WorldWideScience

Sample records for acoustic ducts

  1. Nonlinear acoustic propagation in rectangular ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    The method of multiple scales is used to obtain a second-order uniformly valid expansion for nonlinear acoustic wave propagation in a rectangular duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear materials attenuate sound more than linear materials except at high acoustic frequencies. The nonlinear materials produce higher and combination tones which have higher attenuation rates than the fundamentals. Moreover, the attenuation rates of the fundamentals increase with increasing amplitude.

  2. Inverse potential scattering in duct acoustics.

    Science.gov (United States)

    Forbes, Barbara J; Pike, E Roy; Sharp, David B; Aktosun, Tuncay

    2006-01-01

    The inverse problem of the noninvasive measurement of the shape of an acoustical duct in which one-dimensional wave propagation can be assumed is examined within the theoretical framework of the governing Klein-Gordon equation. Previous deterministic methods developed over the last 40 years have all required direct measurement of the reflectance or input impedance but now, by application of the methods of inverse quantum scattering to the acoustical system, it is shown that the reflectance can be algorithmically derived from the radiated wave. The potential and area functions of the duct can subsequently be reconstructed. The results are discussed with particular reference to acoustic pulse reflectometry.

  3. Acoustic energy in ducts - Further observations

    Science.gov (United States)

    Eversman, W.

    1979-01-01

    The transmission of acoustic energy in uniform ducts carrying uniform flow is investigated with the purpose of clarifying two points of interest. The two commonly used definitions of acoustic 'energy' flux are shown to be related by a Legendre transformation of the Lagrangian density exactly as in deriving the Hamiltonian density in mechanics. In the acoustic case the total energy density and the Hamiltonian density are not the same which accounts for two different 'energy' fluxes. When the duct has acoustically absorptive walls neither of the two flux expressions gives correct results. A reevaluation of the basis of derivation of the energy density and energy flux provides forms which yield consistent results for soft walled ducts.

  4. 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.

  5. The acoustics of aircraft engine-duct systems

    Science.gov (United States)

    Nayfeh, A. H.; Kaiser, J. E.; Telionis, D. P.

    1973-01-01

    Noise generated in aircraft engines is usually suppressed by acoustically treating the engine ducts. The optimization of this treatment requires an understanding of the transmission and attenuation of the acoustic waves. A critical review is presented of the state of the art regarding methods of determining the transmission and attenuation parameters and the effect on these parameters of (1) acoustic properties of liners, (2) the mean velocity, including uniform and shear profiles and nonparallel flow, (3) axial and transverse temperature gradients, (4) slowly and abruptly varying cross sections, and (5) finite-amplitude waves and nonlinear duct liners.

  6. Acoustic propagation in partially choked converging-diverging ducts

    Science.gov (United States)

    Kelly, J. J.; Nayfeh, A. H.; Watson, L. T.

    1982-01-01

    A computer model based on the wave-envelope technique is used to study acoustic propagation in converging-diverging hard walled and lined circular ducts carrying near sonic mean flows. The influences of the liner admittance, boundary layer thickness, spinning mode number, and mean Mach number are considered. The numerical results indicate that the diverging portion of the duct can have a strong reflective effect for partially choked flows.

  7. Nonlinear acoustic propagation in two-dimensional ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    The method of multiple scales is used to obtain a second-order uniformly valid expansion for the nonlinear acoustic wave propagation in a two-dimensional duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear effects tend to flatten and broaden the absorption versus frequency curve, in qualitative agreement with the experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.

  8. Acoustic propagation in ducts with varying cross sections

    Science.gov (United States)

    Nayfeh, A. H.; Telionis, D. P.

    1973-01-01

    The method of multiple scales is used to derive the equations that describe the spatial and temporal variation of the amplitudes and phases of a wave packet propagating in slowly varying hard-walled or lined ducts. The analysis is carried out for rectangular as well as circular ducts. These equations are statements of the conservation of energy. For large admittance or high-frequency modes, an approximate expression is obtained for the attenuation. This expression shows that all possible acoustic modes are attenuating. The results also show that decreasing the cross sectional area can lead to elimination of some of the acoustic modes.

  9. Propagation of spinning acoustic modes in partially choked converging ducts

    Science.gov (United States)

    Nayfeh, A. H.; Kelly, J. J.; Watson, L. T.

    1982-01-01

    A computer model based on the wave-envelope technique is used to study the propagation of spinning acoustic modes in converging hard-walled and lined circular ducts carrying near sonic mean flows. The results show that with increasing spinning mode number the intensification of the acoustic signal at the throat decreases for upstream propagation. The influence of the throat Mach number, frequency, boundary-layer thickness, and liner admittance on the propagation of spinning modes is considered.

  10. Non-linear wave propagation in acoustically lined circular ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    An analysis is presented of the nonlinear effects of the gas motion as well as of the acoustic lining material on the transmission and attenuation of sound in a circular duct with a uniform cross-section and no mean flow. The acoustic material is characterized by an empirical, nonlinear impedance in which the instantaneous resistance is a nonlinear function of both the frequency and the acoustic velocity. The results show that there exist frequency bandwidths around the resonant frequencies in which the nonlinearity decreases the attenuation rate, and outside which the nonlinearity increases the attenuation rate, in qualitative agreement with experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.

  11. A general mapping procedure for variable area duct acoustics

    Science.gov (United States)

    White, J. W.

    1981-01-01

    A general mapping procedure is described and applied to the study of noise propagation in variable area ducts. The mapping provides a boundary fitted co-ordinate system which is ideal for the finite difference solution of acoustic fields with irregular boundaries, without the burden of large matrices required by finite element methods. The procedure is first described in general and then applied to a particular two-dimensional geometry under current experimental investigation. This method should be ideally suited to the study of high frequency noise propagation in variable area ducts and in cases where the far field is included in the calculation procedure. Moreover, the current approach can be directly extended to three-dimensions, resulting in numerical calculation over a rectangular parallelepiped in the transformed plane.

  12. Effect of flow on the acoustic resonances of an open-ended duct

    Science.gov (United States)

    Ingard, U.; Singhal, V. K.

    1975-01-01

    The effect of flow on the acoustic resonances of an open-ended, hard-walled duct is analyzed. The flow produces acoustic losses both in the interior of the duct and at the ends. Unless the duct is very long, typically 100 times the diameter, the losses at the ends dominate. At flow Mach numbers in excess of 0.4 the losses are so large that axial duct resonances are almost completely suppressed. The plane-wave Green's function for the duct with flow is expressed in terms of the (experimentally determined) pressure reflection coefficients at the ends of the duct, and the flow dependence of the complex eigenfrequencies of the duct is obtained. Some observations concerning the noise produced by the flow in the duct are also reported.

  13. Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

    Directory of Open Access Journals (Sweden)

    Hiroshi Kobayashi

    2011-01-01

    Full Text Available This paper describes the development of adaptive acoustic impedance control (AAC technologies to achieve a larger fan noise reduction, by adaptively adjusting reactance and resistance of the acoustic liner impedance. For the actual proof of the AAC technology III performance, the advanced fan noise absorption control duct liner II was made on trial basis, with the simple control system and the plain device. And, then, the duct liner II was examined for the AAC technology I, II, and III models, using the high speed fan test facility. The test results made clear that the duct liner II of the AAC technology III model could achieve the fan noise reduction higher than O.A. SPL 10 dB (A at the maximum fan speed 6000 rpm, containing the reduction of fundamental BPF tone of 18 dB and 2nd BPF tone of 10 dB in response to the fan peed change from 3000 to 6000 rpm.

  14. Acoustic theory of axisymmetric multisectioned ducts. [reduction of turbofan engine noise

    Science.gov (United States)

    Zorumski, W. E.

    1974-01-01

    Equations are developed for the acoustic field in a duct system which is made up of a number of connected circular and annular ducts. These equations are suitable for finding the acoustic field inside of and radiated from an aircraft turbofan engine. Acoustic modes are used as generalized coordinates in order to develop a set of matrix equations for the acoustic field. Equations for these modes are given for circular and annular ducts with uniform flow. Modal source equations are derived for point acoustic sources. General equations for mode transmission and reflection are developed and detailed equations are derived for ducts with multiple sections of acoustic treatment and for ducts with circumferential splitter rings. The general theory is applied to the special case of a uniform area circular duct with multisection liners and it is shown that the mode reflection effects are proportional to differences of the acoustic admittances of adjacent liners. A numerical example is given which shows that multisection liners may provide greater noise suppression than uniform liners.

  15. Acoustic modeling of fan noise generation and scattering in a modular duct system

    NARCIS (Netherlands)

    Nijhof, Marten; Beltman, Marco; Wijnant, Ysbrand; Boer, de André

    2005-01-01

    Fan noise is an important noise source in computers. The noise spectrum of fans contains tonal noise, found at the so-called Blade Passing Frequency (BPF) and its higher harmonics, that plays an important role in the perceived sound quality. An acoustic resonator integrated in the duct of an in-duct

  16. Effects of Inlet/Outlet Ducts on Acoustic Attenuation Characteristics of Circular Expansion Chambers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-bo; GE Yun-shan; JI Zhen-lin; ZHANG Wen-ping; SONG Yan-rong; HAN Xiu-kun; ZHANG Xue-min

    2006-01-01

    The effect of coaxial, offset and extended inlet/outlet on the acoustic attenuation characteristics of circular expansion chambers are studied by the three-dimensional finite element method. The numerical results of transmission loss are compared with experiment results to verify the necessary of using three-dimensional methods. Maps of acoustic pressure level distribution inside of chambers and inlet/outlet ducts are given at a frequency to demonstrate the difference of acoustic wave propagation behavior caused by locations of inlet/outlet ducts. For the chambers of the same length, the chamber with extended inlet/outlet duct has higher attenuation ability than coaxial and offset inlet/outlet duct over middle frequencies.

  17. Numerical study of acoustic modes in ducted shear flow

    Science.gov (United States)

    Vilenski, Gregory G.; Rienstra, Sjoerd W.

    2007-11-01

    The propagation of small-amplitude modes in an inviscid but sheared mean flow inside a duct is studied numerically. For isentropic flow in a circular duct with zero swirl and constant mean flow density the pressure modes are described in terms of the eigenvalue problem for the Pridmore-Brown equation. Since for sufficiently high Helmholtz and wavenumbers, which are of great interest for applications, the field equation is inherently stiff, special care is taken to insure the stability of the numerical algorithm designed to tackle this problem. The accuracy of the method is checked against the well-known analytical solution for uniform flow. The numerical method is shown to be consistent with the analytical predictions at least for Helmholtz numbers up to 100 and circumferential wavenumbers as large as 50, typical Mach numbers being up to 0.65. In order to gain further insight into the possible structure of the modal solutions and to obtain an independent verification of the robustness of the numerical scheme, comparison to the asymptotic solution of the problem based on the WKB method is performed. The asymptotic solution is also used as a benchmark for computations with high Helmholtz numbers, where numerical solutions of other authors are not available. The bulk of the analysis concentrates on the influence of the wall lining. The proposed numerical procedure is adapted in order to include Ingard-Myers boundary conditions. In parallel with this, the WKB solution is used to check the numerical predictions of the typical behaviour of the axial wavenumber in the complex plane, when the wall impedance varies in the complex plane. Numerical analysis of the problem with zero mean flow at the wall and acoustic lining shows that the use of Ingard-Myers condition in combination with an appropriate slip-stream approximation instead of the actual no-slip mean flow profile gives valid results in the limit of vanishing boundary-layer thickness, although the boundary layer

  18. Acoustic propagation in ducts with varying cross sections and sheared mean flow.

    Science.gov (United States)

    Nayfeh, A. H.; Telionis, D. P.; Lekoudis, S. G.

    1973-01-01

    An analysis is presented of the wave propagation and attenuation in two-dimensional ducts with slowly varying cross sections which carry sheared mean flow. A uniformly valid asymptotic expansion of the acoustic waves is obtained in terms of the maximum slope of the wall by using the method of multiple scales. The result is a first-order differential equation describing the amplitude variation with the axial distance. This equation is used to evaluate the effects of variations of the duct cross section and growing boundary layers on the different acoustic modes.

  19. A feasibility study of a 3-D finite element solution scheme for aeroengine duct acoustics

    Science.gov (United States)

    Abrahamson, A. L.

    1980-01-01

    The advantage from development of a 3-D model of aeroengine duct acoustics is the ability to analyze axial and circumferential liner segmentation simultaneously. The feasibility of a 3-D duct acoustics model was investigated using Galerkin or least squares element formulations combined with Gaussian elimination, successive over-relaxation, or conjugate gradient solution algorithms on conventional scalar computers and on a vector machine. A least squares element formulation combined with a conjugate gradient solver on a CDC Star vector computer initially appeared to have great promise, but severe difficulties were encountered with matrix ill-conditioning. These difficulties in conditioning rendered this technique impractical for realistic problems.

  20. Transmission of wave energy in curved ducts. [acoustic propagation within rigid walls

    Science.gov (United States)

    Rostafinski, W.

    1974-01-01

    Investigation of the ability of circular bends to transmit acoustic energy flux. A formulation of wave-energy flow is developed for motion in curved ducts. A parametric study over a range of frequencies shows the ability of circular bends to transmit energy in the case of perfectly rigid walls.

  1. Acoustic propagation within a surface duct in the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Navelkar, G.S.; Murty, T.V.R.; Murty, C.S.

    Sound speed structure forms a surface duct in the upper 50 m layer in the western Bay of Bengal during late July. A range-dependent acoustic ray computation shows that some rays emanating from a source within the upper 30 m, get trapped within...

  2. Three-dimensional coupled mode analysis of internal-wave acoustic ducts.

    Science.gov (United States)

    Shmelev, Alexey A; Lynch, James F; Lin, Ying-Tsong; Schmidt, Henrik

    2014-05-01

    A fully three-dimensional coupled mode approach is used in this paper to describe the physics of low frequency acoustic signals propagating through a train of internal waves at an arbitrary azimuth. A three layer model of the shallow water waveguide is employed for studying the properties of normal modes and their coupled interaction due to the presence of nonlinear internal waves. Using a robust wave number integration technique for Fourier transform computation and a direct global matrix approach, an accurate three-dimensional coupled mode full field solution is obtained for the tonal signal propagation through straight and parallel internal waves. This approach provides accurate results for arbitrary azimuth and includes the effects of backscattering. This enables one to provide an azimuthal analysis of acoustic propagation and separate the effects of mode coupled transparent resonance, horizontal reflection and refraction, the horizontal Lloyd's mirror, horizontal ducting and anti-ducting, and horizontal tunneling and secondary ducting.

  3. Effect of the acoustic boundary layer on the wave propagation in ducts

    Science.gov (United States)

    Nayfeh, A. H.

    1973-01-01

    An analysis is presented for the wave propagation in two-dimensional and circular lined ducts taking into account the effects of viscosity in both the mean and the acoustic problems. The method of composite expansions is used to express each acoustic flow quantity as the sum of an inviscid part and a boundary layer part insignificant outside a thin layer next to the wall. The problem is reduced to solving a second-order ordinary differential equation for the pressure perturbation as in the inviscid acoustic case but with a modified specific wall admittance. An analytic expression is presented for the variation of the modified admittance with the wall and flow parameters, such as the acoustic boundary layer thickness, the mean velocity and temperature gradients at the wall, the frequency of oscillation, and the wavelength.

  4. Duct wall impedance control as an advanced concept for acoustic suppression enhancement. [engine noise reduction

    Science.gov (United States)

    Dean, P. D.

    1978-01-01

    A systems concept procedure is described for the optimization of acoustic duct liner design for both uniform and multisegment types. The concept was implemented by the use of a double reverberant chamber flow duct facility coupled with sophisticated computer control and acoustic analysis systems. The optimization procedure for liner insertion loss was based on the concept of variable liner impedance produced by bias air flow through a multilayer, resonant cavity liner. A multiple microphone technique for in situ wall impedance measurements was used and successfully adapted to produce automated measurements for all liner configurations tested. The complete validation of the systems concept was prevented by the inability to optimize the insertion loss using bias flow induced wall impedance changes. This inability appeared to be a direct function of the presence of a higher order energy carrying modes which were not influenced significantly by the wall impedance changes.

  5. High accuracy acoustic relative humidity measurement in duct flow with air

    OpenAIRE

    Cees van der Geld; Twan Wernaart; Mart Grooten; Wilhelm van Schaik

    2010-01-01

    An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0–12 m/s with an error of ±0.13 m/s, temp...

  6. A hybrid method for determination of the acoustic impedance of an unflanged cylindrical duct for multimode wave

    Science.gov (United States)

    Snakowska, Anna; Jurkiewicz, Jerzy; Gorazd, Łukasz

    2017-05-01

    The paper presents derivation of the impedance matrix based on the rigorous solution of the wave equation obtained by the Wiener-Hopf technique for a semi-infinite unflanged cylindrical duct. The impedance matrix allows, in turn, calculate the acoustic impedance along the duct and, as a special case, the radiation impedance. The analysis is carried out for a multimode incident wave accounting for modes coupling on the duct outlet not only qualitatively but also quantitatively for a selected source operating inside. The quantitative evaluation of the acoustic impedance requires setting of modes amplitudes which has been obtained applying the mode decomposition method to the far-field pressure radiation measurements and theoretical formulae for single mode directivity characteristics for an unflanged duct. Calculation of the acoustic impedance for a non-uniform distribution of the sound pressure and the sound velocity on a duct cross section requires determination of the acoustic power transmitted along/radiated from a duct. In the paper, the impedance matrix, the power, and the acoustic impedance were derived as functions of Helmholtz number and distance from the outlet.

  7. Tunnelling effects for acoustic waves in slowly varying axisymmetric flow ducts

    Science.gov (United States)

    Nielsen, R. B.; Peake, N.

    2016-10-01

    The multiple-scales Wentzel-Kramers-Brillouin (WKB) approximation is used to model the propagation of acoustic waves in an axisymmetric duct with a constriction in the presence of mean flow. An analysis of the reflection/transmission process of modes tunnelling through the constriction is conducted, and the key mathematical feature is the presence of two turning points, located at either real axial locations or in the complex plane. The resulting asymptotic solution consists of WKB solutions in regions away from the constriction and an inner solution valid in the near vicinity of the constriction. A solution which is uniformly valid throughout the duct is also derived. A range of test cases are considered, and the importance of accounting for the inner region, even in cases in which the turning points lie away from the real axis, is demonstrated.

  8. Influence of exit impedance on finite difference solutions of transient acoustic mode propagation in ducts

    Science.gov (United States)

    Baumeister, K. J.

    1981-01-01

    The cutoff mode instability problem associated with a transient finite difference solution to the wave equation is explained. The steady-state impedance boundary condition is found to produce acoustic reflections during the initial transient, which cause finite instabilities in the cutoff modes. The stability problem is resolved by extending the duct length to prevent transient reflections. Numerical calculations are presented at forcing frequencies above, below, and nearly at the cutoff frequency, and exit impedance models are presented for use in the practical design of turbofan inlets.

  9. Global modes, receptivity, and sensitivity analysis of diffusion flames coupled with duct acoustics

    CERN Document Server

    Magri, Luca

    2014-01-01

    In this theoretical and numerical paper, we derive the adjoint equations for a thermo-acoustic system consisting of an infinite-rate chemistry diffusion flame coupled with duct acoustics. We then calculate the thermo-acoustic system's linear global modes (i.e. the frequency/growth rate of oscillations, together with their mode shapes), and the global modes' receptivity to species injection, sensitivity to base-state perturbations, and structural sensitivity to advective-velocity perturbations. We then compare these with the Rayleigh index. The receptivity analysis shows the regions of the flame where open-loop injection of fuel or oxidizer will have most influence on the thermo-acoustic oscillation. We find that the flame is most receptive at its tip. The base-state sensitivity analysis shows the influence of each parameter on the frequency/growth rate. We find that perturbations to the stoichiometric mixture fraction, the fuel slot width, and the heat-release parameter have most influence, while perturbation...

  10. Optimal virtual sensing for active noise control in a rigid-walled acoustic duct

    Science.gov (United States)

    Petersen, Dick; Zander, Anthony C.; Cazzolato, Ben S.; Hansen, Colin H.

    2005-11-01

    The performance of local active noise control systems is generally limited by the small sizes of the zones of quiet created at the error sensors. This is often exacerbated by the fact that the error sensors cannot always be located close to an observer's ears. Virtual sensing is a method that can move the zone of quiet away from the physical location of the transducers to a desired location, such as an observer's ear. In this article, analytical expressions are derived for optimal virtual sensing in a rigid-walled acoustic duct with arbitrary termination conditions. The expressions are derived for tonal excitations, and are obtained by employing a traveling wave model of a rigid-walled acoustic duct. It is shown that the optimal solution for the virtual sensing microphone weights is independent of the source location and microphone locations. It is also shown that, theoretically, it is possible to obtain infinite reductions at the virtual location. The analytical expressions are compared with forward difference prediction techniques. The results demonstrate that the maximum attenuation, that theoretically can be obtained at the virtual location using forward difference prediction techniques, is expected to decrease for higher excitation frequencies and larger virtual distances.

  11. High accuracy acoustic relative humidity measurement in duct flow with air.

    Science.gov (United States)

    van Schaik, Wilhelm; Grooten, Mart; Wernaart, Twan; van der Geld, Cees

    2010-01-01

    An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0-12 m/s with an error of ± 0.13 m/s, temperature 0-100 °C with an error of ± 0.07 °C and relative humidity 0-100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments.

  12. Concurrent identification of aero-acoustic scattering and noise sources at a flow duct singularity in low Mach number flow

    Science.gov (United States)

    Sovardi, Carlo; Jaensch, Stefan; Polifke, Wolfgang

    2016-09-01

    A numerical method to concurrently characterize both aeroacoustic scattering and noise sources at a duct singularity is presented. This approach combines Large Eddy Simulation (LES) with techniques of System Identification (SI): In a first step, a highly resolved LES with external broadband acoustic excitation is carried out. Subsequently, time series data extracted from the LES are post-processed by means of SI to model both acoustic propagation and noise generation. The present work studies the aero-acoustic characteristics of an orifice placed in a duct at low flow Mach numbers with the "LES-SI" method. Parametric SI based on the Box-Jenkins mathematical structure is employed, with a prediction error approach that utilizes correlation analysis of the output residuals to avoid overfitting. Uncertainties of model parameters due to the finite length of times series are quantified in terms of confidence intervals. Numerical results for acoustic scattering matrices and power spectral densities of broad-band noise are validated against experimental measurements over a wide range of frequencies below the cut-off frequency of the duct.

  13. Numerical study of acoustic instability in a partly lined flow duct using the full linearized Navier-Stokes equations

    Science.gov (United States)

    Xin, Bo; Sun, Dakun; Jing, Xiaodong; Sun, Xiaofeng

    2016-07-01

    Lined ducts are extensively applied to suppress noise emission from aero-engines and other turbomachines. The complex noise/flow interaction in a lined duct possibly leads to acoustic instability in certain conditions. To investigate the instability, the full linearized Navier-Stokes equations with eddy viscosity considered are solved in frequency domain using a Galerkin finite element method to compute the sound transmission in shear flow in the lined duct as well as the flow perturbation over the impedance wall. A good agreement between the numerical predictions and the published experimental results is obtained for the sound transmission, showing that a transmission peak occurs around the resonant frequency of the acoustic liner in the presence of shear flow. The eddy viscosity is an important influential factor that plays the roles of both providing destabilizing and making coupling between the acoustic and flow motions over the acoustic liner. Moreover, it is shown from the numerical investigation that the occurrence of the sound amplification and the magnitude of transmission coefficient are closely related to the realistic velocity profile, and we find it essential that the actual variation of the velocity profile in the axial direction over the liner surface be included in the computation. The simulation results of the periodic flow patterns possess the proper features of the convective instability over the liner, as observed in Marx et al.'s experiment. A quantitative comparison between numerical and experimental results of amplitude and phase of the instability is performed. The corresponding eigenvalues achieve great agreement.

  14. A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges.

    Science.gov (United States)

    Kierkegaard, Axel; Boij, Susann; Efraimsson, Gunilla

    2010-02-01

    Acoustic wave propagation in flow ducts is commonly modeled with time-domain non-linear Navier-Stokes equation methodologies. To reduce computational effort, investigations of a linearized approach in frequency domain are carried out. Calculations of sound wave propagation in a straight duct are presented with an orifice plate and a mean flow present. Results of transmission and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement. The wave propagation is modeled with a frequency domain linearized Navier-Stokes equation methodology. This methodology is found to be efficient for cases where the acoustic field does not alter the mean flow field, i.e., when whistling does not occur.

  15. Identification of acoustic wave propagation in a duct line and its application to detection of impact source location based on signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Yong Woo; Kim, Min Soo; Lee, Sang Kwon [Inha University, Seoul (Korea, Republic of)

    2010-12-15

    For the detection of the impact location in a pipeline system, the correlation method has been the conventional method. For the application of the correlation method, the diameter of a duct should be small so that the acoustic wave inside the duct can propagate with nondispersive characteristics, in the form of, for example, a plane wave. This correlation method calculates the cross-correlation between acoustic waves measured at two acceleration sensors attached to a buried duct. It also gives information about the arrival time delay of an acoustic wave between two sensors. These arrival time delays are used for the estimation of the impact location. However, when the diameter of the duct is large, the acoustic waves inside the duct propagate with dispersive characteristics owing to the reflection of the acoustic wave off of the wall of the duct. This dispersive characteristic is related to the acoustic modes inside a duct. Therefore, the correlation method does not work correctly for the detection of the impact location. This paper proposes new methods of accurately measuring the arrival time delay between two sensors attached to duct line system. This method is based on the time-frequency analyses of the short time Fourier transform (STFT) and continuous wavelet transform (CWT). These methods can discriminate direct waves (non-dispersive waves) and reflective waves (dispersive waves) from the measured wave signals through the time-frequency analysis. The direct wave or the reflective wave is used to estimate the arrival time delay. This delay is used for the identification of the impact location. This systematic method can predict the impact location due to the impact forces of construction equipment with more accuracy than the correlation method

  16. Intensification and refraction of acoustical signals in partially choked converging ducts

    Science.gov (United States)

    Nayfeh, A. H.

    1980-01-01

    A computer code based on the wave-envelope technique is used to perform detailed numerical calculations for the intensification and refraction of sound in converging hard walled and lined circular ducts carrying high mean Mach number flows. The results show that converging ducts produce substantial refractions toward the duct center for waves propagating against near choked flows. As expected, the magnitude of the refraction decreases as the real part of the admittance increases. The pressure wave pattern is that of interference among the different modes, and hence the variation of the magnitude of pressure refraction with frequency is not monotonic.

  17. Modified-filtered-u LMS algorithm for active noise control and its application to a short acoustic duct

    Science.gov (United States)

    Kim, Ho-Wuk; Park, Hong-Sug; Lee, Sang-Kwon; Shin, Kihong

    2011-01-01

    This paper presents a new adaptive algorithm for active noise control (ANC) that can be effectively applicable to a short acoustic duct, such as the intake system of an automobile engine, where the stability and fast convergence of the ANC system is particularly important. The new algorithm, called the modified-filtered-u LMS algorithm (MFU-LMS), is developed based on the recursive filtered-u LMS algorithm (FU-LMS) incorporating the simple hyper-stable adaptive recursive filter (SHARF) to ensure the control stability and the variable step size to enhance the convergence rate. The MFU-LMS algorithm is implemented by purely experimental ways, and is applied to active control of noise in a short acoustic duct, and is validated using two experimental cases of which the primary noise sources are a sinusoidal signal embedded in white noise and a chirp signal. The experimental results demonstrate that the proposed MFU-LMS algorithm gives a considerably better performance than other conventional algorithms, such as the filtered-x LMS (FX-LMS) and the FU-LMS algorithms.

  18. Acoustic plane waves normally incident on a clamped panel in a rectangular duct. [to explain noise reduction curves for reducing interior noise in aircraft

    Science.gov (United States)

    Unz, H.; Roskam, J.

    1979-01-01

    The theory of acoustic plane wave normally incident on a clamped panel in a rectangular duct is developed. The coupling theory between the elastic vibrations of the panel (plate) and the acoustic wave propagation in infinite space and in the rectangular duct is considered. The partial differential equation which governs the vibration of the panel (plate) is modified by adding to its stiffness (spring) forces and damping forces, and the fundamental resonance frequency and the attenuation factor are discussed. The noise reduction expression based on the theory is found to agree well with the corresponding experimental data of a sample aluminum panel in the mass controlled region, the damping controlled region, and the stiffness controlled region. All the frequency positions of the upward and downward resonance spikes in the sample experimental data are identified theoretically as resulting from four cross interacting major resonance phenomena: the cavity resonance, the acoustic resonance, the plate resonance, and the wooden back panel resonance.

  19. On the one-dimensional acoustic propagation in conical ducts with stationary mean flow.

    Science.gov (United States)

    Barjau, Ana

    2007-12-01

    This paper proposes a direct time-domain calculation of the time-domain responses of anechoic conical tubes with steady weak mean flow. The starting point is the approximated linear one-dimensional wave equation governing the velocity potential for the case of steady flow with low Mach number. A traveling solution with general space-dependent propagation velocity is then proposed from which the inward and outward pressure and velocity impulse responses can be obtained. The results include the well-known responses of conical and cylindrical ducts with zero mean flow.

  20. 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.

  1. Computational Aerodynamic Simulations of an 840 ft/sec Tip Speed Advanced Ducted Propulsor Fan System Model for Acoustic Methods Assessment and Development

    Science.gov (United States)

    Tweedt, Daniel L.

    2014-01-01

    Computational Aerodynamic simulations of an 840 ft/sec tip speed, Advanced Ducted Propulsor fan system were performed at five different operating points on the fan operating line, in order to provide detailed internal flow field information for use with fan acoustic prediction methods presently being developed, assessed and validated. The fan system is a sub-scale, lownoise research fan/nacelle model that has undergone extensive experimental testing in the 9- by 15- foot Low Speed Wind Tunnel at the NASA Glenn Research Center, resulting in quality, detailed aerodynamic and acoustic measurement data. Details of the fan geometry, the computational fluid dynamics methods, the computational grids, and various computational parameters relevant to the numerical simulations are discussed. Flow field results for three of the five operating conditions simulated are presented in order to provide a representative look at the computed solutions. Each of the five fan aerodynamic simulations involved the entire fan system, excluding a long core duct section downstream of the core inlet guide vane. As a result, only fan rotational speed and system bypass ratio, set by specifying static pressure downstream of the core inlet guide vane row, were adjusted in order to set the fan operating point, leading to operating points that lie on a fan operating line and making mass flow rate a fully dependent parameter. The resulting mass flow rates are in good agreement with measurement values. The computed blade row flow fields for all five fan operating points are, in general, aerodynamically healthy. Rotor blade and fan exit guide vane flow characteristics are good, including incidence and deviation angles, chordwise static pressure distributions, blade surface boundary layers, secondary flow structures, and blade wakes. Examination of the computed flow fields reveals no excessive boundary layer separations or related secondary-flow problems. A few spanwise comparisons between

  2. Noise reduction of spiral ducts.

    Science.gov (United States)

    Lapka, Wojciech; Cempel, Czesław

    2007-01-01

    The paper presents noise reduction (NR) of spiral ducts as a result of computational modeling of acoustic wave propagation. Three-dimensional models were created with the finite element method in COMSOL Multiphysics version 3.3. Nine models of spiral ducts with 1-9 spiral leads were considered. Time-harmonic analysis was used to predict NR, which was shown in spectral and interval frequency bands. Spiral duct performance can be seen as a comparison of NR before and after a change from a circular to a spiral duct.

  3. Algebraically growing waves in ducts with sheared mean flow

    Science.gov (United States)

    Nayfeh, A. H.; Telionis, D. P.

    1974-01-01

    Analysis of the behavior of standing and traveling acoustic waves in a smooth duct with a fluid flow having a sheared mean velocity profile, when the waves grow algebraically as they travel along the duct axis. It is shown that standing waves growing algebraically with the axial distance cannot exist in a smooth duct when the duct wall have a finite resistance. The existence of traveling waves subject to the same law of growth is also dismissed under realistic flow conditions.

  4. Effect of shear on duct wall impedance.

    Science.gov (United States)

    Goldstein, M.; Rice, E.

    1973-01-01

    The solution to the equation governing the propagation of sound in a uniform shear layer is expressed in terms of parabolic cylinder functions. This result is used to develop a closed-form solution for acoustic wall impedance which accounts for both the duct liner and the presence of a boundary layer in the duct. The effective wall impedance can then be used as the boundary condition for the much simpler problem of sound propagation in uniform flow.

  5. Gas Explosions Mitigation by Ducted Venting

    OpenAIRE

    2007-01-01

    The mitigation of effects of gas and dust explosions within industrial equipment is effective if venting the combustion products to safe location. The presence of relief duct is however likely to increase the severity of the explosion with respect to equipment vented to open atmosphere, due to secondary explosions occurring in the initial sections of duct, frictional drag and inertia of the gas column, acoustic and Helmholtz oscillations. The weights of these phenomena on explosion e...

  6. Note on reflection and transmission coefficients for converging-diverging ducts

    Science.gov (United States)

    Durbin, P. A.

    1981-09-01

    Simple formulas for calculating acoustic reflection and transmission coefficients for converging-diverging ducts are derived; they extend the method of Cho and Ingard to arbitrary, slowly varying ducts. These formulas involve two parameters. The first is a function of duct shape and the second is the ratio of the duct radius downstream of the throat to that upstream of the throat to the upstream of the throat. An extension of the method to include mean flow is made for symmetric ducts.

  7. Mammary Duct Ectasia

    Science.gov (United States)

    ... tenderness or inflammation of the clogged duct (periductal mastitis). Mammary duct ectasia most often occurs in women ... that's turned inward (inverted) A bacterial infection called mastitis also may develop in the affected milk duct, ...

  8. The Use of Nonlinear Acoustics as an Energy-Efficient Technique for Aerosol Removal

    National Research Council Canada - National Science Library

    Yuen, W. T; Fu, S. C; Kwan, Joseph K. C; Chao, Christopher Y. H

    2014-01-01

    .... Unlike previous research, which used acoustics solely to cause aerosol agglomeration prior to aerosol removal in traditional duct collection systems, this article considers the acoustic streaming...

  9. 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.

  10. Curved Duct Noise Prediction Using the Fast Scattering Code

    Science.gov (United States)

    Dunn, M. H.; Tinetti, Ana F.; Farassat, F.

    2007-01-01

    Results of a study to validate the Fast Scattering Code (FSC) as a duct noise predictor, including the effects of curvature, finite impedance on the walls, and uniform background flow, are presented in this paper. Infinite duct theory was used to generate the modal content of the sound propagating within the duct. Liner effects were incorporated via a sound absorbing boundary condition on the scattering surfaces. Simulations for a rectangular duct of constant cross-sectional area have been compared to analytical solutions and experimental data. Comparisons with analytical results indicate that the code can properly calculate a given dominant mode for hardwall surfaces. Simulated acoustic behavior in the presence of lined walls (using hardwall duct modes as incident sound) is consistent with expected trends. Duct curvature was found to enhance weaker modes and reduce pressure amplitude. Agreement between simulated and experimental results for a straight duct with hard walls (no flow) was excellent.

  11. Aeroacoustic Noise Analysis of a Locomotive Cooling System Ducts and Structure Optimization

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2015-07-01

    Full Text Available Aero acoustic noise of a locomotive cab cooling system ducts was analyzed by method of Computational Fluid Dynamics (CFD and Computational Aero acoustic (CAA approach. Flow characteristic of the ducts was analyzed by CFD software, then near-field and far-field aero acoustic noise was forecasted with BNS model and FW-H model respectively. Duct structure was optimized according to the analysis of flow field and sound field. Results indicated that noise characteristic of sensitive frequency band at the position of human ear with the optimized duct has a significant improvement.

  12. Finite-amplitude waves in cylindrical lined ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    A second-order uniformly valid expansion is obtained for nonlinear waves propagating in a cylindrical duct lined with a point-reacting acoustic material that consists of a porous sheet followed by honey-comb cavities and backed by the impervious walls of the duct. The effect of the liner is taken into account by coupling the waves in the duct with those in the liner. As in the two-dimensional case, the nonlinearity increases the attenuation rate at all frequencies except in narrow bandwidths around the resonant frequencies, irrespective of the geometrical dimensions of the liner or the acoustic properties of the porous sheet.

  13. 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.

  14. An Exact Transfer Matrix Formulation of Plane Sound Wave Transmission in Inhomogeneous Ducts

    Science.gov (United States)

    Dockumaci, E.

    1998-11-01

    The impedance, or the reflection coefficient, of plane sound waves in inhomogeneous ducts satisfies a Riccati equation. The present paper shows that the duct impedance matrix, or the scattering matrix, can be related explicitly to the solutions of the associated linear equation of the Riccati equation for duct impedance, or reflection coefficient, respectively. New exact analytical scattering matrix solutions, which follow as consequences of this connection, are given for two significant duct acoustics problems, namely, the sound transmission in non-uniform ducts carrying an incompressible subsonic low Mach number mean flow transmission of sound in uniform ducts with a full quadratic axial mean temperature gradient.

  15. Preconditioning the Helmholtz Equation for Rigid Ducts

    Science.gov (United States)

    Baumeister, Kenneth J.; Kreider, Kevin L.

    1998-01-01

    An innovative hyperbolic preconditioning technique is developed for the numerical solution of the Helmholtz equation which governs acoustic propagation in ducts. Two pseudo-time parameters are used to produce an explicit iterative finite difference scheme. This scheme eliminates the large matrix storage requirements normally associated with numerical solutions to the Helmholtz equation. The solution procedure is very fast when compared to other transient and steady methods. Optimization and an error analysis of the preconditioning factors are present. For validation, the method is applied to sound propagation in a 2D semi-infinite hard wall duct.

