Distribution by Scientific Domains

Kinds of Jet

  • african easterly jet
  • air jet
  • easterly jet
  • free jet
  • impinging jet
  • liquid jet
  • parsec-scale jet
  • plasma jet
  • radio jet
  • relativistic jet
  • round jet

  • Terms modified by Jet

  • jet flow
  • jet fuel
  • jet mixer
  • jet power
  • jet production
  • jet stream
  • jet velocity
  • jet ventilation

  • Selected Abstracts

    Correlations of ELM Frequency with Pedestal Plasma Characteristics

    G. Kamberov
    Abstract JET and ASDEX data for the correlations of ELM's frequency with pedestal plasma temperature and density are compared with a corresponding functional dependence predicted by a classical Fokker-Planck approach. Deviations of the predicted relaxation time from the experimental data are found to increase with the input power. They are discussed in relation with a possible non-diffusional transport of plasma into the SOL. This approach gives opportunity to express the impact of the main engineering factors on ELM's frequency and to extrapolate it for ITER scenaria. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Intrahisian Conduction Disease and Junctional Ectopic Tachycardia

    Junctional ectopic tachycardia (JET) is an uncommon arrhythmia that mainly affects pediatric patients. However, its clinical presentation may rarely occur in adulthood. Owing to its incessant nature, limited responsiveness to antiarrhythmic agents and poor prognosis, catheter ablation of the junctional focus is often required, even though this may be accompanied by the occurrence of complete atrioventricular block. We report the case of a 68-year-old man with episodes of sustained ventricular tachycardia and repetitive JET whose initiation was often anticipated by a sudden intrahisian conduction delay in the immediately preceding sinus beats. [source]

    The linkage between velocity patterns and sediment entrainment in a forced-pool and riffle unit

    D. M. Thompson
    Abstract A field-based project was initiated in order to characterize velocities and sediment entrainment in a forced-pool and riffle sequence. Three-dimensional velocities and turbulence intensities were measured with an acoustic Doppler velocimeter at 222 different points at three similar flows that averaged approximately 4·35 m3 s,1 within a large pool,riffle unit on North Saint Vrain Creek, Colorado. Sediment-sorting patterns were observed with the introduction of 500 tracer particles painted according to initial seeding location. Tracer particles moved sporadically during a 113 day period in response to the annual snowmelt peak flow, which reached a maximum level of 14·8 m3 s,1. Velocity data indicate high instantaneous velocities and turbulence levels in the centre of pools. Patterns of sediment deposition support the notion that stream competence is higher in the pool than the downstream riffle. Flow convergence around a large channel constriction appears to play a major role in multiple processes that include helical flow development and sediment routing, and backwater development with low velocities and turbulence levels above the constriction that may locally limit sediment supply. Jet flow, flow separation, vortex scour and turbulence generation enhance scour in the centre of pools. Ultimately, multiple processes appear to play some role in maintenance of this forced pool and the associated riffle. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Simulation of the intraseasonal and the interannual variability of rainfall over West Africa with RegCM3 during the monsoon period

    M. B. Sylla
    Abstract Intraseasonal and interannual variability of rainfall is simulated using the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3) over West Africa. The intraseasonal variability of rainfall showing three distinct phases and the monsoon jump is well reproduced in the simulation. In addition, the regional model shows that while the monsoon rainbelt moves to the Sahel, the African Easterly Jet (AEJ) undergoes a northward migration and a weakening from June to August, when the core is at its northernmost location. This coexists with the appearance and the strengthening of the Tropical Easterly Jet (TEJ), the development and increased activity of the African Easterly Waves (AEWs), and the intensification and northward shift of the ascent between the AEJ and the TEJ core levels and axis. Similarly, the simulated interannual variability of rainfall over West Africa, the Guinea region, and the Sahel, as well as the variability of atmospheric features during contrasting wet and dry years, is also well captured. In fact, in the simulation during dry years the AEWs activity is decreased while the AEJ is strengthened and migrates southward, the TEJ becomes weaker, and the ascent between the levels of the AEJ and the TEJ decreases. The simulated rainfall variability and the behavior of the related features during the rainy season and during contrasting wet and dry years are in line with previous studies that used observations and reanalysis. We conclude that this model performance is of sufficient quality for application to the study of climate processes and mechanisms over West Africa. Copyright © 2009 Royal Meteorological Society [source]

