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Sample records for complex duct simulating

  1. Complex bile duct injuries: management

    PubMed Central

    Ardiles, V.; Pekolj, J.

    2008-01-01

    Background. Laparoscopic cholecystectomy is the present treatment of choice for patients with gallbladder stones, despite its being associated with a higher incidence of biliary injuries compared with the open procedure. Injuries occurring during the laparoscopic approach seem to be more complex. A complex biliary injury is a disease that is difficult to diagnose and treat. We considered complex injuries: 1) injuries that involve the confluence; 2) injuries in which repair attempts have failed; 3) any bile duct injury associated with a vascular injury; 4) or any biliary injury in association with portal hypertension or secondary biliary cirrhosis. The present review is an evaluation of our experience in the treatment of these complex biliary injuries and an analysis of the international literature on the management of patients. PMID:18695753

  2. A Comparison of Simulation Capabilities for Ducts

    SciTech Connect

    Miller, William A.; Smith, Matt K.; Gu, Lixing; New, Joshua Ryan

    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.

  3. Unsteady flowfield simulation of ducted prop-fan configurations

    NASA Technical Reports Server (NTRS)

    Janus, J. M.; Horstman, Howard Z.; Whitfield, David L.

    1992-01-01

    A technique for the simulation of unsteady flows in and around complex rotating machinery is presented. Additional domain decomposition mechanisms are introduced which extend the range of applicability of software developed for the time-accurate simulation of rotating machinery flowfields. The flow models uses the unsteady 3D Euler equations, discretized as a finite-volume method, utilizing a high-resolution approximate Riemann solver for cell interface flux definitions. Multiblock domain decomposition is used to partition the field radially, axially, as well as circumferentially into an ordered arrangement of blocks which exhibit varying degrees of similarity. A general high-order numerical scheme is applied to satisfy the geometric conservation law. Two configurations are presented - ducted single rotation prop-fan and a rotor-deswirl vane combination which form a single stage fan. Comparisons are made to other numerical solutions for these geometries and to available experimental data.

  4. Flow Simulation of Supersonic Inlet with Bypass Annular Duct

    NASA Technical Reports Server (NTRS)

    Kim, HyoungJin; Kumano, Takayasu; Liou, Meng-Sing; Povinelli, Louis A.; Conners, Timothy R.

    2011-01-01

    A relaxed isentropic compression supersonic inlet is a new concept that produces smaller cowl drag than a conventional inlet, but incurs lower total pressure recovery and increased flow distortion in the (radially) outer flowpath. A supersonic inlet comprising a bypass annulus to the relaxed isentropic compression inlet dumps out airflow of low quality through the bypass duct. A reliable computational fluid dynamics solution can provide considerable useful information to ascertain quantitatively relative merits of the concept, and further provide a basis for optimizing the design. For a fast and reliable performance evaluation of the inlet performance, an equivalent axisymmetric model whose area changes accounts for geometric and physical (blockage) effects resulting from the original complex three-dimensional configuration is proposed. In addition, full three-dimensional calculations are conducted for studying flow phenomena and verifying the validity of the equivalent model. The inlet-engine coupling is carried out by embedding numerical propulsion system simulation engine data into the flow solver for interactive boundary conditions at the engine fan face and exhaust plane. It was found that the blockage resulting from complex three-dimensional geometries in the bypass duct causes significant degradation of inlet performance by pushing the terminal normal shock upstream.

  5. Numerical simulation of duct flow with fog droplets

    NASA Astrophysics Data System (ADS)

    Suryan, Abhilash; Lee, J. K.; Kim, D. S.; Kim, H. D.

    2010-12-01

    Evaporative cooling is a widely used air cooling technique. In this method, evaporation of a liquid in the surrounding air cools the air in contact with it. In the current investigation, numerical simulations are carried out to visualize the evaporation and dynamics of tiny water droplets of different diameters in a long air duct. The effect of initial droplet size on the temperature and relative humidity distribution of the air stream in the duct is investigated. Three different initial conditions of air are considered to verify the influence of ambient conditions. Droplet spray patterns are also analyzed to identify the suitable locations for the spray nozzles within the duct. The results obtained are displayed in a series of plots to provide a clear understanding of the evaporative cooling process as well as the droplet dynamics within the ducts.

  6. Large Eddy Simulation of turbulent heat transfer in a rotating square duct

    NASA Astrophysics Data System (ADS)

    Qin, Zhaohui; Pletcher, Richard

    2004-11-01

    Turbulent heat transfer in a rotating square duct is an important topic with numerous applications such as turbine blade cooling and automobile brake cooling. Without rotation, Prandtl's secondary flow of the second kind is known to have a significant impact on the transport of heat and momentum in turbulent duct flows. With rotation, Coriolis force and centrifugal buoyancy force cause more complicated secondary flow pattern and, as a consequence, modify heat transfer coefficients. The objective of this study is to expand the capability of the current LES code to correctly predict complex turbulent flow phenomena and to gain a better understanding of the physics of turbulent flow in rotating passages. A finite volume LU-SGS scheme is used to simulate compressible three-dimensional turbulent flow at low Mach numbers. Time derivative preconditioning is employed to deal with the low Mach number situation. A localized dynamic subgrid-scale (SGS) model is used to evaluate the unresolved stresses. The calculation domain is divided into two parts. In the first part periodic boundary conditions are applied and this provides the fully developed inlet flow for the second part in which the heat transfer conditions are imposed. Characteristic out-flow conditions are used in the second part. This allows the flow to develop further as it responds to the heating condition. The code is parallelized using MPI (Message Passing Interface). To verify the code, we calculated isothermal rotating duct cases and compared our results with DNS and experimental results. Then heated duct flow cases were simulated and the results were compared to available data. Good agreement has been obtained.

  7. Numerical Simulation of Acoustic Propagation in a Lined Duct

    NASA Astrophysics Data System (ADS)

    Biringen, S.; Reichert, R. S.; Yu, J.; Zorumski, W. E.

    1996-11-01

    An inviscid, spatial time-domain numerical simulation is employed to compute acoustic wave propagation in a duct treated with an acoustic liner. The motivation is to assess the effects on sound attenuation of bias flow passed through the liner for application to noise suppression in jet engine nacelles. Physically, the liner is composed of porous sheets with backing air cavities. The mathematical model lumps the liner presence into a continuous empirical source term which modifies the right-hand side of the momentum equations. Thus, liner effects are felt interior to the domain rather than through boundary conditions. This source term determines the time-domain effects of the frequency-domain resistance and reactance of the liner's component sheets. The source term constants are matched to frequency-domain impedance data via a one-dimensional numerical impedance tube simulation. Nonlinear behavior of the liner at high sound pressure levels is included in the form of the source term. Sound pressure levels and axially transmitted power are computed to assess the effect of various magnitudes of bias flow on attenuation.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Male penile propulsion into spiraled spermathecal ducts of female chrysomelid beetles: A numerical simulation approach.

    PubMed

    Filippov, Alexander; Kovalev, Alexander; Matsumura, Yoko; Gorb, Stanislav N

    2015-11-07

    Genital diversification in animals is an interesting evolutionary phenomenon. Sexual selection is the main driving force behind the diversification. However, evolutionary mechanisms that have established and maintained variations in genitalia shape parameters observed in related species are not well understood. Here, for the first time, we used numerical simulations to test the hypothesis that variations in female spermathecal duct shapes among related beetle species mechanically interfere with penile propulsion in varying ways. Our numerical simulations showed that high curvature of the spiraled spermathecal ducts of the female have effects with a threshold-based interaction on male penile insertion. The relative size of spirals observed in the beetle, Cassida rubiginosa, studied here is not small enough to interfere with penile propulsion. But the model revealed that propulsion is impeded by the presence of reverse turns in spermathecal ducts. This type of morphology leads to an increase in the velocity of the propulsion but also to an increase in the propulsion energy cost for males. Our results showed that quantitative differences in spermathecal duct shape can mediate qualitative differences in penile motion. This explains, in part, the mechanism behind origin and maintenance of genital divergence among closely related species in general.

  10. Direct numerical simulation of turbulent flow in a rotating square duct

    SciTech Connect

    Dai, Yi-Jun; Huang, Wei-Xi Xu, Chun-Xiao; Cui, Gui-Xiang

    2015-06-15

    A fully developed turbulent flow in a rotating straight square duct is simulated by direct numerical simulations at Re{sub τ} = 300 and 0 ≤ Ro{sub τ} ≤ 40. The rotating axis is parallel to two opposite walls of the duct and normal to the main flow. Variations of the turbulence statistics with the rotation rate are presented, and a comparison with the rotating turbulent channel flow is discussed. Rich secondary flow patterns in the cross section are observed by varying the rotation rate. The appearance of a pair of additional vortices above the pressure wall is carefully examined, and the underlying mechanism is explained according to the budget analysis of the mean momentum equations.

  11. Simulations of a Normal Shock Train in a Constant Area Duct Using Wall-Modeled LES

    NASA Astrophysics Data System (ADS)

    Vane, Zachary; Bermejo-Moreno, Ivan; Lele, Sanjiva

    2013-11-01

    Large-Eddy Simulations (LES) of a turbulent boundary layer interacting with a normal shock train in a constant area duct (STCAD) are performed using an unstructured solver. Comparisons between wall-modeled LES (WMLES) and wall-resolved LES (WRLES) calculations of a spanwise-periodic flow at M = 1.61 and Re = 16,200 are used to evaluate an equilibrium wall-model's ability to replicate the wall-resolved results. The WMLES approach is then used for simulations at the flow conditions (M = 1.61, Re = 162,000) of the Carroll & Dutton STCAD experiments where traditional WRLES was inaccessible. Spanwise-periodic WMLES calculations were unable to duplicate the experimental wall pressure and Laser Doppler Velocimetry data obtained along the spanwise center plane of the duct. Investigations of the full, low aspect ratio duct geometry were then performed using WMLES. Comparisons with experimental data provide an assessment of the wall-model's ability to simulate realistic, high Reynolds number, non-equilibrium flows. However, the lack of information with respect to the sidewall boundary layers from the experiment led to a WMLES parameter study of the effects of boundary layer confinement on the shock train. Initial results suggest that the tunnel blockage due to the boundary layer displacement thickness determines many of the STCAD's characteristics. A possible improvement to the wall-model through the inclusion of previously omitted non-equilibrium terms is currently being pursued.

  12. Complex malformations of the urogenital tract in a female dog: Gartner duct cyst, ipsilateral renal agenesis, and ipsilateral hydrometra.

    PubMed

    Fujita, Atsushi; Tsuboi, Masaya; Uchida, Kazuyuki; Nishimura, Ryohei

    2016-05-01

    A 10-month-old female toy poodle was referred to the University of Tokyo Veterinary Medical Center with a urogenital anomaly found during sterilization. An exploratory laparotomy revealed a cyst adhering to the cervix and a unilateral renal agenesis. Histopathology and immunohistochemical analysis of the cyst was consistent with remnants of the Wolffian duct or a Gartner duct cyst. This is a rare case of a canine Gartner duct cyst with renal agenesis and uterine anomaly. We discuss the similarity of this case to that of humans and introduce a classification in the literature for these complex urogenital malformations for further clinical research into the precise diagnosis and appropriate surgical planning.

  13. Investigation of particle-laden flow in a straight duct using large eddy simulation

    SciTech Connect

    Fairweather, M.; Yao, J.

    2007-07-01

    A particle-laden turbulent flow in a square duct is predicted using large eddy simulation (LES). The simulation is performed for a Reynolds number of 35,500, and correctly predicts the existence of secondary flows and their effects on the mean flow. The results are also in good qualitative agreement with experimental data obtained at different Reynolds numbers. One-way coupling is assumed between solid particles and the fluid, and a particle equation of motion, including Stokes drag, lift, buoyancy and gravity force terms, solved using a Lagrangian particle tracking technique. Three sizes of particle (1, 50 and 100 {mu}m) are considered, and results demonstrate that size has a significant effect on particle dispersion and deposition in the duct flow. As particle size increases, therefore, they tend to settle on the floor of the duct, with less dispersion in the fluid phase. The study demonstrates the usefulness of LES for nuclear waste processing applications since secondary flows occur in many practically-relevant flows, and since it is desirable that the two-phase waste mixture is kept as homogeneous as possible to prevent, or at least discourage, the settling out of solid particles to form a bed which can promote pipe blockages. (authors)

  14. Hybrid palliation in complex congenital heart malformation with duct-dependent isolated pulmonary artery.

    PubMed

    Marrone, Chiara; Santoro, Giuseppe; Palladino, Maria Teresa; Caianiello, Giuseppe; Russo, Maria Giovanna; Calabrò, Raffaele

    2011-06-02

    A 2 month-old infant with severe congestive heart failure due to unrestrictive ventricular septal defect and absence of the left pulmonary artery was submitted to a hybrid transcatheter-surgical palliation consisting in percutaneous re-canalization of the occluded arterial duct-left pulmonary artery complex and surgical banding of the right pulmonary artery. The post-operative course was uneventful and the baby was discharged in a few days under mild anti-congestive therapy. This hybrid approach was highly effective in stabilizing this critical infant in view of a later and safer surgical repair.

  15. Numerical Simulation of Noise from Supersonic Jets Passing Through a Rigid Duct

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2012-01-01

    The generation, propagation and radiation of sound from a perfectly expanded Mach 2.5 cold supersonic jet flowing through an enclosed rigid-walled duct with an upstream J-deflector have been numerically simulated with the aid of OVERFLOW Navier-Stokes CFD code. A one-equation turbulence model is considered. While the near-field sound sources are computed by the CFD code, the far-field sound is evaluated by Kirchhoff surface integral formulation. Predictions of the farfield directivity of the OASPL (Overall Sound Pressure Level) agree satisfactorily with the experimental data previously reported by the author. Calculations also suggest that there is significant entrainment of air into the duct, with the mass flow rate of entrained air being about three times the jet exit mass flow rate.

  16. Measurement of flowfield in a simulated solid-propellant ducted rocket combustor using laser Doppler velocimetry

    SciTech Connect

    Hsieh, W.H.; Yang, V.; Chuang, C.L.; Yang, A.S.; Cherng, D.L.

    1989-01-01

    A two-component LDV system was used to obtain detailed flow velocity and turbulence measurements in order to study the flow characteristics in a simulated solid-propellant ducted rocket combustor. The vortical structures near the dome region, the size of the recirculation zone, and the location of the reattachment point are all shown to be strongly affected by the jet momentum of both ram air and fuel streams. It is found that the turbulence intensity is anisotropic throughout the front portion of the simulated conbustor, and that the measured Reynolds stress conmponent distribution is well correlated with the local mean velocity vector distribution. 25 refs.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  19. Eulerian-Lagrangian Simulations of Bubbly Flows in A Vertical Square Duct

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Vanka, Surya P.; Thomas, Brian G.

    2013-11-01

    We report results of Eulerian-Lagrangian simulations of developing upward and downward bubbly flows in a vertical square duct with a bulk Reynolds number of 5000. The continuous fluid is simulated with DNS, solving the Navier-Stokes equations by a second-order accurate finite volume fractional step method. Bubbles of sizes comparable to the Kolmogorov scale are injected at the duct entrance with a mean bulk volume fraction below 10-2. A two-way coupling approach is adopted for the interaction between the continuous fluid phase and dispersed bubble phase. The bubbles are tracked by a Lagrangian method including drag and lift forces due to buoyancy and Saffman lift. A in-house code, CU-FLOW, implemented on Graphic Processing Unit (GPU) is used for simulations in this work. The preferential distributions of bubbles and their impact on local turbulence structures and their effects on turbulent kinetic energy budgets are studied. Results between an upward flow and a downward flow with the bubbles are compared. Work Supported by Continuous Casting Consortium at UIUC.

  20. Aerodynamic analysis and simulation of a twin-tail tilt-duct unmanned aerial vehicle

    NASA Astrophysics Data System (ADS)

    Abdollahi, Cyrus

    The tilt-duct vertical takeoff and landing (VTOL) concept has been around since the early 1960s; however, to date the design has never passed the research phase and development phase. Nearly 50 years later, American Dynamics Flight Systems (ADFS) is developing the AD-150, a 2,250lb weight class unmanned aerial vehicle (UAV) configured with rotating ducts on each wingtip. Unlike its predecessor, the Doak VZ-4, the AD-150 features a V tail and wing sweep -- both of which affect the aerodynamic behavior of the aircraft. Because no aircraft of this type has been built and tested, vital aerodynamic research was conducted on the bare airframe behavior (without wingtip ducts). Two weeks of static and dynamic testing were performed on a 3/10th scale model at the University of Maryland's 7' x 10' low speed wind tunnel to facilitate the construction of a nonlinear flight simulator. A total of 70 dynamic tests were performed to obtain damping parameter estimates using the ordinary least squares methodology. Validation, based on agreement between static and dynamic estimates of the pitch and yaw stiffness terms, showed an average percent error of 14.0% and 39.6%, respectively. These inconsistencies were attributed to: large dynamic displacements not encountered during static testing, regressor collinearity, and, while not conclusively proven, differences in static and dynamic boundary layer development. Overall, the damping estimates were consistent and repeatable, with low scatter over a 95% confidence interval. Finally, a basic open loop simulation was executed to demonstrate the instability of the aircraft. As a result, it is recommended that future work be performed to determine trim points and linear models for controls development.

  1. Computer-Simulation Surrogates for Optimization: Application to Trapezoidal Ducts and Axisymmetric Bodies

    NASA Technical Reports Server (NTRS)

    Otto, John C.; Paraschivoiu, Marius; Yesilyurt, Serhat; Patera, Anthony T.

    1995-01-01

    Engineering design and optimization efforts using computational systems rapidly become resource intensive. The goal of the surrogate-based approach is to perform a complete optimization with limited resources. In this paper we present a Bayesian-validated approach that informs the designer as to how well the surrogate performs; in particular, our surrogate framework provides precise (albeit probabilistic) bounds on the errors incurred in the surrogate-for-simulation substitution. The theory and algorithms of our computer{simulation surrogate framework are first described. The utility of the framework is then demonstrated through two illustrative examples: maximization of the flowrate of fully developed ow in trapezoidal ducts; and design of an axisymmetric body that achieves a target Stokes drag.

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

    NASA Astrophysics Data System (ADS)

    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 propeller axis angle-of-attack at rotor speeds of at least 96 percent design.

  3. Large eddy simulation of particle-laden flow in a duct with a 90° bend

    NASA Astrophysics Data System (ADS)

    Njobuenwu, D. O.; Fairweather, M.

    2011-12-01

    Large eddy simulation (LES) of particle-laden turbulent flow is studied for a square duct with a 90° bend and a radius of curvature of 1.5 times the duct width, and for a Reynolds number based on the bulk flow velocity of 100,000. A Lagrangian particle tracking technique is used to study the motion of particles experiencing drag, shear lift, buoyancy and gravitational forces in the flow. LES predictions capture important physical aspects of these flows known to occur in practice, unlike alternative Reynolds-averaged Navier-Stokes (RANS) approaches, such as flow separation in the boundary layers around the bend entrance on the concave wall of the bend, and around the bend exit on the convex wall. The LES predicted flow and particle statistics are generally in good agreement with both experimental data used for validation purposes and RANS solutions, with r.m.s. fluctuating velocity predictions from the LES in particular being superior to values derived using the RANS technique.

  4. Large-Eddy Simulation of a Shock Train in a Duct with Side Walls

    NASA Astrophysics Data System (ADS)

    Morgan, Brandon; Duraisamy, Karthik; Lele, Sanjiva

    2012-11-01

    Large-eddy simulation (LES) is utilized to investigate the three-dimensionality of a shock train in a constant-area isolator model with fully resolved side walls (M∞ = 1.61, Reθ ~ 1660). Flow conditions and geometry are selected to match experimental conditions investigated by Carroll (1988); although Reynolds number is reduced to ensure adequate mesh resolution. Simulations with spanwise periodic boundary conditions are first performed, the results of which are compared to experiment and validated with a three-level grid refinement study. The same shock train interaction is then simulated in a three-dimensional, low-aspect ratio rectangular duct geometry with particular emphasis placed on characterizing secondary corner flows and the effects of these corner flows on the location and structure of the shock train. It is found, for instance, that location of the initial shock is particularly sensitive to the effects of spanwise confinement. Most significantly, it is observed that the same pressure ratio which results in a stable shock train with periodic boundary conditions may result in isolator unstart when side-wall effects are fully resolved.

  5. Effects of friction and heat conduction on sound propagation in ducts. [analyzing complex aerodynamic noise problems

    NASA Technical Reports Server (NTRS)

    Huerre, P.; Karamcheti, K.

    1976-01-01

    The theory of sound propagation is examined in a viscous, heat-conducting fluid, initially at rest and in a uniform state, and contained in a rigid, impermeable duct with isothermal walls. Topics covered include: (1) theoretical formulation of the small amplitude fluctuating motions of a viscous, heat-conducting and compressible fluid; (2) sound propagation in a two dimensional duct; and (3) perturbation study of the inplane modes.

  6. Numerical Simulation of Turbulent Bubbly Flow in a Vertical Square Duct

    NASA Astrophysics Data System (ADS)

    Vanka, Pratap; Kumar, Purushotam; Jin, Kai

    2016-11-01

    We numerically investigate the dynamics of a large number of gas bubbles in a turbulent liquid flow in a confined vertical square duct, a problem of interest to many industrial equipment. The fluid flow is simulated by Direct Numerical Simulations and the motions of the bubbles are resolved by an accurate Volume of Fluid (VOF) technique. The flow is considered periodic in the streamwise direction with an imposed pressure gradient. The surface tension force is incorporated through a Sharp Surface Force (SSF) method that is observed to generate only very small spurious velocities at the interface. The algorithm has been programmed on a multiple-GPU computer in a data parallel mode. The turbulence driven secondary flows are first ensured to agree with previous DNS/LES by other researchers. A very fine grid with 192 x 192 x 768 control volumes is used to resolve the liquid flow as well as 864 bubbles using 12 grid points across each bubble in all directions. The computations are carried out to 1.5 million time steps. It is seen that the bubbles preferentially migrate to walls, starting from a uniform layout. We present instantaneous and time mean velocities, turbulence statistics and compare them with unladen flow as well as with a bubbly flow in a planar channel.

  7. The propagation and attenuation of complex acoustic waves in treated circular and annular ducts

    NASA Technical Reports Server (NTRS)

    Reethof, G.

    1976-01-01

    The propagation of plane waves and higher order acoustic modes in a circular multisectioned duct was studied. A unique source array consisting of two concentric rings of sources, providing phase and amplitude control in the radial, as well as circumferential direction, was developed to generate plane waves and both spinning and nonspinning higher order modes. Measurements of attenuation and radial mode shapes were taken with finite length liners between the hard wall sections of an anechoically terminated duct. Materials tested as liners included a glass fiber material and both sintered fiber metals and perforated sheet metals with a honeycomb backing. The fundamental acoustic properties of these materials were studied with emphasis on the attenuation of sound by the liners and the determination of local versus extended reaction behavior for the boundary condition. The experimental results were compared with a mathematical model for the multisectioned duct.

  8. Simulations of Three-dimensional Droplet Deformation in a Square-Duct at Moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Horwitz, Jeremy; Kumar, Purushotam; Vanka, Pratap

    2013-11-01

    We present results of numerical simulations of deformation of a confined droplet in a three-dimensional square-duct flow using a multiphase Lattice Boltzmann Method. We have studied the effects of capillary number, Reynolds number, and viscosity ratio on the droplet deformation characteristics. Unlike in the Stokes' limit where deformation is governed by a competition between viscous shear and interfacial tension, at higher Reynolds numbers, inertial effects play an increasingly important role. We observe that the deformation history is non-monotonic and contains an overshoot before relaxing to a steady deformed state. In contrast, the capillary number is seen to affect the magnitude of the deformation history and the time at which the peak deformation occurs. The viscosity ratio has a relatively modest effect on the magnitude of the deformation compared with the effects of Reynolds and capillary numbers. However, compared with the Reynolds number, the viscosity ratio and capillary number have a significant effect on the time to reach a steady state. University of Illinois at Urbana-Champaign, Air Conditioning and Refrigeration Center.

  9. Aircraft Ducting

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Templeman Industries developed the Ultra-Seal Ducting System, an environmental composite air duct with a 50 percent weight savings over current metallic ducting, but could not find a commercial facility with the ability to test it. Marshall Space Flight Center conducted a structural evaluation of the duct, equivalent to 86 years of take-offs and landings in an aircraft. Boeing Commercial Airplane Group and McDonnell Douglas Corporation are currently using the ducts.

  10. Effectiveness of a serpentine inlet duct flow control scheme at design and off-design simulated flight conditions

    NASA Astrophysics Data System (ADS)

    Rabe, Angela C.

    An experimental investigation was conducted in a static ground test facility to determine the flow quality of a serpentine inlet duct incorporating active flow control for several simulated flight conditions. The total pressure distortion at the aerodynamic interface plane (AIP) was then used to predict the resulting stability for a compression system. This study was conducted using a model of a compact, low observable, engine inlet duct developed by Lockheed Martin. A flow control technique using air injection through microjets at 1% of the inlet mass flow rate was developed by Lockheed Martin to improve the quality of the flow exiting the inlet duct. Both the inlet duct and the flow control technique were examined at cruise condition and off-design simulated flight conditions (angle of attack and asymmetric distortion). All of the experimental tests were run at an inlet throat Mach number of 0.55 and a resulting Reynolds number of 1.76*105 based on the hydraulic diameter at the inlet throat. For each of the flight conditions tested, the flow control scheme was found to improve the flow uniformity and reduce the inlet distortion at the AIP. For simulated cruise condition, the total pressure recovery was improved by ˜2% with the addition of flow control. For the off-design conditions of angle of attack and asymmetric distortion, the total pressure recovery was improved by 1.5% and 2% respectively. All flight conditions tested showed a reduction in circumferential distortion intensity with flow control. The cruise condition case showed reduced maximum circumferential distortion of 70% with the addition of flow control. A reduction in maximum circumferential distortion of 40% occurred for the angle of attack case with flow control, and 30% for the asymmetric distortion case with flow control. The inlet total pressure distortion was used to predict the changes in stability margin of a compression system due to design and off-design flight conditions and the

  11. Numerical simulation of a shock wave/turbulent boundary layer interaction in a duct

    NASA Technical Reports Server (NTRS)

    Yang, Wei-Li; Greber, Isaac

    1993-01-01

    A numerical investigation of the interaction of an incident oblique shock wave with a turbulent duct flow is presented. The investigation consists of solving the three-dimensional, unsteady, compressible, mass averaged Navier-Stokes equations, using an implicit finite volume, lower-upper time marching code and incorporates the three-dimensional Baldwin-Lomax turbulence model. Computed results are obtained Mach number 2.9 for a turning angle of 13 degrees and Reynolds number based on duct width of 1.36 x 10 exp 7. Under various inlet conditions, the results clearly depict the flow characteristics, including the shock geometry, the separated flow region, the wall pressure distribution, and the skin friction distribution. The findings provide a physical understanding of the three-dimensional vortex structure of the flow in a duct in which a shock wave interacts with a turbulent boundary layer. The results show that the ratio of the boundary layer thickness to the duct width is the critical parameter in determining the separation structure.

  12. Wall-modeled large-eddy simulations of shock/turbulent-boundary layer interaction in a duct

    NASA Astrophysics Data System (ADS)

    Bermejo-Moreno, Ivan; Larsson, Johan; Campo, Laura; Bodart, Julien; Helmer, David; Ham, Frank; Eaton, John K.

    2012-11-01

    We present wall-modeled LES of the interaction of an oblique shock wave and a turbulent boundary layer in a low-aspect-ratio duct, following the experiment by Campo, Helmer & Eaton, 2012. A M = 2 . 05 air stream is deflected by a small compression wedge that spans the top wall of the duct at 20°, generating an oblique shock that reflects off the turbulent boundary layer at the bottom wall. The Reynolds number of the incoming flow based on the boundary layer momentum thickness is Reθ = 6 , 500 . Simulations are performed with a control-volume-based, finite-volume solver of the filtered, compressible Navier-Stokes equations, utilizing a grid-based blend of non-dissipative central and dissipative upwind fluxes, Vreman (2004) subgrid scale model and ENO shock-capturing scheme, active only near shocks. An equilibrium wall model (Kawai and Larsson, 2012) is used. Turbulence is generated at the inflow from experimental data. Simulation results are compared to PIV data on four planes normal to the spanwise coordinate. A grid-convergence study is performed. Two heights of the compression wedge are considered, resulting in an increased strength of the interaction. Simulation results are also used to study the evolution of corner flows, complementing experimental findings. The authors acknowledge financial support provided by the USDoE under the Predictive Science Academic Alliance Program (PSAAP) at Stanford University.

  13. A finite element simulation of sound attenuation in a finite duct with a peripherally variable liner

    NASA Technical Reports Server (NTRS)

    Watson, W. R.

    1977-01-01

    Using multimodal analysis, a variational finite element method is presented for analyzing sound attenuation in a three-dimensional finite duct with a peripherally variable liner in the absence of flow. A rectangular element, with cubic shaped functions, is employed. Once a small portion of a peripheral liner is removed, the attenuation rate near the frequency where maximum attenuation occurs drops significantly. The positioning of the liner segments affects the attenuation characteristics of the liner. Effects of the duct termination are important in the low frequency ranges. The main effect of peripheral variation of the liner is a broadening of the attenuation characteristics in the midfrequency range. Because of matrix size limitations of the presently available computer program, the eigenvalue equations should be solved out of core in order to handle realistic sources.

  14. Lensing duct

    DOEpatents

    Beach, Raymond J. , Benett

    1994-01-01

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic.

  15. Lensing duct

    DOEpatents

    Beach, R.J.; Benett, W.J.

    1994-04-26

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding is described. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic. 3 figures.

  16. Simulation Analysis of Air Flow and Turbulence Statistics in a Rib Grit Roughened Duct

    PubMed Central

    Vogiatzis, I. I.; Denizopoulou, A. C.; Ntinas, G. K.; Fragos, V. P.

    2014-01-01

    The implementation of variable artificial roughness patterns on a surface is an effective technique to enhance the rate of heat transfer to fluid flow in the ducts of solar air heaters. Different geometries of roughness elements investigated have demonstrated the pivotal role that vortices and associated turbulence have on the heat transfer characteristics of solar air heater ducts by increasing the convective heat transfer coefficient. In this paper we investigate the two-dimensional, turbulent, unsteady flow around rectangular ribs of variable aspect ratios by directly solving the transient Navier-Stokes and continuity equations using the finite elements method. Flow characteristics and several aspects of turbulent flow are presented and discussed including velocity components and statistics of turbulence. The results reveal the impact that different rib lengths have on the computed mean quantities and turbulence statistics of the flow. The computed turbulence parameters show a clear tendency to diminish downstream with increasing rib length. Furthermore, the applied numerical method is capable of capturing small-scale flow structures resulting from the direct solution of Navier-Stokes and continuity equations. PMID:25057511

  17. Scissors Duct

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Stennis Space Center engineers are preparing to conduct water tests on an updated version of the scissors duct component of the J-2X engine. Measuring about 2 feet long and about 8 inches in diameter, the duct on the J-2X predecessor, the J-2, connected its fuel turbo pumps to the flight vehicle's upper stage run tanks. According to NASA's J-2X project manager at SSC, Gary Benton, the water tests should establish the limits of the duct's ability to withstand vibration.

  18. Duct closure

    DOEpatents

    Vowell, Kennison L.

    1987-01-01

    A closure for an inclined duct having an open upper end and defining downwardly extending passageway. The closure includes a cap for sealing engagement with the open upper end of the duct. Associated with the cap are an array of vertically aligned plug members, each of which has a cross-sectional area substantially conforming to the cross-sectional area of the passageway at least adjacent the upper end of the passageway. The plug members are interconnected in a manner to provide for free movement only in the plane in which the duct is inclined. The uppermost plug member is attached to the cap means and the cap means is in turn connected to a hoist means which is located directly over the open end of the duct.

  19. Molecular simulation and modeling of complex I.

    PubMed

    Hummer, Gerhard; Wikström, Mårten

    2016-07-01

    Molecular modeling and molecular dynamics simulations play an important role in the functional characterization of complex I. With its large size and complicated function, linking quinone reduction to proton pumping across a membrane, complex I poses unique modeling challenges. Nonetheless, simulations have already helped in the identification of possible proton transfer pathways. Simulations have also shed light on the coupling between electron and proton transfer, thus pointing the way in the search for the mechanistic principles underlying the proton pump. In addition to reviewing what has already been achieved in complex I modeling, we aim here to identify pressing issues and to provide guidance for future research to harness the power of modeling in the functional characterization of complex I. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.

  20. Development of simulation computer complex specification

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The Training Simulation Computer Complex Study was one of three studies contracted in support of preparations for procurement of a shuttle mission simulator for shuttle crew training. The subject study was concerned with definition of the software loads to be imposed on the computer complex to be associated with the shuttle mission simulator and the development of procurement specifications based on the resulting computer requirements. These procurement specifications cover the computer hardware and system software as well as the data conversion equipment required to interface the computer to the simulator hardware. The development of the necessary hardware and software specifications required the execution of a number of related tasks which included, (1) simulation software sizing, (2) computer requirements definition, (3) data conversion equipment requirements definition, (4) system software requirements definition, (5) a simulation management plan, (6) a background survey, and (7) preparation of the specifications.

  1. Simulation forecasts complex flow streams from Ekofisk

    SciTech Connect

    Arnes, F.C.; Lillejord, H.

    1996-10-28

    A commercial steady-state process flowsheet simulation program serves as the basis for a rigorous calculation model for predicting produced flow rates from the Ekofisk complex in the Norwegian sector of the North Sea. The complex is the center of an extensive gathering system that collects oil and gas streams from several producing fields. Prior to running a production forecast, the simulation model is initiated by matching several years of production. Once the simulation model matches historical production data within acceptable limits, it then is driven by production forecasts from reservoir simulations to develop long-term forecasts of gas, NGL, and oil production. The paper describes the Ekofisk field, the process simulation, implementation of the model, and problems encountered.

  2. Turbofan Duct Propagation Model

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  3. Evaluation of panel code predictions with experimental results of inlet performance for a 17-inch ducted prop/fab simulator operating at Mach 0.2

    NASA Technical Reports Server (NTRS)

    Boldman, D. R.; Iek, C.; Hwang, D. P.; Jeracki, R. J.; Larkin, M.; Sorin, G.

    1991-01-01

    An axisymmetric panel code was used to evaluate a series of ducted propeller inlets. The inlets were tested in the Lewis 9 by 15 Foot Low Speed Wind Tunnel. Three basic inlets having ratios of shroud length to propeller diameter of 0.2, 0.4, and 0.5 were tested with the Pratt and Whitney ducted prop/fan simulator. A fourth hybrid inlet consisting of the shroud from the shortest basic inlet coupled with the spinner from the largest basic inlet was also tested. This later configuration represented the shortest overall inlet. The simulator duct diameter at the propeller face was 17.25 inches. The short and long spinners provided hub-to-tip ratios of 0.44 at the propeller face. The four inlets were tested at a nominal free stream Mach number of 0.2 and at angles of attack from 0 degrees to 35 degrees. The panel code method incorporated a simple two-part separation model which yielded conservative estimates of inlet separation.

  4. Efficiency of the confocal method of laser endomicroscopy in complex diagnoses of diseases of common bile duct

    NASA Astrophysics Data System (ADS)

    Anaskin, S. G.; Panchenkov, D. N.; Chertyuk, V. B.; Sazonov, D. V.; Zabozlayev, F. G.; Danilevskaya, O. V.; Mokshina, N. V.; Korniletsky, I. D.

    2017-01-01

    One of the more frequent manifestations of diseases of the bile ducts are its’ strictures or stenoses that could be of either malignant or benign nature. Current methods of diagnosing this pathology include computer tomography (CT) scan, magnetic resonance cholangiopancreatography (MRCP), endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP). However, these methods are not always informative, which makes this a current and topical problem. A fundamentally new method that broadens the capabilities of ERCP when diagnosing diseases of the bile duct accompanied by the development of strictures or stenoses is probe-based confocal laser endomicroscopy (pCLE). The method is based on the principle of confocal fluorescence microscopy. The most elaborate complications arise with the presence of the pre-existing pancreatobiliary pathology: pseudotumoral chronic pancreatitis, acute cholangitis, etc. Early stage cholangiocarcinoma diagnosis can be difficult (and not always possible) even with the help of modern research methods. For the timely diagnostic it is advantageous to conduct pCLE and targeted biopsy of the zone with most manifested changes. In all instances, the first use of the pCLE method for diagnostic purposes allowed us to clarify and correctly verify the diagnosis. When concerning the diseases of the bile duct, the modern stage of pCLE development can be of critical importance when other methods are not effective.

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

    NASA Technical Reports Server (NTRS)

    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

  6. Toward simulating complex systems with quantum effects

    NASA Astrophysics Data System (ADS)

    Kenion-Hanrath, Rachel Lynn

    Quantum effects like tunneling, coherence, and zero point energy often play a significant role in phenomena on the scales of atoms and molecules. However, the exact quantum treatment of a system scales exponentially with dimensionality, making it impractical for characterizing reaction rates and mechanisms in complex systems. An ongoing effort in the field of theoretical chemistry and physics is extending scalable, classical trajectory-based simulation methods capable of capturing quantum effects to describe dynamic processes in many-body systems; in the work presented here we explore two such techniques. First, we detail an explicit electron, path integral (PI)-based simulation protocol for predicting the rate of electron transfer in condensed-phase transition metal complex systems. Using a PI representation of the transferring electron and a classical representation of the transition metal complex and solvent atoms, we compute the outer sphere free energy barrier and dynamical recrossing factor of the electron transfer rate while accounting for quantum tunneling and zero point energy effects. We are able to achieve this employing only a single set of force field parameters to describe the system rather than parameterizing along the reaction coordinate. Following our success in describing a simple model system, we discuss our next steps in extending our protocol to technologically relevant materials systems. The latter half focuses on the Mixed Quantum-Classical Initial Value Representation (MQC-IVR) of real-time correlation functions, a semiclassical method which has demonstrated its ability to "tune'' between quantum- and classical-limit correlation functions while maintaining dynamic consistency. Specifically, this is achieved through a parameter that determines the quantumness of individual degrees of freedom. Here, we derive a semiclassical correction term for the MQC-IVR to systematically characterize the error introduced by different choices of simulation

  7. Simulating Vibrations in a Complex Loaded Structure

    NASA Technical Reports Server (NTRS)

    Cao, Tim T.

    2005-01-01

    The Dynamic Response Computation (DIRECT) computer program simulates vibrations induced in a complex structure by applied dynamic loads. Developed to enable rapid analysis of launch- and landing- induced vibrations and stresses in a space shuttle, DIRECT also can be used to analyze dynamic responses of other structures - for example, the response of a building to an earthquake, or the response of an oil-drilling platform and attached tanks to large ocean waves. For a space-shuttle simulation, the required input to DIRECT includes mathematical models of the space shuttle and its payloads, and a set of forcing functions that simulates launch and landing loads. DIRECT can accommodate multiple levels of payload attachment and substructure as well as nonlinear dynamic responses of structural interfaces. DIRECT combines the shuttle and payload models into a single structural model, to which the forcing functions are then applied. The resulting equations of motion are reduced to an optimum set and decoupled into a unique format for simulating dynamics. During the simulation, maximum vibrations, loads, and stresses are monitored and recorded for subsequent analysis to identify structural deficiencies in the shuttle and/or payloads.

  8. Software for Simulating a Complex Robot

    NASA Technical Reports Server (NTRS)

    Goza, S. Michael

    2003-01-01

    RoboSim (Robot Simulation) is a computer program that simulates the poses and motions of the Robonaut a developmental anthropomorphic robot that has a complex system of joints with 43 degrees of freedom and multiple modes of operation and control. RoboSim performs a full kinematic simulation of all degrees of freedom. It also includes interface components that duplicate the functionality of the real Robonaut interface with control software and human operators. Basically, users see no difference between the real Robonaut and the simulation. Consequently, new control algorithms can be tested by computational simulation, without risk to the Robonaut hardware, and without using excessive Robonaut-hardware experimental time, which is always at a premium. Previously developed software incorporated into RoboSim includes Enigma (for graphical displays), OSCAR (for kinematical computations), and NDDS (for communication between the Robonaut and external software). In addition, RoboSim incorporates unique inverse-kinematical algorithms for chains of joints that have fewer than six degrees of freedom (e.g., finger joints). In comparison with the algorithms of OSCAR, these algorithms are more readily adaptable and provide better results when using equivalent sets of data.

  9. Bile Duct Cancer (Cholangiocarcinoma)

    MedlinePlus

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

  10. Mammary Duct Ectasia

    MedlinePlus

    ... 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, ...

  11. Minimum-complexity helicopter simulation math model

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

    An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.

  12. Simulating Complex Window Systems using BSDF Data

    SciTech Connect

    Konstantoglou, Maria; Jonsson, Jacob; Lee, Eleanor

    2009-06-22

    Nowadays, virtual models are commonly used to evaluate the performance of conventional window systems. Complex fenestration systems can be difficult to simulate accurately not only because of their geometry but also because of their optical properties that scatter light in an unpredictable manner. Bi-directional Scattering Distribution Functions (BSDF) have recently been developed based on a mixture of measurements and modelling to characterize the optics of such systems. This paper describes the workflow needed to create then use these BSDF datasets in the Radiance lighting simulation software. Limited comparisons are made between visualizations produced using the standard ray-tracing method, the BSDF method, and that taken in a full-scale outdoor mockup.

  13. Simulating Operation of a Complex Sensor Network

    NASA Technical Reports Server (NTRS)

    Jennings, Esther; Clare, Loren; Woo, Simon

    2008-01-01

    Simulation Tool for ASCTA Microsensor Network Architecture (STAMiNA) ["ASCTA" denotes the Advanced Sensors Collaborative Technology Alliance.] is a computer program for evaluating conceptual sensor networks deployed over terrain to provide military situational awareness. This or a similar program is needed because of the complexity of interactions among such diverse phenomena as sensing and communication portions of a network, deployment of sensor nodes, effects of terrain, data-fusion algorithms, and threat characteristics. STAMiNA is built upon a commercial network-simulator engine, with extensions to include both sensing and communication models in a discrete-event simulation environment. Users can define (1) a mission environment, including terrain features; (2) objects to be sensed; (3) placements and modalities of sensors, abilities of sensors to sense objects of various types, and sensor false alarm rates; (4) trajectories of threatening objects; (5) means of dissemination and fusion of data; and (6) various network configurations. By use of STAMiNA, one can simulate detection of targets through sensing, dissemination of information by various wireless communication subsystems under various scenarios, and fusion of information, incorporating such metrics as target-detection probabilities, false-alarm rates, and communication loads, and capturing effects of terrain and threat.

  14. Reliability of Complex Nonlinear Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    2004-01-01

    This work describes some of the procedure to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to turbulent flow computations are included.

  15. Fully nonlinear time-domain simulation of a backward bent duct buoy floating wave energy converter using an acceleration potential method

    NASA Astrophysics Data System (ADS)

    Lee, Kyoung-Rok; Koo, Weoncheol; Kim, Moo-Hyun

    2013-12-01

    A floating Oscillating Water Column (OWC) wave energy converter, a Backward Bent Duct Buoy (BBDB), was simulated using a state-of-the-art, two-dimensional, fully-nonlinear Numerical Wave Tank (NWT) technique. The hydrodynamic performance of the floating OWC device was evaluated in the time domain. The acceleration potential method, with a full-updated kernel matrix calculation associated with a mode decomposition scheme, was implemented to obtain accurate estimates of the hydrodynamic force and displacement of a freely floating BBDB. The developed NWT was based on the potential theory and the boundary element method with constant panels on the boundaries. The mixed Eulerian-Lagrangian (MEL) approach was employed to capture the nonlinear free surfaces inside the chamber that interacted with a pneumatic pressure, induced by the time-varying airflow velocity at the air duct. A special viscous damping was applied to the chamber free surface to represent the viscous energy loss due to the BBDB's shape and motions. The viscous damping coefficient was properly selected using a comparison of the experimental data. The calculated surface elevation, inside and outside the chamber, with a tuned viscous damping correlated reasonably well with the experimental data for various incident wave conditions. The conservation of the total wave energy in the computational domain was confirmed over the entire range of wave frequencies.

  16. Duct Joining System

    DOEpatents

    Proctor, John P.

    2001-02-27

    A duct joining system for providing an air-tight seal and mechanical connection for ducts and fittings is disclosed. The duct joining system includes a flexible gasket affixed to a male end of a duct or fitting. The flexible gasket is affixed at an angle relative to normal of the male end of the duct. The female end of the other duct includes a raised bead in which the flexible gasket is seated when the ducts are properly joined. The angled flexible gasket seated in the raised bead forms an air-tight seal as well as fastens or locks the male end to the female end. Alternatively, when a flexible duct is used, a band clamp with a raised bead is clamped over the female end of the flexible duct and over the male end of a fitting to provide an air tight seal and fastened connection.

  17. Duct joining system

    DOEpatents

    Proctor, John P.; deKieffer, Robert C.

    2001-01-01

    A duct joining system for providing an air-tight seal and mechanical connection for ducts and fittings is disclosed. The duct joining system includes a flexible gasket affixed to a male end of a duct or fitting. The flexible gasket is affixed at an angle relative to normal of the male end of the duct. The female end of the other duct includes a raised bead in which the flexible gasket is seated when the ducts are properly joined. The angled flexible gasket seated in the raised bead forms an air-tight seal as well as fastens or locks the male end to the female end. Alternatively, when a flexible duct is used, a band clamp with a raised bead is clamped over the female end of the flexible duct and over the male end of a fitting to provide an air tight seal and fastened connection.

  18. Hollow lensing duct

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

    2000-01-01

    A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

  19. Rocket-in-a-Duct Performance Analysis

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Reed, Brian D.

    1999-01-01

    An axisymmetric, 110 N class, rocket configured with a free expansion between the rocket nozzle and a surrounding duct was tested in an altitude simulation facility. The propellants were gaseous hydrogen and gaseous oxygen and the hardware consisted of a heat sink type copper rocket firing through copper ducts of various diameters and lengths. A secondary flow of nitrogen was introduced at the blind end of the duct to mix with the primary rocket mass flow in the duct. This flow was in the range of 0 to 10% of the primary massflow and its effect on nozzle performance was measured. The random measurement errors on thrust and massflow were within +/-1%. One dimensional equilibrium calculations were used to establish the possible theoretical performance of these rocket-in-a-duct nozzles. Although the scale of these tests was small, they simulated the relevant flow expansion physics at a modest experimental cost. Test results indicated that lower performance was obtained at higher free expansion area ratios and longer ducts, while, higher performance was obtained with the addition of secondary flow. There was a discernable peak in specific impulse efficiency at 4% secondary flow. The small scale of these tests resulted in low performance efficiencies, but prior numerical modeling of larger rocket-in-a-duct engines predicted performance that was comparable to that of optimized rocket nozzles. This remains to be proven in large-scale, rocket-in-a-duct tests.

  20. Bile Duct Diseases

    MedlinePlus

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

  1. Bile duct stricture

    MedlinePlus

    ... occur after surgery to remove the gallbladder. Other causes of this condition include: Cancer of the bile duct, liver or pancreas Damage and scarring due to a gallstone in the bile duct Damage or scarring after ...

  2. Curved Duct Noise Prediction Using the Fast Scattering Code

    NASA Technical Reports Server (NTRS)

    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.

  3. Duct Flow Control System.

    DTIC Science & Technology

    is ejected under pressure tangentially of local duct surfaces through Coanda affected slots at the trailing edge of the duct from which only the...channel passages in order to modify the flow stream through the duct so as to perform certain functions such as thrust control and steerage control effects enhancing vehicle maneuverability.

  4. Blocked Tear Duct

    MedlinePlus

    Blocked tear duct Overview By Mayo Clinic Staff When you have a blocked tear duct, your tears can't drain normally, leaving you ... in the tear drainage system. A blocked tear duct is common in newborns. The condition usually gets ...

  5. Comprehensive Report of Fan Performance From Duct Rake Instrumentation on 1.294 Pressure Ratio, 806 ft/sec Tip Speed Turbofan Simulator Models

    NASA Technical Reports Server (NTRS)

    Jeracki, Robert J.

    2006-01-01

    A large scale model representative of an advanced ducted propulsor-type, low-noise, very high bypass ratio turbofan engine was tested for acoustics, aerodynamic performance, and off-design operability in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel. The test was part of NASA s Advanced Subsonic Technology Noise Reduction Program. The low tip speed fan, nacelle, and un-powered core passage were simulated. As might be expected, the effect of stall management casing treatment was a performance penalty. Reducing the recirculating flow at the fan tip reduced the penalty while still providing sufficient stall margin. Two fans were tested with the same aerodynamic design; one with graphite composite material, and the other with solid titanium. There were surprising performance differences between the two fans, though both blades showed some indication of transitional flow near the tips. Though the pressure and temperature ratios were low for this fan design, the techniques used to improve thermocouple measurement accuracy gave repeatable data with adiabatic efficiencies agreeing within 1 percent. The measured fan adiabatic efficiency at simulated takeoff conditions was 93.7 percent and matched the design intent.

  6. Thrust control system design of ducted rockets

    NASA Astrophysics Data System (ADS)

    Chang, Juntao; Li, Bin; Bao, Wen; Niu, Wenyu; Yu, Daren

    2011-07-01

    The investigation of the thrust control system is aroused by the need for propulsion system of ducted rockets. Firstly the dynamic mathematical models of gas flow regulating system, pneumatic servo system and ducted rocket engine were established and analyzed. Then, to conquer the discussed problems of thrust control, the idea of information fusion was proposed to construct a new feedback variable. With this fused feedback variable, the thrust control system was designed. According to the simulation results, the introduction of the new fused feedback variable is valid in eliminating the contradiction between rapid response and stability for the thrust control system of ducted rockets.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Lightweight Valve Closes Duct Quickly

    NASA Technical Reports Server (NTRS)

    Fournier, Walter L.; Burgy, N. Frank

    1991-01-01

    Expanding balloon serves as lightweight emergency valve to close wide duct. Uninflated balloon stored in housing of duct. Pad resting on burst diaphragm protects balloon from hot gases in duct. Once control system triggers valve, balloon inflates rapidly to block duct. Weighs much less than does conventional butterfly, hot-gas, or poppet valve capable of closing duct of equal diameter.

  9. Chimaera simulation of complex states of flowing matter.

    PubMed

    Succi, S

    2016-11-13

    We discuss a unified mesoscale framework (chimaera) for the simulation of complex states of flowing matter across scales of motion. The chimaera framework can deal with each of the three macro-meso-micro levels through suitable 'mutations' of the basic mesoscale formulation. The idea is illustrated through selected simulations of complex micro- and nanoscale flows.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  10. Chimaera simulation of complex states of flowing matter

    NASA Astrophysics Data System (ADS)

    Succi, S.

    2016-11-01

    We discuss a unified mesoscale framework (chimaera) for the simulation of complex states of flowing matter across scales of motion. The chimaera framework can deal with each of the three macro-meso-micro levels through suitable `mutations' of the basic mesoscale formulation. The idea is illustrated through selected simulations of complex micro- and nanoscale flows. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  11. Advanced Duct Sealing Testing

    SciTech Connect

    Sherman, Max H.; Walker, Iain S.

    2003-08-01

    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 typically shown that these seals tend to fail over extended periods of time. The Lawrence Berkeley National Laboratory has been testing sealant durability for several years. Typical duct tape (i.e. fabric backed tapes with natural rubber adhesives) was found to fail more rapidly than all other duct sealants. This report summarizes the results of duct sealant durability testing of five UL 181B-FX listed duct tapes (three cloth tapes, a foil tape and an Oriented Polypropylene (OPP) tape). One of the cloth tapes was specifically developed in collaboration with a tape manufacturer to perform better in our durability testing. The first test involved the aging of common ''core-to-collar joints'' of flexible duct to sheet metal collars, and sheet metal ''collar-to-plenum joints'' pressurized with 200 F (93 C) air. The second test consisted of baking duct tape specimens in a constant 212 F (100 C) oven following the UL 181B-FX ''Temperature Test'' requirements. Additional tests were also performed on only two tapes using sheet metal collar-to-plenum joints. Since an unsealed flexible duct joint can have a variable leakage depending on the positioning of the flexible duct core, the durability of the flexible duct joints could not be based on the 10% of unsealed leakage criteria. Nevertheless, the leakage of the sealed specimens prior to testing could be considered as a basis for a failure criteria. Visual inspection was also documented throughout the tests. The flexible duct core-to-collar joints were inspected monthly, while the sheet metal collar-to-plenum joints were inspected

  12. Duct Tape Durability Testing

    SciTech Connect

    Sherman, Max H.; Walker, Iain S.

    2004-04-01

    Duct leakage is 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 taped seals tend to fail over extended periods of time. The Lawrence Berkeley National Laboratory (LBNL) has been testing sealant durability for several years using accelerated test methods and found that typical duct tape (i.e., cloth-backed tapes with natural rubber adhesives) fails more rapidly than other duct sealants. This report summarizes the results of duct sealant durability testing over two years for four UL 181B-FX listed duct tapes (two cloth tapes, a foil tape and an Oriented Polypropylene (OPP) tape). One of the cloth tapes was specifically developed in collaboration with a tape manufacturer to perform better in our durability testing. The tests involved the aging of common ''core-to-collar joints'' of flexible duct to sheet metal collars. Periodic air leakage tests and visual inspection were used to document changes in sealant performance. After two years of testing, the flex-to-collar connections showed little change in air leakage, but substantial visual degradation from some products. A surprising experimental result was failure of most of the clamps used to mechanically fasten the connections. This indicates that the durability of clamps also need to be addressed ensure longevity of the duct connection. An accelerated test method developed during this study has been used as the basis for an ASTM standard (E2342-03).

  13. Designing Better Scaffolding in Teaching Complex Systems with Graphical Simulations

    ERIC Educational Resources Information Center

    Li, Na

    2013-01-01

    Complex systems are an important topic in science education today, but they are usually difficult for secondary-level students to learn. Although graphic simulations have many advantages in teaching complex systems, scaffolding is a critical factor for effective learning. This dissertation study was conducted around two complementary research…

  14. A molecular simulation study on salt response of polyelectrolyte complexes

    NASA Astrophysics Data System (ADS)

    Antila, Hanne; van Tassel, Paul; Sammalkorpi, Maria

    2015-03-01

    In aqueous solutions, oppositely charged polymers, polyelectrolytes (PEs) form complexes which are known to be sensitive to added salt with responses ranging from shrinking to full destabilization of the complex. As a specific application of PE complexes, the complex formation of DNA with polycations has been demonstrated to be an effective means of transfecting genetic material in gene therapy. We use all-atom molecular dynamics and coarse-grained Monte Carlo simulations to investigate the effect of excess salt on DNA-polycation complex stability. The detailed all-atom simulations demonstrate the mechanism of polycation and ion species specific salt-driven dissociation involving charge reversal. More generally, other possible mechanisms of salt driven dissociation exist as well. The coarse grained approach, which describes the PE complex as oppositely charged, rigid rods and ions as hard spheres, provides a more complete understanding of PE interactions in salt, and suggests possible mechanisms leading to repulsion between the oppositely charged polyelectrolytes.