  16. Radiated noise of ducted fans

    Science.gov (United States)

    Eversman, Walter

    The differences in the radiated acoustic fields of ducted and unducted propellers of the same thrust operating under similar conditions are investigated. An FEM model is created for the generation, propagation, and radiation of steady, rotor alone noise and exit guide vane interaction noise of a ducted fan. For a specified number of blades, angular mode harmonic, and rotor angular velocity, the acoustic field is described in a cylindrical coordinate system reduced to only the axial and radial directions. It is found that, contrary to the usual understanding of the Tyler and Sofrin (1962) result, supersonic tip speed rotor noise can be cut off if the tip Mach number is only slightly in excess of unity and if the number of blades is relatively small. If there are many blades, the fundamental angular mode number is large, and the Tyler and Sofrin result for thin annuli becomes more relevant. Shrouding of subsonic tip speed propellers is a very effective means of controlling rotor alone noise.

  17. Sound transmission through ducts and aircraft noise prediction, volume 1

    Science.gov (United States)

    Schauer, J. J.; Datko, J. T.; Guyton, R. W.

    1982-01-01

    Aircraft engine acoustical lining impedance models, ray acoustics, hydrodynamic modes, and transient analysis of sound propagation in variable area duct studies were applied to aircraft noise prediction. The effects of several duct lining configurations in a TF33 P5 and a CFM56 engined KC-135B aircraft were predicted. The prediction was based on a model corrected to fit flight noise data and modified by including theoretical duct noise attenuation predictions. The transient solution of variable area ducts permitted the prediction of sound propgation in bullet nose inlets for no low and was moderately successful when a potential flow was included with low Mach numbers. Volume 1 contains the technical report and analysis. Volume 2 contains the user's manuals and listings of the computer codes developed.

  18. Early bile duct cancer

    Institute of Scientific and Technical Information of China (English)

    Jae Myung Cha; Myung-Hwan Kim; Se Jin Jang

    2007-01-01

    Bile duct cancers are frequently diagnosed as advanced diseases. Over half of patients with advanced bile duct cancer present with unresectable malignancies and their prognosis has been very poor even after curative resections. Although there has been a need to diagnose bile duct cancer at its early stage, it has been a difficult goal to achieve due to our lack of knowledge regarding this disease entity. Early bile duct cancer may be defined as a carcinoma whose invasion is confined within the fibromuscular layer of the extrahepatic bile duct or intrahepatic large bile duct without distant metastasis irrespective of lymph node involvement. Approximately 3%-10% of resected bile duct cancers have been reported to be early cancers in the literature. The clinicopathological features of patients with early bile duct cancer differ from those of patients with advanced bile duct cancer, with more frequent asymptomatic presentation, characteristic histopathological findings,and excellent prognosis. This manuscript is organized to emphasize the need for convening an international consensus to develop the concept of early bile duct cancer.

  19. Finite difference solutions to shocked acoustic waves

    Science.gov (United States)

    Walkington, N. J.; Eversman, W.

    1983-01-01

    The MacCormack, Lambda and split flux finite differencing schemes are used to solve a one dimensional acoustics problem. Two duct configurations were considered, a uniform duct and a converging-diverging nozzle. Asymptotic solutions for these two ducts are compared with the numerical solutions. When the acoustic amplitude and frequency are sufficiently high the acoustic signal shocks. This condition leads to a deterioration of the numerical solutions since viscous terms may be required if the shock is to be resolved. A continuous uniform duct solution is considered to demonstrate how the viscous terms modify the solution. These results are then compared with a shocked solution with and without viscous terms. Generally it is found that the most accurate solutions are those obtained using the minimum possible viscosity coefficients. All of the schemes considered give results accurate enough for acoustic power calculations with no one scheme performing significantly better than the others.

  20. Investigation of the Herschel-Quincke tube concept in a rectangular lined duct

    OpenAIRE

    2001-01-01

    In this research an innovative combination of the Herschel-Quincke tubes and traditional liners is proposed for application in noise reduction of aircraft engines. The approach consists of installing Herschel-Quincke (HQ) tubes on lined rectangular ducts. An analytical model was developed to predict the effects of HQ tubes applied to rectangular lined ducts. The technique involves assuming the tube-duct interfaces as finite piston sources. These sources couple the acoustic field inside the du...

  1. 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.

  2. Monograph on propagation of sound waves in curved ducts

    Science.gov (United States)

    Rostafinski, Wojciech

    1991-01-01

    After reviewing and evaluating the existing material on sound propagation in curved ducts without flow, it seems strange that, except for Lord Rayleigh in 1878, no book on acoustics has treated the case of wave motion in bends. This monograph reviews the available analytical and experimental material, nearly 30 papers published on this subject so far, and concisely summarizes what has been learned about the motion of sound in hard-wall and acoustically lined cylindrical bends.

  3. Sound Radiation from a Supersonic Jet Passing Through a Partially Open Exhaust Duct

    Science.gov (United States)

    Kandula, Max

    2011-01-01

    The radiation of sound from a perfectly expanded Mach 2.5 cold supersonic jet of 25.4 mm exit diameter flowing through a partially open rigid-walled duct with an upstream i-deflector has been studied experimentally. In the experiments, the nozzle is mounted vertically, with the nozzle exit plane at a height of 73 jet diameters above ground level. Relative to the nozzle exit plane (NEP), the location of the duct inlet is varied at 10, 5, and -1 jet diameters. Far-field sound pressure levels were obtained at 54 jet diameters above ground with the aid of acoustic sensors equally spaced around a circular arc of radius equal to 80 jet diameters from the jet axis. Data on the jet acoustic field for the partially open duct were obtained and compared with those with a free jet and with a closed duct. The results suggest that for the partially open duct the overall sound pressure level (OASPL) decreases as the distance between the NEP and the duct inlet plane decreases, while the opposite trend is observed for the closed duct. It is also concluded that the observed peak frequency in the partially open duct increases above the free jet value as the angle from the duct axis is increased, and as the duct inlet plane becomes closer to the NEP.

  4. Finite amplitude waves in two-dimensional lined ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    A second-order uniform expansion is obtained for nonlinear wave propagation in a two-dimensional duct lined with a point-reacting acoustic material consisting of a porous sheet followed by honeycomb cavities and backed by the impervious wall of the duct. The waves in the duct are coupled with those in the porous sheet and the cavities. An analytical expression is obtained for the absorption coefficient in terms of the sound frequency, the physical properties of the porous sheet, and the geometrical parameters of the flow configuration. The results show that the nonlinearity flattens and broadens the absorption vs. frequency curve, irrespective of the geometrical dimensions or the porous material acoustic properties, in agreement with experimental observations.

  5. Scattering matrices in non-uniformly lined ducts

    Science.gov (United States)

    Demir, Ahmet

    2017-02-01

    Sudden area expansion and sudden area contraction in an infinitely long duct with discontinuous locally reacting lining are defined by respective mixed boundary value problems. In the absence of a sudden area change, a separate problem with an infinite duct having bifid lining on its wall is described. Introducing Fourier transform along the duct axis boundary value problems is solved by the well-known Wiener-Hopf technique, and then, corresponding scattering matrices are constructed. To show the proper use of scattering matrices in the case of several discontinuities and also validation and comparison purposes, transmitted field in a duct with an inserted expansion chamber whose walls are treated by acoustically absorbent material is derived by the help of the relevant scattering matrices. A perfect agreement is observed when the transmitted fields are compared numerically with a similar work exists in the literature.

  6. Isogeometric analysis of sound propagation through laminar flow in 2-dimensional ducts

    DEFF Research Database (Denmark)

    Nørtoft, Peter; Gravesen, Jens; Willatzen, Morten

    2015-01-01

    We consider the propagation of sound through a slowly moving fluid in a 2-dimensional duct. A detailed description of a flow-acoustic model of the problem using B-spline based isogeometric analysis is given. The model couples the non-linear, steady-state, incompressible Navier-Stokes equation...... in the laminar regime for the flow field, to a linear, time-harmonic acoustic equation in the low Mach number regime for the sound signal. B-splines are used both to represent the duct geometry and to approximate the flow and sound fields. This facilitates an exact representation of complex duct geometries...

  7. 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.

  8. A multi-modal solution for the transmission of sound in nonuniform ducts

    Science.gov (United States)

    Eversman, W.

    1976-01-01

    The method of weighted residuals in the form of a modified Galerkin method with boundary residuals is developed for the study of the transmission of sound in nonuniform ducts carrying a steady compressible flow. In this formulation the steady flow is modeled as essentially one-dimensional but with a kinematic modification to force tangency of the flow at the duct walls. Good agreement has been obtained with known results for transmission and reflection coefficients in hard walled ducts up to near sonic velocities. In ducts with acoustically compliant boundaries good comparisons have been more difficult to achieve except at low Mach numbers. The problem of transmission in a straight, acoustically treated duct with a uniform flow has been formulated and the Galerkin method used with basis functions derived from the case when flow is absent. Results indicate that favorable comparisons with exact computations can be obtained if care is taken in choosing the basis functions.

  9. Acoustic image typing of thyroglossal duct cyst by high frequency ultrasonography and its diagnosis value%高频超声对甲状舌管囊肿的分型及诊断价值

    Institute of Scientific and Technical Information of China (English)

    叶琴; 林礼务; 薛恩生; 林学英; 何以敉; 吴丽足; 梁荣喜

    2009-01-01

    Objective To probe the clinical diagnosis value of high frequency ultrasonography (HFUS) in thyroglossal duct cyst(TDC). Methods Forty-one TDC were taken HFUS and the location, boundary,shape,interal echo of lesions and the relation to hyoid bone were observed. The periphery and internal blood flow signal were detected by color Doppler flow imaging. The results of HFUS were compared with those of pathology after operation. The cases were divided into groups according to pathological types and were compared with acoustic image shows. Results All cases were diagnosed TDC by pathology after operation. Internal walls of 9 TDC consist of cilium columnar epithelium, 19 consist of stratified pavement epithelium and 13 consist of this two epitheliums. HFUS showed different pathological types had different ultrasonic appearances. In this study, 77.8%(7/9) TDC with columnar epithelium showed echoless,84.2 (16/19) TDC with pavement epithelium showed similar solid echopattern and TDC with two epitheliums mainly showed similar solid echopattern and multi-room cyst. Hyperechogenicity of hyoid bone displayed around the lesion in 80.5%(33/41)TDC. No blood flow signal showed in 41 TDC and a little punctiform blood flow signal showed in the periphery of 5 TDC. The diagnose accordance rate of HFUS in TDC was 95.1%(39/41). Conclusions HFUS can clearly show the location, boundary, shape,interal echo of TDC and its relation to hyoid bone. HFUS is important for diagnosis and differential diagnosis of TDC.%目的 探讨高频超声检查对甲状舌管囊肿(TDC)的临床诊断价值.方法 应用高频超声检查41例TDC,观察病变的位置、边界、形态、内部回声及其与舌骨的关系,并应用彩色多普勒血流显像观察肿物边缘与内部的血流信号.超声检查结果 与手术病理诊断对照,将所有资料按照病理类型分组并分别与声像图表现对比.结果 全部病例均经手术病理证实为TDC,其中9例TDC内衬纤毛柱状上皮,19

  10. Transmission of sound through annular ducts of varying cross sections and sheared mean flow

    Science.gov (United States)

    Nayfeh, A. H.; Kaiser, J. E.; Telionis, D. P.

    1974-01-01

    An asymptotic solution is presented for the transmission and attenuation of acoustic waves in an annular duct of slowly varying cross section which carries a sheared mean flow. The analysis also takes into account the growth of the boundary layer as well as any slow variations in the acoustic liner properties. The problem is reduced to the solution of a first-order ordinary differential equation for the amplitude. The analysis is used to estimate the effects of the variations of the duct cross section and boundary layer growth on the different acoustic modes.

  11. 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

  12. Particle deposition in ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sippola, Mark R.

    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 {micro}m 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

  13. A novel duct silencer using dielectric elastomer absorbers

    Science.gov (United States)

    Lu, Zhenbo; Cui, Yongdong; Zhu, Jian; Debiasi, Marco

    2014-03-01

    A novel duct silencer was developed using dielectric elastomer absorbers (DEAs). Dielectric elastomer, a lightweight, high elastic energy density and large deformation under high DC/AC voltages smart material, was used to fabricate this new generation actuator. The acoustic performances of this duct silencer were experimentally investigated in a transmission loss (TL) measurement system using two-load method. It was found that the resonance peaks of this new duct silencer could be controlled by applying various DC voltages, a maximum resonance shift of 59.5Hz for the resonance peaks was achieved which indicated that this duct silencer could be adjusted to absorb broadband range noise without any addition mechanical part. Furthermore, the resonance shift and multiple resonances mechanisms using DEAs were proposed and discussed in the present paper which was aiming to achieve broadband noise reduction. The present results also provide insight into the appropriateness of the absorber for possible use as new acoustic treatment to replace the traditional acoustic treatment.

  14. What Is Bile Duct Cancer?

    Science.gov (United States)

    ... the liver. Types of bile duct cancer by cell type Bile duct cancers can also be divided ... Our Volunteers More ACS Sites Bookstore Shop Cancer Atlas Press Room Cancer Statistics Center Volunteer Learning Center ...

  15. Gallbladder and Bile Duct Disorders

    Science.gov (United States)

    ... Disorders Overview of Gallbladder and Bile Duct Disorders Cholecystitis Gallstones Biliary Pain Without Gallstones Narrowing of the ... ducts are blocked, the gallbladder may become inflamed ( cholecystitis ). Biliary pain without gallstones (acalculous biliary pain) can ...

  16. 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).

  17. Malignant tumors of Stensen's duct.

    Science.gov (United States)

    Steiner, M; Gould, A R; Miller, R L; Johnson, J A

    1999-01-01

    A rare case of squamous cell carcinoma arising in Stensen's duct is reported. The literature concerning malignant neoplasia originating in this site is reviewed, with attention given to the histopathologic diversity of neoplasms occurring in the duct, criteria for determination of origin in the duct, and outcomes of therapy.

  18. Isolated Pancreatic Uncinate Duct IPMN.

    Science.gov (United States)

    Maker, Ajay V; Maker, Vijay K

    2017-04-01

    The ventral pancreas originally forms as an evagination of the common bile duct at 32 days gestation and its duct, the uncinate duct, eventually rotates with the ventral anlage to join the dorsal pancreas and fuse with the main pancreatic duct. Thus, though often considered a "branch" duct of the pancreas, embryologically, the uncinate duct is the "main" pancreatic duct of the ventral pancreas. This concept is not fully addressed in the current definitions of intraductal papillary mucinous neoplasms of the pancreas (IPMN) where international consensus guidelines consider the main-duct IPMN as high risk for malignancy and most small branch-duct IPMN as low risk for malignancy. Thus, it is important to recognize that isolated uncinate-duct IPMN can occur and, based on its embryologic origin and increased association with high-grade dysplasia and invasive cancer, may be managed conceptually as a main duct type of disease rather than a branch duct until better biomarkers of malignancy are discovered. The images provide an example of this unique disease process.

  19. 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.

  20. 14 CFR 25.1103 - Induction system ducts and air duct systems.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Induction system ducts and air duct systems....1103 Induction system ducts and air duct systems. (a) Each induction system duct upstream of the first... auxiliary power unit bleed air duct systems, no hazard may result if a duct failure occurs at any...

  1. 3C DUCT DESIGN METHOD

    Institute of Scientific and Technical Information of China (English)

    Huan-RueiShiu; Feng-ChuOu; Sih-LiChen

    2002-01-01

    A new 3C duct design method is proposed for designing a high quality, energy-efficiency cost-effective air duct system. It not only considers the demand of volume flow rate, but also takes into consideration a number of issues including system pressure balance, noise, vibration, space limitation and total system cost. This new method comprises three major calculation procedures:initial computer-aided design (CAD), computer-aided simulation (CAS) and correction processes (CP). An example is presented in this study to understand the characteristics of 3C method. It shows that 3C duct design method provides a simple computation procedure for an optimum air duct system. It also shortens the design schedule, prevents human calculation errors, and reduces the dependence on designer experience. In addition to apply in a new duct system design, 3C duct design method is also a powerful design tool for the expansion of an existing duct system.

  2. Salivary duct carcinoma

    DEFF Research Database (Denmark)

    Breinholt, Helle; Elhakim, Mohammad Talal; Godballe, Christian;

    2016-01-01

    1990 to 2005 were identified. Histological slides were reviewed, and data concerning demographics, tumour site, clinical stage, treatment profiles and follow-up were retrieved. Survival estimates and prognostic factors were evaluated by comparing Kaplan-Meier plots using the Mantel-Haenszel log......-rank test. RESULTS: Salivary duct carcinoma showed an incidence of 0.04/100.000 inhabitants/year. Distant recurrence was seen in 52% of patients. Five-year overall survival, disease-specific survival and recurrence-free survival were 32%, 42% and 35%, respectively. Univariate analyses suggested that overall...... stage (III/IV) and vascular invasion have a negative impact on all survival measures. Involved resection margins correlated with a poorer overall survival and disease-specific survival, whereas adjuvant radiotherapy improved overall survival and recurrence-free survival. CONCLUSIONS: Salivary duct...

  3. Developing active noise control systems for noise attenuation in ducts

    Science.gov (United States)

    Campos, Rosely V.; Ivo, Rodrigo C.; Medeiros, Eduardo B.

    2002-11-01

    The present work describes some of the research effort on Active Noise Control (ANC) being jointly developed by the Catholic University of Minas Gerais (PUC-MINAS) and the Federal University of Minas Gerais (UFMG). Considerations about the implementation of Digital Signal Processing for noise control in ducts has been presented. The objective is to establish a study on Active Noise Control in ducts combining geometry and acoustic parameters modification together with adaptive digital filtering implementation. Both algorithm and digital signal processing details are also discussed. The main results for a typical application where real attenuation has been obtained are presented and considered according to their use in developing real applications. The authors also believe that the present text should provide an interesting overview for both designers and students concerned about Active Noise Control in ducts. (To be presented in Portuguese.)

  4. Acoustic source data for medium speed IC-engines

    OpenAIRE

    Hynninen, A.; Turunen, R.; Åbom, Mats; Bodén, Hans

    2011-01-01

    Knowledge of the acoustic source characteristics of internal combustion engines (IC-engines) is of great importance when designing the exhaust duct system and its components to withstand the resulting dynamic loads and to reduce the exhaust noise emission. Number of studies has been published earlier on the low frequency in-duct exhaust noise of high speed engines. The goal of the present study is to investigate the medium speed IC-engine acoustic source characteristics numerically and experi...

  5. Compressive sensing based spinning mode detections by in-duct microphone arrays

    Science.gov (United States)

    Yu, Wenjun; Huang, Xun

    2016-05-01

    This paper presents a compressive sensing based experimental method for detecting spinning modes of sound waves propagating inside a cylindrical duct system. This method requires fewer dynamic pressure sensors than the number required by the Shannon-Nyquist sampling theorem so long as the incident waves are sparse in spinning modes. In this work, the proposed new method is firstly validated by preparing some of the numerical simulations with representative set-ups. Then, a duct acoustic testing rig with a spinning mode synthesiser and an in-duct microphone array is built to experimentally demonstrate the new approach. Both the numerical simulations and the experiment results are satisfactory, even when the practical issue of the background noise pollution is taken into account. The approach is beneficial for sensory array tests of silent aeroengines in particular and some other engineering systems with duct acoustics in general.

  6. Effect of transverse velocity and temperature gradients on sound attenuation in two-dimensional ducts

    Science.gov (United States)

    Nayfeh, A. H.; Sun, J.

    1974-01-01

    An investigation is described of the effect of transverse mean-velocity and temperature gradients on sound attenuation in acoustically treated two-dimensional ducts. The results show that cooling the duct walls leads to channeling the sound toward the walls for both downstream and upstream propagation. The effect of mean-temperature gradients on the attenuation rates of the lowest three modes can be as important as the effect of mean-velocity gradients.

  7. Interaction of a turbulent-jet noise source with transverse modes in a rectangular duct

    Science.gov (United States)

    Succi, G. P.; Baumeister, K. J.; Ingard, K. U.

    1978-01-01

    A turbulent jet was used to excite transverse acoustic modes in a rectangular duct. The pressure spectrum showed asymmetric singularities (pressure spikes) at the resonant frequencies of the duct modes. This validates previously published theoretical results. These pressure spikes occurred over a range of jet velocities, orientations, and inlet turbulence levels. At the frequency of the spike, the measured transverse pressure shape matched the resonant mode shape.

  8. Asymptomatic common bile duct stones.

    Science.gov (United States)

    Rosseland, A R; Glomsaker, T B

    2000-11-01

    Patients with asymptomatic bile duct stones exhibit typical signs, such as elevated liver function tests, dilated bile ducts on ultrasound, a history of jaundice, or pancreatitis. The incidence of asymptomatic bile duct stones is about 10%, but up to 2% of patients show no signs of the disease. Bile duct stones can be diagnosed by using clinical judgement, scoring systems, or discriminant function tests. Which diagnostic modality is most reliable, cost-effective and safe, varies with different hospitals. Which therapy is most effective, safe and the cheapest also varies with different departments, but in the future an increasing number of departments will use the one-stage laparoscopic approach.

  9. Extracorporeal piezoelectric lithotripsy for complicated bile duct stones.

    Science.gov (United States)

    Weber, J; Adamek, H E; Riemann, J F

    1991-02-01

    Today, common bile duct stones are extracted endoscopically. After endoscopic sphincterotomy, nearly 90% of all stones can be removed with a Dormia basket or a mechanical lithotripter. Problems are encountered if there are larger stones or a duct stenosis. New conservative therapies do serve as an alternative to surgical intervention for those few patients in whom endoscopic measures have failed. Stone fragmentation can be achieved by extracorporeal shock wave lithotripsy, and remaining fragments can be removed endoscopically. So far, authors of most reports on the successful disintegration of common bile duct stones used the Dornier lithotripter. Stone localization is thus achieved with x-rays, and the shock waves are generated by an underwater spark discharge. We report on our experiences and results with extracorporeal piezoelectric shock wave lithotripsy (EPL) in 19 patients with complicated bile duct stones. With this lithotripter, stones are visualized by ultrasound, and shock waves are produced by a piezoelectric acoustic generator. Fragmentation was achieved in 84.2%, and complete stone removal in 78.9%. These results show that piezoelectric lithotripsy is also a useful method for the treatment of complicated bile duct stones, as has already been proved for the electrohydraulic- and electromagnetic-generated shock waves systems. However, the renunciation of general anesthesia and the need for analgesia or sedation in only 25% of the treatments render this lithotripter system attractive, especially for elderly and frail patients.

  10. Vibroacoustic Analysis of a Refrigerator Freezer Cabinet Coupled with an Air Duct

    Directory of Open Access Journals (Sweden)

    Onur Çelikkan

    2017-01-01

    Full Text Available In this study, the vibration and acoustic interactions between the structure and the cavity inside the freezer cabinet were investigated. Thus, a set of numerical and experimental analyses were performed. In the numerical analysis, the acoustic characteristics of the freezer cavity were solved, and the mixed finite element method was then implemented to analyse the coupled behaviour of the cavity with the air duct using the Acoustic Fluid-Structure Interaction (AFSI technique. In the experimental analyses, an acoustic modal analysis of the freezer cavity and a structural modal analysis of the air duct were performed for the validation process. A good agreement was obtained among the results. Thus, the accuracy of the numerical model was confirmed. The validated models were used for optimizing the design. To solve the noise generation mechanism inside the freezer cabinet, the noise primarily generated by the freezer fan unit was measured under normal working conditions of the refrigerator, and the resonance frequencies were obtained. This information was compared with the normal modes of the air duct, and the overlapping frequencies were identified. To reduce the interaction between the source and the structure, a few design modifications were applied to the air duct. Thus, the structural-borne noise radiating from the air duct into the freezer cavity was reduced.

  11. Sound propagation in slowly varying lined flow ducts of arbitrary cross-section

    Science.gov (United States)

    Rienstra, S. W.

    2003-11-01

    Sound transmission through ducts of constant cross-section with a uniform inviscid mean flow and a constant acoustic lining (impedance wall) is classically described by a modal expansion, where the modes are eigenfunctions of the corresponding Laplace eigenvalue problem along a duct cross-section. A natural extension for ducts with cross-section and wall impedance that are varying slowly (compared to a typical acoustic wavelength and a typical duct radius) in the axial direction is a multiple-scales solution. This has been done for the simpler problem of circular ducts with homentropic irrotational flow. In the present paper, this solution is generalized to the problem of ducts of arbitrary cross-section. It is shown that the multiple-scales problem allows an exact solution, given the cross-sectional Laplace eigensolutions. The formulation includes both hollow and annular geometries. In addition, the turning point analysis is given for a single hard-wall cut-on, cut-off transition. This appears to yield the same reflection and transmission coefficients as in the circular duct problem.

  12. Gallbladder and bile duct

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    930559 An experimental study on effective hep-atic blood flow and hepatic energy metabolismfollowing acute obstructive cholangitis and bil-iary obstruction.SUN Wenbing (孙文兵),et al.Hepatobili Surg,Center,Southwest Hosp,Chongqing 630000.Chin J Digest 1992;12(5):261—263.The changes of effective hepatic blood flow(E-HBF)and hepatic energy metabolism were stud-ied following acutc obstructive cholangitis(AOC)and bile duct ligation(BDL)in rats.The resultsshowed that EHBF was significantly decreased at24hs after and further decreased at 48hs afterBDL.And EHBF was significantly decreased at

  13. Stopping duct quacks: Longevity of residential duct sealants

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, Max H.; Walker, Iain S.; Dickerhoff, Darryl J.

    2000-08-01

    Duct leakage has been identified as a major source of energy loss in residential buildings. Most duct leakage occurs at the connections to registers, plenums or branches in the duct system. At each of these connections a method of sealing the duct system is required. Typical sealing methods include tapes or mastics applied around the joints in the system. Field examinations of duct systems have shown that these seals tend to fail over time periods ranging from days to years. We have used several test methods over the last few years to evaluate the longevity of duct sealants when subjected to temperatures and pressures representative of those found in the field. Traditional cloth duct tapes have been found to significantly under-perform other sealants and have been banned from receiving duct tightness credits in California's energy code (California Energy Commission 1998). Our accelerated testing apparatus has been redesigned since its first usage for improved performance. The methodology is currently under consideration by the American Society for Testing and Materials (ASTM) as a potential new test method. This report will summarize the set of measurements to date, review the status of the test apparatus and test method, and summarize the applications of these results to codes and standards.

  14. 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....

  15. Surgery for Bile Duct (Cholangiocarcinoma) Cancer

    Science.gov (United States)

    ... Situation Bile Duct Cancer Treating Bile Duct Cancer Surgery for Bile Duct Cancer There are 2 general ... also help plan the operation to remove it. Surgery for resectable cancers For resectable cancers, the type ...

  16. 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....

  17. Sound propagation through nonuniform ducts

    Science.gov (United States)

    Nayfeh, A. H.

    1976-01-01

    Methods of determining the transmission and attenuation of sound propagating in nonuniform ducts with and without mean flows are discussed. The approaches reviewed include purely numerical techniques, quasi-one-dimensional approximations, solutions for slowly varying cross sections, solutions for weak wall undulations, approximation of the duct by a series of stepped uniform cross sections, variational methods and solutions for the mode envelopes.

  18. Intrahepatic Transposition of Bile Ducts

    Science.gov (United States)

    Delić, Jasmin; Savković, Admedina; Isaković, Eldar; Marković, Sergije; Bajtarevic, Alma; Denjalić, Amir

    2012-01-01

    Objective. To describe the intrahepatic bile duct transposition (anatomical variation occurring in intrahepatic ducts) and to determine the frequency of this variation. Material and Methods. The researches were performed randomly on 100 livers of adults, both sexes. Main research methods were anatomical macrodissection. As a criterion for determination of variations in some parts of bile tree, we used the classification of Segmentatio hepatis according to Couinaud (1957) according to Terminologia Anatomica, Thieme Stuugart: Federative Committee on Anatomical Terminology, 1988. Results. Intrahepatic transposition of bile ducts was found in two cases (2%), out of total examined cases (100): right-left transposition (right segmental bile duct, originating from the segment VIII, joins the left liver duct-ductus hepaticus sinister) and left-right intrahepatic transposition (left segmental bile duct originating from the segment IV ends in right liver duct-ductus hepaticus dexter). Conclusion. Safety and success in liver transplantation to great extent depends on knowledge of anatomy and some common embryological anomalies in bile tree. Variations in bile tree were found in 24–43% of cases, out of which 1–22% are the variations of intrahepatic bile ducts. Therefore, good knowledge on ductal anatomy enables good planning, safe performance of therapeutic and operative procedures, and decreases the risk of intraoperative and postoperative complications. PMID:22550601

  19. Laparoscopic common bile duct exploration.

    Science.gov (United States)

    Stoker, M E; Leveillee, R J; McCann, J C; Maini, B S

    1991-10-01

    Operative common bile duct exploration, performed in conjunction with cholecystectomy, has been considered the treatment of choice for choledocholithiasis in the presence of an intact gallbladder. With the advent of laparoscopic cholecystectomy, the management of common bile duct stones has been affected. More emphasis is being placed on endoscopic sphincterotomy and options other than operative common duct exploration. Because of this increasing demand, we have developed a new technique for laparoscopic common bile duct exploration performed in the same operative setting as laparoscopic cholecystectomy. A series of five patients who successfully underwent common bile duct exploration, flexible choledochoscopy with stone extraction, and T-tube drainage, all using laparoscopic technique, is reported. Mean postoperative length of hospital stay was 4.6 days. Outpatient T-tube cholangiography was performed in all cases and revealed normal ductal anatomy with no retained stones. Follow-up ranged from 6 weeks to 4 months, and all patients were asymptomatic and had normal liver function tests.

  20. Ascariasis of the pancreatic duct.

    Science.gov (United States)

    Klimovskij, Michail; Dulskas, Audrius; Kraulyte, Zita; Mikalauskas, Saulius

    2015-09-15

    Ascariasis is a common helminthic disease worldwide, although Lithuania and other European countries are not considered endemic areas. The presence of the Ascaris worm in the biliary tree causes choledocholithiasis-like symptoms. We report a case of pancreatic duct ascariasis causing such symptoms. A 73-year-old Lithuanian woman underwent endoscopic retrograde cholangiopancreatography (ERCP) suspecting choledocholithiasis. Contrast injection into the common bile duct demonstrated a slightly dilated biliary tree without any filling defects, and the tail of an Ascaris worm protruding from the opening of the papilla Vater. The worm was captured by a snare but escaped deep into the duct. After a small wirsungotomy the worm was retrieved from the pancreatic duct. The patient received a 150 mg dose of levamisole orally repeated 7 days later and was discharged after complete resolution of symptoms. This first reported sporadic case of pancreatic duct ascariasis in Lithuania was successfully treated with ERCP and Levamisole.

  1. A prediction method for aerodynamic sound produced by multiple elements in air ducts

    Science.gov (United States)

    Mak, C. M.

    2005-10-01

    A prediction method for aerodynamic sound produced by the interaction of multiple elements in a low speed flow duct has been developed. Same as the previous works of Mak and Yang for two in-duct elements, the concept of partially coherent sound fields is adopted to formulate the sound powers produced by interaction of multiple in-duct elements at frequencies below and above the cut-on frequency of the lowest transverse duct mode. An interaction factor is finally defined as a result of a simple relationship between the sound power due to the interaction of multiple in-duct elements and that due to a single in-duct element. The present study suggests that it is possible to predict the level and spectral distribution of the additional acoustic energy produced by the interaction of multiple in-duct elements. The proposed method therefore can form a basis of a generalized prediction method for aerodynamic sound produced by multiple in-duct elements in a ventilation system.

  2. PMR Graphite Engine Duct Development

    Science.gov (United States)

    Stotler, C. L.; Yokel, S. A.

    1989-01-01

    The objective was to demonstrate the cost and weight advantages that could be obtained by utilizing the graphite/PMR15 material system to replace titanium in selected turbofan engine applications. The first component to be selected as a basis for evaluation was the outer bypass duct of the General Electric F404 engine. The operating environment of this duct was defined and then an extensive mechanical and physical property test program was conducted using material made by processing techniques which were also established by this program. Based on these properties, design concepts to fabricate a composite version of the duct were established and two complete ducts fabricated. One of these ducts was proof pressure tested and then run successfully on a factory test engine for over 1900 hours. The second duct was static tested to 210 percent design limit load without failure. An improved design was then developed which utilized integral composite end flanges. A complete duct was fabricated and successfully proof pressure tested. The net results of this effort showed that a composite version of the outer duct would be 14 percent lighter and 30 percent less expensive that the titanium duct. The other type of structure chosen for investigation was the F404 fan stator assembly, including the fan stator vanes. It was concluded that it was feasible to utilize composite materials for this type structure but that the requirements imposed by replacing an existing metal design resulted in an inefficient composite design. It was concluded that if composites were to be effectively used in this type structure, the design must be tailored for composite application from the outset.

  3. Architectural acoustics

    National Research Council Canada - National Science Library

    Long, Marshall

    2014-01-01

    .... Beginning with a brief history, it reviews the fundamentals of acoustics, human perception and reaction to sound, acoustic noise measurements, noise metrics, and environmental noise characterization...

  4. 14 CFR 29.1103 - Induction systems ducts and air duct systems.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Induction systems ducts and air duct systems. 29.1103 Section 29.1103 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF....1103 Induction systems ducts and air duct systems. (a) Each induction system duct upstream of the...

  5. A boundary element model for lined circular ducts with uniform flow

    DEFF Research Database (Denmark)

    Juhl, Peter Møller

    1996-01-01

    A boundary element method has been developed for predicting the acoustics in a circular duct in which a uniform flow propagates. Such a model may be used to predict the performance of different liner designs for inlets of turbo fan engines, which is important for the aeronautics industry...

  6. Isogeometric analysis of sound propagation through laminar flow in 2-dimensional ducts

    DEFF Research Database (Denmark)

    Nørtoft, Peter; Gravesen, Jens; Willatzen, Morten

    2015-01-01

    We consider the propagation of sound through a slowly moving fluid in a 2-dimensional duct. A detailed description of a flow-acoustic model of the problem using B-spline based isogeometric analysis is given. The model couples the non-linear, steady-state, incompressible Navier-Stokes equation in ...

  7. Migratory intralaryngeal thyroglossal duct cyst

    Directory of Open Access Journals (Sweden)

    Karlatti Pradeep

    2010-01-01

    Full Text Available Intralaryngeal thyroglossal duct cysts are rare; a migrating one, rarer still. Such a case may be a cause for confusion and it is important to understand this entity and its typical findings.

  8. TWO NEW DUCT LEAKAGE TESTS

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS,J.W.

    1998-12-01

    Two variations on the tests for duct leakage currently embodied in ASHRAE Standard 152P (Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal Distribution Systems) are presented. Procedures are derived for calculating supply and return duct leakage to/from outside using these new variations. Results of these tests are compared with the original ones in Standard 152P on the basis of data collected in three New York State homes.

  9. 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.

  10. Finite-difference theory for sound propagation in a lined duct with uniform flow using the wave envelope concept

    Science.gov (United States)

    Baumeister, K. J.

    1977-01-01

    Finite difference equations are derived for sound propagation in a two dimensional, straight, soft wall duct with a uniform flow by using the wave envelope concept. This concept reduces the required number of finite difference grid points by one to two orders of magnitude depending on the length of the duct and the frequency of the sound. The governing acoustic difference equations in complex notation are derived. An exit condition is developed that allows a duct of finite length to simulate the wave propagation in an infinitely long duct. Sample calculations presented for a plane wave incident upon the acoustic liner show the numerical theory to be in good agreement with closed form analytical theory. Complete pressure and velocity printouts are given to some sample problems and can be used to debug and check future computer programs.

  11. Virtual Acoustics

    Science.gov (United States)

    Lokki, Tapio; Savioja, Lauri

    The term virtual acoustics is often applied when sound signal is processed to contain features of a simulated acoustical space and sound is spatially reproduced either with binaural or with multichannel techniques. Therefore, virtual acoustics consists of spatial sound reproduction and room acoustics modeling.

  12. 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.

  13. Single Mode Theory for Impedance Eduction in Large-Scale Ducts with Grazing Flow

    Science.gov (United States)

    Watson, Willie R.; Gerhold, Carl H.; Jones, Michael G.; June, Jason C.

    2014-01-01

    An impedance eduction theory for a rigid wall duct containing an acoustic liner with an unknown impedance and uniform grazing flow is presented. The unique features of the theory are: 1) non-planar waves propagate in the hard wall sections of the duct, 2) input data consist solely of complex acoustic pressures acquired on a wall adjacent to the liner, and 3) multiple higher-order modes may exist in the direction perpendicular to the liner and the opposite rigid wall. The approach is to first measure the axial propagation constant of a dominant higher-order mode in the liner sample section. This axial propagation constant is then used in conjunction with a closed-form solution to a reduced form of the convected Helmholtz equation and the wall impedance boundary condition to educe the liner impedance. The theory is validated on a conventional liner whose impedance spectrum is educed in two flow ducts with different cross sections. For the frequencies and Mach numbers of interest, no higher-order modes propagate in the hard wall sections of the smaller duct. A benchmark method is used to educe the impedance spectrum in this duct. A dominant higher-order vertical mode propagates in the larger duct for similar test conditions, and the current theory is applied to educe the impedance spectrum. Results show that when the theory is applied to data acquired in the larger duct with a dominant higher-order vertical mode, the same impedance spectra is educed as that obtained in the small duct where only the plane wave mode is present and the benchmark method is used. This result holds for each higher-order vertical mode that is considered.

