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Sample records for horizontal rectangular duct

  1. Sound Radiation Characteristics of a Rectangular Duct with Flexible Walls

    Directory of Open Access Journals (Sweden)

    Praveena Raviprolu

    2016-01-01

    Full Text Available Acoustic breakout noise is predominant in flexible rectangular ducts. The study of the sound radiated from the thin flexible rectangular duct walls helps in understanding breakout noise. The current paper describes an analytical model, to predict the sound radiation characteristics like total radiated sound power level, modal radiation efficiency, and directivity of the radiated sound from the duct walls. The analytical model is developed based on an equivalent plate model of the rectangular duct. This model has considered the coupled and uncoupled behaviour of both acoustic and structural subsystems. The proposed analytical model results are validated using finite element method (FEM and boundary element method (BEM. Duct acoustic and structural modes are analysed to understand the sound radiation behaviour of a duct and its equivalence with monopole and dipole sources. The most efficient radiating modes are identified by vibration displacement of the duct walls and for these the radiation efficiencies have been calculated. The calculated modal radiation efficiencies of a duct compared to a simple rectangular plate indicate similar radiation characteristics.

  2. Natural convection heat transfer along vertical rectangular ducts

    Energy Technology Data Exchange (ETDEWEB)

    Ali, M. [King Saud University, Mechanical Engineering Department, Riyadh (Saudi Arabia)

    2009-12-15

    Experimental investigations have been reported on steady state natural convection from the outer surface of vertical rectangular and square ducts in air. Seven ducts have been used; three of them have a rectangular cross section and the rest have square cross section. The ducts are heated using internal constant heat flux heating elements. The temperatures along the vertical surface and the peripheral directions of the duct wall are measured. Axial (perimeter averaged) heat transfer coefficients along the side of each duct are obtained for laminar and transition to turbulent regimes of natural convection heat transfer. Axial (perimeter averaged) Nusselt numbers are evaluated and correlated using the modified Rayleigh numbers for laminar and transition regime using the vertical axial distance as a characteristic length. Critical values of the modified Rayleigh numbers are obtained for transition to turbulent. Furthermore, total overall averaged Nusselt numbers are correlated with the modified Rayleigh numbers and the area ratio for the laminar regimes. The local axial (perimeter averaged) heat transfer coefficients are observed to decrease in the laminar region and increase in the transition region. Laminar regimes are obtained at the lower half of the ducts and its chance to appear decreases as the heat flux increases. (orig.)

  3. Flow Through a Rectangular-to-Semiannular Diffusing Transition Duct

    Science.gov (United States)

    Foster, Jeff; Wendt, Bruce J.; Reichert, Bruce A.; Okiishi, Theodore H.

    1997-01-01

    Rectangular-to-semiannular diffusing transition ducts are critical inlet components on supersonic airplanes having bifucated engine inlets. This paper documents measured details of the flow through a rectangular-to-semiannular transition duct having an expansion area ratio of 1.53. Three-dimensional velocity vectors and total pressures at the exit plane of the diffuser are presented. Surface oil-flow visualization and surface static pressure data are shown. The tests were conducted with an inlet Mach number of 0.786 and a Reynolds number based on the inlet centerline velocity and exit diameter of 3.2 x 10(exp 6). The measured data are compared with previously published computational results. The ability of vortex generators to reduce circumferential total pressure distortion is demonstrated.

  4. An experimental comparison of nonswirling and swirling flow in a circular-to-rectangular transition duct

    Science.gov (United States)

    Reichert, B. A.; Hingst, W. R.; Okiishi, T. H.

    1991-01-01

    Circular-to-rectangular transition duct flows with and without inlet swirl were investigated experimentally in order to determine the effect of inlet swirl on the transition duct flow field and to provide detailed duct flow data for comparison with numerical code predictions. Coefficients based on detailed measurements of velocity, total pressure and static pressure, acquired in four cross stream planes within a circular-to-rectangular transition duct, with and without inlet swirl, are presented, as are surface static pressure and surface oil film visualization results.

  5. Research on frictional resistance of bubbly flow in rolling rectangular ducts

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Guangyuan, E-mail: ocean06151211@126.com [School of Energy and Power Engineering, Northeast Dianli University, Jilin 132012 (China); Yan, Changqi; Sun, Licheng; Wang, Yang; Yan, Chaoxing [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin 150001 (China)

    2014-10-15

    Highlights: • The frictional resistance of bubbly flow in three rolling rectangular channels is studied. • Additional pressure drop cannot be neglected for duct I with the largest cross section. • The amplitude of frictional pressure drop increases with increase in the height of duct. • New correlation for frictional pressure drop in rolling motion is achieved. - Abstract: For a flow system in a marine vehicle, rolling motion induced by ocean environment usually imposes a periodical force on the system. Experimental investigation was conducted on frictional resistance of bubbly flow in three rectangular ducts in rolling motion. The cross-sections of the three ducts have the same width of 43 mm but different heights of 1.41 mm, 3.25 mm and 9.96 mm. Rolling motion can easily cause the fluctuation of frictional pressure in the rectangular duct with larger height, therefore, a narrow duct is beneficial to restrain the effect of rolling motion on frictional resistance of bubbly flow. The additional pressure drop in ducts with heights of 1.41 mm and 3.25 mm can be neglected. Increasing the gas flow rate and the rolling amplitude or decreasing the rolling period would result in the increase of the fluctuation amplitude of the frictional pressure. A new correlation by modifying the parameter C in the Chisholm correlation was acquired to describe the hydrodynamic performance of bubbly flow for rectangular ducts in rolling motion, showing a good agreement with the experimental data.

  6. Heat transfer in a vertical rectangular duct filled with a porous matrix ...

    African Journals Online (AJOL)

    This paper presents the results of a comprehensive numerical study to analyze free convective heat transfer in a vertical rectangular duct filled with porous matrix and saturated with nanofluid for temperature dependent viscosity. Using the Darcy- Forchhiemer model, the momentum in the porous medium was simulated.

  7. Fully developed magnetohydrodynamic flows in rectangular ducts with insulating walls

    Energy Technology Data Exchange (ETDEWEB)

    Molokov, S. [Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Angewandte Thermo- und Fluiddynamik (IATF)]|[Kernforschungszentrum Karlsruhe GmbH (Germany). Projekt Kernfusion; Shishko, A. [AN Latvijskoj SSR, Riga (Latvia). Inst. Fiziki

    1993-10-01

    In the first part the effect of magnetic field inclination on the flow structure and the pressure drop is considered. The duct walls are insulating. An asymptotic solution to the problem at high Hartmann numbers is obtained. The results show that for a square duct the increase of the pressure gradient due to the field inclination is negligible (less than 10% for any angle). For blanket relevant values of inclination of up to 10 the deviation of the velocity profile from the slug profile is insignificant. The second part studies the flow in a duct with insulating walls parallel to the magnetic field, while the Hartmann walls are covered by an insulating coating. A new type of the boundary condition is derived, which takes into account finite coating resistance. The effect of the latter on the flow characteristics is studied. An exact solution to the problem is obtained and several approximate formulas for the pressure drop at high Hartmann numbers are presented. (orig./HP) [Deutsch] In ersten Teil wird der Einfluss der Magnetfeldneigung auf die Stroemungsform und den Druckverlust betrachtet. Die Kanalwaende sind isoliert. Fuer grosse Hartmann-Zahlen wird eine asymptotische Loesung des Problems hergeleitet. Die Ergebnisse zeigen, dass fuer einen quadratischen Kanal die Erhoehung des Druckverlusts aufgrund der Magnetfeldneigung vernachlaessigbar ist (weniger als 10% fuer beliebige Winkel). Fuer blanket-relevante Neigungen bis 10 ist die Abweichung des Geschwindigkeitsprofils vom kolbenfoermigen Profil nur unbedeutend. Im zweiten Teil wird eine Stroemung in einem Kanal untersucht, dessen Waende parallel zum Magnetfeld isoliert sind, waehrend die Hartmann-Waende mit einer Isolationsschicht ueberzogen sind. Es wird eine neue Randbedingung hergeleitet, die einen endlichen Widerstand der Beschichtung beruecksichtigt. Ihr Einfluss auf die Stroemungsformen wird untersucht. Es wird eine exakte Loesung des Problems entwickelt. Fuer grosse Hartmann-Zahlen werden mehrere

  8. Fully developed liquid-metal flow in multiple rectangular ducts in a strong uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Molokov, S. (Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Angewandte Thermo- und Fluiddynamik (IATF))

    1993-01-01

    Fully developed liquid-metal flow in a straight rectangular duct with thin conducting walls is investigated. The duct is divided into a number of rectangular channels by electrically conducting dividing walls. A strong uniform magnetic field is applied parallel to the outer side walls and dividing walls and perpendicular to the top and the bottom walls. The analysis of the flow is performed by means of matched asymptotics at large values of the Hartmann number M. The asymptotic solution obtained is valid for arbitrary wall conductance ratio of the side walls and dividing walls, provided the top and bottom walls are much better conductors than the Hartmann layers. The influence of the Hartmann number, wall conductance ratio, number of channels and duct geometry on pressure losses and flow distribution is investigated. If the Hartmann number is high, the volume flux is carried by the core, occupying the bulk of the fluid and by thin layers with thickness of order M[sup -1/2]. In some of the layers, however, the flow is reversed. As the number of channels increases the flow in the channels close to the centre approaches a Hartmann-type flow with no jets at the side walls. Estimation of pressure-drop increase in radial ducts of a self-cooled liquid-metal blanket with respect to flow in a single duct with walls of the same wall conductance ratio gives an upper limit of 30%. (author). 13 refs., 10 figs., 1 tab.

  9. Buoyancy effects in vertical rectangular duct with coplanar magnetic field and single sided heat load

    Science.gov (United States)

    Kostichev, P. I.; Poddubnyi, I. I.; Razuvanov, N. G.

    2017-11-01

    In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.

  10. Three-dimensional detonation cellular structures in rectangular ducts using an improved CESE scheme

    KAUST Repository

    Shen, Yang

    2016-11-01

    The three-dimensional premixed H2-O2 detonation propagation in rectangular ducts is simulated using an in-house parallel detonation code based on the second-order space–time conservation element and solution element (CE/SE) scheme. The simulation reproduces three typical cellular structures by setting appropriate cross-sectional size and initial perturbation in square tubes. As the cross-sectional size decreases, critical cellular structures transforming the rectangular or diagonal mode into the spinning mode are obtained and discussed in the perspective of phase variation as well as decreasing of triple point lines. Furthermore, multiple cellular structures are observed through examples with typical aspect ratios. Utilizing the visualization of detailed three-dimensional structures, their formation mechanism is further analyzed.

  11. Study of compressible flow through a rectangular-to-semiannular transition duct

    Science.gov (United States)

    Foster, Jeffry; Okiishi, Theodore H.; Wendt, Bruce J.; Reichert, Bruce A.

    1995-01-01

    Detailed flow field measurements are presented for compressible flow through a diffusing rectangular-to-semiannular transition duct. Comparisons are made with published computational results for flow through the duct. Three-dimensional velocity vectors and total pressures were measured at the exit plane of the diffuser model. The inlet flow was also measured. These measurements are made using calibrated five-hole probes. Surface oil flow visualization and surface static pressure data were also taken. The study was conducted with an inlet Mach number of 0.786. The diffuser Reynolds based on the inlet centerline velocity and the exit diameter of the diffuser was 3,200,000. Comparison of the measured data with previously published computational results are made. Data demonstrating the ability of vortex generators to reduce flow separation and circumferential distortion is also presented.

  12. On the generation of secondary motion in circular to rectangular transition ducts

    Science.gov (United States)

    Demuren, A. O.

    1993-01-01

    A computer code has been developed for the calculation of three-dimensional turbulent flow in circular to rectangular transition ducts. The governing equations are written in a general curvilinear coordinate system so that all singly-connected geometrical configurations can be accommodated. Turbulence closure is through the standard k-epsilon model or a Reynolds stress closure model. Computed results show qualitative agreement with experimental data. Pressure-induced secondary flow is the dominant mode through the transition, but turbulence-induced secondary flow becomes prominent some distance downstream of the transition.

  13. Back-pressure effects on unsteadiness of separation shock in a rectangular duct at Mach 3

    Science.gov (United States)

    Xiong, Bing; Fan, Xiao-qiang; Wang, Yi; Zhou, Liang; Tao, Yuan

    2017-12-01

    To evaluate back-pressure effects on unsteadiness of separation shock in a rectangular duct, some test cases were designed and conducted in a supersonic air-breathing wind tunnel. High-speed Schlieren technique and high-frequency pressure measurements were utilized for data acquisition. Different back-pressure levels were applied by changing downstream throttling ratio. Some parameters for estimating canonical separation flows, such as zero-crossing frequency and intermittency, have been introduced to analyze the duct separation flow. The experimental results show that the separation shock oscillation frequencies increase and the intermittent region lengths decrease with the increasing back-pressure level. A comparison between the unsteadiness of shock/boundary layer interactions for the canonical flow and the duct internal flow were made. It is found that the normalized Strouhal number for the duct internal separation flow ranges from 0.01 to 0.03, which share the similar range with canonical separation flows. That is to say, the physics of separation shock unsteadiness is similar over a wide range of interaction flows, which may share the inherent flow mechanism.

  14. Comparative study on mode-identification algorithms using a phased-array system in a rectangular duct

    Science.gov (United States)

    Suzuki, Takao; Day, Benjamin J.

    2015-07-01

    To identify multiple acoustic duct modes, conventional beam-forming, CLEAN as well as L2 (i.e. pseudo-inverse) and L1 generalized-inverse beam-forming are applied to phased-array pressure data. A tone signal of a prescribed mode or broadband signal is generated upstream of a curved rectangular duct, and acoustic fields formed in both upstream and downstream stations of the test section are measured with identical wall-mounted microphone arrays. Sound-power distributions of several horizontal and vertical modes including upstream- and downstream-propagating waves can be identified with phased-array techniques, and the results are compared among the four approaches. The comparisons using synthetic data demonstrate that the L2 generalized-inverse algorithm can sufficiently suppress undesirable noise levels and detect amplitude distributions accurately in over-determined cases (i.e. the number of microphones is more than the number of cut-on modes) with minimum computational cost. As the number of cut-on modes exceeds the number of microphones (i.e. under-determined problems), the L1 algorithm is necessary to retain better accuracy. The comparison using test data acquired in the curved duct test rig (CDTR) at NASA Langley Research Center suggests that the L1 /L2 generalized-inverse approach as well as CLEAN can improve the dynamic range of the detected mode by as much as 10 dB relative to conventional beam-forming even with mean flow of M=0.5.

  15. An experimental trace gas investigation of fluid transport and mixing in a circular-to-rectangular transition duct

    Science.gov (United States)

    Reichert, B. A.; Hingst, W. R.; Okiishi, T. H.

    1991-01-01

    An ethylene trace gas technique was used to map out fluid transport and mixing within a circular-to-rectangular transition duct. Ethylene gas was injected at several points in a cross stream plane upstream of the transition duct. Ethylene concentration contours were determined at several cross stream measurement planes spaced axially within the duct. The flow involved a uniform inlet flow at a Mach number level of 0.5. Statistical analyses were used to quantitatively interpret the trace gas results. Also, trace gas data were considered along with aerodynamic and surface flow visualization results to ascertain transition duct flow phenomena. Convection of wall boundary layer fluid by vortices produced regions of high total pressure loss in the duct. The physical extent of these high loss regions is governed by turbulent diffusion.

  16. Validation Plan of Turbulence Models for Internal Gas Flow Analysis in a Heated Rectangular Riser Duct

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sin-Yeob; Shin, Dong-Ho; Park, Goon-Cherl; Cho, Hyoung Kyu [Seoul National Univ., Seoul (Korea, Republic of); Kim, Chan-Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    VHTR being developed at Korea Atomic Energy Research Institute adopts an air-cooled Reactor Cavity Cooling System (RCCS) incorporating rectangular riser channels to remove the afterheat emitted from the reactor vessel. Because the performance of RCCS is determined by heat removal rate through the RCCS riser, it is important to understand the heat transfer phenomena in the RCCS riser to ensure the safety of the reactor. In the mixed convection, due to the buoyance force induced by temperature and density differences, local flow structure and heat transfer mode near the heated wall have significantly dissimilar characteristics from both forced convection and free convection. In this study, benchmark calculation was conducted to reproduce the previous statements that V2F turbulence model can capture the mixed convection phenomena with the Shehata's experimental data. Then, the necessity of the model validation for the mixed convection phenomena was confirmed with the CFD analyses for the geometry of the prototype RCCS riser. For the purpose of validating the turbulence models for mixed convection phenomena in the heated rectangular riser duct, validation plan with three experimental tests was introduced. Among them, the flow visualization test facility with preserved cross-section geometry was introduced and a preliminary test result was shown.

  17. Experimental study on the flow separation and self-excited oscillation phenomenon in a rectangular duct

    Science.gov (United States)

    Xiong, Bing; Wang, Zhen-Guo; Fan, Xiao-Qiang; Wang, Yi

    2017-04-01

    To study the characteristics of flow separation and self-excited oscillation of a shock train in a rectangular duct, a simple test case has been conducted and analyzed. The high-speed Schlieren technique and high-frequency pressure measurements have been adopted to collect the data. The experimental results show that there are two separation modes in the duct under M3 incoming condition. The separation mode switch has great effects on the flow effects, such as the pressure distribution, the standard deviation distribution and so on. The separation mode switch can be judged by the history of pressure standard deviation. When it comes to the self-excited oscillation of a shock train, the frequency contents in the undisturbed region, the intermittent region, and the separated bubble have been compared. It was found that the low-frequency disturbance induced by the upstream shock foot motions can travel downstream and the frequency will be magnified by the separation bubble. The oscillation of the small shock foot and the oscillation of the large shock foot are associated with each other rather than oscillating independently.

  18. Linear Stability Analysis of Flow in an Internally Heated Rectangular Duct

    Energy Technology Data Exchange (ETDEWEB)

    Uhlmann, M.

    2004-07-01

    The linear stability of flow in a vertical rectangular duct subject to homogeneous internal heating, constant-temperature no-slip walls and a driving pressure gradient is investigated numerically. A full Chebyshevbased Galerkin method is found to be more reliable than a collocation method, both including the elimination of the pressure and the stream wise velocity from the system of equations and making use of the full symmetry properties. A classification of the mean flow-obtained as a function of Grashof and Reynolds numbers and the geometrical aspect ratio in terms of its inflectional properties is proposed. It is found that the flow loses stability at all aspects rations for a combination of finite thermal buoyancy and pressure forces with opposed sings. In the square duct, the unstable region coincides with the range where additional inflection lines are observed the mean velocity profile. Unstable eigenfunctions are obtained for all basic symmetry modes and their structure can be described as slightly elongated pockets of cross-stream-vertical motion, training each other along the stream wise direction. (Author) 22 refs.

  19. Horizontal ducting of sound by curved nonlinear internal gravity waves in the continental shelf areas.

    Science.gov (United States)

    Lin, Ying-Tsong; McMahon, Kara G; Lynch, James F; Siegmann, William L

    2013-01-01

    The acoustic ducting effect by curved nonlinear gravity waves in shallow water is studied through idealized models in this paper. The internal wave ducts are three-dimensional, bounded vertically by the sea surface and bottom, and horizontally by aligned wavefronts. Both normal mode and parabolic equation methods are taken to analyze the ducted sound field. Two types of horizontal acoustic modes can be found in the curved internal wave duct. One is a whispering-gallery type formed by the sound energy trapped along the outer and concave boundary of the duct, and the other is a fully bouncing type due to continual reflections from boundaries in the duct. The ducting condition depends on both internal-wave and acoustic-source parameters, and a parametric study is conducted to derive a general pattern. The parabolic equation method provides full-field modeling of the sound field, so it includes other acoustic effects caused by internal waves, such as mode coupling/scattering and horizontal Lloyd's mirror interference. Two examples are provided to present internal wave ducts with constant curvature and meandering wavefronts.

  20. imulasi Numerik Aliran Tiga Dimensi Melalui Rectangular Duct dengan Variasi Bukaan Damper

    Directory of Open Access Journals (Sweden)

    Edo Edgar Santosa

    2016-04-01

    Full Text Available Dalam  sistem saluran  terdapat banyak penggunaan elbow dan assesoris lain yang akan menyebabkan terjadinya kerugian tekanan pada aliran. Hal tersebut  disebabkan karena adanya perubahan arah aliran fluida yang melalui saluran tersebut. Nilai penurunan tekanan (pressure drop pada aliran yang melalui suattu saluran dipengaruhi oleh besarnya laju aliran pada inlet, serta radius kelengkungan dari elbow yang akan menyebabkan aliran sekunder kemudian timbul aliran vortex. Hal ini berakibat kerugian energi (headloss yang lebih besar. Peletakan bodi pengganggu dan pemasangan elbow dimaksudkan untuk melihat fenomena aliran di sekitar bodi pengganggu Model uji yang akan digunakan di dalam studi ini berupa rectangular duct yang pada bagian inlet terpasang elbow 90o dengan damper yang diletakkan pada jarak x/Dh=2. Fluida kerjanya adalah udara yang mengalir secara incompressible, viscous, steady dan mempunyai profil kecepatan uniform pada sisi inlet dengan dua variasi bilangan Reynolds yaitu 2.05 x 105 dan 8.2 x 105serta empat pengaturan sudut bodi pengganggu 0o, 10o, 20o, dan 30o Penelitian dilakukan secara  numerik 3D  menggunakan piranti lunak Computation Fluid Dynamics (CFD komersial dengan model turbulensi k-ε Realizable. Hasil studi ini diperoleh bahwa proses recovery aliran dipengaruhi oleh sudut bukaan damper, untuk variasi sudut bukaan damper 30°. Dengan sudut bukaan 30° terjadi percepatan aliran pada daerah dekat dinding yang berakibat bertambahnya momentum aliran sehingga mempercepat proses recovery aliran dan aliran sekunder pada daerah dekat dinding dapat teratasi.

  1. Variance reduction techniques for 14 MeV neutron streaming problem in rectangular annular bent duct

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, Kotaro [Ship Research Inst., Mitaka, Tokyo (Japan)

    1998-03-01

    Monte Carlo method is the powerful technique for solving wide range of radiation transport problems. Its features are that it can solve the Boltzmann`s transport equation almost without approximation, and that the complexity of the systems to be treated rarely becomes a problem. However, the Monte Carlo calculation is always accompanied by statistical errors called variance. In shielding calculation, standard deviation or fractional standard deviation (FSD) is used frequently. The expression of the FSD is shown. Radiation shielding problems are roughly divided into transmission through deep layer and streaming problem. In the streaming problem, the large difference in the weight depending on the history of particles makes the FSD of Monte Carlo calculation worse. The streaming experiment in the 14 MeV neutron rectangular annular bent duct, which is the typical streaming bench mark experiment carried out of the OKTAVIAN of Osaka University, was analyzed by MCNP 4B, and the reduction of variance or FSD was attempted. The experimental system is shown. The analysis model by MCNP 4B, the input data and the results of analysis are reported, and the comparison with the experimental results was examined. (K.I.)

  2. Jamming/flowing transition of non-Brownian particles suspended in a iso-density fluid flowing in a 2D rectangular duct

    Directory of Open Access Journals (Sweden)

    Burel Maxym

    2017-01-01

    Full Text Available We present the results of an experimental study on the jamming/flowing transition. A suspension of neutrally buoyant large particles flows in an horizontal rectangular duct, where an artificial restriction triggers jamming. We show that the avalanche distribution size is exponential, that is memoryless. We further demonstrate that the avalanche size diverges when the restriction size approaches a critical value and that this divergence is well described by a power law. The parameters (critical opening size and divergence velocity are compared to literature values and show a strong similarity with others systems. Another result of this paper is the study of the influence of the particle morphology. We show that, for a moderate restriction size, the dead-zone formed right upstream of the restriction is larger for angular particles but, paradoxically, that the avalanche size is larger for polyhedra compared to spheres by at least one order of magnitude.

  3. Evaporation Heat Transfer of HCFC 22 on the Grooved Surfaces Inside a Horizontal Rectangular Channel

    Science.gov (United States)

    Kido, Osao; Uehara, Haruo

    The evaporation heat transfer performance on six kinds of grooved surface with 0.15 mm to 0.34 mm of the groove pitch was obtained using a rectangular channel. The upper and lower surfaces inside a horizontal rectangular channel, 10 mm in width, 5 mm in height, and 500 mm in length, were heated electrically by Nichrome heaters. HCFC 22 was used as a working fluid. Evaporating pressure was 0.49 MPa, heat flux was 4.65 kW/m2, vapor quality was varied from 0.1 to 0.9, and mass velocity was varied from 86 to 345 kg/(m2s). The empirical correlations to predict the heat transfer coefficients on upper and lower surfaces were proposed. The maximum heat transfer coefficient on upper surface is obtained on the grooved surface with 2 × 10-8 of the modified bond number. Heat transfer coefficient on lower surface isn't influenced by the groove geometries except for lead angle.

  4. Turbulent convection in a horizontal duct with strong axial magnetic field

    Science.gov (United States)

    Zhang, Xuan; Zikanov, Oleg

    2014-11-01

    Convection in a horizontal duct with one heated wall is studied computationally. The work is motivated by the concept of a blanket for fusion reactors, according to which liquid metal slowly flows in toroidal ducts aligned with the main component of the magnetic field. We first assume that the magnetic field is sufficiently strong for the flow to be purely two-dimensional and analyze chaotic flow regimes at very high Grashof numbers. Furthermore, three-dimensional perturbations are considered and the relation between the length of the duct and the critical Hartmann number, below which the flow becomes three-dimensional, is determined. Financial support was provided by the US NSF (Grant CBET 1232851).

  5. Natural convection heat transfer for a staggered array of heated, horizontal cylinders within a rectangular enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Triplett, C.E.

    1996-12-01

    This thesis presents the results of an experimental investigation of natural convection heat transfer in a staggered array of heated cylinders, oriented horizontally within a rectangular enclosure. The main purpose of this research was to extend the knowledge of heat transfer within enclosed bundles of spent nuclear fuel rods sealed within a shipping or storage container. This research extends Canaan`s investigation of an aligned array of heated cylinders that thermally simulated a boiling water reactor (BWR) spent fuel assembly sealed within a shipping or storage cask. The results are presented in terms of piecewise Nusselt-Rayleigh number correlations of the form Nu = C(Ra){sup n}, where C and n are constants. Correlations are presented both for individual rods within the array and for the array as a whole. The correlations are based only on the convective component of the heat transfer. The radiative component was calculated with a finite-element code that used measured surface temperatures, rod array geometry, and measured surface emissivities as inputs. The correlation results are compared to Canaan`s aligned array results and to other studies of natural convection in horizontal tube arrays.

  6. Magnetohydrodynamics in rectangular ducts. Full numerical simulation; Magnetohydrodynamik in Rechteckgeometrien; Volle numerische Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lenhart, L.

    1994-04-01

    Magnetohydrodynamic flow in straight ducts or bends is a key issue, which has to be investigated for developing self-cooled liquid metal blankets of fusion reactors. The code presented solves the full set of governing equations and simulates all phenomena of such flows, including inertial effects. The range of application is limited by computer storage only. (orig./WL)

  7. A simplified mechanical model with fluid–structure interaction for rectangular tank sloshing under horizontal excitation

    Directory of Open Access Journals (Sweden)

    Changfang Zou

    2015-05-01

    Full Text Available Based on the spring–mass model, a novel mechanical model of sloshing with fluid–structure interaction under a horizontal excitation is proposed, and the coupled dynamic equation of sloshing system is established. Considering the flexibility of bulkhead, the effects of certain factors, such as bulkhead bending stiffness and filling ratios, on the mode of coupled sloshing system are investigated. It is found that these factors have significant influence on the mode. By comparing the present results with the results of ADINA based on the linear potential flow theory and published literatures, the proposed coupled sloshing model is verified. The results show that the simplified rigid mass, m 0 , dominates the contributions to bending moment near the bottom of a bulkhead and the spring–mass, m 1 , k 1 , to bending moment near the liquid-free surface of a bulkhead. Furthermore, the computational cost is greatly reduced by using the proposed mechanical model with fluid–structure interaction for a rectangular tank sloshing.

  8. On the onset of secondary flow and unsteady solutions through a loosely coiled rectangular duct for large aspect ratio

    Energy Technology Data Exchange (ETDEWEB)

    Shaha, Poly Rani; Poddar, Nayan Kumar; Mondal, Rabindra Nath, E-mail: rnmondal71@yahoo.com [Department of Mathematics, Jagannath University, Dhaka-1100 (Bangladesh); Rudro, Sajal Kanti [Department of Mathematics, Notredame Colleage, Motijheel, Dhaka (Bangladesh)

    2016-07-12

    The study of flows through coiled ducts and channels has attracted considerable attention not only because of their ample applications in Chemical, Mechanical, Civil, Nuclear and Biomechanical engineering but also because of their ample applications in other areas, such as blood flow in the veins and arteries of human and other animals. In this paper, a numerical study is presented for the fully developed two-dimensional flow of viscous incompressible fluid through a loosely coiled rectangular duct of large aspect ratio. Numerical calculations are carried out by using a spectral method, and covering a wide range of the Dean number, Dn, for two types of curvatures of the duct. The main concern of the present study is to find out effects of curvature as well as formation of secondary vortices on unsteady solutions whether the unsteady flow is steady-state, periodic, multi-periodic or chaotic, if Dn is increased. Time evolution calculations as well as their phase spaces are performed with a view to study the non-linear behavior of the unsteady solutions, and it is found that the steady-state flow turns into chaotic flow through various flow instabilities, if Dn is increased no matter what the curvature is. It is found that the unsteady flow is a steady-state solution for small Dn’s and oscillates periodically or non-periodically (chaotic) between two- and twelve-vortex solutions, if Dn is increased. It is also found that the chaotic solution is weak for small Dn’s but strong as Dn becomes large. Axial flow distribution is also investigated and shown in contour plots.

  9. Peristaltic transport of a Carreau fluid in a compliant rectangular duct

    Directory of Open Access Journals (Sweden)

    Arshad Riaz

    2014-06-01

    Full Text Available The study of peristaltic flow of a Carreau fluid in a compliant rectangular channel has been analyzed in this article. The assumptions of low Reynolds number and long wavelength approximation are utilized here to simplify the complicated governing equations for the three dimensional flow geometry. The resulting highly non-linear partial differential constitutive equations are solved jointly by homotopy perturbation and Eigen function expansion methods. The effects of various physical parameters on velocity distribution have been observed graphically for both two and three dimensional aspects. The trapping scheme has also been discussed by plotting stream lines.

  10. Mixing of Multiple Jets with a Confined Subsonic Crossflow. Part 2; Opposed Rows of Orifices in Rectangular Ducts

    Science.gov (United States)

    Holdeman, J. D.; Liscinsky, D. S.; Bain, D. B.

    1999-01-01

    This paper summarizes experimental and computational results on the mixing of opposed rows of jets with a confined subsonic crossflow in rectangular ducts. The studies from which these results were excerpted investigated flow and geometric variations typical of the complex three-dimensional flowfield in the combustion chambers in gas turbine engines. The principal observation was that the momentum-flux ratio, J, and the orifice spacing, S/H, were the most significant flow and geometric variables. Jet penetration was critical, and penetration decreased as either momentum-flux ratio or orifice spacing decreased. It also appeared that jet penetration remained similar with variations in orifice size, shape, spacing, and momentum-flux ratio when the orifice spacing was inversely proportional to the square-root of the momentum-flux ratio. It was also seen that planar averages must be considered in context with the distributions. Note also that the mass-flow ratios and the orifices investigated were often very large (jet-to-mainstream mass-flow ratio > 1 and the ratio of orifices-area-to-mainstream- cross-sectional-area up to 0.5, respectively), and the axial planes of interest were often just downstream of the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations.

  11. Effects of temperature-dependent viscosity on fluid flow and heat transfer in a helical rectangular duct with a finite pitch

    Directory of Open Access Journals (Sweden)

    Cuihua Wang

    2014-09-01

    Full Text Available An incompressible fully developed laminar flow in a helical rectangular duct having finite pitch and curvature with temperature-dependent viscosity under heating condition is studied in this work. Both the cases of one wall heated and four walls heated are studied. The cross-sectional dimensions of the rectangular duct are 2a and 2b. The aspect ratio n=2b/2a is 0.5. Water is used as the fluid and Reynolds number (Re is varied in the range of 100 to 400. The secondary flow with temperature-dependent viscosity is enhanced markedly as compared to constant viscosity. An additional pair of vortices is obtained near the center of the outer wall at Re=400 for the model of four walls heated with temperature-dependent viscosity, y, while for constant viscosity, the appearance of two additional vortices near the outer wall cannot be found. Besides, the axial velocity decreases and the temperature increases at the central region of the rectangular duct when the temperature-dependent viscosity is considered. Due to the decrease of the viscosity near the walls, the friction factor obtained with temperature-dependent viscosity is lower than that of constant viscosity, while the convective heat transfer for temperature-dependent viscosity is significantly enhanced owing to the strengthened secondary flow. Especially for four heated walls, the effects of viscosity variation on the flow resistance and heat transfer are more significant.

  12. Anatomy of the lamprey ear: morphological evidence for occurrence of horizontal semicircular ducts in the labyrinth of Petromyzon marinus

    Science.gov (United States)

    Maklad, Adel; Reed, Caitlyn; Johnson, Nicholas S.; Fritzsch, Bernd

    2014-01-01

    In jawed (gnathostome) vertebrates, the inner ears have three semicircular canals arranged orthogonally in the three Cartesian planes: one horizontal (lateral) and two vertical canals. They function as detectors for angular acceleration in their respective planes. Living jawless craniates, cyclostomes (hagfish and lamprey) and their fossil records seemingly lack a lateral horizontal canal. The jawless vertebrate hagfish inner ear is described as a torus or doughnut, having one vertical canal, and the jawless vertebrate lamprey having two. These observations on the anatomy of the cyclostome (jawless vertebrate) inner ear have been unchallenged for over a century, and the question of how these jawless vertebrates perceive angular acceleration in the yaw (horizontal) planes has remained open. To provide an answer to this open question we reevaluated the anatomy of the inner ear in the lamprey, using stereoscopic dissection and scanning electron microscopy. The present study reveals a novel observation: the lamprey has two horizontal semicircular ducts in each labyrinth. Furthermore, the horizontal ducts in the lamprey, in contrast to those of jawed vertebrates, are located on the medial surface in the labyrinth rather than on the lateral surface. Our data on the lamprey horizontal duct suggest that the appearance of the horizontal canal characteristic of gnathostomes (lateral) and lampreys (medial) are mutually exclusive and indicate a parallel evolution of both systems, one in cyclostomes and one in gnathostome ancestors.

  13. Prediction of the bed-load transport by gas-liquid stratified flows in horizontal ducts

    CERN Document Server

    Franklin, Erick de Moraes

    2016-01-01

    Solid particles can be transported as a mobile granular bed, known as bed-load, by pressure-driven flows. A common case in industry is the presence of bed-load in stratified gas-liquid flows in horizontal ducts. In this case, an initially flat granular bed may be unstable, generating ripples and dunes. This three-phase flow, although complex, can be modeled under some simplifying assumptions. This paper presents a model for the estimation of some bed-load characteristics. Based on parameters easily measurable in industry, the model can predict the local bed-load flow rates and the celerity and the wavelength of instabilities appearing on the granular bed.

  14. Mixed convection in liquid metal flow in a horizontal duct with strong axial magnetic field

    Science.gov (United States)

    Zhang, Xuan; Zikanov, Oleg

    2016-11-01

    The work is motivated by design of self-cooled liquid-metal breeder blankets for Tokamak fusion reactors. Thermal convection caused by non-uniform internal heating in a liquid metal flow in a horizontal duct with strong axial magnetic field is analyzed numerically. Axial magnetic field is considered strong enough (the Hartmann number up to 104 corresponding to typical reactor condition) to suppress the streamwise variation of the flow, so a two-dimensional fully developed flow is studied. Duct walls are assumed to be thermally and electrically insulated. The non-uniform internal heat deposited by captured neutrons is fully diverted by the mean flow. Realistically high Grashof (up to 1011) and Reynolds (up to 106) numbers are considered. It is found that the state of the flow is strongly affected by the vertical stable stratification developing in response to the streamwise growth of mean temperature. Two flow regimes are identified: the regime with developed transverse convection at moderate Grashof numbers, and the regime, in which convection is suppressed at high Grashof numbers. Financial support was provided by the U.S. National Science Foundation (Grant CBET 1435269) and by the University of Michigan - Dearborn.

  15. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

    Science.gov (United States)

    Elazhary, Amr Mohamed; Soliman, Hassan M.

    2012-10-01

    An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

  16. An analytical algorithm to determine allowable ampacities of horizontally installed rectangular bus bars

    Directory of Open Access Journals (Sweden)

    Klimenta Dardan O.

    2016-01-01

    Full Text Available The main objective of this paper is to propose an algorithm for the determination of the allowable ampacities of single rectangular-section bus bars without the occurrence of correction factors. Without correction factors, the ampacity computation of the copper and aluminium bus bars is fully automatized. The analytical algorithm has been implemented in a computer program code that along with the allowable ampacity can compute the bus bar temperature and the individual heat transfer coefficient for each side of the bus bar, as well as their corresponding power losses. Natural and forced convection correlations for rectangular bus bars are applied. Effects of the solar radiation and radiation heat losses from the bus bar surface are taken into consideration as well. The finite element method (FEM has been used for the linear/non-linear steady-state thermal analysis, i.e. for validation of the analytical algorithm. All FEM-based numerical computations were carried out using the COMSOL Heat Transfer Module. [Projekat Ministarstva nauke Republike Srbije, br. TR33046

  17. 3-D numerical study of the effect of Reynolds number and baffle angle on heat transfer and pressure drop of turbulent flow of air through rectangular duct of very small height

    Directory of Open Access Journals (Sweden)

    Abhijit Paul

    2016-09-01

    Full Text Available Present article illustrates a computational study of three-dimensional steady state heat transfer and high turbulent flow characteristics through a rectangular duct with constant heat fluxed upper wall and single rectangular cross-sectioned baffle insertion at different angles. RNG k–ɛ model along with standard wall function based computations has been accomplished applying the finite volume method, and SIMPLE algorithm has been executed for solving the governing equations. For a Reynolds number, Re of 10,000 to 50,000, Prandtl Number, Pr of 0.707 and baffle angle, α of 30°, 60°, 90°, 120°, 150°, computational studies are executed, centred onto the hydraulic diameter, Dh, test section and hydrodynamic entry length of the duct. Flow field has been solved using Ansys Fluent 14.0 software. Study exposes that baffled rectangular duct has a higher average Nusselt number, Nu and Darcy friction factor, f compared to a smooth rectangular duct. Nu as well as f are found to be maximum at 90° baffle angle. Results illustrate that both α and Re play a significant role in heat transfer as well as flow characteristics and also effects TEF. The correctness of the results attained in this study is corroborated by comparing the results with those existing in the literature for smooth rectangular duct within a precision of ±2% for f and ±4% for Nu.

  18. A numerical model of 2-D sloshing of pseudo-viscous liquids in horizontally accelerated rectangular containers

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.J. [Sandia National Labs., Albuquerque, NM (United States); Ingber, M.S. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mechanical Engineering

    1995-07-01

    A numerical model for simulating the transient nonlinear behavior of 2-D viscous sloshing flows in rectangular containers subjected to arbitrary horizontal accelerations is presented. The potential-flow formulation uses Rayleigh damping to approximate the effects of viscosity, and Lagrangian node movement is used to accommodate violent sloshing motions. A boundary element approach is used to efficiently handle the time-changing fluid geometry. Additionally, a corrected equation is presented for the constraint condition relating normal and tangential derivatives of the velocity potential where the fluid free surface meets the rigid container wall. The numerical model appears to be more accurate than previous sloshing models, as determined by comparison against exact analytic solutions and results of previously published models.

  19. Quantitative observation of co-current stratified two-phase flow in a horizontal rectangular channel

    Directory of Open Access Journals (Sweden)

    Seungtae Lee

    2015-04-01

    The gas superficial velocity varied from 1.2 m/s to 2.0 m/s for air and from 1.2 m/s to 2.8 m/s for steam under a fixed inlet water superficial velocity of 0.025 m/s. Some advanced measurement methods have been applied to measure the local characteristics of the water layer thickness, temperature, and velocity fields in a horizontal stratified flow. The instantaneous velocity and temperature fields inside the water layer were measured using laser-induced fluorescence and particle image velocimetry, respectively. In addition, the water layer thickness was measured through an ultrasonic method.

  20. Numerical and experimental investigation of multiple shock wave/turbulent boundary layer interactions in a rectangular duct

    Science.gov (United States)

    Dutton, J. C.; Carroll, B. F.

    1988-01-01

    Multiple shock wave/turbulent boundary layer interactions in constant or nearly constant area supersonic duct flows occur in a variety of devices including scramjet inlets, gas ejectors, and supersonic wind tunnels. For sufficiently high duct exit pressures, a multiple shock wave/turbulent boundary layer interaction or shock train may form in the duct and cause a highly nonuniform, and possibly unsteady, flow at the duct exit. In this report, the mean flow characteristics of two shock train interactions, one with an initial Mach number of 2.5 the other at Mach 1.6, are investigated using spark Schlieren photography, surface oil flow visualization, and mean wall pressure measurements. The Mach 2.5 interaction was oblique and asymmetric in nature. A large separation occurs after the first oblique shock. The top and bottom wall boundary layer separation has been investigated, revealing that the shape of the reattachment lines and surface flow patterns for the two separation regions are quite different. This oblique shock flow pattern occurs in a neurally stable fashion with each type of opposing separation region alternately existing on either the top or bottom wall during the course of a run. A small scale unsteadiness in the shock train location, with movement on the order of a boundary layer thickness, is also observed.

  1. Experimental investigation of heat transfer and flow pattern from heated horizontal rectangular fin array under natural convection

    Science.gov (United States)

    Taji, S. G.; Parishwad, G. V.; Sane, N. K.

    2014-07-01

    This paper presents results of the experimental study conducted on heated horizontal rectangular fin array under natural convection. The temperature mapping and the prediction of the flow patterns over the fin array with variable fin spacing is carried out. Dimensionless fin spacing to height (S/H) ratio is varied from 0.05 to 0.3 and length to height ratio (L/H) = 5 is kept constant. The heater input to the fin array assembly is varied from 25 to 100 W. The single chimney flow pattern is observed from 8 to 12 mm fin spacing. The end flow is choked below 6 mm fin spacing. The single chimney flow pattern changes to sliding or end flow choking at 6 mm fin spacing. The average heat transfer coefficient (ha) is very small (2.52-5.78 W/m2 K) at 100 W for S = 5-12 mm. The ha is very small (1.12-1.8 W/m2 K) at 100 W for 2-4 mm fin spacing due to choked fin array end condition. The end flow is not sufficient to reach up to central portion of fin array and in the middle portion there is an unsteady down and up flow pattern resulting in sliding chimney. The central bottom portion of fin array channel does not contribute much in heat dissipation for S = 2-4 mm. The ha has significantly improved at higher spacing as compared to lower spacing region. The single chimney flow pattern is preferred from heat transfer point of view. The optimum spacing is confirmed in the range of 8-10 mm. The average heat transfer results are compared with previous literature and showed similar trend and satisfactory agreement. An empirical equation has been proposed to correlate the average Nusselt number as a function of Grashof number and fin spacing to height ratio. The average error for this equation is -0.32 %.

  2. Liquid metal flows in manifolds and expansions of insulating rectangular ducts in the plane perpendicular to a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Molokov, S.

    1994-01-01

    It is demonstrated the flow pattern in basic insulating 3-D geometries for the actual and for more advanced liquid-metal blanket concepts and discussed the ways to avoid pressure losses caused by flow redistribution. Flows in several geometries, such as symmetric and non-symmetric 180 turns with and without manifolds, sharp elbows, sharp and linear expansions with and without manifolds, T-junction, etc., have been calculated. They demonstrate high reliability of poloidal concepts of liquid-metal blankets, since they guarantee uniform conditions for heat transfer. If changes of the duct cross-section occur in the plane perpendicular to the magnetic field (ideally a coolant should flow always in the radial-poloidal plane) the disturbances are local and the slug velocity profile is reached roughly at the distance equivalent to one duct width from the manifolds, expansions, etc. The effects of inertia in these flows are unimportant for the determination of the pressure drop and mean velocity profiles in the core of the flow but may favour heat transfer characteristics via instabilities and strongly anisotropic turbulence. (orig./HP) [Deutsch] Es werden Stroemungsstrukturen in isolierten, dreidimensionalen Basisgeometrien fuer aktuelle und fortgeschrittenere Fluessigmetall-Blankets diskutiert und Wege aufgezeigt, wie Druckverluste hervorgerufen durch Stroemungsumverteilung vermieden werden koennen. Stroemungen in unterschiedlichen Geometrien, wie z.B. in symmetrischen und asymmetrischen Umlenkungen mit und ohne Verzweigung, in scharfkantigen Kruemmern, in linearen Expansionen mit und ohne Verzweigung, in T-Stuecken, etc. werden berechnet. Sie erhoehen die Zuverlaessigkeit von poloidalen Fluessigmetallkonzepten, da sie homogene Waermeuebertragungsbedingungen garantieren. Falls Querschnittsveraenderungen in einer Ebene senkrecht zum Magnetfeld auftreten (unter idealen Bedingungen sollte das Kuehlmittel in der poloidal-radialen Ebene fliessen) sind Stoerungen lokal, und

  3. Linear stability of a non slipping gas flow in a rectangular lined duct with respect to perturbations of the initial value by indefinitely differentiable disturbances having compact support

    Science.gov (United States)

    Balint, Agneta M.; Balint, Stefan; Szabo, Robert

    2012-11-01

    This paper comments on a number of inaccuracies in the article by Brambley [E.J. Brambley, Fundamental problems with the model of uniform flow over acoustic linings, Journal of Sound and Vibration 322(2009)1026-1037] concerning the new concept of "well-posed partial differential equation" introduced in the paper. In particular, the neglect of specifying: the initial and boundary conditions; meaning of solution; conditions assuring existence and uniqueness of the solution; topology in the space of the solutions necessary for analyze the continuous dependence on the initial data and Lyapunov stability. It is shown that, due to the above inaccuracies, the concept introduced by Brambley is confusing, i.e. depending on the set of initial data, boundary conditions, meaning of solution and topology, the same equation can be ill-posed or it can be well-posed. In our paper the concept of well-posed problem, introduced by Hadamard long times ago, is refreshed and applied in the case of rectangular lined duct. Sufficient conditions for that the Briggs-Bers stability criterion can be applied are given. The requirement appearing here, concerning the existence of a finite upper bound of the set of exponential growth rates, is necessary only for assuring the existence of the Laplace transform of the solutions of the partial differential equation from a considered set and not for that the partial differential equation be well-posed.

  4. Thermal convection in a horizontal duct with strong axial magnetic field

    Science.gov (United States)

    Zhang, Xuan; Zikanov, Oleg

    2015-11-01

    The work is motivated by design of liquid metal blankets of nuclear fusion reactors. The effect of convection on the flow within a toroidally oriented duct is analyzed. Non-uniform strong heating arising from capture of high-speed neutrons is imposed internally, while the walls are assumed to be isothermal. Very strong heating (the Grashof number up to 1011) and strong magnetic field (the Hartmann number up to 104) corresponding to the realistic fusion reactor conditions are considered. Stability of two-dimensional flow states is analyzed using numerical simulations. The unstable modes at high Hartmann and Grashof number are found to have large wavelengths. The integral properties of developed three-dimensional flows are close to those of two-dimensional flows at the typical parameters of a fusion reactor. We also consider the effect of the weak transverse component of the magnetic field on the flow. Financial support was provided by the US NSF (Grant CBET 1232851).

  5. Experimental and numerical investigation of an air pocket immersed and immobilized in a horizontal water duct flow

    Energy Technology Data Exchange (ETDEWEB)

    Vassilev, Assen [Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, ECL/UCBL/INSA-Lyon (France) and INSA-Lyon, LMFA, Bat. J. Jacquard, 20 av. A. EINSTEIN, 69621 Villeurbanne Cedex (France)]. E-mail: assen.vassilev@insa-lyon.fr; Ben Hadid, Hamda [Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, ECL/UCBL/INSA-Lyon (France); INSA-Lyon, LMFA, Bat. J. Jacquard, 20 av. A. EINSTEIN, 69621 Villeurbanne Cedex (France); El Hajem, Mahmoud [Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, ECL/UCBL/INSA-Lyon (France); INSA-Lyon, LMFA, Bat. J. Jacquard, 20 av. A. EINSTEIN, 69621 Villeurbanne Cedex (France); Botton, Valery [Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, ECL/UCBL/INSA-Lyon (France); INSA-Lyon, LMFA, Bat. J. Jacquard, 20 av. A. EINSTEIN, 69621 Villeurbanne Cedex (France)

    2007-08-15

    In this work, we carry out an experimental and numerical study of a horizontal elongated air bubble (air pocket) immersed in a liquid flow. For this purpose, an air pocket of large aspect ratio is immobilized in a main liquid duct flow. This particular geometry differs from that of previous works since the air pocket is not influenced by the presence of other bubbles (slug/plug flow). The characteristic zones of the air-water interface are identified experimentally and discussed as a function of the Reynolds number up to 26,000. Two-dimensional and unsteady numerical calculations without mass transfer across the air-water interface are carried out in order to study the behaviour of the air pocket under the same conditions as in the experiment. The features of the results are that the shape of the air pocket and its front are quite well reconstructed by the numerical calculations. However, the comparison of the air pocket length evolution with the experimental data shows a slightly different behaviour attributed to the mass transfer across the air-water interface. The numerical study provides a further insight into the wavy behaviour of the interface that is responsible for the vortices in the air pocket.

  6. Investigation of the Effects of Tire Inflation Pressure and Forward Speed of Driven Wheel on Horizontal Impact of Passing Rectangular Obstacle

    Directory of Open Access Journals (Sweden)

    H Mohammadzadeh

    2013-09-01

    Full Text Available The tire-mechanics models have been developed for the study of wheel movement on the road or soil surface while these models are unlikely to describe the motion of wheels on uneven surfaces. Due to dynamical complexity of this phenomena and the importance of this subject for farm conditions and the wheel carrier devices, the present research aimed to investigate the effects of several parameters on the wheel passing the obstacle. The experiments were carried out using single wheel tester in soil bin condition. The results indicated a relatively linear relationship between the impact force applied on tire and forward speed of wheel and also the height of rectangular obstacle. The effect of inflation pressure was inversed in the range of complete formed tire’s body on impact force and in low levels of tire inflation pressure; tire’s body damps the maximum impact forces. The medium levels of pressure (about 150-200 kPa resulted in less horizontal force that applied on the wheel for different levels of forward speed and obstacle’s height. Tractive force for passing obstacle was increased by raising forward speed and the obstacle’s height.

  7. Horizonte

    OpenAIRE

    BABIANO MARTÍNEZ, CARLOS JOSÉ

    2015-01-01

    Este proyecto intenta ahondar en la idea de horizonte tratado desde la filosofía japonesa y de su nexo con el mundo occidental. De la necesidad latente de una restructuración de la educación para convertirla en una educación estética capaz de permitir a los individuos completarse plenamente como personas. A través de las enseñanzas orientales del zen, del haiku, de filósofos como Tanizaki, y sus ideas sobre la sombra y la sugerencia, frente a Kierkegaard o Schiller en el lado occidental y sus...

  8. Critical heat flux on a flat plate heater located at the middle of a duct in forced flow of pressurized He II

    Science.gov (United States)

    Okamura, T.; Saeki, M.; Hata, K.; Hama, K.; Shirai, Y.; Shiotsu, M.

    2004-09-01

    Critical heat fluxes (CHFs) were measured for two types of rectangular ducts containing horizontal flat plate heaters. One has the flat plate heater of 6 mm wide and 20 mm long located on the inner lower wall at 50 mm from the inlet. The other duct has two horizontal flat plates of 6 mm wide and 20 mm long on inner upper and lower walls at 50 mm from the inlet. The equation of CHF for the forced convection containing a new nondimensional-parameter m introduced in order to calculate cross-sectionally averaged liquid temperature at the center of the duct was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes.

  9. Particle deposition in ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)

    2002-09-01

    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the

  10. Rectangular Seifert circles and arcs system

    OpenAIRE

    ANDO, Tatsuo; Hayashi, Chuichiro; Hayashi, Miwa

    2014-01-01

    Rectangular diagrams of links are link diagrams in the plane ${\\mathbb R}^2$ such that they are composed of vertical line segments and horizontal line segments and vertical segments go over horizontal segments at all crossings. P. R. Cromwell and I. A. Dynnikov showed that rectangular diagrams of links are useful for deciding whether a given link is split or not, and whether a given knot is trivial or not. We show in this paper that an oriented link diagram $D$ with $c(D)$ crossings and $s(D)...

  11. Numerical study of heat transfer enhancement by rectangular winglet vortex generator pair in a channel

    National Research Council Canada - National Science Library

    Zhang, Qiang; Wang, Liang-Bi

    2016-01-01

    A numerical simulation was performed to investigate the effects of longitudinal vortices on the heat transfer enhancement of a laminar flow in a rectangle duct mounted with rectangular winglet pair on the bottom wall...

  12. Experimental investigation of a rapidly rotating turbulent duct flow

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, G.E.; Johansson, A.V. [Department of Mechanics, KTH, 10044 Stockholm (Sweden); Gunnarsson, J. [Bombardier Transportation, Vaesteraas (Sweden); Moberg, H. [Alfa Laval, 14780 Tumba (Sweden)

    2002-09-01

    Rapidly rotating duct flow is studied experimentally with Rotation numbers in the interval. To achieve this, in combination with relatively high Reynolds numbers (5,000-30,000 based on the hydraulic radius), water was used as the working medium. Square and rectangular duct cross-sections were used and the angle between the rotation vector and the main axis of the duct was varied. The influence of the rotation on the pressure drop in the duct was investigated and suitable scalings of this quantity were studied. (orig.)

  13. Bile Duct Exploration

    Science.gov (United States)

    ... Departments Home / Health Library / Articles / Bile Duct Exploration Bile Duct Exploration The CBD is a tube connecting the ... liver and gallbladder to the intestine. When is bile duct exploration performed? If something is blocking the bile ...