  15. Geomechanical numerical simulations of complex geologic structures

    SciTech Connect

    Arguello, J.G.; Stone, C.M.; Lorenz, J.C.

    1996-05-01

    Ability to predict mechanical response of rock in three dimensions over the spatial and time scales of geologic interest would give the oil and gas industry the ability to reduce risk on prospects, improve pre-project initial reserve estimates, and lower operating costs. A program has recently been initiated, under the auspices of the Advanced Computational Technology Initiative (ACTI), to achieve such a computational technology breakthrough by adapting the unique advanced quasistatic finite element technology developed by Sandia to the mechanics applications important to exploration and production activities within the oil and gas industry. As a precursor to that program, in an effort to evaluate the feasibility of the approach, several complex geologic structures of interest were analyzed with the existing two-dimensional quasistatic finite element code, SANTOS, developed at Sandia. Examples are presented and discussed.

  16. Simulation and display of macromolecular complexes

    NASA Technical Reports Server (NTRS)

    Nir, S.; Garduno, R.; Rein, R.; Macelroy, R. D.

    1977-01-01

    In association with an investigation of the interaction of proteins with DNA and RNA, an interactive computer program for building, manipulating, and displaying macromolecular complexes has been designed. The system provides perspective, planar, and stereoscopic views on the computer terminal display, as well as views for standard and nonstandard observer locations. The molecule or its parts may be rotated and/or translated in any direction; bond connections may be added or removed by the viewer. Molecular fragments may be juxtaposed in such a way that given bonds are aligned, and given planes and points coincide. Another subroutine provides for the duplication of a given unit such as a DNA or amino-acid base.

  17. Loft duct project report

    SciTech Connect

    Reed, J.R.

    1993-06-01

    On October 16, 1992, during a routine examination of the loft of Building 332, the Building Coordinator observed cracks in the welds of the duct work that services the fume hoods for Rooms 1313, 1321, and 1329. Further examination revealed cracks in the weld of the duct work that services the gloveboxes in Rooms 1321 and 1329. Upon discovery of the cracked welds, facility management immediately took the following two actions: Because one crack in the fume hood exhaust extended 70% around the duct circumference, a 1-ton chain fall was used to secure the duct to the roof support structure to prevent the duct from falling if the duct completely fractured. The Facility Manager suspended plutonium handling operations in the gloveboxes and work in the fume hoods in the affected rooms until the situation could be thoroughly investigated. Building 332 is ventilated by drawing conditioned air from the building hallways into the laboratories, hoods, and gloveboxes. This air is filtered through two sets of high-efficiency particulate air (HEPA) filters before being exhausted from the facility. Figure 1 is a schematic of the typical air flow pattern for the facility. All affected duct work is located in the loft of the facility or pressure zone 4. This ducting is fabricated from 12-, 14- and 16-gauge, 304 stainless-steel sheet stock and joined by the Gas Tungsten Arc Welding (GTAW) process.

  18. Ducted auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1982-01-01

    Certain discrete, intense wave signals attributed to auroral kilometric radiation (AKR) were observed with ISEE-l while it was within the plasmaspheric shadow zone for direct propagation. It is believed that wave ducting by thin depletions of the plasma density aligned with the magnetic field accounts for such signals, and that their discrete nature is caused by the satellite intercepting individual ducts. These ducts, which were also observed as coincident decreases of the upper hybrid resonance frequency, appeared to be twenty-percent depletions roughly one hundred kilometers across. The AKR, which is emitted approximately perpendicular to the magnetic field, apparently entered these ducts equatorward of the source after the waves had been refracted parallel to the duct axis. A diffuse background was also observed which is consistent with the leakage from similar ducts at lower L-values. These observations establish the existence of ducted AKR, its signature on the satellite wave spectrograms, and new evidence for depletion ducts within the plasmasphere.

  19. Low loss duct burner

    SciTech Connect

    Mar, H. M.; Reider, S. B.

    1985-07-09

    A jet propulsion engine with a fan bypass duct includes a duct burner with a plurality of flame stabilizers therein each mounted to inner case and outer case members through spherical bearings. Each of the stabilizers consists of two blade members having integral arms thereon actuated by fore and aft motion of an external actuating ring to assume an expanded position to increase duct turbulence for mixing air flow therethrough with a fuel supply and into a retracted position against each other to reduce pressure drop under nonafterburning operation. Each of the flame stabilizer blades has a platform that controls communication between a hot air source and a duct for improving fuel vaporization during afterburner operation thereby to increase afterburning limits; the platforms close communication between the hot air source and the duct during nonafterburning operation when flame stabilization is not required.

  20. Hybrid functionals for simulating complex oxides

    NASA Astrophysics Data System (ADS)

    Franchini, Cesare

    Hybrid functionals are a class of exchange-correlation (XC) functionals in density functional theory (DFT) that are constructed by a suitable mixing of local/semi-local XC functionals (LDA/GGA) with a certain portion of the exact Hartree-Fock exchange. After being used for years in the chemistry community for studying molecular properties, hybrid functionals are being increasingly widely used for solid state problems, for which standard LDA/GGA approximations provide a defective description. In particular, hybrid functionals appear to account well for the complicated coupling between lattice, charge and spin degrees of freedom in transition metal oxides, a class of materials that has recently attracted a lot of interest due to its technological relevance (all-oxides electronics), the large spectrum of functionalities, and the many challenging issues related to strong electronic correlation. The purpose of this talk is to present the essential ideas and physical picture of hybrid functionals and to present a map of recent applications to complex oxides aiming to cover an ample spectra of cases (sp , 3 d, 4 d and 5 d compounds) and to discuss an extended array of physical phenomena including: metal-to-insulator transitions, electron localization, bandgap prediction, polarons, multiferroism, and spin-orbit coupling.

  1. Thermal performance of residential duct systems in basements

    SciTech Connect

    Treidler, B.; Modera, M.

    1994-02-01

    There are many unanswered questions about the typical effects of duct system operation on the infiltration rates and energy usage of single- family residences with HVAC systems in their basements. In this paper, results from preliminary field studies and computer simulations are used to examine the potential for improvements in efficiency of air distribution systems in such houses. The field studies comprise thermal and flow measurements on four houses in Maryland. The houses were found to have significant envelope leakage, duct leakage, and duct conduction losses. Simulations of a basement house, the characteristics of which were chosen from the measured houses, were performed to assess the energy savings potential for basement house. The simulations estimate that a nine percent reduction in space conditioning energy use is obtained by sealing eighty percent of the duct leaks and insulating ducts to an R-value of 0.88 {degree}C{center_dot}m{sup 2}/W (5{degree}F{center_dot}ft{sup 2}{center_dot}h/BTU) where they are exposed in the basement. To determine the maximum possible reduction m energy use, simulations were run with all ducts insulated to 17.6 {degree}C{center_dot}m{sup 2}/W (100 {degree}F{center_dot}ft{sup 2}{center_dot}h/BTU) and with no duct leakage. A reduction of energy use by 14% is obtained by using perfect ducts instead of nominal ducts.

  2. Development testing of throttleable ducted rockets

    NASA Astrophysics Data System (ADS)

    Besser, Hans-Ludwig

    1992-09-01

    Throttleability, being a current requirement for modern air-breathing missile propulsion systems, adds considerable complexity to the development of ducted rockets. Problems are especially inherent in the development of the following: (1) pressure sensitive propellants; (2) hot gas valves (especially for particle laden flow); and (3) ramcombustors featuring high performance over widely varying operating conditions. The use of propellant ingredients with high heating value but unfavorable combustion characteristics, like boron, is an additional challenge in the development of high energy ducted rocket systems. Extensive testing and a well conceived test philosophy are needed to achieve satisfactory development results. MBB, together with its subsidiary Bayem-Chemie, has been engaged in the field of throttleable ducted rockets for more than a decade. This paper summarizes test procedures which were established to address the strongly interrelated development problems and presents examples of test results derived from the development of a ducted rocket engine for a supersonic antiship missile.

  3. Numerical Simulation of Complex Turbomachinery Flows

    NASA Technical Reports Server (NTRS)

    Chernobrovkin, A. A.; Lakshiminarayana, B.

    1999-01-01

    An unsteady, multiblock, Reynolds Averaged Navier Stokes solver based on Runge-Kutta scheme and Pseudo-time step for turbo-machinery applications was developed. The code was validated and assessed against analytical and experimental data. It was used to study a variety of physical mechanisms of unsteady, three-dimensional, turbulent, transitional, and cooling flows in compressors and turbines. Flow over a cylinder has been used to study effects of numerical aspects on accuracy of prediction of wake decay and transition, and to modify K-epsilon models. The following simulations have been performed: (a) Unsteady flow in a compressor cascade: Three low Reynolds number turbulence models have been assessed and data compared with Euler/boundary layer predictions. Major flow features associated with wake induced transition were predicted and studied; (b) Nozzle wake-rotor interaction in a turbine: Results compared to LDV data in design and off-design conditions, and cause and effect of unsteady flow in turbine rotors were analyzed; (c) Flow in the low-pressure turbine: Assessed capability of the code to predict transitional, attached and separated flows at a wide range of low Reynolds numbers and inlet freestream turbulence intensity. Several turbulence and transition models have been employed and comparisons made to experiments; (d) leading edge film cooling at compound angle: Comparisons were made with experiments, and the flow physics of the associated vortical structures were studied; and (e) Tip leakage flow in a turbine. The physics of the secondary flow in a rotor was studied and sources of loss identified.

  4. Simulation of complex phenomena in optical fibres

    NASA Astrophysics Data System (ADS)

    Allington-Smith, Jeremy; Murray, Graham; Lemke, Ulrike

    2012-12-01

    Optical fibres are essential for many types of highly multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the nature of dark energy, requires accurate modellization of the fibre system to achieve their signal-to-noise ratio (SNR) goals. Despite their simple construction, fibres exhibit unexpected behaviour including non-conservation of etendue (focal ratio degradation, FRD) and modal noise. Furthermore, new fibre geometries (non-circular or tapered) have become available to improve the scrambling properties that, together with modal noise, limit the achievable SNR in precision spectroscopy. These issues have often been addressed by extensive tests on candidate fibres and their terminations, but these are difficult and time-consuming. Modelling by ray tracing and wave analysis is possible with commercial software packages, but these do not address the more complex features, in particular FRD. We use a phase-tracking ray-tracing method to provide a practical description of FRD derived from our previous experimental work on circular fibres and apply it to non-standard fibres. This allows the relationship between scrambling and FRD to be quantified for the first time. We find that scrambling primarily affects the shape of the near-field pattern but has negligible effect on the barycentre. FRD helps to homogenize the near-field pattern but does not make it completely uniform. Fibres with polygonal cross-section improve scrambling without amplifying the FRD. Elliptical fibres, in conjunction with tapering, may offer an efficient means of image slicing to improve the product of resolving power and throughput, but the result is sensitive to the details of illumination. We also investigated the performance of fibres close to the limiting numerical aperture since this may affect the uniformity of the SNR for some prime focus fibre instrumentation.

  5. Ranking important nodes in complex networks by simulated annealing

    NASA Astrophysics Data System (ADS)

    Sun, Yu; Yao, Pei-Yang; Wan, Lu-Jun; Shen, Jian; Zhong, Yun

    2017-02-01

    In this paper, based on simulated annealing a new method to rank important nodes in complex networks is presented. First, the concept of an importance sequence (IS) to describe the relative importance of nodes in complex networks is defined. Then, a measure used to evaluate the reasonability of an IS is designed. By comparing an IS and the measure of its reasonability to a state of complex networks and the energy of the state, respectively, the method finds the ground state of complex networks by simulated annealing. In other words, the method can construct a most reasonable IS. The results of experiments on real and artificial networks show that this ranking method not only is effective but also can be applied to different kinds of complex networks. Project supported by the National Natural Science Foundation of China (Grant No. 61573017) and the Natural Science Foundation of Shaanxi Province, China (Grant No. 2016JQ6062).

  6. Complex Organics from Laboratory Simulated Interstellar Ices

    NASA Technical Reports Server (NTRS)

    Dworkin, J. P.

    2003-01-01

    Many of the volatiles in interstellar dense clouds exist in ices surrounding dust grains. The low temperatures of these ices (T < 50 K) preclude most chemical reactions, but photolysis can drive reactions that produce a suite of new species, many of which are complex organics. We study the UV and proton radiation processing of interstellar ice analogs to explore links between interstellar chemistry, the organics in comets and meteorites, and the origin of life on Earth. The high D/H ratios in some interstellar species, and the knowledge that many of the organics in primitive meteorites are D-enriched, suggest that such links are plausible. Once identified, these species may serve as markers of interstellar heritage of cometary dust and meteorites. Of particular interest are our findings that UV photolysis of interstellar ice analogs produce molecules of importance in current living organisms, including quinones, amphiphiles, and amino acids. Quinones are essential in vital metabolic roles such as electron transport. Studies show that quinones should be made wherever polycyclic aromatic hydrocarbons are photolyzed in interstellar ices. In the case of anthracene-containing ices, we have observed the production of 9-anthrone and 9,10 anthraquinone, both of which have been observed in the Murchison meteorite. Amphiphiles are also made when mixed molecular ices are photolyzed. These amphiphiles self-assemble into fluorescent vesicles when placed in liquid water, as do Murchison extracts. Both have the ability to trap an ionic dye. Photolysis of plausible ices can also produce alanine, serine, and glycine as well as a number of small alcohols and amines. Flash heating of the room temperature residue generated by such experiments generates mass spectral distributions similar to those of IDPs. The detection of high D/H ratios in some interstellar molecular species, and the knowledge that many of the organics, such as hydroxy and amino acids, in primitive meteorites are D

  7. Complexity and significance in computer simulations of physiological systems.

    PubMed

    Kootsey, J M

    1987-06-01

    Complexity in a theoretical model may or may not be associated with a high level of arbitrariness, depending on how the model is constructed. In this paper I use examples from cardiac electrophysiology to illustrate two techniques for maintaining significance in complex simulations. First, the approaches of analysis and synthesis are compared as methods of constructing models of complex systems. When a model is constructed by synthesis of known principles, facts, and subunits, it may have any degree of complexity without losing significance; the same is not true for analysis models. Significance can also be maintained by assembling a limited model to test a specific hypothesis of mechanism.

  8. Cystic duct carcinoma mimicking a middle bile duct tumour

    PubMed Central

    Francisco, Elsa; Mendes, Miguel; Vale, Sílvio; Esteves, Joana

    2015-01-01

    Cystic duct carcinoma was defined by Farrar as a tumour restricted to the cystic duct, making it a rare disease. The authors describe a case of a cystic duct carcinoma that fulfils Farrar’s strict diagnostic criteria and that became clinically relevant by compressing the common hepatic duct, thus causing cholestasis. A cholecystectomy was performed with en bloc resection of the cystic and extrahepatic bile duct with a regional lymphadenectomy. PMID:25819819

  9. Simulating complex ion channel kinetics with IonChannelLab

    PubMed Central

    Covarrubias, Manuel; Sánchez-Rodríguez, Jorge E; Perez-Cornejo, Patricia; Arreola, Jorge

    2010-01-01

    In-silico simulation based on Markov chains is a powerful way to describe and predict the activity of many transport proteins including ion channels. However, modeling and simulation using realistic models of voltage- or ligand-gated ion channels exposed to a wide range of experimental conditions require building complex kinetic schemes and solving complicated differential equations. To circumvent these problems, we developed IonChannelLab a software tool that includes a user-friendly Graphical User Interface and a simulation library. This program supports channels with Ohmic or Goldman-Hodgkin-Katz behavior and can simulate the time-course of ionic and gating currents, single channel behavior and steady-state conditions. The program allows the simulation of experiments where voltage, ligand and ionic concentration are varied independently or simultaneously. PMID:20935453

  10. Thermal performance of residential duct systems in basements

    NASA Astrophysics Data System (ADS)

    Treidler, Burke; Modera, Mark

    1994-01-01

    There are many unanswered questions about the typical effects of duct system operation on the infiltration rates and energy usage of single-family residences with HVAC systems in their basements. Results from preliminary field studies and computer simulations are used to examine the potential for improvements in efficiency of air distribution systems in such houses. The field studies comprise thermal and flow measurements on four houses in Maryland. The houses were found to have significant envelope leakage, duct leakage, and duct conduction losses. Simulations of a basement house, the characteristics of which were chosen from the measured houses, were performed to assess the energy savings potential for basement house. The simulations estimate that a nine percent reduction in space conditioning energy use is obtained by sealing eighty percent of the duct leaks and insulating ducks to an R-value of 0.88 (C x sq. m)/W(100 F x sq. ft x h/BTU) where they are exposed in the basement. To determine the maximum possible reduction in energy use, simulations were run with all ducts insulated to (17.6 C x sq m)/W(100 F x sq. ft x h/BTU) and with no duct leakage. A reduction of energy use by 14% is obtained by using perfect ducts instead of normal ducts.

  11. Interactive Computational Algorithms for Acoustic Simulation in Complex Environments

    DTIC Science & Technology

    2015-07-19

    simualtion for urban and other complex propagation environments. The PIs will also collaborate with Stephen Ketcham and Keith Wilson at USACE and...Albert, Keith Wilson, Dinesh Manocha. Validation of 3D numerical simulation for acoustic pulse propagation in an urban environment, The Journal of

  12. Quantum simulations of small electron-hole complexes

    SciTech Connect

    Lee, M.A.; Kalia, R.K.; Vashishta, P.D.

    1984-09-01

    The Green's Function Monte Carlo method is applied to the calculation of the binding energies of electron-hole complexes in semiconductors. The quantum simulation method allows the unambiguous determination of the ground state energy and the effects of band anisotropy on the binding energy. 22 refs., 1 fig.

  13. Complex Equilibria Changing in Photochemical Reaction: Computerized Evaluation and Simulation.

    ERIC Educational Resources Information Center

    Horvath, Otto; Papp, Sandor

    1988-01-01

    States that if photochemical reactions can be followed spectrophotometrically, reactivities can be estimated by evaluating data from only one curve. Studies such a system using computerized evaluation and simulation. Uses chlorocuprate(II) complexes in acetonitrile solutions for the model systems. (MVL)

  14. Accessory Pancreatic Duct Patterns and Their Clinical Implications

    PubMed Central

    Prasanna, Lokadolalu Chandracharya; Rajagopal, KV; Thomas, Huban R

    2015-01-01

    Context and Objective: Accessory pancreatic duct (APD) designed to reduce the pressure of major pancreatic duct by forming a secondary drainage channel. Few studies have mentioned the variant types of accessory ducts and their mode of formation, some of these have a clear clinical significance. Present study is aimed to evaluate the possible variations in the APD and its terminations. Materials and Methods: Forty formalin fixed adult human pancreas with duodenum in situ specimens were studied by injecting 1% aqueous eosin, followed by piece meal dissection of the head of the pancreas from posterior surface. Formation, tributaries, relations, and the termination of the accessory pancreatic duct were noted and photographed. Results: Accessory ducts revealed 50% belonged to long type, 22.5% were of short and ansa pancreatica type each, and embryonic type of duct pattern was seen in 5% specimens. 75% of long type ducts showed positive patency with eosin dye, followed by ansa type (44.4%), and least patency was found in short type (22.2%). With regard to the patency of the accessory pancreatic ducts towards their termination, we found 52.5% of the accessory ducts and 5% of the embryonic type pancreatic ducts were patent and in 42.5% of the specimen the ducts were obliterated. In 85% of specimens the minor duodenal papillae was anterosuperior to the major papilla and superior to the major papillae in 10% of the cases, and in 5% minor papillae was absent. The average distance between the two papillae was 2.35 cm. Conclusion: The knowledge of the complex anatomical relations of the gland with its duct, duodenum and bile ducts are essential for the surgeons and sinologists to plan and perform both the diagnostic as well as therapeutic procedures effectively. PMID:25954609

  15. Physical Simulation of Investment Casting of Complex Shape Parts

    NASA Astrophysics Data System (ADS)

    Rahimian, Mehdi; Milenkovic, Srdjan; Maestro, Laura; De Azua, Aitor Eguidazu Ruiz; Sabirov, Ilchat

    2015-05-01

    Development of investment casting process has been a challenge for manufacturers of complex shape parts. Numerous experimental casting trials are typically carried out to determine the optimum casting parameters for fabrication of high-quality products. In this work, it is demonstrated that physical simulation of investment casting can successfully predict microstructure and hardness in as-cast complex shape parts. The physical simulation tool consists of a thermal model and melting/solidification experiments in thermo-mechanical simulator. The thermal model is employed to predict local cooling rate during solidification at each point of a casting. Melting/solidification experiments are carried out under controlled cooling rates estimated by the thermal model. Microstructural and mechanical characterization of the solidified specimens is performed; the obtained results predict the local microstructure and mechanical properties of the casting. This concept is applied to investment casting of complex shape nozzle guide vanes from Mar-M247 Ni-based superalloy. Experimental casting trials are performed and the outcomes of physical simulation tool are validated against experimental results. It is shown that phase composition, secondary dendrite arm spacing, grain size, γ/ γ' eutectic size and volume fraction, size and shape of carbide particles, and local microhardness can be predicted at each point of the casting via physical simulation.

  16. 91. VIEW OF OBSOLETE AIRCONDITIONING DUCTS LOCATED IN NORTHWEST CORNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    91. VIEW OF OBSOLETE AIR-CONDITIONING DUCTS LOCATED IN NORTHWEST CORNER OF ROOM, ABOVE SLC-3E AUTOPILOT EQUIPMENT. DIGITAL COUNTDOWN AND HOLD CLOCKS ON WALL LEFT OF DUCTS - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  17. Atomistic Simulation of Lignocellulosic Biomass and Associated Cellulosomal Protein Complexes

    SciTech Connect

    Petridis, Loukas; Crowley, Michael F; Smith, Jeremy C

    2010-01-01

    Computer simulations have been performed to obtain an atomic-level understanding of lignocellulose structure and the assembly of its associated cellulosomal protein complexes. First, a CHARMM molecular mechanics force field for lignin is derived and validated by performing a molecular dynamics simulation of a crystal of a lignin fragment molecule and comparing simulation-derived structural features with experimental results. Together with the existing force field for polysaccharides, this work provides the basis for full simulations of lignocellulose. Second, the underlying molecular mechanism governing the assembly of various cellulosomal modules is investigated by performing a novel free-energy calculation of the cohesin-dockerin dissociation. Our calculation indicates a free-energy barrier of ~17 kcal/mol and further reveals a stepwise dissociation pathway involving both the central -sheet interface and its adjacent solvent-exposed loop/turn regions clustered at both ends of the -barrel structure.

  18. Complex molecular assemblies at hand via interactive simulations.

    PubMed

    Delalande, Olivier; Férey, Nicolas; Grasseau, Gilles; Baaden, Marc

    2009-11-30

    Studying complex molecular assemblies interactively is becoming an increasingly appealing approach to molecular modeling. Here we focus on interactive molecular dynamics (IMD) as a textbook example for interactive simulation methods. Such simulations can be useful in exploring and generating hypotheses about the structural and mechanical aspects of biomolecular interactions. For the first time, we carry out low-resolution coarse-grain IMD simulations. Such simplified modeling methods currently appear to be more suitable for interactive experiments and represent a well-balanced compromise between an important gain in computational speed versus a moderate loss in modeling accuracy compared to higher resolution all-atom simulations. This is particularly useful for initial exploration and hypothesis development for rare molecular interaction events. We evaluate which applications are currently feasible using molecular assemblies from 1900 to over 300,000 particles. Three biochemical systems are discussed: the guanylate kinase (GK) enzyme, the outer membrane protease T and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors complex involved in membrane fusion. We induce large conformational changes, carry out interactive docking experiments, probe lipid-protein interactions and are able to sense the mechanical properties of a molecular model. Furthermore, such interactive simulations facilitate exploration of modeling parameters for method improvement. For the purpose of these simulations, we have developed a freely available software library called MDDriver. It uses the IMD protocol from NAMD and facilitates the implementation and application of interactive simulations. With MDDriver it becomes very easy to render any particle-based molecular simulation engine interactive. Here we use its implementation in the Gromacs software as an example.

  19. Scale Model Experiments on Sound Propagation From a Mach 2.5 Cold Nitrogen Jet Flowing Through a Rigid-Walled Duct With a J-Deflector

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Vu, Bruce

    2003-01-01

    The Launch Systems Testbed (LST) represents the evolution of vibroacoustics research and development work performed at NASA John F. Kennedy Space Center (KSC) over the last 15 years. The LST is located at the Launch Equipment Test Facility (LETF) in the KSC industrial complex. The LETF is operated by Sierra Lobo, Inc., as a member of University-Affiliated Technology Development Contract (USTDC) to KSC Spaceport and Engineering and Technology Directorate (YA), with ASRC Aerospace Corporation as a the prime contractor. Trajectory Simulation Mechanism (TSM) is a major component of the LST, developed specifically to simulate nonstationary acoustic loads on launch pad structures, vehicles, and payloads. TSM enhances the capabilities within LST for simulating launch environments of future vehicles. The scaled launch environments will be used to predict the full-scale launch environment via an appropriate scaling procedure. Air Force Research Laboratory (AFRL) has tasked NASA KSC to perform a basic technology test program in support of developing a low-cost clean pad (incorporating passive mitigation techniques) for future launch vehicles. The overall goal of the program is to develop innovative launch exhaust management systems, which effectively reduce launch acoustic environment with innovative duct designs, while eliminating traditional sound suppression water systems. Passive techniques, such as nontraditional duct geometries, resonators, and diffusers, etc., will be investigated. The overall goals are to advance innovative concepts for a clean pad while developing ideas to reduce transmitted sound via investigation and modeling of jet exhaust acoustic and flow field characteristics. The series of tests outlined in this report represent baseline tests and are geared towards defining the acoustic load environment on the TSM pad for open and closed duct configurations. This report summarizes the cold jet acoustic testing for Mach 2.5 supersonic nitrogen jet issuing

  20. Large-Eddy Simulations of Flows in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Kosovic, B.; Lundquist, K. A.

    2011-12-01

    Large-eddy simulation as a methodology for numerical simulation of turbulent flows was first developed to study turbulent flows in atmospheric by Lilly (1967). The first LES were carried by Deardorff (1970) who used these simulations to study atmospheric boundary layers. Ever since, LES has been extensively used to study canonical atmospheric boundary layers, in most cases flat plate boundary layers under the assumption of horizontal homogeneity. Carefully designed LES of canonical convective and neutrally stratified and more recently stably stratified atmospheric boundary layers have contributed significantly to development of better understanding of these flows and their parameterizations in large scale models. These simulations were often carried out using codes specifically designed and developed for large-eddy simulations of horizontally homogeneous flows with periodic lateral boundary conditions. Recent developments in multi-scale numerical simulations of atmospheric flows enable numerical weather prediction (NWP) codes such as ARPS (Chow and Street, 2009), COAMPS (Golaz et al., 2009) and Weather Research and Forecasting model, to be used nearly seamlessly across a wide range of atmospheric scales from synoptic down to turbulent scales in atmospheric boundary layers. Before we can with confidence carry out multi-scale simulations of atmospheric flows, NWP codes must be validated for accurate performance in simulating flows over complex or inhomogeneous terrain. We therefore carry out validation of WRF-LES for simulations of flows over complex terrain using data from Askervein Hill (Taylor and Teunissen, 1985, 1987) and METCRAX (Whiteman et al., 2008) field experiments. WRF's nesting capability is employed with a one-way nested inner domain that includes complex terrain representation while the coarser outer nest is used to spin up fully developed atmospheric boundary layer turbulence and thus represent accurately inflow to the inner domain. LES of a

  1. The future of simulation technologies for complex cardiovascular procedures.

    PubMed

    Cates, Christopher U; Gallagher, Anthony G

    2012-09-01

    Changing work practices and the evolution of more complex interventions in cardiovascular medicine are forcing a paradigm shift in the way doctors are trained. Implantable cardioverter defibrillator (ICD), transcatheter aortic valve implantation (TAVI), carotid artery stenting (CAS), and acute stroke intervention procedures are forcing these changes at a faster pace than in other disciplines. As a consequence, cardiovascular medicine has had to develop a sophisticated understanding of precisely what is meant by 'training' and 'skill'. An evolving conclusion is that procedure training on a virtual reality (VR) simulator presents a viable current solution. These simulations should characterize the important performance characteristics of procedural skill that have metrics derived and defined from, and then benchmarked to experienced operators (i.e. level of proficiency). Simulation training is optimal with metric-based feedback, particularly formative trainee error assessments, proximate to their performance. In prospective, randomized studies, learners who trained to a benchmarked proficiency level on the simulator performed significantly better than learners who were traditionally trained. In addition, cardiovascular medicine now has available the most sophisticated virtual reality simulators in medicine and these have been used for the roll-out of interventions such as CAS in the USA and globally with cardiovascular society and industry partnered training programmes. The Food and Drug Administration has advocated the use of VR simulation as part of the approval of new devices and the American Board of Internal Medicine has adopted simulation as part of its maintenance of certification. Simulation is rapidly becoming a mainstay of cardiovascular education, training, certification, and the safe adoption of new technology. If cardiovascular medicine is to continue to lead in the adoption and integration of simulation, then, it must take a proactive position in the

  2. CORNICE DUCT SYSTEM

    SciTech Connect

    Wayne Place; Chuck Ladd; TC Howard

    2002-12-01

    SYNERGETICS, INC., is in the process of designing, developing, and testing 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. 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. A patent has been submitted, refined based on feedback from the patent office, and resubmitted. Additional refinements to the design will lead to additional claims being added to the patent in the near future. Designs are being finalized for a refined version that will be fabricated and tested in the same residential laboratory house. Work is expected to be complete on this project in April of 2003.

  3. Particle deposition in ventilation ducts

    SciTech Connect

    Sippola, Mark Raymond

    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

  4. Interactive Acoustic Simulation in Urban and Complex Environments

    DTIC Science & Technology

    2015-03-21

    SECURITY CLASSIFICATION OF: Report developed under Topic #A11a-T006, contract W911NF-13-C-0037. Outdoor acoustics simulation plays a vital role in...several military and commercial applications. State-of-the-art outdoor acoustics prediction methods are restricted, slow, or limited to simple...environments. Specifically, no existing method can simultaneously model atmospheric acoustical phenomena, surface interactions due to complex objects, along

  5. Effectiveness of duct cleaning methods on newly installed duct surfaces.

    PubMed

    Holopainen, R; Asikainen, V; Tuomainen, M; Björkroth, M; Pasanen, P; Seppänen, O

    2003-09-01

    Two kinds of air duct cleaning methods, mechanical brushing with different brushes and compressed air cleaning, were compared in the laboratory and in newly built buildings. The ducts were contaminated either with test dust or with dust originated from a construction site. The amount of dust on the duct surface was measured with the vacuum test method and estimated visually before and after the cleaning. In addition, the cleaning times of the different techniques were compared and the amount of residual oil in the ducts was measured in the laboratory test. The brushing methods were more efficient in metal ducts, and compressed air cleaning was more efficient in plastic ducts. After the duct cleaning the mean amount of residual dust on the surface of the ducts was ducts contaminated at construction site and ducts cleaned in the laboratory or in the building site, respectively. The oil residues and the dust stuck onto the oil were difficult to scrape off and remove, and none of the cleaning methods were capable of cleaning the oily duct surfaces efficiently enough. Thus new installations should consist only of oil-free ducts.

  6. Duct thermal performance models for large commercial buildings

    SciTech Connect

    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, assess the impacts of

  7. Large-scale simulations of complex physical systems

    NASA Astrophysics Data System (ADS)

    Belić, A.

    2007-04-01

    Scientific computing has become a tool as vital as experimentation and theory for dealing with scientific challenges of the twenty-first century. Large scale simulations and modelling serve as heuristic tools in a broad problem-solving process. High-performance computing facilities make possible the first step in this process - a view of new and previously inaccessible domains in science and the building up of intuition regarding the new phenomenology. The final goal of this process is to translate this newly found intuition into better algorithms and new analytical results. In this presentation we give an outline of the research themes pursued at the Scientific Computing Laboratory of the Institute of Physics in Belgrade regarding large-scale simulations of complex classical and quantum physical systems, and present recent results obtained in the large-scale simulations of granular materials and path integrals.

  8. A perspective on modeling and simulation of complex dynamical systems

    NASA Astrophysics Data System (ADS)

    Åström, K. J.

    2011-09-01

    There has been an amazing development of modeling and simulation from its beginning in the 1920s, when the technology was available only at a handful of University groups who had access to a mechanical differential analyzer. Today, tools for modeling and simulation are available for every student and engineer. This paper gives a perspective on the development with particular emphasis on technology and paradigm shifts. Modeling is increasingly important for design and operation of complex natural and man-made systems. Because of the increased use of model based control such as Kalman filters and model predictive control, models are also appearing as components of feedback systems. Modeling and simulation are multidisciplinary, it is used in a wide variety of fields and their development have been strongly influenced by mathematics, numerics, computer science and computer technology.

  9. Simulations of Sea Level Rise Effects on Complex Coastal Systems

    NASA Astrophysics Data System (ADS)

    Niedoroda, A. W.; Ye, M.; Saha, B.; Donoghue, J. F.; Reed, C. W.

    2009-12-01

    It is now established that complex coastal systems with elements such as beaches, inlets, bays, and rivers adjust their morphologies according to time-varying balances in between the processes that control the exchange of sediment. Accelerated sea level rise introduces a major perturbation into the sediment-sharing systems. A modeling framework based on a new SL-PR model which is an advanced version of the aggregate-scale CST Model and the event-scale CMS-2D and CMS-Wave combination have been used to simulate the recent evolution of a portion of the Florida panhandle coast. This combination of models provides a method to evaluate coefficients in the aggregate-scale model that were previously treated as fitted parameters. That is, by carrying out simulations of a complex coastal system with runs of the event-scale model representing more than a year it is now possible to directly relate the coefficients in the large-scale SL-PR model to measureable physical parameters in the current and wave fields. This cross-scale modeling procedure has been used to simulate the shoreline evolution at the Santa Rosa Island, a long barrier which houses significant military infrastructure at the north Gulf Coast. The model has been used to simulate 137 years of measured shoreline change and to extend these to predictions of future rates of shoreline migration.

  10. Bile Duct (Cholangiocarcinoma) Cancer: Radiation Therapy

    MedlinePlus

    ... Situation Bile Duct Cancer Treating Bile Duct Cancer Radiation Therapy for Bile Duct Cancer Radiation therapy uses ... of radiation for bile duct cancer. External beam radiation therapy (EBRT) This type of radiation therapy uses ...

  11. Prediction of ducted fan performance

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1972-01-01

    Computer program to predict performance of ducted fan combination at specified advance ratio and angle of attack is described. Parameters affecting performance of ducted fan are presented. Information obtained from computer program is explained for various conditions considered.

  12. Governance of complex systems: results of a sociological simulation experiment.

    PubMed

    Adelt, Fabian; Weyer, Johannes; Fink, Robin D

    2014-01-01

    Social sciences have discussed the governance of complex systems for a long time. The following paper tackles the issue by means of experimental sociology, in order to investigate the performance of different modes of governance empirically. The simulation framework developed is based on Esser's model of sociological explanation as well as on Kroneberg's model of frame selection. The performance of governance has been measured by means of three macro and two micro indicators. Surprisingly, central control mostly performs better than decentralised coordination. However, results not only depend on the mode of governance, but there is also a relation between performance and the composition of actor populations, which has yet not been investigated sufficiently. Practitioner Summary: Practitioners can gain insights into the functioning of complex systems and learn how to better manage them. Additionally, they are provided with indicators to measure the performance of complex systems.

  13. Computer Simulations and Theoretical Studies of Complex Systems: from complex fluids to frustrated magnets

    NASA Astrophysics Data System (ADS)

    Choi, Eunsong

    Computer simulations are an integral part of research in modern condensed matter physics; they serve as a direct bridge between theory and experiment by systemactically applying a microscopic model to a collection of particles that effectively imitate a macroscopic system. In this thesis, we study two very differnt condensed systems, namely complex fluids and frustrated magnets, primarily by simulating classical dynamics of each system. In the first part of the thesis, we focus on ionic liquids (ILs) and polymers--the two complementary classes of materials that can be combined to provide various unique properties. The properties of polymers/ILs systems, such as conductivity, viscosity, and miscibility, can be fine tuned by choosing an appropriate combination of cations, anions, and polymers. However, designing a system that meets a specific need requires a concrete understanding of physics and chemistry that dictates a complex interplay between polymers and ionic liquids. In this regard, molecular dynamics (MD) simulation is an efficient tool that provides a molecular level picture of such complex systems. We study the behavior of Poly (ethylene oxide) (PEO) and the imidazolium based ionic liquids, using MD simulations and statistical mechanics. We also discuss our efforts to develop reliable and efficient classical force-fields for PEO and the ionic liquids. The second part is devoted to studies on geometrically frustrated magnets. In particular, a microscopic model, which gives rise to an incommensurate spiral magnetic ordering observed in a pyrochlore antiferromagnet is investigated. The validation of the model is made via a comparison of the spin-wave spectra with the neutron scattering data. Since the standard Holstein-Primakoff method is difficult to employ in such a complex ground state structure with a large unit cell, we carry out classical spin dynamics simulations to compute spin-wave spectra directly from the Fourier transform of spin trajectories. We

  14. 12. SANDSORTING BUILDING, THIRD FLOOR, VIBRATING SCREENS ON RIGHT, DUCT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. SAND-SORTING BUILDING, THIRD FLOOR, VIBRATING SCREENS ON RIGHT, DUCT FOR DUST COLLECTION SYSTEM IN FOREGROUND, LOOKING NORTH - Mill "C" Complex, Sand-Sorting Building, South of Dee Bennet Road, near Illinois River, Ottawa, La Salle County, IL

  15. 76. DETAIL OF AIRCONDITIONING DUCT BETWEEN PORTABLE PAYLOAD AIRCONDITIONING SYSTEM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    76. DETAIL OF AIR-CONDITIONING DUCT BETWEEN PORTABLE PAYLOAD AIR-CONDITIONING SYSTEM AND LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  16. 54. DETAIL OF AIRCONDITIONING EXHAUST DUCTS ON NORTH FACE OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. DETAIL OF AIR-CONDITIONING EXHAUST DUCTS ON NORTH FACE OF ERECT UMBILICAL MAST - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  17. 40. VIEW INTO MST CUPOLA FROM STATION 124. DUCT HEATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. VIEW INTO MST CUPOLA FROM STATION 124. DUCT HEATER FOR STATION 135 AT TOP LEFT OF PHOTOGRAPH. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  18. 23. A detailed interior view of the duct and delivery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. A detailed interior view of the duct and delivery equipment situated in the upper grain conveyor structure of Elevator and Silo Complex B (1932). - Quaker Oats Cereal Factory, Southeast corner of Broadway & Mill Streets, Akron, Summit County, OH

  19. Isolated Pancreatic Uncinate Duct IPMN.

    PubMed

    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.

  20. Duct Leakage Repeatability Testing

    SciTech Connect

    Walker, Iain; Sherman, Max

    2014-08-01

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

  1. Methods for simulating the dynamics of complex biological processes.

    PubMed

    Schilstra, Maria J; Martin, Stephen R; Keating, Sarah M

    2008-01-01

    In this chapter, we provide the basic information required to understand the central concepts in the modeling and simulation of complex biochemical processes. We underline the fact that most biochemical processes involve sequences of interactions between distinct entities (molecules, molecular assemblies), and also stress that models must adhere to the laws of thermodynamics. Therefore, we discuss the principles of mass-action reaction kinetics, the dynamics of equilibrium and steady state, and enzyme kinetics, and explain how to assess transition probabilities and reactant lifetime distributions for first-order reactions. Stochastic simulation of reaction systems in well-stirred containers is introduced using a relatively simple, phenomenological model of microtubule dynamic instability in vitro. We demonstrate that deterministic simulation [by numerical integration of coupled ordinary differential equations (ODE)] produces trajectories that would be observed if the results of many rounds of stochastic simulation of the same system were averaged. In Section V, we highlight several practical issues with regard to the assessment of parameter values. We draw some attention to the development of a standard format for model storage and exchange, and provide a list of selected software tools that may facilitate the model building process, and can be used to simulate the modeled systems.

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

    SciTech Connect

    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.

  3. Size limitations in semicircular duct systems

    PubMed

    Muller

    1999-06-07

    The present article discusses mechanical requirements and limitations which are applicable to the construction of the system of semicircular ducts, especially to its size. The simplified case of a single, uniform duct system has been considered which can be described by a second order equation of motion. The principal functional quantities for this rotation-sensor are: (1) response speed; (2) sensitivity; and (3) regular flow. The response speed of a single, uniform semicircular duct is characterized by the short time constant (T2) which is dependent on the duct radius (r). Its estimated range is from 0.04 ms in the smallest to 140 ms in the largest known labyrinth. The sensitivity is characterized by the maximal endolymph displacement after a step stimulus (xmax). Its estimated range is from 0.0016 &mgr;m to 5.97 mm (6.56 decades!), assuming an input angular velocity of omega=1 rad s-1. The Reynolds number is a measure for an undisturbed laminar flow. Its estimated range varies from 7.38.10(-4)to 45.1 for omega=1 rad s-1. The above data follow from graphs in which, for a single uniform duct, circuit radius (R) is plotted against duct radius (r) for labyrinths of 233 species belonging to different vertebrate-groups. A relation R =38.9. r1.60was determined. The smallest labyrinth was found in a carp larva (Cyprinus), the largest in a whale shark (Rhincodon). Large whales possess labyrinths of average mammalian size. It is revealed that semicircular duct size is bound by requirements concerning regular flow and by a too low response speed for large labyrinths, and by a too low sensitivity for small labyrinths. Other important quantities are mechanical amplification factors which are a consequence of more complex vestibular constructions than a single uniform duct circuit. Allometric relationships are interpreted as compromises between the quantities mentioned. A hypothesis for the relatively large semicircular duct sizes of fishes, especially Elasmobranchii, compared

  4. Cornice Duct System

    SciTech Connect

    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.

  5. Simulating an Extreme Wind Event in a Topographically Complex Region

    NASA Astrophysics Data System (ADS)

    Lennard, Christopher

    2014-07-01

    Complex topography modifies local weather characteristics such as air temperature, rainfall and airflow within a larger regional extent. The Cape Peninsula around Cape Town, South Africa, is a complex topographical feature responsible for the modification of rainfall and wind fields largely downstream of the Peninsula. During the passage of a cold front on 2 October 2002, an extreme wind event associated with tornado-like damage occurred in the suburb of Manenberg, however synoptic conditions did not indicate convective activity typically associated with a tornado. A numerical regional climate model was operated at very high horizontal resolution (500 m) to investigate the dynamics of the event. The model simulated an interaction between the topography of the peninsula and an airflow direction change associated with the passage of the cold front. A small region of cyclonic circulation was simulated over Manenberg that was embedded in an area of negative vorticity and a leeward gravity wave. The feature lasted 14 min and moved in a north to south direction. Vertically, it was not evident above 220 m. The model assessment describes this event as a shallow but intense cyclonic vortex generated in the lee of the peninsula through an interaction between the peninsula and a change in wind direction as the cold front made landfall. The model did not simulate wind speeds associated with the observed damage suggesting that the horizontal grid resolution ought to be at the scale of the event to more completely understand such microscale airflow phenomena.

  6. Aspect ratio effect on particle transport in turbulent duct flows

    NASA Astrophysics Data System (ADS)

    Noorani, A.; Vinuesa, R.; Brandt, L.; Schlatter, P.

    2016-11-01

    The dynamics of dilute micron-sized spherical inertial particles in turbulent duct flows is studied by means of direct numerical simulations of the carrier phase turbulence with one-way coupled Lagrangian particles. The geometries are a square and a rectangular duct with width-to-height aspect ratio AR of 3 operating at Reτ,c = 360 (based on the centerplane friction velocity and duct half-height). The present study is designed to determine the effect of turbulence-driven secondary motion on the particle dynamics. Our results show that a weak cross-flow secondary motion significantly changes the cross-sectional map of the particle concentration, mean velocity, and fluctuations. As the geometry of the duct is widened from AR = 1 to 3, the secondary vortex on the horizontal wall significantly expands in the spanwise direction, and although the kinetic energy of the secondary flow increases close to the corner, it decays towards the duct centreplane in the AR = 3 case so as the turbulent carrier phase approaches the behavior in spanwise-periodic channel flows, a fact that significantly affects the particle statistics. In the square duct the particle concentration in the viscous sublayer is maximum at the duct centreplane, whereas the maximum is found closer to the corner, at a distance of |z/h| ≈ 1.25 from the centreplane, in the AR = 3 case. Interestingly the centreplane concentration in the rectangular duct is around 3 times lower than that in the square duct. Moreover, a second peak in the accumulation distribution is found right at the corners for both ducts. At this location the concentration increases with particle inertia. The secondary motion changes also the cross-stream map of the particle velocities significantly in comparison to the fluid flow statistics. These directly affect the particle velocity fluctuations such that multiple peaks appear near the duct walls for the particle streamwise and wall-normal velocity fluctuations.

  7. Auditory perception of note transitions in simulated complex bowing patterns.

    PubMed

    Schoonderwaldt, Erwin; Demoucron, Matthias; Altenmüller, Eckart; Leman, Marc

    2013-06-01

    Recent motion-capture measurements of violin bowing revealed an interesting coordination behavior in fast repetitive bowing patterns involving bow changes and string crossings; bow changes were consistently lagging behind string crossings, and the relative timing appeared to be an integral part of the bow-movement patterns. The aim of the current study was to investigate if there might be a perceptual explanation for the observed coordination behavior. For this purpose a virtual violin was used, controlled by simulated bowing gestures. A simplified coordination model is presented, which was implemented to allow real-time control of complex bowing patterns. This synthesis approach was employed in a perceptual experiment in which the participants were asked to optimize the sound by adjusting a slider controlling the main coordination parameters. It was found that the resulting coordination patterns were similar to those observed in performance, implying that complex bowing trajectories for an important part emerge from auditory-motor interaction. Further analysis of the responses shed light on temporal and spatial constraints of the simulated gestures associated with the note transitions. The results raise interesting questions with regard to auditory-motor interaction in complex instrumental control gestures.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. High performance ultrasonic field simulation on complex geometries

    NASA Astrophysics Data System (ADS)

    Chouh, H.; Rougeron, G.; Chatillon, S.; Iehl, J. C.; Farrugia, J. P.; Ostromoukhov, V.

    2016-02-01

    Ultrasonic field simulation is a key ingredient for the design of new testing methods as well as a crucial step for NDT inspection simulation. As presented in a previous paper [1], CEA-LIST has worked on the acceleration of these simulations focusing on simple geometries (planar interfaces, isotropic materials). In this context, significant accelerations were achieved on multicore processors and GPUs (Graphics Processing Units), bringing the execution time of realistic computations in the 0.1 s range. In this paper, we present recent works that aim at similar performances on a wider range of configurations. We adapted the physical model used by the CIVA platform to design and implement a new algorithm providing a fast ultrasonic field simulation that yields nearly interactive results for complex cases. The improvements over the CIVA pencil-tracing method include adaptive strategies for pencil subdivisions to achieve a good refinement of the sensor geometry while keeping a reasonable number of ray-tracing operations. Also, interpolation of the times of flight was used to avoid time consuming computations in the impulse response reconstruction stage. To achieve the best performance, our algorithm runs on multi-core superscalar CPUs and uses high performance specialized libraries such as Intel Embree for ray-tracing, Intel MKL for signal processing and Intel TBB for parallelization. We validated the simulation results by comparing them to the ones produced by CIVA on identical test configurations including mono-element and multiple-element transducers, homogeneous, meshed 3D CAD specimens, isotropic and anisotropic materials and wave paths that can involve several interactions with interfaces. We show performance results on complete simulations that achieve computation times in the 1s range.

  10. Simulation and Processing Seismic Data in Complex Geological Models

    NASA Astrophysics Data System (ADS)

    Forestieri da Gama Rodrigues, S.; Moreira Lupinacci, W.; Martins de Assis, C. A.

    2014-12-01

    Seismic simulations in complex geological models are interesting to verify some limitations of seismic data. In this project, different geological models were designed to analyze some difficulties encountered in the interpretation of seismic data. Another idea is these data become available for LENEP/UENF students to test new tools to assist in seismic data processing. The geological models were created considering some characteristics found in oil exploration. We simulated geological medium with volcanic intrusions, salt domes, fault, pinch out and layers more distante from surface (Kanao, 2012). We used the software Tesseral Pro to simulate the seismic acquisitions. The acquisition geometries simulated were of the type common offset, end-on and split-spread. (Figure 1) Data acquired with constant offset require less processing routines. The processing flow used with tools available in Seismic Unix package (for more details, see Pennington et al., 2005) was geometric spreading correction, deconvolution, attenuation correction and post-stack depth migration. In processing of the data acquired with end-on and split-spread geometries, we included velocity analysis and NMO correction routines. Although we analyze synthetic data and carefully applied each processing routine, we can observe some limitations of the seismic reflection in imaging thin layers, great surface depth layers, layers with low impedance contrast and faults.

  11. Computer simulation of supramolecular assembly by metal-ligand complexation

    NASA Astrophysics Data System (ADS)

    Wang, Shihu; Chen, Chun-Chung; Dormidontova, Elena E.

    2006-03-01

    Monte Carlo simulations were employed to study the supramolecular assembly of oligomers end-functionalized by ligands capable of complexation with metal ions. The properties of these metallo-supramolecular polymers strongly depend on the oligomer concentration, strength of complexation, and metal-to- ligand ratio. At high oligomer concentration the average molecular weight exhibits a maximum near the stoichiometric composition and decreases for higher or lower metal content. On the other hand, at low oligomer concentration the molecular weight shows a local minimum around the stoichiometric composition. This unusual behavior is attributed to the larger population of small rings around the stoichiometric composition, which make up a significant fraction of the overall molecular weight at low oligomer concentration. This effect is especially pronounced at low temperature, where the fraction of rings is higher. The fraction of chains and rings for different concentrations, temperatures and oligomer lengths were calculated and compared with experimental data.

  12. Molecular dynamics simulations of DNA-polycation complexes

    NASA Astrophysics Data System (ADS)

    Ziebarth, Jesse; Wang, Yongmei

    2008-03-01

    A necessary step in the preparation of DNA for use in gene therapy is the packaging of DNA with a vector that can condense DNA and provide protection from degrading enzymes. Because of the immunoresponses caused by viral vectors, there has been interest in developing synthetic gene therapy vectors, with polycations emerging as promising candidates. Molecular dynamics simulations of the DNA duplex CGCGAATTCGCG in the presence of 20 monomer long sequences of the polycations, poly-L-lysine (PLL) and polyethyleneimine (PEI), with explicit counterions and TIP3P water, are performed to provide insight into the structure and formation of DNA polyplexes. After an initial separation of approximately 50 å, the DNA and polycation come together and form a stable complex within 10 ns. The DNA does not undergo any major structural changes upon complexation and remains in the B-form. In the formed complex, the charged amine groups of the polycation mainly interact with DNA phosphate groups, and rarely occupy electronegative sites in either the major or minor grooves. Differences between complexation with PEI and PLL will be discussed.

  13. Complicated bile duct stones

    PubMed Central

    Roy, Ashwin; Martin, Derrick

    2013-01-01

    Common bile duct stones (CBDSs) are solid deposits that can either form within the gallbladder or migrate to the common bile duct (CBD), or form de novo in the biliary tree. In the USA around 15% of the population have gallstones and of these, 3% present with symptoms annually. Because of this, there have been major advancements in the management of gallstones and related conditions. Management is based on the patient's risk profile; young and healthy patients are likely to be recommended for surgery and elderly patients with comorbidities are usually recommended for endoscopic procedures. Imaging of gallstones has advanced in the last 30 years with endoscopic retrograde cholangiopancreatography evolving from a diagnostic to a therapeutic procedure in removing CBDSs. We present a complicated case of a patient with a CBDS and periampullary diverticulum and discuss the techniques used to diagnose and remove the stone from the biliary system. PMID:23946532

  14. GPU-enabled molecular dynamics simulations of ankyrin kinase complex

    NASA Astrophysics Data System (ADS)

    Gautam, Vertika; Chong, Wei Lim; Wisitponchai, Tanchanok; Nimmanpipug, Piyarat; Zain, Sharifuddin M.; Rahman, Noorsaadah Abd.; Tayapiwatana, Chatchai; Lee, Vannajan Sanghiran

    2014-10-01

    The ankyrin repeat (AR) protein can be used as a versatile scaffold for protein-protein interactions. It has been found that the heterotrimeric complex between integrin-linked kinase (ILK), PINCH, and parvin is an essential signaling platform, serving as a convergence point for integrin and growth-factor signaling and regulating cell adhesion, spreading, and migration. Using ILK-AR with high affinity for the PINCH1 as our model system, we explored a structure-based computational protocol to probe and characterize binding affinity hot spots at protein-protein interfaces. In this study, the long time scale dynamics simulations with GPU accelerated molecular dynamics (MD) simulations in AMBER12 have been performed to locate the hot spots of protein-protein interaction by the analysis of the Molecular Mechanics-Poisson-Boltzmann Surface Area/Generalized Born Solvent Area (MM-PBSA/GBSA) of the MD trajectories. Our calculations suggest good binding affinity of the complex and also the residues critical in the binding.

  15. Building Blocks for Reliable Complex Nonlinear Numerical Simulations. Chapter 2

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    This chapter describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to turbulent flow computations are included.

  16. Building Blocks for Reliable Complex Nonlinear Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    2005-01-01

    This chapter describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations.

  17. Building Blocks for Reliable Complex Nonlinear Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Mansour, Nagi N. (Technical Monitor)

    2002-01-01

    This talk describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler and Navier-Stokes equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to turbulent flow computations are included.

  18. Numerical simulation of radiation fog in complex terrain

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Musson-Genon, L.; Carissimo, B.; Dupont, E.

    2009-09-01

    The interest for micro-scale modeling of the atmosphere is growing for environmental applications related, for example, to energy production, transport and urban development. The turbulence in the stable layers where pollutant dispersion is low and can lead to strong pollution events. This could be further complicated by the presence of clouds or fog and is specifically difficult in urban or industrial area due to the presence of buildings. In this context, radiation fog formation and dissipation over complex terrain were therefore investigated with a state-of-the-art model. This study is divided into two phases. The first phase is a pilot stage, which consist of employing a database from the ParisFog campaign which took place in the south of Paris during winter 2006-07 to assess the ability of the cloud model to reproduce the detailed structure of radiation fog. The second phase use the validated model for the study of influence of complex terrain on fog evolution. Special attention is given to the detailed and complete simulations and validation technique used is to compare the simulated results using the 3D cloud model of computational fluid dynamical software Code_Saturne with one of the best collected in situ data during the ParisFog campaign. Several dynamical, microphysical parameterizations and simulation conditions have been described. The resulting 3D cloud model runs at a horizontal resolution of 30 m and a vertical resolution comparable to the 1D model. First results look very promising and are able to reproduce the spatial distribution of fog. The analysis of the behavior of the different parameterized physical processes suggests that the subtle balance between the various processes is achieved.