  14. Propagation of Sound at Moderate and High Intensities in Absorbent and Hard-Walled Cylindrical Ducts. Ph.D. Thesis

    Science.gov (United States)

    Mcdaniel, Oliver Herbert

    1975-01-01

    The propagation of plane wave and higher order acoustic modes in both hard-walled and absorbent cylindrical ducts was studied at moderate sound intensities where the linear wave equation is valid, and at high intensities where nonlinear effects can be observed. The experiments were conducted with an anechoically terminated twelve-inch inside-diameter transite pipe. Various types of sound sources were mounted at one end of the duct to generate the desired acoustic fields within the duct. Arrays of conventional loudspeakers were used to generate plane waves and higher order acoustic modes at moderate intensities, and an array of four high intensity electro-pneumatic sound sources was used for the experiments in the nonlinear region. The attenuation of absorbent liners made of several different materials was obtained at moderate intensities for both plane waves and high order modes. It was found that the characteristics of the liners studied did not change appreciably at high intensities.

  15. Analysis of Dual Rotating Rake Data from the NASA Glenn Advanced Noise Control Fan Duct with Artificial Sources

    Science.gov (United States)

    Dahl, Milo D.; Sutliff, Daniel L.

    2014-01-01

    The Rotating Rake mode measurement system was designed to measure acoustic duct modes generated by a fan stage. Initially, the mode amplitudes and phases were quantified from a single rake measurement at one axial location. To directly measure the modes propagating in both directions within a duct, a second rake was mounted to the rotating system with an offset in both the axial and the azimuthal directions. The rotating rake data analysis technique was then extended to include the data measured by the second rake. The analysis resulted in a set of circumferential mode levels at each of the two rake microphone locations. Radial basis functions were then least-squares fit to this data to obtain the radial mode amplitudes for the modes propagating in both directions within the duct. Validation experiments have been conducted using artificial acoustic sources. Results are shown for the measurement of the standing waves in the duct from sound generated by one and two acoustic sources that are separated into the component modes propagating in both directions within the duct. Measured reflection coefficients from the open end of the duct are compared to analytical predictions.

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

    Science.gov (United States)

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

    1980-01-01

    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. 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, thereby reducing the computation time and the round-off error encountered in purely numerical techniques. A number of test cases that demonstrate the flexibility of the program are included. Convergence of the transmission coefficients and the acoustic pressure profiles with an increasing number of modes is illustrated.

  17. Risk Factors associated with Paraurethral Duct Dilatation following Gonococcal Paraurethral Duct Infection in Men

    Science.gov (United States)

    Fan, Wenge; Zhang, Qingsong; Wang, Lin; Ye, Xun; Jiang, Tingwang

    2016-01-01

    No studies have explored the risk factors for paraurethral duct dilatation following paraurethral duct infection by Neisseria gonorrhoeae in men undergoing ceftriaxone therapy. The present study was performed to explore the risk factors for paraurethral duct dilatation following paraurethral duct infection by N. gonorrhoeae in men undergoing ceftriaxone therapy and thus guide clinical interventions. We compared the demographic, behavioral, and clinical data of men with paraurethral duct infection by N. gonorrhoeae with and without dilatation of the paraurethral duct. Univariate analysis showed significant differences in age, disease course of the infected paraurethral duct, Chlamydia trachomatis infection in the paraurethral duct, and a history of paraurethral duct infection by N. gonorrhoeae between the patient and control groups (Pgonorrhoeae in men. Age, C. trachomatis infection in the paraurethral duct, and a history of paraurethral duct infection by N. gonorrhoeae are also risk factors. Thus, educating patients to undergo timely therapy and treating the C. trachomatis infection may be effective interventions. PMID:27861521

  18. Evaluating the Acoustic Benefits of Over-the-Rotor Acoustic Treatments Installed on the Advanced Noise Control Fan

    Science.gov (United States)

    Gazella, Matthew R.; Takakura, Tamuto; Sutliff, Daniel L.; Bozak, Richard F.; Tester, Brian J.

    2017-01-01

    Over the last 15 years, over-the-rotor acoustic treatments have been evaluated by NASA with varying success. Recently, NASA has been developing the next generation of over-the-rotor acoustic treatments for fan noise reduction. The NASA Glenn Research Centers Advanced Noise Control Fan was used as a Low Technology Readiness Level test bed. A rapid prototyped in-duct array consisting of 50 microphones was employed, and used to correlate the in-duct analysis to the far-field acoustic levels and to validate an existing beam-former method. The goal of this testing was to improve the Technology Readiness Level of various over-the-rotor acoustic treatments by advancing the understanding of the physical mechanisms and projecting the far-field acoustic benefit.

  19. An isolated nasolacrimal duct osteoma.

    Science.gov (United States)

    Kim, Joo Yeon; Kwon, Jae Hwan

    2013-07-01

    Osteomas of the nose and paranasal sinus are common benign tumors that can extend to surrounding structures and result in orbital or intracranial involvement. Presenting symptoms include facial pain, headache, cerebral symptoms, ocular symptoms, and so on, depending on the location and size of the tumor. They commonly occur within the frontal, ethmoid, maxillary, and sphenoid sinuses; however, there are rare cases of reported osteomas in the nasal cavity, turbinate, or orbit. Our case report describes a patient with nasolacrimal duct osteoma who presented with ipsilateral ocular pain, epiphora, and medial canthal swelling. We performed intranasal dacryocystorhinostomy using a nasal endoscope and removed the lacrimal duct osteoma. This report describes symptoms and management of an isolated nasolacrimal duct stone with a review of the literature.

  20. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  1. Acoustic propagation in a rigid torus

    Science.gov (United States)

    El-Raheb, M.; Wagner, P.

    1982-01-01

    The acoustic propagation in a rigid torus is analyzed using a Green's function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.

  2. Applying micro-perforated panels in the measurement of sound source characteristics in a duct system

    Institute of Scientific and Technical Information of China (English)

    SHEN Su; Goran Pavic; LIU Bilong; LI Xiaodong; TIAN Jing

    2012-01-01

    In order to measure the acoustic characteristics of the sound source in a duct system effectively without destroying the main duct, micro-perforated panel structures were applied in the new method by attaching the side branch tubes. The effect and influence to change the acoustical impedance of the loads in a duct system was analyzed and simulated for using one layer and double-layer micro-perforated panel and back cavities with different parameters such as panel thickness, hole diameter, perforation ration, back depth and so on. The results show that the load's resistance can be changed efficiently by adjusting panel thickness, hole diameter, perforation ratio, the ratio of cross-section between ducts and tubes and other parameters; and the load's reactance can be changed efficiently by adjusting back depth and distance between micro-perforated panel and main duct. It is also found that combinative usage of one layer and double-layer of these structures can change the reactance substantially in broad frequency domain. The method and the efficient performance of the structures with micro-perforated panel in the measurement were verified by the experiment under the situations of flow and no- flow. Finally, suggestions to design and apply these structures in the above-mentioned method in application were given.

  3. A wave-envelope of sound propagation in nonuniform circular ducts with compressible mean flows

    Science.gov (United States)

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

    1979-01-01

    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. 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, thereby reducing the computation time and the round-off error encountered in purely numerical techniques. The solution recovers the solution based on the method of multiple scales for slowly varying duct geometry. A computer program was developed based on the wave-envelope analysis for general mean flows. Results are presented for the reflection and transmission coefficients as well as the acoustic pressure distributions for a number of conditions: both straight and variable area ducts with and without liners and mean flows from very low to high subsonic speeds are considered.

  4. Acoustic telemetry

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To determine movements of green turtles in the nearshore foraging areas, we deployed acoustic tags and determined their movements through active and passive acoustic...

  5. Fragmentation of common bile duct and pancreatic duct stones by extracorporeal shock-wave lithotripsy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ham Gyum [Ansan Junior College, Seoul (Korea, Republic of); Son, Soon Yong; Lee, Won Hong [Asan Medical Center, Seoul (Korea, Republic of)

    1998-06-01

    To determine its usefulness and safety of extracorporeal shock-wave lithotripsy in common bile duct and pancreatic duct stones, we analyzed the results of 13 patients with common bile duct stones and 6 patients with pancreatic duct stones which were removed by endoscopic procedures using the balloon or basket, who was performed the extracorporeal shock-wave lithotripsy using the ultrasonography for stone localization with a spark gap type Lithotriptor(Dornier MPL 9000, Germany). Fragmentation and complete clearance of the common bile duct and pancreatic duct stones were obtained in 19 of 19 patients(100%). Apart from transient attacks of fever in 2 of 13 patients with common bile duct stones(15%) and mild elevation of serum amylase and lipase in 2 of 6 patients with pancreatic duct stones(33%), no other serious side effects were observed. In our experiences, extracorporeal shock-wave lithotripsy is a safe and useful treatment for endoscopically unretrievable common bile duct and pancreatic duct stones.

  6. Vitellointestinal Duct Anomalies in Infancy

    Science.gov (United States)

    Kadian, Yogender Singh; Verma, Anjali; Rattan, Kamal Nain; Kajal, Pardeep

    2016-01-01

    Background: Vitellointestinal duct (VID) or omphalomesenteric duct anomalies are secondary to the persistence of the embryonic vitelline duct, which normally obliterates by weeks 5–9 of intrauterine life. Methods: This is a retrospective analysis of a total of 16 patients of symptomatic remnants of vitellointestinal duct from period of Jan 2009 to May 2013. Results: Male to female ratio (M:F) was 4.3:1 and mean age of presentation was 2 months and their mode of presentation was: patent VID in 9 (56.25%) patients, umbilical cyst in 2(12.25%), umbilical granuloma in 2 (12.25%), and Meckel diverticulum as content of hernia sac in obstructed umbilical hernia in 1 (6.25%) patient. Two patients with umbilical fistula had severe electrolyte disturbance and died without surgical intervention. Conclusion: Persistent VID may have varied presentations in infancy. High output umbilical fistula and excessive bowel prolapse demand urgent surgical intervention to avoid morbidity and mortality. PMID:27433448

  7. Fan/Ram Duct Program

    Science.gov (United States)

    1973-10-01

    mwm^mmmt c INPUT I ] H—f TRANSIENT ROUTINE P"" CONTROL """I FAN ] COMPRESSOR MAIN BURNER I DUCT HZ HIGH TURBINE in— LOW TURBINE I...and pressure ratio. 6. Low Turbine Low turbine characteristics, identical In form to those of the high turbine, are shown in figures 27 and 28. 7

  8. Impedance Eduction in Large Ducts Containing Higher-Order Modes and Grazing Flow

    Science.gov (United States)

    Watson, Willie R.; Jones, Michael G.

    2017-01-01

    Impedance eduction test data are acquired in ducts with small and large cross-sectional areas at the NASA Langley Research Center. An improved data acquisition system in the large duct has resulted in increased control of the acoustic energy in source modes and more accurate resolution of higher-order duct modes compared to previous tests. Two impedance eduction methods that take advantage of the improved data acquisition to educe the liner impedance in grazing flow are presented. One method measures the axial propagation constant of a dominant mode in the liner test section (by implementing the Kumarsean and Tufts algorithm) and educes the impedance from an exact analytical expression. The second method solves numerically the convected Helmholtz equation and minimizes an objective function to obtain the liner impedance. The two methods are tested first on data synthesized from an exact mode solution and then on measured data. Results show that when the methods are applied to data acquired in the larger duct with a dominant higher-order mode, the same impedance spectra are educed as that obtained in the small duct where only the plane wave mode propagates. This result holds for each higher-order mode in the large duct provided that the higher-order mode is sufficiently attenuated by the liner.

  9. Suppression of broadband noise radiated by a low-speed fan in a duct.

    Science.gov (United States)

    Huang, L; Ma, X; Feng, L G

    2010-07-01

    Attenuation of ducted fan noise remains a technical challenge in the low frequency range as traditional duct lining becomes ineffective. This study proposes a reactive method to suppress the sound radiation from an axial-flow fan. The method is particularly effective in the low frequency region and covers a broad band. Its effect is derived from two mechanisms. One is the reduction in the confining effects of duct walls when the duct radius is increased; the other is the acoustic interference between the direct radiation from the fan and reflections by the duct junctions. This interference is always destructive for axial dipoles when the frequency approaches zero. This performance differs from normal passive control methods, which become totally ineffective toward zero frequency. An approximate plane-wave theory explains the essential physics of the method, and its quantitative prediction is found to agree well with a full numerical simulation using a spectral method of Chebyshev collocation. The latter is validated by experiment using an axial-flow fan in a duct of finite length. Broadband noise reduction is achieved while the flow speed is kept unchanged. Practical difficulties of implementation for a fan with high pressure increase are discussed.

  10. Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions

    Science.gov (United States)

    Woodward, Richard P.; Bock, Lawrence A.; Heidelberg, Laurence J.; Hall, David G.

    1992-01-01

    The ducted propeller offers structural and acoustic benefits typical of conventional turbofan engines while retaining much of the aeroacoustic benefits of the unducted propeller. A model Advanced Ducted Propeller (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The ADP model was designed and manufactured by the Pratt and Whitney Division of United Technologies. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and propeller axis angles-of-attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe which identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 5 dB fundamental tone reduction was associated with the long inlet and 40-vane sector, which may relate to inlet duct geometry. The fundamental tone level was essentially unaffected by propeller axis angle-of-attack at rotor speeds of at least 96 percent design.

  11. Acoustic cloaking and transformation acoustics

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Chan, C T, E-mail: kenyon@ust.h, E-mail: phchan@ust.h [Department of Physics and the William Mong Institute of NanoScience and Technology, The Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)

    2010-03-24

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  12. Acoustical Imaging

    CERN Document Server

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  13. Current surgical treatment for bile duct cancer

    Institute of Scientific and Technical Information of China (English)

    Yasuji Seyama; Masatoshi Makuuchi

    2007-01-01

    Since extrahepatic bile duct cancer is difficult to diagnose and to cure, a safe and radical surgical strategy is needed. In this review, the modes of infiltration and spread of extrahepatic bile duct cancer and surgical strategy are discussed. Extended hemihepatectomy, with or without pancreatoduodenectomy (PD), plus extrahepatic bile duct resection and regional lymphadenectomy has recently been recognized as the standard curative treatment for hilar bile duct cancer. On the other hand, PD is the choice of treatment for middle and distal bile duct cancer. Major hepatectomy concomitant with PD (hepatopancreatoduodenectomy) has been applied to selected patients with widespread tumors. Preoperative biliary drainage (BD) followed by portal vein embolization (PVE) enables major hepatectomy in patients with hilar bile duct cancer without mortality. BD should be performed considering the surgical procedure, especially, in patients with separated intrahepatic bile ducts caused by hilar bile duct cancer. Right or left trisectoriectomy are indicated according to the tumor spread and biliary anatomy. As a result, extended radical resection offers a chance for cure of hilar bile duct cancer with improved resectability, curability, and a 5-year survival rate of 40%. A 5-year survival rate has ranged from 24% to 39% after PD for middle and distal bile duct cancer.

  14. Numerical Predictions of Mode Reflections in an Open Circular Duct: Comparison with Theory

    Science.gov (United States)

    Dahl, Milo D.; Hixon, Ray

    2015-01-01

    The NASA Broadband Aeroacoustic Stator Simulation code was used to compute the acoustic field for higher-order modes in a circular duct geometry. To test the accuracy of the results computed by the code, the duct was terminated by an open end with an infinite flange or no flange. Both open end conditions have a theoretical solution that was used to compare with the computed results. Excellent comparison for reflection matrix values was achieved after suitable refinement of the grid at the open end. The study also revealed issues with the level of the mode amplitude introduced into the acoustic held from the source boundary and the amount of reflection that occurred at the source boundary when a general nonreflecting boundary condition was applied.

  15. Sound attenuation in rectangular and circular cross-section ducts with flow and bulk-reacting liner

    Science.gov (United States)

    Bies, D. A.; Hansen, C. H.; Bridges, G. E.

    1991-04-01

    A generalized theory is presented for sound propagation in lined ducts of arbitrary cross-section where acoustic wave propagation in the lining is also taken into account. The effects of a mean fluid flow in the duct airway, an anisotropic bulk reacting liner and a limp, impervious membrane covering the liner are all taken into account. Simple extension of the formalism to include the effect of a perforated facing is also provided. Bulk reacting and locally reacting liners are treated as limiting cases. The general analysis is applied to ducts of both rectangular and circular cross-section, taking into account higher order modes as well as plane wave sound propagation. Design charts for duct attenuation in octave frequency band averages and in terms of dimensionless parameters are presented.

  16. Acoustic biosensors

    OpenAIRE

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of ...

  17. Acoustic textiles

    CERN Document Server

    Nayak, Rajkishore

    2016-01-01

    This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.

  18. Coupled Research in Ocean Acoustics and Signal Processing for the Next Generation of Underwater Acoustic Communication Systems

    Science.gov (United States)

    2016-08-05

    the analysis of data collected during the VHF acoustics test con- ducted in a wave tank at the Scripps Institution of Oceanography in October 2015...a follow-on experiment at the same location (Scripps Institution of Oceanogra- phy) commenced. In parallel, the Principle Investigator continued to...Student, Atulya Yellepeddi and is motivated by the desire to exploit lower dimensional struc- tures in acoustic communications data, specifically

  19. The Application of a Boundary Integral Equation Method to the Prediction of Ducted Fan Engine Noise

    Science.gov (United States)

    Dunn, M. H.; Tweed, J.; Farassat, F.

    1999-01-01

    The prediction of ducted fan engine noise using a boundary integral equation method (BIEM) is considered. Governing equations for the BIEM are based on linearized acoustics and describe the scattering of incident sound by a thin, finite-length cylindrical duct in the presence of a uniform axial inflow. A classical boundary value problem (BVP) is derived that includes an axisymmetric, locally reacting liner on the duct interior. Using potential theory, the BVP is recast as a system of hypersingular boundary integral equations with subsidiary conditions. We describe the integral equation derivation and solution procedure in detail. The development of the computationally efficient ducted fan noise prediction program TBIEM3D, which implements the BIEM, and its utility in conducting parametric noise reduction studies are discussed. Unlike prediction methods based on spinning mode eigenfunction expansions, the BIEM does not require the decomposition of the interior acoustic field into its radial and axial components which, for the liner case, avoids the solution of a difficult complex eigenvalue problem. Numerical spectral studies are presented to illustrate the nexus between the eigenfunction expansion representation and BIEM results. We demonstrate BIEM liner capability by examining radiation patterns for several cases of practical interest.

  20. Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method

    Directory of Open Access Journals (Sweden)

    Yunpeng Ma

    2017-01-01

    Full Text Available A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.

  1. A straightforward method for wall impedance eduction in a flow duct.

    Science.gov (United States)

    Jing, Xiaodong; Peng, Sen; Sun, Xiaofeng

    2008-07-01

    The development of the advanced liner technology for aeroengine noise control necessitates the impedance measurement method under realistic flow conditions. Currently, the methods for this need are mainly based on the inverse impedance eduction principle, confronting with the problems of initial guess, high computation cost, and low convergence. In view of this, a new strategy is developed that straightforwardly educes the impedance from the sound pressure information measured on the duct wall opposing to the test acoustic liner embedded in a flow duct. Here, the key insight is that the modal nature of the duct acoustic field renders a summed-exponential representation of the measured sound pressure; thus, the characterizing axial wave number can be readily extracted by means of Prony's method, and further the unknown impedance is calculated from the eigenvalue and dispersion relations based on the classical mode-decomposition analysis. This straightforward method is simple in its basic principle but remarkably has the advantages of ultimately overcoming the drawbacks inherent to the inverse methods, incorporating the realistic multimode nonprogressive wave effects, high computational efficiency, possibly reducing the measurement points, and even avoiding the necessity of the duct exit impedance that bothers perhaps all the existing waveguide methods.

  2. The generation of sound by vorticity waves in swirling duct flows

    Science.gov (United States)

    Howe, M. S.; Liu, J. T. C.

    1977-01-01

    Swirling flow in an axisymmetric duct can support vorticity waves propagating parallel to the axis of the duct. When the cross-sectional area of the duct changes a portion of the wave energy is scattered into secondary vorticity and sound waves. Thus the swirling flow in the jet pipe of an aeroengine provides a mechanism whereby disturbances produced by unsteady combustion or turbine blading can be propagated along the pipe and subsequently scattered into aerodynamic sound. In this paper a linearized model of this process is examined for low Mach number swirling flow in a duct of infinite extent. It is shown that the amplitude of the scattered acoustic pressure waves is proportional to the product of the characteristic swirl velocity and the perturbation velocity of the vorticity wave. The sound produced in this way may therefore be of more significance than that generated by vorticity fluctuations in the absence of swirl, for which the acoustic pressure is proportional to the square of the perturbation velocity. The results of the analysis are discussed in relation to the problem of excess jet noise.

  3. Experimental and Analytical Study of the Hydroacoustics of Propellers in Rigid Ducts

    Science.gov (United States)

    2006-07-01

    Broadband inflow noise due to ingested small-scale turbulence The inflow into any realistic turbomachine is turbulent, with a wide range of length...duct lengths. 32 SECTION 5 Flow Field and Acoustic Source Results Sound generation in low Mach number turbomachines is typically dominated by un...aerodynamic sound sources in turbomachines . Journal of Sound and Vibration, 181(3):369-389, 1995. [31] P. J. Huber. Robust Statistics. Wiley, 1981. 53 [32

  4. [Common bile duct stones and their complications].

    Science.gov (United States)

    Millat, B; Borie, F

    2000-12-01

    At the time of cholecystectomy for symptomatic cholelithiasis, 7-20% of patients have common bile duct stones. Nearly one third of them are asymptomatic. Routine cholangiography during cholecystectomy allows the diagnosis and treatment of common bile duct stones during the same operation. Selective indication for the diagnosis of common bile duct stones based on the positive predictive value of indicators limits treatment to symptomatic cases. No single indicator is however completely accurate in predicting common bile duct stones and the natural history of asymptomatic cases is uncertain. Endoscopic stone extraction preceding cholecystectomy is not superior to one-stage surgical treatment. Diagnosis and treatment of common bile duct stones are feasible laparoscopically. Complications of common bile duct stones are cholangitis and acute pancreatitis; if severe, they require specific therapeutic approaches.

  5. Methods of evaluating cleanliness of ventilation ducts

    Institute of Scientific and Technical Information of China (English)

    曹勇; 罗运有; 于丹; 甘丽斯

    2009-01-01

    A testing system for evaluating cleanliness of ventilation ducts was constructed. Comparisons of four evaluation methods for quantifying the amount of dust on the inner surface of ventilation ducts are presented. The experimental results show that the wiping by solvent method is more efficient than that by the wiping method,especially used on low cleanliness duct surface. The gravimetric tape method is an efficient method of collecting dust samples on the duct surface with low amounts of dust,particularly used to check the cleanliness level after the cleaning work. The optical method can be set up rapidly and is useful for fieldwork measurements.

  6. On acoustic intensity measurements in the presence of mean flow

    Science.gov (United States)

    Munro, D. H.; Ingard, K. U.

    1979-01-01

    A theoretical analysis demonstrates that the technique of measuring acoustic intensity by means of cross correlation between nearby microphones cannot, in general, be extended to situations in which there is mean flow. However, it may be possible to use this technique to measure intensities in ducts with mean flow at frequencies below their cutoff frequencies.

  7. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... chapters represent review articles covering the most relevant areas of the field. They are written with the goal of providing students with comprehensive introductions. Further they offer a supply of numerous references to the relevant literature. Besides its usefulness as a textbook, this will make...

  8. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  9. 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.

  10. 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.

  11. The attenuation of the higher-order cross-section modes in a duct with a thin porous layer.

    Science.gov (United States)

    Yin, Yean; Horoshenkov, Kirill V

    2005-02-01

    A numerical method for sound propagation of higher-order cross-sectional modes in a duct of arbitrary cross-section and boundary conditions with nonzero, complex acoustic admittance has been considered. This method assumes that the cross-section of the duct is uniform and that the duct is of a considerable length so that the longitudinal modes can be neglected. The problem is reduced to a two-dimensional (2D) finite element (FE) solution, from which a set of cross-sectional eigen-values and eigen-functions are determined. This result is used to obtain the modal frequencies, velocities and the attenuation coefficients. The 2D FE solution is then extended to three-dimensional via the normal mode decomposition technique. The numerical solution is validated against experimental data for sound propagation in a pipe with inner walls partially covered by coarse sand or granulated rubber. The values of the eigen-frequencies calculated from the proposed numerical model are validated against those predicted by the standard analytical solution for both a circular and rectangular pipe with rigid walls. It is shown that the considered numerical method is useful for predicting the sound pressure distribution, attenuation, and eigen-frequencies in a duct with acoustically nonrigid boundary conditions. The purpose of this work is to pave the way for the development of an efficient inverse problem solution for the remote characterization of the acoustic boundary conditions in natural and artificial waveguides.

  12. Extracorporeal piezoelectric lithotripsy for retained bile duct stones.

    Science.gov (United States)

    Weber, J; Adamek, H E; Riemann, J F

    1992-05-01

    Extracorporeal piezoelectric shock wave lithotripsy (EPL) was performed in 35 patients with endoscopically non-extractable stones. With this lithotripter, stones are visualized by ultrasound and shock waves are produced by a piezoelectric acoustic generator. The stones could be localized in 32 out of 35 patients. Fragmentation was achieved in 91.4% and complete stone removal in 77.1%. These results show that piezoelectric lithotripsy is also a useful method for the treatment of complicated bile duct stones, as already demonstrated for the electrohydraulically and electromagnetically generated shock waves systems. The piezoelectric system is especially useful in elderly and frail patients because no general anesthesia is needed and only 14% of cases require analgesia or sedation.

  13. Double-duct liquid metal magnetohydrodynamic engine

    Science.gov (United States)

    Haaland, Carsten M.

    1995-01-01

    An internal combustion, liquid metal (LM) magnetohydrodynamic (MHD) engine and an alternating current (AC) magnetohydrodynamic generator, are used in combination to provide useful AC electric energy output. The engine design has-four pistons and a double duct configuration, with each duct containing sodium potassium liquid metal confined between free pistons located at either end of the duct. The liquid metal is forced to flow back and forth in the duct by the movement of the pistons, which are alternatively driven by an internal combustion process. In the MHD generator, the two LM-MHD ducts pass in close proximity through a Hartmann duct with output transformer. AC power is produced by operating the engine with the liquid metal in the two generator ducts always flowing in counter directions. The amount of liquid metal maintained in the ducts may be varied. This provides a variable stroke length for the pistons. The engine/generator provides variable AC power at variable frequencies that correspond to the power demands of the vehicular propulsion. Also the engine should maintain nearly constant efficiency throughout the range of power usage. Automobiles and trucks could be powered by the invention, with no transmission or power converter devices being required.

  14. A rare case of bile duct cyst

    Institute of Scientific and Technical Information of China (English)

    Qing-Gang Wang; Shu-Tian Zhang

    2009-01-01

    Choledochal cyst is an uncommon disease usually seen in young women and can be divided into five types. We report a 66-year-old woman who was diagnosed with types Ⅱ and Ⅱ bile duct cyst simultaneously after surgery, which is a rare type of bile duct cyst.

  15. New cannulation method for pancreatic duct cannulation-bile duct guidewire-indwelling method

    Science.gov (United States)

    Sakai, Yuji; Ishihara, Takeshi; Tsuyuguchi, Toshio; Tawada, Katsunobu; Saito, Masayoshi; Kurosawa, Jo; Tamura, Ryo; Togo, Seiko; Mikata, Rintaro; Tada, Motohisa; Yokosuka, Osamu

    2011-01-01

    The patient was a 58-year-old male with symptomatic alcoholic chronic pancreatitis. Since a 10 mm calculus was observed in the pancreatic body and abdominal pain occurred due to congestion of pancreatic juice, endoscopic retrograde cholangiopancreatography was conducted for assessment of the pancreatic duct and treatment of pancreatic calculus. Pancreatogram was slightly and insufficiently obtained by injecting the contrast media via the common channel of the duodenal main papilla. We tried to cannulate selectively into the pancreatic duct for a clear image. However, the selective cannulation of the pancreatic duct was difficult because of instability of the papilla. On the other hand, selective cannulation of the bile duct was relatively easily achieved. Therefore, after the imaging of the bile duct, a guidewire was retained in the bile duct to immobilize the duodenal papilla and cannulation of the pancreatic duct was attempted. As a result, selective pancreatic duct cannulation became possible. It is considered that the bile duct guidewire-indwelling method may serve as one of the useful techniques for cases whose selective pancreatic duct cannulation is difficult (“selective pancreatic duct difficult cannulation case”). PMID:22110840

  16. Pancreatic duct holder for facilitating duct-to-mucosa pancreatojejunostomy after pancreatoduodenectomy.

    Science.gov (United States)

    Sugiyama, Masanori; Suzuki, Yutaka; Abe, Nobutsugu; Ueki, Hisayo; Masaki, Tadahiko; Mori, Toshiyuki; Atomi, Yutaka

    2009-01-01

    Duct-to-mucosa pancreatojejunostomy after pancreatoduodenectomy may be technically difficult, particularly in cases in which the remnant pancreas is soft with a small main pancreatic duct. We devised a pancreatic duct holder for duct-to-mucosa pancreatojejunostomy. The holder has a cone-shaped tip. A one-third circle of the tip is cut away, which makes a slit. As the tip is inserted gently into the pancreatic duct, the duct can be adequately expanded. The holder provides a good surgical field for anastomosis. A slit of the tip allows needle insertion. The holder facilitates stitches of the jejunum also. Twelve patients underwent pancreatoduodenectomy, followed by duct-to-mucosa pancreatojejunostomy using the holder. The holder allowed 8 or more stitches in duct-to-mucosa anastomosis, even in patients with a small pancreatic duct. No patients developed prolonged pancreatic leakage or pancreatic fistula postoperatively. In conclusion, the pancreatic duct holder is a simple and useful tool for facilitating duct-to-mucosa pancreatojejunostomy.

  17. Bile duct hamartomas (von Mayenburg complexes) mimicking liver metastases from bile duct cancer: MRC findings

    Institute of Scientific and Technical Information of China (English)

    Yasuhiko Nagano; Kenichi Matsuo; Katsuya Gorai; Kazuya Sugimori; Chikara Kunisaki; Hideyuki Ike; Katsuaki Tanaka; Toshio Imada; Hiroshi Shimada

    2006-01-01

    We present a case of a 72-year-old man with a common bile duct cancer, who was initially believed to have multiple liver metastases based on computed tomography findings, and in whom magnetic resonance cholangiography (MRC) revealed a diagnosis of bile duct hamartomas. At exploration for pancreaticoduodenectomy, liver palpation revealed disseminated nodules at the surface of the liver. These nodules showed gray-white nodular lesions of about 0.5cm in diameter scattered on the surface of both liver lobes, which were looked like multiple liver metastases from bile duct cancer. Frozen section of the liver biopsy disclosed multiple bile ducts with slightly dilated lumens embedded in the collagenous stroma characteristics of multiple bile duct hamartomas (BDHs). Only two reports have described the MRC features of bile duct hamartomas. Of all imaging procedures, MRC provides the most relevant features for the imaging diagnosis of bile duct hamartomas.

  18. Complex resonances and trapped modes in ducted domains

    Science.gov (United States)

    Duan, Yuting; Koch, Werner; Linton, Chris M.; McIver, Maureen

    Owing to radiation losses, resonances in open systems, i.e. solution domains which extend to infinity in at least one direction, are generally complex valued. However, near symmetric centred objects in ducted domains, or in periodic arrays, so-called trapped modes can exist below the cut-off frequency of the first non-trivial duct mode. These trapped modes have no radiation loss and correspond to real-valued resonances. Above the first cut-off frequency isolated trapped modes exist only for specific parameter combinations. These isolated trapped modes are termed embedded, because their corresponding eigenvalues are embedded in the continuous spectrum of an appropriate differential operator. Trapped modes are of considerable importance in applications because at these parameters the system can be excited easily by external forcing. In the present paper directly computed embedded trapped modes are compared with numerically obtained resonances for several model configurations. Acoustic resonances are also computed in two-dimensional models of a butterfly and a ball-type valve as examples of more complicated geometries.

  19. 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.

  20. Acoustics Research

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  1. Battlefield acoustics

    CERN Document Server

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  2. Acoustical Imaging

    CERN Document Server

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  3. Room Acoustics

    Science.gov (United States)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  4. Acoustic resonance phenomena in air bleed channels in aviation engines

    Science.gov (United States)

    Aleksentsev, A. A.; Sazhenkov, A. N.; Sukhinin, S. V.

    2016-11-01

    The existence of axial-radial acoustic resonance oscillations of the basic air flow in bleed channels of aviation engines is demonstrated theoretically and experimentally. Numerical and analytical methods are used to determine the frequency of acoustic resonance oscillations for the lowest modes of open and closed bleed channels of the PS-90A engine. Experimental investigations reveal new acoustic resonance phenomena arising in the air flow in bleed channel cavities in the core duct of this engine owing to instability of the basic air flow. The results of numerical, analytical, and experimental studies of the resonance frequencies reached in the flow in bleed channel cavities in the core duct of the PS-90A engine are found to be in reasonable agreement. As a result, various types of resonance oscillations in bleed channels can be accurately described.

  5. Sound Transmission in a Duct with Sudden Area Expansion, Extended Inlet, and Lined Walls in Overlapping Region

    Directory of Open Access Journals (Sweden)

    Ahmet Demir

    2016-01-01

    Full Text Available The transmission of sound in a duct with sudden area expansion and extended inlet is investigated in the case where the walls of the duct lie in the finite overlapping region lined with acoustically absorbent materials. By using the series expansion in the overlap region and using the Fourier transform technique elsewhere we obtain a Wiener-Hopf equation whose solution involves a set of infinitely many unknown expansion coefficients satisfying a system of linear algebraic equations. Numerical solution of this system is obtained for various values of the problem parameters, whereby the effects of these parameters on the sound transmission are studied.

  6. Clinical significance of main pancreatic duct dilation on computed tomography: Single and double duct dilation

    Institute of Scientific and Technical Information of China (English)

    Mark D Edge; Maarouf Hoteit; Amil P Patel; Xiaoping Wang; Deborah A Baumgarten; Qiang Cai

    2007-01-01

    AIM: To study the patients with main pancreatic duct dilation on computed tomography (CT) and thereby to provide the predictive criteria to identify patients at high risk of significant diseases, such as pancreatic cancer, and to avoid unnecessary work up for patients at low risk of such diseases.METHODS: Patients with dilation of the main pancreatic duct on CT at Emory University Hospital in 2002 were identified by computer search. Clinical course and ultimate diagnosis were obtained in all the identified patients by abstraction of their computer database records.RESULTS: Seventy-seven patients were identified in this study. Chronic pancreatitis and pancreatic cancer were the most common causes of the main pancreatic duct dilation on CT. Although the majority of patients with isolated dilation of the main pancreatic duct (single duct dilation) had chronic pancreatitis, one-third of patients with single duct dilation but without chronic pancreatitis had pancreatic malignancies, whereas most of patients with concomitant biliary duct dilation (double duct dilation) had pancreatic cancer.CONCLUSION: Patients with pancreatic double duct dilation need extensive work up and careful follow up since a majority of these patients are ultimately diagnosed with pancreatic cancer. Patients with single duct dilation, especially such patients without any evidence of chronic pancreatitis, also need careful follow-up since the possibility of pancreatic malignancy, including adenocarcinoma and intraductal papillary mucinous tumors, is still high.

  7. Bile Duct Adenoma with Oncocytic Features

    Directory of Open Access Journals (Sweden)

    E. J. Johannesen

    2014-01-01

    Full Text Available Bile duct adenomas are benign bile duct proliferations usually encountered as an incidental finding. Oncocytic bile duct neoplasms are rare and the majority are malignant. A 61-year-old male with a diagnosis of colorectal adenocarcinoma was undergoing surgery when a small white nodule was discovered on the surface of the right lobe of his liver. This lesion was composed of cytologically bland cells arranged in tightly packed glands. These cells were immunopositive for cytokeratin 7, negative for Hep Par 1, contained mucin, and had a Ki67 proliferation index of 8%. The morphology, immunophenotype, presence of mucin, and normal appearing bile ducts, as well as the increased Ki67 proliferation rate, were consistent with a bile duct adenoma with oxyphilic (oncocytic change. Oncocytic tumors in the liver are rare; the first described in 1992. Only two bile duct adenomas with oncocytic change have been reported and neither of them had reported mucin production or the presence of normal appearing bile ducts within the lesion.

