (INIS)

Nelson, L.S.

1980-01-01

Laser heating, levitation melting, and metal combustion were used to prepare individual drops of molten refractory materials which simulate LWR fuel melt products. Drop temperatures ranged from approx. = 1500 to > 3000K. These drops, several millimeters in diameter, were injected into water and subjected to pressure transients (approx. = 1MPa peak pressures) generated by a submerged exploding bridgewire. Molten oxides of Fe, Al and Zr could be induced to explode with bridgewire initiation. High speed films showed the explosions with exceptional clarity, and pressure transducer records could be correlated with individual frames in the films. Pressure spikes one or two MPa high were generated whenever an explosion occurred. Debris particles were mostly spheroidal, with diameters in the range 10 to 1000 μm

Comparison of explicit finite element and mechanical simulation of the proximal femur during dynamic drop-tower testing.

Science.gov (United States)

Ariza, O; Gilchrist, S; Widmer, R P; Guy, P; Ferguson, S J; Cripton, P A; Helgason, B

2015-01-21

Current screening techniques based on areal bone mineral density (aBMD) measurements are unable to identify the majority of people who sustain hip fractures. Biomechanical examination of such events may help determine what predisposes a hip to be susceptible to fracture. Recently, drop-tower simulations of in-vitro sideways falls have allowed the study of the mechanical response of the proximal human femur at realistic impact speeds. This technique has created an opportunity to validate explicit finite element (FE) models against dynamic test data. This study compared the outcomes of 15 human femoral specimens fractured using a drop tower with complementary specimen-specific explicit FE analysis. Correlation coefficient and root mean square error (RMSE) were found to be moderate for whole bone stiffness comparison (R(2)=0.3476 and 22.85% respectively). No correlation was found between experimentally and computationally predicted peak force, however, energy absorption comparison produced moderate correlation and RMSE (R(2)=0.4781 and 29.14% respectively). By comparing predicted strain maps to high speed video data we demonstrated the ability of the FE models to detect vulnerable portions of the bones. Based on our observations, we conclude that there exists a need to extend the current apparent level material models for bone to cover higher strain rates than previously tested experimentally. Copyright © 2014 Elsevier Ltd. All rights reserved.

Drop impact into a deep pool: Vortex shedding and jet formation

KAUST Repository

Agbaglah, Gilou; Thoraval, Marie-Jean; Thoroddsen, Sigurdur T; Zhang, Li V.; Fezzaa, Kamel; Deegan, Robert D.

2015-01-01

One of the simplest splashing scenarios results from the impact of a single drop on a deep pool. The traditional understanding of this process is that the impact generates an axisymmetric sheet-like jet that later breaks up into secondary droplets. Recently it was shown that even this simplest of scenarios is more complicated than expected because multiple jets can be generated from a single impact event and there are transitions in the multiplicity of jets as the experimental parameters are varied. Here, we use experiments and numerical simulations of a single drop impacting on a deep pool to examine the transition from impacts that produce a single jet to those that produce two jets. Using high-speed X-ray imaging methods we show that vortex separation within the drop leads to the formation of a second jet long after the formation of the ejecta sheet. Using numerical simulations we develop a phase diagram for this transition and show that the capillary number is the most appropriate order parameter for the transition. © 2014 Cambridge University Press.

Drop impact into a deep pool: Vortex shedding and jet formation

KAUST Repository

Agbaglah, Gilou

2015-01-02

One of the simplest splashing scenarios results from the impact of a single drop on a deep pool. The traditional understanding of this process is that the impact generates an axisymmetric sheet-like jet that later breaks up into secondary droplets. Recently it was shown that even this simplest of scenarios is more complicated than expected because multiple jets can be generated from a single impact event and there are transitions in the multiplicity of jets as the experimental parameters are varied. Here, we use experiments and numerical simulations of a single drop impacting on a deep pool to examine the transition from impacts that produce a single jet to those that produce two jets. Using high-speed X-ray imaging methods we show that vortex separation within the drop leads to the formation of a second jet long after the formation of the ejecta sheet. Using numerical simulations we develop a phase diagram for this transition and show that the capillary number is the most appropriate order parameter for the transition. © 2014 Cambridge University Press.

Pressure drop and arterial compliance - Two arterial parameters in one measurement.

Science.gov (United States)

Rotman, Oren M; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

2017-01-04

Coronary artery pressure-drop and distensibility (compliance) are two major, seemingly unrelated, parameters in the cardiovascular clinical setting, which are indicative of coronary arteries patency and atherosclerosis severity. While pressure drop is related to flow, and therefore serves as a functional indicator of a stenosis severity, the arterial distensibility is indicative of the arterial stiffness, and hence the arterial wall composition. In the present study, we hypothesized that local pressure drops are dependent on the arterial distensibility, and hence can provide information on both indices. The clinical significance is that a single measurement of pressure drop could potentially provide both functional and bio-mechanical metrics of lesions, and thus assist in real-time decision making prior to stenting. The goal of the current study was to set the basis for understanding this relationship, and define the accuracy and sensitivity required from the pressure measurement system. The investigation was performed using numerical fluid-structure interaction (FSI) simulations, validated experimentally using our high accuracy differential pressure measurement system. Simplified silicone mock coronary arteries with zero to intermediate size stenoses were used, and various combinations of arterial distensibility, diameter, and flow rate were simulated. Results of hyperemic flow cases were also compared to fractional flow reserve (FFR). The results indicate the potential clinical superiority of a high accuracy pressure drop-based parameter over FFR, by: (i) being more lesion-specific, (ii) the possibility to circumvent the FFR dependency on pharmacologically-induced hyperemia, and, (iii) by providing both functional and biomechanical lesion-specific information. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of drop freezing on microphysics of an ascending cloud parcel under biomass burning conditions

Science.gov (United States)

Diehl, K.; Simmel, M.; Wurzler, S.

There is some evidence that the initiation of warm rain is suppressed in clouds over regions with vegetation fires. Thus, the ice phase becomes important as another possibility to initiate precipitation. Numerical simulations were performed to investigate heterogeneous drop freezing for a biomass-burning situation. An air parcel model with a sectional two-dimensional description of the cloud microphysics was employed with parameterizations for immersion and contact freezing which consider the different ice nucleating efficiencies of various ice nuclei. Three scenarios were simulated resulting to mixed-phase or completely glaciated clouds. According to the high insoluble fraction of the biomass-burning particles drop freezing via immersion and contact modes was very efficient. The preferential freezing of large drops followed by riming (i.e. the deposition of liquid drops on ice particles) and the evaporation of the liquid drops (Bergeron-Findeisen process) caused a further decrease of the liquid drops' effective radius in higher altitudes. In turn ice particle sizes increased so that they could serve as germs for graupel or hailstone formation. The effects of ice initiation on the vertical cloud dynamics were fairly significant leading to a development of the cloud to much higher altitudes than in a warm cloud without ice formation.

Free-drop analysis of the transport container for hydrogen isotopes

International Nuclear Information System (INIS)

Lee, M. S.; Hong, C. S.; Baek, S. W.; Ahn, D. H.; Kim, K. R.; Lee, S. H.; Lim, S. P.; Jung, H. S.

2002-01-01

The vessel used for the transport of radioactive materials, containing hydrogen isotopes is evaluated for hypothetical accident conditions according to national regulations. The computational analysis is a cost effective tool to minimize testing and streamline the regulatory procedures, and supports experimental programs to qualify the container for the safe transport of radioactive materials. The numerical analysis of 9m free-drop onto a flat unyielding, horizontal surface has been performed using the explicit finite element computer program ABAQUS. Especially free-drop simulations for 30.deg. C tilted condition is precisely estimated

[Optimize dropping process of Ginkgo biloba dropping pills by using design space approach].

Science.gov (United States)

Shen, Ji-Chen; Wang, Qing-Qing; Chen, An; Pan, Fang-Lai; Gong, Xing-Chu; Qu, Hai-Bin

2017-07-01

In this paper, a design space approach was applied to optimize the dropping process of Ginkgo biloba dropping pills. Firstly, potential critical process parameters and potential process critical quality attributes were determined through literature research and pre-experiments. Secondly, experiments were carried out according to Box-Behnken design. Then the critical process parameters and critical quality attributes were determined based on the experimental results. Thirdly, second-order polynomial models were used to describe the quantitative relationships between critical process parameters and critical quality attributes. Finally, a probability-based design space was calculated and verified. The verification results showed that efficient production of Ginkgo biloba dropping pills can be guaranteed by operating within the design space parameters. The recommended operation ranges for the critical dropping process parameters of Ginkgo biloba dropping pills were as follows: dropping distance of 5.5-6.7 cm, and dropping speed of 59-60 drops per minute, providing a reference for industrial production of Ginkgo biloba dropping pills. Copyright© by the Chinese Pharmaceutical Association.

Lambda-dropping

DEFF Research Database (Denmark)

Danvy, Olivier; Schultz, Ulrik Pagh

1997-01-01

Lambda-lifting a functional program transforms it into a set of recursive equations. We present the symmetric transformation: lambda-dropping. Lambda-dropping a set of recursive equations restores block structure and lexical scope.For lack of scope, recursive equations must carry around all...... the parameters that any of their callees might possibly need. Both lambda-lifting and lambda-dropping thus require one to compute a transitive closure over the call graph:• for lambda-lifting: to establish the Def/Use path of each free variable (these free variables are then added as parameters to each...... of the functions in the call path);• for lambda-dropping: to establish the Def/Use path of each parameter (parameters whose use occurs in the same scope as their definition do not need to be passed along in the call path).Without free variables, a program is scope-insensitive. Its blocks are then free...

Dynamic response of an electrostatically actuated microbeam to drop-table test

International Nuclear Information System (INIS)

Ouakad, Hassen M; Younis, Mohammad I; Alsaleem, Fadi

2012-01-01

In this paper, we present a theoretical and experimental investigation into the dynamic response of an electrostatically actuated microbeam when subjected to drop-table test. For the theoretical part, a reduced-order model based on an Euler–Bernoulli beam model is utilized. The model accounts for the electrostatic bias on the microbeam and the shock pulse of the drop-table test. Simulation results are presented showing the combined effect of electrostatic force and mechanical shock in triggering early pull-in instability of the cantilever microbeams. The analytical simulation results are validated by finite-element results for the static response. Dynamic pull-in threshold as a function of the mechanical shock amplitude is shown over a wide range of shock spanning hundreds of thousands of g up to zero g. For the experimental part, a micromachined cantilever beam made of gold of length 50 µm is subjected to drop-table tests while being biased by electrostatic loads. Several experimental data are shown demonstrating the phenomenon of collapse due to the combined shock and electrostatic forces. It is also demonstrated that by biasing short and too stiff microbeams with electrostatic voltages, their stiffness is weakened. This lowers their threshold of collapse considerably to the range of acceleration that enables testing them with in-house shock testing equipments, such as drop-table tests. (paper)

Comparison of boiling heat transfer coefficient and pressure drop correlations for evaporators

International Nuclear Information System (INIS)

Eskin, N.; Arslan, G.

2009-01-01

Evaporator design is an important aspect for the HVAC industry. As the demand for more efficient and compact heat exchangers increase, researches on estimation of two-phase flow heat transfer and pressure drop gain importance. Due to complexity of the hydrodynamic and heat transfer of the two-phase flow, there are many experimental studies available for refrigerants int he literature. In this study, a model for boiling heat transfer in a horizontal tube has been developed and the simulation results are compared with experimental ones published in the literature. In these comparisons, heat transfer coefficient is calculated by using Kattan-Thome-Favrat (1998), Shah (1982), Kandilikar (1990), Chaddock and Brunemann (1967) correlations under different operational conditions such as saturation pressure, mass flux, the type of refrigerant and two phase flow pattern. Besides that flow pattern has also been considered in the simulation by using Thome and El Hajal (2002) model. For pressure drop Lockhart-Martinelli (1949), Mueller-Steinhagen-Hack (1986) and Groennerund (1979) correlations are used in simulations. Local vapor quality change at each experimental condition through the model is determined. Roughness is an important parameter for frictional pressure drop. Friction coefficient is determined by using Churchill (1977) model. (author)

A gene network simulator to assess reverse engineering algorithms.

Science.gov (United States)

Di Camillo, Barbara; Toffolo, Gianna; Cobelli, Claudio

2009-03-01

In the context of reverse engineering of biological networks, simulators are helpful to test and compare the accuracy of different reverse-engineering approaches in a variety of experimental conditions. A novel gene-network simulator is presented that resembles some of the main features of transcriptional regulatory networks related to topology, interaction among regulators of transcription, and expression dynamics. The simulator generates network topology according to the current knowledge of biological network organization, including scale-free distribution of the connectivity and clustering coefficient independent of the number of nodes in the network. It uses fuzzy logic to represent interactions among the regulators of each gene, integrated with differential equations to generate continuous data, comparable to real data for variety and dynamic complexity. Finally, the simulator accounts for saturation in the response to regulation and transcription activation thresholds and shows robustness to perturbations. It therefore provides a reliable and versatile test bed for reverse engineering algorithms applied to microarray data. Since the simulator describes regulatory interactions and expression dynamics as two distinct, although interconnected aspects of regulation, it can also be used to test reverse engineering approaches that use both microarray and protein-protein interaction data in the process of learning. A first software release is available at http://www.dei.unipd.it/~dicamill/software/netsim as an R programming language package.

Interface analysis of embedded chip resistor device package and its effect on drop shock reliability.

Science.gov (United States)

Park, Se-Hoon; Kim, Sun Kyoung; Kim, Young-Ho

2012-04-01

In this study, the drop reliability of an embedded passive package is investigated under JESD22-B111 condition. Chip resistors were buried in a PCB board, and it was electrically interconnected by electroless and electrolytic copper plating on a tin pad of a chip resistor without intermetallic phase. However tin, nickel, and copper formed a complex intermetallic phase, such as (Cu, Ni)6Sn5, (Cu, Ni)3Sn, and (Ni, Cu)3Sn2, at the via interface and via wall after reflow and aging. Since the amount of the tin layer was small compared with the solder joint, excessive intermetallic layer growth was not observed during thermal aging. Drop failures are always initiated at the IMC interface, and as aging time increases Cu-Sn-Ni IMC phases are transformed continuously due to Cu diffusion. We studied the intermetallic formation of the Cu via interface and simulated the stress distribution of drop shock by using material properties and board structure of embedded passive boards. The drop simulation was conducted according to the JEDEC standard. It was revealed that the crack starting point related to failure fracture changed due to intermetallic phase transformation along the via interface, and the position where failure occurs experimentally agrees well with our simulation results.

Controlling charge on levitating drops.

Science.gov (United States)

Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

2007-08-01

Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation.

Seismic and cask drop excitation evaluation of the tower shielding reactor

International Nuclear Information System (INIS)

Harris, S.P.; Stover, R.L.; Johnson, J.J.; Sumodobila, B.N.

1989-01-01

During the current shutdown of the Tower Shielding Reactor II (TSR-II), analyses were performed to determine the effect of nearby cask drops on the structural and mechanical integrity of the reactor. This evaluation was then extended to include the effects of earthquakes. Several analytic models were developed to simulate the effects of earthquake and cask drop excitation. A coupled soil-structure model was developed. As a result of the analyses, several hardware modifications and enhancements were implemented to ensure reactor integrity during future operations. 6 figs

Seismic and cask drop excitation evaluation of the Tower Shielding Reactor

International Nuclear Information System (INIS)

Stover, R.L.; Harris, S.P.; Johnson, J.J.; Sumodobila, B.N.

1989-01-01

During the current shutdown of the Tower Shielding Reactor II (TSR-II), analyses were performed to determine the effect of nearby cask drops on the structural and mechanical integrity of the reactor. This evaluation was then extended to include the effects of earthquakes. Several analytic models were developed to simulate the effects of earthquake and cask drop excitation. A coupled soil-structure model was developed. As a result of the analyses, several hardware modifications and enhancements were implemented to ensure reactor integrity during future operations

Fault roughness and strength heterogeneity control earthquake size and stress drop

KAUST Repository

Zielke, Olaf

2017-01-13

An earthquake\\'s stress drop is related to the frictional breakdown during sliding and constitutes a fundamental quantity of the rupture process. High-speed laboratory friction experiments that emulate the rupture process imply stress drop values that greatly exceed those commonly reported for natural earthquakes. We hypothesize that this stress drop discrepancy is due to fault-surface roughness and strength heterogeneity: an earthquake\\'s moment release and its recurrence probability depend not only on stress drop and rupture dimension but also on the geometric roughness of the ruptured fault and the location of failing strength asperities along it. Using large-scale numerical simulations for earthquake ruptures under varying roughness and strength conditions, we verify our hypothesis, showing that smoother faults may generate larger earthquakes than rougher faults under identical tectonic loading conditions. We further discuss the potential impact of fault roughness on earthquake recurrence probability. This finding provides important information, also for seismic hazard analysis.

Dynamics of deforming drops

OpenAIRE

Bouwhuis, W.

2015-01-01

Liquid drops play a dominant role in numerous industrial applications, such as spray coating, spray painting, inkjet printing, lithography processes, and spraying/sprinkling in agriculture or gardening. In all of these examples, the generation, flight, impact, and spreading of drops are separate stages of the corresponding industrial processes, which are all thoroughly studied for many years. This thesis focuses on drop dynamics, impact phenomena, Leidenfrost drops, and pouring flows. Based o...

Drop-Burst Length Evaluation of Urban VANETs

Directory of Open Access Journals (Sweden)

Awos Kh. Ali

2017-05-01

Full Text Available Networks performance is traditionally evaluated using packet delivery ratio (PDR and latency (delay. We propose an addition mechanism the drop-burst length (DBL. Many traffic classes display varying application-level performance according to the pattern of drops, even if the PDR is similar. In this paper we study a number of VANET scenarios and evaluate them with these three metrics. Vehicular Ad-hoc Networks (VANETs are an emerging class of Mobile Ad-hoc Network (MANETs where nodes include both moving vehicles and fixed infrastructure. VANETs aim to make transportation systems more intelligent by sharing information to improve safety and comfort. Efficient and adaptive routing protocols are essential for achieving reliable and scalable network performance. However, routing in VANETs is challenging due to the frequent, high-speed movement of vehicles, which results in frequent network topology changes. Our simulations are carried out using NS2 (for network traffic and SUMO (for vehicular movement simulators, with scenarios configured to reflect real-world conditions. The results show that OLSR is able to achieve a best DBL performance and demonstrates higher PDR performance comparing to AODV and GPSR under low network load. However, with GPSR, the network shows more stable PDR under medium and high network load. In term of delay OLSR is outperformed by GPSR.

Scanning drop sensor

Energy Technology Data Exchange (ETDEWEB)

Jin, Jian; Xiang, Chengxiang; Gregoire, John

2017-05-09

Electrochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.

Numerical study of the impact of a drop containing a bubble

Science.gov (United States)

Wei, Yu; Thoraval, Marie-Jean

2017-11-01

The impact of a drop has many applications from inkjet printing to the spreading of crops diseases. This fundamental phenomenon has therefore attracted a lot of interest from different fields. However, they have mostly focused on the simplest case of a drop containing a single fluid. In inkjet printing and in the deposition process of thermal barrier coatings, some bubbles can be present in the drop when it impacts on the solid surface. The presence of the bubble can produce some additional splashing, and affect the quality of the deposited material. Only a few studies have looked at this problem, and many questions still need to be investigated. Generally, there are three possibilities when a drop containing a bubble impacts onto a solid surface, namely the bubble stays in drop, the bubble bursts and a counter jet forms. We have performed axisymmetric numerical simulations with the open source code Gerris to study this vertical jet. We have systematically varied several parameters, including the impact velocity, the bubble size, the vertical position of the bubble, and the liquid properties. We were thus able to characterize under which condition the bubble leads to splashing and the velocity of the produced jet.

Design of a micromachined terahertz electromagnetic crystals (EMXT) channel-drop filter on silicon-substrate

Science.gov (United States)

Zhou, Kai; Liu, Yong; Si, Liming; Lv, Xin

2013-08-01

An integrated 0.5 THz electromagnetic crystals(EMXT) channel-drop filter based on PBG structure is presented in this paper. A channel-drop filter is a device in which a narrow bandwidth is redirected to another "drop" waveguide while other frequencies are unaffected. It's capable of extracting a certain frequency from a continuous spectrum in the bus channel and passing it to the test channel. It has potential applications in photonic integrated circuits, radio astronomy, THz spectroscopy, THz communication and remote sensing radar receiver. PBG structures(or photonic crystals) are periodic structures which possess band gaps, where the electromagnetic wave of certain ranges of frequencies cannot pass through and is reflected. The proposed channel-drop filter consists of input waveguide,output waveguide and PBG structure. The proposed filter is simulated using the finite element method and can be fabricated by micro-electromechanical systems (MEMS) technology,due to its low cost, high performance and high processing precision.The filter operation principle and fabrication process are discussed.The simulation results show its ability to filter the frequency of 496GHz with a linewidth of approximately 4GHz and transmission of 27.2 dB above background.The loss at resonant frequency is less than 1dB considering the thickness and roughness of gold layer required by the MEMS process.The channel drop efficiency is 84%.

Scanning drop sensor

Energy Technology Data Exchange (ETDEWEB)

Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Shinde, Aniketa A.; Guevarra, Dan W.; Jones, Ryan J.; Marcin, Martin R.; Mitrovic, Slobodan

2017-05-09

Electrochemical or electrochemical and photochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.

Extension of the M-D model for treating stress drops in salt

International Nuclear Information System (INIS)

Munson, D.E.; DeVries, K.L.; Fossum, A.F.; Callahan, G.D.

1993-01-01

Development of the multimechanism deformation (M-D) constitutive model for steady state creep, which incorporates irreversible workhardening and recovery transient strains, was motivated by the need to predict very long term closures in underground rooms for radioactive waste repositories in salt. The multimechanism deformation model for the creep deformation of salt is extended to treat the response of salt to imposed stress drops. Stress drop tests produce a very distinctive behavior where both reversible elastic strain and reversible time dependent strain occur. These transient strains are negative compared to the positive transient strains produced by the normal creep workhardening and recovery processes. A simple micromechanical evolutionary process is defined to account for the accumulation of these reversible strains, and their subsequent release with decreases in stress. A number of experimental stress drop tests for various stress drop magnitudes and temperatures are adequately simulated with the model

Numerical simulations of electric potential field for alternating current potential drop associated with surface cracks in low-alloy steel nuclear material

Science.gov (United States)

Yeh, Chun-Ping; Huang, Jiunn-Yuan

2018-04-01

Low-alloy steels used as structural materials in nuclear power plants are subjected to cyclic stresses during power plant operations. As a result, cracks may develop and propagate through the material. The alternating current potential drop technique is used to measure the lengths of cracks in metallic components. The depth of the penetration of the alternating current is assumed to be small compared to the crack length. This assumption allows the adoption of the unfolding technique to simplify the problem to a surface Laplacian field. The numerical modelling of the electric potential and current density distribution prediction model for a compact tension specimen and the unfolded crack model are presented in this paper. The goal of this work is to conduct numerical simulations to reduce deviations occurring in the crack length measurements. Numerical simulations were conducted on AISI 4340 low-alloy steel with different crack lengths to evaluate the electric potential distribution. From the simulated results, an optimised position for voltage measurements in the crack region was proposed.

Drop amalgam voltammetric study of lead complexation by natural ...

African Journals Online (AJOL)

A study of inorganic complexation of lead using drop amalgam voltammetry is described. The study has been carried out in simulated salt lake water and at ionic strength of 7.35 M, the predetermined ionic strength of Lake Katwe. The complexation of lead with the simple ligands (Cl-, CO32-) created anodic waves and the ...

The jet mass distribution after Soft Drop

Energy Technology Data Exchange (ETDEWEB)

Marzani, Simone [Universita di Genova, Dipartimento di Fisica, Genoa (Italy); INFN, Sezione di Genova (Italy); Schunk, Lais [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Soyez, Gregory [IPhT, CEA Saclay, CNRS UMR 3681, Gif-Sur-Yvette (France)

2018-02-15

We present a first-principle computation of the mass distribution of jets which have undergone the grooming procedure known as Soft Drop. This calculation includes the resummation of the large logarithms of the jet mass over its transverse momentum, up to next-to-logarithmic accuracy, matched to exact fixed-order results at next-to-leading order. We also include non-perturbative corrections obtained from Monte-Carlo simulations and discuss analytic expressions for hadronisation and Underlying Event effects. (orig.)

The jet mass distribution after Soft Drop

Science.gov (United States)

Marzani, Simone; Schunk, Lais; Soyez, Gregory

2018-02-01

We present a first-principle computation of the mass distribution of jets which have undergone the grooming procedure known as Soft Drop. This calculation includes the resummation of the large logarithms of the jet mass over its transverse momentum, up to next-to-logarithmic accuracy, matched to exact fixed-order results at next-to-leading order. We also include non-perturbative corrections obtained from Monte-Carlo simulations and discuss analytic expressions for hadronisation and Underlying Event effects.

Molecular dynamics study of the vaporization of an ionic drop

Science.gov (United States)

Galamba, N.

2010-09-01

The melting of a microcrystal in vacuum and subsequent vaporization of a drop of NaCl were studied through molecular dynamics simulations with the Born-Mayer-Huggins-Tosi-Fumi rigid-ion effective potential. The vaporization was studied for a single isochor at increasing temperatures until the drop completely vaporized, and gaseous NaCl formed. Examination of the vapor composition shows that the vapor of the ionic drop and gaseous NaCl are composed of neutral species, the most abundant of which, ranging from simple NaCl monomers (ion pairs) to nonlinear polymers, (NanCln)n=2-4. The enthalpies of sublimation, vaporization, and dissociation of the different vapor species are found to be in reasonable agreement with available experimental data. The decrease of the enthalpy of vaporization of the vapor species, with the radius of the drop decrease, accounts for a larger fraction of trimers and tetramers than that inferred from experiments. Further, the rhombic dimer is significantly more abundant than its linear isomer although the latter increases with the temperature. The present results suggest that both trimers and linear dimers may be important to explain the vapor pressure of molten NaCl at temperatures above 1500 K.

Simulation of the control rod drop under seismic excitations. Experimental program

International Nuclear Information System (INIS)

Chaudat, Th.

2001-01-01

This paper describes the experimental program that will be performed at the end of 1998 at the CEA Saclay on a specially constructed analytical mock-up of a control rod. The purpose of these tests is to partially validate the current methodology of the drop time numerical calculations of a PWR (pressurized water reactor) control rod under seismic excitations. The French nuclear partners (EDF and FRAMATOME) are involved in this program. (author)

Interactions between drops of a molten aluminum-lithium alloy and liquid water

International Nuclear Information System (INIS)

Nelson, L.S.

1994-01-01

In certain hypothesized nuclear reactor accident scenarios, 1- to 10-g drops of molten aluminum-lithium alloys might contact liquid water. Because vigorous steam explosions have occurred when large amounts of molten aluminum-lithium alloys were released into water or other coolants, it becomes important to know whether there will be explosions if smaller amounts of these molten alloys similarly come into contact with water. Therefore, the authors released drops of molten Al-3.1 wt pct Li alloy into deionized water at room temperature. The experiments were performed at local atmospheric pressure (0.085 MPa) without pressure transient triggers applied to the water. The absence of these triggers allowed them to (a) investigate whether spontaneous initiation of steam explosions would occur with these drops and (b) study the alloy-water chemical reactions. The drop sizes and melt temperatures were chosen to simulate melt globules that might form during the hypothesized melting of the aluminum-lithium alloy components

Bipedal gait model for precise gait recognition and optimal triggering in foot drop stimulator: a proof of concept.

Science.gov (United States)

Shaikh, Muhammad Faraz; Salcic, Zoran; Wang, Kevin I-Kai; Hu, Aiguo Patrick

2018-03-10

Electrical stimulators are often prescribed to correct foot drop walking. However, commercial foot drop stimulators trigger inappropriately under certain non-gait scenarios. Past researches addressed this limitation by defining stimulation control based on automaton of a gait cycle executed by foot drop of affected limb/foot only. Since gait is a collaborative activity of both feet, this research highlights the role of normal foot for robust gait detection and stimulation triggering. A novel bipedal gait model is proposed where gait cycle is realized as an automaton based on concurrent gait sub-phases (states) from each foot. The input for state transition is fused information from feet-worn pressure and inertial sensors. Thereafter, a bipedal gait model-based stimulation control algorithm is developed. As a feasibility study, bipedal gait model and stimulation control are evaluated in real-time simulation manner on normal and simulated foot drop gait measurements from 16 able-bodied participants with three speed variations, under inappropriate triggering scenarios and with foot drop rehabilitation exercises. Also, the stimulation control employed in commercial foot drop stimulators and single foot gait-based foot drop stimulators are compared alongside. Gait detection accuracy (98.9%) and precise triggering under all investigations prove bipedal gait model reliability. This infers that gait detection leveraging bipedal periodicity is a promising strategy to rectify prevalent stimulation triggering deficiencies in commercial foot drop stimulators. Graphical abstract Bipedal information-based gait recognition and stimulation triggering.

Drag &Drop, Multiphysics & Neural Net-based Lab-on-Chip Optimization Software, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The overall objective of this project is to develop a drag and drop, component library (fluidic lego) based, system simulation and optimization software for entire...

Experimental investigation of liquid-liquid system drop size distribution in Taylor-Couette flow and its application in the CFD simulation

Science.gov (United States)

Farzad, Reza; Puttinger, Stefan; Pirker, Stefan; Schneiderbauer, Simon

Liquid-liquid systems are widely used in the several industries such as food, pharmaceutical, cosmetic, chemical and petroleum. Drop size distribution (DSD) plays a key role as it strongly affects the overall mass and heat transfer in the liquid-liquid systems. To understand the underlying mechanisms single drop breakup experiments have been done by several researchers in the Taylor-Couette flow; however, most of those studies concentrate on the laminar flow regime and therefore, there is no sufficient amount of data in the case of in turbulent flows. The well-defined pattern of the Taylor-Couette flow enables the possibility to investigate DSD as a function of the local fluid dynamic properties, such as shear rate, which is in contrast to more complex devices such as stirred tank reactors. This paper deals with the experimental investigation of liquid-liquid DSD in Taylor-Couette flow. From high speed camera images we found a simple correlation for the Sauter mean diameter as a function of the local shear employing image processing. It is shown that this correlation holds for different oil-in-water emulsions. Finally, this empirical correlation for the DSD is used as an input data for a CFD simulation to compute the local breakup of individual droplets in a stirred tank reactor.

Single and two-phase flow pressure drop for CANFLEX bundle

Energy Technology Data Exchange (ETDEWEB)

Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G R; Bullock, D E [Atomic Energy of Canada Limited, Ontario (Canada)

1999-12-31

Friction factor and two-phase flow frictional multiplier for a CANFLEX bundle are newly developed and presented in this paper. CANFLEX as a 43-element fuel bundle has been developed jointly by AECL/KAERI to provide greater operational flexibility for CANDU reactor operators and designers. Friction factor and two-phase flow frictional multiplier have been developed by using the experimental data of pressure drops obtained from two series of Freon-134a (R-134a) CHF tests with a string of simulated CANFLEX bundles in a single phase and a two-phase flow conditions. The friction factor for a CANFLEX bundle is found to be about 20% higher than that of Blasius for a smooth circular pipe. The pressure drop predicted by using the new correlations of friction factor and two-phase frictional multiplier are well agreed with the experimental pressure drop data of CANFLEX bundle within {+-} 5% error. 11 refs., 5 figs. (Author)

Single and two-phase flow pressure drop for CANFLEX bundle

Energy Technology Data Exchange (ETDEWEB)

Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G. R.; Bullock, D. E. [Atomic Energy of Canada Limited, Ontario (Canada)

1998-12-31

Friction factor and two-phase flow frictional multiplier for a CANFLEX bundle are newly developed and presented in this paper. CANFLEX as a 43-element fuel bundle has been developed jointly by AECL/KAERI to provide greater operational flexibility for CANDU reactor operators and designers. Friction factor and two-phase flow frictional multiplier have been developed by using the experimental data of pressure drops obtained from two series of Freon-134a (R-134a) CHF tests with a string of simulated CANFLEX bundles in a single phase and a two-phase flow conditions. The friction factor for a CANFLEX bundle is found to be about 20% higher than that of Blasius for a smooth circular pipe. The pressure drop predicted by using the new correlations of friction factor and two-phase frictional multiplier are well agreed with the experimental pressure drop data of CANFLEX bundle within {+-} 5% error. 11 refs., 5 figs. (Author)

Multi-scale Analysis of MEMS Sensors Subject to Drop Impacts

Directory of Open Access Journals (Sweden)

Sarah Zerbini

2007-09-01

Full Text Available The effect of accidental drops on MEMS sensors are examined within the frame-work of a multi-scale finite element approach. With specific reference to a polysilicon MEMSaccelerometer supported by a naked die, the analysis is decoupled into macro-scale (at dielength-scale and meso-scale (at MEMS length-scale simulations, accounting for the verysmall inertial contribution of the sensor to the overall dynamics of the device. Macro-scaleanalyses are adopted to get insights into the link between shock waves caused by the impactagainst a target surface and propagating inside the die, and the displacement/acceleration his-tories at the MEMS anchor points. Meso-scale analyses are adopted to detect the most stresseddetails of the sensor and to assess whether the impact can lead to possible localized failures.Numerical results show that the acceleration at sensor anchors cannot be considered an ob-jective indicator for drop severity. Instead, accurate analyses at sensor level are necessary toestablish how MEMS can fail because of drops.

Analysis of SO/sub 2/ absorption with oxidation in an accelerating stream of drops

Energy Technology Data Exchange (ETDEWEB)

Kleinstreuer, C.; Ramachandran, R.S.; Altwicker, E.R.

1985-02-01

Trace gas absorption with chemical reaction in falling drops is of interest for the understanding of several aspects of a variety of engineering systems including gravity spray processes, flue gas desulfurization, as well as below-cloud scavenging by rain. The main components of such systems consist of the fluid dynamics of multiple drops in a gaseous environment and trace gas mass transfer with liquid-phase reaction. Here we deal specifically with the effects of mass and momentum transfer parameters such as fluid flow velocity, drop characteristics, film resistance layers, and the residence time of an accelerating isothermal stream of drops on the absorption and oxidation rates of sulfur dioxide. Predictive results obtained with a new computer simulation model, validated with measured data points, demonstrate the importance of such system parameters on SO/sub 2/ absorption.

The hydrodynamics of segmented two-phase flow in a circular tube with rapidly dissolving drops.

Science.gov (United States)

Leary, Thomas F; Ramachandran, Arun

2017-05-03

This article discusses boundary integral simulations of dissolving drops flowing through a cylindrical tube for large aspect ratio drops. The dynamics of drop dissolution is determined by three dimensionless parameters: λ, the viscosity of the drop fluid relative to the suspending fluid; Ca, the capillary number defining the ratio of the hydrodynamic force to the interfacial tension force; and k, a dissolution constant based on the velocity of dissolution. For a single dissolving drop, the velocity in the upstream region is greater than the downstream region, and for sufficiently large k, the downstream velocity can be completely reversed, particularly at low Ca. The upstream end of the drop travels faster and experiences greater deformation than the downstream end. The film thickness, δ, between the drop and the tube wall is governed by a delicate balance between dissolution and changes in the outer fluid velocity resulting from a fixed pressure drop across the tube and mass continuity. Therefore, δ, and consequently, the drop average velocity, can increase, decrease or be relatively invariant in time. For two drops flowing in succession, while low Ca drops maintain a nearly constant separation distance during dissolution, at sufficiently large Ca, for all values of k, dissolution increases the separation distance between drops. Under these conditions, the liquid segments between two adjacent drops can no longer be considered as constant volume stirred tanks. These results will guide the choices of geometry and operating parameters that will facilitate the characterization of fast gas-liquid reactions via two-phase segmented flows.

Hanging drop crystal growth apparatus

Science.gov (United States)

Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

1990-01-01

This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

Molecular dynamics study of the vaporization of an ionic drop.

Science.gov (United States)

Galamba, N

2010-09-28

The melting of a microcrystal in vacuum and subsequent vaporization of a drop of NaCl were studied through molecular dynamics simulations with the Born-Mayer-Huggins-Tosi-Fumi rigid-ion effective potential. The vaporization was studied for a single isochor at increasing temperatures until the drop completely vaporized, and gaseous NaCl formed. Examination of the vapor composition shows that the vapor of the ionic drop and gaseous NaCl are composed of neutral species, the most abundant of which, ranging from simple NaCl monomers (ion pairs) to nonlinear polymers, (Na(n)Cl(n))(n=2-4). The enthalpies of sublimation, vaporization, and dissociation of the different vapor species are found to be in reasonable agreement with available experimental data. The decrease of the enthalpy of vaporization of the vapor species, with the radius of the drop decrease, accounts for a larger fraction of trimers and tetramers than that inferred from experiments. Further, the rhombic dimer is significantly more abundant than its linear isomer although the latter increases with the temperature. The present results suggest that both trimers and linear dimers may be important to explain the vapor pressure of molten NaCl at temperatures above 1500 K.

von Kármán Vortex Street within an Impacting Drop

KAUST Repository

Thoraval, Marie-Jean

2012-06-29

The splashing of a drop impacting onto a liquid pool produces a range of different sized microdroplets. At high impact velocities, the most significant source of these droplets is a thin liquid jet emerging at the start of the impact from the neck that connects the drop to the pool. We use ultrahigh-speed video imaging in combination with high-resolution numerical simulations to show how this ejecta gives way to irregular splashing. At higher Reynolds numbers, its base becomes unstable, shedding vortex rings into the liquid from the free surface in an axisymmetric von Kármán vortex street, thus breaking the ejecta sheet as it forms.

von Kármán Vortex Street within an Impacting Drop

KAUST Repository

Thoraval, Marie-Jean; Takehara, Kohsei; Etoh, Takeharu Goji; Popinet, Sté phane; Ray, Pascal; Josserand, Christophe; Zaleski, Sté phane; Thoroddsen, Sigurdur T

2012-01-01

The splashing of a drop impacting onto a liquid pool produces a range of different sized microdroplets. At high impact velocities, the most significant source of these droplets is a thin liquid jet emerging at the start of the impact from the neck that connects the drop to the pool. We use ultrahigh-speed video imaging in combination with high-resolution numerical simulations to show how this ejecta gives way to irregular splashing. At higher Reynolds numbers, its base becomes unstable, shedding vortex rings into the liquid from the free surface in an axisymmetric von Kármán vortex street, thus breaking the ejecta sheet as it forms.

DROP TAIL AND RED QUEUE MANAGEMENT WITH SMALL BUFFERS:STABILITY AND HOPF BIFURCATION

Directory of Open Access Journals (Sweden)

Ganesh Patil

2011-06-01

Full Text Available There are many factors that are important in the design of queue management schemes for routers in the Internet: for example, queuing delay, link utilization, packet loss, energy consumption and the impact of router buffer size. By considering a fluid model for the congestion avoidance phase of Additive Increase Multiplicative Decrease (AIMD TCP, in a small buffer regime, we argue that stability should also be a desirable feature for network performance. The queue management schemes we study are Drop Tail and Random Early Detection (RED. For Drop Tail, the analytical arguments are based on local stability and bifurcation theory. As the buffer size acts as a bifurcation parameter, variations in it can readily lead to the emergence of limit cycles. We then present NS2 simulations to study the effect of changing buffer size on queue dynamics, utilization, window size and packet loss for three different flow scenarios. The simulations corroborate the analysis which highlights that performance is coupled with the notion of stability. Our work suggests that, in a small buffer regime, a simple Drop Tail queue management serves to enhance stability and appears preferable to the much studied RED scheme.

Vibration-Induced Climbing of Drops

Science.gov (United States)

Brunet, P.; Eggers, J.; Deegan, R. D.

2007-10-01

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.

Inferring Drosophila gap gene regulatory network: Pattern analysis of simulated gene expression profiles and stability analysis

NARCIS (Netherlands)

Fomekong-Nanfack, Y.; Postma, M.; Kaandorp, J.A.

2009-01-01

Background: Inference of gene regulatory networks (GRNs) requires accurate data, a method to simulate the expression patterns and an efficient optimization algorithm to estimate the unknown parameters. Using this approach it is possible to obtain alternative circuits without making any a priori

Lower Extremity Kinematics Differed Between a Controlled Drop-Jump and Volleyball-Takeoffs.

Science.gov (United States)

Beardt, Bradley S; McCollum, Myranda R; Hinshaw, Taylour J; Layer, Jacob S; Wilson, Margaret A; Zhu, Qin; Dai, Boyi

2018-04-03

Previous studies utilizing jump-landing biomechanics to predict anterior cruciate ligament injuries have shown inconsistent findings. The purpose of this study was to quantify the differences and correlations in jump-landing kinematics between a drop-jump, a controlled volleyball-takeoff, and a simulated-game volleyball-takeoff. Seventeen female volleyball players performed these three tasks on a volleyball court while three-dimensional kinematic data were collected by three calibrated camcorders. Participants demonstrated significantly increased jump height, shorter stance time, increased time differences in initial contact between two feet, increased knee and hip flexion at initial contact and decreased peak knee and hip flexion for both left and right legs, and decreased knee-ankle distance ratio at the lowest height of mid-hip for the two volleyball-takeoffs compared with the drop-jump (p jump and two volleyball-takeoffs. Controlled drop-jump kinematics may not represent jump-landing kinematics exhibited during volleyball competition. Jump-landing mechanics during sports-specific tasks may better represent those exhibited during sports competition and their associated risk of ACL injury compared with the drop-jump.

Drop Tower Physics

Science.gov (United States)

Dittrich, William A.

2014-01-01

The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

A perspective on the interfacial properties of nanoscopic liquid drops

International Nuclear Information System (INIS)

Malijevský, Alexandr; Jackson, George

2012-01-01

The structural and interfacial properties of nanoscopic liquid drops are assessed by means of mechanical, thermodynamical, and statistical mechanical approaches that are discussed in detail, including original developments at both the macroscopic level and the microscopic level of density functional theory (DFT). With a novel analysis we show that a purely macroscopic (static) mechanical treatment can lead to a qualitatively reasonable description of the surface tension and the Tolman length of a liquid drop; the latter parameter, which characterizes the curvature dependence of the tension, is found to be negative and has a magnitude of about a half of the molecular dimension. A mechanical slant cannot, however, be considered satisfactory for small finite-size systems where fluctuation effects are significant. From the opposite perspective, a curvature expansion of the macroscopic thermodynamic properties (density and chemical potential) is then used to demonstrate that a purely thermodynamic approach of this type cannot in itself correctly account for the curvature correction of the surface tension of liquid drops. We emphasize that any approach, e.g., classical nucleation theory, which is based on a purely macroscopic viewpoint, does not lead to a reliable representation when the radius of the drop becomes microscopic. The description of the enhanced inhomogeneity exhibited by small drops (particularly in the dense interior) necessitates a treatment at the molecular level to account for finite-size and surface effects correctly. The so-called mechanical route, which corresponds to a molecular-level extension of the macroscopic theory of elasticity and is particularly popular in molecular dynamics simulation, also appears to be unreliable due to the inherent ambiguity in the definition of the microscopic pressure tensor, an observation which has been known for decades but is frequently ignored. The union of the theory of capillarity (developed in the nineteenth

Analysis of voltage-drop near cold-electrodes of a combustion MHD generator

International Nuclear Information System (INIS)

Satyamurthy, P.; Venkatramani, N.; Rohatgi, V.K.