  14. Bile Duct Cancer (Cholangiocarcinoma)

    Science.gov (United States)

    ... Home > Types of Cancer > Bile Duct Cancer (Cholangiocarcinoma) Bile Duct Cancer (Cholangiocarcinoma) This is Cancer.Net’s Guide to Bile Duct Cancer (Cholangiocarcinoma). Use the menu below to choose ...

  15. Best connected rectangular arrangements

    Directory of Open Access Journals (Sweden)

    Krishnendra Shekhawat

    2016-03-01

    Full Text Available It can be found quite often in the literature that many well-known architects have employed either the golden rectangle or the Fibonacci rectangle in their works. On contrary, it is rare to find any specific reason for using them so often. Recently, Shekhawat (2015 proved that the golden rectangle and the Fibonacci rectangle are one of the best connected rectangular arrangements and this may be one of the reasons for their high presence in architectural designs. In this work we present an algorithm that generates n-4 best connected rectangular arrangements so that the proposed solutions can be further used by architects for their designs.

  16. Critical Heat Flux on a Flat Plate Located at the Middle of a Duct in Forced Flow of Pressurized He II

    Science.gov (United States)

    Okamura, T.; Saeki, M.; Hata, K.; Hama, K.; Shirai, Y.; Shiotsu, M.

    2004-06-01

    Critical heat fluxes (CHFs) were measured on two horizontal flat plate heaters 6 mm wide and 20 mm long located on inner upper and lower walls of a rectangular duct at 50 mm from the inlet. The duct has 3 mm × 20 mm inner cross sectional area and 100 mm length. The flat plate heaters are made of Manganin and connected electrically in series. Therefore, the ratio of the cross-sectional area of duct to the heater area is 0.25. The measurements were made for the flow velocities from 0 m/s to 2.1 m/s and for the inlet liquid temperatures of 1.6 K, 1.8 K, 1.9 K, 2.0 K and 2.1 K. The measured CHFs were higher for larger flow velocity and lower liquid temperature. The equation of CHF for the forced convection was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes.

  17. Bile Duct Cancer

    Science.gov (United States)

    ... your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. ... the liver get rid of toxins and wastes. Bile duct cancer is rare. It can happen in the ...

  18. Bile Duct Diseases

    Science.gov (United States)

    ... your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. ... toxins and wastes. Different diseases can block the bile ducts and cause a problem with the flow of ...

  19. Effects of ridged walls on the heat transfer in a heated square duct

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.S.; Rodriguez, W.V. [Ciudad Universitaria, Mexico DF (Mexico). Instituto de Ingenieria, UNAM, Coordinacion de Ingenieria de Procesos Industrails y Ambientales, Circuito Interior; Issa, R. [LEGI-MOST, INPG, Grenoble (France)

    2005-05-01

    Turbulent flows in rectangular cooling ducts of rocket engine thrust chambers are characterized by secondary motions of Prandtl's first and second kinds. These secondary currents play a prominent part in heat transfer between the thrust chamber and the cooling gas conveyed in the duct. Previous numerical and experimental works reveal that attaching ridges on the walls of the duct causes the formation of new secondary flows of Prandtl's second kind. These new structures are likely to increase the heat transfer. The present study has investigated numerically, through large eddy simulations, the effects of different forms of ridges on heat transfer in straight square duct flows. (author)

  20. Buckling analysis of rectangular composite plates with rectangular ...

    Indian Academy of Sciences (India)

    Logo of the Indian Academy of Sciences ... A numerical study is carried out using finite element method, to examine the effects of square and rectangular cutout on the buckling behavior of a sixteen ply quasi-isotropic graphite/epoxy symmetrically laminated rectangular composite plate [ 0 ∘ / + 45 ∘ / − 45 ∘ / 90 ∘ ] 2 s ...

  1. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.

    2015-02-06

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon resampling differentiated polynomials into a lower-degree subspace makes differentiation matrices, and operators built from them, rectangular without any row deletions. Then, boundary and interface conditions can be adjoined to yield a square system. The resulting method is both flexible and robust, and avoids ambiguities that arise when applying the classical row deletion method outside of two-point scalar boundary-value problems. The new method is the basis for ordinary differential equation solutions in Chebfun software, and is demonstrated for a variety of boundary-value, eigenvalue and time-dependent problems.

  2. Effects of small boundary perturbation on the MHD duct flow

    Directory of Open Access Journals (Sweden)

    Mahabaleshwar Ulavathi Shettar

    2017-01-01

    Full Text Available In this paper, we investigate the effects of small boundary perturbation on the laminar motion of a conducting fluid in a rectangular duct under applied transverse magnetic field. A small boundary perturbation of magnitude Є is applied on cross-section of the duct. Using the asymptotic analysis with respect to Є, we derive the effective model given by the explicit formulae for the velocity and induced magnetic field. Numerical results are provided confirming that the considered perturbation has nonlocal impact on the asymptotic solution.

  3. Rectangular diagrams of surfaces: representability

    Science.gov (United States)

    Dynnikov, I. A.; Prasolov, M. V.

    2017-06-01

    Introduced here is a simple combinatorial way, which is called a rectangular diagram of a surface, to represent a surface in the three-sphere. It has a particularly nice relation to the standard contact structure on S^3 and to rectangular diagrams of links. By using rectangular diagrams of surfaces it is intended, in particular, to develop a method to distinguish Legendrian knots. This requires a lot of technical work of which the present paper addresses only the first basic question: which isotopy classes of surfaces can be represented by a rectangular diagram? Roughly speaking, the answer is this: there is no restriction on the isotopy class of the surface, but there is a restriction on the rectangular diagram of the boundary link arising from the presentation of the surface. The result extends to Giroux's convex surfaces for which this restriction on the boundary has a natural meaning. In a subsequent paper, transformations of rectangular diagrams of surfaces will be considered and their properties will be studied. By using the formalism of rectangular diagrams of surfaces an annulus in S^3 is produced here that is expected to be a counterexample to the following conjecture: if two Legendrian knots cobound an annulus and have zero Thurston-Bennequin numbers relative to this annulus, then they are Legendrian isotopic. Bibliography: 30 titles.

  4. Bile duct obstruction

    Science.gov (United States)

    ... to the biliary system Liver and bile duct worms (flukes) The risk factors include: History of gallstones, ... In: Walker BR, Colledge NR, Ralston SH, Perman ID, eds. Davidson's Principles and Practice of Medicine. 22nd ...

  5. Mammary Duct Ectasia

    Science.gov (United States)

    ... lumps Mammary duct ectasia Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  6. Horizontal Accelerator

    Data.gov (United States)

    Federal Laboratory Consortium — The Horizontal Accelerator (HA) Facility is a versatile research tool available for use on projects requiring simulation of the crash environment. The HA Facility is...

  7. Melting Process of Clathrate in a Rectangular Cell

    Science.gov (United States)

    Chiba, Takashi; Okada, Masashi; Matsumoto, Koji

    In order to clarify the mechanism of heat transfer during melting of a clathrate in rectangular cells, two melting processes, namely, two-dimensional melting process with natural convection from a vertical wall and one-dimensional melting process by heat conduction from an upper horizontal wall, are studied experimentally. The R-141b was used for generating clathrate. One experiment was carried out by melting the clathrate filled into a 150mm high and 100mm wide rectangular cell from a vertical wall. And in the other experiment, the clathrate was melted from the upper horizontal wall of a rectangular cell with 88mm height and 180mm width. The temperature distributions in cells were measured. The melting front was measured by pictures taken on fixed times. The concentration of freon in the melt was measured by gas-chromatography. The following results are obtained. (1) In the melting process, the clathrate decomposes into an emulsion region which is a water-freon mixture and a liquid freon region under the emulsion. (2) Concentration gradient of freon in the emulsion plyas an important role in the natural convection in the melt. The Nusselt number on the heated vertical wall is depressed by the concentration gradients.

  8. Curved-Duct

    Directory of Open Access Journals (Sweden)

    Je Hyun Baekt

    2000-01-01

    Full Text Available A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a 90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a 90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.

  9. Patent arterial duct

    Directory of Open Access Journals (Sweden)

    Martin Robin P

    2009-07-01

    Full Text Available Abstract Patent arterial duct (PAD is a congenital heart abnormality defined as persistent patency in term infants older than three months. Isolated PAD is found in around 1 in 2000 full term infants. A higher prevalence is found in preterm infants, especially those with low birth weight. The female to male ratio is 2:1. Most patients are asymptomatic when the duct is small. With a moderate-to-large duct, a characteristic continuous heart murmur (loudest in the left upper chest or infraclavicular area is typical. The precordium may be hyperactive and peripheral pulses are bounding with a wide pulse pressure. Tachycardia, exertional dyspnoea, laboured breathing, fatigue or poor growth are common. Large shunts may lead to failure to thrive, recurrent infection of the upper respiratory tract and congestive heart failure. In the majority of cases of PAD there is no identifiable cause. Persistence of the duct is associated with chromosomal aberrations, asphyxia at birth, birth at high altitude and congenital rubella. Occasional cases are associated with specific genetic defects (trisomy 21 and 18, and the Rubinstein-Taybi and CHARGE syndromes. Familial occurrence of PAD is uncommon and the usual mechanism of inheritance is considered to be polygenic with a recurrence risk of 3%. Rare families with isolated PAD have been described in which the mode of inheritance appears to be dominant or recessive. Familial incidence of PAD has also been linked to Char syndrome, familial thoracic aortic aneurysm/dissection associated with patent arterial duct, and familial patent arterial duct and bicuspid aortic valve associated with hand abnormalities. Diagnosis is based on clinical examination and confirmed with transthoracic echocardiography. Assessment of ductal blood flow can be made using colour flow mapping and pulsed wave Doppler. Antenatal diagnosis is not possible, as PAD is a normal structure during antenatal life. Conditions with signs and symptoms of

  10. Oblique bile duct predisposes to the recurrence of bile duct stones.

    Science.gov (United States)

    Strnad, Pavel; von Figura, Guido; Gruss, Regina; Jareis, Katja-Marlen; Stiehl, Adolf; Kulaksiz, Hasan

    2013-01-01

    Bile stones represent a highly prevalent condition and abnormalities of the biliary tree predispose to stone recurrence due to development of biliary stasis. In our study, we assessed the importance of an altered bile duct course for stone formation. 1,307 patients with choledocholithiasis in the absence of any associated hepatobiliary disease who underwent endoscopic retrograde cholangiopancreatography (ERCP) between 2002 and 2009 were analysed. The angle enclosed between the horizontal portion of the common bile duct (CBD) and the horizontal plane was measured (angle α). Oblique common bile duct (OCBD) was defined as a CBD with angle α < 45°. 103 patients (7.9%) were found to harbour OCBD and these were compared to 104 randomly selected control subjects. Compared to controls, OCBD patients were (i) significantly older (72 ± 13 vs. 67 ± 13, p<0.00001); (ii) more frequently underwent a cholecystectomy (p = 0.02) and biliary surgery (p = 0.003) prior to the diagnosis and (iii) more often developed chronic pancreatitis (p = 0.04) as well as biliary fistulae (p = 0.03). Prior to and after ERCP, OCBD subjects displayed significantly elevated cholestatic parameters and angle α negatively correlated with common bile duct diameter (r = -0.29, p = 0.003). OCBD subjects more often required multiple back-to-back ERCP sessions to remove bile stones (p = 0.005) as well as more ERCPs later on due to recurrent stone formation (p<0.05). OCBD defines a novel variant of the biliary tree, which is associated with chronic cholestasis, hampers an efficient stone removal and predisposes to recurrence of bile duct stones.

  11. Oblique bile duct predisposes to the recurrence of bile duct stones.

    Directory of Open Access Journals (Sweden)

    Pavel Strnad

    Full Text Available BACKGROUND AND STUDY AIMS: Bile stones represent a highly prevalent condition and abnormalities of the biliary tree predispose to stone recurrence due to development of biliary stasis. In our study, we assessed the importance of an altered bile duct course for stone formation. PATIENTS AND METHODS: 1,307 patients with choledocholithiasis in the absence of any associated hepatobiliary disease who underwent endoscopic retrograde cholangiopancreatography (ERCP between 2002 and 2009 were analysed. The angle enclosed between the horizontal portion of the common bile duct (CBD and the horizontal plane was measured (angle α. Oblique common bile duct (OCBD was defined as a CBD with angle α < 45°. RESULTS: 103 patients (7.9% were found to harbour OCBD and these were compared to 104 randomly selected control subjects. Compared to controls, OCBD patients were (i significantly older (72 ± 13 vs. 67 ± 13, p<0.00001; (ii more frequently underwent a cholecystectomy (p = 0.02 and biliary surgery (p = 0.003 prior to the diagnosis and (iii more often developed chronic pancreatitis (p = 0.04 as well as biliary fistulae (p = 0.03. Prior to and after ERCP, OCBD subjects displayed significantly elevated cholestatic parameters and angle α negatively correlated with common bile duct diameter (r = -0.29, p = 0.003. OCBD subjects more often required multiple back-to-back ERCP sessions to remove bile stones (p = 0.005 as well as more ERCPs later on due to recurrent stone formation (p<0.05. CONCLUSION: OCBD defines a novel variant of the biliary tree, which is associated with chronic cholestasis, hampers an efficient stone removal and predisposes to recurrence of bile duct stones.

  12. Turbofan Duct Propagation Model

    Science.gov (United States)

    Lan, Justin H.; Posey, Joe W. (Technical Monitor)

    2001-01-01

    The CDUCT code utilizes a parabolic approximation to the convected Helmholtz equation in order to efficiently model acoustic propagation in acoustically treated, complex shaped ducts. The parabolic approximation solves one-way wave propagation with a marching method which neglects backwards reflected waves. The derivation of the parabolic approximation is presented. Several code validation cases are given. An acoustic lining design process for an example aft fan duct is discussed. It is noted that the method can efficiently model realistic three-dimension effects, acoustic lining, and flow within the computational capabilities of a typical computer workstation.

  13. Nasopalatine Duct Cyst

    Directory of Open Access Journals (Sweden)

    Pratik Dedhia

    2013-01-01

    Full Text Available The nasopalatine cyst is the most common epithelial and nonodontogenic cyst of the maxilla. The cyst originates from epithelial remnants from the nasopalatine duct. The cells may be activated spontaneously during life or are eventually stimulated by the irritating action of various agents (infection, etc.. It is different from a radicular cyst. The definite diagnosis should be based on clinical, radiological, and histopathological findings. The treatment is enucleation of the cystic tissue, and only in rare cases a marsupialisation needs to be performed. A case of a nasopalatine duct cyst in a 35-year-old male is reviewed. The typical radiologic and histological findings are presented.

  14. Bile Duct Exploration

    Science.gov (United States)

    ... 223.2273 Request an Appointment Contact Us Share Facebook Twitter Linkedin Email Bile Duct Exploration Menu Print Full Article Overview Test Details Results and Follow-Up Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We ...

  15. Duct Leakage Repeatability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-08-01

    The purpose of this report is to evaluate the repeatability of the three most significant measurement techniques for duct leakage using data from the literature and recently obtained field data. We will also briefly discuss the first two factors. The main question to be answered by this study is to determine if differences in the repeatability of these tests methods is sufficient to indicate that any of these methods is so poor that it should be excluded from consideration as an allowed procedure in codes and standards. The three duct leak measurement methods assessed in this report are the two duct pressurization methods that are commonly used by many practitioners and the DeltaQ technique. These are methods B, C and A, respectively of the ASTM E1554 standard. Although it would be useful to evaluate other duct leak test methods, this study focused on those test methods that are commonly used and are required in various test standards, such as BPI (2010), RESNET (2014), ASHRAE 62.2 (2013), California Title 24 (CEC 2012), DOE Weatherization and many other energy efficiency programs.

  16. Connecting device for air ducts

    Energy Technology Data Exchange (ETDEWEB)

    Kippenberger, G.

    1979-11-29

    The connecting device for air ducts described consists of matched coupling elements of great tensile strength in the form of eyes and cords, which are fitted on the front of the air duct sections. There is a sleeve apron on one side which projects into the other section of air duct.

  17. Cornice Duct System

    Energy Technology Data Exchange (ETDEWEB)

    Wayne Place; Chuck Ladd

    2004-10-29

    SYNERGETICS, INC., has designed, developed, and tested an air handling duct system that integrates the air duct with the cornice trim of interior spaces. The device has the advantage that the normal thermal losses from ducts into unconditioned attics and crawl spaces can be totally eliminated by bringing the ducts internal to the conditioned space. The following report details work conducted in the second budget period to develop the Cornice Duct System into a viable product for use in a variety of residential or small commercial building settings. A full-scale prototype has been fabricated and tested in a laboratory test building at the Daylighting Facility at North Carolina State University., Based on the results of that testing, the prototype design as been refined, fabricated, installed, and extensively tested in a residential laboratory house. The testing indicates that the device gives substantially superior performance to a standard air distribution system in terms of energy performance and thermal comfort. Patent Number US 6,511,373 B2 has been granted on the version of the device installed and tested in the laboratory house. (A copy of that patent is attached.) Refinements to the device have been carried through two additional design iterations, with a particular focus on reducing installation time and cost and refining the air control system. These new designs have been fabricated and tested and show substantial promise. Based on these design and testing iterations, a final design is proposed as part of this document. That final design is the basis for a continuation in part currently being filed with the U.5, Patent office.

  18. A study of high speed flows in an aircraft transition duct. Ph.D. Thesis - Iowa State Univ.

    Science.gov (United States)

    Reichert, Bruce A.

    1991-01-01

    The study of circular-to-rectangular transition duct flows with and without inlet swirl is presented. A method was devised to create a swirling, solid body rotational flow with minimal associated disturbances. Details of the swirl generator design and construction are discussed. Coefficients based on velocities and total and static pressures measured in cross stream planes at four axial locations within the transition duct along with surface static pressures and surface oil film visualization are presented for both nonswirling and swirling incoming flows. A method was developed to acquire trace gas measurements within the transition duct at high flow velocities. Statistical methods are used to help interpret the trace gas results.

  19. Rare bile duct anomaly: B3 duct draining to gallbladder

    Directory of Open Access Journals (Sweden)

    Seung Eun Lee

    2016-01-01

    Full Text Available A 10-year-old girl presented with recurrent right upper abdominal pain and dyspepsia. Magnetic resonance cholangiopancreatography revealed a dilated common channel of intrahepatic bile duct of segment 3 (B3 and segment 4 (B4 drained into the gallbladder directly. The patient underwent laparoscopic cholecystectomy and Roux-en Y hepaticojejunostomy (B3-jejunostomy. Among the anatomical variability of the biliary system, the cholecystohepatic ducts are controversial in existence and incidence. We report a very rare variant of a cholecystohepatic duct in which the B3 duct drained into gallbladder directly and to the best of our knowledge this is the first report.

  20. Using two soft computing methods to predict wall and bed shear stress in smooth rectangular channels

    Science.gov (United States)

    Khozani, Zohreh Sheikh; Bonakdari, Hossein; Zaji, Amir Hossein

    2017-11-01

    Two soft computing methods were extended in order to predict the mean wall and bed shear stress in open channels. The genetic programming (GP) and Genetic Algorithm Artificial Neural Network (GAA) were investigated to determine the accuracy of these models in estimating wall and bed shear stress. The GP and GAA model results were compared in terms of testing dataset in order to find the best model. In modeling both bed and wall shear stress, the GP model performed better with RMSE of 0.0264 and 0.0185, respectively. Then both proposed models were compared with equations for rectangular open channels, trapezoidal channels and ducts. According to the results, the proposed models performed the best in predicting wall and bed shear stress in smooth rectangular channels. The obtained equation for rectangular channels could estimate values closer to experimental data, but the equations for ducts had poor, inaccurate results in predicting wall and bed shear stress. The equation presented for trapezoidal channels did not have acceptable accuracy in predicting wall and bed shear stress either.

  1. Using two soft computing methods to predict wall and bed shear stress in smooth rectangular channels

    Science.gov (United States)

    Khozani, Zohreh Sheikh; Bonakdari, Hossein; Zaji, Amir Hossein

    2017-03-01

    Two soft computing methods were extended in order to predict the mean wall and bed shear stress in open channels. The genetic programming (GP) and Genetic Algorithm Artificial Neural Network (GAA) were investigated to determine the accuracy of these models in estimating wall and bed shear stress. The GP and GAA model results were compared in terms of testing dataset in order to find the best model. In modeling both bed and wall shear stress, the GP model performed better with RMSE of 0.0264 and 0.0185, respectively. Then both proposed models were compared with equations for rectangular open channels, trapezoidal channels and ducts. According to the results, the proposed models performed the best in predicting wall and bed shear stress in smooth rectangular channels. The obtained equation for rectangular channels could estimate values closer to experimental data, but the equations for ducts had poor, inaccurate results in predicting wall and bed shear stress. The equation presented for trapezoidal channels did not have acceptable accuracy in predicting wall and bed shear stress either.

  2. Analysis of sound propagation in ducts using the wave envelope concept

    Science.gov (United States)

    Baumeister, K. J.

    1974-01-01

    A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow for plane wave input. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution does not oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude, and the number of grid points becomes independent of the sound frequency. Physically, the transformed pressure represents the amplitude of the conventional sound wave. Example solutions are presented for sound propagation in a one-dimensional straight hard-wall duct and in a two-dimensional straight soft-wall duct without steady flow. The numerical solutions show evidence of the existence along the duct wall of a developing acoustic pressure diffusion boundary layer which is similar in nature to the conventional viscous flow boundary layer. In order to better illustrate this concept, the wave equation and boundary conditions are written such that the frequency no longer appears explicitly in them. The frequency effects in duct propagation can be visualized solely as an expansion and stretching of the suppressor duct.

  3. Freezing in forced convection flows inside ducts: A review

    Science.gov (United States)

    Weigand, B.; Braun, J.; Neumann, S. O.; Rinck, K. J.

    The present work gives an overview about the recent developments in research on freezing phenomena in forced convection flows inside ducts. Emphasis is given to the fundamental aspects of the phenomena observed in the solidification processes as well as on the analytical and numerical modelling aspects for this kind of problems. The paper deals with solidification problems inside tubes, parallel plate channels, curved rectangular channels and in diverging rectangular channels. Additionally, some new experimental and numerical results on solidification in duct flows are shown from the current research program in Darmstadt on freezing phenomena. Zusammenfassung Die vorliegende Arbeit gibt einen Überblick über aktuelle Forschungsentwicklungen auf dem Gebiet des Gefrierens in durchströmten Kanälen. Der Schwerpunkt wird auf die grundsätzlichen Aspekte gelegt, die sowohl bei den beobachteten Gefriervorgängen selbst, als auch bei deren analytischer oder numerischer Modellierung von Bedeutung sind. Der Artikel befaßt sich mit Gefriervorgängen in Rohren, zwischen parallelen Platten, gekrümmten, rechteckigen Kanälen und divergenten, rechteckigen Kanälen. Darüberhinaus werden einige aktuelle Ergebnisse beim Erstarren von Wasser in Kanalströmungen aus den laufenden Forschungsarbeiten in Darmstadt vorgestellt.

  4. Magnetophoresis Effects on the Flow Characteristics of Oil-Based Ferrofluids in Rectangular Enclosures.

    Science.gov (United States)

    Seo, Hyeon-Seok; Boo, Jin-Hyo; Kim, Youn-Jea

    2015-10-01

    This study numerically investigated the flow characteristics in a rectangular enclosure filled with oil-based ferrofluid (EFH-1, Ferrotec.) under the influence of external magnetic fields. The rectangular enclosure contained obstacles with different shapes, such as a rectangle and a triangle mounted on the top and bottom wall surfaces. In order to generate external magnetic fields, a permanent magnet was located in the lower part of the rectangular enclosure, and its direction was selected to be either horizontal or vertical. Our results showed that the ferrofluid flow fields were affected by the applied external magnetic field direction and eddy flow phenomena in the working fluid were generated in the vicinity of high magnetic flux density distributions, such as at the edge of the permanent magnet. It was also confirmed that the magnetophoretic force distributions in the analysis model played a significant role in the development of the ferrofluid flow fields.

  5. Propagation of sound waves in ducts

    DEFF Research Database (Denmark)

    Jacobsen, Finn

    2000-01-01

    Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described.......Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described....

  6. Numerical study of heat transfer enhancement by rectangular winglet vortex generator pair in a channel

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2016-05-01

    Full Text Available A numerical simulation was performed to investigate the effects of longitudinal vortices on the heat transfer enhancement of a laminar flow in a rectangle duct mounted with rectangular winglet pair on the bottom wall. The studied Reynolds number which was defined using the hydraulic diameter twice the channel height ranges from 500 to 7000. The comparisons of the fluid flow and heat transfer characteristics for the cases with and without rectangular winglet pair were carried out. The effects of the height and attack angle of vortex generator pair on the heat transfer performance were investigated. The results show that mounting rectangular winglet pair on the bottom wall of the channel can significantly enhance heat transfer. The distributions of secondary flow on the cross sections are consistent with the distributions of Nu and J for different attack angles. The maximum heat transfer performance is obtained when the attack angle is 29° due to the maximum value of secondary flow generated by rectangular winglet pair.

  7. A Geometric Framework for Rectangular Shape Detection.

    Science.gov (United States)

    Li, Qi

    2014-07-25

    Rectangular shape detection has a wide range of applications, such as license plate detection, vehicle detection and building detection. In this paper, we propose a geometric framework for rectangular shape detection based on the channelscale space of RGB images. The framework consists of algorithms developed to address three issues of a candidate shape (i.e., a connected component of edge points), including: i) outliers, ii) open shape, and iii) fragmentation. Furthermore, we propose an interestness measure for rectangular shapes by integrating imbalanced points (one type of interest points). Our experimental study shows the promise of the proposed framework.

  8. Successive Standardization of Rectangular Arrays

    Directory of Open Access Journals (Sweden)

    Richard A. Olshen

    2012-02-01

    Full Text Available In this note we illustrate and develop further with mathematics and examples, the work on successive standardization (or normalization that is studied earlier by the same authors in [1] and [2]. Thus, we deal with successive iterations applied to rectangular arrays of numbers, where to avoid technical difficulties an array has at least three rows and at least three columns. Without loss, an iteration begins with operations on columns: first subtract the mean of each column; then divide by its standard deviation. The iteration continues with the same two operations done successively for rows. These four operations applied in sequence completes one iteration. One then iterates again, and again, and again, ... In [1] it was argued that if arrays are made up of real numbers, then the set for which convergence of these successive iterations fails has Lebesgue measure 0. The limiting array has row and column means 0, row and column standard deviations 1. A basic result on convergence given in [1] is true, though the argument in [1] is faulty. The result is stated in the form of a theorem here, and the argument for the theorem is correct. Moreover, many graphics given in [1] suggest that except for a set of entries of any array with Lebesgue measure 0, convergence is very rapid, eventually exponentially fast in the number of iterations. Because we learned this set of rules from Bradley Efron, we call it “Efron’s algorithm”. More importantly, the rapidity of convergence is illustrated by numerical examples.

  9. Optimization of the mechanical performance of a two-duct semicircular duct sytem. Part 1. Dynamics and duct dimensions

    NARCIS (Netherlands)

    Muller, M.; Verhagen, J.H.G.

    2002-01-01

    The classical representation of the semicircular duct system consists of three separate duct circuits. The ducts are, however, in reality, hydrodynamically interconnected. Muller & Verhagen (1988a,b) derived equations for the mechanical behaviour of an interconnected system with three ducts

  10. Transient natural convection heat and mass transfer in a rectangular enclosure - A numerical analysis

    Science.gov (United States)

    Han, Samuel S.; Schafer, Charles F.

    1988-01-01

    A numerical analysis of transient heat and solute transport across a rectangular cavity with combined horizontal temperature and concentration gradients is performed by a numerical method based on the SIMPLE. Numerical results show that the average Nusselt and Sherwood numbers both decrease markedly when the solutal and thermal buoyancy forces act in the opposite directions. When the solutal and thermal buoyancy forces act in the same directions, however, the average Sherwood number increases significantly and yet the average Nusselt number decreases slightly.

  11. ROV inspection inside ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, R.E.; Street, P.F.; Cole, G.V. [AEA Technology, Harwell (United Kingdom)

    1996-12-31

    An instrumentation package for carrying out visual inspections and radiation monitoring within radioactive duct-work has been developed. This paper describes the first application of the package in the main ventilation duct of the Dounreay fuel cycle area. The package was deployed via a commerical ROV within a duct consisting of two parallel runs, over 300 metres long, between 0.9 and 1.7 metres high and 1.1 metres wide. An integrated, computer-controlled station was used for data collection, recording in digital form and on video tape. (Author).

  12. Random Young diagrams in a Rectangular Box

    DEFF Research Database (Denmark)

    Beltoft, Dan; Boutillier, Cédric; Enriquez, Nathanaël

    We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape.......We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape....

  13. Partial rectangular metric spaces and fixed point theorems.

    Science.gov (United States)

    Shukla, Satish

    2014-01-01

    The purpose of this paper is to introduce the concept of partial rectangular metric spaces as a generalization of rectangular metric and partial metric spaces. Some properties of partial rectangular metric spaces and some fixed point results for quasitype contraction in partial rectangular metric spaces are proved. Some examples are given to illustrate the observed results.

  14. Bile Duct Diseases - Multiple Languages

    Science.gov (United States)

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Bile Duct Diseases URL of this page: https://medlineplus.gov/languages/bileductdiseases.html Other topics A-Z Expand Section ...

  15. Salivary duct carcinoma.

    Science.gov (United States)

    D'heygere, Emmanuel; Meulemans, Jeroen; Vander Poorten, Vincent

    2018-01-25

    The review puts new information on geno- and phenotype of salivary duct carcinoma (SDC) in the perspective of the updated 2017 WHO classification. The proportion of SDC is increasing. This may be because of a true rise in incidence, but certainly to better diagnostic tests and changed WHO definitions. In this light, a substantial proportion of carcinoma expleomorphic adenoma is now attributed to the category of SDC. 'Low-grade SDC' and 'SDC in-situ' of the former WHO classification, are now named low-grade and high-grade intraductal carcinoma (IDC), respectively. Recent series quantify biologic aggressiveness: perineural growth, vascular invasion, and extracapsular extension in lymph node metastasis are each observed in two out of three patients with SDC. Most patients die within 3 years, but once 5-year disease-free survival is reached, further disease activity is exceptional. The typical molecular biological profile with high human epidermal growth factor receptor 2 and androgen receptor expression is increasingly successfully exploited in clinical trials for advanced SDC. The aggressive SDC is increasingly diagnosed. Despite intensive combined surgery and radiation therapy, many patients recur, for whom new bullets, targeting the molecular biological mechanisms, are the subject of ongoing clinical trials.

  16. Duct Leakage Repeatability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-01

    Duct leakage often needs to be measured to demonstrate compliance with requirements or to determine energy or Indoor Air Quality (IAQ) impacts. Testing is often done using standards such as ASTM E1554 (ASTM 2013) or California Title 24 (California Energy Commission 2013 & 2013b), but there are several choices of methods available within the accepted standards. Determining which method to use or not use requires an evaluation of those methods in the context of the particular needs. Three factors that are important considerations are the cost of the measurement, the accuracy of the measurement and the repeatability of the measurement. The purpose of this report is to evaluate the repeatability of the three most significant measurement techniques using data from the literature and recently obtained field data. We will also briefly discuss the first two factors. The main question to be answered by this study is to determine if differences in the repeatability of these tests methods is sufficient to indicate that any of these methods is so poor that it should be excluded from consideration as an allowed procedure in codes and standards.

  17. Heat transfer in a vertical rectangular duct filled with a porous matrix ...

    African Journals Online (AJOL)

    with uniform heat flux, Transactions of the ASME Journal of Heat Transfer, Vol. 107, pp. 716-720. Seddeek M.A., Effects of magnetic field and variable viscosity on forced non-Darcy flow about a flat plate with variable wall temperature in porous media in the presence of suction and bellowing, J. Appl. Mech. Tech. Phys., Vol.

  18. Investigation of Heat Transfer in Straight and Curved Rectangular Ducts for Laminar and Transition Flows.

    Science.gov (United States)

    1981-06-01

    between the first and second layers of ARMAFLEX 22 insulation, and another five inserted between the second and third layers. Each of these sets of...the Plexiglas wall. The thermal insulation consisisted of layers ot ARMSTRONG ARMAFLEX 22 Sheet Insulation, a flexible foamed plastic material, on the...heated side of each test section, and black foam insulation one-half inches thick elsewhere. Three layers of the ARMAFLEX 22 insulation were used, each

  19. Correlation for Evaporation Heat Transfer of Pure Refrigerant Inside an Internally Grooved Horizontal Tube

    Science.gov (United States)

    Kido, Osao; Uehara, Haruo

    The empirical correlation to predict the evaporation heat transfer coefficient inside an internally grooved horizontal tube was proposed using previous experimental data studied by other researchers. Parameters in the correlation were selected by refering to the correlation for rectangular channnel. The correlation for rectangular channnel was proposed by taking weighted average of heat transfer coefficients on upper and lower grooved surfaces inside a rectangular channnel to applicate to the internally grooved tube. Effects of parameters in the correlation for grooved tube are corresponding to those in the correlation for rectangular chaannel, and increasing the modified bond number, the heat transfer coefficient decreases. For rectangular channel, the maximum heat transfer coefficient is obtained on the grooved surface with 2 × 10-3 of the modified bond number.

  20. Mixing Characteristics of Elliptical and Rectangular Subsonic Jets with Swirling Co-flow

    Science.gov (United States)

    Gopinath, S.; Sundararaj, M.; Elangovan, S.; Rathakrishnan, E.

    2015-04-01

    This paper presents a computational analysis of effects of swirling co-flow and non-circular subsonic compressible inner jets on centerline velocity decay, mass entrainment and jet spreading rate. Three different exit shapes of elliptical, rectangular and circular inner jets were compared for three different co-flow conditions such as no co-flow, straight co-flow and swirling co-flow. Co-flow is issuing from a circular annular duct. Swirling co-flow is created in the co-flow duct by introducing a swirler with stationary angular vanes of 50° oblique to the jet axis. Reynolds number of inner jet is calculated based on its equivalent diameter as 200342. It is found that the swirling co-flow has strong influence on the boundary condition of inner jet and alters the major features of the jet such as jet potential core length, centerline velocity decay rate and jet spread rate. Streamwise corner vortices of different jet conditions have been captured using velocity vector plot to show the effect of swirling co-flow on the jet flow field. Swirling co-flow with elliptical inner jet exhibits higher velocity decay rate and jet spreading rate than the equivalent area circular and rectangular jet.

  1. Turbulence Measurements of Rectangular Nozzles with Bevel

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2015-01-01

    This paper covers particle image velocimetry measurements of a family of rectangular nozzles with aspect ratios 2, 4, and 8, in the high subsonic flow regime. Far-field acoustic results, presented previously, showed that increasing aspect ratios increased the high frequency noise, especially directed in the polar plane containing the minor axis of the nozzle. The measurements presented here have important implications in the modeling of turbulent sources for acoustic analogy theories. While the nonaxisymmetric mean flow from the rectangular nozzles can be studied reliably using computational solutions, the nonaxisymmetry of the turbulent fluctuations, particularly at the level of velocity components, cannot; only measurements such as these can determine the impact of nozzle geometry on acoustic source anisotropy. Additional nozzles were constructed that extended the wide lip on one side of these nozzles to form beveled nozzles. The paper first documents the velocity fields, mean and variance, from the round, rectangular, and beveled rectangular nozzles at high subsonic speeds. A second section introduces measures of the isotropy of the turbulence, such as component ratios and lengthscales, first by showing them for a round jet and then for the rectangular nozzles. From these measures the source models of acoustic analogy codes can be judged or modified to account for these anisotropies.

  2. Verification of an acoustic transmission matrix analysis of sound propagation in a variable area duct without flow

    Science.gov (United States)

    Miles, J. H.

    1981-01-01

    A predicted standing wave pressure and phase angle profile for a hard wall rectangular duct with a region of converging-diverging area variation is compared to published experimental measurements in a study of sound propagation without flow. The factor of 1/2 area variation used is sufficient magnitude to produce large reflections. The prediction is based on a transmission matrix approach developed for the analysis of sound propagation in a variable area duct with and without flow. The agreement between the measured and predicted results is shown to be excellent.

  3. Ducted combustion chamber for direct injection engines and method

    Science.gov (United States)

    Mueller, Charles

    2015-03-03

    An internal combustion engine includes an engine block having a cylinder bore and a cylinder head having a flame deck surface disposed at one end of the cylinder bore. A piston connected to a rotatable crankshaft and configured to reciprocate within the cylinder bore has a piston crown portion facing the flame deck surface such that a combustion chamber is defined within the cylinder bore and between the piston crown and the flame deck surface. A fuel injector having a nozzle tip disposed in fluid communication with the combustion chamber has at least one nozzle opening configured to inject a fuel jet into the combustion chamber along a fuel jet centerline. At least one duct defined in the combustion chamber between the piston crown and the flame deck surface has a generally rectangular cross section and extends in a radial direction relative to the cylinder bore substantially along the fuel jet centerline.

  4. Transmission of sound through nonuniform circular ducts with compressible mean flows

    Science.gov (United States)

    Nayfeh, A. H.; Shaker, B. S.; Kaiser, J. E.

    1977-01-01

    An acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined, circular duct carrying compressible, sheared, mean flows and having a variable cross section. The theory is applicable to large as well as small axial variations, as long as the mean flow does not separate. Although the theory is described for circular ducts, it is applicable to other duct configurations - annular, two dimensional, and rectangular. The theory is described for the linear problem, but the technique is general and has the advantage of being applicable to the nonlinear case as well as the linear case. The technique is based on solving for the envelopes of the quasi-parallel acoustic modes that exist in the duct instead of solving for the actual wave. A computer program was developed. The mean flow model consists of a one dimensional flow in the core and a quarter-sine profile in the boundary layer. Results are presented for the reflection and transmission coefficients in ducts with varying slopes and carrying different mean flows.

  5. Electrochemical apparatus comprising modified disposable rectangular cuvette

    Science.gov (United States)

    Dattelbaum, Andrew M; Gupta, Gautam; Morris, David E

    2013-09-10

    Electrochemical apparatus includes a disposable rectangular cuvette modified with at least one hole through a side and/or the bottom. Apparatus may include more than one cuvette, which in practice is a disposable rectangular glass or plastic cuvette modified by drilling the hole(s) through. The apparatus include two plates and some means of fastening one plate to the other. The apparatus may be interfaced with a fiber optic or microscope objective, and a spectrometer for spectroscopic studies. The apparatus are suitable for a variety of electrochemical experiments, including surface electrochemistry, bulk electrolysis, and flow cell experiments.

  6. A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications

    Directory of Open Access Journals (Sweden)

    Sangjin Jo

    2014-01-01

    Full Text Available We present a simple coplanar waveguide- (CPW- fed rectangular ring monopole antenna designed for dual-band wireless local area network (WLAN applications. The antenna is based on a simple structure composed of a CPW feed line and a rectangular ring. Dual-band WLAN operation can be achieved by controlling the distance between the rectangular ring and the ground plane of the CPW feed line, as well as the horizontal vertical lengths of the rectangular ring. Simulated and measured data show that the antenna has a compact size of 21.4×59.4 mm2, an impedance bandwidths of 2.21–2.70 GHz and 5.04–6.03 GHz, and a reflection coefficient of less than −10 dB. The antenna also exhibits an almost omnidirectional radiation pattern. This simple compact antenna with favorable frequency characteristics therefore is attractive for applications in dual-band WLAN.

  7. Calculation of generalized Hubbell rectangular source integral.

    Science.gov (United States)

    Murley, Jonathan; Saad, Nasser

    2011-01-01

    A simple formula for computing the generalized Hubbell radiation rectangular source integral [formula in text] is introduced. Tables are given to compare the numerical values derived from our approximation formula with those given earlier in the literature. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Rectangular Laser Resonators with Astigmatic Compensation

    DEFF Research Database (Denmark)

    Skettrup, Torben

    2005-01-01

    An investigation of rectangular resonators with a view to the compensation of astigmatism has been performed. In order to have beam waists placed at the same positions in the tangential and sagittal planes, pairs of equal mirrors were considered. It was found that at least two concave mirrors are...

  9. STABILITY ANALYSIS OF SSSS THIN RECTANGULAR PLATE ...

    African Journals Online (AJOL)

    This was achieved by truncating the two domain Taylor Maclaurin's series at the seventh term to evolve the general deflection polynomial function for thin rectangular plate continuum. Consequently, the SSSS plate boundary conditions were applied, reducing the polynomial function to four degrees of freedom function.

  10. Performance Study of a Ducted Fan System

    Science.gov (United States)

    Abrego, Anita I.; Bulaga, Robert W.; Rutkowski, Michael (Technical Monitor)

    2002-01-01

    An experimental investigation was completed in the NASA Ames 7- by 10-Foot Wind Tunnel with the objective of determining the performance characteristics of a ducted fan. The model was an annular duct with a 38-in diameter, 10-in chord, and a 5-bladed fixed-pitch fan. Model variations included duct angle of attack, exit vane flap length, flap deflection angle, and duct chord length. Duct performance data were obtained for axial and forward flight test conditions. Axial flow test data showed figure of merit decreases with increasing advance ratio. Forward flight data showed an increasing propulsive force with decreasing duct angle of attack. Exit vane flap deflection angle and flap chord length were shown to be an effective way of providing side force. Extending the duct chord did not effect the duct performance.

  11. Affections of the salivary ducts in buffaloes

    Directory of Open Access Journals (Sweden)

    N.A. Misk

    2014-06-01

    Full Text Available The aim of the present study was to determine different affections of the salivary ducts in buffaloes with special reference to diagnosis and treatment. The study was carried out on 39 buffaloes suffering from different affections of the salivary ducts. The recorded affections of the salivary ducts in buffaloes include; ectasia of the parotid duct (21 cases, parotid duct fistula (15 cases and sialocele (3 cases. Each case was subjected to full study including case history, clinical examination, diagnosis, and treatment whenever possible. Exploratory puncture and radiography were used for confirmation of diagnosis. Intraoral marsupialization was performed for treatment of parotid duct ectasia. Salivary fistula was corrected by one of two successful techniques; the first by reconstruction of the parotid duct and the second by ligation of the parotid duct just caudal to the fistula opening. Sialoceles were corrected by removal of the mandibular salivary gland of the affected side.

  12. Device for Measuring Low Flow Speed in a Duct

    Science.gov (United States)

    Quinn, Frank; Magee, Kevin

    2009-01-01

    A multiple-throat venturi system has been invented for measuring laminar flow of air or other gas at low speed (1 to 30 cm/s) in a duct while preserving the laminar nature of the flow and keeping the velocity profile across the duct as nearly flat as possible. While means for measuring flows at higher speeds are well established, heretofore, there have been no reliable means for making consistent, accurate measurements in this speed range. In the original application for which this system was invented, the duct leads into the test section of a low-speed wind tunnel wherein uniform, low-speed, laminar flow is required for scientific experiments. The system could also be used to monitor a slow flow of gas in an industrial process like chemical vapor deposition. In the original application, the multiple- throat venturi system is mounted at the inlet end of the duct having a rectangular cross section of 19 by 14 cm, just upstream of an assembly of inlet screens and flow straighteners that help to suppress undesired flow fluctuations (see Figure 1). The basic venturi measurement principle is well established: One measures the difference in pressure between (1) a point just outside the inlet, where the pressure is highest and the kinetic energy lowest; and (2) the narrowest part (the throat) of the venturi passage, where the kinetic energy is highest and the pressure is lowest. Then by use of Bernoulli s equation for the relationship between pressure and kinetic energy, the volumetric flow speed in the duct can be calculated from the pressure difference and the inlet and throat widths. The design of this system represents a compromise among length, pressure recovery, uniformity of flow, and complexity of assembly. Traditionally, venturis are used to measure faster flows in narrower cross sections, with longer upstream and downstream passages to maintain accuracy. The dimensions of the passages of the present venturi system are sized to provide a readily measurable

  13. Distinct α-intercalated cell morphology and its modification by acidosis define regions of the collecting duct

    Science.gov (United States)

    Purkerson, Jeffrey M.; Schwaderer, Andrew L.; Nakamori, Aya

    2015-01-01

    During metabolic acidosis, the cortical collecting duct (CCD) of the rabbit reverses the polarity of bicarbonate flux from net secretion to net absorption, and this is accomplished by increasing the proton secretory rate by α-intercalated cells (ICs) and decreasing bicarbonate secretion by β-ICs. To better characterize dynamic changes in H+-secreting α-ICs, we examined their morphology in collecting ducts microdissected from kidneys of normal, acidotic, and recovering rabbits. α-ICs in defined axial regions varied in number and basolateral anion exchanger (AE)1 morphology, which likely reflects their relative activity and function along the collecting duct. Upon transition from CCD to outer medullary collecting duct from the outer stripe to the inner stripe, the number of α-ICs increases from 11.0 ± 1.2 to 15.4 ± 1.11 and to 32.0 ± 1.3 cells/200 μm, respectively. In the CCD, the basolateral structure defined by AE1 typically exhibited a pyramidal or conical shape, whereas in the medulla the morphology was elongated and shallow, resulting in a more rectangular shape. Furthermore, acidosis reversibly induced α-ICs in the CCD to acquire a more rectangular morphology concomitant with a transition from diffusely cytoplasmic to increased basolateral surface distribution of AE1 and apical polarization of B1-V-ATPase. The latter results are consistent with the supposition that morphological adaptation from the pyramidal to rectangular shape reflects a transition toward a more “active” configuration. In addition, α-ICs in the outer medullary collecting duct from the outer stripe exhibited cellular morphology strikingly similar to dendritic cells that may reflect a newly defined ancillary function in immune defense of the kidney. PMID:26084929

  14. Duct injection technology prototype development

    Energy Technology Data Exchange (ETDEWEB)

    Harper, S.L. (Babcock and Wilcox Co., Alliance, OH (United States). Research and Development Div.)

    1991-08-01

    This report describes a test program conducted to determine the corrosion rate of materials in the dry scrubber or duct injection systems. Four materials were evaluated: 1010 carbon steel, Corten, 317SS and Hastelloy C-276. The results show that acidic conditions result in higher corrosion rates than alkaline conditions for all the materials. The carbon steel, Corten and stainless steel show moderate to heavy pitting attack in the acidic environment. For the alkaline conditions, the corrosion rates of carbon steel and Corten were higher than the stainless steel or Hastelloy C-276. Also, the corrosion rate of abraded specimens were four time those of unabraded specimens in the flue gas. It is probable that areas of wall-wetting and plugging in the duct injection process will exhibit high rates of corrosion for the carbon steel, Corten, and stainless steel materials. General corrosion and pitting corrosion will predominate. Additionally, abraded duct areas will corrode at a significantly higher rate than unabraded duct materials. 6 refs., 11 figs., 7 tabs.

  15. Gallbladder and Bile Duct Disorders

    Science.gov (United States)

    ... cholesterol) and by-products of drugs from the body. The biliary tract consists of small tubes (ducts) that carry bile from the liver to the gallbladder and then to the small intestine. The gallbladder is a small, pear-shaped sac located beneath the liver. It stores bile. ...

  16. The pressure distribution on the rectangular and trapezoidal storage tanks' perimeters due to liquid sloshing phenomenon

    Directory of Open Access Journals (Sweden)

    Hassan Saghi

    2016-03-01

    Full Text Available Sloshing phenomenon is a complicated free surface flow problem that increases the dynamic pressure on the sidewalls and the bottom of the storage tanks. When the storage tanks are partially filled, it is essential to be able to evaluate the fluid dynamic loads on the tank's perimeter. In this paper, a numerical code was developed to determine the pressure distribution on the rectangular and trapezoidal storage tanks' perimeters due to liquid sloshing phenomenon. Assuming the fluid to be inviscid, the Laplace equation and the nonlinear free surface boundary conditions were solved using coupled boundary element – finite element method. The code performance for sloshing modeling was validated using Nakayama and Washizu's results. Finally, this code was used for partially filled rectangular and trapezoidal storage tanks and free surface displacement, pressure distribution and horizontal and vertical forces exerted on the tanks' perimeters due to liquid sloshing phenomenon were estimated and discussed.

  17. G-weak contraction in ordered cone rectangular metric spaces.

    Science.gov (United States)

    Malhotra, S K; Sharma, J B; Shukla, Satish

    2013-01-01

    We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

  18. g-Weak Contraction in Ordered Cone Rectangular Metric Spaces

    Directory of Open Access Journals (Sweden)

    S. K. Malhotra

    2013-01-01

    Full Text Available We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

  19. Flow Duct Data for Validation of Acoustic Liner Codes for Impedance Eduction

    Science.gov (United States)

    Ahuja, K. K.; Munro, Scott; Gaeta, R. J., Jr.

    2000-01-01

    The objective of the study reported here was to acquire acoustic and flow data with hard and lined duct wall duct sections for validation of a liner prediction code being developed at NASA LaRC. Both the mean flowfield and acoustic flowfields were determined in a cross-plane of the rectangular duct. A flow duct facility with acoustic drivers connected to a rectangular (4.7 x 2.0 inch) source section and a linear acoustic liner mounted downstream of the source section was used in this study. The liner section was designed to allow liner materials to be placed on all 4 walls of the duct. The test liner was of the locally-reacting type and was made from a ceramic material. The material, consisting of a tubular structure, was provided by NASA LaRC. The liner was approximately 8.89 cm (3.5 inches) thick. For the current study, only the two "short" sides of the duct were lined with liner material. The other two sides were hard walls. Two especially built instrumentation sections were attached on either sides of the liner section to allow acoustic and flow measurements to be made upstream and downstream of the liner. The two instrumentation duct sections were built to allow measurement of acoustic and flow properties at planes perpendicular to flow upstream and downstream of the liner section. The instrumentation section was also designed to provide a streamwise gradient in acoustic (complex) pressure from which the acoustic particle velocity, needed for the model validation, can be computed. Flow measurements included pressure, temperature, and velocity profiles upstream of the liner section. The in-flow sound pressure levels and phases were obtained with a microphone probe equipped with a nose cone in two cross planes upstream of the liner and two cross plane downstream of the liner. In addition to the acoustic measurements at the cross planes. axial centerline acoustic data was acquired using an axially traversing microphone probe which was traversed from a location

  20. Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    J. G. Joshi

    2012-01-01

    Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

  1. Anisotropic rectangular metric for polygonal surface remeshing

    KAUST Repository

    Pellenard, Bertrand

    2013-06-18

    We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

  2. Calculation of generalized Hubbell rectangular source integral

    Energy Technology Data Exchange (ETDEWEB)

    Murley, Jonathan [Department of Mathematics and Statistics, University of Prince Edward Island Charlottetown, Prince Edward Island, C1A 4P3 (Canada); Saad, Nasser, E-mail: nsaad@upei.c [Department of Mathematics and Statistics, University of Prince Edward Island Charlottetown, Prince Edward Island, C1A 4P3 (Canada)

    2011-01-15

    A simple formula for computing the generalized Hubbell radiation rectangular source integral H[(table)]=({sigma}a)/(4{pi}) {integral}{sub 0}{sup b}x{sup {lambda}}(x{sup 2}+p){sup -{alpha}}{sub 2}F{sub 1}({alpha},{beta};{gamma};-(a{sup 2})/(x{sup 2}+p))dx, is introduced. Tables are given to compare the numerical values derived from our approximation formula with those given earlier in the literature.

  3. Acoustic Measurements of Rectangular Nozzles With Bevel

    Science.gov (United States)

    Bridges, James E.

    2012-01-01

    A series of convergent rectangular nozzles of aspect ratios 2:1, 4:1, and 8:1 were constructed with uniform exit velocity profiles. Additional nozzles were constructed that extended the wide lip on one side of these nozzles to form beveled nozzles. Far-field acoustic measurements were made and analyzed, and the results presented. The impact of aspect ratio on jet noise was similar to that of enhanced mixing devices: reduction in aft, peak frequency noise with an increase in broadside, high frequency noise. Azimuthally, it was found that rectangular jets produced more noise directed away from their wide sides than from their narrow sides. The azimuthal dependence decreased at aft angles where noise decreased. The effect of temperature, keeping acoustic Mach number constant, was minimal. Since most installations would have the observer on the wide size of the nozzle, the increased high frequency noise has a deleterious impact on the observer. Extending one wide side of the rectangular nozzle, evocative of an aft deck in an installed propulsion system, increased the noise of the jet with increasing length. The impact of both aspect ratio and bevel length were relatively well behaved, allowing a simple bilinear model to be constructed relative to a simple round jet.

  4. Direct numerical simulation of turbulence and heat transfer in a hexagonal shaped duct

    Science.gov (United States)

    Marin, Oana; Obabko, Aleks; Schlatter, Philipp

    2014-11-01

    Flows in hexagonal shapes frequently occur in nuclear reactor applications, and are also present in honeycomb-shaped settling chambers for e.g. wind tunnels. Whereas wall-bounded turbulence has been studied comprehensively in two-dimensional channels, and to a lesser degree also in square and rectangular ducts and triangles, only very limited data for hexagonal ducts is available, including resistance correlations and mean profiles. Here, we use resolved spectral-element simulations to compute velocity and temperature in fully-developed (periodic) hexagonal duct flow. The Reynolds number, based on the fixed flow rate and the hydraulic diameter, ranges between 2000 and 20000. The temperature assumes constant wall flux or constant wall temperature. First DNS results are focused on the mean characteristics such a head loss, Nusselt number, and critical Reynolds number for sustained turbulence. Profiles, both for mean and fluctuating quantities, are extracted and discussed in the context of square ducts and pipes. Comparisons to existing experiments, RANS and empirical correlations are supplied as well. The results show a complicated and fine-scale pattern of the in-plane secondary flow, which clearly affects the momentum and temperature distribution throughout the cross section.