  8. Paraurethral Skene's duct cyst in a newborn

    Science.gov (United States)

    Moralioğlu, Serdar; Bosnalı, Oktav; Celayir, Ayşenur Cerrah; Şahin, Ceyhan

    2013-01-01

    Paraurethral or Skene's duct cysts are rare causes of interlabial masses in neonates. The diagnosis of Skene's duct cysts in the neonatal period is based on its location, in relation to the urethra, and the demonstration of transitional epithelium in the cyst wall. The distinguishing features of paraurethral cysts are the displacement of urethral meatus by the mass and a cyst containing milky fluid. Thus, we report a case of a Skene's duct cyst in a newborn which was treated by incision and drainage. PMID:24049387

  9. An improved multimodal method for sound propagation in nonuniform lined ducts.

    Science.gov (United States)

    Bi, WenPing; Pagneux, Vincent; Lafarge, Denis; Aurégan, Yves

    2007-07-01

    An efficient method is proposed for modeling time harmonic acoustic propagation in a nonuniform lined duct without flow. The lining impedance is axially segmented uniform, but varies circumferentially. The sound pressure is expanded in term of rigid duct modes and an additional function that carries the information about the impedance boundary. The rigid duct modes and the additional function are known a priori so that calculations of the true liner modes, which are difficult, are avoided. By matching the pressure and axial velocity at the interface between different uniform segments, scattering matrices are obtained for each individual segment; these are then combined to construct a global scattering matrix for multiple segments. The present method is an improvement of the multimodal propagation method, developed in a previous paper [Bi et al., J. Sound Vib. 289, 1091-1111 (2006)]. The radial rate of convergence is improved from O(n(-2)), where n is the radial mode indices, to O(n(-4)). It is numerically shown that using the present method, acoustic propagation in the nonuniform lined intake of an aeroengine can be calculated by a personal computer for dimensionless frequency K up to 80, approaching the third blade passing frequency of turbofan noise.

  10. Acoustic biosensors

    Science.gov (United States)

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  11. Transition duct assembly with modified trailing edge in turbine system

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, Kevin Weston; Schott, Carl Gerard; Ingram, Clint Luigie; Siden, Gunnar Leif; Pierre, Sylvain

    2016-10-04

    Transition duct assemblies for turbine systems and turbomachines are provided. In one embodiment, a transition duct assembly includes a plurality of transition ducts disposed in a generally annular array and comprising a first transition duct and a second transition duct. Each of the plurality of transition ducts 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 each transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The transition duct assembly further includes an aerodynamic structure defined by the passages of the first transition duct and the second transition duct. The aerodynamic structure includes a pressure side, a suction side, and a trailing edge, the trailing edge having a modified aerodynamic contour.

  12. 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

  13. Transmission of wave energy in curved ducts

    Science.gov (United States)

    Rostafinski, W.

    1973-01-01

    A formation of wave energy flow was developed for motion in curved ducts. A parametric study over a range of frequencies determined the ability of circular bends to transmit energy for the case of perfectly rigid walls.

  14. Ducted propagation of chorus waves: Cluster observations

    Directory of Open Access Journals (Sweden)

    K. H. Yearby

    2011-09-01

    Full Text Available Ducted propagation of whistler waves in the terrestrial magnetosphere-ionosphere system was discussed and studied long before the first in-situ spacecraft measurements. While a number of implicit examples of the existence of ducted propagation have been found, direct observation of ducts has been hampered by the low sampling rates of measurements of the plasma density. The present paper is based on Cluster observations of chorus waves. The ability to use measurements of the spacecraft potential as a proxy for high time resolution electron density measurements is exploited to identify a number of cases when increased chorus wave power, observed within the radiation belts, is observed simultaneously with density enchantments. It is argued that the observation of ducted propagation of chorus implies modification of numerical models for plasma-wave interactions within the radiation belts.

  15. General Information about Extrahepatic Bile Duct Cancer

    Science.gov (United States)

    ... duct cancer include jaundice and pain in the abdomen. These and other signs and symptoms may be ... Dark urine . Clay colored stool . Pain in the abdomen . Fever . Itchy skin. Nausea and vomiting . Weight loss ...

  16. Treatment Options for Extrahepatic Bile Duct Cancer

    Science.gov (United States)

    ... duct cancer include jaundice and pain in the abdomen. These and other signs and symptoms may be ... Dark urine . Clay colored stool . Pain in the abdomen . Fever . Itchy skin. Nausea and vomiting . Weight loss ...

  17. Stages of Extrahepatic Bile Duct Cancer

    Science.gov (United States)

    ... duct cancer include jaundice and pain in the abdomen. These and other signs and symptoms may be ... Dark urine . Clay colored stool . Pain in the abdomen . Fever . Itchy skin. Nausea and vomiting . Weight loss ...

  18. Treatment Option Overview (Extrahepatic Bile Duct Cancer)

    Science.gov (United States)

    ... duct cancer include jaundice and pain in the abdomen. These and other signs and symptoms may be ... Dark urine . Clay colored stool . Pain in the abdomen . Fever . Itchy skin. Nausea and vomiting . Weight loss ...

  19. Droplets Acoustics

    CERN Document Server

    Dahan, Raphael; Carmon, Tal

    2015-01-01

    Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.

  20. 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

  1. Energy Conservation Through Duct Leakage Reduction

    Science.gov (United States)

    2004-02-26

    Energy Conservation Through Duct Leakage Reduction February 26, 2004 Rich Glatt – Lindab Inc. Report Documentation Page Form ApprovedOMB No. 0704...4. TITLE AND SUBTITLE Energy Conservation Through Duct Leakage Reduction 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...Wall – DW that installs like SW - easiest installing DW system on the market – Eliminates the need for costly flanged connections – SMACNA Leakage

  2. Boundary layer control device for duct silencers

    Science.gov (United States)

    Schmitz, Fredric H. (Inventor); Soderman, Paul T. (Inventor)

    1993-01-01

    A boundary layer control device includes a porous cover plate, an acoustic absorber disposed under the porous cover plate, and a porous flow resistive membrane interposed between the porous cover plate and the acoustic absorber. The porous flow resistive membrane has a flow resistance low enough to permit sound to enter the acoustic absorber and high enough to damp unsteady flow oscillations.

  3. Conceptual design study of advanced acoustic-composite nacelles

    Science.gov (United States)

    Nordstrom, K. E.; Marsh, A. H.; Sargisson, D. F.

    1975-01-01

    Conceptual studies were conducted to assess the impact of incorporating advanced technologies in the nacelles of a current wide-bodied transport and an advanced technology transport. The improvement possible in the areas of fuel consumption, flyover noise levels, airplane weight, manufacturing costs, and airplane operating cost were evaluated for short and long-duct nacelles. Use of composite structures for acoustic duct linings in the fan inlet and exhaust ducts was considered as well as for other nacelle components. For the wide-bodied transport, the use of a long-duct nacelle with an internal mixer nozzle in the primary exhaust showed significant improvement in installed specific fuel consumption and airplane direct operating costs compared to the current short-duct nacelle. The long-duct mixed-flow nacelle is expected to achieve significant reductions in jet noise during takeoff and in turbo-machinery noise during landing approach. Recommendations were made of the technology development needed to achieve the potential fuel conservation and noise reduction benefits.

  4. Amputation neuroma mimics common hepatic duct carcinoma.

    Science.gov (United States)

    Koike, N; Todoroki, T; Kawamoto, T; Inagawa, S; Yoshida, S; Fukao, K

    2000-01-01

    Most amputation neuromas of the biliary tract occur in the cystic duct stump after cholecystectomy and are asymptomatic. However, when they arise in the main hepatic duct and are associated with obstructive jaundice, it is difficult to distinguish them from carcinoma. We describe a case in which preoperative differential diagnosis was difficult. A 60-year-old man was admitted to the Institute of Clinical Medicine, University of Tsukuba, with a chief complaint of jaundice. Cholangiography showed an irregularly elevated nodular lesion on the lateral wall of the common hepatic duct and multiple floating stones in the choledochus. Ultrasonography and computed tomography revealed one-sided regional thickening of the common hepatic duct associated with dilatation of the intrahepatic and extrahepatic bile ducts. Carbohydrate antigen 19-9 level was markedly elevated to 11,200 IU/mL in the bile juice, but was only 38 IU/mL in the serum, below the limit of abnormality. Cholangioscopy showed papillary tumor with coarse granular surface mimicking papillary carcinoma, but biopsy revealed no malignancy. The patient underwent hepaticocholedochus resection. Although the macroscopic finding from the surgical specimens was papillary carcinoma of the common hepatic duct penetrating to the hepatoduodenal ligament, histopathological examination revealed an amputation neuroma consisting of hypertrophic nerve tissues and giant cells containing foreign bodies, probably as a consequence of a previous cholecystectomy. The postoperative course was uneventful and the patient has been living well for the 5 years since the resection.

  5. 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.

  6. Double common bile duct: A case report

    Institute of Scientific and Technical Information of China (English)

    Srdjan P Djuranovic; Milenko B Ugljesic; Nenad S Mijalkovic; Viktorija A Korneti; Nada V Kovacevic; Tamara M Alempijevic; Slaven V Radulovic; Dragan V Tomic; Milan M Spuran

    2007-01-01

    Double common bile duct (DCBD) is a rare congenital anomaly in which two common bile ducts exist. One usually has normal drainage into the papilla duodeni major and the other usually named accessory common bile duct (ACBD) opens in different parts of upper gastrointestinal tract (stomach, duodenum, ductus pancreaticus or septum). This anomaly is of great importance since it is often associated with biliary lithiasis, choledochal cyst, anomalous pancreaticobiliary junction (APBJ) and upper gastrointestinal tract malignancies. We recently recognized a rare case of DCBD associated with APBJ with lithiasis in better developed common bile duct. The opening site of ACBD was in the pancreatic duct. The anomaly was suspected by transabdominal ultrasonography and finally confirmed by endoscopic retrograde cholangiopancreatography (ERCP) followed by endoscopic sphincterotomy and stone extraction. According to the literature, the existence of DCBD with the opening of ACBD in the pancreatic duct is most frequently associated with APBJ and gallbladder carcinoma. In case of DCBD, the opening site of ACBD is of greatest clinical importance because of its close implications with concomitant pathology. The adequate diagnosis of this rare anomaly is significant since the operative complications may occur in cases with DCBD which is not recognized prior to surgical treatment.

  7. Practical modeling of acoustic losses in air due to heat conduction and viscosity

    DEFF Research Database (Denmark)

    Christensen, René; Juhl, Peter Møller; Cutanda Henríquez, Vicente

    2008-01-01

    Accurate acoustics models of small devices with cavities and narrow slits and ducts should include the socalled boundary layer attenuation caused by thermal conduction and viscosity. The purpose of this paper is to present and compare different methods for including these loss mechanisms in analy......Accurate acoustics models of small devices with cavities and narrow slits and ducts should include the socalled boundary layer attenuation caused by thermal conduction and viscosity. The purpose of this paper is to present and compare different methods for including these loss mechanisms...

  8. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    Science.gov (United States)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a 'Gutin' propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  9. Aero-acoustics in a tangential blower: validation of the CFD flow distribution using advanced PIV techniques

    Directory of Open Access Journals (Sweden)

    Jean-Yves Noël

    2007-12-01

    Full Text Available Noise reduction is of increasing importance in the community. Consequently, the development of aero-acoustics is gaining special focus within industry. Computational Aero-Acoustics (CAA, the coupling of Computational Fluid Dynamics (CFD and Computational Acoustics (CA, is being used in the design and assessment of a range of products from HVAC ducts to domestic appliances. The process for carrying out an Aero-Acoustic simulation begins with the solution of the transient flow dynamics in order to compute accurately the pressure fluctuations at a number of points in the computational domain. These fluctuations are passed to the acoustic code to propagate the acoustic waves through the system and determine its acoustic signature. To minimize errors in the acoustic propagation analysis it is thus essential that accurate predictions of the noise sources be obtained. This paper concentrates on the CFD part of the aero-acoustic simulation. The case considered has been taken from the European project DESTINY:3 and comprises a tangential blower located inside a complex duct system. Air is drawn into the fan through two inlets and exits through a single duct. The computational methodology and flow field predictions are presented and compared to experimental PIV data. The numerical predictions were found to be in good agreement with the experimental data, reproducing the asymmetries in the flow field.

  10. An efficient, direct finite difference method for computing sound propagation in arbitrarily shaped two-dimensional and axisymmetric ducts without flow

    Science.gov (United States)

    Chakravarthy, S.

    1978-01-01

    An efficient, direct finite difference method is presented for computing sound propagation in non-stepped two-dimensional and axisymmetric ducts of arbitrarily varying cross section without mean flow. The method is not restricted by axial variation of acoustic impedance of the duct wall linings. The non-uniform two-dimensional or axisymmetric duct is conformally mapped numerically into a rectangular or cylindrical computational domain using a new procedure based on a method of fast direct solution of the Cauchy-Riemann equations. The resulting Helmholtz equation in the computational domain is separable. The solution to the governing equation and boundary conditions is expressed as a linear combination of fundamental solutions. The fundamental solutions are computed only once for each duct shape by means of the fast direct cyclic reduction method for the discrete solution of separable elliptic equations. Numerical results for several examples are presented to show the applicability and efficiency of the method.

  11. Transfer element method with application to acoustic design of aeroengine nacelle

    Directory of Open Access Journals (Sweden)

    Wang Xiaoyu

    2015-04-01

    Full Text Available In the present survey, various methods for the acoustic design of aeroengine nacelle are first briefly introduced along with the comments on their advantages and disadvantages for practical application, and then detailed analysis and discussion focus on a kind of new method which is called “transfer element method” (TEM with emphasis on its application in the following three problems: turbomachinery noise generations, sound transmission in ducts and radiation from the inlet and outlet of ducts, as well as the interaction between them. In the theoretical frame of the TEM, the solution of acoustic field in an infinite duct with stator sound source or liner is extended to that in a finite domain with all knows and unknowns on the interface plane, and the relevant acoustic field is solved by setting up matching equation. In addition, based on combining the TEM with the boundary element method (BEM by establishing the pressure and its derivative continuum conditions on the inlet and outlet surface, the sound radiation from the inlet and outlet of ducts can also be investigated. Finally, the effects of various interactions between the sound source and acoustic treatment have been discussed in this survey. The numerical examples indicate that it is quite important to consider the effect of such interactions on sound attenuation during the acoustic design of aeroengine nacelle.

  12. Evaluating the Acoustic Effect of Over-the-Rotor Foam-Metal Liner Installed on a Low Speed Fan Using Virtual Rotating Microphone Imaging

    Science.gov (United States)

    Sutliff, Daniel L.; Dougherty, Robert P.; Walker, Bruce E.

    2010-01-01

    An in-duct beamforming technique for imaging rotating broadband fan sources has been used to evaluate the acoustic characteristics of a Foam-Metal Liner installed over-the-rotor of a low-speed fan. The NASA Glenn Research Center s Advanced Noise Control Fan was used as a test bed. A duct wall-mounted phased array consisting of several rings of microphones was employed. The data are mathematically resampled in the fan rotating reference frame and subsequently used in a conventional beamforming technique. The steering vectors for the beamforming technique are derived from annular duct modes, so that effects of reflections from the duct walls are reduced.

  13. Transduodenal exploration of the common bile duct in patients with nondilated ducts.

    Science.gov (United States)

    Ratych, R E; Sitzmann, J V; Lillemoe, K D; Yeo, C J; Cameron, J L

    1991-07-01

    Exploration of the small common bile duct can be technically difficult and is associated with a significant risk of ductal injury or late stricture, or both. Transduodenal common duct exploration after sphincteroplasty (TCDE/S) is an alternative method of duct exploration that avoids choledochotomy. Cholecystectomy followed by TCDE/S was performed upon 28 patients with nondilated ducts and suspected choledocholithiasis. Common duct stones were retrieved in 17 patients. Failure to retrieve stones in the remaining 11 patients was attributed to either false-positive results of cholangiography, forceful passage of stones into the duodenum during the initial insertion of a Fogarty catheter through the cystic duct or a false-negative finding at duct exploration. There was no perioperative mortality. Two patients had asymptomatic postoperative hyperamylasemia. One patient had postoperative pancreatitis, hyperbilirubinemia and cholangitis that resolved with antibiotic therapy by the eighth postoperative day. Other complications included wound infection, delayed gastric emptying, pneumonia and otitis media. The over-all morbidity rate was 28.6 per cent. Long term follow-up was obtained in all 28 patients. All patients in the follow-up group are free of recurrent biliary tract disease. TCDE/S appears to be a safe and effective method of exploring the nondilated common bile duct.

  14. 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

  15. Acoustic transducer for acoustic microscopy

    Science.gov (United States)

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  16. 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.

  17. In-duct identification of a rotating sound source with high spatial resolution

    Science.gov (United States)

    Heo, Yong-Ho; Ih, Jeong-Guon; Bodén, Hans

    2015-11-01

    To understand and reduce the flow noise generation from in-duct fluid machines, it is necessary to identify the acoustic source characteristics precisely. In this work, a source identification technique, which can identify the strengths and positions of the major sound radiators in the source plane, is studied for an in-duct rotating source. A linear acoustic theory including the effects of evanescent modes and source rotation is formulated based on the modal summation method, which is the underlying theory for the inverse source reconstruction. A validation experiment is conducted on a duct system excited by a loudspeaker in static and rotating conditions, with two different speeds, in the absence of flow. Due to the source rotation, the measured pressure spectra reveal the Doppler effect, and the amount of frequency shift corresponds to the multiplication of the circumferential mode order and the rotation speed. Amplitudes of participating modes are estimated at the shifted frequencies in the stationary reference frame, and the modal amplitude set including the effect of source rotation is collected to investigate the source behavior in the rotating reference frame. By using the estimated modal amplitudes, the near-field pressure is re-calculated and compared with the measured pressure. The obtained maximum relative error is about -25 and -10 dB for rotation speeds at 300 and 600 rev/min, respectively. The spatial distribution of acoustic source parameters is restored from the estimated modal amplitude set. The result clearly shows that the position and magnitude of the main sound source can be identified with high spatial resolution in the rotating reference frame.

  18. Transurethral resection of the ejaculatory duct.

    Science.gov (United States)

    Paick, J S

    2000-05-01

    Complete bilateral ejaculatory duct obstruction has long been recognized as an uncommon, treatable form of male infertility. Partial ejaculatory duct obstruction reflects a disturbance of ejaculation where sperm quality is impaired during transit through the distal vas deferens and ejaculatory ducts. With the advent and increased use of high-resolution transrectal ultrasonography, abnormalities of the distal ejaculatory ducts related to infertility have been well documented. Although there are no pathognomonic findings associated with ejaculatory duct obstruction, several clinical findings are highly suggestive. In an infertile man with oligospermia or azoospermia with low ejaculate volume, normal secondary sexual characteristics, testes and hormonal profile and dilated seminal vesicles, midline cyst, or calcification on transrectal ultrasonography, ejaculatory duct obstruction is suggested. Of course, other causes of infertility may be concomitantly present and need to be searched for and treated as well. In selected cases, transurethral resection has resulted in marked improvement in semen parameters and pregnancies have been achieved. As is the case with all surgical procedures, proper patient selection and surgical experience are necessary to obtain optimal results. However, it appears that the treatments currently available for relief of ejaculatory obstruction are not optimally effective. Only approximately one half of treated patients will have an improvement in semen parameters and only about one quarter of treated patients will contribute to a pregnancy. What remains to be determined is how to manage the additional nearly 50% of patients who do not benefit from transurethral resection of ejaculatory obstruction. Based on my experience, I suggest that transrectal ultrasonography should be the first diagnostic procedure used when infertile men are suspected of having ejaculatory duct obstruction; however, vasography should still be considered for a more

  19. A wave-envelope technique for wave propagation in non-uniform ducts

    Science.gov (United States)

    Kaiser, J. E.; Nayfeh, A. H.

    1976-01-01

    The method of variation of parameters is used to analyze wave propagation in variable area, plane ducts with no mean flow. The method has an explicit representation of the fast axial variation of the acoustic modes, and numerical integration is required only for the slower axial variations of the mode amplitudes and phases. Results are presented which demonstrate the numerical advantages of the method. Comparison of the results with those of a small perturbation theory are given. The relationship between this method and the method of weighted residuals is discussed.

  20. Stability analysis of a noise control system in a duct by using delay differential equation

    Institute of Scientific and Technical Information of China (English)

    Masakazu Haraguchi; Hai Yan Hu

    2009-01-01

    The paper deals with the criteria for the closed-loop stability of a noise control system in a duct. To study the stability of the system, the model of delay differential equation is derived from the propagation of acoustic wave governed by a partial differential equation of hyperbolic type. Then, a simple feedback controller is designed, and its closed-loop stability is analyzed on the basis of the derived model of delay differential equation. The obtained criteria reveal the influence of the controller gain and the positions of a sensor and an actuator on the closed-loop stability. Finally, numerical simulations are presented to support the theoreti-cal results.

  1. Salivary duct carcinoma of the parotid gland

    Directory of Open Access Journals (Sweden)

    Mona Mlika

    2012-01-01

    Full Text Available Salivary duct carcinoma of the parotid gland is an uncommon tumor, highly aggressive. About 200 cases have been reported in the English literature. Pathomorphologically, these tumors showed great similarities to ductal carcinoma of the female breast, which is why they described this tumor as "salivary duct carcinoma." The authors describe a new case of salivary duct carcinoma of the parotid gland. We present the case of a 50-year-old patient with progressive facial paralysis. The MRI examination of the head showed two ill-defined formations. A malignant tumor was strongly suspected, so that a total left parotidectomy with excision of the adjacent facial nerve and left lymph node dissection was performed. Microscopic examination concluded to a salivary duct carcinoma of the left parotid gland negative with Her2/neu antibody with lymph node metastasis. There were no recurrences or metastases within 3 years of follow-up. Salivary duct carcinoma of the parotid gland is a rare tumor with an aggressive behavior. This is due to its propensity to infiltrate distant organs. The diagnosis is based on microscopic examination. Treatment modalities are non-consensual, but some authors advocate the necessity of aggressive approach, especially in tumors negative with Heur2/neu antibody. This is due to the fact that the overexpression of this antigen was reported to be associated with a poor prognosis.

  2. 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.

  3. Numerical simulation of flow past circular duct

    Institute of Scientific and Technical Information of China (English)

    Ze-gao YIN; Xian-wei Cao; Hong-da SHI; Jian MA

    2010-01-01

    The Renormalization Group(RNG)k-ε 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.

  4. Convolution seal for transition duct in turbine system

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-26

    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 feature for interfacing with an adjacent transition duct. The turbine system further includes a convolution seal contacting the interface feature to provide a seal between the interface feature and the adjacent transition duct.

  5. An effective absorbing boundary algorithm for acoustical wave propagator

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, Berenger's perfectly matched layer (PML) absorbing boundary condition for electromagnetic waves is introduced as the truncation area of the computational domain to absorb one-dimensional acoustic wave for the scheme of acoustical wave propagator (AWP). To guarantee the efficiency of the AWP algorithm, a regulated propagator matrix is derived in the PML medium.Numerical simulations of a Gaussian wave packet propagating in one-dimensional duct are carried out to illustraze the efficiency of the combination of PML and AWP. Compared with the traditional smoothing truncation windows technique of AWP, this scheme shows high computational accuracy in absorbing acoustic wave when the acoustical wave arrives at the computational edges. Optimal coefficients of the PML configurations are also discussed.

  6. Acoustic dose and acoustic dose-rate.

    Science.gov (United States)

    Duck, Francis

    2009-10-01

    Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.

  7. FLUID FLOW IN ROTATING HELICAL SQUARE DUCTS

    Institute of Scientific and Technical Information of China (English)

    Chen Hua-jun; Zhang Ben-zhao; Zhang Jin-suo

    2003-01-01

    A numerical study is made for a fully developed laminar flow in rotating helical pipes.Due to the rotation, the Coriolis force can also contribute to the secondary flow.The interaction between rotation, torsion, and curvature complicates the flow characteristics.The effects of rotation and torsion on the flow transitions are studied in details.The results show that there are obvious differences between the flow in rotating ducts and in helical ducts without rotation.Certain hitherto unknown flow patterns are found.The effects of rotation and torsion on the friction factor are also examined.Present results show the characteristics of the fluid flow in rotating helical square ducts.

  8. 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.

  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. Classiifcation of iatrogenic bile duct injur y

    Institute of Scientific and Technical Information of China (English)

    Wan-Yee Lau; Eric C.H. Lai

    2007-01-01

    BACKGROUND: Iatrogenic bile duct injury continues to be an important clinical problem, resulting in serious morbidity, and occasional mortality, to patients. The ease of management, operative risk, and outcome of bile duct injuries vary considerably, and are highly dependent on the type of injury and its location. This article reviews the various classiifcation systems of bile duct injury. DATA SOURCES: A Medline, PubMed database search was performed to identify relevant articles using the keywords"bile duct injury", "cholecystectomy", and “classiifcation”. Additional papers were identiifed by a manual search of the references from the key articles. RESULTS: Traditionally, biliary injuries have been classiifed using the Bismuth's classiifcation. This classiifcation, which originated from the era of open surgery, is intended to help the surgeons to choose the appropriate technique for the repair, and it has a good correlation with the ifnal outcome after surgical repair. However, the Bismuth's classiifcation does not encompass the whole spectrum of injuries that are possible. Bile duct injury during laparoscopic cholecystectomy tends to be more severe than those with open cholecystectomy. Strasberg’s classiifcation made Bismuth’s classiifcation much more comprehensive by including various other types of extrahepatic bile duct injuries. Our group, Bergman et al, Neuhaus et al, Csendes et al, and Stewart et al have also proposed other classiifcation systems to complement the Bismuth's classiifcation. CONCLUSIONS:None of the classiifcation system is universally accepted as each has its own limitation. Hopefully, a universally accepted comprehensive classiifcation system will be published in the near future.

  11. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  12. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Back Learn about acoustic neuroma AN Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords Questions ... kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To ...

  13. Study of acoustic resonance of cascades

    Science.gov (United States)

    Honjo, M.; Tominaga, T.

    Discrete sounds and vibrations from guide vanes due to acoustic resonance in the vane flow path, are experimentally investigated. Other causes of pure sounds in stationary vanes are considered, such as direct radiation from wake shedding vortices, bubble vortices or leading edges, and radial or axial modes of air columns. Two-dimensional cascade tests are performed under various conditions, and the data are compared with theoretical results of flat plate cascades. Three-dimensional ducted guide vane model tests are carried out to apply prototype guide vanes, and to confirm the resonance of the two-dimensional tests. Results show that frequency is more sensitive to chord length than pitch length, and the ratio of the fluctuation frequency to fluid sound velocity/pitch length is independent of the scale. Bubble vortices on concave surfaces or leading edges are not exciting sources; and under the limit of solidity, no exciting energy can generate acoustic resonance in correspondence to the mode.

  14. Flow Investigation inside A Curved Square Duct

    Directory of Open Access Journals (Sweden)

    Dipyaman Gangopadhyay

    2017-05-01

    Full Text Available This paper presents the results of an experimental work with measurement of wall static pressure of 90°C shaped Curved duct. The test duct is made up of transparent perspex sheets to facilitate the flow visualization study. The duct has an inlet to exit area ratio of 1.0 with centerline distance of 750 mm. The inlet aspect ratio of the test duct has been fixed at 1.0. The velocities for the proposed investigations are to be measured by using a Pitot tube.Wall pressures are measured with the help of an inclinedmanometer with the inclination of 35°. The manometer had two tubes emanating from it: one left open to the atmosphere and the other connected to the steel pipes attached to the four walls of the curved duct. The difference in the readings helped us calculate the static pressure and thereby the normalized pressure. Wall pressure distribution along the curved and parallel walls of the duct at 0°, 22.5°, 45°, 67.5° and 90° measuring sections was measured. All the experimental data has been processed by an Intel i3 CPU, 3 GB RAM PC and analyzed to give the distribution of static pressure in the square duct.The main purpose of this investigation is to show the development of secondary flow which happens when the flow takes place through the bend in the curvature. This secondary flow arises as a result of a centrifugal force acting when the flow moves through the bend. The investigation is carried out at three different velocities 20 m/s, 40 m/s and 60 m/s. The distribution of normalized pressure which is the ratio of static pressure to the dynamic pressure is mapped and shown in the form of contours by using the software package SURFER.The trend of wall static pressure development on the walls of C shaped duct shows that as the flow proceeds towards the curvature, there exists a high pressure gradient between the outside face and inside face due the centrifugal force acting along the curvature. This shows the bulk shifting of flow towards

  15. What Should You Ask Your Doctor about Bile Duct Cancer?

    Science.gov (United States)

    ... support? Along with these sample questions, be sure to write down some of your own. For instance, you ... Diagnosed? How is Bile Duct Cancer Staged? Survival Statistics for Bile Duct Cancers Resectable Versus Unresectable Bile ...

  16. Higher order mode propagation in nonuniform circular ducts

    Science.gov (United States)

    Cho, Y. C.; Ingard, K. U.

    1980-01-01

    This paper presents an analytical investigation of higher order mode propagation in a nonuniform circular duct without mean flow. An approximate wave equation is derived on the assumptions that the duct cross section varies slowly and that mode conversion is negligible. Exact closed form solutions are obtained for a particular class of converging-diverging circular duct which is here referred to as 'circular cosh duct'. Numerical results are presentd in terms of the transmission loss for the various duct shapes and frequencies. The results are applicable to studies of multimodal propagation as well as single mode propagation. The results are also applicable to studies of sound radiation from certain types of contoured inlet ducts, or of sound propagation in a converging-diverging duct of somewhat different shape from a cosh duct.

  17. Is spontaneous closure of a patent arterial duct common?

    Science.gov (United States)

    Hoffman, Julien I E

    2017-01-01

    As closing a patent arterial duct is relatively simple, safe, and successful, most children with a patent arterial duct have it closed soon after diagnosis. The larger ducts are closed to prevent congestive heart failure, pulmonary vascular disease, or aneurysmal dilatation of the ductus, and smaller ducts are closed to prevent infective endocarditis. Consequently, there is no opportunity to determine whether spontaneous closure or diminution in size of the patent arterial duct is common. If the duct does become smaller, flow through it may be so low that no murmur is produced - the silent ductus. The frequency and best management of the silent patent arterial duct are unknown, and we do not know whether these tiny ducts are the last stage before spontaneous closure.

  18. Physics of Acoustic Radiation from Jet Engine Inlets

    Science.gov (United States)

    Tam, Christopher K. W.; Parrish, Sarah A.; Envia, Edmane; Chien, Eugene W.

    2012-01-01

    Numerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics (CAA) algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test (SDT) is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic wave to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of sound waves by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number and duct mode frequency, azimuthal mode number, and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition and in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.

  19. 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 du

  20. 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.

  1. A case of fascioliasis in common bile duct

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Soo Youn; Park, Cheol Min; Chung, Kyu Byung; Lee, Chang Hong; Park, Seung Chul; Choi, Sang Yong; Lim, Han Jong [Korea University College of Medicine, Seoul (Korea, Republic of)

    1989-10-15

    A case of Fascioliasis of common bile duct is confirmed by visualization of adult fluke. Fascioliasis caused by Fasciola hepatica, is common parasitic disease in cattle and sheep. Human is an accidental host. ERCP demonstrated irregular linear conglomerated filling defects in common bile duct. Through surgical intervention, we found adult flukes of F. hepatica and adenomatous hyperplasia of common bile duct.

  2. 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.

  3. 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, "Twister." She finds…

  4. IDUS for Biliary and Pancreatic Duct Lesions

    Institute of Scientific and Technical Information of China (English)

    Takao ltoi

    2008-01-01

    @@ In the recent decade, wire-guided intraductal US(IDUS), which can be passed through the working channel of standard duodenoscopes to provide high-frequency ultrasound images, has been developed as a newly diagnostic tool for biliary and pancreatic duct lesions.

  5. Calcium influx pathways in rat pancreatic ducts

    DEFF Research Database (Denmark)

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

    1996-01-01

    A number of agonists increase intracellular Ca2+ activity, [Ca2+]i, in pancreatic ducts, but the influx/efflux pathways and intracellular Ca2+ stores in this epithelium are unknown. The aim of the present study was to characterise the Ca2+ influx pathways, especially their pH sensitivity, in nati...

  6. Laser Beam Duct Pressure Controller System.

    Science.gov (United States)

    the axial flow of a conditioning gas within the laser beam duct, by matching the time rate of change of the pressure of the flowing conditioning gas...to the time rate of change of the pressure in the cavity of an operably associated laser beam turret.

  7. Familial occurrence of congenital bile duct dilatation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Congenital bile duct dilatation (CBD) that developed in a parent and son is presented.Familial occurrence of CBD is rare,with only a few male cases having been reported.Since the initial report of CBD occurring in siblings in 1981,a total of 20 cases (10 pairs) have been published as of 2007.Clinical and genetic features of CBD are discussed.

  8. Heat Transfer in a Superelliptic Transition Duct

    Science.gov (United States)

    Poinsatte, Philip; Thurman, Douglas; Hippensteele, Steven

    2008-01-01

    Local heat transfer measurements were experimentally mapped using a transient liquid-crystal heat transfer technique on the surface of a circular-to-rectangular transition duct. The transition duct had a length-to-diameter ratio of 1.5 and an exit-plane aspect ratio of 3. The crosssectional geometry was defined by the equation of a superellipse. The cross-sectional area was the same at the inlet and exit but varied up to 15 percent higher through the transition. The duct was preheated to a uniform temperature (nominally 64 C) before allowing room temperature air to be suddenly drawn through it. As the surface cooled, the resulting isothermal contours on the duct surface were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the surface temperature and time data for all points on the duct surfaces during each test. Using this surface temperature-time data together with the temperature of the air flowing through the model and the initial temperature of the model wall, the heat transfer coefficient was calculated by employing the classic one-dimensional, semi-infinite wall heat transfer conduction model. Test results are reported for inlet diameter-based Reynolds numbers ranging from 0.4x106 to 2.4x106 and two grid-generated freestream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 16 percent, which may be more typical of real engine conditions.

  9. The effect of duct surface character on methane explosion propagation

    Institute of Scientific and Technical Information of China (English)

    LIN Bai-quan; YE Qing; JIAN Cong-guang; WU Hai-jin

    2007-01-01

    The effect of duct surface character on methane explosion propagation was experimentally studied and theoretically analyzed. The roughness has effect on methane explosion propagation. The flame propagation velocity and the peak value pressure of methane explosion in rough duct are larger than the parameters in smooth duct. The heat exchange of the surface has effect on methane explosion propagation. The propagation velocity of flame and strength of explosion wave in the duct covered by heat insulation material are larger than those in duct with good heat transmittability.

  10. Magnetic resonance imaging of extrahepatic bile duct disruption

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Yon-Cheong; Wang, Li-Jen; Chen, Chi-Jen [Department of Radiology, Chang Gung Memorial Hospital, 5, Fu-Hsing Street, Gueishan, 33333 Taoyuan (Taiwan); Chen, Ray-Jade [Division of Trauma and Emergency Surgery, Chang Gung Memorial Hospital, 5, Fu-Hsing Street, Gueishan, 33333 Taoyuan (Taiwan)

    2002-10-01

    Blunt injury of the extrahepatic bile duct is rare and hence a large series of scientific study of its MRI is difficult to perform. We present the MRI and MR cholangiography of a case of blunt extrahepatic bile duct injury proven at surgery. The diagnosis could be established based on MRI findings of an abrupt tapering of the extrahepatic bile duct with a retracted end, a discordant small-caliber proximal duct, massive ascites, and a hematoma in proximity to the bile duct injury. This non-invasive MRI study is a promising imaging modality to evaluate biliary tract injury. (orig.)

  11. 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.

  12. Transition duct with divided upstream and downstream portions

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, Kevin Weston; LeBegue, Jeffrey Scott; Maldonado, Jaime Javier; Dillard, Daniel Jackson; Flanagan, James Scott

    2015-07-14

    Turbine systems are provided. In one embodiment, a turbine system includes a transition duct comprising an inlet, an outlet, and a duct 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 duct passage includes an upstream portion extending from the inlet and a downstream portion extending from the outlet. The turbine system further includes a rib extending from an outer surface of the duct passage, the rib dividing the upstream portion and the downstream portion.

  13. The Influence of Stoichiometry and Flame-Holder Shape on Flame Dynamics and Acoustics (Preprint)

    Science.gov (United States)

    2012-04-01

    2915- 2923. Ingard , U., and Singhal, V., 1973, “Upstream and Downstream Sound Radiation into a Moving Flow,” Journal of the Acoustical Society of...America 45(4), 1343-1346. Ingard , U., and Singhal, V., 1973, “Emissions of Higher-Order Acoustic Modes into a Moving Fluid in a Duct,” Journal of the...Dynamics of Bluff Body Stabilized Premixed Reacting Flows,” AIAA Paper 2003-0835. Morse P., and Ingard , U., 1968, Theoretical Acoustics, McGraw Hill, NY

  14. Repetitively pulsed electric laser acoustic studies. Volume 1. Final technical report, Jun 80-Jun 83

    Energy Technology Data Exchange (ETDEWEB)

    Ingard, K.U.; McMillan, C.F.

    1983-09-01

    This report summarizes a study of the acoustical characteristics of a closed loop duct system for pulsed lasers with emphasis on acoustic suppression technology. Several topics are considered involving wave propagation reflection and attenuation in a shock tube, in which pulse waves are generated, simulating those in a pulsed laser system. A detailed analysis of the design of parallel-baffle attenuators for suppression of acoustic waves is given, allowing for the contributions of the reflection transmitted and reverberant contributions to the sound pressure field in the optical cavity.

  15. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  16. Acoustic cryocooler

    Science.gov (United States)

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  17. Acoustic transducer

    Science.gov (United States)

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  18. Acoustic telemetry.

    Energy Technology Data Exchange (ETDEWEB)

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  19. A displacement-pressure finite element formulation for analyzing the sound transmission in ducted shear flows with finite poroelastic lining.