1983-01-01

In this paper turbulent compressible boundary layer equations for mass, momentum and energy are solved near the cold electrode wall of a combustion MHD generator. Arcs are simulated by freezing the electron temperature (and hence electrical conductivity) to a temperature called Tsub(arc) when gas temperature is less than Tsub(arc). Theoretical near electrode drop for various current densities along the flow direction is analysed for various Tsub(arc) temperatures and compared with experimentally obtained near electrode drop. It is found that the Tsub(arc) temperature increases as a square root along the flow direction and has linear dependency on current density. (author)

Motion of Drops on Surfaces with Wettability Gradients

Science.gov (United States)

Subramanian, R. Shankar; McLaughlin, John B.; Moumen, Nadjoua; Qian, Dongying

2002-11-01

A liquid drop present on a solid surface can move because of a gradient in wettability along the surface, as manifested by a gradient in the contact angle. The contact angle at a given point on the contact line between a solid and a liquid in a gaseous medium is the angle between the tangent planes to the liquid and the solid surfaces at that point and is measured within the liquid side, by convention. The motion of the drop occurs in the direction of increasing wettability. The cause of the motion is the net force exerted on the drop by the solid surface because of the variation of the contact angle around the periphery. This force causes acceleration of an initially stationary drop, and leads to its motion in the direction of decreasing contact angle. The nature of the motion is determined by the balance between the motivating force and the resisting hydrodynamic force from the solid surface and the surrounding gaseous medium. A wettability gradient can be chemically induced as shown by Chaudhury and Whitesides who provided unambiguous experimental evidence that drops can move in such gradients. The phenomenon can be important in heat transfer applications in low gravity, such as when condensation occurs on a surface. Daniel et al have demonstrated that the velocity of a drop on a surface due to a wettability gradient in the presence of condensation can be more than two orders of magnitude larger than that observed in the absence of condensation. In the present research program, we have begun to study the motion of a drop in a wettability gradient systematically using a model system. Our initial efforts will be restricted to a system in which no condensation occurs. The experiments are performed as follows. First, a rectangular strip of approximate dimensions 10 x 20 mm is cut out of a silicon wafer. The strip is cleaned thoroughly and its surface is exposed to the vapor from an alkylchlorosilane for a period lasting between one and two minutes inside a

Drop "impact" on an airfoil surface.

Science.gov (United States)

Wu, Zhenlong

2018-05-17

Drop impact on an airfoil surface takes place in drop-laden two-phase flow conditions such as rain and icing, which are encountered by wind turbines or airplanes. This phenomenon is characterized by complex nonlinear interactions that manifest rich flow physics and pose unique modeling challenges. In this article, the state of the art of the research about drop impact on airfoil surface in the natural drop-laden two-phase flow environment is presented. The potential flow physics, hazards, characteristic parameters, droplet trajectory calculation, drop impact dynamics and effects are discussed. The most key points in establishing the governing equations for a drop-laden flow lie in the modeling of raindrop splash and water film. The various factors affecting the drop impact dynamics and the effects of drop impact on airfoil aerodynamic performance are summarized. Finally, the principle challenges and future research directions in the field as well as some promising measures to deal with the adverse effects of drop-laden flows on airfoil performance are proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

Voltage Drop in a Ferroelectric Single Layer Capacitor by Retarded Domain Nucleation.

Science.gov (United States)

Kim, Yu Jin; Park, Hyeon Woo; Hyun, Seung Dam; Kim, Han Joon; Kim, Keum Do; Lee, Young Hwan; Moon, Taehwan; Lee, Yong Bin; Park, Min Hyuk; Hwang, Cheol Seong

2017-12-13

Ferroelectric (FE) capacitor is a critical electric component in microelectronic devices. Among many of its intriguing properties, the recent finding of voltage drop (V-drop) across the FE capacitor while the positive charges flow in is especially eye-catching. This finding was claimed to be direct evidence that the FE capacitor is in negative capacitance (NC) state, which must be useful for (infinitely) high capacitance and ultralow voltage operation of field-effect transistors. Nonetheless, the NC state corresponds to the maximum energy state of the FE material, so it has been widely accepted in the community that the material alleviates that state by forming ferroelectric domains. This work reports a similar V-drop effect from the 150 nm thick epitaxial BaTiO 3 ferroelectric thin film, but the interpretation was completely disparate; the V-drop can be precisely simulated by the reverse domain nucleation and propagation of which charge effect cannot be fully compensated for by the supplied charge from the external charge source. The disappearance of the V-drop effect was also observed by repeated FE switching only up to 10 cycles, which can hardly be explained by the involvement of the NC effect. The retained reverse domain nuclei even after the subsequent poling can explain such behavior.

Vortex flow in acoustically levitated drops

Energy Technology Data Exchange (ETDEWEB)

Yan, Z.L.; Xie, W.J. [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China); Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

2011-08-29

The internal flow of acoustically levitated water drops is investigated experimentally. This study reveals a kind of vortex flow which rotates in the meridional plane of the levitated drop. The magnitude of fluid velocity is nearly vanishing at the drop center, whereas it increases toward the free surface of a levitated drop until the maximum value of about 80 mm/s. A transition of streamline shapes from concentric circles to ellipses takes place at the distance of about 1.2 mm from the drop center. The fluid velocity distribution is plotted as a function of polar angle for seven characteristic streamlines. -- Highlights: → We experimentally observe the internal flow of acoustically levitated water drops. → We present a fascinating structure of vortex flow inside the levitated water drop. → This vortex flow rotates around the drop center in the meridional plane. → Velocity distribution information of this vortex flow is quantitatively analyzed.

Vortex flow in acoustically levitated drops

International Nuclear Information System (INIS)

Yan, Z.L.; Xie, W.J.; Wei, B.

2011-01-01

The internal flow of acoustically levitated water drops is investigated experimentally. This study reveals a kind of vortex flow which rotates in the meridional plane of the levitated drop. The magnitude of fluid velocity is nearly vanishing at the drop center, whereas it increases toward the free surface of a levitated drop until the maximum value of about 80 mm/s. A transition of streamline shapes from concentric circles to ellipses takes place at the distance of about 1.2 mm from the drop center. The fluid velocity distribution is plotted as a function of polar angle for seven characteristic streamlines. -- Highlights: → We experimentally observe the internal flow of acoustically levitated water drops. → We present a fascinating structure of vortex flow inside the levitated water drop. → This vortex flow rotates around the drop center in the meridional plane. → Velocity distribution information of this vortex flow is quantitatively analyzed.

Simulation of E. coli gene regulation including overlapping cell cycles, growth, division, time delays and noise.

Directory of Open Access Journals (Sweden)

Ruoyu Luo

Full Text Available Due to the complexity of biological systems, simulation of biological networks is necessary but sometimes complicated. The classic stochastic simulation algorithm (SSA by Gillespie and its modified versions are widely used to simulate the stochastic dynamics of biochemical reaction systems. However, it has remained a challenge to implement accurate and efficient simulation algorithms for general reaction schemes in growing cells. Here, we present a modeling and simulation tool, called 'GeneCircuits', which is specifically developed to simulate gene-regulation in exponentially growing bacterial cells (such as E. coli with overlapping cell cycles. Our tool integrates three specific features of these cells that are not generally included in SSA tools: 1 the time delay between the regulation and synthesis of proteins that is due to transcription and translation processes; 2 cell cycle-dependent periodic changes of gene dosage; and 3 variations in the propensities of chemical reactions that have time-dependent reaction rates as a consequence of volume expansion and cell division. We give three biologically relevant examples to illustrate the use of our simulation tool in quantitative studies of systems biology and synthetic biology.

Finite Element Analysis of Mechanical Characteristics of Dropped Eggs Based on Fluid-Solid Coupling Theory

Directory of Open Access Journals (Sweden)

Song Haiyan

2017-01-01

Full Text Available It is important to study the properties and mechanics of egg drop impacts in order to reduce egg loss during processing and logistics and to provide a basis for the protective packaging of egg products. In this paper, we present the results of our study of the effects of the structural parameters on the mechanical properties of an egg using a finite element model of the egg. Based on Fluid-Solid coupling theory, a finite element model of an egg was constructed using ADINA, a finite element calculation and analysis software package. To simplify the model, the internal fluid of the egg was considered to be a homogeneous substance. The egg drop impact was simulated by the coupling solution, and the feasibility of the model was verified by comparison with the experimental results of a drop test. In summary, the modeling scheme was shown to be feasible and the simulation results provide a theoretical basis for the optimum design of egg packaging and egg processing equipment.

Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

Directory of Open Access Journals (Sweden)

Alejandro Acevedo-Malavé

2011-09-01

Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

Study of Pressure Drop in Fixed Bed Reactor Using a Computational Fluid Dynamics (CFD Code

Directory of Open Access Journals (Sweden)

Soroush Ahmadi

2018-04-01

Full Text Available Pressure drops of water and critical steam flowing in the fixed bed of mono-sized spheres are studied using SolidWorks 2017 Flow Simulation CFD code. The effects of the type of bed formation, flow velocity, density, and pebble size are evaluated. A new equation is concluded from the data, which is able to estimate pressure drop of a packed bed for high particle Reynolds number, from 15,000 to 1,000,000.

"Self-Shaping" of Multicomponent Drops.

Science.gov (United States)

Cholakova, Diana; Valkova, Zhulieta; Tcholakova, Slavka; Denkov, Nikolai; Smoukov, Stoyan K

2017-06-13

In our recent study we showed that single-component emulsion drops, stabilized by proper surfactants, can spontaneously break symmetry and transform into various polygonal shapes during cooling [ Denkov Nature 2015 , 528 , 392 - 395 ]. This process involves the formation of a plastic rotator phase of self-assembled oil molecules beneath the drop surface. The plastic phase spontaneously forms a frame of plastic rods at the oil drop perimeter which supports the polygonal shapes. However, most of the common substances used in industry appear as mixtures of molecules rather than pure substances. Here we present a systematic study of the ability of multicomponent emulsion drops to deform upon cooling. The observed trends can be summarized as follows: (1) The general drop-shape evolution for multicomponent drops during cooling is the same as with single-component drops; however, some additional shapes are observed. (2) Preservation of the particle shape upon freezing is possible for alkane mixtures with chain length difference Δn ≤ 4; for greater Δn, phase separation within the droplet is observed. (3) Multicomponent particles prepared from alkanes with Δn ≤ 4 plastify upon cooling due to the formation of a bulk rotator phase within the particles. (4) If a compound, which cannot induce self-shaping when pure, is mixed with a certain amount of a compound which induces self-shaping, then drops prepared from this mixture can also self-shape upon cooling. (5) Self-emulsification phenomena are also observed for multicomponent drops. In addition to the three recently reported mechanisms of self-emulsification [ Tcholakova Nat. Commun. 2017 , ( 8 ), 15012 ], a new (fourth) mechanism is observed upon freezing for alkane mixtures with Δn > 4. It involves disintegration of the particles due to a phase separation of alkanes upon freezing.

Dynamics of deforming drops

NARCIS (Netherlands)

Bouwhuis, W.

2015-01-01

Liquid drops play a dominant role in numerous industrial applications, such as spray coating, spray painting, inkjet printing, lithography processes, and spraying/sprinkling in agriculture or gardening. In all of these examples, the generation, flight, impact, and spreading of drops are separate

Adding the 'heart' to hanging drop networks for microphysiological multi-tissue experiments.

Science.gov (United States)

Rismani Yazdi, Saeed; Shadmani, Amir; Bürgel, Sebastian C; Misun, Patrick M; Hierlemann, Andreas; Frey, Olivier

2015-11-07

Microfluidic hanging-drop networks enable culturing and analysis of 3D microtissue spheroids derived from different cell types under controlled perfusion and investigating inter-tissue communication in multi-tissue formats. In this paper we introduce a compact on-chip pumping approach for flow control in hanging-drop networks. The pump includes one pneumatic chamber located directly above one of the hanging drops and uses the surface tension at the liquid-air-interface for flow actuation. Control of the pneumatic protocol provides a wide range of unidirectional pulsatile and continuous flow profiles. With the proposed concept several independent hanging-drop networks can be operated in parallel with only one single pneumatic actuation line at high fidelity. Closed-loop medium circulation between different organ models for multi-tissue formats and multiple simultaneous assays in parallel are possible. Finally, we implemented a real-time feedback control-loop of the pump actuation based on the beating of a human iPS-derived cardiac microtissue cultured in the same system. This configuration allows for simulating physiological effects on the heart and their impact on flow circulation between the organ models on chip.

Measurements of refractive index and size of a spherical drop from Gaussian beam scattering in the primary rainbow region

Science.gov (United States)

Yu, Haitao; Sun, Hui; Shen, Jianqi; Tropea, Cameron

2018-03-01

The primary rainbow observed when light is scattered by a spherical drop has been exploited in the past to measure drop size and relative refractive index. However, if higher spatial resolution is required in denser drop ensembles/sprays, and to avoid then multiple drops simultaneously appearing in the measurement volume, a highly focused beam is desirable, inevitably with a Gaussian intensity profile. The present study examines the primary rainbow pattern resulting when a Gaussian beam is scattered by a spherical drop and estimates the attainable accuracy when extracting size and refractive index. The scattering is computed using generalized Lorenz-Mie theory (GLMT) and Debye series decomposition of the Gaussian beam scattering. The results of these simulations show that the measurement accuracy is dependent on both the beam waist radius and the position of the drop in the beam waist.

Microarray data and gene expression statistics for Saccharomyces cerevisiae exposed to simulated asbestos mine drainage

Directory of Open Access Journals (Sweden)

Heather E. Driscoll

2017-08-01

Full Text Available Here we describe microarray expression data (raw and normalized, experimental metadata, and gene-level data with expression statistics from Saccharomyces cerevisiae exposed to simulated asbestos mine drainage from the Vermont Asbestos Group (VAG Mine on Belvidere Mountain in northern Vermont, USA. For nearly 100 years (between the late 1890s and 1993, chrysotile asbestos fibers were extracted from serpentinized ultramafic rock at the VAG Mine for use in construction and manufacturing industries. Studies have shown that water courses and streambeds nearby have become contaminated with asbestos mine tailings runoff, including elevated levels of magnesium, nickel, chromium, and arsenic, elevated pH, and chrysotile asbestos-laden mine tailings, due to leaching and gradual erosion of massive piles of mine waste covering approximately 9 km2. We exposed yeast to simulated VAG Mine tailings leachate to help gain insight on how eukaryotic cells exposed to VAG Mine drainage may respond in the mine environment. Affymetrix GeneChip® Yeast Genome 2.0 Arrays were utilized to assess gene expression after 24-h exposure to simulated VAG Mine tailings runoff. The chemistry of mine-tailings leachate, mine-tailings leachate plus yeast extract peptone dextrose media, and control yeast extract peptone dextrose media is also reported. To our knowledge this is the first dataset to assess global gene expression patterns in a eukaryotic model system simulating asbestos mine tailings runoff exposure. Raw and normalized gene expression data are accessible through the National Center for Biotechnology Information Gene Expression Omnibus (NCBI GEO Database Series GSE89875 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE89875.

Application of Hanging Drop Technique for Kidney Tissue Culture.

Science.gov (United States)

Wang, Shaohui; Wang, Ximing; Boone, Jasmine; Wie, Jin; Yip, Kay-Pong; Zhang, Jie; Wang, Lei; Liu, Ruisheng

2017-01-01

The hanging drop technique is a well-established method used in culture of animal tissues. However, this method has not been used in adult kidney tissue culture yet. This study was to explore the feasibility of using this technique for culturing adult kidney cortex to study the time course of RNA viability in the tubules and vasculature, as well as the tissue structural integrity. In each Petri dish with the plate covered with sterile buffer, a section of mouse renal cortex was cultured within a drop of DMEM culture medium on the inner surface of the lip facing downward. The tissue were then harvested at each specific time points for Real-time PCR analysis and histological studies. The results showed that the mRNA level of most Na+ related transporters and cotransporters were stably maintained within 6 hours in culture, and that the mRNA level of most receptors found in the vasculature and glomeruli were stably maintained for up to 9 days in culture. Paraffin sections of the cultured renal cortex indicated that the tubules began to lose tubular integrity after 6 hours, but the glomeruli and vasculatures were still recognizable up to 9 days in culture. We concluded that adult kidney tissue culture by hanging drop method can be used to study gene expressions in vasculature and glomeruli. © 2017 The Author(s). Published by S. Karger AG, Basel.

Application of Hanging Drop Technique for Kidney Tissue Culture

Directory of Open Access Journals (Sweden)

Shaohui Wang

2017-05-01

Full Text Available Background/Aims: The hanging drop technique is a well-established method used in culture of animal tissues. However, this method has not been used in adult kidney tissue culture yet. This study was to explore the feasibility of using this technique for culturing adult kidney cortex to study the time course of RNA viability in the tubules and vasculature, as well as the tissue structural integrity. Methods: In each Petri dish with the plate covered with sterile buffer, a section of mouse renal cortex was cultured within a drop of DMEM culture medium on the inner surface of the lip facing downward. The tissue were then harvested at each specific time points for Real-time PCR analysis and histological studies. Results: The results showed that the mRNA level of most Na+ related transporters and cotransporters were stably maintained within 6 hours in culture, and that the mRNA level of most receptors found in the vasculature and glomeruli were stably maintained for up to 9 days in culture. Paraffin sections of the cultured renal cortex indicated that the tubules began to lose tubular integrity after 6 hours, but the glomeruli and vasculatures were still recognizable up to 9 days in culture. Conclusions: We concluded that adult kidney tissue culture by hanging drop method can be used to study gene expressions in vasculature and glomeruli.

Spatial and Temporal Stress Drop Variations of the 2011 Tohoku Earthquake Sequence

Science.gov (United States)

Miyake, H.

2013-12-01

The 2011 Tohoku earthquake sequence consists of foreshocks, mainshock, aftershocks, and repeating earthquakes. To quantify spatial and temporal stress drop variations is important for understanding M9-class megathrust earthquakes. Variability and spatial and temporal pattern of stress drop is a basic information for rupture dynamics as well as useful to source modeling. As pointed in the ground motion prediction equations by Campbell and Bozorgnia [2008, Earthquake Spectra], mainshock-aftershock pairs often provide significant decrease of stress drop. We here focus strong motion records before and after the Tohoku earthquake, and analyze source spectral ratios considering azimuth- and distance dependency [Miyake et al., 2001, GRL]. Due to the limitation of station locations on land, spatial and temporal stress drop variations are estimated by adjusting shifts from the omega-squared source spectral model. The adjustment is based on the stochastic Green's function simulations of source spectra considering azimuth- and distance dependency. We assumed the same Green's functions for event pairs for each station, both the propagation path and site amplification effects are cancelled out. Precise studies of spatial and temporal stress drop variations have been performed [e.g., Allmann and Shearer, 2007, JGR], this study targets the relations between stress drop vs. progression of slow slip prior to the Tohoku earthquake by Kato et al. [2012, Science] and plate structures. Acknowledgement: This study is partly supported by ERI Joint Research (2013-B-05). We used the JMA unified earthquake catalogue and K-NET, KiK-net, and F-net data provided by NIED.

Monitoring Agent for Detecting Malicious Packet Drops for Wireless Sensor Networks in the Microgrid and Grid-Enabled Vehicles

Directory of Open Access Journals (Sweden)

Jongbin Ko

2012-05-01

Full Text Available Of the range of wireless communication technologies, wireless sensor networks (WSN will be one of the most appropriate technologies for the Microgrid and Grid-enabled Vehicles in the Smartgrid. To ensure the security of WSN, the detection of attacks is more efficient than their prevention because of the lack of computing power. Malicious packet drops are the easiest means of attacking WSNs. Thus, the sensors used for constructing a WSN require a packet drop monitoring agent, such as Watchdog. However, Watchdog has a partial drop problem such that an attacker can manipulate the packet dropping rate below the minimum misbehaviour monitoring threshold. Furthermore, Watchdog does not consider real traffic situations, such as congestion and collision, and so it has no way of recognizing whether a packet drop is due to a real attack or network congestion. In this paper, we propose a malicious packet drop monitoring agent, which considers traffic conditions. We used the actual traffic volume on neighbouring nodes and the drop rate while monitoring a sending node for specific period. It is more effective in real network scenarios because unlike Watchdog it considers the actual traffic, which only uses the Pathrater. Moreover, our proposed method does not require authentication, packet encryption or detection packets. Thus, there is a lower likelihood of detection failure due to packet spoofing, Man-In-the Middle attacks or Wormhole attacks. To test the suitability of our proposed concept for a series of network scenarios, we divided the simulations into three types: one attack node, more than one attack nodes and no attack nodes. The results of the simulations meet our expectations.

Turbulence, bubbles and drops

NARCIS (Netherlands)

van der Veen, Roeland

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

NEW EQUATIONS OF STATE BASED ON THE LIQUID DROP MODEL OF HEAVY NUCLEI AND QUANTUM APPROACH TO LIGHT NUCLEI FOR CORE-COLLAPSE SUPERNOVA SIMULATIONS

International Nuclear Information System (INIS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2013-01-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ∼1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes

New Equations of State Based on the Liquid Drop Model of Heavy Nuclei and Quantum Approach to Light Nuclei for Core-collapse Supernova Simulations

Science.gov (United States)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

NEW EQUATIONS OF STATE BASED ON THE LIQUID DROP MODEL OF HEAVY NUCLEI AND QUANTUM APPROACH TO LIGHT NUCLEI FOR CORE-COLLAPSE SUPERNOVA SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

Detection and sizing of cracks using potential drop techniques based on electromagnetic induction

International Nuclear Information System (INIS)

Sato, Yasumoto; Kim, Hoon

2011-01-01

The potential drop techniques based on electromagnetic induction are classified into induced current focused potential drop (ICFPD) technique and remotely induced current potential drop (RICPD) technique. The possibility of numerical simulation of the techniques is investigated and the applicability of these techniques to the measurement of defects in conductive materials is presented. Finite element analysis (FEA) for the RICPD measurements on the plate specimen containing back wall slits is performed and calculated results by FEA show good agreement with experimental results. Detection limit of the RICPD technique in depth of back wall slits can also be estimated by FEA. Detection and sizing of artificial defects in parent and welded materials are successfully performed by the ICFPD technique. Applicability of these techniques to detection of cracks in field components is investigated, and most of the cracks in the components investigated are successfully detected by the ICFPD and RICPD techniques. (author)

Potential drops supported by ion density cavities in the dynamic response of a plasma diode to an applied field

International Nuclear Information System (INIS)

Bohm, M.; Torven, S.

1990-06-01

Experiments have shown that an applied voltage drop may either be supported by a cathode sheath or by a quasi-linear variation over the plasma lasting for several electron transit times. In the latter case an ion density cavity existed initially. An analytical model and numerical simulations are used to show that a cavity gives rise to a quasi-linear potential variation for applied voltage drops below a certain critical value. For larger values the drop concentrates to a cathode sheath. The quasi-linear profile steepens to a double layer for large cavity depths. (authors)

Semi-automatic image analysis methodology for the segmentation of bubbles and drops in complex dispersions occurring in bioreactors

Science.gov (United States)

Taboada, B.; Vega-Alvarado, L.; Córdova-Aguilar, M. S.; Galindo, E.; Corkidi, G.

2006-09-01

Characterization of multiphase systems occurring in fermentation processes is a time-consuming and tedious process when manual methods are used. This work describes a new semi-automatic methodology for the on-line assessment of diameters of oil drops and air bubbles occurring in a complex simulated fermentation broth. High-quality digital images were obtained from the interior of a mechanically stirred tank. These images were pre-processed to find segments of edges belonging to the objects of interest. The contours of air bubbles and oil drops were then reconstructed using an improved Hough transform algorithm which was tested in two, three and four-phase simulated fermentation model systems. The results were compared against those obtained manually by a trained observer, showing no significant statistical differences. The method was able to reduce the total processing time for the measurements of bubbles and drops in different systems by 21-50% and the manual intervention time for the segmentation procedure by 80-100%.

Axisymmetric Liquid Hanging Drops

Science.gov (United States)

Meister, Erich C.; Latychevskaia, Tatiana Yu

2006-01-01

The geometry of drops hanging on a circular capillary can be determined by numerically solving a dimensionless differential equation that is independent on any material properties, which enables one to follow the change of the height, surface area, and contact angle of drops hanging on a particular capillary. The results show that the application…

Coalescence of liquid drops: Different models versus experiment

KAUST Repository

Sprittles, J. E.

2012-01-01

The process of coalescence of two identical liquid drops is simulated numerically in the framework of two essentially different mathematical models, and the results are compared with experimental data on the very early stages of the coalescence process reported recently. The first model tested is the "conventional" one, where it is assumed that coalescence as the formation of a single body of fluid occurs by an instant appearance of a liquid bridge smoothly connecting the two drops, and the subsequent process is the evolution of this single body of fluid driven by capillary forces. The second model under investigation considers coalescence as a process where a section of the free surface becomes trapped between the bulk phases as the drops are pressed against each other, and it is the gradual disappearance of this "internal interface" that leads to the formation of a single body of fluid and the conventional model taking over. Using the full numerical solution of the problem in the framework of each of the two models, we show that the recently reported electrical measurements probing the very early stages of the process are better described by the interface formation/disappearance model. New theory-guided experiments are suggested that would help to further elucidate the details of the coalescence phenomenon. As a by-product of our research, the range of validity of different "scaling laws" advanced as approximate solutions to the problem formulated using the conventional model is established. © 2012 American Institute of Physics.

Application of hanging drop technique for stem cell differentiation and cytotoxicity studies.

Science.gov (United States)

Banerjee, Meenal; Bhonde, Ramesh R

2006-05-01

The aim of our study is to explore the possibility of using an ancient method of culture technique- the hanging drop technique for stem cell differentiation and cytotoxicity testing. We demonstrate here a variety of novel applications of this age old technique not only to harness the differentiation potential of stem cells into specific lineages but also for cytotoxicity studies. Here we have prepared hanging drop cultures by placing 20 microl micro-drops of nutrient media and 10% Fetal Calf Serum (FCS) containing cells of interest on the lids of 60 mm dishes. Bottom plates of the dishes were filled with sterile Phosphate Buffer Saline (PBS) to avoid desiccation of samples. Lids were then placed on the bottom plates to achieve hanging drop cultures. We utilized this technique for cultivation of ciliated epithelia to study cytotoxicity and differentiation of bone marrow stromal cells. Most importantly the modified culture technique presented here is simple, economical and cost effective in terms of the time taken and the reagents required and are amenable to goal specific modification such as cytotoxicity testing. It is advantageous over the existing system in terms of retention of viability and functionality for longer duration and for providing three dimensional growth micro-environment making it useful for organotypic cultures and in vivo simulation.

Adding the ‘heart’ to hanging drop networks for microphysiological multi-tissue experiments†

Science.gov (United States)

Yazdi, Saeed Rismani; Shadmani, Amir; Bürgel, Sebastian C.; Misun, Patrick M.; Hierlemann, Andreas; Frey, Olivier

2017-01-01

Microfluidic hanging-drop networks enable culturing and analysis of 3D microtissue spheroids derived from different cell types under controlled perfusion and investigating inter-tissue communication in multi-tissue formats. In this paper we introduce a compact on-chip pumping approach for flow control in hanging-drop networks. The pump includes one pneumatic chamber located directly above one of the hanging drops and uses the surface tension at the liquid–air-interface for flow actuation. Control of the pneumatic protocol provides a wide range of unidirectional pulsatile and continuous flow profiles. With the proposed concept several independent hanging-drop networks can be operated in parallel with only one single pneumatic actuation line at high fidelity. Closed-loop medium circulation between different organ models for multi-tissue formats and multiple simultaneous assays in parallel are possible. Finally, we implemented a real-time feedback control-loop of the pump actuation based on the beating of a human iPS-derived cardiac microtissue cultured in the same system. This configuration allows for simulating physiological effects on the heart and their impact on flow circulation between the organ models on chip. PMID:26401602

CANFLEX fuel bundle junction pressure drop

International Nuclear Information System (INIS)

Chung, H. J.; Chung, C. H.; Jun, J. S.; Hong, S. D.; Chang, S. K.; Kim, B. D.

1996-11-01

This report describes the junction pressure drop test results which are to used to determine the alignment angle between bundles to achieve the most probable fuel string pressure drop for randomly aligned bundles for use in the fuel string total pressure drop test. (author). 4 tabs., 17 figs

CANFLEX fuel bundle junction pressure drop

Energy Technology Data Exchange (ETDEWEB)

Chung, H. J.; Chung, C. H.; Jun, J. S.; Hong, S. D.; Chang, S. K.; Kim, B. D.

1996-11-01

This report describes the junction pressure drop test results which are to used to determine the alignment angle between bundles to achieve the most probable fuel string pressure drop for randomly aligned bundles for use in the fuel string total pressure drop test. (author). 4 tabs., 17 figs.

49 CFR 178.603 - Drop test.

Science.gov (United States)

2010-10-01

... used for the hydrostatic pressure or stacking test. Exceptions for the number of steel and aluminum..., non-resilient, flat and horizontal surface. (e) Drop height. Drop heights, measured as the vertical... than flat drops, the center of gravity of the test packaging must be vertically over the point of...

Dynamic and quasi-static simulation and analysis of the plutonium oxide/metal containers subject to 30-foot dropping

International Nuclear Information System (INIS)

Gong, C.; Miller, R.F.

1995-01-01

This analysis of the plutonium oxide/metal storage containers is in support of the design and testing project The results from the dynamic analysis show some important facts that have not been considered before. The internal bagless transfer can will have higher stress than the primary container. The quasi-static analysis provides a conservative solution. In both vertical upright drop (dynamic) and inclined upside down drop (quasi-static) the containers are structurally sound

Calculation of pressure drop and flow redistribution in the core of LMFBR type reactors

International Nuclear Information System (INIS)

Botelho, D.A.; Morgado, O.J.

1985-01-01

It is studied the flow redistribution through of fuel elements to the pressure drop calculation in the core of sodium cooled reactors. Using the quasi-static formulation of equations of the conservation of mass, energy and momentum, it was developed a computer program to flow redistribution calculations and pressure drop for different power levels and total flow simulating an arbitrary number of channels for sodium flowing . An optimization of the number of sufficient channels for calculations of this nature is done. The method is applied in studies of transients in the same reactor. (M.C.K.) [pt

Calculation of pressure drop and flow redistribution in the LMFBR core

International Nuclear Information System (INIS)

Morgado, O.J.

1984-01-01

The flow redistribution through fuel assemblies of LMFBRs: for the correct calculation of mass flow rates and pressure drop, are studied. Using a quasi-static formulation of conservation equations of mass and energy, a computer program was developed to simulate any arbitrary number of flow channels, operating at different linear power levels. Therefore f flow channels, operating at different linear power levels. Therefore, it was possible to perform thermal transient calculations for the Clinch River reactor core. The results of the calculations agree with the data found in the literature and supply accurate information about flow redistribution, average temperature, and pressure drop in the core, when the reactor is operated at conditions from the designed flow conditions, as is always the case in a load changing operation, or during transients. (Autor) [pt

Liquid-gas mass transfer at drop structures

DEFF Research Database (Denmark)

Matias, Natércia; Nielsen, Asbjørn Haaning; Vollertsen, Jes

2017-01-01

-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical...... sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were...... established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates...

Motion simulation of hydraulic driven safety rod using FSI method

International Nuclear Information System (INIS)

Jung, Jaeho; Kim, Sanghaun; Yoo, Yeonsik; Cho, Yeonggarp; Kim, Jong In

2013-01-01

Hydraulic driven safety rod which is one of them is being developed by Division for Reactor Mechanical Engineering, KAERI. In this paper the motion of this rod is simulated by fluid structure interaction (FSI) method before manufacturing for design verification and pump sizing. A newly designed hydraulic driven safety rod which is one of reactivity control mechanism is simulated using FSI method for design verification and pump sizing. The simulation is done in CFD domain with UDF. The pressure drop is changed slightly by flow rates. It means that the pressure drop is mainly determined by weight of moving part. The simulated velocity of piston is linearly proportional to flow rates so the pump can be sized easily according to the rising and drop time requirement of the safety rod using the simulation results

Tamoxifen-Containing Eye Drops Successfully Trigger Cre-Mediated Recombination in the Entire Eye.

Science.gov (United States)

Schlecht, Anja; Leimbeck, Sarah V; Tamm, Ernst R; Braunger, Barbara M

2016-01-01

Embryonic lethality in mice with targeted gene deletion is a major issue that can be circumvented by using Cre-loxP-based animal models. Various inducible Cre systems are available, e.g. such that are activated following tamoxifen treatment, and allow deletion of a specific target gene at any desired time point during the life span of the animal. In this study, we describe the efficiency of topical tamoxifen administration by eye drops using a Cre- reporter mouse strain (R26R). We report that tamoxifen-responsive CAGGCre-ER (TM) mice show a robust Cre- mediated recombination throughout the entire eye.

Nonlinear oscillations of inviscid free drops

Science.gov (United States)

Patzek, T. W.; Benner, R. E., Jr.; Basaran, O. A.; Scriven, L. E.

1991-01-01

The present analysis of free liquid drops' inviscid oscillations proceeds through solution of Bernoulli's equation to obtain the free surface shape and of Laplace's equation for the velocity potential field. Results thus obtained encompass drop-shape sequences, pressure distributions, particle paths, and the temporal evolution of kinetic and surface energies; accuracy is verified by the near-constant drop volume and total energy, as well as the diminutiveness of mass and momentum fluxes across drop surfaces. Further insight into the nature of oscillations is provided by Fourier power spectrum analyses of mode interactions and frequency shifts.

Thermal performance and pressure drop of spiral-tube ground heat exchangers for ground-source heat pump

International Nuclear Information System (INIS)

Jalaluddin; Miyara, Akio

2015-01-01

Thermal performance and pressure drop of the spiral-tube GHE were evaluated in this present work. A numerical simulation tool was used to carry out this research. The heat exchange rates per meter borehole depth of the spiral-tube GHE with various pitches and their pressure drops were compared with that of the U-tube GHE. Furthermore, a comparative analysis between a spiral pipe and straight pipe was performed. In comparison with the straight pipe, using the spiral pipe in the borehole increased the heat exchange rate to the ground per meter borehole depth. However, the pressure drop of water flow also increased due to increasing the length of pipe per meter borehole depth and its spiral geometry. The accuracy of the numerical model was verified for its pressure drop with some pressure drop correlations. The heat exchange rate and pressure drop of the GHEs are presented. As an example, the heat exchange rate per meter borehole depth of spiral pipe with 0.05 m pitch in the turbulent flow increased of 1.5 times. Its pressure drop also increased of 6 times. However, from the view point of energy efficiency, using the spiral pipe in the ground-source heat pump system gives a better performance than using the straight pipe. The heat exchange rate and pressure drop are important parameter in design of the ground-source heat pump (GSHP) system. - Highlights: • Thermal performance and pressure drop of spiral-tube GHE are presented. • Effects of spiral pitch on thermal performance and pressure drop are analyzed. • Using a spiral pipe increases heat exchange rate per meter borehole depth of GHE. • Pressure drop per meter borehole depth also increases in the spiral pipe.

Influence of turbulence on the drop growth in warm clouds, Part I: comparison of numerically and experimentally determined collision kernels

Directory of Open Access Journals (Sweden)

Christoph Siewert

2014-09-01

Full Text Available This study deals with the comparison of numerically and experimentally determined collision kernels of water drops in air turbulence. The numerical and experimental setups are matched as closely as possible. However, due to the individual numerical and experimental restrictions, it could not be avoided that the turbulent kinetic energy dissipation rate of the measurement and the simulations differ. Direct numerical simulations (DNS are performed resulting in a very large database concerning geometric collision kernels with 1470 individual entries. Based on this database a fit function for the turbulent enhancement of the collision kernel is developed. In the experiments, the collision rates of large drops (radius >7.5μm$> 7.5\\,\\text{\\textmu{}m}$ are measured. These collision rates are compared with the developed fit, evaluated at the measurement conditions. Since the total collision rates match well for all occurring dissipation rates the distribution information of the fit could be used to enhance the statistical reliability and for the first time an experimental collision kernel could be constructed. In addition to the collision rates, the drop size distributions at three consecutive streamwise positions are measured. The drop size distributions contain mainly small drops (radius <7.5μm$< 7.5\\,\\text{\\textmu{}m}$. The measured evolution of the drop size distribution is confronted with model calculations based on the newly derived fit of the collision kernel. It turns out that the observed fast evolution of the drop size distribution can only be modeled if the collision kernel for small drops is drastically increased. A physical argument for this amplification is missing since for such small drops, neither DNSs nor experiments have been performed. For large drops, for which a good agreement of the collision rates was found in the DNS and the experiment, the time for the evolution of the spectrum in the wind tunnel is too short to draw

A-DROP: A predictive model for the formation of oil particle aggregates (OPAs)

Science.gov (United States)

Zhao, Lin; Boufadel, Michel C.; Geng, Xiaolong; Lee, Kenneth; King, Thomas; Robinson, Brian; Fitzpatrick, Faith A.

2016-01-01

Oil–particle interactions play a major role in removal of free oil from the water column. We present a new conceptual–numerical model, A-DROP, to predict oil amount trapped in oil–particle aggregates. A new conceptual formulation of oil–particle coagulation efficiency is introduced to account for the effects of oil stabilization by particles, particle hydrophobicity, and oil–particle size ratio on OPA formation. A-DROP was able to closely reproduce the oil trapping efficiency reported in experimental studies. The model was then used to simulate the OPA formation in a typical nearshore environment. Modeling results indicate that the increase of particle concentration in the swash zone would speed up the oil–particle interaction process; but the oil amount trapped in OPAs did not correspond to the increase of particle concentration. The developed A-DROP model could become an important tool in understanding the natural removal of oil and developing oil spill countermeasures by means of oil–particle aggregation.

The Drop Tower Bremen -Experiment Operation

Science.gov (United States)

Könemann, Thorben; von Kampen, Peter; Rath, Hans J.

The idea behind the drop tower facility of the Center of Applied Space Technology and Micro-gravity (ZARM) in Bremen is to provide an inimitable technical opportunity of a daily access to short-term weightlessness on earth. In this way ZARM`s european unique ground-based microgravity laboratory displays an excellent economic alternative for research in space-related conditions at low costs comparable to orbital platforms. Many national and international ex-perimentalists motivated by these prospects decide to benefit from the high-quality and easy accessible microgravity environment only provided by the Drop Tower Bremen. Corresponding experiments in reduced gravity could open new perspectives of investigation methods and give scientists an impressive potential for a future technology and multidisciplinary applications on different research fields like Fundamental Physics, Astrophysics, Fluid Dynamics, Combus-tion, Material Science, Chemistry and Biology. Generally, realizing microgravity experiments at ZARM`s drop tower facility meet new requirements of the experimental hardware and may lead to some technical constraints in the setups. In any case the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) maintaining the drop tower facility is prepared to as-sist experimentalists by offering own air-conditioned laboratories, clean rooms, workshops and consulting engineers, as well as scientific personal. Furthermore, ZARM`s on-site apartment can be used for accommodations during the experiment campaigns. In terms of approaching drop tower experimenting, consulting of experimentalists is mandatory to successfully accomplish the pursued drop or catapult capsule experiment. For this purpose there will be a lot of expertise and help given by ZARM FAB mbH in strong cooperation to-gether with the experimentalists. However, in comparison to standard laboratory setups the drop or catapult capsule setup seems to be completely different at first view. While defining a

Pendent_Drop: An ImageJ Plugin to Measure the Surface Tension from an Image of a Pendent Drop

Directory of Open Access Journals (Sweden)

Adrian Daerr

2016-01-01

Full Text Available The pendent drop method for surface tension measurement consists in analysing the shape of an axisymmetric drop hanging from a capillary tube. This software is an add-on for the public domain image processing software ImageJ which matches a theoretical profile to the contour of a pendent drop, either interactively or by automatically minimising the mismatch. It provides an estimate of the surface tension, drop volume and surface area from the best matching parameters. It can be used in a headless setup. It is hosted on http://fiji.sc/List_of_update_sites with the source code on https://github.com/adaerr/pendent-drop

Monte Carlo simulation of a simple gene network yields new evolutionary insights.

Science.gov (United States)

Andrecut, M; Cloud, D; Kauffman, S A

2008-02-07

Monte Carlo simulations of a genetic toggle switch show that its behavior can be more complex than analytic models would suggest. We show here that as a result of the interplay between frequent and infrequent reaction events, such a switch can have more stable states than an analytic model would predict, and that the number and character of these states depend to a large extent on the propensity of transcription factors to bind to and dissociate from promoters. The effects of gene duplications differ even more; in analytic models, these seem to result in the disappearance of bi-stability and thus a loss of the switching function, but a Monte Carlo simulation shows that they can result in the appearance of new stable states without the loss of old ones, and thus in an increase of the complexity of the switch's behavior which may facilitate the evolution of new cellular functions. These differences are of interest with respect to the evolution of gene networks, particularly in clonal lines of cancer cells, where the duplication of active genes is an extremely common event, and often seems to result in the appearance of viable new cellular phenotypes.

"Dropping Your Genes." A Genetics Simulation in Meiosis, Fertilization & Reproduction.

Science.gov (United States)

Atkins, Thomas; Roderick, Joyce MacFall

1991-01-01

An activity that introduces students to the concepts of independent assortment of alleles during meiosis and gametogenesis, the richness of the variation that occurs as a result of allele recombination, and the unique phenotypes of offspring. Reproducible handouts with the directions and model chromosomes are provided. (KR)

Total Site Heat Integration Considering Pressure Drops

Directory of Open Access Journals (Sweden)

Kew Hong Chew

2015-02-01

Full Text Available Pressure drop is an important consideration in Total Site Heat Integration (TSHI. This is due to the typically large distances between the different plants and the flow across plant elevations and equipment, including heat exchangers. Failure to consider pressure drop during utility targeting and heat exchanger network (HEN synthesis may, at best, lead to optimistic energy targets, and at worst, an inoperable system if the pumps or compressors cannot overcome the actual pressure drop. Most studies have addressed the pressure drop factor in terms of pumping cost, forbidden matches or allowable pressure drop constraints in the optimisation of HEN. This study looks at the implication of pressure drop in the context of a Total Site. The graphical Pinch-based TSHI methodology is extended to consider the pressure drop factor during the minimum energy requirement (MER targeting stage. The improved methodology provides a more realistic estimation of the MER targets and valuable insights for the implementation of the TSHI design. In the case study, when pressure drop in the steam distribution networks is considered, the heating and cooling duties increase by 14.5% and 4.5%.