  5. Investigation on flow and heat transfer characteristics in rectangular channel with drop-shaped pin fins

    Directory of Open Access Journals (Sweden)

    Fengming Wang

    2012-12-01

    Full Text Available The flow and heat transfer characteristics inside a rectangular channel embedded with pin fins were numerically and experimentally investigated. Several differently shaped pin fins (i.e., circular, elliptical, and drop-shaped with the same cross-sectional areas were compared in a staggered arrangement. The Reynolds number based on the obstructed section hydraulic diameter (defined as the ratio of the total wetted surface area to the open duct volume available for flow was varied from 4800 to 8200. The more streamlined drop-shaped pin fins were better at delaying or suppressing separation of the flow passing through them, which decreased the aerodynamic penalty compared to circular pin fins. The heat transfer enhancement of the drop-shaped pin fins was less than that of the circular pin fins. In terms of specific performance parameters, drop-shaped pin fins are a promising alternative configuration to circular pin fins.

  6. Convective flow patterns in inclined rectangular cavities with rotation

    Science.gov (United States)

    Avila, Ruben; Perez-Espejel, Diana

    2015-11-01

    The natural convection in inclined three dimensional rectangular cavities with rotation is numerically investigated by using a spectral element method. When the rate of rotation (Ta number) is equal to zero, the critical Rayleigh number Rac for the onset of transverse or longitudinal rolls is obtained by solving (using the Tau-Chebyshev spectral method) the equations of the linear stability theory. In the numerical approach, the rotation is imposed once the steady state of the longitudinal or transverse rolls is attained. The cavity rotates around an axis that is orthogonal to its cold and hot surfaces, and passes through the center of these surfaces. In all the analyzed cases, the tilted angle δ, from the horizontal, varies in the interval 0° <= δ <90° (the cavity is heated from its lower surface, then an unstable condition prevails) and 90° < δ <= 180° (the cavity is heated from its upper surface, then a stable condition prevails). We report the influence of the Ta number on the critical Ra number, the average Nusselt number (evaluated at the hot surface), and the flow patterns in the tilted cavity. DGAPA-PAPIIT Project: IN117314-3.

  7. Experimental study on mixing efficiency in water supply rectangular tanks

    Science.gov (United States)

    Bateman, A.; Medina, V.; Mujal, A.

    2009-04-01

    Phenomenon of mixing in drinking water storage tanks and reservoirs has a direct effect on the quality of water. Creation of poor mixing zones and volume stratification can have negative effects in public health. The design of a storage tank must consider the conditions of the inlet and outlets, and also their orientation (vertical or horizontal) to prevent the formation of these zones. Experiments done in a reduced scaled-model with a rectangular base and three different inlets (two waterfalls and a pipe inlet) had the objective to decide which of these inlets achieved the best mixing efficiency. Four situations were considered while three entrances, two unsteady: filling and drawing, and two steady with different outlets. Moreover the effects of columns that support the roof of the tank were studied by running the three entrances with and without columns in the four situations. Neglecting the viscous scale effects, the time taken to mix the volume stored depends on the distance between the inlet and the opposite wall as though as its orientation. Taking into account the whole tank columns have a negative effect on mixing efficiency although they divide the flux and create local zones of turbulence around them, increasing local mixing. Using a digital treating image technique the results are found in a quantitative way.

  8. Construction of preheaters with horizontal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Goetze

    1944-09-27

    This report involved construction of preheaters for distillation and cracking plants in the oil industry, particularly in America. The use of heat transmission by radiation was also a consideration here. The recycling of waste gases occurred, but was not the rule. A convection section was often built next to the radiation section, in which the discharge gases were used for heating the incoming product. The general arrangement of the preheaters was discussed. The first form was a rectangular box with fireproof lining with tubes arranged in a single row along the outer walls and sometimes in a double row on the ceiling. It consisted of smooth and finned tubes. From the simple form a double preheater was developed that allowed one or two common discharge flues to provide as large a heating surface as possible within a reasonable space. Other items discussed were recycling of waste gases, reasons for the choice of horizontal preheaters with radiation heating, the use of vertical tubes in the U.S.A. and elsewhere in the oil industry, details of horizontal preheater tubes, end closures, material, suspension, protection against overloading by radiation, circulation heating, burners, use of horizontal radiation preheaters in hydrogenation in the U.S.A., rebuilding I. G. preheaters, construction, tube supports, and masonry. A list of references on cracking, preheaters, heat transmission, and alloyed steels was given.

  9. Pyrolysis oil combustion in a horizontal box furnace with an externally mixed nozzle

    Science.gov (United States)

    Combustion characteristics of neat biomass fast-pyrolysis oil were studied in a horizontal combustion chamber with a rectangular cross-section. An air-assisted externally mixed nozzle known to successfully atomize heavy fuel oils was installed in a modified nominal 100 kW (350,000 BTU/h nominal cap...

  10. Quadcopter thrust optimization with ducted-propeller

    Directory of Open Access Journals (Sweden)

    Kuantama Endrowednes

    2017-01-01

    Full Text Available In relation to quadcopter body frame model, propeller can be categorized into propeller with ducted and without ducted. This study present differences between those two using CFD (Computational Fluid Dynamics method. Both categories utilize two blade-propeller with diameter of 406 (mm. Propeller rotation generates acceleration per time unit on the volume of air. Based on the behavior of generated air velocity, ducted propeller can be modeled into three versions. The generated thrust and performance on each model were calculated to determine the best model. The use of ducted propeller increases the total weight of quadcopter and also total thrust. The influence of this modeling were analyzed in detail with variation of angular velocity propeller from 1000 (rpm to 9000 (rpm. Besides the distance between propeller tip and ducted barrier, the size of ducted is also an important part in thrust optimization and total weight minimization of quadcopter.

  11. Application of steady state finite element and transient finite difference theory to sound propagation in a variable area duct: A comparison with experiment

    Science.gov (United States)

    Baumeister, K. J.; Eversman, W.; Astley, R. J.; White, J. W.

    1981-01-01

    Sound propagation without flow in a rectangular duct with a converging-diverging area variation was studied experimentally and theoretically. The area variation was of sufficient magnitude to produce large reflections and induce modal scattering. The rms (root-mean-squared) pressure and phase angle on both the flat and curved surface were measured and tabulated. The steady state finite element theory and the transient finite difference theory are in good agreement with the data. It is concluded that numerical finite difference and finite element theories appear ideally suited for handling duct propagation problems which encounter large area variations.

  12. Specific transduction and labeling of pancreatic ducts by targeted recombinant viral infusion into mouse pancreatic ducts.

    Science.gov (United States)

    Guo, Ping; Xiao, Xiangwei; El-Gohary, Yousef; Criscimanna, Angela; Prasadan, Krishna; Rymer, Christopher; Shiota, Chiyo; Wiersch, John; Gaffar, Iliana; Esni, Farzad; Gittes, George K

    2013-11-01

    Specific labeling of pancreatic ducts has proven to be quite difficult. Such labeling has been highly sought after because of the power it would confer to studies of pancreatic ductal carcinogenesis, as well as studies of the source of new insulin-producing β-cells. Cre-loxp recombination could, in theory, lineage-tag pancreatic ducts, but results have been conflicting, mainly due to low labeling efficiencies. Here, we achieved a high pancreatic duct labeling efficiency using a recombinant adeno-associated virus (rAAV) with a duct-specific sox9 promoter infused into the mouse common biliary/pancreatic duct. We saw rapid, diffuse duct-specific labeling, with 50 and 89% labeling in the pancreatic tail and head region, respectively. This highly specific labeling of ducts should greatly enhance our ability to study the role of pancreatic ducts in numerous aspects of pancreatic growth, development and function.

  13. Molecular Mechanisms of Bile Duct Development

    OpenAIRE

    Zong, Yiwei; Stanger, Ben Z.

    2010-01-01

    The mammalian biliary system, consisting of the intrahepatic and extrahepatic bile ducts, is responsible for transporting bile from the liver to the intestine. Bile duct dysfunction, as is seen in some congenital biliary diseases such as Alagille syndrome and biliary atresia, can lead to the accumulation of bile in the liver, preventing the excretion of detoxification products and ultimately leading to liver damage. Bile duct formation requires coordinated cell-cell interactions, resulting in...

  14. Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

    Science.gov (United States)

    Sadeghi, Morteza; Saidi, Mohammad Hassan; Sadeghi, Arman

    2017-06-01

    Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well as to validate the analytical solutions. We show that, with the exception of the migratory ionic conductivity, all the physicochemical parameters are strong functions of the channel aspect ratio. Accordingly, a slit geometry is not a good representative of a rectangular channel when the width is comparable to the height. It is also observed that the distribution of the electrical potential is not uniform over the surface of a charge-regulated channel. In addition, unlike ordinary channels for which an increase in the background salt concentration is always accompanied by higher flow rates, quite the opposite may be true for a pH-regulated duct at higher salt concentrations.

  15. Spatially extended sound equalization in rectangular rooms

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2001-01-01

    The results of a theoretical study on global sound equalization in rectangular rooms at low frequencies are presented. The zone where sound equalization can be obtained is a continuous three-dimensional region that occupies almost the complete volume of the room. It is proved that the equalization...... of broadband signals can be achieved by the simulation of a traveling plane wave using FIR filters. The optimal solution has been calculated following the traditional least-squares approximation, where a modeling delay has been applied to minimize reverberation. An advantage of the method is that the sound...

  16. Spatially extended sound equalization in rectangular rooms

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2001-01-01

    of broadband signals can be achieved by the simulation of a traveling plane wave using FIR filters. The optimal solution has been calculated following the traditional least-squares approximation, where a modeling delay has been applied to minimize reverberation. An advantage of the method is that the sound......The results of a theoretical study on global sound equalization in rectangular rooms at low frequencies are presented. The zone where sound equalization can be obtained is a continuous three-dimensional region that occupies almost the complete volume of the room. It is proved that the equalization...

  17. Supersonic jets from bevelled rectangular nozzles

    Science.gov (United States)

    Rice, Edward J.; Raman, Ganesh

    1993-01-01

    The influence of nozzle exit geometry on jet mixing and noise production was studied experimentally for a series of rectangular nozzles operating at supersonic jet velocities. Both converging (C) and converging-diverging (C-D) nozzles were built with asymmetrical (single bevel) and symmetrical (double bevel) exit chambers and with conventional straight exits for comparison. About a four decibel reduction of peak mixing noise was observed for the double bevelled C-D nozzle operated at design pressure ratio. All bevelled geometries provided screech noise reduction for under-expanded jets and an upstream mixing noise directivity shift which would be beneficial for improved acoustic treatment performance of a shrouded system.

  18. Computing simulated endolymphatic flow thermodynamics during the caloric test using normal and hydropic duct models.

    Science.gov (United States)

    Rey-Martinez, Jorge; McGarvie, Leigh; Pérez-Fernández, Nicolás

    2017-03-01

    The obtained simulations support the underlying hypothesis that the hydrostatic caloric drive is dissipated by local convective flow in a hydropic duct. To develop a computerized model to simulate and predict the internal fluid thermodynamic behavior within both normal and hydropic horizontal ducts. This study used a computational fluid dynamics software to simulate the effects of cooling and warming of two geometrical models representing normal and hydropic ducts of one semicircular horizontal canal during 120 s. Temperature maps, vorticity, and velocity fields were successfully obtained to characterize the endolymphatic flow during the caloric test in the developed models. In the normal semicircular canal, a well-defined endolymphatic linear flow was obtained, this flow has an opposite direction depending only on the cooling or warming condition of the simulation. For the hydropic model a non-effective endolymphatic flow was predicted; in this model the velocity and vorticity fields show a non-linear flow, with some vortices formed inside the hydropic duct.

  19. Design of horizontal fin array for radiative heat transfer

    Science.gov (United States)

    Ali, Mutari Hajara; Shuaibu, Bilyaminu

    2017-08-01

    This paper presents the analytical and simulation results of optimizing the radiative heat transfer performance of horizontal rectangular fin array heat sink. The fin thickness and inter-fin spacing need to be properly designed to eliminate surface area changes accompanying the creation of fin structures. Analytical expression for this change in area is developed in this work and used in identifying the optimum number of fins and their corresponding inter-fin spacing for a given rectangular space of a radiative heat sink. COMSOL Multiphysics software is used to simulate the structures considered in the above analysis. The performances of the simulated structures as radiative heat sinks are compared with the ones suggested by the developed empirical equation. The results from the two methods agreed with each successfully in the sense that the structures with large numerical radiative power from the simulations are found to also be the optimum structures suggested by the analytical formula derived in this work.

  20. Experimental Study of Rectangular Labyrinth Weir

    Directory of Open Access Journals (Sweden)

    M. Rezaee

    2016-09-01

    Full Text Available Introduction: Labyrinth weirs compare with straight weirs had required less freeboard in upstream so they are more appropriate for the irrigation networks. So they could maked more space to sotrage water and restrained foold with higher discharge. Labyrinths weirs have three generally form triangles, trapezoidal and rectangular that Tullis et al. (15 presented formula (3 for discharge coefficient of labyrinth weirs (triangles and rectangular and a few studiescarried out on rectangular shape and its hydraulic characteristics are not specified.Therefore main aim of this paper study and characterized hydraulic characteristics of rectangular labyrinth weirs by using laboratory data. Materials and Methods: In this study rectangular labyrinth weir discharge and coefficient discharge relationships used dimensional analysis and experiment on hydraulic modeling, constant coefficient was defined. Laboratory flume is shown in Figure 2 (0.5 m wide x 12 m long x 0.8 m deep. Models was made from clear plexiglass plate with 10 cm thickness thatcuted using leaserdevice and the crest manualy shaped quadrant with radius 10 cm, all models using silicon glue install in the flume. The upstream depth readership by point gauge that installed in upstream of models. Discharge calcutaed byupsterm depth of triangular weir that installed in down stream of flume.Data were analyzed by SPSS software and to compare relationships with each other used two parameter root mean square error and correlation coefficient and charts darw in Excel Results and Discussion: discharge coefficient formula (11 carried out by using SPSS software that compared with formula (3. Results showed (Tables 2 and 3 that the correlation coefficient of formula (11 was more than a formula (3 and formula (11 RSME was less than formula (3 RSME except in first and fifth hydraulic model (rectengular1 and 5 that they were almost equal. So the formula (11 was more accurate than a formula (3 to peredict

  1. Minimum Leakage/Low Cost Duct Connections

    Energy Technology Data Exchange (ETDEWEB)

    John Proctor

    2003-08-01

    Leaky and disconnected joints in HVAC air distribution systems are extremely widespread. The average efficiency of duct systems in homes in the US is approximately 55% with approximately 60% of the loss due to duct leakage. Beyond the energy and emissions penalties caused by these leaks, leaky systems have detrimental comfort, health, and safety effects. The health and safety effects include the delivery of combustion products into the homes due to leakage induced depressurization. Current duct installation practice does not attempt to address the problem. This project developed a prototype Professionally Engineered Duct System that will virtually eliminate air leakage and that can be applied in new and replacement installations at the same labor cost as current designs. It uses snap-together duct fittings that will not come apart, can be applied to all types of duct systems, and cannot be separated without exceptional force. its use would require minimal changes to current installation practice. The research team developed the prototype through a multi-step process beginning with a functional analysis of duct connections. This was followed by identifying duct sealing and attachment methods offering potential to meet design objectives, evaluating the designs in terms of function and economic feasibility, and building and testing the most promising design option. Two versions of this design were developed through a test, revise, retest process. One application was to a rigid sheet metal duct, the other was to a helix core flex duct. The process produced a sheet metal application with 1/20th the leakage of a standard connection and a flex duct application with 1/10th the leakage of a standard connection. A patent search has found that the design will not infringe on existing patents and is patentable.

  2. Thin section casting program. Volume 2: Horizontal TSC (Thin-Section Casting) approach

    Science.gov (United States)

    1989-01-01

    In horizontal thin-section casting (HTSC), 1-inch-thick steel sections are produced at speeds up to 600 ipm or about 60 tons per hour per foot of width (tphf). Liquid steel is fed from the ladle, and flows through a specially designed tundish, then flows through a refractory feeding tube and nozzle, with approximately the same external dimensions as the cast section, into a near-horizontal rectangular mold whose all four sides are traveling in the same direction and speed as the steel casting. This report is the second of a six volume set on thin section casting. This volume covers the research on horizontal thin section casting (TSC).

  3. Kinetic Energy Recovery from the Chimney Flue Gases Using Ducted Turbine System

    Science.gov (United States)

    Mann, Harjeet S.; Singh, Pradeep K.

    2017-03-01

    An innovative idea of extracting kinetic energy from man-made wind resources using ducted turbine system for on-site power generation is introduced in this paper. A horizontal axis ducted turbine is attached to the top of the chimney to harness the kinetic energy of flue gases for producing electricity. The turbine system is positioned beyond the chimney outlet, to avoid any negative impact on the chimney performance. The convergent-divergent duct causes increase in the flue gas velocity and hence enhances the performance of the turbine. It also acts as a safety cover to the energy recovery system. The results from the CFD based simulation analysis indicate that significant power 34 kW can be harnessed from the chimney exhaust. The effect of airfoils NACA4412 and NACA4416 and the diffuser angle on the power extraction by the energy recovery system using a 6-bladed ducted turbine has been studied with the CFD simulation. It is observed that the average flue gas velocity in the duct section at the throat is approximately twice that of the inlet velocity, whereas maximum velocity achieved is 2.6 times the inlet velocity. The simulated results show that about power may be extracted from the chimney flue gases of 660 MW power plant. The system can be retrofitted to existing chimneys of thermal power plants, refineries and other industries.

  4. Measure Guideline. Sealing and Insulating Ducts in Existing Homes

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, R. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Puttagunta, S. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

    2011-12-01

    This document begins with a discussion on potential cost and performance benefits of duct sealing and insulating. It continues with a review of typical duct materials and components and the overall procedures for assessing and improving the duct system.

  5. Measure Guideline: Sealing and Insulating of Ducts in Existing Homes

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, R.; Puttagunta, S.

    2011-12-01

    This document begins with a discussion on potential cost and performance benefits of duct sealing and insulating. It continues with a review of typical duct materials and components and the overall procedures for assessing and improving the duct system.

  6. Ducted wind turbine optimization : A numerical approach

    NARCIS (Netherlands)

    Dighe, V.V.; De Oliveira Andrade, G.L.; van Bussel, G.J.W.

    2017-01-01

    The practice of ducting wind turbines has shown a beneficial effect on the overall performance, when compared to an open turbine of the same rotor diameter1. However, an optimization study specifically for ducted wind turbines (DWT’s) is missing or incomplete. This work focuses on a numerical

  7. Thoracic duct lymphography by subcutaneous contrast agent ...

    African Journals Online (AJOL)

    A 4-year-old male Japanese Shiba Inu presented with recurrent chylothorax. The thoracic duct was successfully imaged using computed tomography after the injection of an iodine contrast agent into the subcutaneous tissue surrounding the anus. The thoracic duct was successfully ligated and pericardectomy performed via ...

  8. Salivary Duct Cyst: Histo-pathologic Correlation

    Directory of Open Access Journals (Sweden)

    Divya Vinayachandran

    2013-01-01

    Full Text Available Non-neoplastic cysts of the salivary glands are uncommon and represent 2-5% of all salivary gland lesions. They are mainly mucoceles or salivary duct cysts. Unlike a mucocele, which is surrounded by granulation tissue, the salivary duct cyst is lined by epithelium. Salivary duct cysts are more common in the oral minor salivary glands and rarely occur in the major salivary glands, show a marked predilection for the superficial lobe of the parotid, and represent 10% of all salivary gland cysts. Neoplastic differentiation of the lining of the salivary duct cyst has been reported. We report a case of a salivary duct cyst of the left parotid gland, with a review of radiographic and histopathologic features.

  9. Diffuse bile duct tumors: guidelines for management.

    Science.gov (United States)

    Saunders, K; Longmire, W; Tompkins, R; Chavez, M; Cates, J; Roslyn, J

    1991-12-01

    The majority of patients with bile duct cancer have small focal adenocarcinomas localized to the upper, middle, or lower third of the bile duct. In contrast, a small subgroup of patients have been identified with bile duct tumors that are diffuse, involving multiple segments of the extrahepatic biliary tract. Among 186 patients with documented bile duct cancer treated at the UCLA Medical Center between 1954 and 1988, 13 patients (7%) had diffuse lesions. Patients with diffuse tumors had markedly poorer survival rates than did those with focal lesions. As diffuse tumors are not amenable to resection, surgical management consists primarily of establishing suitable biliary drainage. All patients with bile duct cancer should undergo careful intraoperative evaluation to exclude a diffuse lesion before tumor resection.

  10. Solutal-thermo-diffusion convection in a vibrating rectangular cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chacha, M. [UAE University, Department of Mechanical Engineering, PO Box 17555, AD, Al Ain (United Arab Emirates); Saghir, M.Z. [Ryerson University, Department of Mechanical Engineering, 350 Victoria Street, ON, M5B 2K3, Toronto (Canada)

    2005-01-01

    Diffusion-dominated experiments on-board the International Space Station and other free-flying platforms are affected by the convective flow due to the residual acceleration field and/or to the oscillatory accelerations (g-jitters) caused by several external sources. We are interested in investigating these effects on the solutal-thermo-diffusion for a binary fluid mixture. We considered a rectangular rigid cavity filled with methane (20%) and normal butane (80%), subject to a temperature difference on its lateral walls and radiation heat transfer on the horizontal walls. The full transient Navier-Stokes equations, accounting for a unique mode of oscillatory acceleration, coupled with the mass and heat transfer formulations and the equation of state of the fluid were solved numerically using the control volume technique. The species transport equation accounts for varying diffusion coefficients with the temperature and the fluid composition and their effect is analysed as compared to that of their average constant values. Results revealed that convection is enhanced and temperature and species profiles distortion from purely diffusive (zero-gravity) condition increases in a buoyancy-destabilizing configuration. The numerical study shows that by elimination both the residual gravity and the g-jitter levels are essential to achieve nearly purely diffusive conditions when their direction is orthogonal to that of the temperature gradient. For the configuration investigated, the g-jitter is found to reduce compositional variation. When quasi-steady state conditions are attained, thermal and compositional quantities fluctuate following a mode whose fundamental (primary) frequency is equal to that of the initially imposed vibration. (authors)

  11. Determining large deflections in rectangular combined loaded ...

    Indian Academy of Sciences (India)

    In this study, large deflection of cantilever beams of Ludwick type material subjected to a combined loading consisting of a uniformly distributed load and one vertical concentrated load at the free end was investigated. In calculations, both material and geometrical non-linearity have been considered. Horizontal and vertical ...

  12. The problem of isotropic rectangular plate with four clamped edges

    Indian Academy of Sciences (India)

    This report discusses in exact solution of the governing equation of an isotropic rectangular plate with four clamped edges. A numerical method for clamped isotropic rectangular plate under distributed loads and an exact solution of the governing equation in terms of trigonometric and hyperbolic function are given. Finally ...

  13. Helping Students Acquainted with Multiplication in Rectangular Model

    Science.gov (United States)

    Tasman, Fridgo; den Hertog, Jaap; Zulkardi; Hartono, Yusuf

    2011-01-01

    Usually, multiplication is introduced to students to represent quantities that come in groups. However there is also rectangular array model which is also related to multiplication. Barmby et al. (2009) has shown that the rectangular model such as array representations encourage students to develop their thinking about multiplication as a binary…

  14. 3D Flow around a Rectangular Cylinder: a review | Odesola ...

    African Journals Online (AJOL)

    This paper presents the review of 3D flow around a rectangular cylinder using large eddy simulation as the turbulence model and the computational study is developed in the frame of the Benchmark on the Aerodynamics of aRectangular Cylinder (BARC). Different simulations around bluff bodies were reviewed and the ...

  15. Free vibration characteristics analysis of rectangular plate with rectangular opening based on Fourier series method

    Directory of Open Access Journals (Sweden)

    WANG Minhao

    2017-08-01

    Full Text Available Plate structures with openings are common in many engineering structures. The study of the vibration characteristics of such structures is directly related to the vibration reduction, noise reduction and stability analysis of an overall structure. This paper conducts research into the free vibration characteristics of a thin elastic plate with a rectangular opening parallel to the plate in an arbitrary position. We use the improved Fourier series to represent the displacement tolerance function of the rectangular plate with an opening. We can divide the plate into an eight zone plate to simplify the calculation. We then use linear springs, which are uniformly distributed along the boundary, to simulate the classical boundary conditions and the boundary conditions of the boundaries between the regions. According to the energy functional and variational method, we can obtain the overall energy functional. We can also obtain the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients. We can then obtain the natural frequencies and corresponding vibration modes of the rectangular plate with an opening by solving the equation. We then compare the calculated results with the finite element method to verify the accuracy and effectiveness of the method proposed in this paper. Finally, we research the influence of the boundary condition, opening size and opening position on the vibration characteristics of a plate with an opening. This provides a theoretical reference for practical engineering application.

  16. Task parameters affecting ergonomic demands and productivity of HVAC duct installation.

    Science.gov (United States)

    Mitropoulos, Panagiotis; Hussain, Sanaa; Guarascio-Howard, Linda; Memarian, Babak

    2014-01-01

    Mechanical installation workers experience work-related musculoskeletal disorders (WMSDs) at high rates. (1) Quantify the ergonomic demands during HVAC installation, (2) identify the tasks and task parameters that generated extreme ergonomic demands, and (3) propose improvements to reduce the WMSDs among mechanical workers. The study focused on installation of rectangular ductwork components using ladders, and analyzed five operations by two mechanical contractors. Using continuous time observational assessment, the videotaped operations were analyzed along two dimensions: (1) the production tasks and durations, and (2) the ergonomic demands for four body regions (neck, arms/shoulders, back, and knees). The analysis identified tasks with low portion of productive time and high portion of extreme postures, and task parameters that generated extreme postures. Duct alignment was the task with the highest portion of extreme postures. The position of the ladder (angle and distance from the duct) was a task parameter that strongly influenced the extreme postures for back, neck and shoulders. Other contributing factors included the difficulty to reach the hand tools when working on the ladder, the congestion of components in the ceiling, and the space between the duct and the ceiling. The identified tasks and factors provide directions for improvement.

  17. Advantages of laparoscopic common bile duct exploration in common bile duct stones.

    Science.gov (United States)

    Li, Ke-Yue; Shi, Cheng-Xian; Tang, Ke-Li; Huang, Jian-Zhao; Zhang, De-Lin

    2017-07-31

    To compare the efficacy, safety, and surgical outcomes of laparoscopic common bile duct exploration, endoscopic retrograde cholangiopancreatography, and open common bile duct exploration for treatment of common bile duct stones. In total, 210 patients were prospectively randomized into 3 groups: laparoscopic common bile duct exploration, endoscopic retrograde cholangiopancreatography, and open common bile duct exploration. The primary outcome measures were the common bile duct stone clearance rate and the complication rate. The secondary outcome measures were mortality, total costs, and length of hospital stay. The success rates in the laparoscopic common bile duct exploration group (97.14%, 68 out of 70) and open common bile duct exploration group (98.57%, 69/70) were significantly higher than that in the endoscopic retrograde cholangiopancreatography group (85.71%, 60/70, both p  0.05). Laparoscopic common bile duct exploration provides an alternative therapeutic approach that was safer and more reliable, allowed for earlier recovery, and provided more cost-effective treatment of common bile duct stones.

  18. Belo Horizonte em recortes

    Directory of Open Access Journals (Sweden)

    Ivete Lara Camargos Walty

    1998-03-01

    Full Text Available A partir do conceito de rizoma de Deleuze e Guatari, faz-se uma montagem de trechos de textos literários sobre Belo Horizonte, intercalados com extratos do livro As cidades invisíveis, de Italo Calvino, como objetivo de se esboçar faces/retratos da cidade.

  19. Symptomatic pancreatic duct stones in the disconnected bile duct: A case series.

    Science.gov (United States)

    Ende, Alexander R; Irani, Shayan; Kozarek, Richard A

    Pancreaticobiliary maljunction (PBM) refers to the union of the pancreatic and biliary ducts outside of the duodenal wall. Patients are at increased risk of bile duct and gallbladder cancer, likely secondary to pancreatic juice refluxing into the biliary tree, and it is recommended that they undergo biliary diversion. This is a case series of all patients in our institution with PBM and bilioenteric anastomosis who presented with symptomatic pancreatic duct stones in a disconnected bile duct. IRB approval was obtained prior to the initiation of the study. We describe eight cases of this finding. All patients underwent ERCP, with stones successfully removed from the disconnected bile duct in seven patients and from the pancreatic duct in one patient. This novel finding has not been described in the medical literature, and may become more prevalent as more patients with PBM undergo bilioenteric anastomosis. Copyright © 2016 IAP and EPC. Published by Elsevier B.V. All rights reserved.

  20. Traumatic resin ducts as indicators of bark beetle outbreaks

    Science.gov (United States)

    R. Justin DeRose; Matthew F. Bekker; James N. Long

    2017-01-01

    The formation of traumatic resin ducts (TRDs) represents an important induced defense in woody plants that enhances oleoresin production and flow in response to environmental perturbations. In some genera (Pinus), resin ducts are copious and conspicuous; however, in others (Picea), resin ducts are relatively rare. The occurrence and strength of resin ducts, in...

  1. Horizontal violence in Nursing

    Directory of Open Access Journals (Sweden)

    Tsimoulaki Evangelia

    2017-01-01

    Full Text Available One’s effort to clarify the definition of horizontal labour violence is of great importance, due to the variety of definitions that are mentioned in the worldwide scientific literature. Furthermore, the reference of multiple forms of such violence herein the nurse professional group is challenging, as well. Another fact of great importance is that, any form of professional violence (horizontal violence, horizontal mobbing in the work place environment can be possibly escalated and include even physical abuse (Bullying, besides the psychological and emotional impact for the victim. The definitions of Horizontal violence, Mobbing and Bullying, include a repeated negative behaviour emanating from at least one “predator” towards at least one “victim”, with work status differences and the existence or lack of physical abuse (Bullying. Horizontal violence is a hostile, aggressive and harmful behaviour which is either overt or concealed and is pointed from an individual to another individual of the same working rank and causes intense emotional pain at the victim. The manifestations vary from humiliating tasks assignment or the victim’s efforts undermining to clearly aggressive behaviors (criticism, intimidation, sarcasm etc.. The reason behind this phenomenon is multifactorial extended not only towards the working environment but also to the personal characteristics of the “predator” as well as the possible “victim”. The researchers emphasize the high incidence of the phenomenon, as well as the cost that is induced by the violent behaviors to both the health professionals and the hospital. Finally, they point out the paradox of the presence of violence inside a system that is designed to promote health.

  2. Sun ducts: new design and applications

    Energy Technology Data Exchange (ETDEWEB)

    Coch, H.; Isalgue, A. [School of Architecture, Barcelona (Spain)

    2000-07-01

    Developed in Barcelona since 1968, sun ducts are an architectural technique which takes advantage of direct sunlight, enabling it to reach interior zones of buildings which would normally be dark and gloomy. In addition to its main function of illuminating interiors with a special quality, unlike other natural lighting devices, sun ducts also offer other associated functional possibilities making their use highly advantageous in many cases of dense modern architecture. In recent years, using the experience gained since 1968, we have been attempting to produce standardised sun duct designs; new models have been researched and developed which once standardised, have begun to be used in buildings. The good results in the applications carried out and the ample possibilities for future uses of the ducts in architectural and urban design solutions in compact urban fabrics together make the development of applications of this technique very interesting. (author)

  3. Thoracic duct injury from blunt trauma.

    Science.gov (United States)

    Pai, G P; Bhatti, N A; Ellison, R G; Rubin, J W; Moore, H V

    1984-05-01

    We have reported a case of traumatic chylothorax occurring as a rare complication of fracture dislocation of the dorsal spine. When conservative management by drainage, low-fat diet, and parenteral alimentation proved unsuccessful, thoracic duct ligation effected a cure.

  4. Mode propagation and attenuation in lined ducts

    CERN Document Server

    BI, Wenping

    2014-01-01

    Optimal impedance for each mode is an important concept in an infinitely long duct lined with uniform absorption material. However it is not valid for finite length linings. This is because that the modes in lined ducts are not power-orthogonal; the total sound power is not equal to the sum of the sound power of each mode; cross-power terms may play important roles. In this paper, we study sound propagation and attenuation in an infinite rigid duct lined with a finite length of lining impedance. The lining impedance may be axial segments and circumferentially non-uniform. We propose two new physical quantities Kp and S to describe the self-overlap of the left eigenfunction and right eigenfunction of one mode and the normalized overlap between modes, respectively. The two new physical quantities describe totally the mode behaviors in lined ducts.

  5. Horizontal high speed stacking for batteries with prismatic cans

    Energy Technology Data Exchange (ETDEWEB)

    Bartos, Andrew L.; Lin, Yhu-Tin; Turner, III, Raymond D.

    2016-06-14

    A system and method for stacking battery cells or related assembled components. Generally planar, rectangular (prismatic-shaped) battery cells are moved from an as-received generally vertical stacking orientation to a generally horizontal stacking orientation without the need for robotic pick-and-place equipment. The system includes numerous conveyor belts that work in cooperation with one another to deliver, rotate and stack the cells or their affiliated assemblies. The belts are outfitted with components to facilitate the cell transport and rotation. The coordinated movement between the belts and the components promote the orderly transport and rotation of the cells from a substantially vertical stacking orientation into a substantially horizontal stacking orientation. The approach of the present invention helps keep the stacked assemblies stable so that subsequent assembly steps--such as compressing the cells or attaching electrical leads or thermal management components--may proceed with a reduced chance of error.

  6. Reference values of MRI measurements of the common bile duct and pancreatic duct in children

    Energy Technology Data Exchange (ETDEWEB)

    Gwal, Kriti; Bedoya, Maria A.; Patel, Neal; Darge, Kassa; Anupindi, Sudha A. [University of Pennsylvania Perelman School of Medicine, Department of Radiology, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States); Rambhatla, Siri J. [Beth Israel Medical Center, Department of Pediatrics, Newark, NJ (United States); Sreedharan, Ram R. [University of Pennsylvania, Departments of Gastroenterology, Hepatology and Nutrition, The Children' s Hospital of Philadelphia, Perelman School of Medicine, Philadelphia, PA (United States)

    2015-08-15

    Magnetic resonance imaging/cholangiopancreatography (MRI/MRCP) is now an essential imaging modality for the evaluation of biliary and pancreatic pathology in children, but there are no data depicting the normal diameters of the common bile duct (CBD) and pancreatic duct. Recognition of abnormal duct size is important and the increasing use of MRCP necessitates normal MRI measurements. To present normal MRI measurements for the common bile duct and pancreatic duct in children. In this retrospective study we searched all children ages birth to 10 years in our MR urography (MRU) database from 2006 until 2013. We excluded children with a history of hepatobiliary or pancreatic surgery. We stratified 204 children into five age groups and retrospectively measured the CBD and the pancreatic duct on 2-D axial and 3-D coronal T2-weighted sequences. We performed statistical analysis, using logistic and linear regressions to detect the age association of the visibility and size of the duct measurements. We used non-parametric tests to detect gender and imaging plane differences. Our study included 204 children, 106 (52%) boys and 98 (48%) girls, with a median age of 33 months (range 0-119 months). The children were distributed into five age groups. The common bile duct was visible in all children in all age groups. The pancreatic duct was significantly less visible in the youngest children, group 1 (54/67, 80.5%; P = 0.003) than in the oldest children, group 5 (22/22, 100%). In group 2 the pancreatic duct was seen in 19/21 (90.4%), in group 3 52/55 (94.5%), and in group 4 39/39 (100%). All duct measurements increased with age (P < 0.001; r-value > 0.423), and the incremental differences between ages were significant. The measurement variations between the axial and coronal planes were statistically significant (P < 0.001); however these differences were fractions of millimeters. For example, in group 1 the mean coronal measurement of the CBD was 2.1 mm and the axial

  7. INTERIOR DUCT SYSTEM DESIGN, CONSTRUCTION, AND PERFORMANCE

    Energy Technology Data Exchange (ETDEWEB)

    Janet E.R. Mcllvaine; David Beal; Philip Fairey

    2001-10-10

    By removing air distribution and conditioning equipment from unconditioned spaces, homeowners stand to benefit substantially with respect to both energy savings and indoor air quality. Duct leakage introduces: Greater heating and cooling loads from air at extreme temperatures and humidity levels; Outside air and air from unconditioned spaces that may contain air borne contaminants, combustion gases, pollen, mold spores, and/or particles of building materials; and Higher whole-house infiltration/exfiltration rates. Exemplary studies conducted since 1990 have demonstrated the prevalence of duct leakage throughout the United States and measured energy savings of approximately 20% during both heating and cooling seasons from leakage reduction. These all dealt with duct leakage to and/or from unconditioned spaces. In the building science community, leakage within the conditioned space is generally presumed to eliminate the negative consequences of duct leakage with the exception of possibly creating pressure imbalances in the house which relates to higher infiltration and/or exfiltration. The practical challenges of isolating ducts and air handlers from unconditioned spaces require builders to construct an air-tight environment for the ducts. Florida Solar Energy Center researchers worked with four builders in Texas, North Carolina, and Florida who build a furred-down chase located either in a central hallway or at the edges of rooms as an architectural detail. Some comparison homes with duct systems in attics and crawl spaces were included in the test group of more than 20 homes. Test data reveals that all of the duct/AHU systems built inside the conditioned space had lower duct leakage to unconditioned spaces than their conventional counterparts; however, none of the homes was completely free of duct leakage to unconditioned spaces. Common problems included wiring and plumbing penetrations of the chase, failure to treat the chase as an air tight space, and misguided

  8. Rectangular maximum-volume submatrices and their applications

    KAUST Repository

    Mikhalev, Aleksandr

    2017-10-18

    We introduce a definition of the volume of a general rectangular matrix, which is equivalent to an absolute value of the determinant for square matrices. We generalize results of square maximum-volume submatrices to the rectangular case, show a connection of the rectangular volume with an optimal experimental design and provide estimates for a growth of coefficients and an approximation error in spectral and Chebyshev norms. Three promising applications of such submatrices are presented: recommender systems, finding maximal elements in low-rank matrices and preconditioning of overdetermined linear systems. The code is available online.

  9. Calcium influx pathways in rat pancreatic ducts

    DEFF Research Database (Denmark)

    Hug, M J; Pahl, C; Novak, I

    1996-01-01

    by CCH by 55%. In resting ducts, an increase in extracellular pH, pHe, by means of HEPES and HCO3-/CO2 buffers, increased [Ca2+]i; a decrease in pHe had the opposite effect. In stimulated ducts the pH-evoked effects on Ca2+ influx were more pronounced and depended on the agonist used. At pHe 6.5 both ATP...

  10. Turbulent flow over thin rectangular riblets

    Energy Technology Data Exchange (ETDEWEB)

    Ei-Samni, O. A. [The University of Alexandria, Alexandria (Egypt); Yoon, Hyun Sik; Chun, Ho Hwan [Pusan National Univ., Pusan (Korea, Republic of)

    2005-09-15

    The effect of longitudinal thin rectangular riblets aligned with the flow direction on turbulent channel flow has been investigated using direct numerical simulation. The thin riblets have been modeled using the Immersed Boundary Method (IBM) where the velocities at only one set of vertical nodes at the riblets positions are enforced to be zeros. Different spacings, ranging between 11 and 43 wall units, have been simulated aiming at the getting the optimum spacing corresponding to the maximum drag reduction while keeping the height/spacing ratio at 0.5. Reynolds number based on the friction velocity u{sub {tau}} and the channel half depth {delta} is set to 150. The flow is driven by adjusted pressure gradient so that the mass flow rate is kept constant in all the simulations. This study shows similar trend of the drag ratio to that of the experiments at the different spacings. Also, this research provides an optimum spacing of around 17 wall units leading to maximum drag reduction as experimental data. Explanation of drag increasing/decreasing mechanism is highlighted.

  11. Epidemic Spreading in Random Rectangular Networks

    CERN Document Server

    Estrada, Ernesto; Moreno, Yamir

    2015-01-01

    Recently, Estrada and Sheerin (Phys. Rev. E 91, 042805 (2015)) developed the random rectangular graph (RRG) model to account for the spatial distribution of nodes in a network allowing the variation of the shape of the unit square commonly used in random geometric graphs (RGGs). Here, we consider an epidemics dynamics taking place on the nodes and edges of an RRG and we derive analytically a lower bound for the epidemic threshold for a Susceptible-Infected-Susceptible (SIS) or Susceptible-Infected-Recovered (SIR) model on these networks. Using extensive numerical simulations of the SIS dynamics we show that the lower bound found is very tight. We conclude that the elongation of the area in which the nodes are distributed makes the network more resilient to the propagation of an epidemics due to the fact that the epidemic threshold increases with the elongation of the rectangle. On the other hand, using the "classical" RGG for modeling epidemics on non-squared cities generates a larger error due to the effects...

  12. Factors affecting common bile duct diameter.

    Science.gov (United States)

    Daradkeh, Salam; Tarawneh, Emad; Al-Hadidy, Azmy

    2005-01-01

    The purpose of the study was to see the effect of age, sex, body mass index, previous cholecystectomy, hepatomegaly and fasting status on the common bile duct diameter. A series of 463 patients, 283 females and 180 males, with no hepatobiliary or pancreatic pathology were included in this study, the mean age was 45 +/- 16 years. Their age, sex, weight, height, fasting status and previous cholecystectomy was assessed and recorded by a physician prior to ultrasound examination. All patients were examined by real-time ultrasound to see if there was any pathology in the hepatobiliary and pancreatic area. Those with history of common bile duct exploration, endoscopic sphincterotomy or with previous history of cholecystectomy of less than 6 months and patients with common bile duct pathology were excluded from the study. The midportion of the common bile duct was taken as a fixed measurement for all patients and the size of the liver was also recorded. Analysis of variance as part of SPSS statistical package was used where common bile duct was considered a dependent variable, while sex, fasting status, hepatomegaly and previous cholecystectomy were considered to be independent variables, age and sex were considered as co-variants. The factors found to be significantly affecting the diameter of the common bile duct (P<0.05) were age, previous cholecystectomy and body mass index. If the CBD dilatation can not be explained by age, previous cholecystectomy and BMI, a pathology causing obstruction should be ruled out.

  13. A Comparison of Simulation Capabilities for Ducts

    Energy Technology Data Exchange (ETDEWEB)

    Miller, William A [ORNL; Smith, Matt K [ORNL; Gu, Lixing [Florida Solar Energy Center (FSEC); New, Joshua Ryan [ORNL

    2014-11-01

    Typically, the cheapest way to install a central air conditioning system in residential buildings is to place the ductwork in the attic. Energy losses due to duct-attic interactions can be great, but current whole-house models are unable to capture the dynamic multi-mode physics of the interactions. The building industry is notoriously fragmented and unable to devote adequate research resources to solve this problem. Builders are going to continue to put ducts in the attic because floor space is too expensive to closet them within living space, and there are both construction and aesthetic issues with other approaches such as dropped ceilings. Thus, there is a substantial need to publicly document duct losses and the cost of energy used by ducts in attics so that practitioners, builders, homeowners and state and federal code officials can make informed decisions leading to changes in new construction and additional retrofit actions. Thus, the goal of this study is to conduct a comparison of AtticSim and EnergyPlus simulation algorithms to identify specific features for potential inclusion in EnergyPlus that would allow higher-fidelity modeling of HVAC operation and duct transport of conditioned air. It is anticipated that the resulting analysis from these simulation tools will inform energy decisions relating to the role of ducts in future building energy codes and standards.

  14. Drug-induced bile duct injury.

    Science.gov (United States)

    Visentin, Michele; Lenggenhager, Daniela; Gai, Zhibo; Kullak-Ublick, Gerd A

    2017-09-04

    Drug-induced liver injury includes a spectrum of pathologies, some related to the mode of injury, some to the cell type primarily damaged. Among these, drug-induced bile duct injury is characterized by the destruction of the biliary epithelium following exposure to a drug. Most of the drugs associated with bile duct injury cause immune-mediated lesions to the epithelium of interlobular ducts. These share common histopathological features with primary biliary cholangitis, such as inflammation and necrosis at the expense of cholangiocytes and, if the insult persists, bile duct loss and biliary cirrhosis. Some drugs selectively target larger ducts. Such injury is often dose-dependent and thought to be the result of intrinsic drug toxicity. The histological changes resemble those seen in primary sclerosing cholangitis. This overview focuses on the clinical and pathological features of bile duct injury associated with drug treatment and on the immunological and biochemical effects that drugs exert on the biliary epithelium. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Analysis of Rectangular Loop Antenna Printed on Magnetic Plate

    OpenAIRE

    Taguchi, Mitsuo; Matsunaga, Yuki; Tanaka, Shinya; Shimoda, Hideaki

    2006-01-01

    In this paper, a rectangular loop antenna printed on the low loss magnetic plate is numerically and experimentally analyzed. In the numerical analysis, the electromagnetic simulator Micro-Stripes based on the transmission line matrix method is used.

  16. Triple-band metamaterial absorption utilizing single rectangular hole

    Science.gov (United States)

    Kim, Seung Jik; Yoo, Young Joon; Kim, Young Ju; Lee, YoungPak

    2017-01-01

    In the general metamaterial absorber, the single absorption band is made by the single meta-pattern. Here, we introduce the triple-band metamaterial absorber only utilizing single rectangular hole. We also demonstrate the absorption mechanism of the triple absorption. The first absorption peak was caused by the fundamental magnetic resonance in the metallic part between rectangular holes. The second absorption was generated by induced tornado magnetic field. The process of realizing the second band is also presented. The third absorption was induced by the third-harmonic magnetic resonance in the metallic region between rectangular holes. In addition, the visible-range triple-band absorber was also realized by using similar but smaller single rectangular-hole structure. These results render the simple metamaterials for high frequency in large scale, which can be useful in the fabrication of metamaterials operating in the optical range.

  17. Heat transfer in inclined air rectangular cavities with two localized heat sources

    Directory of Open Access Journals (Sweden)

    Samy M. Elsherbiny

    2015-12-01

    The investigation used rectangular enclosures with position ratios of the heaters, B1 = 0.25, B2 = 0.75, size ratio, ɛ = 0.25, and covered Rayleigh numbers based on scale length, s/A ranging from 103 to 106. The tilt angle from the horizontal was changed from Φ = 0° to 180°, and the aspect ratio was taken as A = 1, 5, and 10. The results are presented graphically in the form of streamlines and isotherm contour plots. The heat transfer characteristics, and average Nusselt numbers were also presented. A correlation for Nu is also given.

  18. A wideband stepped-impedance rectangular-ring resonator bandpass filter with multiple notched bands

    Science.gov (United States)

    Nakhlestani, Amir; Movahhedi, Masoud; Hakimi, Ahmad

    2014-07-01

    A configuration of wideband bandpass filter (BPF) with multiple notched bands is presented. Proposed BPF is based on stepped-impedance resonator. By utilising dual stepped-impedance resonators in folded topology a rectangular-ring resonator is formed. Two notched bands in the passband are achieved without using asymmetrical coupled lines. In other words, the filter configuration is capable of producing notched bands. It should be noted that additional information on filter performance and design is presented. Measurement results are presented to approve propounded filter characteristics. The measured passband of the second proposed filter is from 3.68 to 10.2 GHz with insertion loss of -1.76 dB in the first passband at the centre frequency of 4.45 GHz. The measured notched band frequencies are about 5.45 and 7.95 GHz with rejection of -21.77 and -20.82 dB, respectively. The return loss in the passband is better than -11.4 dB.

  19. The influence of tip clearance and Prandtl number on turbulent forced convection heat transfer of rectangular fins

    Science.gov (United States)

    Park, Hae-Kyun; Chung, Bum-Jin

    2016-12-01

    The turbulent forced convection heat transfer of rectangular fins in a duct was investigated by varying the tip clearance and Pr. Mass transfer experiments using a H2SO4-CuSO4 electroplating system were performed based on the analogy between heat and mass transfers. FLUENT 6.3 was used for calculations. Turbulent models were tested and the Reynolds Stress Model was chosen, which showed a 1.15 % discrepancy with the existing correlation for a simple tube flow when Pr = 2, but 13 % when Pr = 2014. For a more complex fin channel, the discrepancy increased up to 30 %. The optimal tip clearances, corresponding to maximum heat transfer rates, did not vary with Pr, which is explained using the temperature contours. The results were also compared with the laminar case where Pr influenced the optimal tip clearance.

  20. Horizontal drilling activity in Manitoba

    Energy Technology Data Exchange (ETDEWEB)

    Fox, J.

    1997-04-01

    An update of horizontal well drilling in Manitoba was provided. Manitoba`s productive formations are: (1) the Bakken Formation, (2) the Lodgepole Formation, (3) the Mission Canyon Formation, (4) the Amaranth Formation, and (5) the Melita Formation. A total of 28 exploratory wells and 29 development wells, including 11 horizontal wells were drilled in 1996. The 11 horizontal wells accounted for 30 per cent of the drilling meterage. The leading drillers for horizontal wells in Manitoba are Tundra Oil and Gas, Chevron, Anderson and HCO. Production from horizontal wells in 1996 totaled 310 cubic meter per day. To date, no horizontal wells have been drilled in the Bakken Formation. The least successful horizontal well application has been in the Lodgepole Formation. A summary of horizontal well production was provided for each Formation. 4 tabs., 10 figs.

  1. Simple resection of the lesion bile duct branch for treatment of regional hepatic bile duct stones.

    Science.gov (United States)

    Enliang, Li; Rongshou, Wu; Shidai, Shi; Jingling, Zhang; Qian, Feng; Wenjun, Liao; Linquan, Wu

    2017-07-01

    To evaluate the effectiveness and safety of simple resections of bile duct branch lesions for the treatment of regional hepatic bile duct stones.A retrospective analysis of the clinical data from patients in our hospital from November 2008 to November 2015, who only underwent a simple resection of the lesion bile duct branch. The patients' clinical characteristics, surgical features, postoperative complications, stone clear rate, residual stone rate, and recurrence stone rate were analyzed.This study of 32 patients included 13 males and 19 females with intrahepatic bile duct stones confined to the right hepatic bile duct branch. The intraoperative blood loss, operation time, and postoperative hospital stay were 478.0 ± 86.5, 210.7 ± 6.6, and 10.8 ± 3.5, respectively. Postoperative complications occurred in 6 patients (18.8%), all of whom recovered with conservative management. There were no deaths during hospitalization. The intraoperative stone clearance rate was 95.8%. Three patients had a recurrence of stones at a mean of 22 months of follow-up (range, 4-36 months).Simple resection of bile duct branch lesions is safe and feasible for patients who have regional hepatic bile duct stones limited to the right hepatic bile duct branches.

  2. Ultrasound appearance of chronic mammary duct ectasia

    Energy Technology Data Exchange (ETDEWEB)

    Duchesne, N. [Ottawa Hospital, Dept. of Radiology, Ottawa, Ontario (Canada)]. E-mail: nathalie_duchesne_22@yahoo.ca; Skolnik, S. [Univ. of Toronto, Dept. of Family Medicine, Toronto, Ontario (Canada); Bilmer, S. [Ottawa Hospital, Dept. of Radiology, Ottawa, Ontario (Canada)

    2005-12-15

    Mammary duct ectasia (MDE), also called periductal mastitis, mammary dysplasia, or plasma cell mastitis, is a benign condition of the mammary gland first described by Haagensen in 1951. The etiology of MDE is unknown and its pathogenesis still controversial; the periductal inflammation could be either the cause or the result of dilated damaged ducts. The process is usually bilateral and asymptomatic, with only a small percentage of patients presenting with symptoms that may include long course of tumour formation, usually subareolar breast lumps, nipple discharge, nipple retraction, mastalgia, and mammary abscess or fistulas. Mammographic presentation of MDE is well known; its features include periductal calcification, benign intraductal calcification, and retroareolar duct dilatation. The periductal calcification results from dystrophic calcification and forms calcified rings or very dense, oval, elongated calcifications, each with a central lucency representing the dilated duct. Intraductal calcifications of duct ectasia represent inspissated intraductal material and are typically of uniform high density, often needle-like, and occasionally branching. Occasionally, there are no mammographic findings, and the diagnosis must rely on sonographic features. Appearance of MDE on ultrasonography (US) depends on the stage of the disease and the contents of the dilated ducts. The acute presentation has been demonstrated in the literature more often than has its chronic counterpart. In the former, duct content can vary from anechoic to isoechoic with surrounding fatty tissue. In chronic MDE, episodes of inflammation are longer. This tends to result in secretions that have a more solid, cheesy texture, partly due to cholesterol crystals, foam cells, and inflammatory cells. For both types of MDE, the appearance can mimic high-grade ductal carcinoma in situ (DCIS) on US. In this essay, 2 chronic MDE cases are presented and their US appearance discussed. Our goal is to explore

  3. The "flying" bile duct: avulsion of the common bile duct in a plane crash survivor.

    LENUS (Irish Health Repository)

    Mohan, H

    2012-02-01

    Blunt trauma is an unusual cause of extrahepatic bile duct injury. This is a case of a 51-year-old gentleman who sustained a significant seatbelt injury in a plane crash. Laparotomy, performed due to persistent abdominal pain, revealed that the common bile duct (CBD) was completely avulsed from the duodenum. Following insertion of drains and transfer to a hepatobiliary centre, the devascularised CBD was excised and replaced with a roux-en-y hepaticojejunostomy. Necrotic tissue was debrided from the pancreatic head. A persistent bile leak developed from the sub-hepatic drain. Repeat laparotomy revealed a bile leak from small ducts on the liver surface. Ligation of the ducts and bioglue sealing of the area were successfully performed. Subsequent to this a pancreatic fistula developed from the main pancreatic duct, which has since resolved. This unusual case illustrates the need for prompt recognition and early repair to optimise outcomes in traumatic CBD injury.

  4. Numerical simulation of flow past circular duct

    Directory of Open Access Journals (Sweden)

    Ze-gao Yin

    2010-06-01

    Full Text Available The Renormalization Group (RNG k—ɛ turbulence model and Volume of Fluid (VOF method were employed to simulate the flow past a circular duct in order to obtain and analyze hydraulic parameters. According to various upper and bottom gap ratios, the force on the duct was calculated. When the bottom gap ratio is 0, the drag force coefficient, lift force coefficient, and composite force reach their maximum values, and the azimuth reaches its minimum. With an increase of the bottom gap ratio from 0 to 1, the drag force coefficient and composite force decrease sharply, and the lift force coefficient does not decreases so much, but the azimuth increases dramatically. With a continuous increase of the bottom gap ratio from 1 upward, the drag force coefficient, lift force coefficient, composite force, and azimuth vary little. Thus, the bottom gap ratio is the key factor influencing the force on the circular duct. When the bottom gap ratio is less than 1, the upper gap ratio has a remarkable influence on the force of the circular duct. When the bottom gap ratio is greater than 1, the variation of the upper gap ratio has little influence on the force of the circular duct.