    Science.gov (United States)

    Nennig, Benoit; Tahar, Mabrouk Ben; Perrey-Debain, Emmanuel

    2011-07-01

    In the present work, the propagation of sound in a lined duct containing sheared mean flow is studied. Walls of the duct are acoustically treated with absorbent poroelastic foams. The propagation of elasto-acoustic waves in the liner is described by Biot's model. In the fluid domain, the propagation of sound in a sheared mean flow is governed by the Galbrun's equation. The problem is solved using a mixed displacement-pressure finite element formulation in both domains. A 3D implementation of the model has been performed and is illustrated on axisymmetric examples. Convergence and accuracy of the numerical model are shown for the particular case of the modal propagation in a infinite duct containing a uniform flow. Practical examples concerning the sound attenuation through dissipative silencers are discussed. In particular, effects of the refraction effects in the shear layer as well as the mounting conditions of the foam on the transmission loss are shown. The presence of a perforate screen at the air-porous interface is also considered and included in the model.

  20. 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.

  1. Rationale for Measuring Duct Leakage Flows in Large Commercial Buildings

    Energy Technology Data Exchange (ETDEWEB)

    Wray, Craig P.; Diamond, Richard C.; Sherman, Max H.

    2005-07-01

    Industry-wide methods of assessing duct leakage are based on duct pressurization tests, and focus on ''high pressure'' ducts. Even though ''low pressure'' ducts can be a large fraction of the system and tend to be leaky, few guidelines or construction specifications require testing these ducts. We report here on the measured leakage flows from ten large commercial duct systems at operating conditions: three had low leakage (less than 5% of duct inlet flow), and seven had substantial leakage (9 to 26%). By comparing these flows with leakage flows estimated using the industry method, we show that the latter method by itself is not a reliable indicator of whole-system leakage flow, and that leakage flows need to be measured.

  2. The Acoustic Performance of Plane Laggings and Similar Multi-Layer Acoustic Structures.

    Science.gov (United States)

    Au, Chak Kuen

    Acoustic laggings are used to inhibit the transmission of the sound radiated from the vibrating surfaces of machines, ducts, pipes, etc. They are formed of layers of porous materials such as fibreglass or mineral wool, layers of impervious materials such as metal cladding sheets and sometimes airspaces. A novel procedure for estimating the diffuse field 1/3 octave band insertion loss which a plane acoustic lagging produces when applied to a plane structure is developed. This novel procedure, which constitutes the major contribution of the work described in the thesis to new knowledge, is based on sets of formulae which describe how obliquely incident plane sound waves interact with the different basic layers, such as the porous layers and the impervious layers which form the lagging. The validity of the procedure is demonstrated by comparing the results it produces with measured results. The procedure is then used to undertake a parametric study to assess the effect of the properties of the various types of layers. Often the cladding sheet of a lagging is fastened to the base structure which is being lagged and an approximate analysis to consider the effect of such fastening is presented. The influence of corrugated cladding sheets is also considered. The principles used to predict the performance of plane acoustic laggings can be adapted to predict other acoustic properties such as the acoustic absorption of plane acoustic structures and this is done in the final part of the thesis. A comparison is made between the predicted and the measured performances of various types of acoustic structures.

  3. 3D Acoustic Modelling of Dissipative Silencers with Nonhomogeneous Properties and Mean Flow

    Directory of Open Access Journals (Sweden)

    E. M. Sánchez-Orgaz

    2014-07-01

    Full Text Available A finite element approach is proposed for the acoustic analysis of automotive silencers including a perforated duct with uniform axial mean flow and an outer chamber with heterogeneous absorbent material. This material can be characterized by means of its equivalent acoustic properties, considered coordinate-dependent via the introduction of a heterogeneous bulk density, and the corresponding material airflow resistivity variations. An approach has been implemented to solve the pressure wave equation for a nonmoving heterogeneous medium, associated with the problem of sound propagation in the outer chamber. On the other hand, the governing equation in the central duct has been solved in terms of the acoustic velocity potential considering the presence of a moving medium. The coupling between both regions and the corresponding acoustic fields has been carried out by means of a perforated duct and its acoustic impedance, adapted here to include absorbent material heterogeneities and mean flow effects simultaneously. It has been found that bulk density heterogeneities have a considerable influence on the silencer transmission loss.

  4. Performing Active Noise Control and Acoustic Experiments Remotely

    Directory of Open Access Journals (Sweden)

    Imran Khan

    2012-12-01

    Full Text Available This paper presents a novel and advanced remotely controlled laboratory for conducting Active Noise Control (ANC, acoustic and Digital Signal Processing (DSP experiments. The laboratory facility, recently developed by Blekinge Institute of Technology (BTH Sweden, supports remote learning through internet covering beginners level such as simple experimental measurements to advanced users and even researchers such as algorithm development and their performance evaluation on DSP. The required software development for ANC algorithms and equipment control are carried out anywhere in the world remotely from an internet-connected client PC using a standard web browser. The paper describes in detail how ANC, acoustic and DSP experiments can be performed remotely The necessary steps involved in an ANC experiment such as validity of ANC, forward path estimation and active control applied to a broad band random noise [0-200Hz] in a ventilation duct will be described in detail. The limitations and challenges such as the forward path and nonlinearities pertinent to the remote laboratory setup will be described for the guidance of the user. Based on the acoustic properties of the ventilation duct some of the possible acoustic experiments such as mode shapes analysis and standing waves analysis etc. will also be discussed in the paper.

  5. Theoretical analysis of HVAC duct hanger systems

    Science.gov (United States)

    Miller, R. D.

    1987-01-01

    Several methods are presented which, together, may be used in the analysis of duct hanger systems over a wide range of frequencies. The finite element method (FEM) and component mode synthesis (CMS) method are used for low- to mid-frequency range computations and have been shown to yield reasonably close results. The statistical energy analysis (SEA) method yields predictions which agree with the CMS results for the 800 to 1000 Hz range provided that a sufficient number of modes participate. The CMS approach has been shown to yield valuable insight into the mid-frequency range of the analysis. It has been demonstrated that it is possible to conduct an analysis of a duct/hanger system in a cost-effective way for a wide frequency range, using several methods which overlap for several frequency bands.

  6. Extrahepatic bile duct neurilemmoma mimicking Klatskin tumor.

    Science.gov (United States)

    Kamani, Fereshteh; Dorudinia, Atosa; Goravanchi, Farhood; Rahimi, Farzaneh

    2007-04-01

    Neurilemmoma rarely develops in the biliary tree. Here, we report a 39-year-old Iranian woman with neurilemmoma in the extrahepatic bile duct presenting with progressively deepening jaundice. On the basis of clinical and radiological features, this tumor was initially suspected as Klatskin tumor. Histologically, the tumor was a typical neurilemmoma. Immunostaining showed that tumor cells were strongly and diffusely positive for S-100 protein, which supported the diagnosis of neurilemmoma. Neurilemmoma should be considered in the differential diagnosis of obstructive jaundice.

  7. Right anterior segmental hepatic duct emptying directly into the cystic duct in a living donor.

    Science.gov (United States)

    Ishiguro, Yasunao; Hyodo, Masanobu; Fujiwara, Takehito; Sakuma, Yasunaru; Hojo, Nobuyuki; Mizuta, Koichi; Kawarasaki, Hideo; Lefor, Alan T; Yasuda, Yoshikazu

    2010-08-07

    A 35-year-old mother was scheduled to be the living donor for liver transplantation to her second son, who suffered from biliary atresia complicated with biliary cirrhosis at the age of 2 years. The operative plan was to recover the left lateral segment of the mother's liver for living donor transplantation. With the use of cholangiography at the time of surgery, we found the right anterior segmental duct (RASD) emptying directly into the cystic duct, and the catheter passed into the RASD. After repairing the incision in the cystic duct, transplantation was successfully performed. Her postoperative course was uneventful. Biliary anatomical variations were frequently encountered, however, this variation has very rarely been reported. If the RASD was divided, the repair would be very difficult because the duct will not dilate sufficiently in an otherwise healthy donor. Meticulous preoperative evaluation of the living donor's biliary anatomy, especially using magnetic resonance cholangiography and careful intraoperative techniques, is important to prevent bile duct injury and avoid the risk to the healthy donor.

  8. Endoscopic management of bile duct stones.

    Science.gov (United States)

    Sivak, M V

    1989-09-01

    Endoscopic sphincterotomy is the procedure of choice for choledocholithiasis in patients who have had a cholecystectomy. The bile duct is cleared of stones in about 80 to 90 percent of patients. Available data, largely retrospective, suggest that surgery and endoscopic sphincterotomy are about equal with respect to removal of stones, morbidity, and mortality. Certain technical problems are discussed, including inability to insert the papillotome, the large stone, and problems relating to anatomy such as peripapillary diverticulum and prior gastrectomy. The treatment of patients with bile duct stones who have not had a cholecystectomy, with and without cholelithiasis, is controversial. Endoscopic sphincterotomy without subsequent cholecystectomy is adequate treatment for the majority of patients who are unfit for surgery, even if there are stones in the gallbladder, provided they are asymptomatic after endoscopic removal of stones from the bile ducts. Endoscopic sphincterotomy has been performed in the treatment of gallstone-induced pancreatitis, acute obstructive cholangitis, and sump syndrome. The complication rate for endoscopic sphincterotomy ranges from 6.5 to 8.7 percent, with a mortality rate of 0 to 1.3 percent. The most common serious complications are perforation, hemorrhage, acute pancreatitis, and sepsis.

  9. Endoscopic Management of Difficult Bile Duct Stones

    Directory of Open Access Journals (Sweden)

    Christian Ell

    1992-01-01

    Full Text Available More than 90% of all common bile duct concrements can be removed via the endoscopic retrograde route via endoscopic sphincterotomy, stone extraction by baskets and balloon catheters, or mechanical lithotripsy. Oversized, very hard or impacted stones, however, often still resist conventional endoscopic therapy. Promising new or improved approaches for the treatment of these stones are intracorporeal or extracorporeal shock wave lithotripsy. Shockwave lithotriptors for extracorporeal shockwave lithotripsy are currently available worldwide. However, for the waterbath first generation devices, general anesthesia is required since shockwaves are very painful. Furthermore, an x-ray localization system is essential to visualize the stones after having filled the bile duct over a nasobiliary catheter. An average of two shockwave treatments with additional two to four endoscopic sessions are required. ln tracorporeal lithotripsy promises more comfort and less effort for the patient. Shockwaves are generated either by means of the spark gap principle (electrohydraulic probes or by laser-induced plasma generation. Laser-induced shockwave lithotripsy appears to be more safer, since with dye and solid state lasers, athermal, well-controlled shockwaves can be generateJ without the risks for duct perfo ration (as described for the electrohydraulic system. Furthermore, a recently developed stone-tissue detection system integrated in a new dye laser system enchances the safety of laser-induced lithotripsy. ln consequence, lithotripsy without direct endoscopic control appears possible in selected cases.

  10. Particle deposition in industrial duct bends.

    Science.gov (United States)

    Peters, Thomas M; Leith, David

    2004-07-01

    A study of particle deposition in industrial duct bends is presented. Particle deposition by size was measured by comparing particle size distributions upstream and downstream of bends that had geometries and flow conditions similar to those used in industrial ventilation. As the interior surface of the duct bend was greased to prevent particle bounce, the results are applicable to liquid drops and solid particles where duct walls are sticky. Factors investigated were: (i) flow Reynolds number (Re = 203 000, 36 000); (ii) particle Reynolds number (10 vertical); and (vii) construction technique (smooth, gored, segmented). Measured deposition was compared with models developed for bends in small diameter sampling lines (Re 20 microm, deposition was slightly greater in the horizontal-to-horizontal orientation than in the horizontal-to-vertical orientation due to gravitational settling. Penetration was not a multiplicative function of bend angle as theory predicts, due to the developing nature of turbulent flow in bends. Deposition in a smooth bend was similar to that in a gored bend; however, a tight radius segmented bend (R0 = 1.7) exhibited much lower deposition. For more gradual bends (3 < R0 < 12), curvature ratio had negligible effect on deposition.

  11. MRI of the biliary and pancreatic ducts

    Energy Technology Data Exchange (ETDEWEB)

    Pavone, P.; Laghi, A.; Catalano, C.; Panebianco, V.; Fabiano, S.; Passariello, R. [Dept. of Radiology II, Univ. of Rome ``La Sapienza`` (Italy)

    1999-10-01

    Magnetic resonance Cholangiopancreatography (MRCP) is a non-invasive imaging technique able to provide projectional images of the bile ducts. Different sequences, using both breath-hold and non-breath-hold acquisition techniques, have been employed in order to obtain MRCP images. The authors discuss technical aspects, considering both three-dimensional non-breath-hold techniques and two-dimensional breath-hold, multi-slice and thick slab sequences. Clinical applications of MRCP are evaluated, presenting data from both the literature and personal experience. The main indication for MRCP study is represented by the evaluation of common bile duct obstruction, with the aim of assessing the presence of the obstruction (accuracy 85-100 %) and, subsequently, its level (accuracy 91-100 %) and its cause. The utility of associating conventional MR images to MRCP in malignant strictures, in order to characterize and stage the malignant lesion, is also discussed. Finally, data are presented regarding the indications and the utility of MR-pancreatography in the evaluation of patients with pancreatic duct anomalies and chronic pancreatitis. (orig.) With 9 figs., 39 refs.

  12. Springer Handbook of Acoustics

    CERN Document Server

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  13. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  14. 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.

  15. Acoustic Spatiality

    Directory of Open Access Journals (Sweden)

    Brandon LaBelle

    2012-06-01

    Full Text Available Experiences of listening can be appreciated as intensely relational, bringing us into contact with surrounding events, bodies and things. Given that sound propagates and expands outwardly, as a set of oscillations from a particular source, listening carries with it a sensual intensity, whereby auditory phenomena deliver intrusive and disruptive as well as soothing and assuring experiences. The physicality characteristic of sound suggests a deeply impressionistic, locational "knowledge structure" – that is, the ways in which listening affords processes of exchange, of being in the world, and from which we extend ourselves. Sound, as physical energy reflecting and absorbing into the materiality around us, and even one's self, provides a rich platform for understanding place and emplacement. Sound is always already a trace of location.Such features of auditory experience give suggestion for what I may call an acoustical paradigm – how sound sets in motion not only the material world but also the flows of the imagination, lending to forces of signification and social structure, and figuring us in relation to each other. The relationality of sound brings us into a steady web of interferences, each of which announces the promise or problematic of being somewhere.

  16. Acoustic Neurinomas

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  17. Acoustic Neurinomas

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  18. 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.)

  19. A viable method to predict acoustic streaming in presence of cavitation.

    Science.gov (United States)

    Louisnard, O

    2017-03-01

    The steady liquid flow observed under ultrasonic emitters generating acoustic cavitation can be successfully predicted by a standard turbulent flow calculation. The flow is driven by the classical averaged volumetric force density calculated from the acoustic field, but the inertial term in Navier-Stokes equations must be kept, and a turbulent solution must be sought. The acoustic field must be computed with a realistic model, properly accounting for dissipation by the cavitation bubbles [Louisnard, Ultrason. Sonochem., 19, (2012) 56-65]. Comparison with 20kHz experiments, involving the combination of acoustic streaming and a perpendicular forced flow in a duct, shows reasonably good agreement. Moreover, the persistence of the cavitation effects on the wall facing the emitter, in spite of the deflection of the streaming jet, is correctly reproduced by the model. It is also shown that predictions based either on linear acoustics with the correct turbulent solution, or with Louisnard's model with Eckart-Nyborg's theory yields unrealistic results.

  20. Acoustic source for generating an acoustic beam

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  1. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    Science.gov (United States)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  2. Aberrant bile ducts, 'remnant surface bile ducts,' and peribiliary glands: descriptive anatomy, historical nomenclature, and surgical implications.

    Science.gov (United States)

    El Gharbawy, Ramadan M; Skandalakis, Lee J; Heffron, Thomas G; Skandalakis, John E

    2011-05-01

    The term "aberrant bile ducts" has been used to designate three heterogeneous groups of biliary structures: (1) bile ducts degenerating or disappearing (unknown etiology, diverse locations); (2) curious biliary structures in the transverse fissure; and (3) aberrant right bile ducts draining directly into the common hepatic duct. We report our observations on these three groups. Twenty-nine fresh human livers of stillborns and adults were injected differentially with colored latex and dissected. Adult livers showed portal venous and hepatic arterial branches, and bile ducts not associated with parenchyma, subjacent to and firmly adherent with the liver capsule: elements of ramifications of normal sheaths were present on the liver's surface. These ramifications, having lost parenchyma associated with them, then sequentially lost their portal branches, bile ducts and arterial branches. This process affected the ramifications of the sheaths in the left triangular ligament, adjacent to the inferior vena cava, in the gallbladder bed and anywhere else on the liver's surface and resulted in the presence of bile ducts accompanied by portal venous and/or hepatic arterial branches and not associated with parenchyma for a period of time. This first group represented normal bile ducts that do not meet the criteria of aberration and could be appropriately designated "remnant surface bile ducts." Such changes were not found in the transverse fissures and review of the literature revealed that the curious biliary structures are the microscopic peribiliary glands. The third group met the criteria of aberration and the anatomy of a representative duct is described.

  3. Right anterior segmental hepatic duct emptying directly into the cystic duct in a living donor

    Institute of Scientific and Technical Information of China (English)

    Yasunao; Ishiguro; Masanobu; Hyodo; Takehito; Fujiwara; Yasunaru; Sakuma; Nobuyuki; Hojo; Koichi; Mizuta; Hideo; Kawarasaki; Alan; T; Lefor; Yoshikazu; Yasuda

    2010-01-01

    A 35-year-old mother was scheduled to be the living donor for liver transplantation to her second son,who suffered from biliary atresia complicated with biliary cirrhosis at the age of 2 years.The operative plan was to recover the left lateral segment of the mother's liver for living donor transplantation.With the use of cholangiography at the time of surgery,we found the right anterior segmental duct(RASD) emptying directly into the cystic duct,and the catheter passed into the RASD.After repairing the inci...

  4. A 3D Multiport Scattering Matrix Based-Method for Educing Wall Impedance of Cylindrical Lined Duct Section: Simulation and Error Evaluation

    Directory of Open Access Journals (Sweden)

    Mohamed Taktak

    2009-01-01

    Full Text Available The first step to achieve the development of an original indirect method to educe the wall normalized acoustic impedance of a cylindrical lined duct section which includes frequency and modal content pressure field dependence is introduced. It is based on the minimization of the difference between numerical and experimental acoustic power dissipations deduced from the 3D numerical and experimental scattering matrices of a lined duct element. The work presented in this paper is a step toward conducting experiments with a flow duct facility developed during the European DUCAT program. To validate this eduction technique, a simulation of the experiment is performed for no flow conditions assuming an axi-symmetric wall lined with a locally reacting material whose impedance was measured with the two microphone method (TMM. The simulation conducted for two incident pressure vectors with a Monte Carlo's technique also provides an assessment of the uncertainty in three predominant experimental parameters on the scattering matrix coefficients, the acoustic power dissipation, and the educed impedance whose results will be useful during the experiments being conducted.

  5. Conversion of acoustic energy by lossless liners

    Science.gov (United States)

    Moehring, W.; Eversman, W.

    1982-01-01

    The Blokhintzev acoustic energy equation is applied to a two-dimensional duct containing a uniform flow with a finite length lining. It is shown that the difference of the incident and outgoing acoustic energy differs in general from the energy dissipated in the liner, the difference being related to the displacements at the liner's edges. It is shown that in the case of a locally reacting lossless liner for frequencies below the first cut-off frequency and for low Mach number acoustic energy is generated if the flow and the incident sound wave are in the same direction and is absorbed if these two directions are opposite unless special edge conditions are met. Furthermore it is shown under the same conditions that the ratio of the reflection coefficient at finite flow velocity to the reflection coefficient at vanishing velocity is to first order in Mach number independent of the liner characteristics. A numerical calculation confirms these predictions at least for mass-like linear admittance.

  6. Climate analysis of evaporation ducts in the South China Sea

    OpenAIRE

    McKeon, Brian D.

    2013-01-01

    Approved for public release; distribution is unlimited. Evaporation ducts have important implications for U.S. Naval activities involving electromagnetic propagation. The presence of an evaporation duct can affect naval operations involving communications, surveillance, electronic warfare, and detection of low-flying missiles, surface ships, or submarine periscopes. We conducted a climate scale analysis of evaporation duct heights (EDH) in the northern South China Sea (SCS), including how ...

  7. Omphalomesenteric duct cyst with gastric mocosa: A case report

    OpenAIRE

    2006-01-01

    Persistance of the omphalomesenteric duct may lead to several anomalies including umblical sinus, umblical cyst, MeckeVs diverticulum or patent omphalomesenteric duct fistula. Clinical manifestations of umblical disorders are usually nonspecific; use of cross-sectional imaging can help identify most of these entities because of their typical locations and distributions in continuity with the other organs and guide therapy. A case of omphalomesenteric duct cyst are presented and analysed toget...

  8. Atlantic Herring Acoustic Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...

  9. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... acoustic neuroma resource Click to learn more... LOGIN EVENTS DONATE Home Learn Back Learn about acoustic neuroma ... support group for me? Find a Group Upcoming Events Video Library Photo Gallery One-on-One Support ...

  10. Method for Observing Intravascular BongHan Duct

    CERN Document Server

    Jiang, X; Shin, H; Lee, B; Choi, C; Soh, K; Cheun, B; Baik, K; Soh, K; Jiang, Xiaowen; Kim, Hee-kyeong; Shin, Hak-soo; Lee, Byong-chon; Choi, Chunho; Soh, Kyung-soon; Cheun, Byeung-soo; Baik, Ku-youn; Soh, Kwang-sup

    2002-01-01

    A method for observing intra blood vessel ducts which are threadlike bundle of tubules which form a part of the BongHan duct system. By injecting 10% dextrose solution at a vena femoralis one makes the intravascular BongHan duct thicker and stronger to be easily detectable after incision of vessels. The duct is semi-transparent, soft and elastic, and composed of smaller tubules whose diameters are of 10$\\mu$m order, which is in agreement with BongHan theory.

  11. Biliary stenting for management of common bile duct stones.

    Science.gov (United States)

    Choudhuri, G; Sharma, B C; Saraswat, V A; Agarwal, D K; Baijal, S S

    1998-06-01

    Large and multiple common bile duct stones may defy extraction despite an adequate endoscopic papillotomy. We treated 65 patients with symptomatic bile duct stones with endoscopic stents after failed attempts at stone extraction. Of the 65 patients, bile duct stones were extracted in eight at a second attempt, 29 underwent elective surgery and 28 patients were followed with the stent in situ for 21-52 months (median 42 months). During follow up, two patients had recurrent pain and two required surgery. The remaining 24 patients remained asymptomatic. Biliary stenting is a safe and effective mode of treatment for common bile duct stones in patients who have failed stone extraction after endoscopic papillotomy.

  12. 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.

  13. 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.)

  14. 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.

  15. 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

  16. 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)

  17. Convolution seal for transition duct in turbine system

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook will pr...

  19. Tutorial on architectural acoustics

    Science.gov (United States)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  20. Live 3D image overlay for arterial duct closure with Amplatzer Duct Occluder II additional size.

    Science.gov (United States)

    Goreczny, Sebstian; Morgan, Gareth J; Dryzek, Pawel

    2016-03-01

    Despite several reports describing echocardiography for the guidance of ductal closure, two-dimensional angiography remains the mainstay imaging tool; three-dimensional rotational angiography has the potential to overcome some of the drawbacks of standard angiography, and reconstructed image overlay provides reliable guidance for device placement. We describe arterial duct closure solely from venous approach guided by live three-dimensional image overlay.

  1. 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.

  2. Radiation of sound from unflanged cylindrical ducts

    Science.gov (United States)

    Hartharan, S. L.; Bayliss, A.

    1983-01-01

    Calculations of sound radiated from unflanged cylindrical ducts are presented. The numerical simulation models the problem of an aero-engine inlet. The time dependent linearized Euler equations are solved from a state of rest until a harmonic solution is attained. A fourth order accurate finite difference scheme is used and solutions are obtained from a fully vectorized Cyber-203 computer program. Cases of both plane waves and spin modes are treated. Spin modes model the sound generated by a turbofan engine. Boundary conditions for both plane waves and spin modes are treated. Solutions obtained are compared with experiments conducted at NASA Langley Research Center.

  3. NONLINEAR ELASTICITY OF BLOOD ARTERIAL DUCT

    Institute of Scientific and Technical Information of China (English)

    黄孟才; 顾忠; 沈俊; 唐复勇

    1991-01-01

    The paper deals with nonlinear elasticity of blood arterial duct, in which the artery is modeled to bea locally triclinic, transverse isotropic, incorapressible, axisymmetric and thickwalled tube with large deformations, The nonlinear coustitutive relationship of arterial tissues is based on the theorv of Green and Adkins. A nonlinear strain energy density function is introduced for nonlinear stress-strain relationship of second order, in which the coefficient of each term is expressed by means of a Lame’s constant, The elasticity constants are nqcessary to describe such a uonlinear finite strain etastieity of the second order, These constants are determined by means of the stress-strain increment theory.

  4. Classification and management of bile duct injuries

    OpenAIRE

    2011-01-01

    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...

  5. Indoor acoustic gain design

    Science.gov (United States)

    Concha-Abarca, Justo Andres

    2002-11-01

    The design of sound reinforcement systems includes many variables and usually some of these variables are discussed. There are criteria to optimize the performance of the sound reinforcement systems under indoor conditions. The equivalent acoustic distance, the necessary acoustic gain, and the potential acoustic gain are parameters which must be adjusted with respect to the loudspeaker array, electric power and directionality of loudspeakers, the room acoustics conditions, the distance and distribution of the audience, and the type of the original sources. The design and installation of front of the house and monitoring systems have individual criteria. This article is about this criteria and it proposes general considerations for the indoor acoustic gain design.

  6. Acoustical studies on corrugated tubes

    Science.gov (United States)

    Balaguru, Rajavel

    Corrugated tubes and pipes offer greater global flexibility combined with local rigidity. They are used in numerous engineering applications such as vacuum cleaner hosing, air conditioning systems of aircraft and automobiles, HVAC control systems of heating ducts in buildings, compact heat exchangers, medical equipment and offshore gas and oil transportation flexible riser pipelines. Recently there has been a renewed research interest in analyzing the flow through a corrugated tube to understand the underlying mechanism of so called whistling, although the whistling in such a tube was identified in early twentieth century. The phenomenon of whistling in a corrugated tube is interesting because an airflow through a smooth walled tube of similar dimensions will not generate any whistling tones. Study of whistling in corrugated tubes is important because, it not only causes an undesirable noise problem but also results in flow-acoustic coupling. Such a coupling can cause significant structural vibrations due to flow-acoustic-structure interaction. This interaction would cause flow-induced vibrations that could result in severe damage to mechanical systems having corrugated tubes. In this research work, sound generation (whistling) in corrugated tubes due to airflow is analyzed using experimental as well as Computational Fluid Dynamics-Large Eddy Simulation (CFD-LES) techniques. Sound generation mechanisms resulting in whistling have been investigated. The whistling in terms of frequencies and sound pressure levels for different flow velocities are studied. The analytical and experimental studies are carried out to understand the influence of various parameters of corrugated tubes such as cavity length, cavity width, cavity depth, pitch, Reynolds numbers and number of corrugations. The results indicate that there is a good agreement between theoretically calculated, computationally predicted and experimentally measured whistling frequencies and sound pressure levels

  7. Parametric Room Acoustic Workflows

    DEFF Research Database (Denmark)

    Parigi, Dario; Svidt, Kjeld; Molin, Erik

    2017-01-01

    The paper investigates and assesses different room acoustics software and the opportunities they offer to engage in parametric acoustics workflow and to influence architectural designs. The first step consists in the testing and benchmarking of different tools on the basis of accuracy, speed...... and interoperability with Grasshopper 3d. The focus will be placed to the benchmarking of three different acoustic analysis tools based on raytracing. To compare the accuracy and speed of the acoustic evaluation across different tools, a homogeneous set of acoustic parameters is chosen. The room acoustics parameters...... included in the set are reverberation time (EDT, RT30), clarity (C50), loudness (G), and definition (D50). Scenarios are discussed for determining at different design stages the most suitable acoustic tool. Those scenarios are characterized, by the use of less accurate but fast evaluation tools to be used...

  8. 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...

  9. 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

  10. Diverticular bile duct lesion in chronic active hepatitis

    DEFF Research Database (Denmark)

    Vyberg, M

    1989-01-01

    Liver needle biopsies from patients with non-A, non-B chronic active hepatitis and so-called abnormal bile duct epithelium were studied with a three-dimensional method. Photographs of bile duct structures in serial sections were transferred to acrylic plates. Five bile duct lesions of a not previ......Liver needle biopsies from patients with non-A, non-B chronic active hepatitis and so-called abnormal bile duct epithelium were studied with a three-dimensional method. Photographs of bile duct structures in serial sections were transferred to acrylic plates. Five bile duct lesions...... 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...... infiltrate associated with pronounced periportal piecemeal necrosis. In two cases, a germinal center was adjacent to the epithelium. The pathogenesis of the diverticular bile duct lesion is unknown, but the diverticuli probably represent Hering ducts and groups of periportal liver cells which have escaped...

  11. 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 i...

  12. 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...

  13. Radiopaque intrahepatic duct stones in plain radiograph: case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi Young; Suh, Chang Hae; Park, Chan Sup; Chung, Won Kyun [College of Medicine, Inha University, Seongnam (Korea, Republic of)

    1994-04-15

    We experienced 3 cases of intrahepatic duct stones detected on plain radiographs. The patients had history of multiple episodes of recurrent cholangitis. Radiographic characteristics of these stones included multiple, round or rectangular radiopaque densities surrounded by calcified rim; these densities showed a branching pattern along the intrahepatic ducts.

  14. 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

  15. Hybrid noise control in a duct using a light micro-perforated plate.

    Science.gov (United States)

    Wang, X N; Choy, Y S; Cheng, L

    2012-12-01

    A plate silencer consists of an expansion chamber with two side-branch cavities covered by light but extremely stiff plates. It works effectively with a wide stopband from low-to-medium frequencies only if the plate is extremely stiff, to ensure a strong reflection of acoustic wave to the upstream in the duct. However, a plate with a slightly weak bending stiffness will result in non-uniform transmission loss (TL) spectra with narrowed stopband. In this study, a hybrid silencer is proposed by introducing micro-perforations into the plate to elicit the sound absorption in order to compensate for the deficiency in the passband caused by the insufficient sound reflection in a certain frequency range due to weaker plate stiffness. A theoretical model, capable of dealing with the strong coupling between the vibrating micro-perforated plate and sound fields inside the cavity and the duct, is developed. Through proper balancing between the sound absorption and reflection, the proposed hybrid silencer provides a more flattened and uniform TL and a widened stopband by more than 20% while relaxing the harsh requirement on the bending stiffness of the plate. Theoretical predictions are validated by experimental data, with phenomenon explained through numerical analyses.

  16. Experimental methodology for turbocompressor in-duct noise evaluation based on beamforming wave decomposition

    Science.gov (United States)

    Torregrosa, A. J.; Broatch, A.; Margot, X.; García-Tíscar, J.

    2016-08-01

    An experimental methodology is proposed to assess the noise emission of centrifugal turbocompressors like those of automotive turbochargers. A step-by-step procedure is detailed, starting from the theoretical considerations of sound measurement in flow ducts and examining specific experimental setup guidelines and signal processing routines. Special care is taken regarding some limiting factors that adversely affect the measuring of sound intensity in ducts, namely calibration, sensor placement and frequency ranges and restrictions. In order to provide illustrative examples of the proposed techniques and results, the methodology has been applied to the acoustic evaluation of a small automotive turbocharger in a flow bench. Samples of raw pressure spectra, decomposed pressure waves, calibration results, accurate surge characterization and final compressor noise maps and estimated spectrograms are provided. The analysis of selected frequency bands successfully shows how different, known noise phenomena of particular interest such as mid-frequency "whoosh noise" and low-frequency surge onset are correlated with operating conditions of the turbocharger. Comparison against external inlet orifice intensity measurements shows good correlation and improvement with respect to alternative wave decomposition techniques.

  17. Heat Transfer in Conical Corner and Short Superelliptical Transition Ducts

    Science.gov (United States)

    Poinsatte, Philip; Thurman, Douglas; Hippensteele, Steven

    2008-01-01

    Local surface heat transfer measurements were experimentally mapped using a transient liquid-crystal heat-transfer technique on the surface of two circular-to-rectangular transition ducts. One has a transition cross section defined by conical corners (Duct 1) and the other by an elliptical equation with changing coefficients (Duct 2). Duct 1 has a length-to-diameter ratio of 0.75 and an exit plane aspect ratio of 1.5. Duct 2 has a length-to-diameter ratio of 1.0 and an exit plane aspect ratio of 2.9. Test results are reported for various inlet-diameter-based Reynolds numbers ranging from 0.45 106 to 2.39 106 and two freestream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 16 percent, which may be more typical of real engine conditions.

  18. Hepatobiliary Scan in Infantile Spontaneous Perforation of Common Bile Duct

    Energy Technology Data Exchange (ETDEWEB)

    Zeon, Seok Kil; Ryu, Jong Gul; Lee, Eun Young [Keimyung University School of Medicine, Taegu (Korea, Republic of); Lee, Jong Gil [Taegu Fatima Hospital, Taegu (Korea, Republic of)

    1996-03-15

    Spontaneous perforation of CBD in infant is a rare but fatal disease. We report a case of bile leakage from common bile duct in 11 months old girl with progressive abdominal distension and vomiting, preoperatively diagnosed by hepatobiliary scan with Tc-99m-DISIDA, which was confirmed by surgery. Operative cholangiogram showed a small perforation at the confluence of cystic duct and common bile duct with mild fusiform dilatation, and no definite abnormality in confluence of the common bile duct and pancreatic duct. Simple drainage of the free peritoneal bilous fluid and T-tube drainage were performed without any evidence of the complication. Patient was inevitable for 6 months OPD follow-up examination.

  19. Extravasation Mucocele Arising from a Lingual Thyroglossal Duct Remnant

    Directory of Open Access Journals (Sweden)

    Mitsuhiko Nakahira

    2015-01-01

    Full Text Available Although a thyroglossal duct cyst is a congenital anomaly, it can also appear in adults. Despite the presence of embryological remnants, it is still unclear why the cyst should suddenly develop later in life. We report a case of a 46-year-old male with an extravasation mucocele arising from a long-standing lingual thyroglossal duct remnant. MRI demonstrated a lingual cystic lesion near the hyoid bone associated with a suprahyoid tract-like structure masquerading as a thyroglossal duct cyst. However, histopathological examination demonstrated a mucocele secondary to a rupture of a thyroglossal duct remnant with numerous intramural heterotopic salivary glands. We propose a new mechanism of an acquired cystic formation of this congenital disease that excessive production of mucus from heterotopic salivary glands and a physical trauma such as swallowing may lead to extravasation of mucus from the thyroglossal duct.

  20. Main-duct intraductal papillary mucinous adenoma of the pancreas

    Directory of Open Access Journals (Sweden)

    Takuma Kensuke

    2011-11-01

    Full Text Available Abstract Background The prevalence of carcinoma in main-duct intraductal papillary mucinous neoplasm (IPMN is high, and surgical resection is recommended for all patients with a main-duct IPMN. Results A main-duct IPMN with typical imagings including protruding lesions in the dilated main pancreatic duct was resected, but the histology was intraductal papillary mucinous adenoma of the pancreas. Discussion It has been reported that the presence of mural nodules and dilatation of MPD are significantly higher in malignant IPMNs. The presented case had protruding lesions in the dilated main pancreatic duct on endoscopic ultrasonography, but the histology was adenoma. Conclusion Preoperative distinction between benign and malignant IPMNs is difficult.

  1. 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.)

  2. Bile duct emptying in response to fat: a validation study.

    Science.gov (United States)

    Hunt, D R; Scott, A J

    1990-11-01

    Fatty meal sonography has been suggested to assess patients with biliary pain after cholecystectomy, but the effects of gallbladder removal on biliary dynamics has not been studied prospectively. Before elective cholecystectomy, 25 patients had their common hepatic ducts' diameter measured by ultrasonography before and after a fat stimulus. In 23, tests were repeated 1 month, 1 year, and 5 years after surgery. In preoperative studies, 5 patients showed dilatation after fat and 2 of these had stones in the common bile duct. However, another 4 patients with stones or sludge in the duct did not show dilatation, so that the response to fat was a poor indicator of patients requiring common bile duct exploration. No patient had major symptoms after surgery. At 1 month and 12 months, the response to fat was variable with more than half of those tested showing no decrease in duct size. A more consistent pattern emerged at 5 years, when 14 of 18 patients tested showed a decrease in common hepatic duct after fat; 3 were unchanged and 1 increased by 1 mm. The response to fat was less consistent and more difficult to measure in the common bile duct, even 5 years after operation. It was concluded that not all patients with indications for exploration of the common bile duct on operative cholangiography show a dilatation response to fat on preoperative testing. Also, fatty meal sonography should be used with caution because the response to fat in asymptomatic patients soon after operation is unpredictable, with occasional patients showing dilation without apparent obstruction. Measurement of common hepatic duct is preferred to common bile duct and increases in diameter of 1 mm are probably not significant.