Drop size measurements in Venturi scrubbers

Energy Technology Data Exchange (ETDEWEB)

Fernandez Alonso, D.; Azzopardi, B.J. [Nottingham Univ. (United Kingdom). Dept. of Chemical Engineering; Goncalves, J.A.S.; Coury, J.R. [Universidade Federal de Sao Carlos (Brazil). Departamento de Engenharia Quimica

2001-07-01

Venturi scrubbers are high efficiency gas cleaners in which suspended particles are removed from gas streams by drops formed by liquid atomisation, usually in the Venturi throat. The size of the drops formed are of fundamental importance to the performance of the equipment, both in terms of pressure drop and dust removal efficiency. In this study, drop sizes in a cylindrical laboratory-scale Venturi scrubber were measured using a laser diffraction technique. Gas velocity and liquid to gas ratios varied from 50 to 90 m/s and 0.5 to 2.0 1/m{sup 3}, respectively. Water was injected using two different arrangements: either as jets in the throat or as a film just upstream of the convergence. Drop size measurements were performed at three positions in the case of jet injection: two located along the throat, and the last one at the end of the diffuser. The present data shows that the Sauter mean diameter of the spray can be well correlated by the equation of Boll et al. (J. Air Pollut. Control Assoc. 24 (1974) 932). Drop size distributions are satisfactorily represented by a Rosin-Rammler function. This paper also provides a simple method for calculating the parameters of the Rosin-Rammler function. As a result of this work, drop sizes in Venturi scrubbers can be estimated with much higher accuracy. (Author)

New moment magnitude scale, evidence of stress drop magnitude scaling and stochastic ground motion model for the French West Indies

Science.gov (United States)

Drouet, Stéphane; Bouin, Marie-Paule; Cotton, Fabrice

2011-12-01

In this study we analyse records from the 'Les Saintes' seismic sequence following the Mw= 6.3 earthquake of 2004 November 11, which occurred close to Guadeloupe (French West Indies). 485 earthquakes with magnitudes from 2 to 6, recorded at distances between 5 and 150 km are used. S-waves Fourier spectra are analysed to simultaneously determine source, path and site terms. The results show that the duration magnitude routinely estimated for the events that occurred in the region underestimate moment magnitude by 0.5 magnitude units over the whole magnitude range. From the inverted seismic moments and corner frequencies, we compute Brune's stress drops. We show that stress drops increase with increasing magnitude. The same pattern is observed on apparent stresses (i.e. the seismic energy-to-moment ratio). However, the rate of increase diminishes at high magnitudes, which is consistent with a constant stress drop model for large events. Using the results of the inversions, we perform ground motion simulations for the entire data set using the SMSIM stochastic simulation tool. The results show that a good fit (σ= 0.25) with observed data is achieved when the source is properly described by its moment magnitude and stress drop, and when site effects are taken into account. Although the magnitude-dependent stress drop model is giving better results than the constant stress drop model, the interevent variability remains high, which could suggest that stress drop depends on other parameters such as the depth of the hypocentre. In any case, the overall variability is of the same order of magnitude as usually observed in empirical ground motion prediction equations.

Partial coalescence from bubbles to drops

KAUST Repository

Zhang, F. H.

2015-10-07

The coalescence of drops is a fundamental process in the coarsening of emulsions. However, counter-intuitively, this coalescence process can produce a satellite, approximately half the size of the original drop, which is detrimental to the overall coarsening. This also occurs during the coalescence of bubbles, while the resulting satellite is much smaller, approximately 10 %. To understand this difference, we have conducted a set of coalescence experiments using xenon bubbles inside a pressure chamber, where we can continuously raise the pressure from 1 up to 85 atm and thereby vary the density ratio between the inner and outer fluid, from 0.005 up to unity. Using high-speed video imaging, we observe a continuous increase in satellite size as the inner density is varied from the bubble to emulsion-droplet conditions, with the most rapid changes occurring as the bubble density grows up to 15 % of that of the surrounding liquid. We propose a model that successfully relates the satellite size to the capillary wave mode responsible for its pinch-off and the overall deformations from the drainage. The wavelength of the primary wave changes during its travel to the apex, with the instantaneous speed adjusting to the local wavelength. By estimating the travel time of this wave mode on the bubble surface, we also show that the model is consistent with the experiments. This wavenumber is determined by both the global drainage as well as the interface shapes during the rapid coalescence in the neck connecting the two drops or bubbles. The rate of drainage is shown to scale with the density of the inner fluid. Empirically, we find that the pinch-off occurs when 60 % of the bubble fluid has drained from it. Numerical simulations using the volume-of-fluid method with dynamic adaptive grid refinement can reproduce these dynamics, as well as show the associated vortical structure and stirring of the coalescing fluid masses. Enhanced stirring is observed for cases with second

Sepsis from dropped clips at laparoscopic cholecystectomy

International Nuclear Information System (INIS)

Hussain, Sarwat

2001-01-01

We report seven patients in whom five dropped surgical clips and two gallstones were visualized in the peritoneal cavity, on radiological studies. In two, subphrenic abscesses and empyemas developed as a result of dropped clips into the peritoneal cavity during or following laparoscopic cholecystectomy. In one of these two, a clip was removed surgically from the site of an abscess. In two other patients dropped gallstones, and in three, dropped clips led to no complications. These were seen incidentally on studies done for other indications. Abdominal abscess secondary to dropped gallstones is a well-recognized complication of laparoscopic cholecystectomy (LC). We conclude that even though dropped surgical clips usually do not cause problems, they should be considered as a risk additional to other well-known causes of post-LC abdominal sepsis

Micro-splashing by drop impacts

KAUST Repository

Thoroddsen, Sigurdur T; Takehara, Kohsei; Etoh, Takeharugoji

2012-01-01

We use ultra-high-speed video imaging to observe directly the earliest onset of prompt splashing when a drop impacts onto a smooth solid surface. We capture the start of the ejecta sheet travelling along the solid substrate and show how it breaks up immediately upon emergence from the underneath the drop. The resulting micro-droplets are much smaller and faster than previously reported and may have gone unobserved owing to their very small size and rapid ejection velocities, which approach 100 m s-1, for typical impact conditions of large rain drops. We propose a phenomenological mechanism which predicts the velocity and size distribution of the resulting microdroplets. We also observe azimuthal undulations which may help promote the earliest breakup of the ejecta. This instability occurs in the cusp in the free surface where the drop surface meets the radially ejected liquid sheet. © 2012 Cambridge University Press.

Micro-splashing by drop impacts

KAUST Repository

Thoroddsen, Sigurdur T.

2012-07-18

We use ultra-high-speed video imaging to observe directly the earliest onset of prompt splashing when a drop impacts onto a smooth solid surface. We capture the start of the ejecta sheet travelling along the solid substrate and show how it breaks up immediately upon emergence from the underneath the drop. The resulting micro-droplets are much smaller and faster than previously reported and may have gone unobserved owing to their very small size and rapid ejection velocities, which approach 100 m s-1, for typical impact conditions of large rain drops. We propose a phenomenological mechanism which predicts the velocity and size distribution of the resulting microdroplets. We also observe azimuthal undulations which may help promote the earliest breakup of the ejecta. This instability occurs in the cusp in the free surface where the drop surface meets the radially ejected liquid sheet. © 2012 Cambridge University Press.

A boundary integral method for two-dimensional (non)-Newtonian drops in slow viscous flow

NARCIS (Netherlands)

Toose, E.M.; Geurts, B.J.; Kuerten, J.G.M.

1995-01-01

A boundary integral method for the simulation of the time-dependent deformation of Newtonian or non-Newtonian drops suspended in a Newtonian fluid is developed. The boundary integral formulation for Stokes flow is used and the non-Newtonian stress is treated as a source term which yields an extra

Pressure drop in ET-RR-1

International Nuclear Information System (INIS)

Khattab, M.; Mina, A.R.

1990-01-01

Measurements of pressure drop through a bundle comprising 16 rods and their lower arrangement grid as well as orifices similar to those of ET-RR-1 core have been done. Experiments are carried out under adiabatic turbulent flow conditions at about 35 degree C. Bundle Reynolds number range is 4 x 10 -2 x 10. Orifices of diameters 4.5, 3.25 or 2.5 cm. are mounted underneath the bundle. The bundle and lower grid pressure drop coefficients are 3.75 and 1.8 respectively. Orifices pressure drop coefficients are 2.65, 19.67 and 53.55 respectively. The ratio of bundle pressure drop to that of 4.5 cm. Orifice diameter is 1.415. The pressure drop coefficients are utilizer to calculate flow through bundles. The flow rate per bundle is 39.1, 20.4 or 13.1 m 3 /hr. Depending on orifice diameter

Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

Science.gov (United States)

Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.

2016-08-01

Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

Drop trampoline

Science.gov (United States)

Chantelot, Pierre; Coux, Martin; Clanet, Christophe; Quere, David

2017-11-01

Superhydrophobic substrates inspired from the lotus leaf have the ability to reflect impacting water drops. They do so very efficiently and contact lasts typically 10 ms for millimetric droplets. Yet unlike a lotus leaf most synthetic substrates are rigid. Focusing on the interplay between substrate flexibility and liquid repellency might allow us to understand the dynamic properties of natural surfaces. We perform liquid marbles impacts at velocity V onto thin ( 0.01 mm) stretched circular PDMS membranes. We obtain contact time reductions of up to 70%. The bouncing mechanism is drastically modified compared to that on a rigid substrate: the marble leaves the substrate while it is still spread in a disk shape as it is kicked upwards by the membrane. We show that the bouncing is controlled by an interplay between the dynamics of the drop and the membrane.

Thermocapillary reorientation of Janus drops

Science.gov (United States)

Rosales, Rodolfo; Saenz, Pedro

2017-11-01

Janus drops, named after the Ancient Roman two-faced god, are liquid drops formed from two immiscible fluids. Experimental observations indicate that a Janus drop may re-orientate in response to an applied external thermal gradient due to the Marangoni effect. Depending on the angle between the interior interface and the direction of the temperature gradient, disparities in the physical properties of the constituent liquids may lead to asymmetries in the thermocapillary flow. As a result, the drop will move along a curved path until a torque-free configuration is achieved, point after which it will continue on a straight trajectory. Here, we present the results of a theoretical investigation of this realignment phenomenon in the Stokes regime and in the limit of non-deformable interfaces. A 3D semi-analytical method in terms of polar spherical harmonics is developed to characterize and rationalize the hydrodynamic response (forces and torques), flow (velocity and temperature distribution) and trajectory of a Janus drop moving during the temperature-driven reorientation process. Furthermore, we discuss how this phenomenon may be exploited to develop dynamically reconfigurable micro-lenses. This work was partially supported by the US National Science Foundation through Grants DMS-1614043 and DMS-1719637.

Optimal formation of genetically modified and functional pancreatic islet spheroids by using hanging-drop strategy.

Science.gov (United States)

Kim, H J; Alam, Z; Hwang, J W; Hwang, Y H; Kim, M J; Yoon, S; Byun, Y; Lee, D Y

2013-03-01

Rejection and hypoxia are important factors causing islet loss at an early stage after pancreatic islet transplantation. Recently, islets have been dissociated into single cells for reaggregation into so-called islet spheroids. Herein, we used a hanging-drop strategy to form islet spheroids to achieve functional equivalence to intact islets. To obtain single islet cells, we dissociated islets with trypsin-EDTA digestion for 10 minutes. To obtain spheroids, we dropped various numbers of single cells (125, 250, or 500 cells/30 μL drop) onto a Petri dish, that was inverted for incubation in humidified air containing 5% CO(2) at 37 °C for 7 days. The aggregated spheroids in the droplets were harvested for further culture. The size of the aggregated islet spheroids depended on the number of single cells (125-500 cells/30 μL droplet). Their morphology was similar to that of intact islets without any cellular damage. When treated with various concentrations of glucose to evaluate responsiveness, their glucose-mediated stimulation index value was similar to that of intact islets, an observation that was attributed to strong cell-to-cell interactions in islet spheroids. However, islet spheroids aggregated in general culture dishes showed abnormal glucose responsiveness owing to weak cell-to-cell interactions. Cell-to-cell interactions in islet spheroids were confirmed with an anti-connexin-36 monoclonal antibody. Finally, nonviral poly(ethylene imine)-mediated interleukin-10 cytokine gene delivered beforehand into dissociated single cells before formation of islet spheroids increased the gene transfection efficacy and interleukin-10 secretion from islet spheroids >4-fold compared with intact islets. These results demonstrated the potential application of genetically modified, functional islet spheroids with of controlled size and morphology using an hanging-drop technique. Copyright © 2013 Elsevier Inc. All rights reserved.

Blood drop patterns: Formation and applications.

Science.gov (United States)

Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei

2016-05-01

The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

An efficient parallel stochastic simulation method for analysis of nonviral gene delivery systems

KAUST Repository

Kuwahara, Hiroyuki; Gao, Xin

2011-01-01

DNA molecules into the nucleus of target cells. Several computational and experimental studies have shown that the design process of synthetic gene transfer vectors can be greatly enhanced by computational modeling and simulation. This paper proposes a

Directly Estimating Earthquake Rupture Area using Second Moments to Reduce the Uncertainty in Stress Drop

Science.gov (United States)

McGuire, Jeffrey J.; Kaneko, Yoshihiro

2018-06-01

The key kinematic earthquake source parameters: rupture velocity, duration and area, shed light on earthquake dynamics, provide direct constraints on stress-drop, and have implications for seismic hazard. However, for moderate and small earthquakes, these parameters are usually poorly constrained due to limitations of the standard analysis methods. Numerical experiments by Kaneko and Shearer [2014,2015] demonstrated that standard spectral fitting techniques can lead to roughly 1 order of magnitude variation in stress-drop estimates that do not reflect the actual rupture properties even for simple crack models. We utilize these models to explore an alternative approach where we estimate the rupture area directly. For the suite of models, the area averaged static stress drop is nearly constant for models with the same underlying friction law, yet corner frequency based stress-drop estimates vary by a factor of 5-10 even for noise free data. Alternatively, we simulated inversions for the rupture area as parameterized by the second moments of the slip distribution. A natural estimate for the rupture area derived from the second moments is A=πLcWc, where Lc and Wc are the characteristic rupture length and width. This definition yields estimates of stress drop that vary by only 10% between the models but are slightly larger than the true area-averaged values. We simulate inversions for the second moments for the various models and find that the area can be estimated well when there are at least 15 available measurements of apparent duration at a variety of take-off angles. The improvement compared to azimuthally-averaged corner-frequency based approaches results from the second moments accounting for directivity and removing the assumption of a circular rupture area, both of which bias the standard approach. We also develop a new method that determines the minimum and maximum values of rupture area that are consistent with a particular dataset at the 95% confidence

Experimental observations of anomalous potential drops over ion density cavities

International Nuclear Information System (INIS)

Bohm, M.

1991-08-01

Experiments are reported showing the plasma potential response when a step voltage is applied over the plasma column between the two plasma sources in a triple plasma machine. The time resolution is sufficient to resolve potential variations caused essentially by the electron motion, and two independent probe methods are used to obtain this time resolution. Depending on the initial conditions two different responses were observed on the time scale of the electron motion. When the initial ion density varies along the plasma column and has a local minimum (that is, forms an ion density cavity), the applied potential drop becomes distributed over the cavity after a few electron transit times. Later the profile steepens to a double layer on the time scale of the ion motion. The width of the cavity is comparable to the length of the plasma column. When the initial density is axially uniform, most of the potential drop instead concentrates to a narrow region at the low potential end of the plasma column after a few electron transit times. On the time scale of the ion motion this potential drop begins to propagate into the plasma as a double layer. The results obtained are consistent with those from numerical simulations with similar boundary conditions. Further experiments are necessary to get conclusive insight into the voltage supporting capability of an ion density cavity. (au) (34 refs.)

Experimental and numerical studies on pressure drop in reverse electrodialysis: Effect of unit cell configuration

Energy Technology Data Exchange (ETDEWEB)

Hong, Sung Kook; Choi, Kyung Soo [Advanced Combustion Laboratory, Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Chan Soo; Hwang, Kyo Sik; Han, Ji Hyung; Kim, Han Ki; Jeong, Nam Jo [Jeju Global Research Center, Korea Institute of Energy Research, Jeju (Korea, Republic of)

2016-11-15

Experimental and numerical studies on pressure drop in Reverse electrodialysis (RED) were performed. In this study, a module with 200 unit cells is considered for the demonstration of bench-scale RED module and two different unit cell configurations are utilized. Pressure drop through the module is measured by varying flow rates. For evaluating the hydrodynamic characteristics in the unit cell, a numerical simulation is also conducted and the simplified method using a porous media model is employed to simulate the channel filled with spacer. Due to the insertion of spacer and narrow channel, great pressure loss occurs along the unit cell. Based on estimated pressure data, high pressure difference between seawater and fresh water channel takes place locally in the unit cell configuration with crossflow direction, leading to a leakage problem through the membrane and finally degradation in the output power. Consequently, it is confirmed that the unit cell configuration is one of the important design parameters in a RED module.

Hydrothermal waves in evaporating sessile drops

OpenAIRE

Brutin, D.; Rigollet, F.; Niliot, C. Le

2009-01-01

Drop evaporation is a simple phenomena but still unclear concerning the mechanisms of evaporation. A common agreement of the scientific community based on experimental and numerical work evidences that most of the evaporation occurs at the triple line. However, the rate of evaporation is still empirically predicted due to the lack of knowledge on the convection cells which develop inside the drop under evaporation. The evaporation of sessile drop is more complicated than it appears due to the...

Isolated drops from capillary jets by means of Gaussian wave packets

Science.gov (United States)

Garcia, Francisco Javier; Gonzalez, Heliodoro; Castrejon-Pita, Alfonso Arturo; Castrejon-Pita, Jose Rafael; Gomez-Aguilar, Francisco Jose

2017-11-01

The possibility of obtaining isolated drops from a continuous liquid jet through localized velocity perturbations is explored analytically, numerically and experimentally. We show that Gaussian wave packets are appropriate for this goal. A temporal linear analysis predicts the early evolution of these wave packets and provides an estimate of the breakup length of the jet. Non-linear numerical simulations allow us both to corroborate these results and to obtain the shape of the surface of the jet prior to breakup. Finally, we show experimental evidence that stimulating with a Gaussian wave packet can lead to the formation of an isolated drop without disturbing the rest of the jet. The authors acknowledge support from the Spanish Government under Contract No. FIS2014-25161, the Junta de Andalucia under Contract No. P11-FQM-7919, the EPSRC-UK via the Grant EP/P024173/1, and the Royal Society.

Numerical Study on Bubble Dynamics and Two-Phase Frictional Pressure Drop of Slug Flow Regime in Adiabatic T-junction Square Microchannel

Directory of Open Access Journals (Sweden)

K. Kishor

2017-10-01

Full Text Available In this study, bubble dynamics and frictional pressure drop associated with gas liquid two-phase slug flow regime in adiabatic T-junction square microchannel has been investigated using CFD. A comprehensive study on the mechanism of bubble formation via squeezing and shearing regime is performed. The randomness and recirculation profiles observed in the squeezing regime are significantly higher as compared to the shearing regime during formation of the slug. Further, effects of increasing gas velocity on bubble length are obtained at fixed liquid velocities and simulated data displayed good agreement with available correlations in literature. The frictional pressure drop for slug flow regime from simulations are also obtained and evaluated against existing separated flow models. A regression correlation has also been developed by modifying C-parameter using separated flow model, which improves the prediction of two-phase frictional pressure drop data within slug flow region, with mean absolute error of 10 %. The influences of fluid properties such as liquid viscosity and surface tension on the two-phase frictional pressure drop are also investigated and compared with developed correlation. The higher liquid viscosity and lower surface tension value resulted in bubble formation via shearing regime.

Fundamental Drop Dynamics and Mass Transfer Experiments to Support Solvent Extraction Modeling Efforts

International Nuclear Information System (INIS)

Christensen, Kristi; Rutledge, Veronica; Garn, Troy

2011-01-01

In support of the Nuclear Energy Advanced Modeling Simulation Safeguards and Separations (NEAMS SafeSep) program, the Idaho National Laboratory (INL) worked in collaboration with Los Alamos National Laboratory (LANL) to further a modeling effort designed to predict mass transfer behavior for selected metal species between individual dispersed drops and a continuous phase in a two phase liquid-liquid extraction (LLE) system. The purpose of the model is to understand the fundamental processes of mass transfer that occur at the drop interface. This fundamental understanding can be extended to support modeling of larger LLE equipment such as mixer settlers, pulse columns, and centrifugal contactors. The work performed at the INL involved gathering the necessary experimental data to support the modeling effort. A custom experimental apparatus was designed and built for performing drop contact experiments to measure mass transfer coefficients as a function of contact time. A high speed digital camera was used in conjunction with the apparatus to measure size, shape, and velocity of the drops. In addition to drop data, the physical properties of the experimental fluids were measured to be used as input data for the model. Physical properties measurements included density, viscosity, surface tension and interfacial tension. Additionally, self diffusion coefficients for the selected metal species in each experimental solution were measured, and the distribution coefficient for the metal partitioning between phases was determined. At the completion of this work, the INL has determined the mass transfer coefficient and a velocity profile for drops rising by buoyancy through a continuous medium under a specific set of experimental conditions. Additionally, a complete set of experimentally determined fluid properties has been obtained. All data will be provided to LANL to support the modeling effort.

Parametric resonance in acoustically levitated water drops

International Nuclear Information System (INIS)

Shen, C.L.; Xie, W.J.; Wei, B.

2010-01-01

Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.

Parametric resonance in acoustically levitated water drops

Energy Technology Data Exchange (ETDEWEB)

Shen, C.L.; Xie, W.J. [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China); Wei, B., E-mail: bbwei@nwpu.edu.c [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

2010-05-10

Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.

The effect of reported high-velocity small raindrops on inferred drop size distributions and derived power laws

Directory of Open Access Journals (Sweden)

H. Leijnse

2010-07-01

Full Text Available It has recently been shown that at high rainfall intensities, small raindrops may fall with much larger velocities than would be expected from their diameters. These were argued to be fragments of recently broken-up larger drops. In this paper we quantify the effect of this phenomenon on raindrop size distribution measurements from a Joss-Waldvogel disdrometer, a 2-D Video Distrometer, and a vertically-pointing Doppler radar. Probability distributions of fall velocities have been parameterized, where the parameters are functions of both rainfall intensity and drop size. These parameterizations have been used to correct Joss-Waldvogel disdrometer measurements for this phenomenon. The effect of these corrections on fitted scaled drop size distributions are apparent but not major. Fitted gamma distributions for three different types of rainfall have been used to simulate drop size measurements. The effect of the high-velocity small drops is shown to be minor. Especially for the purpose of remote sensing of rainfall using radar, microwave links, or optical links, the errors caused by using the slightly different retrieval relations will be masked completely by other error sources.

Flow of Hydrolysed Polyacrylamide Mother Liquor through Filter Bag: Detecting the Effects of Formulation and Process Properties on Pressure Drop

Directory of Open Access Journals (Sweden)

Zi-Ming Feng

2016-01-01

Full Text Available Hydrolysed polyacrylamide (HPAM mother liquor is mainly used to extract oil. The HPAM solution is needed to filter the impurity using a bag filter before it is injected into the oil well. Therefore, the pressure drop of HPAM mother liquor must be less than 0.02 MPa in the processing of impurity filtration. The influence factors on pressure drop need to be researched. In this work, the computational fluid dynamics program (CFD was used to research some key influence factors on pressure drop, such as porosity, outlet pressure of filter, inlet flow rate and viscosity of mother liquor. The simulation results indicated that with increasing porosity, outlet pressure, inlet flow rate and mother liquor viscosity, the pressure drop had increased after flowing through the filter bag.

Deformed liquid marbles: Freezing drop oscillations with powders

KAUST Repository

Marston, Jeremy; Zhu, Y.; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur T

2012-01-01

In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

Deformed liquid marbles: Freezing drop oscillations with powders

KAUST Repository

Marston, Jeremy

2012-09-01

In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

Modelling of Fed-batch Fermentation Process with Droppings for L-lysine Production

Directory of Open Access Journals (Sweden)

Velitchka Ivanova

2006-04-01

Full Text Available The aim of the article is the development of dynamic unstructured model of L-lysine fed-batch fermentation process with droppings. This approach includes the following procedures: description of the process by generalized stoichiometric equations; preliminary data processing; identification of the specific rates (growth rate (mu , substrate utilization rate (nu, production rate (rho; establishment and optimization of the dynamic model of the process; simulation researches.

Effects of simulated microgravity on gene expression and biological phenotypes of a single generation Caenorhabditis elegans cultured on 2 different media.

Science.gov (United States)

Tee, Ling Fei; Neoh, Hui-Min; Then, Sue Mian; Murad, Nor Azian; Asillam, Mohd Fairos; Hashim, Mohd Helmy; Nathan, Sheila; Jamal, Rahman

2017-11-01

Studies of multigenerational Caenorhabditis elegans exposed to long-term spaceflight have revealed expression changes of genes involved in longevity, DNA repair, and locomotion. However, results from spaceflight experiments are difficult to reproduce as space missions are costly and opportunities are rather limited for researchers. In addition, multigenerational cultures of C. elegans used in previous studies contribute to mixture of gene expression profiles from both larvae and adult worms, which were recently reported to be different. Usage of different culture media during microgravity simulation experiments might also give rise to differences in the gene expression and biological phenotypes of the worms. In this study, we investigated the effects of simulated microgravity on the gene expression and biological phenotype profiles of a single generation of C. elegans worms cultured on 2 different culture media. A desktop Random Positioning Machine (RPM) was used to simulate microgravity on the worms for approximately 52 to 54 h. Gene expression profile was analysed using the Affymetrix GeneChip® C. elegans 1.0 ST Array. Only one gene (R01H2.2) was found to be downregulated in nematode growth medium (NGM)-cultured worms exposed to simulated microgravity. On the other hand, eight genes were differentially expressed for C. elegans Maintenance Medium (CeMM)-cultured worms in microgravity; six were upregulated, while two were downregulated. Five of the upregulated genes (C07E3.15, C34H3.21, C32D5.16, F35H8.9 and C34F11.17) encode non-coding RNAs. In terms of biological phenotype, we observed that microgravity-simulated worms experienced minimal changes in terms of lifespan, locomotion and reproductive capabilities in comparison with the ground controls. Taking it all together, simulated microgravity on a single generation of C. elegans did not confer major changes to their gene expression and biological phenotype. Nevertheless, exposure of the worms to microgravity

Soft drop jet mass measurement

CERN Document Server

Roloff, Jennifer Kathryn; The ATLAS collaboration

2018-01-01

Calculations of jet substructure observables that are accurate beyond leading-logarithm accuracy have recently become available. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This poster documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross-section is measured as a function of log( ρ^2), where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 ifb of sqrt(s) = 13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Levitation of a drop over a film flow

Science.gov (United States)

Sreenivas, K. R.; de, P. K.; Arakeri, Jaywant H.

1999-02-01

A vertical jet of water impinging on a horizontal surface produces a radial film flow followed by a circular hydraulic jump. We report a phenomenon where fairly large (1 ml) drops of liquid levitate just upstream of the jump on a thin air layer between the drop and the film flow. We explain the phenomenon using lubrication theory. Bearing action both in the air film and the water film seems to be necessary to support large drops. Horizontal support is given to the drop by the hydraulic jump. A variety of drop shapes is observed depending on the volume of the drop and liquid properties. We show that interaction of the forces due to gravity, surface tension, viscosity and inertia produces these various shapes.

Three-dimensional culture of buffalo granulosa cells in hanging drop mimics the preovulatory follicle stage.

Science.gov (United States)

Yadav, Monica; Agrawal, Himanshu; Pandey, Mamta; Singh, Dheer; Onteru, Suneel K

2018-03-01

Granulosa cell (GC) culture models mimicking the intrafollicular environment are limited. Such models have a great potential in reproductive toxicity studies. The buffalo, a monovulatory species like humans, could be a better model than polyovulatory rodents. Therefore, we targeted the development and characterization of three-dimensional (3D) culture systems for buffalo GCs. The GCs from small ovarian follicles (SF) maintained the CYP19 gene expression for 144 hr in a 2D culture system. Hence, GCs from SF were cultured directly in 3D using hanging drop and Poly-([2-hydroxyethyl methacrylate]) (polyHEMA) methods in the DMEM media containing 1 ng/ml FSH and 10 ng/ml IGF-1 for 144 hr. The expression profile of nine GC-specific transcripts; CYP19, TNFAIP6, AMH, PTI, NR4A1, FSHR, RUNX, LHR, and COX2/PTGS2; revealed that 3D-spheroids developed in hanging drop method maintained the GC phenotype of preovulatory follicles. Therefore, hanging drop method is a best method for culturing GCs to mimic the intrafollicular environment. © 2017 Wiley Periodicals, Inc.

Drop Test Results of CRDM under Seismic Loads

International Nuclear Information System (INIS)

Choi, Myoung-Hwan; Cho, Yeong-Garp; Kim, Gyeong-Ho; Sun, Jong-Oh; Huh, Hyung

2016-01-01

This paper describes the test results to demonstrate the drop performance of CRDM under seismic loads. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the drop performance under seismic loads such as operating basis earthquake (OBE) and safe shutdown earthquake (SSE). Especially, the CAR drop times are important data for the safety analysis. confirm the drop performance under seismic loads. The delay of drop time at Rig no. 2 due to seismic loads is greater than that at Rig no. 3. The total pure drop times under seismic loads are estimated as 1.169 and 1.855, respectively

Drop Test Results of CRDM under Seismic Loads

Energy Technology Data Exchange (ETDEWEB)

Choi, Myoung-Hwan; Cho, Yeong-Garp; Kim, Gyeong-Ho; Sun, Jong-Oh; Huh, Hyung [KAERI, Daejeon (Korea, Republic of)

2016-05-15

This paper describes the test results to demonstrate the drop performance of CRDM under seismic loads. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the drop performance under seismic loads such as operating basis earthquake (OBE) and safe shutdown earthquake (SSE). Especially, the CAR drop times are important data for the safety analysis. confirm the drop performance under seismic loads. The delay of drop time at Rig no. 2 due to seismic loads is greater than that at Rig no. 3. The total pure drop times under seismic loads are estimated as 1.169 and 1.855, respectively.

Impact of granular drops

KAUST Repository

Marston, J. O.

2013-07-15

We investigate the spreading and splashing of granular drops during impact with a solid target. The granular drops are formed from roughly spherical balls of sand mixed with water, which is used as a binder to hold the ball together during free-fall. We measure the instantaneous spread diameter for different impact speeds and find that the normalized spread diameter d/D grows as (tV/D)1/2. The speeds of the grains ejected during the “splash” are measured and they rarely exceed twice that of the impact speed.

Impact of granular drops

KAUST Repository

Marston, J. O.; Mansoor, Mohammad M.; Thoroddsen, Sigurdur T

2013-01-01

We investigate the spreading and splashing of granular drops during impact with a solid target. The granular drops are formed from roughly spherical balls of sand mixed with water, which is used as a binder to hold the ball together during free-fall. We measure the instantaneous spread diameter for different impact speeds and find that the normalized spread diameter d/D grows as (tV/D)1/2. The speeds of the grains ejected during the “splash” are measured and they rarely exceed twice that of the impact speed.

Ring-Sheared Drop (RSD): Microgravity Module for Containerless Flow Studies

Science.gov (United States)

Gulati, Shreyash; Raghunandan, Aditya; Rasheed, Fayaz; McBride, Samantha A.; Hirsa, Amir H.

2017-02-01

Microgravity is potentially a powerful tool for investigating processes that are sensitive to the presence of solid walls, since fluid containment can be achieved by surface tension. One such process is the transformation of protein in solution into amyloid fibrils; these are protein aggregates associated with neurodegenerative diseases such as Alzheimer's and Parkinson's. In addition to solid walls, experiments with gravity are also subject to influences from sedimentation of aggregates and buoyancy-driven convection. The ring-sheared drop (RSD) module is a flow apparatus currently under development to study formation of amyloid fibrils aboard the International Space Station (ISS). A 25 mm diameter drop of protein solution will be contained by surface tension and constrained by a pair of sharp-edged tubes, forming two contact rings. Shear can be imparted by rotating one ring with the other ring kept stationary. Here we report on parabolic flights conducted to test the growth and pinning of 10 mm diameter drops of water in under 10 s of microgravity. Finite element method (FEM) based fluid dynamics computations using a commercial package (COMSOL) assisted in the design of the parabolic flight experiments. Prior to the parabolic flights, the code was validated against experiments in the lab (1 g), on the growth of sessile and pendant droplets. The simulations show good agreement with the experiments. This modeling capability will enable the development of the RSD at the 25 mm scale for the ISS.

Dominant Drop mutants are gain-of-function alleles of the muscle segment homeobox gene (msh) whose overexpression leads to the arrest of eye development.

Science.gov (United States)

Mozer, B A

2001-05-15

Dominant Drop (Dr) mutations are nearly eyeless and have additional recessive phenotypes including lethality and patterning defects in eye and sensory bristles due to cis-regulatory lesions in the cell cycle regulator string (stg). Genetic analysis demonstrates that the dominant small eye phenotype is the result of separate gain-of-function mutations in the closely linked muscle segment homeobox (msh) gene, encoding a homeodomain transcription factor required for patterning of muscle and nervous system. Reversion of the Dr(Mio) allele was coincident with the generation of lethal loss-of-function mutations in msh in cis, suggesting that the dominant eye phenotype is the result of ectopic expression. Molecular genetic analysis revealed that two dominant Dr alleles contain lesions upstream of the msh transcription start site. In the Dr(Mio) mutant, a 3S18 retrotransposon insertion is the target of second-site mutations (P-element insertions or deletions) which suppress the dominant eye phenotype following reversion. The pattern of 3S18 expression and the absence of msh in eye imaginal discs suggest that transcriptional activation of the msh promoter accounts for ectopic expression. Dr dominant mutations arrest eye development by blocking the progression of the morphogenetic furrow leading to photoreceptor cell loss via apoptosis. Gal4-mediated ubiquitous expression of msh in third-instar larvae was sufficient to arrest the morphogenetic furrow in the eye imaginal disc and resulted in lethality prior to eclosion. Dominant mutations in the human msx2 gene, one of the vertebrate homologs of msh, are associated with craniosynostosis, a disease affecting cranial development. The Dr mutations are the first example of gain-of-function mutations in the msh/msx gene family identified in a genetically tractible model organism and may serve as a useful tool to identify additional genes that regulate this class of homeodomain proteins. Copyright 2001 Academic Press.

CFD analysis of pressure drop across grid spacers in rod bundles compared to correlations and heavy liquid metal experimental data

Energy Technology Data Exchange (ETDEWEB)

Batta, A., E-mail: batta@kit.edu; Class, A.G., E-mail: class@kit.edu

2017-02-15

Early studies of the flow in rod bundles with spacer grids suggest that the pressure drop can be decomposed in contributions due to flow area variations by spacer grids and frictional losses along the rods. For these shape and frictional losses simple correlations based on theoretical and experimental data have been proposed. In the OECD benchmark study LACANES it was observed that correlations could well describe the flow behavior of the heavy liquid metal loop including a rod bundle with the exception of the core region, where different experts chose different pressure-loss correlations for the losses due to spacer grids. Here, RANS–CFD simulations provided very good data compared to the experimental data. It was observed that the most commonly applied Rehme correlation underestimated the shape losses. The available correlations relate the pressure drop across a grid spacer to the relative plugging of the spacer i.e. solidity e{sub max}. More sophisticated correlations distinct between spacer grids with round or sharp leading edge shape. The purpose of this study is to (i) show that CFD is suitable to predict pressure drop across spacer grids and (ii) to access the generality of pressure drop correlations. By verification and validation of CFD results against experimental data obtained in KALLA we show (i). The generality (ii) is challenged by considering three cases which yield identical pressure drop in the correlations. First we test the effect of surface roughness, a parameter not present in the correlations. Here we compare a simulation assuming a typical surface roughness representing the experimental situation to a perfectly smooth spacer surface. Second we reverse the flow direction for the spacer grid employed in the experiments which is asymmetric. The flow direction reversal is chosen for convenience, since an asymmetric spacer grid with given blockage ratio, may result in different flow situations depending on flow direction. Obviously blockage

Transcriptional profiling of protein expression related genes of Pichia pastoris under simulated microgravity.

Directory of Open Access Journals (Sweden)

Feng Qi

Full Text Available The physiological responses and transcription profiling of Pichia pastoris GS115 to simulated microgravity (SMG were substantially changed compared with normal gravity (NG control. We previously reported that the recombinant P. pastoris grew faster under SMG than NG during methanol induction phase and the efficiencies of recombinant enzyme production and secretion were enhanced under SMG, which was considered as the consequence of changed transcriptional levels of some key genes. In this work, transcriptiome profiling of P. pastoris cultured under SMG and NG conditions at exponential and stationary phases were determined using next-generation sequencing (NGS technologies. Four categories of 141 genes function as methanol utilization, protein chaperone, RNA polymerase and protein transportation or secretion classified according to Gene Ontology (GO were chosen to be analyzed on the basis of NGS results. And 80 significantly changed genes were weighted and estimated by Cluster 3.0. It was found that most genes of methanol metabolism (85% of 20 genes and protein transportation or secretion (82.2% of 45 genes were significantly up-regulated under SMG. Furthermore the quantity and fold change of up-regulated genes in exponential phase of each category were higher than those of stationary phase. The results indicate that the up-regulated genes of methanol metabolism and protein transportation or secretion mainly contribute to enhanced production and secretion of the recombinant protein under SMG.

Thyrotoxicosis Presenting as Unilateral Drop Foot.

Science.gov (United States)

Hara, Kenju; Miyata, Hajime; Motegi, Takahide; Shibano, Ken; Ishiguro, Hideaki

2017-01-01

Neuromuscular disorders associated with hyperthyroidism have several variations in their clinical phenotype, such as ophthalmopathy, periodic paralysis, and thyrotoxic myopathy. We herein report an unusual case of thyrotoxic myopathy presenting as unilateral drop foot. Histopathological examinations of the left tibialis anterior muscle showed marked variation in the fiber size, mild inflammatory cell infiltration, and necrotic and regenerated muscle fibers with predominantly type 1 fiber atrophy. Medical treatment with propylthiouracil resulted in complete improvement of the left drop foot. This case expands the phenotype of thyrotoxicosis and suggests that thyrotoxicosis be considered as a possible cause of unilateral drop foot.

Transient erythromycin resistance phenotype associated with peptidyl-tRNA drop-off on early UGG and GGG codons

DEFF Research Database (Denmark)

Macvanin, Mirjana; Gonzalez de Valdivia, Ernesto I; Ardell, David H

2007-01-01

-peptide-encoding sequence, we asked whether the codons UGG and GGG, which are known to promote peptidyl-tRNA drop-off at early positions in mRNA, would result in a phenotype of erythromycin resistance if located after this sequence. We find that UGG or GGG, at either position +4 or +5, without a following stop codon......, is associated with an erythromycin resistance phenotype upon gene induction. Our results suggest that, while a stop codon at +4 gives a tripeptide product (MIL) and erythromycin sensitivity, UGG or GGG codons at the same position give a tetrapeptide product (MILW or MILG) and phenotype of erythromycin...... resistance. Thus, the drop-off event on GGG or UGG codons occurs after incorporation of the corresponding amino acid into the growing peptide chain. Drop-off gives rise to a peptidyl-tRNA where the peptide moiety functionally mimics a minigene peptide product of the type previously associated...

Bubble and Drop Nonlinear Dynamics (BDND)

Science.gov (United States)

Trinh, E. H.; Leal, L. Gary; Thomas, D. A.; Crouch, R. K.

1998-01-01

Free drops and bubbles are weakly nonlinear mechanical systems that are relatively simple to characterize experimentally in 1-G as well as in microgravity. The understanding of the details of their motion contributes to the fundamental study of nonlinear phenomena and to the measurement of the thermophysical properties of freely levitated melts. The goal of this Glovebox-based experimental investigation is the low-gravity assessment of the capabilities of a modular apparatus based on ultrasonic resonators and on the pseudo- extinction optical method. The required experimental task is the accurate measurements of the large-amplitude dynamics of free drops and bubbles in the absence of large biasing influences such as gravity and levitation fields. A single-axis levitator used for the positioning of drops in air, and an ultrasonic water-filled resonator for the trapping of air bubbles have been evaluated in low-gravity and in 1-G. The basic feasibility of drop positioning and shape oscillations measurements has been verified by using a laptop-interfaced automated data acquisition and the optical extinction technique. The major purpose of the investigation was to identify the salient technical issues associated with the development of a full-scale Microgravity experiment on single drop and bubble dynamics.

Drop Testing Representative Multi-Canister Overpacks

Energy Technology Data Exchange (ETDEWEB)

Snow, Spencer D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Morton, Dana K. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-06-01

The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10^-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10^-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

Spent Nuclear Fuel (SNF) Bounding Drop Support Calculations

International Nuclear Information System (INIS)

CHENAULT, D.M.

1999-01-01

This report evaluates different drop heights, concrete and other impact media to which the transport package and/or the MCO is dropped. A prediction method is derived for estimating the resultant impact factor for determining the bounding drop case for the SNF Project

Wetting and evaporation of binary mixture drops.

Science.gov (United States)

Sefiane, Khellil; David, Samuel; Shanahan, Martin E R

2008-09-11

Experimental results on the wetting behavior of water, methanol, and binary mixture sessile drops on a smooth, polymer-coated substrate are reported. The wetting behavior of evaporating water/methanol drops was also studied in a water-saturated environment. Drop parameters (contact angle, shape, and volume) were monitored in time. The effects of the initial relative concentrations on subsequent evaporation and wetting dynamics were investigated. Physical mechanisms responsible for the various types of wetting behavior during different stages are proposed and discussed. Competition between evaporation and hydrodynamic flow are evoked. Using an environment saturated with water vapor allowed further exploration of the controlling mechanisms and underlying processes. Wetting stages attributed to differential evaporation of methanol were identified. Methanol, the more volatile component, evaporates predominantly in the initial stage. The data, however, suggest that a small proportion of methanol remained in the drop after the first stage of evaporation. This residual methanol within the drop seems to influence subsequent wetting behavior strongly.

Chemoembolization Decreases Drop-Off Risk of Hepatocellular Carcinoma Patients on the Liver Transplant List

International Nuclear Information System (INIS)

Frangakis, Constantine; Geschwind, Jean-Francois; Kim, Daniel; Chen, Yong; Koteish, Ayman; Hong, Kelvin; Liapi, Eleni; Georgiades, Christos S.