  5. Characterization of flow in a scroll duct

    Science.gov (United States)

    Begg, E. K.; Bennett, J. C.

    1985-01-01

    A quantitative, flow visualization study was made of a partially elliptic cross section, inward curving duct (scroll duct), with an axial outflow through a vaneless annular cutlet. The working fluid was water, with a Re(d) of 40,000 at the inlet to the scroll duct, this Reynolds number being representative of the conditions in an actual gas turbine scroll. Both still and high speed moving pictures of fluorescein dye injected into the flow and illuminated by an argon ion laser were used to document the flow. Strong secondary flow, similar to the secondary flow in a pipe bend, was found in the bottom half of the scroll within the first 180 degs of turning. The pressure field set up by the turning duct was strong enough to affect the inlet flow condition. At 90 degs downstream, the large scale secondary flow was found to be oscillatory in nature. The exit flow was nonuniform in the annular exit. By 270 degs downstream, the flow appeared unorganized with no distinctive secondary flow pattern. Large scale structures from the upstream core region appeared by 90 degs and continued through the duct to reenter at the inlet section.

  6. Numerical simulation of flow past circular duct

    Directory of Open Access Journals (Sweden)

    Ze-gao YIN

    2010-06-01

    Full Text Available On the basis of Fluent software, Renormalization Group (RNGk-ε turbulent model and Volume of Fluid (VOF method are employed to simulate the flow past circular duct to obtain and analyze the hydraulic parameters. According to various upper and bottom gap-ratios, the force on duct is calculated. Firstly, when bottom gap-ratio is 0, drag force coefficient, lift force coefficient and composite force reach the maximum respectively and azimuth reaches the minimum. Secondly, with the increase of bottom gap-ratio from 0 to 1, drag force coefficient and composite force decrease sharply, lift force coefficient decreases a little, but azimuth increases dramatically. Thirdly, with the continuous increase of bottom gap-ratio from 1, drag force coefficient, lift force coefficient, composite force and azimuth vary little. So, bottom gap-ratio is the key factor influencing the force on circular duct. When bottom gap-ratio is less than 1, upper gap-ratio has the remarkable influence on the circular duct force. When bottom gap-ratio is greater than 1, the varation of upper gap-ratio has a little influence on the circular duct force.

  7. [Clinical analysis of 22 cases with parotid gland duct injury].

    Science.gov (United States)

    Jiang, Yong-lian; Yang, Pei-lei; Liu, Guo-yuan

    2011-08-01

    To discuss the early diagnosis and treatment of injury to the parotid duct. Segmental epidural catheter was used to repair the injured parotid duct, if the broken ends of the parotid duct can't be anastomized end to end, facial vein transplantation and fascia parotideomasseterica flap were used for reconstruction. In 22 cases, one case was lost to follow-up, nineteen cases had successful reconstruction of the parotid duct with good parotid secretions. Two cases had atrophy of the parotid gland. Early diagnosis is critical for treatment of injury of parotid duct. The efficacy of segmental epidural catheter is excellent for repair of parotid duct defect.

  8. Numerical study of flow and heat transfer behaviour of power-law non-Newtonian fluids in rectangular channels

    Energy Technology Data Exchange (ETDEWEB)

    Syrjaelae, S. [VTT Chemical Technology, Espoo (Finland). Polymer and Fibre Technology

    1996-12-31

    This thesis presents numerical studies on the flow and heat transfer behaviour of powerlaw non-Newtonian fluids in rectangular ducts, and in extruder channels of rectangular cross-section. For both applications hydrodynamically and thermally fully developed flows are studied first, and subsequently more realistic situations involving the effects of thermal development, viscous dissipation and temperature-dependent viscosity are considered. All numerical computations are based on the finite element method, and a marching procedure in the streamwise direction is utilized in the thermally developing situations. A salient feature of the present numerical approach is that it employs higher-order elements with quartic polynomial interpolation functions for dependent variables. In all cases studied the numerical procedure adopted yields consistent performance with respect to mesh refinement, and comparisons with available analytical solutions show very good agreement. The influence of different factors, such as shear-thinning, viscous dissipation and temperature-dependent viscosity, is investigated. In the extrusion flow computations the importance of considering the recirculating flow and associated transverse convection is clearly established. (orig.) (30 refs.)

  9. Percutaneous treatment of benign bile duct strictures

    Energy Technology Data Exchange (ETDEWEB)

    Koecher, Martin [Department of Radiology, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic)]. E-mail: martin.kocher@seznam.cz; Cerna, Marie [Department of Radiology, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Havlik, Roman [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Kral, Vladimir [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Gryga, Adolf [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic); Duda, Miloslav [Department of Surgery, University Hospital, I.P.Pavlova 6, 775 20 Olomouc (Czech Republic)

    2007-05-15

    Purpose: To evaluate long-term results of treatment of benign bile duct strictures. Materials and methods: From February 1994 to November 2005, 21 patients (9 men, 12 women) with median age of 50.6 years (range 27-77 years) were indicated to percutaneous treatment of benign bile duct stricture. Stricture of hepatic ducts junction resulting from thermic injury during laparoscopic cholecystectomy was indication for treatment in one patient, stricture of hepaticojejunostomy was indication for treatment in all other patients. Clinical symptoms (obstructive jaundice, anicteric cholestasis, cholangitis or biliary cirrhosis) have appeared from 3 months to 12 years after surgery. Results: Initial internal/external biliary drainage was successful in 20 patients out of 21. These 20 patients after successful initial drainage were treated by balloon dilatation and long-term internal/external drainage. Sixteen patients were symptoms free during the follow-up. The relapse of clinical symptoms has appeared in four patients 9, 12, 14 and 24 months after treatment. One year primary clinical success rate of treatment for benign bile duct stricture was 94%. Additional two patients are symptoms free after redilatation (15 and 45 months). One patient is still in treatment, one patient died during secondary treatment period without interrelation with biliary intervention. The secondary clinical success rate is 100%. Conclusion: Benign bile duct strictures of hepatic ducts junction or biliary-enteric anastomosis are difficult to treat surgically and endoscopically inaccessible. Percutaneous treatment by balloon dilatation and long-term internal/external drainage is feasible in the majority of these patients. It is minimally invasive, safe and effective.

  10. Xylometazoline hydrochloride nasal spray combined with laser artificial nasolacrimal duct implantation for nasolacrimal duct obstruction

    Directory of Open Access Journals (Sweden)

    Xiao-Zhao Yang

    2017-02-01

    Full Text Available AIM: To study the role of xylometazoline hydrochloride nasal spray in combination therapy of nasolacrimal duct obstruction and to investigate the effect of nasal inflammation on nasolacrimal duct obstruction. METHODS: Totally 279 patients with nasolacrimal duct obstruction were collected, who received lacrimal passage irrigation, CT angiography for lacrimal passage and nasal endoscope before treated by lacrimal laser forming and artificial nasolacrimal duct implantation combined with xylometazoline hydrochloride nasal spray. In group A, 137 patients were treated with antibiotic eye drop and non-steroidal anti-inflammatory drugs after operations. In group B, 142 patients were treated with xylometazoline hydrochloride nasal spray besides the same treatment for group A. RESULTS:In the 279 patients 217(77.8%, in which 105 cases(76.6%were in group A and 112 cases(78.9%were in group B, were suffered with nasal inflammation, including nasal mucosal hyperemia, inferior turbinate hypertrophy, middle turbinate hypertrophy. At 3mo after the ducts were drawn, efficacy of group B was 95.8%, which was significant better than that of group A(86.1%, PCONCLUSION: Nasal inflammation was an important factor in the incidence of nasolacrimal duct obstruction, which shoud pay more attention in the process of diagnosis and treatment. Combination therapy could improve the cure rate of nasolacrimal duct obstruction.

  11. Salivary duct carcinoma of the palate

    Directory of Open Access Journals (Sweden)

    Ponniah I

    2005-01-01

    Full Text Available Salivary duct carcinoma is a rare high-grade neoplasm that more frequently affects the parotid gland. Though neoplasms of this type are infrequent in minor salivary glands, they are less aggressive and may lead to early diagnosis before distant metastases could occur. Salivary duct carcinoma is also the most frequent epithelial component of carcinosarcoma. The present article reports a case of SDC of the palate in a 26-year-old male and discusses SDC as a malignant epithelial component in carcinosarcoma.

  12. Collecting duct carcinoma associated with oncocytoma

    Directory of Open Access Journals (Sweden)

    George M. Yousef

    2005-10-01

    Full Text Available Collecting duct carcinoma (CDC is a rare, highly aggressive malignant neoplasm that arises from the collecting duct epithelium of the kidney. CDC was reported to coexist with renal cell and transitional cell carcinomas. We report a rare case of CDC associated with oncocytoma, confirmed by the characteristic histological appearance and immunohistochemistry. We also review the epidemiological, histological and immunohistochemical criteria for diagnosis, in addition to the genetic and cytogenetic aberrations reported in the literature. Identification and reporting CDC is important for the establishment of treatment strategies and monitoring prognosis.

  13. Acoustic power balance in lined ducts

    Science.gov (United States)

    Eversman, W.

    1979-01-01

    It is shown that the two common definitions of acoustic energy density and intensity in uniform unlined ducts carrying uniform flow are compatible to the extent that both energy densities can be used in an appropriate variational principle to derive the convected wave equation. When the duct walls are lined both energy densities must be modified to account for the wall energy density. This results in a new energy conservation equation which utilizes a modified definition of axial power and accounts for wall dissipation. Computations in specific cases demonstrate the validity of the modified acoustic energy relation.

  14. Low-cost orbiting grinder for cutting ducts

    Science.gov (United States)

    Lang, E. J.

    1970-01-01

    Low-cost, portable machine cuts ducts made from heat-treated alloys. An abrasive wheel, powered by a high-speed air motor mounted on an expandible plug against the inner wall of the duct, gives precise cutting.

  15. HORIZONTAL BOILING REACTOR SYSTEM

    Science.gov (United States)

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  16. NUMERICAL DETERMINATION OF HORIZONTAL SETTLERS PERFORMANCE

    Directory of Open Access Journals (Sweden)

    M. M. Biliaiev

    2015-08-01

    Full Text Available Purpose.Horizontal settlers are one of the most important elements in the technological scheme of water purification. Their use is associated with the possibility to pass a sufficiently large volume of water. The important task at the stage of their designing is evaluating of their effectiveness. Calculation of the efficiency of the settler can be made by mathematical modeling. Empirical, analytical models and techniques that are currently used to solve the problem, do not allow to take into account the shape of the sump and various design features that significantly affects the loyalty to a decision on the choice of the size of the settling tank and its design features. The use of analytical models is limited only to one-dimensional solutions, does not allow accounting for nonuniform velocity field of the flow in the settler. The use of advanced turbulence models for the calculation of the hydrodynamics in the settler complex forms now requires very powerful computers. In addition, the calculation of one variant of the settler may last for dozens of hours. The aim of the paper is to build a numerical model to evaluate the effectiveness of horizontal settling tank modified design. Methodology. Numerical models are based on: 1 equation of potential flow; 2 equation of inviscid fluid vortex flow; 3 equation of viscous fluid dynamics; 4 mass transfer equation. For numerical simulation the finite difference schemes are used. The numerical calculation is carried out on a rectangular grid. For the formation of the computational domain markers are used. Findings.The models allow calculating the clarification process in the settler with different form and different configuration of baffles. Originality. A new approach to investigate the mass transfer process in horizontal settler was proposed. This approach is based on the developed CFD models. Three fluid dynamics models were used for the numerical investigation of flows and waste waters purification

  17. HVAC; Heating, Ventilation, Air Conditioning - Aerosol Duct Sealant

    Science.gov (United States)

    2016-09-01

    Expeditionary Warfare Center. This technology internally seals leaks in air distribution ducts by injecting a fog of aerosolized sealant particles...Duct Sealant The Aeroseal™ duct sealant technology was demonstrated in four buildings at four different Navy facilities around the country...climatic conditions and different air distribution systems types. Data on thermal energy and fan power was collected before and after the duct sealant

  18. Mechanisms of Lower Bile Duct Stricture in Autoimmune Pancreatitis

    OpenAIRE

    Watanabe, Takayuki; Maruyama, Masahiro; Ito, Tetsuya; Maruyama, Masafumi; Muraki, Takashi; Hamano, Hideaki; Arakura, Norikazu; Hasebe, Osamu; Kawa, Shigeyuki

    2014-01-01

    Objectives We attempted to clarify the mechanism underlying lower bile duct stricture in autoimmune pancreatitis. Methods Imaging and histologic finding of the bile duct were assessed for 73 patients with autoimmune pancreatitis to clarify whether IgG4-related biliary inflammation or pancreatic head swelling is associated with lower bile duct stricture. Results Lower bile duct stricture was found in 59 (81%) patients. Pancreatic head swelling was significantly more frequent among patients wit...

  19. Gravity currents in non-rectangular cross-area channels with stratified ambient

    Science.gov (United States)

    Ungarish, Marius

    2014-11-01

    The propagation of a high-Reynolds-number gravity current (GC) in a horizontal channel along the horizontal coordinate x is considered. The current is of constant density, ρc, and the ambient has a linear stable stratification, from ρb at the bottom z = 0 to ρo at z = H . The cross-section of the channel is given by the general -f1 (z) model is developed for the solution of a GC of fixed volume released from a lock on the bottom (ρc >=ρb). The dependent variables are the position of the interface, h (x , t) , and the speed (area-averaged), u (x , t) , where t is time. The cross-section geometry enters the formulation via the width of the channel f (z) =f1 (z) +f2 (z) . For a given f (z) , the free input parameters of are the height ratio H /h0 of ambient to lock and the stratification parameter S = (ρb -ρo) / (ρc -ρo) . The equations of motion are a hyperbolic PDE system. The initial motion displays a ``slumping'' stage with constant speed, calculated analytically. An analytical solution for the long-time self-similar propagation is also available for special cases. The model is a significant generalization of the rectangular-channel analysis.

  20. A two-component NZRI metamaterial based rectangular cloak

    Directory of Open Access Journals (Sweden)

    Sikder Sunbeam Islam

    2015-10-01

    Full Text Available A new two-component, near zero refractive index (NZRI metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.

  1. PRODUCTIVITY OF FRACTURED HORIZONTAL WELLS

    Directory of Open Access Journals (Sweden)

    Stjepan Antolović

    2009-12-01

    Full Text Available The interest and performance of horizontal drilling and completions has increased during the last two decades. Horizontal wells are advantageous compared to vertical wells in thin reservoirs, reservoirs with favorable vertical permeability and reservoirs with water and gas coning problems. In many reservoirs, the ratio of horizontal permeability to the vertical permeability is substantially larger than one and often is close to 10. Thus, these reservoirs are very good candidates for hydraulic fracturing. By hydraulic fracturing one or more fractures are created, which can be longitudinal or orthogonal. By that, flow is altered and it mostly conducts horizontally through reservoir toward horizontal wellbore. With this altered flow, fluid is produced faster, with less pressure loss by fluid unit of produced fluid. Some of the existing mathematical models to determine the productivity of multifractured horizontal wells are presented in this work (the paper is published in Croatian.

  2. Detonation duct gas generator demonstration program

    Science.gov (United States)

    Wortman, Andrew; Brinlee, Gayl A.; Othmer, Peter; Whelan, Michael A.

    1991-01-01

    The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.

  3. Metastatic leiomyosarcoma of the intrapancreatic bile duct.

    Science.gov (United States)

    Perysinakis, Iraklis; Katopodi, Aggeliki; Avlonitis, Spyridon; Georgiadou, Despoina; Choreftaki, Theodosia; Christopoulos, George; Margaris, Ilias

    2013-01-01

    We report the case of a patient with a history of surgically treated pulmonary leiomyosarcoma, presenting with recurrent acute cholangitis and metastatic leiomyosarcoma of the common bile duct. Preoperative examinations had revealed a high grade malignant neoplasm and bilateral lung metastases. The patient underwent pylorus-preserving pancreaticoduodenectomy and survived for 5.5 years after the first diagnosis.

  4. Whistler instability in a magnetospheric duct

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, I.; Tripathi, V.K. (Indian Inst. of Tech., New Delhi (India). Dept. of Physics); Jain, V.K. (Jawaharlal Nehru Univ., New Delhi (India). School of Environmental Sciences)

    1989-04-01

    A whistler wave propagating through a preformed magnetospheric duct is susceptible to growth/amplification by an electron beam. The interaction is non-local and could be of Cerenkov or slow-cyclotron type. First-order perturbation theory is employed to obtain the growth rate for flat and Gaussian beam densities. (author).

  5. Transhorizon Radiowave Propagation due to Evaporation Ducting ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 1. Transhorizon Radiowave Propagation due to Evaporation Ducting - The Effect of Tropospheric Weather Conditions on VHF and UHF Radio Paths Over the Sea. Salil David Gunashekar D R Siddle E M Warrington. General Article Volume 11 ...

  6. Idea Bank: Duct Tape Note Twister

    Science.gov (United States)

    McHenry, Molly

    2008-01-01

    In this article, the author relates how she observed a middle school math teacher deliver a miserable class. She realized that she did the same thing to her music students. To engage her students, she developed "Note Twister," a music reading game using duct tape to form musical notes and the basic premise behind the game,…

  7. Persistent Mullerian Duct Syndrome with Transverse Testicular ...

    African Journals Online (AJOL)

    inguinal side. The opposite scrotum is empty. PMDS with. TTE is rare. We report a case of PMDS with TTE discovered during surgery for a right inguinal hernia in a 25-year-old male. Key words: Mullerian inhibiting factor, persistent. Mullerian duct syndrome, transverse testicular ectopia. Address for correspondence: Dr. P.

  8. Surgical treatment of congenital biliary duct cyst

    Directory of Open Access Journals (Sweden)

    Wang De-chun

    2012-03-01

    Full Text Available Abstract Background It is acknowledged that total cyst excision is a safe and ideal surgical treatment for congenital biliary duct cyst, compared to simple internal drainage. The aim of this study was to determine the optimal operation occasion and the effect of laparoscopy on congenital biliary duct cyst based upon total cyst excision. Methods From January 2002 to January 2011, 217 patients were admitted to Southwest Hospital for congenital biliary duct cyst. To determine the optimal surgery occasion, we divided these subjects into three groups, the infant group (age ≤ 3 years, the immaturity group (3 18 years, and then evaluated the feasibility, risk and long-term outcome after surgery in the three groups. To analyze the effect of laparoscopic technique on congenital biliary duct cyst, we divided the patients into the laparoscopy and the open surgery groups. Results Among the three groups, the morbidity from cholangiolithiasis before surgical treatment had obvious discrepancy (p 0.05. Similarly, no significant discrepancy was observed in the morbidity from postoperative complications or long-term postoperative complications (p > 0.05 between the laparoscopic and the open surgery groups. Conclusions We conclude that total cyst excision should be performed as early as possible. The optimal treatment occasion is the infant period, and laparoscopic resection may be a new safe and feasible minimally invasive surgery for this disease.

  9. Congenital nasolacrimal duct obstruction: irrigation or probing?

    Science.gov (United States)

    Kim, Y S; Moon, S C; Yoo, K W

    2000-12-01

    The authors investigated the efficacy of antibiotic irrigation as the therapeutic option in congenital nasolacrimal duct obstruction. We retrospectively reviewed the medical record of 76 patients' eyes in whom congenital nasolacrimal duct obstruction had been diagnosed. In 50 of these patients, the colonizing microorganism was identified and, irrigation through canaliculi was performed using antibiotics of suitable sensitivity. Nasolacrimal system probing was performed on 26 patients as the control group. Treatment was regarded successful when over a 4 week period epiphora or mucous discharge disappeared and when saline passed without resistance on irrigation. 96.0% of patients in the irrigation group and 84.6% of patients in probing group were treated successfully. There was no statistical difference in the success rate between the two groups (P = 0.173). The recovery period based on culture results was 3.22 +/- 0.37 months in the group in which microorganisms were isolated and 2.39 +/- 0.35 months in the group in which no organisms were isolated. There were no statistically significant differences in the success rates between the group in which there was growth and the group in which there was no growth (P = 0.1308). Thus a similar result was obtained using nasolacrimal probing and canaliculus antibiotic irrigation in congenital nasolacrimal duct obstruction. Antibiotic irrigation is a safe and simple therapeutic option in congenital nasolacrimal duct obstruction.

  10. Ducted wind turbines : A potential energy shaper

    NARCIS (Netherlands)

    Dighe, V.V.

    2016-01-01

    In order to harvest wind resources more efficiently and to the greatest extent possible, unconventional wind turbine designs have been proposed, but never gained any acceptance in the marketplace. A team of researchers from TU Delft plans to revisit the concept of ducted wind turbines, which have

  11. Surgical management for bile duct injury.

    Science.gov (United States)

    Feng, Xiaobin; Dong, Jiahong

    2017-09-12

    The management of bile duct injury (BDI) remains a considerable challenge in hepatobiliary surgery. BDI is mainly iatrogenic, and mostly occurs in cholecystectomy. Laparoscopic cholecystectomy (LC) has been performed widely, however, the incidence of BDI associated with LC increases 2-3 times compared to that in open cholecystectomy (OC). BDI also occurs in robotic cholecystectomy. In China, the evidence-based Practice Guideline for Diagnosis and Treatment of BDI was published by the Biliary Surgery Group of Surgery Branch of Chinese Medical Association, with the purpose of reducing the incidence of BDI as well as promoting its optimal diagnosis and treatment. Surgery remains the mainstay of treatment for BDI and traumatic bile duct stricture. The definitive repair involves a series of procedures including exposing the proximal and distal bile duct, anastomotic bile duct tissue preparation, minimally invasive tissue anastomoses, and so on. Successful management is a surgical challenge requiring great specialized experience and precise surgical skill. The application of precision biliary surgery is recommended for promoting standardized management of BDI.

  12. Surgical management of Stenson's duct injury using epidural ...

    African Journals Online (AJOL)

    Stenson's duct of parotid gland is a major duct which drains saliva into the oral cavity. Deep penetrating wound in the form of cut or crush injury to the buccal ... These conditions are difficult to diagnose because of complex anatomy and variable nature of injury. Successful management of parotid duct injury depends on early ...

  13. Persistent Mullerian Duct Syndrome (PMDS With Large Intraabdominal Seminoma

    Directory of Open Access Journals (Sweden)

    Della Harigovind

    2017-07-01

    Full Text Available Persistent Mullerian Duct Syndrome, a form of male pseudohermaphroditism is characterized by the presence of the Mullerian duct derivatives in an otherwise phenotypically as well as genotypically normal male. We report a case of large intra abdominal seminoma in a male patient with cryptorchidism, along with persistence of Mullerian duct derivatives (uterus.

  14. Affections of the salivary ducts in buffaloes | Misk | Open Veterinary ...

    African Journals Online (AJOL)

    Exploratory puncture and radiography were used for confirmation of diagnosis. Intraoral marsupialization was performed for treatment of parotid duct ectasia. Salivary fistula was corrected by one of two successful techniques; the first by reconstruction of the parotid duct and the second by ligation of the parotid duct just ...

  15. Laser-Guided Repair of Complex Bile Duct Strictures

    NARCIS (Netherlands)

    van Gulik, Thomas; Beek, Johan; de Reuver, Philip; Aronson, Daniel; van Delden, Otto; Busch, Olivier; Gouma, Dirk

    2009-01-01

    Background: The repair of bile duct strictures (BDS) requires identification of healthy bile duct proximal to the stenosis. Identification may be difficult in complex bile duct injuries after cholecystectomy or partial liver resection. Aim: We describe a technique to identify the prestenotic bile

  16. Termination pattern of the main and accessory pancreatic ducts ...

    African Journals Online (AJOL)

    The pancreas has the main and occasionally a patent accessory pancreatic ducts that carry secretions to the duodenum. Anatomical studies on these ducts are limited. The present study observed the anatomy of the two ducts in eighty six Tanzanians' autopsy subjects to find out if the pattern is similar to those reported from ...

  17. Laser-guided repair of complex bile duct strictures.

    NARCIS (Netherlands)

    Gulik, T. van; Beek, J.; Reuver, P. de; Aronson, D.C.; Delden, O. van; Busch, O.; Gouma, D.

    2009-01-01

    BACKGROUND: The repair of bile duct strictures (BDS) requires identification of healthy bile duct proximal to the stenosis. Identification may be difficult in complex bile duct injuries after cholecystectomy or partial liver resection. AIM: We describe a technique to identify the prestenotic bile

  18. A new metamaterial-based wideband rectangular invisibility cloak

    Science.gov (United States)

    Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.

    2018-02-01

    A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.

  19. GARCON - Genetic Algorithm for Rectangular Cuts OptimizatioN.

    CERN Document Server

    Drozdetskiy, A

    2007-01-01

    We will present Genetic Algorithm for Rectangular Cuts OptimizatioN (GARCON) program and demonstrate its functionality on a simple HEP analysis example. The program automatically performs rectangular cuts optimization and verification for stability in a multi-dimensional cuts phase space. The program has been successfully used by a number of different analyses presented in the Compact Muon Solenoid (CMS collaboration) Physics Technical Design Report (Large Hadron Collider (LHC), CERN, Geneva, Switzerland), corresponding results are also published in a number of papers in 2006.

  20. Experimental evaluation of gas filled plenum (GFP) insulation for ducts

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain S.; Guillot, Cyril

    2003-01-26

    Forced-air heating and cooling system ducts are often located outside conditioned space in US houses. For these systems to perform efficiently it is important that these ducts be well insulated. Common practice is to use a glass fiber wrap around the ducts--either field applied or more commonly, integrated into a flexible duct. Most duct insulation has an R-value of 4.2, with R6 and R8 ducts also occasionally used. With glass fiber insulation being about R4 per inch (RSI 0.28/cm), this adds 2 to 4 inches (50 to 100 mm) to the duct diameter. Some building codes are now requiring these higher insulation levels, for example, the EPA requires the use of R6 ducts (for Energy Star ducts), and International Energy Conservation Code (BOCA 2003) requires R8 ducts. The difficulty with adding insulation to ducts is the increase in diameter of the ducts that makes them expensive to transport because they take up a large volume and are difficult to install in the confined spaces available for ducts in houses. The objective of this study was to evaluate Gas Filled Plenum (GFP) technology as an alternative duct insulation. GFP ducts have the potential to provide greater insulation levels than existing ducts (for a given thickness of insulation or size of duct) and provide cost savings in transportation. These transportation cost savings are based on the idea of shipping the GFP ducts empty and inflating them on-site. To evaluate this technology for ducts we constructed a prototype duct and determined both its flow and heat transfer resistance in LBNL's duct testing laboratories. The GFP technology works by encapsulating a gas (usually air--but other noble gases such as Argon or Krypton can provide significant increases in thermal resistance with increased cost) in a metalized film jacket. A honeycomb structure is used to keep individual gas pockets small to minimize convection heat transfer. A metallic finish (usually aluminum) minimizes radiation heat transfer between the

  1. Late Probing for Congenital Nasolacrimal Duct Obstruction

    Directory of Open Access Journals (Sweden)

    Mohammad Abrishami

    2009-04-01

    Full Text Available

    PURPOSE: To report the results of late nasolacrimal duct probing in patients with congenital nasolacrimal duct obstruction (NLDO. METHODS: This retrospective study was performed on a consecutive series of patients with congenital NLDO who underwent late (after 15 months of age nasolacrimal duct probing for the first time. RESULTS: Over a period of five years, 158 patients including 75 (47.4% male and 83 (52.6% female subjects with mean age of 3±4.2 years (range, 15 months to 37 years underwent initial probing for NLDO. Nasolacrimal duct probing was performed unilaterally in 78% and bilaterally in 22% of the patients. Success rate was 75% overall, 72% in unilateral cases and 83% in bilateral instances. Success rate was not correlated with age at intervention. CONCLUSIONS: Nasolacrimal duct probing seems to be reasonably successful for treatment of congenital NLDO in patients older than 15 months who are seen for the first time. Silicone intubation or dacryocystorhinostomy should be reserved for refractory cases.

  2. Analysis of High Tc Superconducting Rectangular Microstrip Patches over Ground Planes with Rectangular Apertures in Substrates Containing Anisotropic Materials

    Directory of Open Access Journals (Sweden)

    Abderraouf Messai

    2013-01-01

    Full Text Available A rigorous full-wave analysis of high Tc superconducting rectangular microstrip patch over ground plane with rectangular aperture in the case where the patch is printed on a uniaxially anisotropic substrate material is presented. The dyadic Green’s functions of the considered structure are efficiently determined in the vector Fourier transform domain. The effect of the superconductivity of the patch is taken into account using the concept of the complex resistive boundary condition. The accuracy of the analysis is tested by comparing the computed results with measurements and previously published data for several anisotropic substrate materials. Numerical results showing variation of the resonant frequency and the quality factor of the superconducting antenna with regard to operating temperature are given. Finally, the effects of uniaxial anisotropy in the substrate on the resonant frequencies of different TM modes of the superconducting microstrip antenna with rectangular aperture in the ground plane are presented.

  3. Natural convection heat transfer within horizontal spent nuclear fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Canaan, R.E.

    1995-12-01

    Natural convection heat transfer is experimentally investigated in an enclosed horizontal rod bundle, which characterizes a spent nuclear fuel assembly during dry storage and/or transport conditions. The basic test section consists of a square array of sixty-four stainless steel tubular heaters enclosed within a water-cooled rectangular copper heat exchanger. The heaters are supplied with a uniform power generation per unit length while the surrounding enclosure is maintained at a uniform temperature. The test section resides within a vacuum/pressure chamber in order to subject the assembly to a range of pressure statepoints and various backfill gases. The objective of this experimental study is to obtain convection correlations which can be used in order to easily incorporate convective effects into analytical models of horizontal spent fuel systems, and also to investigate the physical nature of natural convection in enclosed horizontal rod bundles in general. The resulting data consist of: (1) measured temperatures within the assembly as a function of power, pressure, and backfill gas; (2) the relative radiative contribution for the range of observed temperatures; (3) correlations of convective Nusselt number and Rayleigh number for the rod bundle as a whole; and (4) correlations of convective Nusselt number as a function of Rayleigh number for individual rods within the array.

  4. Experimental evaluation of gas filled plenum (GFP) insulation for ducts

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain S.; Guillot, Cyril

    2003-01-26

    Forced-air heating and cooling system ducts are often located outside conditioned space in US houses. For these systems to perform efficiently it is important that these ducts be well insulated. Common practice is to use a glass fiber wrap around the ducts--either field applied or more commonly, integrated into a flexible duct. Most duct insulation has an R-value of 4.2, with R6 and R8 ducts also occasionally used. With glass fiber insulation being about R4 per inch (RSI 0.28/cm), this adds 2 to 4 inches (50 to 100 mm) to the duct diameter. Some building codes are now requiring these higher insulation levels, for example, the EPA requires the use of R6 ducts, and International Energy Conservation Code (BOCA 2003) requires R8 ducts. The difficulty with adding insulation to ducts is the increase in diameter of the ducts that makes them expensive to transport because they take up a large volume and are difficult to install in the confined spaces available for ducts in houses. The objective of this study was to evaluate Gas Filled Plenum (GFP) technology as an alternative duct insulation. GFP ducts have the potential to provide greater insulation levels than existing ducts (for a given thickness of insulation or size of duct) and provide cost savings in transportation. These transportation cost savings are based on the idea of shipping the GFP ducts empty and inflating them on-site. To evaluate this technology for ducts we constructed a prototype duct and determined both its flow and heat transfer resistance in LBNL's duct testing laboratories. The GFP technology works by encapsulating a gas (usually air--but other noble gases such as Argon or Krypton can provide significant increases in thermal resistance with increased cost) in a metalized film jacket. A honeycomb structure is used to keep individual gas pockets small to minimize convection heat transfer. A metallic finish (usually aluminum) minimizes radiation heat transfer between the surfaces.

  5. Performance Study and CFD Predictions of a Ducted Fan System

    Science.gov (United States)

    Abrego, Anita I.; Chang, I-Chung; Bulaga, Robert W.; Rutkowski, Michael (Technical Monitor)

    2002-01-01

    An experimental investigation was completed in the NASA Ames 7 by 10-Foot Wind Tunnel to study the performance characteristics of a ducted fan. The goal of this effort is to study the effect of ducted fan geometry and utilize Computational Fluid Dynamics (CFD) analysis to provide a baseline for correlation. A 38-inch diameter, 10-inch chord duct with a five-bladed fixed-pitch fan was tested. Duct performance data were obtained in hover, vertical climb, and forward flight test conditions. This paper will present a description of the test, duct performance results and correlation with CFD predictions.

  6. A wideband rectangular-ring textile antenna integrated with corner-notched artificial magnetic conductor (AMC) plane

    Science.gov (United States)

    Aun, N. F. M.; Soh, P. J.; Jamlos, M. F.; Lago, H.; Al-Hadi, A. A.

    2017-01-01

    This paper presents the design of a wideband artificial magnetic conductor (AMC) for operation in the Wireless Body Area Network Ultra Wideband (WBAN-UWB) mandatory channel 6. The proposed AMC is incorporated onto a rectangular-ring patch antenna for operation centered at 8 GHz with 2 GHz of bandwidth. The incorporation of the AMC improved the antenna reflection coefficient and impedance bandwidth, besides shielding the radiator against on-body detuning. The prototype is fully fabricated using textiles except for an SMA connector used for feeding. It is observed that the experimental results are in good agreement with the simulations, and bandwidth broadening is successfully achieved and validated.

  7. Rectangular grids formed by hydrogen-bonding interactions ...

    Indian Academy of Sciences (India)

    Administrator

    Rectangular grids formed by hydrogen-bonding interactions between successive chains of linear polymers. [Co(II)-4,4¢-bpy-Co(II)]n and their inclusion properties: Synthesis and single crystal investigations. E SURESH 1 and MOHAN M BHADBHADE 2. 1Silicates and Catalysis Division, Central Salt & Marine Chemicals ...

  8. direct method of analysis of an isotropic rectangular plate direct ...

    African Journals Online (AJOL)

    eobe

    This work. This work evaluates the static analysis of an isotropic rectangular plate with various ... used to obtain the total potential energy of the plate by employing the static elastic theory of plate. static elastic theory of plate. The shape func he shape func he shape .... finite site particles and the overall response of such a.

  9. stability analysis of ssss thin rectangular plate using multi

    African Journals Online (AJOL)

    user

    The stability analysis of all four edges simply supported (SSSS) thin rectangular plate using multi-degrees of freedom (MDOF) Taylor ... polynomial function in plates' continuum analysis other than SDOF. In which .... The percentage differences (error) between this study, Ibearugbulem et. al and Ezeh et. al with of those of ...

  10. Dynamic response of ground supported rectangular water tanks to ...

    African Journals Online (AJOL)

    ... reinforced concrete rectangular water tank under earthquake excitation. A linear three-dimensional finite element analysis and SAP2000 software have been used to predict tank response. The variable analysis parameters considered are the aspect ratio (tank height to length ratio) and tank water level, while the tank wall ...

  11. Hydroelastic analysis of a rectangular plate subjected to slamming loads

    Science.gov (United States)

    Wang, Shan; Guedes Soares, C.

    2017-12-01

    A hydroelastic analysis of a rectangular plate subjected to slamming loads is presented. An analytical model based on Wagner theory is used for calculations of transient slamming load on the ship plate. A thin isotropic plate theory is considered for determining the vibration of a rectangular plate excited by an external slamming force. The forced vibration of the plate is calculated by the modal expansion method. Analytical results of the transient response of a rectangular plate induced by slamming loads are compared with numerical calculations from finite element method. The theoretical slamming pressure based on Wagner model is applied on the finite element model of a plate. Good agreement is obtained between the analytical and numerical results for the structural deflection of a rectangular plate due to slamming pressure. The effects of plate dimension and wave profile on the structural vibration are discussed as well. The results show that a low impact velocity and a small wetted radial length of wave yield negligible effects of hydroelasticity.

  12. End depth in steeply sloping rough rectangular channels

    Indian Academy of Sciences (India)

    The paper presents a theoretical model to compute the end depth of a free overfall in steeply sloping rough rectangular channels. A momentum equation based on the Boussinesq approximation is applied to obtain the equation of the end depth. The effect ofstreamline curvature at the free surface is utilized to develop the ...

  13. On Typical Elastic Problem of Green's Function For Rectangular ...

    African Journals Online (AJOL)

    ... is on the method of the separation of variables. Here, the Green's function of the Neumann's problem for Poisson's equation is adopted. Unlike the problems of the full and half strips, the problem of the rectangular strip admits known formulae of the hyperbolic functions in addition to conventional trigonometric functions.

  14. FDTD Analysis of U-Slot Rectangular Patch Antenna

    Science.gov (United States)

    Luk, K. M.; Tong, K. F.; Shum, S. M.; Lee, K. F.; Lee, R. Q.

    1997-01-01

    The U-slot rectangular patch antenna (Figure I) has been found experimentally to provide impedance and gain bandwidths of about 300 without the need of stacked or coplanar parasitic elements [1,2]. In this paper, simulation results of the U-slot patch using FDTD analysis are presented. Comparison with measured results are given.

  15. A bounds on the resonant frequency of rectangular microstrip antennas

    Science.gov (United States)

    Bailey, M. C.

    1980-01-01

    The calculation of currents induced by a transverse electric plane wave normally incident upon an infinite strip embedded in a grounded dielectric slab is used to infer a lower bound on the resonant frequency (or resonant-E-plane dimension) for rectangular microstrip antennas. An upper bound is provided by the frequency for which the E-plane dimension is a half-wavelength.

  16. Dynamic Response of Ground Supported Rectangular Water Tanks ...

    African Journals Online (AJOL)

    Bheema

    Review of design Codes. Some of the structural design codes that tackle fluid tank systems are the American Concrete. Institute, ACI 350.3, the Euro Code 8 and the Standards Association of New Zealand, NZS. These codes address ground supported circular and rectangular concrete tanks having fixed or flexible bases.

  17. Relationship between room shape and acoustics of rectangular concert halls

    DEFF Research Database (Denmark)

    Klosak, Andrzej K.; Gade, Anders Christian

    2008-01-01

    Extensive acoustics computer simulations have been made using Odeon computer simulation software. In 24 rectangular rooms representing "shoe-box" type concert halls with volumes of 8 000 m3, 12 000 m3 and 16 000 m3 from 300 to 850 measurements positions have been analysed. Only room averaged...

  18. Optical vortex propagation in few-mode rectangular polymer waveguides

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir S.; Chipouline, Arkadi; Zywietz, Urs

    2017-01-01

    We demonstrate that rectangular few-mode dielectric waveguides, fabricated with standard lithographic technique, can support on-chip propagation of optical vortices. We show that specific superpositions of waveguide eigenmodes form quasi-degenerate modes carrying light with high purity states...

  19. Analysis of Rectangular Microstrip Antennas with Air Substrates ...

    African Journals Online (AJOL)

    This paper presents an analysis of rectangular microstrip antennas with air substrates. The effect of the substrate thickness on the bandwidth and the efficiency are examined. An additional thin layer supporting the dielectric material is added to the air substrate in order to make the antenna mechanically rigid and easy to ...

  20. Evaluation of Double Perforated Baffles Installed in Rectangular Secondary Clarifiers

    Directory of Open Access Journals (Sweden)

    Byonghi Lee

    2017-06-01

    Full Text Available Double perforated baffles in rectangular secondary clarifiers were studied to determine whether they contribute to producing high-quality effluents. The Computational Fluid Dynamics (CFD simulations indicated that bio-flocculation occurred at the front of the baffle and the longitudinal movement of the settled sludge was hampered whenever the clarifier had high inflow. Simulation results showed that the rectangular clarifier with the double perforated baffle produced an effluent with lower suspended solid (SS concentrations than the effluent from the clarifier without the baffle. To verify the simulation results, a double perforated baffle was installed in two of the 48 rectangular clarifiers in a 300,000 m3/d-capacity wastewater treatment plant. To study the effect of the baffle on solid removal, the effluent turbidity of the clarifier with and without the double perforated baffle was measured simultaneously. Experimental data showed that the double perforated baffle played a significant role in reducing effluent turbidity. The effluent turbidity reduction ratio with the baffle decreased when the Sludge Volume Index (SVI of the Mixed Liquor Suspended Solids (MLSS was below 100 mL/g. The overall average reduction ratio was 24.3% for SVI < 100 mL/g and 45.1% for SVI > 100 mL/g. The results of this study suggest that double perforated baffles must be installed in secondary rectangular clarifiers to produce high-quality effluent regardless of the operational conditions.

  1. analytical bending solution of all clamped isotropic rectangular plate

    African Journals Online (AJOL)

    HP

    to the governing differential equation of the plate on Winkler foundation to obtain the deflection coefficient, . Numerical example was presented at the end to compare the results obtained by this method and those from earlier studies. The percentage difference obtained for central deflection of all clamped rectangular plate ...

  2. Energy levels in rectangular quantum well wires based on a ...

    Indian Academy of Sciences (India)

    Abstract. The effect of a spatially dependent effective mass on the energy levels in a rectangular quantum wire with finite barrier potential is considered. The heterojunction is modelled by an error function rather than a step function to more accurately model the material transition region at the interface between the two ...

  3. The problem of isotropic rectangular plate with four clamped edges

    Indian Academy of Sciences (India)

    ... received considerable attention because of its technical importance. This paper analyses the deflections of an isotropic rectangular clamped thin plates under uniformly distributed loads. A plate is called thin when its thickness is at least one order of magnitude smaller than the span of the plate. The bending and buckling.

  4. Natural convection in rectangular enclosures with one thermally ...

    African Journals Online (AJOL)

    Natural convective fluid flow and heat transfer in rectangular enclosures bounded by three adiabatic walls and one thermally active and differentially heated vertical side were predicted by using the finite difference method. The effects of different temperature functions, aspect ratio and Rayleigh numbers on the natural ...

  5. Plasma-filled rippled wall rectangular backward wave oscillator ...

    Indian Academy of Sciences (India)

    Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-filled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma ...

  6. Hydroelastic analysis of a rectangular plate subjected to slamming loads

    Science.gov (United States)

    Wang, Shan; Guedes Soares, C.

    2017-10-01

    A hydroelastic analysis of a rectangular plate subjected to slamming loads is presented. An analytical model based on Wagner theory is used for calculations of transient slamming load on the ship plate. A thin isotropic plate theory is considered for determining the vibration of a rectangular plate excited by an external slamming force. The forced vibration of the plate is calculated by the modal expansion method. Analytical results of the transient response of a rectangular plate induced by slamming loads are compared with numerical calculations from finite element method. The theoretical slamming pressure based on Wagner model is applied on the finite element model of a plate. Good agreement is obtained between the analytical and numerical results for the structural deflection of a rectangular plate due to slamming pressure. The effects of plate dimension and wave profile on the structural vibration are discussed as well. The results show that a low impact velocity and a small wetted radial length of wave yield negligible effects of hydroelasticity.

  7. Graphene-based tunable terahertz filter with rectangular ring ...

    Indian Academy of Sciences (India)

    WEI SU

    2017-08-16

    Aug 16, 2017 ... Abstract. A plasmonic band-pass filter based on graphene rectangular ring resonator with double narrow gaps is proposed and numerically investigated by finite-difference time-domain (FDTD) simulations. For the filter with or without gaps, the resonant frequencies can be effectively adjusted by changing ...

  8. Graphene-based tunable terahertz filter with rectangular ring ...

    Indian Academy of Sciences (India)

    A plasmonic band-pass filter based on graphene rectangular ring resonator with double narrow gaps is proposed and numerically investigated by finite-difference time-domain (FDTD) simulations. For the filter with or without gaps, the resonant frequencies can be effectively adjusted by changing the width of the graphene ...

  9. Biaxial charts for rectangular reinforced columns in accordance with ...

    African Journals Online (AJOL)

    Biaxial charts for rectangular reinforced columns in accordance with the Ethiopian building code standard EBCS-2:Part1. ... Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link above.

  10. 2D Flow around a Rectangular Cylinder: A Computational Study ...

    African Journals Online (AJOL)

    The influence of vortical structure and pressure distribution around the section of rectangular cylinders are examined and reported. The integral aerodynamic parameters are also reported. Strouhal numbers for Reynolds numbers of 55, 75, 100, 150, 250 and 400 are 0.102, 0.122, 0.129, 0.136, 0.139 and 0.158 respectively.

  11. Internal flow characteristics of a rectangular ramjet air intake

    NARCIS (Netherlands)

    Moerel, J.-L.; Veraar, R.G.; Halswijk, W.H.C.; Pimentel, R.; Corriveau, D.; Hamel, N.; Lesage, F.; Vos, J.B.

    2009-01-01

    Two research institutes TNO Defence, Security and Safety and DRDC-Valcartier have worked together on the improvement of modeling and simulation tools for the functioning of supersonic air intakes for realistic ramjet engines of tactical missiles. The emphasis laid on complex rectangular intake

  12. Coupled parametric design of flow control and duct shape

    Science.gov (United States)

    Florea, Razvan (Inventor); Bertuccioli, Luca (Inventor)

    2009-01-01

    A method for designing gas turbine engine components using a coupled parametric analysis of part geometry and flow control is disclosed. Included are the steps of parametrically defining the geometry of the duct wall shape, parametrically defining one or more flow control actuators in the duct wall, measuring a plurality of performance parameters or metrics (e.g., flow characteristics) of the duct and comparing the results of the measurement with desired or target parameters, and selecting the optimal duct geometry and flow control for at least a portion of the duct, the selection process including evaluating the plurality of performance metrics in a pareto analysis. The use of this method in the design of inter-turbine transition ducts, serpentine ducts, inlets, diffusers, and similar components provides a design which reduces pressure losses and flow profile distortions.

  13. Dispersion properties of ducted whistlers, generated by lightning discharge

    Directory of Open Access Journals (Sweden)

    D. L. Pasmanik

    2005-06-01

    Full Text Available Whistler-mode wave propagation in magnetospheric ducts of enhanced cold plasma density is studied. The case of the arbitrary ratio of the duct radius to the whistler wavelength is considered, where the ray-tracing method is not applicable. The set of duct eigenmodes and their spatial structure are analysed and dependencies of eigenmode propagation properties on the duct characteristics are studied. Special attention is paid to the analysis of the group delay time of one-hop propagation of the whistler wave packet along the duct. We found that, in contrast to the case of a wide duct, the group delay time in a rather narrow duct decreases as the eigenmode number increases. The results obtained are suggested for an explanation of some types of multi-component whistler signals.

  14. Effect of grazing flow on structural-acoustic response of an elastic plate with sound in a duct

    Science.gov (United States)

    Manchakattil Sucheendran, Mahesh

    The design of supersonic and hypersonic vehicles involves the challenging task of designing thin panels that can withstand severe unsteady pressure and thermal loads. A good understanding and accurate prediction of the coupled structural-acoustic response of thin panels subjected to sound waves are key elements of this design process. Due to the cost of in-flight testing, the experimental assessment of the structural-acoustic response of skin panels is usually conducted in ground-based facilities consisting of a duct in which acoustic waves propagate at grazing incidence with skin panels mounted along the duct walls. A key limitation of such facility is the absence of flow, the impact of which on the structural-acoustic response of the skin panel is still poorly understood. To shed some insight on this key contribution, this analytical and numerical study focuses on the structural-acoustic interaction of sound with a thin elastic plate mounted flush on a wall in a rectangular duct in the presence of a uniform mean subsonic and supersonic flow. A linear, time-harmonic theory based on modal descriptions of the plate velocity and duct acoustic fields is first developed. The theory includes the effect of uniform mean flow in the duct and clamped and simply-supported boundary conditions for the plate. The sound radiated by the plate is calculated using Doak's theory [22], extended in this work to account for subsonic and supersonic uniform mean flow in the duct, and verified using the numerical solver. The theoretical model provides important insight on the effect of flow in the duct on the coupled response of the plate. Four metrics characterizing the coupled response are considered: the deviation of the peak response frequency from the in vacuo natural frequency of plate, the amplitude of the peak response, the effective acoustic damping of the plate, and the plate modal coupling through the duct acoustic field. The theory is extended to estimate the onset of

  15. Acoustic Power Transmission Through a Ducted Fan

    Science.gov (United States)

    Envia, Ed

    2016-01-01

    For high-speed ducted fans, when the rotor flowfield is shock-free, the main contribution to the inlet radiated acoustic power comes from the portion of the rotor stator interaction sound field that is transmitted upstream through the rotor. As such, inclusion of the acoustic transmission is an essential ingredient in the prediction of the fan inlet noise when the fan tip relative speed is subsonic. This paper describes a linearized Euler based approach to computing the acoustic transmission of fan tones through the rotor. The approach is embodied in a code called LINFLUX was applied to a candidate subsonic fan called the Advanced Ducted Propulsor (ADP). The results from this study suggest that it is possible to make such prediction with sufficient fidelity to provide an indication of the acoustic transmission trends with the fan tip speed.

  16. Renal collecting duct carcinoma in a dog.

    Science.gov (United States)

    Kobayashi, N; Suzuki, K; Shibuya, H; Sato, T; Aoki, I; Nagashima, Y

    2008-07-01

    An 8-year-old, male, mongrel dog developed severe cough and anorexia and died within 3 months. Autopsy revealed an invasive grayish-white mass in the right kidney and multiple nodules in the lungs, thoracic wall, and spleen. Histologically, the renal mass and the other nodules were mainly composed of papillotubular structures lined by oval-to-polygonal pleomorphic cells. The cells were reactive with DBA, PNA, and UEA-1 lectins and positive for vimentin but negative for CD10 and high molecular weight cytokeratin. Because of its histological, histochemical, and immunohistochemical similarities with human collecting duct carcinoma (CDC), a diagnosis of renal collecting duct carcinoma with pulmonary, thoracic, and splenic metastases was established. To our knowledge, this is the first case report of CDC in animals.

  17. Active noise reduction systems in ducts

    Science.gov (United States)

    Tichy, J.; Poole, L. A.; Warnaka, G. E.

    1984-12-01

    Fundamentals of the theory of the sound propagation in ducts with perfectly reflecting walls, relevant to noise reduction systems, is summarized. A brief historical review of the active sound cancellation techniques is given. Systems based on time invariant parameters are analyzed and their inherited drawbacks outlined. A new generation of systems using controllers based on modified adaptive LMS algorithm is described. The measurements in an experimental duct show that the random noise can be reduced by 25-30 dB, while the noise with line spectra can be decreased by up to 40 dB. Good success is also reported with impulse signals which have random time intervals between the pulses.

  18. Heat transfer and fluid flow analysis of artificially roughened ducts having rib and groove roughness

    Science.gov (United States)

    Aharwal, K. R.; Pawar, C. B.; Chaube, Alok

    2014-06-01

    Artificially roughness is one of the well known methods of enhancing heat transfer from the heat transfer surface in the form of repeated ribs, grooves or combination of ribs and groove (compound turbulators). The artificial roughness produced on the heat transferring surface is used in cooling of gas turbine blades, nuclear reactor, solar air heating systems etc. Solar air heaters have wide applications in low to moderate temperature range, namely, drying of foods, agricultural crops, seasoning of wood and space heating etc. Solar air heaters have low value of convective heat transfer coefficient between the working fluid (air) and the heat transferring surface, due to the formation of thin laminar viscous sub-layer on its surface. The heat transfer from the surface can be increased by breaking this laminar viscous sub layer. Hence, in the present work compound turbulators in the form of integral wedge shaped ribs with grooves are used on the heat transfer surface, to study its effect on the heat transfer coefficient (Nusselt number) and friction factor in the range of Reynolds number 3,000-18,000. The roughness produced on the absorber plate forms the wetted side of upper broad wall of the rectangular duct of solar air heater. The relative groove position ( g/p) was varied from 0.4 to 0.8 and the wedge angle (Φ) was varied from 10° to 25°, relative roughness pitch ( p/e) and relative roughness height ( e/D) was maintained as 8.0 and 0.033 respectively. The aspect ratio of the rectangular duct was maintained as 8. The Nusselt number and friction factor of the artificially roughened ducts were determined experimentally and the corresponding values were compared with that of smooth surface duct. It is observed that wedge-groove roughened surface shows more enhancement in heat transfer compared to only rib roughened surface arrangement. The investigation revealed that Nusselt number increases 1.5-3 times, while the friction factor increases two to three folds that

  19. Primary tuberculosis of cystic duct lymph node.

    Science.gov (United States)

    Ghazanfar, Aamir; Asghar, Afifa; Khan, Naqeeb Ullah; Hassan, Iram

    2017-06-16

    Tuberculosis (TC) is very common and significant cause of morbidity and mortality worldwide. Isolated cystic duct lymph node TC cases without involvement of gallbladder are exceedingly rare. It is difficult to diagnose preoperatively because of lack of characteristic signs and symptoms of TC. We report a man aged 45 years who presented with right upper abdominal pain since 1week. It was associated with nausea and postprandial fullness. There was no evidence of jaundice and lymphadenopathy. Abdominal examination showed moderate right upper quadrant tenderness with positive Murphy's sign and splenomegaly but no signs of peritonism. Abdomen ultrasound revealed sludge in gallbladder, dilated pancreatic duct, coarse exotexture of liver, splenomegaly and no lymphadenopathy. He underwent laparoscopic cholecystectomy; histological report showed chronic caseating granulomatous lymphadenitis with Langhans type of giant cells in lymph node near cystic duct with chronic cholecystitis of gallbladder. Standard antituberculosis therapy was given for 12 months. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  20. Performance Analysis of a Shallow Duct Flat Plate Solar Air Heater with and without Porous Media

    Directory of Open Access Journals (Sweden)

    Haroun A.K. Shahad

    2016-12-01

    Full Text Available In this study a flat plate solar air heater with a shallow duct is analyzed experimentally. The collector consists of a 4.5m long air duct with a (20×5cm cross-sectional area. The air duct consists of four channels so that the collector becomes more compact. The collector is studied under the weather conditions of Hilla city – Iraq with latitude and longitude equal 32.3° N and 44.25° E respectively and it is tilted by 45° with the horizontal plane. The effect of the air mass flow rate on the collector performance is also studied.The performance of the collector is analyzed with and without porous media stuffing. The measured parameters are the air and absorber temperatures, air speed and pressure drop. The temperatures are measured by means of type (K thermocouples as this type covers the temperature range of the studied system. The values of the temperature are displayed by temperature data logger devices. The air speed and pressure drop are measured by digital anemometer and manometer devices respectively. The results of the studied system show that as the air mass flow rate increases, the temperature of both the flowing air and the absorber decrease, whilst the efficiency of the collector increases. The results also show that the addition of the steel wool porous material inside the air duct increases the temperature of both the flowing air and the absorber, and by that increases the efficiency of the collector. The porous media also caused an increase in the pressure drop between the outlet air and the atmosphere. This pressure drop increased with the increase in the air mass flow rate

  1. Compact Buried Ducts in a Hot-Humid Climate House

    Energy Technology Data Exchange (ETDEWEB)

    Mallay, Dave [Home Innovation Research Labs, Upper Marlboro, MD (United States)

    2016-01-07

    "9A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval. The primary research question with buried ducts is potential condensation at the outer jacket of the duct insulation in humid climates during the cooling season. Current best practices for buried ducts rely on encapsulating the insulated ducts with closed-cell spray polyurethane foam insulation to control condensation and improve air sealing. The encapsulated buried duct concept has been analyzed and shown to be effective in hot-humid climates. The purpose of this project is to develop an alternative buried duct system that performs effectively as ducts in conditioned space - durable, energy efficient, and cost-effective - in a hot-humid climate (IECC warm-humid climate zone 3A) with three goals that distinguish this project: 1) Evaluation of design criteria for buried ducts that use common materials and do not rely on encapsulation using spray foam or disrupt traditional work sequences; 2) Establishing design criteria for compact ducts and incorporate those with the buried duct criteria to further reduce energy losses and control installed costs; 3) Developing HVAC design guidance for performing accurate heating and cooling load calculations for compact buried ducts.