    Pre-rainy season moisture build-up and storm precipitation delivery in the West African Sahel

    J. Bayo Omotosho
    Abstract The salient differences between the years of above and below normal precipitation, particularly within the long period of 1972,1990 with persistently decreasing Sahelian rainfall, are investigated for Kano, a Nigerian station within the Sahel. Daily rainfall data from 1916 to 2000, storm records from 1951 to 2000 and radiosonde data for three dry and three wet years are used in this study. Results confirm previous findings that the African Easterly Jet (AEJ) located in the 700,600 mb layer is stronger during the dry than in wet years. Significantly, however, it is shown that during the wet years, there is stronger and deeper early season (April,June) build-up of moisture below the AEJ. Furthermore, throughout the period from April to August, the middle troposphere was almost always drier than normal during the dry years and moist than normal in the wet years. Consequent upon these, the storms, which deliver almost all the rainfall in the Sahel, produce at least 150% more precipitation during the wet than in the dry years, though the June to September or annual total number of storms differs by only about 30%. Finally, during the dry years, the onset of rainfall is found to be generally very late compared to the long-term mean, with shorter length of the rainy season. Copyright © 2007 Royal Meteorological Society [source]

    Changes in seasonal mean maximum air temperature in Romania and their connection with large-scale circulation

    Rodica Tomozeiu
    Abstract This paper investigates the temporal and spatial variability of the seasonal mean of maximum air temperature in Romania and its links with the large,scale atmospheric circulation. The Romanian data sets are represented by time series at 14 stations. The large-scale parameters are represented by the observed sea-level pressure (SLP) and geopotential height at 500 hPa (Z500). The period analysed was 1922,98 for winter and 1960,98 for all seasons. Before analysis, the original temperature data were tested to detect for inhomogeneity using the standard normal homogeneity test. Empirical orthogonal functions (EOFs) were used to analyse the spatial and temporal variability of the local and large-scale parameters and to eliminate noise from the original data set. The time series associated with the first EOF pattern of the SLP and mean maximum temperature in Romania were analysed from trend and shifts point of view using the Pettitt and Mann,Kendall tests respectively. The covariance map computed using the Z500 and the seasonal mean of maximum temperature in Romania were used as additional methods to identify the large-scale circulation patterns influencing the local variability. Significant increasing trends were found for winter and summer mean maximum temperature in Romania, with upward shifts around 1947 and 1985 respectively. During autumn, a decreasing trend with a downward shift around 1969 was detected. These changes seem to be real, since they are connected to similar changes in the large-scale circulation. So, the intensification of the southwesterly circulation over Europe since 1933 overlapped with the enhancement of westerly circulation after the 1940s could be the reason for the change in winter mean maximum temperature. The slight weakening of the southwesterly circulation during autumn could be one of the reasons for the decrease in the regime of the mean maximum temperature for autumn seasons. Additionally, the covariance map technique reveals the influence of the North Atlantic oscillation in winter, East Atlantic Jet in summer and Scandinavian (or Euroasia-1) circulation pattern in autumn upon mean maximum air temperature. Copyright © 2002 Royal Meteorological Society. [source]

    A conceptual model for understanding rainfall variability in the West African Sahel on interannual and interdecadal timescales