2011-01-01

Introduction: The drop-off risk for patients awaiting liver transplantation for hepatocellular carcinoma (HCC) is 22%. Transplant liver availability is expected to worsen, resulting in longer waiting times and increased drop-off rates. Our aim was to determine whether chemoembolization can decrease this risk. Patients and Methods: Eighty-seven consecutive HCC patients listed for liver transplant (Milan criteria) underwent statistical comparability adjustments using the propensity score (Wilcoxon, Fisher’s, and chi-square tests). Forty-three nonchemoembolization patients and 22 chemoembolization patients were comparable for Child-Pugh and Model for End-Stage Liver Disease scores, tumor size and number, alpha fetoprotein (AFP) levels, and cause of cirrhosis. We calculated the risk of dropping off the transplant list by assigning a transplant time to those who dropped off (equal probability with patients who were on the list longer than the patient in question). The significance level was obtained by calculating the simulation distribution of the difference compared with the permutations of chemoembolization versus nonchemoembolization assignment of the patients. Kaplan–Meier estimators (log-rank test) were used to determine survival rates. Results: Median follow-up was 187 ± 110 weeks (range 38 to 435, date of diagnosis). The chemoembolization group had an 80% drop-off risk decrease (15% nonchemoembolization versus 3% chemoembolization, p = 0.04). Although survival was better for the chemoembolization group, it did not reach statistical significance. Two-year survival for the nonchemoembolization and chemoembolization group was 57.3% ± 7.1% and 76.0% ± 7.9%, respectively (p = 0.078). Conclusions: Chemoembolization appears to result in a significant decrease in the risk of dropping off liver transplant list for patients with HCC and results in a tendency toward longer survival.

Drop-out from a psychodynamic group psychotherapy outpatient unit.

Science.gov (United States)

Jensen, Hans Henrik; Mortensen, Erik Lykke; Lotz, Martin

2014-11-01

BACKGROUND. Drop-out from psychotherapy is common and represents a considerable problem in clinical practice and research. Aim. To explore pre-treatment predictors of early and late drop-out from psychodynamic group therapy in a public outpatient unit for non-psychotic disorders in Denmark. Methods. Naturalistic design including 329 patients, the majority with mood, neurotic and personality disorders referred to 39-session group therapy. Predictors were socio-demographic and clinical variables, self-reported symptoms (Symptom Check List-90-Revised) and personality style (Millon Clinical Multiaxial Inventory-II). Drop-out was classified into early and late premature termination excluding patients who dropped out for external reasons. Results. Drop-out comprised 20.6% (68 patients) of the sample. Logistic regression revealed social functioning, vocational training, alcohol problems and antisocial behavior to be related to drop-out. However, early drop-outs had prominent agoraphobic symptoms, lower interpersonal sensitivity and compulsive personality features, and late drop-outs cognitive and somatic anxiety symptoms and antisocial personality features. Clinical and psychological variables accounted for the major part of variance in predictions of drop-out, which ranged from 15.6% to 19.5% (Nagelkerke Pseudo R-Square). Conclusion. Social functioning was consistently associated with drop-out, but personality characteristics and anxiety symptoms differentiated between early and late drop-out. Failure to discriminate between stages of premature termination may explain some of the inconsistencies in the drop-out literature. Clinical implications. Before selection of patients to time-limited psychodynamic groups, self-reported symptoms should be thoroughly considered. Patients with agoraphobic symptoms should be offered alternative treatment. Awareness of and motivation to work with interpersonal issues may be essential for compliance with group therapy.

Reducing Variability in Stress Drop with Root-Mean Acceleration

Science.gov (United States)

Crempien, J.; Archuleta, R. J.

2012-12-01

Stress drop is a fundamental property of the earthquake source. For a given tectonic region stress drop is assumed to be constant allowing for the scaling of earthquake spectra. However, the variability of the stress drop, either for worldwide catalogs or regional catalogs, is quite large. The variability around the median value is on the order of 1.5 in log10 units. One question that continues to pervade the analysis of stress drop is whether this variability is an inherent characteristic of the Earth or is an artifact of the determination of stress drop via the use of the spectral analysis. It is simple to see that the stress drop determined by seismic moment times corner frequency cubed that errors in the corner frequency will strongly influence the variability in the stress drop. To avoid this strong dependence on corner frequency cubed, we have examined the determination of stress drop based on the approach proposed by Hanks (1979), namely using the root-mean-square acceleration. The stress drop determined using rms acceleration may be advantageous because the stress drop is only affected by the square root of the corner frequency. To test this approach we have determined stress drops for the 2000 Tottori earthquake and its aftershocks. We use both the classic method of fitting to a spectrum as well as using rms acceleration. For a preliminary analysis of eight aftershocks and the mainshock we find that the variability in stress drop is reduced by about a factor of two. This approach needs more careful analysis of more events, which will be shown at the meeting.

Why Do Students Drop Advanced Mathematics?

Science.gov (United States)

Horn, Ilana

2004-01-01

Students, especially black, Latino and Native American youth and students of low socio-economic status drop out of advanced mathematics. Teachers must coordinate their expectations, their knowledge of students and their teaching practices in order to stop struggling students from dropping out of advanced math classes.

Delayed frost growth on jumping-drop superhydrophobic surfaces.

Science.gov (United States)

Boreyko, Jonathan B; Collier, C Patrick

2013-02-26

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation.

Hanging drop crystal growth apparatus and method

Science.gov (United States)

Carter, Daniel C. (Inventor); Smith, Robbie E. (Inventor)

1989-01-01

An apparatus (10) is constructed having a cylindrical enclosure (16) within which a disc-shaped wicking element (18) is positioned. A well or recess (22) is cut into an upper side (24) of this wicking element, and a glass cover plate or slip (28) having a protein drop disposed thereon is sealably positioned on the wicking element (18), with drop (12) being positioned over well or recess (22). A flow of control fluid is generated by a programmable gradient former (16), with this control fluid having a vapor pressure that is selectively variable. This flow of control fluid is coupled to the wicking element (18) where control fluid vapor diffusing from walls (26) of the recess (22) is exposed to the drop (12), forming a vapor pressure gradient between the drop (12) and the control fluid vapor. Initially, this gradient is adjusted to draw solvent from the drop (12) at a relatively high rate, and as the critical supersaturation point is approached (the point at which crystal nucleation occurs), the gradient is reduced to more slowly draw solvent from the drop (12). This allows discrete protein molecules more time to orient themselves into an ordered crystalline lattice, producing protein crystals which, when processed by X-ray crystallography, possess a high degree of resolution.

Free drop impact analysis of shipping cask

International Nuclear Information System (INIS)

Pfeiffer, P.A.; Kennedy, J.M.

1989-01-01

The WHAMS-2D and WHAMS-3D codes were used to analyze the dynamic response of the RAS/TREAT shielded shipping cask subjected to transient leadings for the purpose of assessing potential damage to the various components that comprise the the cask. The paper describes how these codes can be used to provide and intermediate level of detail between full three-dimensional finite element calculations and hand calculations which are cost effective for design purposes. Three free drops were adressed: (1) a thirty foot axial drop on either end; (2) a thirty foot oblique angle drop with the cask having several different orientations from the vertical with impact on the cask corner; and (3) a thirty foot side drop with simultaneous impact on the lifting trunnion and the bottom end. Results are presented for two models of the side and oblique angle drops; one model includes only the mass of the lapped sleeves of depleted uranium (DU) while the other includes the mass and stiffness of the DU. The results of the end drop analyses are given for models with and without imperfections in the cask. Comparison of the analysis to hand calculations and simplified analyses are given. (orig.)

Electrowetting-on-dielectrics for manipulation of oil drops and gas bubbles in aqueous-shell compound drops.

Science.gov (United States)

Li, Jiang; Wang, Yixuan; Chen, Haosheng; Wan, Jiandi

2014-11-21

We present the manipulation of oil, organic and gaseous chemicals by electrowetting-on-dielectric (EWOD) technology using aqueous-shell compound drops. We demonstrate that the transport and coalescence of viscous oil drops, the reaction of bromine with styrene in benzene solution, and the reaction of red blood cells with carbon monoxide bubbles can be accomplished using this method.

A new role for reduction in pressure drop in cyclones using computational fluid dynamics techniques

Directory of Open Access Journals (Sweden)

D. Noriler

2004-01-01

Full Text Available In this work a new mechanical device to improve the gas flow in cyclones by pressure drop reduction is presented and discussed. This behavior occurs due to the effects of introducing swirling breakdown phenomenon at the inlet of the vortex finder tube. The device consists of a tube with two gas inlets in an appositive spiral flux that produces a sudden reduction in the tangential velocity peak responsible for practically 80 % of the pressure drop in cyclones. In turn, peak reduction causes a decrease in pressure drop by a breakdown of the swirling, and because of this the solid particles tend to move faster toward the wall , increasing collection efficiency. As a result of this phenomenon the overall performance of cyclones is improved. Numerical simulations with 3-D, transient, asymmetric and anisotropic turbulence closure by differential Reynolds stress for Lapple and Stairmand standard geometries of 0.3 m in diameter, show a reduction in pressure drop of 20 % and a shift of the tangential velocity peak toward the wall. All numerical experiments were carried out with a commercial CFD code showing numerical stability and good convergence rates with high-order interpolation schemes, SIMPLEC pressure-velocity coupling and other numerical features.

Studying the field induced breakup of acoustically levitated drops

Science.gov (United States)

Warschat, C.; Riedel, J.

2017-10-01

Coulomb fission of charged droplets (The terms drop and droplet are often used synonymous. Throughout this manuscript, to avoid confusion, the terms drop and droplet will be used for liquid spheres with radii in the millimeter range and the micrometer range, respectively. In our experiments, the first correspond to the parent drop while the latter describes the ejected progeny droplets.) is a well-studied natural phenomenon. Controlled droplet fission is already successfully employed in several technological applications. Still, since the occurring surface rupture relies on the exact understanding and description of the liquid gas boundary, some details are still under debate. Most empirical systematic studies observe falling micrometer droplets passing through the electric field inside a plate capacitor. This approach, although easily applicable and reliable, limits the experimental degrees of freedom regarding the observable time and the maximum size of the drops and can only be performed in consecutive individual observations of different subsequent drops. Here we present a novel setup to study the field induced breakup of acoustically levitated drops. The design does not bear any restrictions towards the temporal window of observation, and allows handling of drops of a tunable radius ranging from 10 μm to several millimeters and a real-time monitoring of one single drop. Our comprehensive study includes a time resolved visual inspection, laser shadowgraphy, laser induced fluorescence imaging, and ambient mass spectrometric interrogation of the nascent Taylor cone. The results shown for a millimeter sized drop, previously inaccessible for Coulomb fission experiments, are mostly comparable with previous results for smaller drops. The major difference is the time scale and the threshold potential of the drop rupture. Both values, however, resemble theoretically extrapolations to the larger radius. The technique allows for a systematic study of breakup behavior of

Motion of a drop driven by substrate vibrations

Science.gov (United States)

Brunet, P.; Eggers, J.; Deegan, R. D.

2009-01-01

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wet by the drop. Frequency of vibrations ranges from 30 to 200 Hz, and above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up/down symmetry-breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements.

The new Drop Tower catapult system

Science.gov (United States)

von Kampen, Peter; Kaczmarczik, Ulrich; Rath, Hans J.

2006-07-01

The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of the "Drop Tower" began. Since then, the eye-catching tower with a height of 146 m and its characteristic glass roof has become the emblem of the technology centre in Bremen. The Drop Tower Bremen provides a facility for experiments under conditions of weightlessness. Items are considered weightless, when they are in "free fall", i.e. moving without propulsion within the gravity field of the earth. The height of the tower limits the simple "free fall" experiment period to max. 4.74 s. With the inauguration of the catapult system in December 2004, the ZARM is entering a new dimension. This world novelty will meet scientists' demands of extending the experiment period up to 9.5 s. Since turning the first sod on May 3rd, 1988, the later installation of the catapult system has been taken into account by building the necessary chamber under the tower. The catapult system is located in a chamber 10 m below the base of the tower. This chamber is almost completely occupied by 12 huge pressure tanks. These tanks are placed around the elongation of the vacuum chamber of the drop tube. In its centre there is the pneumatic piston that accelerates the drop capsule by the pressure difference between the vacuum inside the drop tube and the pressure inside the tanks. The acceleration level is adjusted by means of a servo hydraulic breaking system controlling the piston velocity. After only a quarter of a second the drop capsule achieves its lift-off speed of 175 km/h. With this exact speed, the capsule will rise up to the top of the tower and afterwards fall down again into the deceleration unit which has been moved under the drop tube in the meantime. The scientific advantages of the doubled experiment time are obvious: during almost 10 s of high

Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

Directory of Open Access Journals (Sweden)

Li Yuting

2015-10-01

Full Text Available Potential drop techniques are of two types: the direct current potential drop (DCPD technique and alternating current potential drop (ACPD technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.

Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

Science.gov (United States)

Li, Yuting; Gan, Fangji; Wan, Zhengjun; Liao, Junbi; Li, Wenqiang

2015-10-01

Potential drop techniques are of two types: the direct current potential drop (DCPD) technique and alternating current potential drop (ACPD) technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.

Theory of magnetostriction of electron-hole drops in Ge

International Nuclear Information System (INIS)

Markiewicz, R.S.

1978-01-01

A large mass of electron-hole liquid (γ drop) formed in a strain-induced potential well in Ge is known to distort its shape significantly in a magnetic field B > or approx. = 1 kG. It is shown in this paper that the shape change can be understood in detail as due to a ''recombination current'' of electron-hole pairs needed to replace those pairs which recombine in the drop volume. The Lorentz force deflects this current and produces a macroscopic dipole current loop inside the drop. The drop then changes shape to minimize its total energy, including magnetic, strain, and surface energies. While the drop usually flattens along the field direction, both para- and diamagnetic effects (elongated drops) are found to be possible, depending on excitation conditions, in accord with experiment. Similar effects are predicted to occur in small drops in unstrained Ge. This paper presents a magnetohydrodynamic theory of the magnetostriction which takes into account density variations which occur in the strain well and in high magnetic fields. A simpler theory is given for the special case in which the drop may be considered incompressible (small drops and moderate fields). Effects of carrier mass anisotropy and fluid viscosity are taken into consideration

Ground Motion Prediction Equations Empowered by Stress Drop Measurement

Science.gov (United States)

Miyake, H.; Oth, A.

2015-12-01

Significant variation of stress drop is a crucial issue for ground motion prediction equations and probabilistic seismic hazard assessment, since only a few ground motion prediction equations take into account stress drop. In addition to average and sigma studies of stress drop and ground motion prediction equations (e.g., Cotton et al., 2013; Baltay and Hanks, 2014), we explore 1-to-1 relationship for each earthquake between stress drop and between-event residual of a ground motion prediction equation. We used the stress drop dataset of Oth (2013) for Japanese crustal earthquakes ranging 0.1 to 100 MPa and K-NET/KiK-net ground motion dataset against for several ground motion prediction equations with volcanic front treatment. Between-event residuals for ground accelerations and velocities are generally coincident with stress drop, as investigated by seismic intensity measures of Oth et al. (2015). Moreover, we found faster attenuation of ground acceleration and velocities for large stress drop events for the similar fault distance range and focal depth. It may suggest an alternative parameterization of stress drop to control attenuation distance rate for ground motion prediction equations. We also investigate 1-to-1 relationship and sigma for regional/national-scale stress drop variation and current national-scale ground motion equations.

Pressure Drop of Chamfer on Spacer Grid Strap

Energy Technology Data Exchange (ETDEWEB)

Kim, Euijae; Kim, Kanghoon; Kim, Kyounghong; Nahm, Keeyil [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

2014-05-15

A swirl flow and cross flow are generated by the spacer grid with mixing vane that enhances the thermal performance and critical heat flux (CHF). The additional pressure drop makes it difficult to meet acceptance criteria for overall pressure drop in fuel assembly depending upon the pump capacity. The chamfer on the end of spacer grid strap is one solution to reduce additional pressure drop without any adverse effect on flow fields. In this research, the pressure drop tests for spacer grid with and without chamfer were carried out at the hydraulic test facility. The result can be applied to develop high performance nuclear fuel assemblies for Pressurized Water Reactor (PWR) plants. The pressure drop tests for 5x5 spacer grid with and without chamfer as well as 6x6 spacer grid with and without chamfer were carried out at the INFINIT test facility. The Reynolds number ranged about from 16000 to 75000. The sweep-up and sweep-down test showed that the direction of sweep did not affect the pressure drop. The chamfer on spacer grid strap reduced the pressure drop due to the decreased in ratio of inlet area to outlet area. The pressure loss coefficient for spacer grid with chamfer was by up to 13.8 % lower than that for spacer grid without chamfer. Hence, the chamfer on spacer grid strap was one of effective ways to reduce the pressure drop.

Drop impact entrapment of bubble rings

KAUST Repository

Thoraval, M.-J.

2013-04-29

We use ultra-high-speed video imaging to look at the initial contact of a drop impacting on a liquid layer. We observe experimentally the vortex street and the bubble-ring entrapments predicted numerically, for high impact velocities, by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, article 264506). These dynamics mainly occur within 50 -s after the first contact, requiring imaging at 1 million f.p.s. For a water drop impacting on a thin layer of water, the entrapment of isolated bubbles starts through azimuthal instability, which forms at low impact velocities, in the neck connecting the drop and pool. For Reynolds number Re above -12 000, up to 10 partial bubble rings have been observed at the base of the ejecta, starting when the contact is -20% of the drop size. More regular bubble rings are observed for a pool of ethanol or methanol. The video imaging shows rotation around some of these air cylinders, which can temporarily delay their breakup into micro-bubbles. The different refractive index in the pool liquid reveals the destabilization of the vortices and the formation of streamwise vortices and intricate vortex tangles. Fine-scale axisymmetry is thereby destroyed. We show also that the shape of the drop has a strong influence on these dynamics. 2013 Cambridge University Press.

Marangoni Flow Induced Evaporation Enhancement on Binary Sessile Drops.

Science.gov (United States)

Chen, Pin; Harmand, Souad; Ouenzerfi, Safouene; Schiffler, Jesse

2017-06-15

The evaporation processes of pure water, pure 1-butanol, and 5% 1-butanol aqueous solution drops on heated hydrophobic substrates are investigated to determine the effect of temperature on the drop evaporation behavior. The evolution of the parameters (contact angle, diameter, and volume) during evaporation measured using a drop shape analyzer and the infrared thermal mapping of the drop surface recorded by an infrared camera were used in investigating the evaporation process. The pure 1-butanol drop does not show any thermal instability at different substrate temperatures, while the convection cells created by the thermal Marangoni effect appear on the surface of the pure water drop from 50 °C. Because 1-butanol and water have different surface tensions, the infrared video of the 5% 1-butanol aqueous solution drop shows that the convection cells are generated by the solutal Marangoni effect at any substrate temperature. Furthermore, when the substrate temperature exceeds 50 °C, coexistence of the thermal and solutal Marangoni flows is observed. By analyzing the relation between the ratio of the evaporation rate of pure water and 1-butanol aqueous solution drops and the Marangoni number, a series of empirical equations for predicting the evaporation rates of pure water and 1-butanol aqueous solution drops at the initial time as well as the equations for the evaporation rate of 1-butanol aqueous solution drop before the depletion of alcohol are derived. The results of these equations correspond fairly well to the experimental data.

Drop-out rate and drop-out reasons among promising Norwegian track and field athletes: a 25 year study

OpenAIRE

Enoksen, Eystein

2011-01-01

© Eystein Enoksen, 2011 The aim of the present study was to identify the total drop-out rate and drop-out reasons for a group of promising track and field athletes. 202 males and 98 females, aged 16 ±2 years, took part in this study. Questionnaires were administrated in 1975, 1983, and 1989. In-depth interviews were conducted in 1989 and in 2000. A chi-square test was administrated to test the difference between males and females dropping out and to test the most significant reasons influe...

Creeping motion of long bubbles and drops in capillary tubes

DEFF Research Database (Denmark)

Westborg, Henrik; Hassager, Ole

1989-01-01

The flow of inviscid bubbles and viscous drops in capillary tubes has been simulated by a Galerkin finite element method with surface tension included at the bubble/liquid interface. The results show good agreement with published experimental results. At low capillary numbers the front and the rear...... of the bubble are nearly spherical. As the capillary number increases the thickness of the wetting film between the tube wall and the bubble increases, and the bubble assumes a more slender shape with a characteristic bump at the rear. Recirculations are found in front and behind the bubble, which disappear...

Numerical investigation of the deformation mechanism of a bubble or a drop rising or falling in another fluid

International Nuclear Information System (INIS)

Wang Han; Yang Yongming; Hu Yüe; Zhang Huisheng; Zhang Zhenyu

2008-01-01

A numerical method for simulating the motion and deformation of an axisymmetric bubble or drop rising or falling in another infinite and initially stationary fluid is developed based on the volume of fluid (VOF) method in the frame of two incompressible and immiscible viscous fluids under the action of gravity, taking into consideration of surface tension effects. A comparison of the numerical results by this method with those by other works indicates the validity of the method. In the frame of inviscid and incompressible fluids without taking into consideration of surface tension effects, the mechanisms of the generation of the liquid jet and the transition from spherical shape to toroidal shape during the bubble or drop deformation, the increase of the ring diameter of the toroidal bubble or drop and the decrease of its cross-section area during its motion, and the effects of the density ratio of the two fluids on the deformation of the bubble or drop are analysed both theoretically and numerically. (condensed matter: structure, thermal and mechanical properties)

University Drop-Out: An Italian Experience

Science.gov (United States)

Belloc, Filippo; Maruotti, Antonello; Petrella, Lea

2010-01-01

University students' drop-out is a crucial issue for the universities' efficiency evaluation and funding. In this paper, we analyze the drop-out rate of the Economics and Business faculty of Sapienza University of Rome. We use administrative data on 9,725 undergraduates students enrolled in three-years bachelor programs from 2001 to 2007 and…

Acoustic forcing of a liquid drop

Science.gov (United States)

Lyell, M. J.

1992-01-01

The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

Experimental study of drop breakup in a turbulent flow; Etude experimentale de la rupture de gouttes dans un ecoulement turbulent

Energy Technology Data Exchange (ETDEWEB)

Galinat, S.

2005-04-15

This work presents the drop breakup phenomenon in a turbulent flow induced by a cross-section restriction in a pipe. A global analysis of single-drop breakup, in a finite volume downstream of the orifice, has allowed deriving statistical quantities such as the break-up probability and the daughter-drop distribution. These parameters are function of a global Weber number based on the maximal pressure drop through the orifice. At a local scale, the locations of breakup events are distributed heterogeneously and depend on the flow Reynolds number. The local hydrodynamic study in downstream of the orifice, which has been done by using Particle Image Velocimetry, reveals the specific breakup zones. Otherwise, this analysis has proved that the turbulence is the predominant external stress at the drop scale. The relation between drop deformation and the external stress along the trajectory has been simulated numerically by the response of a damped oscillator to the locally measured instantaneous turbulence forcing. The results of statistical analysis have allowed to introduce a breakup criterion, based on a unique deformation threshold value for all experiments. This multi-scale approach has been conducted to study drop breakup mechanisms in a concentrated dispersion. The breakup probability decrease with the increase of dispersed phase concentration, which influences the turbulent Weber number distribution in downstream of the orifice. (author)

The origin of star-shaped oscillations of Leidenfrost drops

Science.gov (United States)

Ma, Xiaolei; Burton, Justin C.

We experimentally investigate the oscillations of Leidenfrost drops of water, liquid nitrogen, ethanol, methanol, acetone and isopropyl alcohol. The drops levitate on a cushion of evaporated vapor over a hot, curved surface which keeps the drops stationary. We observe star-shaped modes along the periphery of the drop, with mode numbers n = 2 to 13. The number of observed modes is sensitive to the properties of the liquid. The pressure oscillation frequency in the vapor layer under the drop is approximately twice that of the drop frequency, which is consistent with a parametric forcing mechanism. However, the Rayleigh and thermal Marangoni numbers are of order 10,000, indicating that convection should play a dominating role as well. Surprisingly, we find that the wavelength and frequency of the oscillations only depend on the thickness of the liquid, which is twice the capillary length, and do not depend on the mode number, substrate temperature, or the substrate curvature. This robust behavior suggests that the wavelength for the oscillations is set by thermal convection inside the drop, and is less dependent on the flow in the vapor layer under the drop

Redifferentiation of in vitro expanded adult articular chondrocytes by combining the hanging-drop cultivation method with hypoxic environment.

Science.gov (United States)

Martinez, Inigo; Elvenes, Jan; Olsen, Randi; Bertheussen, Kjell; Johansen, Oddmund

2008-01-01

The main purpose of this work has been to establish a new culturing technique to improve the chondrogenic commitment of isolated adult human chondrocytes, with the aim of being used during cell-based therapies or tissue engineering strategies. By using a rather novel technique to generate scaffold-free three-dimensional (3D) structures from in vitro expanded chondrocytes, we have explored the effects of different culture environments on cartilage formation. Three-dimensional chondrospheroids were developed by applying the hanging-drop technique. Cartilage tissue formation was attempted after combining critical factors such as serum-containing or serum-free media and atmospheric (20%) or low (2.5%) oxygen tensions. The quality of the formed microtissues was analyzed by histology, immunohistochemistry, electron microscopy, and real-time PCR, and directly compared with native adult cartilage. Our results revealed highly organized, 3D tissue-like structures developed by the hanging-drop method. All culture conditions allowed formation of 3D spheroids; however, cartilage generated under low oxygen tension had a bigger size, enhanced matrix deposition, and higher quality of cartilage formation. Real-time PCR demonstrated enhanced expression of cartilage-specific genes such us collagen type II and aggrecan in 3D cultures when compared to monolayers. Cartilage-specific matrix proteins and genes expressed in hanging-drop-developed spheroids were comparable to the expression obtained by applying the pellet culture system. In summary, our results indicate that a combination of 3D cultures of chondrocytes in hanging drops and a low oxygen environment represent an easy and convenient way to generate cartilage-like microstructures. We also show that a new specially tailored serum-free medium is suitable for in vitro cartilage tissue formation. This new methodology opens up the possibility of using autogenously produced solid 3D structures with redifferentiated chondrocytes as an

Propelling a water drop with the vapor-mediated Marangoni effect

Science.gov (United States)

Kim, Seungho; Kim, Ho-Young

2013-11-01

We show that a water drop on solid surfaces can be propelled just by placing a volatile alcohol drop nearby. It is found to be because the water-air interface near the alcohol drop mixes with alcohol vapor, thereby locally lowering the surface tension. The surface-tension-gradient induces the motion of the water drop, enabling the trajectory control of water drops through the motion of remote alcohol drops. This vapor-mediated Marangoni effect also gives rise to other interesting interfacial flow phenomena, such as nucleation of holes on a water film and ballooning of a water drop hanging from a syringe needle with the approach of an alcohol drop. We visualize such interfacial dynamics with a high-speed camera and rationalize their salient features by scaling analysis. This work was supported by the National Research Foundation of Korea (grant no. 2012-008023).

Allelic drop-out probabilities estimated by logistic regression

DEFF Research Database (Denmark)

Tvedebrink, Torben; Eriksen, Poul Svante; Asplund, Maria

2012-01-01

We discuss the model for estimating drop-out probabilities presented by Tvedebrink et al. [7] and the concerns, that have been raised. The criticism of the model has demonstrated that the model is not perfect. However, the model is very useful for advanced forensic genetic work, where allelic drop-out...... is occurring. With this discussion, we hope to improve the drop-out model, so that it can be used for practical forensic genetics and stimulate further discussions. We discuss how to estimate drop-out probabilities when using a varying number of PCR cycles and other experimental conditions....

Development of Drop/Shock Test in Microelectronics and Impact Dynamic Analysis for Uniform Board Response

Science.gov (United States)

Kallolimath, Sharan Chandrashekar

For the past several years, many researchers are constantly developing and improving board level drop test procedures and specifications to quantify the solder joint reliability performance of consumer electronics products. Predictive finite element analysis (FEA) by utilizing simulation software has become widely acceptable verification method which can reduce time and cost of the real-time test process. However, due to testing and metrological limitations it is difficult not only to simulate exact drop condition and capture critical measurement data but also tedious to calibrate the system to improve test methods. Moreover, some of the important ever changing factors such as board flexural rigidity, damping, drop height, and drop orientation results in non-uniform stress/strain distribution throughout the test board. In addition, one of the most challenging tasks is to quantify uniform stress and strain distribution throughout the test board and identify critical failure factors. The major contributions of this work are in the four aspects of the drop test in electronics as following. First of all, an analytical FEA model was developed to study the board natural frequencies and responses of the system with the consideration of dynamic stiffness, damping behavior of the material and effect of impact loading condition. An approach to find the key parameters that affect stress and strain distributions under predominate mode responses was proposed and verified with theoretical solutions. Input-G method was adopted to study board response behavior and cut boundary interpolation methods was used to analyze local model solder joint stresses with the development of global/local FEA model in ANSYS software. Second, no ring phenomenon during the drop test was identified theoretically when the test board was modeled as both discrete system and continuous system. Numerical analysis was then conducted by FEA method for detailed geometry of attached chips with solder

Control rod drop transient analysis with the coupled parallel code pCTF-PARCSv2.7

International Nuclear Information System (INIS)

Ramos, Enrique; Roman, Jose E.; Abarca, Agustín; Miró, Rafael; Bermejo, Juan A.

2016-01-01

Highlights: • An MPI parallel version of the thermal–hydraulic subchannel code COBRA-TF has been developed. • The parallel code has been coupled to the 3D neutron diffusion code PARCSv2.7. • The new codes are validated with a control rod drop transient. - Abstract: In order to reduce the response time when simulating large reactors in detail, a parallel version of the thermal–hydraulic subchannel code COBRA-TF (CTF) has been developed using the standard Message Passing Interface (MPI). The parallelization is oriented to reactor cells, so it is best suited for models consisting of many cells. The generation of the Jacobian matrix is parallelized, in such a way that each processor is in charge of generating the data associated with a subset of cells. Also, the solution of the linear system of equations is done in parallel, using the PETSc toolkit. With the goal of creating a powerful tool to simulate the reactor core behavior during asymmetrical transients, the 3D neutron diffusion code PARCSv2.7 (PARCS) has been coupled with the parallel version of CTF (pCTF) using the Parallel Virtual Machine (PVM) technology. In order to validate the correctness of the parallel coupled code, a control rod drop transient has been simulated comparing the results with the real experimental measures acquired during an NPP real test.

Fragmentation of molten metal drop with instantaneous contact temperature below the boiling point of Na

International Nuclear Information System (INIS)

Inukai, S.; Sugiyama, K.; Nishimura, S.; Kinoshita, I.

2001-01-01

The consequence of the core disruptive accidents in metallic-fueled Na-cooled reactors is strongly affected by the feedback reactivity originating in the boiling of Na and the dispersion of molten fuel due to fuel-coolant interactions. The design of the core configuration to promote the dispersion of molten fuel is therefore very important for social acceptance. It has been recognized in this context that metallic fuel has a potentiality to make liquefied fuel with fuel pin tube even in the temperature range below the boiling point of Na. If the liquefied fuel solidified without fuel-coolant interactions in the core region, this event leads the core condition to a pessimistic scenario of re-criticality. As a basic study related to this problem, the present experimental study investigates the possibility of fragmentation of metal drop with instantaneous contact temperature below the boiling point of Na (883 C). The molten Al drop, which has a melting point of 660 C above the operational temperature range of core, was selected as a simulant of liquefied fuel in the present study. Al particles of 5 g or 0.56 g were heated up to the initial temperature ranging from 850 C to 1113 C in a crucible by using an electric heater. The molten Al drop was dropped into a sodium pool adjusted the temperature from 280 C to 499 C. The Al drop at initial temperature sufficiently higher that the boiling point of Na was observed to fragment into pieces under the condition of instantaneous contact temperature below the boiling point of Na. It is confirmed that the fragmentation is caused due to the thermal interactions between the molten Al and the Na entrapped into the drop. (author)

Fragmentation of molten metal drop with instantaneous contact temperature below the boiling point of Na

Energy Technology Data Exchange (ETDEWEB)

Inukai, S.; Sugiyama, K. [Hokkaido Univ., Dept. of Nuclear Engineering, Sapporo (Japan); Nishimura, S.; Kinoshita, I. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

2001-07-01

The consequence of the core disruptive accidents in metallic-fueled Na-cooled reactors is strongly affected by the feedback reactivity originating in the boiling of Na and the dispersion of molten fuel due to fuel-coolant interactions. The design of the core configuration to promote the dispersion of molten fuel is therefore very important for social acceptance. It has been recognized in this context that metallic fuel has a potentiality to make liquefied fuel with fuel pin tube even in the temperature range below the boiling point of Na. If the liquefied fuel solidified without fuel-coolant interactions in the core region, this event leads the core condition to a pessimistic scenario of re-criticality. As a basic study related to this problem, the present experimental study investigates the possibility of fragmentation of metal drop with instantaneous contact temperature below the boiling point of Na (883 C). The molten Al drop, which has a melting point of 660 C above the operational temperature range of core, was selected as a simulant of liquefied fuel in the present study. Al particles of 5 g or 0.56 g were heated up to the initial temperature ranging from 850 C to 1113 C in a crucible by using an electric heater. The molten Al drop was dropped into a sodium pool adjusted the temperature from 280 C to 499 C. The Al drop at initial temperature sufficiently higher that the boiling point of Na was observed to fragment into pieces under the condition of instantaneous contact temperature below the boiling point of Na. It is confirmed that the fragmentation is caused due to the thermal interactions between the molten Al and the Na entrapped into the drop. (author)

Drop Weight Device Fabrication and Tests for a Dynamic Material Property of Shock-Absorbing Material and Structure in Transportation Package

International Nuclear Information System (INIS)

Choi, Woo Seok; Jeon, Jea Eon; Han, Sang Hyeok; Lee, Sang Hoon; Seo, Ki Seok

2009-01-01

A radioactive material transportation package consists of canister and impact limiters. IAEA Safety Standard Series No. TS-R-1 recommends a drop test to evaluate the structural integrity of a transportation package under a hypothetical accident condition. The free drop test of a transportation package from 9 m height simulates one of accident conditions. The transportation package has a potential energy corresponding to 9 m drop height, and this energy changes to a kinetic energy when it impacts on the target. The energy is absorbed by a deformation of shock-absorbing material so that the minimum energy is transferred to canister. Accordingly, the shock-absorbing material is a very important part in transportation package design. Since the data for shock-absorbing material characteristics is acquired by a static test in general, it is quite different to that of dynamic characteristics. And the dynamic characteristics data is hardly found in literature. In this study, a drop weight facility was designed and fabricated which produces an impact speed like that of free drop of 9 m height. Several materials considered for an impact limiter and impact limiter structures were tested by a drop weight facility to acquire a dynamic material characteristics data

Drop Weight Device Fabrication and Tests for a Dynamic Material Property of Shock-Absorbing Material and Structure in Transportation Package

Energy Technology Data Exchange (ETDEWEB)

Choi, Woo Seok; Jeon, Jea Eon; Han, Sang Hyeok; Lee, Sang Hoon; Seo, Ki Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

A radioactive material transportation package consists of canister and impact limiters. IAEA Safety Standard Series No. TS-R-1 recommends a drop test to evaluate the structural integrity of a transportation package under a hypothetical accident condition. The free drop test of a transportation package from 9 m height simulates one of accident conditions. The transportation package has a potential energy corresponding to 9 m drop height, and this energy changes to a kinetic energy when it impacts on the target. The energy is absorbed by a deformation of shock-absorbing material so that the minimum energy is transferred to canister. Accordingly, the shock-absorbing material is a very important part in transportation package design. Since the data for shock-absorbing material characteristics is acquired by a static test in general, it is quite different to that of dynamic characteristics. And the dynamic characteristics data is hardly found in literature. In this study, a drop weight facility was designed and fabricated which produces an impact speed like that of free drop of 9 m height. Several materials considered for an impact limiter and impact limiter structures were tested by a drop weight facility to acquire a dynamic material characteristics data.

Flow and pressure drop fluctuations in a vertical tube subject to low frequency oscillations

International Nuclear Information System (INIS)

Pendyala, Rajashekhar; Jayanti, Sreenivas; Balakrishnan, A.R.

2008-01-01

Heat transfer and other equipment mounted on off-shore platforms may be subjected to low frequency oscillations. The effect of these oscillations, typically in the frequency range of 0.1-1 Hz, on the flow rate and pressure drop in a vertical tube has been studied experimentally in the present work. A 1.75 m-long vertical tube of inner diameter 0.016 m was mounted on a plate and the whole plate was subjected to oscillations in the vertical plane using a mechanical simulator capable of providing low frequency oscillations in the range of 8-30 cycles/min at an amplitude of 0.125 m. The effect of the oscillations on the flow rate and the pressure drop has been measured systematically in the Reynolds number range 500-6500. The induced flow rate fluctuations were found to be dependent on the Reynolds number with stronger fluctuations at lower Reynolds numbers. The effective friction factor, based on the mean pressure drop and the mean flow rate, was also found to be higher than expected. Correlations have been developed to quantify this Reynolds number dependence

Flow and pressure drop fluctuations in a vertical tube subject to low frequency oscillations

Energy Technology Data Exchange (ETDEWEB)

Pendyala, Rajashekhar; Jayanti, Sreenivas [Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Balakrishnan, A.R. [Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)], E-mail: arbala@iitm.ac.in

2008-01-15

Heat transfer and other equipment mounted on off-shore platforms may be subjected to low frequency oscillations. The effect of these oscillations, typically in the frequency range of 0.1-1 Hz, on the flow rate and pressure drop in a vertical tube has been studied experimentally in the present work. A 1.75 m-long vertical tube of inner diameter 0.016 m was mounted on a plate and the whole plate was subjected to oscillations in the vertical plane using a mechanical simulator capable of providing low frequency oscillations in the range of 8-30 cycles/min at an amplitude of 0.125 m. The effect of the oscillations on the flow rate and the pressure drop has been measured systematically in the Reynolds number range 500-6500. The induced flow rate fluctuations were found to be dependent on the Reynolds number with stronger fluctuations at lower Reynolds numbers. The effective friction factor, based on the mean pressure drop and the mean flow rate, was also found to be higher than expected. Correlations have been developed to quantify this Reynolds number dependence.

Research on combustion of black-liquor drops

International Nuclear Information System (INIS)

Macek, A.

1999-01-01

Black liquor, the major by-product of the kraft process for production of pulp, is one of the most important industrial fuels. It is burned in recovery boilers in the form of large spray drops (mm), with the objective of simultaneous recovery of heat and chemicals (sodium and sulfur). Even though black-liquor combustion in boilers has been practised for over half a century, research efforts toward improvement of combustion efficiency and abatement of environmental emissions are much more recent. The present paper addresses a specific aspect of that research, namely, elucidation of processes which occur during combustion of black-liquor drops in boiler-gas streams. The paper (a) gives a brief description of the kraft process, (b) reviews the experimental and theoretical (modeling) research advances on combustion of kraft-liquor drops during the 1980s and 1990s, (c) re-examines the results of an earlier combustion study in which black-liquor drops were observed in free flight at temperatures near those in recovery boilers, and (d) recommends input for the modeling of in-flight combustion of kraft-liquor drops in recovery boilers. (author)

The evaporation of the charged and uncharged water drops

Indian Academy of Sciences (India)

Drop evaporation; ventilation coefficient; evaporation-effect of electrical forces. ... to study the effect of ventilation on the rate of evaporation of the millimeter sized ... a ventilated drop to reach its equilibrium temperature increases with the drop ...

Transfection of the IHH gene into rabbit BMSCs in a simulated microgravity environment promotes chondrogenic differentiation and inhibits cartilage aging.

Science.gov (United States)

Liu, Peng-Cheng; Liu, Kuan; Liu, Jun-Feng; Xia, Kuo; Chen, Li-Yang; Wu, Xing

2016-09-27

The effect of overexpressing the Indian hedgehog (IHH) gene on the chondrogenic differentiation of rabbit bone marrow-derived mesenchymal stem cells (BMSCs) was investigated in a simulated microgravity environment. An adenovirus plasmid encoding the rabbit IHH gene was constructed in vitro and transfected into rabbit BMSCs. Two large groups were used: conventional cell culture and induction model group and simulated microgravity environment group. Each large group was further divided into blank control group, GFP transfection group, and IHH transfection group. During differentiation induction, the expression levels of cartilage-related and cartilage hypertrophy-related genes and proteins in each group were determined. In the conventional model, the IHH transfection group expressed high levels of cartilage-related factors (Coll2 and ANCN) at the early stage of differentiation induction and expressed high levels of cartilage hypertrophy-related factors (Coll10, annexin 5, and ALP) at the late stage. Under the simulated microgravity environment, the IHH transfection group expressed high levels of cartilage-related factors and low levels of cartilage hypertrophy-related factors at all stages of differentiation induction. Under the simulated microgravity environment, transfection of the IHH gene into BMSCs effectively promoted the generation of cartilage and inhibited cartilage aging and osteogenesis. Therefore, this technique is suitable for cartilage tissue engineering.

Development of new testing methods for the numerical load analysis for the drop test of steel sheet containers for the final repository Konrad

International Nuclear Information System (INIS)

Protz, C.; Voelzke, H.; Zencker, U.; Hagenow, P.; Gruenewald, H.

2011-01-01

The qualification of steel sheet containers as intermediate-level waste container for the final repository is performed by the BAM (Bundeasmt fuer Materialpruefung) according to the BfS (Bundesamt fuer Strahlenschutz) requirements. The testing requirements include the stacking pressure tests, lifting tests, drop tests thermal tests (fire resistance) and tightness tests. Besides the verification using model or prototype tests and transferability considerations numerical safety analyses may be performed alternatively. The authors describe the internal BAM research project ConDrop aimed to develop extended testing methods for the drop test of steel sheet containers for the final repository Konrad using numerical load analyses. A finite element model was developed using The FE software LS-PrePost 3.0 and ANSYS 12.0 and the software FE-Code LS-DYNA for the simulation of the drop test (5 m height). The results were verified by experimental data from instrumented drop tests. The container preserves its integrity after the drop test, plastic deformation occurred at the bottom plate, the side walls, the cask cover and the lateral uprights.

Generic versus brand-name North American topical glaucoma drops.

Science.gov (United States)

Mammo, Zaid N; Flanagan, John G; James, David F; Trope, Graham E

2012-02-01

To determine whether brand-name glaucoma drops differ from generic equivalents in bottle design, viscosity, surface tension, and volume in North America. Experimental study. We studied 5 bottles each of 11 kinds of glaucoma drops. Density-based calculations of drop volume were assessed using 0.1 mg analytic balance. Viscosity was measured using rotational rheometery. Bottle tip diameter was measured using 0.05 mm Vernier calipers. Surface tension was measured using a Fisher Scientific (Ottawa, ON) tensiometer. For the American brand-name Timoptic XE, the average drop volume was 38 ± 3.1 μL versus 24 ± 1.5 μL of Timolol GFS (p brand-name Timoptic XE, the average drop volume was 42 ± 4.0 μL versus 25 ± 2 μL of timolol maleate EX (p brand-name Timoptic drop volume was 28 ± 1.4 μL versus 35 ± 1.9 μL Apo-Timop (p brand-name Timoptic delivered significantly smaller drop volumes than generic Apo-Timop. Careful consideration should be given to drop viscosity and bottle design when generic ophthalmic products are evaluated for interchangeability and market entry. Copyright © 2012 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Electric generation and ratcheted transport of contact-charged drops

Science.gov (United States)

Cartier, Charles A.; Graybill, Jason R.; Bishop, Kyle J. M.