  2. Unilateral Duplication Of Parotid Duct. A Rare Anatomical Variation

    Directory of Open Access Journals (Sweden)

    Humberto Ferreira Arquez

    2017-11-01

    Full Text Available Background: The paired parotid glands are the largest of the major salivary glands and produces mainly serous secretions. The secretion of this gland reaches the oral cavity through single parotid duct (Stensen’s duct. The parotid duct begins at the anterior border of the gland, crosses the masseter muscle, and then pierces the buccinator muscle to reach the mucosa lining the mouth at the level of the cheek. The purpose of this study is determine the morphologic features of the parotid duct and describe an anatomical variation until now unreported. Methods and Findings: A total of 17 cadavers were used for this study in the Morphology Laboratory at the University of Pamplona. In a cadaver were findings: The main parotid duct originated two conducts: Left superior parotid duct and Left inferior parotid duct, is observed the criss-cross of the ducts, and then perforated the buccinator muscle and entered the oral cavity at a double parotid papilla containing a double opening, separated from each other in 0,98 mm. In the remaining  33 parotid regions (97.06% the parotid duct is conformed to the classical descriptions given in anatomical textbooks. Conclusions: The parotid duct anatomy is important for duct endoscopy, lithotripsy, sialography and trans-ductal facial nerve stimulation in the early stage of facial palsy in some cases. The anatomical variations also has clinical importance for parotid gland surgery and facial cosmetic surgery. To keep in mind the parotid duct variation will reduce iatrogenic injury risks and improve diagnosis of parotid duct injury.

  3. Idiopathic chylopericardium treated by percutaneous thoracic duct embolization after failed surgical thoracic duct ligation

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Malachi; Ayyagari, Raj R. [Yale School of Medicine, Yale New Haven Hospital, New Haven, CT (United States); Division of Interventional Radiology, Department of Radiology, 789 Howard Avenue, P.O. Box 208042, New Haven, CT (United States)

    2015-06-15

    Chylopericardium rarely occurs in pediatric patients, but when it does it is most often a result of lymphatic injury during cardiothoracic surgery. Primary idiopathic chylopericardium is especially rare, with few cases in the pediatric literature. We report a 10-year-old boy who presented with primary idiopathic chylopericardium after unsuccessful initial treatment with surgical lymphatic ligation and creation of a pericardial window. Following readmission to the hospital for a right-side chylothorax resulting from the effluent from the pericardial window, he had successful treatment by interventional radiology with percutaneous thoracic duct embolization. This case illustrates the utility of thoracic duct embolization as a less-invasive alternative to surgical thoracic duct ligation, or as a salvage procedure when surgical ligation fails. (orig.)

  4. Granular Cell Tumour of the Bile Duct in Association with Intrahepatic Bile Duct Adenomas

    Directory of Open Access Journals (Sweden)

    F Schweiger

    1994-01-01

    Full Text Available Granular cell tumour of the extrahepatic biliary tract is a rare benign lesion likely of neurogenic origin. Review of the previously reported cases indicates that almost all patients are female, and the majority is Black. Symptoms usually are those of biliary obstruction or cholecystitis. Surgical resection of the tumour is curative. Intrahepatic bile duct adenoma is another rare benign biliary neoplasm that does not manifest clinically but can be confused with metastatic carcinoma, cholangiocarcinoma or other focal liver lesions at laparotomy or autopsy. The authors report the case of an asymptomatic Caucasian woman with biochemical evidence of liver disease who had a granular cell tumour of the bile duct as well as several intrahepatic bile duct adenomas.

  5. Pathological spectrum of bile duct lesions from chronic bile duct injury to invasive cholangiocarcinoma corresponding to bile duct imaging findings of occupational cholangiocarcinoma.

    Science.gov (United States)

    Kinoshita, Masahiko; Kubo, Shoji; Nakanuma, Yasuni; Sato, Yasunori; Takemura, Shigekazu; Tanaka, Shogo; Hamano, Genya; Ito, Tokuji; Terajima, Hiroaki; Yamada, Terumasa; Nakamori, Shoji; Arimoto, Akira; Fujikawa, Masahiro; Sugawara, Yasuhiko; Yamamoto, Takatsugu; Abue, Makoto; Nakagawa, Kei; Unno, Michiaki; Mizuguchi, Toru; Takenaka, Kenji; Shirabe, Ken; Shibata, Toshihiko

    2016-02-01

    We aimed to identify the pathological characteristics of occupational cholangiocarcinoma. We examined the location and distribution of the carcinomas: atypical epithelium including biliary intraepithelial neoplasia (BilIN) and intraductal papillary neoplasm of the bile duct (IPNB); and chronic bile duct injuries in operative or autopsy liver specimens from 16 patients. We examined the detailed pathological findings and diagnostic imaging of three patients. Immunohistochemical analysis using primary antibodies against γH2AX and S100P was performed. BilIN and chronic bile duct injury were observed in 16 patients, and IPNB or invasive IPNB was observed in 11 patients. BilIN, IPNB, and/or chronic bile duct injury were observed in almost all the large bile ducts. Regional dilatation of the bile ducts without tumor-induced obstruction revealed such pathological changes. Highly positive results for the γH2AX and S100P markers were noted in invasive carcinoma, BilIN, and IPNB, whereas positive results for γH2AX and negative results for S100P were noted in non-neoplastic biliary epithelium. The carcinogenic process of occupational cholangiocarcinoma comprised chronic bile duct injury and DNA damage in almost all the large bile ducts, along with induction of precancerous lesions and development of invasive carcinoma. Such pathological findings reflected radiological changes on diagnostic imaging. © 2015 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  6. Horizontal and Vertical Line Designs.

    Science.gov (United States)

    Johns, Pat

    2003-01-01

    Presents an art lesson in which students learn about the artist Piet Mondrian and create their own abstract artworks. Focuses on geometric shapes using horizontal and vertical lines. Includes background information about the artist. (CMK)

  7. Notes on the horizontal cohomology

    OpenAIRE

    Verbovetsky, Alexander

    1998-01-01

    This paper is devoted to the horizontal (``characteristic'') cohomology of systems of differential equations. Recent results on computing the horizontal cohomology via the compatibility complex are generalized. New results on the Vinogradov C-spectral sequence and the Krasil'shchik C-cohomology are obtained. As an application of general theory, the examples of an evolution equation and a p-form gauge theory are explicitly worked out.

  8. Mechanisms of Horizontal Gene Transfer

    OpenAIRE

    Cafini Barrado, Fabio; Medrano Romero, Verónica; Morikawa, Kazuya

    2017-01-01

    Horizontal gene transfer plays important roles in the evolution of S. aureus, and indeed, a variety of virulence factors and antibiotic resistance genes are embedded in a series of mobile genetic elements. In this chapter, we review the mechanisms of horizontal gene transfer, including recent findings on the natural genetic competence. Then, we consider the transfer of two important antibiotic resistance genes: the methicillin resistance gene, mecA (in Staphylococcal Cassette Chromosome) and ...

  9. Endoscopic treatment for complex biliary and pancreatic duct injuries

    Directory of Open Access Journals (Sweden)

    Simon Bouchard

    2014-01-01

    Full Text Available Severe injuries of biliary or pancreatic ducts are associated with significant morbidity and mortality. Severe bile duct injuries such as major biliary leaks, complete transection, or complete occlusion of bile ducts can be grouped under the term complex bile duct injuries (CBDI. In the spectrum of pancreatic duct injuries, disconnected pancreatic duct syndrome (DPDS represents the most severe form and most often occurs after a severe episode of acute pancreatitis. Treatment of these complex injuries is quite challenging and for many years surgical management has been considered the treatment of choice. However, in the past few years, some studies have reported the successful management of CBDI or DPDS using endoscopic procedures alone or in combination with a percutaneous approach. In this review, we detail the endoscopic or combined endoscopic/percutaneous treatment possibilities for CBDI and DPDS.

  10. Flow regime analysis of non-Newtonian duct flows

    Science.gov (United States)

    Speetjens, Michel; Rudman, Murray; Metcalfe, Guy

    2006-01-01

    Reoriented duct flows of generalized Newtonian fluids are an idealization of non-Newtonian fluid flow in industrial in-line mixers. Based on scaling analysis and computation we find that non-Newtonian duct flows have several limit behaviors, in the sense that such flows can become (nearly) independent of one or more of the rheological and dynamical control parameters, simplifying the general flow and mixing problem. These limit flows give several levels of modeling complexity to the full problem of non-Newtonian duct flow. We describe the sets of simplified flow models and their corresponding regions of validity. This flow-model decomposition captures the essential rheological and dynamical characteristics of the reoriented duct flows and enables a more efficient and systematic study and design of flow and mixing of non-Newtonian fluids in ducts. Key aspects of the flow-model decomposition are demonstrated via a specific, but representative, duct flow.

  11. A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna

    Directory of Open Access Journals (Sweden)

    Biao Li

    2016-01-01

    Full Text Available A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated on FR4 substrate with dielectric constant 4.4. The proposed antenna achieves 10 dB return loss bandwidths and 3 dB axial ratio (AR in the frequency bands 2.39–2.81 GHz and 5.42–5.92 GHz, respectively. Both these characteristics are suitable for WLAN and WiMAX applications.

  12. Differential expansion and rectangular HOMFLY for the figure eight knot

    Directory of Open Access Journals (Sweden)

    A. Morozov

    2016-10-01

    Full Text Available Differential expansion (DE for a Wilson loop average in representation R is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of 3d Chern–Simons theory. Especially simple is the relation between the DE for the trefoil 31 and for the figure eight knot 41. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso–Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfill this program for all rectangular representation R=[rs], i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.

  13. Fractional Fourier transforms of electromagnetic rectangular Gaussian Schell model beams

    Science.gov (United States)

    Liu, Xiayin; Zhao, Daomu

    2015-06-01

    We extend the scalar rectangular Gaussian Schell model (RGSM) beams to the electromagnetic domain and obtain the analytical expression for the propagation of the electromagnetic RGSM (EM RGSM) beams through an ABCD optical system. As a practical application, we illustrate how the spectral density, the spectral degree of polarization and the spectral degree of coherence of the EM RGSM beams through the fractional Fourier transform (FRFT) optical system depend on the FRFT order p and the value of beam profile M. It is found that the periods of the on-axis spectral density, the on-axis degree of polarization and the transverse degree of coherence for the FRFT order are all 2. In addition, it is of interest that the profiles of the transverse spectral intensity and the degree of polarization in the standard Fourier transform plane (i.e., p=1) are shown to form flat rectangular region which is wider for larger values of M.

  14. Free vibration analysis of rectangular plates with central cutout

    Directory of Open Access Journals (Sweden)

    Kanak Kalita

    2016-12-01

    Full Text Available A nine-node isoparametric plate element in conjunction with first-order shear deformation theory is used for free vibration analysis of rectangular plates with central cutouts. Both thick and thin plate problems are solved for various aspect ratios and boundary conditions. In this article, primary focus is given to the effect of rotary inertia on natural frequencies of perforated rectangular plates. It is found that rotary inertia has significant effect on thick plates, while for thin plates the rotary inertia term can be ignored. It is seen that the numerical convergence is very rapid and based on comparison with experimental and analytical data from literature, it is proposed that the present formulation is capable of yielding highly accurate results. Finally, some new numerical solutions are provided here, which may serve as benchmark for future research on similar problems.

  15. Mode conversion in rectangular-core optical fibers.

    Science.gov (United States)

    Bullington, Amber L; Pax, Paul H; Sridharan, Arun K; Heebner, John E; Messerly, Michael J; Dawson, Jay W

    2012-01-01

    Mode conversion from the fundamental to a higher-order mode in a rectangular-core optical fiber is accomplished by applying pressure with the edge of a flat plate. Modal analysis of the near and far field images of the fiber's transmitted beam determines the purity of the converted mode. Mode conversion reaching 75% of the targeted higher-order mode is achieved using this technique. Conversion from a higher-order mode back to the fundamental mode is also demonstrated with comparable efficiency. Propagation of a higher-order mode in a rectangular-core fiber allows for better thermal management and bend-loss immunity than conventional circular-core fibers, extending the power-handling capabilities of optical fibers. © 2012 Optical Society of America

  16. Shielding calculations for changing from circular to a Rectangular ...

    African Journals Online (AJOL)

    From these calculations, the dose rates at the occupied sites ³ 5.0 m, require concrete wall shielding of thickness, t = 183.1 cm as against the 190 cm which is now in place at the RTC. This implies that the biological shi-eld in place is adequate for the replacement of the cylindrical source cage with a rectangular or plaque ...

  17. Partitioning Rectangular and Structurally Nonsymmetric Sparse Matrices for Parallel Processing

    Energy Technology Data Exchange (ETDEWEB)

    B. Hendrickson; T.G. Kolda

    1998-09-01

    A common operation in scientific computing is the multiplication of a sparse, rectangular or structurally nonsymmetric matrix and a vector. In many applications the matrix- transpose-vector product is also required. This paper addresses the efficient parallelization of these operations. We show that the problem can be expressed in terms of partitioning bipartite graphs. We then introduce several algorithms for this partitioning problem and compare their performance on a set of test matrices.

  18. Simple formula for computing the Hubbell radiation rectangular source integral

    Energy Technology Data Exchange (ETDEWEB)

    Murley, Jonathan, E-mail: Jmurley@stu1.cs.upei.c [Department of Mathematics and Statistics, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 (Canada); Saad, Nasser, E-mail: nsaad@upei.c [Department of Mathematics and Statistics, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3 (Canada)

    2011-01-15

    A simple analytic formula is derived for use in solving the Hubbell radiation rectangular source integrals H(a,b)={integral}{sub 0}{sup b}(x{sup 2}+1){sup -1/2}arctan(a(x{sup 2}+1){sup -1/2})dx,0

  19. Diffraction of electromagnetic waves by a rectangular wedge structure

    Science.gov (United States)

    Makarov, G. I.; Sozonov, A. P.

    A theoretical problem of electromagnetic wave diffraction in a system of two rectangular wedges is examined: a perfectly conducting wedge and a wedge with finite relative permittivity, the two wedges having a common face. For the Fourier component of the diffraction field, a shifting Riemann boundary value problem is obtained. This problem is reduced to a convolution-type integral equation for the semiaxis, with the kernel taking the form of the sum of the difference and regular kernels.

  20. The hydrodynamic advantages of synchronized swimming in a rectangular pattern.

    Science.gov (United States)

    Daghooghi, Mohsen; Borazjani, Iman

    2015-10-08

    Fish schooling is a remarkable biological behavior that is thought to provide hydrodynamic advantages. Theoretical models have predicted significant reduction in swimming cost due to two physical mechanisms: vortex hypothesis, which reduces the relative velocity between fish and the flow through the induced velocity of the organized vortex structure of the incoming wake; and the channeling effect, which reduces the relative velocity by enhancing the flow between the swimmers in the direction of swimming. Although experimental observations confirm hydrodynamic advantages, there is still debate regarding the two mechanisms. We provide, to our knowledge, the first three-dimensional simulations at realistic Reynolds numbers to investigate these physical mechanisms. Using large-eddy simulations of self-propelled synchronized swimmers in various rectangular patterns, we find evidence in support of the channeling effect, which enhances the flow velocity between swimmers in the direction of swimming as the lateral distance between swimmers decreases. Our simulations show that the coherent structures, in contrast to the wake of a single swimmer, break down into small, disorganized vortical structures, which have a low chance for constructive vortex interaction. Therefore, the vortex hypothesis, which is relevant for diamond patterns, was not found for rectangular patterns, but needs to be further studied for diamond patterns in the future. Exploiting the channeling mechanism, a fish in a rectangular school swims faster as the lateral distance decreases, while consuming similar amounts of energy. The fish in the rectangular school with the smallest lateral distance (0.3 fish lengths) swims 20% faster than a solitary swimmer while consuming similar amount of energy.

  1. Pancreatic duct cells as a source of VEGF in mice.

    Science.gov (United States)

    Xiao, Xiangwei; Prasadan, Krishna; Guo, Ping; El-Gohary, Yousef; Fischbach, Shane; Wiersch, John; Gaffar, Iljana; Shiota, Chiyo; Gittes, George K

    2014-05-01

    Vascular endothelial growth factor (VEGF) is essential for proper pancreatic development, islet vascularisation and insulin secretion. In the adult pancreas, VEGF is thought to be predominantly secreted by beta cells. Although human duct cells have previously been shown to secrete VEGF at angiogenic levels in culture, an analysis of the kinetics of VEGF synthesis and secretion, as well as elucidation of an in vivo role for this ductal VEGF in affecting islet function and physiology, has been lacking. We analysed purified duct cells independently prepared by flow cytometry, surgical isolation or laser-capture microdissection. We infected duct cells in vivo with Vegf (also known as Vegfa) short hairpin RNA (shRNA) in an intrapancreatic ductal infusion system and examined the effect of VEGF knockdown in duct cells in vitro and in vivo. Pancreatic duct cells express high levels of Vegf mRNA. Compared with beta cells, duct cells had a much higher ratio of secreted to intracellular VEGF. As a bioassay, formation of tubular structures by human umbilical vein endothelial cells was essentially undetectable when cultured alone and was substantially increased when co-cultured with pancreatic duct cells but significantly reduced when co-cultured with duct cells pretreated with Vegf shRNA. Compared with islets transplanted alone, improved vascularisation and function was detected in the islets co-transplanted with duct cells but not in islets co-transplanted with duct cells pretreated with Vegf shRNA. Human islet preparations for transplantation typically contain some contaminating duct cells and our findings suggest that the presence of duct cells in the islet preparation may improve transplantation outcomes.

  2. The importance of cognitive map placement in bile duct injuries.

    Science.gov (United States)

    Sutherland, Francis; Dixon, Elijah

    2017-12-01

    Bile duct injuries often occur because of surgeon spatial disorientation. The psychological concept of cognitive map misplacement is a useful explanation of how this disorientation and injury occurs. Surgeons may find that using a "bile duct time out" is a helpful way to orient. Based on the mnemonic B-SAFE, they can use 5 subhepatic landmarks (B, bile duct; S, sulcus of Rouviere; A, hepatic artery; F, umbilical fissure; E, enteric/duodenum) to correctly place their cognitive map.

  3. Squamous Cell Carcinoma of the Distal Common Bile Duct

    OpenAIRE

    Jain A; Juneja M; Naik S; Sharma S; Kapoor S; Sewkani A; Varshney S

    2005-01-01

    CONTEXT: Squamous cell carcinoma of the biliary tree is rare. Although few cases of squamous cell carcinoma of the intrahepatic bile-duct and gallbladder have been reported, until today, only four cases of squamous cell carcinoma of the extrahepatic bile duct have been reported in the literature. CASE REPORT: We present a case of squamous cell carcinoma of the distal common bile duct presenting with obstructive jaundice in a 60-year-old male which was successfully managed by a Whipple's pancr...

  4. Active noise control in a duct to cancel broadband noise

    Science.gov (United States)

    Chen, Kuan-Chun; Chang, Cheng-Yuan; Kuo, Sen M.

    2017-09-01

    The paper presents cancelling duct noises by using the active noise control (ANC) techniques. We use the single channel feed forward algorithm with feedback neutralization to realize ANC. Several kinds of ducts noises including tonal noises, sweep tonal signals, and white noise had investigated. Experimental results show that the proposed ANC system can cancel these noises in a PVC duct very well. The noise reduction of white noise can be up to 20 dB.

  5. Effective stress assessment at rectangular rounded lateral notches

    Directory of Open Access Journals (Sweden)

    Enrico Maggiolini

    2015-07-01

    Full Text Available Rectangular lateral notches are not common engineering components, thus little research attention has been directed towards the investigation of their stress field properties. Indeed, no in-depth investigations have been conducted to date to assess their effective stress distributions according to the effective stress definitions provided by more recent non-local approaches (i.e. critical distance, average values, implicit gradient values, etc.. In fact, the potential applications of this kind of investigation are not even particularly relevant. However, rectangular notches could provide an interesting theoretical and experimental benchmark or reference case in order to validate the effective stress definitions. The aim of this paper is to investigate the linear elastic stress field at edges, corners and in the surrounding material of rectangular, sharp or rounded lateral notches. The consequent effective values of these notches are evaluated in relation to brittle fracture or their predicted fatigue strength values. The main goal of this paper is to investigate the relationship between geometrical proportions and the location of critical failure points according to the definitions of effective stress proposed in the literature.

  6. Single and Multi-channel Quantum Dragons from Rectangular Nanotubes

    Science.gov (United States)

    Li, Zhou; Novotny, Mark

    2015-03-01

    Recently quantum dragons have been discovered theoretically. Quantum dragons are nanostructures with correlated disorder that permit energy-independent total quantum transmission of electrons. Hence the electrical conductance G in a two-terminal measurement should be the conductance quantum G0 = 2e2 / h . The single-band tight banding model is used. An example of a single-channel quantum dragon is a rectangular nanotube with disorder along the direction z of the electron propagation. Quantum dragons are obtained by solving the time-independent Schrödinger equation to obtain the electrical transmission calT as a function of the incoming electron energy E. A quantum dragon has calT (E) =1 for all energies. This work generalizes the solution of the time-independent Schrödinger equation to the case of more than one open channel, and applies the method to nanotubes formed from rectangular lattices. One can envision such single-walled rectangular nanotubes for iron starting from free-standing single-atom-thick Fe membranes which have recently been obtained experimentally. Supported in part by NSF Grant DMR-1206233.

  7. Double-composite rectangular truss bridge and its joint analysis

    Directory of Open Access Journals (Sweden)

    Yongjian Liu

    2015-08-01

    Full Text Available This paper describes a novel composite tubular truss bridge with concrete slab and concrete-filled rectangular chords. With concrete slab plus truss system and joints reinforced with concrete and Perfobond Leiste rib, double composite truss bridge proved to be a fairly suitable solution in negative moment area. Perfobond Leiste shear connector (PBL is widely implemented in the composite structure for its outstanding fatigue resistance. In this pilot bridge, Perfobond Leister ribs (PBR were installed in the truss girder's joints, which played double roles as shear connector and stiffener. An erection method and overall bridge structural analysis were then presented. Typical joints in the pilot bridge were selected to analyze the effect of PBR. Investigation of the effect of PBR in concrete-filled tubular joints was elaborated. Comparison has revealed that concrete-filled tubular joints with PBR have much higher constraint capability than joints without PBR. For rectangular tubular truss, the punching shear force of the concrete filled joint with PBR is approximately 43% larger than that of the joint without PBR. Fatigue performance of the joint installed with PBR was improved, which was found through analysis of the stress concentration factor of joint. The PBR installed in the joints mitigated the stress concentration factor in the chord face. Therefore, the advantages of this new type of bridge are demonstrated, including the convenience of construction using rectangular truss, innovative concept of structural design and better global and local performances.

  8. Free vibration of rectangular plates with a small initial curvature

    Science.gov (United States)

    Adeniji-Fashola, A. A.; Oyediran, A. A.

    1988-01-01

    The method of matched asymptotic expansions is used to solve the transverse free vibration of a slightly curved, thin rectangular plate. Analytical results for natural frequencies and mode shapes are presented in the limit when the dimensionless bending rigidity, epsilon, is small compared with in-plane forces. Results for different boundary conditions are obtained when the initial deflection is: (1) a polynomial in both directions, and (2) the product of a polynomial and a trigonometric function, and arbitrary. For the arbitrary initial deflection case, the Fourier series technique is used to define the initial deflection. The results obtained show that the natural frequencies of vibration of slightly curved plates are coincident with those of perfectly flat, prestressed rectangular plates. However, the eigenmodes are very different from those of initially flat prestressed rectangular plates. The total deflection is found to be the sum of the initial deflection, the deflection resulting from the solution of the flat plate problem, and the deflection resulting from the static problem.

  9. Hydrogen production from a rectangular horizontal filter press Divergent Electrode-Flow-Through (DEFT™) alkaline electrolysis stack

    Science.gov (United States)

    Gillespie, M. I.; Kriek, R. J.

    2017-12-01

    A membraneless Divergent Electrode-Flow-Through (DEFT™) alkaline electrolyser, for unlocking profitable hydrogen production by combining a simplistic, inexpensive, modular and durable design, capable of overcoming existing technology current density thresholds, is ideal for decentralised renewable hydrogen production, with the only requirement of electrolytic flow to facilitate high purity product gas separation. Scale-up of the technology was performed, representing a deviation from the original tested stack design, incorporating elongated electrodes housed in a filter press assembly. The pilot plant operating parameters were limited to a low flow velocity range (0.03 m s-1 -0.04 m s-1) with an electrode gap of 2.5 mm. Performance of this pilot plant demonstrated repeatability to results previously obtained. Mesh electrodes with geometric area of 344.32 cm2 were used for plant performance testing. A NiO anode and Ni cathode combination developed optimal performance yielding 508 mA cm-2 at 2 VDC in contrast to a Ni anode and cathode combination providing 467 mA cm-2 at 2.26 VDC at 0.04 m s-1, 30% KOH and 80 °C. An IrO2/RuO2/TiO2 anode and Pt cathode combination underwent catalyst deactivation. Owing to the nature of the gas/liquid separation system, gas qualities were inadequate compared to results achieved previously. Future improvements will provide qualities similar to results achieved before.

  10. Risk factors for central bile duct injury complicating partial liver resection

    NARCIS (Netherlands)

    Boonstra, E. A.; de Boer, M. T.; Sieders, E.; Peeters, P. M. J. G.; de Jong, K. P.; Slooff, M. J. H.; Porte, R. J.

    Background: Bile duct injury is a serious complication following liver resection. Few studies have differentiated between leakage from small peripheral bile ducts and central bile duct injury (CBDI), defined as an injury leading to leakage or stenosis of the common bile duct, common hepatic duct,

  11. CLINICAL AND MORPHOLOGICAL DIAGNOSTIC INTRAHEPATIC BILE DUCTS PAUCITY

    Directory of Open Access Journals (Sweden)

    O. E. Iryshkin

    2013-01-01

    Full Text Available Aim. To study the clinica-morphological features of syndromatic and nonsyndromatic paucity of intrahepatic bile ducts in pediatric liver transplant recipients. Methods and results. The clinical records were analyzed and histological studies of native livers of 20 children, who had suffered from paucity of intrahepatic bile ducts and to whom liver transplantation were made, were completed. The obtained data indicate higher levels of AST in patients with nonsyndromatic paucity of intrahepaticbile ducts (p = 0,023. Ductopenia was the more frequent indication of syndromatic form of paucity of intrahepatic bile ducts (p = 0,01, while ductular proliferations, which form «ductular structure», were discovered more often in nonsyndromatic paucity of intrahepaticbile ducts (p = 0,03. The extent of inflammatory-destructive changes was more expressed in nonsyndromatic pauci- ty of intrahepatic bile ducts (p = 0,01. Fibrosis or cirrhosis was formed more often in nonsyndromatic paucity of intrahepatic bile ducts (p = 0,008. Conclusion. Our results indicate more severe clinical and morphological manifestations in nonsyndromatic paucity of intrahepatic bile ducts. These findings may suggest about heavier liver condition in patient with nonsyndromatic form of paucity of intrahepatic bile ducts

  12. Duct injection technology prototype development: Evaluation of engineering data

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-01

    The objective of the Duct Injection Technology Prototype Development Project is to develop a sound design basis for applying duct injection technology as a post-combustion SO{sub 2}emissions control method to existing coal-fired power plants. The necessary engineering design and scale-up criteria will be developed for the commercialization of duct injection technology for the control of SO{sub 2} emissions from coal-fired boilers in the utility industry. The primary focus of the analyses summarized in this Topical Report is the review of the known technical and economic information associated with duct injection technology. (VC)

  13. Leaf seal for transition duct in turbine system

    Science.gov (United States)

    Flanagan, James Scott; LeBegue, Jeffrey Scott; McMahan, Kevin Weston; Dillard, Daniel Jackson; Pentecost, Ronnie Ray

    2013-06-11

    A turbine system is disclosed. In one embodiment, the turbine system includes a transition duct. The transition duct includes an inlet, an outlet, and a passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The transition duct further includes an interface member for interfacing with a turbine section. The turbine system further includes a leaf seal contacting the interface member to provide a seal between the interface member and the turbine section.

  14. Flexible metallic seal for transition duct in turbine system

    Science.gov (United States)

    Flanagan, James Scott; LeBegue, Jeffrey Scott; McMahan, Kevin Weston; Dillard, Daniel Jackson; Pentecost, Ronnie Ray

    2014-04-22

    A turbine system is disclosed. In one embodiment, the turbine system includes a transition duct. The transition duct includes an inlet, an outlet, and a passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The transition duct further includes an interface member for interfacing with a turbine section. The turbine system further includes a flexible metallic seal contacting the interface member to provide a seal between the interface member and the turbine section.

  15. Convolution seal for transition duct in turbine system

    Science.gov (United States)

    Flanagan, James Scott; LeBegue, Jeffrey Scott; McMahan, Kevin Weston; Dillard, Daniel Jackson; Pentecost, Ronnie Ray

    2015-03-10

    A turbine system is disclosed. In one embodiment, the turbine system includes a transition duct. The transition duct includes an inlet, an outlet, and a passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The transition duct further includes an interface member for interfacing with a turbine section. The turbine system further includes a convolution seal contacting the interface member to provide a seal between the interface member and the turbine section.

  16. An analysis on Free Convection Cooling of a 3×3 Heater Array in Rectangular Enclosure using Cu-EG-Water Nanofluid

    OpenAIRE

    Abimanyu Purusothaman; Venkatachalam Divya; Nagarajan Nithyadevi; ÖZTOP, H. F.

    2016-01-01

    This paper deals with the study of natural convection cooling of a discrete heater array in Cu-EG-water nanofluid filled rectangular enclosure. A 3 × 3 array of non-protruding heat sources is embedded on one of the vertical walls of the enclosure while the top horizontal and opposite vertical walls are assumed to be isothermally cold. The remaining portions in which the heaters are mounted and all other walls are insulated. The above setup is modeled into a system of partial differential equa...

  17. Salivary duct carcinoma of accessory parotid

    OpenAIRE

    Al-Hashim, Mohammed A.; Al-Jazan, Nasser A.

    2017-01-01

    Accessory parotid gland (APG) is seen in around 21%?56% of individuals. Tumors of accessory parotid are uncommon with an incidence rate of 1%?8% of all parotid tumors. Ductal carcinoma of APG is rare, so no reported incidence was seen in the literature. However, salivary gland ductal carcinoma is reported to be 1% of all salivary gland neoplasms. We report here a case of salivary duct carcinoma of APG. Clinical presentation, investigation, and management are discussed. A 69-year-old female pr...

  18. Effectiveness of duct sealing and duct insulation in multi-family buildings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Karins, N.H.; Tuluca, A.; Modera, M.

    1997-07-01

    This research investigated the cost-effectiveness of sealing and insulating the accessible portions of duct systems exposed to unconditioned areas in multifamily housing. Airflow and temperature measurements were performed in 25 apartments served by 10 systems a 9 multi-family properties. The measurements were performed before and after each retrofit, and included apartment airflow (supply and return), duct system temperatures, system fan flow and duct leakage area. The costs for each retrofit were recorded. The data were analyzed and used to develop a prototypical multifamily house. This prototype was used in energy simulations (DOE-2.1E) and air infiltration simulations (COMIS 2.1). The simulations were performed for two climates: New York City and Albany. In each climate, one simulation was performed assuming the basement was tight, and another assuming the basement was leaky. Simulation results and average retrofit costs were used to calculate cost-effectiveness. The results of the analysis indicate that sealing leaks of the accessible ductwork is cost-effective under all conditions simulated (simple payback was between 3 and 4 years). Insulating the accessible ductwork, however, is only cost-effective for buildings with leaky basement, in both climates (simple paybacks were less than 5 years). The simple payback period for insulating the ducts in buildings with tight basements was greater than 10 years, the threshold of cost-effectiveness for this research. 13 refs., 5 figs., 27 tabs.

  19. Theoretical investigation of biomass productivities achievable in solar rectangular photobioreactors for the cyanobacterium Arthrospira platensis.

    Science.gov (United States)

    Pruvost, Jeremy; Cornet, J F; Goetz, Vincent; Legrand, Jack

    2012-01-01

    Modeling was done to simulate whole-year running of solar rectangular photobioreactors (PBRs). Introducing the concept of ideal reactor, the maximal biomass productivity that could be achieved on Earth on nitrate as N-source was calculated. Two additional factors were also analyzed with respect to dynamic calculations over the whole year: the effect of PBR location and the effects of given operating conditions on the resulting decrease in productivity compared with the ideal one. Simulations were conducted for the cyanobacterium Arthospira platensis, giving an ideal productivity (upper limit) in the range 55-60 tX ha(-1) year(-1) for a sun tracking system (and around 35-40 tX ha(-1) year(-1) for a fixed horizontal PBR). For an implantation in France (Nantes, west coast), the modification in irradiation conditions resulted in a decrease in biomass productivity of 40%. Various parameters were investigated, with special emphasis on the influence of the incident angle of solar illumination on resulting productivities, affecting both light capture and light transfer inside the bulk culture. It was also found that with appropriate optimization of the residence time as permitted by the model, productivities close to maximal could be achieved for a given location. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  20. Feasibility of Rectangular Concrete Pressure Vessels for Human Occupancy

    Science.gov (United States)

    1990-07-01

    fatigue cracks. Concrete fatigae does not occur in prestressed sections. Failure occurs in tendons after overload has caused massive concrete cracking...alternative, but intermittent drying of the concrete cannot be permitted. Records of cure times and temperatures should be maintained. Visual ...inspection is about the only reliable NDE method available. The inspector visually checks placement of forms, tendon ducts and rebar. The reinforcing should

  1. DRILL BITS FOR HORIZONTAL WELLS

    Directory of Open Access Journals (Sweden)

    Paolo Macini

    1996-12-01

    Full Text Available This paper underlines the importance of the correct drill bit application in horizontal wells. Afler the analysis of the peculiarities of horizontal wells and drainholes drilling techniques, advantages and disadvantages of the application of both roller cone and fixed cutters drill bits have been discussed. Also, a review of the potential specific featuries useful for a correct drill bit selection in horizontal small diameter holes has been highlighted. Drill bits for these special applications, whose importance is quickly increasing nowadays, should be characterised by a design capable to deliver a good penetration rate low WOB, and, at the same time, be able to withstand high RPM without premature cutting structure failure and undergauge. Formation properties will also determine the cutting structure type and the eventual specific features for additional gauge and shoulder protection.

  2. Nuclear component horizontal seismic restraint

    Science.gov (United States)

    Snyder, Glenn J.

    1988-01-01

    A nuclear component horizontal seismic restraint. Small gaps limit horizontal displacement of components during a seismic occurrence and therefore reduce dynamic loadings on the free lower end. The reactor vessel and reactor guard vessel use thicker section roll-forged rings welded between the vessel straight shell sections and the bottom hemispherical head sections. The inside of the reactor guard vessel ring forging contains local vertical dovetail slots and upper ledge pockets to mount and retain field fitted and installed blocks. As an option, the horizontal displacement of the reactor vessel core support cone can be limited by including shop fitted/installed local blocks in opposing alignment with the reactor vessel forged ring. Beams embedded in the wall of the reactor building protrude into apertures in the thermal insulation shell adjacent the reactor guard vessel ring and have motion limit blocks attached thereto to provide to a predetermined clearance between the blocks and reactor guard vessel ring.

  3. Nurses’ Perceptions of Horizontal Violence

    Directory of Open Access Journals (Sweden)

    Rosemary Taylor

    2016-04-01

    Full Text Available In this article, I describe a study exploring horizontal violence and nurses’ perceptions of the phenomenon within the context of two 28-bed inpatient hospital units. The purpose of the study was to develop a clearer understanding of horizontal violence, incorporating observation and inquiry to identify the language nurses use to describe their experiences and factors in the nursing work environment that may perpetuate the phenomenon. Observation, review and analysis of policies, and interviews with staff were completed between June and November 2012. Thematic analysis resulted in five themes: (a behaviors are minimized and not recognized, (b fear inhibits all reporting, (c avoidance and isolation are coping strategies, (d lack of respect and support, and (e organizational chaos. The findings suggest future interventions must address a range of factors that perpetuate horizontal violence within the nursing work environment with consideration for the embeddedness and complexity of the phenomenon.

  4. Classification and management of bile duct injuries.

    Science.gov (United States)

    Mercado, Miguel Angel; Domínguez, Ismael

    2011-04-27

    To review the classification and general guidelines for treatment of bile duct injury patients and their long term results. In a 20-year period, 510 complex circumferential injuries have been referred to our team for repair at the Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" hospital in Mexico City and 198 elsewhere (private practice). The records at the third level Academic University Hospital were analyzed and divided into three periods of time: GI-1990-99 (33 cases), GII- 2000-2004 (139 cases) and GIII- 2004-2008 (140 cases). All patients were treated with a Roux en Y hepatojejunostomy. A decrease in using transanastomotic stents was observed (78% vs 2%, P = 0.0001). Partial segment IV and V resection was more frequently carried out (45% vs 75%, P = 0.2) (to obtain a high bilioenteric anastomosis). Operative mortality (3% vs 0.7%, P = 0.09), postoperative cholangitis (54% vs 13%, P = 0.0001), anastomosis strictures (30% vs 5%, P = 0.0001), short and long term complications and need for reoperation (surgical or radiological) (45% vs 11%, P = 0.0001) were significantly less in the last period. The authors concluded that transition to a high volume center has improved long term results for bile duct injury repair. Even interested and tertiary care centers have a learning curve.

  5. Speckle Imaging Over Horizontal Paths

    Energy Technology Data Exchange (ETDEWEB)

    Carrano, C J

    2002-05-21

    Atmospheric aberrations reduce the resolution and contrast in surveillance images recorded over horizontal or slant paths. This paper describes our recent horizontal and slant path imaging experiments of extended scenes as well as the results obtained using speckle imaging. The experiments were performed with an 8-inch diameter telescope placed on either a rooftop or hillside and cover ranges of interest from 0.5 km up to 10 km. The scenery includes resolution targets, people, vehicles, and other structures. The improvement in image quality using speckle imaging is dramatic in many cases, and depends significantly upon the atmospheric conditions. We quantify resolution improvement through modulation transfer function measurement comparisons.

  6. Surgical management of Stenson's duct injury using epidural catheter

    African Journals Online (AJOL)

    2012-07-05

    Jul 5, 2012 ... ... drains saliva into the oral cavity. Deep penetrating wound in the form of cut or crush injury to the buccal area carries the risk of parotid duct injury. It is in the form of ductal exposure, laceration, total severing, or crushing of the duct. These conditions are difficult to diagnose because of complex anatomy.

  7. Chloride and potassium conductances of cultured human sweat ducts

    DEFF Research Database (Denmark)

    Novak, I; Pedersen, P S; Larsen, Erik Hviid

    1992-01-01

    The purpose of this study was to characterize the ion conductances, in particular those for Cl- and K+, of human sweat duct cells grown in primary culture. Sweat duct cells from healthy individuals were grown to confluence on a dialysis membrane, which was then mounted in a mini-Ussing chamber...

  8. Bidirectional infrasonic ducts associated with sudden stratospheric warming events

    NARCIS (Netherlands)

    Assink, J.D.; Waxler, R.; Smets, P.S.M.; Evers, L.G.

    2014-01-01

    In January 2011, the state of the polar vortex in the midlatitudes changed significantly due to a minor sudden stratospheric warming event. As a result, a bidirectional duct for infrasound propagation developed in the middle atmosphere that persisted for 2 weeks. The ducts were due to two zonal wind

  9. Cystic duct closure by sealing with bipolar electrocoagulation

    DEFF Research Database (Denmark)

    Schulze, S; Damgaard, B; Jørgensen, Lars Nannestad

    2010-01-01

    BACKGROUND: Cystic duct leakage after cholecystectomy is not uncommon and is a potentially serious complication. The aim of this study was to assess a bipolar sealing system (LigaSure) for closure of the cystic duct. METHODS: The records from consecutive laparoscopic cholecystectomies performed...

  10. Morphological study of pancreatic duct in red jungle fowl | Kadhim ...

    African Journals Online (AJOL)

    Neither goblet cells nor ductal glands were found in the pancreatic ducts. Secretion of both neutral and sulfated materials by the epithelial lining the pancreatic ducts, suggesting that they are acting not only to facilitate the transport of the pancreatic juice, but also as a protective barrier to protect the gland from autodigestion.

  11. Associated patent urachus and patent omphalo– mesenteric duct in ...

    African Journals Online (AJOL)

    The association of patent urachus and a patent omphalo–mesenteric duct in children is very rare. A computer-assisted (PubMed and Google Scholar) search of the pediatric literature to identify all cases of patent urachus and a patent omphalo–mesenteric duct association was performed. We found only eleven cases of the ...

  12. Long duct nacelle aerodynamic development for DC-10 derivatives

    Science.gov (United States)

    Patel, S. P.; Donelson, J. E.

    1980-01-01

    The results are presented of a wind tunnel test utilizing a 4.7-percent-scale semispan model of the DC-10 in the Calspan 8-foot transonic wind tunnel. The effect of a revised long-duct nacelle shape on the channel velocities, the incremental drag relative to the baseline long-duct nacelle, and channel velocities for the baseline long-duct nacelle were determined and compared with data obtained at Ames. The baseline and the revised long-duct nacelles are representative of a CF6-50 mixed-flow configuration and were evaluated on a model of a proposed DC-10 stretched-fuselage configuration. The results showed that the revised long-duct nacelle has an appreciable effect on the inboard channel velocities, resulting in an increased channel Mach number. However, the pressure recovery on the nacelle afterbody was about the same for both nacelles. The lift curves for both long-duct nacelle configurations were the same. The channel pressures measured at Calspan were in good agreement with those measured at Ames for the baseline long-duct nacelle. The incremental drag for the revised nacelle was measured as two to four counts (three counts is approximately equal to one percent of the airplane drag) higher than that of the baseline long-duct nacelle.

  13. Sound waves in two-dimensional ducts with sinusoidal walls

    Science.gov (United States)

    Nayfeh, A. H.

    1974-01-01

    The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.

  14. Morphological study of pancreatic duct in red jungle fowl

    African Journals Online (AJOL)

    Jane

    2010-10-18

    Oct 18, 2010 ... Morphological and histochemical study of the pancreas and pancreatic ducts of ten adult red jungle fowl (Gallus gallus spadiceus) were carried out by means of light microscopy. The bulk of the pancreas consists of a dorsal, ventral, third and small splenic lobe. Three pancreatic ducts were recognized as.

  15. ATP release, generation and hydrolysis in exocrine pancreatic duct cells

    DEFF Research Database (Denmark)

    Kowal, Justyna Magdalena; Yegutkin, G.G.; Novak, Ivana

    2015-01-01

    Extracellular adenosine triphosphate (ATP) regulates pancreatic duct function via P2Y and P2X receptors. It is well known that ATP is released from upstream pancreatic acinar cells. The ATP homeostasis in pancreatic ducts, which secrete bicarbonate-rich fluid, has not yet been examined. First, ou...

  16. Intracellular pH in rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I; Hug, M; Greger, R

    1997-01-01

    In order to study the mechanism of H+ and HCO3- transport in a HCO3- secreting epithelium, pancreatic ducts, we have measured the intracellular pH (pHi) in this tissue using the pH sensitive probe BCECF. We found that exposures of ducts to solutions containing acetate/acetic acid or NH4+/NH3 buff...

  17. Duct thermal performance models for large commercial buildings

    Energy Technology Data Exchange (ETDEWEB)

    Wray, Craig P.

    2003-10-01

    Despite the potential for significant energy savings by reducing duct leakage or other thermal losses from duct systems in large commercial buildings, California Title 24 has no provisions to credit energy-efficient duct systems in these buildings. A substantial reason is the lack of readily available simulation tools to demonstrate the energy-saving benefits associated with efficient duct systems in large commercial buildings. The overall goal of the Efficient Distribution Systems (EDS) project within the PIER High Performance Commercial Building Systems Program is to bridge the gaps in current duct thermal performance modeling capabilities, and to expand our understanding of duct thermal performance in California large commercial buildings. As steps toward this goal, our strategy in the EDS project involves two parts: (1) developing a whole-building energy simulation approach for analyzing duct thermal performance in large commercial buildings, and (2) using the tool to identify the energy impacts of duct leakage in California large commercial buildings, in support of future recommendations to address duct performance in the Title 24 Energy Efficiency Standards for Nonresidential Buildings. The specific technical objectives for the EDS project were to: (1) Identify a near-term whole-building energy simulation approach that can be used in the impacts analysis task of this project (see Objective 3), with little or no modification. A secondary objective is to recommend how to proceed with long-term development of an improved compliance tool for Title 24 that addresses duct thermal performance. (2) Develop an Alternative Calculation Method (ACM) change proposal to include a new metric for thermal distribution system efficiency in the reporting requirements for the 2005 Title 24 Standards. The metric will facilitate future comparisons of different system types using a common ''yardstick''. (3) Using the selected near-term simulation approach

  18. The anatomy of fluid-yielding ducts in breast cancer.

    Science.gov (United States)

    Twelves, Dominique; Nerurkar, Ashutosh; Osin, Peter; Ward, Ann; Isacke, Clare M; Gui, Gerald P H

    2012-04-01

    The concept of an intraductal approach to evaluate the breast microenvironment assumes direct access to the cancer-containing duct. Central duct access to the cancer-affected lobe is essential if cytology or cell markers are to be useful indicators of pre-malignant change. Access to the cancer-bearing lobe would be less important if field change effects of malignant change were predominantly supra-lobar. The aim of this study was to determine how often duct lavage fluid drains the breast cancer-affected segment. 58 patients undergoing mastectomy for breast cancer were recruited among which 47 had at least one fluid-yielding duct. Following duct lavage, fluid-yielding ducts were perfused ex vivo with Polyurethane Elastomer (PU4ii) resin. Specimens were sliced sagittally, and the extent of resin perfusion and anatomical relationship to the cancer-affected segment was recorded. Computed tomography (CT) scanning was performed on selected mastectomies before cut-up for a feasibility study of 3D duct reconstruction. The median number of fluid-yielding ducts cannulated per cancer-affected breast was 2 (range 1-4). 35/47 (74%) mastectomy specimens were successfully cannulated for resin perfusion. 29/35 (83%) showed tracing of the cancer-affected duct system, 6/35 resin perfusions traced duct systems unaffected by cancer and 12/35 perfusions extravasated. The proportion of sagittal breast slices perfused by resin was 13-68% (median 43%). Volume rendering CT showed it is feasible to produce a simulated image of the perfused ducts. Duct access to the cancer-containing segment is feasible in the majority of patients. Fluid-yielding ducts proportionately drain a significant volume of the breast. Large symptomatic cancers may cause obstruction with distal collapse. Further quantitative study of breast perfusion CT scans may be helpful for estimating the volume fraction of breast tissue perfused by fluid-yielding ducts. The intraductal approach is a valid concept for biomarker

  19. Topological mixing study of non-Newtonian duct flows

    Science.gov (United States)

    Speetjens, Michel; Metcalfe, Guy; Rudman, Murray

    2006-10-01

    Tracer advection of non-Newtonian fluids in reoriented duct flows is investigated in terms of coherent structures in the web of tracer paths that determine transport properties geometrically. Reoriented duct flows are an idealization of in-line mixers, encompassing many micro and industrial continuous mixers. The topology of the tracer dynamics of reoriented duct flows is Hamiltonian. As the stretching per reorientation increases from zero, we show that the qualitative route from the integrable state to global chaos and good mixing does not depend on fluid rheology. This is due to a universal symmetry of reoriented duct flows, which we derive, controlling the topology of the tracer web. Symmetry determines where in parameter space global chaos first occurs, while increasing non-Newtonian effects delays the quantitative value of onset. Theory is demonstrated computationally for a representative duct flow, the rotated arc mixing flow.

  20. Cystic duct remnant mucocele in a liver transplant recipient

    Energy Technology Data Exchange (ETDEWEB)

    Ahlawat, Sushil K. [Georgetown University Hospital, Department of Medicine, Division of Gastroenterology, Washington, DC (United States); University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ (United States); Fishbien, Thomas M. [Georgetown University Hospital, Department of Medicine, Division of Gastroenterology, Washington, DC (United States); Haddad, Nadim G. [Georgetown University Hospital, Department of Surgery, Division of Transplant Surgery, Washington, DC (United States)

    2008-08-15

    Cystic duct remnant mucocele is an extremely rare complication of liver transplantation in children. Surgical correction is usually required for cystic duct remnant mucocele when it causes biliary obstruction. We describe a 14-month-old liver transplant recipient who presented with biliary obstruction 1 month after orthotopic liver transplantation with an end-to-end choledochocholedocal biliary anastomosis for hepatoblastoma. US, CT and cholangiography findings were consistent with mucocele of the allograft cystic duct remnant. Surgery was not needed in our patient because the mucocele and biliary obstruction had resolved on repeat imaging most likely due to guidewire manipulation during cholangiography, resulting in opening of the cystic duct remnant orifice and drainage into the common duct. (orig.)

  1. Radiological spectrum of intraductal papillary tumors of the bile ducts

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jae Hoon; Yi, Chin A; Lim, Hyo Keun; Lee, Won Jae; Lee, Soon Jin; Kim, Seung Hoon [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2002-01-01

    Papillary tumor of the bile duct is characterized by the presence of an intraductal tumor with a papillary surface comprising innumerable frondlike infoldings of proliferated columnar epithelial cells surrounding slender fibrovascular stalks. There may be multiple tumors along the bile ducts (papillomatosis or papillary carcinomatosis), which are dilated due to obstruction by a tumor per se, by sloughed tumor debris, or by excessive mucin. Radiologically, the biliary tree is diffusely dilated, either in a lobar or segmental fashion, or aneurysmally, depending on the location of the tumor, the debris, and the amount of mucin production. A tumor can be depicted by imaging as an intraductal mass with a thickened and irregular bile duct wall. Sloughed tumor debris and mucin plugs should be differentiated from bile duct stones. Cystically or aneurysmally, dilated bile ducts in mucin-hypersecreting variants (intraductal papillary mucinous tumors) should be differentiated from cystadenoma, cystadenocarcinoma and liver abscess.

  2. Simulation of collagen solution flow in rectangular capillary

    Science.gov (United States)

    Kysela, Bohus; Skocilas, Jan; Zitny, Rudolf; Stancl, Jaromir; Houska, Milan; Landfeld, Ales

    The viscoelastic properties of foods and polymers can be evaluated from flow of the material in capillary with specified dimension and shape. The extrusion rheometer equipped by capillary with rectangular cross-section was used for determination of the rheological behaviour of water collagen solution. The measurements of the axial profiles in longitudinal direction of the total stresses at capillary wall were performed for various shear rates. The linear viscoelastic model of Oldroyd B type: White-Metzner model was used for simulation of fluid flow in OpenFOAM software package. The simulations describe the effect of relaxation time on wall total stress in convergent-divergent capillary.

  3. Single-crystalline vanadium dioxide nanowires with rectangular cross sections.

    Science.gov (United States)

    Guiton, Beth S; Gu, Qian; Prieto, Amy L; Gudiksen, Mark S; Park, Hongkun

    2005-01-19

    We report the synthesis of single-crystalline VO2 nanowires with rectangular cross sections using a vapor transport method. These nanowires have typical diameters of 60 (+/-30) nm and lengths up to >10 mum. Electron microscopy and diffraction measurements show that the VO2 nanowires are single crystalline and exhibit a monoclinic structure. Moreover, they preferentially grow along the [100] direction and are bounded by the (01) and (011) facets. These VO2 nanowires should provide promising materials for fundamental investigations of nanoscale metal-insulator transitions.

  4. Acoustic-Gravity Waves Interacting with a Rectangular Trench

    Directory of Open Access Journals (Sweden)

    Usama Kadri

    2015-01-01

    Full Text Available A mathematical solution of the two-dimensional linear problem of an acoustic-gravity wave interacting with a rectangular trench, in a compressible ocean, is presented. Expressions for the flow field on both sides of the trench are derived. The dynamic bottom pressure produced by the acoustic-gravity waves on both sides of the trench is measurable, though on the transmission side it decreases with the trench depth. A successful recording of the bottom pressures could assist in the early detection of tsunami.