  3. Lacrimal Duct Occlusion Is Associated with Infectious Keratitis

    Science.gov (United States)

    Li, Guigang; Guo, Jingmin; Liu, Rong; Hu, Weikun; Xu, Lingjuan; Wang, Juan; Cai, Subo; Zhang, Hong; Zhu, Yingting

    2016-01-01

    Background: To explore the prevalence of lacrimal duct obstruction in patients with infectious keratitis, and the necessity of lacrimal duct dredge in the treatment of human infectious keratitis. Methodology/Principle Findings: The design is prospective, non-control case series. Thirty-one eyes from twenty-eight continuous patients with infectious keratitis were included in this study. The presence/absence of lacrimal duct obstruction was determined by the lacrimal duct irrigation test. The diagnosis of infectious keratitis was made based on clinical manifestations, cornea scraping microscopic examination and bacterial/fungus culture. Diagnosis of viral keratitis was set up based on the recurrent history, deep neovascularization and typical outlook of the cornea scar. The treatment of keratitis included drugs, eye drops or surgery, while treatment of chronic dacryocystitis was lacrimal duct dredging with supporting tube implantation surgery. In the thirty-one eyes with infectious keratitis, fifteen suffered from fungal keratitis (48%), two bacterial keratitis (6%), and fourteen viral keratitis (45%). Eleven eyes (35%) from ten patients with infectious keratitis also suffered from lacrimal duct obstruction. In those cases, six eyes also suffered from lower canalicular obstruction, three nasolacrimal duct obstruction and chronic dacryocystitis, one a combination of upper and lower canalicular obstruction, one upper canalicular obstruction. After local and systemic applications of anti-bacterial, anti-viral, anti-fungal and anti-inflammatory drugs, twenty-eight eyes (90%) recovered within three weeks, while the ulceration of three patients required the lacrimal duct dredging and supporting tube implantation surgery for the healing. Conclusions: Herein, we first report that the prevalence of infectious keratitis is closely correlated to the occurrence of lacrimal duct obstruction. When both confirmed, simultaneous treatment of keratitis and lacrimal duct obstruction

  4. 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.

  5. A Plug-and-Play Duct System Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    R. Beach, B. Dickson, A. Grisolia, A. Poerschke, A. Rapport

    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.

  6. Computation of unsteady transonic flows through rotating and stationary cascades. 3: Acoustic far-field analysis

    Science.gov (United States)

    Slutsky, S.; Fischer, D.; Erdos, J. I.

    1977-01-01

    A small perturbation type analysis has been developed for the acoustic far field in an infinite duct extending upstream and downstream of an axial turbomachinery stage. The analysis is designed to interface with a numerical solution of the near field of the blade rows and, thereby, to provide the necessary closure condition to complete the statement of infinite duct boundary conditions for the subject problem. The present analysis differs from conventional inlet duct analyses in that a simple harmonic time dependence was not assumed, since a transient signal is generated by the numerical near-field solution and periodicity is attained only asymptotically. A description of the computer code developed to carry out the necessary convolutions numerically is included, as well as the results of a sample application using an impulsively initiated harmonic signal.

  7. Altered collecting duct adenylyl cyclase content in collecting duct endothelin-1 knockout mice

    Directory of Open Access Journals (Sweden)

    Kohan Donald E

    2007-05-01

    Full Text Available Abstract Background Endothelin-1 (ET-1 inhibition of vasopressin (AVP-stimulated water reabsorption by the inner medullary collecting duct (IMCD is associated with reduced cAMP accumulation. To determine the effect of ET-1 deficiency, AVP-stimulated cAMP responsiveness was assessed in IMCD from mice with collecting duct-specific deletion of ET-1 (CD ET-1 KO and from control animals. Methods Cyclic AMP production, adenylyl cyclase (AC mRNA, and AC protein were measured in acutely isolated IMCD. Results CD ET-1 KO IMCD had enhanced AVP-stimulated cAMP accumulation. Inhibition of calcium-stimulated AC using BAPTA did not prevent enhanced AVP responsiveness in CD ET-1 KO IMCD. Factors known to be modified by ET-1, including nitric oxide, cyclooxygenase metabolites, and superoxide did not affect the increased AVP responsiveness of CD ET-1 KO IMCD. Differential V2 receptor or G-protein activity was not involved since CD ET-1 KO IMCD had increased cAMP accumulation in response to forskolin and/or cholera toxin. CD ET-1 KO did not affect mRNA or protein levels of AC3, one of the major known collecting duct AC isoforms. However, the other known major collecting duct AC isoform (AC5/6 did have increased protein levels in CD ET-1 KO IMCD, although AC5 (weak signal and 6 mRNA levels were unchanged. Conclusion ET-1 deficiency increases IMCD AC5/6 content, an effect that may synergize with acute ET-1 inhibition of AVP-stimulated cAMP accumulation.

  8. Low-dispersion finite difference methods for acoustic waves in a pipe

    Science.gov (United States)

    Davis, Sanford

    1991-01-01

    A new algorithm for computing one-dimensional acoustic waves in a pipe is demonstrated by solving the acoustic equations as an initial-boundary-value problem. Conventional dissipation-free second-order finite difference methods suffer severe phase distortion for grids with less that about ten mesh points per wavelength. Using the signal generation by a piston in a duct as an example, transient acoustic computations are presented using a new compact three-point algorithm which allows about 60 percent fewer mesh points per wavelength. Both pulse and harmonic excitation are considered. Coupling of the acoustic signal with the pipe resonant modes is shown to generate a complex transient wave with rich harmonic content.

  9. 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.

  10. Vibro-acoustics

    CERN Document Server

    Nilsson, Anders

    2015-01-01

    This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...

  11. Springer handbook of acoustics

    CERN Document Server

    2014-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays  and acoustic emission.  Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...

  12. Particle image velocimetry measurement of an instability wave over a porous wall in a duct with flow

    Science.gov (United States)

    Alomar, Antoni; Aurégan, Yves

    2017-01-01

    The flow in a rectangular channel lined with a porous material and acoustically excited with an upstream loudspeaker has been investigated using particle image velocimetry. The measurements are phase-locked to the loudspeaker signal so that the phase-averaged velocity in the lined section is obtained during an excitation period. Most features of the phase-averaged velocity field in the lined section are found to be well described from the sum of three single duct modes: the hydrodynamic instability wave, a standing wave and an acoustic wave. The hydrodynamic instability wave travels at half the mean flow velocity, and its structure shows differences to the case of a locally reacting liner. The relative phase lag between the hydrodynamic and acoustic waves at the liner end dictates the interference between both waves, giving rise to the oscillations of the acoustical transmission coefficient as a function of the frequency. A detachment of the instability wave from the porous wall is observed in the vicinity of the liner downstream edge, together with the separation of the mean vorticity core.

  13. A multi-channel feedback algorithm for the development of active liners to reduce noise in flow duct applications

    Science.gov (United States)

    Mazeaud, B.; Galland, M.-A.

    2007-10-01

    The present paper deals with the design and development of the active part of a hybrid acoustic treatment combining porous material properties and active control techniques. Such an acoustic system was developed to reduce evolutionary tones in flow duct applications. Attention was particularly focused on the optimization process of the controller part of the hybrid cell. A piezo-electric transducer combining efficiency and compactness was selected as a secondary source. A digital adaptive feedback control algorithm was specially developed in order to operate independently cell by cell, and to facilitate a subsequent increase in the liner surface. An adaptive bandpass filter was used to prevent the development of instabilities due to the coupling occurring between cells. Special care was taken in the development of such systems for time-varying primary signals. An automatic frequency detection loop was therefore introduced in the control algorithm, enabling the continuous adaptation of the bandpass filtering. The multi-cell structure was experimentally validated for a four-cell system located on a duct wall in the presence of flow. Substantial noise reduction was obtained throughout the 0.7-2.5 kHz frequency range, with flow velocities up to 50 m/s.

  14. Time-Dependent Parabolic Finite Difference Formulation for Harmonic Sound Propagation in a Two-Dimensional Duct with Flow

    Science.gov (United States)

    Kreider, Kevin L.; Baumeister, Kenneth J.

    1996-01-01

    An explicit finite difference real time iteration scheme is developed to study harmonic sound propagation in aircraft engine nacelles. To reduce storage requirements for future large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable for a harmonic monochromatic sound field, a parabolic (in time) approximation is introduced to reduce the order of the governing equation. The analysis begins with a harmonic sound source radiating into a quiescent duct. This fully explicit iteration method then calculates stepwise in time to obtain the 'steady state' harmonic solutions of the acoustic field. For stability, applications of conventional impedance boundary conditions requires coupling to explicit hyperbolic difference equations at the boundary. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.

  15. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-04-30

    OASIS, INC. 1 Report No. QSR-14C0172-Ocean Acoustics-043016 Quarterly Progress Report Technical and Financial Deep Water Ocean Acoustics...understanding of the impact of the ocean and seafloor environmental variability on deep- water (long-range) ocean acoustic propagation and to...improve our understanding. During the past few years, the physics effects studied have been three-dimensional propagation on global scales, deep water

  16. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-10-07

    Res., 114, C07021. Evers, L. G. & Snellen , M., 2015. Passive probing of the sound fixing and ranging channel with hydro-acoustic observations from...ridge earthquakes, J. Acoust. Soc. Am., 137, 2124–2136. Evers, L. G., Green, D. N., Young, N. W., & Snellen , M., 2013. Remote hydroacoustic sensing...Heaney, K. D., Assink, J. D., Smets, P. S. M., & Snellen , M., 2014. Evanescent wave coupling in a geophysical system: Airborne acoustic signals from

  17. Nearfield Acoustical Holography

    Science.gov (United States)

    Hayek, Sabih I.

    Nearfield acoustical holography (NAH) is a method by which a set of acoustic pressure measurements at points located on a specific surface (called a hologram) can be used to image sources on vibrating surfaces on the acoustic field in three-dimensional space. NAH data are processed to take advantage of the evanescent wavefield to image sources that are separated less that one-eighth of a wavelength.

  18. Three-Dimensional Acoustic Propagation Through Shallow Water Internal, Surface Gravity and Bottom Sediment Waves

    Science.gov (United States)

    2011-09-01

    high resolution bathymetry of the mouth of San Francisco Bay. Very strong acoustic ducting is shown to steer acoustic energy beams along the sand...10’ 73oW 50’ 55’ 39oN 5’ 10’ 15’ envmoor smoor glenmoor osumoor osu BL MSM NRL300 NRL500 whoi224 whoi400 SHRU WHOI array ASIS (b... Francisco Bay in 2005 and described in [71]. High resolution (2x2 m) bathymetry data was gathered with multiple multibeam sonar measurements and is

  19. Development of a new duct leakage test: DeltaQ

    Energy Technology Data Exchange (ETDEWEB)

    Walker,I.S.; Sherman,M.H.; Wempen, J.; Wang, D.; McWilliams, J.A.; Dickerhoff, D.J.

    2001-08-01

    Duct leakage is a key factor in determining energy losses from forced air heating and cooling systems. Several studies (Francisco and Palmiter 1997 and 1999, Andrews et al. 1998, and Siegel et al. 2001) have shown that the duct system efficiency cannot be reliably determined without good estimates of duct leakage. Specifically, for energy calculations, it is the duct leakage air flow to outside at operating conditions that is required. Existing test methods either precisely measure the size of leaks (but not the flow through them at operating conditions), or measure these flows with insufficient accuracy. The DeltaQ duct leakage test method was developed to provide improved estimates of duct leakage during system operation. In this study we developed the analytical calculation methods and the test procedures used in the DeltaQ test. As part of the development process, we have estimated uncertainties in the test method (both analytically and based on field data) and designed automated test procedures to increase accuracy and reduce the contributions of operator errors in performing field tests. In addition, the test has been evaluated in over 100 houses by several research teams to show that it can be used in a wide range of houses and to aid in finding limits or problems in field applications. The test procedure is currently being considered by ASTM as an update of an existing duct leakage standard.

  20. Mechanical properties of the porcine bile duct wall

    Directory of Open Access Journals (Sweden)

    Andersen Helle

    2004-07-01

    Full Text Available Abstract Background and Aim The function of the common bile duct is to transport bile from the liver and the gall bladder to the duodenum. Since the bile duct is a distensible tube consisting mainly of connective tissue, it is important to obtain data on the passive mechanical wall properties. The aims of this study were to study morphometric and biomechanical wall properties during distension of the bile duct. Methods Ten normal porcine common bile ducts were examined in vitro. A computer-controlled volume ramp infusion system with concomitant pressure recordings was constructed. A video camera provided simultaneous measurement of outer dimensions of the common bile duct. Wall stresses and strains were computed. Results The common bile duct length increased by 25% from 24.4 ± 1.8 mm at zero pressure to 30.5 ± 2.0 mm at 5 kPa (p (βε - 1. The circumferential stress-strain curve was shifted to the left when compared to the longitudinal stress-strain curve, i.e. the linear constants (α values were different (p 0.5. Conclusion The porcine bile duct exhibited nonlinear anisotropic mechanical properties.

  1. Magnetic Resonance Sialography Findings of Submandibular Ducts Imaging

    Directory of Open Access Journals (Sweden)

    Nezahat Karaca Erdoğan

    2013-01-01

    Full Text Available Purpose. We aimed to assess the problem solving capability of magnetic resonance sialography (MR sialography, a noninvasive method for imaging submandibular gland ducts and determining duct-related pathologies, by comparing diseased and healthy cases. Materials and Methods. We conducted radiological assessment on a total of 60 submandibular glands (mean age 44.7 in 20 cases and 10 volunteers. MR sialography examinations were conducted with single-shot fast spin-echo sequence by using a surface coil placed on the submandibular gland. Each gland was evaluated in terms of the length, width and stricture of the main duct, as well as the difference between the intraparenchymal duct width, and the main duct width. Statistical analysis was performed. Results. In the MR sialography the primary duct mean length was determined as 51 mm (40–57 mm in all submandibular glands. On the MR sialography imaging, the visualization ratio of the ductal system of submandibular gland was evaluated in the cases and volunteers. Conclusion. MR sialography is an effective and a noninvasive method in imaging submandibular gland ducts, demonstrating the presence, location and degree of stricture/dilatation, and elucidating the disease etiology.

  2. Handbook of Engineering Acoustics

    CERN Document Server

    Möser, Michael

    2013-01-01

    This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.

  3. Shallow Water Acoustic Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where high-frequency acoustic scattering and surface vibration measurements of fluid-loaded and non-fluid-loaded structures...

  4. Acoustic Technology Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — This laboratory contains an electro-magnetic worldwide data collection and field measurement capability in the area of acoustic technology. Outfitted by NASA Langley...

  5. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  6. Laboratory for Structural Acoustics

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where acoustic radiation, scattering, and surface vibration measurements of fluid-loaded and non-fluid-loaded structures are...

  7. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook...... will present topics on signal processing which are important in a specific area of acoustics. These will be of interest to specialists in these areas because they will be presented from their technical perspective, rather than a generic engineering approach to signal processing. Non-specialists, or specialists...

  8. Flow Development through a Duct and a Diffuser Using CFD

    Directory of Open Access Journals (Sweden)

    Prasanta K.Sinha

    2017-01-01

    Full Text Available In the present paper an extensive study of rectangular cross-sectioned C-duct and C-diffuser is made by the help of 2-D mean velocity contours. Study of flow characteristics through constant area duct is a fundamental research area of basic fluid mechanics since the concepts of potential flow and frictional losses in conduit flow were established. C-ducts are used in aircraft intakes, combustors, internal cooling systems of gas turbines, ventilation ducts, wind tunnels etc., while diffuser is mechanical device usually made in the form of a gradual conical expander intended to raise the static pressure of the fluid flowing through it. Flow through curved ducts is more complex compared to straight duct due to the curvature of the duct axis and centrifugal forces are induced on the flowing fluid resulting in the development of secondary motion (normal to the primary flow direction which is manifested in the form of a pair of contra-rotating vortices. For a diffuser in addition to the secondary flow, the diverging flow passage, which causes an adverse stream wise pressure gradient, can lead to flow separation. The combined effect may result n non uniformity of total pressure and total pressure loss at the exit. A comparative study of different turbulent models available in the Fluent using y  as guidance in selecting the appropriate grid configuration and turbulence models are done. Standard k-ε model and RSM models are used to solve the closure problem for both the constant area duct and the diffuser. It has been observed that the Standard k-e model predicts the flow through the constant area duct and the diffuser within a reasonable domain ofthe y  range.

  9. Acoustic Nondestructive Testing and Measurement of Tension for Steel Reinforcing Members: Part 2 - Field Testing

    Science.gov (United States)

    2014-09-01

    steel beam-and-girder designs, but a significant problem is that the anchor tendons (i.e., rods) are inaccessible for expedient inspection and repair . A...embedded in concrete. Acoustic waves are nondestructive. They can travel long distances through engineered structures and can be used to thoroughly...complete post-tensioned anchorage system includes tendons (bars/rods or strands), anchorage devices or bearing plates, ducts, end caps, grout tubes

  10. Bound states in the continuum in open acoustic resonators

    CERN Document Server

    Lyapina, A A; Pilipchuk, A S; Sadreev, A F

    2015-01-01

    We consider bound states in the continuum (BSC) or embedded trapped modes in two- and three-dimensional acoustic axisymmetric duct-cavity structures. We demonstrate numerically that under variation of the length of the cavity multiple BSCs occur due to the Friedrich-Wintgen two-mode full destructive interference mechanism. The BSCs are detected by tracing the resonant widths to the points of the collapse of Fano resonances where one of the two resonant modes acquires infinite life-time. It is shown that the approach of the acoustic coupled mode theory cast in the truncated form of a two-mode approximation allows us to analytically predict the BSC frequencies and shape functions to a good accuracy in both two and three dimensions.

  11. Flow in Idealised Compliant Human Cystic Duct Models

    Science.gov (United States)

    Al-Atabi, M.; Chin, S. B.; Beck, S.; Luo, X. Y.

    The functions of the cystic duct and the role of its complicated geometry (in particular the valves of Heister), in the delivery of bile flow have always been a subject of speculation. This paper reports on an experimental investigation of the flow in idealised, compliant cystic duct models. The valves of Heister were idealised using eight semi-circular alternating baffles fitted inside the compliant tubes. These tubes were arranged in configurations representing the anatomical configurations of real cystic ducts. Models both with and without baffles were tested for comparison. The results show that the valves of Heister seem to play a role in facilitating both the filling and emptying of the gallbladder.

  12. A procedure for the calculation of flow through axisymmetric ducts

    Directory of Open Access Journals (Sweden)

    P. S. Heyns

    1983-03-01

    Full Text Available A procedure for the calculation of flow through axisymmetric ducts as are typically found in turbomachines, is presented. The procedure is based on a streamline curvature method with the governing equations formulated along quasi-orthogonals in the flow field. This formulation allows the procedure to be used for segments of a duct wherein the flow direction is predominantly radial. It is assumed that the flow on specific stream surfaces is isentropic, but normal entropy gradients may exist because of processes which took place upstream of the duct.

  13. Spontaneous common bile duct perforation due to periampullary growth

    Directory of Open Access Journals (Sweden)

    Pandiaraja Javabal

    2014-06-01

    Full Text Available Spontaneous common bile duct perforations are an unusual cause of acute abdomen. In spontaneous common bile duct perforation, malignant growth is even rare. It is a rare entity usually reported in infants and children due to congenital anomalies. It is rarely reported in adults. In this case report, a 55 - year - old male patient who was diagnosed as a duodenal perforation in the pre - operative period, but the intra - operative findings was common bile duct perforation due to periampullary growth, is reported

  14. Spontaneous rupture of intrahepatic biliary ducts with biliary peritonitis.

    Science.gov (United States)

    Aydin, Unal; Yazici, Pinar; Coker, Ahmet

    2007-01-01

    Spontaneous rupture of intrahepatic biliary ducts is a rare cause of acute abdomen due to biliary peritonitis. We report a 92-year-old woman with 48-h history of upper abdominal pain, nausea and vomiting and peritoneal signs. CT scan showed free fluid in the abdomen and mild dilatation of the common bile duct. Exploratory laparotomy showed bile in the abdominal cavity with leak-age from a ruptured bile duct radicle in segment 3, as confirmed on intraoperative cholangiography. She underwent cholecystectomy, choledochotomy with removal of gallstones, repair of the perforation with primary suture and placement of a T-tube. She had an uneventful recovery.

  15. Thermo-chemo-radiotherapy for advanced bile duct carcinoma

    Institute of Scientific and Technical Information of China (English)

    Terumi Kamisawa; Yuyang Tu; Naoto Egawa; Katsuyuki Karasawa; Tadayoshi Matsuda; Kouji Tsuruta; Atsutake Okamoto

    2005-01-01

    AIM: Complete resection of the bile duct carcinoma is sometimes difficult by subepithelial spread in the duct wall or direct invasion of adjacent blood vessels. Nonresected extrahepatic bile duct carcinoma has a dismal prognosis,with a life expectancy of about 6 mo to 1 year. To improve the treatment results of locally advanced bile duct carcinoma, we have been conducting a clinical trial using regional hyperthermia in combination with chemoradiation therapy.METHODS: Eight patients complaining of obstructive jaundice with advanced extrahepatic bile duct underwent thermo-chemo-radiotherapy (TCRT). All tumors were located in the upper bile duct and involved hepatic bifurcation, and obstructed the bile duct completely.Radiofrequency capacitive hyperthermia was administered simultaneously with chemotherapeutic agents once weekly immediately following radiotherapy at 2 Gy.We administered heat to the patient for 40 min after the tumor temperature had risen to 42 ℃. The chemotherapeutic agents employed were cis-platinum (CDDP,50 mg/m2) in combination with 5-fluorouracil (5-FU,800 mg/m2) or methotrexate (MTX, 30 mg/m2) in combination with 5-FU (800 mg/m2). Number of heat treatments ranged from 2 to 8 sessions. The bile duct at autopsy was histologically examined in three patients treated with TCRT.RESULTS: In respect to resolution of the bile duct, there were three complete regression (CR), two partial regression (PR), and three no change (NC). Mean survival was 13.2±10.8 mo (mean±SD). Four patients survived for more than 20 mo. Percutaneous transhepatic biliary drainage (PTBD) tube could be removed in placement of self-expandable metallic stent into the patency-restored bile duct after TCRT. No major side effects occurred. At autopsy, marked hyalinization or fibrosis with necrosis replaced extensively bile duct tumor and wall, in which suppressed cohesiveness of carcinoma cells and degenerative cells were sparsely observed.CONCLUSION: Although the number of cases is

  16. EFFECT OF AIRFLOW AND HEAT INPUT RATES ON DUCT EFFICIENCY.

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS,J.W.

    2003-05-28

    Reducing the airflow and heat input rates of a furnace that is connected to a duct system in thermal contact with unconditioned spaces can significantly reduce thermal distribution efficiency. This is a straightforward theoretical calculation based on the increased residence time of the air in the duct at the lower flow rate, which results in greater conduction losses. Experimental tests in an instrumented residential-size duct system have confirmed this prediction. Results are compared with the heat-loss algorithm in ASHRAE Standid 152P. The paper concludes with a discussion of possible remedies for this loss of efficiency in existing systems and optional design strategies in new construction.

  17. Paraurethral Skene′s duct cyst in a newborn

    Directory of Open Access Journals (Sweden)

    Serdar Moralioglu

    2013-01-01

    Full Text Available Paraurethral or Skene′s duct cysts are rare causes of interlabial masses in neonates. The diagnosis of Skene′s duct cysts in the neonatal period is based on its location, in relation to the urethra, and the demonstration of transitional epithelium in the cyst wall. The distinguishing features of paraurethral cysts are the displacement of urethral meatus by the mass and a cyst containing milky fluid. Thus, we report a case of a Skene′s duct cyst in a newborn which was treated by incision and drainage.

  18. [Inadvertent thoracic duct puncture during right axially central venous cannulation].

    Science.gov (United States)

    Kawashima, Shingo; Itagaki, Taiga; Adachi, Yushi; Ishii, Yasuhiro; Taniguchi, Midzuki; Doi, Matsuyuki; Sato, Shigehito

    2010-10-01

    A case of inadvertent thoracic duct puncture during right axially central venous cannulation is reported. The catheterization was performed under the real time ultrasound guidance technique and the coronal view image was continuously displayed. After confirming the feelings of venous puncture, clear yellow fluid was aspired into the connected syringe to the needle. Initially, an accidental thoracic puncture with subsequent pleural fluid aspiration was suspected;however, no finding of pleural effusion was observed with ultrasound imaging and computed tomography. Thus, an accidental thoracic duct puncture and the subsequent lymph fluid aspiration were suspected. Even in a right side approach for central venous catheterization, thoracic duct injury might ensure.

  19. BACTERIOLOGICAL INVESTIGATION ON Fasciola hepatica AND CATTLE BILIARY DUCTS

    Directory of Open Access Journals (Sweden)

    A. Panebianco

    2009-03-01

    Full Text Available The aim of this work was to investigate the occurrence of bacteria in Fasciola hepatica and into cattle biliary ducts containing the parasite. A total of 24 liver and 58 F. hepatica samples were analysed. In all biliary ducts and in 62,06% of parasite Enterobacteriaceae were isolated. The bacterial specie more frequently isolated from parasite were Citrobacter freundii (34%, Proteus mirabilis (18%, Providencia rettgeri (12%, Staphylococcus spp. (18%, Enterobacter spp. (12%. There doesn’t appear to be a correlation between bacterial specie from parasite and ducts. The Authors conclude with some related inspective consideration.

  20. Transition duct with late injection in turbine system

    Energy Technology Data Exchange (ETDEWEB)

    LeBegue, Jeffrey Scott; Pentecost, Ronnie Ray; Flanagan, James Scott; Kim, Won -Wook; McMahan, Kevin Weston

    2015-09-15

    A system for supplying an injection fluid to a combustor is disclosed. The system includes a transition duct comprising 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 passage defines a combustion chamber. The system further includes a tube providing fluid communication for the injection fluid to flow through the transition duct and into the combustion chamber.

  1. Experimental study on inhibitory effect of bridgy duct of hepatic artery on apoptosis of liver and bile duct cells

    Institute of Scientific and Technical Information of China (English)

    Hongwei Lu; Yiming Li; Hong Ji; Jinkai Xu

    2006-01-01

    Objective: To investigate whether the method of bridgy duct established between the recipient's spleen artery and the donor's gastroduodenal artery could inhibit the apoptosis of liver and bile duct cells caused by hepatic artery ischemia.Methods: Twenty-four mongrel dogs from Xi'an area were used to establish simplified models of dog orthotopic liver transplantation and divided into three groups randomly: HAI group (hepatic artery ischemia group),BBB group (bypassing the blood by a bridgy duct) and control group. After cold perfusion, The samples were collected from liver and bile duct in each group at different time and fixed in glutaraldehyde and 4% polyformaldehyde respectively. At last, the apoptosis of liver and bile duct cells were observed and the apoptotic indexes were calculated. Results: Two hours after cold perfusion, apoptotic phenomenon was common in HAI group, rare in BBB group, while no apoptotic phenomenon was observed in control group. TUNEL staining showed that there was no significant difference in apoptotic index among the three groups immediately after cold perfusion. However, with time going, the apoptotic cells were increased in three groups, and the difference in apoptotic index was significant among three groups (P < 0.01 ). Conclusion: Bridgy duct of hepatic artery can inhibit the apoptosis of liver and bile duct cells caused by HAI significantly.

  2. Intestinal prolapse through a persistent omphalomesenteric duct causing small-bowel obstruction.

    Science.gov (United States)

    Pauleau, Ghislain; Commandeur, Diane; Andro, Christophe; Chapellier, Xavier

    2012-07-11

    Persistent omphalomesenteric duct as a cause of small-bowel obstruction is an exceptional finding. A neonate presented with occlusion due to intestinal prolapse through a persistent omphalomesenteric duct. Remnants of the duct were successfully resected, and the postoperative course was uneventful. We discuss the presentation of omphalomesenteric duct and its management.

  3. ß-adrenergic regulation of ion transport in pancreatic ducts: Patch-clamp study of isolated rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I

    1998-01-01

    much smaller effects. At comparable concentrations, it depolarized Vm by a few millivolts. Neither agonist had significant effects on intracellular Ca2+. CONCLUSIONS: This study provides the first direct evidence that adrenergic stimulation, namely, that of beta-adrenoceptors, controls ion transport....... METHODS: Small intralobular ducts were isolated from rat pancreas and studied in vitro by the whole-cell patch clamp technique. Cell membrane voltages and currents were indicators of cellular ion transport. In some ducts, intracellular Ca2+ activity was measured by fluorescence optical methods. RESULTS...... in pancreatic ducts. Similar to secretin, isoproterenol stimulation leads to opening of luminal Cl- channels, and HCO3- enters the lumen in exchange for Cl-....

  4. Acoustic fluidization for earthquakes?

    OpenAIRE

    Sornette, D.; Sornette, A.

    2000-01-01

    Melosh [1996] has suggested that acoustic fluidization could provide an alternative to theories that are invoked as explanations for why some crustal faults appear to be weak. We show that there is a subtle but profound inconsistency in the theory that unfortunately invalidates the results. We propose possible remedies but must acknowledge that the relevance of acoustic fluidization remains an open question.

  5. Acoustic diffusers III

    Science.gov (United States)

    Bidondo, Alejandro

    2002-11-01

    This acoustic diffusion research presents a pragmatic view, based more on effects than causes and 15 very useful in the project advance control process, where the sound field's diffusion coefficient, sound field diffusivity (SFD), for its evaluation. Further research suggestions are presented to obtain an octave frequency resolution of the SFD for precise design or acoustical corrections.

  6. Parametric Room Acoustic Workflows

    DEFF Research Database (Denmark)

    Parigi, Dario; Svidt, Kjeld; Molin, Erik

    2017-01-01

    The paper investigates and assesses different room acoustics software and the opportunities they offer to engage in parametric acoustics workflow and to influence architectural designs. The first step consists in the testing and benchmarking of different tools on the basis of accuracy, speed and ...

  7. Anomalous pancreatico-biliary ductal union with cystic dilatation of the bile duct.

    Science.gov (United States)

    Richer, J P; Faure, J P; Morichau-Beauchant, M; Dugue, T; Maillot, N; Kamina, P; Carretier, M

    1998-01-01

    We report, in an adult, an asymptomatic association between cystic dilation of the bile duct (type IV A in Todani's classification) and anomalous pancreatico-biliary ductal union (APBD) with stones in a long common channel. In APBD, the connection between the common bile duct and the main pancreatic duct is located outside the duodenal wall andis therefore not under the influence of the sphincter of Boyden. An abnormally long common channel is in excess of 15 mm. Two types of convergence anomalies are defined according to whether the bile duct opens into the main pancreatic duct (BP) or the main pancreatic duct into the bile duct (PB). In APBD, there is probably a reverse pressure gradient between the bile and pancreatic ducts, with regurgitation of pancreatic juice into the bile duct, repeated attacks of cholangitis, stenosis and cystic dilatation. A long common channel is associated with a higher incidence of carcinoma of the gall bladder of the bile duct.

  8. Heat Transfer Augmentation in Developing Flow Through a Ribbed Square Duct

    Institute of Scientific and Technical Information of China (English)

    Khan R K; Ali M.A.T; Akhanda M.A.R

    2006-01-01

    An experimental study is conducted to investigate the heat transfer augmentation in developing turbulent flow through a ribbed square duct. The duct is made of 16mm thick bakelite sheet. The bottom surface of the ribbed wall having rib pitch to height ratio of 10 is heated by passing a c current to the heater placed under it. The uniform heating is controlled using a digital temperature controller and a variac. The results of ribbed duct are compared with the results of a smooth duct under the same experimental conditions. It is observed that the heat transfer augmentation in ribbed duct is better than that of the smooth duct. At Re=5.0 × 104 , the mean temperature of air flowing through the ribbed duct increases by 2.45 percent over the smooth duct, whereas in the ribbed duct Nusselt number increases by 15.14 percent than that of the smooth duct with a 6 percent increase in pressure drop.

  9. Molecular basis of potassium channels in pancreatic duct epithelial cells

    DEFF Research Database (Denmark)

    Hayashi, M.; Novak, Ivana

    2013-01-01

    Potassium channels regulate excitability, epithelial ion transport, proliferation, and apoptosis. In pancreatic ducts, K channels hyperpolarize the membrane potential and provide the driving force for anion secretion. This review focuses on the molecular candidates of functional K channels...

  10. 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, our...... aim was to reveal whether pancreatic duct cells release ATP locally and whether they enzymatically modify extracellular nucleotides/sides. Second, we wished to explore which physiological and pathophysiological factors may be important in these processes. Using a human pancreatic duct cell line, Capan......-1, and online luminescence measurement, we detected fast ATP release in response to pH changes, bile acid, mechanical stress and hypo-osmotic stress. ATP release following hypo-osmotic stress was sensitive to drugs affecting exocytosis, pannexin-1, connexins, maxi-anion channels and transient...

  11. Persistent omphalomesenteric duct causing small bowel obstruction in an adult

    Institute of Scientific and Technical Information of China (English)

    Haridimos Markogiannakis; Dimitrios Theodorou; Konstantinos G Toutouzas; Panagiotis Drimousis; Sotirios Georgios Panoussopoulos; Stilianos Katsaragakis

    2007-01-01

    An extremely rare case of persistent omphalomesenteric duct causing small bowel obstruction is presented. A 20-year-old female patient without medical history presented with colicky abdominal pain, vomiting, absence of passage of gas and feces, and abdominal distension of 24 h duration. Physical examination and blood tests were normal. Abdominal X-ray showed small bowel obstruction.Computed tomography of the abdomen demonstrated dilated small bowel and a band originating from the umbilicus and continuing between the small bowel loops;an omphalomesenteric duct remnant was suspected. In exploratory laparotomy, persistent omphalomesenteric duct causing small bowel obstruction was identified and resected. The patient had an uneventful recovery and was discharged on the 5th postoperative day. Although persistent omphalomesenteric duct is an extremely infrequent cause of small bowel obstruction in adult patients, it should be taken into consideration in patients without any previous surgical history.

  12. Nasolacrimal duct mucocele: case report and literature review.

    Science.gov (United States)

    Britto, Fernanda Carneiro Corujeira de; Rosier, Vitor Veloso; Luz, Tovar Vicente; Verde, Raquel Crisóstomo Lima; Lima, Clara Mônica Figueiredo de; Lessa, Marcus Miranda

    2015-01-01

    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.

  13. Design requirement on KALIMER control rod assembly duct

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, W.; Kang, H. Y.; Nam, C.; Kim, J. O.; Kim, Y. J

    1998-03-01

    This document establishes the design guidelines which are needs for designing the control rod assembly duct of the KALIMER as design requirements. it describes control rod assembly duct of the KALIMER and its requirements that includes functional requirements, performance requirements, interfacing systems, design limits and strength requirements, seismic requirements, structural requirements, environmental requirements, reliability and safety requirements, standard and codes, QA programs, and other requirements. The control rod system consists of three parts, which are drive mechanism, drive-line, and absorber bundle. This report deals with the absorber bundle and its outer duct only because the others are beyond the scope of fuel system design. The guidelines for design requirements intend to be used for an improved design of the control rod assembly duct of the KALIMER. (author). 19 refs.

  14. 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.

  15. Iatrogenic nasolacrimal duct obstruction following tooth extraction in a cat.

    Science.gov (United States)

    Paiva, Sávia Calline C S; Froes, Tilde R; Lange, Rogério Ribas; Machado, Marcello; Pachaly, José Ricardo; Montiani-Ferreira, Fabiano

    2013-01-01

    A 10-year-old DSH cat was referred for a dental evaluation and extraction procedure. Subsequently, the animal developed an acute onset of ocular discharge. Ophthalmologic examination revealed presence of unilateral ocular mucoid discharge leading to a diagnosis of epiphora secondary to nasolacrimal duct obstruction. Dacryocystorhinography was performed and confirmed the presence of a nasolacrimal duct obstruction, presumably acquired after an invasive dental procedure. Additionally, a vinyl cast in situ study of the nasolacrymal apparatus was performed to demonstrate the route of the nasolacrimal duct in the cat and its relationship to oral dental structures. This report documents an unusual case in which excessive inflammation/edema following tooth extraction caused acute epiphora secondary to extraluminal compression of the distal nasolacrimal duct.

  16. 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...

  17. Molecular basis of potassium channels in pancreatic duct epithelial cells

    DEFF Research Database (Denmark)

    Hayashi, M.; Novak, Ivana

    2013-01-01

    Potassium channels regulate excitability, epithelial ion transport, proliferation, and apoptosis. In pancreatic ducts, K channels hyperpolarize the membrane potential and provide the driving force for anion secretion. This review focuses on the molecular candidates of functional K channels in pan...

  18. Extrahepatic right hepatic duct diverticulum:a rare entity

    Institute of Scientific and Technical Information of China (English)

    Eduardo SM Fernandes; Raquel L Bernardo; Moacir M Fernandes; Rogério MC Araújo; Renato Sebbe; Asterio Monte; José F Coelho; Antonio AP Souza; Joaquim Ribeiro Filho

    2010-01-01

    BACKGROUND: Douglas described choledochal cysts in 1852 and Todani proposed an anatomy-based classiifcation in 1977. The classiifcation is the most extensively used, but does not include some rare variations. We present a case of hepatic duct diverticulum, one of the variations, and discuss its diagnosis and treatment. METHODS: A 57-year-old woman presented with upper abdominal pain and discomfort associated with nausea and vomiting. She was ifnally diagnosed with cholelithiasis and right hepatic duct diverticulum. RESULT: The patient underwent resection of the hepatic duct diverticulum and cholecystectomy, and was asymptomatic 26 months after surgery. CONCLUSIONS: Hepatic duct diverticulum is a rare form of choledochal cyst, not included in Todani's classiifcation. Todani's classiifcation including this and other uncommon variations of choledochal cysts must be reviewed. The best diagnostic imaging methods and treatment for choledochal cysts must be deifned.

  19. 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.

  20. Computational Ocean Acoustics

    CERN Document Server

    Jensen, Finn B; Porter, Michael B; Schmidt, Henrik

    2011-01-01

    Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...