2017-10-01

We describe a simple microfluidic system that enables the steady generation and efficient transport of aqueous drops using only a constant voltage input. Drop generation is achieved through an electrohydrodynamic dripping mechanism by which conductive drops grow and detach from a grounded nozzle in response to an electric field. The now-charged drops are transported down a ratcheted channel by contact charge electrophoresis powered by the same voltage input used for drop generation. We investigate how the drop size, generation frequency, and transport velocity depend on system parameters such as the liquid viscosity, interfacial tension, applied voltage, and channel dimensions. The observed trends are well explained by a series of scaling analyses that provide insight into the dominant physical mechanisms underlying drop generation and ratcheted transport. We identify the conditions necessary for achieving reliable operation and discuss the various modes of failure that can arise when these conditions are violated. Our results demonstrate that simple electric inputs can power increasingly complex droplet operations with potential opportunities for inexpensive and portable microfluidic systems.

Inverse Leidenfrost effect: self-propelling drops on a bath

Science.gov (United States)

Gauthier, Anais; van der Meer, Devaraj; Lohse, Detlef; Physics of Fluids Team

2017-11-01

When deposited on very hot solid, volatile drops can levitate over a cushion of vapor, in the so-called Leidenfrost state. This phenomenon can also be observed on a hot bath and similarly to the solid case, drops are very mobile due to the absence of contact with the substrate that sustains them. We discuss here a situation of ``inverse Leidenfrost effect'' where room-temperature drops levitate on a liquid nitrogen pool - the vapor is generated here by the bath sustaining the relatively hot drop. We show that the drop's movement is not random: the liquid goes across the bath in straight lines, a pattern only disrupted by elastic bouncing on the edges. In addition, the drops are initially self-propelled; first at rest, they accelerate for a few seconds and reach velocities of the order of a few cm/s, before slowing down. We investigate experimentally the parameters that affect their successive acceleration and deceleration, such as the size and nature of the drops and we discuss the origin of this pattern.

Drop formation of black liquor spraying; Mustalipeaen pisaroituminen

Energy Technology Data Exchange (ETDEWEB)

Fogelholm, C J; Kankkunen, A; Nieminen, K; Laine, J; Miikkulainen, P [Helsinki Univ. of Technology, Otaniemi (Finland): Lab. of Energy Technology and Environmental Protection

1997-10-01

Black liquor is a spent liquor of the pulp and paper industry. It is burned in kraft recovery boilers for chemical and energy recovery. The high dry solids content and viscosity of black liquor require a high spraying temperature. This affects the performance of the boiler. Kraft recovery boiler deposit formation, emissions and chemical recovery are strongly affected by the drop size and the velocity of the black liquor spray formed by a splashplate nozzle. The sheet breakup mechanism is studied with a system based on a video and image-analysis. The drop size of mill-scale nozzles was measured also with an image-analysis-system. Measurements were carried out in a spray test chamber. The sheet breakup mechanism and drop size tests were carried out both below and over the boiling point of black liquor. Special attention was paid to the effect of flashing on drop formation. Temperature increase normally decreases drop size. In the temperature where the wavy-sheet disintegration changes to perforated-sheet disintegration the drop size increases. Spray velocity rises when the temperature is increased above the boiling point. (orig.)

Ultrasonic defect-sizing using decibel drop methods. I

International Nuclear Information System (INIS)

Murphy, R.V.

1987-03-01

Results are reported of a study performed to investigate the accuracy and repeatability of various ultrasonic decibel (dB) drop sizing methods in determining the length, vertical extent and orientation of artificial and real weld flaws in thin steel sections. Seven artificial flaws and nine real weld flaws were examined; over 200 data plots were produced. The general findings are: a) length and vertical extent are assessed most accurately when using a 14 dB drop from the maximum indication amplitude; b) decibel drops less that 14 dB generally undersize flaws while decibel drops greater than 14 dB generally oversize flaws; c) flaws which are smaller than the width of the sound beam cannot be assessed accurately using dB drop methods; d) large flaws are assessed most accurately when the sound beam strikes the flaws at near normal incidence; e) the vertical extent and orientation of large flaws are plotted most accurately using the beam centre line method as opposed to the beam profile method; and, f) the limitations of dB-drop-sizing methods have considerable ramifications for CAN3-N285.4-M83 and ASME XI evaluation criteria

PERFLUOROCARBON LIQUIDS' ABILITY TO PROTECT THE MACULA FROM INTRAOCULAR DROPPING OF METALLIC FOREIGN BODIES: A Model Eye Study.

Science.gov (United States)

Shah, Chirag M; Gentile, Ronald C; Mehta, Mitul C

2016-07-01

To examine the utility of perfluoro-n-octane (PFO) in balanced salt solution (BSS) to shield the macula from the impact of dropped metallic intraocular foreign bodies (IOFBs) by modeling scenarios in which they may fall during surgical removal. Model eyes were filled with various fluid mixtures (Group 1: 10% PFO/90% BSS; Group 2: 100% BSS; Group 3: 100% PFO; Group 4: 10% PFO/90% air; Group 5: 10% BSS/90% air). In Groups 1, 4, and 5, the 10% fluid volume covered the theoretical macula. For each fluid mixture, up to 30 IOFB drop scenarios were performed for each of the 5 sample IOFBs from 3 locations. Trajectories were recorded using a camera attached to a Zeiss operating microscope (Carl Zeiss, Jena, Germany). The percentages of IOFBs impacting the macula were calculated and Fisher exact test was used to assess differences. In Group 1, 93% (417/450) of the dropped IOFBs were deflected by the PFO-BSS interface compared with 0% (0/500) in Groups 2, 3, 4, and 5 (P macula in 30% of tests when dropped from the superior posterior segment (P < 0.01), all other IOFBs (2.8-13.4 mg) were deflected by the PFO-BSS interface in 100% of Group 1 drops (P < 0.01). As demonstrated by these simulations, the PFO-BSS interface can deflect IOFBs dropped during surgery in a wide range of scenarios, especially when the IOFB is of lower mass.

The dynamics of liquid drops and their interaction with solids of varying wettabilities

KAUST Repository

Sprittles, J. E.

2012-01-01

Microdrop impact and spreading phenomena are explored as an interface formation process using a recently developed computational framework. The accuracy of the results obtained from this framework for the simulation of high deformation free-surface flows is confirmed by a comparison with previous numerical studies for the large amplitude oscillations of free liquid drops. Our code\\'s ability to produce high resolution benchmark calculations for dynamic wetting flows is then demonstrated by simulating microdrop impact and spreading on surfaces of greatly differing wettability. The simulations allow one to see features of the process which go beyond the resolution available to experimental analysis. Strong interfacial effects which are observed at the microfluidic scale are then harnessed by designing surfaces of varying wettability that allow new methods of flow control to be developed. © 2012 American Institute of Physics.

Drop test of reinforced concrete slab onto storage cask

International Nuclear Information System (INIS)

Kato, Y.; Hattori, S.; Ito, C.; Sirai, K.; Ozaki, S.; Kato, O.

1993-01-01

In this research, drop tests onto full-scale casks considering the specifications of a falling object (weight, construction, drop height, etc.) demonstrate and evaluate the integrity of casks in case a heavy object drops into the storage facilities. (J.P.N.)

Survival of Listeria monocytogenes in simulated gastrointestinal system and transcriptional profiling of stress- and adhesion-related genes

DEFF Research Database (Denmark)

Jiang, Lingli; Olesen, Inger; Andersen, Thomas

2010-01-01

-related genes after exposure to the conditions similar to those encountered in the mouth, stomach, and small intestine. None of the L. monocytogenes strains investigated could survive in the gastric juice at pH 2.5 or 3.0. Their survival increased at higher pH (3.5 and 4.0) in the gastric stress. Relative...... afterpassing through the simulated gastrointestinal tract, whereas that of the adhesion-related gene ami was downregulated. Taken together, this study revealed that L. monocytogenes strains enhanced the expression of stressrelated genes and decreased the transcription of adhesion-related gene in order...

Numerical study of drop spreading on a flat surface

Science.gov (United States)

Wang, Sheng; Desjardins, Olivier

2017-11-01

In this talk, we perform a numerical study of a droplet on a flat surface with special emphasis on capturing the spreading dynamics. The computational methodology employed is tailored for simulating large-scale two-phase flows within complex geometries. It combines a conservative level-set method to capture the liquid-gas interface, a conservative immersed boundary method to represent the solid-fluid interface, and a sub-grid curvature model at the triple-point to implicitly impose the contact angle of the liquid-gas interface. The performance of the approach is assessed in the inertial droplet spreading regime, the viscous spreading regime of high viscosity drops, and with the capillary oscillation of low viscosity droplets.

A numerical analysis on the heat transfer and pressure drop characteristics of welding type plate heat exchangers

International Nuclear Information System (INIS)

Jeong, Jong Yun; Kang, Yong Tae; Nam, Sang Chul

2008-01-01

Numerical analysis was carried out to examine the heat transfer and pressure drop characteristics of plate heat exchangers for absorption application using computational Fluid Dynamics(CFD) technique. A commercial CFD software package, FLUENT was used to predict the characteristics of heat transfer, pressure drop and flow distribution within plate heat exchangers. In this paper, a welded plate heat exchanger with the plate of chevron embossing type was numerically analyzed by controlling mass flow rate, solution concentration, and inlet temperatures. The working fluid is H 2 O/LiBr solution with the LiBr concentration of 50∼60% in mass. The numerical simulation show reasonably good agreement with the experimental results. Also, the numerical results show that plate of the chevron shape gives better results than plate of the elliptical shape from the view points of heat transfer and pressure drop. These results provide a guideline to apply the welded PHE for the solution heat exchanger of absorption systems

Fluid mechanics calculations in physics of droplets – IV: Head-on and off-center numerical collisions of unequal-size drops

Directory of Open Access Journals (Sweden)

Alejandro Acevedo-Malavé

2016-09-01

Full Text Available In this study, the finite volume method is employed to simulate the coalescence collision between water drops immersed in a continuous phase (n-heptane. For that purpose, it is chosen a range of values for the velocity of collisions for the finite volume calculations may yield different possible outcomes of the collision process. It can be seen for head-on collisions that when the velocity of collision is 0.2 m/s and 3.5 m/s, the little drop induces the formation of a hole in the bigger drop, until the surface tension forces to restore the circular form of the resulting drop. For a velocity of collision of 16.0 m/s, the little drop deforms the bigger one, and the system is converted into a thin ligament with the evolution of the dynamics. In this case, a little mass of n-heptane is trapped between the two drops, but at the end of the dynamics it drains to the continuous phase. For off-center collisions, two different values for the velocity of collisions were chosen, and the drops exhibit a lot of waves on the droplets’ surface. The streamlines are calculated for the process of coalescence of drops. These streamlines allow the understanding of the dynamics of the droplets immersed on the n-heptane phase. The effect of the interfacial tension it is showed due to the oscillations that the droplet exhibits. When the coalescence has begun, the streamlines form circular patterns at the zone of contact between the drops which explain the increment of the thickness of the bridge structure of the fluid between the two drops. At the end of the dynamics, when the velocity is of 0.2 m/s, the bigger drop reaches a circular form approximately, but when the velocity is of 3.5 m/s the drop reaches an elongated form.

Impact of ultra-viscous drops: air-film gliding and extreme wetting

KAUST Repository

Langley, Kenneth; Li, Erqiang; Thoroddsen, Sigurdur T

2017-01-01

water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a

Effect of humidity on the filter pressure drop

International Nuclear Information System (INIS)

Vendel, J.; Letourneau, P.

1995-01-01

The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO 2 ). Cesium hydroxyde (CsOH) of size of 2 μ M AMMD has been generated by an ultrasonic generator and the 0.7 μm AMMD titanium oxyde has been dispersed by a open-quotes turn-tableclose quotes generator. As it is noted in the BISWAS'publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced

Effect of humidity on the filter pressure drop

Energy Technology Data Exchange (ETDEWEB)

Vendel, J.; Letourneau, P. [Institut de Protection et de Surete Nucleaire, Gif-sur-Yvette (France)

1995-02-01

The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

Antisense-induced suppression of taxoid 14β- hydroxylase gene ...

African Journals Online (AJOL)

Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the 14OH mRNA level in transgenic cells dropped dramatically, suggesting that the expression of endogenous14OH gene was significantly suppressed by the exogenous as14OH gene. Correspondingly, the total yield of three major C-14 ...

Ballistic Jumping Drops on Superhydrophobic Surfaces via Electrostatic Manipulation.

Science.gov (United States)

Li, Ning; Wu, Lei; Yu, Cunlong; Dai, Haoyu; Wang, Ting; Dong, Zhichao; Jiang, Lei

2018-02-01

The ballistic ejection of liquid drops by electrostatic manipulating has both fundamental and practical implications, from raindrops in thunderclouds to self-cleaning, anti-icing, condensation, and heat transfer enhancements. In this paper, the ballistic jumping behavior of liquid drops from a superhydrophobic surface is investigated. Powered by the repulsion of the same kind of charges, water drops can jump from the surface. The electrostatic acting time for the jumping of a microliter supercooled drop only takes several milliseconds, even shorter than the time for icing. In addition, one can control the ballistic jumping direction precisely by the relative position above the electrostatic field. The approach offers a facile method that can be used to manipulate the ballistic drop jumping via an electrostatic field, opening the possibility of energy efficient drop detaching techniques in various applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Annual Occurrence of Meteorite-Dropping Fireballs

Science.gov (United States)

Konovalova, Natalia; Jopek, Tadeusz J.

2016-07-01

The event of Chelyabinsk meteorite has brought about change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the meteorite. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of meteorites with the known fall dates and of the meteorite-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of meteorites and meteorite-dropping fireballs shows several periods of increased activity in the course of the year. The analysis of the atmospheric trajectories and physical properties of sporadic meteorite-dropping fireballs observed in Tajikistan by instrumental methods in the summer‒autumn periods of increased fireballs activity has been made. As a result the structural strength, the bulk density and terminal mass of the studied fireballs that can survive in the Earth atmosphere and became meteorites was obtained. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by D-criterion of Southworth and Hawkins the fireballs that could be the members of group of meteorite-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for meteorite-dropping fireballs was made and the evolution of orbits of these objects in the past on a long interval of time was investigated.

The effect of dropping impact on bruising pomegranate fruit

Directory of Open Access Journals (Sweden)

M Mohammad Shafie

2016-04-01

Full Text Available Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred in harvest and postharvest stages. The bruising is defined as damage to fruit flesh usually with no abrasion of the peel. The two different types of dynamic loading which can physically cause fruit bruising are impact and vibration. The impact and vibration loadings may occur during picking or sorting as the pomegranates are dropped into storage bins and during transportation. The focus of this work was on the impact loading as this appeared to be the most prevalent. In view of the limitations of conventional testing methods (ASTM D3332 Standard Test Methods for Mechanical Shock Fragility of Products, the method and procedure for determining dropping bruise boundary of fruit were also established by adapting free-fall dropping tests. Materials and Methods: After the ‘Malas-e-Saveh’ pomegranates had been selected, they were numbered, and the weight and dimension of each sample were measured and recorded. Firmness in cheek region of each fruit was also measured. Fruit firmness was determined by measuring the maximum force during perforating the sample to a depth of 10 mm at a velocity of 100 mm min-1 with an 8 mm diameter cylindrical penetrometer mounted onto a STM-5 Universal Testing Machine (SANTAM, Design CO. LTD., England. Free-fall dropping tests with a series of drop heights (6, 7, 10, 15, 30 and 60 cm were conducted on fresh ‘Malas-e-Saveh’ pomegranates. Three samples were used for each dropping height, and each sample was subjected to impact on two different positions. Before the test was started, it was necessary to control the sample's drop position. The cheek of sample was placed on the fruit holder. An aluminum plate mounted

Liquid toroidal drop under uniform electric field

Science.gov (United States)

Zabarankin, Michael

2017-06-01

The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ⁡ρ +2 ln ⁡[96 π ]-9 )/ (12 ln ⁡ρ +4 ln ⁡[96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.

9 m side drop test of scale model

International Nuclear Information System (INIS)

Ku, Jeong-Hoe; Chung, Seong-Hwan; Lee, Ju-Chan; Seo, Ki-Seog

1993-01-01

A type B(U) shipping cask had been developed in KAERI for transporting PWR spent fuel. Since the cask is to transport spent PWR fuel, it must be designed to meet all of the structural requirements specified in domestic packaging regulations and IAEA safety series No.6. This paper describes the side drop testing of a one - third scale model cask. The crush and deformations of the shock absorbing covers directly control the deceleration experiences of the cask during the 9 m side drop impact. The shock absorbing covers greatly mitigated the inertia forces of the cask body due to the side drop impact. Compared with the side drop test and finite element analysis, it was verified that the 1/3 scale model cask maintain its structural integrity of the model cask under the side drop impact. The test and analysis results could be used as the basic data to evaluate the structural integrity of the real cask. (J.P.N.)

Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry.

Science.gov (United States)

Shrivas, Kamlesh; Wu, Hui-Fen

2007-11-02

A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

Air-drop blood supply in the French Army.

Science.gov (United States)

Javaudin, Olivier; Baillon, A; Varin, N; Martinaud, C; Pouget, T; Civadier, C; Clavier, B; Sailliol, A

2018-02-12

Haemorrhagic shock remains the leading cause of preventable death in overseas and austere settings. Transfusion of blood components is critical in the management of this kind of injury. For French naval and ground military units, this supply often takes too long considering the short shelf-life of red blood cell concentrates (RBCs) and the limited duration of transport in cooling containers (five to six days). Air-drop supply could be an alternative to overcome these difficulties on the condition that air-drop does not cause damage to blood units. After a period of study and technical development of packaging, four air-drops at medium and high altitudes were performed with an aircraft of the French Air Force. After this, one air-drop was carried out at medium altitude with 10 RBCs and 10 French lyophilised plasma (FLYP). A second air-drop was performed with a soldier carrying one FLYP unit at 12 000 feet. For these air-drops real blood products were used, and quality control testing and temperature monitoring were performed. The temperatures inside the containers were within the normal ranges. Visual inspection indicated that transfusion packaging and dumped products did not undergo deterioration. The quality control data on RBCs and FLYP, including haemostasis, suggested no difference before and after air-drop. The operational implementation of the air-drop of blood products seems to be one of the solutions for the supply of blood products in military austere settings or far forward on battlefield, allowing safe and early transfusion. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Nectar and pollination drops: how different are they?

Science.gov (United States)

Nepi, Massimo; von Aderkas, Patrick; Wagner, Rebecca; Mugnaini, Serena; Coulter, Andrea; Pacini, Ettore

2009-08-01

Pollination drops and nectars (floral nectars) are secretions related to plant reproduction. The pollination drop is the landing site for the majority of gymnosperm pollen, whereas nectar of angiosperm flowers represents a common nutritional resource for a large variety of pollinators. Extrafloral nectars also are known from all vascular plants, although among the gymnosperms they are restricted to the Gnetales. Extrafloral nectars are not generally involved in reproduction but serve as 'reward' for ants defending plants against herbivores (indirect defence). Although very different in their task, nectars and pollination drops share some features, e.g. basic chemical composition and eventual consumption by animals. This has led some authors to call these secretions collectively nectar. Modern techniques that permit chemical analysis and protein characterization have very recently added important information about these sugary secretions that appear to be much more than a 'reward' for pollinating (floral nectar) and defending animals (extrafloral nectar) or a landing site for pollen (pollination drop). Nectar and pollination drops contain sugars as the main components, but the total concentration and the relative proportions are different. They also contain amino acids, of which proline is frequently the most abundant. Proteomic studies have revealed the presence of common functional classes of proteins such as invertases and defence-related proteins in nectar (floral and extrafloral) and pollination drops. Invertases allow for dynamic rearrangement of sugar composition following secretion. Defence-related proteins provide protection from invasion by fungi and bacteria. Currently, only few species have been studied in any depth. The chemical composition of the pollination drop must be investigated in a larger number of species if eventual phylogenetic relationships are to be revealed. Much more information can be provided from further proteomic studies of both

Controlling Vapor Pressure In Hanging-Drop Crystallization

Science.gov (United States)

Carter, Daniel C.; Smith, Robbie

1988-01-01

Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

Application of Proteomics to the Study of Pollination Drops

Directory of Open Access Journals (Sweden)

Natalie Prior

2013-04-01

Full Text Available Premise of the study: Pollination drops are a formative component in gymnosperm pollen-ovule interactions. Proteomics offers a direct method for the discovery of proteins associated with this early stage of sexual reproduction. Methods: Pollination drops were sampled from eight gymnosperm species: Chamaecyparis lawsoniana (Port Orford cedar, Ephedra monosperma, Ginkgo biloba, Juniperus oxycedrus (prickly juniper, Larix ×marschlinsii, Pseudotsuga menziesii (Douglas-fir, Taxus ×media, and Welwitschia mirabilis. Drops were collected by micropipette using techniques focused on preventing sample contamination. Drop proteins were separated using both gel and gel-free methods. Tandem mass spectrometric methods were used including a triple quadrupole and an Orbitrap. Results: Proteins are present in all pollination drops. Consistency in the protein complement over time was shown in L. ×marschlinsii. Representative mass spectra from W. mirabilis chitinase peptide and E. monosperma serine carboxypeptidase peptide demonstrated high quality results. We provide a summary of gymnosperm pollination drop proteins that have been discovered to date via proteomics. Discussion: Using proteomic methods, a dozen classes of proteins have been identified to date. Proteomics presents a way forward in deepening our understanding of the biological function of pollination drops.

Cavity optomechanics in a levitated helium drop

Science.gov (United States)

Childress, L.; Schmidt, M. P.; Kashkanova, A. D.; Brown, C. D.; Harris, G. I.; Aiello, A.; Marquardt, F.; Harris, J. G. E.

2017-12-01

We describe a proposal for a type of optomechanical system based on a drop of liquid helium that is magnetically levitated in vacuum. In the proposed device, the drop would serve three roles: its optical whispering-gallery modes would provide the optical cavity, its surface vibrations would constitute the mechanical element, and evaporation of He atoms from its surface would provide continuous refrigeration. We analyze the feasibility of such a system in light of previous experimental demonstrations of its essential components: magnetic levitation of mm-scale and cm-scale drops of liquid He , evaporative cooling of He droplets in vacuum, and coupling to high-quality optical whispering-gallery modes in a wide range of liquids. We find that the combination of these features could result in a device that approaches the single-photon strong-coupling regime, due to the high optical quality factors attainable at low temperatures. Moreover, the system offers a unique opportunity to use optical techniques to study the motion of a superfluid that is freely levitating in vacuum (in the case of 4He). Alternatively, for a normal fluid drop of 3He, we propose to exploit the coupling between the drop's rotations and vibrations to perform quantum nondemolition measurements of angular momentum.

Self-excited hydrothermal waves in evaporating sessile drops

Science.gov (United States)

Sefiane, K.; Moffat, J. R.; Matar, O. K.; Craster, R. V.

2008-08-01

Pattern formation driven by the spontaneous evaporation of sessile drops of methanol, ethanol, and FC-72 using infrared thermography is observed and, in certain cases, interpreted in terms of hydrothermal waves. Both methanol and ethanol drops exhibit thermal wave trains, whose wave number depends strongly on the liquid volatililty and substrate thermal conductivity. The FC-72 drops develop cellular structures whose size is proportional to the local thickness. Prior to this work, hydrothermal waves have been observed in the absence of evaporation in shallow liquid layers subjected to an imposed temperature gradient. In contrast, here both the temperature gradients and the drop thickness vary spatially and temporally and are a natural consequence of the evaporation process.

Advantages of Westinghouse BWR control rod drop accidents methodology utilizing integrated POLCA-T code

International Nuclear Information System (INIS)

Panayotov, Dobromir

2008-01-01

The paper focuses on the activities pursued by Westinghouse in the development and licensing of POLCA-T code Control Rod Drop Accident (CRDA) Methodology. The comprehensive CRDA methodology that utilizes PHOENIX4/POLCA7/POLCA-T calculation chain foresees complete cycle-specific analysis. The methodology consists of determination of candidates of control rods (CR) that could cause a significant reactivity excursion if dropped throughout the entire fuel cycle, selection of limiting initial conditions for CRDA transient simulation and transient simulation itself. The Westinghouse methodology utilizes state-of-the-art methods. Unnecessary conservatisms in the methodology have been avoided to allow the accurate prediction of margin to design bases. This is mainly achieved by using the POLCA-T code for dynamic CRDA evaluations. The code belongs to the same calculation chain that is used for core design. Thus the very same reactor, core, cycle and fuel data base is used. This allows also reducing the uncertainties of input data and parameters that determine the energy deposition in the fuel. Uncertainty treatment, very selective use of conservatisms, selection of the initial conditions for limiting case analyses, incorporation into POLCA-T code models of the licensed fuel performance code are also among the means of performing realistic CRDA transient analyses. (author)

Drop Impact on Textile Material: Effect of Fabric Properties

Directory of Open Access Journals (Sweden)

Romdhani Zouhaier

2014-09-01

Full Text Available This paper presents an experimental study of impact of water drop on a surface in a spreading regime with no splashing. Three surfaces were studied: virgin glass, coating film and woven cotton fabric at different construction parameters. All experiments were carried out using water drop with the same free fall high. Digidrop with high-resolution camera is used to measure the different parameters characterising this phenomenon. Results show an important effect of the height of the free fall on the drop profile and the spreading behaviour. An important drop deformation at the surface impact was observed. Then, fabric construction as the weft count deeply affects the drop impact. For plain weave, an increase of weft count causes a decrease in penetration and increase in the spreading rate. The same result was obtained for coated fabric. Therefore, the impact energy was modified and the drop shape was affected, which directly influenced the spreading rate.

A study of fungi on droppings of certain birds

Directory of Open Access Journals (Sweden)

C. S. Singh

2014-08-01

Full Text Available Droppings of fowl, owl, parrot, pigeon and sparrow were asepticaly collected in sterilized bottles from different places at Gorakhpur, 54 fungi were isolated. The number of fungi was more in the pigeon showing considerable decrease in the fowl and the sparrow. In the parrot and the owl, however. the fungi were egual in number. The number of Phycomycetes was almost the same on droppings of all birds, from parrot only one species could be isolated. A larger number of Ascomyteces was recorded from fowl, less from pigeon and owl and the least (two each on sparrow and parrot droppings. The Basidiomycetes, represented by two species only, were recorded on owl and pigeon droppings. Pigeon droppings yielded the largest number of Deuteromycetes. They were egual in numbers on owl and parrot while on fowl and sparrow their number was comparatively less. Mycelia sterilia, though poor in their numbers, were recorded on all the bird droppings excepting owl.

Afterlife of a Drop Impacting a Liquid Pool

Science.gov (United States)

Saha, Abhishek; Wei, Yanju; Tang, Xiaoyu; Law, Chung K.

2017-11-01

Drop impact on liquid pool is ubiquitous in industrial processes, such as inkjet printing and spray coating. While merging of drop with the impacted liquid surface is essential to facilitate the printing and coating processes, it is the afterlife of this merged drop and associated mixing which control the quality of the printed or coated surface. In this talk we will report an experimental study on the structural evolution of the merged droplet inside the liquid pool. First, we will analyze the depth of the crater created on the pool surface by the impacted drop for a range of impact inertia, and we will derive a scaling relation and the associated characteristic time-scale. Next, we will focus on the toroidal vortex formed by the moving drop inside the liquid pool and assess the characteristic time and length scales of the penetration process. The geometry of the vortex structure which qualitatively indicates the degree of mixedness will also be discussed. Finally, we will present the results from experiments with various viscosities to demonstrate the role of viscous dissipation on the geometry and structure formed by the drop. This work is supported by the Army Research Office and the Xerox Corporation.

Drop shape visualization and contact angle measurement on curved surfaces.

Science.gov (United States)

Guilizzoni, Manfredo

2011-12-01

The shape and contact angles of drops on curved surfaces is experimentally investigated. Image processing, spline fitting and numerical integration are used to extract the drop contour in a number of cross-sections. The three-dimensional surfaces which describe the surface-air and drop-air interfaces can be visualized and a simple procedure to determine the equilibrium contact angle starting from measurements on curved surfaces is proposed. Contact angles on flat surfaces serve as a reference term and a procedure to measure them is proposed. Such procedure is not as accurate as the axisymmetric drop shape analysis algorithms, but it has the advantage of requiring only a side view of the drop-surface couple and no further information. It can therefore be used also for fluids with unknown surface tension and there is no need to measure the drop volume. Examples of application of the proposed techniques for distilled water drops on gemstones confirm that they can be useful for drop shape analysis and contact angle measurement on three-dimensional sculptured surfaces. Copyright © 2011 Elsevier Inc. All rights reserved.

Device for making liquid drops

International Nuclear Information System (INIS)

Yamada, Masao; Fukuda, Fumito; Nishikawa, Masana; Ishii, Takeshi.

1976-01-01

Object: To provide a device for producing liquid drops in the form of liquefied gases indispensable to make deuterium and tritium ice pellets used as a fusion fuel in a tokamak type fusion reactor. Structure: First, pressure P 1 at the upper surface of liquefied gas in a container and outlet pressure P 2 of a nozzle disposed at the lower part of the container are adjusted into the state of P 1 >= P 2 , and it is preset so that even under such conditions, the liquefied gas from the nozzle is not naturally flown out. Next, a vibration plate disposed within the container is rapidly downwardly advanced toward the nozzle through a predetermined distance. As a result, pressure of the liquefied gas within a depression under the vibration plate rises instantaneously or in a pulse fashion to dissatisfy the aforesaid set condition whereby the liquefied gas may be flown out from the nozzle in the form of liquid drops. In accordance with the present device, it is possible to produce a suitable number of drops at a suitable point. (Yoshihara, H.)

Vertical vibration dynamics of acoustically levitated drop containing two immiscible liquids

Science.gov (United States)

Zang, Duyang; Zhai, Zhicong; Li, Lin; Lin, Kejun; Li, Xiaoguang; Geng, Xingguo

2016-09-01

We have studied the levitation and oscillation dynamics of complex drops containing two immiscible liquids. Two types of drops, core-shell drop and abnormal-shaped drop, have been obtained depending on the levitation procedures. The oscillation dynamics of the drops have been studied using a high speed camera. It has been found that the oscillation of the abnormal-shaped drop has a longer oscillation period and decays much faster than that of the core-shell drop, which cannot be accounted for by the air resistance itself. The acoustic streaming induced by ultrasound may bring an additional force against the motion of the drop due to the Bernoulli effect. This is responsible for the enhanced damping during the oscillation in acoustic levitation.

Drop-In Clinics for Environmental Science Students

Directory of Open Access Journals (Sweden)

Marcie Lynne Jacklin

2008-12-01

Full Text Available This paper describes the use of drop in clinics as a new pedagogical approach in information literacy instruction. Although drop in clinics have been used before for library instruction purposes, they are generally aligned with improvement of student academic writing. In the scenario described in this article, in contrast, the drop in clinic is used in a different manner. The drop in clinic as described here offers students an opportunity to engage in self-directed learning by letting them control the content of the instruction. The clinic is offered to students as a way for them to direct their own learning of the course content. It is facilitated by the librarian but it is not controlled by the librarian. The use of this innovative approach is grounded in the example of environmental science and tourism students at a medium sized university in Ontario and it is an approach that has been jointly promoted to students by both the librarian and the course instructor.

Application of volume of fluid method for simulation of a droplet impacting a fiber

Directory of Open Access Journals (Sweden)

M. Khalili

2016-06-01

Full Text Available In the present work, impact of a Newtonian drop on horizontal thin fibers with circular cross section is simulated in 2D views. The numerical simulations of the phenomena are carried out using volume of fluid (VOF method for tracking the free surface motion. Impacting of a Newtonian droplet on a circular thin fiber (350μm radius investigated numerically. The main focus of this simulation is to acquire threshold radius and velocity of a drop which is entirely captured by the fiber. The model agrees well with the experiments and demonstrates the threshold radius decreased generally with the increase of impact velocity. In other words, for velocity larger than threshold velocity of capture perhaps only a small portion of fluid is stuck on the solid and the rest of the drop is ejected for impact velocity smaller than critical velocity the drop is totally captured. This threshold velocity has been determined when the impact is centered.

Self-excited hydrothermal waves in evaporating sessile drops

OpenAIRE

Sefiane K.; Moffat J.R.; Matar O.K.; Craster R.V.

2008-01-01

Pattern formation driven by the spontaneous evaporation of sessile drops of methanol, ethanol, and FC-72 using infrared thermography is observed and, in certain cases, interpreted in terms of hydrothermal waves. Both methanol and ethanol drops exhibit thermal wave trains, whose wave number depends strongly on the liquid volatililty and substrate thermal conductivity. The FC- 72 drops develop cellular structures whose size is proportional to the local thickness. Prior to this work, hydrotherma...

Drop tests of the Three Mile Island knockout canister

International Nuclear Information System (INIS)

Box, W.D.; Aaron, W.S.; Shappert, L.B.; Childress, P.C.; Quinn, G.J.; Smith, J.V.

1987-01-01

A type of Three Mile Island Unit 2 (TMI-2) defueling canister, called a ''knockout'' canister, was subjected to a series of drop tests at the Oak Ridge National Laboratory's Drop Test Facility. These tests confirmed the structural integrity of internal fixed neutron poisons in support of a request for NRC licensing of this type of canister for the shipment of TMI-2 reactor fuel debris to the Idaho National Engineering Laboratory (INEL) for the Core Examination R and D Program. This report presents the data generated and the results obtained from a series of four drop tests that included two drops with the test assembly in the vertical position and two drops with the assembly in the horizontal position

Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.

Science.gov (United States)

Yang, Xianfeng; Zhang, Zhiqiang; Yang, Jialing; Sun, Yuxin

2016-01-01

The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.

Vertical vibration and shape oscillation of acoustically levitated water drops

International Nuclear Information System (INIS)

Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

2014-01-01

We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

Vertical vibration and shape oscillation of acoustically levitated water drops

Energy Technology Data Exchange (ETDEWEB)

Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

2014-09-08

We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

Surfactant-Enhanced Benard Convection on an Evaporating Drop

Science.gov (United States)

Nguyen, Van X.; Stebe, Kathleen J.

2001-11-01

Surfactant effects on an evaporating drop are studied experimentally. Using a fluorescent probe, the distribution and surface phase of the surfactant is directly imaged throughout the evaporation process. From these experiments, we identify conditions in which surfactants promote surface tension-driven Benard instabilities in aqueous systems. The drops under study contain finely divided particles, which act as tracers in the flow, and form well-defined patterns after the drop evaporates. Two flow fields have been reported in this system. The first occurs because the contact line becomes pinned by solid particles at the contact line region. In order for the contact line to remain fixed, an outward flow toward the ring results, driving further accumulation at the contact ring. A ‘coffee ring’ of particles is left as residue after the drop evaporates[1]. The second flow is Benard convection, driven by surface tension gradients on the drop[2,3]. In our experiments, an insoluble monolayer of pentadecanoic acid is spread at the interface of a pendant drop. The surface tension is recorded, and the drop is deposited on a well-defined solid substrate. Fluorescent images of the surface phase of the surfactant are recorded as the drop evaporates. The surfactant monolayer assumes a variety of surface states as a function of the area per molecule at the interface: surface gaseous, surface liquid expanded, and surface liquid condensed phases[4]. Depending upon the surface state of the surfactant as the drop evaporates, transitions of residue patterns left by the particles occur, from the coffee ring pattern to Benard cells to irregular patterns, suggesting a strong resistance to outward flow are observed. The occurrence of Benard cells on a surfactant-rich interface occurs when the interface is in LE-LC coexistence. Prior research concerning surfactant effects on this instability predict that surfactants are strongly stabilizing[5]. The mechanisms for this change in behavior

[Stability of physical state on compound hawthorn dropping pills].

Science.gov (United States)

Zhang, Wei; Chen, Hong-Yan; Jiang, Jian-Lan

2008-11-01

To evaluate the stability of physical state with accelerate test and dropping in process before and after on compound hawthorn dropping pills. Scanning electron microscope, TG-DTA, FT-IR and XRD were used. The active components presented amorphous, tiny crystal and molecular state in dropping pills, and it had no obvious reaction between PEG 4000 and active components. With time prolonging, a little of active components changed from amorphous state to tiny crystal or molecular state. Solid dispersion improved the stability and dissolution of compound hawthorn dropping pills.

Preparation and characterisation of superheated drop detectors

International Nuclear Information System (INIS)

Krishnamoorthy, P.

1989-01-01

Basic mechanism of bubble nucleation in superheated drops with respect to minimum energy of radiation and temperature is discussed. Experimental details and techniques for the preparation of Superheated Drop Detectors (SDDs) is explained. For the sample preparation, homogeneous composition of polymer (Morarfloc) and glycerine was used as the host medium and three different refrigerants Mafron-21, Mafron-12 and Mafron-11/12 (50:50) were chosen as the sensitive liquids. A pressure reactor developed at Health and Safety Laboratory is used for dispersing the sensitive liquid drops in the homogeneous composition under pressure. Some of the imporatant detector characteristics were studied. (author). 26 refs., 9 figs., 1 tab

Underwater sound produced by individual drop impacts and rainfall

DEFF Research Database (Denmark)

Pumphrey, Hugh C.; Crum, L. A.; Jensen, Leif Bjørnø

1989-01-01

An experimental study of the underwater sound produced by water drop impacts on the surface is described. It is found that sound may be produced in two ways: first when the drop strikes the surface and, second, when a bubble is created in the water. The first process occurs for every drop...

From nuclear reactions to liquid-drop collisions

International Nuclear Information System (INIS)

Menchaca R, A.; Huidobro, F.; Martinez D, A.; Michaelian, K.; Perez, A.; Rodriguez, V.; Carjan, N.

1997-01-01

A review of the experimental and theoretical situation in coalescence and fragmentation studies of binary liquid-drop collisions is given, putting in perspective our own contributions, which include experiments with mercury and oil drops and the application of a nuclear reaction model, specifically modified by us for the macroscopic case. (Author)

Drop dynamics on a stretched viscoelastic filament: An experimental study

Science.gov (United States)

Peixinho, Jorge; Renoult, Marie-Charlotte; Crumeyrolle, Olivier; Mutabazi, Innocent

2016-11-01

Capillary pressure can destabilize a thin liquid filament during breakup into a succession of drops. Besides, the addition of a linear, high molecular weight, flexible and soluble polymer is enough to modify the morphology of this instability. In the time period preceding the breakup, the development of beads-on-a-string structures where drops are connected by thin threads is monitored. The drops dynamics involve drop formation, drop migration and drop coalescence. Experiments using a high-speed camera on stretched bridges of viscoelastic polymeric solutions were conducted for a range of viscosities and polymer concentrations. The rheological properties of the solutions are also quantified through conventional shear rheology and normal stress difference. The overall goal of this experimental investigation is to gain more insight into the formation and time evolution of the drops. The project BIOENGINE is co-financed by the European Union with the European regional development fund and by the Normandie Regional Council.

Building micro-soccer-balls with evaporating colloidal fakir drops

Science.gov (United States)

Gelderblom, Hanneke; Marín, Álvaro G.; Susarrey-Arce, Arturo; van Housselt, Arie; Lefferts, Leon; Gardeniers, Han; Lohse, Detlef; Snoeijer, Jacco H.

2013-11-01

Drop evaporation can be used to self-assemble particles into three-dimensional microstructures on a scale where direct manipulation is impossible. We present a unique method to create highly-ordered colloidal microstructures in which we can control the amount of particles and their packing fraction. To this end, we evaporate colloidal dispersion drops from a special type of superhydrophobic microstructured surface, on which the drop remains in Cassie-Baxter state during the entire evaporative process. The remainders of the drop consist of a massive spherical cluster of the microspheres, with diameters ranging from a few tens up to several hundreds of microns. We present scaling arguments to show how the final particle packing fraction of these balls depends on the drop evaporation dynamics, particle size, and number of particles in the system.

Evaporation kinetics in the hanging drop method of protein crystal growth

Science.gov (United States)

Baird, James K.; Frieden, Richard W.; Meehan, E. J., Jr.; Twigg, Pamela J.; Howard, Sandra B.; Fowlis, William A.

1987-01-01

An engineering analysis of the rate of evaporation of solvent in the hanging drop method of protein crystal growth is presented; these results are applied to 18 different drop and well arrangements commonly encountered in the laboratory, taking into account the chemical nature of the salt, the drop size and shape, the drop concentration, the well size, the well concentration, and the temperature. It is found that the rate of evaporation increases with temperature, drop size, and with the salt concentration difference between the drop and the well. The evaporation possesses no unique half-life. Once the salt in the drop achieves about 80 percent of its final concentration, further evaporation suffers from the law of diminishing returns.

Visualization study of film drops produced by bubble bursting

International Nuclear Information System (INIS)

Ma Chao; Bo Hanliang

2012-01-01

The phenomenon that bubble bursting results in drops production is common in the steam generator of the nuclear power plant, and the fine drops generated by this way is one of the most important source of the drop entrainment in the vapor stream. The visualization experiment about the film drops produced by the bursting bubbles at a free water surface was studied using a high-speed video camera. The results show that the bubble cap breaks up in a single point, within the limits of bubble size in the experiment at present. The whole process can be distinguished into four successive stages: A primary inertial drainage, the bubble cap puncture at the foot or on the top, the film rolls-up and the liquid ring appearing with the hole expanding, and fine film drops emission under the effect of destabilization of a Rayleigh-Taylor type. The expression about the bubble radius and the film drops number is obtain by fitting the experiment data at the bubble radius range from 3-25 mm. The result trend agrees well with the previous work. (authors)

Pressure drop and friction factor correlations of supercritical flow

International Nuclear Information System (INIS)

Fang Xiande; Xu Yu; Su Xianghui; Shi Rongrong

2012-01-01

Highlights: ► Survey and evaluation of friction factor models for supercritical flow. ► Survey of experimental study of supercritical flow. ► New correlation of friction factor for supercritical flow. - Abstract: The determination of the in-tube friction pressure drop under supercritical conditions is important to the design, analysis and simulation of transcritical cycles of air conditioning and heat pump systems, nuclear reactor cooling systems and some other systems. A number of correlations for supercritical friction factors have been proposed. Their accuracy and applicability should be examined. This paper provides a comprehensive survey of experimental investigations into the pressure drop of supercritical flow in the past decade and a comparative study of supercritical friction factor correlations. Our analysis shows that none of the existing correlations is completely satisfactory, that there are contradictions between the existing experimental results and thus more elaborate experiments are needed, and that the tube roughness should be considered. A new friction factor correlation for supercritical tube flow is proposed based on 390 experimental data from the available literature, including 263 data of supercritical R410A cooling, 45 data of supercritical R404A cooling, 64 data of supercritical carbon dioxide (CO 2 ) cooling and 18 data of supercritical R22 heating. Compared with the best existing model, the new correlation increases the accuracy by more than 10%.

Dynamic calculation of the TN 28 VT package during 9 meter drop

International Nuclear Information System (INIS)

Goude, P.; Werle, J.; Martinotti, B.; Milet, L.