  5. The demagnetizing field of a non-uniform rectangular prism

    DEFF Research Database (Denmark)

    Smith, Anders; Nielsen, Kaspar Kirstein; Christensen, Dennis

    2010-01-01

    The effect of demagnetization on the magnetic properties of a rectangular ferromagnetic prism under non-uniform conditions is investigated. A numerical model for solving the spatially varying internal magnetic field is developed, validated and applied to relevant cases. The demagnetizing field...... is solved by an analytical calculation and the coupling between applied field, the demagnetization tensor field and spatially varying temperature is solved through iteration. We show that the demagnetizing field is of great importance in many cases and that it is necessary to take into account the non...

  6. A New Fuzzy System Based on Rectangular Pyramid

    Science.gov (United States)

    Jiang, Mingzuo; Yuan, Xuehai; Li, Hongxing; Wang, Jiaxia

    2015-01-01

    A new fuzzy system is proposed in this paper. The novelty of the proposed system is mainly in the compound of the antecedents, which is based on the proposed rectangular pyramid membership function instead of t-norm. It is proved that the system is capable of approximating any continuous function of two variables to arbitrary degree on a compact domain. Moreover, this paper provides one sufficient condition of approximating function so that the new fuzzy system can approximate any continuous function of two variables with bounded partial derivatives. Finally, simulation examples are given to show how the proposed fuzzy system can be effectively used for function approximation. PMID:25874253

  7. Stability of rectangular concrete-filled steel tubes

    Directory of Open Access Journals (Sweden)

    Kanishchev Ruslan

    2017-01-01

    Full Text Available The paper deals with the theoretical analysis of the influence of imperfections on the stability and carrying capacity of axially compressed cold-formed rectangular steel tubes filled with concrete, which use as bearing structures in the structural engineering, bridges, underground subway systems and tunnels. The behavior of the mentioned above composite structures under load were presented by numerical modelling in software ABAQUS. The support conditions of loaded edges of the steel section were considered as clamped in the models. The results of the analysis were shown the influence of imperfections on the stability and carrying capacity of the composite columns.

  8. A Plug-and-Play Duct System Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Beach, Robert [IBACOS, Inc., Pittsburgh, PA (United States); Dickson, Bruce [IBACOS, Inc., Pittsburgh, PA (United States); Grisolia, Anthony [IBACOS, Inc., Pittsburgh, PA (United States); Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States); Rapport, Ari [IBACOS, Inc., Pittsburgh, PA (United States)

    2017-07-10

    This report describes an air distribution system composed of a series of uniformly-sized ducts that terminate in rooms throughout the home and return to a central manifold, similar in fashion to a “home-run” cross-linked polyethylene plumbing system. With a well-designed manifold, each duct receives an equal static pressure potential for airflow from the air handling unit, and the number of needed ducts for each room are simply attached to fittings located on the manifold; in this sense, the system is plug-and-play (PnP). As indicated, all ducts in the PnP system are identical in size and small enough to fit in the ceiling and wall cavities of a house (i.e., less than 3.5-in. outer diameter). These ducts are also more appropriately sized for the lower airflow requirements of modern, energy-efficient homes; therefore, the velocity of the air moving through the duct is between that of conventional duct systems (approximately 700 ft/min) and high-velocity systems (more than 1,500 ft/min) on the market today. The PnP duct system uses semi-rigid plastic pipes, which have a smooth inner wall and are straightforward to install correctly, resulting in a system that has minimal air leakage. However, plastic ducts are currently not accepted by code for use in residential buildings; therefore, the project team considered other duct materials for the system that are currently accepted by code, such as small-diameter, wirehelix, flexible ductwork.

  9. A Plug-and-Play Duct System Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R. [IBACOS, Inc., Pittsburgh, PA (United States); Dickson, B. [IBACOS, Inc., Pittsburgh, PA (United States); Grisolia, A. [IBACOS, Inc., Pittsburgh, PA (United States); Poerschke, A. [IBACOS, Inc., Pittsburgh, PA (United States); Rapport, A. [IBACOS, Inc., Pittsburgh, PA (United States)

    2017-07-01

    This report describes an air distribution system composed of a series of uniformly-sized ducts that terminate in rooms throughout the home and return to a central manifold, similar in fashion to a “home-run” cross-linked polyethylene plumbing system. With a well-designed manifold, each duct receives an equal static pressure potential for airflow from the air handling unit, and the number of needed ducts for each room are simply attached to fittings located on the manifold; in this sense, the system is plug-and-play (PnP). As indicated, all ducts in the PnP system are identical in size and small enough to fit in the ceiling and wall cavities of a house (i.e., less than 3.5-in. outer diameter). These ducts are also more appropriately sized for the lower airflow requirements of modern, energy-efficient homes; therefore, the velocity of the air moving through the duct is between that of conventional duct systems (approximately 700 ft/min) and high-velocity systems (more than 1,500 ft/min) on the market today. The PnP duct system uses semi-rigid plastic pipes, which have a smooth inner wall and are straightforward to install correctly, resulting in a system that has minimal air leakage. However, plastic ducts are currently not accepted by code for use in residential buildings; therefore, the project team considered other duct materials for the system that are currently accepted by code, such as small-diameter, wirehelix, flexible ductwork.

  10. Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

    Directory of Open Access Journals (Sweden)

    Li Yuan

    2013-09-01

    Full Text Available The coupling effects in bilayer thick metal (silver films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique. Many interesting light phenomena are observed as the distance between the metal rectangular nanohole arrays varies. Coupling effects are found to play very important roles on the optical and electronic properties of bilayer metal rectangular nanohole arrays: antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole, are probably excited in each layer of bilayer metal rectangular nanohole arrays; antisymmetric and symmetric magnetic coupling probably occur between the metal rectangular nanohole arrays.

  11. Effect of ursodeoxycholic acid administration on bile duct proliferation and cholestasis in bile duct ligated rat.

    Science.gov (United States)

    Frezza, E E; Gerunda, G E; Plebani, M; Galligioni, A; Giacomini, A; Neri, D; Faccioli, A M; Tiribelli, C

    1993-07-01

    The origin, mechanism, and significance of the bile duct proliferation (BDP) associated with cholestasis remain unexplained. This study examined the effect of oral administration of ursodeoxycholic acid (UDCA) on both BDP and cholestasis in the rat. After bile duct ligation, male Sprague-Dawley rats were treated for 30 days with either UDCA (5 mg/day) (group A) or saline solution (group B). Animals were sacrificed at day 30. The serum activity of aminotransferase (ALT, AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT) was significantly lower (P acids were lower (P animals (33 +/- 11 vs 64 +/- 22 per 1000 cells; P acid and lithocolate and increase periductular bile acid recirculation.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Effect of geometric nonlinearity on the free flexural vibrations of moderately thick rectangular plates

    Science.gov (United States)

    Raju, K. K.; Rao, G. V.; Raju, I. S.

    1978-01-01

    The effect of geometric nonlinearity on the free flexural vibrations of moderately thick rectangular plates is studied in this paper. Finite element formulation is employed to obtain the non-linear to linear period ratios for some rectangular plates. A conforming finite element of rectangular shape wherein the effects of shear deformation and rotatory inertia are included, is developed and used for the analysis. Results are presented for both simply supported and clamped boundary conditions.

  13. Resolution comparison between integral-imaging-based hologram synthesis methods using rectangular and hexagonal lens arrays.

    Science.gov (United States)

    Chen, Ni; Yeom, Jiwoon; Jung, Jae-Hyun; Park, Jae-Hyeung; Lee, Byoungho

    2011-12-19

    We compare the resolution of the hologram reconstruction synthesis methods based on integral imaging using rectangular and hexagonal lens arrays. By using a hexagonal lens array instead of conventional rectangular lens array, the three-dimensional objects are sampled with hexagonal grids. Due to more efficient sampling of the hexagonal grid, the resolution of the reconstructed object is higher compared with the case of using rectangular lens array. We analyze the resolution enhancement of the hologram reconstruction quantitatively and verify it experimentally.

  14. Granular Cell Tumour of the Bile Duct in Association with Intrahepatic Bile Duct Adenomas

    OpenAIRE

    Schweiger, F; Radhi, J; Coop, FW; Murphy, RW

    1994-01-01

    Granular cell tumour of the extrahepatic biliary tract is a rare benign lesion likely of neurogenic origin. Review of the previously reported cases indicates that almost all patients are female, and the majority is Black. Symptoms usually are those of biliary obstruction or cholecystitis. Surgical resection of the tumour is curative. Intrahepatic bile duct adenoma is another rare benign biliary neoplasm that does not manifest clinically but can be confused with metastatic carcinoma, cholangio...

  15. Transcatheter stenting of arterial duct in duct-dependent congenital heart disease

    Directory of Open Access Journals (Sweden)

    Đukić Milan

    2013-01-01

    Full Text Available Introduction. Critical congenital heart diseases (CHD are mostly duct-dependent and require stable systemic-pulmonary communication. In order to maintain patency of the ductus arteriosus (DA, the first line treatment is Prostaglandin E1 and the second step is the surgical creation of aortic-pulmonary shunt. To reduce surgical risk in neonates with the critical CHD, transcatheter stenting of DA can be performed in selected cases. Case Outline. A four-month old infant was diagnosed with the pulmonary artery atresia with ventricular septal defect (PAA/VSD. The left pulmonary artery was perfused from DA, and the right lung through three major aortopulmonary collaterals (MAPCAs. A coronary stent was placed in the long and critically stenotic DA, with final arterial duct diameter of 3.5 mm, and significantly increased blood supply to the left lung. After the procedure, the infant’s status was improved with regard to arterial oxygen saturation, feeding and weight gain. During the follow-up, one year later, aortography revealed in-stent stenosis. The left pulmonary artery, as well as the branches, was well-developed and the decision was made to proceed with further surgical correction. Conclusion. Stenting of DA can be an effective alternative to primary surgical correction in selected patients with duct-dependent CHD.

  16. Transcatheter stenting of arterial duct in duct-dependent congenital heart disease.

    Science.gov (United States)

    Djukić, Milan; Ilisić, Tamara; Stefanović, Igor; Gradinac, Marija; Vulićević, Irena; Parezanović, Vojislav; Jovanović, Ida

    2013-01-01

    Critical congenital heart diseases (CHD) are mostly duct-dependent and require stable systemic-pulmonary communication. In order to maintain patency of the ductus arteriosus (DA), the first line treatment is Prostaglandin E1 and the second step is the surgical creation of aortic-pulmonary shunt. To reduce surgical risk in neonates with the critical CHD, transcatheter stenting of DA can be performed in selected cases. A four-month old infant was diagnosed with the pulmonary artery atresia with ventricular septal defect (PAA/VSD). The left pulmonary artery was perfused from DA, and the right lung through three major aortopulmonary collaterals (MAPCAs). A coronary stent was placed in the long and critically stenotic DA, with final arterial duct diameter of 3.5 mm, and significantly increased blood supply to the left lung. After the procedure, the infant's status was improved with regard to arterial oxygen saturation, feeding and weight gain. During the follow-up, one year later, aortography revealed in-stent stenosis. The left pulmonary artery, as well as the branches, was well-developed and the decision was made to proceed with further surgical correction. Stenting of DA can be an effective alternative to primary surgical correction in selected patients with duct-dependent CHD.

  17. Analysis and modeling of ducted and evanescent gravity waves observed in the Hawaiian airglow

    Directory of Open Access Journals (Sweden)

    D. B. Simkhada

    2009-08-01

    Full Text Available Short-period gravity waves of especially-small horizontal scale have been observed in the Maui, Hawaii airglow. Typical small-scale gravity wave events have been investigated, and intrinsic wave propagation characteristics have been calculated from simultaneous meteor radar wind measurements. Here we report specific cases where wave structure is significantly determined by the local wind structure, and where wave characteristics are consistent with ducted or evanescent waves throughout the mesopause region. Two of the documented events, exhibiting similar airglow signatures but dramatically different propagation conditions, are selected for simple numerical modeling case studies. First, a Doppler-ducted wave trapped within relatively weak wind flow is examined. Model results confirm that the wave is propagating in the 85–95 km region, trapped weakly by evanescence above and below. Second, an evanescent wave in strong wind flow is examined. Model results suggest an opposite case from the first case study, where the wave is instead trapped above or below the mesopause region, with strong evanescence arising in the 85–95 km airglow region. Distinct differences between the characteristics of these visibly-similar wave events demonstrate the need for simultaneous observations of mesopause winds to properly assess local propagation conditions.

  18. Some Considerations on Horizontal Displacement and Horizontal Displacement Coefficient B

    Directory of Open Access Journals (Sweden)

    Tajduś Krzysztof

    2015-12-01

    Full Text Available Mining-induced deformations of the ground surface and within the rock mass may pose danger not only for surface constructions but also for underground objects (e.g., tunnels, underground storages, garages, diverse types of pipelines, electric cables, etc. For a proper evaluation of hazard for surface and underground objects, such parameters as horizontal displacement and horizontal deformations, especially their maximum values, are of crucial importance. The paper is an attempt at a critical review of hitherto accomplished studies and state of the art of predicting horizontal displacement u, in particular the coefficient B, whose value allows determination of the value of maximum displacement if the value of maximum slope is known, or the value of maximum deformation if the value of maximum trough slope is recognized. Since the geodesic observations of fully developed subsidence troughs suggest that the value of the coefficient depends on the depth H, radius of main influences range r and properties of overburden rock, in particular the occurrence of sub-eras Paleogene and Neogene layers (old name: Quaternary and Tertiary with low strength parameters, therefore a formula is provided in the present paper allowing for the estimation of the influence of those factors on the value of coefficient B.

  19. Sampling requirements for forage quality characterization of rectangular hay bales

    Energy Technology Data Exchange (ETDEWEB)

    Sheaffer, C.C.; Martin, N.P.; Jewett, J.G.; Halgerson, J.; Moon, R.D.; Cuomo, G.R.

    2000-02-01

    Commercial lots of alfalfa (Medicago sativa L.) hay are often bought and sold on the basis of forage quality. Proper sampling is essential to obtain accurate forage quality results for pricing of alfalfa hay, but information about sampling is limited to small, 20- to 40-kg rectangular bales. Their objectives were to determine the within-bale variation in 400-kg rectangular bales and to determine the number and distribution of core samples required to represent the crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and dry matter (DM) concentration in commercial lots of alfalfa hay. Four bales were selected from each of three hay lots and core sampled nine times per side for a total of 54 cores per bale. There was no consistent pattern of forage quality variation within bales. Averaged across lots, any portion of a bale was highly correlated with bale grand means for CP, ADF, NDF, and DM. Three lots of hay were probed six times per bale, one core per bale side from 55, 14, and 14 bales per lot. For determination of CP, ADF, NDF, and DM concentration, total core numbers required to achieve an acceptable standard error (SE) were minimized by sampling once per bale. Bootstrap analysis of data from the most variable hay lot suggested that forage quality of any lot of 400-kg alfalfa hay bales should be adequately represented by 12 bales sampled once per bale.

  20. Confined swimming of bio-inspired microrobots in rectangular channels.

    Science.gov (United States)

    Temel, Fatma Zeynep; Yesilyurt, Serhat

    2015-02-02

    Controlled swimming of bio-inspired microrobots in confined spaces needs to be understood well for potential use in medical applications in conduits and vessels inside the body. In this study, experimental and computational studies are performed for analysis of swimming modes of a bio-inspired microrobot in rectangular channels at low Reynolds number. Experiments are performed on smooth and rough surfaces using a magnetic helical swimmer (MHS), having 0.5 mm diameter and 2 mm length, with left-handed helical tail and radially polarized magnetic head within rotating magnetic field obtained by two electromagnetic coil pairs. Experiments indicate three motion modes of the MHS with respect to the rotation frequency: (i) lateral motion under the effect of a perpendicular force such as gravity and the surface traction at low frequencies, (ii) lateral motion under the effect of fluid forces and gravity at transition frequencies, and (iii) circular motion under the effect of fluid forces at high frequencies. Observed modes of motion for the MHS are investigated with computational fluid dynamics simulations by calculating translational and angular velocities and studying the induced flow fields for different radial positions inside the channel. Results indicate the importance of rotation frequency, surface roughness and flow field on the swimming modes and behaviour of the MHS inside the rectangular channel.

  1. Deformation of an elastic capsule in a rectangular microfluidic channel.

    Science.gov (United States)

    Kuriakose, S; Dimitrakopoulos, P

    2013-01-01

    In the present study we investigate computationally the deformation of an elastic capsule in a rectangular microfluidic channel and compare it with that of a droplet. In contrast to the bullet or parachute shape in a square or cylindrical channel where the capsule extends along the flow direction, in a rectangular channel the capsule extends mainly along the less-confined lateral direction of the channel cross-section (i.e. the channel width), obtaining a pebble-like shape. The different shape evolution in these two types of solid channels results from the different tension development on the capsule membrane required for interfacial stability. Furthermore, in asymmetric channel flows, capsules show a different deformation compared to droplets with constant surface tension (which extend mainly along the flow direction) and to vesicles which extend along the more-confined channel height. Therefore, our study highlights the different stability dynamics associated with these three types of interfaces. Our findings suggest that the erythrocyte deformation in asymmetric vessels (which is similar to that of capsules) results from the erythrocyte's inner spectrin skeleton rather than from its outer lipid bilayer.

  2. A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2014-01-01

    Full Text Available A rectangular planar spiral antenna sensor was designed for detecting the partial discharge in gas insulation substations (GIS. It can expediently receive electromagnetic waves leaked from basin-type insulators and can effectively suppress low frequency electromagnetic interference from the surrounding environment. Certain effective techniques such as rectangular spiral structure, bow-tie loading, and back cavity structure optimization during the antenna design process can miniaturize antenna size and optimize voltage standing wave ratio (VSWR characteristics. Model calculation and experimental data measured in the laboratory show that the antenna possesses a good radiating performance and a multiband property when working in the ultrahigh frequency (UHF band. A comparative study between characteristics of the designed antenna and the existing quasi-TEM horn antenna was made. Based on the GIS defect simulation equipment in the laboratory, partial discharge signals were detected by the designed antenna, the available quasi-TEM horn antenna, and the microstrip patch antenna, and the measurement results were compared.

  3. Numerical investigation of flow past a row of rectangular rods

    Directory of Open Access Journals (Sweden)

    S.Ul. Islam

    2016-09-01

    Full Text Available A numerical study of uniform flow past a row of rectangular rods with aspect ratio defined as R = width/height = 0.5 is performed using the Lattice Boltzmann method. For this study the Reynolds number (Re is fixed at 150, while spacings between the rods (g are taken in the range from 1 to 6. Depending on g, the flow is classified into four patterns: flip-flopping, nearly unsteady-inphase, modulated inphase-antiphase non-synchronized and synchronized. Sudden jumps in physical parameters were observed, attaining either maximum or minimum values, with the change in flow patterns. The mean drag coefficient (Cdmean of middle rod is higher than the second and fourth rod for flip-flopping pattern while in case of nearly unsteady-inphase the middle rod attains minimum drag coefficient. It is also found that the Strouhal number (St of first, second and fifth rod decreases as g increases while that of other two have mixed trend. The results further show that there exist secondary interaction frequencies together with primary vortex shedding frequency due to jet in the gap between rods for 1 ⩽ g ⩽ 3. For the average values of Cdmean and St, an empirical relation is also given as a function of gap spacing. This relation shows that the average values of Cdmean and St approach to those of single rectangular rod with increment in g.

  4. High-Frequency Underwater Acoustic Propagation in a Port Modeled as a Three-Dimensional Duct Closed at One End Using the Method of Images

    Directory of Open Access Journals (Sweden)

    Pierre-Philippe J. Beaujean

    2012-01-01

    Full Text Available A computer-efficient model for underwater acoustic propagation in a shallow, three-dimensional rectangular duct closed at one end has been developed using the method of images. The duct simulates a turning basin located in a port, surrounded with concrete walls, and filled with sea water. The channel bottom is composed of silt. The modeled impulse response is compared with the impulse response measured between 15 kHz and 33 kHz. Despite small sensor-position inaccuracies and an approximated duct geometry, the impulse response can be modeled with a relative echo magnitude error of 1.62 dB at worst and a relative echo location error varying between 0% and 4% when averaged across multiple measurements and sensor locations. This is a sufficient level of accuracy for the simulation of an acoustic communication system operating in the same frequency band and in shallow waters, as time fluctuations in echo magnitude commonly reach 10 dB in this type of environment.

  5. Treatment of infants with congenital nasolacrimal duct obstruction

    Directory of Open Access Journals (Sweden)

    Zhuo Chen

    2014-07-01

    Full Text Available AIM: To explore the different ages of congenital nasolacrimal duct obstruction in infants, take different treatment methods at different times. METHODS:The 87 cases of 102 children were divided into three different age groups: the first group of 25d-3mo of age 21 cases 26 eyes; The second group >3mo-7mo 31 cases 36 eyes; The third group >7-24mo of age 35 cases 40 eyes. For the first group of infants, the implementation of the lacrimal sac nasolacrimal duct massage + eye drops; for the second group of infants, carry lacrimal pressure washing treatment; for the third group of infants, the implementation of the nasolacrimal duct probing treatment. RESULTS:The first group of children through the nasolacrimal duct sac massage + drops tobramycin eye drops treatment unobstructed 12, the cure rate was 46.2%; The second group of children through pressurized irrigation treatment lacrimal patency by 33, the cure rate was 91.7%; The third group of children through the nasolacrimal duct probing unobstructed 36 treatment, the cure rate was 90.0%. The second and third group were better than the first group(χ2=15.71, Pχ2=15.27, Pχ2=0.02, P>0.05.CONCLUSION:Infants with congenital nasolacrimal duct obstruction should distinguish between ages, taking different treatments, in order to obtain a better therapeutic effect, and lacrimal pressure washing is the preferred way of treating infants with congenital nasolacrimal duct obstruction.

  6. Intraductal papillary neoplasm originating from an anomalous bile duct.

    Science.gov (United States)

    Maki, Harufumi; Aoki, Taku; Ishizawa, Takeaki; Tanaka, Mariko; Sakatani, Takashi; Beck, Yoshifumi; Hasegawa, Kiyoshi; Sakamoto, Yoshihiro; Kokudo, Norihiro

    2017-04-01

    An 82-year-old woman who had been suffering from repeated obstructive jaundice for 7 years was referred to our hospital. Although endoscopic aspiration of the mucin in the common bile duct had been temporally effective, origin of the mucin production had not been detectable. The patient thus had been forced to be on long-term follow-up without curative resection. Endoscopic retrograde cholangioscopy on admission revealed massive mucin in the common bile duct. In addition, an anomalous bile duct located proximal to the gallbladder was identified. Since the lumen of the anomalous duct was irregular and the rest of biliary tree was completely free of suspicious lesions, the anomalous duct was judged to be the primary site. Surgical resection of the segment 4 and 5 of the liver combined with the extrahepatic biliary tract was performed. Pathological diagnosis was compatible to intraductal papillary neoplasm with high-grade intraepithelial dysplasia of the anomalous bile duct. The patient has been free from the disease for 6.5 years after resection. This is the first case of intraductal papillary neoplasm derived from an anomalous bile duct, which was resected after long-term conservative treatment. The present case suggested the slow growing character of natural history of the neoplasm.

  7. [Clinicopathologic features of drug-induced vanishing bile duct syndrome].

    Science.gov (United States)

    Ye, L H; Wang, C K; Zhang, H C; Liu, Z Q; Zheng, H W

    2017-04-20

    Vanishing bile duct syndrome (VBDS) manifests as progressive destruction and disappearance of the intrahepatic bile duct caused by various factors and cholestasis. VBDS associated with drug-induced liver injury (D-VBDS) is an important etiology of VBDS, and immune disorder or immune imbalance may be the main pathogenesis. According to its clinical symptoms, serological markers, and course of the disease, D-VBDS is classified into major form and minor form, and its clinical features are based on various pathomorphological findings. Its prognosis is associated various factors including regeneration of bile duct cells, number of bile duct injuries, level and range of bile duct injury, bile duct proliferation, and compensatory shunt of bile duct branches. This disease has various clinical outcomes; most patients have good prognosis after drug withdrawal, and some patients may experience cholestatic cirrhosis, liver failure, and even death. Due to the clinical manifestation and biochemical changes are similar to the primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), it need to identify by clinical physician.

  8. Bile duct epithelial tight junctions and barrier function

    Science.gov (United States)

    Rao, R.K.; Samak, G.

    2013-01-01

    Bile ducts play a crucial role in the formation and secretion of bile as well as excretion of circulating xenobiotic substances. In addition to its secretory and excretory functions, bile duct epithelium plays an important role in the formation of a barrier to the diffusion of toxic substances from bile into the hepatic interstitial tissue. Disruption of barrier function and toxic injury to liver cells appear to be involved in the pathogenesis of a variety of liver diseases such as primary sclerosing cholangitis, primary biliary cirrhosis and cholangiocarcinoma. Although the investigations into understanding the structure and regulation of tight junctions in gut, renal and endothelial tissues have expanded rapidly, very little is known about the structure and regulation of tight junctions in the bile duct epithelium. In this article we summarize the current understanding of physiology and pathophysiology of bile duct epithelium, the structure and regulation of tight junctions in canaliculi and bile duct epithelia and different mechanisms involved in the regulation of disruption and protection of bile duct epithelial tight junctions. This article will make a case for the need of future investigations toward our understanding of molecular organization and regulation of canalicular and bile duct epithelial tight junctions. PMID:24665411

  9. Lesions of the segmental and lobar hepatic ducts.

    Science.gov (United States)

    Longmire, W P; Tompkins, R K

    1975-01-01

    Despite reports to the contrary, unobstructed drainage of 50% of an otherwise normal liver through either the right or left uninfected hepatic duct is adequate to restore normal liver function, even if the obstructed lobe remains in place. An undrained liver lobe, if present, may require no further treatment. As long as it is completely obstructed and uninfected, it will undergo a progressive asymptomatic atrophy. Cholangitis invariably develops behind a partial lobar ductal obstruction, producing jaundice, pruritis, and fever. Unless unobstructed, uninfected biliary flow can be achieved through a segmental or lobar duct, it is better that the duct be completely obstructed and the affected liver parenchyma allowed to atrophy, provided there is normal biliary flow from the residual 50% of liver. This concept is important in the management of injured anomalous segmental or lobar hepatic duct and in the palliative treatment of bile duct carcinoma. Localized intrahepatic infections communicating with abnormal biliary ducts will require hepatic resection of the infected parenchyma and ducts for cure. The abnormality may be saccular dilatation of the intrahepatic ductal system with abscess formation or intrahepatic abscess associated with stenosis of the ductal system from trauma to the duct, to the duct and liver, or to retained intrahepatic stones. Diffusely situated intrahepatic abscesses secondary to ductal abnormalities can be treated with systemic antibiotics, local drainage of a dmoninant abscess, and efforts to improve biliary drainage. Images Fig. 4. Fig. 5. Fig. 6. Fig. 8. Fig. 9. Fig. 10. Figs. 11A and B Figs. 12A and B. Fig. 13. Fig. 14. Fig. 15. Fig. 16. Fig. 17. PMID:1180585

  10. Spontaneous recanalization of the pancreatic duct: case report and review.

    Science.gov (United States)

    Arkovitz, M S; Garcia, V F

    1996-06-01

    An eight-year-old boy received a grade 3 pancreatic injury as a result of a bicycle handlebar accident. Endoscopic retrograde cholangiopancreatography (ERCP) showed a proximal pancreatic duct transection. At laparotomy, a complete transection of the gland and duct was visualized; however, only debridement and external fistulization were performed. Follow-up ERCP performed 3 months postoperatively showed recanalization of the pancreatic duct without further operative intervention. At 1-year follow-up, the patient is pain free and tolerating a regular diet.

  11. ROV [Remotely Operated Vehicle] inspection inside ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, R.E. [AEA Technology, Harwell (United Kingdom)

    1996-12-31

    An instrumentation package for carrying out visual inspections and radiation monitoring within radioactive duct-work has been developed. This paper describes the first application of the package in the main ventilation duct of the Dounreay fuel cycle area. The package was deployed via a commercial ROV within a duct consisting of two parallel runs, over 300 metres long, between 0.9 and 1.7 metres high and 1.1 metres wide. An integrated, computer-controlled station was used for data collection, recording in digital form and on video tape. (UK).

  12. Bile duct adenoma and von Meyenburg complex-like duct arising in hepatitis and cirrhosis: pathogenesis and histological characteristics.

    Science.gov (United States)

    Aishima, Shinichi; Tanaka, Yuki; Kubo, Yuichiro; Shirabe, Ken; Maehara, Yoshihiko; Oda, Yoshinao

    2014-11-01

    Morphologic features and neoplastic potentials of bile duct adenoma (BDA) and von Meyenburg complex (VMC)-like duct arising in chronic liver disease were unknown. Thirty-five BDAs and 12 VMC-like duct lesions were observed in 39 cases with chronic liver disease. BDAs were divided into the EMA-cytoplasmic type (n = 14) and EMA-luminal type (n = 21). EMA-cytoplasmic BDA composed of a proliferation of cuboidal to low-columnar cells forming an open lumen with NCAM(+)/MUC6(-), resembling an interlobular bile duct. EMA-luminal BDA showed uniform cuboidal cells with narrow lumen, and NCAM(++)/MUC6(++), resembling a ductular reaction. VMC-like duct showed positive MUC1 expression and negative MUC6. The expression of S100P, glucose transporter-1 (GLUT-1) and insulin-like growth factor II mRNA-binding protein 3 (IMP-3) were not detected in three lesions. p16 expression was higher than those of the ductular reaction, and the Ki67 and p53 indexes were very low (bile duct type; BDA, ductular/peribiliary gland type; and VMC-like duct. They may be reactive proliferation rather than neoplastic lesions. © 2014 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.

  13. Technical knacks and outcomes of extended extrahepatic bile duct resection in patients with mid bile duct cancer

    Science.gov (United States)

    Lee, Seung-Jae; Ha, Tae-Yong; Kim, Ki-Hun; Ahn, Chul-Soo; Moon, Deok-Bog; Song, Gi-Won; Jung, Dong-Hwan; Park, Gil-Chun; Lee, Sung-Gyu

    2013-01-01

    Backgrounds/Aims Mid bile duct cancers often involve the proximal intrapancreatic bile duct, and resection of the extrahepatic bile duct (EHBD) can result in a tumor-positive distal resection margin (RM). We attempted a customized surgical procedure to obtain a tumor-free distal RM during EHBD resection, so that R0 resection can be achieved without performing pancreaticoduodenectomy through extended EHBD resection. Methods We previously reported the surgical procedures of extended EHBD resection, in which the intrapancreatic duct excavation resembles a ≥2 cm-long funnel. This unique procedure was performed in 11 cases of mid bile duct cancer occurring in elderly patients between the ages of 70 and 83 years. Results The tumor involved the intrapancreatic duct in all cases. Deep pancreatic excavation per se required about 30-60 minutes. Cancer-free hepatic duct RM was obtained in 10 patients. Prolonged leakage of pancreatic juice occurred in 2 patients, but all were controlled with supportive care. Adjuvant therapies were primarily applied to RM-positive or lymph node-positive patients. Their 1-year and 3-year survival rates were 90.9% and 60.6%, respectively. Conclusions We suggest that extended EHBD resection can be performed as a beneficial option to achieve R0 resection in cases in which pancreaticoduodenectomy should be avoided due to various causes including old age and expectation of a poor outcome. PMID:26155223

  14. Bile Duct Cancer (Cholangiocarcinoma) Treatment (PDQ®)—Health Professional Version

    Science.gov (United States)

    Bile duct cancer (also called cholangiocarcinoma) can occur in the bile ducts in the liver (intrahepatic) or outside the liver (perihilar or distal extrahepatic). Learn about the types of bile duct cancer, risk factors, clinical features, staging, and treatment for bile duct cancer in this expert-reviewed summary.

  15. Calculation of wakefields in 2D rectangular structures

    Energy Technology Data Exchange (ETDEWEB)

    Zagorodnov, I. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Bane, K.L.F.; Stupakov, G. [Stanford Univ., CA (United States). SLAC National Accelerator Lab.

    2015-08-15

    We consider the calculation of electromagnetic fields generated by an electron bunch passing through a vacuum chamber structure that, in general, consists of an entry pipe, followed by some kind of transition or cavity, and ending in an exit pipe. We limit our study to structures having rectangular cross-section, where the height can vary as function of longitudinal coordinate but the width and side walls remain fixed. For such structures, we derive a Fourier representation of the wake potentials through one-dimensional functions. A new numerical approach for calculating the wakes in such structures is proposed and implemented in the computer code ECHO(2D). The computation resource requirements for this approach are moderate and comparable to those for finding the wakes in 2D rotationally symmetric structures. Numerical examples obtained with the new numerical code are presented.

  16. Calculation of wakefields in 2D rectangular structures

    Directory of Open Access Journals (Sweden)

    I. Zagorodnov

    2015-10-01

    Full Text Available We consider the calculation of electromagnetic fields generated by an electron bunch passing through a vacuum chamber structure that, in general, consists of an entry pipe, followed by some kind of transition or cavity, and ending in an exit pipe. We limit our study to structures having rectangular cross section, where the height can vary as function of longitudinal coordinate but the width and side walls remain fixed. For such structures, we derive a Fourier representation of the wake potentials through one-dimensional functions. A new numerical approach for calculating the wakes in such structures is proposed and implemented in the computer code echo(2d. The computation resource requirements for this approach are moderate and comparable to those for finding the wakes in 2D rotationally symmetric structures. Numerical examples obtained with the new numerical code are presented.

  17. Are Haar-like Rectangular Features for Biometric Recognition Reducible?

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2013-01-01

    ? This paper proposes total sensitivity analysis about the mean for this purpose for two different biometric traits, iris and face. Experimental results on multiple public databases show the superiority of the proposed system, using the found influential features, compared to state-of-the-art biometric......Biometric recognition is still a very difficult task in real-world scenarios wherein unforeseen changes in degradations factors like noise, occlusion, blurriness and illumination can drastically affect the extracted features from the biometric signals. Very recently Haar-like rectangular features...... which have usually been used for object detection were introduced for biometric recognition resulting in systems that are robust against most of the mentioned degradations [9]. The problem with these features is that one can define many different such features for a given biometric signal...

  18. Metamaterial absorbers realized in an X-band rectangular waveguide

    Science.gov (United States)

    Huang, Yong-Jun; Wen, Guang-Jun; Li, Jian; Zhong, Jing-Ping; Wang, Ping; Sun, Yuan-Hua; O., Gordon; Zhu, Wei-Ren

    2012-11-01

    In this paper, we demonstrate six types of metamaterial absorbers (MMAs) by measuring their absorptivities in an X-band (8-12 GHz) rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.

  19. Complex Ohmic conductance of electrolytes in rectangular microchannels

    Science.gov (United States)

    Campisi, Michele; Accoto, Dino; Dario, Paolo

    2006-04-01

    Motivated by the interest that microelectrolytic systems are gaining in the development of the so-called lab-on-a-chip systems, i.e., miniature microfluidic devices for biochemical analysis, we present an analytical study of Ohmic conduction in rectangular charged microchannels filled with electrolytic solution. The study complements a previous one [M. Campisi et al., J. Chem. Phys. 123, 204724 (2005)], concerning ac electro-osmosis. The problem is framed within the theory of nonequilibrium thermodynamics and is based on the solution of the incompressible Navier-Stokes equation with an electrical body force due to the interaction of the applied electric field with the charged electric double layer (EDL) which forms at the solid-liquid interface. We analyze in detail the dependence of the system complex conductance on the ratio linear dimensions over Debye length with an eye on finite EDL effects, and compare its scaling properties with those of electrokinetic and hydraulic complex conductances.

  20. Oscillating flow and separation of species in rectangular channels

    Energy Technology Data Exchange (ETDEWEB)

    Hacioglu, A., E-mail: ahacioglu@ufl.edu; Narayanan, R., E-mail: ranga@ufl.edu [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2016-07-15

    The mass transfer and separation of species in a tube using oscillatory flows are strongly affected by the fluid flow profiles in the tube. It has been well established that oscillatory motion in a one-dimensional flow configuration leads to a single tuning dimensionless frequency, where optimum separation may be effected. In this work, the effect on species separation by two-dimensional laminar flow arising in a rectangular cross section is studied and a surprising result is that a second tuning frequency may occur at lower dimensionless oscillation frequencies. The physics reveals that this new optimum disappears when the aspect ratio is either very large or close to unity. These observations are related to the flow profiles at different aspect ratios.

  1. Free Vibration Analysis of Rectangular Orthotropic Membranes in Large Deflection

    Directory of Open Access Journals (Sweden)

    Zheng Zhou-Lian

    2009-01-01

    Full Text Available This paper reviewed the research on the vibration of orthotropic membrane, which commonly applied in the membrane structural engineering. We applied the large deflection theory of membrane to derive the governing vibration equations of orthotropic membrane, solved it, and obtained the power series formula of nonlinear vibration frequency of rectangular membrane with four edges fixed. The paper gave the computational example and compared the two results from the large deflection theory and the small one, respectively. Results obtained from this paper provide some theoretical foundation for the measurement of pretension by frequency method; meanwhile, the results provide some theoretical foundation for the research of nonlinear vibration of membrane structures and the response solving of membrane structures under dynamic loads.

  2. Experimental study of natural circulation flow instability in rectangular channels

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Tao; Qi, Shi; Song, Mingqiang [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Passive Nuclear Safety Technology, Beijing (China). Beijing Key Lab.; Xiao, Zejun [Nuclear, Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.

    2017-05-15

    Experiments of natural circulation flow instability were conducted in rectangular channels with 5 mm and 10 mm wide gaps. Results for different heating powers were obtained. The results showed that the flow will tend to be instable with the growing of heating power. The oscillation period of pressure D-value and volume flow are the same, but their phase positions are opposite. They both can be described by trigonometric functions. The existence of edge position and secondary flow will strengthen the disturbance of fluid flow in rectangle channels, which contributes to heat transfer. The disturbance of bubble and fluid will be strengthened, especially in the saturated boiling section, which make it possible for the mixing flow. The results also showed that the resistance in 5 mm channel is bigger than that in 10 mm channel, it is less likely to form stable natural circulation in the subcooled region.

  3. Mechanisms of rectangular groove-induced multiple-microdroplet coalescences

    Science.gov (United States)

    Shen, Feng; Li, Yi; Wang, Guiren; Liu, Zhaomiao

    2017-06-01

    The mechanism of microdroplet coalescence is a fundamental issue for droplet-based microfluidics. We developed an asymmetric expansion (a rectangular groove) along one side of a microchannel to achieve multiple-microdroplet trapping, collision, and coalescence. Compared with reported symmetric expansions, this asymmetric groove could easily trap microdroplets and control two or three microdroplet coalescences precisely without a requirement for temporal and spatial synchronization. To reveal the mechanisms of multiple-droplet coalescences in a groove, we observed five different coalescence patterns under different flow conditions. Moreover, we characterized the flow behavior quantitatively by simulating the velocity vector fields in both the microdroplets and continuous phase, finding good agreement with experiments. Finally, a map of coalescence forms with different capillary numbers (0.001droplet-based microfluidic devices.

  4. Spatial impulse response of a rectangular double curved transducer

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2012-01-01

    Calculation of the pressure field from transducers having both a convex and a concave surface geometry is a complicated assignment that often is accomplished by subdividing the transducer surface into smaller flat elements of which the spatial impulse response is known. This method is often seen...... applied to curved transducers because an analytical solution is un-known. In this work a semi-analytical algorithm for the exact solution to a first order in diffraction effect of the spatial impulse response of rectangular shaped double curved transducers is presented. The algorithm and an approximation...... approximations ranging from 0.03 % to 0.8 % relative to a numerical solution for the spatial impulse response. It is shown that the presented algorithm gives consistent results with Field II for a linear flat, a linear focused, and a convex non-focused element. Best solution was found to be 0.01 % with a three...

  5. Self-induced vortex ring dynamics in subsonic rectangular jets

    Science.gov (United States)

    Grinstein, Fernando F.

    1995-10-01

    The development in space and time of vortex rings in low aspect-ratio (AR) rectangular jets is investigated. By design, the present studies isolate the self-induced ring dynamics from effects of unsteady events otherwise present upstream and downstream of the rings in developed jets. The simulations show that the vortex rings undergo quite regular self-induced nonplanar deformations, approximately recovering their shape and flatness with axis rotated with respect to their initial configuration. The axis-rotation periods are in good agreement with previously reported data for pseudoelliptic rings, and exhibit nearly linear growth rate as a function of AR. For the larger aspect-ratio case studied (AR=4), bifurcation of the ring due to vortex reconnection into roughly round rings is observed, followed by collision of the split rings and a new reconnection process, suggesting pathways for transition to turbulence based on self-induced vortex deformations and reconnections.

  6. Critical current studies of a HTS rectangular coil

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Z. [Department of Engineering, University of Cambridge (United Kingdom); Chudy, M., E-mail: Michal.chudy@stuba.sk [Graduate School of Technology Management, University of Pretoria (South Africa); Institute of Power and Applied Electrical Engineering, Slovak University of Technology in Bratislava (Slovakia); Ruiz, H.S. [Department of Engineering, University of Leicester, Leicester LE1 7RH (United Kingdom); Zhang, X.; Coombs, T. [Department of Engineering, University of Cambridge (United Kingdom)

    2017-05-15

    Highlights: • Unique square pancake coil was manufactured. • Measurements in relatively high magnetic field were performed. • Different sections of the coil were characterized. • Parts of the coil which are limiting critical current were identified. - Abstract: Nowadays, superconducting high field magnets are used in numerous applications due to their superior properties. High temperature superconductors (HTS) are usually used for production of circular pancake or racetrack coils. However different geometries of HTS coils might be required for some specific applications. In this study, the HTS coil wound on a rectangular frame was fully characterized in homogeneous DC background field. The study contains measurements of critical current angular dependencies. The critical current of the entire coil and two selected strands under different magnitudes and orientations of external magnetic fields are measured. The critical regions of the coil in different angular regimes are determined. This study brings better understanding of the in- field performance of HTS coils wound on frames with right-angles.

  7. Generation of high current, long duration rectangular pulses

    CERN Document Server

    Faugeras, Paul E; Zanasco, J P

    1973-01-01

    The excitation of the fast pulsed kicker magnets foreseen for the CERN 400 GeV proton synchrotron requires rectangular pulses with a current amplitude of 3000 A to 10000 A, a pulse duration adjustable between 1 and 24 mu sec, and short rise and fall times. These pulses are generated by a LC ladder network discharged with fast switches. Several kinds of switches have been tested: multigap thyratrons of standard design, a composite switch called 'thyragnitron' and made of a normal thyratron by-passed ignitrons, and finally special thyratrons with a second cathode assembly in place of the usual anode. Experimental pulse shapes and results of life tests for these different switches are presented and discussed. (8 refs).

  8. A case of double common bile duct in a deceased donor for transplantation.

    Science.gov (United States)

    Imamura, Hajime; Eguchi, Susumu; Shapiro, A M James; Kin, Tatsuya

    2017-12-01

    A double common bile duct is extremely rare among the anatomical variations in the biliary tract system. We report an incidentally encountered case of the double common bile duct and discuss the novel anatomical findings of the accessory common bile duct from the viewpoint of embryology. A unique point of our case is that the accessory common bile duct bifurcated at the level of the intrapancreatic bile duct. There is no similar case in the previous literature among type II double common bile duct in the viewpoint of anatomical findings of the accessory common bile duct. We assume that this asymptomatic anatomical variation may be present more commonly, but not diagnosed.

  9. Low Cost/Low Noise Variable Pitch Ducted Fan Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ACI proposes a design for a Propulsor (Low Cost/Low Noise Variable Pitch Ducted Fan) that has wide application in all sectors of Aviation. Propulsor hardware of this...

  10. Biliary duct obstruction treatment with aid of percutaneous ...

    African Journals Online (AJOL)

    Biliary duct obstruction treatment with aid of percutaneous transhepatic biliary drainage. Daniel Knap, Natalia Orlecka, Renata Judka, Aleksandra Juza, Michał Drabek, Maciej Honkowicz, Tomasz Kirmes, Bartosz Kadłubicki, Dominik Sieron, Jan Baron ...

  11. Lacrimal gland duct stones: misdiagnosed as chalazion in 3 cases.

    Science.gov (United States)

    Kim, Sung Chul; Lee, Kook; Lee, Sang Un

    2014-02-01

    To report 3 cases of lacrimal gland duct stones misdiagnosed as chalazion. Retrospective case series. Three patients with lacrimal gland duct stones misdiagnosed as chalazion at a local clinic between 2010 and 2012. A thorough review of clinical, imaging, and histopathologic manifestations. Clinical manifestations of lacrimal gland duct stones included conjunctival injection, lid swelling, tenderness, and ocular discharge, which are similar to chalazion symptoms. Computed tomography revealed a relatively well-defined, high-density mass near the lacrimal gland. Histopathologic examination of excised material revealed calcified amorphous stones. Intractable chalazion-like lesions at the lateral canthal area near the lacrimal gland should be carefully examined; imaging studies are required to confirm the presence of lacrimal gland duct stones, which require surgical removal. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  12. Measure Guideline: Buried and/or Encapsulated Ducts

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, C. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Zoeller, W. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Mantha, P. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

    2013-08-01

    Buried and/or encapsulated ducts (BEDs) are a class of advanced, energy-efficiency strategies intended to address the significant ductwork thermal losses associated with ducts installed in unconditioned attics. BEDs are ducts installed in unconditioned attics that are covered in loose-fill insulation and/or encapsulated in closed cell polyurethane spray foam insulation. This Measure Guideline covers the technical aspects of BEDs as well as the advantages, disadvantages, and risks of BEDs compared to other alternative strategies. This guideline also provides detailed guidance on installation of BEDs strategies in new and existing homes through step-by-step installation procedures. Some of the procedures presented here, however, require specialized equipment or expertise. In addition, some alterations to duct systems may require a specialized license.

  13. Ducting arrangement for cooling a gas turbine structure

    Science.gov (United States)

    Lee, Ching-Pang; Morrison, Jay A.

    2015-07-21

    A ducting arrangement (10) for a can annular gas turbine engine, including: a duct (12, 14) disposed between a combustor (16) and a first row of turbine blades and defining a hot gas path (30) therein, the duct (12, 14) having raised geometric features (54) incorporated into an outer surface (80); and a flow sleeve (72) defining a cooling flow path (84) between an inner surface (78) of the flow sleeve (72) and the duct outer surface (80). After a cooling fluid (86) traverses a relatively upstream raised geometric feature (90), the inner surface (78) of the flow sleeve (72) is effective to direct the cooling fluid (86) toward a landing (94) separating the relatively upstream raised geometric feature (90) from a relatively downstream raised geometric feature (94).

  14. Minimally invasive treatment of extrahepatic bile duct stones

    Directory of Open Access Journals (Sweden)

    HAN Wurijile

    2015-05-01

    Full Text Available With the continuous improvement of endoscopic technology and equipment, minimally invasive treatment of bile duct stones becomes increasingly diversified. In this paper, the concept of minimally invasive treatment of bile duct stones, surgical indications and contraindications, surgical methods, and the advantages and disadvantages of surgical methods are introduced. It is shown that the application of laparoscope has laid the foundation for the minimally invasive treatment of bile duct stones, and the combined application of choledochoscope and endoscope has brought new ideas for minimally invasive treatment of bile duct stones. The combination of three endoscopes avoids the disadvantages of traditional open surgery: large trauma and long operation time, and reduces the patient′s pain and complications. In the near future, the combination of three endoscopes still has much room for growth. As long as the indications for several surgeries are mastered and the safety and efficacy are evaluated objectively, the combination of three endoscopes will play the biggest role.

  15. Nasolacrimal Duct Mucocele: Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Britto, Fernanda Carneiro Corujeira de

    2014-02-01

    Full Text Available Introduction Mucoceles are benign expansive cystic formations, composed of a mucus-secreting epithelium (respiratory or pseudostratified epithelium. Nasolacrimal mucocele occurs in a small proportion of children with nasolacrimal duct obstruction and is characterized by a cystic mass in the medial canthus with dilation of the nasolacrimal duct; although dacryocystoceles are rare in adults, they have been reported in patients with trachoma. Objective Discuss clinical aspects, diagnosis, and therapeutic management of mucocele of nasolacrimal duct based on literature review. Resumed Report The authors report a case of bilateral congenital nasolacrimal duct cysts in a 30-year-old man, identified as a tumor in the topography of both lacrimal sacs since birth without associated symptoms. The patient underwent successive surgical treatments, leading to recurrence of the tumor at the right side and recurrent local infections. Conclusion Endoscopic dacryocystorhinostomy has been increasingly used with good results and success rates similar to the external access.

  16. Dynamic Response of Ground Supported Rectangular Water Tanks ...

    African Journals Online (AJOL)

    Bheema

    distribution developed in rigid tanks for a horizontal base excitation (Jaiswal and Jain, 2005a,b). In fact, prior to the advent of modern computers and the widespread of numerical methods in structural engineering, water storage tanks were analyzed mathematically using closed form shell analysis solutions together with ...

  17. A Multi-Objective Approach to Visualize Proportions and Similarities Between Individuals by Rectangular Maps

    DEFF Research Database (Denmark)

    Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero

    In this paper we address the problem of visualizing the proportions and the similarities attached to a set of individuals. We represent this information using a rectangular map, i.e., a subdivision of a rectangle into rectangular portions so that each portion is associated with one individual, th...

  18. On Mathematical Optimization for the Visualization of Frequencies and Adjacencies as Rectangular Maps

    DEFF Research Database (Denmark)

    Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero

    2018-01-01

    In this paper we address the problem of visualizing a frequency distribution and an adjacency relation attached to a set of individuals. We represent this information using a rectangular map, i.e., a subdivision of a rectangle into rectangular portions so that each portion is associated with one ...

  19. Piezoelectrically forced vibrations of rectangular SC-cut quartz plates

    Science.gov (United States)

    Lee, P. C. Y.; Lin, W. S.

    1998-06-01

    A system of two-dimensional first-order equations for piezoelectric crystal plates with general symmetry and with electroded faces was recently deduced from the three-dimensional equations of linear piezoelectricity. Solutions of these equations for AT-cut plates of quartz were shown to give accurate dispersion curves without corrections, and the resonances predicted agree closely with the experimental data of Koga and Fukuyo [I. Koga and H. Fukuyo, J. Inst. Electr. Commun. Eng. Jpn. 36, 59 (1953)] and that of Nakazawa, Horiuchi, and Ito (M. Nakazawa, K. Horiuchi, and H. Ito, Proceedings of the 1990 IEEE Ultrasonics Symposium, pp. 547-555). In this article, these equations are employed to study the free as well as the forced vibrations of doubly rotated quartz plates. Solutions of straight-crested vibrational modes varying in the x1 and x3 directions of SC-cut quartz plates of infinite extent are obtained and from which dispersion curves are computed. Comparison of those dispersion curves with those from the three-dimensional equations shows that the agreement is very close without any corrections. Resonance frequencies for free vibrations and capacitance ratios for piezoelectrically forced vibrations are computed and examined for various length-to-thickness or width-to-thickness ratios of rectangular SC-cut quartz plates. The capacitance ratio as a function of forcing frequency is computed for a rectangular AT-cut quartz and compared with the experimental data of Seikimoto, Watanabe, and Nakazawa (H. Sekimoto, Y. Watanabe, and M. Nakazawa, Proceedings of the 1992 IEEE Frequency Control Symposium, pp. 532-536) and is in close agreement.

  20. Quantitative study of rectangular waveguide behavior in the THz.

    Energy Technology Data Exchange (ETDEWEB)

    Rowen, Adam M.; Nordquist, Christopher Daniel; Wanke, Michael Clement

    2009-10-01

    This report describes our efforts to quantify the behavior of micro-fabricated THz rectangular waveguides on a configurable, robust semiconductor-based platform. These waveguides are an enabling technology for coupling THz radiation directly from or to lasers, mixers, detectors, antennas, and other devices. Traditional waveguides fabricated on semiconductor platforms such as dielectric guides in the infrared or co-planar waveguides in the microwave regions, suffer high absorption and radiative losses in the THz. The former leads to very short propagation lengths, while the latter will lead to unwanted radiation modes and/or crosstalk in integrated devices. This project exploited the initial developments of THz micro-machined rectangular waveguides developed under the THz Grand Challenge Program, but instead of focusing on THz transceiver integration, this project focused on exploring the propagation loss and far-field radiation patterns of the waveguides. During the 9 month duration of this project we were able to reproduce the waveguide loss per unit of length in the waveguides and started to explore how the loss depended on wavelength. We also explored the far-field beam patterns emitted by H-plane horn antennas attached to the waveguides. In the process we learned that the method of measuring the beam patterns has a significant impact on what is actually measured, and this may have an effect on most of the beam patterns of THz that have been reported to date. The beam pattern measurements improved significantly throughout the project, but more refinements of the measurement are required before a definitive determination of the beam-pattern can be made.

  1. DUCT RETROFIT STRATEGY TO COMPLEMENT A MODULATING FURNACE.

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS,J.W.

    2002-10-02

    Some recent work (Walker 2001, Andrews 2002) has indicated that installing a modulating furnace in a conventional duct system may, in many cases, result in a significant degradation in thermal distribution efficiency. The fundamental mechanism was pointed out nearly two decades ago (Andrews and Krajewski 1985). The problem occurs in duct systems that are less-than-perfectly insulated (e.g., R-4 duct wrap) and are located outside the conditioned space. It stems from the fact that when the airflow rate is reduced, as it will be when the modulating furnace reduces its heat output rate, the supply air will have a longer residence time in the ducts and will therefore lose a greater percentage of its heat by conduction than it did at the higher airflow rate. The impact of duct leakage, on the other hand, is not expected to change very much under furnace modulation. The pressures in the duct system will be reduced when the airflow rate is reduced, thus reducing the leakage per unit time. This is balanced by the fact that the operating time will increase in order to meet the same heating load as with the conventional furnace operating at higher output and airflow rates. The balance would be exact if the exponent in the pressure vs. airflow equation were the same as that in the pressure vs. duct leakage equation. Since the pressure-airflow exponent is usually {approx}0.5 and the pressure-leakage exponent is usually {approx}0.6, the leakage loss as a fraction of the load should be slightly lower for the modulating furnace. The difference, however, is expected to be small, determined as it is by a function with an exponent equal to the difference between the above two exponents, or {approx}0.1. The negative impact of increased thermal conduction losses from the duct system may be partially offset by improved efficiency of the modulating furnace itself. Also, the modulating furnace will cycle on and off less often than a single-capacity model, and this may add a small amount

  2. Compact Buried Ducts in a Hot-Humid Climate House

    Energy Technology Data Exchange (ETDEWEB)

    Mallay, D. [Home Innovation Research Labs, Upper Marlboro, MD (United States)

    2016-01-01

    A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval.