  1. Acoustic ground impedance meter

    Science.gov (United States)

    Zuckerwar, A. J. (Inventor)

    1984-01-01

    A method and apparatus are presented for measuring the acoustic impedance of a surface in which the surface is used to enclose one end of the chamber of a Helmholz resonator. Acoustic waves are generated in the neck of the resonator by a piston driven by a variable speed motor through a cam assembly. The acoustic waves are measured in the chamber and the frequency of the generated acoustic waves is measured by an optical device. These measurements are used to compute the compliance and conductance of the chamber and surface combined. The same procedure is followed with a calibration plate having infinite acoustic impedance enclosing the chamber of the resonator to compute the compliance and conductance of the chamber alone. Then by subtracting, the compliance and conductance for the surface is obtained.

  2. Cochlear bionic acoustic metamaterials

    Science.gov (United States)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  3. 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.

  4. 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....

  5. Bile duct hamar tomas-the von Meyenburg complex

    Institute of Scientific and Technical Information of China (English)

    Valdemir José Alegre Salles; Alexandre Marotta; Jorge Miguel Kather Netto; Manlio Basílio Speranzini; Marcos Roberto Martins

    2007-01-01

    Hamartomas of the bile duct (von Meyenburg complex) are benign neoplasms of the liver, constituted histologically cystic dilatations of the bile duct, encompassed by ifbrous stroma. We report a 42-year-old female patient with symptomatic cholecystitis, whose gross and ultrasonic appearance suggestive of multiple liver metastases. Magnetic resonance imaging and liver biopsy are the gold standards for diagnosis of this rare hepatobiliary condition.

  6. A case report of hepatocellular carcinoma in common hepatic duct

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chi Sung; Park, In Ae; Choi, Sang Woon; Chung, Jung Kee [YongDeungPo City Hospital, Seoul (Korea, Republic of)

    1989-08-15

    We experienced a rare case of intraductal (common hepatic duct) hepatocellular carcinoma. Review of the literature disclosed 30 cases or less in which common duct involvement was a predominant clinical feature. Well demarcated, ovoid filling defect mass in CHD without parenchymal tumor mass was noted in ultrasound, PTC and CT study. The liver was cirrhotic, but {alpha}-fetoprotein level was normal. Differential diagnosis especially with Klatskin tumor is important and thought to be possible.

  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. Female form of persistent mullerian duct syndrome: Rare entity

    Directory of Open Access Journals (Sweden)

    Shailesh Solanki

    2015-01-01

    Full Text Available Persistent Mullerian duct syndrome (PMDS is a rare form of Disorder of sex development in which Mullerian duct derivatives (fallopian tubes, uterus and the proximal vagina are present in an otherwise normally differentiated 46 XY male. In the majority of cases, PMDS is a surprise finding either during orchidopexy or during inguinal hernia repair. We report a case of 4 year child with female type (Type III PMDS. We are discussing the presentation, management and review of the literature.

  9. EXPERIMENTAL INVESTIGATION OF A VARIABLE GEOMETRY DUCTED PROPELLER

    Directory of Open Access Journals (Sweden)

    Tomasz Muszyński

    2013-03-01

    Full Text Available The paper presents preliminary results of experimental research on the variable geometry of a ducted propeller. The purpose of this work is explore the area of ​​application of the ducted propellers of variable geometry. The paper contains the description of a test station and a model, initial tests’ results of some selected geometries intakes and exit vents in comparison with an open propeller.

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

    Science.gov (United States)

    2016-09-01

    Approved for public release: distribution unlimited TDS-NAVFAC-EXWC-PW-1603 Sep 2016 HVAC ; Heating, Ventilation, Air Conditioning - Aerosol...energy consumption, depending on the HVAC system type and the location of the ducts that were sealed. The cost effectiveness of the technology is...Although several studies have been done on the effectiveness of sealing leaky HVAC ductwork with aerosol duct sealant, few studies have been done on

  11. A case of peribiliary cysts accompanying bile duct carcinoma

    Institute of Scientific and Technical Information of China (English)

    Fumihiko Miura; Tadahiro Takada; Hodaka Amano; Masahiro Yoshida; Takahiro Isaka; Naoyuki Toyota; Keita Wada; Kenji Takagi; Kenichiro Karo

    2006-01-01

    A rare case of peribiliary cysts accompaying bile duct carcinoma is presented. A 54-year-old man was diagnosed as having lower bile duct carcinoma and peribiliary cysts by diagnostic imaging. He underwent pylorus preserving pancreatoduodenectomy. As for the peribiliary cysts, a course of observation was taken.Over surgery due to misdiagnosis of patients with biliary malignancy accompanied by peribiliary cysts should be avoided.

  12. Renal Collecting Duct Cancer: a Report of 2 Cases

    Institute of Scientific and Technical Information of China (English)

    Shiying Zhou

    2005-01-01

    @@ Renal collecting duct cancer is a rare malignant tumor, which accounts for 1% to 2% of epithelial kidney tumors,[1] Its pathological appearance has been easily misdiagnosed as a mammilliform renal cell carcinoma or as other tumors. The malignancy of renal collecting duct cancer is high, with early metastasis and poor prognosis. The clinical data for 2 cases of the tumor are discussed in this report, including reports on the histopathology and the changes in immunohistochemistry.

  13. Development and regression of the thyroglossal duct in mice.

    Science.gov (United States)

    Inoue, Katsuyuki; Bando, Yasuhiko; Sakiyama, Koji; Takizawa, Shota; Sakashita, Hideaki; Kondo, Hisatake; Amano, Osamu

    2015-07-01

    The thyroid anlage develops in the foramen caecum area of the tongue, and migrates through the anterior neck towards its final position in front of the laryngeal cartilages. During migration, the thyroglossal duct, a temporary structure connecting the thyroid anlage and the foramen caecum, is recognized. In the present study, chronological changes and apoptosis in the thyroglossal duct of mice were investigated histochemically using an antibody against Nkx2-1, initially identified as a thyroid transcription factor 1 (TTF1), and the TUNEL reaction in consecutive serial sagittal sections. At embryonic day 10.00 (E10.00), the thyroid anlage was Nkx2-1-immunoreactive and located just below the foramen caecum. As the thyroid anlage descended, the thyroglossal duct was formed at E10.25, being less than 10μm in diameter. By E10.75, the Nkx2-1-positive thyroglossal duct had progressively elongated up to 100μm. At E11.00 the thyroglossal duct began to disappear, beginning in its mid-portion, and finally became invisible at E11.50. At E11.00-12.00, apoptotic cells were found in an area where the thyroglossal duct was partially discontinuous. After E12.00, cartilaginous tissue of the hyoid bone anlage developed in the mid-portion of the area where the thyroglossal duct had regressed. Immunoreactivity for thyroglobulin, a marker of differentiated thyroid endocrine cells, was detected at E13.00. These results strongly suggest that the mouse thyroglossal duct disappears as a result of apoptosis before differentiation of the endocrine thyroid.

  14. On One-dimensional Sound Analysis of a Duct Network with Helmholtz Resonators

    OpenAIRE

    寺尾, 道仁; Terao, Michihito; 関根, 秀久; Sekine, Hidehisa; 大川, 真平; Okawa, Shinpei; 林, 大志; Hayashi, Daiji

    2002-01-01

    The outer orifice correction for Helmholtz resonators attached to the sidewall ofcircular ducts was studied. For the outer orifice correction when the axis direction ofthe orifice coincides with that of the duct, .explicit expressions were given by Ingard and Rschevkin. But their application to duct sections with duct-sidewall resonators is beyond their premise. An explicit expression ofthe outer orifice correction for duct-sidewall resonators was derived by conducting three-dimensionalbounda...

  15. Acoustic Force Density Acting on Inhomogeneous Fluids in Acoustic Fields

    DEFF Research Database (Denmark)

    Karlsen, Jonas Tobias; Augustsson, Per; Bruus, Henrik

    2016-01-01

    We present a theory for the acoustic force density acting on inhomogeneous fluids in acoustic fields on time scales that are slow compared to the acoustic oscillation period. The acoustic force density depends on gradients in the density and compressibility of the fluid. For microfluidic systems...

  16. Natural convection heat transfer along vertical rectangular ducts

    Science.gov (United States)

    Ali, M.

    2009-12-01

    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.

  17. [From Langenbuch to Strasberg: the spectrum of bile duct injuries].

    Science.gov (United States)

    Mercado, Miguel Angel

    2004-01-01

    Bile duct injuries are the main serious complication of laparoscopy cholecystectomy. The frequency of this type of injuries rangers, between 1 to 3 in 1,000 cases and although this rate remains stables, their frequency has increased because of the increasing expansion of the indication of cholecystectomy. Each lesion is the individual in it's features as well as the scenario in which the surgeon faces it. Several classifications have been developed, but that developed by Strasberg most used nowadays. Intraoperative cholangiography has shown evidence in meta analytic studies that diminishes the frequency of lesions but does not abolish them. Conversion from laparoscope's to the open approach with ample and convincent dissection is probably the best maneuver to reduce the frequency of lesions, when any anatomical or technical doubt appears. No patient should be operated in critical condition. In this situation, biliary reconstruction has a secondary role and only drainage of the ducts (percutaneous or surgical) is indicated. Roux en Y hepatoyeyunostomy is the procedure of choice for almost all cases, leaving other types of procedures for selected cases. Transhepatic transanastomotical stents should be used according to the individual status of the patient when small, scared or inflamed ducts are found. High quality anastomosis is obtained when proper ducts are found. Sometimes high dissection of the ducts is needed in order to obtain adequate ducts. Nine of each ten cases are completely rehabilitated, obtaining a good quality of life.

  18. 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.

  19. Energy efficient engine: Turbine transition duct model technology report

    Science.gov (United States)

    Leach, K.; Thurlin, R.

    1982-01-01

    The Low-Pressure Turbine Transition Duct Model Technology Program was directed toward substantiating the aerodynamic definition of a turbine transition duct for the Energy Efficient Engine. This effort was successful in demonstrating an aerodynamically viable compact duct geometry and the performance benefits associated with a low camber low-pressure turbine inlet guide vane. The transition duct design for the flight propulsion system was tested and the pressure loss goal of 0.7 percent was verified. Also, strut fairing pressure distributions, as well as wall pressure coefficients, were in close agreement with analytical predictions. Duct modifications for the integrated core/low spool were also evaluated. The total pressure loss was 1.59 percent. Although the increase in exit area in this design produced higher wall loadings, reflecting a more aggressive aerodynamic design, pressure profiles showed no evidence of flow separation. Overall, the results acquired have provided pertinent design and diagnostic information for the design of a turbine transition duct for both the flight propulsion system and the integrated core/low spool.

  20. Iatrogenic injury of an aberrant right posterior sectoral bile duct

    Directory of Open Access Journals (Sweden)

    John Cantrell

    2011-08-01

    Full Text Available A 34-year-old woman presented with a history of a previous laparoscopic cholecystectomy, followed within a few days by a formal laparotomy for a suspected bile duct injury. Approximately one week after the laparotomy, she developed a sinus on the anterior abdominal wall that was draining bile. She was then referred to our institution for further management. The earlier surgery was done at another hospital, and these details were not clear. A CT scan, including a CT sinogram, was performed. The sinogram was done by inserting a catheter into the sinus and running in diluted contrast under gravity. CT images showed the sinus tract communicating with a collection in the gallbladder fossa, as well as contrast opacification of the segment 6 and 7 bile ducts. A week later, an endoscopic retrograde cholangiopancreatography (ERCP examination was performed. This showed no filling of the right posterior sectoral ducts but normal opacification of the other ducts. These findings led to the diagnosis of an aberrant right posterior sectoral bile duct that was not identified prior to surgery and that was damaged at the time of laparoscopic cholecystectomy. This duct now drained into the gallbladder fossa, causing the collection and draining sinus.

  1. An evaporation duct prediction model coupled with the MM5

    Institute of Scientific and Technical Information of China (English)

    JIAO Lin; ZHANG Yonggang

    2015-01-01

    Evaporation duct is an abnormal refractive phenomenon in the marine atmosphere boundary layer. It has been generally accepted that the evaporation duct prominently affects the performance of the electronic equipment over the sea because of its wide distribution and frequent occurrence. It has become a research focus of the navies all over the world. At present, the diagnostic models of the evaporation duct are all based on the Monin-Obukhov similarity theory, with only differences in the flux and character scale calculations in the surface layer. These models are applicable to the stationary and uniform open sea areas without considering the alongshore effect. This paper introduces the nonlinear factorav and the gust wind itemwg into the Babin model, and thus extends the evaporation duct diagnostic model to the offshore area under extremely low wind speed. In addition, an evaporation duct prediction model is designed and coupled with the fifth generation mesoscale model (MM5). The tower observational data and radar data at the Pingtan island of Fujian Province on May 25–26, 2002 were used to validate the forecast results. The outputs of the prediction model agree with the observations from 0 to 48 h. The relative error of the predicted evaporation duct height is 19.3% and the prediction results are consistent with the radar detection.

  2. 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.

  3. The influence of mesoscale eddies on shallow water acoustic propagation

    Science.gov (United States)

    Deferrari, Harry; Olson, Donald

    2003-10-01

    Acoustic propagation measurements in 150 m depth on the Florida escarpment observe the effects of the passage of a cyclonic eddy. As the stream core of the Florida Current meanders, the eddy is formed and propagates along the shelf edge. The sequence over a roughly a fortnight is as follows: ahead of the eddy, warm surface water and cold bottom water are swept onto the terrace forming a steep thermocline and corresponding strong downward refracting C(z). The gradient produce intense, focused RBR arrivals and the thermocline becomes a duct for internal waves to propagate shoreward. At first, the internal wave energy is minimal and propagation is stable and coherent. As the internal tides attempt to propagate on shelf, the sound speed field and the acoustic signals become increasingly variable. The variability reaches a crescendo as the 200 m long internal tide is blocked from propagating on to the narrower shelf and begins to break and overturn producing small-scale variability. As the eddy passes, nearly iso-thermal conditions are restored along with quiescent internal wave fields and reduced signal variability. Here, the effects are quantized with data from fixed-system acoustic and oceanographic measurements demonstrating that the mesoscale determines acoustic propagation conditions days in advance.

  4. 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.

  5. Flat acoustic lens by acoustic grating with curled slits

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Pai; Xiao, Bingmu; Wu, Ying, E-mail: ying.wu@kaust.edu.sa

    2014-10-03

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. - Highlights: • Expression of transmission coefficient of an acoustic grating with curled slits. • Non-dispersive and tunable effective medium parameters for the acoustic grating. • A flat acoustic focusing lens with gradient index by using the acoustic grating.

  6. Acoustic mapping velocimetry

    Science.gov (United States)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  7. Underwater Applications of Acoustical Holography

    Directory of Open Access Journals (Sweden)

    P. C. Mehta

    1984-01-01

    Full Text Available The paper describes the basic technique of acoustical holography. Requirements for recording the acoustical hologram are discussed with its ability for underwater imaging in view. Some practical systems for short-range and medium-range imaging are described. The advantages of acoustical holography over optical imaging, acoustical imaging and sonars are outlined.

  8. Predicting Acoustics in Class Rooms

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2005-01-01

    Typical class rooms have fairly simple geometries, even so room acoustics in this type of room is difficult to predict using today's room acoustic computer modeling software. The reasons why acoustics of class rooms are harder to predict than acoustics of complicated concert halls might...

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

    Science.gov (United States)

    Kowal, J M; Yegutkin, G G; Novak, I

    2015-12-01

    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, our aim was to reveal whether pancreatic duct cells release ATP locally and whether they enzymatically modify extracellular nucleotides/sides. Second, we wished to explore which physiological and pathophysiological factors may be important in these processes. Using a human pancreatic duct cell line, Capan-1, and online luminescence measurement, we detected fast ATP release in response to pH changes, bile acid, mechanical stress and hypo-osmotic stress. ATP release following hypo-osmotic stress was sensitive to drugs affecting exocytosis, pannexin-1, connexins, maxi-anion channels and transient receptor potential cation channel subfamily V member 4 (TRPV4) channels, and corresponding transcripts were expressed in duct cells. Direct stimulation of intracellular Ca(2+) and cAMP signalling and ethanol application had negligible effects on ATP release. The released ATP was sequentially dephosphorylated through ecto-nucleoside triphosphate diphosphohydrolase (NTPDase2) and ecto-5'-nucleotidase/CD73 reactions, with respective generation of adenosine diphosphate (ADP) and adenosine and their maintenance in the extracellular medium at basal levels. In addition, Capan-1 cells express counteracting adenylate kinase (AK1) and nucleoside diphosphate kinase (NDPK) enzymes (NME1, 2), which contribute to metabolism and regeneration of extracellular ATP and other nucleotides (ADP, uridine diphosphate (UDP) and uridine triphosphate (UTP)). In conclusion, we illustrate a complex regulation of extracellular purine homeostasis in a pancreatic duct cell model involving: ATP release by several mechanisms and subsequent nucleotide breakdown and ATP regeneration via counteracting nucleotide

  10. Anatomic Variations of the Right Hepatic Duct: Results and Surgical Implications from a Cadaveric Study

    Directory of Open Access Journals (Sweden)

    Theodoros Mariolis-Sapsakos

    2012-01-01

    Full Text Available Purpose. Thorough understanding of biliary anatomy is required when performing surgical interventions in the hepatobiliary system. This study describes the anatomical variations of right bile ducts in terms of branching and drainage patterns, and determines their frequency. Methods. We studied 73 samples of cadaveric material, focusing on the relationship of the right anterior and posterior segmental branches, the way they form the right hepatic duct, and the main variations of their drainage pattern. Results. The anatomy of the right hepatic duct was typical in 65.75% of samples. Ectopic drainage of the right anterior duct into the common hepatic duct was found in 15.07% and triple confluence in 9.59%. Ectopic drainage of the right posterior duct into the common hepatic duct was discovered in 2.74% and ectopic drainage of the right posterior duct into the left hepatic duct in 4.11%. Ectopic drainage of the right anterior duct into the left hepatic ductal system and ectopic drainage of the right posterior duct into the cystic duct was found in 1.37%. Conclusion. The branching pattern of the right hepatic duct was atypical in 34.25% of cases. Thus, knowledge of the anatomical variations of the extrahepatic bile ducts is important in many surgical cases.

  11. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side ... Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a patient ...

  12. Thermal Acoustic Fatigue Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...

  13. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... resource Click to learn more... LOGIN EVENTS DONATE Home Learn Back Learn about acoustic neuroma AN Facts ... Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational Video OrangeTheory AN Warriors Laurie of ...

  14. Acoustic imaging system

    Science.gov (United States)

    Smith, Richard W.

    1979-01-01

    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  15. An acoustic invisible gateway

    CERN Document Server

    Zhu, Yi-Fan; Liang, Bin; Kan, Wei-Wei; Yang, Jun; Cheng, Jian-Chun

    2015-01-01

    The recently-emerged concept of "invisible gateway" with the extraordinary capability to block the waves but allow the passage of other entities has attracted great attentions due to the general interests in illusion devices. However, the possibility to realize such a fascinating phenomenon for acoustic waves has not yet been explored, which should be of paramount significance for acoustical applications but would necessarily involve experimental difficulty. Here we design and experimentally demonstrate an acoustic invisible gateway (AIG) capable of concealing a channel under the detection of sound. Instead of "restoring" a whole block of background medium by using transformation acoustics that inevitably requires complementary or restoring media with extreme parameters, we propose an inherently distinct methodology that only aims at engineering the surface impedance at the "gate" to mimic a rigid "wall" and can be conveniently implemented by decorating meta-structures behind the channel. Such a simple yet ef...

  16. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  17. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  18. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  19. Acoustic MIMO signal processing

    CERN Document Server

    Huang, Yiteng; Chen, Jingdong

    2006-01-01

    A timely and important book addressing a variety of acoustic signal processing problems under multiple-input multiple-output (MIMO) scenarios. It uniquely investigates these problems within a unified framework offering a novel and penetrating analysis.

  20. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... ANA About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma Association 600 Peachtree ... info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational ...

  1. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  2. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Choosing a healthcare provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a ...

  3. Acoustic imaging system

    Science.gov (United States)

    Kendall, J. M., Jr.

    1977-01-01

    Tool detects noise sources by scanning sound "scene" and displaying relative location of noise-producing elements in area. System consists of ellipsoidal acoustic mirror and microphone and a display device.

  4. Symptoms of Acoustic Neuroma

    Science.gov (United States)

    ... Programs & Services Search ANAUSA.org Connect with us! Symptoms of Acoustic Neuroma Each heading slides to reveal more information. Early Symptoms Early Symptoms Early symptoms are easily overlooked, thus making diagnosis ...

  5. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects ... To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a patient kit ...

  6. Autonomous Acoustic Receiver System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Collects underwater acoustic data and oceanographic data. Data are recorded onboard an ocean buoy and can be telemetered to a remote ship or shore station...

  7. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms ... effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a ...

  8. Principles of musical acoustics

    CERN Document Server

    Hartmann, William M

    2013-01-01

    Principles of Musical Acoustics focuses on the basic principles in the science and technology of music. Musical examples and specific musical instruments demonstrate the principles. The book begins with a study of vibrations and waves, in that order. These topics constitute the basic physical properties of sound, one of two pillars supporting the science of musical acoustics. The second pillar is the human element, the physiological and psychological aspects of acoustical science. The perceptual topics include loudness, pitch, tone color, and localization of sound. With these two pillars in place, it is possible to go in a variety of directions. The book treats in turn, the topics of room acoustics, audio both analog and digital, broadcasting, and speech. It ends with chapters on the traditional musical instruments, organized by family. The mathematical level of this book assumes that the reader is familiar with elementary algebra. Trigonometric functions, logarithms and powers also appear in the book, but co...

  9. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  10. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J;

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  11. Acoustic Communications (ACOMMS) ATD

    Science.gov (United States)

    2016-06-14

    Communications , Computers , Intelligence, Surveillance, and Reconnaissance (C4ISR) systems that "capture, synthesize and distribute near-real time information to...Acoustic Communications (ACOMMS) ATD Tam Nguyen 2531 Jefferson Davis Hwy Arlington, VA 22242 phone: (703) 604-6013 ext 520 fax: (703) 604-6056...email: NguyenTL@navsea.navy.mil Award # N0001499PD30007 LONG-TERM GOALS The goal of the recently completed Acoustic Communications Advanced

  12. Effect of herpesvirus infection on pancreatic duct cell secretion

    Institute of Scientific and Technical Information of China (English)

    Péter Hegyi; András Varró; Mária K Kovács; Mike A Gray; Barry E Argent; Zsolt Boldogk(o)i; Balázs (O)rd(o)g; Zoltán Rakonczai Jr; Tamás Takács; János Lonovics; Annamária Szabolcs; Réka Sári; András Tóth; Julius G Papp

    2005-01-01

    AIM: To examine the effect of acute infection caused by herpesvirus (pseudorabies virus, PRV) on pancreatic ductal secretion.METHODS: The virulent Ba-DupGreen (BDG) and nonvirulent Ka-RREpOlacgfp (KEG) genetically modified strains of PRV were used in this study and both of them contain the gene for green fluorescent protein (GFP). Small intra/interlobular ducts were infected with BDG virus (107 PFU/mL for 6 h) or with KEG virus (1010 PFU/mL for 6 h), while non-infected ducts were incubated only with the culture media. The ducts were then cultured for a further 18 h.The rate of HCO3- secretion [base efflux -J(B-)] was determined from the buffering capacity of the cells and the initial rate of intracellular acidification (1) after sudden blockage of basolateral base loaders with dihydro-4,4,-diisothiocyanatostilbene-2,2,-disulfonic acid (500 μmol/L)and amiloride (200 μmol/L), and (2) after alkali loading the ducts by exposure to NH4Cl. All the experiments were performed in HCO3--buffered Ringer solution at 37 ℃ (n = 5ducts for each experimental condition). Viral structural proteins were visualized by immunohistochemistry. Virallyencoded GFP and immunofluorescence signals were recorded by a confocal laser scanning microscope.RESULTS: The BDG virus infected the majority of accessible cells of the duct as judged by the appearance of GFP and viral antigens in the ductal cells. KEG virus caused a similarly high efficiency of infection. After blockage of basolateral base loaders, BDG infection significantly elevated -J(B-) 24 h after the infection, compared to the non-infected group. However, KEG infection did not modify -J(B-). After alkali loading the ducts, -J(B-) was significantly elevated in the BDG group compared to the control group 24 h after the infection. As we found with the inhibitor stop method, no change was observed in the group KEG compared to the non-infected group.CONCLUSION: Incubation with the BDG or KEG strains of PRV results in an effective

  13. The method used for justification of engineering solutions for multistage plate-type mufflers attached to gas-air ducts of thermal power plants

    Science.gov (United States)

    Tupov, V. B.

    2013-08-01

    This paper describes technical and economic problems associated with the selection of designs of mufflers attached to gas-air ducts of thermal power plants. A method is suggested that makes it possible to determine the dimensions of each stage of plate-type mufflers on the basis of achieving the lowest total discounted costs in order to provide the required acoustical performance at a permissible aerodynamic resistance of a muffler. The condition of the lowest total discounted costs for a multistage muffler, which is valid for different types of mufflers, has been obtained.

  14. 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.

  15. Extracorporeal shock-wave lithotripsy of bile duct stones

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Tae; Kim, Myung Joon; Yoo, Hyung Sik; Suh, Jung Ho; Lee, Moo Sang; Jo, Jang Hwan; Kim, Byung Ro [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1989-12-15

    During the past one and half year, we performed ESWL therapy in 13 patients with common bile duct and intrahepatic duct stones, applying Lithostar-R (Siemens co. West Germany) and analyzed their results. In 13 patients, 9 residual common bile duct stones and 7 intrahepatic duct stones were selected postoperatively. The size of stones were ranged from 0.7 cm to 3.5 cm in diameter. 2 stones were multiple and the remained 14 were single in number. The visualization of stones were done with fluoroscopy after the injection of contrast media via cholangiographic T-tube or ERCP. ESWL were applied continuously until stone disintegration was visible, or upto maximum number of 3500 discharge of shock wave. If not disintegrated upto 3500, patients were underwent second or third lithotripsy session with interval of one week. Our results showed that among 9 common bile duct stones, 4 were completely disintegrated and passed out spontaneously, but 3 partially fragmented and removed by the additional procedure. 2 were failed. Among 7 intrahepatic stones, 3 completely and 2 partially were succeeded. One stone partially fragmented were retained without removal and other one were failed. Skin petechia in all patients were revealed on the entry port of shock wave, but no serous complication was not occurred.

  16. Sensor-based navigation of air duct inspection mobile robots

    Science.gov (United States)

    Koh, Kyoungchul; Choi, H. J.; Kim, Jae-Seon; Ko, Kuk Won; Cho, Hyungsuck

    2001-02-01

    12 This paper deals with an image sensor system and its position estimation algorithm for autonomous duct cleaning and inspection mobile robots. For the real application, a hierarchical control structure that consists of robot motion controller and image sensor system is designed considering the efficient and autonomous motion behaviors in narrow space such as air ducts. The sensor's system consists of a CCD camera and two laser sources to generate slit beams. The image of the structured lights is used for calculating the geometric parameters of the air ducts which are usually designed with a rectangular section. With the acquired 3D information about the environment, the mobile robot with two differential driving wheels is able to autonomously navigates along the duct path without any human intervention. For real time navigation, the relative position estimation of the robot are performed from 3D image reconstructed by the sensor system. The calibration and image processing methods used for the sensor system are presented with the experimental data. The experimental results show the possibility of the sensor based navigation which is important for effective duct cleaning by small mobile robots.

  17. Measure Guideline: Optimizing the Configuration of Flexible Duct Junction Boxes

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Burdick, A.

    2014-03-01

    This measure guideline offers additional recommendations to heating, ventilation, and air conditioning (HVAC) system designers for optimizing flexible duct, constant-volume HVAC systems using junction boxes within Air Conditioning Contractors of America (ACCA) Manual D guidance (Rutkowski, H. Manual D -- Residential Duct Systems, 3rd edition, Version 1.00. Arlington, VA: Air Conditioning Contractors of America, 2009.). IBACOS used computational fluid dynamics software to explore and develop guidance to better control the airflow effects of factors that may impact pressure losses within junction boxes among various design configurations (Beach, R., Prahl, D., and Lange, R. CFD Analysis of Flexible Duct Junction Box Design. Golden, CO: National Renewable Energy Laboratory, submitted for publication 2013). These recommendations can help to ensure that a system aligns more closely with the design and the occupants' comfort expectations. Specifically, the recommendations described herein show how to configure a rectangular box with four outlets, a triangular box with three outlets, metal wyes with two outlets, and multiple configurations for more than four outlets. Designers of HVAC systems, contractors who are fabricating junction boxes on site, and anyone using the ACCA Manual D process for sizing duct runs will find this measure guideline invaluable for more accurately minimizing pressure losses when using junction boxes with flexible ducts.

  18. 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.

  19. Summary of recent design studies of advanced acoustic-composite nacelles

    Science.gov (United States)

    Norton, H. T., Jr.

    1975-01-01

    The results are summarized of recent NASA-sponsored studies of advanced acoustic-composite nacelles. Conceptual nacelle designs for current wide-bodied transports and for advanced technology transports, intended for operational use in the mid-1980's, were studied by Lockheed-California Company and the Douglas Aircraft Company. These studies were conducted with the objective of achieving significant reductions in community noise and/or fuel consumption with minimum penalties in airplane weights, cost, and operating expense. The results indicate that the use of advanced composite materials offer significant potential weight and cost savings and result in reduced fuel consumption and noise when applied to nacelles. The most promising concept for realizing all of these benefits was a long duct, mixed flow acoustic composite nacelle with advanced acoustic liners.

  20. Acoustic vector sensor signal processing

    Institute of Scientific and Technical Information of China (English)

    SUN Guiqing; LI Qihu; ZHANG Bin

    2006-01-01

    Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on.

  1. Narrow sidebranch arrays for low frequency duct noise control.

    Science.gov (United States)

    Tang, S K

    2012-11-01

    The present study investigates the sound transmission loss across a section of an infinitely long duct where one or more narrow sidebranch tubes are installed flushed with the duct wall. The finite-element method is used to compute the wave propagation characteristics, and a simplified theoretical analysis is carried out at the same time to explain the wave mechanism at frequencies of high sound reduction. Results show that the high sound transmission loss at a particular frequency is due to the concerted actions of three consecutive sidebranch tubes with the most upstream one in the resonant state. The expansion chamber effect of the setup also plays a role in enhancing sound attenuation at non-resonance frequencies. Broadband performance of the device can be greatly enhanced by appropriate arrangements of tube lengths and/or by coupling arrays on the two sides of the duct.

  2. Pancreatic fistula through the distal common bile duct

    Directory of Open Access Journals (Sweden)

    Čolović Radoje B.

    2002-01-01

    Full Text Available Pancreatic fistula is usually caused by acute or chronic pancreatitis, injury and operations of the pancreas. The pancreatic juice comes either from the main pancreatic duct or from side branches. Extremely rare pancreatic fistula may come through the distal end of the common bile duct that is not properly sutured or ligated after traumatic or operative transaction. We present a 58-year old man who developed a life threatening high output pancreatic fistula through the distal end of the common bile duct that was simply ligated after resection for carcinoma. Pancreatic fistula was developed two weeks after original surgery and after two emergency reoperations for serious bleeding from the stump of the right gastric artery resected and ligated during radical limphadenectomy. The patient was treated conservatively by elevation of the drain- age bag after firm tunnel round the drain was formed so that there was no danger of spillage of the pancreatic juice within abdomen.

  3. Biliary endoprostheses in tumors at the hepatic duct bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Lammer, J.; Neumayer, K.; Steiner, H.

    1986-11-01

    In 51 patients with tumors at the hepatic duct bifurcation, endoprostheses were transhepatically inserted into the bile ducts. Patients with Bismuth-3-tumors (i.e. bilateral biliary obstruction) were treated by insertion of 2 or more endoprostheses. Long-term success presumed drainage of all obstructed ducts, because cholangitis has been a common problem secondary to undrained segments. Furthermore the debris and the high viscosity of infected bile increased the risk for obstruction of the endoprostheses, which was observed in 6%. The mean time of survival was 7 months with a maximum of 26 months. In our experience endoprostheses can be used successfully in unresectable Klatskin tumours, which increases the comfort for the patients in their last months of life.

  4. [Minimally-invasive management of common bile duct stones].

    Science.gov (United States)

    Beller, S; Szinicz, G

    2005-02-01

    Common bile duct stones may present a health hazard for our patients. Nevertheless, since the implementation of laparoscopic cholecystectomy optimal diagnostic and therapeutic algorithm are not yet defined. Symptomatic calculi can be assumed on the basis of pathological laboratory values or diagnosed by means of ultrasound, Intraoperative Cholangiography (IOC) or Magnetic-Resonance-Cholangio-Tomography (MRCT). For therapy of common bile duct stones endoscopic and laparoscopic minimally-invasive strategies are available. As any type of management may show some benefit, it is not yet evident which policy we should prefer. Specialists do not agree on the necessity of therapy in asymptomatic patients with common bile duct calculi at all. This article shows a current state of the opinion and art and tends to highlight trends and future perspectives.

  5. Endoscopic pancreatic duct stent placement for inflammatory pancreatic diseases

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The role of endoscopic therapy in the management of pancreatic diseases is continuously evolving; at present most pathological conditions of the pancreas are successfully treated by endoscopic retrograde cholangiopancreatography (ERCP) or endoscopic ultrasound (EUS),or both. Endoscopic placement of stents has played and still plays a major role in the treatment of chronic pancreatitis, pseudocysts, pancreas divisum, main pancreatic duct injuries, pancreatic fistulae, complications of acute pancreatitis, recurrent idiopathic pancreatitis,and in the prevention of post-ERCP pancreatitis. These stents are currently routinely placed to reduce intraductal hypertension, bypass obstructing stones, restore lumen patency in cases with dominant, symptomatic strictures,seal main pancreatic duct disruption, drain pseudocysts or fluid collections, treat symptomatic major or minor papilla sphincter stenosis, and prevent procedure-induced acute pancreatitis. The present review aims at updating and discussing techniques, indications, and results of endoscopic pancreatic duct stent placement in acute and chronic inflammatory diseases of the pancreas.

  6. Papillary carcinoma of the thyroglossal duct cyst: case report.

    Directory of Open Access Journals (Sweden)

    Nasrollah Maleki

    2015-04-01

    Full Text Available Thyroglossal duct cysts are the most common form of congenital cysts on the neck. The incidence of thyroid papillary carcinoma in thyroglossal duct cyst is less than 1%. In most cases the diagnosis is made postoperatively. We present a 22-year-old female with thyroid papillary carcinoma arising from thyroglossal duct cyst,identified in pathologic study after sistrunk operation.In our case there was neither invasion to adjacent tissue nor lymph node involvement.The patient then underwent total thyroidectomy and bilateral neck dissection. The patient was treated with radioactive iodide and thyroid suppression therapy was given as adjuvant treatment.The patient has been following for two years without any metastasis.

  7. 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....

  8. [Postoperative handling in biliodigestive derivation by iatrogenic bile duct injury].

    Science.gov (United States)

    Domínguez, I; Mercado, M A

    2008-01-01

    Bile duct injury is a severe complication related to cholecystectomy, impacting in the long-term quality of life and functional status. Bile duct repair is the first-line treatment for complex injuries. During short-term and long-term postoperative care, it is important to bear in mind the diagnostic tools, both laboratory and imaging, that will be useful to evaluate a possible surgical complication and to plan an adequate therapeutic strategy. In addition, post-surgical classification describes patients according to their complications and clinical course. In this review we describe the principal issues of postoperative care after bile duct repair, highlighting the diagnosis, severity classification and therapeutic approach of acute cholangitis.

  9. 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.

  10. Acoustic comfort in eating establishments

    DEFF Research Database (Denmark)

    Svensson, David; Jeong, Cheol-Ho; Brunskog, Jonas

    2014-01-01

    The subjective concept of acoustic comfort in eating establishments has been investigated in this study. The goal was to develop a predictive model for the acoustic comfort, by means of simple objective parameters, while also examining which other subjective acoustic parameters could help explain...... the feeling of acoustic comfort. Through several layers of anal ysis, acoustic comfort was found to be rather complex, and could not be explained entirely by common subjective parameters such as annoyance, intelligibility or privacy. A predictive model for the mean acoustic comfort for an eating establishment...

  11. Interactions in an acoustic world

    CERN Document Server

    Simaciu, Ion; Borsos, Zoltan; Bradac, Mariana

    2016-01-01

    The present paper aims to complete an earlier paper where the acoustic world was introduced. This is accomplished by analyzing the interactions which occur between the inhomogeneities of the acoustic medium, which are induced by the acoustic vibrations traveling in the medium. When a wave packet travels in a medium, the medium becomes inhomogeneous. The spherical wave packet behaves like an acoustic spherical lens for the acoustic plane waves. According to the principle of causality, there is an interaction between the wave and plane wave packet. In specific conditions the wave packet behaves as an acoustic black hole.

  12. Condensation in jet engine intake ducts during stationary operation

    Energy Technology Data Exchange (ETDEWEB)

    Young, J.B. [Univ. of Cambridge (United Kingdom). Whittle Lab.