    S.E. Nicholson
    Abstract This article describes and validates a new conceptual model for understanding Sahel rainfall variability. This conceptual model provides a framework that can readily incorporate and synthesize the roles played by the oceans, the African landmass and local meteorological factors. The most important ,local' factors are the location of the African Easterly Jet (AEJ) and the associated shears. The position of the AEJ helps to distinguish between a ,wet mode' and a ,dry mode' in the Sahel, while other factors determine which of two spatial patterns prevail during years of the dry regime. We test the paradigm by contrasting selected circulation parameters for the years 1958,1967 (representing the wet mode) and 1968,1997 (representing the dry mode). In doing so, we have identified several changes in the general atmospheric circulation that have accompanied the shift to drier conditions. The AEJ is further southward and more intense, the Inter-tropical Convergence Zone (ITCZ) is further south, the Tropical Easterly Jet (TEJ) is weaker, the equatorial westerlies are shallower and weaker, the southwesterly monsoon flow is weaker, and the relative humidity is lower (but not consistently so). The results of this study suggest that the key factor controlling the occurrence of the ,wet Sahel' mode versus the ,dry' mode is the presence of deep, well-developed equatorial westerlies. These displace the AEJ northward into Sahelian latitudes and increase the shear instabilities. The westerlies appear to be at least partially responsible for the well-known association between a weaker AEJ and wetter conditions in the Sahel, because the thermal wind induced by the Sahara/Atlantic temperature gradient is imposed upon a westerly basic state. Since one of the strongest contrasts between the ,wet Sahel' and ,dry Sahel' modes is the strength of the TEJ, the TEJ probably also plays a pivotal role in rainfall variability. In the dry mode, the equatorial westerlies are poorly developed and the core of the AEJ lies well to the south of the Sahel. The dry mode consists of two basic spatial patterns, depending on whether the Guinea Coast Region is anomalously wet or dry (the well-known dipole and no-dipole patterns, respectively). Which occurs is determined by other factors acting to reduce the intensity of the rainbelt. One of the relevant factors appears to be sea-surface temperatures (SSTs) in the Gulf of Guinea. Copyright © 2001 Royal Meteorological Society [source]

    Antibacterial Activity of an Atmospheric Pressure Plasma Jet Against Relevant Wound Pathogens in vitro on a Simulated Wound Environment

    Georg Daeschlein
    Abstract The aim of the study was to test the efficacy of a hand-held atmospheric pressure plasma jet (APPJ) toward typical wound pathogens in vitro simulating antisepsis on wound surfaces. The plasma jet has been proved to be highly effective in vitro against the most commonly encountered pathogenic species of acute and chronic wounds reaching nearly the power of antiseptics. The following bacteria and fungi were treated on half rigid media (agar) imitating wound colonization: methicillin-sensitive Staphylococcus aureus ATCC 1924 (MSSA), Enterococcus faecium ATCC 6057 (EF), Pseudomonas aeruginosa ATCC 15442 (PA), Candida albicans ATCC 10231 (CA), and , -hemolyzing Streptococci of the Lancefield serogroup A (HSA). Highest reduction factor (RF) was obtained treating PA (RF 4.0) followed by HSA (3.2), MSSA (2.7), CA (2.0), and EF (1.9). Consequently, simulating wound surfaces with moist environment using semisolid agar media, the APPJ allowed bactericidal treatment of highly contaminated surfaces of 55,cm2 imitating skin and wound colonization within 6,min. This antibacterial reduction power together with its handsome flexibility of the APPJ could be a suited therapeutic option in the therapy of infected or colonized wounds. [source]

    900-MHz Nonthermal Atmospheric Pressure Plasma Jet for Biomedical Applications

    Jun Choi
    Abstract A portable microwave-excited atmospheric pressure plasma jet (APPJ) using a coaxial transmission line resonator is introduced for applications of plasma biomedicine. Its unique feature includes the portability and no need for matching network and cooling system with high power efficiency, operating at 900,MHz with low ignition power less than 2.5,W in argon at atmospheric pressure. The temperature at the downstream of the APPJ stays less than 47,°C (,320,K) during 5,min of continuous operation. The optical emission spectrum of the APPJ shows various reactive radicals such as OH, NO, and O which are responsible for biomedicine. The APPJ was applied to investigate the acceleration of blood coagulation, which occurred within 20,s of plasma treatment in vitro and within 1,min in vivo. This is significantly faster than the natural coagulation. [source]

    Influence of Cold Plasma Atmospheric Jet on Surface Integrin Expression of Living Cells

    Alexey Shashurin
    Abstract The effects induced in cells due to treatment with cold atmospheric plasma jet are studied. Cell migration rate is measured by means of time-lapse microscopy. In order to characterize cell surface integrin expression, the fluorescent response of cells after surface integrins are stained with specific antibodies is measured by flow cytometry. We show that treatment of cells with plasma jet affects the cells on sub-cellular level, namely decreases expression of cell surface integrins (,1 and ,v integrins were tested). This change in integrin expression might be the original cause for the effects observed on cellular level, such as reduced cell migration rate and cell detachment observed experimentally. [source]

