A Quadtree-gridding LBM with Immersed Boundary for Two-dimension Viscous Flows

Science.gov (United States)

Yao, Jieke; Feng, Wenliang; Chen, Bin; Zhou, Wei; Cao, Shikun

2017-07-01

An un-uniform quadtree grids lattice Boltzmann method (LBM) with immersed boundary is presented in this paper. In overlapping for different level grids, temporal and spatial interpolation are necessary to ensure the continuity of physical quantity. In order to take advantage of the equation for temporal and spatial step in the same level grids, equal interval interpolation, which is simple to apply to any refined boundary grids in the LBM, is adopted in temporal and spatial aspects to obtain second-order accuracy. The velocity correction, which can guarantee more preferably no-slip boundary condition than the direct forcing method and the momentum exchange method in the traditional immersed-boundary LBM, is used for solid boundary to make the best of Cartesian grid. In present quadtree-gridding immersed-boundary LBM, large eddy simulation (LES) is adopted to simulate the flows over obstacle in higher Reynolds number (Re). The incompressible viscous flows over circular cylinder are carried out, and a great agreement is obtained.

A Three-Dimensional, Immersed Boundary, Finite Volume Method for the Simulation of Incompressible Heat Transfer Flows around Complex Geometries

Directory of Open Access Journals (Sweden)

Hassan Badreddine

2017-01-01

Full Text Available The current work focuses on the development and application of a new finite volume immersed boundary method (IBM to simulate three-dimensional fluid flows and heat transfer around complex geometries. First, the discretization of the governing equations based on the second-order finite volume method on Cartesian, structured, staggered grid is outlined, followed by the description of modifications which have to be applied to the discretized system once a body is immersed into the grid. To validate the new approach, the heat conduction equation with a source term is solved inside a cavity with an immersed body. The approach is then tested for a natural convection flow in a square cavity with and without circular cylinder for different Rayleigh numbers. The results computed with the present approach compare very well with the benchmark solutions. As a next step in the validation procedure, the method is tested for Direct Numerical Simulation (DNS of a turbulent flow around a surface-mounted matrix of cubes. The results computed with the present method compare very well with Laser Doppler Anemometry (LDA measurements of the same case, showing that the method can be used for scale-resolving simulations of turbulence as well.

An Immersed Boundary - Adaptive Mesh Refinement solver (IB-AMR) for high fidelity fully resolved wind turbine simulations

Science.gov (United States)

Angelidis, Dionysios; Sotiropoulos, Fotis

2015-11-01

The geometrical details of wind turbines determine the structure of the turbulence in the near and far wake and should be taken in account when performing high fidelity calculations. Multi-resolution simulations coupled with an immersed boundary method constitutes a powerful framework for high-fidelity calculations past wind farms located over complex terrains. We develop a 3D Immersed-Boundary Adaptive Mesh Refinement flow solver (IB-AMR) which enables turbine-resolving LES of wind turbines. The idea of using a hybrid staggered/non-staggered grid layout adopted in the Curvilinear Immersed Boundary Method (CURVIB) has been successfully incorporated on unstructured meshes and the fractional step method has been employed. The overall performance and robustness of the second order accurate, parallel, unstructured solver is evaluated by comparing the numerical simulations against conforming grid calculations and experimental measurements of laminar and turbulent flows over complex geometries. We also present turbine-resolving multi-scale LES considering all the details affecting the induced flow field; including the geometry of the tower, the nacelle and especially the rotor blades of a wind tunnel scale turbine. This material is based upon work supported by the Department of Energy under Award Number DE-EE0005482 and the Sandia National Laboratories.

A stochastic immersed boundary method for fluid-structure dynamics at microscopic length scales

International Nuclear Information System (INIS)

Atzberger, Paul J.; Kramer, Peter R.; Peskin, Charles S.

2007-01-01

In modeling many biological systems, it is important to take into account flexible structures which interact with a fluid. At the length scale of cells and cell organelles, thermal fluctuations of the aqueous environment become significant. In this work, it is shown how the immersed boundary method of [C.S. Peskin, The immersed boundary method, Acta Num. 11 (2002) 1-39.] for modeling flexible structures immersed in a fluid can be extended to include thermal fluctuations. A stochastic numerical method is proposed which deals with stiffness in the system of equations by handling systematically the statistical contributions of the fastest dynamics of the fluid and immersed structures over long time steps. An important feature of the numerical method is that time steps can be taken in which the degrees of freedom of the fluid are completely underresolved, partially resolved, or fully resolved while retaining a good level of accuracy. Error estimates in each of these regimes are given for the method. A number of theoretical and numerical checks are furthermore performed to assess its physical fidelity. For a conservative force, the method is found to simulate particles with the correct Boltzmann equilibrium statistics. It is shown in three dimensions that the diffusion of immersed particles simulated with the method has the correct scaling in the physical parameters. The method is also shown to reproduce a well-known hydrodynamic effect of a Brownian particle in which the velocity autocorrelation function exhibits an algebraic (τ -3/2 ) decay for long times [B.J. Alder, T.E. Wainwright, Decay of the Velocity Autocorrelation Function, Phys. Rev. A 1(1) (1970) 18-21]. A few preliminary results are presented for more complex systems which demonstrate some potential application areas of the method. Specifically, we present simulations of osmotic effects of molecular dimers, worm-like chain polymer knots, and a basic model of a molecular motor immersed in fluid subject to a