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

    PubMed

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

    2012-04-01

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

  20. Numerical Methods and Simulations of Complex Multiphase Flows

    NASA Astrophysics Data System (ADS)

    Brady, Peter

    Multiphase flows are an important part of many natural and technological phenomena such as ocean-air coupling (which is important for climate modeling) and the atomization of liquid fuel jets in combustion engines. The unique challenges of multiphase flow often make analytical solutions to the governing equations impossible and experimental investigations very difficult. Thus, high-fidelity numerical simulations can play a pivotal role in understanding these systems. This dissertation describes numerical methods developed for complex multiphase flows and the simulations performed using these methods. First, the issue of multiphase code verification is addressed. Code verification answers the question "Is this code solving the equations correctly?" The method of manufactured solutions (MMS) is a procedure for generating exact benchmark solutions which can test the most general capabilities of a code. The chief obstacle to applying MMS to multiphase flow lies in the discontinuous nature of the material properties at the interface. An extension of the MMS procedure to multiphase flow is presented, using an adaptive marching tetrahedron style algorithm to compute the source terms near the interface. Guidelines for the use of the MMS to help locate coding mistakes are also detailed. Three multiphase systems are then investigated: (1) the thermocapillary motion of three-dimensional and axisymmetric drops in a confined apparatus, (2) the flow of two immiscible fluids completely filling an enclosed cylinder and driven by the rotation of the bottom endwall, and (3) the atomization of a single drop subjected to a high shear turbulent flow. The systems are simulated numerically by solving the full multiphase Navier-Stokes equations coupled to the various equations of state and a level set interface tracking scheme based on the refined level set grid method. The codes have been parallelized using MPI in order to take advantage of today's very large parallel computational

  1. The Eemian climate simulated by two models of different complexities

    NASA Astrophysics Data System (ADS)

    Nikolova, Irina; Yin, Qiuzhen; Berger, Andre; Singh, Umesh; Karami, Pasha

    2013-04-01

    The Eemian period, also known as MIS-5, experienced warmer than today climate, reduction in ice sheets and important sea-level rise. These interesting features have made the Eemian appropriate to evaluate climate models when forced with astronomical and greenhouse gas forcings different from today. In this work, we present the simulated Eemian climate by two climate models of different complexities, LOVECLIM (LLN Earth system model of intermediate complexity) and CCSM3 (NCAR atmosphere-ocean general circulation model). Feedbacks from sea ice, vegetation, monsoon and ENSO phenomena are discussed to explain the regional similarities/dissimilarities in both models with respect to the pre-industrial (PI) climate. Significant warming (cooling) over almost all the continents during boreal summer (winter) leads to a largely increased (reduced) seasonal contrast in the northern (southern) hemisphere, mainly due to the much higher (lower) insolation received by the whole Earth in boreal summer (winter). The arctic is warmer than at PI through the whole year, resulting from its much higher summer insolation and its remnant effect in the following fall-winter through the interactions between atmosphere, ocean and sea ice. Regional discrepancies exist in the sea-ice formation zones between the two models. Excessive sea-ice formation in CCSM3 results in intense regional cooling. In both models intensified African monsoon and vegetation feedback are responsible for the cooling during summer in North Africa and on the Arabian Peninsula. Over India precipitation maximum is found further west, while in Africa the precipitation maximum migrates further north. Trees and grassland expand north in Sahel/Sahara, trees being more abundant in the results from LOVECLIM than from CCSM3. A mix of forest and grassland occupies continents and expand deep in the high northern latitudes in line with proxy records. Desert areas reduce significantly in Northern Hemisphere, but increase in North

  2. Monte Carlo simulations of systems with complex energy landscapes

    NASA Astrophysics Data System (ADS)

    Wüst, T.; Landau, D. P.; Gervais, C.; Xu, Y.

    2009-04-01

    Non-traditional Monte Carlo simulations are a powerful approach to the study of systems with complex energy landscapes. After reviewing several of these specialized algorithms we shall describe the behavior of typical systems including spin glasses, lattice proteins, and models for "real" proteins. In the Edwards-Anderson spin glass it is now possible to produce probability distributions in the canonical ensemble and thermodynamic results of high numerical quality. In the hydrophobic-polar (HP) lattice protein model Wang-Landau sampling with an improved move set (pull-moves) produces results of very high quality. These can be compared with the results of other methods of statistical physics. A more realistic membrane protein model for Glycophorin A is also examined. Wang-Landau sampling allows the study of the dimerization process including an elucidation of the nature of the process.

  3. MOLECULAR SIMULATION OF PHASE EQUILIBRIA FOR COMPLEX FLUIDS

    SciTech Connect

    Athanassios Z. Panagiotopoulos

    2009-09-09

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  4. Linearized simulation of flow over wind farms and complex terrains.

    PubMed

    Segalini, Antonio

    2017-04-13

    The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results.This article is part of the themed issue 'Wind energy in complex terrains'.

  5. Soil signature simulation of complex mixtures and particle size distributions

    NASA Astrophysics Data System (ADS)

    Carson, Tyler; Bachmann, Charles M.; Salvaggio, Carl

    2015-09-01

    Soil reflectance signatures were modeled using the digital imaging and remote sensing image generation model and Blender three-dimensional (3-D) graphic design software. Using these tools, the geometry, radiometry, and chemistry of quartz and magnetite were exploited to model the presence of particle size and porosity effects in the visible and the shortwave infrared spectrum. Using the physics engines within the Blender 3-D graphic design software, physical representations of granular soil scenes were created. Each scene characterized a specific particle distribution and density. Chemical and optical properties of pure quartz and magnetite were assigned to particles in the scene based on particle size. This work presents a model to describe an observed phase-angle dependence of beach sand density. Bidirectional reflectance signatures were simulated for targets of varying size distribution and density. This model provides validation for a phenomenological trade space between density and particle size distribution in complex, heterogeneous soil mixtures. It also confirms the suggestion that directional reflectance signatures can be defined by intimate mixtures that depend on pore spacing. The study demonstrated that by combining realistic target geometry and spectral measurements of pure quartz and magnetite, effects of soil particle size and density could be modeled without functional data fitting or rigorous analysis of material dynamics. This research does not use traditional function-based models for simulation. The combination of realistic geometry, physically viable particle structure, and first-principles ray-tracing enables the ability to represent signature changes that have been observed in experimental observations.

  6. Numerical simulation of the falling snow deposition over complex terrain

    NASA Astrophysics Data System (ADS)

    Wang, Zhengshi; Huang, Ning

    2017-01-01

    Snow is one of the most dynamic natural elements on the Earth's surface, and the variations in its distribution in time and space profoundly affect the hydrological cycle, climate system, and ecological evolution as well as other natural processes. Most previous studies have paid less attention to the process determining the distribution of snow on the ground as a result of the effect of nonuniform mountain wind on the trajectories of snow particles. In this paper, we present a numerical study on the falling snow deposition process involving snow particles of mixed grain sizes over complex terrain. A three-dimensional large-eddy simulation code was used to predict the wind field by considering the fluid-solid coupling effect, and the Lagrangian particle tracking method was employed to track the movement of each tracking snow particle. The grid resolution and model parameters were determined by the best fit with the field experiment, and the coupling effect between snow particles and wind field was found to be nonnegligible when the drifting snow occurred. In general, the preferential deposition on a single ridge showed a tendency from windward slope toward leeward slope with the increasing advection, while it was hard to describe the snow distribution over complex terrains with a unified deposition model due to the interaction of surrounding topographies and different atmospheric stabilities, and the particle tracking approach was substantially suitable for this issue. Our study significantly improved the understanding of the evolution of snow distributions at high levels of resolution.

  7. Constant-complexity stochastic simulation algorithm with optimal binning

    SciTech Connect

    Sanft, Kevin R.; Othmer, Hans G.

    2015-08-21

    At the molecular level, biochemical processes are governed by random interactions between reactant molecules, and the dynamics of such systems are inherently stochastic. When the copy numbers of reactants are large, a deterministic description is adequate, but when they are small, such systems are often modeled as continuous-time Markov jump processes that can be described by the chemical master equation. Gillespie’s Stochastic Simulation Algorithm (SSA) generates exact trajectories of these systems, but the amount of computational work required for each step of the original SSA is proportional to the number of reaction channels, leading to computational complexity that scales linearly with the problem size. The original SSA is therefore inefficient for large problems, which has prompted the development of several alternative formulations with improved scaling properties. We describe an exact SSA that uses a table data structure with event time binning to achieve constant computational complexity with respect to the number of reaction channels for weakly coupled reaction networks. We present a novel adaptive binning strategy and discuss optimal algorithm parameters. We compare the computational efficiency of the algorithm to existing methods and demonstrate excellent scaling for large problems. This method is well suited for generating exact trajectories of large weakly coupled models, including those that can be described by the reaction-diffusion master equation that arises from spatially discretized reaction-diffusion processes.

  8. Constant-complexity stochastic simulation algorithm with optimal binning.

    PubMed

    Sanft, Kevin R; Othmer, Hans G

    2015-08-21

    At the molecular level, biochemical processes are governed by random interactions between reactant molecules, and the dynamics of such systems are inherently stochastic. When the copy numbers of reactants are large, a deterministic description is adequate, but when they are small, such systems are often modeled as continuous-time Markov jump processes that can be described by the chemical master equation. Gillespie's Stochastic Simulation Algorithm (SSA) generates exact trajectories of these systems, but the amount of computational work required for each step of the original SSA is proportional to the number of reaction channels, leading to computational complexity that scales linearly with the problem size. The original SSA is therefore inefficient for large problems, which has prompted the development of several alternative formulations with improved scaling properties. We describe an exact SSA that uses a table data structure with event time binning to achieve constant computational complexity with respect to the number of reaction channels for weakly coupled reaction networks. We present a novel adaptive binning strategy and discuss optimal algorithm parameters. We compare the computational efficiency of the algorithm to existing methods and demonstrate excellent scaling for large problems. This method is well suited for generating exact trajectories of large weakly coupled models, including those that can be described by the reaction-diffusion master equation that arises from spatially discretized reaction-diffusion processes.

  9. Global-Scale Hydrology: Simple Characterization of Complex Simulation

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.

    1999-01-01

    Atmospheric general circulation models (AGCMS) are unique and valuable tools for the analysis of large-scale hydrology. AGCM simulations of climate provide tremendous amounts of hydrological data with a spatial and temporal coverage unmatched by observation systems. To the extent that the AGCM behaves realistically, these data can shed light on the nature of the real world's hydrological cycle. In the first part of the seminar, I will describe the hydrological cycle in a typical AGCM, with some emphasis on the validation of simulated precipitation against observations. The second part of the seminar will focus on a key goal in large-scale hydrology studies, namely the identification of simple, overarching controls on hydrological behavior hidden amidst the tremendous amounts of data produced by the highly complex AGCM parameterizations. In particular, I will show that a simple 50-year-old climatological relation (and a recent extension we made to it) successfully predicts, to first order, both the annual mean and the interannual variability of simulated evaporation and runoff fluxes. The seminar will conclude with an example of a practical application of global hydrology studies. The accurate prediction of weather statistics several months in advance would have tremendous societal benefits, and conventional wisdom today points at the use of coupled ocean-atmosphere-land models for such seasonal-to-interannual prediction. Understanding the hydrological cycle in AGCMs is critical to establishing the potential for such prediction. Our own studies show, among other things, that soil moisture retention can lead to significant precipitation predictability in many midlatitude and tropical regions.

  10. Surgery for Bile Duct (Cholangiocarcinoma) Cancer

    MedlinePlus

    ... 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 ...

  11. Simulating Ecological Complexity Using the Example of Pesticides in Ecosystems.

    ERIC Educational Resources Information Center

    Muir, Patricia S.; McCune, Bruce

    1993-01-01

    Describes a simulation exercise developed for an introductory biology course for nonmajors. The simulation focuses on the control of western spruce budworms in forests of the western United States. A nonlinear, multivariate simulation model is used. (PR)

  12. Use of the Environmental Simulation Program (ESP) to Simulate Complex Waste Treatment Processes

    SciTech Connect

    MacLean, G. T.; Ho, Q. T.; Berger, S. R. K.

    2003-02-26

    The Environmental Simulation Program is a process simulator designed for aqueous based chemical processes. ESP, which is produced by OLI Systems, Inc., utilizes sophisticated activity coefficient models and predictive equations that result in the ability to simulate very complex electrolyte systems (OLI, 2002). The software comes with databanks of regressed parameters for a large number of aqueous, vapor, and solid species covering most of the elements. ESP has been used extensively at the U. S. Department of Energy Hanford Site to predict nuclear waste slurry vapor-liquid-solid equilibrium. It has and is being used to model leaching and washing of nuclear waste sludges, evaporation of nuclear waste solutions, crystallization of salts, precipitation of plutonium and other metals from waste solutions, and other processing of dilute and concentrated aqueous solutions, sludges, and slurries. The software is also used extensively to rationalize the characterization of nuclear wastes using limited data from analyses of waste samples. The OLI provided databanks suffer from a legacy interaction model that limits the accuracy when neutral solutes are important. Also, the nitrate-nitrite systems typically found in nuclear wastes are not properly parameterized in ESP databases because of the existence of sodium nitrate and nitrite ion pairs. Properties databanks for ESP have been developed at Flour Federal Services that eliminate the legacy model and provide more accurate simulation results than the OLI supplied databases for such concentrated solutions and slurries.

  13. Particulate mixing in a turbulent serpentine duct

    NASA Astrophysics Data System (ADS)

    Huang, X.; Durbin, P. A.

    2012-01-01

    Direct numerical simulations of particles in a serpentine duct were conducted at bulk flow Stokes numbers between 0.125 and 6. The geometrical curvature causes particles to depart direction from the mean flow. Above a Stokes number of about unity, a reflection layer forms along the outer curve of the bend. Reflectional mixing creates regions of nearly uniform particle mean velocity and kinetic energy. Particles leave the inner bend in a plume that separates from the inner wall at low Stokes number. At higher Stokes number, the plume splits in two, adding an upper part consisting of ballistic particles, that do not follow the geometrical curvature. When the Stokes number is low, the instantaneous 3-D distribution of particles visualizes wall streaks. But at higher Stokes number, particles disperse out of the reflection layer and form large scale puffs in the central portion of the duct.

  14. Ascariasis of the pancreatic duct.

    PubMed

    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.

  15. Hydrodynamic Modeling, Optimization and Performance Assessment for Ducted and Non-ducted Tidal Turbines

    NASA Astrophysics Data System (ADS)

    Shives, Michael Robert

    This thesis examines methods for designing and analyzing kinetic turbines based on blade element momentum (BEM) theory and computational fluid dynamics (CFD). The underlying goal of the work was to assess the potential augmentation of power production associated with enclosing the turbine in an expanding duct. Thus, a comparison of the potential performance of ducted and non-ducted turbines was carried out. This required defining optimal turbine performance for both concepts. BEM is the typical tool used for turbine optimization and is very well established in the context of wind turbine design. BEM was suitable for conventional turbines, but could not account for the influence of ducts, and no established methodology for designing ducted turbines could be found in the literature. Thus, methods were established to design and analyze ducted turbines based on an extended version of BEM (with CFD-derived coefficients), and based on CFD simulation. Additional complications arise in designing tidal turbines because traditional techniques for kinetic turbine design have been established for wind turbines, which are similar in their principle of operation but are driven by flows with inherently different boundary conditions than tidal currents. The major difference is that tidal flows are bounded by the ocean floor, the water surface and channel walls. Thus, analytical and CFD-based methods were established to account for the effects of these boundaries (called blockage effects) on the optimal design and performance of turbines. Additionally, tidal flows are driven by changes in the water surface height in the ocean and their velocity is limited by viscous effects. Turbines introduced into a tidal flow increase the total drag in the system and reduce the total flow in a region (e.g. a tidal channel). An analytical method to account for this was taken from the field of tidal resource assessment, and along with the methods to account for ducts and blockage effects, was

  16. Subsonic Flows through S-Ducts with Flow Control

    NASA Astrophysics Data System (ADS)

    Chen, Yi

    An inlet duct of an aircraft connects the air intake mounted on the fuselage to the engine within the aircraft body. The ideal outflow quality of the duct is steady, uniform and of high total pressure. Recently compact S-shaped inlet ducts are drawing more attention in the design of UAVs with short propulsion system. Compact ducts usually involve strong streamwise adverse pressure gradient and transverse secondary flow, leading to large-scale harmful vortical structures in the outflow. To improve the outflow quality modern flow control techniques have to be applied. Before designing successful flow control methods a solid understanding of the baseline flow field with the duct is crucial. In this work the fundamental mechanism of how the three dimensional flow topology evolves when the relevant parameters such as the duct geometry and boundary layer thickness are varied, is studied carefully. Two distinct secondary-flow patterns are identified. For the first time the sensitivity of the flow topology to the inflow boundary layer thickness in long ducts is clearly addressed. The interaction between the transverse motion induced by the transverse pressure gradient and the streamwise separation is revealed as the crucial reason for the various flow patterns existing in short ducts. A non-symmetric flow pattern is identified for the first time in both experiments and simulations in short ducts in which the intensity of the streamwise separation and the transverse invasion are in the same order of magnitude. A theory of energy accumulation and solution bifurcation is used to give a reasonable explanation for this non-symmetry. After gaining the knowledge of where and how the harmful vortical structures are generated several flow control techniques are tested to achieve a better outflow quality. The analysis of the flow control cases also provides a deeper insight into the behavior of the three-dimensional flow within the ducts. The conventional separation control method

  17. What Happens After Treatment for Bile Duct Cancer?

    MedlinePlus

    ... After Treatment What Happens After Treatment for Bile Duct Cancer? For some people with bile duct cancer, ... Bile Duct Cancer Stops Working More In Bile Duct Cancer About Bile Duct Cancer Causes, Risk Factors, ...

  18. Intraductal tubular neoplasms of the bile ducts.

    PubMed

    Katabi, Nora; Torres, Javiera; Klimstra, David S

    2012-11-01

    metastases, 1 after local intraductal recurrence. However, the occurrence of metastasis in 3 of these patients was quite late (average, 52 mo). Intraductal tubular neoplasm of the bile ducts is a biliary intraductal neoplasm with a distinctive histologic pattern resembling the recently described intraductal tubulopapillary neoplasm of the pancreas. Immunohistochemical features are similar to those of other pancreatobiliary-type carcinomas. However, this tumor may be hard to recognize as intraductal because of its complex architecture. When the tumor is entirely intraductal, the outcome appears to be favorable, but metastases can occur when invasive carcinoma is present, even after many years.

  19. PMR Graphite Engine Duct Development

    NASA Technical Reports Server (NTRS)

    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.

  20. Chemical complexity in astrophysical simulations: optimization and reduction techniques

    NASA Astrophysics Data System (ADS)

    Grassi, T.; Bovino, S.; Schleicher, D.; Gianturco, F. A.

    2013-05-01

    Chemistry plays a key role in the evolution of the interstellar medium, so it is highly important to follow its evolution in numerical simulations. However, it could easily dominate the computational cost when applied to large systems. In this paper we discuss two approaches to reduce these costs: (i) based on computational strategies, and (ii) based on the properties and on the topology of the chemical network. The first methods are more robust, while the second are meant to be giving important information on the structure of large, complex networks. We first discuss the numerical solvers for integrating the system of ordinary differential equations (ODE) associated with the chemical network, and then we propose a buffer method that decreases the computational time spent in solving the ODE system. We further discuss a flux-based method that allows one to determine and then cut on the fly the less active reactions. In addition we also present a topological approach for selecting the most probable species that will be active during the chemical evolution, thus gaining information on the chemical network that otherwise would be difficult to retrieve. This topological technique can also be used as an a priori reduction method for any size network. We implemented these methods into a 1D Lagrangian hydrodynamical code to test their effects: both classes lead to large computational speed-ups, ranging from ×2 to ×5. We have also tested some hybrid approaches finding that coupling the flux method with a buffer strategy gives the best trade-off between robustness and speed-up of calculations.

  1. CFD-based Design of LOX Pump Inlet Duct for Reduced Dynamic Loads

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Dorney, Daniel J.; Dorney, Suzanne M.

    2003-01-01

    Numerical simulations have been completed for a variety of designs for a 90 deg elbow duct. The objective is to identify a design that minimizes the dynamic load entering a LOX turbopump located at the elbow exit. Designs simulated to date indicate that simpler duct geometries result in lower losses. Benchmark simulations have verified that the compressible flow code used in this study is applicable to these incompressible flow simulations.

  2. CFD-Based Design of Turbopump Inlet Duct for Reduced Dynamic Loads

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Dorney, Suzanne M.; Dorney, Daniel J.

    2003-01-01

    Numerical simulations have been completed for a variety of designs for a 90 deg elbow duct. The objective is to identify a design that minimizes the dynamic load entering a LOX turbopump located at the elbow exit. Designs simulated to date indicate that simpler duct geometries result in lower losses. Benchmark simulations have verified that the compressible flow codes used in this study are applicable to these incompressible flow simulations.

  3. SMALL, GEOLOGICALLY COMPLEX RESERVOIRS CAN BENEFIT FROM RESERVOIR SIMULATION

    SciTech Connect

    Richard E. Bennett

    2002-06-24

    The Cascade Sand zone of the Mission-Visco Lease in the Cascade Oil field of Los Angeles County, California, has been under water flood since 1970. Increasing water injection to increase oil production rates was being considered as an opportunity to improve oil recovery. However, a secondary gas cap had formed in the up-dip portion of the reservoir with very low gas cap pressures, creating concern that oil could be displaced into the gas cap resulting in the loss of recoverable oil. Therefore, injecting gas into the gas cap to keep the gas cap pressurized and restrict the influx of oil during water injection was also being considered. Further, it was recognized that the reservoir geology in the gas cap area is very complex with numerous folding and faulting and thus there are potential pressure barriers in several locations throughout the reservoir. With these conditions in mind, there were concerns regarding well to well continuity in the gas cap, which could interfere with the intended repressurization impact. Concerns about the pattern of gas flow from well to well, the possibilities of cycling gas without the desired increased pressure, and the possible loss of oil displaced into the gas cap resulted in the decision to conduct a gas tracer survey in an attempt to better define inter-well communication. Following the gas tracer survey, a reservoir model would be developed to integrate the findings of the gas tracer survey, known geologic and reservoir data, and historic production data. The reservoir model would be used to better define the reservoir characteristics and provide information that could help optimize the waterflood-gas injection project under consideration for efficient water and gas injection management to increase oil production. However, due to inadequate gas sampling procedures in the field and insufficiently developed laboratory analytical techniques, the laboratory was unable to detect the tracer in the gas samples taken. At that point, focus

  4. A non-local computational boundary condition for duct acoustics

    NASA Technical Reports Server (NTRS)

    Zorumski, William E.; Watson, Willie R.; Hodge, Steve L.

    1994-01-01

    A non-local boundary condition is formulated for acoustic waves in ducts without flow. The ducts are two dimensional with constant area, but with variable impedance wall lining. Extension of the formulation to three dimensional and variable area ducts is straightforward in principle, but requires significantly more computation. The boundary condition simulates a nonreflecting wave field in an infinite duct. It is implemented by a constant matrix operator which is applied at the boundary of the computational domain. An efficient computational solution scheme is developed which allows calculations for high frequencies and long duct lengths. This computational solution utilizes the boundary condition to limit the computational space while preserving the radiation boundary condition. The boundary condition is tested for several sources. It is demonstrated that the boundary condition can be applied close to the sound sources, rendering the computational domain small. Computational solutions with the new non-local boundary condition are shown to be consistent with the known solutions for nonreflecting wavefields in an infinite uniform duct.

  5. 14 CFR 29.1103 - Induction systems ducts and air duct systems.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Induction systems ducts and air duct... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Induction System § 29.1103 Induction systems ducts and air duct systems. (a) Each induction system duct upstream of the...

  6. 14 CFR 25.1103 - Induction system ducts and air duct systems.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Induction system ducts and air duct systems... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Induction System § 25.1103 Induction system ducts and air duct systems. (a) Each induction system duct upstream of the...

  7. Articulated transition duct in turbomachine

    DOEpatents

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

    2014-04-29

    Turbine systems are provided. 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 and a downstream portion. The upstream portion extends from the inlet between an inlet end and an aft end. The downstream portion extends from the outlet between an outlet end and a head end. The turbine system further includes a joint coupling the aft end of the upstream portion and the head end of the downstream portion together. The joint is configured to allow movement of the upstream portion and the downstream portion relative to each other about or along at least one axis.

  8. Sound propagation in choked ducts

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Liu, C. Y.

    1976-01-01

    The linearized equations describing the propagation of sound in variable area ducts containing flow are shown to be singular when the duct mean flow is sonic. The singularity is removed when previously ignored nonlinear terms are retained. The results of a numerical study, for the case of plane waves propagating in a one-dimensional converging-diverging duct, show that the sound field is adequately described by the linearized equations only when the axial mean flow Mach number at the duct throat M sub th 0.6. For M sub th 0.6, the numerical results showed that acoustic energy flux was not conserved. An attempt was made to extend the study to include the nonlinear behavior of the sound field. Meaningful results were not obtained due, primarily, to numerical difficulties.

  9. Observationally constrained modeling of sound in curved ocean internal waves: examination of deep ducting and surface ducting at short range.

    PubMed

    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).

  10. TWO NEW DUCT LEAKAGE TESTS

    SciTech Connect

    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.

  11. Fan/Ram Duct Program

    DTIC Science & Technology

    1973-10-01

    turbofan engine shutoff scheme, the ram duct flow conditions, and the Ian duct shutoff vane area transi- tion schedule. This loss will be...airflow. The performance of the turbofan is neglected until the main engine burner is ignited. At that time it is assumed that the turbo - fan...B. Transient Operation . . .. TRANSIENT TRANSITION TEST CASES A. Turbofan to Ramjet B. Ramjet to Turbo fan CONCLUSIONS AND RECOMMENDATIONS

  12. Flow duct for nuclear reactors

    DOEpatents

    Straalsund, Jerry L.

    1978-01-01

    Improved liquid sodium flow ducts for nuclear reactors are described wherein the improvement comprises varying the wall thickness of each of the walls of a polygonal tubular duct structure so that each of the walls is of reduced cross-section along the longitudinal center line and of a greater cross-section along wall junctions with the other walls to form the polygonal tubular configuration.

  13. Duct Leakage Repeatability Testing

    SciTech Connect

    Walker, Iain; Sherman, Max

    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.

  14. Turbofan aft duct suppressor study

    NASA Technical Reports Server (NTRS)

    Syed, A. A.; Motsinger, R. E.; Fiske, G. H.; Joshi, M. C.; Kraft, R. E.

    1983-01-01

    Suppressions due to acoustic treatment in the annular exhaust duct of a model fan were theoretically predicted and compared with measured suppressions. The predictions are based on the modal analysis of sound propagation in a straight annular flow duct with segmented treatment. Modal distributions of the fan noise source (fan-stator interaction only) were measured using in-duct modal probes. The flow profiles were also measured in the vicinity of the modal probes. The acoustic impedance of the single degree of freedom treatment was measured in the presence of grazing flow. The measured values of mode distribution of the fan noise source, the flow velocity profile and the acoustic impedance of the treatment in the duct were used as input to the prediction program. The predicted suppressions, under the assumption of uniform flow in the duct, compared well with the suppressions measured in the duct for all test conditions. The interaction modes generated by the rotor-stator interaction spanned a cut-off ratio range from nearly 1 to 7.

  15. Examining Factors that Affect Performance in Complex Simulation Environments

    ERIC Educational Resources Information Center

    Mayrath, Michael Charles

    2009-01-01

    This study examined the effects of manipulating the modality (text-only, voice-only, voice+text) of a tutorial and restriction (restricted vs. unrestricted) of a simulation's interface on retention and transfer of tutorial content. The tutorial prepared novice students to use Packet Tracer, a simulation developed by Cisco that teaches network…

  16. Locating Anomalies in Complex Data Sets Using Visualization and Simulation

    NASA Technical Reports Server (NTRS)

    Panetta, Karen

    2001-01-01

    The research goals are to create a simulation framework that can accept any combination of models written at the gate or behavioral level. The framework provides the ability to fault simulate and create scenarios of experiments using concurrent simulation. In order to meet these goals we have had to fulfill the following requirements. The ability to accept models written in VHDL, Verilog or the C languages. The ability to propagate faults through any model type. The ability to create experiment scenarios efficiently without generating every possible combination of variables. The ability to accept adversity of fault models beyond the single stuck-at model. Major development has been done to develop a parser that can accept models written in various languages. This work has generated considerable attention from other universities and industry for its flexibility and usefulness. The parser uses LEXX and YACC to parse Verilog and C. We have also utilized our industrial partnership with Alternative System's Inc. to import vhdl into our simulator. For multilevel simulation, we needed to modify the simulator architecture to accept models that contained multiple outputs. This enabled us to accept behavioral components. The next major accomplishment was the addition of "functional fault models". Functional fault models change the behavior of a gate or model. For example, a bridging fault can make an OR gate behave like an AND gate. This has applications beyond fault simulation. This modeling flexibility will make the simulator more useful for doing verification and model comparison. For instance, two or more versions of an ALU can be comparatively simulated in a single execution. The results will show where and how the models differed so that the performance and correctness of the models may be evaluated. A considerable amount of time has been dedicated to validating the simulator performance on larger models provided by industry and other universities.

  17. Radiation of sound from unflanged cylindrical ducts

    NASA Technical Reports Server (NTRS)

    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.

  18. Anatomy of the nipple and breast ducts

    PubMed Central

    Urban, Cícero; Vallejo, André

    2016-01-01

    Over time, variations of mastectomy came up and started allowing the oncological safety and the possibility of an immediate breast reconstruction. Nipple sparing mastectomy (NSM) procedures have strongly increased in frequency and have become one of the best alternatives to treat breast cancer, also improving overall aesthetic outcomes and the achievement of contralateral breast symmetry. The nipple areola-complex (NAC) must be considered the identity of the breast concerning self-esteem of patients. This paper will remind the main anatomical topics around the nipple and breast ducts. PMID:26855906

  19. STEPS: Modeling and Simulating Complex Reaction-Diffusion Systems with Python.

    PubMed

    Wils, Stefan; De Schutter, Erik

    2009-01-01

    We describe how the use of the Python language improved the user interface of the program STEPS. STEPS is a simulation platform for modeling and stochastic simulation of coupled reaction-diffusion systems with complex 3-dimensional boundary conditions. Setting up such models is a complicated process that consists of many phases. Initial versions of STEPS relied on a static input format that did not cleanly separate these phases, limiting modelers in how they could control the simulation and becoming increasingly complex as new features and new simulation algorithms were added. We solved all of these problems by tightly integrating STEPS with Python, using SWIG to expose our existing simulation code.

  20. IMAGE: Simulation for Understanding Complex Situations and Increasing Future Force Agility

    DTIC Science & Technology

    2008-12-01

    IMAGE: SIMULATION FOR UNDERSTANDING COMPLEX SITUATIONS AND INCREASING FUTURE FORCE AGILITY Michel Lizotte, François Bernier, Marielle Mokhtari...ism exploiting this common vocabulary. Supporting a team sharing ideas also means handling ownership of comprehension models and allowing a user to...simulation models are closely related. Any meaning - ful simulation object actually implements a Representa- tion concept. Some comprehension model

  1. Challenges in Integrating a Complex Systems Computer Simulation in Class: An Educational Design Research

    ERIC Educational Resources Information Center

    Loke, Swee-Kin; Al-Sallami, Hesham S.; Wright, Daniel F. B.; McDonald, Jenny; Jadhav, Sheetal; Duffull, Stephen B.

    2012-01-01

    Complex systems are typically difficult for students to understand and computer simulations offer a promising way forward. However, integrating such simulations into conventional classes presents numerous challenges. Framed within an educational design research, we studied the use of an in-house built simulation of the coagulation network in four…

  2. A SYSTEMIZATION AND PENETRATION STUDY FOR STRAIGHT CYLINDRICAL DUCTS,

    DTIC Science & Technology

    DUCTS, *NEUTRON BEAMS, DUCTED BODIES, ALUMINUM, NEUTRON DETECTORS, POLONIUM , BERYLLIUM, SOURCES, NEUTRON SCATTERING, SHIELDING, WATER, NEUTRON TRANSPORT THEORY, ISOTROPISM, DUCT BENDS, NEUTRON FLUX, PENETRATION.

  3. Fan Performance From Duct Rake Instrumentation on a 1.294 Pressure Ratio, 725 ft/sec Tip Speed Turbofan Simulator Using Vaned Passage Casing Treatment

    NASA Technical Reports Server (NTRS)

    Fite, E. Brian

    2006-01-01

    A 1.294 pressure ratio, 725 ft/sec tip speed, variable pitch low noise fan was designed and tested in the NASA Glenn 9- by 15-foot Wind Tunnel. The design included a casing treatment that used recirculation to extend the fan stall line and provide an acceptable operating range. Overall aerodynamic experimental results are presented for this low tip speed, low noise fan without casing treatment as well as using several variants of the casing treatment that moved the air extraction and insertion axial locations. Measurements were made to assess effects on performance, operability, and noise. An unusual instability was discovered near the design operating line and is documented in the fan operating range. Measurements were made to compare stall margin improvements as well as measure the performance impact of the casing treatments. Experimental results in the presence of simulated inlet distortion, via screens, are presented for the baseline and recirculation casing treatment configurations. Estimates are made for the quantity of recirculation weight flow based on limited instrumentation in the recirculation system along with discussion of results and conclusions

  4. 29. DETAIL OF OUTLET DUCTS FOR MST AIRCONDITIONING SYSTEM IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. DETAIL OF OUTLET DUCTS FOR MST AIR-CONDITIONING SYSTEM IN NORTHWEST CORNER OF SLC-3W MST STATION 70.5 (LOWEST PAYLOAD SERVICE STATION). NOTE RING ATTACHMENT FOR PERSONNEL SAFETY HARNESS IN LEFT FOREGROUND. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  5. 24. AIRCONDITIONING DUCT, WINCH CONTROL BOX, AND SPEAKER AT STATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. AIR-CONDITIONING DUCT, WINCH CONTROL BOX, AND SPEAKER AT STATION 85.5 OF MST. FOLDED-UP PLATFORM ON RIGHT OF PHOTO. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  6. 22. A closeup interior view of the duct work and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. A close-up interior view of the duct work and mechanical equipment used in the delivery of the grain to the upper level grain conveyor system for Elevator and Silo Complex B (1932). - Quaker Oats Cereal Factory, Southeast corner of Broadway & Mill Streets, Akron, Summit County, OH

  7. A Computer Simulated Experiment in Complex Order Kinetics

    ERIC Educational Resources Information Center

    Merrill, J. C.; And Others

    1975-01-01

    Describes a computer simulation experiment in which physical chemistry students can determine all of the kinetic parameters of a reaction, such as order of the reaction with respect to each reagent, forward and reverse rate constants for the overall reaction, and forward and reverse activation energies. (MLH)

  8. Towards large eddy and direct simulation of complex turbulent flows

    NASA Technical Reports Server (NTRS)

    Moin, Parviz

    1991-01-01

    Recent advances in the methodology for direct numerical simulation of turbulent flows and some of the current applications are reviewed. It is argued that high-order finite difference schemes yield solutions with comparable accuracy to the spectral methods with the same number of degrees of freedom. The effects of random inflow conditions on the downstream evolution of turbulence are discussed.

  9. Stress Training and Simulator Complexity: Why Sometimes More Is Less

    ERIC Educational Resources Information Center

    Tichon, Jennifer G.; Wallis, Guy M.

    2010-01-01

    Through repeated practice under conditions similar to those in real-world settings, simulator training prepares an individual to maintain effective performance under stressful work conditions. Interfaces offering high fidelity and immersion can more closely reproduce real-world experiences and are generally believed to result in better learning…

  10. Duct leakage measurement and analysis

    SciTech Connect

    Swim, W.B.; Griggs, E.I.

    1995-08-01

    Leakage measurements were made on 6-in. (150-mm) and 10-in. (250-mm) round and 14-in. by 6-in. (350-mm by 150-mm) and 22-in. by 8-in. (560-mm by 200-mm) rectangular ducts for both positive and negative internal pressures. The data were found to fit a power law model, with the leakage rate (Q) increasing with a power, n, of static pressure difference ({Delta}p), i.e., Q {proportional_to} ({Delta}p){sup n}. A convenient leakage prediction equation, Q = C ({Delta}p*){sup n}, uses a normalized pressure difference, {Delta}p* = {Delta}p/{Delta}p{sub ref}, with {Delta}p in in. wg (Pa) and a reference pressure difference, {Delta}p{sub ref}, of 1 in. wg (250 Pa). C{sub D}, the recommended design values of C for a repetitive element of a duct system--one duct section and one joint, ranged from 0.01 cfm (0.005 L/s) for a Vanstone flanged joint to 18.5 cfm (8.7 L/s) for an unsealed 22-in. by 8-in (560-mm by 200-mm) duct with a slip-and-drive joint. Most test ducts had C{sub D} values of 6 to 8 cfm (3 to 4 L/s) and had values of n close to 0.58. Joints were found to account for most of the leakage, and thus most of the value of C{sub D}, in unsealed ducts, with seams contributing only 10% to 38% of the total.

  11. Visual Analytics for Complex Engineering Systems: Hybrid Visual Steering of Simulation Ensembles.

    PubMed

    Matković, Krešimir; Gračanin, Denis; Splechtna, Rainer; Jelović, Mario; Stehno, Benedikt; Hauser, Helwig; Purgathofer, Werner

    2014-12-01

    In this paper we propose a novel approach to hybrid visual steering of simulation ensembles. A simulation ensemble is a collection of simulation runs of the same simulation model using different sets of control parameters. Complex engineering systems have very large parameter spaces so a naïve sampling can result in prohibitively large simulation ensembles. Interactive steering of simulation ensembles provides the means to select relevant points in a multi-dimensional parameter space (design of experiment). Interactive steering efficiently reduces the number of simulation runs needed by coupling simulation and visualization and allowing a user to request new simulations on the fly. As system complexity grows, a pure interactive solution is not always sufficient. The new approach of hybrid steering combines interactive visual steering with automatic optimization. Hybrid steering allows a domain expert to interactively (in a visualization) select data points in an iterative manner, approximate the values in a continuous region of the simulation space (by regression) and automatically find the "best" points in this continuous region based on the specified constraints and objectives (by optimization). We argue that with the full spectrum of optimization options, the steering process can be improved substantially. We describe an integrated system consisting of a simulation, a visualization, and an optimization component. We also describe typical tasks and propose an interactive analysis workflow for complex engineering systems. We demonstrate our approach on a case study from automotive industry, the optimization of a hydraulic circuit in a high pressure common rail Diesel injection system.

  12. Computer simulation of the precordial QRS complex: effects of simulated changes in ventricular wall thickness and volume.

    PubMed

    Salu, Y; Marcus, M L

    1976-12-01

    The cardiac electric field generated by depolarization of the human ventricle is simulated with a computer model which utilizes 1,500 dipoles. The configuration of the ventricles utilized in the model assumed that the cross-sectional shape of the left ventricle was circular and the right ventricular free wall was a portion of an ellipse. The torso was assumed to be homogeneous and infinite. The activation sequence was based on the measurements of Durrer. The depolarizational wave was simulated by dipole layers. The output of the model is presented as a standard multilead precordial ECG. The ECG complexes generated by the model closely resemble the precordial QRS complexes of normal man. Simulated increases in wall thickness (1 to 2.2 X control) were associated with changes in the calculated precordial QRS complexes which were characteristic of left ventricular hypertrophy. Voltage (R in V5 or V6 and S in V1) and QRS duration increased linearly as a function of calculated left ventricular mass. Increases in ventricular activation time were related nonlinearly to changes in left ventricular mass and did not occur in the absence of a simulated increase in wall thickness. The effects of simulated changes in left ventricular volume (0.6 to 3.0 X control) on the QRS complex were mainly dependent on the resultant increase in left ventricular mass. This model may be useful in simulating the precordial QRS complexes that result from isolated or combined changes in ventricular volume or wall thickness or other disorders of the heart. Furthermore, it may be useful whenever a simulation of a QRS generator is needed.

  13. Smoothed Profile Method to Simulate Colloidal Particles in Complex Fluids

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ryoichi; Nakayama, Yasuya; Kim, Kang

    A new direct numerical simulation scheme, called "Smoothed Profile (SP) method," is presented. The SP method, as a direct numerical simulation of particulate flow, provides a way to couple continuum fluid dynamics with rigid-body dynamics through smoothed profile of colloidal particle. Our formulation includes extensions to colloids in multicomponent solvents such as charged colloids in electrolyte solutions. This method enables us to compute the time evolutions of colloidal particles, ions, and host fluids simultaneously by solving Newton, advection-diffusion, and Navier-Stokes equations so that the electro-hydrodynamic couplings can be fully taken into account. The electrophoretic mobilities of charged spherical particles are calculated in several situations. The comparisons with approximation theories show quantitative agreements for dilute dispersions without any empirical parameters.

  14. Three dimensional direct numerical simulation of complex jet flows

    NASA Astrophysics Data System (ADS)

    Shin, Seungwon; Kahouadji, Lyes; Juric, Damir; Chergui, Jalel; Craster, Richard; Matar, Omar

    2016-11-01

    We present three-dimensional simulations of two types of very challenging jet flow configurations. The first consists of a liquid jet surrounded by a faster coaxial air flow and the second consists of a global rotational motion. These computations require a high spatial resolution and are performed with a newly developed high performance parallel code, called BLUE, for the simulation of two-phase, multi-physics and multi-scale incompressible flows, tested on up to 131072 threads with excellent scalability performance. The method for the treatment of the fluid interfaces uses a hybrid Front Tracking/Level Set technique that defines the interface both by a discontinuous density field as well as by a local triangular Lagrangian mesh. Coriolis forces are taken into account and solved via an exact time-integration method that ensures numerical accuracy and stability. EPSRC UK Programme Grant EP/K003976/1.

  15. Integrating Multibody Simulation and CFD: toward Complex Multidisciplinary Design Optimization

    NASA Astrophysics Data System (ADS)

    Pieri, Stefano; Poloni, Carlo; Mühlmeier, Martin

    This paper describes the use of integrated multidisciplinary analysis and optimization of a race car model on a predefined circuit. The objective is the definition of the most efficient geometric configuration that can guarantee the lowest lap time. In order to carry out this study it has been necessary to interface the design optimization software modeFRONTIER with the following softwares: CATIA v5, a three dimensional CAD software, used for the definition of the parametric geometry; A.D.A.M.S./Motorsport, a multi-body dynamic simulation software; IcemCFD, a mesh generator, for the automatic generation of the CFD grid; CFX, a Navier-Stokes code, for the fluid-dynamic forces prediction. The process integration gives the possibility to compute, for each geometrical configuration, a set of aerodynamic coefficients that are then used in the multiboby simulation for the computation of the lap time. Finally an automatic optimization procedure is started and the lap-time minimized. The whole process is executed on a Linux cluster running CFD simulations in parallel.

  16. Simulating and mapping spatial complexity using multi-scale techniques

    USGS Publications Warehouse

    De Cola, L.

    1994-01-01

    A central problem in spatial analysis is the mapping of data for complex spatial fields using relatively simple data structures, such as those of a conventional GIS. This complexity can be measured using such indices as multi-scale variance, which reflects spatial autocorrelation, and multi-fractal dimension, which characterizes the values of fields. These indices are computed for three spatial processes: Gaussian noise, a simple mathematical function, and data for a random walk. Fractal analysis is then used to produce a vegetation map of the central region of California based on a satellite image. This analysis suggests that real world data lie on a continuum between the simple and the random, and that a major GIS challenge is the scientific representation and understanding of rapidly changing multi-scale fields. -Author

  17. Viscous flow computations for elliptical two-duct version of the SSME hot gas manifold

    NASA Technical Reports Server (NTRS)

    Roger, R. P.

    1986-01-01

    The objective of the effort was to numerically simulate viscous subsonic flow in a proposed elliptical two-duct version of the fuel side Hot Gas Manifold (HGM) for the Space Shuttle Main Engine (SSME). The numerical results were to complement both water flow and air flow experiments in the two-duct geometry performed at NASA-MSFC and Rocketdyne. The three-dimensional character of the HGM consists of two essentially different geometries. The first part of the construction is a concentric shell duct structure which channels the gases from a turbine exit into the second part comprised of two cylindrically shaped transfer ducts. The initial concentric shell portion can be further subdivided into a turnaround section and a bowl section. The turnaround duct (TAD) changes the direction of the mean flow by 180 degress from a smaller radius to a larger radius duct which discharges into the bowl. The cylindrical transfer ducts are attached to the bowl on one side thus providing a plane of symmetry midway between the two. Centerline flow distance from the TAD inlet to the transfer duct exit is approximately two feet. Details of the approach used to numerically simulate laminar or turbulent flow in the HGM geometry are presented. Computational results are presented and discussed.

  18. Numerical simulation of flow in centrifugal pump with complex impeller

    NASA Astrophysics Data System (ADS)

    Cui, Bao-ling; Lin, Yong-gang; Jin, Ying-zi

    2011-03-01

    Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically. The relative velocity and pressure distributions in the flowpart are obtained. It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller. The back-flow region is at inlet of long-blade suction side, near middle part of long-blade pressure side and outlet of short-blade suction side. The flow near volute throat is affected greatly by volute. The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat. The static and total pressure rise uniformly from inlet to outlet in the impeller. At impeller outlet, the pressure periodically decreases from pressure side to suction side, and then the static pressure sharply rise near the throat. The experimental results show that the back flow in the impeller has an important influence on the performance of pump.

  19. What's New in Bile Duct Cancer Research and Treatment?

    MedlinePlus

    ... Bile Duct Cancer About Bile Duct Cancer What’s New in Bile Duct Cancer Research and Treatment? Bile ... is tumor blood vessels. Bile duct tumors need new blood vessels to grow beyond a certain size. ...

  20. What Are the Key Statistics about Bile Duct Cancer?

    MedlinePlus

    ... About Bile Duct Cancer What Are the Key Statistics About Bile Duct Cancer? Bile duct cancer (cholangiocarcinoma) ... it is when it is found. For survival statistics, see “ Survival statistics for bile duct cancers .” Visit ...

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

    MedlinePlus

    ... What Should You Ask Your Doctor About Bile Duct Cancer? It is important to have frank, open ... Doctor About Bile Duct Cancer? More In Bile Duct Cancer About Bile Duct Cancer Causes, Risk Factors, ...

  2. Affections of the salivary ducts in buffaloes

    PubMed Central

    Misk, N.A.; Misk, T.N.; Semieka, M.A.; Ahmed, A.F.

    2014-01-01

    The aim of the present study was to determine different affections of the salivary ducts in buffaloes with special reference to diagnosis and treatment. The study was carried out on 39 buffaloes suffering from different affections of the salivary ducts. The recorded affections of the salivary ducts in buffaloes include; ectasia of the parotid duct (21 cases), parotid duct fistula (15 cases) and sialocele (3 cases). Each case was subjected to full study including case history, clinical examination, diagnosis, and treatment whenever possible. Exploratory puncture and radiography were used for confirmation of diagnosis. Intraoral marsupialization was performed for treatment of parotid duct ectasia. Salivary fistula was corrected by one of two successful techniques; the first by reconstruction of the parotid duct and the second by ligation of the parotid duct just caudal to the fistula opening. Sialoceles were corrected by removal of the mandibular salivary gland of the affected side. PMID:26623341

  3. Laparoscopic management of enlarged cystic duct.

    PubMed

    Nowzaradan, Y; Meador, J; Westmoreland, J

    1992-12-01

    After laparoscopic exploration of the common bile duct, or when a patient has acute cholecystitis, the cystic duct is sometimes edematous and too large to be ligated safely with an Endoclip. In such cases, ligation of the cystic duct with an Endoloop offers a solution to the problem. The standard technique for application of an Endoloop consists of dividing the cystic duct and then applying the Endoloop. This becomes more difficult if, after the cystic duct is divided, loss of traction on the common bile duct results in retraction of the divided cystic stump outside of the laparoscopic field of view. To avoid this difficulty, the authors apply an Endoloop with the grasping forceps on the cystic duct before the duct is divided so that it cannot retract from operative view and for this task developed an instrument that allows simultaneous introduction of both grasping forceps and the Endoloop through a single port.

  4. Affections of the salivary ducts in buffaloes.

    PubMed

    Misk, N A; Misk, T N; Semieka, M A; Ahmed, A F

    2014-01-01

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

  5. Performance Study of a Ducted Fan System

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  6. Technology Solutions Case Study: New Insights for Improving the Designs of Flexible Duct Junction Boxes

    SciTech Connect

    2014-01-01

    In this project, IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance.

  7. Common and Uncommon Anatomical Variants of Intrahepatic Bile Ducts in Magnetic Resonance Cholangiopancreatography and its Clinical Implication

    PubMed Central

    Sarawagi, Radha; Sundar, Shyam; Raghuvanshi, Sameer; Gupta, Sanjeev Kumar; Jayaraman, Gopal

    2016-01-01

    Summary Background Preoperative knowledge of intrahepatic bile duct (IHD) anatomy is critical for planning liver resections, liver transplantations and complex biliary reconstructive surgery. The purpose of our study was to demonstrate the imaging features of various anatomical variants of IHD using magnetic resonance cholangio-pancreatography (MRCP) and their prevalence in our population. Material/Methods This observational clinical evaluation study included 224 patients who were referred for MRCP. MRCP was performed in a 1.5-Tesla magnet (Philips) with SSH MRCP 3DHR and SSHMRCP rad protocol. A senior radiologist assessed the biliary passage for anatomical variations. Results The branching pattern of the right hepatic duct (RHD) was typical in 55.3% of subjects. The most common variant was right posterior sectoral duct (RPSD) draining into the left hepatic duct (LHD) in 27.6% of subjects. Trifurcation pattern was noted in 9.3% of subjects. In 4% of subjects, RPSD was draining into the common hepatic duct (CHD) and in 0.8% of subjects into the cystic duct. Other variants were noted in 2.6% of subjects. In 4.9% of cases there was an accessory duct. The most common type of LHD branching pattern was a common trunk of segment 2 and 3 ducts joining the segment 4 duct in 67.8% of subjects. In 23.2% of subjects, segment 2 duct united with the common trunk of segment 3 and 4 and in 3.4% of subjects segment 2, 3, and 4 ducts united together to form LHD. Other uncommon branching patterns of LHD were seen in 4.9% of subjects. Conclusions Intrahepatic bile duct anatomy is complex with many common and uncommon variations. MRCP is a reliable non-invasive imaging method for demonstration of bile duct morphology, which is useful to plan complex surgeries and to prevent iatrogenic injuries. PMID:27298653

  8. Mouse Acetylcholinesterase Unliganded and in Complex with Huperzine A: A Comparison of Molecular Dynamics Simulations

    SciTech Connect

    Tara, Sylvia; Straatsma, TP; Mccammon, Andy

    1999-06-01

    A 1 ns molecular dynamics simulation of unliganded mouse acetylcholinesterase (AChE) is compared to a previous simulation of mouse AChE complexed with Huperzine A (HupA). Several common features are observed. In both simulations, the active site gorge fluctuates in size during the 1 ns trajectory, and is completely pinched off several times. Many of the residues in the gorge that formed hydrogen bonds with HupA in the simulation of the complex, now form hydrogen bonds with other protein residues and water molecules in the gorge. The opening of a "backdoor" entrance to the active site that was found in the simulation of the complex is also observed in the unliganded simulation. Differences between the two simulations include overall lower structural RMS deviations for residues in the gorge in the unliganded simulation, a smaller diameter of the gorge in the absence of HupA, and the disappearance of a side channel that was frequently present in the liganded simulation. The differences between the two simulations can be attributed, in part, to the interaction of AChE with HupA.

  9. Simulations of photochemical smog formation in complex urban areas

    NASA Astrophysics Data System (ADS)

    Muilwijk, C.; Schrijvers, P. J. C.; Wuerz, S.; Kenjereš, S.

    2016-12-01

    In the present study we numerically investigated the dispersion of photochemical reactive pollutants in complex urban areas by applying an integrated Computational Fluid Dynamics (CFD) and Computational Reaction Dynamics (CRD) approach. To model chemical reactions involved in smog generation, the Generic Reaction Set (GRS) approach is used. The GRS model was selected since it does not require detailed modeling of a large set of reactive components. Smog formation is modeled first in the case of an intensive traffic emission, subjected to low to moderate wind conditions in an idealized two-dimensional street canyon with a building aspect ratio (height/width) of one. It is found that Reactive Organic Components (ROC) play an important role in the chemistry of smog formation. In contrast to the NOx/O3 photochemical steady state model that predicts a depletion of the (ground level) ozone, the GRS model predicts generation of ozone. Secondly, the effect of direct sunlight and shadow within the street canyon on the chemical reaction dynamics is investigated for three characteristic solar angles (morning, midday and afternoon). Large differences of up to one order of magnitude are found in the ozone production for different solar angles. As a proof of concept for real urban areas, the integrated CFD/CRD approach is applied for a real scale (1 × 1 km2) complex urban area (a district of the city of Rotterdam, The Netherlands) with high traffic emissions. The predicted pollutant concentration levels give realistic values that correspond to moderate to heavy smog. It is concluded that the integrated CFD/CRD method with the GRS model of chemical reactions is both accurate and numerically robust, and can be used for modeling of smog formation in complex urban areas.

  10. Simulation of a Complex Groundwater System and an Application

    NASA Astrophysics Data System (ADS)

    Premchitt, Jerasak; Das Gupta, Ashim

    1981-06-01

    A hydrologic model of an extensive groundwater basin was developed for the study of land subsidence due to deep well pumping in Bangkok, Thailand. It is a quasi-three-dimensional flow model with relevant modifications to suit the hydrogeologic situations in the problem area. The troublesome effect of yield from aquitard is discarded, while the field information on subsurface strata is fully utilized to establish a realistic model. The subsurface is considered to be a single hydraulically connected body stratified into model layers for convenience in the simulation. Pumping can be imposed at any depth, and discharge rates can be arbitrary. Any number of model layers can be incorporated, with coupling being provided through the leakage flux. The power and flexibility of the model is demonstrated in the simulation of groundwater flow regime in the Lower Central Plain of Thailand for a time period of 45 years. At first the model is calibrated with available field measurements in the past, and it is then extended for the prediction of future situations. The model represents the actual field situation. The mathematical process is simple, and it would require less computing effort than the equivalent full three-dimensional model or the quasi-three-dimensional model with one-dimensional elements to represent aquitards.