  3. Surgical versus endoscopic treatment of bile duct stones

    DEFF Research Database (Denmark)

    Martin, D J; Vernon, D R; Toouli, J

    2006-01-01

    10% to 18% of patients undergoing cholecystectomy for gallstones have common bile duct (CBD) stones. Treatment options for these stones include pre- or post-operative endoscopic retrograde cholangiopancreatography (ERCP) or open or laparoscopic surgery.......10% to 18% of patients undergoing cholecystectomy for gallstones have common bile duct (CBD) stones. Treatment options for these stones include pre- or post-operative endoscopic retrograde cholangiopancreatography (ERCP) or open or laparoscopic surgery....

  4. Numerical Modeling of a Ducted Rocket Combustor With Experimental Validation

    OpenAIRE

    Hewitt, Patrick

    2008-01-01

    The present work was conducted with the intent of developing a high-fidelity numerical model of a unique combustion flow problem combining multi-phase fuel injection with substantial momentum and temperature into a highly complex turbulent flow. This important problem is very different from typical and more widely known liquid fuel combustion problems and is found in practice in pulverized coal combustors and ducted rocket ramjets. As the ducted rocket engine cycle is only now finding wides...

  5. Better Duct Systems for Home Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    2004-11-01

    Duct systems used in forced-air space-conditioning systems are a vital element in home energy efficiency. How well a system works makes a big difference in the cost and the effectiveness of heating and cooling a home. At the same time, a duct system that is poorly designed or maintained can have a detrimental effect on the health of the people who live in the house, through the unintended distribution of indoor air pollution.

  6. Parotid duct stenosis: interventional radiology to the rescue.

    Science.gov (United States)

    Roberts, D N; Juman, S; Hall, J R; Jonathan, D A

    1995-11-01

    Recurrent parotid sialadenitis due to isolated parotid duct stenosis is an uncommon condition and poses a difficult management problem. Conventional surgical practice carries with it a potentially high morbidity for what is a benign condition. We present three cases where parotid duct stenosis has been treated by balloon dilatation and propose that this is a safe, quick and repeatable method for dealing with this problem.

  7. BETTER DUCT SYSTEMS FOR HOME HEATING AND COOLING.

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS,J.

    2001-01-01

    This is a series of six guides intended to provide a working knowledge of residential heating and cooling duct systems, an understanding of the major issues concerning efficiency, comfort, health, and safety, and practical tips on installation and repair of duct systems. These guides are intended for use by contractors, system designers, advanced technicians, and other HVAC professionals. The first two guides are also intended to be accessible to the general reader.

  8. Effect of surface deposits on electromagnetic propagation in uniform ducts

    Science.gov (United States)

    Baumeister, Kenneth J.

    1991-01-01

    A finite-element Galerkin formulation has been used to study the effect of material surface deposits on the reflective characteristics of straight uniform ducts with PEC (perfectly electric conducting) walls. Over a wide frequency range, the effect of both single and multiple dielectric surface deposits on the duct reflection coefficient were examined. The power reflection coefficient was found to be significantly increased by the addition of deposits on the wall.

  9. Analysis of junior high school students' difficulty in resolving rectangular conceptual problems

    Science.gov (United States)

    Utami, Aliksia Kristiana Dwi; Mardiyana, Pramudya, Ikrar

    2017-08-01

    Geometry is one part of the mathematics that must be learned in school and it has important effects on the development of creative thinking skills of learners, but in fact, there are some difficulties experienced by the students. This research focuses on analysis difficulty in resolving rectangular conceptual problems among junior high school students in every creative thinking skills level. This research used a descriptive method aimed to identify the difficulties and cause of the difficulties experienced by five students. The difficulties are associated with rectangular shapes and related problems. Data collection was done based on students' work through test, interview, and observations. The result revealed that student' difficulties in understanding the rectangular concept can be found at every creative thinking skills level. The difficulties are identifying the objects rectangular in the daily life except for a rectangle and square, analyzing the properties of rectangular shapes, and seeing the interrelationships between figures.

  10. Disentangling rectangularization and life span extension with the moving rectangle method

    DEFF Research Database (Denmark)

    Schalkwijk, Frank H; Koopman, Jacob J E; Ghariq, Eidrees

    2016-01-01

    PURPOSE: The moving rectangle method is used to disentangle the contributions of rectangularization and life span extension to the increase in life expectancy. It requires the choice of an endpoint of the survival curve that approaches the maximum age at death. We examined the effect of choosing...... of rectangularization and life span extension to the increase in life expectancy were calculated using the moving rectangle method. RESULTS: The choice of different survival values as end points profoundly influenced the estimated contributions of rectangularization and life span extension to the increase in life...... expectancy. When choosing 0.001, rectangularization contributed most years, whereas when choosing 0.1, life span extension contributed most years. CONCLUSIONS: When the moving rectangle method is used to estimate the contributions of rectangularization and life span extension to the increase in life...

  11. Finite element fatigue analysis of rectangular clutch spring of automatic slack adjuster

    Science.gov (United States)

    Xu, Chen-jie; Luo, Zai; Hu, Xiao-feng; Jiang, Wen-song

    2015-02-01

    The failure of rectangular clutch spring of automatic slack adjuster directly affects the work of automatic slack adjuster. We establish the structural mechanics model of automatic slack adjuster rectangular clutch spring based on its working principle and mechanical structure. In addition, we upload such structural mechanics model to ANSYS Workbench FEA system to predict the fatigue life of rectangular clutch spring. FEA results show that the fatigue life of rectangular clutch spring is 2.0403×105 cycle under the effect of braking loads. In the meantime, fatigue tests of 20 automatic slack adjusters are carried out on the fatigue test bench to verify the conclusion of the structural mechanics model. The experimental results show that the mean fatigue life of rectangular clutch spring is 1.9101×105, which meets the results based on the finite element analysis using ANSYS Workbench FEA system.

  12. Parotid duct laceration repair in two horses : case report

    Directory of Open Access Journals (Sweden)

    A. Olivier

    1998-07-01

    Full Text Available Repair of parotid duct lacerations in 2 horses is described using intraluminal silastic tubing as a stent. The duct was lacerated traumatically at the facial vessel notch (incisura vasorum facialium in the 1st horse, and iatrogenically after removal of an intraluminal sialolith after development of infection within the duct in the 2nd horse. In both cases, a silastic tube was passed retrograde into the duct via the salivary papilla, past the wound until the end lay rostroventral to the parotid salivary gland. The severed salivary ducts and the wounds were sutured. The external portion of the silastic tube was sutured to the skin and the tube left in place. Recovery in the 1st case was uneventful. In the 2nd case a salivary duct/cutaneous fistula formed at a wound distant from the sutured wound, which healed spontaneously. This technique differs from a similar described technique in that the stent tube exits the oral cavity and is attached to the outer skin surface.

  13. Measure Guideline: Buried and/or Encapsulated Ducts

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, C.; Zoeller, W.; Mantha, P.

    2013-08-01

    Buried and/or encapsulated ducts (BEDs) are a class of advanced, energy-efficiency strategies intended to address the significant ductwork thermal losses associated with ducts installed in unconditioned attics. BEDs are ducts installed in unconditioned attics that are covered in loose-fill insulation and/or encapsulated in closed cell polyurethane spray foam insulation. This Measure Guideline covers the technical aspects of BEDs as well as the advantages, disadvantages, and risks of BEDs compared to other alternative strategies. This guideline also provides detailed guidance on installation of BEDs strategies in new and existing homes through step-by-step installation procedures. This Building America Measure Guideline synthesizes previously published research on BEDs and provides practical information to builders, contractors, homeowners, policy analysts, building professions, and building scientists. Some of the procedures presented here, however, require specialized equipment or expertise. In addition, some alterations to duct systems may require a specialized license. Persons implementing duct system improvements should not go beyond their expertise or qualifications. This guideline provides valuable information for a building industry that has struggled to address ductwork thermal losses in new and existing homes. As building codes strengthen requirements for duct air sealing and insulation, flexibility is needed to address energy efficiency goals. While ductwork in conditioned spaces has been promoted as the panacea for addressing ductwork thermal losses, BEDs installations approach - and sometimes exceed - the performance of ductwork in conditioned spaces.

  14. Improving Diffusing S-duct Performance by Secondary Flow Control

    Science.gov (United States)

    Reichert, Bruce A.; Wendt, Bruce J.

    1994-01-01

    The objective of this research was to study ways to reduce inlet flow distortion (i.e., total pressure nonuniformity) and improve total pressure recovery in a diffusing S-duct. This was accomplished by controlling the development of secondary flows within the duct through the use of tapered-fin type vortex generators. Reported are results for the bare duct and seven different configurations of vortex generators. Data presented for each configuration include surface static pressure, surface flow visualization, and exit plane total pressure and transverse velocity. The performance of each configuration was assessed by calculating total pressure recovery and inlet distortion descriptors from the data and comparing them to the values for the bare duct. The best configuration tested reduced distortion (as measured by the DC(45) and DC(90) descriptors) by more than 50 percent while improving total pressure recovery by 0.5 percent. These results should provide valuable guidance in designing vortex generator installations in ducts and for assessing the accuracy of computational fluid dynamics (CFD) methods to calculate duct flows with installed vortex generators.

  15. WAVE PROPAGATION in the HOT DUCT of VHTR

    Energy Technology Data Exchange (ETDEWEB)

    Richard Schultz; Jim C. P. Liou

    2013-07-01

    In VHTR, helium from the reactor vessel is conveyed to a power conversion unit through a hot duct. In a hypothesized Depressurized Conduction Cooldown event where a rupture of the hot duct occurs, pressure waves will be initiated and reverberate in the hot duct. A numerical model is developed to quantify the transients and the helium mass flux through the rupture for such events. The flow path of the helium forms a closed loop but only the hot duct is modeled in this study. The lower plum of the reactor vessel and the steam generator are treated as specified pressure and/or temperature boundary to the hot duct. The model is based on the conservation principles of mass, momentum and energy, and on the equations of state for helium. The numerical solution is based on the method of characteristics with specified time intervals with a predictor and corrector algorithm. The rupture sub-model gives reasonable results. Transients induced by ruptures with break area equaling 20%, 10%, and 5% of the duct cross-sectional area are described.

  16. Flow control in a diffusing S-Duct

    Science.gov (United States)

    Vakili, A. D.; Wu, J. M.; Liver, P.; Bhat, M. K.

    1985-01-01

    Accurate measurements have been made of secondary flow in a 1.51 area ratio diffusing 30 deg - 30 deg S-Duct with circulair cross section. Turbulent flow was entering the duct at Mach number of 0.6, the boundary layer thickness at the duct entrance was ten percent of the duct inlet diameter. Through measurements made, local flow velocity vector as well as static and total pressures mapping of the flow at several stations were obtained. Strong secondary flow was measured in the first bend which continued into the second bend with new vorticity produced in there in the opposite direction. Surface oil flow visualization and wall pressures indicated a region of separated flow starting at theta approximately equal to 22 deg on the inside of the first bend up to theta approximately equal to 44 deg on the outside of the second bend. The flow separated in 'cyclone' form and never reattached in the duct. As a result of the secondary flow and the flow separation, significant total pressure distortion was observed at the exit of the duct. Using flow control devices the separation was eliminated while the exit distortion was improved.

  17. Panspermia and horizontal gene transfer

    Science.gov (United States)

    Klyce, Brig

    2009-08-01

    Evidence that extremophiles are hardy and ubiquitous is helping to make panspermia a respectable theory. But even if life on Earth originally came from space, biologists assume that the subsequent evolution of life is still governed by the darwinian paradigm. In this review we show how panspermia could amend darwinism and point to a cosmic source for, not only extremophiles but, all of life. This version of panspermia can be called "strong panspermia." To support this theory we will discuss recent evidence pertaining to horizontal gene transfer, viruses, genes apparently older than the Earthly evolution of the features they encode, and primate-specific genes without identifiable precursors.

  18. Measure Guideline: Summary of Interior Ducts in New Construction, Including an Efficient, Affordable Method to Install Fur-Down Interior Ducts

    Energy Technology Data Exchange (ETDEWEB)

    Beal, D. [BA-PIRC, Cocoa, FL (United States); McIlvaine, J. [BA-PIRC, Cocoa, FL (United States); Fonorow, K. [BA-PIRC, Cocoa, FL (United States); Martin, E. [BA-PIRC, Cocoa, FL (United States)

    2011-11-01

    This document illustrates guidelines for the efficient installation of interior duct systems in new housing, including the fur-up chase method, the fur-down chase method, and interior ducts positioned in sealed attics or sealed crawl spaces.

  19. Traumatic resin ducts in Larix decidua stems impacted by debris flows.

    Science.gov (United States)

    Bollschweiler, Michelle; Stoffel, Markus; Schneuwly, Dominique M; Bourqui, Karin

    2008-02-01

    Following mechanical injury, stems of many conifers produce tangential rows of traumatic resin ducts (TRDs), the distribution of which has been used to date geomorphic events. However, little is known about how far TRD formation extends tangentially and axially from the point of injury or what the time course of TRD appearance is. We analyzed 28 injuries in eight Larix decidua Mill. tree stems resulting from debris flows in October 2000 and November 2004. Injuries occurred outside the period of cambial activity, and TRD formation occurred in the first layers of the growth ring formed in the year following that of injury. The axial extent of TRD formation averaged 74 cm and was greater above the injury than below it. At the height of the wound center, TRDs extended horizontally to a mean of 18% of the stem circumference excluding that portion where the cambium had been destroyed. In subsequent growth rings, TRDs, if present, were confined mainly to the height of the center of injury. Both the vertical and horizontal extent of TRD formation was related to the injury size. Within growth rings, the position of TRD formation changed with increasing distance from the wound progressing from early earlywood to later portions of the growth ring.

  20. Horizontal gene transfer in chromalveolates

    Directory of Open Access Journals (Sweden)

    Bhattacharya Debashish

    2007-09-01

    Full Text Available Abstract Background Horizontal gene transfer (HGT, the non-genealogical transfer of genetic material between different organisms, is considered a potentially important mechanism of genome evolution in eukaryotes. Using phylogenomic analyses of expressed sequence tag (EST data generated from a clonal cell line of a free living dinoflagellate alga Karenia brevis, we investigated the impact of HGT on genome evolution in unicellular chromalveolate protists. Results We identified 16 proteins that have originated in chromalveolates through ancient HGTs before the divergence of the genera Karenia and Karlodinium and one protein that was derived through a more recent HGT. Detailed analysis of the phylogeny and distribution of identified proteins demonstrates that eight have resulted from independent HGTs in several eukaryotic lineages. Conclusion Recurring intra- and interdomain gene exchange provides an important source of genetic novelty not only in parasitic taxa as previously demonstrated but as we show here, also in free-living protists. Investigating the tempo and mode of evolution of horizontally transferred genes in protists will therefore advance our understanding of mechanisms of adaptation in eukaryotes.

  1. A fixed point theorem for uniformly locally contractive mappings in a C-chainable cone rectangular metric space

    Directory of Open Access Journals (Sweden)

    Bessem Samet

    2011-09-01

    Full Text Available Recently, Azam, Arshad and Beg [ Banach contraction principle on cone rectangular metric spaces, Appl. Anal. Discrete Math. 2009] introduced the notion of cone rectangular metric spaces by replacing the triangular inequality of a cone metric space by a rectangular inequality. In this paper, we introduce the notion of c-chainable cone rectangular metric space and we establish a fixed point theorem for uniformly locally contractive mappings in such spaces. An example is given to illustrate our obtained result.

  2. Anisometropia and amblyopia in nasolacrimal duct obstruction.

    Science.gov (United States)

    Kipp, Michael A; Kipp, Michael A; Struthers, William

    2013-06-01

    To investigate an association of childhood nasolacrimal duct obstruction (NLDO) with anisometropia and amblyopia. The medical records of patients from newborn to 6 years of age with a diagnosis of NLDO seen from 2000 to 2010 were retrospectively reviewed. Data collected included age at onset of NLDO, laterality of NLDO, cycloplegic refractive error, determination of clinically significant anisometropia (defined as ≥1 D), and diagnosis of amblyopia with amblyopia subtype (anisometropic vs other). A total of 1,218 patients with NLDO were included. Of these, 887 cases (72.8%) were unilateral; 331 (27.2%), bilateral. Anisometropia was found in 67 (7.6%) unilateral cases and 12 (3.6 %) bilateral cases on initial examination (χ2=5.48, P anisometropia patients (χ(2) = 33.01, P anisometropia for a total of 105 of 1218 (8.6%). Of the 482 patients, 28 (5.8%) developed amblyopia, 16 cases of which were purely attributable to anisometropia. Of 41 patients with anisometropia who were in the follow-up, 9 (22%) developed amblyopia. Anisometropia occurred at a greater rate in unilateral NLDO patients compared with bilateral NLDO patients and occurred at a greater rate in this NLDO cohort than expected in the general pediatric population. Several patients with anisometropia developed clinical amblyopia. Measurement of cycloplegic refraction in all NLDO patients at initial examination should be considered. Periodic follow-up is appropriate for patients with NLDO and anisometropia. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

  3. Ejaculatory duct obstruction in infertile men.

    Science.gov (United States)

    Paick, J; Kim, S H; Kim, S W

    2000-04-01

    To analyse our experience of ejaculatory duct obstruction (EDO) in infertile men, evaluating the diagnostic steps and the outcome of management according to the aetiology. Over a 7-year period, 50 infertile men were diagnosed with EDO as a contributory factor to male infertility. Diagnostic criteria included a history, physical examination, semen analyses, semen fructose measurement, hormonal study, testicular biopsy, transrectal ultrasonography (TRUS) and/or vasography. Thirty-one patients with EDO were treated by transurethral resection (26) or forced lavage via a vasotomy (five). In 45 of the 50 men, semen analyses showed the typical characteristics of complete EDO. Seminal values were variable in five cases of partial EDO; the semen fructose levels were EDO was a midline cyst in 16, Wolffian malformation in four, tuberculosis in 17, previous genitourinary infection in five and idiopathic in eight men. In 17 patients the seminal vesicles appeared to be atrophied on TRUS; 15 of these patients had a history of pulmonary tuberculosis and subsequent vasography in five showed multiple bilateral vasal obstruction. TRUS findings correlated well with vasography except in one case. The overall rate of improved semen values and paternity was 61% and 26%, respectively. Of 16 patients with midline cysts, 14 had improved semen variables and achieved paternity, seven after transurethral resection. TRUS should be the first diagnostic procedure used when infertile men are suspected of having EDO, but vasography should still be considered for a more comprehensive diagnosis. In patients with atrophic seminal vesicles on TRUS and with a history of pulmonary tuberculosis, further study is unnecessary and microscopic epididymal sperm aspiration is recommended for in vitro fertilization. The measurement of semen fructose may be helpful in diagnosing partial EDO. Patients with midline cysts who are treated by transurethral resection are expected to have the best outcome.

  4. 77 FR 1915 - Light-Walled Rectangular Pipe and Tube From Mexico; Final Results of Antidumping Duty...

    Science.gov (United States)

    2012-01-12

    ... Rectangular Pipe and Tube from Mexico'' from Christian Marsh, Deputy Assistant Secretary for Antidumping and... International Trade Administration Light-Walled Rectangular Pipe and Tube From Mexico; Final Results of... antidumping duty order on light-walled rectangular pipe and tube from Mexico.\\1\\ This administrative review...

  5. Parametric study of electromagnetic waves propagating in absorbing curved S ducts

    Science.gov (United States)

    Baumeister, Kenneth J.

    1989-01-01

    A finite-element Galerkin formulation has been developed to study attenuation of transverse magnetic (TM) waves propagating in two-dimensional S-curved ducts with absorbing walls. In the frequency range where the duct diameter and electromagnetic wave length are nearly equal, the effect of duct length, curvature (duct offset), and absorber wall thickness was examined. For a given offset in the curved duct, the length of the S-duct was found to significantly affect both the absorptive and reflective characteristics of the duct. For a straight and a curved duct with perfect electric conductor terminations, power attenuation contours were examined to determine electromagnetic wall properties associated with maximum input signal absorption. Offset of the S-duct was found to significantly affect the value of the wall permittivity associated with the optimal attenuation of the incident electromagnetic wave.

  6. Horizontal gene transfer in choanoflagellates.

    Science.gov (United States)

    Tucker, Richard P

    2013-01-01

    Horizontal gene transfer (HGT), also known as lateral gene transfer, results in the rapid acquisition of genes from another organism. HGT has long been known to be a driving force in speciation in prokaryotes, and there is evidence for HGT from symbiotic and infectious bacteria to metazoans, as well as from protists to bacteria. Recently, it has become clear that as many as a 1,000 genes in the genome of the choanoflagellate Monosiga brevicollis may have been acquired by HGT. Interestingly, these genes reportedly come from algae, bacteria, and other choanoflagellate prey. Some of these genes appear to have allowed an ancestral choanoflagellate to exploit nutrient-poor environments and were not passed on to metazoan descendents. However, some of these genes are also found in animal genomes, suggesting that HGT into a common ancestor of choanozoans and animals may have contributed to metazoan evolution. Copyright © 2012 Wiley Periodicals, Inc.

  7. Hue geometry and horizontal connections.

    Science.gov (United States)

    Ben-Shahar, Ohad; Zucker, Steven W

    2004-01-01

    Primate visual systems support an elaborate specialization for processing color information. Concentrating on the hue component, we observe that, contrary to Mondrian-like assumptions, hue varies in a smooth manner for ecologically important natural imagery. To represent these smooth variations, and to support those information processing tasks that utilize hue, a piecewise smooth hue field is postulated. The geometry of hue-patch interactions is developed analogously to orientation-patch interactions in texture. The result is a model for long-range (horizontal) interactions in the color domain, the power of which is demonstrated on a number of examples. Implications for computer image processing, computer vision, visual neurophysiology and psychophysics are discussed.

  8. Explorando nuevos horizontes en NASA

    Science.gov (United States)

    Villanueva, G. L.

    A pesar de la incesante expansión del Universo iniciada con el Big Bang 14 mil millones de años atrás, nuestro Universo se siente cada día más cercano. La inquebrantable vocación de la humanidad por descubrir nuevos horizontes ha permitido el acercamiento de civilizaciones en nuestro planeta y nos ha permitido conocer nuestro lugar en el Universo como nunca antes. En este artículo presento una breve sinopsis de nuestro trabajo que se relaciona con diversas investigaciones con implicaciones astrobiológicas, desde el origen de los ingredientes de la "sopa de la vida", hasta la evolución y composición de la atmósfera de Marte.

  9. The Effects of Vortex Ingestion on the Flow in a Diffusing S-duct

    Science.gov (United States)

    Wendt, B. J.; Reichert, B. A.

    1994-01-01

    An experimental study of the effects of an ingested vortex on the flowfield of a diffusing S-duct is reported. The vortex is generated through the use of a stationary pinwheel device mounted upstream of the diffusing S-duct. Three test conditions vary the location of the vortex in the duct inlet crossplane. For each condition of ingested vortex, a baseline S-duct and an S-duct with an array of vortex generators is examined. The data taken consist of duct inlet and exit crossplane surveys of velocity and total pressure. Duct surface flow visualization and static pressure are also recorded. The data acquired in these tests are compared to identical S-duct data taken in the absence of the ingested vortex. The ingested vortex is observed to have a strong influence on the flowfield inside (and exiting) the S-duct, but only when the vortex impinges at the inlet crossplane location coincident with the crossplane location of downstream flow separation within the duct. When the ingested vortex impinges at this location it reduces the extent of flowfield separation inside the baseline duct and promotes stronger crossflow in the exit plane of both the baseline duct and the duct with installed vortex generators. This enhanced crossflow also strengthens the vortices shed from the vortex generators. The other impingement locations of the ingested vortex are found to produce little effect on the flowfield of the duct with or without vortex generators.

  10. Optimum design of the injection duct system of a stenter machine

    Energy Technology Data Exchange (ETDEWEB)

    Juraeva, Makhsuda; Song, Dong Joo [Yeungnam University, Geyongsan (Korea, Republic of); Ryu, Kyung Jin [Ajou Motor College, Boryeong (Korea, Republic of)

    2017-05-15

    Stenter machines are used for drying fabrics in the textile industry and have a heater, injection duct system, and fans inside a chamber. The injection duct system has ducts and air-injecting holes. Plane-type injection duct systems were investigated to obtain uniform airflow at the air-injecting holes. The flow field of the injection duct systems was computed using ANSYS CFX with different heights of the duct end and different shapes for the air-injecting holes. There was a high mass flow rate at the air-injecting holes and high airflow circulation inside both plane-type and mountain-type ducts at the ends. The height of the duct end was varied between 40 mm and 160 mm. The injection duct systems were analyzed with four different shapes of air-injecting holes. The circular and elliptical holes had lower standard deviations of the mass flow rate than other shapes. Relatively uniform mass flow rates were obtained in the plane-type and mountain-type duct systems when the height of the duct end was 40 mm and the shape of the air-injecting holes was circular or elliptical. The developed injection duct systems were improved by obtaining a uniform mass flow rate at the air-injecting holes. A stenter prototype was fabricated with the developed injection duct system to confirm the numerical results. The developed injection duct system had better performance than the original system.

  11. Technical Note: Thoracic duct embolization for treatment of chylothorax: A novel guidance technique for puncture using combined MRI and fluoroscopy

    Directory of Open Access Journals (Sweden)

    Alampath Praveen

    2012-01-01

    Full Text Available Thoracic duct embolization (TDE is an established radiological interventional procedure for thoracic duct injuries. Traditionally, it is done under fluoroscopic guidance after opacifying the thoracic duct with bipedal lymphangiography. We describe our experience in usinga heavily T2W sequence for guiding thoracic duct puncture and direct injection of glue through the puncture needle without cannulating the duct.

  12. Trastuzumab in Treating Patients With Locally Advanced or Metastatic Gallbladder Cancer or Bile Duct Cancer That Cannot Be Removed by Surgery

    Science.gov (United States)

    2014-05-15

    Adenocarcinoma of the Extrahepatic Bile Duct; Adenocarcinoma of the Gallbladder; Malignant Neoplasm; Recurrent Extrahepatic Bile Duct Cancer; Recurrent Gallbladder Cancer; Unresectable Extrahepatic Bile Duct Cancer; Unresectable Gallbladder Cancer

  13. Support device in a pressure vessel, particularly a reactor pressure vessel, to support against horizontal forces. Abstuetzeinrichtung an einem Druckbehaelter, insbesondere einem Reaktordruckbehaelter, gegen Horizontalkraefte

    Energy Technology Data Exchange (ETDEWEB)

    Dorner, H.; Harand, E.; Scholz, M.; Scheler, R.

    1986-04-17

    In a support device on a reactor pressure vessel of a PWR, a guide leading downwards is provided in the vertical pellet cartridge on the floor side of the reactor pressure vessel, which is located in a fixed support pipe. The support pipe is supported on a concreted baseplate in the horizontal direction, and can be screwed to this. The support pipe has a plate-shaped support foot to support it on the baseplate. The reactor pressure vessel, normally resting on its main coolant duct in the plane normal to the axis, can be effectively supported against horizontal forces by this additional support, without preventing thermal movement in the longitudinal axis.

  14. Does salivary duct repositioning prevent complications after tumor resection or salivary gland surgery?

    Science.gov (United States)

    Sakakibara, Akiko; Minamikawa, Tsutomu; Hashikawa, Kazunobu; Sakakibara, Shunsuke; Hasegawa, Takumi; Akashi, Masaya; Furudoi, Shungo; Komori, Takahide

    2015-05-01

    Tissue that is resected for the treatment of oral tumors often includes salivary gland ducts. At their institution, the authors conserve and transfer as much of the salivary duct as possible during these procedures to avoid obstructive complications. Differentiating these obstructive complications from a metastatic node can be challenging and can confound subsequent oncologic management. This study compared and examined the effectiveness of salivary duct repositioning in decreasing the incidence of obstructive complications. Cases of oromandibular disease treated with salivary duct resection at Kobe University Graduate School of Medicine from 2008 to 2013 were retrospectively analyzed. Thirty-two cases (25 patients) of Wharton duct resection and 31 cases (31 patients) of Stensen duct resection were included. The incidence of complications after salivary duct repositioning, duct ligation, and retention of the sublingual gland around the Wharton duct was compared. Wharton ducts were repositioned in 30 cases and ligated in 2 cases. Complications, including oral swelling at the Wharton duct, were observed in 5 cases of repositioning and 2 cases of ligation. Stensen ducts were repositioned in 9 cases and ligated in 22 cases. The only complication reported was a single case of salivary fistula after ligation. Salivary duct repositioning is performed to prevent blockage of physiologic salivary discharge. Complications were more frequently associated with Wharton ducts than with Stensen ducts because of the unique physiologic and anatomic characteristics of the Wharton duct. Repositioning of the salivary duct is a suitable method for preventing complications associated with the Wharton duct. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  15. Recurrence of choledocholithiasis following endoscopic bile duct clearance: Long term results and factors associated with recurrent bile duct stones.

    Science.gov (United States)

    Konstantakis, Christos; Triantos, Christos; Theopistos, Vasileios; Theocharis, Georgios; Maroulis, Ioannis; Diamantopoulou, Georgia; Thomopoulos, Konstantinos

    2017-01-16

    To evaluate the rate of recurrence of symptomatic choledocholithiasis and identify factors associated with the recurrence of bile duct stones in patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (EST) for bile duct stone disease. All patients who underwent ERCP and EST for bile duct stone disease and had their bile duct cleared from 1/1/2005 until 31/12/2008 was enrolled. All symptomatic recurrences during the study period (until 31/12/2015) were recorded. Clinical and laboratory data potentially associated with common bile duct (CBD) stone recurrence were retrospectively retrieved from patients' files. A total of 495 patients were included. Sixty seven (67) out of 495 patients (13.5%) presented with recurrent symptomatic choledocholithiasis after 35.28 ± 16.9 mo while twenty two (22) of these patients (32.8%) experienced a second recurrence after 35.19 ± 23.2 mo. Factors associated with recurrence were size (diameter) of the largest CBD stone found at first presentation (10.2 ± 6.9 mm vs 7.2 ± 4.1 mm, P = 0.024), diameter of the CBD at the first examination (15.5 ± 6.3 mm vs 12.0 ± 4.6 mm, P = 0.005), use of mechanical lithotripsy (ML) (P = 0.04) and presence of difficult lithiasis (P = 0.04). Periampullary diverticula showed a trend towards significance (P = 0.066). On the contrary, number of stones, angulation of the CBD, number of ERCP sessions required to clear the CBD at first presentation, more than one ERCP session needed to clear the bile duct initially and a gallbladder in situ did not influence recurrence. Bile duct stone recurrence is a possible late complication following endoscopic stone extraction and CBD clearance. It appears to be associated with anatomical parameters (CBD diameter) and stone characteristics (stone size, use of ML, difficult lithiasis) at first presentation.

  16. Efficient computation of coherent synchrotron radiation in a rectangular chamber

    Directory of Open Access Journals (Sweden)

    Robert L. Warnock

    2016-09-01

    Full Text Available We study coherent synchrotron radiation (CSR in a perfectly conducting vacuum chamber of rectangular cross section, in a formalism allowing an arbitrary sequence of bends and straight sections. We apply the paraxial method in the frequency domain, with a Fourier development in the vertical coordinate but with no other mode expansions. A line charge source is handled numerically by a new method that rids the equations of singularities through a change of dependent variable. The resulting algorithm is fast compared to earlier methods, works for short bunches with complicated structure, and yields all six field components at any space-time point. As an example we compute the tangential magnetic field at the walls. From that one can make a perturbative treatment of the Poynting flux to estimate the energy deposited in resistive walls. The calculation was motivated by a design issue for LCLS-II, the question of how much wall heating from CSR occurs in the last bend of a bunch compressor and the following straight section. Working with a realistic longitudinal bunch form of r.m.s. length 10.4  μm and a charge of 100 pC we conclude that the radiated power is quite small (28 W at a 1 MHz repetition rate, and all radiated energy is absorbed in the walls within 7 m along the straight section.

  17. Instability of Flow Over a Periodic Array of Rectangular Cylinders

    Science.gov (United States)

    Parker, Scott; Balachandar, S.

    1999-11-01

    Arrays of rectangular cylinders represent a simplified model of the geometry seen in many industrial heat exchangers. Flow in such geometries is governed by the interaction of multiple bluff body wakes, and exhibits greater complexity than flow over a single body. The present work examines array flow using a specialized multi-domain spectral element code. Through stability analysis the present study characterizes the onset of wake instability in these array types, for which the critical Reynolds number, shedding frequency, and eigenfunction have been determined. These results are compared with those of an isolated body in order to demonstrate the effects of array geometry on vortex shedding and heat transfer. The generation of surface vortices from the leading edge of an object in an array is shown to be a feature of the wake instability of upstream objects. The dynamics of the non-linear saturation of the wake instability and the generation of surface vortices are examined. The results of the use of oscillating flow to amplify the wake instability are discussed in terms of its impact on the critical Reynolds number, nonlinear saturation, and surface vortex generation.

  18. Compressibility effects in the shear layer over a rectangular cavity

    Energy Technology Data Exchange (ETDEWEB)

    Beresh, Steven J.; Wagner, Justin; Casper, Katya Marie

    2016-10-26

    we studied the influence of compressibility on the shear layer over a rectangular cavity of variable width in a free stream Mach number range of 0.6–2.5 using particle image velocimetry data in the streamwise centre plane. As the Mach number increases, the vertical component of the turbulence intensity diminishes modestly in the widest cavity, but the two narrower cavities show a more substantial drop in all three components as well as the turbulent shear stress. Furthermore, this contrasts with canonical free shear layers, which show significant reductions in only the vertical component and the turbulent shear stress due to compressibility. The vorticity thickness of the cavity shear layer grows rapidly as it initially develops, then transitions to a slower growth rate once its instability saturates. When normalized by their estimated incompressible values, the growth rates prior to saturation display the classic compressibility effect of suppression as the convective Mach number rises, in excellent agreement with comparable free shear layer data. The specific trend of the reduction in growth rate due to compressibility is modified by the cavity width.

  19. Parametric analysis of laminar pulsating flow in a rectangular channel

    Science.gov (United States)

    Blythman, Richard; Alimohammadi, Sajad; Persoons, Tim; Jeffers, Nick; Murray, Darina B.

    2017-10-01

    Pulsating flow has potential for enhanced cooling of future electronics and photonics systems. To better understand the mechanisms underlying any heat transfer enhancement, it is necessary to decouple the mechanical and thermal problems. The current work performs a parametric analysis of the flow hydrodynamics using particle image velocimetry (PIV) measurements, CFD simulations and analytical solutions, reorganised in terms of amplitude and phase values using complex notation. To the best of the authors' knowledge, the frequency-dependent behaviour of amplitude and phase of wall shear stress has not been studied in a two-dimensional channel. For laminar flow, the amplitudes are directly proportional to pressure. The amplitudes of various local and mean wall shear stress measures are augmented with frequency compared to steady flow, especially near the short walls and corners. The phases of wall shear stress differ at each wall at moderate frequencies - with the bulk-mean values at the short wall leading those at the long wall - and tend to π/4 in the limit of high frequency. The amplitudes of pressure gradient increase more significantly than wall shear stress magnitudes due to accelerative forces. The boundaries to the quasi-steady, intermediate and inertia-dominated regimes are estimated at Womersley number W o = 1.6 and 27.6 in a rectangular channel, based on the contribution of viscous and inertial terms.

  20. Capacitive micromachined ultrasonic Lamb wave transducers using rectangular membranes.

    Science.gov (United States)

    Badi, Mohammed H; Yaralioglu, Goksen G; Ergun, A Sanli; Hansen, Sean T; Wong, Eehern J; Khuri-Yakub, Butrus T

    2003-09-01

    This paper details the theory, fabrication, and characterization of a new Lamb wave device. Built using capacitive micromachined ultrasonic transducers (CMUTs), the structure described uses rectangular membranes to excite and receive Lamb waves on a silicon substrate. An equivalent circuit model for the transducer is proposed that produces results, which match well with those observed by experiment. During the derivation of this model, emphasis is placed on the resistance presented to the transducer membranes by the Lamb wave modes. Finite element analysis performed in this effort shows that the dominant propagating mode in the device is the lowest order antisymmetric flexural wave (A0). Furthermore, most of the power that couples into the Lamb wave is due to energy in the vibrating membrane that is transferred to the substrate through the supporting posts of the device. The manufacturing process of the structure, which relies solely on fundamental IC-fabrication techniques, is also discussed. The resulting device has an 18-microm-thick substrate that is almost entirely made up of crystalline silicon and operates at a frequency of 2.1 MHz. The characterization of this device includes S-parameter and laser vibrometer measurements as well as delay-line transmission data. The insertion loss, as determined by both S-parameter and delay-line transmission measurements, is 20 dB at 2.1 MHz. When configured as a delay-line oscillator, the device functions well as a sensor with sensitivity to changes in the mass loading of its substrate.

  1. Products of rectangular random matrices: Singular values and progressive scattering

    Science.gov (United States)

    Akemann, Gernot; Ipsen, Jesper R.; Kieburg, Mario

    2013-11-01

    We discuss the product of M rectangular random matrices with independent Gaussian entries, which have several applications, including wireless telecommunication and econophysics. For complex matrices an explicit expression for the joint probability density function is obtained using the Harish-Chandra-Itzykson-Zuber integration formula. Explicit expressions for all correlation functions and moments for finite matrix sizes are obtained using a two-matrix model and the method of biorthogonal polynomials. This generalizes the classical result for the so-called Wishart-Laguerre Gaussian unitary ensemble (or chiral unitary ensemble) at M=1, and previous results for the product of square matrices. The correlation functions are given by a determinantal point process, where the kernel can be expressed in terms of Meijer G-functions. We compare the results with numerical simulations and known results for the macroscopic level density in the limit of large matrices. The location of the end points of support for the latter are analyzed in detail for general M. Finally, we consider the so-called ergodic mutual information, which gives an upper bound for the spectral efficiency of a MIMO communication channel with multifold scattering.

  2. Single-channel noise reduction using optimal rectangular filtering matrices.

    Science.gov (United States)

    Long, Tao; Chen, Jingdong; Benesty, Jacob; Zhang, Zhenxi

    2013-02-01

    This paper studies the problem of single-channel noise reduction in the time domain and presents a block-based approach where a vector of the desired speech signal is recovered by filtering a frame of the noisy signal with a rectangular filtering matrix. With this formulation, the noise reduction problem becomes one of estimating an optimal filtering matrix. To achieve such estimation, a method is introduced to decompose a frame of the clean speech signal into two orthogonal components: One correlated and the other uncorrelated with the current desired speech vector to be estimated. Different optimization cost functions are then formulated from which non-causal optimal filtering matrices are derived. The relationships among these optimal filtering matrices are discussed. In comparison with the classical sample-based technique that uses only forward prediction, the block-based method presented in this paper exploits both the forward and backward prediction as well as the temporal interpolation and, therefore, can improve the noise reduction performance by fully taking advantage of the speech property of self correlation. There is also a side advantage of this block-based method as compared to the sample-based technique, i.e., it is computationally more efficient and, as a result, more suitable for practical implementation.

  3. Swirling Strength Vortex Study in Confined Rectangular Jet

    Science.gov (United States)

    Kong, Bo; Olsen, Michael; Fox, Rodney; Hill, James

    2009-11-01

    Vortex behavior in confined rectangular jet (Re = 20K, Re = 50K) were examined by using vortex swirling strength as a defining characteristic. Instantaneous velocity fields were collected for by using Particle Image Velocimetry(PIV). Swirling strength fields were calculated from velocity fields, and then filtered with a universal threshold of 1.5 times of swirling strength RMS value. By identifying clusters in filtered swirling strength fields, vortex structures were defined. Both instantaneous swirling strength field data and vortex population calculation indicate that the positively (counterclockwise) rotating vortices are dominant on the left side of the jet, and negatively (clockwise) rotating vortices are dominant on the right side. As flow develops further downstream, vortex population decreases and the flow approach channel flow. At the locations of the left peak of turbulent kinetic energy, two point spatial cross-correlation of swirling strength with velocity fluctuation were calculated. Linear stochastic estimation was also used to interpret the spatial correlation results and to determine conditional flow structures. High speed PIV data were also analyzed by using swirling strength technique to trace development of vortices. Vortex trajectories were found by tracing individual swirling strength clusters. The speed and strength of individual vortex were also studied by using this method.

  4. Attenuation in Rectangular Waveguides with Finite Conductivity Walls

    Directory of Open Access Journals (Sweden)

    K. C. Yeong

    2011-06-01

    Full Text Available We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E and the magnetic field (H at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.

  5. Diversity of acoustic streaming in a rectangular acoustofluidic field.

    Science.gov (United States)

    Tang, Qiang; Hu, Junhui

    2015-04-01

    Diversity of acoustic streaming field in a 2D rectangular chamber with a traveling wave and using water as the acoustic medium is numerically investigated by the finite element method. It is found that the working frequency, the vibration excitation source length, and the distance and phase difference between two separated symmetric vibration excitation sources can cause the diversity in the acoustic streaming pattern. It is also found that a small object in the acoustic field results in an additional eddy, and affects the eddy size in the acoustic streaming field. In addition, the computation results show that with an increase of the acoustic medium's temperature, the speed of the main acoustic streaming decreases first and then increases, and the angular velocity of the corner eddies increases monotonously, which can be clearly explained by the change of the acoustic dissipation factor and shearing viscosity of the acoustic medium with temperature. Commercialized FEM software COMSOL Multiphysics is used to implement the computation tasks, which makes our method very easy to use. And the computation method is partially verified by an established analytical solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Permuting sparse rectangular matrices into block-diagonal form

    Energy Technology Data Exchange (ETDEWEB)

    Aykanat, Cevdet; Pinar, Ali; Catalyurek, Umit V.

    2002-12-09

    This work investigates the problem of permuting a sparse rectangular matrix into block diagonal form. Block diagonal form of a matrix grants an inherent parallelism for the solution of the deriving problem, as recently investigated in the context of mathematical programming, LU factorization and QR factorization. We propose graph and hypergraph models to represent the nonzero structure of a matrix, which reduce the permutation problem to those of graph partitioning by vertex separator and hypergraph partitioning, respectively. Besides proposing the models to represent sparse matrices and investigating related combinatorial problems, we provide a detailed survey of relevant literature to bridge the gap between different societies, investigate existing techniques for partitioning and propose new ones, and finally present a thorough empirical study of these techniques. Our experiments on a wide range of matrices, using state-of-the-art graph and hypergraph partitioning tools MeTiS and PaT oH, revealed that the proposed methods yield very effective solutions both in terms of solution quality and run time.

  7. Technical Performance of Universal and Enhanced Intraoral Imaging Rectangular Collimators.

    Science.gov (United States)

    Johnson, K Brandon; Mauriello, Sally M; Ludlow, John B; Platin, Enrique

    2015-08-01

    The purpose of this study was to compare the number and type of technical errors between 2 rectangular collimators, time/motion effort and radiographer preference. Subjects (n=17) were recruited to expose an 18 projection full mouth series (FMX) using Tru-Align™ (enhanced) and Rinn® (universal) collimator devices. Both FMXs were exposed using photostimulable phosphor (PSP) digital sensors on a DXTTR manikin with an intraoral x-ray unit. A 5-question survey evaluated ease of device use, time required and device preference. Data were analyzed using frequencies, paired t-test, ANOVA and least squares means using a general linear model. A lower mean number of technique errors per FMX occurred with the enhanced device (9.7) compared to the universal device (12.1). Collimator centering errors occurred 3-times more often with the universal device. The mean numbers of diagnostically unacceptable errors per FMX were similar (Universal=3.2 vs Enhanced=2.9). The least squares means adjusted model showed a statistically significant difference of errors between the 2 devices (p=0.0478) and errors by location when comparing posterior to anterior and posterior to bitewing (pradiographs more efficiently with fewer collimator centering errors; however, it does so with a 35% greater exposure area and a concomitant increase in patient dose. Copyright © 2015 The American Dental Hygienists’ Association.

  8. Investigations of a building-integrated ducted wind turbine module

    Science.gov (United States)

    Dannecker, Robert K. W.; Grant, Andrew D.

    2002-01-01

    So far, wind energy has not played a major role in the group of technologies for embedded generation in the built environment. However, the wind flow around conventional tall buildings generates differential pressures, which may cause an enhanced mass flow through a building-integrated turbine. As a first step, a prototype of a small-scale ducted wind turbine has been developed and tested, which seems to be feasible for integration into the leading roof edge of such a building. Here an experimental and numerical investigation of the flow through building-integrated ducting is presented. Pressure and wind speed measurements have been carried out on a wind tunnel model at different angles of incident wind, and different duct configurations have been tested. It was confirmed that wind speeds up to 30% higher than in the approaching freestream may be induced in the duct, and good performance was obtained for angles of incident wind up to ±60°. The experimental work proceeded in parallel with computational fluid dynamics (CFD) modelling. The geometry of the system was difficult to represent to the required level of accuracy, and modelling was restricted to a few simple cases, for which the flow field in the building-integrated duct was compared with experimental results. Generally good agreement was obtained, indicating that CFD techniques could play a major role in the design process. Predicted power of the proposed device suggests that it will compare favourably with conventional small wind turbines and photovoltaics in an urban environment.

  9. High-Performance Ducts in Hot-Dry Climates

    Energy Technology Data Exchange (ETDEWEB)

    Hoeschele, Marc [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chitwood, Rick [National Renewable Energy Laboratory (NREL), Golden, CO (United States); German, Alea [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Weitzel, Elizabeth [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-07-30

    Duct thermal losses and air leakage have long been recognized as prime culprits in the degradation of heating, ventilating, and air-conditioning (HVAC) system efficiency. Both the U.S. Department of Energy’s Zero Energy Ready Home program and California’s proposed 2016 Title 24 Residential Energy Efficiency Standards require that ducts be installed within conditioned space or that other measures be taken to provide similar improvements in delivery effectiveness (DE). Pacific Gas & Electric Company commissioned a study to evaluate ducts in conditioned space and high-performance attics (HPAs) in support of the proposed codes and standards enhancements included in California’s 2016 Title 24 Residential Energy Efficiency Standards. The goal was to work with a select group of builders to design and install high-performance duct (HPD) systems, such as ducts in conditioned space (DCS), in one or more of their homes and to obtain test data to verify the improvement in DE compared to standard practice. Davis Energy Group (DEG) helped select the builders and led a team that provided information about HPD strategies to them. DEG also observed the construction process, completed testing, and collected cost data.

  10. Guideline for design requirement on KALIMER driver fuel assembly duct

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Woan; Kang, H. Y.; Nam, C.; Kim, J. O.; Lim, J. S.; Ryu, W. S.; Min, B. T.; Kim, D. H.; Kim, Y. J.

    1998-01-01

    This document describes design requirements which are needs for designing the driver fuel assembly duct of the KALIMER as design guidance. The driver fuel assembly duct of the KALIMER consists of fuel rods, mounting rail, nosepiece, duct with pad, handling socket with pad. Fuel rod consists of top end plug, bottom end plug with solid ferritic-martensitic steel rod and key way, fuel slug, cladding, and wire wrap. In the assembly, the rods are in a triangular pitch array, and the rod bundle attaches to the nosepiece with mounting rails. The bottom end of the assembly duct is formed by a long nosepiece which provides the lower restraint function and the coolant inlet. It contains functional requirements, performance and operational requirements, interfacing systems requirements, core restraint and interface requirements, design limits and strength requirements, structural requirements, environmental requirements, reliability and safety requirements, standard and codes, QA programs, and other requirements. The design requirements are intended to be used for the design of the driver fuel assembly duct of the KALIMER. (author). 16 refs., 4 figs.

  11. G Plus Industrial touts new ventilation ducting product

    Energy Technology Data Exchange (ETDEWEB)

    Larmour, A.

    2010-09-01

    This article discussed a new line of industrial-strength plastic duct work for underground mine ventilation. G Plus Industrial Plastics manufactures an extensive line of industrial-strength plastic products that help solve corrosion, wear, impact, and weight problems commonly found in mining and related industries. The new ventilation ducting product is impact and corrosion resistant, and it produces better air-flow resulting in significant cost savings. Plastic helps overcome wear and corrosion problems encountered in mines, and it can be designed to be stronger than aluminum, wood, or steel because it reacts better to impact and slides better. Standard duct work for mine ventilation is either flexible vinyl cloth or sheet metal, both of which create air restriction and weaknesses causing cracks, resulting in air loss. Plastic performs better, requiring less energy to bring the same amount of air to the end point. The ducting has been in development for almost a year. With the high energy rates in Ontario, plastic ducting is expected to result in substantial cost savings. 1 fig.

  12. Ducts in the Attic? What Were They Thinking? Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.; Winkler, J.

    2010-08-01

    As energy-efficiency efforts focus increasingly on existing homes, we scratch our heads about construction decisions made 30, 40, 50-years ago and ask: 'What were they thinking?' A logical follow-on question is: 'What will folks think in 2050 about the homes we're building today?' This question can lead to a lively discussion, but the current practice that we find most alarming is placing ducts in the attic. In this paper, we explore through literature and analysis the impact duct location has on cooling load, peak demand, and energy cost in hot climates. For a typical new home in these climates, we estimate that locating ducts in attics rather than inside conditioned space increases the cooling load 0.5 to 1 ton, increases cooling costs 15% and increases demand by 0.75 kW. The aggregate demand to service duct loss in homes built in Houston, Las Vegas, and Phoenix during the period 2000 through 2009 is estimated to be 700 MW. We present options for building homes with ducts in conditioned space and demonstrate that these options compare favorably with other common approaches to achieving electricity peak demand and consumption savings in homes.

  13. Does the bile duct angulation affect recurrence of choledocholithiasis?

    Science.gov (United States)

    Seo, Dong Beom; Bang, Byoung Wook; Jeong, Seok; Lee, Don Haeng; Park, Shin Goo; Jeon, Yong Sun; Lee, Jung Il; Lee, Jin-Woo

    2011-01-01

    AIM: To investigate whether bile duct angulation and T-tube choledochostomy influence the recurrence of choledocholithiasis. METHODS: We conducted a retrospective study inclu-ding 259 patients who underwent endoscopic sphincterotomy and cholecystectomy for choledocholithiasis between 2000 and 2007. The imaginary line was drawn along the center of the bile duct and each internal angle was measured at the two angulation sites of the bile duct respectively. The values of both angles were added together. We then tested our hypothesis by examining whether T-tube choledochostomy was performed and stone recurrence occurred by reviewing each subject’s medical records. RESULTS: The overall recurrence rate was 9.3% (24 of 259 patients). The mean value of sums of angles in the recurrence group was 268.3° ± 29.6°, while that in the non-recurrence group was 314.8° ± 19.9° (P bile duct angulation and T-tube choledochostomy may be risk factors of recurrence of bile duct stones. PMID:22039327

  14. Gas reservoir evaluation for underbalanced horizontal drilling

    National Research Council Canada - National Science Library

    Li Gao; Meng Ying-Feng; Wei Na; Xu Zhao-Yang; Li Hong-Tao; Xiao Gui-Lin; Zhang Yu-Rui

    2014-01-01

    .... Based on drilling operation parameters, well structure and monitored parameters, the wellbore pressure and the gas reservoir permeability could be predicted theoretically for underbalanced horizontal drilling...

  15. Thyroid cancer in lingual thyroid and thyroglossal duct cyst.

    Science.gov (United States)

    Sturniolo, Giacomo; Vermiglio, Francesco; Moleti, Mariacarla

    2017-01-01

    Ectopy is the most common embryogenetic defect of the thyroid gland, representing between 48 and 61% of all thyroid dysgeneses. Persistence of thyroid tissue in the context of a thyroglossal duct remnant and lingual thyroid tissue are the most common defects. Although most cases of ectopic thyroid are asymptomatic, any disease affecting the thyroid may potentially involve the ectopic tissue, including malignancies. The prevalence of differentiated thyroid carcinoma in lingual thyroid and thyroglossal duct cyst is around 1% of patients affected with the above thyroid ectopies. We here review the current literature concerning primary thyroid carcinomas originating from thyroid tissue on thyroglossal duct cysts and lingual thyroid. Copyright © 2016 SEEN. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Design of a Mobile Robot for Air Ducts Exploration

    Directory of Open Access Journals (Sweden)

    Moses A. Koledoye

    2017-10-01

    Full Text Available This work presents the solutions adopted for the design and the implementation of an autonomous wheeled robot developed for the exploration and mapping of air ventilation ducts. The hardware is based on commercial off-the-shelf devices, including sensors, motors, processing devices and interfaces. The mechanical chassis was designed from scratch to meet a trade-off between small size and available volume to host the components. The software stack is based on the Robot Operating System (ROS. Special attention was dedicated to the design of the mobility strategy, which must take into account some constraints and issues that are specific to the considered application, such as the relatively small size of ducts, the need to detect and avoid possible holes on the floor of the duct and other unusual obstacles and the unavailability of external reference frameworks for localization. The main contribution of this paper lies in the design, implementation and experimentation of the overall system.

  17. Intracellular pH in rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I; Hug, M; Greger, R

    1997-01-01

    In order to study the mechanism of H+ and HCO3- transport in a HCO3- secreting epithelium, pancreatic ducts, we have measured the intracellular pH (pHi) in this tissue using the pH sensitive probe BCECF. We found that exposures of ducts to solutions containing acetate/acetic acid or NH4+/NH3...... buffers (20 mmol/l) led to pHi changes in accordance with entry of lipid-soluble forms of the buffers, followed by back-regulation of pHi by duct cells. In another type of experiment, changes in extracellular pH of solutions containing HEPES or HCO3-/CO2 buffers led to significant changes in pHi that did....... Under some conditions, these exchangers can be invoked to regulate cell pH....