    Plasma Polymerization of HMDSO with an Atmospheric Pressure Plasma Jet for Corrosion Protection of Aluminum and Low-Adhesion Surfaces

    Uwe Lommatzsch
    Abstract Thin functional films were deposited on aluminum with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as precursor. A high dynamic deposition rate on the order of 450,nm,·,m,·,min,1 was achieved. Composition and structure of the thin films show a strong dependence on the downstream location of the precursor injection. A 4,mm downstream shift of the precursor injection increases the carbon content in the thin film by a factor of 2.5, as indicated by XPS analysis and alters the degree of cross-linking according to the FTIR spectra. The coating with the low carbon content (17 at.-%) provides corrosion resistance for aluminum 2024 unclad exposed for 96,h to a neutral salt spray test. The coating with the high carbon content reduces the adhesion of an epoxy resin to the surface and may be used as a release coating. [source]

    A Simple Optical Monitoring Technique for Determining the Geometrical Characteristics of a Plasma Jet

    Boyan E. Djakov
    Abstract Summary: A sensor device is proposed to evaluate the location, size, and shape of a plasma jet. It consists of a small number (e.g., six) of photodetectors arranged in a cross-sectional plane of the jet. Tests of the technique are made by simulations based on CCD images of a plasma jet taken simultaneously from three different angles of view. Photodiode configuration [source]

    Interferometric Insights into the Cycle of Matter

    Katharina Schreyer
    C01 A Multiplicity Survey of the , Oph Molecular Cloud , Preliminary Results C02 Bispectrum Speckle Interferometry of Young Jet- and Outflow-sources [source]

    Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient Air

    S. Al Rabadi
    Abstract Two-dimensional phase Doppler anemometer measurements of droplet size and velocity conducted under several nozzle conditions and a systematic variation of the air mass flow quality and liquid phase viscosity show that the air entrainment process is enhanced when keeping all test conditions constant except for increasing the Newtonian liquid viscosity above of that of water. A two-zone entrainment model based on a variable two-phase entrainment coefficient is proposed with the normalized axial distance allowing for a change in the jet angle. Thus, the jet perimeter is lower and the breakup length is longer in the case of air/relatively higher viscosity liquid phase. It provides the most accurate reproduction of the experimental droplet velocity in comparison with that of other models in the literature and, hence, is recommended for the prediction of the droplet velocity in the case of two-phase air/liquid phase free jet flow in stagnant ambient air. A model for predicting the droplet rain out, considering the droplet trajectories in the free jet flow, allows also for an adequate reproduction of the experimental data. [source]

    Experimental and Numerical Simulation Study of Heat Transfer Due to Confined Impinging Circular Jet

    L. Chang-geng
    Abstract An experimental and numerical simulation study of heat transfer due to a confined impinging circular jet is presented. In this research, a stainless steel foil heated disk was used as the heat transfer surface of a simulated chip, and the thermocouples were mounted symmetrically along the diameter of the foil to measure the temperature distribution on the surface. Driven by a small pump, a circular air jet (1.5,mm and 1,mm in diameter) impinged on the heat-transfer surface with middle and low Reynolds numbers. The parameters, such as Reynolds number and ratio of height-to-diameter, were changed to investigate the radial distribution of the Nusselt number and the characteristics of heat transfer in the stagnation region. Numerical computations were performed by using several different turbulence models. In wall bounded turbulent flows, near-wall modeling is crucial. Therefore, the turbulence models enhanced wall treatment, such as the RNG ,-, model, may be superior for modeling impingement flows. The numerical results showed reasonable agreement with the experimental data for local heat transfer coefficient distributions. The impinging jet may be an effective method to solve the cooling problem of high power density electronic packaging. [source]

    Aerodynamically Assisted Jets: A Paradigm for Directly Microbubbling and Microfoaming Combinations of Advanced Materials,

    ADVANCED MATERIALS, Issue 23 2008
    Sumathy Arumuganathar
    This Communication elucidates the ability to directly microbubble and microfoam suspensions containing structural, functional and/or biological materials. Structural entities such as these having functional gradation could potentially be explored in a plethora of applications within the physical and life sciences. [source]