  11. Design and performance of duct acoustic treatment

    NASA Technical Reports Server (NTRS)

    Motsinger, R. E.; Kraft, R. E.

    1991-01-01

    The procedure for designing acoustic treatment panels used to line the walls of aircraft engine ducts and for estimating the resulting suppression of turbofan engine duct noise is discussed. This procedure is intended to be used for estimating noise suppression of existing designs or for designing new acoustic treatment panels and duct configurations to achieve desired suppression levels.

  12. Molecular dynamics simulations of a membrane protein/amphipol complex.

    PubMed

    Perlmutter, Jason D; Popot, Jean-Luc; Sachs, Jonathan N

    2014-10-01

    Amphipathic polymers known as "amphipols" provide a highly stabilizing environment for handling membrane proteins in aqueous solutions. A8-35, an amphipol with a polyacrylate backbone and hydrophobic grafts, has been extensively characterized and widely employed for structural and functional studies of membrane proteins using biochemical and biophysical approaches. Given the sensitivity of membrane proteins to their environment, it is important to examine what effects amphipols may have on the structure and dynamics of the proteins they complex. Here we present the first molecular dynamics study of an amphipol-stabilized membrane protein, using Escherichia coli OmpX as a model. We begin by describing the structure of the complexes formed by supplementing OmpX with increasing amounts of A8-35, in order to determine how the amphipol interacts with the transmembrane and extramembrane surfaces of the protein. We then compare the dynamics of the protein in either A8-35, a detergent, or a lipid bilayer. We find that protein dynamics on all accessible length scales is restrained by A8-35, which provides a basis to understanding some of the stabilizing and functional effects of amphipols that have been experimentally observed.

  13. Duct injection technology prototype development

    SciTech Connect

    Harper, S.L. . Research and Development Div.)

    1991-08-01

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

  14. A new approach for turbulent simulations in complex geometries

    NASA Astrophysics Data System (ADS)

    Israel, Daniel M.

    Historically turbulence modeling has been sharply divided into Reynolds averaged Navier-Stokes (RANS), in which all the turbulent scales of motion are modeled, and large-eddy simulation (LES), in which only a portion of the turbulent spectrum is modeled. In recent years there have been numerous attempts to couple these two approaches either by patching RANS and LES calculations together (zonal methods) or by blending the two sets of equations. In order to create a proper bridging model, that is, a single set of equations which captures both RANS and LES like behavior, it is necessary to place both RANS and LES in a more general framework. The goal of the current work is threefold: to provide such a framework, to demonstrate how the Flow Simulation Methodology (FSM) fits into this framework, and to evaluate the strengths and weaknesses of the current version of the FSM. To do this, first a set of filtered Navier-Stokes (FNS) equations are introduced in terms of an arbitrary generalized filter. Additional exact equations are given for the second order moments and the generalized subfilter dissipation rate tensor. This is followed by a discussion of the role of implicit and explicit filters in turbulence modeling. The FSM is then described with particular attention to its role as a bridging model. In order to evaluate the method a specific implementation of the FSM approach is proposed. Simulations are presented using this model for the case of a separating flow over a "hump" with and without flow control. Careful attention is paid to error estimation, and, in particular, how using flow statistics and time series affects the error analysis. Both mean flow and Reynolds stress profiles are presented, as well as the phase averaged turbulent structures and wall pressure spectra. Using the phase averaged data it is possible to examine how the FSM partitions the energy between the coherent resolved scale motions, the random resolved scale fluctuations, and the subfilter

  15. Automatic Assessment of Complex Task Performance in Games and Simulations. CRESST Report 775

    ERIC Educational Resources Information Center

    Iseli, Markus R.; Koenig, Alan D.; Lee, John J.; Wainess, Richard

    2010-01-01

    Assessment of complex task performance is crucial to evaluating personnel in critical job functions such as Navy damage control operations aboard ships. Games and simulations can be instrumental in this process, as they can present a broad range of complex scenarios without involving harm to people or property. However, "automatic"…

  16. Laboratory production of complex organics in simulated interstellar ices

    NASA Astrophysics Data System (ADS)

    Dworkin, J.; Bernstein, M.; Ashbourn, S.; Iraci, L.; Cooper, G.; Sandford, S.; Allamandola, L.

    1 see www.astrochem.org for more information. Bernstein, M., Dworkin, J., Sandford, S., &Allamandola, L. (2001). Ultraviolet Ir- radiation of Naphthalene in H2O Ice: Implications for Meteorites and Biogenesis. Meteoritics and Planetary Science36, 351-358. Bernstein, M., Dworkin, J., Sandford, S., Cooper, G. &Allamandola, L. (2002) The Formation of Racemic Amino Acids byUltraviolet Photolysis of Interstellar Ice Analogs. Nature, 416, 401U403 Dworkin, J., Deamer, D., Sandford, S., &Allamandola, L. (2001). Self-Assembling Amphiphilic Molecules: Synthesis in Simulated Interstellar/Precometary Ices. Proc. Nat. Acad. Sci. USA 98, 815-819. Krishnamurthy, R., Epstein, S., Cronin, J., Pizzarello, S. &Yuen, G. (1992) Isotopic and molecular analyses of hydrocarbons and monocarboxylic acids of the Murchison meteorite. Geochim. Cosmochim. Acta 56, 4045-4058. Sandford, S. A., Bernstein, M. P., &Dworkin, J. P. (2001). Assessment of the interstellar processes leading to deuterium enrichment in meteoritic organics. Meteoritics and Planetary Sci- ence36, 1117-1133.

  17. Simulation of the kinetics of oxygen complexes in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Joo Lee, Young; von Boehm, J.; Nieminen, R. M.

    2002-10-01

    The formation kinetics of thermal double donors (TDD's) is studied by a general kinetic model with parameters based on accurate ab initio total-energy calculations. The kinetic model includes all relevant association, dissociation, and restructuring processes. The simulated kinetics agrees qualitatively and in most cases quantitatively with the experimentally found consecutive kinetics of TDD's. It also supports our earlier assignments of the ring-type oxygen chains to TDD's [Pesola et al., Phys. Rev. Lett. 84, 5343 (2000)]. We demonstrate with the kinetic model that the most common assumption that only the O2 dimer acts as a fast diffusing species would lead to an unrealistic steady increase of the concentration of O3. The neglect of restructuring processes leads to an anomalous increase of oxygen dimers and negligible concentrations of TDD's. The capture of interstitial oxygens by diffusing oxygen chains and the escaping of interstitial oxygens from the chains fully dominate the formation kinetics.

  18. Effect of motion cues during complex curved approach and landing tasks: A piloted simulation study

    NASA Technical Reports Server (NTRS)

    Scanlon, Charles H.

    1987-01-01

    A piloted simulation study was conducted to examine the effect of motion cues using a high fidelity simulation of commercial aircraft during the performance of complex approach and landing tasks in the Microwave Landing System (MLS) signal environment. The data from these tests indicate that in a high complexity MLS approach task with moderate turbulence and wind, the pilot uses motion cues to improve path tracking performance. No significant differences in tracking accuracy were noted for the low and medium complexity tasks, regardless of the presence of motion cues. Higher control input rates were measured for all tasks when motion was used. Pilot eye scan, as measured by instrument dwell time, was faster when motion cues were used regardless of the complexity of the approach tasks. Pilot comments indicated a preference for motion. With motion cues, pilots appeared to work harder in all levels of task complexity and to improve tracking performance in the most complex approach task.

  19. Towards numerical simulation of bubbly flows in complex geometries

    NASA Astrophysics Data System (ADS)

    Mattson, Michael; Mahesh, Krishnan

    2008-11-01

    We are developing the LES capability for bubbly flows in complex geometries using unstructured grids and an Euler--Lagrangian methodology. Two Lagrangian bubble models are considered: (i) the bubbles are treated as a dispersed phase in the carrier fluid, and individual bubbles are point particles governed by an equation for bubble motion and (ii) the force coupling method by Maxey et al. [Fluid Dyn. Res., 32 (1997), 143-156]. The evolution of the bubble radius (assuming spherical bubbles) is governed by the Rayleigh--Plesset equation and integrated using a Runge--Kutta integrator with adaptive time-stepping. The talk will discuss numerical issues and contrast results between the two methodologies. Numerical results ranging from the motion of individual bubbles in channels and around bodies to drag reduction by bubbles in turbulent channel flow will be presented.

  20. Large eddy simulation for atmospheric boundary layer flow over flat and complex terrains

    NASA Astrophysics Data System (ADS)

    Han, Yi; Stoellinger, Michael; Naughton, Jonathan

    2016-09-01

    In this work, we present Large Eddy Simulation (LES) results of atmospheric boundary layer (ABL) flow over complex terrain with neutral stratification using the OpenFOAM-based simulator for on/offshore wind farm applications (SOWFA). The complete work flow to investigate the LES for the ABL over real complex terrain is described including meteorological-tower data analysis, mesh generation and case set-up. New boundary conditions for the lateral and top boundaries are developed and validated to allow inflow and outflow as required in complex terrain simulations. The turbulent inflow data for the terrain simulation is generated using a precursor simulation of a flat and neutral ABL. Conditionally averaged met-tower data is used to specify the conditions for the flat precursor simulation and is also used for comparison with the simulation results of the terrain LES. A qualitative analysis of the simulation results reveals boundary layer separation and recirculation downstream of a prominent ridge that runs across the simulation domain. Comparisons of mean wind speed, standard deviation and direction between the computed results and the conditionally averaged tower data show a reasonable agreement.

  1. Genetic Simulation Tools for Post-Genome Wide Association Studies of Complex Diseases

    PubMed Central

    Amos, Christopher I.; Bafna, Vineet; Hauser, Elizabeth R.; Hernandez, Ryan D.; Li, Chun; Liberles, David A.; McAllister, Kimberly; Moore, Jason H.; Paltoo, Dina N.; Papanicolaou, George J.; Peng, Bo; Ritchie, Marylyn D.; Rosenfeld, Gabriel; Witte, John S.

    2014-01-01

    Genetic simulation programs are used to model data under specified assumptions to facilitate the understanding and study of complex genetic systems. Standardized data sets generated using genetic simulation are essential for the development and application of novel analytical tools in genetic epidemiology studies. With continuing advances in high-throughput genomic technologies and generation and analysis of larger, more complex data sets, there is a need for updating current approaches in genetic simulation modeling. To provide a forum to address current and emerging challenges in this area, the National Cancer Institute (NCI) sponsored a workshop, entitled “Genetic Simulation Tools for Post-Genome Wide Association Studies of Complex Diseases” at the National Institutes of Health (NIH) in Bethesda, Maryland on March 11-12, 2014. The goals of the workshop were to: (i) identify opportunities, challenges and resource needs for the development and application of genetic simulation models; (ii) improve the integration of tools for modeling and analysis of simulated data; and (iii) foster collaborations to facilitate development and applications of genetic simulation. During the course of the meeting the group identified challenges and opportunities for the science of simulation, software and methods development, and collaboration. This paper summarizes key discussions at the meeting, and highlights important challenges and opportunities to advance the field of genetic simulation. PMID:25371374

  2. Teaching and Assessing Complex Skills in Simulation With Application to Rifle Marksmanship Training

    DTIC Science & Technology

    2009-12-01

    Interservice /Industry Training, Simulation, and Education Conference (I/ITSEC) 2009 2009 Paper No. 9086 Page 1 of 10 Teaching and Assessing Complex...integrate key areas of knowledge related to skill acquisition and expertise, address strategies for teaching and assessing complex skills, and examine the...complex skill development, based upon learning principles and enhanced performance feedback. Our emphasis is on teaching the “warrior” skills needed for

  3. Parallel Cartesian grid refinement for 3D complex flow simulations

    NASA Astrophysics Data System (ADS)

    Angelidis, Dionysios; Sotiropoulos, Fotis

    2013-11-01

    A second order accurate method for discretizing the Navier-Stokes equations on 3D unstructured Cartesian grids is presented. Although the grid generator is based on the oct-tree hierarchical method, fully unstructured data-structure is adopted enabling robust calculations for incompressible flows, avoiding both the need of synchronization of the solution between different levels of refinement and usage of prolongation/restriction operators. The current solver implements a hybrid staggered/non-staggered grid layout, employing the implicit fractional step method to satisfy the continuity equation. The pressure-Poisson equation is discretized by using a novel second order fully implicit scheme for unstructured Cartesian grids and solved using an efficient Krylov subspace solver. The momentum equation is also discretized with second order accuracy and the high performance Newton-Krylov method is used for integrating them in time. Neumann and Dirichlet conditions are used to validate the Poisson solver against analytical functions and grid refinement results to a significant reduction of the solution error. The effectiveness of the fractional step method results in the stability of the overall algorithm and enables the performance of accurate multi-resolution real life simulations. This material is based upon work supported by the Department of Energy under Award Number DE-EE0005482.

  4. The Detection of Radiated Modes from Ducted Fan Engines

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Nark, Douglas M.; Thomas, Russell H.

    2001-01-01

    The bypass duct of an aircraft engine is a low-pass filter allowing some spinning modes to radiate outside the duct. The knowledge of the radiated modes can help in noise reduction, as well as the diagnosis of noise generation mechanisms inside the duct. We propose a nonintrusive technique using a circular microphone array outside the engine measuring the complex noise spectrum on an arc of a circle. The array is placed at various axial distances from the inlet or the exhaust of the engine. Using a model of noise radiation from the duct, an overdetermined system of linear equations is constructed for the complex amplitudes of the radial modes for a fixed circumferential mode. This system of linear equations is generally singular, indicating that the problem is illposed. Tikhonov regularization is employed to solve this system of equations for the unknown amplitudes of the radiated modes. An application of our mode detection technique using measured acoustic data from a circular microphone array is presented. We show that this technique can reliably detect radiated modes with the possible exception of modes very close to cut-off.

  5. Performance and Flowfield Measurements on a 10-inch Ducted Rotor VTOL UAV

    NASA Technical Reports Server (NTRS)

    Martin, Preston; Tung, Chee

    2004-01-01

    A ducted fan VTOL UAV with a 10-inch diameter rotor was tested in the US Army 7-by 10-Foot Wind Tunnel. The test conditions covered a range of angle of attack from 0 to 110 degrees to the freestream. The tunnel velocity was varied from 0 (simulating a hover condition) to 128 ft/sec in propeller mode. A six-component internal balance measured the aerodynamic loads for a range of model configurations. including the isolated rotor, the isolated duct, and the full configuration of the duct and rotor. For some conditions, hotwire velocity surveys were conducted along the inner and outer surface of the duct and across the downstream wake. In addition, fluorescent oil flow visualization allowed the flow separation patterns inside and outside of the duct to be mapped for a few test conditions. Two different duct shapes were tested to determine the performance effects of leading edge radius. For each duct, a range of rotor tip gap from 1%R to 4.5%R was tested to determine the performance penalty in hover and axial flight. Measured results are presented in terms of hover performance, hover performance in a crosswind, and high angle of attack performance in propeller mode. In each case, the effects of both tip gap and duct leading edge radius are illustrated using measurements. Some of the hover performance issues were also studied using a simple analytical method, and the results agreed with the measurements.

  6. Potassium transport in the mammalian collecting duct.

    PubMed

    Muto, S

    2001-01-01

    The mammalian collecting duct plays a dominant role in regulating K(+) excretion by the nephron. The collecting duct exhibits axial and intrasegmental cell heterogeneity and is composed of at least two cell types: collecting duct cells (principal cells) and intercalated cells. Under normal circumstances, the collecting duct cell in the cortical collecting duct secretes K(+), whereas under K(+) depletion, the intercalated cell reabsorbs K(+). Assessment of the electrochemical driving forces and of membrane conductances for transcellular and paracellular electrolyte movement, the characterization of several ATPases, patch-clamp investigation, and cloning of the K(+) channel have provided important insights into the role of pumps and channels in those tubule cells that regulate K(+) secretion and reabsorption. This review summarizes K(+) transport properties in the mammalian collecting duct. Special emphasis is given to the mechanisms of how K(+) transport is regulated in the collecting duct.

  7. Building complex simulations rapidly using MATRIX(x): The Space Station redesign

    NASA Astrophysics Data System (ADS)

    Carrington, C. K.

    MSFC's quick response to the Space Station redesign effort last year required the development of a computer simulation to model the attitude and station-keeping dynamics of a complex body with rotating solar arrays in orbit around the Earth. The simulation was written using a rapid-prototyping graphical simulation and design tool called MATRIX(x) and provided the capability to quickly remodel complex configuration changes by icon manipulation using a mouse. The simulation determines time-dependent inertia properties, and models forces and torques from gravity-gradient, solar radiation, and aerodynamic disturbances. Surface models are easily built from a selection of beams, plates, tetrahedrons, and cylinders. An optimization scheme was written to determine the torque equilibrium attitudes that balance gravity-gradient and aerodynamic torques over an orbit, and propellant-usage estimates were determined. The simulation has been adapted to model the attitude dynamics for small spacecraft.

  8. Stenting of the arterial duct: a new approach to palliation for pulmonary atresia.

    PubMed Central

    Gibbs, J L; Rothman, M T; Rees, M R; Parsons, J M; Blackburn, M E; Ruiz, C E

    1992-01-01

    OBJECTIVE--To assess the possibility of maintaining ductal patency in neonates with complex pulmonary atresia by percutaneous implantation of balloon expandable stents. PATIENTS--Two duct-dependent neonates with long segment pulmonary atresia, right sided aortic arch, and left sided arterial duct. RESULTS--Stents with final diameter of 3.5 or 4 mm and initial length of 7 or 15 mm were successfully positioned in the arterial duct. Two stents were required in one child and four in the other in order to stent the entire length of the duct. After the procedures the ducts remained widely patent and arterial oxygen saturations remained above 80%. Complications of the procedures included perforation of a peripheral pulmonary artery and cardiac perforation, both caused by guide wire manipulation. Both babies died suddenly, one at five weeks, and the other at nine days after successful stenting of the duct. Both ducts were patent at necropsy; the exact cause of one death was not clearly defined, but the second seemed to be caused by pneumococcal septicaemia. CONCLUSIONS--Stenting of the arterial duct is technically feasible. It provides adequate palliation for neonates with pulmonary atresia at least in the short term and it seems to result in balanced, central perfusion of both pulmonary arteries. This preliminary report suggests that this previously untried technique may prove to be a promising and attractive alternative to neonatal aortopulmonary shunt operation. Images PMID:1372815

  9. Mechanism of dynamic near-infrared fluorescence cholangiography of extrahepatic bile ducts and applications in detecting bile duct injuries using indocyanine green in animal models.

    PubMed

    Gao, Yang; Li, Min; Song, Zi-Fang; Cui, Le; Wang, Bi-Rong; Lou, Xiao-Ding; Zhou, Tao; Zhang, Yong; Zheng, Qi-Chang

    2017-02-01

    Fluorescence intraoperative cholangiography (IOC) is a potential alternative for identifying anatomical variation and preventing iatrogenic bile duct injuries by using the near-infrared probe indocyanine green (ICG). However, the dynamic process and mechanism of fluorescence IOC have not been elucidated in previous publications. Herein, the optical properties of the complex of ICG and bile, dynamic fluorescence cholangiography and iatrogenic bile duct injuries were investigated. The emission spectrum of ICG in bile peaked at 844 nm and ICG had higher tissue penetration. Extrahepatic bile ducts could fluoresce 2 min after intravenous injection, and the fluorescence intensity reached a peak at 8 min. In addition, biliary dynamics were observed owing to ICG excretion from the bile ducts into the duodenum. Quantitative analysis indicated that ICG-guided fluorescence IOC possessed a high signal to noise ratio compared to the surrounding peripheral tissue and the portal vein. Fluorescence IOC was based on rapid uptake of circulating ICG in plasma by hepatic cells, excretion of ICG into the bile and then its interaction with protein molecules in the bile. Moreover, fluorescence IOC was sensitive to detect bile duct ligation and acute bile duct perforation using ICG in rat models. All of the results indicated that fluorescence IOC using ICG is a valid alternative for the cholangiography of extrahepatic bile ducts and has potential for measurement of biliary dynamics.

  10. Promoting Conceptual Change for Complex Systems Understanding: Outcomes of an Agent-Based Participatory Simulation

    NASA Astrophysics Data System (ADS)

    Rates, Christopher A.; Mulvey, Bridget K.; Feldon, David F.

    2016-08-01

    Components of complex systems apply across multiple subject areas, and teaching these components may help students build unifying conceptual links. Students, however, often have difficulty learning these components, and limited research exists to understand what types of interventions may best help improve understanding. We investigated 32 high school students' understandings of complex systems components and whether an agent-based simulation could improve their understandings. Pretest and posttest essays were coded for changes in six components to determine whether students showed more expert thinking about the complex system of the Chesapeake Bay watershed. Results showed significant improvement for the components Emergence ( r = .26, p = .03), Order ( r = .37, p = .002), and Tradeoffs ( r = .44, p = .001). Implications include that the experiential nature of the simulation has the potential to support conceptual change for some complex systems components, presenting a promising option for complex systems instruction.

  11. Qualitative and Quantitative Protein Complex Prediction Through Proteome-Wide Simulations.

    PubMed

    Rizzetto, Simone; Priami, Corrado; Csikász-Nagy, Attila

    2015-10-01

    Despite recent progress in proteomics most protein complexes are still unknown. Identification of these complexes will help us understand cellular regulatory mechanisms and support development of new drugs. Therefore it is really important to establish detailed information about the composition and the abundance of protein complexes but existing algorithms can only give qualitative predictions. Herein, we propose a new approach based on stochastic simulations of protein complex formation that integrates multi-source data--such as protein abundances, domain-domain interactions and functional annotations--to predict alternative forms of protein complexes together with their abundances. This method, called SiComPre (Simulation based Complex Prediction), achieves better qualitative prediction of yeast and human protein complexes than existing methods and is the first to predict protein complex abundances. Furthermore, we show that SiComPre can be used to predict complexome changes upon drug treatment with the example of bortezomib. SiComPre is the first method to produce quantitative predictions on the abundance of molecular complexes while performing the best qualitative predictions. With new data on tissue specific protein complexes becoming available SiComPre will be able to predict qualitative and quantitative differences in the complexome in various tissue types and under various conditions.

  12. Parotid salivary duct sialocele associated with glandular duct stenosis in a cat.

    PubMed

    Vallefuoco, Rosario; Jardel, Nicolas; El Mrini, Meryem; Stambouli, Fouzia; Cordonnier, Nathalie

    2011-10-01

    Feline parotid salivary duct sialocele is an uncommon disorder that has been previously reported in association with traumatic rupture of the duct in only two cats. Both cases were successfully treated by proximal duct ligation. We describe the successful surgical treatment of a parotid duct sialocele, secondary to spontaneous salivary duct stenosis, in an adult domestic shorthair cat. The cat was referred for assessment of a recurrent fluid-filled swelling on the left side of the face. Cytology of the aspirated fluid was consistent with serous saliva. The anatomical localisation of the lesion and the nature of the fluid were indicative of parotid gland/duct involvement. Retrograde sialography by parotid duct cannulation was unsuccessful because the left parotid duct opening was stenosed and obstructed by scar tissue. Surgical exploration revealed a parotid salivary duct sialocele, which was completely removed along with the parotid gland without complications.

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

    NASA Astrophysics Data System (ADS)

    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. HAARP-Induced Ionospheric Ducts

    SciTech Connect

    Milikh, Gennady; Vartanyan, Aram

    2011-01-04

    It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Those observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.

  15. Tear-ducts in wine

    NASA Astrophysics Data System (ADS)

    Bush, John W. M.

    1999-11-01

    We examine the radial spoke pattern evident in the meniscus region in glasses of strong alcoholic beverages exhibiting the `tears-in-wine' phenomenon. We demonstrate that the pattern results from ridge-like elevations of the free surface which are supported by evaporatively-driven Marangoni convection in the meniscus region. Vortices associated with the convective motions are aligned in the radial direction by the surface tension gradient responsible for the generation of tears. The radial flow is focussed into the ridges, which thus serve as the principal conduits of fluid for the tears; consequently, we refer to the ridges as `tear-ducts'. The phenomenon is examined experimentally, and a numerical model of evaporatively-driven Marangoni convection is developed which reproduces the salient features of the tear-duct phenomenon.

  16. Spectral light source distribution variations to enhance discrimination of the common bile duct from surroundings in reflectance hyperspectral images

    NASA Astrophysics Data System (ADS)

    Litorja, Maritoni; Fein, Mira; Wehner, Eleanor; Schwarz, Roderich; Zuzak, Karel; Livingston, Edward

    2013-03-01

    The classification of anatomical features using hyperspectral imaging has been a common goal in biomedical hyperspectral imaging. Identification and location of the common bile duct is critical in cholecystectomies, one of the most common surgical procedures. In this study, surgical images where the common bile duct is visible to the surgeon during open surgeries of patients with normal bile ducts were acquired. The effect of the spectral distribution of simulated light sources on the scene color are explored with the objective of providing the optimum spectral light distribution that can enhance contrast between the common bile duct and surrounding tissue through luminance and color differences.

  17. To Duct or Not to Duct: Evaluating the Space Conditioning Impacts of Heat Pump Water Heaters in the PNNL Lab Homes

    SciTech Connect

    Widder, Sarah H.; Parker, Graham B.; Peeks, B.; Sullivan, Greg; Shaffer, Scott

    2014-08-22

    Heat pump water heaters (HPWH) are a promising technology for substantially reducing water heating-related energy use in the residential sector. However, concerns have been raised regarding the impact of HPWHs on space conditioning energy when installed in conditioned space, primarily in northern climates. For example, the Northwest Energy Efficiency Alliance (NEEA’s) Northern Climate HPWH Specification, which describes the characteristics a HPWH must have to be incentivized in cold climates in the Pacific Northwest (PNW), requires exhaust ducting for their Tier II-specified products and both supply and exhaust ducting for the Tier III-specified product (NEEA 2013). However, these concerns and installation recommendations are based on modeling and comparative field data are not available to verify modeled performance. This study examines the overall performance and operation of two GE GeoSpring HPWHs in conditioned space in the matched pair of PNNL Lab Homes with no ducting, exhaust ducting, and full ducting (supply and exhaust) and explores the interactions between the HPWH and the home’s heating/cooling system. The data collected in this field evaluation suggest that previous modeling may not completely characterize the complex interactions of HPWHs, HVAC systems, and ducting. This report discusses the impact on space conditioning and water heater energy use of configuring an HPWH with exhaust only ducting or full ducting, as compared to an unducted HPWH. Additional cost analysis is necessary to assess the cost effectiveness of ducting and to make formal recommendations regarding appropriate installation of HPWHs in more varied scenarios.

  18. Modeling particle loss in ventilation ducts

    SciTech Connect

    Sippola, Mark R.; Nazaroff, William W.

    2003-04-01

    Empirical equations were developed and applied to predict losses of 0.01-100 {micro}m airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 {micro}m. The 50th percentile cut-point diameters were 15 {micro}m in supply runs and 25 {micro}m in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 {micro}m are exhausted from the building. Large particles deposit within the building, mostly in supply ducts or on indoor surfaces. When filters are present, most particles are either filtered or exhausted. The fates of particles generated indoors follow similar trends as outdoor particles drawn into the building.

  19. On the neutrons streaming in straight duct

    PubMed

    Jehouani; Boulkheir; Ichaoui

    2000-10-01

    The main aim of this study is to evaluate the thermal neutron streaming through a straight cylindrical duct by using the Monte Carlo method and evaluating the neutron reflection by the duct wall to the total flux at the exit of the duct. The duct walls are made separately of iron and aluminum. We have considered 10 groups of energy between 10(-5) and 10 eV. For a point source at the mouth of the duct, we have determined the direct and the reflected part of the total thermal neutron flux at the exit of the duct for different lengths and different radii of the duct. For a punctual source, we have found that the major contribution to the total flux of neutrons at the exit is due to the neutron reflection by walls, and the reflection contribution decreases when the neutron energy decreases. For a constant length of the duct, the reflected part decreases when the duct radius increases, while for the disk shaped source, we have found the opposite phenomenon. The transmitted neutron flux distribution at the exit of the duct is determined for a disk shaped source for different neutron energies and different distances from the exit center.

  20. Investigation of hydrodynamics and heat transfer at liquid metal downflow in a rectangular duct in a coplanar magnetic field

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Hydrodynamics and heat transfer in a liquid metal downflow in a rectangular duct with an aspect ratio of approximately 3/1 in a coplanar magnetic field (MF) are studied upon inhomogeneous (one-sided) heating of the duct. The flow in the heat-transfer duct of the cooling system of a liquid-metal blanket module of the tokamak-type thermonuclear reactor is modeled. Experiments were carried out at the mercury magnetohydrodynamic (MHD) test facility, which is a part of the MHD-complex of Moscow Power Engineering Institute-Joint Institute for High Temperatures of the Russian Academy of Sciences. A probe technique is used for measurements in the flow. The studies are performed within the following ranges of regime parameters: Reynolds numbers Re = 10000-55000, Hartmann numbers Ha = 0-800, and Grashof numbers Grq = 0-6 × 108. Averaged profiles of velocity, temperature, temperature fluctuations of the flow, and duct wall temperature are presented for two typical flow regimes. Detailed measurements are performed in the duct cross-section distant from the heating beginning in the region of homogeneous MF. MF leads to the turbulent transport suppression, owing to which the temperature on the heated wall increases. A considerable influence of the heat-gravitational counter-convection, the interaction of which with the external MF leads in some regimes to the appearance and development of instabilities in the laminarized flow, is revealed under the downflow conditions. Generation of large-scale secondary vortices with the axis parallel to the MF induction causes temperature fluctuations of the abnormal intensity that considerably exceeds the level of turbulent fluctuations. Such temperature fluctuations easily penetrate into the duct wall and can lead to the fatigue breakdown of thermonuclear reactor cooling paths. Ranges of unallowable regime parameters are determined and the boundary in coordinates Gr-Re is presented, where this effect is revealed or vanishes. The numerical

  1. Visualization of complex processes in lipid systems using computer simulations and molecular graphics.

    PubMed

    Telenius, Jelena; Vattulainen, Ilpo; Monticelli, Luca

    2009-01-01

    Computer simulation has become an increasingly popular tool in the study of lipid membranes, complementing experimental techniques by providing information on structure and dynamics at high spatial and temporal resolution. Molecular visualization is the most powerful way to represent the results of molecular simulations, and can be used to illustrate complex transformations of lipid aggregates more easily and more effectively than written text. In this chapter, we review some basic aspects of simulation methodologies commonly employed in the study of lipid membranes and we describe a few examples of complex phenomena that have been recently investigated using molecular simulations. We then explain how molecular visualization provides added value to computational work in the field of biological membranes, and we conclude by listing a few molecular graphics packages widely used in scientific publications.

  2. Pressure Losses across Multiple Fittings in Ventilation Ducts

    PubMed Central

    Ai, Z. T.; Mak, C. M.

    2013-01-01

    The accurate prediction of pressure losses across in-duct fittings is of significance in relation to the accurate sizing and good energy efficiency of air-delivery systems. Current design guides provide design methods and data for the prediction of pressure losses only for a single and isolated fitting. This study presents an investigation of pressure losses across multiple interactive in-duct fittings in a ventilation duct. A laboratory measurement of pressure losses across one fitting and multiple fittings in a ventilation duct is carried out. The pressure loss across multiple interactive fittings is lower than that across multiple similar individual fittings, while the percentage decrease is dependent on the configuration and combination of the fittings. This implies that the pressure loss across multiple closely mounted fittings calculated by summing the pressure losses across individual fittings, as provided in the ASHRAE handbook and the CIBSE guide, is overpredicted. The numerical prediction of the pressure losses across multiple fittings using the large-eddy simulation (LES) model shows good agreement with the measured data, suggesting that this model is a useful tool in ductwork design and can help to save experimental resources and improve experimental accuracy and reliability. PMID:24385871

  3. Pressure losses across multiple fittings in ventilation ducts.

    PubMed

    Ai, Z T; Mak, C M

    2013-01-01

    The accurate prediction of pressure losses across in-duct fittings is of significance in relation to the accurate sizing and good energy efficiency of air-delivery systems. Current design guides provide design methods and data for the prediction of pressure losses only for a single and isolated fitting. This study presents an investigation of pressure losses across multiple interactive in-duct fittings in a ventilation duct. A laboratory measurement of pressure losses across one fitting and multiple fittings in a ventilation duct is carried out. The pressure loss across multiple interactive fittings is lower than that across multiple similar individual fittings, while the percentage decrease is dependent on the configuration and combination of the fittings. This implies that the pressure loss across multiple closely mounted fittings calculated by summing the pressure losses across individual fittings, as provided in the ASHRAE handbook and the CIBSE guide, is overpredicted. The numerical prediction of the pressure losses across multiple fittings using the large-eddy simulation (LES) model shows good agreement with the measured data, suggesting that this model is a useful tool in ductwork design and can help to save experimental resources and improve experimental accuracy and reliability.

  4. Bile Ducts in Regenerative Liver Nodules of Alagille Patients Are Not the Result of Genetic Mosaicism.

    PubMed

    Rougemont, Anne-Laure; Alvarez, Fernando; McLin, Valérie A; Guiochon-Mantel, Anne; Bouligand, Jérome; Clément, Sophie; Tonson La Tour, Aude; Wildhaber, Barbara E; Rubbia-Brandt, Laura; Sartelet, Hervé

    2015-07-01

    Alagille syndrome (ALGS) is a complex, multisystem disease associated with mutations in the JAG1 gene. In the liver, ALGS is characterized by paucity of intrahepatic bile ducts. Gene dosage analysis performed on a large, central regenerative nodule with preserved interlobular bile ducts of 2 unrelated ALGS patients, and on surrounding cirrhotic and ductopenic liver parenchyma, showed in both cases complete JAG1 heterozygous deletion in the regenerative nodule and the ductopenic liver, with no differences in gene dosage. Thus, JAG1 mosaicism and differential haploinsufficiency do not explain the presence of bile ducts in centrally located regenerative nodules.

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

    PubMed Central

    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 (P<0.05). Multivariate logistic regression analysis showed consistent results (P<0.05). This study that shows delayed treatment may be a major risk factor for paraurethral duct dilatation secondary to paraurethral duct infection by N. gonorrhoeae 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

  6. Simulation assisted characterization of kaolinite-methanol intercalation complexes synthesized using cost-efficient homogenization method

    NASA Astrophysics Data System (ADS)

    Makó, Éva; Kovács, András; Ható, Zoltán; Kristóf, Tamás

    2015-12-01

    Recent experimental and simulation findings with kaolinite-methanol intercalation complexes raised the question of the existence of more stable structures in wet and dry state, which has not been fully cleared up yet. Experimental and molecular simulation analyses were used to investigate different types of kaolinite-methanol complexes, revealing their real structures. Cost-efficient homogenization methods were applied to synthesize the kaolinite-dimethyl sulfoxide and kaolinite-urea pre-intercalation complexes of the kaolinite-methanol ones. The tested homogenization method required an order of magnitude lower amount of reagents than the generally applied solution method. The influence of the type of pre-intercalated molecules and of the wetting or drying (at room temperature and at 150 °C) procedure on the intercalation was characterized experimentally by X-ray diffraction and thermal analysis. Consistent with the suggestion from the present simulations, 1.12-nm and 0.83-nm stable kaolinite-methanol complexes were identified. For these complexes, our molecular simulations predict either single-layered structures of mobile methanol/water molecules or non-intercalated structures of methoxy-functionalized kaolinite. We found that the methoxy-modified kaolinite can easily be intercalated by liquid methanol.

  7. Non-Newtonian bile flow in elastic cystic duct: one- and three-dimensional modeling.

    PubMed

    Li, W G; Luo, X Y; Chin, S B; Hill, N A; Johnson, A G; Bird, N C

    2008-11-01

    Bile flow is thought to play an essential role in the pathophysiological genesis of cholelithiasis (gallstone formation) and in gallbladder pain. In this paper, we extend our previous study of the human biliary system (Li et al., 2007, J. Biomech. Eng., 129:164-173) to include two important factors: the non-Newtonian properties of bile, and elastic deformation of the cystic duct. A one-dimensional (1D) model is analyzed and compared with three-dimensional (3D) fluid-structure interaction simulations. It is found that non-Newtonian bile raises resistance to the flow of bile, which can be augmented significantly by the elastic deformation (collapse) of the cystic duct. We also show that the 1D model predicts the pressure drop of the cystic duct flow well for all cases considered (Newtonian or non-Newtonian flow, rigid or elastic ducts), when compared with the full 3D simulations.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Perturbations From Ducts on the Modes of Acoustic Thermometers

    PubMed Central

    Gillis, K. A.; Lin, H.; Moldover, M. R.

    2009-01-01

    We examine the perturbations of the modes of an acoustic thermometer caused by circular ducts used either for gas flow or as acoustic waveguides coupled to remote transducers. We calculate the acoustic admittance of circular ducts using a model based on transmission line theory. The admittance is used to calculate the perturbations to the resonance frequencies and half-widths of the modes of spherical and cylindrical acoustic resonators as functions of the duct’s radius, length, and the locations of the transducers along the duct's length. To verify the model, we measured the complex acoustic admittances of a series of circular tubes as a function of length between 200 Hz and 10 kHz using a three-port acoustic coupler. The absolute magnitude of the specific acoustic admittance is approximately one. For a 1.4 mm inside-diameter, 1.4 m long tube, the root mean square difference between the measured and modeled specific admittances (both real and imaginary parts) over this frequency range was 0.018. We conclude by presenting design considerations for ducts connected to acoustic thermometers. PMID:27504227

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Fibreoptic choledochoscopy in common bile duct surgery.

    PubMed Central

    Ashby, B. S.

    1978-01-01

    Fibreoptic choledochoscopy permits visual examination of the interior of the bile ducts during operations for gallstones. But it does not replace operative cholangiography, and the common bile duct should not be opened simply to perform choledochoscopy. Operative choledochoscopy following conventional exploration and removal of stones ensures that the ducts are clear before insertion of a T tube and closure, avoiding the problem of the retained stone. Exploratory choledochoscopy with stone retrieval under direct vision is less traumatic to the ducts than conventional blind methods, and visual confirmation that the lower end of the duct is clear and the papilla patent may allow the common bile duct to be closed without a T tube, shortening the patient's convalescent period. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:697297

  12. Formation of Complex Amino Acid Precursors in Simulated Primitive Atmosphere and Their Alteration under Simulated Submarine Hydrothermal Conditions

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kensei; Kurihara, Hironari; Hirako, Tomoaki; Obayashi, Yumiko; Kaneko, Takeo; Takano, Yoshinori; Yoshimura, Yoshitaka

    Since late 1970's a great number of submarine hydrothermal systems (SHSs) has been dis-covered, and they are considered possible sites of chemical evolution and generation of life on the Earth since their discovery in late 1970s. A number of experiments simulating the con-ditions of SHSs were conducted, and abiotic production and polymerization of amino acids were reported. Free amino acids were frequently used as starting materials to examine possible organic reactions in the simulation experiments. In our early studies, not free amino acids but complex amino acids precursors with large molecular weights were formed abiotically from simulated primitive Earth atmosphere (a mixture of CO, N2 and H2 O) (Takano et al., 2004). Such complex organics (hereafter referred as to CNWs) should have been delivered to SHSs in Primitive Ocean, where they were subjected to further alteration. We examined possible alteration of the complex organics in high-temperature high-pressure environments by the su-percritical water flow reactor (SCWFR) (Islam et al.. 2003) and an autoclave. CNWs were quite hydrophilic compounds whose molecular weights were ca. 3000. After heating 573 K for 2 min in the SCWFR, aggregates of organics were formed, which were separated from aque-ous solution with a Nucleopore filter (pore size: 200 nm). We propose the following scenario of chemical evolution: (1) Complex organics including amino acid precursors were formed in primitive atmosphere and/or extraterrestrial environments, (ii) they were delivered to primor-dial SHSs, (iii) hydrothermal alteration occurred in SHSs to give organic aggregates, (iv) quite primitive molecular systems with subtle biological functions were generated in the competition among such aggregates. References: Islam, Md. N., Kaneko, T., and Kobayashi, K (2003). Reactions of Amino Acids with a Newly ConstructedSupercritical Water Flow Reactor Simulating Submarine Hydrothermal Systems. Bull. Chem. Soc. Jpn., 76, 1171. Takano, Y

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

    PubMed

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

    2013-11-01

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

  14. Ramjet bypass duct and preburner configuration

    NASA Technical Reports Server (NTRS)

    Orlando, Robert J. (Inventor)

    1994-01-01

    A combined turbofan and ramjet aircraft engine includes a forward bypass duct which allows the engine to operate more efficiently during the turbofan mode of operation. By mounting a ramjet preburner in the forward duct and isolating this duct from the turbofan bypass air, a transition from turbofan operation to ramjet operation can take place at lower flight Mach numbers without incurring pressure losses or blockage in the turbofan bypass air.

  15. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics

    NASA Astrophysics Data System (ADS)

    Anupindi, Kameswararao; Delorme, Yann; Shetty, Dinesh A.; Frankel, Steven H.

    2013-12-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high-order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. (2010) [33]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of fluid flow patterns that exist in pathological

  16. New Insights To Simulate the Luminescence Properties of Pt(II) Complexes Using Quantum Calculations.

    PubMed

    Massuyeau, Florian; Faulques, Eric; Latouche, Camille

    2017-03-24

    The present manuscript reports a thorough quantum investigation on the luminescence properties of three monoplatinum(II) complexes. First, the simulated bond lengths at the ground state are compared to the observed ones, and the simulated electronic transitions are compared to the reported ones in the literature in order to assess our methodology. In a second time we show that geometries from the first triplet excited state are similar to the ground state ones. Simulations of the phosphorescence spectra from the first triplet excited states have been performed taking into account the vibronic coupling effects together with mode-mixing (Dushinsky) and solvent effects. Our simulations are compared with the observed ones already reported in the literature and are in good agreement. The calculations demonstrate that the normal modes of low energy are of great importance on the phosphorescence signature. When temperature effects are taken into account, the simulated phosphorescence spectra are drastically improved. An analysis of the computational time shows that the vibronic coupling simulation is cost-effective and thus can be extended to treat large transition metal complexes. In addition to the intrinsic importance of the investigated targets, this work provides a robust method to simulate phosphorescence spectra and to increase the duality experiment-theory.

  17. Lipid Clustering Correlates with Membrane Curvature as Revealed by Molecular Simulations of Complex Lipid Bilayers

    PubMed Central

    Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S. P.

    2014-01-01

    Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model α-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins. PMID:25340788

  18. Lipid clustering correlates with membrane curvature as revealed by molecular simulations of complex lipid bilayers.

    PubMed

    Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S P

    2014-10-01

    Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model α-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins.

  19. NASA Operational Simulator (NOS) for V&V of complex systems

    NASA Astrophysics Data System (ADS)

    Zemerick, Scott A.; Morris, Justin R.; Bailey, Brandon T.

    2013-05-01

    This paper describes the development, capabilities and utility of the NASA Operational Simulator (NOS), a generic software-only simulation architecture developed for NASA missions. NOS was developed by the NASA's Independent Verification and Validation (IV&V) Independent Test Capability (ITC) team and is primarily utilized by software developers and (independent) testers to verify the functionality of a spacecraft's flight software from a system-wide perspective. NOS was initially developed in support of a software-only simulator for the Global Precipitation Measurement (GPM) mission to support verification and validation activities for NASA's IV&V Program. Due to the successes of the GPM simulator (GO-SIM), the NOS architecture is being reused to develop a simulation environment in support of the James Webb Space Telescope (JWST). While NOS has primarily been utilized on NASA missions, its generic architecture can be easily applied across domains to support V&V of complex systems.

  20. Anatomical assessment of bile ducts of Luschka in human fetuses.

    PubMed

    Kocabiyik, Necdet; Yalcin, Bülent; Kilbas, Zafer; Karadeniz, Sinan R; Kurt, Bülent; Comert, Ayhan; Ozan, Hasan

    2009-08-01

    Bile ducts of Luschka (also called subvesical or supravesicular ducts) can cause bile leakage during laparoscopic cholecystectomy, especially if surgery is carried out in ignorance of such variations. The aim of this study was to clarify the clinical anatomy of these ducts in human fetuses and frequency of the ducts locating near gallbladder fossa. Thirty-two fetal cadaver livers were dissected and the gallbladders were separated from the livers and ducts were investigated under a surgical microscope. All observed ducts were examined microscopically and connective tissue cords were excluded. Bile ducts of Luschka locating near cystic fossa were found in 7 of 32 fetuses (21.9%). Three of the seven ducts ran towards to liver segment 5 (S5); three ducts were found in the gallbladder fossa; and one duct ran towards to liver segment 4 (S4). Also it was found that three of the seven ducts drained into the subsegmental duct of S5, two ducts drained into the right hepatic duct, one duct drained into the right anterior branch bile duct, and one duct drained into the subsegmental duct of S4. Subvesical ducts running along the gallbladder fossa between the gallbladder and the liver parenchyma were found in a relatively high incidence in fetuses than adults. Awareness and knowledge about incidence of such ducts alerts the surgeon during laparoscopic cholecystectomy. Therefore morbidity due to bile leaks can be reduced.

  1. Generator stator core vent duct spacer posts

    DOEpatents

    Griffith, John Wesley; Tong, Wei

    2003-06-24

    Generator stator cores are constructed by stacking many layers of magnetic laminations. Ventilation ducts may be inserted between these layers by inserting spacers into the core stack. The ventilation ducts allow for the passage of cooling gas through the core during operation. The spacers or spacer posts are positioned between groups of the magnetic laminations to define the ventilation ducts. The spacer posts are secured with longitudinal axes thereof substantially parallel to the core axis. With this structure, core tightness can be assured while maximizing ventilation duct cross section for gas flow and minimizing magnetic loss in the spacers.

  2. Circumportal pancreas with retroportal main pancreatic duct.

    PubMed

    Hashimoto, Yasushi; Ross, Andrew S; Traverso, L William

    2009-08-01

    There have been 6 cases of circumportal pancreas reported, and 2 of them had the main pancreatic duct in a retroportal dorsal portion. This extremely uncommon anomaly is asymptomatic and therefore incidentally discovered. For the surgeon, it is important to discover this during pancreatic resection so the pancreatic duct can be closed and fistula is avoided. We describe the third case where a circumportal pancreas had its main pancreatic duct passing under the portal vein. The duct was identified and ligated. A fistula did not occur.

  3. Inference, simulation, modeling, and analysis of complex networks, with special emphasis on complex networks in systems biology

    NASA Astrophysics Data System (ADS)

    Christensen, Claire Petra

    Across diverse fields ranging from physics to biology, sociology, and economics, the technological advances of the past decade have engendered an unprecedented explosion of data on highly complex systems with thousands, if not millions of interacting components. These systems exist at many scales of size and complexity, and it is becoming ever-more apparent that they are, in fact, universal, arising in every field of study. Moreover, they share fundamental properties---chief among these, that the individual interactions of their constituent parts may be well-understood, but the characteristic behaviour produced by the confluence of these interactions---by these complex networks---is unpredictable; in a nutshell, the whole is more than the sum of its parts. There is, perhaps, no better illustration of this concept than the discoveries being made regarding complex networks in the biological sciences. In particular, though the sequencing of the human genome in 2003 was a remarkable feat, scientists understand that the "cellular-level blueprints" for the human being are cellular-level parts lists, but they say nothing (explicitly) about cellular-level processes. The challenge of modern molecular biology is to understand these processes in terms of the networks of parts---in terms of the interactions among proteins, enzymes, genes, and metabolites---as it is these processes that ultimately differentiate animate from inanimate, giving rise to life! It is the goal of systems biology---an umbrella field encapsulating everything from molecular biology to epidemiology in social systems---to understand processes in terms of fundamental networks of core biological parts, be they proteins or people. By virtue of the fact that there are literally countless complex systems, not to mention tools and techniques used to infer, simulate, analyze, and model these systems, it is impossible to give a truly comprehensive account of the history and study of complex systems. The author

  4. Simulations of one- and two-dimensional complex plasmas using a modular, object-oriented code

    NASA Astrophysics Data System (ADS)

    Jefferson, R. A.; Cianciosa, M.; Thomas, E.

    2010-11-01

    In a complex plasma, charged microparticles ("dust") are added to a background of ions, electrons, and neutral particles. This dust fully interacts with the surrounding plasma and self-consistently alters the plasma environment leading to the emergence of new plasma behavior. Numerical tools that complement experimental investigations can provide important insights into the properties of complex plasmas. This paper discusses a newly developed code, named DEMON (dynamic exploration of microparticle clouds optimized numerically), for simulating a complex plasma. The DEMON code models the behavior of the charged particle component of a complex plasma in a uniform plasma background. The key feature of the DEMON code is the use of a modular force model that allows a wide variety of experimental configurations to be studied without varying the core code infrastructure. Examples of the flexibility of this modular approach are presented using examples of one- and two-dimensional complex plasmas.

  5. Design of an anemometer to characterize the flow in the ducts of a hydrogenerator rotor rim

    NASA Astrophysics Data System (ADS)

    Venne, Kevin; Mydlarski, Laurent; Torriano, Federico; Charest-Fournier, Jean-Philippe; Hudon, Claude; Morissette, Jean-Francois

    2016-11-01

    Due to its complex geometry, the airflow within hydrogenerators is difficult to characterize. And although CFD can be a reliable engineering tool, its application to the field of hydrogenerators is very recent and has certain inherent limitations, which are due in part to geometrical and flow complexities, including the coexistence of moving (rotor) and stationary (stator) components. For this reason, experimental measurements are required to validate the CFD simulations of such complex flows. To this end, a 1:4 scale model of a hydrogenerator was constructed at the IREQ (Hydro-Québec Research Institute) to better understand the flow dynamics in the rotor and stator components, and to help benchmark its CFD simulations. However, new flow sensors must be developed to quantify the flow in the confined and harsh regions of hydrogenerators. Of particular interest is the flow within the rotor rim ducts, since it is directly responsible for cooling one of the most critical components, the poles. This rather complex task required the design of an anemometer that had to be accurate, durable, cost-effective, easy to install, and able to withstand the extreme conditions (temperatures of 50°C, centrifugal forces of 300g, etc.) found in hydrogenerators. This paper presents two preliminary designs of such sensors and a series of tests that were performed to calibrate and test them. Funding graciously provided by the NSERC and FRQNT.

  6. Exact calculations of phase and membrane equilibria for complex fluids by Monte Carlo simulation. Progress report

    SciTech Connect

    Panagiotopoulos, A.Z.

    1992-06-08

    Objective is to develop molecular simulation techniques for phase equilibria in complex systems. The Gibbs ensemble Monte Carlo method was extended to obtain phase diagrams for highly asymmetric and ionic fluids. The modified Widom test particle technique was developed for chemical potentials of long polymeric molecules, and preliminary calculations of phase behavior of simple model homopolymers were performed.

  7. Exact calculations of phase and membrane equilibria for complex fluids by Monte Carlo simulation

    SciTech Connect

    Panagiotopoulos, A.Z.

    1992-06-08

    Objective is to develop molecular simulation techniques for phase equilibria in complex systems. The Gibbs ensemble Monte Carlo method was extended to obtain phase diagrams for highly asymmetric and ionic fluids. The modified Widom test particle technique was developed for chemical potentials of long polymeric molecules, and preliminary calculations of phase behavior of simple model homopolymers were performed.

  8. Appreciating the Complexity of Project Management Execution: Using Simulation in the Classroom

    ERIC Educational Resources Information Center

    Hartman, Nathan S.; Watts, Charles A.; Treleven, Mark D.

    2013-01-01

    As the popularity and importance of project management increase, so does the need for well-prepared project managers. This article discusses our experiences using a project management simulation in undergraduate and MBA classes to help students better grasp the complexity of project management. This approach gives students hands-on experience with…

  9. Toward a Common Structure in Demographic Educational Modeling and Simulation: A Complex Systems Approach

    ERIC Educational Resources Information Center

    Guevara, Porfirio

    2014-01-01

    This article identifies elements and connections that seem to be relevant to explain persistent aggregate behavioral patterns in educational systems when using complex dynamical systems modeling and simulation approaches. Several studies have shown what factors are at play in educational fields, but confusion still remains about the underlying…

  10. Simulation of Lamb wave propagation for the characterization of complex structures.

    PubMed

    Agostini, Valentina; Delsanto, Pier Paolo; Genesio, Ivan; Olivero, Dimitri

    2003-04-01

    Reliable numerical simulation techniques represent a very valuable tool for analysis. For this purpose we investigated the applicability of the local interaction simulation approach (LISA) to the study of the propagation of Lamb waves in complex structures. The LISA allows very fast and flexible simulations, especially in conjunction with parallel processing, and it is particularly useful for complex (heterogeneous, anisotropic, attenuative, and/or nonlinear) media. We present simulations performed on a glass fiber reinforced plate, initially undamaged and then with a hole passing through its thickness (passing-by hole). In order to give a validation of the method, the results are compared with experimental data. Then we analyze the interaction of Lamb waves with notches, delaminations, and complex structures. In the first case the discontinuity due to a notch generates mode conversion, which may be used to predict the defect shape and size. In the case of a single delamination, the most striking "signature" is a time-shift delay, which may be observed in the temporal evolution of the signal recorded by a receiver. We also present some results obtained on a geometrically complex structure. Due to the inherent discontinuities, a wealth of propagation mechanisms are observed, which can be exploited for the purpose of quantitative nondestructive evaluation (NDE).

  11. Dirty ducting poses significant risks.

    PubMed

    Norman, Richard

    2010-06-01

    Richard Norman, managing director of ventilation system cleaning specialist Indepth Hygiene, discusses the importance of ensuring that such systems are properly cleaned in healthcare facilities, especially, he argues, as dust and debris on internal surfaces of ducting are potentially "ideal nutrients" for the growth of microorganisms such as MRSA and Clostridium difficile. In addition he warns that, if not properly and regularly cleaned, grease extract ventilation systems linked to catering facilities are a potential source of danger to hospital patients, staff, and visitors alike.

  12. Simulation of unsaturated flow in complex fractures using smoothed particle hydrodynamics

    SciTech Connect

    Tartakovsky, Alexandre M.; Meakin, Paul

    2005-08-01

    Smoothed particle hydrodynamics (SPH) models were used to simulate unsaturated flow in fractures with complex geometries. SPH is a fully Lagrangian particle-based method that allows the dynamics of interfaces separating fluids to be modeled without employing complex front tracking schemes. In SPH simulations, the fluid density field is represented by a superposition of weighting functions centered on particles which represent the fluids. The pressure is related to the fluid density through an equation of state, and the particles move in response to the pressure gradient. SPH does not require the construction of grids that would otherwise introduce numerical dispersion. The model can be used to simulate complex free-surface flow phenomenon such as invasion of wetting and nonwetting fluids into three-dimensional fractures. These processes are a severe challenge for grid-based methods. Surface tension was simulated by using a van der Waals equation of state and a combination of short-range repulsive and longer-range attractive interactions between fluid particles. The wetting behavior was simulated using similar interactions between mobile fluid particles and stationary boundary particles. The fracture geometry was generated from self-affine fractal surfaces. The fractal model was based on a large body of experimental work, which indicates that fracture surfaces have a self-affine fractal geometry characterized by a material independent (quasi universal) Hurst exponent of about 0.75.