2004-01-01

International regulations require that a packaging for the transport of radioactive material has to withstand a 9-meter drop onto an unyielding target. It has to be shown that the containment of the radioactive contents is guaranteed. For some packagings the trunnions are not only used during handling and transport but serve also to absorb the energy of the shock during a 9-meter drop. An LS-DYNA3D model of an angular sector of a trunnion has been developed taking into account the rupture of the structure. The finite element analysis has been validated by successfully calibrating it with an actual drop test. The cask consists of a main cylindrical steel body equipped with thermal fins and additional neutron shielding encased in an external thin steel shell. During transport, two shock absorbers made of wood in a steel shell are attached to the top and the bottom of the main body. There are two pairs of trunnions to allow fixing and handling of the packaging. A comparative view of the actual and the simulated deformed structure shows that the residual deformation of the finite element analysis coincides almost perfectly with the one observed after the test. Comparing the acceleration, as a function of time, measured at the top and the bottom between the reduced scale model and the finite element model some differences are observed although the general shape of the signals is similar

Differential Gene Expression of Longan Under Simulated Acid Rain Stress.

Science.gov (United States)

Zheng, Shan; Pan, Tengfei; Ma, Cuilan; Qiu, Dongliang

2017-05-01

Differential gene expression profile was studied in Dimocarpus longan Lour. in response to treatments of simulated acid rain with pH 2.5, 3.5, and a control (pH 5.6) using differential display reverse transcription polymerase chain reaction (DDRT-PCR). Results showed that mRNA differential display conditions were optimized to find an expressed sequence tag (EST) related with acid rain stress. The potential encoding products had 80% similarity with a transcription initiation factor IIF of Gossypium raimondii and 81% similarity with a protein product of Theobroma cacao. This fragment is the transcription factor activated by second messenger substances in longan leaves after signal perception of acid rain.

Experimental Setup For Study of Drop Deformation In Air Flow

Directory of Open Access Journals (Sweden)

Basalaev Sergey

2017-01-01

Full Text Available Experimental study for study of deformation of drops in air flow is considered. Experimental setup includes a module for obtaining the drops, an air flow system and measuring system. Module for formation of drops is in the form of vertically arranged dropper with capillary with the possibility of formation of fixed drops. Air flow supply system comprises an air pump coupled conduit through a regulating valve with a cylindrical pipe, installed coaxially with dropper. The measuring system includes the video camera located with possibility of visualization of drop and the Pitot gage for measurement of flow rate of air located in the output section of branch pipe. This experimental setup allows to provide reliable and informative results of the investigation of deformation of drops in the air flow.

Satellite Formation during Coalescence of Unequal Size Drops

KAUST Repository

Zhang, F. H.

2009-03-12

The coalescence of a drop with a flat liquid surface pinches off a satellite from its top, in the well-known coalescence cascade, whereas the coalescence of two equally sized drops does not appear to leave such a satellite. Herein we perform experiments to identify the critical diameter ratio of two drops, above which a satellite is produced during their coalescence. We find that the critical parent ratio is as small as 1.55, but grows monotonically with the Ohnesorge number. The daughter size is typically about 50% of the mother drop. However, we have identified novel pinch-off dynamics close to the critical size ratio, where the satellite does not fully separate, but rather goes directly into a second stage of the coalescence cascade, thus generating a much smaller satellite droplet.

Electrostatic charging and levitation of helium II drops

International Nuclear Information System (INIS)

Niemela, J.J.

1997-01-01

Liquid Helium II drops, of diameter 1 mm or less, are charged with positive helium ions and subsequently levitated by static electric fields. Stable levitation was achieved for drops of order 100-150 micrometers in diameter. The suspended drops could be translated to arbitrary positions within the levitator using additional superimposed DC electric fields, and also could be made to oscillate stably about their average positions by means of an applied time-varying electric field. A weak corona discharge was used to produce the necessary ions for levitation. A novel superfluid film flow device, developed for the controlled deployment of large charged drops, is described. Also discussed is an adjustable electric fountain that requires only a field emission tip operating at modest potentials, and works in both Helium I and Helium II

Satellite Formation during Coalescence of Unequal Size Drops

KAUST Repository

Zhang, F. H.; Li, E. Q.; Thoroddsen, Sigurdur T

2009-01-01

The coalescence of a drop with a flat liquid surface pinches off a satellite from its top, in the well-known coalescence cascade, whereas the coalescence of two equally sized drops does not appear to leave such a satellite. Herein we perform experiments to identify the critical diameter ratio of two drops, above which a satellite is produced during their coalescence. We find that the critical parent ratio is as small as 1.55, but grows monotonically with the Ohnesorge number. The daughter size is typically about 50% of the mother drop. However, we have identified novel pinch-off dynamics close to the critical size ratio, where the satellite does not fully separate, but rather goes directly into a second stage of the coalescence cascade, thus generating a much smaller satellite droplet.

Two secondary drops

Indian Academy of Sciences (India)

Figure shows formation of two secondary drops of unequal size and their merger. The process is same as the earlier process until t= 0.039 Tc with necking occurring at two places, one at the bottom of the column and the other at the middle. The necking at the middle of the liquid column is due to Raleigh instability.

Interfacial Instabilities in Evaporating Drops

Science.gov (United States)

Moffat, Ross; Sefiane, Khellil; Matar, Omar

2007-11-01

We study the effect of substrate thermal properties on the evaporation of sessile drops of various liquids. An infra-red imaging technique was used to record the interfacial temperature. This technique illustrates the non-uniformity in interfacial temperature distribution that characterises the evaporation process. Our results also demonstrate that the evaporation of methanol droplets is accompanied by the formation of wave-trains in the interfacial temperature field; similar patterns, however, were not observed in the case of water droplets. More complex patterns are observed for FC-72 refrigerant drops. The effect of substrate thermal conductivity on the structure of the complex pattern formation is also elucidated.

Rain drop size densities over land and over sea

Science.gov (United States)

Bumke, Karl

2010-05-01

A detailed knowledge of rain drop size densities is an essential presumption with respect to remote sensing of precipitation. Since maritime and continental aerosol is significantly different yielding to differences in cloud drop size densities, maritime and continental rain drop size densities may be different, too. In fact only a little is known about differences in rain drop size densities between land and sea due to a lack of suitable data over the sea. To fill in this gap measurements were performed during the recent 10 years at different locations in Germany and on board of research vessels over the Baltic Sea, the North Sea, Atlantic, Indian, and Pacific Ocean. Measurements were done by using an optical disdrometer (ODM 470, Großklaus et al., 1998), which is designed especially to perform precipitation measurements on moving ships and under high wind speeds. Temporal resolution of measurements is generally 1 minute, total number of time series is about 220000. To investigate differences in drop size densities over land and over sea measurements have been divided into four classes on the basis of prevailing continental or maritime influence: land measurements, coastal measurements, measurements in areas of semi-enclosed seas, and open sea measurements. In general differences in drop size densities are small between different areas. A Kolmogoroff Smirnoff test does not give any significant difference between drop size densities over land, coastal areas, semi-enclosed, and open seas at an error rate of 5%. Thus, it can be concluded that there are no systematic differences between maritime and continental drop size densities. The best fit of drop size densities is an exponential decay curve, N(D ) = 6510m -3mm -1mm0.14h- 0.14×R-0.14×exp(- 4.4mm0.25h-0.25×R- 0.25×D mm -1), it is estimated by using the method of least squares. N(D) is the drop size density normalized by the resolution of the optical disdrometer, D the diameter of rain drops in mm, and R the

Ready-made allogeneic ABO-specific serum eye drops

DEFF Research Database (Denmark)

Harritshøj, Lene Holm; Nielsen, Connie; Ullum, Henrik

2014-01-01

serum treatment. CONCLUSION: Ready-made ABO-identical allogeneic serum eye drops were straightforwardly produced, quality-assured and registered as a safe standard blood product for the treatment of certain cases of severe dry eye disease. Therapeutic efficacy was comparable to previous reports......PURPOSE: To overcome problems and delays of the preparation of autologous serum eye drops, a production line of ABO-specific allogeneic serum eye drops from male blood donors was set up in a blood bank. Feasibility, clinical routine, safety and efficacy were evaluated in a cohort of patients...

Dropped Ceiling

OpenAIRE

Tabet, Rayyane

2012-01-01

On December 2nd 1950 the first drop of Saudi oil arrived to Lebanon via the newly constructed Trans-Arabian Pipeline, the world's longest pipeline and the largest American private investment in a foreign land. The 30inch wide structure which spanned 1213 kilometers passing through Saudi Arabia, Jordan, and Syria to end in Lebanon had required 3 years of planning and surveying, 2 years of installation, the fabrication of 256,000 tons of steel tubes, the employment of 30,000 workers, the ratifi...

Eye-Drops for Activation of DREADDs

Directory of Open Access Journals (Sweden)

William T. Keenan

2017-11-01

Full Text Available Designer Receptors Exclusively Activated by Designer Drugs (DREADDs are an important tool for modulating and understanding neural circuits. Depending on the DREADD system used, DREADD-targeted neurons can be activated or repressed in vivo following a dose of the DREADD agonist clozapine-N-oxide (CNO. Because DREADD experiments often involve behavioral assays, the method of CNO delivery is important. Currently, the most common delivery method is intraperitoneal (IP injection. IP injection is both a fast and reliable technique, but it is painful and stressful particularly when many injections are required. We sought an alternative CNO delivery paradigm, which would retain the speed and reliability of IP injections without being as invasive. Here, we show that CNO can be effectively delivered topically via eye-drops. Eye-drops robustly activated DREADD-expressing neurons in the brain and peripheral tissues and does so at the same dosages as IP injection. Eye-drops provide an easier, less invasive and less stressful method for activating DREADDs in vivo.

Drop test facility available to private industry

International Nuclear Information System (INIS)

Shappert, L.B.; Box, W.D.

1983-01-01

In 1978, a virtually unyielding drop test impact pad was constructed at Oak Ridge National Laboratory's (ORNL's) Tower Shielding Facility (TSF) for the testing of heavy shipping containers designed for transporting radioactive materials. Because of the facility's unique capability for drop-testing large, massive shipping packages, it has been identified as a facility which can be made available for non-DOE users

Measurement of an Evaporating Drop on a Reflective Substrate

Science.gov (United States)

Chao, David F.; Zhang, Nengli

2004-01-01

A figure depicts an apparatus that simultaneously records magnified ordinary top-view video images and laser shadowgraph video images of a sessile drop on a flat, horizontal substrate that can be opaque or translucent and is at least partially specularly reflective. The diameter, contact angle, and rate of evaporation of the drop as functions of time can be calculated from the apparent diameters of the drop in sequences of the images acquired at known time intervals, and the shadowgrams that contain flow patterns indicative of thermocapillary convection (if any) within the drop. These time-dependent parameters and flow patterns are important for understanding the physical processes involved in the spreading and evaporation of drops. The apparatus includes a source of white light and a laser (both omitted from the figure), which are used to form the ordinary image and the shadowgram, respectively. Charge-coupled-device (CCD) camera 1 (with zoom) acquires the ordinary video images, while CCD camera 2 acquires the shadowgrams. With respect to the portion of laser light specularly reflected from the substrate, the drop acts as a plano-convex lens, focusing the laser beam to a shadowgram on the projection screen in front of CCD camera 2. The equations for calculating the diameter, contact angle, and rate of evaporation of the drop are readily derived on the basis of Snell s law of refraction and the geometry of the optics.

Evaluation of finite element codes for demonstrating the performance of radioactive material packages in hypothetical accident drop scenarios

International Nuclear Information System (INIS)

Tso, C.F.; Hueggenberg, R.

2004-01-01

Drop testing and analysis are the two methods for demonstrating the performance of packages in hypothetical drop accident scenarios. The exact purpose of the tests and the analyses, and the relative prominence of the two in the license application, may depend on the Competent Authority and will vary between countries. The Finite Element Method (FEM) is a powerful analysis tool. A reliable finite element (FE) code when used correctly and appropriately, will allow a package's behaviour to be simulated reliably. With improvements in computing power, and in sophistication and reliability of FE codes, it is likely that FEM calculations will increasingly be used as evidence of drop test performance when seeking Competent Authority approval. What is lacking at the moment, however, is a standardised method of assessing a FE code in order to determine whether it is sufficiently reliable or pessimistic. To this end, the project Evaluation of Codes for Analysing the Drop Test Performance of Radioactive Material Transport Containers, funded by the European Commission Directorate-General XVII (now Directorate-General for Energy and Transport) and jointly performed by Arup and Gesellschaft fuer Nuklear-Behaelter mbH, was carried out in 1998. The work consisted of three components: Survey of existing finite element software, with a view to finding codes that may be capable of analysing drop test performance of radioactive material packages, and to produce an inventory of them. Develop a set of benchmark problems to evaluate software used for analysing the drop test performance of packages. Evaluate the finite element codes by testing them against the benchmarks This paper presents a summary of this work

Evaluation of finite element codes for demonstrating the performance of radioactive material packages in hypothetical accident drop scenarios

Energy Technology Data Exchange (ETDEWEB)

Tso, C.F. [Arup (United Kingdom); Hueggenberg, R. [Gesellschaft fuer Nuklear-Behaelter mbH (Germany)

2004-07-01

Drop testing and analysis are the two methods for demonstrating the performance of packages in hypothetical drop accident scenarios. The exact purpose of the tests and the analyses, and the relative prominence of the two in the license application, may depend on the Competent Authority and will vary between countries. The Finite Element Method (FEM) is a powerful analysis tool. A reliable finite element (FE) code when used correctly and appropriately, will allow a package's behaviour to be simulated reliably. With improvements in computing power, and in sophistication and reliability of FE codes, it is likely that FEM calculations will increasingly be used as evidence of drop test performance when seeking Competent Authority approval. What is lacking at the moment, however, is a standardised method of assessing a FE code in order to determine whether it is sufficiently reliable or pessimistic. To this end, the project Evaluation of Codes for Analysing the Drop Test Performance of Radioactive Material Transport Containers, funded by the European Commission Directorate-General XVII (now Directorate-General for Energy and Transport) and jointly performed by Arup and Gesellschaft fuer Nuklear-Behaelter mbH, was carried out in 1998. The work consisted of three components: Survey of existing finite element software, with a view to finding codes that may be capable of analysing drop test performance of radioactive material packages, and to produce an inventory of them. Develop a set of benchmark problems to evaluate software used for analysing the drop test performance of packages. Evaluate the finite element codes by testing them against the benchmarks This paper presents a summary of this work.

Dynamic Impact Analysis of Bagless Transfer System 3013 Can in Drops at Various Inclination Angles

International Nuclear Information System (INIS)

Gong, C.

2001-01-01

The purpose of this analysis is to provide rational judgment for the most pernicious impact angle of dropping. A numerical simulation method, finite element analysis, is adopted for this study. The general-purpose finite element analysis code, ABAQUS(R) [HKS, 1998], facilitates the numerical computation. The geometrical finite element modeling is developed with the software PATRAN(R) [MSC, 1999]. The finite element code ABAQUS(R)has been verified according to the QA plans

A simulation study of gene-by-environment interactions in GWAS implies ample hidden effects

Science.gov (United States)

Marigorta, Urko M.; Gibson, Greg

2014-01-01

The switch to a modern lifestyle in recent decades has coincided with a rapid increase in prevalence of obesity and other diseases. These shifts in prevalence could be explained by the release of genetic susceptibility for disease in the form of gene-by-environment (GxE) interactions. Yet, the detection of interaction effects requires large sample sizes, little replication has been reported, and a few studies have demonstrated environmental effects only after summing the risk of GWAS alleles into genetic risk scores (GRSxE). We performed extensive simulations of a quantitative trait controlled by 2500 causal variants to inspect the feasibility to detect gene-by-environment interactions in the context of GWAS. The simulated individuals were assigned either to an ancestral or a modern setting that alters the phenotype by increasing the effect size by 1.05–2-fold at a varying fraction of perturbed SNPs (from 1 to 20%). We report two main results. First, for a wide range of realistic scenarios, highly significant GRSxE is detected despite the absence of individual genotype GxE evidence at the contributing loci. Second, an increase in phenotypic variance after environmental perturbation reduces the power to discover susceptibility variants by GWAS in mixed cohorts with individuals from both ancestral and modern environments. We conclude that a pervasive presence of gene-by-environment effects can remain hidden even though it contributes to the genetic architecture of complex traits. PMID:25101110

Tiller classes on signalgrass pasture according to the cattle droppings position

Directory of Open Access Journals (Sweden)

Manoel Eduardo Rozalino Santos

2010-01-01

Full Text Available The experiment was carried out aiming to investigate the influence of natural deposition of cattle droppings on population density of several classes of tillers on the Brachiaria decumbens Stapf. cv. Basilisk pasture managed under continuous stocking. Two places on the same pasture were evaluated: one near (immediately adjacent and one far, about 1.0 m, from the cattle droppings. Randomized block design with three repetitions was used. Tillers were classified according to the developmental stage, growth origin, defoliation rate and length. The number of vegetative tillers was higher (P<0.05 at the place that was far from the droppings (1.851 perfilhos/ m2 than at the one near them (848 perfilhos/m2. The number of reproductive tillers was higher (P<0.05 at the place near the droppings. Being near or far from the droppings showed no impact on the population density of dead tillers (584 perfilhos/m2 mean. The number of basal tiller and aerial tillers were higher (P<0.05 at the place far from the droppings, when collated to the place near the droppings. The population densities of both defoliated tillers and tillers without shoot meristem, far from the droppings, were higher (P<0.05, while the population density of nondefoliated tillers was higher (P<0.05 at the place found near the droppings. The shortest tillers were common (P<0.05 at the place far from the droppings, while the highest were frequently found (P<0.05 near the droppings. In the B. decumbens pasture under continuous stocking, deposition of droppings by cattle changes the spatial distribution of tillers categories and thus constitutes a factor causing spatial heterogeneity of vegetation.

Chemical-Reaction-Controlled Phase Separated Drops: Formation, Size Selection, and Coarsening

Science.gov (United States)

Wurtz, Jean David; Lee, Chiu Fan

2018-02-01

Phase separation under nonequilibrium conditions is exploited by biological cells to organize their cytoplasm but remains poorly understood as a physical phenomenon. Here, we study a ternary fluid model in which phase-separating molecules can be converted into soluble molecules, and vice versa, via chemical reactions. We elucidate using analytical and simulation methods how drop size, formation, and coarsening can be controlled by the chemical reaction rates, and categorize the qualitative behavior of the system into distinct regimes. Ostwald ripening arrest occurs above critical reaction rates, demonstrating that this transition belongs entirely to the nonequilibrium regime. Our model is a minimal representation of the cell cytoplasm.

Hypothetical accident conditions, free drop and thermal tests: Specification 6M

International Nuclear Information System (INIS)

Blankenship, R.W.

1980-05-01

The 30 gallon Specification 6M shipping container with rolled-top food pack cans as inner containers is evaluated under conditions required by 10 CFR 71.42. One kilogram of depleted uranium as UO 2 was packaged in each of the inner containers. After completion of a free drop test and a simulated thermal test, the maximum observed leakage of UO 2 for the following week was 3.2 μg. This leakage is well below the allowable leakage per week for most plutonium isotopic mixtures. Using the examples provided, any plutonium isotopic mixture can be easily compared with the allowable leakage per week. Test conditions and results are reported

Investigation of the fragmentation of molten metals dropped into cold water

International Nuclear Information System (INIS)

Shiralkar, G.S.

1976-11-01

The physical mechanism by which small quantities of molten metal fragment extensively when dropped into a pool of cold water was investigated. Since this subject has been the focus of considerable research in the past, some of the more prominent theories are briefly discussed. Experiments were conducted dropping small solid spheres at a high temperature instead of molten metal drops, and indicate a significant difference from the latter. Several hypotheses were proposed based on the hydrodynamics of the molten drop and tested analytically. The theory that the drop fragmentation is caused by the violent release of dissolved gas from within the drop was investigated experimentally and lead to the conclusion that tin fragmentation probably does not occur in this way. It is felt that a calculation of the dynamics of the vapor film that would be expected to surround the hot drop is needed. This calculation was not performed but several suggestions and estimates have been made. It would seem that the possibility of metal fragmentation by rapid vaporization of water entrapped within the metal drop is well worth investigating

ITER FW cooling by a flat channel, adapted to low flow rate and high pressure drop

International Nuclear Information System (INIS)

Ovchinnikov, I.B.; Bondarchuk, D.E.; Gervash, A.A.; Glazunov, D.A.; Komarov, A.O.; Kuznetsov, V.E.; Mazul, I.V.; Rulev, R.V.; Yablokov, N.A.

2011-01-01

Highlights: ► ITER FW cooling: pressure drop quotation must be assigned according to thermal load. ► Flat channel solutions with wide range (1:500) of hydraulic resistivity are presented. ► Simulations in Ansys CFX were carried out for presented designs. ► Usage of pressure drop quotation significantly reduces surface temperature. ► Experiments in TSEFEY-M facility confirm simulations. - Abstract: Application of hypervapotron (HV) to cool in-vessel components of ITER – divertor and first wall (FW) – is characterized by the same design load (5 MW/m 2 ) but water flow rate for FW is 8–9 times (almost by order!) less for parallel feeding elements so it seems it would be better to use other design. Several variants of a flat channel design different from HV are suggested that enable to adapt a channel to pressure quota up to 1 MPa and higher. A main feature of the suggested variants is a spiral or multi-spiral stream (flat multi spiral––FMS) that improves heat rejection and can be obtained both by exciting of such mode and forced by channel geometry. Comparison of the variants was carried out in simulations (Ansys CFX) as well as in experiments on the TSEFEY-M facility with electron-beam gun. It is shown that excitation of a spiral stream in a channel significantly reduces a temperature of a loaded surface of a channel. Miniature thermocouples were used to measure temperature near the surface.

Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding

Science.gov (United States)

Lin, Po-Cheng; I, Lin

2016-02-01

We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

Drop deformation and breakup in a partially filled horizontal rotating cylinder

Science.gov (United States)

White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

2014-11-01

Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

STUDY ON SOFTENING AND DROPPING PROPERTIES OF METALIZED BURDEN INSIDE BLAST FURNACE

Directory of Open Access Journals (Sweden)

Bi-yang Tuo

2014-12-01

Full Text Available The inferences of burden metallization rate on softening-melting dropping properties were investigated through softening-melting dropping test of three kinds of metalized burden pressure drop. The results indicated that the softeningmelting temperature interval of pre-reduction mixed burden is bigger than primeval mixed burden, the melting interval narrow with the rise of metallization rate of ferric burden as well as dropping temperature interval. The average pressure drop, maximum pressure drop and softening-melting dropping properties eigenvalue decrease with the rise of metallization rate of ferric burden. Besides, the dropping temperature of burden reduces with the rise of carbon content of molten iron. The combination high metalized burden and higher carbon content of molten iron is benefit to decreasing thickness of cohesive zone and improve permeability of cohesive zone.

Ultrasonic defect sizing using decibel drop methods. III

International Nuclear Information System (INIS)

Mills, C.; Goszczynski, J.; Mitchell, A.B.

1988-03-01

An earlier study on the use of ultrasonic decibel drop sizing methods for determining the length and vertical extent of flaws in welded steel sections was based on the scanning of machined flaws and fabrication flaws. The present study utilized the techniques developed to perform a similar study of the type of flaws expected to develop during service (e.g. fatigue cracks). The general findings are that: a) the use of decibel drops of less than 14 dB generally undersize the length of fatigue cracks; and b) the use of decibel drop methods to determine vertical extent is questionable

Naturally Occurring Egg Drop Syndrome Infection in Turkeys

Directory of Open Access Journals (Sweden)

Z. Biđin

2007-01-01

Full Text Available A decrease in the egg quality, production, fertility and hatchability without serious clinical signs of illness was recorded in turkey fl ocks in Croatia at the beginning of 2002. It was assumed that the egg drop syndrome virus might be one of the etiological agents responsible for the abnormalities in the egg production. The systematic serological monitoring, using a haemagglutination inhibition test, showed that the antibodies to the egg drop syndrome virus existed in 94.4 and 55.1% of the sera analysed in 2002 and 2003, respectively. The haemagglutination inhibition titres ranged from 16 to 128. The sera samples were randomly collected from 11 - to 46-week-old hens from the affected fl ocks. The serological evidence of the egg drop syndrome virus infection was confirmed by detection of the presence of the virus genome in the turkey sera by the polymerase chain reaction. Vaccination of the 18- and 25-week-old turkey hens against the egg drop syndrome virus started in March 2003. After this period, the presence of antibodies to the egg drop syndrome virus (the haemagglutination inhibition titres between 16 and 256 was found in 96.7% of the analysed sera, while the egg production reached normal or higher values for the Nicholas hybrid line of turkeys.

Role of Structural Asymmetry in Controlling Drop Spacing in Microfluidic Ladder Networks

Science.gov (United States)

Wang, William; Maddala, Jeevan; Vanapalli, Siva; Rengasamy, Raghunathan

2012-02-01

Manipulation of drop spacing is crucial to many processes in microfluidic devices including drop coalescence, detection and storage. Microfluidic ladder networks ---where two droplet-carrying parallel channels are connected by narrow bypass channels through which the motion of drops is forbidden---have been proposed as a means to control relative separation between pairs of drops. Prior studies in microfluidic ladder networks with vertical bypasses, which possess fore-aft structural symmetry, have revealed that pairs of drops can only undergo reduction in drop spacing at the ladder exit. We investigate the dynamics of drops in microfluidic ladder networks with both vertical and slanted bypasses. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative spacing between drops, enabling them to contract, synchronize, expand or even flip at the ladder exit. Our experiments confirm all the behaviors predicted by theory. Numerical analysis further shows that ladders containing several identical bypasses can only linearly transform the input drop spacing. Finally, we find that ladders with specific combinations of vertical and slanted bypasses can generate non-linear transformation of input drop spacing, despite the absence of drop decision-making events at the bypass junctions.

High-precision drop shape analysis on inclining flat surfaces: introduction and comparison of this special method with commercial contact angle analysis.

Science.gov (United States)

Schmitt, Michael; Heib, Florian

2013-10-07

Drop shape analysis is one of the most important and frequently used methods to characterise surfaces in the scientific and industrial communities. An especially large number of studies, which use contact angle measurements to analyse surfaces, are characterised by incorrect or misdirected conclusions such as the determination of surface energies from poorly performed contact angle determinations. In particular, the characterisation of surfaces, which leads to correlations between the contact angle and other effects, must be critically validated for some publications. A large number of works exist concerning the theoretical and thermodynamic aspects of two- and tri-phase boundaries. The linkage between theory and experiment is generally performed by an axisymmetric drop shape analysis, that is, simulations of the theoretical drop profiles by numerical integration onto a number of points of the drop meniscus (approximately 20). These methods work very well for axisymmetric profiles such as those obtained by pendant drop measurements, but in the case of a sessile drop onto real surfaces, additional unknown and misunderstood effects on the dependence of the surface must be considered. We present a special experimental and practical investigation as another way to transition from experiment to theory. This procedure was developed to be especially sensitive to small variations in the dependence of the dynamic contact angle on the surface; as a result, this procedure will allow the properties of the surface to be monitored with a higher precession and sensitivity. In this context, water drops onto a 111 silicon wafer are dynamically measured by video recording and by inclining the surface, which results in a sequence of non-axisymmetric drops. The drop profiles are analysed by commercial software and by the developed and presented high-precision drop shape analysis. In addition to the enhanced sensitivity for contact angle determination, this analysis technique, in

LTPS-TFT Pixel Circuit Compensating for TFT Threshold Voltage Shift and IR-Drop on the Power Line for AMOLED Displays

Directory of Open Access Journals (Sweden)

Ching-Lin Fan

2012-01-01

Full Text Available We propose a new pixel design for the active matrix organic light-emitting diode (AMOLED using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs. The proposed pixel is composed of four switching TFTs, one driving TFT (DTFT, and one capacitor. The simulation results are performed by AIM-SPICE software. The error rate of OLED output current with (threshold voltage variation (0.3 V and power line drop by 1 V are improved to about 1.67% and 15%, respectively. Thus, the proposed pixel circuit can successfully overcome drawbacks suffered from DTFT threshold voltage deviation and IR-drop on power line.

Superheated drop, open-quotes Bubbleclose quotes, dosimeters

International Nuclear Information System (INIS)

Harper, M.J.; Lindler, K.W.; Nelson, M.E.; Johnson, T.L.; Jones, C.R.; Rabovsky, J.L.; Rao, N.; Kerschner, H.F.; Reil, G.K.; Schwartz, R.B.

1991-01-01

Superheated Drop Dosimeters (SDD) offer a sensitive, immediate measure of the neutron dose equivalent, but their dynamic range is limited and their response varies with temperature, pressure, and vibration. They contain thousands of superheated liquid drops in a stabilizing matrix. High linear energy transfer (LET) radiation triggers vaporization of the drops into visible bubbles. If the matrix is a liquid, the bubbles slowly rise, and the number present indicates the dose rate. Dose may be measured by displacement of the matrix, or by counting the sounds of vaporization. If the matrix is a gel, the bubbles are fixed, and their number is proportional to the dose equivalent. Our research has focused on modeling and elimination of the environmental response, extension of the dynamic range, and tests and evaluations of prototype devices

Fundamentals and applications of fast micro-drop impact

NARCIS (Netherlands)

Visser, C.W.

2014-01-01

3D-printing, biofabrication, diesel engines, and spray cleaning all depend on controlled drop impact. However, surprisingly, these drops have received scarce attention so far. This is mainly due to their small size and high impact velocity, which makes visualizing the impact a challenge. This thesis

Different behavioural responses of larval fish under microgravity and morphological correlates in the inner ear -a drop-tower study

Science.gov (United States)

Hilbig, Reinhard; Weigele, Jochen; Knie, Miriam; Hendrik Anken, Ralf

In vertebrates altered gravitational environments such as weightlessness (microgravity, g) in-duce changes in central and peripheral interpretation of sensory input leading to alterations in motor behaviour (e.g., intersensory-conflicts) including space motion sickness, a sensory motor kinetosis normally accompanied by malaise and vomiting. In fish it had been repeatedly shown that some fish of a given batch reveal motion sickness after transition from hypergravity (pull up) to microgravity microgravity in the course of parabolic aircraft flight (PF= low quality microgravity = LQM) experiments or in the case of drop tower experiments at ZARM (Bre-men) immediately after release of the capsule. The drop-tower studies were designed to further elucidate the role of otolith asymmetry concerning an individually different susceptibility to kinetoses. In order to test, whether the differing results between the PF and the drop-tower experiment were based exclusively on the differing quality of diminished gravity, or, if further parameters of the PF and the drop-tower environment need to be taken into consideration (e.g., vibrations and changing accelerations during PFs or the brisk compression of the drop-capsule at its release) to explain the differing results, drop-tower flights were performed at a series of increasing accelerations, by centrifugation in the drop capsule. This simulation of "differ-ent micro" gravity was carried out in housing larval cichlid fish (Oreochromis mossambicus) within a centrifuge at high quality microgravity 10-6g (HQM) and 10-4g to 0.3g during the drop-tower flights. The percentual ratios of the swimming behaviour at drop-tower changed significantly according to the increasing acceleration force of the centrifuge during flight. With increasing acceleration (= detectable gravity for fish) the relative proportion of looping an d spinning movements decreased in favour of normal swimming an at 0.3g nearly no kinetotic behaviour was observed. When

Contact angle of sessile drops in Lennard-Jones systems.

Science.gov (United States)

Becker, Stefan; Urbassek, Herbert M; Horsch, Martin; Hasse, Hans

2014-11-18

Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.

Drop-out probabilities of IrisPlex SNP alleles

DEFF Research Database (Denmark)

Andersen, Jeppe Dyrberg; Tvedebrink, Torben; Mogensen, Helle Smidt

2013-01-01

In certain crime cases, information about a perpetrator's phenotype, including eye colour, may be a valuable tool if no DNA profile of any suspect or individual in the DNA database matches the DNA profile found at the crime scene. Often, the available DNA material is sparse and allelic drop-out...... of true alleles is possible. As part of the validation of the IrisPlex assay in our ISO17025 accredited, forensic genetic laboratory, we estimated the probability of drop-out of specific SNP alleles using 29 and 30 PCR cycles and 25, 50 and 100 Single Base Extension (SBE) cycles. We observed no drop-out...... when the amount of DNA was greater than 125 pg for 29 cycles of PCR and greater than 62 pg for 30 cycles of PCR. With the use of a logistic regression model, we estimated the allele specific probability of drop-out in heterozygote systems based on the signal strength of the observed allele...

Probabilistic Risk Assessment of Cask Drop Accident during On-site Spent Nuclear Fuel Transportation

Energy Technology Data Exchange (ETDEWEB)

Ham, Jae Hyun; Christian, Robby; Momani, Belal Al; Kang, Hyun Gook [KAERI, Daejeon (Korea, Republic of)

2016-05-15

There are two ways to transfer the SNF from a site to other site, one is land transportation and the other is maritime transportation. Maritime transportation might be used because this way uses more safe route which is far from populated area. The whole transportation process can be divided in two parts: transferring the SNF between SNP and wharf in-Nuclear Power Plant (NPP) site by truck, and transferring the SNF from the wharf to the other wharf by ship. In this research, on-site SNF transportation between SNP and wharf was considered. Two kinds of single accident can occur during this type of SNF transportation, impact and fire, caused by internal events and external events. In this research, PRA of cask drop accident during onsite SNF transportation was done, risk to a person (mSv/person) from a case with specific conditions was calculated. In every 11 FEM simulation drop cases, FDR is 1 even the fuel assemblies are located inside of the cask. It is a quite larger value for all cases than the results with similar drop condition from the reports which covers the PRA on cask storage system. Because different from previous reports, subsequent impact was considered. Like in figure 8, accelerations which are used to calculate the FDR has extremely higher values in subsequent impact than the first impact for all SNF assemblies.

DropBot: An open-source digital microfluidic control system with precise control of electrostatic driving force and instantaneous drop velocity measurement

International Nuclear Information System (INIS)

Fobel, Ryan; Fobel, Christian; Wheeler, Aaron R.

2013-01-01

We introduce DropBot: an open-source instrument for digital microfluidics (http://microfluidics.utoronto.ca/dropbot). DropBot features two key functionalities for digital microfluidics: (1) real-time monitoring of instantaneous drop velocity (which we propose is a proxy for resistive forces), and (2) application of constant electrostatic driving forces through compensation for amplifier-loading and device capacitance. We anticipate that this system will enhance insight into failure modes and lead to new strategies for improved device reliability, and will be useful for the growing number of users who are adopting digital microfluidics for automated, miniaturized laboratory operation.

Magnetohydrodynamic pressure drop in a quickly changing magnetic field

International Nuclear Information System (INIS)

Xu, Z.Y.; Chen, J.M.; Qian, J.P.; Jiang, W.H.; Pan, C.J.; Li, W.Z.

1995-01-01

The magnetohydrodynamic (MHD) pressure drop of 22 Na 78 K flow in a circular duct was measured under a quickly changing magnetic field. The MHD pressure drop reduced with time as the magnetic field strength decreased. However, the dimensionless pressure drop gradient varied with the interaction parameter and had a higher value in the middle of the range of values of the interaction parameter. Therefore, a quickly changing magnetic field is harmful to the structural material in a liquid metal self-cooled blanket of a fusion reactor, since the greater pressure drop gradient may cause a larger stress in the blanket. This is even more harmful if the magnetic field strength decreases very quickly or its distribution in space is greatly non-uniform. (orig.)

Hydrodynamic shrinkage of liquid CO2 Taylor drops in a straight microchannel

Science.gov (United States)

Qin, Ning; Wen, John Z.; Ren, Carolyn L.

2018-03-01

Hydrodynamic shrinkage of liquid CO2 drops in water under a Taylor flow regime is studied using a straight microchannel (length/width ~100). A general form of a mathematical model of the solvent-side mass transfer coefficient (k s) is developed first. Based on formulations of the surface area (A) and the volume (V) of a general Taylor drop in a rectangular microchannel, a specific form of k s is derived. Drop length and speed are experimentally measured at three specified positions of the straight channel, namely, immediately after drop generation (position 1), the midpoint of the channel (position 2) and the end of the channel (position 3). The reductions of drop length (L x , x  =  1, 2, 3) from position 1 to 2 and down to 3 are used to quantify the drop shrinkage. Using the specific model, k s is calculated mainly based on L x and drop flowing time (t). Results show that smaller CO2 drops produced by lower flow rate ratios ({{Q}LC{{O2}}}/{{Q}{{H2}O}} ) are generally characterized by higher (nearly three times) k s and Sherwood numbers than those produced by higher {{Q}LC{{O2}}}/{{Q}{{H2}O}} , which is essentially attributed to the larger effective portion of the smaller drop contributing in the mass transfer under same levels of the flowing time and the surface-to-volume ratio (~104 m-1) of all drops. Based on calculated pressure drops of the segmented flow in microchannel, the Peng-Robinson equation of state and initial pressures of drops at the T-junction in experiments, overall pressure drop (ΔP t) in the straight channel as well as the resulted drop volume change are quantified. ΔP t from position 1-3 is by average 3.175 kPa with a ~1.6% standard error, which only leads to relative drop volume changes of 0.3‰ to 0.52‰.

Hydrodynamic shrinkage of liquid CO2 Taylor drops in a straight microchannel.

Science.gov (United States)

Qin, Ning; Wen, John; Ren, Carolyn L

2018-01-16

Hydrodynamic shrinkage of liquid CO2 drops in water under a Taylor flow regime is studied using a straight microchannel (length/width ~ 100). A general form of a mathematical model of the solvent-side mass transfer coefficient (ks) is developed first. Based on formulations of the surface area (A) and the volume (V) of a general Taylor drop in a rectangular microchannel, a specific form of ks is derived. Drop length and speed are experimentally measured at three specified positions of the straight channel, namely, immediately after drop generation (position 1), the midpoint of the channel (position 2) and the end of the channel (position 3). The reductions of drop length (Lx, x = 1, 2, 3) from position 1 to 2 and down to 3 are used to quantify the drop shrinkage. Using the specific model, ks is calculated mainly based on Lx and drop flowing time (t). Results show that smaller CO2 drops produced by lower flow rate ratios (QLCO2/QH2O) are generally characterized by higher (nearly three times) ks and Sherwood numbers than those produced by higher QLCO2/QH2O, which is essentially attributed to the larger effective portion of the smaller drop contributing in the mass transfer under same levels of the flowing time and the surface-to-volume ratio (~ 104 m-1) of all drops. Based on calculated pressure drops of the segmented flow in microchannel, the Peng-Robinson equation of state (EOS) and initial pressures of drops at the T-junction in experiments, overall pressure drop (ΔPt) in the straight channel as well as the resulted drop volume change are quantified. ΔPt from position 1 to 3 is by average 3.175 kPa with a ~1.6% standard error, which only leads to relative drop volume changes of 0.3‰ to 0.52‰. © 2018 IOP Publishing Ltd.

Impact of ultra-viscous drops: air-film gliding and extreme wetting

KAUST Repository

Langley, Kenneth

2017-01-23

A drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary-viscous balance. The spreading velocity of the wetting spots is independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.

Pressure drop in flashing flow through obstructions

International Nuclear Information System (INIS)

Weinle, M.E.; Johnston, B.S.

1985-01-01

An experiment was designed to investigate the pressure drop for flashing flow across obstructions of different geometries at various flow rates. Tests were run using two different orifices to determine if the two-phase pressure drop could be characterized by the single phase loss coefficient and the general behavior of the two-phase multiplier. For the geometries studied, it was possible to correlate the multiplier in a geometry-independent fashion

Pressure drop in T's in concentric ducts

International Nuclear Information System (INIS)

Shock, R.A.W.

1983-02-01

A set of experiments has been carried out to measure the pressure drop characteristics of single-phase flow in dividing and joining right-angled T's in a concentric ducting system. These have been compared with measured pressure drops in a simple round tube system. In most tests with the concentric system the number of velocity heads lost is either similar to, or more than, the value for the round tubes. (author)

Falling drops skating on a film of air

Science.gov (United States)

Rubinstein, Shmuel

2012-02-01

When a raindrop hits a window, the surface immediately becomes wet as the water spreads. Indeed, this common observation of a drop impacting a surface is ubiquitous in our everyday experience. I will show that the impact of a drop on a surface is a much richer, more complex phenomenon than our simple experience may suggests: To completely wet the surface the drop must first expel all the air beneath it; however, this does not happened instantaneously. Instead, a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the fluid spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate laterally outward at strikingly high velocities. Simultaneously, the wetting fluid spreads inward at a much slower velocity, trapping a bubble of air within the drop. However, these events occur at diminutive length scales and fleeting time scales; therefore, to visualize them we develop new imaging modalities that are sensitive to the behavior right at the surface and that have time resolution superior to even the very fastest cameras. These imaging techniques reveal that the ultimate wetting of the surface occurs through a completely new mechanism, the breakup of the thin film of air through a spinodal like dewetting process that breaks the cylindrical symmetry of the impact and drives an anomalously rapid spreading of a wetting front. These results are in accord with recent theoretical predictions and challenge the prevailing paradigm in which contact between the liquid and solid occurs immediately, and spreading is dominated by the dynamics of a single contact line.

Water Penetration through a Superhydrophobic Mesh During a Drop Impact

Science.gov (United States)

Ryu, Seunggeol; Sen, Prosenjit; Nam, Youngsuk; Lee, Choongyeop

2017-01-01

When a water drop impacts a mesh having submillimeter pores, a part of the drop penetrates through the mesh if the impact velocity is sufficiently large. Here we show that different surface wettability, i.e., hydrophobicity and superhydrophobicity, leads to different water penetration dynamics on a mesh during drop impact. We show, despite the water repellence of a superhydrophobic surface, that water can penetrate a superhydrophobic mesh more easily (i.e., at a lower impact velocity) over a hydrophobic mesh via a penetration mechanism unique to a superhydrophobic mesh. On a superhydrophobic mesh, the water penetration can occur during the drop recoil stage, which appears at a lower impact velocity than the critical impact velocity for water penetration right upon impact. We propose that this unique water penetration on a superhydrophobic mesh can be attributed to the combination of the hydrodynamic focusing and the momentum transfer from the water drop when it is about to bounce off the surface, at which point the water drop retrieves most of its kinetic energy due to the negligible friction on superhydrophobic surfaces.

Calculation method for control rod dropping time in reactor

International Nuclear Information System (INIS)

Nogami, Takeki; Kato, Yoshifumi; Ishino, Jun-ichi; Doi, Isamu.

1996-01-01

If a control rod starts dropping, the dropping speed is rapidly increased, then settled substantially constant, rapidly decreased when it reaches a dash pot. A second detection signal generated by removing an AC component from a first detection signal is differentiated twice. The time when the maximum value among the twice differentiated values is generated is determined as a time when the control rods starts dropping. The time when minimum value among the twice differentiated values is generated is determined as a time when the control rod reaches the dash pot of the reactor. The measuring time within a range from the time when the control rod starts dropping to the time when the control rod reaches the dash pot of the reactor is determined. As a result, processing for the calculation of the dropping start time and dash pot reaching time of the control rod can be automatized. Further, it is suffice to conduct differentiation twice till the reaching time, which can facilitate the processing thereby enabling to determine a reliable time range. (N.H.)