    Basin-wide warming of the Indian Ocean during El Niño and Indian Ocean dipole years

    J. S. Chowdary
    Abstract Basin-wide wintertime surface warming is observed in the Indian Ocean during El Niño years. The basin-wide warming is found to be stronger when El Niño and Indian Ocean Dipole (IOD) co-occur. The mechanisms responsible for the basin-wide warming are different for the years with El Niño only (El Niño without IOD) and for the co-occurrence (both El Niño and IOD) years. Strong westward propagation of downwelling Rossby waves is observed in the southern Indian Ocean during the IOD years. Such strong propagation is not seen in the case of the El Niño-only years. This indicates that the ocean dynamics play an important role in winter warming of the western Indian Ocean during the IOD years. The weak easterly wind anomalies in the El Niño-only years show no measurable impact on the Wyrtki Jets, but weakening or reversal of these jets is seen in the IOD years. This strongly suggests that the variability related to surface circulation is due to the local IOD forcing rather than El Niño induced wind anomaly. For the El Niño-only composites, surface heat fluxes (mainly latent heat flux and short wave radiation) play an important role in maintaining the basin-wide surface warming in the Indian Ocean. In the IOD-only composites (when there is no El Niño in the Pacific), such basin-wide warming is not seen because of the absence of ENSO (El Niño and Southern Oscillation) induced subsidence over the eastern Indian Ocean. For the years in which both El Niño in the Pacific and dipole in the Indian Ocean co-occur, warming in the western Indian Ocean is due to the ocean dynamics and that in the eastern Indian Ocean is due to the anomalous latent heat flux and solar radiation. Copyright © 2007 Royal Meteorological Society [source]

    Jets from black hole X-ray binaries: testing, refining and extending empirical models for the coupling to X-rays

    R. P. Fender
    ABSTRACT In this paper we study the relation of radio emission to X-ray spectral and variability properties for a large sample of black hole X-ray binary systems. This is done to test, refine and extend , notably into the timing properties , the previously published ,unified model' for the coupling of accretion and ejection in such sources. In 14 outbursts from 11 different sources we find that in every case the peak radio flux, on occasion directly resolved into discrete relativistic ejections, is associated with the bright hard to soft state transition near the peak of the outburst. We also note the association of the radio flaring with periods of X-ray flaring during this transition in most, but not all, of the systems. In the soft state, radio emission is in nearly all cases either undetectable or optically thin, consistent with the suppression of the core jet in these states and ,relic' radio emission from interactions of previously ejected material and the ambient medium. However, these data cannot rule out an intermittent, optically thin, jet in the soft state. In attempting to associate X-ray timing properties with the ejection events we find a close, but not exact, correspondence between phases of very low integrated X-ray variability and such ejections. In fact the data suggest that there is not a perfect one-to-one correspondence between the radio, X-ray spectral or X-ray timing properties, suggesting that they may be linked simply as symptoms of the underlying state change and not causally to one another. We further study the sparse data on the reactivation of the jet during the transition back to the hard state in decay phase of outbursts, and find marginal evidence for this in one case only. In summary we find no strong evidence against the originally proposed model, confirming and extending some aspects of it with a much larger sample, but note that several aspects remain poorly tested. [source]

    Improved Plasma Spray Torch Stability Through Multi-Electrode Design

    J. Schein
    Abstract Coating production by thermal plasma spray is dependent on the residence time of particles in the plasma jet produced by the gas flow inside a plasma torch. To ensure a high fraction of well-molten particles to be accelerated towards the substrate a long reproducible residence time is needed. This can be achieved by a long plasma jet with little or no temporal variation in length and temperature. While single electrode plasma torches need an unstable attachment of the anodic arc root in order to avoid excess erosion, which also causes an unstable plasma jet, multi-electrode torches allow operation with fixed anode attachments by subdividing the anode current by the number of electrodes used, and thereby thus reducing the power input for each separated arc root. Once the steady anode attachment has been obtained the produced plasma jet exhibits a steady characteristic, but also looses rotational symmetry. The separation can be achieved by using either multi anode or multi cathode geometry with appropriate electrical control. Both version have been produced with 3 electrodes each resulting in two systems known as the Delta Gun (3 anodes) and Triplex (3 cathodes). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Experimental determination of saltating glass particle dispersion in a turbulent boundary layer