  13. Discrete event simulation as a tool in optimization of a professional complex adaptive system.

    PubMed

    Nielsen, Anders Lassen; Hilwig, Helmer; Kissoon, Niranjan; Teelucksingh, Surujpal

    2008-01-01

    Similar urgent needs for improvement of health care systems exist in the developed and developing world. The culture and the organization of an emergency department in developing countries can best be described as a professional complex adaptive system, where each agent (employee) are ignorant of the behavior of the system as a whole; no one understands the entire system. Each agent's action is based on the state of the system at the moment (i.e. lack of medicine, unavailable laboratory investigation, lack of beds and lack of staff in certain functions). An important question is how one can improve the emergency service within the given constraints. The use of simulation signals is one new approach in studying issues amenable to improvement. Discrete event simulation was used to simulate part of the patient flow in an emergency department. A simple model was built using a prototyping approach. The simulation showed that a minor rotation among the nurses could reduce the mean number of visitors that had to be refereed to alternative flows within the hospital from 87 to 37 on a daily basis with a mean utilization of the staff between 95.8% (the nurses) and 87.4% (the doctors). We conclude that even faced with resource constraints and lack of accessible data discrete event simulation is a tool that can be used successfully to study the consequences of changes in very complex and self organizing professional complex adaptive systems.

  14. Evaluation of soil flushing of complex contaminated soil: an experimental and modeling simulation study.

    PubMed

    Yun, Sung Mi; Kang, Christina S; Kim, Jonghwa; Kim, Han S

    2015-04-28

    The removal of heavy metals (Zn and Pb) and heavy petroleum oils (HPOs) from a soil with complex contamination was examined by soil flushing. Desorption and transport behaviors of the complex contaminants were assessed by batch and continuous flow reactor experiments and through modeling simulations. Flushing a one-dimensional flow column packed with complex contaminated soil sequentially with citric acid then a surfactant resulted in the removal of 85.6% of Zn, 62% of Pb, and 31.6% of HPO. The desorption distribution coefficients, KUbatch and KLbatch, converged to constant values as Ce increased. An equilibrium model (ADR) and nonequilibrium models (TSNE and TRNE) were used to predict the desorption and transport of complex contaminants. The nonequilibrium models demonstrated better fits with the experimental values obtained from the column test than the equilibrium model. The ranges of KUbatch and KLbatch were very close to those of KUfit and KLfit determined from model simulations. The parameters (R, β, ω, α, and f) determined from model simulations were useful for characterizing the transport of contaminants within the soil matrix. The results of this study provide useful information for the operational parameters of the flushing process for soils with complex contamination.

  15. Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids.

    PubMed

    Thantsha, Mapitsi S; Cloete, Thomas E; Moolman, Francis S; Labuschagne, Philip W

    2009-01-31

    Gastric acidity is the main factor affecting viability of probiotics in the gastrointestinal tract (GIT). This study investigated the survival in simulated gastrointestinal fluids of Bifidobacterium longum Bb-46 encapsulated in interpolymer complexes formed in supercritical carbon dioxide (scCO(2)). Bacteria were exposed sequentially to simulated gastric fluid (SGF, pH 2) for 2 h and simulated intestinal fluid (SIF, pH 6.8) for 6 or 24 h. Total encapsulated bacteria were determined by suspending 1 g of product in SIF for 6 h at 37 degrees C prior to plating out. Plates were incubated anaerobically at 37 degrees C for 72 h. The interpolymer complex displayed pH-responsive release properties, with little to no release in SGF and substantial release in SIF. There was a limited reduction in viable counts at the end of exposure period due to encapsulation. Protection efficiency of the interpolymer complex was improved by addition of glyceryl monostearate (GMS). Gelatine capsules delayed release of bacteria from the interpolymer complex thus minimizing time of exposure to the detrimental conditions. Use of poly(caprolactone) (PCL), ethylene oxide-propylene oxide triblock copolymer (PEO-PPO-PEO) decreased the protection efficiency of the matrix. Interpolymer complex encapsulation showed potential for protection of probiotics and therefore for application in food and pharmaceuticals.

  16. Managing complexity in simulations of land surface and near-surface processes

    SciTech Connect

    Coon, Ethan T.; Moulton, J. David; Painter, Scott L.

    2016-01-12

    Increasing computing power and the growing role of simulation in Earth systems science have led to an increase in the number and complexity of processes in modern simulators. We present a multiphysics framework that specifies interfaces for coupled processes and automates weak and strong coupling strategies to manage this complexity. Process management is enabled by viewing the system of equations as a tree, where individual equations are associated with leaf nodes and coupling strategies with internal nodes. A dynamically generated dependency graph connects a variable to its dependencies, streamlining and automating model evaluation, easing model development, and ensuring models are modular and flexible. Additionally, the dependency graph is used to ensure that data requirements are consistent between all processes in a given simulation. Here we discuss the design and implementation of these concepts within the Arcos framework, and demonstrate their use for verification testing and hypothesis evaluation in numerical experiments.

  17. Simulation of complex glazing products; from optical data measurements to model based predictive controls

    SciTech Connect

    Kohler, Christian

    2012-04-01

    Complex glazing systems such as venetian blinds, fritted glass and woven shades require more detailed optical and thermal input data for their components than specular non light-redirecting glazing systems. Various methods for measuring these data sets are described in this paper. These data sets are used in multiple simulation tools to model the thermal and optical properties of complex glazing systems. The output from these tools can be used to generate simplified rating values or as an input to other simulation tools such as whole building annual energy programs, or lighting analysis tools. I also describe some of the challenges of creating a rating system for these products and which factors affect this rating. A potential future direction of simulation and building operations is model based predictive controls, where detailed computer models are run in real-time, receiving data for an actual building and providing control input to building elements such as shades.

  18. Managing complexity in simulations of land surface and near-surface processes

    DOE PAGES

    Coon, Ethan T.; Moulton, J. David; Painter, Scott L.

    2016-01-12

    Increasing computing power and the growing role of simulation in Earth systems science have led to an increase in the number and complexity of processes in modern simulators. We present a multiphysics framework that specifies interfaces for coupled processes and automates weak and strong coupling strategies to manage this complexity. Process management is enabled by viewing the system of equations as a tree, where individual equations are associated with leaf nodes and coupling strategies with internal nodes. A dynamically generated dependency graph connects a variable to its dependencies, streamlining and automating model evaluation, easing model development, and ensuring models aremore » modular and flexible. Additionally, the dependency graph is used to ensure that data requirements are consistent between all processes in a given simulation. Here we discuss the design and implementation of these concepts within the Arcos framework, and demonstrate their use for verification testing and hypothesis evaluation in numerical experiments.« less

  19. Structure, Spectra, and DFT Simulation of Nickel Benzazolate Complexes with Tris(2-aminoethyl)amine Ligand.

    PubMed

    Cerezo, Javier; Requena, Alberto; Zúñiga, José; Piernas, María José; Santana, M Dolores; Pérez, José; García, Luís

    2017-03-20

    Benzazolate complexes of Ni(II), [Ni(pbz)(tren)]ClO4 (pbz = 2-(2'-hydroxyphenyl)-benzimidazole (pbm), 1, 2-(2'-hydroxyphenyl)-benzoxazole (pbx), 2, 2-(2'-hydroxyphenyl)-benzothiazole (pbt), 3; tren = tris(2-aminoethyl)amine), are prepared by self-assembly reaction and structurally characterized. Theoretical DFT simulations are carried out to reproduce the features of their crystal structures and their spectroscopic and photophysic properties. The three complexes are moderately luminescent at room temperature both in acetonitrile solution and in the solid state. The simulations indicate that the absorption spectrum is dominated by two well-defined transitions, and the electronic density concentrates in three MOs around the benzazole ligands. The Stokes shifts of the emission spectra of complexes 1-3 are determined by optimizing the electronic excited state.

  20. Comparison of Measured and Numerically Simulated Turbulence Statistics in a Convective Boundary Layer Over Complex Terrain

    SciTech Connect

    Rai, Raj K.; Berg, Larry K.; Kosović, Branko; Mirocha, Jeffrey D.; Pekour, Mikhail S.; Shaw, William J.

    2016-11-25

    High resolution numerical simulation can provide insight into important physical processes that occur within the planetary boundary layer (PBL). The present work employs large eddy simulation (LES) using the Weather Forecasting and Research (WRF) model, with the LES domain nested within mesoscale simulation, to simulate real conditions in the convective PBL over an area of complex terrain. A multiple nesting approach has been used to downsize the grid spacing from 12.15 km (mesoscale) to 0.03 km (LES). A careful selection of grid spacing in the WRF Meso domain has been conducted to minimize artifacts in the WRF-LES solutions. The WRF-LES results have been evaluated with in situ and remote sensing observations collected during the US Department of Energy-supported Columbia BasinWind Energy Study (CBWES). Comparison of the first- and second-order moments, turbulence spectrum, and probability density function (PDF) of wind speed shows good agreement between the simulations and data. Furthermore, the WRF-LES variables show a great deal of variability in space and time caused by the complex topography in the LES domain. The WRF-LES results show that the flow structures, such as roll vortices and convective cells, vary depending on both the location and time of day. In addition to basic studies related to boundary-layer meteorology, results from these simulations can be used in other applications, such as studying wind energy resources, atmospheric dispersion, fire weather etc.

  1. Volterra representation enables modeling of complex synaptic nonlinear dynamics in large-scale simulations

    PubMed Central

    Hu, Eric Y.; Bouteiller, Jean-Marie C.; Song, Dong; Baudry, Michel; Berger, Theodore W.

    2015-01-01

    Chemical synapses are comprised of a wide collection of intricate signaling pathways involving complex dynamics. These mechanisms are often reduced to simple spikes or exponential representations in order to enable computer simulations at higher spatial levels of complexity. However, these representations cannot capture important nonlinear dynamics found in synaptic transmission. Here, we propose an input-output (IO) synapse model capable of generating complex nonlinear dynamics while maintaining low computational complexity. This IO synapse model is an extension of a detailed mechanistic glutamatergic synapse model capable of capturing the input-output relationships of the mechanistic model using the Volterra functional power series. We demonstrate that the IO synapse model is able to successfully track the nonlinear dynamics of the synapse up to the third order with high accuracy. We also evaluate the accuracy of the IO synapse model at different input frequencies and compared its performance with that of kinetic models in compartmental neuron models. Our results demonstrate that the IO synapse model is capable of efficiently replicating complex nonlinear dynamics that were represented in the original mechanistic model and provide a method to replicate complex and diverse synaptic transmission within neuron network simulations. PMID:26441622

  2. Radiated noise of ducted fans

    NASA Astrophysics Data System (ADS)

    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.

  3. Radiated noise of ducted fans

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    1992-01-01

    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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    Aldrich, R.; Puttagunta, S.

    2011-12-01

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

  6. What Are the Risk Factors for Bile Duct Cancer?

    MedlinePlus

    ... but it can affect people who travel to Asia. Abnormalities where the bile duct and pancreatic duct ... duct cancer is much more common in Southeast Asia and China, largely because of the high rate ...

  7. Restricted dynamics of water around a protein-carbohydrate complex: Computer simulation studies

    NASA Astrophysics Data System (ADS)

    Jana, Madhurima; Bandyopadhyay, Sanjoy

    2012-08-01

    Water-mediated protein-carbohydrate interaction is a complex phenomenon responsible for different biological processes in cellular environment. One of the unexplored but important issues in this area is the role played by water during the recognition process and also in controlling the microscopic properties of the complex. In this study, we have carried out atomistic molecular dynamics simulations of a protein-carbohydrate complex formed between the hyaluronan binding domain of the murine Cd44 protein and the octasaccharide hyaluronan in explicit water. Efforts have been made to explore the heterogeneous influence of the complex on the dynamic properties of water present in different regions around it. It is revealed from our analyses that the heterogeneous dynamics of water around the complex are coupled with differential time scales of formation and breaking of hydrogen bonds at the interface. Presence of a highly rigid thin layer of motionally restricted water molecules bridging the protein and the carbohydrate in the common region of the complex has been identified. Such water molecules are expected to play a crucial role in controlling properties of the complex. Importantly, it is demonstrated that the formation of the protein-carbohydrate complex affects the transverse and longitudinal degrees of freedom of the interfacial water molecules in a heterogeneous manner.

  8. Chapter 3: Atomistic Simulation of Lignocellulosic Biomass and Associated Cellulosomal Protein Complexes

    SciTech Connect

    Petridis, L.; Xu, J.; Crowley, M. F.; Smith, J. C.; Cheng, X.

    2010-01-01

    Computer simulations have been performed to obtain an atomic-level understanding of lignocellulose structure and the assembly of its associated cellulosomal protein complexes. First, a CHARMM molecular mechanics force field for lignin is derived and validated by performing a molecular dynamics simulation of a crystal of a lignin fragment molecule and comparing simulation-derived structural features with experimental results. Together with the existing force field for polysaccharides, this work provides the basis for full simulations of lignocellulose. Second, the underlying molecular mechanism governing the assembly of various cellulosomal modules is investigated by performing a novel free-energy calculation of the cohesin-dockerin dissociation. Our calculation indicates a free-energy barrier of {approx}17 kcal/mol and further reveals a stepwise dissociation pathway involving both the central {beta}-sheet interface and its adjacent solvent-exposed loop/turn regions clustered at both ends of the {beta}-barrel structure.

  9. Double-duct liquid metal magnetohydrodynamic engine

    DOEpatents

    Haaland, Carsten M.

    1997-01-01

    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.

  10. Double-duct liquid metal magnetohydrodynamic engine

    DOEpatents

    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.

  11. Predicting vibrational failure of flexible ducting

    NASA Technical Reports Server (NTRS)

    Henry, R. H.

    1971-01-01

    Technique applies to liquid or gas transfer through flexible ducting and proves valuable in high velocity fluid flow cases. Fluid mechanism responsible for free bellows vibrational excitation also causes flexible hose oscillation. Static pressure stress influences flexible ducting fatigue life and is considered separately.

  12. Analysis on Turbulent Flows using Large-eddy Simulation on the Seaside Complex Terrain

    NASA Astrophysics Data System (ADS)

    Kamio, T.; Iida, M.; Arakawa, C.

    2014-12-01

    The purpose of this study is the Large-eddy Simulation (LES) of the turbulent wind on the complex terrain, and the first results of the simulation are described. The authors tried to apply the LES code, which was developed as an atmospheric simulator in Japan Agency for the Marine-Earth Science and Technology (JAMSTEC), to the wind prediction for the wind energy. On the wind simulation, the highest problem would be the boundary conditions, and the case in this paper was simplified one. The case study in this paper is the west wind on a complex terrain site, which is the wind from sea for the site. The steady flow was employed for the inlet condition, because the wind on the sea is the low turbulent wind, and almost all the turbulence would be generated by the roughness of the ground surface. The wall function was employed as the surface condition on the ground surface. The computational domain size was about 8 × 3 × 2.5 km3, and the minimum cell size was about 10 × 10 × 3 m3. The computational results, the vertical profile of the averaged wind speed and the turbulence intensity, agreed with the measurement by the meteorological masts. Moreover, the authors tried the analysis of the turbulence characteristics. The power spectrum density model, and the cross spectrum analyses gave the knowledge of the turbulent characteristics on the complex terrain and the hints for the domain and grid of the numerical analysis.

  13. Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models

    SciTech Connect

    Paik, Joongcheol; Sotiropoulos, Fotis; Sale, Michael J

    2005-06-01

    A numerical method is developed for carrying out unsteady Reynolds-averaged Navier-Stokes (URANS) simulations and detached-eddy simulations (DESs) in complex 3D geometries. The method is applied to simulate incompressible swirling flow in a typical hydroturbine draft tube, which consists of a strongly curved 90 degree elbow and two piers. The governing equations are solved with a second-order-accurate, finite-volume, dual-time-stepping artificial compressibility approach for a Reynolds number of 1.1 million on a mesh with 1.8 million nodes. The geometrical complexities of the draft tube are handled using domain decomposition with overset (chimera) grids. Numerical simulations show that unsteady statistical turbulence models can capture very complex 3D flow phenomena dominated by geometry-induced, large-scale instabilities and unsteady coherent structures such as the onset of vortex breakdown and the formation of the unsteady rope vortex downstream of the turbine runner. Both URANS and DES appear to yield the general shape and magnitude of mean velocity profiles in reasonable agreement with measurements. Significant discrepancies among the DES and URANS predictions of the turbulence statistics are also observed in the straight downstream diffuser.

  14. Monte Carlo simulations of flexible polyanions complexing with whey proteins at their isoelectric point

    NASA Astrophysics Data System (ADS)

    de Vries, R.

    2004-02-01

    Electrostatic complexation of flexible polyanions with the whey proteins α-lactalbumin and β-lactoglobulin is studied using Monte Carlo simulations. The proteins are considered at their respective isoelectric points. Discrete charges on the model polyelectrolytes and proteins interact through Debye-Hückel potentials. Protein excluded volume is taken into account through a coarse-grained model of the protein shape. Consistent with experimental results, it is found that α-lactalbumin complexes much more strongly than β-lactoglobulin. For α-lactalbumin, strong complexation is due to localized binding to a single large positive "charge patch," whereas for β-lactoglobulin, weak complexation is due to diffuse binding to multiple smaller charge patches.

  15. Surgical management of Stenson’s duct injury by using double J stent urethral catheter

    PubMed Central

    Aloosi, Suha N.; Khoshnaw, Najmaddin; Ali, Shakhawan M.; Muhammad, Belal A.

    2015-01-01

    Background Parotid duct or gland injury can be caused by assault with a knife, bottle, electrical-saw, road traffic accident, or rarely gunshot and fractures of the facial skeleton. The injury can be in the form of laceration, ductal exposure, total cutting, or crushing of the duct. These conditions are difficult to diagnose because of complex anatomy and variable forms of the injury. A successful management of parotid duct injuries depends on early diagnosis and appropriate intervention; improper surgery may lead to complications such as sialocele or salivary fistula Case report A 27-years-old man was presented to the maxillofacial unit, complaining of bleeding over the right side of his face after accidental exposure to a chain-saw three hours before admission. On examination, a 6 cm deep lacerated wound was found over the right buccal area, suspecting facial nerve-buccal branch and parotid duct injury. Under general anesthesia the parotid duct injury diagnosed, microsurgical anastomosis of the cut-ends of the parotid duct performed using the double J catheter. Sutures and JJ stent removed seven and twenty postoperative days respectively. After a proper supportive treatment a complete healing of the duct was obtained with normal amount of saliva. Conclusions Herein, we described an easy yet efficient technique in management of parotid duct injury using a JJ stent which is often used for urethra. We think that use of JJ stent is a valuable technique to be used in the diagnosis and surgical repair of the parotid duct during traumatic facial and/or parotid injuries. PMID:26555062

  16. Non-linear duct acoustics and its application to fan noise

    NASA Technical Reports Server (NTRS)

    Vaidya, P. G.

    1977-01-01

    Quite often the scalar Helmholtz equation is assumed to be the fundamental equation of duct acoustics and various relations are derived from it. An investigation is, therefore, conducted regarding the underlying assumptions leading to the Helmholtz equation. It is found that serious errors, even well below 186 dB, are possible if the assumption of linearity were to be made. In duct acoustics these errors are highest near the cutoff points and in the case of ducts with transonic flow. It is pointed out that serious errors could arise if a nonlinear problem is analyzed by linear methods. At times, an entire phenomenon remains unpredictable by linear methods. Attention is given to the characteristics of nonlinear systems, the phenomenon of multiple pure tones in the case of noise from the aircraft engine fans, the limitations of the conventional acoustics equation, duct shape and nonlinearity, and the numerical simulation of a fan with 8 blades.

  17. Fluidic-Driven Ducted Heat Ejector

    NASA Astrophysics Data System (ADS)

    Gerty, Donavon; Mahalingam, Raghav; Glezer, Ari

    2003-11-01

    A high-aspect ratio miniature air duct is developed for forced convection heat rejection from electronic hardware within sealed enclosures. Relatively high heat transfer coefficient is achieved at low volume flow rates by a thin oscillating reed that is mounted across the span of the duct, parallel to its (wide) walls. The flow is induced by the time-periodic shedding of tip vortices at the edge of the reed which continue to propagate downstream along the duct. The interaction of these vortices with vorticity concentrations along the duct surfaces and the structure of the ensuing flow are investigated using high-resolution phase-locked and time-averaged particle image velocimetry. The dependence of the global flow and heat transfer from the duct walls on the frequency and amplitude of the reed motion are also characterized.

  18. Uniformly spaced field-aligned ionization ducts

    NASA Technical Reports Server (NTRS)

    Gross, S. H.; Muldrew, D. B.

    1984-01-01

    A number of interesting cases of combination mode ducted echoes for mid- and low-latitude regions are presented that show nearly uniformly spaced multiple combination mode traces on the ionograms in the frequency range above 1 MHz. These traces suggest that a parallel system of field-aligned ducts is present. Ray tracing studies are made to determine the structure that would explain the observations using the electron density profile derivable from the vertical trace and assuming field-aligned ducts. Spacing perpendicular to the ducts is found to be as much as 70 km. Some of these parallel duct structures are found to extend to the conjugate hemisphere, possibly to the F peak.

  19. Flexible simulation framework to couple processes in complex 3D models for subsurface utilization assessment

    NASA Astrophysics Data System (ADS)

    Kempka, Thomas; Nakaten, Benjamin; De Lucia, Marco; Nakaten, Natalie; Otto, Christopher; Pohl, Maik; Tillner, Elena; Kühn, Michael

    2016-04-01

    Utilization of the geological subsurface for production and storage of hydrocarbons, chemical energy and heat as well as for waste disposal requires the quantification and mitigation of environmental impacts as well as the improvement of georesources utilization in terms of efficiency and sustainability. The development of tools for coupled process simulations is essential to tackle these challenges, since reliable assessments are only feasible by integrative numerical computations. Coupled processes at reservoir to regional scale determine the behaviour of reservoirs, faults and caprocks, generally demanding for complex 3D geological models to be considered besides available monitoring and experimenting data in coupled numerical simulations. We have been developing a flexible numerical simulation framework that provides efficient workflows for integrating the required data and software packages to carry out coupled process simulations considering, e.g., multiphase fluid flow, geomechanics, geochemistry and heat. Simulation results are stored in structured data formats to allow for an integrated 3D visualization and result interpretation as well as data archiving and its provision to collaborators. The main benefits in using the flexible simulation framework are the integration of data geological and grid data from any third party software package as well as data export to generic 3D visualization tools and archiving formats. The coupling of the required process simulators in time and space is feasible, while different spatial dimensions in the coupled simulations can be integrated, e.g., 0D batch with 3D dynamic simulations. User interaction is established via high-level programming languages, while computational efficiency is achieved by using low-level programming languages. We present three case studies on the assessment of geological subsurface utilization based on different process coupling approaches and numerical simulations.

  20. Molecular dynamics simulations of bovine cathepsin B and its complex with CA074.

    PubMed

    Yamamoto, A; Tomoo, K; Miyagawa, H; Takaoka, Y; Sumiya, S; Kitamura, K; Ishida, T

    2000-04-01

    To promote our better understanding of the dynamic stability of the bovine cathepsin B structure, which is characterized by an extra disulfide bond at Cys148-Cys252 from the other species, and of the binding stability of CA074 (a cathepsin B-specific inhibitor), molecular dynamics (MD) simulations were performed for the enzyme and its CA074 complex, assuming a system in aqueous solution at 300 K. The MD simulation covering 400 ps indicated that the existence of a Cys148-Cys252 disulfide bond increases the conformational flexibility of the occluding loop, although the conformational stability of the overall structure is little affected. The structural characteristics of the complex elucidated by X-ray analysis were suggested to be also intrinsic and stable in the dynamic state; the hydrogen bonding/electrostatic interactions between the main and side chains of CA074 and the Sn and Sn' subsites of the enzyme were maintained throughout the MD simulation. Furthermore, the simulation made clear that the binding of CA074 significantly restricted the conformational flexibility of the substrate binding region, especially the occluding loop, of cathepsin B. Statistical analyses during the simulation suggest that the selectivity of CA074 for cathepsin B stems from the tight P1'-S1' and P2'-S2' interactions, assisted in particular by double hydrogen bonds between the carboxyl two oxygens of the CA074 C-terminus and the imidazole NH groups of His110 and His111 residues.

  1. Electromagnetic propagation in PEC and absorbing curved S-ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, Kenneth J.

    1988-01-01

    A finite-element Galerkin formulation has been developed to study transverse magnetic (TM) wave propagation in 2-D S-curved ducts with both perfectly conducting and absorbing walls. The reflection and transmission at the entrances and the exits of the curved ducts are determined by coupling the finite-element solutions in the curved ducts to the eigenfunctions of an infinite, uniform, perfectly conducting duct. Example solutions are presented for a double mitred and S-ducts of various lengths. The length of the S-duct is found to significantly effect the reflective characteristics of the duct. Also, the effect of curvature on an absorbing duct is illustrated.

  2. The application of the transfer matrix and matrix condensation methods with finite elements to duct acoustics

    NASA Astrophysics Data System (ADS)

    Craggs, A.

    1989-08-01

    When making an acoustic finite element model of a duct system, the resulting matrices can be very large due to the length of ductwork, the complex changes in geometry and the numerous junctions, and a full model may require several thousand nodes. In this paper two techniques are given for reducing the size of the matrices; the transfer matrix method and the condensed stiffness matrix approach—both of which lead to equations expressed in terms of the input and output nodes only. The methods are demonstrated with examples on a straight section of duct and a branched duct network. The substantial reductions in computer memory shown imply that duct acoustic problems can be studied using a desktop work station.

  3. - - and Cross-Joints of Lined Ducts

    NASA Astrophysics Data System (ADS)

    Mechel, F. P.

    1998-10-01

    Much effort has been spent to increase the attenuation of lined ducts at low frequencies with only a minor increase of the blocking of the duct by thick silencers, in order to keep the stationary flow of the resistance of the silencer at low values. There exists a similar problem at high frequencies, where the attenuation goes down at about the square of the inverse frequency as soon as the frequency limit of ray formation is exceeded at which the free duct is about half a wavelength wide. The principal remedy of the problem, to choose narrow ducts, would increase the aerodynamic resistance. The ray-acoustical background of the low attenuation at high frequency suggests using the existing corners of the ductwork into which the silencer is inserted for the generation of high-frequency attenuation. A naı̈ve idea is to assume that the exciting sound ray of the inlet duct should be absorbed by an absorber on the corner wall opposite this duct, thereby avoiding the excitation of the outlet branch of the duct. Such a corner absorber could be applied in wide ducts also. This paper presents theories of joints of acoustically lined ducts with separate sound absorbers at the corner walls. The numerical results will show that high transmission losses can indeed be achieved at high frequencies, but the mechanism of the corner attenuation is not so much the absorption by the corner absorber, but more the (cut-off) attenuation of higher modes in the lined outlet branch of the duct.

  4. A Project Management Approach to Using Simulation for Cost Estimation on Large, Complex Software Development Projects

    NASA Technical Reports Server (NTRS)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    It is very difficult for project managers to develop accurate cost and schedule estimates for large, complex software development projects. None of the approaches or tools available today can estimate the true cost of software with any high degree of accuracy early in a project. This paper provides an approach that utilizes a software development process simulation model that considers and conveys the level of uncertainty that exists when developing an initial estimate. A NASA project will be analyzed using simulation and data from the Software Engineering Laboratory to show the benefits of such an approach.

  5. Use of simulation to understand the effects of task complexity and time away on clinical confidence.

    PubMed

    Cohen, Elaine; Ononye, Chiagozie; Salud, Jonathan; Kwan, Calvin; Salud, Lawrence; Pugh, Carla

    2013-01-01

    In prior studies, mannequin-based simulation training has been used to help decrease student anxiety toward intimate clinical examinations. Using time away as an independent variable, the aim of this study was to assess decay of clinical confidence for four procedural tasks that vary in procedural complexity. Clinical confidence with intimate examinations, after a standardized mannequin-based simulation curriculum, decays over time. This decay is noted after two months of time away. Longer periods of time away did not show increased differences.

  6. Solving complex maintenance planning optimization problems using stochastic simulation and multi-criteria fuzzy decision making

    SciTech Connect

    Tahvili, Sahar; Österberg, Jonas; Silvestrov, Sergei; Biteus, Jonas

    2014-12-10

    One of the most important factors in the operations of many cooperations today is to maximize profit and one important tool to that effect is the optimization of maintenance activities. Maintenance activities is at the largest level divided into two major areas, corrective maintenance (CM) and preventive maintenance (PM). When optimizing maintenance activities, by a maintenance plan or policy, we seek to find the best activities to perform at each point in time, be it PM or CM. We explore the use of stochastic simulation, genetic algorithms and other tools for solving complex maintenance planning optimization problems in terms of a suggested framework model based on discrete event simulation.

  7. Docking and molecular dynamics simulations of the ternary complex nisin2:lipid II

    PubMed Central

    Mulholland, Sam; Turpin, Eleanor R.; Bonev, Boyan B.; Hirst, Jonathan D.

    2016-01-01

    Lanthionine antibiotics are an important class of naturally-occurring antimicrobial peptides. The best-known, nisin, is a commercial food preservative. However, structural and mechanistic details on nisin-lipid II membrane complexes are currently lacking. Recently, we have developed empirical force-field parameters to model lantibiotics. Docking and molecular dynamics (MD) simulations have been used to study the nisin2:lipid II complex in bacterial membranes, which has been put forward as the building block of nisin/lipid II binary membrane pores. An Ile1Trp mutation of the N-terminus of nisin has been modelled and docked onto lipid II models; the computed binding affinity increased compared to wild-type. Wild-type nisin was also docked onto three different lipid II structures and a stable 2:1 nisin:lipid II complex formed. This complex was inserted into a membrane. Six independent MD simulations revealed key interactions in the complex, specifically the N-terminal engagement of nisin with lipid II at the pyrophosphate and C-terminus of the pentapeptide chain. Nisin2 inserts into the membrane and we propose this as the first step in pore formation, mediated by the nisin N-terminus–lipid II pentapeptide hydrogen bond. The lipid II undecaprenyl chain adopted different conformations in the presence of nisin, which may also have implications for pore formation. PMID:26888784

  8. The Development of the Ducted Fan Noise Propagation and Radiation Code CDUCT-LaRC

    NASA Technical Reports Server (NTRS)

    Nark, Douglas M.; Farassat, F.; Pope, D. Stuart; Vatsa, Veer

    2003-01-01

    The development of the ducted fan noise propagation and radiation code CDUCT-LaRC at NASA Langley Research Center is described. This code calculates the propagation and radiation of given acoustic modes ahead of the fan face or aft of the exhaust guide vanes in the inlet or exhaust ducts, respectively. This paper gives a description of the modules comprising CDUCT-LaRC. The grid generation module provides automatic creation of numerical grids for complex (non-axisymmetric) geometries that include single or multiple pylons. Files for performing automatic inviscid mean flow calculations are also generated within this module. The duct propagation is based on the parabolic approximation theory of R. P. Dougherty. This theory allows the handling of complex internal geometries and the ability to study the effect of non-uniform (i.e. circumferentially and axially segmented) liners. Finally, the duct radiation module is based on the Ffowcs Williams-Hawkings (FW-H) equation with a penetrable data surface. Refraction of sound through the shear layer between the external flow and bypass duct flow is included. Results for benchmark annular ducts, as well as other geometries with pylons, are presented and compared with available analytical data.

  9. Simulation modelling as a tool to diagnose the complex networks of security systems

    NASA Astrophysics Data System (ADS)

    Iskhakov, S. Y.; Shelupanov, A. A.; Meshcheryakov, R. V.

    2017-01-01

    In the article, the questions of modelling of complex security system networks are considered. The simulation model of operation of similar complexes and approbation of the offered approach to identification of the incidents are presented. The approach is based on detection of uncharacteristic alterations of the network operation mode. The results of the experiment allow one to draw a conclusion on possibility of the offered model application to analyse the current status of heterogeneous security systems. Also, it is confirmed that the application of short-term forecasting methods for the analysis of monitoring system data allows one to automate the process of formation the criteria to reveal the incidents.

  10. Deposition Velocities of Non-Newtonian Slurries in Pipelines: Complex Simulant Testing

    SciTech Connect

    Poloski, Adam P.; Bonebrake, Michael L.; Casella, Andrew M.; Johnson, Michael D.; Toth, James J.; Adkins, Harold E.; Chun, Jaehun; Denslow, Kayte M.; Luna, Maria; Tingey, Joel M.

    2009-07-01

    ) was performed at each yield stress condition. Unlike the previous simulant, the sizes and densities of the particles that can deposit in the piping are a result of the simulant precipitation process; there is expected to be a complex mixture of particles of various sizes and densities that make it difficult to predict a stability map. The objective of the testing is to observe whether behavior consistent with the stability-map concept occurs in complex simulants with mixtures of different sizes and densities.

  11. Simulations reveal that the HIV-1 gp120-CD4 complex dissociates via complex pathways and is a potential target of the polyamidoamine (PAMAM) dendrimer

    NASA Astrophysics Data System (ADS)

    Nandy, Bidisha; Bindu, D. Hima; Dixit, Narendra M.; Maiti, Prabal K.

    2013-07-01

    The polyamidoamine (PAMAM) dendrimer prevents HIV-1 entry into target cells in vitro. Its mechanism of action, however, remains unclear and precludes the design of potent dendrimers targeting HIV-1 entry. We employed steered molecular dynamics simulations to examine whether the HIV-1 gp120-CD4 complex is a target of PAMAM. Our simulations mimicked single molecule force spectroscopy studies of the unbinding of the gp120-CD4 complex under the influence of a controlled external force. We found that the complex dissociates via complex pathways and defies the standard classification of adhesion molecules as catch and slip bonds. When the force loading rate was large, the complex behaved as a slip bond, weakening gradually. When the loading rate was small, the complex initially strengthened, akin to a catch bond, but eventually dissociated over shorter separations than with large loading rates. PAMAM docked to gp120 and destabilized the gp120-CD4 complex. The rupture force of the complex was lowered by PAMAM. PAMAM disrupted salt bridges and hydrogen bonds across the gp120-CD4 interface and altered the hydration pattern of the hydrophobic cavity in the interface. In addition, intriguingly, PAMAM suppressed the distinction in the dissociation pathways of the complex between the small and large loading rate regimes. Taken together, our simulations reveal that PAMAM targets the gp120-CD4 complex at two levels: it weakens the complex and also alters its dissociation pathway, potentially inhibiting HIV-1 entry.

  12. Monitoring of Grouting Compactness in a Post-Tensioning Tendon Duct Using Piezoceramic Transducers.

    PubMed

    Jiang, Tianyong; Kong, Qingzhao; Wang, Wenxi; Huo, Linsheng; Song, Gangbing

    2016-08-22

    A post-tensioning tendon duct filled with grout can effectively prevent corrosion of the reinforcement, maintain bonding behavior between the reinforcement and concrete, and enhance the load bearing capacity of concrete structures. In practice, grouting of the post-tensioning tendon ducts always causes quality problems, which may reduce structural integrity and service life, and even cause accidents. However, monitoring of the grouting compactness is still a challenge due to the invisibility of the grout in the duct during the grouting process. This paper presents a stress wave-based active sensing approach using piezoceramic transducers to monitor the grouting compactness in real time. A segment of a commercial tendon duct was used as research object in this study. One lead zirconate titanate (PZT) piezoceramic transducer with marble protection, called a smart aggregate (SA), was bonded on the tendon and installed in the tendon duct. Two PZT patch sensors were mounted on the top outside surface of the duct, and one PZT patch sensor was bonded on the bottom outside surface of the tendon duct. In the active sensing approach, the SA was used as an actuator to generate a stress wave and the PZT sensors were utilized to detect the wave response. Cement or grout in the duct functions as a wave conduit, which can propagate the stress wave. If the cement or grout is not fully filled in the tendon duct, the top PZT sensors cannot receive much stress wave energy. The experimental procedures simulated four stages during the grout pouring process, which includes empty status, half grouting, 90% grouting, and full grouting of the duct. Experimental results show that the bottom PZT sensor can detect the signal when the grout level increases towards 50%, when a conduit between the SA and PZT sensor is formed. The top PZT sensors cannot receive any signal until the grout process is completely finished. The wavelet packet-based energy analysis was adopted in this research to

  13. Monitoring of Grouting Compactness in a Post-Tensioning Tendon Duct Using Piezoceramic Transducers

    PubMed Central

    Jiang, Tianyong; Kong, Qingzhao; Wang, Wenxi; Huo, Linsheng; Song, Gangbing

    2016-01-01

    A post-tensioning tendon duct filled with grout can effectively prevent corrosion of the reinforcement, maintain bonding behavior between the reinforcement and concrete, and enhance the load bearing capacity of concrete structures. In practice, grouting of the post-tensioning tendon ducts always causes quality problems, which may reduce structural integrity and service life, and even cause accidents. However, monitoring of the grouting compactness is still a challenge due to the invisibility of the grout in the duct during the grouting process. This paper presents a stress wave-based active sensing approach using piezoceramic transducers to monitor the grouting compactness in real time. A segment of a commercial tendon duct was used as research object in this study. One lead zirconate titanate (PZT) piezoceramic transducer with marble protection, called a smart aggregate (SA), was bonded on the tendon and installed in the tendon duct. Two PZT patch sensors were mounted on the top outside surface of the duct, and one PZT patch sensor was bonded on the bottom outside surface of the tendon duct. In the active sensing approach, the SA was used as an actuator to generate a stress wave and the PZT sensors were utilized to detect the wave response. Cement or grout in the duct functions as a wave conduit, which can propagate the stress wave. If the cement or grout is not fully filled in the tendon duct, the top PZT sensors cannot receive much stress wave energy. The experimental procedures simulated four stages during the grout pouring process, which includes empty status, half grouting, 90% grouting, and full grouting of the duct. Experimental results show that the bottom PZT sensor can detect the signal when the grout level increases towards 50%, when a conduit between the SA and PZT sensor is formed. The top PZT sensors cannot receive any signal until the grout process is completely finished. The wavelet packet-based energy analysis was adopted in this research to

  14. 3-D FDTD simulation of shear waves for evaluation of complex modulus imaging.

    PubMed

    Orescanin, Marko; Wang, Yue; Insana, Michael

    2011-02-01

    The Navier equation describing shear wave propagation in 3-D viscoelastic media is solved numerically with a finite differences time domain (FDTD) method. Solutions are formed in terms of transverse scatterer velocity waves and then verified via comparison to measured wave fields in heterogeneous hydrogel phantoms. The numerical algorithm is used as a tool to study the effects on complex shear modulus estimation from wave propagation in heterogeneous viscoelastic media. We used an algebraic Helmholtz inversion (AHI) technique to solve for the complex shear modulus from simulated and experimental velocity data acquired in 2-D and 3-D. Although 3-D velocity estimates are required in general, there are object geometries for which 2-D inversions provide accurate estimations of the material properties. Through simulations and experiments, we explored artifacts generated in elastic and dynamic-viscous shear modulus images related to the shear wavelength and average viscosity.

  15. AN AGENT-BASED SIMULATION STUDY OF A COMPLEX ADAPTIVE COLLABORATION NETWORK

    SciTech Connect

    Ozmen, Ozgur; Smith, Jeffrey; Yilmaz, Levent

    2013-01-01

    One of the most significant problems in organizational scholarship is to discern how social collectives govern, organize, and coordinate the actions of individuals to achieve collective outcomes. The collectives are usually interpreted as complex adaptive systems (CAS). The understanding of CAS is more likely to arise with the help of computer-based simulations. In this tutorial, using agent-based modeling approach, a complex adaptive social communication network model is introduced. The objective is to present the underlying dynamics of the system in a form of computer simulation that enables analyzing the impacts of various mechanisms on network topologies and emergent behaviors. The ultimate goal is to further our understanding of the dynamics in the system and facilitate developing informed policies for decision-makers.

  16. Molecular Dynamics Simulations of l-RNA Involving Homo- and Heterochiral Complexes.

    PubMed

    Dudek, Marta; Trylska, Joanna

    2017-03-14

    l-RNA is a mirror image of the naturally occurring d-RNA. We present the first simulations of l-RNA/d-RNA complexes in the AMBER ff10 force field that we modified to account for l-ribonucleotides. To validate the modifications we performed molecular dynamics simulations of several homo- and heterochiral RNA complexes. We did not observe any canonical base pairing in the l-/d-systems, but we found many repeatable geometric patterns that suggest possible structural motifs between the heterochiral RNA strands. The microscopic picture of l-RNA/d-RNA interface could help formulate the rules for designing l-RNAs with desired affinity toward specific d-RNA motifs.

  17. Average-Case Complexity Versus Approximate Simulation of Commuting Quantum Computations

    NASA Astrophysics Data System (ADS)

    Bremner, Michael J.; Montanaro, Ashley; Shepherd, Dan J.

    2016-08-01

    We use the class of commuting quantum computations known as IQP (instantaneous quantum polynomial time) to strengthen the conjecture that quantum computers are hard to simulate classically. We show that, if either of two plausible average-case hardness conjectures holds, then IQP computations are hard to simulate classically up to constant additive error. One conjecture relates to the hardness of estimating the complex-temperature partition function for random instances of the Ising model; the other concerns approximating the number of zeroes of random low-degree polynomials. We observe that both conjectures can be shown to be valid in the setting of worst-case complexity. We arrive at these conjectures by deriving spin-based generalizations of the boson sampling problem that avoid the so-called permanent anticoncentration conjecture.

  18. Multi-Agent-Based Simulation of a Complex Ecosystem of Mental Health Care.

    PubMed

    Kalton, Alan; Falconer, Erin; Docherty, John; Alevras, Dimitris; Brann, David; Johnson, Kyle

    2016-02-01

    This paper discusses the creation of an Agent-Based Simulation that modeled the introduction of care coordination capabilities into a complex system of care for patients with Serious and Persistent Mental Illness. The model describes the engagement between patients and the medical, social and criminal justice services they interact with in a complex ecosystem of care. We outline the challenges involved in developing the model, including process mapping and the collection and synthesis of data to support parametric estimates, and describe the controls built into the model to support analysis of potential changes to the system. We also describe the approach taken to calibrate the model to an observable level of system performance. Preliminary results from application of the simulation are provided to demonstrate how it can provide insights into potential improvements deriving from introduction of care coordination technology.

  19. Three-body interactions in complex fluids: Virial coefficients from simulation finite-size effects

    SciTech Connect

    Ashton, Douglas J.; Wilding, Nigel B.

    2014-06-28

    A simulation technique is described for quantifying the contribution of three-body interactions to the thermodynamical properties of coarse-grained representations of complex fluids. The method is based on a new approach for determining virial coefficients from the measured volume-dependent asymptote of a certain structural function. By comparing the third virial coefficient B{sub 3} for a complex fluid with that of an approximate coarse-grained model described by a pair potential, three body effects can be quantified. The strategy is applicable to both Molecular Dynamics and Monte Carlo simulation. Its utility is illustrated via measurements of three-body effects in models of star polymers and in highly size-asymmetrical colloid-polymer mixtures.

  20. Advanced Turbofan Duct Liner Concepts

    NASA Technical Reports Server (NTRS)

    Bielak, Gerald W.; Premo, John W.; Hersh, Alan S.

    1999-01-01

    The Advanced Subsonic Technology Noise Reduction Program goal is to reduce aircraft noise by 10 EPNdB by the year 2000 relative, to 1992 technology. The improvement goal for nacelle attenuation is 25% relative to 1992 technology by 1997 and 50% by 2000. The Advanced Turbofan Duct Liner Concepts Task work by Boeing presented in this document was in support of these goals. The basis for the technical approach was a Boeing study conducted in 1993-94 under NASA/FAA contract NAS1-19349, Task 6, investigating broadband acoustic liner concepts. As a result of this work, it was recommended that linear double layer, linear and perforate triple layer, parallel element, and bulk absorber liners be further investigated to improve nacelle attenuations. NASA LaRC also suggested that "adaptive" liner concepts that would allow "in-situ" acoustic impedance control also be considered. As a result, bias flow and high-temperature liner concepts were also added to the investigation. The major conclusion from the above studies is that improvements in nacelle liner average acoustic impedance characteristics alone will not result in 25% increased nacelle noise reduction relative to 1992 technology. Nacelle design advancements currently being developed by Boeing are expected to add 20-40% more acoustic lining to hardwall regions in current inlets, which is predicted to result in and additional 40-80% attenuation improvement. Similar advancements are expected to allow 10-30% more acoustic lining in current fan ducts with 10-30% more attenuation expected. In addition, Boeing is currently developing a scarf inlet concept which is expected to give an additional 40-80% attenuation improvement for equivalent lining areas.

  1. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics

    PubMed Central

    Shetty, Dinesh A.; Frankel, Steven H.

    2013-01-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. [Journal of Computational Physics 2010; 229 (23), 8802-8822]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of

  2. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics.

    PubMed

    Anupindi, Kameswararao; Delorme, Yann; Shetty, Dinesh A; Frankel, Steven H

    2013-12-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. [Journal of Computational Physics 2010; 229 (23), 8802-8822]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of

  3. Simulation and fitting of complex reaction network TPR: The key is the objective function

    NASA Astrophysics Data System (ADS)

    Savara, Aditya

    2016-11-01

    A method has been developed for finding improved fits during simulation and fitting of data from complex reaction network temperature programmed reactions (CRN-TPR). It was found that simulation and fitting of CRN-TPR presents additional challenges relative to simulation and fitting of simpler TPR systems. The method used here can enable checking the plausibility of proposed chemical mechanisms and kinetic models. The most important finding was that when choosing an objective function, use of an objective function that is based on integrated production provides more utility in finding improved fits when compared to an objective function based on the rate of production. The response surface produced by using the integrated production is monotonic, suppresses effects from experimental noise, requires fewer points to capture the response behavior, and can be simulated numerically with smaller errors. For CRN-TPR, there is increased importance (relative to simple reaction network TPR) in resolving of peaks prior to fitting, as well as from weighting of experimental data points. Using an implicit ordinary differential equation solver was found to be inadequate for simulating CRN-TPR. The method employed here was capable of attaining improved fits in simulation and fitting of CRN-TPR when starting with a postulated mechanism and physically realistic initial guesses for the kinetic parameters.

  4. Simulation and fitting of complex reaction network TPR: The key is the objective function

    SciTech Connect

    Savara, Aditya Ashi

    2016-07-07

    In this research, a method has been developed for finding improved fits during simulation and fitting of data from complex reaction network temperature programmed reactions (CRN-TPR). It was found that simulation and fitting of CRN-TPR presents additional challenges relative to simulation and fitting of simpler TPR systems. The method used here can enable checking the plausibility of proposed chemical mechanisms and kinetic models. The most important finding was that when choosing an objective function, use of an objective function that is based on integrated production provides more utility in finding improved fits when compared to an objective function based on the rate of production. The response surface produced by using the integrated production is monotonic, suppresses effects from experimental noise, requires fewer points to capture the response behavior, and can be simulated numerically with smaller errors. For CRN-TPR, there is increased importance (relative to simple reaction network TPR) in resolving of peaks prior to fitting, as well as from weighting of experimental data points. Using an implicit ordinary differential equation solver was found to be inadequate for simulating CRN-TPR. Lastly, the method employed here was capable of attaining improved fits in simulation and fitting of CRN-TPR when starting with a postulated mechanism and physically realistic initial guesses for the kinetic parameters.

  5. Simulation and fitting of complex reaction network TPR: The key is the objective function

    DOE PAGES

    Savara, Aditya Ashi

    2016-07-07

    In this research, a method has been developed for finding improved fits during simulation and fitting of data from complex reaction network temperature programmed reactions (CRN-TPR). It was found that simulation and fitting of CRN-TPR presents additional challenges relative to simulation and fitting of simpler TPR systems. The method used here can enable checking the plausibility of proposed chemical mechanisms and kinetic models. The most important finding was that when choosing an objective function, use of an objective function that is based on integrated production provides more utility in finding improved fits when compared to an objective function based onmore » the rate of production. The response surface produced by using the integrated production is monotonic, suppresses effects from experimental noise, requires fewer points to capture the response behavior, and can be simulated numerically with smaller errors. For CRN-TPR, there is increased importance (relative to simple reaction network TPR) in resolving of peaks prior to fitting, as well as from weighting of experimental data points. Using an implicit ordinary differential equation solver was found to be inadequate for simulating CRN-TPR. Lastly, the method employed here was capable of attaining improved fits in simulation and fitting of CRN-TPR when starting with a postulated mechanism and physically realistic initial guesses for the kinetic parameters.« less

  6. Assessment of complex dissociative disorder patients and simulated dissociation in forensic contexts.

    PubMed

    Brand, Bethany L; Webermann, Aliya R; Frankel, A Steven

    Few assessors receive training in assessing dissociation and complex dissociative disorders (DDs). Potential differential diagnoses include anxiety, mood, psychotic, substance use, and personality disorders, as well as exaggeration and malingering. Individuals with DDs typically elevate on many clinical and validity scales on psychological tests, yet research indicates that they can be distinguished from DD simulators. Becoming informed about the testing profiles of DD individuals and DD simulators can improve the accuracy of differential diagnoses in forensic settings. In this paper, we first review the testing profiles of individuals with complex DDs and contrast them with DD simulators on assessment measures used in forensic contexts, including the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Personality Assessment Inventory (PAI), and the Structured Inventory of Reported Symptoms (SIRS), as well as dissociation-specific measures such as the Dissociative Experiences Scale (DES) and Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D-R). We then provide recommendations for assessing complex trauma and dissociation through the aforementioned assessments.

  7. The Geometric Cluster Algorithm: Rejection-Free Monte Carlo Simulation of Complex Fluids

    NASA Astrophysics Data System (ADS)

    Luijten, Erik

    2005-03-01

    The study of complex fluids is an area of intense research activity, in which exciting and counter-intuitive behavior continue to be uncovered. Ironically, one of the very factors responsible for such interesting properties, namely the presence of multiple relevant time and length scales, often greatly complicates accurate theoretical calculations and computer simulations that could explain the observations. We have recently developed a new Monte Carlo simulation methodootnotetextJ. Liu and E. Luijten, Phys. Rev. Lett.92, 035504 (2004); see also Physics Today, March 2004, pp. 25--27. that overcomes this problem for several classes of complex fluids. Our approach can accelerate simulations by orders of magnitude by introducing nonlocal, collective moves of the constituents. Strikingly, these cluster Monte Carlo moves are proposed in such a manner that the algorithm is rejection-free. The identification of the clusters is based upon geometric symmetries and can be considered as the off-latice generalization of the widely-used Swendsen--Wang and Wolff algorithms for lattice spin models. While phrased originally for complex fluids that are governed by the Boltzmann distribution, the geometric cluster algorithm can be used to efficiently sample configurations from an arbitrary underlying distribution function and may thus be applied in a variety of other areas. In addition, I will briefly discuss various extensions of the original algorithm, including methods to influence the size of the clusters that are generated and ways to introduce density fluctuations.

  8. Molecular dynamics simulations of DNA/PEI complexes: effect of PEI branching and protonation state.

    PubMed

    Sun, Chongbo; Tang, Tian; Uludağ, Hasan; Cuervo, Javier E

    2011-06-08

    Complexes formed by DNA and polyethylenimine (PEI) are of great research interest because of their application in gene therapy. In this work, we carried out all-atom molecular dynamics simulations to study eight types of DNA/PEI complexes, each of which was formed by one DNA duplex d(CGCGAATTCGCG)(2) and one PEI. We used eight different PEIs with four different degrees of branching and two protonation ratios of amine groups (23% and 46%) in the simulations to investigate how the branching degree and protonation state can affect the binding. We found that 46% protonated PEIs form more stable complexes with DNA, and the binding is achieved mainly through direct interaction between the protonated amine groups on PEI and the electronegative oxygens on the DNA backbone, with some degree of interaction with electronegative groove nitrogens/oxygens. For the 23% protonated PEIs, indirect interaction mediated by one or more water molecules plays an important role in binding. Compared with the protonation state, the degree of branching has a smaller effect on binding, which essentially diminishes at the protonation ratio of 46%. These simulations shed light on the detailed mechanism(s) of PEI binding to DNA, and may facilitate the design of PEI-based gene delivery carriers.

  9. Specific DNA recognition by the Antp homeodomain: MD simulations of specific and nonspecific complexes.

    PubMed

    Gutmanas, Aleksandras; Billeter, Martin

    2004-12-01

    Four molecular dynamics simulation trajectories of complexes between the wild-type or a mutant Antennapedia homeodomain and 2 DNA sequences were generated in order to probe the mechanisms governing the specificity of DNA recognition. The starting point was published affinity measurements showing that a single protein mutation combined with a replacement of 2 base pairs yields a new high-affinity complex, whereas the other combinations, with changes on only 1 macromolecule, exhibited lower affinity. The simulations of the 4 complexes yielded fluctuating networks of interaction. On average, these networks differ significantly, explaining the switch of affinity caused by the alterations in the macromolecules. The network of mostly hydrogen-bonding interactions involving several water molecules, which was suggested both by X-ray and NMR structures of the wild-type homeodomain and its DNA operator sequence, could be reproduced in the trajectory. More interestingly, the high-affinity complex with alterations in both the protein and the DNA yielded again a dynamic but very tight network of intermolecular interactions, however, attributing a significantly stronger role to direct hydrophobic interactions at the expense of water bridges. The other 2 homeodomain-DNA complexes, with only 1 molecule altered, show on average over the trajectories a clearly reduced number of protein-DNA interactions. The observations from these simulations suggest specific experiments and thus close the circle formed by biochemical, structural, and computational studies. The shift from a water-dominated to a more "dry" interface may prove important in the design of proteins binding DNA in a specific manner.