Transcription factors and stress response gene alterations in human keratinocytes following Solar Simulated Ultra Violet Radiation.

Science.gov (United States)

Marais, Thomas L Des; Kluz, Thomas; Xu, Dazhong; Zhang, Xiaoru; Gesumaria, Lisa; Matsui, Mary S; Costa, Max; Sun, Hong

2017-10-19

Ultraviolet radiation (UVR) from sunlight is the major effector for skin aging and carcinogenesis. However, genes and pathways altered by solar-simulated UVR (ssUVR), a mixture of UVA and UVB, are not well characterized. Here we report global changes in gene expression as well as associated pathways and upstream transcription factors in human keratinocytes exposed to ssUVR. Human HaCaT keratinocytes were exposed to either a single dose or 5 repetitive doses of ssUVR. Comprehensive analyses of gene expression profiles as well as functional annotation were performed at 24 hours post irradiation. Our results revealed that ssUVR modulated genes with diverse cellular functions changed in a dose-dependent manner. Gene expression in cells exposed to a single dose of ssUVR differed significantly from those that underwent repetitive exposures. While single ssUVR caused a significant inhibition in genes involved in cell cycle progression, especially G2/M checkpoint and mitotic regulation, repetitive ssUVR led to extensive changes in genes related to cell signaling and metabolism. We have also identified a panel of ssUVR target genes that exhibited persistent changes in gene expression even at 1 week after irradiation. These results revealed a complex network of transcriptional regulators and pathways that orchestrate the cellular response to ssUVR.

Tunable all-optical photonic crystal channel drop filter for DWDM systems

Science.gov (United States)

Habibiyan, H.; Ghafoori-Fard, H.; Rostami, A.

2009-06-01

In this paper we propose a tunable channel drop filter in a two-dimensional photonic crystal, based on coupled-cavity waveguides with alternating small and large defects and an electromagnetically induced transparency phenomenon. By utilizing this phenomenon a narrower linewidth is obtained and also the frequency of the dropped signal becomes tunable. Simulation results show that the proposed filter is suitable for dense wavelength-division multiplexing (DWDM) systems with 0.8 nm channel spacing. Using this novel component, two ultrasmall eight-channel double-sided and single-sided demultiplexers are introduced. The properties of these devices are investigated using the finite-difference time-domain method. For the single-sided device, transmission loss is 1.5 ± 0.5 dB, the cross-talk level between adjacent channels is better than -18 dB and the average 3 dB optical passband is 0.36 nm. Using planar silicon-on-insulator technology, the physical area for the single-sided component is 700 µm2 and for the double-sided component is 575 µm2. To the best of our knowledge, these are the smallest all-optical demultiplexers with this spectral resolution reported to date. Malfunction of the proposed device due to fabrication errors is modeled and its tunable characteristic is demonstrated.

Drop detachment and motion on fuel cell electrode materials.

Science.gov (United States)

Gauthier, Eric; Hellstern, Thomas; Kevrekidis, Ioannis G; Benziger, Jay

2012-02-01

Liquid water is pushed through flow channels of fuel cells, where one surface is a porous carbon electrode made up of carbon fibers. Water drops grow on the fibrous carbon surface in the gas flow channel. The drops adhere to the superficial fiber surfaces but exhibit little penetration into the voids between the fibers. The fibrous surfaces are hydrophobic, but there is a substantial threshold force necessary to initiate water drop motion. Once the water drops begin to move, however, the adhesive force decreases and drops move with minimal friction, similar to motion on superhydrophobic materials. We report here studies of water wetting and water drop motion on typical porous carbon materials (carbon paper and carbon cloth) employed in fuel cells. The static coefficient of friction on these textured surfaces is comparable to that for smooth Teflon. But the dynamic coefficient of friction is several orders of magnitude smaller on the textured surfaces than on smooth Teflon. Carbon cloth displays a much smaller static contact angle hysteresis than carbon paper due to its two-scale roughness. The dynamic contact angle hysteresis for carbon paper is greatly reduced compared to the static contact angle hysteresis. Enhanced dynamic hydrophobicity is suggested to result from the extent to which a dynamic contact line can track topological heterogeneities of the liquid/solid interface.

Tracking Drop-out Students in Palestinian Refugee Camps in Lebanon

Science.gov (United States)

Al-Hroub, Anies

2015-01-01

This research paper examines the perceptions of students on the school drop-out problem in Palestinian refugee camps in Lebanon regarding (a) the social and economic causes associated with the phenomenon of school drop-out; (b) the educational policies and practices used in UNRWA schools and their relationship to student drop-out; and (c) the role…

Pressure drops in low pressure local boiling

International Nuclear Information System (INIS)

Courtaud, Michel; Schleisiek, Karl

1969-01-01

For prediction of flow reduction in nuclear research reactors, it was necessary to establish a correlation giving the pressure drop in subcooled boiling for rectangular channels. Measurements of pressure drop on rectangular channel 60 and 90 cm long and with a coolant gap of 1,8 and 3,6 mm were performed in the following range of parameters. -) 3 < pressure at the outlet < 11 bars abs; -) 25 < inlet temperature < 70 deg. C; -) 200 < heat flux < 700 W/cm 2 . It appeared that the usual parameter, relative length in subcooled boiling, was not sufficient to correlate experimental pressure losses on the subcooled boiling length and that there was a supplementary influence of pressure, heat flux and subcooling. With an a dimensional parameter including these terms a correlation was established with an error band of ±10%. With a computer code it was possible to derive the relation giving the overall pressure drop along the channel and to determine the local gradients of pressure drop. These local gradients were then correlated with the above parameter calculated in local conditions. 95 % of the experimental points were computed with an accuracy of ±10% with this correlation of gradients which can be used for non-uniform heated channels. (authors) [fr

NU-IN: Nucleotide evolution and input module for the EvolSimulator genome simulation platform

Directory of Open Access Journals (Sweden)

Barker Michael S

2010-08-01

Full Text Available Abstract Background There is increasing demand to test hypotheses that contrast the evolution of genes and gene families among genomes, using simulations that work across these levels of organization. The EvolSimulator program was developed recently to provide a highly flexible platform for forward simulations of amino acid evolution in multiple related lineages of haploid genomes, permitting copy number variation and lateral gene transfer. Synonymous nucleotide evolution is not currently supported, however, and would be highly advantageous for comparisons to full genome, transcriptome, and single nucleotide polymorphism (SNP datasets. In addition, EvolSimulator creates new genomes for each simulation, and does not allow the input of user-specified sequences and gene family information, limiting the incorporation of further biological realism and/or user manipulations of the data. Findings We present modified C++ source code for the EvolSimulator platform, which we provide as the extension module NU-IN. With NU-IN, synonymous and non-synonymous nucleotide evolution is fully implemented, and the user has the ability to use real or previously-simulated sequence data to initiate a simulation of one or more lineages. Gene family membership can be optionally specified, as well as gene retention probabilities that model biased gene retention. We provide PERL scripts to assist the user in deriving this information from previous simulations. We demonstrate the features of NU-IN by simulating genome duplication (polyploidy in the presence of ongoing copy number variation in an evolving lineage. This example is initiated with real genomic data, and produces output that we analyse directly with existing bioinformatic pipelines. Conclusions The NU-IN extension module is a publicly available open source software (GNU GPLv3 license extension to EvolSimulator. With the NU-IN module, users are now able to simulate both drift and selection at the nucleotide

Non-isothermal spreading of liquid drops on horizontal plates

International Nuclear Information System (INIS)

Ehrhard, P.; Davis, S.H.

1990-05-01

A viscous-liquid drop spreads on a smooth horizontal surface, which is uniformly heated or cooled. Lubrication theory is used to study thin drops subject to capillary, thermocapillary and gravity forces, and a variety of contact-angle-versus-speed conditions. It is found for isothermal drops that gravity is very important at large times and determines the power law for unlimited spreading. Predictions compare well with the experimental data on isothermal spreading for both two-dimensional and axisymmetric configurations. It is found that heating (cooling) retards (augments) the spreading process. When the advancing contact angle is zero, heating will cause the drop to spread only finitely far. For positive advancing contact angles, sufficient cooling will cause unlimited spreading. Thus, the heat transfer serves as a sentitive control on the spreading. (orig.) [de

Evaluating Eye Drop Instillation Technique and Its Determinants in Glaucoma Patients

Directory of Open Access Journals (Sweden)

Xinbo Gao

2018-01-01

Full Text Available Aim. To evaluate eye drop instillation technique and to explore its determinants in glaucoma patients. Methods. One hundred and thirteen patients diagnosed with glaucoma and self-administering topical antiglaucoma eye drops for at least 1 month were evaluated. All patients instilled artificial tear solution in one eye as they would do at home. The whole process was evaluated by two study staff. A comprehensive score system associated with eye drop instillation techniques was used to quantify the instillation technique and explore its determinants such as demographic and clinical characteristics. Results. Half of the patients (48.67% finished the administration of eye drop on first attempt.1.7 eye drops were squeezed out on average. 43 patients (37.17% got contact with ocular surface or adnexa. Only 19.7% patients had eye drop instillation techniques being defined as well. 11 patients (9.7% had prior instruction regarding using eye drops, while only 4 patients knew to occlude the tear duct by pressing the dacryocyst area. Older age and worse visual acuity were found to be independent risk factors for worse instillation technique. Conclusions. Eye drop instillation technique in glaucoma patients deserves great attention from eye care practitioners during their lifelong follow-up, especially those aged older and have worse visual acuity.

Student Drop-Out from German Higher Education Institutions

Science.gov (United States)

Heublein, Ulrich

2014-01-01

28% of students of any one year currently give up their studies in bachelor degree programmes at German higher education institutions. Drop-out is to be understood as the definite termination in the higher education system without obtaining an academic degree. The drop-out rate is thereby calculated with the help of statistical estimation…

Pharmacological activities of an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts in UVB-induced oxidative stress and inflammation of human corneal cells.

Science.gov (United States)

Bigagli, Elisabetta; Cinci, Lorenzo; D'Ambrosio, Mario; Luceri, Cristina

2017-08-01

Ultraviolet B (UVB) exposure is a risk factor for corneal damage resulting in oxidative stress, inflammation and cell death. The aim of this study was to investigate the potential protective effects of a commercial eye drop (Dacriovis™) containing Matricaria chamomilla and Euphrasia officinalis extracts on human corneal epithelial cells (HCEC-12) against UVB radiation-induced oxidative stress and inflammation as well as the underlying mechanisms. The antioxidant potential of the eye drops was evaluated by measuring the ferric reducing antioxidant power and the total phenolic content by Folin-Ciocalteu reagent. HCEC-12 cells were exposed to UVB radiation and treated with the eye drops at various concentrations. Cell viability, wound healing assay, reactive oxygen species (ROS) levels, protein and lipid oxidative damage and COX-2, IL-1β, iNOS, SOD-2, HO-1 and GSS gene expression, were assessed. Eye drops were able to protect corneal epithelial cells from UVB-induced cell death and ameliorated the wound healing; the eye drops exhibited a strong antioxidant activity, decreasing ROS levels and protein and lipid oxidative damage. Eye drops also exerted anti-inflammatory activities by decreasing COX-2, IL-1β, iNOS expression, counteracted UVB-induced GSS and SOD-2 expression and restored HO-1 expression to control levels. These findings suggest that an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts exerts positive effects against UVB induced oxidative stress and inflammation and may be useful in protecting corneal epithelial cells from UVB exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Spume Drops: Their Potential Role in Air-Sea Gas Exchange

Science.gov (United States)

Monahan, Edward C.; Staniec, Allison; Vlahos, Penny

2017-12-01

After summarizing the time scales defining the change of the physical properties of spume and other droplets cast up from the sea surface, the time scales governing drop-atmosphere gas exchange are compared. Following a broad review of the spume drop production functions described in the literature, a subset of these functions is selected via objective criteria, to represent typical, upper bound, and lower bound production functions. Three complementary mechanisms driving spume-atmosphere gas exchange are described, and one is then used to estimate the relative importance, over a broad range of wind speeds, of this spume drop mechanism compared to the conventional, diffusional, sea surface mechanism in air-sea gas exchange. While remaining uncertainties in the wind dependence of the spume drop production flux, and in the immediate sea surface gas flux, preclude a definitive conclusion, the findings of this study strongly suggest that, at high wind speeds (>20 m s-1 for dimethyl sulfide and >30 m s-1 for gases such a carbon dioxide), spume drops do make a significant contribution to air-sea gas exchange.Plain Language SummaryThis paper evaluates the existing spume drop generation functions available to date and selects a reasonable upper, lower and mid range function that are reasonable for use in air sea exchange models. Based on these the contribution of spume drops to overall air sea gas exchange at different wind speeds is then evaluated to determine the % contribution of spume. Generally below 20ms-1 spume drops contribute <1% of gas exchange but may account for a significant amount of gas exchange at higher wind speeds.

Filter aids influence on pressure drop across a filtration system

Science.gov (United States)

Hajar, S.; Rashid, M.; Nurnadia, A.; Ammar, M. R.; Hasfalina, C. M.

2017-06-01

Filter aids is commonly used to reduce pressure drop across air filtration system as it helps to increase the efficiency of filtration of accumulated filter cake. Filtration velocity is one of the main parameters that affect the performance of filter aids material. In this study, a formulated filter aids consisting of PreKot™ and activated carbon mixture (designated as PrekotAC) was tested on PTFE filter media under various filtration velocities of 5, 6, and 8 m/min at a constant material loading of 0.2 mg/mm2. Results showed that pressure drop is highly influenced by filtration velocity where higher filtration velocity leads to a higher pressure drop across the filter cake. It was found that PrekotAC performed better in terms of reducing the pressure drop across the filter cake even at the highest filtration velocity. The diversity in different particle size distribution of non-uniform particle size in the formulated PrekotAC mixture presents a higher permeability causes a lower pressure drop across the accumulated filter cake. The finding suggests that PrekotAC is a promising filter aids material that helps reducing the pressure drop across fabric filtration system.

Experimental analysis of waveform effects on satellite and ligament behavior via in situ measurement of the drop-on-demand drop formation curve and the instantaneous jetting speed curve

International Nuclear Information System (INIS)

Kwon, Kye-Si

2010-01-01

In situ techniques to measure the drop-on-demand (DOD) drop formation curve and the instantaneous jetting speed curve are developed such that ligament behavior and satellite behavior of inkjet droplets can be analyzed effectively. It is known that the droplet jetting behavior differs by ink properties and the driving waveform voltage. In this study, to reduce possible droplet placement errors due to satellite drops or long ligaments during printing, waveform effects on drop formation are investigated based on the measured DOD drop formation curve and the instantaneous jetting speed curve. Experimental results show that a dwell time greater than the so-called efficient dwell time was effective in reducing placement errors due to satellite drops during the printing process

Theory and experiments on electrohydrodynamic enhancement of evaporation from water drops

International Nuclear Information System (INIS)

Barthakur, N.N.

1990-01-01

Space charge produce by a single corona electrode was used to enhance evaporation rates from sessile drops of water. The drying curve was traced and a drop lifetime determined by a beta ray gauge which provided both sensitivity and reproducibility to the measurements. Lifetime was reduced by a factor of 3.5 to 4.7 when subjected to fluxes of 3.02x10 12 positive charges cm -2 s -1 than those from freely evaporating drops in the laboratory. A theoretical model based on mass transfer coefficient was developed to predict the drop lifetime. Calculated lifetime of drops of volume 0.1 to 0.5 ml agreed within 12 percent of the experimental values. Electric wind caused by the ionic drag is proposed to be the principal driving force for the observed enhancement of evaporation from the drops. (author). 24 refs., 2 figs., 1 tab

Physical Watermarking for Securing Cyber-Physical Systems via Packet Drop Injections

Energy Technology Data Exchange (ETDEWEB)

Ozel, Omur [Carnegie Mellon Univ., Pittsburgh, PA (United States); Weekrakkody, Sean [Carnegie Mellon Univ., Pittsburgh, PA (United States); Sinopoli, Bruno [Carnegie Mellon Univ., Pittsburgh, PA (United States)

2017-10-23

Physical watermarking is a well known solution for detecting integrity attacks on Cyber-Physical Systems (CPSs) such as the smart grid. Here, a random control input is injected into the system in order to authenticate physical dynamics and sensors which may have been corrupted by adversaries. Packet drops may naturally occur in a CPS due to network imperfections. To our knowledge, previous work has not considered the role of packet drops in detecting integrity attacks. In this paper, we investigate the merit of injecting Bernoulli packet drops into the control inputs sent to actuators as a new physical watermarking scheme. With the classical linear quadratic objective function and an independent and identically distributed packet drop injection sequence, we study the effect of packet drops on meeting security and control objectives. Our results indicate that the packet drops could act as a potential physical watermark for attack detection in CPSs.

Skating on a Film of Air: Drops Impacting on a Surface

Science.gov (United States)

Kolinski, John M.; Rubinstein, Shmuel M.; Mandre, Shreyas; Brenner, Michael P.; Weitz, David A.; Mahadevan, L.

2012-02-01

The commonly accepted description of drops impacting on a surface typically ignores the essential role of the air that is trapped between the impacting drop and the surface. Here we describe a new imaging modality that is sensitive to the behavior right at the surface. We show that a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the drop spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate on the air film laterally outward at surprisingly high velocities, consistent with theoretical predictions. Eventually this thin film of air breaks down as the fluid wets the surface via a spinodal-like mechanism. Our results show that the dynamics of impacting drops are much more complex than previously thought, with a rich array of unexpected phenomena that require rethinking classic paradigms.

Stability of alternating current discharges between water drops on insulation surfaces

International Nuclear Information System (INIS)

Rowland, S M; Lin, F C

2006-01-01

Discharges between water drops are important in the ageing of hydrophobic outdoor insulators. They may also be important in the processes leading up to flashover of these insulators in high pollution conditions. This paper considers discharges between drops when a limited alternating current is available, as experienced by an ageing insulator in service. A phenomenon is identified in which the length of a discharge between two drops is reduced through a particular type of distortion of the drops. This is visually characterized as a liquid protrusion from each of a pair of water drops along the insulator surface. This process is distinct from vibration of the drops, general distortion of their shape and the very fast emission of jet streams seen in very high fields. The process depends upon the discharge current, the resistivity of the moisture and the hydrophobicity of the insulation surface

A review on water fault diagnosis of PEMFC associated with the pressure drop

International Nuclear Information System (INIS)

Pei, Pucheng; Li, Yuehua; Xu, Huachi; Wu, Ziyao

2016-01-01

Highlights: • Reviewed the effect factors and estimations of pressure drop associated with water fault diagnosis. • Reviewed pressure drop-based water fault diagnosis using different indicators. • Deviation of pressure drop is used frequently to diagnose water fault. • Reviewed recovery strategies based on pressure drop used in commercial PEMFC. • Merits, demerits and application prospects of pressure drop-based water fault diagnosis are discussed. - Abstract: The pressure difference between the inlet and outlet of the reactant in fuel cells is called the pressure drop, which is related to the water amount inside the fuel cells. In recent years there have been many studies that used the pressure drop to detect the water content and diagnose water fault of proton exchange membrane fuel cells (PEMFCs). To our knowledge, there has not been a systematic review of these studies. In this paper, the effect variables of pressure drop are reviewed firstly. Then estimations of the theoretical pressure drop are reviewed mainly based on the following four aspects: Bernoulli’s equation, two-phase flow multiplier, Darcy’s law and artificial intelligence. Afterward, the water fault diagnosis based on the pressure drop using the following six indicators are reviewed: indicator of direct pressure drop, its deviation, frequency, multiplier, the ratio of pressure drop to flow rate and the flooding degree. In addition, the strategies of water fault recovery are also summarized. Finally the merits, demerits and application prospects of pressure drop-based water fault diagnosis are presented.

'Cryptogenic Drop Attacks' revisited: evidence of overlap with functional neurological disorder.

Science.gov (United States)

Hoeritzauer, Ingrid; Carson, Alan J; Stone, Jon

2018-02-07

In their 1973 BMJ paper 'Cryptogenic Drop Attacks', Stevens and Matthews described 40, mostly middle-aged, female patients with drop attacks of unknown cause. Although clinically common, there has been little on this topic since. We aimed to determine clinical features, comorbidity and outcome of patients with drop attacks. We carried out a retrospective review of patients with cryptogenic drop attacks seen consecutively by one clinician (JS) between 2006 and 2016. Demographics, phenomenology, duration and frequency of attacks, attack description and comorbid diagnoses were recorded. Patients were followed up with a notes review. 83 patients with cryptogenic drop attacks were predominantly female (89%, n=79), mean age 44  years. The majority (93%, n=77) could not remember the fall itself and almost half (43%, n=36) experienced prodromal dissociative symptoms. Mechanical trips or syncope preceded drop attacks, historically, in 24% (n=20) of cases. Persistent fatigue (73%, n=61), chronic pain (40%, n=33), functional limb weakness (31%,n=26) and dissociative (non-epileptic) attacks 28% (n=23) were common, with the latter usually preceding or emerging from drop attacks. At follow-up (88%, mean 38 months), 28% (n=23) had resolution of their drop attacks. Predisposing (but non-causative) disease comorbidity was found at baseline (n=12) and follow-up (n=5). Cryptogenic drop attacks are associated with high frequency of comorbid functional somatic and functional neurological disorders. Patients commonly have prodromal dissociative symptoms and in some there was a clear relationship with prior or subsequent dissociative (non-epileptic) attacks. Some cryptogenic drop attacks may be best understood as phenomena on the spectrum of dissociative attacks. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Probing the nanoscale with high-speed interferometry of an impacting drop

KAUST Repository

Thoroddsen, Sigurdur T.

2017-02-28

The simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 mu m thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thicknessevolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.

Probing the nanoscale with high-speed interferometry of an impacting drop

KAUST Repository

Thoroddsen, Sigurdur T; Li, Erqiang; Vakarelski, Ivan Uriev; Langley, Kenneth

2017-01-01

The simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 mu m thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thicknessevolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.

Critical look at South Africa’s Green Drop Programme

CSIR Research Space (South Africa)

Ntombela, Cebile

2016-10-01

Full Text Available (WSAs) in the controversial wastewater services sector. In particular, we focus on DWS’s incentive-based mechanism, the National Green Drop Certification Programme (Green Drop Programme), and evaluate the achievements and challenges associated with its...

Fabrication and Operation of Microfluidic Hanging-Drop Networks.

Science.gov (United States)

Misun, Patrick M; Birchler, Axel K; Lang, Moritz; Hierlemann, Andreas; Frey, Olivier

2018-01-01

The hanging-drop network (HDN) is a technology platform based on a completely open microfluidic network at the bottom of an inverted, surface-patterned substrate. The platform is predominantly used for the formation, culturing, and interaction of self-assembled spherical microtissues (spheroids) under precisely controlled flow conditions. Here, we describe design, fabrication, and operation of microfluidic hanging-drop networks.

On the relation of earthquake stress drop and ground motion variability

Science.gov (United States)

Oth, Adrien; Miyake, Hiroe; Bindi, Dino

2017-07-01

One of the key parameters for earthquake source physics is stress drop since it can be directly linked to the spectral level of ground motion. Stress drop estimates from moment corner frequency analysis have been shown to be extremely variable, and this to a much larger degree than expected from the between-event ground motion variability. This discrepancy raises the question whether classically determined stress drop variability is too large, which would have significant consequences for seismic hazard analysis. We use a large high-quality data set from Japan with well-studied stress drop data to address this issue. Nonparametric and parametric reference ground motion models are derived, and the relation of between-event residuals for Japan Meteorological Agency equivalent seismic intensity and peak ground acceleration with stress drop is analyzed for crustal earthquakes. We find a clear correlation of the between-event residuals with stress drops estimates; however, while the island of Kyushu is characterized by substantially larger stress drops than Honshu, the between-event residuals do not reflect this observation, leading to the appearance of two event families with different stress drop levels yet similar range of between-event residuals. Both the within-family and between-family stress drop variations are larger than expected from the ground motion between-event variability. A systematic common analysis of these parameters holds the potential to provide important constraints on the relative robustness of different groups of data in the different parameter spaces and to improve our understanding on how much of the observed source parameter variability is likely to be true source physics variability.

Drop performance test and evaluation for HANARO shutoff units

International Nuclear Information System (INIS)

Jung, Y. H.; Cho, Y. K.; Lee, J. H.; Choi, Y. S.; Woo, J. S.

2004-01-01

The function of the shutoff units of the HANARO is to rapidly insert the shutoff rod into the reactor core for safe shutdown of reactor. This paper describes drop performance test and evaluation for a shutoff unit for the technical verification of lifetime extension and localization of the HANARO shutoff units. We have performed preliminary drop performance tests for a shutoff unit at 1/2-core test loop and analyzed through the comparison with the test results performed during design verification test and the results of the periodic performance test in HANARO. It shows that the results of the local fabrication, installation and alignment for the shutoff unit meet the basic performance requirements, Furthermore, the performance evaluation method of the periodic drop test of the HANARO shutoff units is a conservative method comparing with the real drop time

An Extensional Characterization of Lambda-Lifting and Lambda-Dropping

DEFF Research Database (Denmark)

Danvy, Olivier

1999-01-01

Lambda-lifting and lambda-dropping respectively transform a block-structured functional program into recursive equations and vice versa. Lambda-lifting was developed in the early 80’s, whereas lambda-dropping is more recent. Both are split into an analysis and a transformation. Published work......, however, has only concentrated on the analysis parts. We focus here on the transformation parts and more precisely on their correctness, which appears never to have been proven. To this end, we define extensional versions of lambda-lifting and lambda-dropping and establish their correctness with respect...

An Extensional Characterization of Lambda-Lifting and Lambda-Dropping

DEFF Research Database (Denmark)

Danvy, Olivier

1998-01-01

Lambda-lifting and lambda-dropping respectively transform a block-structured functional program into recursive equations and vice versa. Lambda-lifting was developed in the early 80’s, whereas lambda-dropping is more recent. Both are split into an analysis and a transformation. Published work......, however, has only concentrated on the analysis parts. We focus here on the transformation parts and more precisely on their correctness, which appears never to have been proven. To this end, we define extensional versions of lambda-lifting and lambda-dropping and establish their correctness with respect...

Complex cooling water systems optimization with pressure drop consideration

CSIR Research Space (South Africa)

Gololo, KV

2012-12-01

Full Text Available Pressure drop consideration has shown to be an essential requirement for the synthesis of a cooling water network where reuse/recycle philosophy is employed. This is due to an increased network pressure drop associated with additional reuse...

Modeling and simulation of milk emulsion drying in spray dryers

Directory of Open Access Journals (Sweden)

V. S. Birchal

2005-06-01

Full Text Available This work aims at modeling and simulating the drying of whole milk emulsion in spray dryers. Drops and particles make up the discrete phase and are distributed into temporal compartments following their residence time in the dryer. Air is the continuous and well-mixed phase. Mass and energy balances are developed for each phase, taking into account their interactions. Constitutive equations for describing the drop swelling and drying mechanisms as well as the heat and mass transfer between particles and hot air are proposed and analyzed. A set of algebraic-differential equations is obtained and solved by specific numerical codes. Results from experiments carried out in a pilot spray dryer are used to validate the model developed and the numerical algorithm. Comparing the simulated and experimental data, it is shown that the model predicts well the individual drop-particle history inside the dryer as well as the overall outlet air-particle temperature and humidity.

Vortex-induced buckling of a viscous drop impacting a pool

KAUST Repository

Li, Erqiang

2017-07-20

We study the intricate buckling patterns which can form when a viscous drop impacts a much lower viscosity miscible pool. The drop enters the pool by its impact inertia, flattens, and sinks by its own weight while stretching into a hemispheric bowl. Upward motion along the outer bottom surface of this bowl produces a vortical boundary layer which separates along its top and rolls up into a vortex ring. The vorticity is therefore produced in a fundamentally different way than for a drop impacting a pool of the same liquid. The vortex ring subsequently advects into the bowl, thereby stretching the drop liquid into ever thinner sheets, reaching the micron level. The rotating motion around the vortex pulls in folds to form multiple windings of double-walled toroidal viscous sheets. The axisymmetric velocity field thereby stretches the drop liquid into progressively finer sheets, which are susceptible to both axial and azimuthal compression-induced buckling. The azimuthal buckling of the sheets tends to occur on the inner side of the vortex ring, while their folds can be stretched and straightened on the outside edge. We characterize the total stretching from high-speed video imaging and use particle image velocimetry to track the formation and evolution of the vortex ring. The total interfacial area between the drop and the pool liquid can grow over 40-fold during the first 50 ms after impact. Increasing pool viscosity shows entrapment of a large bubble on top of the drop, while lowering the drop viscosity produces intricate buckled shapes, appearing at the earliest stage and being promoted by the crater motions. We also present an image collage of the most intriguing and convoluted structures observed. Finally, a simple point-vortex model reproduces some features from the experiments and shows variable stretching along the wrapping sheets.

MAC-Layer Active Dropping for Real-Time Video Streaming in 4G Access Networks

KAUST Repository

She, James

2010-12-01

This paper introduces a MAC-layer active dropping scheme to achieve effective resource utilization, which can satisfy the application-layer delay for real-time video streaming in time division multiple access based 4G broadband wireless access networks. When a video frame is not likely to be reconstructed within the application-layer delay bound at a receiver for the minimum decoding requirement, the MAC-layer protocol data units of such video frame will be proactively dropped before the transmission. An analytical model is developed to evaluate how confident a video frame can be delivered within its application-layer delay bound by jointly considering the effects of time-varying wireless channel, minimum decoding requirement of each video frame, data retransmission, and playback buffer. Extensive simulations with video traces are conducted to prove the effectiveness of the proposed scheme. When compared to conventional cross-layer schemes using prioritized-transmission/retransmission, the proposed scheme is practically implementable for more effective resource utilization, avoiding delay propagation, and achieving better video qualities under certain conditions.

Student Drop-Out Trends at Sultan Qaboos University and Kuwait University: 2000-2011

Science.gov (United States)

Al Ghanboosi, Salim Saleem; Alqahtani, Abdulmuhsen Ayedh

2013-01-01

The current study aims to explore the drop-out trends at Sultan Qaboos. University and Kuwait University. Archival data of the period 2000-2011 were used to achieve this goal. Main findings showed that (a) male drop-out rates are higher than female drop-out rates; (b) drop- out rates at scientific colleges are higher; (c) drop-out rates of…

Effect of rb-bFGF eye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery

Directory of Open Access Journals (Sweden)

Jing Chen

2017-10-01

Full Text Available AIM: To compare and analyze the effect of recombinant bovine basic fibroblast growth factor(bFGFeye drops and hydroxyl indican eye drops on the tear film stability and dry eye symptoms after age-related cataract surgery. METHODS: A total of 115 patients(115 affected eyeswith dry eyes after age-related cataract surgery were divided into the bFGF group, the hydroxyl indican group and the blank control group by the random number table method. The blank control group was only given routine anti-inflammatory treatment, and on the basis, the bFGF group and the hydroxyl indican group were treated with bFGF eye drops and hydroxyl indican eye drops respectively. The clinical efficacy, adverse reactions, changes in scores of dry eye symptoms, Schirmer test(SⅠt, tear film break-up time(BUTand corneal fluorescein staining(CFSscores at different time points were compared among the three groups. RESULTS: The total markedly effective rates in the bFGF group(89.5%was higher than that in the hydroxyl indican group(70.3%or the blank control group(47.5%(PPPCONCLUSION: The tear film is unstable in early stage after age-related cataract surgery, and there are dry eye symptoms. The intervention with bFGF eye drops and hydroxyl indican eye drops can effectively restore the tear film stability and significantly relieve dry eye symptoms, and the effect of bFGF eye drops is more significant.

Summary of Skoda JS rod drop measurements analysis

International Nuclear Information System (INIS)

Svarny, J.; Krysl, V.

1999-01-01

A summary is presented of the Skoda JS rod drop reactivity measurements analysis provided during last two years based on control rod worth measurements by the outer ion chambers. Standard analysis based on comparisons of dynamics macrocode MOBY-DICK-SK and experimental data is extended to the 8-th group delayed neutron structure and new features of rod drop process are investigated. (author)

Error-free 320 Gb/s simultaneous add-drop multiplexing

DEFF Research Database (Denmark)

Mulvad, Hans Christian Hansen; Oxenløwe, Leif Katsuo; Clausen, Anders

2007-01-01

We report on the first demonstration of error-free time-division add-drop multiplexing at 320 Gb/s. The add- and drop-operations are performed simultaneously in a non-linear optical loop mirror with only 100 m of highly non-linear fibre....

Dropped fuel damage prediction techniques and the DROPFU code

International Nuclear Information System (INIS)

Mottershead, K.J.; Beardsmore, D.W.; Money, G.

1995-01-01

During refuelling, and fuel handling, at UK Advanced Gas Cooled Reactor (AGR) stations it is recognised that the accidental dropping of fuel is a possibility. This can result in dropping individual fuel elements, a complete fuel stringer, or a whole assembly. The techniques for assessing potential damage have been developed over a number of years. This paper describes how damage prediction techniques have subsequently evolved to meet changing needs. These have been due to later fuel designs and the need to consider drops in facilities outside the reactor. The paper begins by briefly describing AGR fuel and possible dropped fuel scenarios. This is followed by a brief summary of the damage mechanisms and the assessment procedure as it was first developed. The paper then describes the additional test work carried out, followed by the detailed numerical modelling. Finally, the paper describes the extensions to the practical assessment methods. (author)

Ultrasonic characterization of single drops of liquids

Energy Technology Data Exchange (ETDEWEB)

Sinha, Dipen N. (Los Alamos, NM)

1998-01-01

Ultrasonic characterization of single drops of liquids. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities.

Ultrasonic characterization of single drops of liquids

Energy Technology Data Exchange (ETDEWEB)

Sinha, D.N.

1998-04-14

Ultrasonic characterization of single drops of liquids is disclosed. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities. 5 figs.

Standing wave design and optimization of a simulated moving bed chromatography for separation of xylobiose and xylose under the constraints on product concentration and pressure drop.

Science.gov (United States)

Lee, Chung-Gi; Choi, Jae-Hwan; Park, Chanhun; Wang, Nien-Hwa Linda; Mun, Sungyong

2017-12-08

The feasibility of a simulated moving bed (SMB) technology for the continuous separation of high-purity xylobiose (X2) from the output of a β-xylosidase X1→X2 reaction has recently been confirmed. To ensure high economical efficiency of the X2 production method based on the use of xylose (X1) as a starting material, it is essential to accomplish the comprehensive optimization of the X2-separation SMB process in such a way that its X2 productivity can be maximized while maintaining the X2 product concentration from the SMB as high as possible in consideration of a subsequent lyophilization step. To address this issue, a suitable SMB optimization tool for the aforementioned task was prepared based on standing wave design theory. The prepared tool was then used to optimize the SMB operation parameters, column configuration, total column number, adsorbent particle size, and X2 yield while meeting the constraints on X2 purity, X2 product concentration, and pressure drop. The results showed that the use of a larger particle size caused the productivity to be limited by the constraint on X2 product concentration, and a maximum productivity was attained by choosing the particle size such that the effect of the X2-concentration limiting factor could be balanced with that of pressure-drop limiting factor. If the target level of X2 product concentration was elevated, higher productivity could be achieved by decreasing particle size, raising the level of X2 yield, and increasing the column number in the zones containing the front and rear of X2 solute band. Copyright © 2017 Elsevier B.V. All rights reserved.

Capillarity and wetting phenomena drops, bubbles, pearls, waves

CERN Document Server

Gennes, Pierre-Gilles; Quéré, David

2004-01-01

As I glance out my window in the early morning, I can see beads of droplets gracing a spider web. The film of dew that has settled on the threads is unstable and breaks up spontaneously into droplets. This phenomenon has implications for the treatment of textile fibers (the process known as "oiling"), glass, and carbon. It is no less important when applying mascara! I take my morning shower. The moment I step out, I dry off by way of evaporation (which makes me feel cold) and by dewetting (the process by which dry areas form spontaneously and expand on my skin). As I rush into my car under a pelting rain, my attention is caught by small drops stuck on my windshield. I also notice larger drops rolling down and others larger still that, like snails, leave behind them a trail of water. I ask myself what the difference is between these rolling drops and grains of sand tumbling down an incline. I wonder why the smallest drops remain stuck. The answers to such questions do help car manufacturers treat the surface o...

Drop behavior in acoustic standing waves; Teizaihachu ni okeru ekiteki no kyodo

Energy Technology Data Exchange (ETDEWEB)

Kamimura, H. [National Aerospace Laboratory, Tokyo (Japan); Yamanaka, T. [Yokohama National University, Yokohama (Japan)

1997-10-01

When new materials, such as those for space shuttles, are developed, it is necessary to hold then in a non-contacting manner. Described herein is behavior of drops in a holding device which utilizes acoustic radiation pressure. When an object sufficiently small as compared with wavelength of a sound wave is placed in acoustic standing waves, it is subjected to acoustic radiation pressure. Chandrasekahr developed the theory on the stability of a rotating drop by equating the entire mechanical energy of a drop with its surface energy. This theory, based on the assumption of symmetric surface energy, is incapable of theoretically dealing with multi-lobed waves evolved by surface tension. In this study, multi-lobed waves excited by sound waves in a rotating drop are analytically found without assuming symmetry of drop surface energy. The multi-lobe waves are first found on the assumption that the acoustic radiation pressure around a drop is constant. Then, the effects of the deformed drop on the radiation pressure around the drop are considered. In addition, the equation for the relationship between the radiation pressure and a drop that becomes oblate due to the radiation pressure is obtained. The theoretically derived results by this equation are in good agreement with the observed results by the ground and flight tests. 17 refs., 18 figs.

Epileptic negative drop attacks in atypical benign partial epilepsy: a neurophysiological study.

Science.gov (United States)

Hirano, Yoshiko; Oguni, Hirokazu; Osawa, Makiko

2009-03-01

We conducted a computer-assisted polygraphic analysis of drop attacks in a child with atypical benign partial epilepsy (ABPE) to investigate neurophysiological characteristics. The patient was a six-year two-month-old girl, who had started to have focal motor seizures, later combined with daily epileptic negative myoclonus (ENM) and drop attacks, causing multiple injuries. We studied episodes of ENM and drop attacks using video-polygraphic and computer-assisted back-averaging analysis. A total of 12 ENM episodes, seven involving the left arm (ENMlt) and five involving both arms (ENMbil), and five drop attacks were captured for analysis. All episodes were time-locked to spike-and-wave complexes (SWC) arising from both centro-temporo-parietal (CTP) areas. The latency between the onset of SWC and ENMlt, ENMbil, and drop attacks reached 68 ms, 42 ms, and 8 ms, respectively. The height of the spike as well as the slow-wave component of SWC for drop attacks were significantly larger than that for both ENMlt and ENMbil (p negative myoclonus involving not only upper proximal but also axial muscles, causing the body to fall. Thus, drop attacks in ABPE are considered to be epileptic negative drop attacks arising from bilateral CTP foci and differ from drop attacks of a generalized origin seen in Lennox-Gastaut syndrome and myoclonic-astatic epilepsy.

A PIV Study of Drop-interface Coalescence with Surfactants

Science.gov (United States)

Weheliye, Weheliye Hashi; Dong, Teng; Angeli, Panagiota

2017-11-01

In this work, the coalescence of a drop with an aqueous-organic interface was studied by Particle Image Velocimetry (PIV). The effect of surfactants on the drop surface evolution, the vorticity field and the kinetic energy distribution in the drop during coalescence were investigated. The coalescence took place in an acrylic rectangular box with 79% glycerol solution at the bottom and Exxsol D80 oil above. The glycerol solution drop was generated through a nozzle fixed at 2cm above the aqueous/oil interface and was seeded with Rhodamine particles. The whole process was captured by a high-speed camera. Different mass ratios of non-ionic surfactant Span80 to oil were studied. The increase of surfactant concentration promoted deformation of the interface before the rupture of the trapped oil film. At the early stages after film rupture, two counter-rotating vortices appeared at the bottom of the drop which then travelled to the upper part. The propagation rates, as well as the intensities of the vortices decreased at high surfactant concentrations. At early stages, the kinetic energy was mainly distributed near the bottom part of the droplet, while at later stages it was distributed near the upper part of the droplet. Programme Grant MEMPHIS, Chinese Scholarship Council (CSC).

ESD full chip simulation: HBM and CDM requirements and simulation approach

Directory of Open Access Journals (Sweden)

E. Franell

2008-05-01

Full Text Available Verification of ESD safety on full chip level is a major challenge for IC design. Especially phenomena with their origin in the overall product setup are posing a hurdle on the way to ESD safe products. For stress according to the Charged Device Model (CDM, a stumbling stone for a simulation based analysis is the complex current distribution among a huge number of internal nodes leading to hardly predictable voltage drops inside the circuits.

This paper describes an methodology for Human Body Model (HBM simulations with an improved ESD-failure coverage and a novel methodology to replace capacitive nodes within a resistive network by current sources for CDM simulation. This enables a highly efficient DC simulation clearly marking CDM relevant design weaknesses allowing for application of this software both during product development and for product verification.

Active structuring of colloidal armour on liquid drops

OpenAIRE

Dommersnes, Paul; Rozynek, Zbigniew; Mikkelsen, Alexander; Castberg, Rene; Kjerstad, Knut; Hersvik, Kjetil; Fossum, Jon Otto

2013-01-01

Adsorption and assembly of colloidal particles at the surface of liquid droplets are at the base of particle-stabilized emulsions and templating. Here we report that electrohydrodynamic and electro-rheological effects in leaky-dielectric liquid drops can be used to structure and dynamically control colloidal particle assemblies at drop surfaces, including electric-fieldassisted convective assembly of jammed colloidal ‘ribbons’, electro-rheological colloidal chains confined to a...

Origin and dynamics of vortex rings in drop splashing.

Science.gov (United States)

Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho

2015-09-04

A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row of vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.

Numerical simulation for gas-liquid two-phase flow in pipe networks

International Nuclear Information System (INIS)

Li Xiaoyan; Kuang Bo; Zhou Guoliang; Xu Jijun

1998-01-01

The complex pipe network characters can not directly presented in single phase flow, gas-liquid two phase flow pressure drop and void rate change model. Apply fluid network theory and computer numerical simulation technology to phase flow pipe networks carried out simulate and compute. Simulate result shows that flow resistance distribution is non-linear in two phase pipe network

Two-phase flow boiling pressure drop in small channels

International Nuclear Information System (INIS)

Sardeshpande, Madhavi V.; Shastri, Parikshit; Ranade, Vivek V.