    H. T. Wang
    Abstract A horizontal saltation layer of glass particles in air is investigated experimentally over a flat bed and also over a triangular ridge in a wind tunnel. Particle concentrations are measured by light scattering diffusion (LSD) and digital image processing, and velocities using particle image velocimetry (PIV). All the statistical moments of the particle concentration are determined such as mean concentration, root mean square concentration fluctuations, skewness and flatness coefficients. Over the flat bed, it is confirmed that the mean concentration decreases exponentially with height, the mean dispersion height being a significant length scale. It is shown that the concentration distribution follows quite well a lognormal distribution. Over the ridge, measurements were made at the top of the ridge and in the cavity region and are compared with measurements without the ridge. On the hill crest, particles are retarded, the saltation layer decreases in thickness and concentration is increased. Downwind of the ridge, particle flow behaves like a jet, in particular no particle return flow is observed. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    The influence of pool length on local turbulence production and energy slope: a flume experiment

    Douglas M. Thompson
    Abstract The in,uence of pool length on the strength of turbulence generated by vortex shedding was investigated in a 6 m long recirculating ,ume. The experiment utilized a 38% constriction of ,ow and an average channel-bed slope of 0·007. The base geometry for the intermediate-length pool experiment originated from a highly simpli,ed, 0·10 scale model of a forced pool from North Saint Vrain Creek, Colorado. Discharge in the ,ume was 31·6 l/s, which corresponds to a discharge in the prototype channel of 10 m3/s. Three shorter and four longer pool lengths also were created with a ,xed bed to determine changes in turbulence intensities and energy slope with pool elongation. Three-dimensional velocities were measured with an acoustic Doppler velocimeter at 31,40 different 0·6-depth and near-bed locations downstream of the rectangular constriction. The average velocity and root mean square (RMS) of the absolute magnitude of velocity at both depths are signi,cantly related to the distance from the constriction in most pool locations downstream of the constriction. In many locations, pool elongation results in a non-linear change in turbulence intensities and average velocity. Based on the overall ,ow pattern, the strongest turbulence occurs in the center of the pool along the shear zone between the jet and recirculating eddy. The lateral location of this shear zone is sensitive to changes in pool length. Energy slope also was sensitive to pool length due to a combination of greater length of the pool and greater head loss with shorter pools. The results indicate some form of hydraulic optimization is possible with pools adjusting their length to adjust the location and strength of turbulent intensities in the center of pools, and lower their rate of energy dissipation. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    A New Echocardiographic Index for Assessing Left Ventricular Function and Mechanism of Mitral Regurgitation and Its Relation to Other Echocardiographic Indices

    ECHOCARDIOGRAPHY, Issue 6 2007
    Cemal Sag M.D.
    Objective: Mitral regurgitation (MR) is a progressive disease of the mitral valve, which can be primary or functional. The assessment of left ventricular function in MR is still troublesome. In this study, we evaluated the validity of a new parameter, total dt, in patients with MR. Methods: Forty patients with severe MR constituted the study group. According to the transesophageal echocardiographic evaluation, the patients were dichotomized into two groups: (1) Primary MR; n = 21, (2) Functional MR; n = 19. The total dt was defined as the sum of time intervals from 1 msto 3 ms (positive dt) and from 3 ms to 1 ms (negative dt) on the CW Doppler recording of MR jet. It was compared to other indices of left ventricular function and left ventricular geometry, including ejection fraction, fractional shortening, myocardial performance index, coaptation distance, left ventricular volume and diameter, sphericity index, and parameters of diastolic function. Result: The total dt correlated with myocardial performance index, coaptation distance, and sphericity index. It could differentiate between primary and functional MR with an area under curve of 0.878, followed by myocardial performance index with 0.860. The total dt > 104 ms was 79% sensitive and 81% specific for discrimination. Conclusion: The total dt is useful for assessing left ventricular function and also for differentiating primary MR from functional MR. [source]