  10. Magnetic Resonance (MR) Cholangiopancreatography Demonstration of the Cystic Duct Entering the Right Hepatic Duct

    PubMed Central

    D’Angelo, Tommaso; Racchiusa, Sergio; Mazziotti, Silvio; Cicero, Giuseppe

    2017-01-01

    Patient: Female, 51 Final Diagnosis: Cystic duct draining into the right hepatic biliary duct Symptoms: Recurrent abdominal pain Medication: — Clinical Procedure: MR-cholangiopancreatography Specialty: Radiology Objective: Congenital defects/diseases Background: MR cholangiopancreatography is widely performed before laparoscopic cholecystectomy to rule out choledocholithiasis and to avoid iatrogenic injuries that may be related to the high frequency of anatomical variations of the biliary tree. Although most of these variants have already been demonstrated surgically and by endoscopic retrograde cholangiopancreatography and CT cholangiography, there are no references in which MR cholangiopancreatography has shown a cystic duct draining into the right hepatic biliary duct. Case Report: A 51-year-old woman with a history of recurrent abdominal pain underwent an abdominal ultrasound in an outside center, which revealed gallbladder cholelithiasis. In this patient, an MR cholangiopancreatography was performed and the laboratory data were obtained. Laboratory findings showed only a mild increase of cholestasis. MRCP did not reveal significant dilatation of intra- or extrahepatic biliary ducts, while the cystic duct showed an atypical insertion, draining directly into the right hepatic duct. Conclusions: To avoid unintentional bile duct injuries, MRCP evaluation of the biliary anatomy is particularly important for pre-operative evaluation of patients undergoing laparoscopic cholecystectomy. In particular, in the case we describe, the right hepatic duct might have been mistaken for the cystic duct, with potentially severe surgical complications and clinical consequences. PMID:28275221

  11. Investigation in the 7-By-10 Foot Wind Tunnel of Ducts for Cooling Radiators Within an Airplane Wing, Special Report

    NASA Technical Reports Server (NTRS)

    Harris, Thomas A.; Recant, Isidore G.

    1938-01-01

    An investigation was made in the NACA 7- by 10-foot wind tunnel of a large-chord wing model with a duct to house a simulated radiator suitable for a liquid-cooled engine. The duct was expanded to reduce the radiator losses, and the installation of the duct and radiator was made entirely within the wing to reduce form and interference drag. The tests were made using a two-dimensional flow set-up with a full-span duct and radiator. Section aerodynamic characteristics of the basic airfoil are given and also curves showing the characteristics of the various duct-radiator combinations. An expression for efficiency, the primary criterion of merit of any duct, and the effect of the several design parameters of the duct-radiator arrangement are discussed. The problem of throttling is considered and a discussion of the power required for cooling is included. It was found that radiators could be mounted in the wing and efficiently pass enough air for cooling with duct outlets located at any point from 0.25c to 0.70c from the wing leading edge on the upper surface. The duct-inlet position was found to be critical and, for maximum efficiency, had to be at the stagnation point of the airfoil and to change with flight attitude. The flow could be efficiently throttled only by a simultaneous variation of duct inlet and outlet sizes and of inlet position. It was desirable to round both inlet and outlet lips. With certain arrangements of duct, the power required for cooling at high speed was a very low percentage of the engine power.

  12. When can a high-resolution simulation over complex terrain be called LES?

    NASA Astrophysics Data System (ADS)

    Cuxart, Joan

    2015-12-01

    The ceaseless rise of computational power leads to a continuous increase of the resolution of the numerical models of the atmosphere. It is found today that operational models are run at horizontal resolutions near 1 km whereas research exercises for flows over complex terrain use resolutions at the hectometer scale. Horizontal resolutions of 100 m or finer have been used to perform Large-Eddy Simulations (LES) for some specific regimes like, e.g., the atmospheric boundary-layer in idealized configurations. However, to use the name "Large-Eddy Simulation" implies to be able to resolve at least the largest turbulent energetic eddies, which is almost impossible to reach with resolutions of the order of 100m for a real case, where many different processes occur linked to different scales, many of them even smaller than 100 m. Therefore, LES is an inappropriate denomination for these numerical exercises, that may simply be called High-Resolution Mesoscale Simulations.

  13. Characterization of the secondary flow in hexagonal ducts

    NASA Astrophysics Data System (ADS)

    Marin, O.; Vinuesa, R.; Obabko, A. V.; Schlatter, P.

    2016-12-01

    In this work we report the results of DNSs and LESs of the turbulent flow through hexagonal ducts at friction Reynolds numbers based on centerplane wall shear and duct half-height Reτ,c ≃ 180, 360, and 550. The evolution of the Fanning friction factor f with Re is in very good agreement with experimental measurements. A significant disagreement between the DNS and previous RANS simulations was found in the prediction of the in-plane velocity, and is explained through the inability of the RANS model to properly reproduce the secondary flow present in the hexagon. The kinetic energy of the secondary flow integrated over the cross-sectional area yz decreases with Re in the hexagon, whereas it remains constant with Re in square ducts at comparable Reynolds numbers. Close connection between the values of Reynolds stress u w ¯ on the horizontal wall close to the corner and the interaction of bursting events between the horizontal and inclined walls is found. This interaction leads to the formation of the secondary flow, and is less frequent in the hexagon as Re increases due to the 120∘ aperture of its vertex, whereas in the square duct the 90∘ corner leads to the same level of interaction with increasing Re. Analysis of turbulence statistics at the centerplane and the azimuthal variance of the mean flow and the fluctuations shows a close connection between hexagonal ducts and pipe flows, since the hexagon exhibits near-axisymmetric conditions up to a distance of around 0.15DH measured from its center. Spanwise distributions of wall-shear stress show that in square ducts the 90∘ corner sets the location of a high-speed streak at a distance zv+≃50 from it, whereas in hexagons the 120∘ aperture leads to a shorter distance of zv+≃38 . At these locations the root mean square of the wall-shear stresses exhibits an inflection point, which further shows the connections between the near-wall structures and the large-scale motions in the outer flow.

  14. The identification of complex interactions in epidemiology and toxicology: a simulation study of boosted regression trees

    PubMed Central

    2014-01-01

    Background There is a need to evaluate complex interaction effects on human health, such as those induced by mixtures of environmental contaminants. The usual approach is to formulate an additive statistical model and check for departures using product terms between the variables of interest. In this paper, we present an approach to search for interaction effects among several variables using boosted regression trees. Methods We simulate a continuous outcome from real data on 27 environmental contaminants, some of which are correlated, and test the method’s ability to uncover the simulated interactions. The simulated outcome contains one four-way interaction, one non-linear effect and one interaction between a continuous variable and a binary variable. Four scenarios reflecting different strengths of association are simulated. We illustrate the method using real data. Results The method succeeded in identifying the true interactions in all scenarios except where the association was weakest. Some spurious interactions were also found, however. The method was also capable to identify interactions in the real data set. Conclusions We conclude that boosted regression trees can be used to uncover complex interaction effects in epidemiological studies. PMID:24993424

  15. Comparison of Measured and Numerically Simulated Turbulence Statistics in a Convective Boundary Layer Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Rai, Raj K.; Berg, Larry K.; Kosović, Branko; Mirocha, Jeffrey D.; Pekour, Mikhail S.; Shaw, William J.

    2017-04-01

    The Weather Research and Forecasting (WRF) model can be used to simulate atmospheric processes ranging from quasi-global to tens of m in scale. Here we employ large-eddy simulation (LES) using the WRF model, with the LES-domain nested within a mesoscale WRF model domain with grid spacing decreasing from 12.15 km (mesoscale) to 0.03 km (LES). We simulate real-world conditions in the convective planetary boundary layer over an area of complex terrain. The WRF-LES model results are evaluated against observations collected during the US Department of Energy-supported Columbia Basin Wind Energy Study. Comparison of the first- and second-order moments, turbulence spectrum, and probability density function of wind speed shows good agreement between the simulations and observations. One key result is to demonstrate that a systematic methodology needs to be applied to select the grid spacing and refinement ratio used between domains, to avoid having a grid resolution that falls in the grey zone and to minimize artefacts in the WRF-LES model solutions. Furthermore, the WRF-LES model variables show large variability in space and time caused by the complex topography in the LES domain. Analyses of WRF-LES model results show that the flow structures, such as roll vortices and convective cells, vary depending on both the location and time of day as well as the distance from the inflow boundaries.

  16. GPU simulation of nonlinear propagation of dual band ultrasound pulse complexes

    SciTech Connect

    Kvam, Johannes Angelsen, Bjørn A. J.; Elster, Anne C.

    2015-10-28

    In a new method of ultrasound imaging, called SURF imaging, dual band pulse complexes composed of overlapping low frequency (LF) and high frequency (HF) pulses are transmitted, where the frequency ratio LF:HF ∼ 1 : 20, and the relative bandwidth of both pulses are ∼ 50 − 70%. The LF pulse length is hence ∼ 20 times the HF pulse length. The LF pulse is used to nonlinearly manipulate the material elasticity observed by the co-propagating HF pulse. This produces nonlinear interaction effects that give more information on the propagation of the pulse complex. Due to the large difference in frequency and pulse length between the LF and the HF pulses, we have developed a dual level simulation where the LF pulse propagation is first simulated independent of the HF pulse, using a temporal sampling frequency matched to the LF pulse. A separate equation for the HF pulse is developed, where the the presimulated LF pulse modifies the propagation velocity. The equations are adapted to parallel processing in a GPU, where nonlinear simulations of a typical HF beam of 10 MHz down to 40 mm is done in ∼ 2 secs in a standard GPU. This simulation is hence very useful for studying the manipulation effect of the LF pulse on the HF pulse.

  17. Comparison of Measured and Numerically Simulated Turbulence Statistics in a Convective Boundary Layer Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Rai, Raj K.; Berg, Larry K.; Kosović, Branko; Mirocha, Jeffrey D.; Pekour, Mikhail S.; Shaw, William J.

    2016-11-01

    The Weather Research and Forecasting (WRF) model can be used to simulate atmospheric processes ranging from quasi-global to tens of m in scale. Here we employ large-eddy simulation (LES) using the WRF model, with the LES-domain nested within a mesoscale WRF model domain with grid spacing decreasing from 12.15 km (mesoscale) to 0.03 km (LES). We simulate real-world conditions in the convective planetary boundary layer over an area of complex terrain. The WRF-LES model results are evaluated against observations collected during the US Department of Energy-supported Columbia Basin Wind Energy Study. Comparison of the first- and second-order moments, turbulence spectrum, and probability density function of wind speed shows good agreement between the simulations and observations. One key result is to demonstrate that a systematic methodology needs to be applied to select the grid spacing and refinement ratio used between domains, to avoid having a grid resolution that falls in the grey zone and to minimize artefacts in the WRF-LES model solutions. Furthermore, the WRF-LES model variables show large variability in space and time caused by the complex topography in the LES domain. Analyses of WRF-LES model results show that the flow structures, such as roll vortices and convective cells, vary depending on both the location and time of day as well as the distance from the inflow boundaries.

  18. Modelling and simulation of complex sociotechnical systems: envisioning and analysing work environments

    PubMed Central

    Hettinger, Lawrence J.; Kirlik, Alex; Goh, Yang Miang; Buckle, Peter

    2015-01-01

    Accurate comprehension and analysis of complex sociotechnical systems is a daunting task. Empirically examining, or simply envisioning the structure and behaviour of such systems challenges traditional analytic and experimental approaches as well as our everyday cognitive capabilities. Computer-based models and simulations afford potentially useful means of accomplishing sociotechnical system design and analysis objectives. From a design perspective, they can provide a basis for a common mental model among stakeholders, thereby facilitating accurate comprehension of factors impacting system performance and potential effects of system modifications. From a research perspective, models and simulations afford the means to study aspects of sociotechnical system design and operation, including the potential impact of modifications to structural and dynamic system properties, in ways not feasible with traditional experimental approaches. This paper describes issues involved in the design and use of such models and simulations and describes a proposed path forward to their development and implementation. Practitioner Summary: The size and complexity of real-world sociotechnical systems can present significant barriers to their design, comprehension and empirical analysis. This article describes the potential advantages of computer-based models and simulations for understanding factors that impact sociotechnical system design and operation, particularly with respect to process and occupational safety. PMID:25761227

  19. Self-assembly of polyelectrolyte surfactant complexes using large scale MD simulation

    NASA Astrophysics Data System (ADS)

    Goswami, Monojoy; Sumpter, Bobby

    2014-03-01

    Polyelectrolytes (PE) and surfactants are known to form interesting structures with varied properties in aqueous solutions. The morphological details of the PE-surfactant complexes depend on a combination of polymer backbone, electrostatic interactions and hydrophobic interactions. We study the self-assembly of cationic PE and anionic surfactants complexes in dilute condition. The importance of such complexes of PE with oppositely charged surfactants can be found in biological systems, such as immobilization of enzymes in polyelectrolyte complexes or nonspecific association of DNA with protein. Many useful properties of PE surfactant complexes come from the highly ordered structures of surfactant self-assembly inside the PE aggregate which has applications in industry. We do large scale molecular dynamics simulation using LAMMPS to understand the structure and dynamics of PE-surfactant systems. Our investigation shows highly ordered pearl-necklace structures that have been observed experimentally in biological systems. We investigate many different properties of PE-surfactant complexation for different parameter ranges that are useful for pharmaceutical, engineering and biological applications.

  20. FACET: A simulation software framework for modeling complex societal processes and interactions

    SciTech Connect

    Christiansen, J. H.

    2000-06-02

    FACET, the Framework for Addressing Cooperative Extended Transactions, was developed at Argonne National Laboratory to address the need for a simulation software architecture in the style of an agent-based approach, but with sufficient robustness, expressiveness, and flexibility to be able to deal with the levels of complexity seen in real-world social situations. FACET is an object-oriented software framework for building models of complex, cooperative behaviors of agents. It can be used to implement simulation models of societal processes such as the complex interplay of participating individuals and organizations engaged in multiple concurrent transactions in pursuit of their various goals. These transactions can be patterned on, for example, clinical guidelines and procedures, business practices, government and corporate policies, etc. FACET can also address other complex behaviors such as biological life cycles or manufacturing processes. To date, for example, FACET has been applied to such areas as land management, health care delivery, avian social behavior, and interactions between natural and social processes in ancient Mesopotamia.

  1. Dispersion of particles in complex terrain: comparisons between WRF LES and simulations using different PBL schemes

    NASA Astrophysics Data System (ADS)

    Xue, L.; Kosovic, B.; Tessendorf, S. A.; Rasmussen, R.

    2015-12-01

    A key process in wintertime orographic cloud seeding using ground-based generators is the dispersion of silver iodide particles released from the generators in the mountainous area. The dispersion features determine the targeting efficiency and ultimately the seeding effect on the ground under favorable seeding conditions. Previous field experiments showed that the silver iodide plumes were narrow (spread angle was around 20 degrees) and were confined within the mountainous boundary layer (usually lower than 1 km AGL). The numerical simulation of the particle dispersion in complex terrain using weather models is challenging due to the stable atmosphere in winter, the unresolved terrain-flow interaction, and the inherent numerical diffusion close to the source point in the Eulerian framework. A recent study by Xue et al. (2014) showed that Large Eddy Simulation (LES) of the particle dispersion in complex terrain with grid spacing of 100 m could reproduce most observed features while simulations using PBL schemes with 500 m grid spacing had difficulty reproducing the vertical dispersion. This study will simulate the same case using the Weather Research and Forecasting (WRF) model in LES mode and with several PBL schemes. The differences between the LES-simulated dispersion results and the PBL results will be analyzed and presented. Especially, the difference attributed to the unrepresented sub-grid scale (SGS) topography information in the PBL will be studied in detail. The ultimate goal of this study is to incorporate the dispersion due to turbulent kinetic energy induced by SGS topography into the existing PBL schemes to better simulate the process in mountainous regions.

  2. The influence of simulation model complexity on the estimation of internal loading in gymnastics landings.

    PubMed

    Mills, Chris; Pain, Matthew T G; Yeadon, Maurice R

    2008-01-01

    Evaluating landing technique using a computer simulation model of a gymnast and landing mat could be a useful tool when attempting to assess injury risk. The aims of this study were: (1) to investigate whether a subject-specific torque-driven or a subject-specific muscle-driven model of a gymnast is better at matching experimental ground reaction forces and kinematics during gymnastics landings, (2) to calculate their respective simulation run times and (3) to determine what level of model complexity is required to assess injury risk. A subject-specific planar seven-link wobbling mass model of a gymnast and a multi-layer model of a landing mat were developed for this study. Subject-specific strength parameters were determined which defined the maximum voluntary torque/angle/angular velocity relationship about each joint. This relationship was also used to produce subject-specific 'lumped' muscle models for each joint. Kinetic and kinematic data were obtained during landings from backward and forward rotating gymnastics vaults. Both torque-driven and muscle-driven models were capable of producing simulated landings that matched the actual performances (with overall percentage differences between 10.1% and 18.2%). The torque-driven model underestimated the internal loading on joints and bones, resulting in joint reaction forces that were less than 50% of those calculated using the muscle-driven model. Simulation time increased from approximately 3 min (torque driven) to more than 10 min (muscle driven) as model complexity increased. The selection of a simulation model for assessing injury risk must consider the need for determining realistic internal forces as the priority despite increases in simulation run time.

  3. The role of microphysical processes on the mesoscale simulation over the complex terrain, the Himalayas

    NASA Astrophysics Data System (ADS)

    Shrestha, R. K.; Gallagher, M. W.; Connolly, P.

    2010-12-01

    The objective of this study is to evaluate the impact of the four different cloud microphysical schemes (WSM3, WSM6, Morrison double moment and Lin scheme) within the Weather Research and Forecasting model (WRF), as part of simulations of mesoscale weather systems across complex terrain in the Nepalese Himalayas. The Himalayas is characterized by a complex and rugged topography, with altitudes varying e.g. 70m in Southeastern Nepal, to the highest peak of the world, 8850m (Mt. Everest), and which extends from West to East covering many South and Central Asian countries: Afghanistan, Pakistan, China, India, Nepal, Bhutan, and Myanmar. Circulation in such a complex environment is complicated due to obstruction of flows by mountain ranges which in turn have wide ranging effects on cloud and rain formation and distribution. Monsoon rain is intrinsically linked to people’s daily life across the South Asia since more than 80% people depend on agriculture and majority of the agricultural systems are rainfall dependent. Modeling of the key microphysical process in this complex terrain provides insight into the general understanding of the processes and their spatial patterns, however there are many uncertainties in general. These uncertainties are even more pronounced when such models are applied to the complex terrain characteristic of the Himalayas. Numerical experiments are designed using the WRF model, with three nested domains (27, 9 and 3 km grid spacing). The performance of the four categories of microphysical schemes is examined in model experiments for (i) monsoon onset, (ii) monsoon decay and (iii) winter rainfall. The simulated results are compared with limited observed meteorological parameters such as rainfall, temperature, wind speed and wind direction, from ground-based meteorological stations situated within the high resolution (3km x 3km) domain. Results show that a) Simulated rainfall is very sensitive to the chosen microphysical scheme with rainfall

  4. URDME: a modular framework for stochastic simulation of reaction-transport processes in complex geometries

    PubMed Central

    2012-01-01

    Background Experiments in silico using stochastic reaction-diffusion models have emerged as an important tool in molecular systems biology. Designing computational software for such applications poses several challenges. Firstly, realistic lattice-based modeling for biological applications requires a consistent way of handling complex geometries, including curved inner- and outer boundaries. Secondly, spatiotemporal stochastic simulations are computationally expensive due to the fast time scales of individual reaction- and diffusion events when compared to the biological phenomena of actual interest. We therefore argue that simulation software needs to be both computationally efficient, employing sophisticated algorithms, yet in the same time flexible in order to meet present and future needs of increasingly complex biological modeling. Results We have developed URDME, a flexible software framework for general stochastic reaction-transport modeling and simulation. URDME uses Unstructured triangular and tetrahedral meshes to resolve general geometries, and relies on the Reaction-Diffusion Master Equation formalism to model the processes under study. An interface to a mature geometry and mesh handling external software (Comsol Multiphysics) provides for a stable and interactive environment for model construction. The core simulation routines are logically separated from the model building interface and written in a low-level language for computational efficiency. The connection to the geometry handling software is realized via a Matlab interface which facilitates script computing, data management, and post-processing. For practitioners, the software therefore behaves much as an interactive Matlab toolbox. At the same time, it is possible to modify and extend URDME with newly developed simulation routines. Since the overall design effectively hides the complexity of managing the geometry and meshes, this means that newly developed methods may be tested in a realistic

  5. Paraurethral Skene's duct cyst in a newborn

    PubMed Central

    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

  6. Magnetospheric whistler ducts observed by ISIS satellites

    NASA Technical Reports Server (NTRS)

    Ondoh, T.

    1976-01-01

    The latitudinal width of the magnetospheric whistler duct has been estimated by the first and final invariant latitudes of whistler echoes and the conservation of the magnetic flux for the centered dipole field, using 105 whistler echoes in ISIS VLF data received at Kashima, Japan for 1972-1973. The latitudinal distribution of whistler duct occurrence shows a maximum at invariant latitudes of 40-45 degrees near the maximum occurrence latitude of ground whistlers. The radial width of magnetospheric whistler duct in the geomagnetically equatorial plane increases with invariant latitude of the geomagnetic flux tube in which whistlers propagate.

  7. Duct Remediation Program: Remediation operations and implementation

    SciTech Connect

    Beckman, T.d.; Davis, M.M.; Karas, T.M.

    1992-11-01

    Plutonium holdup material has accumulated in the process ventilation duct systems at Rocky Flats. Non-Destructive Assay (NDA) measurements identified ducts containing this material. The Defense Nuclear Facility Safety Board and the Department of Energy established the criteria for remediation of these ducts. A remediation team was assembled and a program plan created. This program plan included activities such as fissile material accumulation identification, criticality safety assessments, radiation dose determinations, facility safety evaluations, prevention of future accumulation, and removal of holdup material. Several operational considerations had to be evaluated in determining completion of remediation.

  8. Atomic Simulation of Complex DNA DSBs and the Interactions with the Ku70/80 Heterodimer

    NASA Technical Reports Server (NTRS)

    Hu, Shaowen; Cucinotta, Francis A.

    2011-01-01

    DNA double strand breaks (DSBs) induced by ionizing radiation (IR) usually contain modified bases such as 8-oxo-7,8-dihydroguanine (8-oxoG) and thymine glycol, apurinic/apyrimidinic (AP) sites, 2-deoxyribonolactone, or single-strand breaks (SSBs). The presence of such lesions in close proximity to the DSB terminus makes the DNA nicks more difficult to repair and rejoin than endogenously induced simple DSBs, and as such a major determinant of the biological effects of high linear energy transfer (LET) radiation as encountered in space travel. In this study we conducted molecular dynamics simulations on a series of DNA duplexes with various complex lesions of 8-oxoG and AP sites, in an effort to investigate the effects of such lesions to the structural integrity and stability of DNA after insulted by IR. We also simulated the interaction of such complex DSBs with the Ku70/80 heterodimer, the first protein in mammalian cells to embark the non-homologous end joining (NHEJ) DNA repair pathway. The results indicate, compared to DNA with simple DSBs, the complex lesions can enhance the hydrogen bonds opening rate at the DNA terminus, and increase the mobility of the whole duplex, thus they present more deleterious effects to the genome integrity if not captured and repaired promptly in cells. Simulations also demonstrate the binding of Ku drastically reduces structural disruption and flexibility caused by the complex lesions, and the interactions of Ku with complex DSBs have a different potential energy landscape from the bound structure with simple DSB. In all complex DSBs systems, the binding of DSB terminus with Ku70 is softened while the binding of the middle duplex with Ku80 is tightened. This energy shift may help the Ku protein to secure at the DSB terminus for a longer time, so that other end processing factors or repair pathways can proceed at the lesions before NHEJ repair process starts. These atomic simulations may provide valuable new insight into the

  9. Atomic level insights into realistic molecular models of dendrimer-drug complexes through MD simulations

    NASA Astrophysics Data System (ADS)

    Jain, Vaibhav; Maiti, Prabal K.; Bharatam, Prasad V.

    2016-09-01

    Computational studies performed on dendrimer-drug complexes usually consider 1:1 stoichiometry, which is far from reality, since in experiments more number of drug molecules get encapsulated inside a dendrimer. In the present study, molecular dynamic (MD) simulations were implemented to characterize the more realistic molecular models of dendrimer-drug complexes (1:n stoichiometry) in order to understand the effect of high drug loading on the structural properties and also to unveil the atomistic level details. For this purpose, possible inclusion complexes of model drug Nateglinide (Ntg) (antidiabetic, belongs to Biopharmaceutics Classification System class II) with amine- and acetyl-terminated G4 poly(amidoamine) (G4 PAMAM(NH2) and G4 PAMAM(Ac)) dendrimers at neutral and low pH conditions are explored in this work. MD simulation analysis on dendrimer-drug complexes revealed that the drug encapsulation efficiency of G4 PAMAM(NH2) and G4 PAMAM(Ac) dendrimers at neutral pH was 6 and 5, respectively, while at low pH it was 12 and 13, respectively. Center-of-mass distance analysis showed that most of the drug molecules are located in the interior hydrophobic pockets of G4 PAMAM(NH2) at both the pH; while in the case of G4 PAMAM(Ac), most of them are distributed near to the surface at neutral pH and in the interior hydrophobic pockets at low pH. Structural properties such as radius of gyration, shape, radial density distribution, and solvent accessible surface area of dendrimer-drug complexes were also assessed and compared with that of the drug unloaded dendrimers. Further, binding energy calculations using molecular mechanics Poisson-Boltzmann surface area approach revealed that the location of drug molecules in the dendrimer is not the decisive factor for the higher and lower binding affinity of the complex, but the charged state of dendrimer and drug, intermolecular interactions, pH-induced conformational changes, and surface groups of dendrimer do play an

  10. Scattering of acoustic duct modes by axial liner splices

    NASA Astrophysics Data System (ADS)

    Tam, Christopher K. W.; Ju, Hongbin; Chien, Eugene W.

    2008-03-01

    Recent engine test data and results of computational analysis show that the engine inlet acoustic liner splices have a significant impact on aircraft flight noise certification and cabin noise levels. The phenomenon of scattering of acoustic duct modes by axial liner splices is investigated. Previous studies, invariably, follow the frequency-domain approach. The present study, however, uses the time-domain approach. It is demonstrated that time-domain computation yields results that are in close agreement with frequency-domain results. The scattering phenomenon under consideration is very complex. This study concentrates on the effects of four parameters. They are the width of the splices, the frequency of the incident duct mode, the number of splices and the length of splices. Based on the computed results, the conditions under which scattered wave modes would significantly increase the intensity of transmitted waves are identified. It is also found that surface scattering by liner splices has the tendency to distribute energy equally to all the cut-on scattered azimuthal modes. On the other hand, for each scattered azimuthal mode, the high-order cut-on radial mode, generally, has the highest intensity. Moreover, scattering by liner splices is a local phenomenon. It is confined primarily to an area of the duct adjacent to the junction between the hard wall near the fan face and the spliced liner.

  11. Examination of Duct Physiology in the Human Mammary Gland

    PubMed Central

    Mills, Dixie; Gomberawalla, Ameer; Gordon, Eva J.; Tondre, Julie; Nejad, Mitra; Nguyen, Tinh; Pogoda, Janice M.; Rao, Jianyu; Chatterton, Robert; Henning, Susanne; Love, Susan M.

    2016-01-01

    Background The human breast comprise several ductal systems, or lobes, which contain a small amount of fluid containing cells, hormones, proteins and metabolites. The complex physiology of these ducts is likely a contributing factor to the development of breast cancer, especially given that the vast majority of breast cancers begin in a single lobular unit. Methods We examined the levels of total protein, progesterone, estradiol, estrone sulfate, dehydroepiandrosterone sulfate, and macrophages in ductal fluid samples obtained from 3 ducts each in 78 women, sampled twice over a 6 month period. Samples were processed for both cytological and molecular analysis. Intraclass correlation coefficients and mixed models were utilized to identify significant data. Results We found that the levels of these ductal fluid components were generally uncorrelated among ducts within a single breast and over time, suggesting that each lobe within the breast has a distinct physiology. However, we also found that estradiol was more correlated in women who were nulliparous or produced nipple aspirate fluid. Conclusions Our results provide evidence that the microenvironment of any given lobular unit is unique to that individual unit, findings that may provide clues about the initiation and development of ductal carcinomas. PMID:27073976

  12. Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex

    SciTech Connect

    Xie, Jing; McClellan, Miranda; Sun, Rui; Kohale, Swapnil C.; Govind, Niranjan; Hase, William L.

    2015-02-05

    Direct dynamics simulations were used to study dissociation of the [CH3--I--OH]- complex ion, which was observed in a previous study of the OH- + CH3I gas phase reaction (J. Phys. Chem. A 2013, 117, 7162). Restricted B97-1 simulations were performed to study dissociation at 65, 75 and 100 kcal/mol and the [CH3--I--OH]- ion dissociated exponentially, in accord with RRKM theory. For these energies the major dissociation products are CH3I + OH-, CH2I- + H2O, and CH3OH + I-. Unrestricted B97-1 and restricted and unrestricted CAM-B3LYP simulations were also performed at 100 kcal/mol to compare with the restricted B97-1 results. The {CH3I + OH-}:{CH2I- + H2O}:{CH3OH + I-} product ratio is 0.72 : 0.15 : 0.13, 0.81 : 0.05 : 0.14, 0.71 : 0.19 : 0.10 , and 0.83 : 0.13 : 0.04 for the restricted B97-1, unrestricted B97-1, restricted CAM-B3LYP, and unrestricted CAM-B3LYP simulations, respectively. Other product channels found are CH2 + I- + H2O, CH2 + I-(H2O), CH4 + IO-, CH3 - + IOH, and CH3 + IOH-. The CH3 - + IOH singlet products are only given by the restricted B97-1 simulation and the lower energy CH3 + IOH- doublet products are only formed by the unrestricted B97-1 simulation. Also studied were the direct and indirect atomic-level mechanisms for forming CH3I + OH-, CH2I- + H2O, and CH3OH + I-. The majority of CH3I + OH- were formed through a direct mechanism. For both CH2I- + H2O and CH3OH + I-, the direct mechanism is overall more important than the indirect mechanisms, with the round-about like mechanism the most important indirect mechanism at high excitation energies. Mechanism comparisons between the B97-1 and CAM-B3LYP simulations showed that formation of the CH3OH---I- complex is favored for the B97-1 simulations, while formation of the HO----HCH2I complex is favored for the CAM-B3LYP simulations. The unrestricted simulations give a higher percentage of indirect mechanisms than the restricted simulations. The possible role of the self-interaction error in the

  13. Simulation of tracer dispersion from elevated and surface releases in complex terrain

    NASA Astrophysics Data System (ADS)

    Hernández, J. F.; Cremades, L.; Baldasano, J. M.

    A new version of an advanced mesoscale dispersion modeling system for simulating passive air pollutant dispersion in the real atmospheric planetary boundary layer (PBL), is presented. The system comprises a diagnostic mass-consistent meteorological model and a Lagrangian particle dispersion model (LADISMO). The former version of LADISMO, developed according to Zannetti (Air pollution modelling, 1990), was based on the Monte Carlo technique and included calculation of higher-order moments of vertical random forcing for convective conditions. Its ability to simulate complex flow dispersion has been stated in a previous paper (Hernández et al. 1995, Atmospheric Environment, 29A, 1331-1341). The new version follows Thomson's scheme (1984, Q. Jl Roy. Met. Soc.110, 1107-1120). It is also based on Langevin equation and follows the ideas given by Brusasca et al. (1992, Atmospheric Environment26A, 707-723) and Anfossi et al. (1992, Nuovo Cemento 15c, 139-158). The model is used to simulate the dispersion and predict the ground level concentration (g.l.c.) of a tracer (SF 6) released from both an elevated source ( case a) and a ground level source ( case b) in a highly complex mountainous terrain during neutral and synoptically dominated conditions ( case a) and light and apparently stable conditions ( case b). The last case is considered as being a specially difficult task to simulate. In fact, few works have reported situations with valley drainage flows in complex terrains and real stable atmospheric conditions with weak winds. The model assumes that nearly calm situations associated to strong stability and air stagnation, make the lowest layers of PBL poorly diffusive (Brusasca et al., 1992, Atmospheric Environment26A, 707-723). Model results are verified against experimental data from Guardo-90 tracer experiments, an intensive field campaign conducted in the Carrion river valley (Northern Spain) to study atmospheric diffusion within a steep walled valley in mountainous

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Mann, Harjeet S.; Singh, Pradeep K.

    2017-03-01

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

  16. Simulation in undergraduate paediatric nursing curriculum: Evaluation of a complex 'ward for a day' education program.

    PubMed

    Gamble, Andree S

    2017-03-01

    Simulation in health education has been shown to increase confidence, psychomotor and professional skills, and thus positively impact on student preparedness for clinical placement. It is recognised as a valuable tool to expose and engage students in realistic patient care encounters without the potential to cause patient harm. Although inherent challenges exist in the development and implementation of simulation, variability in clinical placement time, availability and quality dictates the need to provide students with learning opportunities they may otherwise not experience. With this, and a myriad of other issues providing the impetus for improved clinical preparation, 28 final semester undergraduate nursing students in a paediatric nursing course were involved in an extended multi-scenario simulated clinical shift prior to clinical placement. The simulation focussed on a complex ward experience, giving students the opportunity to demonstrate a variety of psychomotor skills, decision making, leadership, team work and other professional attributes integral for successful transition into the clinical arena. Evaluation data were collected at 3 intermittent points; post-simulation, post clinical placement, and 3 months after commencing employment as a Registered Nurse. Quantitative and qualitative analysis suggested positive impacts on critical nursing concepts and psychomotor skills resulted for participants in both clinical placement and beyond into the first months of employment.

  17. How to solve complex problems in foundry plants - future of casting simulation -

    NASA Astrophysics Data System (ADS)

    Ohnaka, I.

    2015-06-01

    Although the computer simulation of casting has progressed dramatically over the last decades, there are still many challenges and problems. This paper discusses how to solve complex engineering problems in foundry plants and what we should do in the future, in particular, for casting simulation. First, problem solving procedures including application of computer simulation are demonstrated and various difficulties are pointed-out exemplifying mainly porosity defects in sand castings of spheroidal graphite cast irons. Next, looking back conventional scientific and engineering research to understand casting phenomena, challenges and problems are discussed from problem solving view point, followed by discussion on the issues we should challenge such as how to integrate huge amount of dispersed knowledge in various disciplines, differentiation of science-oriented and engineering-oriented models, professional ethics, how to handle fluctuating materials, initial and boundary conditions, error accumulation, simulation codes as black-box, etc. Finally some suggestions are made on how to challenge the issues such as promotion of research on the simulation based on the science- oriented model and publication of reliable data of casting phenomena in complicated-shaped castings including reconsideration of the evaluation system.

  18. Simulation of metal-ligand self-assembly into spherical complex M6L8.

    PubMed

    Yoneya, Makoto; Yamaguchi, Tomohiko; Sato, Sota; Fujita, Makoto

    2012-09-05

    Molecular dynamics simulations were performed to study the self-assembly of a spherical complex through metal-ligand coordination interactions. M(6)L(8), a nanosphere with six palladium ions and eight pyridine-capped tridentate ligands, was selected as a target system. We successfully observed the spontaneous formation of spherical shaped M(6)L(8) cages over the course of our simulations, starting from random initial placement of the metals and ligands. To simulate spontaneous coordination bond formations and breaks, the cationic dummy atom method was employed to model nonbonded metal-ligand interactions. A coarse-grained solvent model was used to fill the gap between the time scale of the supramolecular self-assembly and that accessible by common molecular dynamics simulation. The simulated formation process occurred in the distinct three-stage (assembly, evolution, fixation) process that is well correlated with the experimental results. We found that the difference of the lifetime (or the ligand exchange rate) between the smaller-sized incomplete clusters and the completed M(6)L(8) nanospheres is crucially important in their supramolecular self-assembly.

  19. How much complexity is needed in global model organic aerosol simulations?

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Daskalakis, N.; Kanakidou, M.

    2014-12-01

    The skill in simulating the global atmospheric distribution and fate of organic aerosols (OA) of thirty-one global chemistry/transport and general circulation models of various complexities will be presented. Significant differences between models are identified in the magnitude of primary emissions, secondary OA (SOA) formation, the number of OA species used, the complexity of OA parameterizations (gas-particle partitioning, chemical aging, multiphase chemistry, aerosol microphysics), and the OA physical, chemical and optical properties. The diversity of the global OA simulation results has increased since earlier AeroCom experiments, mainly due to the increasing complexity of the SOA parameterization in models, and the implementation of new, highly uncertain, OA sources. Diversity of over an order of magnitude exists in the modeled vertical distribution of OA concentrations pointing to uncertainties in the parameterization of the semi-volatile character of OA and its temperature dependence, as well as OA long-range transport. Fine aerosol organic carbon (OC) and OA observations from continuous monitoring networks and individual field campaigns have been used for model evaluation. Τhe combined model/measurements analysis suggests the existence of increased OA levels during summer due to biogenic SOA formation over large areas of the USA that can be of the same order of magnitude as the POA, even at urban locations, and contribute to the observed urban seasonal pattern. The global models are able to simulate the high secondary character of OA observed in the atmosphere as a result of SOA formation and of POA aging, although, the amount of OA present in the atmosphere remains largely underestimated. The models skill with increasing model complexity with regard to OC or OA mass concentration will be presented and thoroughly discussed. This work is part of AeroCom phase II.

  20. Venting of gas explosion through relief ducts: interaction between internal and external explosions.

    PubMed

    Ferrara, G; Willacy, S K; Phylaktou, H N; Andrews, G E; Di Benedetto, A; Salzano, E; Russo, G

    2008-06-30

    Relief ducts fitted to venting openings is a widespread configuration in the industrial practice. The presence of a duct has been reported to severely increase the violence of the vented explosion posing a problem for the proper design of the venting device. Several studies have reported the leading importance--in the whole complex explosion phenomenology--of a secondary explosion in the duct. Modern approaches in the study of simply vented explosions (without ducts) have focused on the study of the interaction between internal and external explosion as a key issue in the mechanisms of pressure generation. The issue is even more relevant when a duct is fitted to the vent due the confined nature of the external explosion. In this work the interaction between internal and external events is experimentally investigated for gas explosions vented through a relief duct. The work has aimed at studying mechanisms underlying the pressure rise of this venting configuration. The study has put the emphasis on the mutual nature of the interaction. A larger scale than laboratory has been investigated allowing drawing results with a greater degree of generality with respect to data so far presented in literature.

  1. Sound propagation in and radiation from acoustically lined flow ducts: A comparison of experiment and theory

    NASA Technical Reports Server (NTRS)

    Plumblee, H. E., Jr.; Dean, P. D.; Wynne, G. A.; Burrin, R. H.

    1973-01-01

    The results of an experimental and theoretical study of many of the fundamental details of sound propagation in hard wall and soft wall annular flow ducts are reported. The theory of sound propagation along such ducts and the theory for determining the complex radiation impedance of higher order modes of an annulus are outlined, and methods for generating acoustic duct modes are developed. The results of a detailed measurement program on propagation in rigid wall annular ducts with and without airflow through the duct are presented. Techniques are described for measuring cut-on frequencies, modal phase speed, and radial and annular mode shapes. The effects of flow velocity on cut-on frequencies and phase speed are measured. Comparisons are made with theoretical predictions for all of the effects studies. The two microphone method of impedance is used to measure the effects of flow on acoustic liners. A numerical study of sound propagation in annular ducts with one or both walls acoustically lined is presented.

  2. Partial Müllerian Duct Retention in Smad4 Conditional Mutant Male Mice

    PubMed Central

    Petit, Fabrice G.; Deng, Chuxia; Jamin, Soazik P.

    2016-01-01

    Müllerian duct regression is a complex process which involves the AMH signalling pathway. We have previously demonstrated that besides AMH and its specific type II receptor (AMHRII), BMPR-IA and Smad5 are two essential factors implicated in this mechanism. Mothers against decapentaplegic homolog 4 (Smad4) is a transcription factor and the common Smad (co-Smad) involved in transforming growth factor beta (TGF-β) signalling pathway superfamily. Since Smad4 null mutants die early during gastrulation, we have inactivated Smad4 in the Müllerian duct mesenchyme. Specific inactivation of Smad4 in the urogenital ridge leads to the partial persistence of the Müllerian duct in adult male mice. Careful examination of the urogenital tract reveals that the Müllerian duct retention is randomly distributed either on one side or both sides. Histological analysis shows a uterus-like structure, which is confirmed by the expression of estrogen receptor α. As previously described in a β-catenin conditional mutant mouse model, β-catenin contributes to Müllerian duct regression. In our mutant male embryos, it appears that β-catenin expression is locally reduced along the urogenital ridge as compared to control mice. Moreover, the expression pattern is similar to those observed in control female mice. This study shows that reduced Smad4 expression disrupts the Wnt/β-catenin signalling leading to the partial persistence of Müllerian duct. PMID:27194944

  3. Nurse training with simulation: an innovative approach to teach complex microsurgery patient care.

    PubMed

    Flurry, Mitchell; Brooke, Sebastian; Micholetti, Brett; Natoli, Noel; Moyer, Kurtis; Mnich, Stephanie; Potochny, John

    2012-10-01

    Simulation has become an integral part of education at all levels within the medical field. The ability to allow personnel to practice and learn in a safe and controlled environment makes it a valuable tool for initial training and continued competence verification. An area of specific interest to the reconstructive microsurgeon is assurance that the nursing staff has adequate training and experience to provide optimum care for microsurgery patients. Plastic surgeons in institutions where few microsurgeries are performed face challenges teaching nurses how to care for these complex patients. Because no standard exists to educate microsurgery nurses, learning often happens by chance on-the-job encounters. Outcomes, therefore, may be affected by poor handoffs between inexperienced personnel. Our objective is to create a course that augments such random clinical experience and teaches the knowledge and skills necessary for successful microsurgery through simulated patient scenarios. Quality care reviews at our institution served as the foundation to develop an accredited nursing course providing clinical training for the care of microsurgery patients. The course combined lectures on microsurgery, pharmacology, and flap monitoring as well as simulated operating room, surgical intensive care unit, postanesthesia care unit, Trauma Bay, and Floor scenarios. Evaluation of participants included precourse examination, postcourse examination, and a 6-month follow-up. Average test scores were 72% precourse and 92% postcourse. Educational value, effectiveness of lectures and simulation, and overall course quality was rated very high or high by 86% of respondents; 0% respondents rated it as low. Six-month follow-up test score average was 88%. Learning to care for microsurgery patients should not be left to chance patient encounters on the job. Simulation provides a safe, reproducible, and controlled clinical experience. Our results show that simulation is a highly rated and

  4. Simulating the Complex Cell Design of Trypanosoma brucei and Its Motility

    PubMed Central

    Alizadehrad, Davod; Krüger, Timothy; Engstler, Markus; Stark, Holger

    2015-01-01

    The flagellate Trypanosoma brucei, which causes the sleeping sickness when infecting a mammalian host, goes through an intricate life cycle. It has a rather complex propulsion mechanism and swims in diverse microenvironments. These continuously exert selective pressure, to which the trypanosome adjusts with its architecture and behavior. As a result, the trypanosome assumes a diversity of complex morphotypes during its life cycle. However, although cell biology has detailed form and function of most of them, experimental data on the dynamic behavior and development of most morphotypes is lacking. Here we show that simulation science can predict intermediate cell designs by conducting specific and controlled modifications of an accurate, nature-inspired cell model, which we developed using information from live cell analyses. The cell models account for several important characteristics of the real trypanosomal morphotypes, such as the geometry and elastic properties of the cell body, and their swimming mechanism using an eukaryotic flagellum. We introduce an elastic network model for the cell body, including bending rigidity and simulate swimming in a fluid environment, using the mesoscale simulation technique called multi-particle collision dynamics. The in silico trypanosome of the bloodstream form displays the characteristic in vivo rotational and translational motility pattern that is crucial for survival and virulence in the vertebrate host. Moreover, our model accurately simulates the trypanosome's tumbling and backward motion. We show that the distinctive course of the attached flagellum around the cell body is one important aspect to produce the observed swimming behavior in a viscous fluid, and also required to reach the maximal swimming velocity. Changing details of the flagellar attachment generates less efficient swimmers. We also simulate different morphotypes that occur during the parasite's development in the tsetse fly, and predict a flagellar

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Transmission of wave energy in curved ducts

    NASA Technical Reports Server (NTRS)

    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.

  7. Silencing using flexible plate in a duct

    NASA Astrophysics Data System (ADS)

    Ramamoorthy, Sripriya; Grosh, Karl; Nawar, Tony G.

    2002-11-01

    A flexible plate interacting with air in a duct can provide passive means for low frequency broadband transmission loss. The sensitivity of the system to various parameters including unintentionally applied tension, effect of external fluid loading, lateral plate cross modes, structural and acoustic boundary condition are analyzed through experimental measurements and theoretical predictions. In order to avoid breakout noise, a backing cavity can be introduced below the plate. This introduces differences in filtering characteristics. Compared to plate in a single duct, the two-duct system will have higher plate resonance frequencies due to cavity loading on the plate. Means to achieve low frequency broadband transmission loss using two-duct silencers will be discussed. Significance of three dimensionality of the problem will be brought out by comparing the results of three-dimensional finite-element analysis with experimental data. Successful designs and experiments for low frequency attenuation will be presented. [Work supported by NSF and ONR.

  8. Treatment Option Overview (Extrahepatic Bile Duct Cancer)

    MedlinePlus

    ... bile ducts or has spread to the liver, lymph nodes , or other places in the body). Whether ... the body. Cancer can spread through tissue , the lymph system , and the blood : Tissue. The cancer spreads ...

  9. Stages of Extrahepatic Bile Duct Cancer

    MedlinePlus

    ... bile ducts or has spread to the liver, lymph nodes , or other places in the body). Whether ... the body. Cancer can spread through tissue , the lymph system , and the blood : Tissue. The cancer spreads ...

  10. General Information about Extrahepatic Bile Duct Cancer

    MedlinePlus

    ... bile ducts or has spread to the liver, lymph nodes , or other places in the body). Whether ... the body. Cancer can spread through tissue , the lymph system , and the blood : Tissue. The cancer spreads ...

  11. Treatment Options for Extrahepatic Bile Duct Cancer

    MedlinePlus

    ... bile ducts or has spread to the liver, lymph nodes , or other places in the body). Whether ... the body. Cancer can spread through tissue , the lymph system , and the blood : Tissue. The cancer spreads ...

  12. Rotating Rake Turbofan Duct Mode Measurement System

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.

    2005-01-01

    An experimental measurement system was developed and implemented by the NASA Glenn Research Center in the 1990s to measure turbofan duct acoustic modes. The system is a continuously rotating radial microphone rake that is inserted into the duct. This Rotating Rake provides a complete map of the acoustic duct modes present in a ducted fan and has been used on a variety of test articles: from a low-speed, concept test rig, to a full-scale production turbofan engine. The Rotating Rake has been critical in developing and evaluating a number of noise reduction concepts as well as providing experimental databases for verification of several aero-acoustic codes. More detailed derivation of the unique Rotating Rake equations are presented in the appendix.

  13. Unusually large sialolith of Wharton's duct

    PubMed Central

    Iqbal, Ali; Gupta, Anup K.; Natu, Subodh S.; Gupta, Atul K.

    2012-01-01

    The formation of calcific concretions in the salivary duct or glands is a common disorder, especially in the submandibular glands. Most of the salivary calculi are small in size, in contrast to those that reach several centimeters, which are reported as megaliths or giant calculi in the literature. They may occur in any of the salivary gland ducts but are most common in Wharton's duct and the submandibular gland. This report presents clinical and radiographical sign of an unusually large sialolith. There was painless swelling on the floor of the edentulous mouth and patient was unaware of it. Radiographical examination revealed large irregular radio-opaque mass superimposed on right canine and premolar areas. This case report describes a patient presenting with an unusually large submandibular gland duct sialolith, the subsequent patient management, the aetiology, diagnosis and its treatment. PMID:23483770

  14. Understanding Crew Decision-Making in the Presence of Complexity: A Flight Simulation Experiment

    NASA Technical Reports Server (NTRS)

    Young, Steven D.; Daniels, Taumi S.; Evans, Emory; deHaag, Maarten Uijt; Duan, Pengfei

    2013-01-01

    Crew decision making and response have long been leading causal and contributing factors associated with aircraft accidents. Further, it is anticipated that future aircraft and operational environments will increase exposure to risks related to these factors if proactive steps are not taken to account for ever-increasing complexity. A flight simulation study was designed to collect data to help in understanding how complexity can, or may, be manifest. More specifically, an experimental apparatus was constructed that allowed for manipulation of information complexity and uncertainty, while also manipulating operational complexity and uncertainty. Through these manipulations, and the aid of experienced airline pilots, several issues have been discovered, related most prominently to the influence of information content, quality, and management. Flight crews were immersed in an environment that included new operational complexities suggested for the future air transportation system as well as new technological complexities (e.g. electronic flight bags, expanded data link services, synthetic and enhanced vision systems, and interval management automation). In addition, a set of off-nominal situations were emulated. These included, for example, adverse weather conditions, traffic deviations, equipment failures, poor data quality, communication errors, and unexpected clearances, or changes to flight plans. Each situation was based on one or more reference events from past accidents or incidents, or on a similar case that had been used in previous developmental tests or studies. Over the course of the study, 10 twopilot airline crews participated, completing over 230 flights. Each flight consisted of an approach beginning at 10,000 ft. Based on the recorded data and pilot and research observations, preliminary results are presented regarding decision-making issues in the presence of the operational and technological complexities encountered during the flights.

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

    DOEpatents

    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.

  16. Investigation of the interfacial tension of complex coacervates using field-theoretic simulations

    SciTech Connect

    Kumar, Rajeev

    2012-01-01

    Complex coacervation, a liquid-liquid phase separation that occurs when two oppositely charged polyelectrolytes are mixed in a solution, has the potential to be exploited for many emerging applications including wet adhesives and drug delivery vehicles. The ultra-low interfacial tension of coacervate systems against water is critical for such applications, and it would be advantageous if molecular models could be used to characterize how various system properties (e.g., salt concentration) affect the interfacial tension. In this article we use field-theoretic simulations to characterize the interfacial tension between a complex coacervate and its supernatant. After demonstrating that our model is free of ultraviolet divergences (calculated properties converge as the collocation grid is refined), we develop two methods for calculating the interfacial tension from field-theoretic simulations. One method relies on the mechanical interpretation of the interfacial tension as the interfacial pressure, and the second method estimates the change in free energy as the area between the two phases is changed. These are the first calculations of the interfacial tension from full field theoretic simulation of which we are aware, and both the magnitude and scaling behaviors of our calculated interfacial tension agree with recent experiments.

  17. Godunov method for multiprobe cryosurgery simulation with complex-shaped tumors

    NASA Astrophysics Data System (ADS)

    Tarwidi, D.

    2016-02-01

    Cryosurgery is a technique to eradicate abnormal biological tissues by freezing. The objective of cryosurgery is to maximize cryoinjury of tumor tissues while at the same time minimizing cryoinjury to the surrounding healthy tissues. The location and number of cryoprobes are important factors to obtain optimal cryosurgery in complex-shaped tumors. This paper presents multiprobe cryosurgery simulation with optimal cryoprobes location in target region. Bubble packing method is used to obtain optimal cryoprobes layout. We consider mathematical model of freezing by bioheat transfer equation in solid (frozen tissue), liquid (unfrozen tissue), and mushy region. This model is referred to as Stefan problem where the location of moving solid-mushy or mushy-liquid interface is not known and it is as part of the solution. We reformulate the bioheat equations into single enthalpy (energy) equation which can resolve the moving boundary between two phases. The first-order of Godunov method is adopted to obtain numerical solution of the phase change problem. This method is easily applied since we only solve one governing equation regardless the moving interface between two phases. For demonstration purposes, multiprobe cryosurgery for lung cancer case with complex geometry is simulated and interpreted. The numerical simulation for three to ten cryoprobes configuration shows that the nine cryoprobes layout has the smallest total defect in this case. The numerical results provide an important information for cryosurgeon before conducting effective cryosurgery protocol.

  18. INTERIOR DUCT SYSTEM DESIGN, CONSTRUCTION, AND PERFORMANCE

    SciTech Connect

    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

  19. In Defense of Simulating Complex and Tragic Historical Episodes: A Measured Response to the Outcry over a New England Slavery Simulation

    ERIC Educational Resources Information Center

    Wright-Maley, Cory

    2014-01-01

    A slavery simulation that took place as part of a field trip for students of a Hartford junior high academy led a father to file a human rights suit against the school district, and for one official to comment that simulations of complex and tragic human phenomena have "no place in an educational system." In light of these conclusions,…

  20. All-atom molecular dynamics simulation of a photosystem i/detergent complex.

    PubMed

    Harris, Bradley J; Cheng, Xiaolin; Frymier, Paul

    2014-10-09

    All-atom molecular dynamics (MD) simulation was used to investigate the solution structure and dynamics of the photosynthetic pigment-protein complex photosystem I (PSI) from Thermosynechococcus elongatus embedded in a toroidal belt of n-dodecyl-β-d-maltoside (DDM) detergent. Evaluation of root-mean-square deviations (RMSDs) relative to the known crystal structure show that the protein complex surrounded by DDM molecules is stable during the 200 ns simulation time, and root-mean-square fluctuation (RMSF) analysis indicates that regions of high local mobility correspond to solvent-exposed regions such as turns in the transmembrane α-helices and flexible loops on the stromal and lumenal faces. Comparing the protein-detergent complex to a pure detergent micelle, the detergent surrounding the PSI trimer is found to be less densely packed but with more ordered detergent tails, contrary to what is seen in most lipid bilayer models. We also investigated any functional implications for the observed conformational dynamics and protein-detergent interactions, discovering interesting structural changes in the psaL subunits associated with maintaining the trimeric structure of the protein. Importantly, we find that the docking of soluble electron mediators such as cytochrome c6 and ferredoxin to PSI is not significantly impacted by the solubilization of PSI in detergent.

  1. Dynamic Simulation of VEGA SRM Bench Firing By Using Propellant Complex Characterization

    NASA Astrophysics Data System (ADS)

    Di Trapani, C. D.; Mastrella, E.; Bartoccini, D.; Squeo, E. A.; Mastroddi, F.; Coppotelli, G.; Linari, M.

    2012-07-01

    During the VEGA launcher development, from the 2004 up to now, 8 firing tests have been performed at Salto di Quirra (Sardinia, Italy) and Kourou (Guyana, Fr) with the objective to characterize and qualify of the Zefiros and P80 Solid Rocket Motors (SRM). In fact the VEGA launcher configuration foreseen 3 solid stages based on P80, Z23 and Z9 Solid Rocket Motors respectively. One of the primary objectives of the firing test is to correctly characterize the dynamic response of the SRM in order to apply such a characterization to the predictions and simulations of the VEGA launch dynamic environment. Considering that the solid propellant is around 90% of the SRM mass, it is very important to dynamically characterize it, and to increase the confidence in the simulation of the dynamic levels transmitted to the LV upper part from the SRMs. The activity is articulated in three parts: • consolidation of an experimental method for the dynamic characterization of the complex dynamic elasticity modulus of elasticity of visco-elastic materials applicable to the SRM propellant operative conditions • introduction of the complex dynamic elasticity modulus in a numerical FEM benchmark based on MSC NASTRAN solver • analysis of the effect of the introduction of the complex dynamic elasticity modulus in the Zefiros FEM focusing on experimental firing test data reproduction with numerical approach.