2016-01-01

Highlights: • Study of typical 19 mm steam generator tube has been undertaken in detail. • Study of two phase flow boiling pressure drop, flow instability and identification of flow regimes using pressure fluctuations is the main focus of present work. • Effect of heat and mass flux on pressure drop and void fraction was studied. • Flow regimes identified from pressure fluctuations data using FFT plots. • Homogeneous model predicted pressure drop well in agreement. - Abstract: Two-phase flow boiling in small channels finds a variety of applications in power and process industries. Heat transfer, boiling flow regimes, flow instabilities, pressure drop and dry out are some of the key issues related to two-phase flow boiling in channels. In this work, the focus is on pressure drop in two-phase flow boiling in tubes of 19 mm diameter. These tubes are typically used in steam generators. Relatively limited experimental database is available on 19 mm ID tube. Therefore, in the present work, the experimental set-up is designed for studying flow boiling in 19 mm ID tube in such a way that any of the different flow regimes occurring in a steam generator tube (from pre-heating of sub-cooled water to dry-out) can be investigated by varying inlet conditions. The reported results cover a reasonable range of heat and mass flux conditions such as 9–27 kW/m 2 and 2.9–5.9 kg/m 2 s respectively. In this paper, various existing correlations are assessed against experimental data for the pressure drop in a single, vertical channel during flow boiling of water at near-atmospheric pressure. A special feature of these experiments is that time-dependent pressures are measured at four locations along the channel. The steady-state pressure drop is estimated and the identification of boiling flow regimes is done with transient characteristics using time series analysis. Experimental data and corresponding results are compared with the reported correlations. The results will be

Simulating Results of Experiments on Gene Regulation of the Lactose Operon in Escherichia coli; a Problem-Solving Exercise.

Science.gov (United States)

Hitchen, Trevor; Metcalfe, Judith

1987-01-01

Describes a simulation of the results of real experiments which use different strains of Escherichia coli. Provides an inexpensive practical problem-solving exercise to aid the teaching and understanding of the Jacob and Monod model of gene regulation. (Author/CW)

Numerical Simulation of Flow Behavior within a Venturi Scrubber

Directory of Open Access Journals (Sweden)

M. M. Toledo-Melchor

2014-01-01

Full Text Available The present work details the three-dimensional numerical simulation of single-phase and two-phase flow (air-water in a venturi scrubber with an inlet and throat diameters of 250 and 122.5 mm, respectively. The dimensions and operating parameters correspond to industrial applications. The mass flow rate conditions were 0.483 kg/s, 0.736 kg/s, 0.861 kg/s, and 0.987 kg/s for the gas only simulation; the mass flow rate for the liquid was 0.013 kg/s and 0.038 kg/s. The gas flow was simulated in five geometries with different converging and diverging angles while the two-phase flow was only simulated for one geometry. The results obtained were validated with experimental data obtained by other researchers. The results show that the pressure drop depends significantly on the gas flow rate and that water flow rate does not have significant effects neither on the pressure drop nor on the fluid maximum velocity within the scrubber.

Drop rebound after impact: the role of the receding contact angle.

Science.gov (United States)

Antonini, C; Villa, F; Bernagozzi, I; Amirfazli, A; Marengo, M

2013-12-31

Data from the literature suggest that the rebound of a drop from a surface can be achieved when the wettability is low, i.e., when contact angles, measured at the triple line (solid-liquid-air), are high. However, no clear criterion exists to predict when a drop will rebound from a surface and which is the key wetting parameter to govern drop rebound (e.g., the "equilibrium" contact angle, θeq, the advancing and the receding contact angles, θA and θR, respectively, the contact angle hysteresis, Δθ, or any combination of these parameters). To clarify the conditions for drop rebound, we conducted experimental tests on different dry solid surfaces with variable wettability, from hydrophobic to superhydrophobic surfaces, with advancing contact angles 108° contact angles 89° contact angle is the key wetting parameter that influences drop rebound, along with surface hydrophobicity: for the investigated impact conditions (drop diameter 2.4 contact angles higher than 100°. Also, the drop rebound time decreased by increasing the receding contact angle. It was also shown that in general care must be taken when using statically defined wetting parameters (such as advancing and receding contact angles) to predict the dynamic behavior of a liquid on a solid surface because the dynamics of the phenomenon may affect surface wetting close to the impact point (e.g., as a result of the transition from the Cassie-Baxter to Wenzel state in the case of the so-called superhydrophobic surfaces) and thus affect the drop rebound.

VOF simulations of the contact angle dynamics during the drop spreading: standard models and a new wetting force model.

Science.gov (United States)

Malgarinos, Ilias; Nikolopoulos, Nikolaos; Marengo, Marco; Antonini, Carlo; Gavaises, Manolis

2014-10-01

In this study,a novel numerical implementation for the adhesion of liquid droplets impacting normally on solid dry surfaces is presented. The advantage of this new approach, compared to the majority of existing models, is that the dynamic contact angle forming during the surface wetting process is not inserted as a boundary condition, but is derived implicitly by the induced fluid flow characteristics (interface shape) and the adhesion physics of the gas-liquid-surface interface (triple line), starting only from the advancing and receding equilibrium contact angles. These angles are required in order to define the wetting properties of liquid phases when interacting with a solid surface. The physical model is implemented as a source term in the momentum equation of a Navier-Stokes CFD flow solver as an "adhesion-like" force which acts at the triple-phase contact line as a result of capillary interactions between the liquid drop and the solid substrate. The numerical simulations capture the liquid-air interface movement by considering the volume of fluid (VOF) method and utilizing an automatic local grid refinement technique in order to increase the accuracy of the predictions at the area of interest, and simultaneously minimize numerical diffusion of the interface. The proposed model is validated against previously reported experimental data of normal impingement of water droplets on dry surfaces at room temperature. A wide range of impact velocities, i.e. Weber numbers from as low as 0.2 up to 117, both for hydrophilic (θadv=10°-70°) and hydrophobic (θadv=105°-120°) surfaces, has been examined. Predictions include in addition to droplet spreading dynamics, the estimation of the dynamic contact angle; the latter is found in reasonable agreement against available experimental measurements. It is thus concluded that theimplementation of this model is an effective approach for overcoming the need of a pre-defined dynamic contact angle law, frequently adopted as

High-Speed Interferometry Under Impacting Drops

KAUST Repository

Langley, Kenneth R.; Li, Erqiang; Thoroddsen, Sigurdur T

2017-01-01

Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

High-Speed Interferometry Under Impacting Drops

KAUST Repository

Langley, Kenneth R.

2017-08-31

Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

Flow rate-pressure drop relation for deformable shallow microfluidic channels

Science.gov (United States)

Christov, Ivan C.; Cognet, Vincent; Shidhore, Tanmay C.; Stone, Howard A.

2018-04-01

Laminar flow in devices fabricated from soft materials causes deformation of the passage geometry, which affects the flow rate--pressure drop relation. For a given pressure drop, in channels with narrow rectangular cross-section, the flow rate varies as the cube of the channel height, so deformation can produce significant quantitative effects, including nonlinear dependence on the pressure drop [{Gervais, T., El-Ali, J., G\\"unther, A. \\& Jensen, K.\\ F.}\\ 2006 Flow-induced deformation of shallow microfluidic channels.\\ \\textit{Lab Chip} \\textbf{6}, 500--507]. Gervais et. al. proposed a successful model of the deformation-induced change in the flow rate by heuristically coupling a Hookean elastic response with the lubrication approximation for Stokes flow. However, their model contains a fitting parameter that must be found for each channel shape by performing an experiment. We present a perturbation approach for the flow rate--pressure drop relation in a shallow deformable microchannel using the theory of isotropic quasi-static plate bending and the Stokes equations under a lubrication approximation (specifically, the ratio of the channel's height to its width and of the channel's height to its length are both assumed small). Our result contains no free parameters and confirms Gervais et. al.'s observation that the flow rate is a quartic polynomial of the pressure drop. The derived flow rate--pressure drop relation compares favorably with experimental measurements.

Further experience in simulation of rod drop experiments in the Loviisa and Mochovce reactors

International Nuclear Information System (INIS)

Siltanen, P.; Kaloinen, E.; Tanskanen, A.; Mattila, R.

2001-01-01

Simulations of reactor scram experiments using the 3-dimensional kinetics code HEXTRAN have been updated for the initial cores of Loviisa-1 and 2 Mochovce-1 and have been extended to burned cores of Loviisa-1. In these simulations, the entire experiment is simulated dynamically, including the behaviour of the core, the signal of the ionization chamber, and the inverse point kinetics of the reactivity meter. The predicted output of the reactivity meter is compared with the output observed during the experiment (Authors)

Effect of electrode intrusion on pressure drop and electrochemical performance of an all-vanadium redox flow battery

Science.gov (United States)

Kumar, S.; Jayanti, S.

2017-08-01

In this paper, we present a study of the effect of electrode intrusion into the flow channel in an all-vanadium redox flow battery. Permeability, pressure drop and electrochemical performance have been measured in a cell with active area 100 cm2and 414 cm2 fitted with a carbon felt electrode of thickness of 3, 6 or 9 mm compressed to 1.5, 2.5 or 4 mm, respectively, during assembly. Results show that the pressure drop is significantly higher than what can be expected in the thick electrode case while its electrochemical performance is lower. Detailed flow analysis using computational fluid dynamics simulations in two different flow fields shows that both these results can be attributed to electrode intrusion into the flow channel leading to increased resistance to electrolyte flow through the electrode. A correlation is proposed to evaluate electrode intrusion depth as a function of compression.

Develoment of pressure drop calculation modules for a wire-wrapped LMR subassembly

International Nuclear Information System (INIS)

Kim, Young Gyun; Lim, Hyun Jin; Kim, Won Seok; Kim, Young Il

2000-06-01

Pressure drop calculation modules for a wire-wrapped LMR subassembly was been developed. This report summarizes present information on pressure drop calculation modules for inlet hole, lower part and upper part of a wire-wrapped LMR subassembly which was developed using simple formulas of sudden expansion and sudden contraction. A case calculation study was done using design data of a KALIMER driver fuel subassembly. And the total pressure drop in the driver fuel subassembly, except for the bundle part, was calculated as 0.13 MPa, which is in the reasonable pressure drop range. The developed modules will be integrated in the total subassembly pressure drop calculation code with further improvements

Numerical simulation of droplet formation regimes and sizes in microfluidic T-junction devices

Science.gov (United States)

Nekouei, Mehdi; Vanapalli, Siva

2014-11-01

The T-junction geometry has been widely used for producing monodisperse droplets in microfluidic devices. Droplet formation regimes and sizes are expected to depend on a variety of conditions including flow rates, capillary number, channel geometry and viscosity ratio. Experiments have investigated drop production at a T-junction in a narrow control parameter space and developed analytical models for specific operating regimes. In this study, we take advantage of numerical simulations based on volume-of-fluid method to explore this broad parameter space systematically, and contrast our results with prior experimental data. We find our simulations predict well the regimes of squeezing, dripping and jetting. We also observe that our drop size data is in good agreement with three different experimental reports. Although our results match experimental data, the analytical models do not agree with each other since they are based on specific operating conditions. We use numerical simulations to elucidate the missing components in the physics of drop formation at a T-junction, with an attempt to reconcile existing analytical models.

Analysis of an Electrostatic MEMS Squeeze-film Drop Ejector

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Edward P. Furlani

2009-10-01

Full Text Available We present an analysis of an electrostatic drop-on-demand MEMS fluid ejector. The ejector consists of a microfluidic chamber with a piston that is suspended a few microns beneath a nozzle plate. A drop is ejected when a voltage is applied between the orifice plate and the piston. This produces an electrostatic force that moves the piston towards the nozzle. The moving piston generates a squeeze-film pressure distribution that causes drop ejection. We discuss the operating physics of the ejector and present a lumped-element model for predicting its performance. We calibrate the model using coupled structural-fluidic CFD analysis.

Internal flow of acoustically levitated drops undergoing sectorial oscillations

International Nuclear Information System (INIS)

Shen, C.L.; Xie, W.J.; Yan, Z.L.; Wei, B.

2010-01-01

We present the experimental observation and theoretical analysis of fluid flow in acoustically levitated water drop undergoing sectorial oscillations. The fluid always flows between the extended sections and the compressed sections. The magnitude of fluid velocity decreases from the equatorial fringe to the centre of levitated drop. The maximum fluid velocity is 60-160 mm/s and the Reynolds number of the oscillations is estimated to be 137-367. The internal flow of the drop is analyzed as potential flow, and the fluid velocity is found to be horizontal. In the equatorial plane, the calculated stream lines and velocity profiles agree well with the experimental observations.

A GCM study of organic matter in marine aerosol and its potential contribution to cloud drop activation

Directory of Open Access Journals (Sweden)

G. J. Roelofs

2008-02-01

Full Text Available With the global aerosol-climate model ECHAM5-HAM we investigate the potential influence of organic aerosol originating from the ocean on aerosol mass and chemical composition and the droplet concentration and size of marine clouds. We present sensitivity simulations in which the uptake of organic matter in the marine aerosol is prescribed for each aerosol mode with varying organic mass and mixing state, and with a geographical distribution and seasonality similar to the oceanic emission of dimethyl sulfide. Measurements of aerosol mass, aerosol chemical composition and cloud drop effective radius are used to assess the representativity of the model initializations. Good agreement with the measurements is obtained when organic matter is added to the Aitken, accumulation and coarse modes simultaneously. Representing marine organics in the model leads to higher cloud drop number concentrations and thus smaller cloud drop effective radii, and this improves the agreement with measurements. The mixing state of the organics and the other aerosol matter, i.e. internal or external depending on the formation process of aerosol organics, is an important factor for this. We estimate that globally about 75 Tg C yr⁻¹ of organic matter from marine origin enters the aerosol phase, with comparable contributions from primary emissions and secondary organic aerosol formation.

Analyses to demonstrate the structural performance of the CASTOR KN12 in hypothetical accident drop accident scenarios

International Nuclear Information System (INIS)

Diersch, R.; Weiss, M.; Tso, C.F.; Chung, S.H.; Lee, H.Y.

2004-01-01

CASTORc ircledR KN-12 is a new cask design by GNB for KHNP-NETEC for dry and wet transportation of up to twelve spent PWR fuel assemblies in Korea. It received its transport license from the Korean Competent Authority KINS in July 2002 and is now in use in South Korea. It has been designed to satisfy the regulatory requirements of the 10 CFR 71 and the IAEA ST-1 for Type B(U)F packages. Its structural performance was demonstrated against the load cases and boundary conditions as defined in 10 CFR 71 and NRC's Regulatory Guide 7.8, and further explained in NUREG 1617. This included normal conditions of transport load cases - including Hot Environment, Cold Environment, Increased External Pressure (140MPa), Minimum External Pressure (24.5kPa), Vibration and shock, and 0.3m free drop - and the hypothetical accident conditions load cases - including the 9m Free Drop, Puncture, Thermal Fire Accident, 200m Water Immersion and 1.5 x MNOP Internal Pressure. Structural performance were demonstrated by analysis, including state-of-the-art finite element (FE) simulation, and confirmed by tests using a 1/3-scale model. Test results were also used to verify the numerical tool and the methods used in the analyses. All the structural analyses including validation against drop tests were carried out by Arup, and testing were carried out by KAERI. This paper concentrates on the analysis carried out to demonstrate performance in the hypothetical accident 9m free drop scenarios, and results from a small selection of them

Analyses to demonstrate the structural performance of the CASTOR KN12 in hypothetical accident drop accident scenarios

Energy Technology Data Exchange (ETDEWEB)

Diersch, R.; Weiss, M. [Gesellschaft fuer Nuklear-Behaelter mbH (Germany); Tso, C.F. [Arup (United Kingdom); Chung, S.H.; Lee, H.Y. [KHNP-NETEC (Korea)

2004-07-01

CASTORc{sup ircledR} KN-12 is a new cask design by GNB for KHNP-NETEC for dry and wet transportation of up to twelve spent PWR fuel assemblies in Korea. It received its transport license from the Korean Competent Authority KINS in July 2002 and is now in use in South Korea. It has been designed to satisfy the regulatory requirements of the 10 CFR 71 and the IAEA ST-1 for Type B(U)F packages. Its structural performance was demonstrated against the load cases and boundary conditions as defined in 10 CFR 71 and NRC's Regulatory Guide 7.8, and further explained in NUREG 1617. This included normal conditions of transport load cases - including Hot Environment, Cold Environment, Increased External Pressure (140MPa), Minimum External Pressure (24.5kPa), Vibration and shock, and 0.3m free drop - and the hypothetical accident conditions load cases - including the 9m Free Drop, Puncture, Thermal Fire Accident, 200m Water Immersion and 1.5 x MNOP Internal Pressure. Structural performance were demonstrated by analysis, including state-of-the-art finite element (FE) simulation, and confirmed by tests using a 1/3-scale model. Test results were also used to verify the numerical tool and the methods used in the analyses. All the structural analyses including validation against drop tests were carried out by Arup, and testing were carried out by KAERI. This paper concentrates on the analysis carried out to demonstrate performance in the hypothetical accident 9m free drop scenarios, and results from a small selection of them.

Evaluation of Sodium Sulphacetamide drops in the Treatment of ...

African Journals Online (AJOL)

Sodium sulphacetamide eye drops had been used successfully in the past in the treatment of ophthalmia neonatorium (ON) but its use has decreased remarkably in recent time. The efficacy of 10 percent sodium sulphacetamide eye drops in the treatment of ON was prospectively evaluated in 68 neonates seen in our ...

Experimental validation of plugging during drop formation in a T-junction.

Science.gov (United States)

Abate, Adam R; Mary, Pascaline; van Steijn, Volkert; Weitz, David A

2012-04-21

At low capillary number, drop formation in a T-junction is dominated by interfacial effects: as the dispersed fluid flows into the drop maker nozzle, it blocks the path of the continuous fluid; this leads to a pressure rise in the continuous fluid that, in turn, squeezes on the dispersed fluid, inducing pinch-off of a drop. While the resulting drop volume predicted by this "squeezing" mechanism has been validated for a range of systems, as of yet, the pressure rise responsible for the actual pinch-off has not been observed experimentally. This is due to the challenge of measuring the pressures in a T-junction with the requisite speed, accuracy, and localization. Here, we present an empirical study of the pressures in a T-junction during drop formation. Using Laplace sensors, pressure probes we have developed, we confirm the central ideas of the squeezing mechanism; however, we also uncover other findings, including that the pressure of the dispersed fluid is not constant but rather oscillates in anti-phase with that of the continuous fluid. In addition, even at the highest capillary number for which monodisperse drops can be formed, pressure oscillations persist, indicating that drop formation in confined geometries does not transition to an entirely shear-driven mechanism, but to a mechanism combining squeezing and shearing.

Identification of unique cis-element pattern on simulated microgravity treated Arabidopsis by in silico and gene expression

Science.gov (United States)

Soh, Hyuncheol; Choi, Yongsang; Lee, Taek-Kyun; Yeo, Up-Dong; Han, Kyeongsik; Auh, Chungkyun; Lee, Sukchan

2012-08-01

Arabidopsis gene expression microarray (44 K) was used to detect genes highly induced under simulated microgravity stress (SMS). Ten SMS-inducible genes were selected from the microarray data and these 10 genes were found to be abundantly expressed in 3-week-old plants. Nine out of the 10 SMS-inducible genes were also expressed in response to the three abiotic stresses of drought, touch, and wounding in 3-week-old Arabidopsis plants respectively. However, WRKY46 was elevated only in response to SMS. Six other WRKY genes did not respond to SMS. To clarify the characteristics of the genes expressed at high levels in response to SMS, 20 cis-elements in the promoters of the 40 selected genes including the 10 SMS-inducible genes, the 6 WRKY genes, and abiotic stress-inducible genes were analyzed and their spatial positions on each promoter were determined. Four cis-elements (M/T-G-T-P from MYB1AT or TATABOX5, GT1CONSENSUS, TATABOX5, and POLASIG1) showed a unique spatial arrangement in most SMS-inducible genes including WRKY46. Therefore the M/T-G-T-P cis-element patterns identified in the promoter of WRKY46 may play important roles in regulating gene expression in response to SMS. The presences of the cis-element patterns suggest that the order or spatial positioning of certain groups of cis-elements is more important than the existence or numbers of specific cis-elements. Taken together, our data indicate that WRKY46 is a novel SMS inducible transcription factor and the unique spatial arrangement of cis-elements shown in WRKY46 promoter may play an important role for its response to SMS.

Log-normal spray drop distribution...analyzed by two new computer programs

Science.gov (United States)

Gerald S. Walton

1968-01-01

Results of U.S. Forest Service research on chemical insecticides suggest that large drops are not as effective as small drops in carrying insecticides to target insects. Two new computer programs have been written to analyze size distribution properties of drops from spray nozzles. Coded in Fortran IV, the programs have been tested on both the CDC 6400 and the IBM 7094...

Controlling a nuclear reactor with dropped control rods

International Nuclear Information System (INIS)

Mc Atee, K.R.; Alsop, B.H.

1987-01-01

A control system is described for a nuclear power plant including a reactor with a core having an upper portion and a lower portion and control rods which are inserted into and withdrawn from the core of the reactor vertically to control reactivity in the core. The system comprises: means to measure neutron flux separately in the upper portion and the lower portion of the reactor and to generate from such measurements a signal representative of axial distribution of power between the upper and lower portions of the reactor core; means to detect a dropped control rod in the reactor and to generate a dropped rod signal in response thereto; means to generate an axial power distribution limit signal representative of a critical axial power distribution for a dropped rod condition; means to compare the axial power distribution signal to the axial power distribution limit signal and to generate an axial power distribution out of limits signal when the axial power distribution signal exceeds the axial power distribution limit signal; and means responsive only to the presence of both the dropped rod signal and the axial power distribution out of limits signal to generate a signal for shutting the reactor down

Sodium-fuel interaction: dropping experiments and subassembly test

International Nuclear Information System (INIS)

Holtbecker, H.; Schins, H.; Jorzik, E.; Klein, K.

1978-01-01

Nine dropping tests, which bring together 2 to 4 kg of molten UO 2 with 150 l sodium, showed the incoherency and non-violence of these thermal interactions. The pressures can be described by sodium incipient boiling and bubble collapse; the UO 2 fragmentation by thermal stress and bubble collapse impact forces. The mildness of the interaction is principally due to the slowness and incoherency of UO 2 fragmentation. This means that parametric models which assume instantaneous mixing and fragmentation are of no use for the interpretation of dropping experiments. One parametric model, the Caldarola Fuel Coolant Interaction Variable Mass model, is being coupled to the two dimensional time dependent hydrodynamic REXCO-H code. In a first step the coupling is applicated to a monodimensional geometry. A subassembly test is proposed to validate the model. In this test rapid mixing between UO 2 and sodium has to be obtained. Dispersed molten UO 2 fuel is obtained by flashing injected sodium drops inside a UO 2 melt. This flashing is theoretically explained and modelled as a superheat limited explosion. The measured sodium drop dwell times of two experiments are compared to results obtained from the mentioned theory, which is the basis of the Press 2 Code

Structure formation in soft nanocolloids: liquid-drop model.

Science.gov (United States)

Doukas, A-K; Likos, C N; Ziherl, P

2018-04-25

Using a model where soft nanocolloids such as spherical polymer brushes and star polymers are viewed as compressible liquid drops, we theoretically explore contact interactions between such particles. By numerically minimizing the phenomenological free energy consisting of bulk and surface terms, we find that at small deformations the drop-drop interaction is pairwise additive and described by a power law. We also propose a theory to describe the small-deformation regime, and the agreement is very good at all drop compressibilities. The large-deformation regime, which is dominated by many-body interactions, is marked by a rich phase diagram which includes the face- and body-centered-cubic, σ, A15, and simple hexagonal lattice as well as isostructural and re-entrant transitions. Most of these features are directly related to the non-convex deformation free energy emerging from many-body effects in the partial-faceting regime. The phase diagram, which depends on just two model parameters, contains many of the condensed phases observed in experiments. We also provide statistical-mechanical arguments that relate the two model parameters to the molecular architecture of the polymeric nanocolloids, chain rigidity, and solvent quality. The model represents a generic framework for the overarching features of the phase behavior of polymeric nanocolloids at high compressions.

Foamed emulsion drainage: flow and trapping of drops.

Science.gov (United States)

Schneider, Maxime; Zou, Ziqiang; Langevin, Dominique; Salonen, Anniina

2017-06-07

Foamed emulsions are ubiquitous in our daily life but the ageing of such systems is still poorly understood. In this study we investigate foam drainage and measure the evolution of the gas, liquid and oil volume fractions inside the foam. We evidence three regimes of ageing. During an initial period of fast drainage, both bubbles and drops are very mobile. As the foam stabilises drainage proceeds leading to a gradual decrease of the liquid fraction and slowing down of drainage. Clusters of oil drops are less sheared, their dynamic viscosity increases and drainage slows down even further, until the drops become blocked. At this point the oil fraction starts to increase in the continuous phase. The foam ageing leads to an increase of the capillary pressure until the oil acts as an antifoaming agent and the foam collapses.

Spectral Analysis on Time-Course Expression Data: Detecting Periodic Genes Using a Real-Valued Iterative Adaptive Approach

Directory of Open Access Journals (Sweden)

Kwadwo S. Agyepong

2013-01-01

Full Text Available Time-course expression profiles and methods for spectrum analysis have been applied for detecting transcriptional periodicities, which are valuable patterns to unravel genes associated with cell cycle and circadian rhythm regulation. However, most of the proposed methods suffer from restrictions and large false positives to a certain extent. Additionally, in some experiments, arbitrarily irregular sampling times as well as the presence of high noise and small sample sizes make accurate detection a challenging task. A novel scheme for detecting periodicities in time-course expression data is proposed, in which a real-valued iterative adaptive approach (RIAA, originally proposed for signal processing, is applied for periodogram estimation. The inferred spectrum is then analyzed using Fisher’s hypothesis test. With a proper -value threshold, periodic genes can be detected. A periodic signal, two nonperiodic signals, and four sampling strategies were considered in the simulations, including both bursts and drops. In addition, two yeast real datasets were applied for validation. The simulations and real data analysis reveal that RIAA can perform competitively with the existing algorithms. The advantage of RIAA is manifested when the expression data are highly irregularly sampled, and when the number of cycles covered by the sampling time points is very reduced.

Hypothetical accident conditions free drop and thermal tests USA/5791/BLF (ERDA-AL)

International Nuclear Information System (INIS)

Blankenship, R.W.

1980-05-01

The USA/5791/BLF (ERDA-AL) shipping container with rolled-top food pack cans as inner containers is evaluated under conditions required by 10 CFR 71.42. One kilogram of depleted uranium as UO 2 was packaged in each of the inner containers. After completion of a free drop test and a simulated thermal test, the maximum observed leakage of UO 2 for the following week was 3.0 μg. This leakage is well below the allowable leakage per week for most plutonium isotopic mixtures. Using the examples provided, any plutonium isotopic mixture can be easily compared with the allowable leakage per week. Test conditions and results are reported

Modeling and Control of a DFIG-Based Wind Turbine During a Grid Voltage Drop

Directory of Open Access Journals (Sweden)

M. Shahabi

2011-10-01

Full Text Available Doubly-fed induction generators (DFIG are widely used in wind energy generation systems. During a grid voltage drop, performance is degraded with rotor over current deteriorating the fault-ride through (FRT capability of the DFIG wind-energy generation system. In this paper, a complete mathematical DFIG model is proposed. The rotor is considered fed by a voltage source converter whereas the stator is connected to the grid directly. Output power and electromagnetic torque are controlled using field-oriented control (FOC. Simulation results show the efficiency of the controller in exploiting the maximum power of wind.

Experimental research of pressure drop in packed beds of monosized spheres a novel correlation for pressure drop calculation

Directory of Open Access Journals (Sweden)

Stamenić Mirjana S.

2017-01-01

Full Text Available Flow through packed beds of spheres is a complex phenomenon and it has been extensively studied. Although, there is many different correlations there is still no reliable universal equation for prediction of pressure drop. The paper presents the results of experimental research of pressure drop in packed bed of monosized spheres of three different diameters, 8, 11, and 13 mm set within cylindrical vessel of diameter dk = 74 mm, and two different heights of packed bed, hs = 300 and 400 mm. It has been proposed modification of widely used Ergun’s equation in the form of fp = [150+1.3•(Rep/(1-ε]•(1-ε2/(ε3×Rep and new correlation fp = 1/[(27.4-25700•dh/Rep+0.545+6.85•dh] for pressure drop calculation in simple and convenient form for hand and computer calculations. For total number of 362 experimental runs the correlation ratio of the modified Ergun’s relation was CR = 99.3%, and standard deviation SD = 12.2%, while novel relation has CR = 93.7% and SD = 5.4%. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 33049

A kernel regression approach to gene-gene interaction detection for case-control studies.

Science.gov (United States)

Larson, Nicholas B; Schaid, Daniel J

2013-11-01

Gene-gene interactions are increasingly being addressed as a potentially important contributor to the variability of complex traits. Consequently, attentions have moved beyond single locus analysis of association to more complex genetic models. Although several single-marker approaches toward interaction analysis have been developed, such methods suffer from very high testing dimensionality and do not take advantage of existing information, notably the definition of genes as functional units. Here, we propose a comprehensive family of gene-level score tests for identifying genetic elements of disease risk, in particular pairwise gene-gene interactions. Using kernel machine methods, we devise score-based variance component tests under a generalized linear mixed model framework. We conducted simulations based upon coalescent genetic models to evaluate the performance of our approach under a variety of disease models. These simulations indicate that our methods are generally higher powered than alternative gene-level approaches and at worst competitive with exhaustive SNP-level (where SNP is single-nucleotide polymorphism) analyses. Furthermore, we observe that simulated epistatic effects resulted in significant marginal testing results for the involved genes regardless of whether or not true main effects were present. We detail the benefits of our methods and discuss potential genome-wide analysis strategies for gene-gene interaction analysis in a case-control study design. © 2013 WILEY PERIODICALS, INC.

Numerical study on pressure drop and heat transfer for designing sodium-to-air heat exchanger tube banks on advanced sodium-cooled fast reactor

International Nuclear Information System (INIS)

Kang, Hie-Chan; Eoh, Jae-Hyuk; Cha, Jae-Eun; Kim, Seong-O.

2013-01-01

Highlights: ► Numerical simulation for the heat flow characteristic of the sodium-to-air heat exchanger (AHX) and tube banks. ► Parallelogram tube banks showed almost similar thermal and hydraulic characteristics to the rectangular tube banks. ► Pressure drop and heat transfer of the staggered and rectangular tube banks compared with Zhukauskas’ correlation. ► AHX was modeled as porous media and suggested design guide to enhance the performance. - Abstract: A numerical study is performed to investigate the thermal and hydraulic characteristics and build up design model of the AHX (sodium-to-air heat exchanger) unit of a sodium-cooled fast reactor. Helical-coiled tube banks in the AHX are modeled as porous media and simulated heat and momentum transfer by a commercial program. Two-dimensional flow characteristic appears differently at the inlet region of the AHX annulus, and the required length of the inlet region is shorter for an inlet having a 45 degree chamber or a round shape than for one with a perpendicular corner. Pressure drop and heat transfer coefficient for rectangular, parallelogram and staggered tube banks as the main components of the AHX are evaluated and discussed. Pressure drop and heat transfer shows similar trends and underestimated values, respectively, when compared with Zhukauskas empirical correlations. The parallelogram tube bank shows similar results to the rectangular arrangement.

On the Rod Drop technique in integral reactivity measures in control banks and reactor safety

International Nuclear Information System (INIS)

Stefani, Giovanni Laranjo

2013-01-01

This work presents a study on the effect of shading in neutron detectors, when used in measures of reactivity with the rod drop technique. Shading can be understood as a change in the efficiency of the detectors, when it is given in detected neutrons fission occurred in the reactor, more evident in the detectors closest to the bank being inserted. The method of analysis was based on simulations of reactor IPEN/MB-01, using the code CITATION and MCNP program. In both cases, the results were static, showing Neutronic flows in only two situations: before insertion of the control rod and after insertion. The measure of reactivity in this case was achieved using the expression derived from the source jerk technique. In addition to theoretical study, data from a rod drop experiment conducted in the reactor IPEN/MB-01 were also used. In this case, the reactivity was obtained using inverse kinetic method, since experimental data were set of values that vary with time. In all cases, correction factors for the shadowing effect have been proposed. (author)

Construction of the model for the Genetic Analysis Workshop 14 simulated data: genotype-phenotype relationships, gene interaction, linkage, association, disequilibrium, and ascertainment effects for a complex phenotype.

Science.gov (United States)

Greenberg, David A; Zhang, Junying; Shmulewitz, Dvora; Strug, Lisa J; Zimmerman, Regina; Singh, Veena; Marathe, Sudhir

2005-12-30

The Genetic Analysis Workshop 14 simulated dataset was designed 1) To test the ability to find genes related to a complex disease (such as alcoholism). Such a disease may be given a variety of definitions by different investigators, have associated endophenotypes that are common in the general population, and is likely to be not one disease but a heterogeneous collection of clinically similar, but genetically distinct, entities. 2) To observe the effect on genetic analysis and gene discovery of a complex set of gene x gene interactions. 3) To allow comparison of microsatellite vs. large-scale single-nucleotide polymorphism (SNP) data. 4) To allow testing of association to identify the disease gene and the effect of moderate marker x marker linkage disequilibrium. 5) To observe the effect of different ascertainment/disease definition schemes on the analysis. Data was distributed in two forms. Data distributed to participants contained about 1,000 SNPs and 400 microsatellite markers. Internet-obtainable data consisted of a finer 10,000 SNP map, which also contained data on controls. While disease characteristics and parameters were constant, four "studies" used varying ascertainment schemes based on differing beliefs about disease characteristics. One of the studies contained multiplex two- and three-generation pedigrees with at least four affected members. The simulated disease was a psychiatric condition with many associated behaviors (endophenotypes), almost all of which were genetic in origin. The underlying disease model contained four major genes and two modifier genes. The four major genes interacted with each other to produce three different phenotypes, which were themselves heterogeneous. The population parameters were calibrated so that the major genes could be discovered by linkage analysis in most datasets. The association evidence was more difficult to calibrate but was designed to find statistically significant association in 50% of datasets. We also

An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone-Beam CT

Directory of Open Access Journals (Sweden)

Lei Zhu

2008-01-01

Full Text Available Reconstruction algorithms for circular cone-beam (CB scans have been extensively studied in the literature. Since insufficient data are measured, an exact reconstruction is impossible for such a geometry. If the reconstruction algorithm assumes zeros for the missing data, such as the standard FDK algorithm, a major type of resulting CB artifacts is the intensity drop along the axial direction. Many algorithms have been proposed to improve image quality when faced with this problem of data missing; however, development of an effective and computationally efficient algorithm remains a major challenge. In this work, we propose a novel method for estimating the unmeasured data and reducing the intensity drop artifacts. Each CB projection is analyzed in the Radon space via Grangeat's first derivative. Assuming the CB projection is taken from a parallel beam geometry, we extract those data that reside in the unmeasured region of the Radon space. These data are then used as in a parallel beam geometry to calculate a correction term, which is added together with Hu’s correction term to the FDK result to form a final reconstruction. More approximations are then made on the calculation of the additional term, and the final formula is implemented very efficiently. The algorithm performance is evaluated using computer simulations on analytical phantoms. The reconstruction comparison with results using other existing algorithms shows that the proposed algorithm achieves a superior performance on the reduction of axial intensity drop artifacts with a high computation efficiency.

The influence of shoe drop on the kinematics and kinetics of children tennis players.

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Herbaut, Alexis; Chavet, Pascale; Roux, Maxime; Guéguen, Nils; Gillet, Christophe; Barbier, Franck; Simoneau-Buessinger, Emilie

2016-11-01

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12 mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p = .004) and the ankle was less dorsiflexed at foot strike (p = .037). In D0 compared with D12, the peak impact force was reduced by 17% (p = .049), the ankle was less dorsiflexed at foot strike (p = .045) and the knee was more flexed at foot strike (p = .007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p = .658) or the peak ankle plantarflexor moment (p = .071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.

Drop splashing: the role of surface wettability and liquid viscosity

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Almohammadi, Hamed; Amirfazli, Alidad; -Team

2017-11-01

There are seemingly contradictory results in the literature about the role of surface wettability and drop viscosity for the splashing behavior of a drop impacting onto a surface. Motivated by such issues, we conducted a systematic experimental study where splashing behavior for a wide range of the liquid viscosity (1-100 cSt) and surface wettability (hydrophilic to hydrophobic) are examined. The experiments were performed for the liquids with both low and high surface tensions ( 20 and 72 mN/m). We found that the wettability affects the splashing threshold at high or low contact angle values. At the same drop velocity, an increase of the viscosity (up to 4 cSt) promotes the splashing; while, beyond such value, any increase in viscosity shows the opposite effect. It is also found that at a particular combination of liquid surface tension and viscosity (e.g. silicone oil, 10 cSt), an increase in the drop velocity changes the splashing to spreading. We relate such behaviors to the thickness, shape, and the velocity of the drop's lamella. Finally, to predict the splashing, we developed an empirical correlation which covers all of the previous reported data, hence clarifying the ostensible existing contradictions.

Drop-out from a drug treatment clinic and associated reasons.

Science.gov (United States)

Hoseinie, Leila; Gholami, Zhaleh; Shadloo, Behrang; Mokri, Azarakhsh; Amin-Esmaeili, Masoumeh; Rahimi-Movaghar, Afarin

2017-05-01

The aim of this study was to assess drop-out rates and associated reasons among patients at the Iranian National Center for Addiction Studies (INCAS) clinic. In a one-year period (April 2014 to March 2015), all patients with drug dependence who had been referred for treatment and attended for a first assessment were included in this study (N=242). Those who received treatment were followed until March 2016. Survival analysis showed that 70.2% had dropped out from treatment. Log rank test showed that treatment drop-out rates differed between the different approaches used (P < 0.001), with the lowest slope inbuprenorphine maintenance treatment and the highest in the detoxification programme. Drop-out rates within the first three months was 62% (SE= 0.05) and 82.4% (SE=0.03) for opioids and stimulants dependence, respectively. Analyses were performed using SPSS (Version 21.0) and STATA software, (version 13.0). From the patients' perspective, motivational inconsistencies were considered as the main reason for not starting or leaving treatment. The findings of this study could give service providers a better grasp of drop-out rates and the associated reasons.

Bacterial and fungal flora of seagull droppings in Jersey

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Cragg, John; Clayton, Yvonne M.

1971-01-01

In Jersey 166 fresh and 122 dried seagull droppings were obtained and studied locally and in London for the presence of bacteria and fungi of potentially pathogenic nature. There were no salmonella or shigella bacteria isolated from the two groups but there was a high proportion of Candida albicans obtained from the fresh material (21·7%) and only 1·6% from the dry faeces. Cryptococcus neoformans and Histoplasma capsulatum were not found in either the dry or fresh droppings. The normal bacterial and fungal flora of the seagull was established and it is considered that the C. albicans in fresh gull droppings would not materially increase albicans infections in man. PMID:5104846

Polymer Surface Textured with Nanowire Bundles to Repel High-Speed Water Drops.

Science.gov (United States)

Li, Y P; Li, X Y; Zhu, X P; Lei, M K; Lakhtakia, A

2018-05-11

Water drops impacting windshields of high-speed trains and aircraft as well as blades in steam turbine power generators obliquely and at high speeds are difficult to repel. Impacting drops penetrate the void regions of nanotextured and microtextured superhydrophobic coatings, with this pinning resulting in the loss of drop mobility. In order to repel high-speed water drops, we nanotextured polymer surfaces with nanowire bundles separated from their neighbors by microscale void regions, with the nanowires in a bundle separated from their neighbors by nanoscale void regions. Water drops with speeds below a critical speed rebound completely. Water drops with speeds exceeding a critical speed rebound partially, but residual droplets that begin to be pinned undergo a spontaneous dewetting process and slide off. The natural oscillations of residual droplets drive this dewetting process in the interbundle void regions, resulting in a transition from the sticky Wenzel state to the slippery Cassie state without external stimuli.

No-shows, drop-outs and completers in psychotherapeutic treatment

DEFF Research Database (Denmark)

Fenger, Morten Munthe; Mortensen, Erik Lykke; Poulsen, Stig Bernt

2011-01-01

A primary challenge in mental health services is a high rate of non-attendance (i.e. no-show and drop-out) for patients referred to treatment for psychiatric disorders.......A primary challenge in mental health services is a high rate of non-attendance (i.e. no-show and drop-out) for patients referred to treatment for psychiatric disorders....

Gene cluster statistics with gene families.

Science.gov (United States)

Raghupathy, Narayanan; Durand, Dannie

2009-05-01

Identifying genomic regions that descended from a common ancestor is important for understanding the function and evolution of genomes. In distantly related genomes, clusters of homologous gene pairs are evidence of candidate homologous regions. Demonstrating the statistical significance of such "gene clusters" is an essential component of comparative genomic analyses. However, currently there are no practical statistical tests for gene clusters that model the influence of the number of homologs in each gene family on cluster significance. In this work, we demonstrate empirically that failure to incorporate gene family size in gene cluster statistics results in overestimation of significance, leading to incorrect conclusions. We further present novel analytical methods for estimating gene cluster significance that take gene family size into account. Our methods do not require complete genome data and are suitable for testing individual clusters found in local regions, such as contigs in an unfinished assembly. We consider pairs of regions drawn from the same genome (paralogous clusters), as well as regions drawn from two different genomes (orthologous clusters). Determining cluster significance under general models of gene family size is computationally intractable. By assuming that all gene families are of equal size, we obtain analytical expressions that allow fast approximation of cluster probabilities. We evaluate the accuracy of this approximation by comparing the resulting gene cluster probabilities with cluster probabilities obtained by simulating a realistic, power-law distributed model of gene family size, with parameters inferred from genomic data. Surprisingly, despite the simplicity of the underlying assumption, our method accurately approximates the true cluster probabilities. It slightly overestimates these probabilities, yielding a conservative test. We present additional simulation results indicating the best choice of parameter values for data

Effect of rb-bFGF eye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery

Directory of Open Access Journals (Sweden)

Yu Ling

2018-01-01

Full Text Available AIM: To investigate the effect of recombinant bovine basic fibroblast growth factor(rb-bFGFeye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery. METHODS: Totally 80 patients with 80 affected eyes undergoing age-related cataract surgery in our hospital from January 2015 to October 2016 were selected as study subjects, and they were randomly divided into control group and experimental group with 40 patients(40 affected eyesin each group. The two groups were treated with hydroxyl indican eye drops and rb-bFGF eye drops, respectively. The clinical curative effect, inflammation related factors \\〖interleukin 6(IL-6, tumor necrosis factor α(TNF-α\\〗, Schirmer test(SⅠt, break-up time(BUTof tear film, corneal sodium fluorescein staining(FLand scores of dry eye symptoms in the two groups were observed. RESULTS: The total treatment effective rate of experimental group after treatment was significantly higher than that of the control group(90.0% vs 72.5%; χ2=4.021, PP>0.05. After treatment, IL-6, TNF-α, SⅠt, FL score and scores of dry eye symptoms in two groups significantly decreased while BUT significantly increased(PPCONCLUSION: In the treatment of patients after age-related cataract after surgery, rb-bFGF eye drops has more advantages over hydroxyl indican eye drops in regulating the expression of inflammatory factors, improving the tear film stability and relieving dry eye symptoms.

Pressure drop in contraction flow

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