    Diastolic Blood Pressure-Estimated Left Ventricular dp/dt

    ECHOCARDIOGRAPHY, Issue 2 2002
    Hüseyin Y, lmaz M.D.
    Background: Peak dp/dt is one of the best isovolumic phase indexes of the myocardial contractile state requiring invasive procedures or presence of mitral regurgitation severe enough to measure in clinical practice by Doppler echocardiography. In this study, we sought the correlation between two noninvasive methods of measurements for left ventricular dp/dt-diastolic blood pressure- (DBP) estimated and continuous-wave Doppler-derived dp/dt-min electrocardiographic/echocardiographic study to emphasize the clinical feasibility of the DBP-estimated method. Method: Thirty-six randomized patients (27 male, 9 female; 58 ± 8 years) with mild mitral regurgitation were enrolled in this study. DBP-estimated dp/dt was calculated from DBP minus the left ventricular end-diastolic pressure (LVEDP) over the isovolumetric contraction time (IVCT). LVEDP was assumed to be 10 mmHg for all patients. Doppler-determined left ventricular dp/dt was derived from the continuous-wave Doppler spectrum of mitral regurgitation jet by dividing the magnitude of the left ventricular atrial pressure gradient rise between 1 mm/sec,3 mm/sec of mitral regurgitant velocity signal by the time taken for this change. Results: Left ventricular dp/dt by Doppler was 1122 ± 303 mmHg/sec and blood pressure-estimated dp/dt was 1063 ± 294 mmHg/sec. There was a high correlation (r = 0.97, P < 0.001) of dp/dt between the two techniques. Conclusions: DBP and IVCT can generate left ventricular dp/dt without invasive procedures, even in the absence of mitral regurgitation in clinical practice. [source]

    Hydrodynamic Modulation Voltammetry with a Dual Disk Chopped Flow-Microjet Electrode (CF-MJE)

    ELECTROANALYSIS, Issue 18 2003
    Nafeesa Simjee
    Abstract A novel form of hydrodynamic modulation voltammetry (HMV) is described, based on the periodic variation of mass transport in a microjet electrode (MJE) system, in combination with phase-sensitive detection techniques. In the configuration developed, a jet of solution is fired from a nozzle that is aligned directly over the surface of a dual disk Pt-Pt ultramicroelectrode (UME). The potential at each electrode is controlled separately. A rotating blade, positioned between the nozzle and the UME probe, is used to periodically interrupt flow to the electrode surface, resulting in modulation of the overall mass transfer rate between two defined extremes. The use of a dual disk UME enables two transport-limited current signals to be recorded simultaneously, one for the analyte of interest, and the other for a ,reference species' (oxygen for the studies described herein). The latter current response corresponds to the variation in mass transport rate in the chopped flow (CF) arrangement and is used as the signal for phase sensitive detection of the analyte current. Studies of potassium hexachloroiridate (III) [IrCl] oxidation in aqueous solution are used to demonstrate the capabilities of the technique. HMV in the CF-MJE arrangement allows quantitative concentration measurements, down to at least 5×10,7,M. [source]

    Robust gender and age estimation under varying facial pose

    Hironori Takimoto
    Abstract This paper presents a method for gender and age estimation which is robust to changing facial pose. We propose a feature point detection method, called the adapted retinal sampling method (ARSM), and a feature extraction method. A basic concept of the ARSM is to add knowledge about the facial structure to the retinal sampling method. In this method, feature points are detected on the basis of seven points corresponding to facial organs from a facial image. The reason why we used seven points as the basis of feature point detection is that facial organs are conspicuous in the facial region, and are comparatively easy to extract. As features robust to changing facial pose, skin texture, hue, and the Gabor jet are used for gender and age estimation. For classification of gender and estimation of age, we use a multilayered neural network. We also examine the left, right symmetry of faces in connection with gender and age estimation by the proposed method. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(7): 32, 40, 2008; Published online in Wiley InterScience ( DOI 10.1002/ecj.10125 [source]

    Modeling of Coating Process, Phase Changes, and Damage of Plasma Sprayed Thermal Barrier Coatings on Ni-Base Superalloys,

    Tilmann Beck
    The paper gives an overview on the modeling activities on plasma sprayed thermal barrier coating in the frame of TFB 63. In the first part, through-process modeling of the APS deposition of a ZrO2 based TBC is described. Starting from simulation of the plasma jet, heat transfer into the powder particles, particle melting, particle impact on the substrate surface, and solidification is simulated. A homogenization method is introduced to describe the mechanical properties of the resulting TBC. The second part shows simulation of interdiffusion and phase transformations of MCrAlY and intermetallic oxidation protection coatings on several cast Ni-base alloy substrates. Finally, FEM-based damage simulation of oxidation protection coatings by transversal fatigue cracks during thermomechanical fatigue loading as well as by delamination of the TBC during thermocyclic loading is discussed. [source]

    Nanofibers from Laser Spinning: Laser Spinning of Bioactive Glass Nanofibers (Adv. Funct.