  2. Simulation of the mobility of metal - EDTA complexes in groundwater: The influence of contaminant metals

    USGS Publications Warehouse

    Friedly, J.C.; Kent, D.B.; Davis, J.A.

    2002-01-01

    Reactive transport simulations were conducted to model chemical reactions between metal - EDTA (ethylenediaminetetraacetic acid) complexes during transport in a mildly acidic quartz - sand aquifer. Simulations were compared with the results of small-scale tracer tests wherein nickel-, zinc-, and calcium - EDTA complexes and free EDTA were injected into three distinct chemical zones of a plume of sewage-contaminated groundwater. One zone had a large mass of adsorbed, sewage-derived zinc; one zone had a large mass of adsorbed manganese resulting from mildly reducing conditions created bythe sewage plume; and one zone had significantly less adsorbed manganese and negligible zinc background. The chemical model assumed that the dissolution of iron(III) from metal - hydroxypolymer coatings on the aquifer sediments by the metal - EDTA complexes was kinetically restricted. All other reactions, including metal - EDTA complexation, zinc and manganese adsorption, and aluminum hydroxide dissolution were assumed to reach equilibrium on the time scale of transport; equilibrium constants were either taken from the literature or determined independently in the laboratory. A single iron(III) dissolution rate constant was used to fit the breakthrough curves observed in the zone with negligible zinc background. Simulation results agreed well with the experimental data in all three zones, which included temporal moments derived from breakthrough curves at different distances downgradient from the injections and spatial moments calculated from synoptic samplings conducted at different times. Results show that the tracer cloud was near equilibrium with respect to Fe in the sediment after 11 m of transport in the Zn-contaminated region but remained far from equilibrium in the other two zones. Sensitivity studies showed that the relative rate of iron(III) dissolution by the different metal - EDTA complexes was less important than the fact that these reactions are rate controlled. Results

  3. Simulation of the mobility of metal-EDTA complexes in groundwater: the influence of contaminant metals.

    PubMed

    Friedly, J C; Kent, D B; Davis, J A

    2002-02-01

    Reactive transport simulations were conducted to model chemical reactions between metal-EDTA (ethylenediaminetetraacetic acid) complexes during transport in a mildly acidic quartz-sand aquifer. Simulations were compared with the results of small-scale tracer tests wherein nickel-, zinc-, and calcium-EDTA complexes and free EDTA were injected into three distinct chemical zones of a plume of sewage-contaminated groundwater. One zone had a large mass of adsorbed, sewage-derived zinc; one zone had a large mass of adsorbed manganese resulting from mildly reducing conditions created by the sewage plume; and one zone had significantly less adsorbed manganese and negligible zinc background. The chemical model assumed that the dissolution of iron(III) from metal-hydroxypolymer coatings on the aquifer sediments by the metal-EDTA complexes was kinetically restricted. All other reactions, including metal-EDTA complexation, zinc and manganese adsorption, and aluminum hydroxide dissolution were assumed to reach equilibrium on the time scale of transport; equilibrium constants were either taken from the literature or determined independently in the laboratory. A single iron(III) dissolution rate constant was used to fit the breakthrough curves observed in the zone with negligible zinc background. Simulation results agreed well with the experimental data in all three zones, which included temporal moments derived from breakthrough curves at different distances downgradient from the injections and spatial moments calculated from synoptic samplings conducted at different times. Results show that the tracer cloud was near equilibrium with respect to Fe in the sediment after 11 m of transport in the Zn-contaminated region but remained far from equilibrium in the other two zones. Sensitivity studies showed that the relative rate of iron(III) dissolution by the different metal-EDTA complexes was less important than the fact that these reactions are rate controlled. Results suggest that

  4. Duct Liner Optimization for Turbomachinery Noise Sources

    DTIC Science & Technology

    1975-11-01

    AD-A279 441lIIIflhIh* NASA TECHNICAL NASA TMA X-72789 MEMORANDUM oo £ 00 r-:. DUCT LINER OPTIMIZATION FOR TURBOMACHINERY w NOISE SOURCES By Harold C...Recipient’s r.atalog No. NASA TM X-72789! 4 Title diid Subtitle 5. Rewrt Date Duct Liner Optimization for Turbomachinery Noise Sources November 1975...profiles is combined wit., a numerical minimization algorithm to predict optimal liner configurations having one, two, and three sections. Source models

  5. Energy Conservation Through Duct Leakage Reduction

    DTIC Science & Technology

    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

  6. Effect of shear on duct wall impedance.

    NASA Technical Reports Server (NTRS)

    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.

  7. Sound radiation from a flanged inclined duct.

    PubMed

    McAlpine, Alan; Daymond-King, Alex P; Kempton, Andrew J

    2012-12-01

    A simple method to calculate sound radiation from a flanged inclined duct is presented. An inclined annular duct is terminated by a rigid vertical plane. The duct termination is representative of a scarfed exit. The concept of a scarfed duct has been examined in turbofan aero-engines as a means to, potentially, shield a portion of the radiated sound from being transmitted directly to the ground. The sound field inside the annular duct is expressed in terms of spinning modes. Exterior to the duct, the radiated sound field owing to each mode can be expressed in terms of its directivity pattern, which is found by evaluating an appropriate form of Rayleigh's integral. The asymmetry is shown to affect the amplitude of the principal lobe of the directivity pattern, and to alter the proportion of the sound power radiated up or down. The methodology detailed in this article provides a simple engineering approach to investigate the sound radiation for a three-dimensional problem.

  8. World, We Have Problems: Simulation for Large Complex, Risky Projects, and Events

    NASA Technical Reports Server (NTRS)

    Elfrey, Priscilla

    2010-01-01

    Prior to a spacewalk during the NASA STS/129 mission in November 2009, Columbia Broadcasting System (CBS) correspondent William Harwood reported astronauts, "were awakened again", as they had been the day previously. Fearing something not properly connected was causing a leak, the crew, both on the ground and in space, stopped and checked everything. The alarm proved false. The crew did complete its work ahead of schedule, but the incident reminds us that correctly connecting hundreds and thousands of entities, subsystems and systems, finding leaks, loosening stuck valves, and adding replacements to very large complex systems over time does not occur magically. Everywhere major projects present similar pressures. Lives are at - risk. Responsibility is heavy. Large natural and human-created disasters introduce parallel difficulties as people work across boundaries their countries, disciplines, languages, and cultures with known immediate dangers as well as the unexpected. NASA has long accepted that when humans have to go where humans cannot go that simulation is the sole solution. The Agency uses simulation to achieve consensus, reduce ambiguity and uncertainty, understand problems, make decisions, support design, do planning and troubleshooting, as well as for operations, training, testing, and evaluation. Simulation is at the heart of all such complex systems, products, projects, programs, and events. Difficult, hazardous short and, especially, long-term activities have a persistent need for simulation from the first insight into a possibly workable idea or answer until the final report perhaps beyond our lifetime is put in the archive. With simulation we create a common mental model, try-out breakdowns of machinery or teamwork, and find opportunity for improvement. Lifecycle simulation proves to be increasingly important as risks and consequences intensify. Across the world, disasters are increasing. We anticipate more of them, as the results of global warming

  9. Automating Embedded Analysis Capabilities and Managing Software Complexity in Multiphysics Simulation, Part I: Template-Based Generic Programming

    SciTech Connect

    Pawlowski, Roger P.; Phipps, Eric T.; Salinger, Andrew G.

    2012-01-01

    An approach for incorporating embedded simulation and analysis capabilities in complex simulation codes through template-based generic programming is presented. This approach relies on templating and operator overloading within the C++ language to transform a given calculation into one that can compute a variety of additional quantities that are necessary for many state-of-the-art simulation and analysis algorithms. An approach for incorporating these ideas into complex simulation codes through general graph-based assembly is also presented. These ideas have been implemented within a set of packages in the Trilinos framework and are demonstrated on a simple problem from chemical engineering.

  10. Automating Embedded Analysis Capabilities and Managing Software Complexity in Multiphysics Simulation, Part I: Template-Based Generic Programming

    DOE PAGES

    Pawlowski, Roger P.; Phipps, Eric T.; Salinger, Andrew G.

    2012-01-01

    An approach for incorporating embedded simulation and analysis capabilities in complex simulation codes through template-based generic programming is presented. This approach relies on templating and operator overloading within the C++ language to transform a given calculation into one that can compute a variety of additional quantities that are necessary for many state-of-the-art simulation and analysis algorithms. An approach for incorporating these ideas into complex simulation codes through general graph-based assembly is also presented. These ideas have been implemented within a set of packages in the Trilinos framework and are demonstrated on a simple problem from chemical engineering.

  11. Surface complexation of heavy metal cations on clay edges: insights from first principles molecular dynamics simulation of Ni(II)

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Liu, Xiandong; Lu, Xiancai; He, Mengjia; Jan Meijer, Evert; Wang, Rucheng

    2017-04-01

    Aiming at an atomistic mechanism of heavy metal cation complexing on clay surfaces, we carried out systematic first principles molecular dynamics (FPMD) simulations to investigate the structures, free energies and acidity constants of Ni(II) complexes formed on edge surfaces of 2:1 phyllosilicates. Three representative complexes were studied, including monodentate complex on the tbnd SiO site, bidentate complex on the tbnd Al(OH)2 site, and tetradentate complex on the octahedral vacancy where Ni(II) fits well into the lattice. The complexes structures were characterized in detail. Computed free energy values indicate that the tetradentate complex is significantly more stable than the other two. The calculated acidity constants indicate that the tetradentate complex can get deprotonated (pKa = 8.4) at the ambient conditions whereas the other two hardly deprotonate due to extremely high pKa values. By comparing with the 2 Site Protolysis Non Electrostatic Surface Complexation and Cation Exchange (2SPNE SC/CE) model, the vacant site has been assigned to the strong site and the other two to the weak site, respectively. Thus a link has been built between atomistic simulations and macroscopic experiments and it is deduced that this should also apply to other heavy metal cations based on additional simulations of Co(II) and Cu(II) and previous simulations of Fe(II) and Cd(II)). This study forms a physical basis for understanding the transport and fixation of heavy metal elements in many geologic environments.

  12. Information-Theoretic Approaches for Evaluating Complex Adaptive Social Simulation Systems

    SciTech Connect

    Omitaomu, Olufemi A; Ganguly, Auroop R; Jiao, Yu

    2009-01-01

    In this paper, we propose information-theoretic approaches for comparing and evaluating complex agent-based models. In information theoretic terms, entropy and mutual information are two measures of system complexity. We used entropy as a measure of the regularity of the number of agents in a social class; and mutual information as a measure of information shared by two social classes. Using our approaches, we compared two analogous agent-based (AB) models developed for regional-scale social-simulation system. The first AB model, called ABM-1, is a complex AB built with 10,000 agents on a desktop environment and used aggregate data; the second AB model, ABM-2, was built with 31 million agents on a highperformance computing framework located at Oak Ridge National Laboratory, and fine-resolution data from the LandScan Global Population Database. The initializations were slightly different, with ABM-1 using samples from a probability distribution and ABM-2 using polling data from Gallop for a deterministic initialization. The geographical and temporal domain was present-day Afghanistan, and the end result was the number of agents with one of three behavioral modes (proinsurgent, neutral, and pro-government) corresponding to the population mindshare. The theories embedded in each model were identical, and the test simulations focused on a test of three leadership theories - legitimacy, coercion, and representative, and two social mobilization theories - social influence and repression. The theories are tied together using the Cobb-Douglas utility function. Based on our results, the hypothesis that performance measures can be developed to compare and contrast AB models appears to be supported. Furthermore, we observed significant bias in the two models. Even so, further tests and investigations are required not only with a wider class of theories and AB models, but also with additional observed or simulated data and more comprehensive performance measures.

  13. Emergence of hydrogen bonds from molecular dynamics simulation of substituted N-phenylthiourea-catechol oxidase complex.

    PubMed

    Park, Kyung-Lae

    2017-01-01

    A series of N-phenylthiourea derivatives was built starting from the X-ray structure in the molecular mechanics framework and the interaction profile in the complex with the catechol oxidase was traced using molecular dynamics simulation. The results showed that the geometry and interactions between ligand and receptor were highly related to the position of the substituted side chains of phenyl moiety. At the end of molecular dynamics run, a concentrated multicenter hydrogen bond was created between the substituted ligand and receptor. The conformation of the ligand itself were also restricted in the receptor pocket. Furthermore, the simulation time of 50 ns were found to be long enough to explore the relevant conformational space and the stationary behavior of the molecular dynamic could be observed.

  14. Beneficiation of Stillwater Complex Rock for the Production of Lunar Simulants

    NASA Technical Reports Server (NTRS)

    Rickman, D. L.; Young, C.; Stoeser, D.; Edmunson, J.

    2014-01-01

    The availability of pure, high calcium plagioclase would be a significant asset in any attempt to manufacture high-quality lunar simulants. A suitable plagioclase product can be obtained from materials obtained from the Stillwater Complex of Montana. The access, geology, petrology, and mineralogy of the relevant rocks and the mill tailings are described here. This study demonstrates successful plagioclase recovery from mill tailings produced by the Stillwater Mine Company. Hydrogen peroxide was used to remove carboxymethyl cellulose from the tailing. The characteristics of the plagioclase products are shown and locked grains are identified as a limit to achievable purity. Based on the experimental results, flowsheets were developed showing how these resources could be processed and made into 'separates' of (1) high calcium plagioclase and (2) orthopyroxene/clinopyroxene with the thought that they would be combined later to make simulant.

  15. Comparison of Different Measurement Techniques and a CFD Simulation in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Schulz, Christoph; Hofsäß, Martin; Anger, Jan; Rautenberg, Alexander; Lutz, Thorsten; Cheng, Po Wen; Bange, Jens

    2016-09-01

    This paper deals with a comparison of data collected by measurements and a simulation for a complex terrain test site in southern Germany. Lidar, met mast, unmanned aerial vehicle (UAV) measurements of wind speed and direction and Computational Fluid Dynamics (CFD) data are compared to each other. The site is characterised regarding its flow features and the suitability for a wind turbine test field. A Delayed-Detached-Eddy- Simulation (DES) was employed using measurement data to generate generic turbulent inflow. A good agreement of the wind profiles between the different approaches was reached. The terrain slope leads to a speed-up, a change of turbulence intensity as well as to flow angle variations.

  16. Advanced Methodology for Simulation of Complex Flows Using Structured Grid Systems

    NASA Technical Reports Server (NTRS)

    Steinthorsson, Erlendur; Modiano, David

    1995-01-01

    Detailed simulations of viscous flows in complicated geometries pose a significant challenge to current capabilities of Computational Fluid Dynamics (CFD). To enable routine application of CFD to this class of problems, advanced methodologies are required that employ (a) automated grid generation, (b) adaptivity, (c) accurate discretizations and efficient solvers, and (d) advanced software techniques. Each of these ingredients contributes to increased accuracy, efficiency (in terms of human effort and computer time), and/or reliability of CFD software. In the long run, methodologies employing structured grid systems will remain a viable choice for routine simulation of flows in complex geometries only if genuinely automatic grid generation techniques for structured grids can be developed and if adaptivity is employed more routinely. More research in both these areas is urgently needed.

  17. Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes

    NASA Astrophysics Data System (ADS)

    Mostame, Sarah; Rebentrost, Patrick; Eisfeld, Alexander; Kerman, Andrew J.; Tsomokos, Dimitris I.; Aspuru-Guzik, Alan

    2012-02-01

    In the initial stage of photosynthesis, light-harvested energy is transferred with remarkably high efficiency to a reaction center, with the vibrational environment assisting the transport mechanism. It is of great interest to mimic this process with present-day technologies. Here we propose an analog quantum simulator of open system dynamics, where noise engineering of the environment has a central role. In particular, we propose the use of superconducting qubits for the simulation of exciton transport in the Fenna-Matthew-Olson protein, a prototypical photosynthetic complex. Our method allows for a single-molecule implementation and the investigation of energy transfer pathways as well as non-Markovian and spatiotemporal noise-correlation effects.

  18. Dynamic three-dimensional simulations of densely-packed fluid loaded cloth in a complex geometry

    NASA Astrophysics Data System (ADS)

    Akcabay, Deniz T.; Schultz, William W.; Dowling, David R.

    2006-11-01

    This talk presents three-dimensional simulations of the fluid-structure interaction that occurs inside the washtub of a modern clothes washing machine. The results are based on the numerical solution of the incompressible Navier-Stokes equations on a Cartesian grid using Peskin's Immersed Boundary Method for the cloth-fluid coupling, and a weighted domain-mapping method to represent the complicated moving boundaries of the agitator and washtub. Cloth pieces are modeled as impermeable flexible isotropic elastic plates. Results from simple benchmarking studies with theoretical and experimental results for the individual cloth and complex geometry models are presented. A variety of simulation studies involving complicated mixing patterns that result from mechanical excitation from a realistic agitator are shown and analyzed. The effects of cloth size, bending stiffness, and load density on the resulting motion of individual pieces of cloth and on the bulk flow within the machine are analyzed. [Sponsored by Whirlpool Corporation

  19. Lattice-Boltzmann Simulation of Tablet Dissolution in Complex Hydrodynamic Environment

    NASA Astrophysics Data System (ADS)

    Jiang, Jiaolong; Sun, Ning; Park, Taeshin; Ko, Glen H.; Gersappe, Dilip

    2015-03-01

    Using the Lattice-Boltzmann method, we developed a 3D model to study the tablet dissolution process in a complex hydrodynamic environment involving spatially varying velocity and shear forces. The results show that a turbulent flow is formed in the region above the tablet, which has been obtained by visualization experiments. The dissolution profiles were obtained by incorporating detailed kinetics, showing good agreement with case studies from literature. After studying the influence of the paddle speed and the size of the system, we simulated the dissolution process for multicomponent tablets. Our results indicate how the hydrodynamic environment would affect the dissolution process by changing the local concentration of components near the tablet as well as by the particle erosion under high fluid velocity. Since the code was successfully parallelized, the simulation for comparatively large systems is possible now.

  20. Stress influences decisions to break a safety rule in a complex simulation task in females.

    PubMed

    Starcke, Katrin; Brand, Matthias; Kluge, Annette

    2016-07-01

    The current study examines the effects of acutely induced laboratory stress on a complex decision-making task, the Waste Water Treatment Simulation. Participants are instructed to follow a certain decision rule according to safety guidelines. Violations of this rule are associated with potential high rewards (working faster and earning more money) but also with the risk of a catastrophe (an explosion). Stress was induced with the Trier Social Stress Test while control participants underwent a non-stress condition. In the simulation task, stressed females broke the safety rule more often than unstressed females: χ(2) (1, N=24)=10.36, p<0.001, V=0.66. In males, no difference between stressed and unstressed participants was observed. We conclude that stress increased the decisions to break the safety rule because stressed female participants focused on the potential high gains while they neglected the risk of potential negative consequences.

  1. Numerical simulations of Rayleigh-Taylor (RT) turbulence with complex acceleration history

    NASA Astrophysics Data System (ADS)

    Ramaprabhu, Praveen; Dimonte, Guy; Andrews, Malcolm

    2007-11-01

    Complex acceleration histories of an RT unstable interface are important in validating turbulent mix models. Of particular interest are alternating stages of acceleration and deceleration, since the the associated demixing is a discriminating test of such models. We have performed numerical simulations of a turbulent RT mixing layer subjected to two stages of acceleration separated by a stage of deceleration. The profile was chosen from earlier Linear Electric Motor experiments with which we compare our results. The acceleration phases produce classical RT unstable growth (t^2) with growth rates comparable to earlier results of turbulent RT simulations. The calculations are challenging as dominant bubbles become shredded as they reverse direction in response to the reversal in g, placing increased demands on numerical resolution. The shredding to small scales is accompanied by a peaking of the molecular mixing during the RT stable stage. In general, we find that simulations agree with experiments when initialized with broadband initial perturbations, but not for an annular shell. Other effects such as the presence of surface tension in the LEM experiments (but not in our simulations) further complicate this picture.

  2. Noise control zone for a periodic ducted Helmholtz resonator system.

    PubMed

    Cai, Chenzhi; Mak, Cheuk Ming

    2016-12-01

    This paper presents a theoretical study of the dispersion characteristics of sound wave propagation in a periodic ducted Helmholtz resonator (HR) system. The predicted result fits well with a numerical simulation using a finite element method. This study indicates that for the same system, no matter how many HRs are connected or what the periodic distance is, the area under average transmission loss T L¯ curves is always the same. The broader the noise attenuation band, the lower the peak attenuation amplitude. A noise control zone compromising the attenuation bandwidth or peak amplitude is proposed for noise control optimization.

  3. Applications of a simulation model to description of anaerobic conversion of complex organic matter into methane

    SciTech Connect

    Vavilin, V.A.; Rytow, S.V.; Lokshina, L.Ya.

    1996-12-31

    Three years passed since the generalized model of anaerobic degradation of complex organic matter has been developed. Now the new modifications were created. Anaerobic degradation was described as a multistep process of series and parallel reactions in which several groups of bacteria take part. Hydrolysis, acidogenesis, acetogenesis and methanogenesis were considered in the model with the various kinetic functions. A two-phase equation describing a particulate substrate degradation as a heterogeneous reaction has been developed. Acetic, butyric, and propionic groups of acidogenic bacteria producing the particular products were considered. The additional group of homoacetogenic bacteria producing acetate from hydrogen and carbon dioxide was involved into new version of the model. Ammonia and hydrogen sulfide inhibition were described previously. In that paper, it was shown by simulation of several case-studies that unionized volatile fatty acids (VFA) are the inhibitors of key stages of anaerobic conversion of complex organic matter: hydrolysis, acetogenesis and methanogenesis.

  4. Modeling and Simulation of Complex Network Attributes on Coordinating Large Multiagent System

    PubMed Central

    Li, Xiang; Liu, Ming

    2014-01-01

    With the expansion of distributed multiagent systems, traditional coordination strategy becomes a severe bottleneck when the system scales up to hundreds of agents. The key challenge is that in typical large multiagent systems, sparsely distributed agents can only communicate directly with very few others and the network is typically modeled as an adaptive complex network. In this paper, we present simulation testbed CoordSim built to model the coordination of network centric multiagent systems. Based on the token-based strategy, the coordination can be built as a communication decision problem that agents make decisions to target communications and pass them over to the capable agents who will potentially benefit the team most. We have theoretically analyzed that the characters of complex network make a significant difference with both random and intelligent coordination strategies, which may contribute to future multiagent algorithm design. PMID:24955399

  5. Soot prediction by Large-Eddy Simulation of complex geometry combustion chambers

    NASA Astrophysics Data System (ADS)

    Lecocq, Guillaume; Hernández, Ignacio; Poitou, Damien; Riber, Eléonore; Cuenot, Bénédicte

    2013-01-01

    This article is dedicated to the modeling of soot production in Large-Eddy Simulations (LES) of complex geometries. Such computations impose a trade-off between accuracy and CPU cost which limits the choice of soot models to semi-empirical ones. As the presence of acetylene is a necessary condition for soot inception, the Leung et al. model that accounts for this feature is chosen and used in this work. However, acetylene concentration is not provided by the reduced chemistries used in LES of complex geometries and a methodology has been developed to predict this key species through a tabulation technique. With this methodology, the model of Leung et al. is first tested and validated against measured laminar premixed flames. Then, the soot prediction method is applied to the LES of the combustion chamber of a helicopter engine.

  6. Implementation of numerical simulation techniques in analysis of the accidents in complex technological systems

    SciTech Connect

    Klishin, G.S.; Seleznev, V.E.; Aleoshin, V.V.

    1997-12-31

    Gas industry enterprises such as main pipelines, compressor gas transfer stations, gas extracting complexes belong to the energy intensive industry. Accidents there can result into the catastrophes and great social, environmental and economic losses. Annually, according to the official data several dozens of large accidents take place at the pipes in the USA and Russia. That is why prevention of the accidents, analysis of the mechanisms of their development and prediction of their possible consequences are acute and important tasks nowadays. The accidents reasons are usually of a complicated character and can be presented as a complex combination of natural, technical and human factors. Mathematical and computer simulations are safe, rather effective and comparatively inexpensive methods of the accident analysis. It makes it possible to analyze different mechanisms of a failure occurrence and development, to assess its consequences and give recommendations to prevent it. Besides investigation of the failure cases, numerical simulation techniques play an important role in the treatment of the diagnostics results of the objects and in further construction of mathematical prognostic simulations of the object behavior in the period of time between two inspections. While solving diagnostics tasks and in the analysis of the failure cases, the techniques of theoretical mechanics, of qualitative theory of different equations, of mechanics of a continuous medium, of chemical macro-kinetics and optimizing techniques are implemented in the Conversion Design Bureau {number_sign}5 (DB{number_sign}5). Both universal and special numerical techniques and software (SW) are being developed in DB{number_sign}5 for solution of such tasks. Almost all of them are calibrated on the calculations of the simulated and full-scale experiments performed at the VNIIEF and MINATOM testing sites. It is worth noting that in the long years of work there has been established a fruitful and effective

  7. Replica exchange Monte Carlo simulation of human serum albumin-catechin complexes.

    PubMed

    Li, Yunqi; An, Lijia; Huang, Qingrong

    2014-09-04

    Replica exchange Monte Carlo simulation equipped with an orientation-enhanced hydrophobic interaction was utilized to study the impacts of molar ratio and ionic strength on the complex formation of human serum albumin (HSA) and catechin. Only a small amount of catechins was found to act as bridges in the formation of HSA-catechin complexes. Selective binding behavior was observed at low catechin to HSA molar ratio (R). Increase of catechin amount can suppress HSA self-aggregation and diminish the selectivity of protein binding sites. Strong saturation binding with short-range interactions was found to level off at around 4.6 catechins per HSA on average, while this number slowly increased with R when long-range interactions were taken into account. Meanwhile, among the three rings of catechin, the 3,4-dihydroxyphenyl (B-ring) shows the strongest preference to bind HSA. Neither the aggregation nor the binding sites of the HSA-catechin complex was sensitive to ionic strength, suggesting that the electrostatic interaction is not a dominant force in such complexes. These results provide a further molecular level understanding of protein-polyphenol binding, and the strategy employed in this work shows a way to bridge phase behaviors at macroscale and the distribution of binding sites at residue level.

  8. Free energy landscape of the Michaelis complex of lactate dehydrogenase: A network analysis of atomistic simulations

    NASA Astrophysics Data System (ADS)

    Pan, Xiaoliang; Schwartz, Steven

    2015-03-01

    It has long been recognized that the structure of a protein is a hierarchy of conformations interconverting on multiple time scales. However, the conformational heterogeneity is rarely considered in the context of enzymatic catalysis in which the reactant is usually represented by a single conformation of the enzyme/substrate complex. Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate with concomitant interconversion of two forms of the cofactor nicotinamide adenine dinucleotide (NADH and NAD+). Recent experimental results suggest that multiple substates exist within the Michaelis complex of LDH, and they are catalytic competent at different reaction rates. In this study, millisecond-scale all-atom molecular dynamics simulations were performed on LDH to explore the free energy landscape of the Michaelis complex, and network analysis was used to characterize the distribution of the conformations. Our results provide a detailed view of the kinetic network the Michaelis complex and the structures of the substates at atomistic scale. It also shed some light on understanding the complete picture of the catalytic mechanism of LDH.

  9. Computational Fluid Dynamics Analysis of Flexible Duct Junction Box Design

    SciTech Connect

    Beach, R.; Prahl, D.; Lange, R.

    2013-12-01

    IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics (CFD) simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance. Current Air Conditioning Contractors of America (ACCA) guidance (Group 11, Appendix 3, ACCA Manual D, Rutkowski 2009) allows for unconstrained variation in the number of takeoffs, box sizes, and takeoff locations. The only variables currently used in selecting an equivalent length (EL) are velocity of air in the duct and friction rate, given the first takeoff is located at least twice its diameter away from the inlet. This condition does not account for other factors impacting pressure loss across these types of fittings. For each simulation, the IBACOS team converted pressure loss within a box to an EL to compare variation in ACCA Manual D guidance to the simulated variation. IBACOS chose cases to represent flows reasonably correlating to flows typically encountered in the field and analyzed differences in total pressure due to increases in number and location of takeoffs, box dimensions, and velocity of air, and whether an entrance fitting is included. The team also calculated additional balancing losses for all cases due to discrepancies between intended outlet flows and natural flow splits created by the fitting. In certain asymmetrical cases, the balancing losses were significantly higher than symmetrical cases where the natural splits were close to the targets. Thus, IBACOS has shown additional design constraints that can ensure better system performance.

  10. Theoretical Simulations and Ultrafast Pump-probe Spectroscopy Experiments in Pigment-protein Photosynthetic Complexes

    SciTech Connect

    Buck, D. R.

    2000-09-12

    Theoretical simulations and ultrafast pump-probe laser spectroscopy experiments were used to study photosynthetic pigment-protein complexes and antennae found in green sulfur bacteria such as Prosthecochloris aestuarii, Chloroflexus aurantiacus, and Chlorobium tepidum. The work focused on understanding structure-function relationships in energy transfer processes in these complexes through experiments and trying to model that data as we tested our theoretical assumptions with calculations. Theoretical exciton calculations on tubular pigment aggregates yield electronic absorption spectra that are superimpositions of linear J-aggregate spectra. The electronic spectroscopy of BChl c/d/e antennae in light harvesting chlorosomes from Chloroflexus aurantiacus differs considerably from J-aggregate spectra. Strong symmetry breaking is needed if we hope to simulate the absorption spectra of the BChl c antenna. The theory for simulating absorption difference spectra in strongly coupled photosynthetic antenna is described, first for a relatively simple heterodimer, then for the general N-pigment system. The theory is applied to the Fenna-Matthews-Olson (FMO) BChl a protein trimers from Prosthecochloris aestuarii and then compared with experimental low-temperature absorption difference spectra of FMO trimers from Chlorobium tepidum. Circular dichroism spectra of the FMO trimer are unusually sensitive to diagonal energy disorder. Substantial differences occur between CD spectra in exciton simulations performed with and without realistic inhomogeneous distribution functions for the input pigment diagonal energies. Anisotropic absorption difference spectroscopy measurements are less consistent with 21-pigment trimer simulations than 7-pigment monomer simulations which assume that the laser-prepared states are localized within a subunit of the trimer. Experimental anisotropies from real samples likely arise from statistical averaging over states with diagonal energies shifted by

  11. Dynamics and friction drag behavior of viscoelastic flows in complex geometries: A multiscale simulation approach

    NASA Astrophysics Data System (ADS)

    Koppol, Anantha Padmanabha Rao

    Flows of viscoelastic polymeric fluids are of great fundamental and practical interest as polymeric materials for commodity and value-added products are processed typically in a fluid state. The nonlinear coupling between fluid motion and microstructure, which results in highly non-Newtonian theology, memory/relaxation and normal stress development or tension along streamlines, greatly complicates the analysis, design and control of such flows. This has posed tremendous challenges to researchers engaged in developing first principles models and simulations that can accurately and robustly predict the dynamical behavior of polymeric flows. Despite this, the past two decades have witnessed several significant advances towards accomplishing this goal. Yet a problem of fundamental and great pragmatic interest has defied solution to years of ardent research by several groups, namely the relationship between friction drag and flow rate in inertialess flows of highly elastic polymer solutions in complex kinematics flows. First principles-based solution of this long-standing problem in non-Newtonian fluid mechanics is the goal of this research. To achieve our objective, it is essential to develop the capability to perform large-scale multiscale simulations, which integrate continuum-level finite element solvers for the conservation of mass and momentum with fast integrators of stochastic differential equations that describe the evolution of polymer configuration. Hence, in this research we have focused our attention on development of a parallel, multiscale simulation algorithm that is capable of robustly and efficiently simulating complex kinematics flows of dilute polymeric solutions using the first principles based bead-spring chain description of the polymer molecules. The fidelity and computational efficiency of the algorithm has been demonstrated via three benchmark flow problems, namely, the plane Couette flow, the Poiseuille flow and the 4:1:4 axisymmetric

  12. 14 CFR 29.1103 - Induction systems ducts and air duct systems.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sufficient distance upstream of the auxiliary power unit compartment to prevent hot gas reverse flow from... stage of the engine supercharger and of the auxiliary power unit compressor must have a drain to prevent... resistant, for other ducts, except that ducts for auxiliary power units must be fireproof within...

  13. Duct injection technology prototype development: Nozzle development Subtask 4. 1, Atomizer specifications for duct injection technology

    SciTech Connect

    Not Available

    1992-02-01

    Babcock Wilcox has conducted a program to identify atomizers appropriate for successful in-duct injection of humidification water and lime slurries. The purpose of this program was to identify and quantify atomizer spray and performance criteria that affect the operations and reliability of the in-duct SO{sub 2} removal process, and compare commercially available atomizers to these criteria.

  14. Cationic complexation with dissolved organic matter: Insights from molecular dynamics computer simulations and NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kalinichev, A. G.; Xu, X.; Kirkpatrick, R.

    2006-12-01

    Dissolved organic matter (DOM) is ubiquitous in soil and surface water and plays many important geochemical and environmental roles acting as a proton donor/acceptor and pH buffer and interacting with metal ions, minerals and organic species to form water-soluble and water-insoluble complexes of widely differing chemical and biological stabilities. There are strong correlations among the concentration of DOM and the speciation, solubility and toxicity of many trace metals in soil and water due to metal-DOM interaction. DOM can also significantly negatively affect the performance of nanofiltration and reverse osmosis membranes used industrially for water purification and desalination, being one of the major causes of a so-called `membrane bio- fouling'. The molecular scale mechanisms and dynamics of the DOM interactions with metals and membranes are, however, quite poorly understood. Methods of computational molecular modeling, combined with element- specific nuclear magnetic resonance (NMR) spectroscopy, can serve as highly effective tools to probe and quantify on a fundamental molecular level the DOM interactions with metal cations in aqueous solutions, and to develop predictive models of the molecular mechanisms responsible for the metal-DOM complexation in the environment. This paper presents the results of molecular dynamics (MD) computer simulations of the interaction of DOM with dissolved Na+, Cs+, Mg2+, and Ca2+. Na+ forms only very weak outer-sphere complexes with DOM. These results and the results of other recent molecular modeling efforts (e.g., Sutton et al., Environmental Toxicology and Chemistry, 24, 1902-1911, 2005), clearly indicate that both the structural and dynamic aspects of the cation-DOM complexation follow a simple trend in terms of the charge/size ratio for the ions. Due to the competition between ion hydration in bulk aqueous solution and adsorption of these cations by the negatively charged DOM functional groups (primarily carboxylate

  15. Device for Measuring Low Flow Speed in a Duct

    NASA Technical Reports Server (NTRS)

    Quinn, Frank; Magee, Kevin

    2009-01-01

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

  16. Prediction of peptide binding to a major histocompatibility complex class I molecule based on docking simulation.

    PubMed

    Ishikawa, Takeshi

    2016-10-01

    Binding between major histocompatibility complex (MHC) class I molecules and immunogenic epitopes is one of the most important processes for cell-mediated immunity. Consequently, computational prediction of amino acid sequences of MHC class I binding peptides from a given sequence may lead to important biomedical advances. In this study, an efficient structure-based method for predicting peptide binding to MHC class I molecules was developed, in which the binding free energy of the peptide was evaluated by two individual docking simulations. An original penalty function and restriction of degrees of freedom were determined by analysis of 361 published X-ray structures of the complex and were then introduced into the docking simulations. To validate the method, calculations using a 50-amino acid sequence as a prediction target were performed. In 27 calculations, the binding free energy of the known peptide was within the top 5 of 166 peptides generated from the 50-amino acid sequence. Finally, demonstrative calculations using a whole sequence of a protein as a prediction target were performed. These data clearly demonstrate high potential of this method for predicting peptide binding to MHC class I molecules.

  17. Percolation in nanocomposites with complex geometries: Experimental and Monte Carlo simulation studies

    NASA Astrophysics Data System (ADS)

    Stevens, D. R.; Downen, L. N.; Clarke, L. I.

    2008-12-01

    The development of nanocomposites (a matrix, often polymeric, enhanced by a particle with a nanometer-sized dimension) has expanded dramatically in recent years with a particular focus on materials with complex microstructure and nanostructure. Such composites rely on formation of a connected network of particles throughout the sample volume in order to enhance the polymer’s mechanical and electrical properties. From a fundamental perspective, this network formation will be governed by a percolation process within the constrained geometry of the particular microstructure. In this paper, the percolation process within a particular complex nanostructure, namely, a mat of electrospun nanofibers with fiber size of ≈100nm and high porosity, is studied via continuum Monte Carlo simulations, where the sample geometry (fiber and particle sizes, orientation, and sample porosity) is matched to the mats utilized in our previous experimental work. A good agreement between experimental and computational results is observed. Simulations of spherical dopant in uniform samples, with zero, one, or two sample dimensions similar in size to the particle, were completed to explore the effects of confinement, in particular within a single fiber. These results were compared and contrasted with those from porous fibrous mats to determine the influence of porosity on the critical volume fraction. The results indicate that percolation in fibrous mats occurs via pathways that include sections of many fibers rather than being contained within single fibers which span the sample. The detailed dependence of critical volume fraction on porosity and the sensitivity to fiber number and width is discussed.

  18. Initial Inductive Learning in a Complex Computer Simulated Environment: The Role of Metacognitive Skills and Intellectual Ability.

    ERIC Educational Resources Information Center

    Veenman, M. V. J.; Prins, F. J.; Elshout, J. J.

    2002-01-01

    Discusses conceptual knowledge acquisition using computer simulation and describes a study of undergraduates that examined the role of metacognitive skillfulness and intellectual ability during initial inductive learning with a complex computer simulation. Results showed that metacognitive skillfulness was positively related to learning behavior…

  19. A DYNAMIC PHYSIOLOGICALLY-BASED TOXICOKINETIC (DPBTK) MODEL FOR SIMULATION OF COMPLEX TOLUENE EXPOSURE SCENARIOS IN HUMANS

    EPA Science Inventory

    A GENERAL PHYSIOLOGICAL AND TOXICOKINETIC (GPAT) MODEL FOR SIMULATION OF COMPLEX TOLUENE EXPOSURE SCENARIOS IN HUMANS. E M Kenyon1, T Colemen2, C R Eklund1 and V A Benignus3. 1U.S. EPA, ORD, NHEERL, ETD, PKB, RTP, NC, USA; 2Biological Simulators, Inc., Jackson MS, USA, 3U.S. EP...

  20. Numerical methods for the simulation of complex multi-body flows with applications for the integrated Space Shuttle vehicle

    NASA Technical Reports Server (NTRS)

    Chan, William M.

    1992-01-01

    The following papers are presented: (1) numerical methods for the simulation of complex multi-body flows with applications for the Integrated Space Shuttle vehicle; (2) a generalized scheme for 3-D hyperbolic grid generation; (3) collar grids for intersecting geometric components within the Chimera overlapped grid scheme; and (4) application of the Chimera overlapped grid scheme to simulation of Space Shuttle ascent flows.

  1. Simulating pollutant transport in complex terrain with a Lagrangian particle dispersion model

    NASA Astrophysics Data System (ADS)

    Szintai, B.; Kaufmann, P.; Rotach, M. W.

    2009-04-01

    Lagrangian particle dispersion models (LPDMs) are among the most sophisticated tools to simulate atmospheric dispersion of pollutants, and are widely used in emergency response systems. In these systems, LPDMs should be coupled with a numerical weather prediction (NWP) model, which provides information from the mean wind as well as from the turbulence state of the atmosphere. Mean wind can directly be used from the NWP model, while turbulence characteristics have to be parameterized by a so-called meteorological pre-processor. In most cases, to diagnose turbulence variables, meteorological pre-processors use similarity theory approaches, which are based on turbulence datasets over flat and homogeneous surface. However, turbulence structure in complex terrain, such as in steep and narrow Alpine valleys, can be substantially different from flat conditions. In this study a new scaling approach from Weigel et al. (2007), based on measurements and model simulations of the Riviera Project in the framework of the Mesoscale Alpine Program (MAP), is investigated with respect to pollutant dispersion. In the Riviera Project, analysis of turbulence measurements in a steep and narrow Alpine valley showed that daytime profiles of Turbulent Kinetic Energy (TKE) scale very well if the convective velocity scale w* is obtained from the sunlit eastern slope rather than from the surface directly under the measured profiles. This scaling behaviour was also reproduced by high-resolution Large Eddy Simulation runs. To improve the performance of the dispersion model in complex terrain, this new scaling approach is introduced in the meteorological pre-processor of the LPDM and results are validated with a real tracer experiment. For the evaluation of the dispersion model, the TRANSALP tracer experiment is used. During this experiment passive tracers were released and detected in an Alpine valley in Southern Switzerland on two days in October 1989. To simulate this case the operational

  2. Coarse-grained simulations of vortex dynamics and transition in complex high-Re flows

    SciTech Connect

    Grinstein, Fernando F

    2011-01-21

    Turbulent flow complexity in applications in engineering, geophysics and astrophysics typically requires achieving accurate and dependable large scale predictions of highly nonlinear processes with under-resolved computer simulation models. Laboratory observations typically demonstrate the end outcome of complex non-linear three-dimensional physical processes with many unexplained details and mechanisms. Carefully controlled computational experiments based on the numerical solution of the conservation equations for mass, momentum, and energy, provide insights into the underlying flow dynamics. Relevant computational fluid dynamics issues to be addressed relate to the modeling of the unresolved tlow conditions at the subgrid scale (SGS) level - within a computational cell, and at the supergrid (SPG) scale - at initialization and beyond computational boundaries. SGS and SPG information must be prescribed for closure of the equations solved numerically. SGS models appear explicitly or implicitly as additional source tenns in the modified flow equations solved by the numerical solutions being calculated, while SPG models provide the necessary set of initial and boundary conditions that must be prescribed to ensure unique well-posed solutions. From this perspective, it is clear that the simulation process is inherently determined by the SGS and SPG information prescription process. On the other hand, observables in laboratory experiments are always characterized by the finite scales of the instrumental resolution of measuring/visualizing devices, and subject as well to SPG issues. It is thus important to recognize the inherently intrusive nature of observations based on numerical or laboratory experiments. Ultimately, verification and validation (V & V) frameworks and appropriate metrics for the specific problems at hand are needed to establish predictability of the simulation model. Direct numerical simulation (DNS) - resolving all relevant space/time scales, is

  3. Lattice based Kinetic Monte Carlo Simulations of a complex chemical reaction network

    NASA Astrophysics Data System (ADS)

    Danielson, Thomas; Savara, Aditya; Hin, Celine

    Lattice Kinetic Monte Carlo (KMC) simulations offer a powerful alternative to using ordinary differential equations for the simulation of complex chemical reaction networks. Lattice KMC provides the ability to account for local spatial configurations of species in the reaction network, resulting in a more detailed description of the reaction pathway. In KMC simulations with a large number of reactions, the range of transition probabilities can span many orders of magnitude, creating subsets of processes that occur more frequently or more rarely. Consequently, processes that have a high probability of occurring may be selected repeatedly without actually progressing the system (i.e. the forward and reverse process for the same reaction). In order to avoid the repeated occurrence of fast frivolous processes, it is necessary to throttle the transition probabilities in such a way that avoids altering the overall selectivity. Likewise, as the reaction progresses, new frequently occurring species and reactions may be introduced, making a dynamic throttling algorithm a necessity. We present a dynamic steady-state detection scheme with the goal of accurately throttling rate constants in order to optimize the KMC run time without compromising the selectivity of the reaction network. The algorithm has been applied to a large catalytic chemical reaction network, specifically that of methanol oxidative dehydrogenation, as well as additional pathways on CeO2(111) resulting in formaldehyde, CO, methanol, CO2, H2 and H2O as gas products.

  4. Atomistic simulation for deforming complex alloys with application toward TWIP steel and associated physical insights

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Xu, Shaofeng; Liu, Jiabin; Li, Xiaoyan; Wei, Yujie; Wang, Hongtao; Gao, Huajian; Yang, Wei

    2017-01-01

    The interest in promoting deformation twinning for plasticity is mounting for advanced materials. In contrast to disordered grain boundaries, highly organized twin boundaries are beneficial to promoting strength-ductility combination. Twinning deformation typically involves the kinetics of stacking faults, its interplay with dislocations, as well as the interactions between dislocations and twin boundaries. While the latter has been intensively studied, the dynamics of stacking faults has been rarely touched upon. In this work, we report new physical insights on the stacking fault dynamics in twin induced plasticity (TWIP) steels. The atomistic simulation is made possible by a newly introduced approach: meta-atom molecular dynamics simulation. The simulation suggests that the stacking fault interactions are dominated by dislocation reactions that take place spontaneously, different from the existing mechanisms. Whether to generate a single stacking fault, or a twinning partial and a trailing partial dislocation, depends upon a unique parameter, namely the stacking fault energy. The latter in turn determines the deformation twinning characteristics. The complex twin-slip and twin-dislocation interactions demonstrate the dual role of deformation twins as both the dislocation barrier and dislocation storage. This duality contributes to the high strength and high ductility of TWIP steels.

  5. In-flight simulation of high agility through active control: Taming complexity by design

    NASA Technical Reports Server (NTRS)

    Padfield, Gareth D.; Bradley, Roy

    1993-01-01

    The motivation for research into helicopter agility stems from the realization that marked improvements relative to current operational types are possible, yet there is a dearth of useful criteria for flying qualities at high performance levels. Several research laboratories are currently investing resources in developing second generation airborne rotorcraft simulators. The UK's focus has been the exploitation of agility through active control technology (ACT); this paper reviews the results of studies conducted to date. The conflict between safety and performance in flight research is highlighted and the various forms of safety net to protect against system failures are described. The role of the safety pilot, and the use of actuator and flight envelope limiting are discussed. It is argued that the deep complexity of a research ACT system can only be tamed through a requirement specification assembled using design principles and cast in an operational simulation form. Work along these lines conducted at DRA is described, including the use of the Jackson System Development method and associated Ada simulation.

  6. Unveiling the complex glassy dynamics of square shoulder systems: simulations and theory.

    PubMed

    Das, Gayatri; Gnan, Nicoletta; Sciortino, Francesco; Zaccarelli, Emanuela

    2013-04-07

    We performed extensive molecular dynamics (MD) simulations, supplemented by Mode Coupling Theory (MCT) calculations, for the square shoulder model, a purely repulsive potential where the hardcore is complemented by a finite shoulder. For the one-component version of this model, MCT predicted [Sperl et al., Phys. Rev. Lett. 104, 145701 (2010)] the presence of diffusion anomalies both upon cooling and upon compression and the occurrence of glass-glass transitions. In the simulations, we focus on a non-crystallising binary mixture, which, at the investigated shoulder width, shows a non-monotonic behaviour of the diffusion upon cooling but not upon isothermal compression. In addition, we find the presence of a disconnected glass-glass line in the phase diagram, ending in two higher order singularities. These points generate a logarithmic dependence of the density correlators as well as a subdiffusive behaviour of the mean squared displacement, although with the interference of the nearby liquid-glass transition. We also perform novel MCT calculations using as input the partial structure factors obtained within MD, confirming the simulation results. The presence of two hard sphere glasses, differing only in their hardcore length, is revealed, showing that the simple competition between the two is sufficient for creating a rather complex dynamical behaviour.

  7. Transurethral resection of the ejaculatory duct.

    PubMed

    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

  8. Simulation Based Optimization of Complex Monolithic Composite Structures Using Cellular Core Technology

    NASA Astrophysics Data System (ADS)

    Hickmott, Curtis W.

    Cellular core tooling is a new technology which has the capability to manufacture complex integrated monolithic composite structures. This novel tooling method utilizes thermoplastic cellular cores as inner tooling. The semi-rigid nature of the cellular cores makes them convenient for lay-up, and under autoclave temperature and pressure they soften and expand providing uniform compaction on all surfaces including internal features such as ribs and spar tubes. This process has the capability of developing fully optimized aerospace structures by reducing or eliminating assembly using fasteners or bonded joints. The technology is studied in the context of evaluating its capabilities, advantages, and limitations in developing high quality structures. The complex nature of these parts has led to development of a model using the Finite Element Analysis (FEA) software Abaqus and the plug-in COMPRO Common Component Architecture (CCA) provided by Convergent Manufacturing Technologies. This model utilizes a "virtual autoclave" technique to simulate temperature profiles, resin flow paths, and ultimately deformation from residual stress. A model has been developed simulating the temperature profile during curing of composite parts made with the cellular core technology. While modeling of composites has been performed in the past, this project will look to take this existing knowledge and apply it to this new manufacturing method capable of building more complex parts and develop a model designed specifically for building large, complex components with a high degree of accuracy. The model development has been carried out in conjunction with experimental validation. A double box beam structure was chosen for analysis to determine the effects of the technology on internal ribs and joints. Double box beams were manufactured and sectioned into T-joints for characterization. Mechanical behavior of T-joints was performed using the T-joint pull-off test and compared to traditional

  9. Molecular Simulation-Based Structural Prediction of Protein Complexes in Mass Spectrometry: The Human Insulin Dimer

    PubMed Central

    Li, Jinyu; Rossetti, Giulia; Dreyer, Jens; Raugei, Simone; Ippoliti, Emiliano; Lüscher, Bernhard; Carloni, Paolo

    2014-01-01

    Protein electrospray ionization (ESI) mass spectrometry (MS)-based techniques are widely used to provide insight into structural proteomics under the assumption that non-covalent protein complexes being transferred into the gas phase preserve basically the same intermolecular interactions as in solution. Here we investigate the applicability of this assumption by extending our previous structural prediction protocol for single proteins in ESI-MS to protein complexes. We apply our protocol to the human insulin dimer (hIns2) as a test case. Our calculations reproduce the main charge and the collision cross section (CCS) measured in ESI-MS experiments. Molecular dynamics simulations for 0.075 ms show that the complex maximizes intermolecular non-bonded interactions relative to the structure in water, without affecting the cross section. The overall gas-phase structure of hIns2 does exhibit differences with the one in aqueous solution, not inferable from a comparison with calculated CCS. Hence, care should be exerted when interpreting ESI-MS proteomics data based solely on NMR and/or X-ray structural information. PMID:25210764

  10. Examination of climatological wind patterns and simulated pollen dispersion in a complex island environment.

    PubMed

    Viner, Brian J; Arritt, Raymond W; Westgate, Mark E

    2017-03-29

    Complex terrain creates small-scale circulations which affect pollen dispersion but may be missed by meteorological observing networks and coarse-grid meteorological models. On volcanic islands, these circulations result from differing rates of surface heating between land and sea as well as rugged terrain. We simulated the transport of bentgrass, ryegrass, and maize pollen from 30 sources within the agricultural regions of the Hawaiian island Kaua'i during climatological conditions spanning season conditions and the La Niña, El Niño, and neutral phases of the El Niño-Southern Oscillation. Both pollen size and source location had major effects on predicted dispersion over and near the island. Three patterns of pollen dispersion were identified in response to prevailing wind conditions: southwest winds transported pollen inland, funneling pollen grains through valleys; east winds transported pollen over the ocean, with dispersive tails for the smallest pollen grains following the mean wind and extending as far as the island of Ni'ihau 35 km away; and northeast winds moved pollen inland counter to the prevailing flow due to a sea breeze circulation that formed over the source region. These results are the first to predict the interactions between complex island terrain and local climatology on grass pollen dispersion. They demonstrate how numerical modeling can provide guidance for field trials by illustrating the common flow regimes present in complex terrain, allowing field trials to focus on areas where successful sampling is more likely to occur.

  11. Complex Urban Simulations and Sustainable Urban Planning with Spatial and Social Implications

    NASA Astrophysics Data System (ADS)

    Becker, T.; Boschert, S.; Hempel, L.; Höffken, S.; Obst, B.

    2013-09-01

    Cities can be seen as complex systems of heterogeneous processes with a high variety of different influences (e.g. social, infrastructural, economic, and political impacts). This especially applies for tasks concerning urban development of existing assets. The optimization of traffic flows, reduction of emissions, improvement of energy efficiency, but also urban climate and landscape planning issues require the involvement of many different actors, balancing different perspectives, and divergent claims. The increasing complexities of planning and decision processes make high demands on professionals of various disciplines, government departments, and municipal decision-makers. In the long term, topics like urban resilience, energy management, risk and resource management have to be taken into account and reflected in future projects, but always related to socio-spatial and governmental aspects. Accordingly, it is important to develop models to be able to understand and analyze the outcomes and effects of governmental measures and planning to the urban environment. Thus, a more systematic approach is needed - going away from welldefined city models to city system models. The purpose is to describe urban processes not only quantitatively, but to grasp their qualitative complexity and interdependencies, by modeling and simulating existing urban systems. This contribution will present the City System Model (CSM) concept closely related to an Urban Energy Planning use case, will highlight the methodology, and focus on first results and findings from an ongoing interdisciplinary research project and use case to improve the basis of information for decision-makers and politicians about urban planning decisions.

  12. Endoscopic management of ejaculatory duct obstruction.

    PubMed

    Aggour, A; Mostafa, H; Maged, W

    1998-01-01

    A total of 191 patients were evaluated at our department for azoospermia, and 11 were found to have azoospermia due to ejaculatory duct obstruction as proved by normal serum hormones, normal testicular biopsy, low ejaculate volume and absence of fructose in semen. Also transrectal ultrasound was performed, revealing distended seminal vesicles and dilated ejaculatory ducts. All these criteria together suggested ejaculatory duct obstruction as a cause of azoospermia. All patients underwent endoscopic management for treatment of their ejaculatory duct obstruction in the form of resection and/or incision of the ejaculatory duct ostium inside the urethra and patency was checked intraoperatively by injection of sterile methylene blue in the vas and visualizing the efflux of the blue dye endoscopically. Intraoperative patency was documented in 10 patients and postoperative patency by follow-up semen analysis in 7 patients (70% patency rate) of which 2 (20% pregnancy rate) were able to conceive within 2 years of endoscopic treatment. Postoperative complications included acute urinary retention in 1 patient, haematuria in 5 and recurrent epididymitis in 2 patients.

  13. Salivary duct carcinoma of the parotid gland

    PubMed Central

    Mlika, Mona; Kourda, Nadia; Zidi, YSH; Aloui, Raoudha; Zneidi, Nadia; Rammeh, Soumaya; Zermani, Rachida; Jilani, Sarah Ben

    2012-01-01

    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. PMID:22434951

  14. Characterization of flow in a scroll duct

    NASA Technical Reports Server (NTRS)

    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.

  15. Acoustic mode radiation from the termination of a truncated nonlinear internal gravity wave duct in a shallow ocean area.