  18. Endoscopic management of difficult common bile duct stones

    Science.gov (United States)

    Trikudanathan, Guru; Navaneethan, Udayakumar; Parsi, Mansour A

    2013-01-01

    Endoscopy is widely accepted as the first treatment option in the management of bile duct stones. In this review we focus on the alternative endoscopic modalities for the management of difficult common bile duct stones. Most biliary stones can be removed with an extraction balloon, extraction basket or mechanical lithotripsy after endoscopic sphincterotomy. Endoscopic papillary balloon dilation with or without endoscopic sphincterotomy or mechanical lithotripsy has been shown to be effective for management of difficult to remove bile duct stones in selected patients. Ductal clearance can be safely achieved with peroral cholangioscopy guided laser or electrohydraulic lithotripsy in most cases where other endoscopic treatment modalities have failed. Biliary stenting may be an alternative treatment option for frail and elderly patients or those with serious co morbidities. PMID:23345939

  19. Study of Relationship Between the Blood Supply of the Extrahepatic Bile Duct and Duct Supply Branches from Gastroduodenal Artery on Imaging and Anatomy

    Directory of Open Access Journals (Sweden)

    Jie Dai

    2015-01-01

    Full Text Available Background: Liver transplantation has become the treatment of choice for patients with end-stage acute or chronic hepatic disease. Bile duct complications are common events after liver transplantation. The aim of this study was to evaluate the blood supply of the human bile duct and identify the underlying mechanisms of bile duct complications after liver transplantation. Methods: The duct supply branches from gastroduodenal artery and blood supply of extrahepatic bile duct system were re-evaluated through selective hepatic angiography from 600 patients. In addition, 33 cadavers were injected with latex casting material into the common hepatic artery, then the extrahepatic bile duct and the branches from the common hepatic artery were carefully dissected to visualize the gastroduodenal artery and its branching to the extrahepatic bile duct. Results: The bile duct artery arose from the branch of the gastroduodenal artery in 8.1% (49/600. Of these 49 individuals, the bile duct artery was supplied by the gastroduodenal artery (61.22%, 30/49, the proper hepatic artery (14.29%, 7/49, or both the gastroduodenal artery and the proper hepatic artery (24.49%, 12/49. In our study of 33 cadavers, the percentage that the bile duct artery arose from the gastroduodenal artery was 27.27%. The blood supply to the bile extrahepatic bile ducts was divided into different segments and formed longitudinal and arterial network anastomosed on the walls of the duct. Conclusions: There is a close relationship between the duct supply branches from gastroduodenal artery and the blood supplying patterns of the extrahepatic bile duct system. In liver transplant surgery, the initial part of the gastroduodenal artery is preferred to be preserved in the donor liver. It is of great significance to improve the success rate of operation and reduce complications.

  20. Study of Relationship Between the Blood Supply of the Extrahepatic Bile Duct and Duct Supply Branches from Gastroduodenal Artery on Imaging and Anatomy

    Science.gov (United States)

    Dai, Jie; Wu, Xiao-Feng; Yang, Chun; Li, Hong-Jun; Chen, Ya-Liang; Liu, Guo-Zhen; Song, Yi-Zhi; Wu, Huan-Huan; Ding, Jin-Li; Li, Ning

    2015-01-01

    Background: Liver transplantation has become the treatment of choice for patients with end-stage acute or chronic hepatic disease. Bile duct complications are common events after liver transplantation. The aim of this study was to evaluate the blood supply of the human bile duct and identify the underlying mechanisms of bile duct complications after liver transplantation. Methods: The duct supply branches from gastroduodenal artery and blood supply of extrahepatic bile duct system were re-evaluated through selective hepatic angiography from 600 patients. In addition, 33 cadavers were injected with latex casting material into the common hepatic artery, then the extrahepatic bile duct and the branches from the common hepatic artery were carefully dissected to visualize the gastroduodenal artery and its branching to the extrahepatic bile duct. Results: The bile duct artery arose from the branch of the gastroduodenal artery in 8.1% (49/600). Of these 49 individuals, the bile duct artery was supplied by the gastroduodenal artery (61.22%, 30/49), the proper hepatic artery (14.29%, 7/49), or both the gastroduodenal artery and the proper hepatic artery (24.49%, 12/49). In our study of 33 cadavers, the percentage that the bile duct artery arose from the gastroduodenal artery was 27.27%. The blood supply to the bile extrahepatic bile ducts was divided into different segments and formed longitudinal and arterial network anastomosed on the walls of the duct. Conclusions: There is a close relationship between the duct supply branches from gastroduodenal artery and the blood supplying patterns of the extrahepatic bile duct system. In liver transplant surgery, the initial part of the gastroduodenal artery is preferred to be preserved in the donor liver. It is of great significance to improve the success rate of operation and reduce complications. PMID:25635427

  1. CASE STUDY OF DUCT RETROFIT OF A 1985 HOME AND GUIDELINES FOR ATTIC AND CRAWL SPACE DUCT SEALING

    Energy Technology Data Exchange (ETDEWEB)

    Boudreaux, Philip R [ORNL; Christian, Jeffrey E [ORNL; Jackson, Roderick K [ORNL

    2012-01-01

    The U.S. Department of Energy (DOE) is fully committed to research for developing the information and capabilities necessary to provide cost-effective residential retrofits yielding 50% energy savings within the next several years. Heating, ventilation, and air conditioning (HVAC) is the biggest energy end use in the residential sector, and a significant amount of energy can be wasted through leaky ductwork in unconditioned spaces such as attics and crawl spaces. A detailed duct sealing case study is presented for one house along with nine brief descriptions of other duct retrofits completed in the mixed-humid climate. Costs and estimated energy savings are reported for most of the ten houses. Costs for the retrofits ranged from $0.92/ft2 to $1.80/ft2 of living space and estimated yearly energy cost savings due to the duct retrofits range from 1.8% to 18.5%. Lessons learned and duct sealing guidelines based on these ten houses, as well as close work with the HVAC industry in the mixed-humid climate of East Tennessee, northern Georgia, and south-central Kentucky are presented. It is hoped that the lessons learned and guidelines will influence local HVAC contractors, energy auditors, and homeowners when diagnosing or repairing HVAC duct leakage and will be useful for steering DOE s future research in this area.

  2. Observationally constrained modeling of sound in curved ocean internal waves: examination of deep ducting and surface ducting at short range.

    Science.gov (United States)

    Duda, Timothy F; Lin, Ying-Tsong; Reeder, D Benjamin

    2011-09-01

    A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the shelf of the South China Sea northeast of Tung-Sha Island. Construction of the time-varying three-dimensional sound-speed fields used in the modeling simulations was guided by environmental data collected concurrently with the acoustic data. Computed three-dimensional propagation results compare well with field observations. The simulations allow identification of time-dependent sound forward scattering and ducting processes within the curved internal gravity waves. Strong acoustic intensity enhancement was observed during passage of high-amplitude nonlinear waves over the source/receiver paths, and is replicated in the model. The waves were typical of the region (35 m vertical displacement). Two types of ducting are found in the model, which occur asynchronously. One type is three-dimensional modal trapping in deep ducts within the wave crests (shallow thermocline zones). The second type is surface ducting within the wave troughs (deep thermocline zones). © 2011 Acoustical Society of America

  3. Energy output estimation for a small wind turbine positioned on a rooftop in the urban environment with and without a duct

    Energy Technology Data Exchange (ETDEWEB)

    Beller, C.

    2011-05-15

    Nowadays, wind turbines in general, but also urban wind turbines attained acceptance to a certain extend. Conceptual designs and some examples in reality exist, where small-scale wind turbines have been implemented close to buildings or even integrated in the building structure. This work is aiming to estimate how much energy a wind turbine could produce in the built environment, depending on its integration and configuration. On the basis of measurements taken on the rooftop of H.C. Orsted Institut in Copenhagen, which is located in an urban area, a comparison of fictive free standing turbines with ducted turbines of the same type was carried out. First, a prevailing wind energy direction was detected with rough mean velocity and frequency calculations. Next, a duct was aligned with the direction, where the highest energy potential was found. Further calculations were conducted with more detailed wind velocity distributions, depending on the wind direction sectors. The duct's wind velocity amplification capability was set to 14%, while a total opening angle of 30. was assumed to be accessible from both sides. With the simplifying assumptions and the uncertainties at the location of measurement, the free standing turbines had an energy potential of 300kWh/m2/a for the horizontal axis wind turbine (HAWT) and for the vertical axis wind turbine (VAWT) 180kWh/m2/a. For the ducted turbines an energy output of 180kWh/m2/a was found for the HAWT configuration, while the VAWT configuration reached an output of 110kWh/m2/a. The available wind had an energy potential of 730kWh/m2/a. Evaluating these results it seems a free standing turbine is preferable, when only considering the power output, whereas the ducted version comprises properties, which are important considering the requirements needed in the inhabited area such as safety and noise issues. (Author)

  4. Simulation of natural circulation in a rectangular loop using CFD code PHOENICS

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.; Borghain, A.; Maheshwari, N.K.; Vijayan, P.K. [Bhabha Atomic Reseach Centre, Trombay, Mumbai (India). Reactor Engineering Div.

    2011-05-15

    Single phase natural circulation in a rectangular loop is simulated using the PHOENICS code, a general purpose Computational Fluid Dynamics (CFD) code. The rectangular loop, having different operating power levels, has been modeled with the help of the Multiple Block Fine Grid Embedment (MBFGE) technique. The Co-located Co-variant Method (CCM) is used to simulate this loop in PHOENICS. Extensive experimental and CFD studies have been conducted on single phase natural circulation in a rectangular loop. The paper presents the results of three-dimensional CFD analysis for the prediction of steady state behavior in a rectangular loop and its comparison with experimental data. The results of code prediction and readily available experimental data show good agreement. (orig.)

  5. The coextrusion of two incompressible elastico-viscous fluids through a rectangular channel

    Science.gov (United States)

    Jones, R. S.; Thomas, O. D. J.

    1989-05-01

    The slow coextrusion of two non-Newtonian fluids through a rectangular channel is considered. The shape of the interface and the secondary flows are investigated and their dependence on the fluid properties determined.

  6. Numerical investigation of heat transfer enhancement in a rectangular heated pipe for turbulent nanofluid

    National Research Council Canada - National Science Library

    Yarmand, Hooman; Gharehkhani, Samira; Kazi, Salim Newaz; Sadeghinezhad, Emad; Safaei, Mohammad Reza

    2014-01-01

    .... The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated...

  7. On the Regularization independence of the Casimir energy for rectangular geometries

    Science.gov (United States)

    Manzoni, Luiz

    2011-04-01

    The Ramanujan sum of a divergent series is employed to investigate the regularization independence of the Casimir energy in d-dimensional rectangular geometries. As an specific application we consider the piston geometry for the scalar field.

  8. K+ channels on resting duct cells from rat pancreas.

    Science.gov (United States)

    Hayashi, Mikio; Matsuda, Hiroko

    2009-01-01

    The ductal system of the exocrine pancreas produces HCO(3)(-)-rich fluid in response to secretin and other stimuli. HCO(3)(-) efflux across the luminal membrane is mediated by a Cl(-)-HCO(3)(-) exchanger operating in parallel with the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. Basolateral K(+) channels provide an exit pathway for K(+) and play a vital role in maintaining the membrane potential, which is a crucial component of the driving force for anion secretion. Measurements of membrane potential with intracellular microelectrodes suggested that Ba(2+)-sensitive K(+) conductance accounts for more than 60% of the total basolateral ionic conductance in resting ducts (1). To identify the Ba(2+)-sensitive K(+) channels, we isolated ducts from normal rat pancreas by collagenase digestion. We first demonstrated that the ducts did not express a vascular endothelial marker PECAM-1 (platelet/endothelial cell adhesion molecule-1), but expressed cytokeratin 20, a marker of duct cells (2), using immunofluorescent staining. In addition, monoclonal anti-CFTR antibody was detected near the luminal membrane of these cells. In cell-attached single-channel recordings, we observed three types of K(+) channels on basolateral membrane in unstimulated duct cells. The 40 pS K(+) channels are likely to mediate whole-cell inwardly rectifying K(+) (Kir) currents, which were blocked by extracellular Ba(2+) in a voltage-dependent manner. The properties of 90 pS and 170 pS K(+) channels are similar to those of Ca(2+)-activated K(+) channels. We then identified Kir2.0 and SK4/IK1 (intermediate conductance Ca(2+)-activated K(+) channel) subunits as molecular candidates of the K(+) channels using RT-PCR analysis. The present results suggest that these subunits may mediate native K(+) currents in resting duct cells. Further functional studies with specific blockers are required to evaluate which of these K(+) channels contribute to the resting membrane potential

  9. Surgical strategy for bile duct cancer: Advances and current limitations

    Science.gov (United States)

    Akamatsu, Nobuhisa; Sugawara, Yasuhiko; Hashimoto, Daijo

    2011-01-01

    The aim of this review is to describe recent advances and topics in the surgical management of bile duct cancer. Radical resection with a microscopically negative margin (R0) is the only way to cure cholangiocarcinoma and is associated with marked survival advantages compared to margin-positive resections. Complete resection of the tumor is the surgeon’s ultimate aim, and several advances in the surgical treatment for bile duct cancer have been made within the last two decades. Multidetector row computed tomography has emerged as an indispensable diagnostic modality for the precise preoperative evaluation of bile duct cancer, in terms of both longitudinal and vertical tumor invasion. Many meticulous operative procedures have been established, especially extended hepatectomy for hilar cholangiocarcinoma, to achieve a negative resection margin, which is the only prognostic factor under the control of the surgeon. A complete caudate lobectomy and resection of the inferior part of Couinaud’s segment IV coupled with right or left hemihepatectomy has become the standard surgical procedure for hilar cholangiocarcinoma, and pylorus-preserving pancreaticoduodenectomy is the first choice for distal bile duct cancer. Limited resection for middle bile duct cancer is indicated for only strictly selected cases. Preoperative treatments including biliary drainage and portal vein embolization are also indicated for only selected patients, especially jaundiced patients anticipating major hepatectomy. Liver transplantation seems ideal for complete resection of bile duct cancer, but the high recurrence rate and decreased patient survival after liver transplant preclude it from being considered standard treatment. Adjuvant chemotherapy and radiotherapy have a potentially crucial role in prolonging survival and controlling local recurrence, but no definite regimen has been established to date. Further evidence is needed to fully define the role of liver transplantation and adjuvant

  10. Simultaneous Papillary Carcinoma in Thyroglossal Duct Cyst and Thyroid

    Directory of Open Access Journals (Sweden)

    Gustavo Cancela e Penna

    2017-01-01

    Full Text Available Thyroglossal duct cyst (TDC is a cystic expansion of a remnant of the thyroglossal duct tract. Carcinomas in the TDC are extremely rare and are usually an incidental finding after the Sistrunk procedure. In this report, an unusual case of a 36-year-old woman with concurrent papillary thyroid carcinoma arising in the TDC and on the thyroid gland is presented, followed by a discussion of the controversies surrounding the possible origins of a papillary carcinoma in the TDC, as well as the current management options.

  11. Sterility caused by functional absence of ejaculatory ducts.

    Science.gov (United States)

    Arce, B; Padrón, R S; Pérez-Plaza, M

    1981-01-01

    Five patients with functional absence of genital excretory ducts are presented, with emphasis on the scarcity of physical and complementary data obtained. The low impairment of spermatogenesis is pointed out. Seminal characteristics are analysed and the diagnostic importance of spermogram data stressed. The importance of the qualitative determination of fructose for the diagnosis of this syndrome is noted, as well as the incidence of this syndrome as the cause of azoospermia and sterility. The existence of a unilateral congenital absence of ejaculatory ducts is demonstrated. Cases of this sort cannot be detected unless a contralateral acquired lesion occurs.

  12. Sound propagation through a variable area duct - Experiment and theory

    Science.gov (United States)

    Silcox, R. J.; Lester, H. C.

    1981-01-01

    A comparison of experiment and theory has been made for the propagation of sound through a variable area axisymmetric duct with zero mean flow. Measurement of the acoustic pressure field on both sides of the constricted test section was resolved on a modal basis for various spinning mode sources. Transmitted and reflected modal amplitudes and phase angles were compared with finite element computations. Good agreement between experiment and computation was obtained over a wide range of frequencies and modal transmission variations. The study suggests that modal transmission through a variable area duct is governed by the throat modal cut-off ratio.

  13. Diverticular bile duct lesion in chronic active hepatitis

    DEFF Research Database (Denmark)

    Vyberg, M

    1989-01-01

    of a not previously described diverticular type were revealed. The diverticuli were of varying shape with a diameter of 30 to 110 microns and a length of 75 to 150 microns budding from small (12 to 25 microns), slightly ectatic bile ducts. The diverticular epithelium was disordered. Some cells appeared as bile duct...... cells, but most were larger, with rounded nuclei, prominent nucleoli and abundant eosinophilic cytoplasm, sometimes with periodic acid-Schiff-positive, diastase-resistant granules. The lesions were only partly surrounded by a basement membrane. They were all embedded in a tight mononuclear inflammatory...

  14. Common bile duct stones: analysis of the videolaparoscopic surgical treatment

    Directory of Open Access Journals (Sweden)

    Marco Aurelio Santo

    2012-03-01

    Full Text Available CONTEXT: About 9% of the Brazilian population has gallstones and the incidence increases significantly with aging. The choledocholithiasis is found around 15% of these patients, and a third to half of these cases presented as asymptomatic. Once the lithiasis in the common bile duct is characterized through intraoperative cholangiography, the laparoscopic surgical exploration can be done through the transcystic way or directly through choledochotomy. OBJECTIVE: To evaluate the results and outcomes of the laparoscopic treatment of common bile duct lithiasis. METHODS: Seventy consecutive patients were evaluated. They prospectively underwent the treatment of the lithiasis in the common bile duct and the exploration ways were compared according to the following parameters: criteria on their indication, success in the clearance, surgical complications. It was verified that about ½ of the choledocholithiasis carriers did not show any expression of predictive factors (clinical antecedents of jaundice and/or acute pancreatitis, compatible sonographic data and the pertaining lab tests. The laparoscopic exploration through the transcystic way is favored when there are no criteria for the practice of primary choledochotomy, which are: lithiasis in the proximal bile duct, large (over 8 mm or numerous calculi (multiple calculosis. RESULTS: The transcystic way was employed in about 50% of the casuistic and the choledochotomy in about 30%. A high success rate (around 80% was achieved in the clearance of the common bile duct stones through laparoscopic exploration. The transcystic way, performed without fluoroscopy or choledochoscopy, attained a low rate of success (around 45%, being 10% of those by transpapilar pushing of calculi less than 3 mm. The exploration through choledochotomy, either primary or secondary, if the latter was performed after the transcystic route failure, showed high success rate (around 95%. When the indication to choledochotomy was

  15. [Mini invasive treatment of common biliary duct lithiasis].

    Science.gov (United States)

    Deacu, Adriana

    2003-01-01

    The aim of the paper is to show modern techniques of treatment in common biliary duct lithiasis, in the context of the remarkable development of laparoscopic surgery. The text, trays to mark some directions for the surgeon to know when and which of the modern techniques to chose for safe treatment of common biliary duct lithiasis. The criteria are bound to the moment of diagnosis, clinical state of the patient and laboratory tests. Of course, a final commitment will be taken after an objective evaluation of the technique possibilities and the experience of the team.

  16. Advanced Strategy Guideline: Air Distribution Basics and Duct Design

    Energy Technology Data Exchange (ETDEWEB)

    Burdick, A.

    2011-12-01

    This report discusses considerations for designing an air distribution system for an energy efficient house that requires less air volume to condition the space. Considering the HVAC system early in the design process will allow adequate space for equipment and ductwork and can result in cost savings. Principles discussed that will maximize occupant comfort include delivery of the proper amount of conditioned air for appropriate temperature mixing and uniformity without drafts, minimization of system noise, the impacts of pressure loss, efficient return air duct design, and supply air outlet placement, as well as duct layout, materials, and sizing.

  17. A measuring stand for a ducted fan aircraft propulsion unit

    Directory of Open Access Journals (Sweden)

    Hlaváček David

    2014-03-01

    Full Text Available The UL-39 ultra-light aircraft which is being developed by the Department of Aerospace Engineering, Faculty of Mechanical Engineering, Czech Technical University in Prague, is equipped with an unconventional ducted fan propulsion unit. The unit consists of an axial fan driven by a piston engine and placed inside a duct ended with a nozzle. This article describes the arrangement of a modernised measuring stand for this highly specific propulsion unit which will be able to measure the fan pressure ratio and velocity field in front of and behind the fan and its characteristic curve.

  18. Azygos ladder and looped thoracic duct – a case report

    Directory of Open Access Journals (Sweden)

    Kumar N

    2011-04-01

    Full Text Available Knowledge of variations in the posterior mediastinum close to the vertebral column is important for cardiothoracic surgeons, radiologists and orthopedic surgeons. We report variations of azygos veins and thoracic duct. The azygos system of veins showed a ladder pattern. The hemiazygos and accessory hemiazygos veins communicated with the azygos vein through six transverse channels across the vertebral column. The accessory hemiazygos and hemiazygos veins joined to form a common channel which opened into the azygos vein. The thoracic duct gave two branches in the posterior mediastinum and these branches joined to form a loop.

  19. Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation

    KAUST Repository

    Saghir, Shahid

    2016-12-01

    The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear static and dynamic behavior of rectangular microplates under small and large actuating forces. In the first part, we present and compare various approaches to develop reduced order models for the nonlinear von-Karman rectangular microplates actuated by nonlinear electrostatic forces. The reduced-order models aim to investigate the static and dynamic behavior of the plate under small and large actuation forces. A fully clamped microplate is considered. Different types of basis functions are used in conjunction with the Galerkin method to discretize the governing equations. First we investigate the convergence with the number of modes retained in the model. Then for validation purpose, a comparison of the static results is made with the results calculated by a nonlinear finite element model. The linear eigenvalue problem for the plate under the electrostatic force is solved for a wide range of voltages up to pull-in. In the second part, we present an investigation of the static and dynamic behavior of a fully clamped microplate. We investigate the effect of different non-dimensional design parameters on the static response. The forced-vibration response of the plate is then investigated when the plate is excited by a harmonic AC load superimposed to a DC load. The dynamic behavior is examined near the primary and secondary (superharmonic and subharmonic) resonances. The microplate shows a strong hardening behavior due to the cubic nonlinearity of midplane stretching. However, the behavior switches to softening as the DC load is increased. Next, near-square plates are studied to understand the effect of geometric imperfections of microplates. In the final part of the dissertation, we investigate the mechanical behavior of

  20. Horizontal vortex single chamber hydroturbine

    Directory of Open Access Journals (Sweden)

    Sergio Antonio Zarate-Orrego

    2016-01-01

    Full Text Available Se evaluó una máquina con alta resistencia de forma para extraer energía de una quebrada, río o corriente marina, y generar electricidad. Sin instrumentos adecuados, la investigación fue cualitativa. Se supuso que si aun así funcionaba, su comportamiento podía mejorar suavizándose la forma. El aparato tiene una tobera semi-convergente de paredes planas, una cámara de vórtice cilíndrica y un rodete. Capta agua por su sección mayor y la descarga tangencialmente por su sección menor en la cámara de vórtice; ésta tiene un orificio en una de sus paredes laterales. Así forma un vórtice horizontal que hace girar un rodete cuyo eje acciona un generador eléctrico. El trabajo experimental realizado mostró que sí es posible producir energía eléctrica con este dispositivo pese a las condiciones adversas en que se ensayó.

  1. Horizontal cooperation in logistics : Opportunities and impediments

    NARCIS (Netherlands)

    Cruijssen, Frans; Cools, Martine; Dullaert, Wout

    This paper presents the results of a large-scale survey on the potential benefits of and impediments for horizontal cooperation in Flanders. The main findings are that in general Logistics Service Providers strongly believe in the potential benefits of horizontal cooperation to increase their

  2. Rectifying Horizontal Inequalities: Lessons from African Conflict ...

    African Journals Online (AJOL)

    One of the most prevalent and underrepresented root causes of conflict in Africa and worldwide is that of horizontal inequalities. In that light, the goal of this paper is to provide practical solutions for the long-term resolution of conflict by addressing one of its root causes, that of horizontal inequalities. Reference will be made ...

  3. Rectifying Horizontal Inequalities: Lessons from African Conflict

    African Journals Online (AJOL)

    and horizontal (between groups) inequalities. A number of scholars have addressed the question of inequalities. Frances Stewart, for example, deals with the problem of horizontal inequalities in a number of papers.2 Stewart. (2002:3) argues that 'unequal access to political/economic/social resources. 1 The social contract ...

  4. Do infants have the horizontal bias?

    NARCIS (Netherlands)

    van Renswoude, D.R.; Johnson, S.P.; Raijmakers, M.E.J.; Visser, I.

    2016-01-01

    A robust set of studies show that adults make more horizontal than vertical and oblique saccades, while scanning real-world scenes. In this paper we study the horizontal bias in infants. The directions of eye movements were calculated for 41 infants (M = 8.40 months, SD = 3.74, range = 3.48–15.47)

  5. The Process of Horizontal Differentiation: Two Models.

    Science.gov (United States)

    Daft, Richard L.; Bradshaw, Patricia J.

    1980-01-01

    Explores the process of horizontal differentiation by examining events leading to the establishment of 30 new departments in five universities. Two types of horizontal differentiation processes--administrative and academic--were observed and each was associated with different organizational conditions. (Author/IRT)

  6. Autoantibodies Targeting a Collecting Duct-Specific Water Channel in Tubulointerstitial Nephritis

    DEFF Research Database (Denmark)

    Landegren, Nils; Pourmousa Lindberg, Mina; Skov, Jakob

    2016-01-01

    with autoimmune polyendocrine syndrome type 1 who developed tubulointerstitial nephritis and ESRD in association with autoantibodies against kidney collecting duct cells. One of the patients developed autoantibodies targeting the collecting duct-specific water channel aquaporin 2, whereas autoantibodies...

  7. Congenital double bile duct presenting as recurrent cholangitis in a child

    Directory of Open Access Journals (Sweden)

    K.D. Chakravarty

    2015-12-01

    Full Text Available Double common bile duct (DCBD is a rare congenital anomaly. Most of these bile duct anomalies are associated with bile duct stones, anomalous pancreaticobiliary junction (APBJ, pancreatitis and bile duct or gastric cancers. Early detection and treatment is important to avoid long term complications. Surgical resection of the anomalous bile duct and reconstruction of the biliary enteric anastomosis is the treatment of choice. We report a rare case of DCBD anomaly in a girl, who presented with recurrent cholangitis. She had type Va DCBD anomaly. She underwent successful resection of the bile duct and reconstruction of the biliary enteric anastomosis. Preoperative imaging and diagnosis of the congenital biliary anomaly is very important to avoid intraoperative bile duct injury. Review of the literature shows very few cases of type Va DCBD, presenting with either bile duct stones or APBJ.

  8. Chemo Drug May Buy Time for Those with Bile Duct Cancer

    Science.gov (United States)

    ... Chemo Drug May Buy Time for Those With Bile Duct Cancer For patients with the rare disease, survival ... system cancer, a new study finds. People with bile duct cancer who received the medication lived for an ...

  9. Measure Guideline: Summary of Interior Ducts in New Construction, Including an Efficient, Affordable Method to Install Fur-Down Interior Ducts

    Energy Technology Data Exchange (ETDEWEB)

    Beal, D.; McIlvaine , J.; Fonorow, K.; Martin, E.

    2011-11-01

    This document illustrates guidelines for the efficient installation of interior duct systems in new housing, including the fur-up chase method, the fur-down chase method, and interior ducts positioned in sealed attics or sealed crawl spaces. This document illustrates guidelines for the efficient installation of interior duct systems in new housing. Interior ducts result from bringing the duct work inside a home's thermal and air barrier. Architects, designers, builders, and new home buyers should thoroughly investigate any opportunity for energy savings that is as easy to implement during construction, such as the opportunity to construct interior duct work. In addition to enhanced energy efficiency, interior ductwork results in other important advantages, such as improved indoor air quality, increased system durability and increased homeowner comfort. While the advantages of well-designed and constructed interior duct systems are recognized, the implementation of this approach has not gained a significant market acceptance. This guideline describes a variety of methods to create interior ducts including the fur-up chase method, the fur-down chase method, and interior ducts positioned in sealed attics or sealed crawl spaces. As communication of the intent of an interior duct system, and collaboration on its construction are paramount to success, this guideline details the critical design, planning, construction, inspection, and verification steps that must be taken. Involved in this process are individuals from the design team; sales/marketing team; and mechanical, insulation, plumbing, electrical, framing, drywall and solar contractors.

  10. Horizontal gene transfer in human pathogens.

    Science.gov (United States)

    Juhas, Mario

    2015-02-01

    Horizontal gene transfer has a tremendous impact on the genome plasticity, adaptation and evolution of bacteria. Horizontally transferred mobile genetic elements are involved in the dissemination of antibiotic resistance and virulence genes, thus contributing to the emergence of novel "superbugs". This review provides update on various mechanisms of horizontal gene transfer and examines how horizontal gene transfer contributes to the evolution of pathogenic bacteria. Special focus is paid to the role horizontal gene transfer plays in pathogenicity of the emerging human pathogens: hypervirulent Clostridium difficile and Escherichia coli (including the most recent haemolytic uraemic syndrome outbreak strain) and methicillin-resistant Staphylococcus aureus (MRSA), which have been associated with largest outbreaks of infection recently.

  11. Chitin in the silk gland ducts of the spider Nephila edulis and the silkworm Bombyx mori.

    Science.gov (United States)

    Davies, Gwilym J G; Knight, David P; Vollrath, Fritz

    2013-01-01

    Here we report the detection and localisation of chitin in the cuticle of the spinning ducts of both the spider Nephila edulis and the silkworm Bombyx mori. Our observations demonstrate that the duct walls of both animals contain chitin notwithstanding totally independent evolutionary pathways of the systems. We conclude that chitin may well be an essential component for the construction of spinning ducts; we further conclude that in both species chitin may indicate the evolutionary origin of the spinning ducts.

  12. Chitin in the silk gland ducts of the spider Nephila edulis and the silkworm Bombyx mori.

    Directory of Open Access Journals (Sweden)

    Gwilym J G Davies

    Full Text Available Here we report the detection and localisation of chitin in the cuticle of the spinning ducts of both the spider Nephila edulis and the silkworm Bombyx mori. Our observations demonstrate that the duct walls of both animals contain chitin notwithstanding totally independent evolutionary pathways of the systems. We conclude that chitin may well be an essential component for the construction of spinning ducts; we further conclude that in both species chitin may indicate the evolutionary origin of the spinning ducts.

  13. Surgical management of Stenson's duct injury using epidural catheter

    African Journals Online (AJOL)

    2012-07-05

    rediffmail.com ... and silk worm gut as a indwelling stent inside the parotid duct before repairing have been reported.[6] Only ... of trauma from a road traffic accident 2 h before reporting was noted. Patient was conscious when ...

  14. Design requirement on KALIMER blanket fuel assembly duct

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Woan; Kang, H. Y.; Nam, C.; Kim, J. O

    1998-03-01

    This document describes design requirements which are needed for designing the blanket fuel assembly duct of the KALIMER as design guidance. The blanket fuel assembly duct of the KALIMER consists of fuel rods, mounting rail, nosepiece, duct with pad, handling socket with pad. Blanket fuel rod consists of top end plug, bottom end plug with solid ferritic-martensitic steel rod and key way blanket fuel slug, cladding, and wire wrap. In the assembly, the rods are in a triangular pitch array, and the rod bundle is attached to the nosepiece with mounting rails. The bottom end of the assembly duct is formed by a long nosepiece which provides the lower restraint function and the paths for coolant inlet. This report contains functional requirements, performance and operational requirements, interfacing systems requirements, core restraint and interface requirements, design limits and strength requirements, system configuration and essential feature requirements, seismic requirements, structural requirements, environmental requirements, reliability and safety requirements, standard and codes, QA programs, and other requirements. (author). 20 refs., 4 figs.

  15. Thyroglossal Duct Papillary Thyroid Carcinoma and Synchronous Lingual Thyroid Atypia

    Directory of Open Access Journals (Sweden)

    Timothy Yoo

    2016-01-01

    Full Text Available Thyroglossal duct and lingual thyroid ectopic lesions are exceedingly rare synchronous findings. Papillary thyroid carcinoma of these ectopic thyroid sites is well understood but still a rare finding. This case points to some management nuances in regard to ectopic thyroid screening with imaging and also shows the effectiveness of minimally invasive transoral robotic surgery for lingual thyroid.

  16. Reconstruction of major bile duct injuries after laparoscopic cholecystectomy

    DEFF Research Database (Denmark)

    Holte, Kathrine; Bardram, Linda; Wettergren, André

    2010-01-01

    Bile duct injury (BDI) after cholecystectomy remains a serious complication with major implications for patient outcome. For most major BDIs, the recommended method of repair is a hepaticojejunostomy (HJ). We conducted a retrospective review aiming to examine the perioperative and the long...

  17. Effect of duct orientation on particle deposition in the human ...

    African Journals Online (AJOL)

    ... of alveolar re-circulation and gravity orientation are key factors in determining the deposition in the last four generations of the human respiratory tract. Keywords: duct orientation, particle deposition, respiratory tract, discretization approach. African Journal of Educational Studies in Mathematics and Sciences Vol. 9, 2011 ...

  18. Clear cell carcinoid tumor of the distal common bile duct

    Directory of Open Access Journals (Sweden)

    Tsukada Katsuhiko

    2007-01-01

    Full Text Available Abstract Background Carcinoid tumors rarely arise in the extrahepatic bile duct and can be difficult to distinguish from carcinoma. There are no reports of clear cell carcinoid (CCC tumors in the distal bile duct (DBD to the best of our knowledge. Herein, we report a CCC tumor in the DBD and review the literature concerning extrahepatic bile duct carcinoid tumors. Case presentation A 73-old man presented with fever and occult obstructive jaundice. Ultrasonography, computed tomography (CT and magnetic resonance cholangiopancreaticography (MRCP demonstrated a nodular tumor projection in the DBD without regional lymph node swelling. Under suspicion of carcinoma, we resected the head of the pancreas along with 2nd portion duodenectomy and a lymph node dissection. The surgical specimen showed a golden yellow polypoid tumor in the DBD (0.8 × 0.6 × 0.5 cm in size. The lesion was composed of clear polygonal cells arranged in nests and a trabecular pattern. The tumor invaded through the wall into the fibromuscular layer. Immunohistochemical stains showed that neoplastic cells were positive for neuron-specific enolase (NSE, chromogranin A, synaptophysin, and pancreatic polypeptide and negative for inhibin, keratin, CD56, serotonin, gastrin and somatostatin. The postoperative course was uneventful and he is living well without relapse 12 months after surgery. Conclusion Given the preoperative difficulty in differentiating carcinoid from carcinoma, the pancreaticoduodenectomy is an appropriate treatment choice for carcinoid tumors located within the intra-pancreatic bile duct.

  19. Bidirectional infrasonic ducts associated with sudden stratospheric warming events

    Science.gov (United States)

    Assink, J. D.; Waxler, R.; Smets, P.; Evers, L. G.

    2014-02-01

    In January 2011, the state of the polar vortex in the midlatitudes changed significantly due to a minor sudden stratospheric warming event. As a result, a bidirectional duct for infrasound propagation developed in the middle atmosphere that persisted for 2 weeks. The ducts were due to two zonal wind jets, one between 30 and 50 km and the other around 70 km altitude. In this paper, using microbarom source modeling, a previously unidentified source region in the eastern Mediterranean is identified, besides the more well known microbarom source regions in the Atlantic Ocean. Infrasound data are then presented in which the above mentioned bidirectional duct is observed in microbarom signals recorded at the International Monitoring System station I48TN in Tunisia, from the Mediterranean region to the east and from the Atlantic Ocean to the west. While the frequency bands of the two sources overlap, the Mediterranean signal is coherent up to about 0.6 Hz. This observation is consistent with the microbarom source modeling; the discrepancy in the frequency band is related to differences in the ocean wave spectra for the two basins considered. This work demonstrates the sensitivity of infrasound to stratospheric dynamics and illustrates that the classic paradigm of a unidirectional stratospheric duct for infrasound propagation can be broken during a sudden stratospheric warming event.

  20. Biliary cystadenoma of the left intrahepatic duct (2007: 2b)

    NARCIS (Netherlands)

    Seidel, R.; Weinrich, M.; Pistorius, G.; Fries, P.; Schneider, G.

    2007-01-01

    Biliary cystadenoma is a rare epithelial cystic neoplasm representing only 5% of intrahepatic cystic lesions of biliary origin. Commonly, the lesions are solitary cystic structures with multiple thin-walled septa predominantly arising from the right hepatic duct. Although the lesions are generally

  1. Persistent Mullerian duct syndrome: the hidden normal or abnormal ...

    African Journals Online (AJOL)

    Persistent Mullerian duct syndrome (PMDS) is a rare disorder of male sexual development. It is characterized by the presence of a uterus, fallopian tubes, and upper vagina in an otherwise phenotypically and genotypically normal male. This malformation is usually an incidental finding during the operative treatment of other ...

  2. Optimizing the Treatment of Acute Duct-Destructive Pancreatitis

    Science.gov (United States)

    Zhakiev, Bazylbek S.; Karsakbayev, Uteugali G.; Kelimberdiev, Mersaid S.; ?uhamedgalieva, Bodagoz M.; K?nonenko, Aleksander F.

    2016-01-01

    The search for new methods for treating duct-destructive pancreatitis is a relevant problem. Endogenous intoxication and oxidative stress that accompany acute pancreatitis often progress even after surgery, which forces one to search for additional possibilities of preventing these severe consequences. This research studied the effect of small…

  3. Symptomatic vitelline duct anomalies in children | Ameh | South ...

    African Journals Online (AJOL)

    A wide variety of anomalies may occur as a result of the vitelline duct (VD) failing to obliterate completely. Most reports on symptomatic VD focus on Meckel\\'s diverticulum, while other anomalies are given little attention. A retrospective review was conducted at our institution. According to the records 18 symptomatic children ...

  4. Laparoscopic managment of common bile duct stones: our initial experience.

    Science.gov (United States)

    Aroori, S.; Bell, J. C.

    2002-01-01

    The management of choledocholithiasis has changed radically since the introduction of laparoscopic cholecystectomy. However, perceived technical difficulties have deterred many surgeons from treating common bile duct stones laparoscopically at the time of cholecystectomy. This has lead to reliance on endoscopic retrograde cholangiopancreatography followed by endoscopic sphincterotomy to deal with common bile duct stones. We retrospectively reviewed the charts of patients who had laparoscopic common bile duct exploration at Downe Hospital between December 1999 and August 2001. Among 149 laparoscopic cholecystectomies done by our group in this period, 10 patients (6.7%) underwent laparoscopic CBD exploration, three by the transcystic technique and seven by choledochotomy. Three patients (2%) had unsuspected stones found on routine per- operative cholangiogram. The mean operative time was 2.34hrs (range 1.50-3.30hrs). The mean hospital post- operative stay was 3 days (range 1-6 days). Post-operative morbidity was zero. Stone clearance was achieved in all cases. We conclude, laparoscopic exploration of the common bile duct is relatively safe and straightforward method. The key skill required is the ability to perform laparoscopic suturing with confidence. PMID:12137159

  5. Radiation from a lined duct in uniform flow

    DEFF Research Database (Denmark)

    Juhl, Peter Møller

    1999-01-01

    This paper presents a boundary element formulation for modelling the sound field inside and outside a duct in uniform flow. The model is the first step towards models for predicting the noise radiated from turbo fan engines. For this purpose the frequency range is very large (up to ka=40), and non...

  6. Duct injection technology prototype development. Materials corrosion report, Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Harper, S.L. [Babcock and Wilcox Co., Alliance, OH (United States). Research and Development Div.

    1991-08-01

    This report describes a test program conducted to determine the corrosion rate of materials in the dry scrubber or duct injection systems. Four materials were evaluated: 1010 carbon steel, Corten, 317SS and Hastelloy C-276. The results show that acidic conditions result in higher corrosion rates than alkaline conditions for all the materials. The carbon steel, Corten and stainless steel show moderate to heavy pitting attack in the acidic environment. For the alkaline conditions, the corrosion rates of carbon steel and Corten were higher than the stainless steel or Hastelloy C-276. Also, the corrosion rate of abraded specimens were four time those of unabraded specimens in the flue gas. It is probable that areas of wall-wetting and plugging in the duct injection process will exhibit high rates of corrosion for the carbon steel, Corten, and stainless steel materials. General corrosion and pitting corrosion will predominate. Additionally, abraded duct areas will corrode at a significantly higher rate than unabraded duct materials. 6 refs., 11 figs., 7 tabs.

  7. Echinococcal Cyst of the Pancreas with Cystopancreatic Duct Fistula ...

    African Journals Online (AJOL)

    Echinococcal Cyst of the Pancreas with Cystopancreatic. Duct Fistula Successfully Treated by Partial Cystectomy and. Cystogastrostomy. Ahmed Elaffand, Adarsh Vijay1, Samah Mohamed, Hassan Hani Al-Battah1, Ayda Youssef, Ahmed Farahat. INTRODUCTION. Hydatid disease (HD) is a rare endemic disease in.

  8. A Rare Case of Mediastinal Cyst: Thoracic Duct Cyst

    Directory of Open Access Journals (Sweden)

    Duygu Mergan

    2016-01-01

    Full Text Available Thoracic duct cysts are very rarely observed cysts of the mediastinum. These cysts, which can become established in the costovertebral sulcus or the visceral compartment, have generally been reported at the level of the 10th and 11th vertebrae; however, they can be observed at any location along the ductus [1]. A 37-year-old male patient complained of chest pain for the last 3 months that especially increased after meals. He complained of shortness of breath while walking or going up the stairs, for the last month. The lung graphy showed an increased darkening at a 5x6cm smooth (clean-cut, regular, orderly bordered shadow just behind the heart shadow. The patient%u2019s computed thorax tomography showed a retrocardiac-paravertebral, middle line positioned, 8.5x7x6 cm proportioned, regular bordered, thin walled, homogenous cystic bulk at the subcarinal level. The patient, who could not be relieved with medical treatment, was taken to surgery. The lesion was reached by right posterolateral thoracotomy, and drainage of lymph-containing cystic fluid and excision of the cyst walls were performed by incising the thoracic duct cyst with a mediastinal pleura incision. Mass ligation was then performed to the thoracic duct. We wanted to present our thoracic duct cyst case in this article due to the currently limited number of actual cases reported in the literature.

  9. Heuristic approach to the passive optical network with fibre duct ...

    African Journals Online (AJOL)

    PON) plan- ning problem ... This paper uses concepts from network flow optimisation to incorporate fibre duct shar- ing into a ...... 682–686. [31] Yen JY, 1971, Finding the k shortest loopless paths in a network, Management Science, 17(11), pp.

  10. High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine

    NARCIS (Netherlands)

    Tang, J.; van Bussel, G.J.W.

    2017-01-01

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure

  11. Resin duct characteristics in the wood of fire-scarred North American conifers

    Science.gov (United States)

    Estelle Arbellay; Markus Stoffel; Elaine K. Sutherland; Kevin T. Smith; Donald A. Falk

    2013-01-01

    Traumatic resin ducts form in xylem and phloem tissue of conifers in response to abiotic wounding, fungal invasion, and insect attack. Little is known about resin duct characteristics in the wood of fire-scarred trees. The aim of this study is to quantify changes in traits of both axial and radial resin ducts, along with those of associated epithelial cells and...

  12. Absorption of the Wolffian duct and duplicated ureter by the urogenital sinus: morphological study using human fetuses and embryos.

    Science.gov (United States)

    Naito, Michiko; Hinata, Nobuyuki; Rodriguez-Vazquez, Jose Francisco; Murakami, Gen; Aizawa, Shin; Fujisawa, Masato

    2015-07-01

    To describe the embryological origin of the duplicated ureter and to investigate whether the urogenital sinus absorbs not only the Wolffian duct (WD) but also the ureter. During studies using sections of human fetuses (45 specimens), we incidentally found a specific type of ureteric duplication (at ~7 weeks) in which two unilateral ureters joined at the vesico-ureteric junction, apparently representing a morphology arising at an intermediate stage between complete and partial ureteric duplication. The existing literature lacks any photographic representation of early development of the vesico-ureteric junction, and we therefore studied horizontal sections of 10 human embryos (at ~5-6 weeks' gestation) in which the ureter did not join the urogenital sinus (future bladder) but instead joined the WD (future vas deferens). The sinus consistently showed a reversed Y-shape, the arms of which extended posteriorly to receive the WD. When absorption of the duct into the sinus wall reached the distal end of the ureter, the arm-like parts appeared to enlarge posteriorly for further involvement of the duct, with little or no incorporation of the ureter; therefore, the future trigone of the bladder might develop from these arm-like parts of the sinus posterior wall. Consequently, in the case of ureteric duplication included in the present study, it is considered that the ureters would probably have merged with the WD at closely adjacent sites. The present study represents the first photographic illustration of the early development of the human vesico-ureteric junction. © 2014 The Authors BJU International © 2014 BJU International Published by John Wiley & Sons Ltd.

  13. Causes and Prevention of Laparoscopic Bile Duct Injuries

    Science.gov (United States)

    Way, Lawrence W.; Stewart, Lygia; Gantert, Walter; Liu, Kingsway; Lee, Crystine M.; Whang, Karen; Hunter, John G.

    2003-01-01

    Objective To apply human performance concepts in an attempt to understand the causes of and prevent laparoscopic bile duct injury. Summary Background Data Powerful conceptual advances have been made in understanding the nature and limits of human performance. Applying these findings in high-risk activities, such as commercial aviation, has allowed the work environment to be restructured to substantially reduce human error. Methods The authors analyzed 252 laparoscopic bile duct injuries according to the principles of the cognitive science of visual perception, judgment, and human error. The injury distribution was class I, 7%; class II, 22%; class III, 61%; and class IV, 10%. The data included operative radiographs, clinical records, and 22 videotapes of original operations. Results The primary cause of error in 97% of cases was a visual perceptual illusion. Faults in technical skill were present in only 3% of injuries. Knowledge and judgment errors were contributory but not primary. Sixty-four injuries (25%) were recognized at the index operation; the surgeon identified the problem early enough to limit the injury in only 15 (6%). In class III injuries the common duct, erroneously believed to be the cystic duct, was deliberately cut. This stemmed from an illusion of object form due to a specific uncommon configuration of the structures and the heuristic nature (unconscious assumptions) of human visual perception. The videotapes showed the persuasiveness of the illusion, and many operative reports described the operation as routine. Class II injuries resulted from a dissection too close to the common hepatic duct. Fundamentally an illusion, it was contributed to in some instances by working too deep in the triangle of Calot. Conclusions These data show that errors leading to laparoscopic bile duct injuries stem principally from misperception, not errors of skill, knowledge, or judgment. The misperception was so compelling that in most cases the surgeon did not

  14. Invasive thyroglossal duct cyst papillary carcinoma: a case report

    Directory of Open Access Journals (Sweden)

    Aghaghazvini Shirin

    2009-12-01

    Full Text Available Abstract Introduction A thyroglossal duct cyst is the most common congenital anomaly of the thyroid gland and midline masses in childhood (70% abnormality in childhood, 7% in adult. Carcinomas arising from a thyroglossal duct cyst are rare (only 1% of thyroglossal duct cyst cases and characterized by relatively non-aggressive behavior and rare lymphatic spread. They are also diagnosed mostly during the third and fourth decades of life. About 85% to 92% of all thyroglossal duct cyst carcinomas are papillary carcinomas. Case presentation We present the case of a 44-year-old Iranian woman with Cacausian ethnicity with a painless anterior neck mass that appeared gradually over three months. She had a history of frequent painful swelling of the anterior part of her neck, which subsided with antibiotic therapy. Thyroid functional tests were normal and a thyroid scinitigraphy showed a cold nodule in the left lobe of her thyroid. A computed tomography scan revealed a large, heterogeneous enhancing soft tissue mass with cystic components in the midline of the anterior neck space. This extended from the base of the tongue,(completely separated from its muscles, to the inferior aspect of the thyroid gland and showed the destruction of the hyoid bone and the thyroid cartilage. The diagnosis of a thyroglossal duct cyst with malignant transformation was maintained. A fine needle aspiration revealed papillary carcinoma. Conclusion This patient's case is presented because of its rare, aggressive, and invasive nature and rare and unusual manifestation, as well as its rapid increase in size, the destruction of the hyoid bone, chondrolysis of the thyroid cartilage, lymph adenopathy and the existence of a cold nodule in the thyroid gland.

  15. Escaping from Flatland: clinical and biological aspects of human mammary duct anatomy in three dimensions.

    Science.gov (United States)

    Going, James J; Moffat, David F

    2004-05-01

    Accurate knowledge of breast duct anatomy in three dimensions is needed to understand normal breast development, how intraepithelial neoplasia may spread through a breast, and the potential for diagnostic and therapeutic access to breast parenchyma via the nipple. This paper reports three related exploratory studies. In study 1, the median number of milk-collecting ducts in the nipple was determined in 72 breasts excised for cancer; in study 2, the volumes of all 20 complete duct systems ("lobes") in an autopsy breast were measured from 2 mm serial "subgross" sections; and in study 3, a 3D digital model of all collecting ducts in a mastectomy nipple was made from 68 100 micro m serial sections. The mastectomy nipples contained 11-48 central ducts (median 27, inter-quartile range 21-30). In the autopsy breast, the largest "lobe" drained 23% of breast volume; half of the breast was drained by three ducts and 75% by the largest six. Conversely, eight small duct systems together accounted for only 1.6% of breast volume. The 3D model of the nipple revealed three distinct nipple duct populations. Seven ducts maintained a wide lumen up to the skin surface (population A); 20 ducts tapered to a minute lumen at their origin in the vicinity of skin appendages (population B) on the apex of the nipple; and a minor duct population (C) arose around the base of the papilla. Major variations in duct morphology and extent define highly variable territories in which intraepithelial neoplasia could grow. While population A ducts appear accessible to duct endoscopy or lavage, population B and population C ducts may be less accessible. Copyright 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  16. Spontaneous perforation of the bile duct in a neonate: Drainage or resection?

    Directory of Open Access Journals (Sweden)

    Te-Zhung Chen

    2012-07-01

    Full Text Available Spontaneous perforation of the bile duct is a rare disease, and delayed diagnosis without optimal treatment can be fatal. Abdominal drainage with or without repair of perforation seems to be adequate in most case series. We report on a 10-day-old female neonate with spontaneous perforation of the bile duct over the junction of cystic duct and common hepatic duct, who recovered uneventfully with follow-up for 3 years after receiving a single-stage operation of cholecystectomy and biliary reconstruction. Drainage only or resection of the gall bladder or bile duct should depend on the patient's clinical conditions and intraoperative findings.

  17. Acute pancreatitis after thoracic duct ligation for iatrogenic chylothorax. A case report.

    Science.gov (United States)

    Bédat, Benoît; Scarpa, Cosimo Riccardo; Sadowski, Samira Mercedes; Triponez, Frédéric; Karenovics, Wolfram

    2017-01-23

    To report the association between thoracic duct ligation and acute pancreatitis. The association between sudden stop of lymphatic flow and pancreatitis has been established in experimental models. A 57-year-old woman operated for thymoma presented a iatrogenic chylothorax. After thoracic duct ligation, she presented an acute pancreatitis which resolved after conservative treatment. The chylothorax disappeared within 4 days of thoracic duct ligation. This is the first report of acute pancreatitis following thoracic duct ligation. The pancreas and digestive tract should be assessed in symptomatic patients after thoracic duct ligation.

  18. Recompletion by horizontal drilling pays off

    Energy Technology Data Exchange (ETDEWEB)

    Holifield, R.H.; Rehm, B.

    1989-03-01

    More than 20 wells have been recompleted in the Giddings field by drilling a new, horizontal interval from existing 5 1/2-in. cased wells for distances of 300 to 1,250 ft. Recompleting existing wells is much cheaper than drilling a new well. Plus, the new completions, overall, produce better. The horizontal wells are routinely profitable now, and pay out occurs in 3 to 24 months. During this program, the techniques for slim-hole- medium-radius, horizontal drilling in Giddings have been mastered and costs have dropped 75%. It is believed that this program may be the first (or among the first) continuing horizontal project drilled out of cased wells with repeatable profitability as opposed to projected viability.

  19. Productivity and injectivity of horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Khalid

    2000-03-06

    One of the key issues addressed was pressure drop in long horizontal wells and its influence on well performance. Very little information is available in the literature on flow in pipes with influx through pipe walls. Virtually all of this work has been in small diameter pipes and with single-phase flow. In order to address this problem new experimental data on flow in horizontal and near horizontal wells have been obtained. Experiments were conducted at an industrial facility on typical 6 1/8 ID, 100 feet long horizontal well model. The new data along with available information in the literature have been used to develop new correlations and mechanistic models. Thus it is now possible to predict, within reasonable accuracy, the effect of influx through the well on pressure drop in the well.

  20. Redefining the surface anatomy of the parotid duct: an in vivo ultrasound study.

    Science.gov (United States)

    Stringer, Mark D; Mirjalili, S Ali; Meredith, Susan J; Muirhead, Jill C

    2012-11-01

    The surface anatomy of the parotid duct is important when assessing facial lacerations and in facial rejuvenation surgery but is inconsistently described in reference texts. The aim of this study was to map the surface anatomy of the adult parotid duct using ultrasound. Fifty healthy adults (31 women; mean age, 33 years) were scanned by an experienced sonographer using a 13-5 MHz linear probe and a Siemens Sonoline Antares ultrasound machine. The caliber, length, and course of the parotid duct were recorded bilaterally. The parotid duct was identified bilaterally in all participants. One subject had a double duct bilaterally. In the remaining 49 individuals (98 ducts), the duct had a mean maximum internal caliber of 0.6 ± 0.2 mm and length 42 ± 7.5 mm. Ninety-two (94 percent) ducts were below the most popular surface marking, which is reported as a line between the lower border of the tragus and mid philtrum. In 93 percent of individuals, the duct was within 1.5 cm of the middle half of a line between the lower border of the tragus and cheilion. A more accurate description of the surface anatomy of the parotid duct should assist with early diagnosis of parotid duct injuries and avoidance of iatrogenic injury. Diagnostic, IV.