    This cover image is a graphical representation of the laser spinning process described by Félix Quintero et al. on page 3084. Laser spinning involves the use of a high power laser to melt a very small volume from a plate of the precursor material. A high speed supersonic gas jet causes the rapid elongation and cooling of the melt, yielding a glass nanofiber. The authors also describe the use of this technique in producing Bioglass nanofibers. [source]

    High Definition Digital Fabrication of Active Organic Devices by Molecular Jet Printing,

    J. Chen
    Abstract We introduce a high resolution molecular jet (MoJet) printing technique for vacuum deposition of evaporated thin films and apply it to fabrication of 30,,m pixelated (800,ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8-hydroxyquinoline) (Alq3) and fabrication of narrow channel (15,,m) organic field effect transistors (OFETs) with pentacene channel and silver contacts. Patterned printing of both organic and metal films is demonstrated, with the operating properties of MoJet-printed OLEDs and OFETs shown to be comparable to the performance of devices fabricated by conventional evaporative deposition through a metal stencil. We show that the MoJet printing technique is reconfigurable for digital fabrication of arbitrary patterns with multiple material sets and high print accuracy (of better than 5,,m), and scalable to fabrication on large area substrates. Analogous to the concept of "drop-on-demand" in Inkjet printing technology, MoJet printing is a "flux-on-demand" process and we show it capable of fabricating multi-layer stacked film structures, as needed for engineered organic devices. [source]

    Fluid flow and heat transfer characteristics of cone orifice jet (effects of cone angle)

    Mizuki Kito
    Abstract The use of a jet from an orifice nozzle with a saddle-backed-shape velocity profile and a contracted flow at the nozzle exit may improve the heat transfer characteristics on an impingement plate because of its larger centerline velocity. However, it requires more power to operate than a common nozzle because of its higher flow resistance. We therefore initially considered the use of a cone orifice nozzle to obtain better heat transfer performance as well as to decrease the flow resistance. We examined the effects of the cone angle , on the cone orifice free jet flow and heat transfer characteristics of the impinging jet. We compared two nozzles: a pipe nozzle and a quadrant nozzle. The first one provides a velocity profile of a fully developed turbulent pipe flow, and the second has a uniform velocity profile at the nozzle exit. We observed a significant enhancement of the heat transfer characteristics of the cone orifice jets at Re=1.5×104. Using the cone orifice impinging jets enhanced the heat transfer rates as compared to the quadrant jet, even when the jets were supplied with the same operational power as the pipe jet. For instance, a maximum enhancement up to approximately 22% at r/do,0.5 is observed for ,=15°. In addition, an increase of approximately 7% is attained as compared to when the pipe jet was used. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( DOI 10.1002/htj.20243 [source]

    Heat transfer and fluid flow characteristics in a swirling impinging jet

    Mamoru Senda
    Abstract An experimental study on heat transfer and fluid flow has been carried out for a swirling round impinging jet. A thermosensitive liquid crystal sheet was used for the heat transfer measurements and the three velocity components were measured with LDV in the stagnation region for cases where the Swirl number Sw = 0.0, 0.22, and 0.45 at the Reynolds number Re = 8100. The formation of recirculation flow due to a swirl near the impinging wall was found to deteriorate the heat transfer coefficient in the stagnation region and results in a more uniform distribution of the Nusselt number with an increasing Swirl number. The heat transfer mechanism of the swirling impinging jet is discussed based on the flow characteristics of the mean velocities and turbulence quantities. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(5): 324,335, 2005; Published online in Wiley InterScience (www.interscience. DOI 10.1002/htj.20068 [source]