    1995-04-01

    The paper describes on analysis of the condensation of moist air in very long intake ducts of jet engines during stationary operation. Problems arising from such condensation include fan over speed and increased stagnation pressure loss in the intake duct. The analysis demonstrates that, for moderate values of relative humidity, homogeneous condensation will occur in an outer annulus adjacent to the intake cowling if the local flow Mach number attains values of about 1.0. In the central region of the intake duct, where design Mach numbers of 0.8 may be attained, homogeneous condensation is unlikely to occur except, possibly, when the relative humidity is close to 100 percent and the ambient temperature very high. However, if the intake duct is very long, significant heterogeneous condensation on foreign particles present in the atmosphere is possible. The concentration of foreign nuclei required for this type of condensation is comparable to the likely levels of contamination at many industrial test sites. The effects of condensation on engine test results are twofold. First, condensation is a thermodynamically irreversible process and results in an increase of entropy and hence loss of total pressure in the intake duct. Uncorrected measurements using Pitot probes may not record this loss correctly. Second, the mass and energy transfer between the phases during the condensation process has a tendency to accelerate the flow approaching the engine, an effect that may be counteracted by a reduction in mass flow rate in order to maintain the static pressure constant. These conclusions are in agreement with experimental results obtained on-site during the testing of a jet engine fitted with a very long intake duct.

  13. Optimal one-section and two-section circular sound-absorbing duct liners for plane-wave and monopole sources without flow

    Science.gov (United States)

    Lester, H. C.; Posey, J. W.

    1976-01-01

    A discrete frequency study is made of the influence of source characteristics on the optimal properties of acoustically lined uniform and two section ducts. Two simplified sources, a plane wave and a monopole, are considered in some detail and over a greater frequency range than has been previously studied. Source and termination impedance effects are given limited examination. An example of a turbomachinery source and three associated source variants is also presented. Optimal liner designs based on modal theory approach the Cremer criterion at low frequencies and the geometric acoustics limit at high frequencies. Over an intermediate frequency range, optimal two section liners produced higher transmission losses than did the uniform configurations. Source distribution effects were found to have a significant effect on optimal liner design, but source and termination impedance effects appear to be relatively unimportant.

  14. Entropy analysis of pressure driven flow in a curved duct

    Science.gov (United States)

    Narla, V. K.; Jaliparthi, Vijayasekhar

    2017-07-01

    This paper aims to present a theoretical model describing entropy generation analysis using second law of thermodynamics. A two-dimensional, incompressible, viscous MHD fluid flow in a curved duct undergoing peristalsis with prescribed wall motions in the presence of heat transfer is applied and demonstrated. In this problem, It is assumed that the inertial effect is very small and the wall wave length is comparatively large with duct width. The velocity and temperature fields are obtained analytically by solving momentum and energy equations. The entropy generation number is calculated by utilizing velocity and temperature profiles. The influence of various physical parameters on entropy generation are discussed numerically with the help of graphs.

  15. 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.

  16. 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

  17. Common bile duct stones: analysis of the videolaparoscopic surgical treatment.

    Science.gov (United States)

    Santo, Marco Aurelio; Domene, Carlos Eduardo; Riccioppo, Daniel; Barreira, Lian; Takeda, Flavio Roberto; Pinotti, Henrique Walter

    2012-01-01

    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. To evaluate the results and outcomes of the laparoscopic treatment of common bile duct lithiasis. 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). 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 primary, the necessity for choledochoscopy through

  18. 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......-axisymmetric excitation is important (spinning modes). In addition the model allows the duct to be partially or fully treated with an axisymmetric locally reacting liner. Results determined with the model are compared with results from the literature and results calculated with an analytic model....

  19. Whistler propagation in ionospheric density ducts: Simulations and DEMETER observations

    Science.gov (United States)

    Woodroffe, J. R.; Streltsov, A. V.; Vartanyan, A.; Milikh, G. M.

    2013-11-01

    On 16 October 2009, the Detection of Electromagnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite observed VLF whistler wave activity coincident with an ionospheric heating experiment conducted at HAARP. At the same time, density measurements by DEMETER indicate the presence of multiple field-aligned enhancements. Using an electron MHD model, we show that the distribution of VLF power observed by DEMETER is consistent with the propagation of whistlers from the heating region inside the observed density enhancements. We also discuss other interesting features of this event, including coupling of the lower hybrid and whistler modes, whistler trapping in artificial density ducts, and the interference of whistlers waves from two adjacent ducts.

  20. A numerical investigation of primary surface rounded cross wavy ducts

    Science.gov (United States)

    Utriainen, E.; Sundén, B.

    A three-dimensional numerical study was conducted to assess the hydraulic and heat transfer performance of primary surface type heat exchanger surfaces, called cross wavy (CW) ducts aimed for recuperators. The governing equations, i.e., the mass conservation equation, Navier-Stokes equations and the energy equation, are solved numerically by a finite volume method for boundary fitted coordinates. Periodic boundary conditions are imposed in the main flow direction. In this particular case laminar convective flow and heat transfer prevail. Details of the recuperator ducts and the numerical method as well as relevant results are presented.

  1. Ursodeoxycholic acid treatment of vanishing bile duct syndromes

    Institute of Scientific and Technical Information of China (English)

    Thomas Pusl; Ulrich Beuers

    2006-01-01

    Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC, and anticholestatic effects have been reported for several other cholestatic syndromes. Several potential mechanisms of action of UDCA have been proposed including stimulation of hepatobiliary secretion, inhibition of apoptosis and protection of cholangiocytes against toxic effects of hydrophobic bile acids.

  2. 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.

  3. 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.

  4. 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.

  5. 103Pd radioactive stent inhibits biliary duct restenosis and reduces smooth muscle actin expression during duct healing in dogs

    Institute of Scientific and Technical Information of China (English)

    Gui-Jin He; Qin-Yi Gao; Shu-He Xu; Hong Gao; Tao Jiang; Xian-Wei Dai; Kai Ma

    2006-01-01

    BACKGROUND: This study was designed to assess the expression of smooth muscle actin (SMA) in the healing process after implanting a 103Pd radioactive stent in the biliary duct, and to discuss the function and signiifcance of this stent in preventing biliary stricture formation. METHODS:A model of biliary injury in dogs was made and then a 103Pd radioactive stent was positioned in the biliary duct. The expression and distribution of SMA were assessed in the anastomotic tissue 30 days after implantation of the stent. RESULTS:SMA expression was less in the 103Pd stent group than in the ordinary stent group. The 103Pd stent inhibited scar contracture and anastomotic stenosis. CONCLUSION:The 103Pd stent can reduce the expression of SMA in the healing process and inhibit scar contracture and anastomotic stenosis in the dog biliary duct.

  6. 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.

  7. ASSESSMENT OF FUNGAL (PENICILLIUM CHRYSOGENUM) GROWTH ON THREE HVAC DUCT MATERIALS

    Science.gov (United States)

    The article discusses laboratory experiments to evaluate the susceptibility of three ventilation duct materials (fibrous glass ductboard, galvanized steel, and insulated flexible duct) to fungal (P. chrysogenum) growth. [NOTE: Many building investigators have documented fungal bi...

  8. 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.

  9. Decline of the performance of a portable axial-flow fan due to the friction and duct bending loss of a connected flexible duct.

    Science.gov (United States)

    Ojima, Jun

    2017-03-28

    In a job site, a portable fan is often used to ventilate a confined space. When a portable fan is applied to such a space, the actual ventilation flow rate must be accurately estimated in advance because the safety level of contaminant and oxygen concentrations in the space will determine the ventilation requirements. When a portable fan is used with a flexible duct, the actual flow rate of the fan decreases due to the friction and duct bending loss of the duct. Intending to show the decline of a fan performance, the author conducted laboratory experiments and reported the quantitative effect of the friction and duct bending loss of a flexible duct to the flow rate of a portable fan. Four commercial portable fans of different specifications were procured for the experiments, and the decline of the performance of each portable fan due to the friction loss etc. of a connected flexible duct was investigated by measuring actual flow rate. The flow rate showed an obvious decrease from the rated flow rate when a flexible duct was connected. Connection of a straight polyester flexible duct and a straight aluminum flexible duct reduced the flow rates to 81.2 - 52.9% and less than 50%, respectively. The flow rate decreased with an increase of the bend angle of the flexible duct. It is recommended that flow rate check of a portable fan should be diligently carried out in every job site.

  10. High-frequency seafloor acoustics

    National Research Council Canada - National Science Library

    Jackson, D. R; Richardson, M. D

    2007-01-01

    This title provides access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics...

  11. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....

  12. Advanced Active Acoustics Lab (AAAL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Active Acoustics Lab (AAAL) is a state-of-the-art Undersea Warfare (USW) acoustic data analysis facility capable of both active and passive underwater...

  13. 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.

  14. 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.

  15. Acoustic detection of pneumothorax

    Science.gov (United States)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (ppneumothorax states (pPneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (pPneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  16. Passive broadband acoustic thermometry

    Science.gov (United States)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  17. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  18. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  19. Acoustics of courtyard theatres

    Institute of Scientific and Technical Information of China (English)

    WANG Jiqing

    2008-01-01

    The traditional Chinese theatre was often built with a courtyard. In such open-top space, the absence of a roof would mean little reverberation and non-diffused sound field.Acoustically the situation is quite different from that of any enclosed space. The refore, theclassic room acoustics, such as Sabine reverberation formula, would no longer be applicable due to the lack of sound reflections from the ceiling. As the parameter of reverberation time T30 shows the decay rate only, it would not properly characterize the prominent change in the fine structure of the echogram, particularly in case of a large reduction of reflections during the decay process. The sense of reverbrance in a courtyard space would differ noticeably from that of the equivalent 3D-T30 in an enclosed space. Based upon the characteristic analysis of the sound field in an open-top space, this paper presents a preliminary study on the acoustics of the courtyard theatres.

  20. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  1. 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...

  2. Acoustic classification of dwellings

    DEFF Research Database (Denmark)

    Berardi, Umberto; Rasmussen, Birgit

    2014-01-01

    insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...... of descriptors, number of classes, and class intervals occurred between national schemes. However, a proposal “acoustic classification scheme for dwellings” has been developed recently in the European COST Action TU0901 with 32 member countries. This proposal has been accepted as an ISO work item. This paper...

  3. Room Acoustical Fields

    CERN Document Server

    Mechel, Fridolin

    2013-01-01

    This book presents the theory of room acoustical fields and revises the Mirror Source Methods for practical computational use, emphasizing the wave character of acoustical fields.  The presented higher methods include the concepts of “Mirror Point Sources” and “Corner sources which allow for an excellent approximation of complex room geometries and even equipped rooms. In contrast to classical description, this book extends the theory of sound fields describing them by their complex sound pressure and the particle velocity. This approach enables accurate descriptions of interference and absorption phenomena.

  4. Acoustic black holes

    CERN Document Server

    Visser, M

    1999-01-01

    Acoustic propagation in a moving fluid provides a conceptually clean and powerful analogy for understanding black hole physics. As a teaching tool, the analogy is useful for introducing students to both General Relativity and fluid mechanics. As a research tool, the analogy helps clarify what aspects of the physics are kinematics and what aspects are dynamics. In particular, Hawking radiation is a purely kinematical effect, whereas black hole entropy is intrinsically dynamical. Finally, I discuss the fact that with present technology acoustic Hawking radiation is almost experimentally testable.

  5. Do We Know What Causes Bile Duct Cancer?

    Science.gov (United States)

    ... whether it’s bile duct stones, infestation with a parasite, or something else. Scientists are starting to understand how inflammation might lead to certain changes in the DNA of cells, making them grow abnormally and form cancers. DNA is the chemical in each of our ...

  6. Experimental study on the particles deposition in the sampling duct

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Charuau, J. [Institut de Protection et de Surete Nucleaire, Yvette (France)

    1995-02-01

    A high standard of protection against the harmful effects of radioactive aerosol dissemination requires a measurement, as representative as possible, of their concentration. This measurement depends on the techniques used for aerosol sampling and transfer to the detector, as well as on the location of the latter with respect to the potential sources. The aeraulic design of the apparatus is also an important factor. Once collected the aerosol particles often have to travel through a variably shaped duct to the measurement apparatus. This transport is responsible for losses due to the particles deposition on the walls, leading to a distortion on the concentration measurements and a change in the particle size distribution. To estimate and minimize measurement errors it is important to determine the optimal transport conditions when designing a duct; its diameter and material, the radius of curvature of the bends and the flow conditions must be defined in particular. This paper presents an experimental study in order to determine, for each deposition mechanism, the retained fraction, or the deposition velocity for different flow regimes. This study has pointed out that it exists a favourable flow regime for the particle transport through the sampling ducts (2 500 < Re < 5 000). It has been established, for any particle diameters, equations to predict the aerosol penetration in smooth-walled cylindrical metal ducts.

  7. 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…

  8. Benign Pancreatic Duct Strictures: Medical and Endoscopic Therapy

    Directory of Open Access Journals (Sweden)

    JE Geenen

    2000-01-01

    Full Text Available Pancreatic duct strictures usually reflect underlying pancreatic disease and are likely caused by one or more of the following: acute or chronic pancreatitis, benign or malignant pancreatic neoplasm, pseudocyst and trauma. The characteristics of pancreatic strictures are identified, and medical and endoscopic therapy options are reviewed.

  9. Effect of lining anisotropy on sound attenuation in lined ducts

    Science.gov (United States)

    Kim, Jeong-Woo; Bolton, J. Stuart; Alexander, Jonathan H.

    2005-09-01

    In this paper, the effect of duct-lining anisotropy, with respect to flow resistivity, in particular, is considered. The duct lining is modeled by using a fully poroelastic theory derived from the Biot theory. The lining is considered to occupy only a part of the duct cross section, and is imagined to be infinite in length. When the appropriate solutions for the sound fields within the airway and the anisotropic porous material are substituted into the boundary conditions of the problem, a homogeneous system of equations results. The propagation characteristics of the duct modes can then be found by identifying the conditions under which the determinant of that system of equations is zero. Corresponding experiments have been conducted using samples of aviation-grade glass fiber partially lining a square-section, four-microphone standing wave tube. Excellent agreement between measured attenuations and predictions was found. It will be shown that the modal attenuation is primarily sensitive to the flow resistivity of the lining in the axial direction.

  10. Two phase flow combustion modelling of a ducted rocket

    NARCIS (Netherlands)

    Stowe, R.A.; Dubois, C.; Harris, P.G.; Mayer, A.E.H.J.; Champlain, A. de; Ringuette, S.

    2001-01-01

    Under a co-operative program, the Defence Research Establishment Valcartier and Université Laval in Canada and the TNO Prins Maurits Laboratory in the Netherlands have studied the use of a ducted rocket for missile propulsion. Hot-flow direct-connect combustion experiments using both simulated and s

  11. 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.

  12. 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.

  13. Design curves for circular and annular duct silencers

    Science.gov (United States)

    Watson, Willie R.; Ramakrishnan, R.

    1989-01-01

    Conventional models of sound propagation between porous walls (Scott, 1946) are adapted in order to calculate design curves for the lined circular and annular-duct silencers used in HVAC systems. The derivation of the governing equations is outlined, and results for two typical cases are presented graphically. Good agreement with published experimental data is demonstrated.

  14. 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...

  15. Heuristic approach to the passive optical network with fibre duct ...

    African Journals Online (AJOL)

    This paper uses concepts from network flow optimisation to incorporate fibre duct shar- .... Steiner tree T rooted in c so as to minimise the overall deployment cost .... sharing exist at road junctions where fibres can be routed together on one ...

  16. A visual pitfall: persistent Mullerian duct syndrome (PMDS).

    NARCIS (Netherlands)

    Marcus, K.A.; Halbertsma, F.J.; Picard, J.Y.; Otten, B.J.

    2008-01-01

    Persistent Mullerian Duct Syndrome (PMDS) is a rare disorder of the anti-mullerian hormone (AMH) synthesis or receptor, which due to the visual contrast of normal masculine external genitalia and female internal genitalia can raise confusion, sometimes during surgery for cryptorchidism or hernia ing

  17. [Experimental microendoscopy of the milk duct system (ductoscopy)].

    Science.gov (United States)

    Rimbach, S; Wallwiener, D; Fein, A; von Fournier, D; Bastert, G

    1995-01-01

    According to recent reports, the microendoscopic lactiferous duct investigation (ductoscopy) could improve diagnosis in case of pathological nipple discharge. However, the description of a reproducible and reliable methodology, suitable for thorough evaluation of the lactiferous duct is missing so far. Therefore, the pressure study developed a procedure, that may serve now as an experimental basis for further clinical evaluation. Access to the mamillary duct is primarily gained using atraumatic flexible teflon catheters. Corresponding to the diameter of the duct, either a semirigid 0.87 mm fiberendoscope can be successfully introduced via a 1.2 mm catheter, or a flexible 0.50 mm fiberendoscope via a 1.0 mm catheter. A controlled distension using few milliliters of ringer's lactate is the prerequisite for clear visualization of the intraductal space and protection against iatrogenic wall lesions. Metal microtocars are available as prototypes. They carry a somewhat higher risk to perforate, but are advantageous when pointing at an intraductal structure and using the microtrocar as a mark for microdochectomy.

  18. Predicting Turbulent Convective Heat Transfer in Fully Developed Duct Flows

    Science.gov (United States)

    Rokni, Masoud; Gatski, Thomas B.

    2001-01-01

    The performance of an explicit algebraic stress model (EASM) is assessed in predicting the turbulent flow and forced heat transfer in both straight and wavy ducts, with rectangular, trapezoidal and triangular cross-sections, under fully developed conditions. A comparison of secondary flow patterns. including velocity vectors and velocity and temperature contours, are shown in order to study the effect of waviness on flow dynamics, and comparisons between the hydraulic parameters. Fanning friction factor and Nusselt number, are also presented. In all cases. isothermal conditions are imposed on the duct walls, and the turbulent heat fluxes are modeled using gradient-diffusion type models. The formulation is valid for Reynolds numbers up to 10(exp 5) and this minimizes the need for wall functions that have been used with mixed success in previous studies of complex duct flows. In addition, the present formulation imposes minimal demand on the number of grid points without any convergence or stability problems. Criteria in terms of heat transfer and friction factor needed to choose the optimal wavy duct cross-section for industrial applications among the ones considered are discussed.

  19. Purinoceptors Evoke Different Electrophysiological Responses in Pancreatic Ducts

    DEFF Research Database (Denmark)

    Hede, S E; Amstrup, Jan; Christoffersen, Bettina C

    1999-01-01

    In epithelia, extracellular nucleotides are often associated with regulation of ion transporters, especially Cl(-) channels. In this study, we investigated which purinoceptors are present in native pancreatic ducts and how they regulate ion transport. We applied whole-cell patch-clamp recordings,...

  20. Reynolds-stress model prediction of 3-D duct flows

    CERN Document Server

    Gerolymos, G A

    2014-01-01

    The paper examines the impact of different modelling choices in second-moment closures by assessing model performance in predicting 3-D duct flows. The test-cases (developing flow in a square duct [Gessner F.B., Emery A.F.: {\\em ASME J. Fluids Eng.} {\\bf 103} (1981) 445--455], circular-to-rectangular transition-duct [Davis D.O., Gessner F.B.: {\\em AIAA J.} {\\bf 30} (1992) 367--375], and \\tsn{S}-duct with large separation [Wellborn S.R., Reichert B.A., Okiishi T.H.: {\\em J. Prop. Power} {\\bf 10} (1994) 668--675]) include progressively more complex strains. Comparison of experimental data with selected 7-equation models (6 Reynolds-stress-transport and 1 scale-determining equations), which differ in the closure of the velocity/pressure-gradient tensor $\\Pi_{ij}$, suggests that rapid redistribution controls separation and secondary-flow prediction, whereas, inclusion of pressure-diffusion modelling improves reattachment and relaxation behaviour.

  1. Laparoscopic managment of common bile duct stones: our initial experience.

    Science.gov (United States)

    Aroori, S; Bell, J C

    2002-05-01

    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.

  2. An acoustic window for sustainable buildings

    Science.gov (United States)

    Kang, Jian; Brocklesby, Martin; Li, Zhemin; Oldham, David J.

    2005-04-01

    Encouraging the use of natural ventilation is an important tendency in the green building movement, but opening windows can often cause noise problems. This research develops a window system which allows natural ventilation while reducing noise transmission. The core idea is to create a ventilation path by staggering two layers of glass and using micro-perforated absorbers (MPA) along the path created to reduce noise. The MPA are made from transparent materials so that daylighting is relatively unaffected. Starting with a brief introduction of the MPA theory and its application in ducts, the paper presents a series of numerical simulations using finite element method based software FEMLAB, and experiment results measured between a semi-anechoic chamber and a reverberation chamber. Performance in acoustics, ventilation and daylighting are all taken into account. A basic window configuration is first considered, studying the effectiveness of various window parameters. A number of strategic designs are then examined, including external hoods and louvers in the sound path. There is generally a good agreement between simulation and measurement, and the noise reduction can be as good as a single glazing, with air movement to achieve occupant comfort, rather than just for minimum air exchange. [Work supported by EPSRC.

  3. Broadband asymmetric acoustic transmission through an acoustic prism

    Science.gov (United States)

    Song, Ailing; Chen, Tianning; Wang, Xiaopeng; Xi, Yanhui

    2017-08-01

    Narrow bandwidth and complex structure are the main shortcomings of the existing asymmetric acoustic transmission devices. In this letter, a simple broadband asymmetric acoustic transmission device is proposed by using an acoustic prism filled with xenon gas. The sound pressure field distributions, the transmission spectra, and the prism angle effect are numerically investigated by using finite element method. The proposed device can always realize asymmetric acoustic transmission for the wave frequency larger than 480 Hz because the wave paths are not influenced by the wave frequencies. The asymmetric acoustic transmission is attributed to normal refraction and total reflection occur at different interfaces. Besides, relatively high transmission efficiency is realized due to the similar impedance between the acoustic prism and background. And the transmitted wave direction can be controlled freely by changing the prism angle. Our design provides a simple method to obtain broadband asymmetric acoustic transmission device and has potentials in many applications, such as noise control and medical ultrasound.

  4. Isolated segmental, sectoral and right hepatic bile duct injuries

    Institute of Scientific and Technical Information of China (English)

    Radoje B Colovic

    2009-01-01

    The treatment of isolated segmental, sectoral and right hepatic bile duct injuries is controversial. Nineteen patients were treated over a 26-year period. Group one was comprised of 4 patients in whom the injury was primarily repaired during the original surgery;3 over a T-tube, 1 with a Roux-en-Y. These patients had an uneventful recovery. The second group consisted of 5 patients in whom the duct was ligated;4 developed infection, 3 of which required drainage and biliary repair. Two patients had good long-term outcomes;the third developed a late anastomotic stricture requiring further surgery. The fourth patient developed a small bile leak and pain which resolved spontaneously. The fifth patient developed complications from which he died. The third group was comprised of 4 patients referred with biliary peritonitis;all underwent drainage and lavage, and developed biliary fistulae, 3 of which resolved spontaneously, 1 required Roux-en-Y repair, with favorable outcomes. The fourth group consisted of 6 patients with biliary fistulae. Two patients, both with an 8-wk history of a fistula, underwent Roux-en-Y repair. Two others also underwent a Roux-en-Y repair, as their fistulae showed no signs of closure. The remaining 2 patients had spontaneous closure of their biliary fistulae. A primary repair is a reasonable alternative to ligature of injured duct. Patients with ligated ducts may develop complications. Infected ducts require further surgery. Patients with biliary peritonitis must be treated with drainage and lavage. There is a 50% chance that a biliary fistula will close spontaneously. In cases where the biliary fistula does not close within 6 to 8 wk, a Roux-en-Y anastomosis should be considered.

  5. Modal Analysis in Lined Wedge-Shaped Ducts

    Science.gov (United States)

    Mechel, F. P.

    1998-10-01

    It has been suggested to describe the sound field in a wedge-shaped duct in a cylindrical co-ordinate system in which the boundaries of the wedge lie in a co-ordinate surface. This suggestion was developed in a companion paper [1]. The wave equation can be separated only if the boundaries are ideally reflecting (rigid or soft). Two solutions were proposed in reference [1] for absorbing boundaries. In the first solution the sound field is composed of “ideal modes” (modes in a wedge with ideally reflecting boundaries); the boundary condition at the absorbing boundary then leads to a system of equations for the mode amplitudes. The problem with this method lies in the fact that there is no radial orthogonality of the ideal modes so that the precision of the field synthesis by ideal modes is doubtful. In the second method in reference [1] one defines “fictitious modes” which satisfy the boundary conditions at the flanks exactly and which are based on hypergeometric functions as radial functions, but which produce a “rest” in the wave equation. It was described how this rest can be minimized; this procedure leads to slow numerical integrations. In the present paper, the wedge is subdivided into duct sections with parallel walls (the boundary is stepped); the fields in the sections are composed of duct modes (modes in a straight lined duct); the mode amplitudes are determined from the boundary conditions at the section limits. The advantages of the present method are (analytically) the duct modes are orthogonal across the sections, so the mode amplitudes can be determined with the usual precision of a modal analysis, and (numerically) no numerical integrations are needed.

  6. Current perspective in the treatment of bile duct injuries

    Directory of Open Access Journals (Sweden)

    Juan Jos and eacute; Granados-Romero

    2016-03-01

    Full Text Available The laparoscopic cholecystectomy is considered the gold standard for the treatment of benign gallbladder disease, which is associated with an increased incidence of biliary injuries. These types of injuries are multicausal, and anatomical variations or anatomical perception errors are the most common risk factors. The objective of this study is to describe the evolution in the management of bile duct injuries and actual, diagnostic tools, incidence, prognosis and treatment. A literature research about diagnosis and treatment of iatrogenic bile duct injuries as well as their impact on the incidence of morbidity and mortality, based on a 30-year period, was performed on Medline, Cochrane, Embase, MedScape and PubMed database, for all studies that met the eligibility criteria. A thorough quality assessment of all included studies was performed. Synthesis of the results was achieved by narrative review. The bile duct injury is a complication that requires a complex therapy and multidisciplinary management. Reconstruction and treatment techniques have been evolving. The selection of adequate treatment will impact on the patient and acute;s quality of life. The results of the existing studies reporting on iatrogenic bile duct injuries are useful; because the iatrogenic bile duct injuries are complex alterations and constitute one of the most serious complications of a cholecystectomy and require a comprehensive approach, immediate repair, proper drainage and timely referral to adequate treatment to improve long-term prognosis. According to the literature review, currently there better treatments such as absorbable prosthesis, which improve the prognosis and patient and acute;s quality of life, and represent less risk of complications in short/long term. [Int J Res Med Sci 2016; 4(3.000: 677-684

  7. Papillary carcinoma in a thyroglossal duct: case report

    Directory of Open Access Journals (Sweden)

    Antonio Santos Martins

    1999-11-01

    Full Text Available CONTEXT: Thyroglossal duct cysts are the most common congenital cervical abnormality in childhood. Malignant lesions are rare in thyroglossal duct cysts (about 1%. OBJECTIVE: To report a case of papillary carcinoma in thyroglossal duct cysts. DESIGN: Case report. CASE REPORT: The patient was a 21-year-old female with a four-month history of an anterior midline neck mass but without other symptoms. The physical examination revealed a 4.0 cm diameter, smooth, painless, cystic nodule at the level of the hyoid bone. The thyroid gland was normal by palpation and no neck lymph nodes were found. Indirect laryngoscopy, fine-needle biopsy aspiration and cervical ultrasound were normal and compatible with the physical findings of a thyroglossal duct cyst. The patient underwent surgery with this diagnosis, under general anesthesia, and the mass was resected by the usual Sistrunk procedure. There were no local signs of invasion of the tissue surrounding the cyst or duct at surgery. The patient was discharged within 24 hours. Histopathological examination of the specimen showed a 3.5 x 3.0 x 3.0 cm thyroglossal cyst, partially filled by a solid 1.0 x 0.5 cm brownish tissue. Histological sections showed a papillary carcinoma in the thyroid tissue of a thyroglossal cyst, with normal thyroid tissue at the boundary of the carcinoma. There was no capsule invasion and the margins were negative. The follow-up of the patient consisted of head and neck examinations, ultrasonography of the surgical region and thyroid, and total body scintigraphy. The patient has been followed up for two years with no further evidence of disease.

  8. The design and development of an automatic control system for the in-duct cancellation of spinning modes of sound. M.S. Thesis

    Science.gov (United States)

    Harrington, W. W.

    1973-01-01

    The reduction is discussed of the discrete tones generated by jet engines which is essential for jet aircraft to meet present and proposed noise standards. The discrete tones generated by the blades and vanes propagate in the inlet and exhaust duct in the form of spiraling acoustic waves, or spinning modes. The reduction of these spinning modes by the cancellation effect of the combination of two acoustic fields was investigated. The spinning mode synthesizer provided the means for effective study of this noise reduction scheme. Two sets of electrical-acoustical transducers located in an equally-spaced circular array simultaneously generate a specified spinning mode and the cancelling mode. Analysis of the wave equation for the synthesizer established the optimum cancelling array acoustic parameters for maximum sound pressure level reduction. The parameter dependence of the frequency ranges of propagation of single, specified circumferential modes generated by a single array, and of effective cancellation of the modes generated by two arrays, was determined. Substantial sound pressure level reduction was obtained for modes within these limits.

  9. Lhx1 is required in Müllerian duct epithelium for uterine development.

    Science.gov (United States)

    Huang, Cheng-Chiu; Orvis, Grant D; Kwan, Kin Ming; Behringer, Richard R

    2014-05-15

    The female reproductive tract organs of mammals, including the oviducts, uterus, cervix and upper vagina, are derived from the Müllerian ducts, a pair of epithelial tubes that form within the mesonephroi. The Müllerian ducts form in a rostral to caudal manner, guided by and dependent on the Wolffian ducts that have already formed. Experimental embryological studies indicate that caudal elongation of the Müllerian duct towards the urogenital sinus occurs in part by proliferation at the ductal tip. The molecular mechanisms that regulate the elongation of the Müllerian duct are currently unclear. Lhx1 encodes a LIM-homeodomain transcription factor that is essential for male and female reproductive tract development. Lhx1 is expressed in both the Wolffian and Müllerian ducts. Wolffian duct-specific knockout of Lhx1 results in degeneration of the Wolffian duct and consequently the non-cell-autonomous loss of the Müllerian duct. To determine the role of Lhx1 specifically in the Müllerian duct epithelium, we performed a Müllerian duct-specific knockout study using Wnt7a-Cre mice. Loss of Lhx1 in the Müllerian duct epithelium led to a block in Müllerian duct elongation and uterine hypoplasia characterized by loss of the entire endometrium (luminal and glandular epithelium and stroma) and inner circular but not the outer longitudinal muscle layer. Time-lapse imaging and molecular analyses indicate that Lhx1 acts cell autonomously to maintain ductal progenitor cells for Müllerian duct elongation. These studies identify LHX1 as the first transcription factor that is essential in the Müllerian duct epithelial progenitor cells for female reproductive tract development. Furthermore, these genetic studies demonstrate the requirement of epithelial-mesenchymal interactions for uterine tissue compartment differentiation.

  10. Identification and treatment of variation of extrahepatic bile duct in laparoscopic cholecystectomy

    Directory of Open Access Journals (Sweden)

    PENG Lei

    2015-10-01

    Full Text Available ObjectiveTo investigate the identification and treatment of variation of extrahepatic bile duct in laparoscopic cholecystectomy (LC, and to reduce the occurrence of bile duct injury. MethodsThis study included 60 patients who received LC in the People′s Hospital of Caidian District in Wuhan and had structural variation of extrahepatic bile duct found during the operation from January 2012 to January 2014. The clinical data were retrospectively analyzed, and the intraoperative and postoperative conditions were summarized. ResultsDuring operation, cystic duct variation was found in 32 cases, abnormal position of the point where the cystic duct joins the extrahepatic bile duct in 20 cases, the cystic duct and the common hepatic duct having the common wall before joining the common bile duct in 2 cases, aberrant bile duct in the gallbladder bed in 2 cases, and accessory hepatic duct in 4 cases. Fifty-one patients (85% successfully underwent LC; 9 patients (15% were converted to open surgery. All patients finished surgery successfully. There were 2 cases of postoperative complications; one patient developed residual stones in the bile duct, and bile leakage occurred in the other patient at one week after LC, who recovered after reoperation. All patients were cured and discharged, without severe complications such as intraperitoneal hemorrhage, infection, and intestinal injury. ConclusionIdentifying the structural variation of extrahepatic bile duct, dissecting the Calot′s triangle meticulously, and determining the type of variation of extrahepatic bile duct play important roles in LC and significantly reduce the incidence of bile duct injury.

  11. Parametric measurements of the effect of in-duct orifice edge shape on its noise damping performance

    Science.gov (United States)

    Ji, Chenzhen; Zhao, Dan; Han, Nuomin; Li, Jing

    2016-12-01

    Acoustic liners perforated with thousands of millimeter-size orifices are widely used in aero-engines and gas turbine engines as an effective noise damper. In this work, experimental investigations of the acoustic damping effect of in-duct perforated orifices are performed on a cold-flow pipe. A mean flow (also known as bias flow) is applied and its flow rate is variable. Emphasis is placed on the effect of the orifice edge shape. For this, 16 in-duct orifices with different edge shapes and porosities are designed and manufactured by using 3D printing technology and conventional laser cutting technique. The damping effect of these in-duct orifices is characterized by using power absorption coefficient Δ and reflection coefficient χ from 100 to 1000 Hz. The performances of these orifices are found to be either improved or deteriorated, depending on (1) edge shape, (2) the ratio T/d of orifice thickness to its diameter, (3) the bias flow Mach number, (4) downstream pipe length Ld and (5) porosity η via varying either the number N or surface area Ao of the orifices. In addition, modifying orifice edge does not lead to an increase of power absorption at lower frequency (⩽ 700 Hz). However, as the frequency is increased, the orifice with square (S-type) edge is found to be associated with 10 percent more power absorption. It is interesting to find that T/d over the tested range (≤ 0.5) has little influence on its damping capacity. However, the mean bias flow Mach number Ma and porosity η are shown to play critical roles on determining the noise damping performance of these orifices. Maximum power absorption Δmax is found to occur at Ma ≈ 0.018, while the optimum porosity corresponding to Δmax is approximately 7 percent. The present parametric measurements shed light on the roles of orifice edge shape, porosity and mean flow on its noise damping capacity, and facilitate the design of effective perforated liners.

  12. ß-adrenergic regulation of ion transport in pancreatic ducts: Patch-clamp study of isolated rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I

    1998-01-01

    BACKGROUND & AIMS: In the intact pancreas, bicarbonate secretion is thought to be controlled by a number of regulators, including adrenergic agonists. The aim of this study was to investigate the effects of adrenergic agonists on pancreatic ducts, which are the site of bicarbonate secretion. METH...

  13. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has onl...

  14. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-08-03

    Award No.: N00014-14-C-0172 Report No. QSR-14C0172-Ocean Acoustics-063016 Prepared for: Office of Naval Research For the period: April 1...The source level in this overlay is a free parameter (but is estimated to be ~215 dB) re 1uPa2/m2). This agreement is exceptional. It shows the dip

  15. Indigenous Acoustic Detection.

    Science.gov (United States)

    1982-01-26

    considerable distances, and they act as good sensors of human presence. Though singing insects are ubiquitous in warm areas, even in the desert ( Nevo and...methodology. DTIC. CD-58-PL. Lloyd, J. E. 1981. Personnel communication. Nevo , E. and S. A. Blondheim. 1972. Acoustic isolation in the speciation of

  16. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  17. Deep Water Ocean Acoustics

    Science.gov (United States)

    2015-04-15

    sound speed profile is range-independent; since there is little expectation there will be significant mesoscale phenomenon given the lack of solar ...34 Journal of the Acoustical Society of America 93 (4), 1736-1742 (1993). 2 Chris H. Harrison and Martin Siderius, "Effective Parameters for Matched

  18. Underwater Acoustic Networking Techniques

    CERN Document Server

    Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele

    2012-01-01

    This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

  19. Vibroacoustic modeling of an acoustic resonator tuned by dielectric elastomer membrane with voltage control

    Science.gov (United States)

    Yu, Xiang; Lu, Zhenbo; Cheng, Li; Cui, Fangsen

    2017-01-01

    This paper investigates the acoustic properties of a duct resonator tuned by an electro-active membrane. The resonator takes the form of a side-branch cavity which is attached to a rigid duct and covered by a pre-stretched Dielectric Elastomer (DE) in the neck area. A three-dimensional, analytical model based on the sub-structuring approach is developed to characterize the complex structure-acoustic coupling between the DE membrane and its surrounding acoustic media. We show that such resonator provides sound attenuation in the medium frequency range mainly by means of sound reflection, as a result of the membrane vibration. The prediction accuracy of the proposed model is validated against experimental test. The pre-stretched DE membrane with fixed edges responds to applied voltage change with a varying inner stress and, by the same token, its natural frequency and vibrational response can be tuned to suit particular frequencies of interest. The peaks in the transmission loss (TL) curves can be shifted towards lower frequencies when the voltage applied to the DE membrane is increased. Through simulations on the effect of increasing the voltage level, the TL shifting mechanism and its possible tuning range are analyzed. This paves the way for applying such resonator device for adaptive-passive noise control.

  20. Acoustic hygrometer. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Shakkottai, P.; Kwack, E.Y.

    1998-02-02

    The water vapor content for air in drier ducts, ovens, furnaces and the like is determined by a measurement of sound speed which is done by measuring the time difference between sound pulses reflected by two reflectors spaced a known distance apart in a guide tube. The transmitter-receiver is located at one end of the tube. The tube has enough number of holes to allow the hot moist air to get into the probe tube. A non-porous tube containing dry air placed in the same duct provides a similar measurement of dry-sound speed. The ratio of the two speeds of sound or the two measured time intervals is a simple function of the water vapor content practically independent of temperature thereby providing a very accurate measurement of water vapor content over an extremely wide range of temperatures. The sensor is accurate, immune to harsh environments, has an extremely low time constant, has absolutely no hysteresis and needs no calibration.