    PubMed

    Lin, Ying-Tsong; Duda, Timothy F; Lynch, James F

    2009-10-01

    Horizontal ducting of sound between short-wavelength nonlinear internal gravity waves in coastal environments has been reported in many theoretical and experimental studies. Important consequences arising at the open end of an internal wave duct (the termination) are examined in this paper with three-dimensional normal mode theory and parabolic approximation modeling. For an acoustic source located in such a duct and sufficiently far from the termination, some of the propagating sound may exit the duct by penetrating the waves at high grazing angles, but a fair amount of the sound energy is still trapped in the duct and propagates toward the termination. Analysis here shows that the across-duct sound energy distribution at the termination is unique for each acoustic vertical mode, and as a result the sound radiating from the termination of the duct forms horizontal beams that are different for each mode. In addition to narrowband analysis, a broadband simulation is made for water depths of order 80 m and propagation distances of 24 km. Situations occur with one or more modes absent in the radiated field and with mode multipath in the impulse response. These are both consistent with field observations.

  16. Convolution seal for transition duct in turbine system

    DOEpatents

    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.

  17. Searching the conformational complexity and binding properties of HDAC6 through docking and molecular dynamic simulations.

    PubMed

    Sixto-López, Yudibeth; Bello, Martiniano; Rodríguez-Fonseca, Rolando Alberto; Rosales-Hernández, Martha Cecilia; Martínez-Archundia, Marlet; Gómez-Vidal, José Antonio; Correa-Basurto, José

    2016-09-23

    Histone deacetylases (HDACs) are a family of proteins involved in the deacetylation of histones and other non-histones substrates. HDAC6 belongs to class II and shares similar biological functions with others of its class. Nevertheless, its three-dimensional structure that involves the catalytic site remains unknown for exploring the ligand recognition properties. Therefore, in this contribution, homology modeling, 100-ns-long Molecular Dynamics (MD) simulation and docking calculations were combined to explore the conformational complexity and binding properties of the catalytic domain 2 from HDAC6 (DD2-HDAC6), for which activity and affinity toward five different ligands have been reported. Clustering analysis allowed identifying the most populated conformers present during the MD simulation, which were used as starting models to perform docking calculations with five DD2-HDAC6 inhibitors: Cay10603 (CAY), Rocilinostat (RCT), Tubastatin A (TBA), Tubacin (TBC), and Nexturastat (NXT), and then were also submitted to 100-ns-long MD simulations. Docking calculations revealed that the five inhibitors bind at the DD2-HDAC6 binding site with the lowest binding free energy, the same binding mode is maintained along the 100-ns-long MD simulations. Overall, our results provide structural information about the molecular flexibility of apo and holo DD2-HDAC6 states as well as insight of the map of interactions between DD2-HDAC6 and five well-known DD2-HDAC6 inhibitors allowing structural details to guide the drug design. Finally, we highlight the importance of combining different theoretical approaches to provide suitable structural models for structure-based drug design.

  18. Response of the intermediate complexity Mars Climate Simulator to different obliquity angles

    NASA Astrophysics Data System (ADS)

    Segschneider, J.; Grieger, B.; Keller, H. U.; Lunkeit, F.; Kirk, E.; Fraedrich, K.; Rodin, A.; Greve, R.

    2005-05-01

    A climate model of intermediate complexity, named the Mars Climate Simulator, has been developed based on the Portable University Model of the Atmosphere (PUMA). The main goal of this new development is to simulate the climate variations on Mars resulting from the changes in orbital parameters and their impact on the layered polar terrains (also known as permanent polar ice caps). As a first step towards transient simulations over several obliquity cycles, the model is applied to simulate the dynamical and thermodynamical response of the Martian climate system to different but fixed obliquity angles. The model is forced by the annual and daily cycle of solar insolation. Experiments have been performed for obliquities of φ=15∘ (minimum), φ=25.2∘ (present), and φ=35∘ (maximum). The resulting changes in solar insolation mainly in the polar regions impact strongly on the cross-equatorial circulation which is driven by the meridional temperature gradient and steered by the Martian topography. At high obliquity, the cross-equatorial near surface flow from the winter to the summer hemisphere is strongly enhanced compared to low obliquity periods. The summer ground temperature ranges from 200 K (φ=15∘) to 250 K (φ=35∘) at 80∘N in northern summer, and from 220 K (φ=15∘) to 270 K (φ=35∘) at 80∘S in southern summer. In the atmosphere at 1 km above ground, the respective range is 195-225 K in northern summer, and 210-250 K in southern summer.

  19. Adaptive, High-Order, and Scalable Software Elements for Dynamic Rupture Simulations in Complex Geometries

    NASA Astrophysics Data System (ADS)

    Kozdon, J. E.; Wilcox, L.; Aranda, A. R.

    2014-12-01

    The goal of this work is to develop a new set of simulation tools for earthquake rupture dynamics based on state-of-the-art high-order, adaptive numerical methods capable of handling complex geometries. High-order methods are ideal for earthquake rupture simulations as the problems are wave-dominated and the waves excited in simulations propagate over distance much larger than their fundamental wavelength. When high-order methods are used for such problems significantly fewer degrees of freedom are required as compared with low-order methods. The base numerical method in our new software elements is a discontinuous Galerkin method based on curved, Kronecker product hexahedral elements. We currently use MPI for off-node parallelism and are in the process of exploring strategies for on-node parallelism. Spatial mesh adaptivity is handled using the p4est library and temporal adaptivity is achieved through an Adams-Bashforth based local time stepping method; we are presently in the process of including dynamic spatial adaptivity which we believe will be valuable for capturing the small-scale features around the propagating rupture front. One of the key features of our software elements is that the method is provably stable, even after the inclusion of the nonlinear frictions laws which govern rupture dynamics. In this presentation we will both outline the structure of the software elements as well as validate the rupture dynamics with SCEC benchmark test problems. We are also presently developing several realistic simulation geometries which may also be reported on. Finally, the software elements that we have designed are fully public domain and have been designed with tightly coupled, wave dominated multiphysics applications in mind. This latter design decisions means the software elements are applicable to many other geophysical and non-geophysical applications.

  20. Study on Pressure Wave Propagation in a Liquid Containing Spherical Bubbles in a Rectangular Duct

    NASA Astrophysics Data System (ADS)

    Kawahara, Junya; Watanabe, Masao; Kobayashi, Kazumichi

    2015-12-01

    Pressure wave propagation in a liquid containing several bubbles is numerically investigated. We simulate liner plane wave propagation in a liquid containing 10 spherical bubbles in a rectangular duct with the equation of motion for N spherical bubbles. The sound pressures of the reflected waves from the rigid walls are calculated by using the method of images. The result shows that the phase velocity of the pressure wave propagating in the liquid containing 10 spherical bubbles in the duct agrees well with the low-frequency speed of sound in a homogeneous bubbly liquid.

  1. 21. STATION 70.5 OF MST, WEST SIDE. AIRCONDITIONING DUCT AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. STATION 70.5 OF MST, WEST SIDE. AIR-CONDITIONING DUCT AT TOP; POWER BOX ON RIGHT; WINCH ON LEFT. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  2. An immersed boundary method for direct and large eddy simulation of stratified flows in complex geometry

    NASA Astrophysics Data System (ADS)

    Rapaka, Narsimha R.; Sarkar, Sutanu

    2016-10-01

    A sharp-interface Immersed Boundary Method (IBM) is developed to simulate density-stratified turbulent flows in complex geometry using a Cartesian grid. The basic numerical scheme corresponds to a central second-order finite difference method, third-order Runge-Kutta integration in time for the advective terms and an alternating direction implicit (ADI) scheme for the viscous and diffusive terms. The solver developed here allows for both direct numerical simulation (DNS) and large eddy simulation (LES) approaches. Methods to enhance the mass conservation and numerical stability of the solver to simulate high Reynolds number flows are discussed. Convergence with second-order accuracy is demonstrated in flow past a cylinder. The solver is validated against past laboratory and numerical results in flow past a sphere, and in channel flow with and without stratification. Since topographically generated internal waves are believed to result in a substantial fraction of turbulent mixing in the ocean, we are motivated to examine oscillating tidal flow over a triangular obstacle to assess the ability of this computational model to represent nonlinear internal waves and turbulence. Results in laboratory-scale (order of few meters) simulations show that the wave energy flux, mean flow properties and turbulent kinetic energy agree well with our previous results obtained using a body-fitted grid (BFG). The deviation of IBM results from BFG results is found to increase with increasing nonlinearity in the wave field that is associated with either increasing steepness of the topography relative to the internal wave propagation angle or with the amplitude of the oscillatory forcing. LES is performed on a large scale ridge, of the order of few kilometers in length, that has the same geometrical shape and same non-dimensional values for the governing flow and environmental parameters as the laboratory-scale topography, but significantly larger Reynolds number. A non-linear drag law

  3. Mental workload when driving in a simulator: effects of age and driving complexity.

    PubMed

    Cantin, Vincent; Lavallière, Martin; Simoneau, Martin; Teasdale, Normand

    2009-07-01

    Driving errors for older drivers may result from a higher momentary mental workload resulting from complex driving situations, such as intersections. The present study examined if the mental workload of young and older active drivers vary with the difficulty of the driving context. We adopted the probe reaction time (RT) technique to measure the workload while driving in a simulator. The technique provided clear instructions about the primary (driving) and secondary (RT) tasks. To avoid structural interference, the secondary task consisted of responding as rapidly as possible with a vocal response ("top") to an auditory stimulus. Participants drove through a continuous 26.4-km scenario including rural and urban sections and probes (stimuli) were given in a baseline static condition and in three different driving contexts embedded into the overall driving scenario. Specifically, stimuli were given randomly when (a) driving on straight roads at a constant speed, (b) approaching intersections for which the driver had to stop the car, and (c) when overtaking a slower vehicle. Unless a driving error was made, drivers did not need any emergency responses. Reaction time was defined as the temporal interval between the auditory stimulus and the onset of the corresponding verbal response detected from the analog signal of a piezo-electric microphone fixed on a headset (ms accuracy). Baseline RTs were similar for both groups. Both groups showed longer RTs when driving and RTs increased as the complexity of the driving contexts increased (driving straights, intersections, overtaking maneuvers). Compared to younger drivers, however, older drivers showed longer RTs for all driving contexts and the most complex driving context (overtaking maneuvers) yielded a disproportionate increase. In conclusion, driving leads to a greater mental workload for the older drivers than for the younger drivers and this effect was exacerbated by the more complex driving context (overtaking

  4. User's Manual for DuctE3D: A Program for 3D Euler Unsteady Aerodynamic and Aeroelastic Analysis of Ducted Fans

    NASA Technical Reports Server (NTRS)

    Srivastava, R.; Reddy, T. S. R.

    1997-01-01

    The program DuctE3D is used for steady or unsteady aerodynamic and aeroelastic analysis of ducted fans. This guide describes the input data required and the output files generated, in using DuctE3D. The analysis solves three dimensional unsteady, compressible Euler equations to obtain the aerodynamic forces. A normal mode structural analysis is used to obtain the aeroelastic equations, which are solved using either the time domain or the frequency domain solution method. Sample input and output files are included in this guide for steady aerodynamic analysis and aeroelastic analysis of an isolated fan row.

  5. Phase-field simulations of GaN growth by selective area epitaxy from complex mask geometries

    SciTech Connect

    Aagesen, Larry K.; Thornton, Katsuyo; Coltrin, Michael E.; Han, Jung

    2015-05-21

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. The model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. The model provides a route to optimize masks and processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.

  6. Phase-field simulations of GaN growth by selective area epitaxy on complex mask geometries

    DOE PAGES

    Aagesen, Larry K.; Coltrin, Michael Elliott; Han, Jung; ...

    2015-05-15

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. Furthermore, this model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. We found that the model provides a route to optimize masks andmore » processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.« less

  7. Phase-field simulations of GaN growth by selective area epitaxy on complex mask geometries

    SciTech Connect

    Aagesen, Larry K.; Coltrin, Michael Elliott; Han, Jung; Thornton, Katsuyo

    2015-05-15

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. Furthermore, this model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. We found that the model provides a route to optimize masks and processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.

  8. Unusual giant sialolith of Wharton's duct

    PubMed Central

    Gadve, Vandana; Mohite, Apurva; Bang, Kshitij; Shenoi, S. R.

    2016-01-01

    Salivary gland calculi account for the most common disease of the salivary glands. Most of the salivary calculi are small in size. Some calculi that reach several centimeters are reported as megaliths or giant calculi in the literature. They may occur in any of the salivary gland ducts but are most common in Wharton's duct and in the submandibular gland. This report presents clinical and radiographical sign of an unusually large sialolith. A patient came with pain in the floor of mouth. There was a swelling on floor of mouth on the left side. Radiographical examination revealed large irregular radio-opaque mass superimposed on left lateral incisor to molar areas. This case report describes a patient presenting with an unusually large submandibular gland duct sialolith, the subsequent patient management, the etiology, diagnosis, and its treatment. PMID:27795655

  9. Iatrogenic bile duct injuries in kashmir valley.

    PubMed

    Chowdri, Nisar A; Dar, Farooq A; Naikoo, Zahoor A; Wani, Nazir A; Parray, Fazl Q; Wani, Khurshid A

    2010-08-01

    Cholecystectomy is one of the commonest operations performed throughout the world and bile duct injury is the worst complication of this procedure. In a prospective and retrospective study 25 patients were seen in a tertiary care hospital over a period of 10 years. 72% of patients were referred from other hospitals. 48% of patients presented within one month of injury. Pain was the commonest presentation (92%) followed by jaundice (80%). Liver functions were deranged in 70% of patients, USG revealed biliary dilatation in 69.6% of patients. ERCP was done in 16 patients and revealed cut off of the common hepatic duct in 43.8% of patients. Intraoperative findings revealed adhesions in 96% of patients. 48% of patients had bile duct stricture. Roux-en-Y hepaticojejunostomy was the commonest procedure performed. All patients showed improvement in liver function after surgery. Wound infection was the commonest complication seen in 32% patients. 3 patients died in our series.

  10. Unusual giant sialolith of Wharton's duct.

    PubMed

    Gadve, Vandana; Mohite, Apurva; Bang, Kshitij; Shenoi, S R

    2016-09-01

    Salivary gland calculi account for the most common disease of the salivary glands. Most of the salivary calculi are small in size. Some calculi that reach several centimeters are reported as megaliths or giant calculi in the literature. They may occur in any of the salivary gland ducts but are most common in Wharton's duct and in the submandibular gland. This report presents clinical and radiographical sign of an unusually large sialolith. A patient came with pain in the floor of mouth. There was a swelling on floor of mouth on the left side. Radiographical examination revealed large irregular radio-opaque mass superimposed on left lateral incisor to molar areas. This case report describes a patient presenting with an unusually large submandibular gland duct sialolith, the subsequent patient management, the etiology, diagnosis, and its treatment.

  11. Acoustic energy in ducts - Further observations

    NASA Technical Reports Server (NTRS)

    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.

  12. Film condensation in a horizontal rectangular duct

    NASA Technical Reports Server (NTRS)

    Lu, Qing; Suryanarayana, N. V.

    1993-01-01

    Condensation heat transfer in a horizontal rectangular duct was experimentally and analytically investigated. To prevent the dripping of condensate on the film, the experiment was conducted inside a horizontal rectangular duct with vapor condensing only on the bottom cooled plate of the duct. R-113 and FC-72 (Fluorinert Electronic Fluid developed by the 3M Company) were used as the condensing fluids. The experimental program included measurements of film thickness, local and average heat transfer coefficients, wave length, wave speed, and a study of wave initiation. The measured film thickness was used to obtain the local heat transfer coefficient. The wave initiation was studied both with condensation and with an adiabatic air-liquid flow. The test sections used in both experiments were identical.

  13. Evaluation of PEGIT duct connection system

    SciTech Connect

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

    2003-08-01

    Most air duct system components are assembled in the field and are mechanically fastened by sheet metal screws (for sheet metal-to-sheet metal) or by drawbands (for flex duct-to-sheet metal). Air sealing is separate from this mechanical fastening and is usually achieved using tape or mastic products after mechanical fastening. Field observations have shown that mechanical fastening rarely meets code or manufacturers requirements and that sealing procedures are similarly inconsistent. To address these problems, Proctor Engineering Group (PEG) is developing a system of joining ducts (called PEGIT) that combines the mechanical fastening and sealing into a single self-contained procedure. The PEGIT system uses a shaped flexible seal between specially designed sheet metal duct fittings to both seal and fasten duct sections together. Figure 1 shows the inner duct fitting complete with rubber seal. This seal provides the air seal for the completed fitting and is shaped to allow the inner and outer fittings to slide together, and then to lock the fittings in place. The illustration in Figure 2 shows the approximate cross section of the rubber seal that shows how the seal has a lip that is angled backwards. This angled lip allows the joint to be pushed together by folding flat but then its long axis makes it stiff in the pulling apart direction. This study was undertaken to assist PEG in some of the design aspects of this system and to test the performance of the PEGIT system. This study was carried out in three phases. The initial phase evaluated the performance of a preliminary seal design for the PEGIT system. After the first phase, the seal was redesigned and this new seal was evaluated in the second phase of testing. The third phase performed more detailed testing of the second seal design to optimize the production tolerances of the sheet metal fittings. This report summarizes our findings from the first two phases and provides details about the third phase of testing.

  14. Cavitation erosion in blocked flow with a ducted ice-class propeller

    SciTech Connect

    Doucet, J.M.; Bose, N.; Walker, D.; Jones, S.J.

    1996-12-31

    Ships that operate in ice often encounter momentary increased propeller cavitation because ice pieces block the flow into the propeller. For ducted propellers, this additional cavitation is more significant than it is for open propellers; ice pieces may become lodged against and within the duct and subject the propeller to longer periods of increased cavitation due to the blocked flow. Associated with this blocked flow is the possibility of cavitation erosion on the propeller. An erosion study, using paint films, was conducted in a cavitation tunnel with a model propeller of the type fitted to the Canadian Marine Drilling Ltd. vessel MV Robert LeMeur. A simulated ice blockage was installed ahead of the propeller model and within the duct. Tests were carried out over a range of advance coefficients for various test conditions. The resulting types of cavitation were documented, the erosion patterns were photographed and comparisons between each test were made.

  15. Heat Transfer Enhancement in Solar Air Heater Duct Fitted With Punched Hole Delta Winglets

    NASA Astrophysics Data System (ADS)

    Warrier, Hithesh. U.; Kotebavi, Vinod. M.

    2016-09-01

    This paper investigates the thermal performance of solar air heater fitted with delta winglet type vortex generators with holes punched on it by experimental and numerical analysis. Delta winglet type vortex generators having holes punched onto it are fitted in a duct of size 400*300*30mm.it is placed in duct in 3 different configurations, as an array having 5 pair in one row. Delta winglet pair has an attack angle of 30degree, with height of winglet equal to half of duct height. The study is done for Reynolds's no in the range of 9000 to 25000. Thermal performance is evaluated by analyzing both friction factor and Nussult's number using Webb's correlation for surface roughness. Numerical simulation is done using Ansys fluent. Experimental and numerical results are then compared. Results shows that heat transfer enhancement of about 20-150% can be achieved by using punched hole delta winglet.

  16. a Model for Sound Propagation in Capillary Ducts with Mean Flow

    NASA Astrophysics Data System (ADS)

    Ih, J.-G.; Park, C.-M.; Kim, H.-J.

    1996-02-01

    A theoretical formulation is carried out of acoustic wave propagation in a narrow capillary tube with steady gas flow. The transverse variations of the particle velocity, temperature, and viscosity are considered. A fully developed laminar steady flow is assumed and the concept of a complex propagation constant is introduced in the formulation. The final equation form reduces to a Kummer-type differential equation and its solution is obtained in terms of confluent hypergeometric functions. The dispersion equation for the complex propagation constants takes on a recursive form. A simplified form of the analysis permits comparison with previous results dealing with visco-thermal effects and includes the features of Poiseuille-type laminar steady flow for low and medium shear wave numbers. Numerical simulation results show that the effect of steady flow is very significant for the backward traveling waves, and the assumption of a parabolic velocity profile for shear wave numbers less than four should be used carefully when the flow Mach number is greater than 0·1. The present theory is applicable for shear wave numbers up to 10 or more, with the non-parabolic axial velocity fluctuations included, which encompasses almost all the possible situations of capillary duct dimension, temperature and flow velocity. The theory?!would be useful as an approximation in solving the acoustic problems of the monolith in catalytic converters for automotive exhaust systems and of the propagation of sound in a porous medium.

  17. Congenital Atresia of Wharton’s Duct

    PubMed Central

    Hseu, Anne; Anne, Premchand

    2016-01-01

    This is a case report of a three-month-old male who presented to clinic with a cystic lesion under the tongue. On clinical examination, a cystic lesion was observed in the, floor-of-mouth. The patient was referred to Paediatric Otorhinolaryngology service for further management. The differential diagnoses for floor-of-mouth lesions should be reviewed with primary focus on the Wharton’s duct atresia and its management. It is crucial to recognize submandibular duct atresia in the primary Paediatric clinic in order to expedite management of lesion before complications arise including infection, enlargement of cyst, and feeding and breathing difficulties. PMID:27042492

  18. Duct disruption, a new explanation of miliaria.

    PubMed

    Shuster, S

    1997-01-01

    From argument and a few personal observations, the hypothesis has crystallised that the miliaria commonly occurring in unacclimatised Caucasians visiting hot climates is caused by exposure to ultraviolet irradiation, by an effect on the cells of the upper epidermis, which eventually allows a split to develop between them and the new stratum corneum that grows up beneath, into which sweat from the disrupted ducts can collect as microcysts. This dehiscence is the probable explanation of sunburn peeling and photo-onycholysis. It is concluded that duct disruption, not blockage or dysfunction, is the immediate cause of the miliarias.

  19. Congenital abnormalities of the ovine paramesonephric ducts.

    PubMed

    Smith, K C; Long, S E; Parkinson, T J

    1995-01-01

    A 15 month survey of ovine reproductive tracts was undertaken in slaughterhouses in southwest England. A total of 33506 tracts were examined; 23536 from lambs and 9970 from adults. In total, 3.4% of tracts were pregnant and 3.3% exhibited abnormalities. Twenty cases of uterus unicornis, six of uterus didelphys and 11 of segmental aplasia were encountered, such that partial aplasia of the paramesonephric ducts accounted for 3.3% of all abnormalities. Although developmental abnormalities of the ovine female genital system are relatively uncommon, a substantial proportion of these can be accounted for by development defects of the paramesonephric ducts.

  20. Preconditioning the Helmholtz Equation for Rigid Ducts

    NASA Technical Reports Server (NTRS)

    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.

  1. Pressure Loss in Ducts with Compound Elbows

    DTIC Science & Technology

    1943-02-01

    Report LOSS IN DUCTS WITH COMPOUND ELBOWS By John R. Weske Case School of Applied Science NACA N A c JI LE&.lJ/J \\ 9 **Y @woti AERONAUT WASHINGTON...AEROHATJTICS ADVANCE RESTRICTED REPORT ● -. PRESWRE U)SS IN DUCTS WITH C-ND ELBOWS By John R; Weske SUMMARY . Results are presented of’measurmneut of the...pressure drop and, h some oases, of the velooity distribution in ocxupound elbows WRS undertaken for the purposo of furnishing to the designer of duetIng

  2. Computing Propagation Of Sound In Engine Ducts

    NASA Technical Reports Server (NTRS)

    Saylor, Silvia

    1995-01-01

    Frequency Domain Propagation Model (FREDOM) computer program accounts for acoustic loads applied to components of engines. Models propagation of noise through fluids in ducts between components and through passages within components. Used not only to analyze hardware problems, but also for design purposes. Updated version of FREQPL program easier to use. Devised specifically for use in analyzing acoustic loads in rocket engines. Underlying physical and mathematical concepts implemented also applicable to acoustic propagation in other enclosed spaces; analyzing process plumbing and ducts in industrial buildings with view toward reducing noise in work areas.

  3. Fundamental investigation of duct/ESP phenomena

    SciTech Connect

    Brown, C.A. ); Durham, M.D. ); Sowa, W.A. . Combustion Lab.); Himes, R.M. ); Mahaffey, W.A. )

    1991-10-21

    Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

  4. Sensitivity of the coastal tsunami simulation to the complexity of the 2011 Tohoku earthquake source model

    NASA Astrophysics Data System (ADS)

    Monnier, Angélique; Loevenbruck, Anne; Gailler, Audrey; Hébert, Hélène

    2016-04-01

    The 11 March 2011 Tohoku-Oki event, whether earthquake or tsunami, is exceptionally well documented. A wide range of onshore and offshore data has been recorded from seismic, geodetic, ocean-bottom pressure and sea level sensors. Along with these numerous observations, advance in inversion technique and computing facilities have led to many source studies. Rupture parameters inversion such as slip distribution and rupture history permit to estimate the complex coseismic seafloor deformation. From the numerous published seismic source studies, the most relevant coseismic source models are tested. The comparison of the predicted signals generated using both static and cinematic ruptures to the offshore and coastal measurements help determine which source model should be used to obtain the more consistent coastal tsunami simulations. This work is funded by the TANDEM project, reference ANR-11-RSNR-0023-01 of the French Programme Investissements d'Avenir (PIA 2014-2018).

  5. Simulation of 125I induced DNA strand breaks in a CAP-DNA complex.

    PubMed

    Li, W; Friedland, W; Jacob, P; Paretzke, H G; Panyutin, I; Neumann, R D

    2002-01-01

    The E. coli catabolite gene activator protein (CAP)-DNA complex with 125I located at the position of the H5 atom of the cytosine near the centre was incorporated into the PARTRAC track structure code. DNA strand breaks due to irradiation were calculated by track structure and radical attack simulations; strand breaks due to neutralisation of the highly charged 125Te ion were derived from a semi-empirical distribution. According to the calculations, the neutralisation effect dominates the strand breakage frequency at 2 bases away from the 125I decay site on both strands. The first breakage distribution counted from a 32P labelled end on the strand with 125I agreed well with experimental data, but on the opposite strand, the calculated distribution is more concentrated around the decay site and its yield is about 20% larger than the measured data.

  6. Spectral element simulations of laminar and turbulent flows in complex geometries

    NASA Technical Reports Server (NTRS)

    Karniadakis, George EM

    1989-01-01

    Spectral element methods are high-order weighted residual techniques based on spectral expansions of variables and geometry for the Navier-Stokes (NS) and transport equations. Here, practical aspects of these methods and their efficient implementation are examined, and several examples of flows in truly complex geometries are presented. The spectral element discretization for NS equations is introduced, and the convergence of the method is addressed. An efficient data management scheme is discussed in the context of parallel processing computations. The method is validated by comparing the spectral element solutions with the exact eigensolutions for the Orr-Sommerfeld equations in two and three dimensions. Computer-aided flow visualizations are presented for an impulsive flow past a sharp edge wedge. Three-dimensional states of channel flow disrupted by an array of cylindrical eddy promoters are studied, and the results of a direct simulation of the turbulent flow in a plane channel are presented.

  7. Exact calculations of phase and membrane equilibria for complex fluids by Monte Carlo simulation

    SciTech Connect

    Panagiotopoulos, A.Z.

    1990-08-28

    The general objective of this project is the investigation of phase equilibria for complex fluids using a novel methodology, Monte Carlo simulation in the Gibbs ensemble. The methodology enables the direct determination of the properties of two coexisting fluid phases (e.g. a liquid at equilibrium with its vapor) from a single computer experiment, and is applicable to multicomponent systems with arbitrary equilibrium constraints imposed. The specific goals of this work are to adapt the Gibbs technique to (a) highly asymmetric mixtures with large differences in size and potential energies of interaction (b) chain molecules and (c) ionic systems. Significant progress has been made in all three areas. In this paper, we will briefly describe the progress made in each area, using the same numbering scheme for the tasks as in the original proposal.

  8. Method and apparatus for transfer function simulator for testing complex systems

    NASA Technical Reports Server (NTRS)

    Kavaya, M. J. (Inventor)

    1985-01-01

    A method and apparatus for testing the operation of a complex stabilization circuit in a closed loop system is presented. The method is comprised of a programmed analog or digital computing system for implementing the transfer function of a load thereby providing a predictable load. The digital computing system employs a table stored in a microprocessor in which precomputed values of the load transfer function are stored for values of input signal from the stabilization circuit over the range of interest. This technique may be used not only for isolating faults in the stabilization circuit, but also for analyzing a fault in a faulty load by so varying parameters of the computing system as to simulate operation of the actual load with the fault.

  9. Pulse-spreading harmonic complex as an alternative carrier for vocoder simulations of cochlear implants.

    PubMed

    Mesnildrey, Quentin; Hilkhuysen, Gaston; Macherey, Olivier

    2016-02-01

    Noise- and sine-carrier vocoders are often used to acoustically simulate the information transmitted by a cochlear implant (CI). However, sine-waves fail to mimic the broad spread of excitation produced by a CI and noise-bands contain intrinsic modulations that are absent in CIs. The present study proposes pulse-spreading harmonic complexes (PSHCs) as an alternative acoustic carrier in vocoders. Sentence-in-noise recognition was measured in 12 normal-hearing subjects for noise-, sine-, and PSHC-vocoders. Consistent with the amount of intrinsic modulations present in each vocoder condition, the average speech reception threshold obtained with the PSHC-vocoder was higher than with sine-vocoding but lower than with noise-vocoding.

  10. Curvilinear Immersed Boundary Method for Simulating Fluid Structure Interaction with Complex 3D Rigid Bodies

    PubMed Central

    Borazjani, Iman; Ge, Liang; Sotiropoulos, Fotis

    2010-01-01

    The sharp-interface CURVIB approach of Ge and Sotiropoulos [L. Ge, F. Sotiropoulos, A Numerical Method for Solving the 3D Unsteady Incompressible Navier-Stokes Equations in Curvilinear Domains with Complex Immersed Boundaries, Journal of Computational Physics 225 (2007) 1782–1809] is extended to simulate fluid structure interaction (FSI) problems involving complex 3D rigid bodies undergoing large structural displacements. The FSI solver adopts the partitioned FSI solution approach and both loose and strong coupling strategies are implemented. The interfaces between immersed bodies and the fluid are discretized with a Lagrangian grid and tracked with an explicit front-tracking approach. An efficient ray-tracing algorithm is developed to quickly identify the relationship between the background grid and the moving bodies. Numerical experiments are carried out for two FSI problems: vortex induced vibration of elastically mounted cylinders and flow through a bileaflet mechanical heart valve at physiologic conditions. For both cases the computed results are in excellent agreement with benchmark simulations and experimental measurements. The numerical experiments suggest that both the properties of the structure (mass, geometry) and the local flow conditions can play an important role in determining the stability of the FSI algorithm. Under certain conditions unconditionally unstable iteration schemes result even when strong coupling FSI is employed. For such cases, however, combining the strong-coupling iteration with under-relaxation in conjunction with the Aitken’s acceleration technique is shown to effectively resolve the stability problems. A theoretical analysis is presented to explain the findings of the numerical experiments. It is shown that the ratio of the added mass to the mass of the structure as well as the sign of the local time rate of change of the force or moment imparted on the structure by the fluid determine the stability and convergence of the

  11. Acoustical modes in lined ducts with flexible walls - A variational approach

    NASA Astrophysics Data System (ADS)

    Astley, R. J.

    A unified variational scheme is set forth for calculating axial wavenumbers, attenuations, and pressure distributions for acoustical modes propagating in flexible lined ducts. The technique accounts for the effects of bulk liners, flexible walls, and mean flow in the airway by describing a variational statement of the dispersion relationship for the propagation of fundamental modes. The variational statement can be applied as a Rayleigh-Ritz finite-element scheme to compute the eigenmodes for these ducts. The approach therefore unifies the computation of the fundamental dispersion relationships and the more complex modes described with high-resolution meshes. The approach is used to describe an experimental test duct without flow, and the Rayleigh-Ritz solution provides results that are similar to those of the full numerical solution. The present treatment is of practical interest to the design and fabrication of silencers and acoustically lined moving ductwork.

  12. Modeling Structural Dynamics of Biomolecular Complexes by Coarse-Grained Molecular Simulations.

    PubMed

    Takada, Shoji; Kanada, Ryo; Tan, Cheng; Terakawa, Tsuyoshi; Li, Wenfei; Kenzaki, Hiroo

    2015-12-15

    Due to hierarchic nature of biomolecular systems, their computational modeling calls for multiscale approaches, in which coarse-grained (CG) simulations are used to address long-time dynamics of large systems. Here, we review recent developments and applications of CG modeling methods, focusing on our methods primarily for proteins, DNA, and their complexes. These methods have been implemented in the CG biomolecular simulator, CafeMol. Our CG model has resolution such that ∼10 non-hydrogen atoms are grouped into one CG particle on average. For proteins, each amino acid is represented by one CG particle. For DNA, one nucleotide is simplified by three CG particles, representing sugar, phosphate, and base. The protein modeling is based on the idea that proteins have a globally funnel-like energy landscape, which is encoded in the structure-based potential energy function. We first describe two representative minimal models of proteins, called the elastic network model and the classic Go̅ model. We then present a more elaborate protein model, which extends the minimal model to incorporate sequence and context dependent local flexibility and nonlocal contacts. For DNA, we describe a model developed by de Pablo's group that was tuned to well reproduce sequence-dependent structural and thermodynamic experimental data for single- and double-stranded DNAs. Protein-DNA interactions are modeled either by the structure-based term for specific cases or by electrostatic and excluded volume terms for nonspecific cases. We also discuss the time scale mapping in CG molecular dynamics simulations. While the apparent single time step of our CGMD is about 10 times larger than that in the fully atomistic molecular dynamics for small-scale dynamics, large-scale motions can be further accelerated by two-orders of magnitude with the use of CG model and a low friction constant in Langevin dynamics. Next, we present four examples of applications. First, the classic Go̅ model was used to

  13. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  14. An integrated model for simulating nitrogen trading in an agricultural catchment with complex hydrogeology.

    PubMed

    Cox, T J; Rutherford, J C; Kerr, S C; Smeaton, D C; Palliser, C C

    2013-09-30

    Nitrogen loads to several New Zealand lakes are dominated by nonpoint runoff from pastoral farmland which adversely affects lake water quality. A 'cap and trade' scheme is being considered to help meet targets set for nitrogen loads to Lake Rotorua, and a numerical model, NTRADER, has been developed to simulate and compare alternative schemes. NTRADER models both the geophysics of nitrogen generation and transport, including groundwater lag times, and the economics of 'cap and trade' schemes. It integrates the output from several existing models, including a farm-scale nitrogen leaching and abatement model, a farm-scale management economic model, and a catchment-scale nitrogen transport model. This paper details modeling methods and compares possible trading program design features for the Lake Rotorua catchment. Model simulations demonstrate how a cap and trade program could be used to effectively achieve challenging environmental goals in the targeted catchment. However, results also show that, due to complex hydrogeology, satisfactory environmental outcomes may be not achieved unless groundwater lag times are incorporated into the regulatory scheme. One way to do this, as demonstrated here, would be to explicitly include lag times in the cap and trade program. The utility of the model is further demonstrated by quantifying relative differences in abatement costs across potential regulatory schemes.

  15. POD evaluation using simulation: A phased array UT case on a complex geometry part

    NASA Astrophysics Data System (ADS)

    Dominguez, Nicolas; Reverdy, Frederic; Jenson, Frederic

    2014-02-01

    The use of Probability of Detection (POD) for NDT performances demonstration is a key link in products lifecycle management. The POD approach is to apply the given NDT procedure on a series of known flaws to estimate the probability to detect with respect to the flaw size. A POD is relevant if and only if NDT operations are carried out within the range of variability authorized by the procedure. Such experimental campaigns require collection of large enough datasets to cover the range of variability with sufficient occurrences to build a reliable POD statistics, leading to expensive costs to get POD curves. In the last decade research activities have been led in the USA with the MAPOD group and later in Europe with the SISTAE and PICASSO projects based on the idea to use models and simulation tools to feed POD estimations. This paper proposes an example of application of POD using simulation on the inspection procedure of a complex -full 3D- geometry part using phased arrays ultrasonic testing. It illustrates the methodology and the associated tools developed in the CIVA software. The paper finally provides elements of further progress in the domain.

  16. Simulations of Complex and Microscopic Models of Cardiac Electrophysiology Powered by Multi-GPU Platforms

    PubMed Central

    Gouvêa de Barros, Bruno; Sachetto Oliveira, Rafael; Meira, Wagner; Lobosco, Marcelo; Weber dos Santos, Rodrigo

    2012-01-01

    Key aspects of cardiac electrophysiology, such as slow conduction, conduction block, and saltatory effects have been the research topic of many studies since they are strongly related to cardiac arrhythmia, reentry, fibrillation, or defibrillation. However, to reproduce these phenomena the numerical models need to use subcellular discretization for the solution of the PDEs and nonuniform, heterogeneous tissue electric conductivity. Due to the high computational costs of simulations that reproduce the fine microstructure of cardiac tissue, previous studies have considered tissue experiments of small or moderate sizes and used simple cardiac cell models. In this paper, we develop a cardiac electrophysiology model that captures the microstructure of cardiac tissue by using a very fine spatial discretization (8 μm) and uses a very modern and complex cell model based on Markov chains for the characterization of ion channel's structure and dynamics. To cope with the computational challenges, the model was parallelized using a hybrid approach: cluster computing and GPGPUs (general-purpose computing on graphics processing units). Our parallel implementation of this model using a multi-GPU platform was able to reduce the execution times of the simulations from more than 6 days (on a single processor) to 21 minutes (on a small 8-node cluster equipped with 16 GPUs, i.e., 2 GPUs per node). PMID:23227109

  17. A parallel overset-curvilinear-immersed boundary framework for simulating complex 3D incompressible flows

    PubMed Central

    Borazjani, Iman; Ge, Liang; Le, Trung; Sotiropoulos, Fotis

    2013-01-01

    We develop an overset-curvilinear immersed boundary (overset-CURVIB) method in a general non-inertial frame of reference to simulate a wide range of challenging biological flow problems. The method incorporates overset-curvilinear grids to efficiently handle multi-connected geometries and increase the resolution locally near immersed boundaries. Complex bodies undergoing arbitrarily large deformations may be embedded within the overset-curvilinear background grid and treated as sharp interfaces using the curvilinear immersed boundary (CURVIB) method (Ge and Sotiropoulos, Journal of Computational Physics, 2007). The incompressible flow equations are formulated in a general non-inertial frame of reference to enhance the overall versatility and efficiency of the numerical approach. Efficient search algorithms to identify areas requiring blanking, donor cells, and interpolation coefficients for constructing the boundary conditions at grid interfaces of the overset grid are developed and implemented using efficient parallel computing communication strategies to transfer information among sub-domains. The governing equations are discretized using a second-order accurate finite-volume approach and integrated in time via an efficient fractional-step method. Various strategies for ensuring globally conservative interpolation at grid interfaces suitable for incompressible flow fractional step methods are implemented and evaluated. The method is verified and validated against experimental data, and its capabilities are demonstrated by simulating the flow past multiple aquatic swimmers and the systolic flow in an anatomic left ventricle with a mechanical heart valve implanted in the aortic position. PMID:23833331

  18. Low-cost orbiting grinder for cutting ducts

    NASA Technical Reports Server (NTRS)

    Lang, E. J.

    1970-01-01

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

  19. Do We Know What Causes Bile Duct Cancer?

    MedlinePlus

    ... inflame the bile ducts, whether it’s bile duct stones, infestation with a parasite, or something else. Scientists ... Treatments & Side Effects Cancer Facts & Statistics News and Stories Glossary For Health Care Professionals Programs & Services Breast ...

  20. Higher order mode propagation in nonuniform circular ducts

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Higher order mode propagation in a nonuniform circular duct without mean flow was investigated. 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 referred to as 'circular cosh duct.' Numerical results are presented in terms of the transmission loss for the various duct shapes and frequencies. The results are applicable to multimodal propagation, single mode propagation, and 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.

  1. Higher order mode propagation in nonuniform circular ducts

    NASA Technical Reports Server (NTRS)

    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.

  2. 15. CELLAR. Underside of 1852 duct at east end of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. CELLAR. Underside of 1852 duct at east end of cellar. Note access panel. Note plaster on underside of duct and between joists. - Twelfth Street Meeting House, 20 South Twelfth Street, Philadelphia, Philadelphia County, PA

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

    PubMed

    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.

  4. Should You Have the Air Ducts in Your Home Cleaned?

    EPA Pesticide Factsheets

    Duct cleaning generally refers to the cleaning of various heating and cooling system components of forced air systems, including the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils.

  5. Simulation of Complex Transport of Nanoparticles around a Tumor Using Tumor-Microenvironment-on-Chip

    PubMed Central

    Kwak, Bongseop; Ozcelikkale, Altug; Shin, Crystal S.; Park, Kinam; Han, Bumsoo

    2014-01-01

    Delivery of therapeutic agents selectively to tumor tissue, which is referred as “targeted delivery,” is one of the most ardently pursued goals of cancer therapy. Recent advances in nanotechnology enable numerous types of nanoparticles (NPs) whose properties can be designed for targeted delivery to tumors. In spite of promising early results, the delivery and therapeutic efficacy of the majority of NPs are still quite limited. This is mainly attributed to the limitation of currently available tumor models to test these NPs and systematically study the effects of complex transport and pathophysiological barriers around the tumors. In this study, thus, we developed a new in vitro tumor model to recapitulate the tumor microenvironment determining the transport around tumors. This model, named tumor-microenvironment-on-chip (T-MOC), consists of 3-dimensional microfluidic channels where tumor cells and endothelial cells are cultured within extracellular matrix under perfusion of interstitial fluid. Using this T-MOC platform, the transport of NPs and its variation due to tumor microenvironmental parameters have been studied including cut-off pore size, interstitial fluid pressure, and tumor tissue microstructure. The results suggest that T-MOC is capable of simulating the complex transport around the tumor, and providing detailed information about NP transport behavior. This finding confirms that NPs should be designed considering their dynamic interactions with tumor microenvironment. PMID:25194778

  6. Simulated two-dimensional electronic spectroscopy of the eight-bacteriochlorophyll FMO complex

    SciTech Connect

    Yeh, Shu-Hao; Kais, Sabre

    2014-12-21

    The Fenna-Matthews-Olson (FMO) protein-pigment complex acts as a molecular wire conducting energy between the outer antenna system and the reaction center; it is an important photosynthetic system to study the transfer of excitonic energy. Recent crystallographic studies report the existence of an additional (eighth) bacteriochlorophyll a (BChl a) in some of the FMO monomers. To understand the functionality of this eighth BChl, we simulated the two-dimensional electronic spectra of both the 7-site (apo form) and the 8-site (holo form) variant of the FMO complex from green sulfur bacteria, Prosthecochloris aestuarii. By comparing the spectrum, it was found that the eighth BChl can affect two different excitonic energy transfer pathways: (1) it is directly involved in the first apo form pathway (6 → 3 → 1) by passing the excitonic energy to exciton 6; and (2) it facilitates an increase in the excitonic wave function overlap between excitons 4 and 5 in the second pathway (7 → 4,5 → 2 → 1) and thus increases the possible downward sampling routes across the BChls.

  7. Modeling and Control of a Tailsitter with a Ducted Fan

    NASA Astrophysics Data System (ADS)

    Argyle, Matthew Elliott

    There are two traditional aircraft categories: fixed-wing which have a long endurance and a high cruise airspeed and rotorcraft which can take-off and land vertically. The tailsitter is a type of aircraft that has the strengths of both platforms, with no additional mechanical complexity, because it takes off and lands vertically on its tail and can transition the entire aircraft horizontally into high-speed flight. In this dissertation, we develop the entire control system for a tailsitter with a ducted fan. The standard method to compute the quaternion-based attitude error does not generate ideal trajectories for a hovering tailsitter for some situations. In addition, the only approach in the literature to mitigate this breaks down for large attitude errors. We develop an alternative quaternion-based error method which generates better trajectories than the standard approach and can handle large errors. We also derive a hybrid backstepping controller with almost global asymptotic stability based on this error method. Many common altitude and airspeed control schemes for a fixed-wing airplane assume that the altitude and airspeed dynamics are decoupled which leads to errors. The Total Energy Control System (TECS) is an approach that controls the altitude and airspeed by manipulating the total energy rate and energy distribution rate, of the aircraft, in a manner which accounts for the dynamic coupling. In this dissertation, a nonlinear controller, which can handle inaccurate thrust and drag models, based on the TECS principles is derived. Simulation results show that the nonlinear controller has better performance than the standard PI TECS control schemes. Most constant altitude transitions are accomplished by generating an optimal trajectory, and potentially actuator inputs, based on a high fidelity model of the aircraft. While there are several approaches to mitigate the effects of modeling errors, these do not fully remove the accurate model requirement. In this

  8. A Thorax Simulator for Complex Dynamic Bioimpedance Measurements With Textile Electrodes.

    PubMed

    Ulbrich, Mark; Muhlsteff, Jens; Teichmann, Daniel; Leonhardt, Steffen; Walter, Marian

    2015-06-01

    Bioimpedance measurements on the human thorax are suitable for assessment of body composition or hemodynamic parameters, such as stroke volume; they are non-invasive, easy in application and inexpensive. When targeting personal healthcare scenarios, the technology can be integrated into textiles to increase ease, comfort and coverage of measurements. Bioimpedance is generally measured using two electrodes injecting low alternating currents (0.5-10 mA) and two additional electrodes to measure the corresponding voltage drop. The impedance is measured either spectroscopically (bioimpedance spectroscopy, BIS) between 5 kHz and 1 MHz or continuously at a fixed frequency around 100 kHz (impedance cardiography, ICG). A thorax simulator is being developed for testing and calibration of bioimpedance devices and other new developments. For the first time, it is possible to mimic the complete time-variant properties of the thorax during an impedance measurement. This includes the dynamic real part and dynamic imaginary part of the impedance with a peak-to-peak value of 0.2 Ω and an adjustable base impedance (24.6 Ω ≥ Z0 ≥ 51.6 Ω). Another novelty is adjustable complex electrode-skin contact impedances for up to 8 electrodes to evaluate bioimpedance devices in combination with textile electrodes. In addition, an electrocardiographic signal is provided for cardiographic measurements which is used in ICG devices. This provides the possibility to generate physiologic impedance changes, and in combination with an ECG, all parameters of interest such as stroke volume (SV), pre-ejection period (PEP) or extracellular resistance (Re) can be simulated. The speed of all dynamic signals can be altered. The simulator was successfully tested with commercially available BIS and ICG devices and the preset signals are measured with high correlation (r = 0.996).

  9. Complex Spine Pathology Simulator: An Innovative Tool for Advanced Spine Surgery Training.

    PubMed

    Gragnaniello, Cristian; Abou-Hamden, Amal; Mortini, Pietro; Colombo, Elena V; Bailo, Michele; Seex, Kevin A; Litvack, Zachary; Caputy, Anthony J; Gagliardi, Filippo

    2016-11-01

    Background Technical advancements in spine surgery have made possible the treatment of increasingly complex pathologies with less morbidity. Time constraints in surgeons' training have made it necessary to develop new training models for spine pathology. Objective To describe the application of a novel compound, Stratathane resin ST-504 derived polymer (SRSDP), that can be injected at different spinal target locations to mimic spinal epidural, subdural extra-axial, and intra-axial pathologies for the use in advanced surgical training. Material and Methods Fresh-frozen thoracolumbar and cervical spine segments of human and sheep cadavers were used to study the model. SRSDP is initially liquid after mixing, allowing it to be injected into target areas where it expands and solidifies, mimicking the entire spectrum of spinal pathologies. Results Different polymer concentrations have been codified to vary adhesiveness, texture, spread capability, deformability, and radiologic visibility. Polymer injection was performed under fluoroscopic guidance through pathology-specific injection sites that avoided compromising the surgical approach for subsequent excision of the artificial lesion. Inflation of a balloon catheter of the desired size was used to displace stiff cadaveric neurovascular structures to mimic pathology-related mass effect. Conclusion The traditional cadaveric training models principally only allow surgeons to practice the surgical approach. The complex spine pathology simulator is a novel educational tool that in a user-friendly, low-cost fashion allows trainees to practice advanced technical skills in the removal of complex spine pathology, potentially shortening some of the aspects of the learning curve of operative skills that may otherwise take many years to acquire.

  10. Geant4-DNA simulations using complex DNA geometries generated by the DnaFabric tool

    NASA Astrophysics Data System (ADS)

    Meylan, S.; Vimont, U.; Incerti, S.; Clairand, I.; Villagrasa, C.

    2016-07-01

    Several DNA representations are used to study radio-induced complex DNA damages depending on the approach and the required level of granularity. Among all approaches, the mechanistic one requires the most resolved DNA models that can go down to atomistic DNA descriptions. The complexity of such DNA models make them hard to modify and adapt in order to take into account different biological conditions. The DnaFabric project was started to provide a tool to generate, visualise and modify such complex DNA models. In the current version of DnaFabric, the models can be exported to the Geant4 code to be used as targets in the Monte Carlo simulation. In this work, the project was used to generate two DNA fibre models corresponding to two DNA compaction levels representing the hetero and the euchromatin. The fibres were imported in a Geant4 application where computations were performed to estimate the influence of the DNA compaction on the amount of calculated DNA damage. The relative difference of the DNA damage computed in the two fibres for the same number of projectiles was found to be constant and equal to 1.3 for the considered primary particles (protons from 300 keV to 50 MeV). However, if only the tracks hitting the DNA target are taken into account, then the relative difference is more important for low energies and decreases to reach zero around 10 MeV. The computations were performed with models that contain up to 18,000 DNA nucleotide pairs. Nevertheless, DnaFabric will be extended to manipulate multi-scale models that go from the molecular to the cellular levels.

  11. Propagation of waves of acoustic frequencies in curved ducts

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1973-01-01

    The propagation of waves of acoustic frequencies in curved ducts is studied for the first four modes. The analysis makes use of Bessel functions to construct curves of wave number in the duct versus imposed wave number. The results apply to ducts of arbitrary width and arbitrary radii of curvature. The characteristics of motion in a bend are compared with propagation of waves in a straight duct, and important differences in the behavior of waves are noted.

  12. Recent classifications of the common bile duct injury

    PubMed Central

    2014-01-01

    Laparoscopic cholecystectomy is now a gold standard treatment modality for gallstone diseases. However, the incidence rate of bile duct injury has not been changed for many years. From initial classification published by Bismuth, there have been many classifications of common bile duct injury. The initial classification, levels and types of bile duct injury, and currently combined vascular injuries are reviewed here. PMID:26155253

  13. 14 CFR 23.1103 - Induction system ducts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Induction system ducts. 23.1103 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Induction System § 23.1103 Induction system ducts. (a) Each induction system duct must have a drain to prevent...

  14. Turbofan aft duct suppressor study program listing and user's guide

    NASA Technical Reports Server (NTRS)

    Joshi, M. C.; Kraft, R. E.

    1983-01-01

    A description of the structure of the Annular Flow Duct Program (AFDP) for the calculation of acoustic suppression due to treatment in a finite length annular duct carrying sheared flow is presented. Although most appropriate for engine exhaust ducts, this program can be used to study sound propagation in any duct that maintains annular geometry over a considerable length of the duct. The program is based on the modal analysis of sound propagation in ducts with axial segments of different wall impedances. For specified duct geometry, wall impedance, flow and acoustic conditions in the duct (including mode amplitude distribution of the source) and duct termination reflection characteristics, the program calculates the suppression due to the treatment in the duct. The presence of forward and backward traveling modes in the duct due to the reflection and redistribution of modes at segment interfaces and duct end terminations are taken into account in the calculations. The effects of thin wall boundary layers (with a linear or mean flow velocity profile) on the acoustic propagation are also included in the program. A functional description of the major subroutines is included and a sample run is provided with an explanation of the output.

  15. Whistler waves guided by density depletion ducts in a magnetoplasma

    SciTech Connect

    Bakharev, P. V.; Zaboronkova, T. M.; Kudrin, A. V.; Krafft, C.

    2010-11-15

    The guided propagation of whistler waves along cylindrical density depletion ducts in a magneto-plasma is studied. It is shown that, under certain conditions, such ducts can support volume and surface eigenmodes. The dispersion properties and field structure of whistler modes guided by density depletion ducts are analyzed. The effect of collisional losses in the plasma on the properties of modes is discussed.

  16. Ontogeny of the nasopalatine duct in primates.

    PubMed

    Shimp, Kristin L; Bhatnagar, Kunwar P; Bonar, Christopher J; Smith, Timothy D

    2003-09-01

    Ecological explanations have been put forward to account for the precocious or delayed development of patency in ducts leading to the vomeronasal organ (VNO) in certain mammals. Perinatal function may be related, in part, to the patency or fusion of the vomeronasal and nasopalatine (NPD) ducts. However, few studies have focused on NPD development in primates, which generally have a prolonged period of dependence during infancy. In this study we examined 24 prenatal primates and 13 neonatal primates, and a comparative sample of fetal mice and insectivores. In embryonic and early fetal Microcebus murinus, the NPD was completely fused, whereas in fetuses of later stages the duct was partially fused or completely patent. M. myoxinus of all stages demonstrated some degree of NPD fusion. In all other prenatal primates, the NPD was fused to some extent. Four prenatal insectivores (Tenrec ecaudatus) showed some degree of NPD fusion. In Mus musculus at 19 days gestation, the NPD was patent, although the anatomically separate VNO duct was fused. T. ecaudatus and most of the neonatal primates revealed complete NPD patency. An exception was Saguinus geoffroyi, which exhibited fusion of the NPD near the VNO opening. These observations may relate to differences in perinatal VNO function. The differences noted in our study suggest that M. murinus and M. myoxinus may differ in perinatal VNO functionality and perhaps in related behavior. Observations of neonatal primates suggest that NPD patency may be relatively common at birth and could serve other purposes in addition to being an access route for VNO stimuli.

  17. 46 CFR 116.610 - Ventilation ducts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... side of the boundary. A fire damper blade need not be insulated; and (7) Ducts serving cargo spaces... at least 11 USSG and not more than 3.2 millimeters (0.125 inch) gap between the blade and casing; (2... damper springs, blades, and hinges must be of stainless steel construction or of steel suitably coated...

  18. 46 CFR 116.610 - Ventilation ducts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... side of the boundary. A fire damper blade need not be insulated; and (7) Ducts serving cargo spaces... at least 11 USSG and not more than 3.2 millimeters (0.125 inch) gap between the blade and casing; (2... damper springs, blades, and hinges must be of stainless steel construction or of steel suitably coated...

  19. 46 CFR 116.610 - Ventilation ducts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... side of the boundary. A fire damper blade need not be insulated; and (7) Ducts serving cargo spaces... at least 11 USSG and not more than 3.2 millimeters (0.125 inch) gap between the blade and casing; (2... damper springs, blades, and hinges must be of stainless steel construction or of steel suitably coated...

  20. 46 CFR 116.610 - Ventilation ducts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... side of the boundary. A fire damper blade need not be insulated; and (7) Ducts serving cargo spaces... at least 11 USSG and not more than 3.2 millimeters (0.125 inch) gap between the blade and casing; (2... damper springs, blades, and hinges must be of stainless steel construction or of steel suitably coated...