Immersed boundary simulation of flow through arterial junctions

Indian Academy of Sciences (India)

Dwaipayan Sarkar

haemodynamic activities in regions like carotid arteries, encephalic regions and ... immersed boundary method (IBM), has gained attention in the last few years .... the flow from left inlet and the flow is subsequently divided among the two ...

Numerical Simulation of Wind Turbine Rotors Autorotation by Using the Modified LS-STAG Immersed Boundary Method

Directory of Open Access Journals (Sweden)

Ilia K. Marchevsky

2017-01-01

Full Text Available A software package is developed for numerical simulation of wind turbine rotors autorotation by using the modified LS-STAG level-set/cut-cell immersed boundary method. The level-set function is used for immersed boundaries description. Algorithm of level-set function construction for complex-shaped airfoils, based on Bézier curves usage, is proposed. Also, algorithm for the level-set function recalculation at any time without reconstructing the Bézier curve for each new rotor position is described. The designed second-order Butterworth low-pass filter for aerodynamic torque filtration for simulations using coarse grids is presented. To verify the modified LS-STAG method, the flow past autorotating Savonius rotor with two blades was simulated at Re=1.96·105.

Curvilinear immersed boundary method for simulating fluid structure interaction with complex 3D rigid bodies

Science.gov (United States)

Borazjani, Iman; Ge, Liang; Sotiropoulos, Fotis

2008-08-01

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 the FSI algorithm is unconditionally unstable 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 FSI

An improved ghost-cell immersed boundary method for compressible flow simulations

KAUST Repository

Chi, Cheng; Lee, Bok Jik; Im, Hong G.

2016-01-01

This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary

A new 3D immersed boundary method for non-Newtonian fluid-structure-interaction with application

Science.gov (United States)

Zhu, Luoding

2017-11-01

Motivated by fluid-structure-interaction (FSI) phenomena in life sciences (e.g., motions of sperm and cytoskeleton in complex fluids), we introduce a new immersed boundary method for FSI problems involving non-Newtonian fluids in three dimensions. The non-Newtonian fluids are modelled by the FENE-P model (including the Oldroyd-B model as an especial case) and numerically solved by a lattice Boltzmann scheme (the D3Q7 model). The fluid flow is modelled by the lattice Boltzmann equations and numerically solved by the D3Q19 model. The deformable structure and the fluid-structure-interaction are handled by the immersed boundary method. As an application, we study a FSI toy problem - interaction of an elastic plate (flapped at its leading edge and restricted nowhere else) with a non-Newtonian fluid in a 3D flow. Thanks to the support of NSF-DMS support under research Grant 1522554.

Unstructured Cartesian refinement with sharp interface immersed boundary method for 3D unsteady incompressible flows

Science.gov (United States)

Angelidis, Dionysios; Chawdhary, Saurabh; Sotiropoulos, Fotis

2016-11-01

A novel numerical method is developed for solving the 3D, unsteady, incompressible Navier-Stokes equations on locally refined fully unstructured Cartesian grids in domains with arbitrarily complex immersed boundaries. Owing to the utilization of the fractional step method on an unstructured Cartesian hybrid staggered/non-staggered grid layout, flux mismatch and pressure discontinuity issues are avoided and the divergence free constraint is inherently satisfied to machine zero. Auxiliary/hanging nodes are used to facilitate the discretization of the governing equations. The second-order accuracy of the solver is ensured by using multi-dimension Lagrange interpolation operators and appropriate differencing schemes at the interface of regions with different levels of refinement. The sharp interface immersed boundary method is augmented with local near-boundary refinement to handle arbitrarily complex boundaries. The discrete momentum equation is solved with the matrix free Newton-Krylov method and the Krylov-subspace method is employed to solve the Poisson equation. The second-order accuracy of the proposed method on unstructured Cartesian grids is demonstrated by solving the Poisson equation with a known analytical solution. A number of three-dimensional laminar flow simulations of increasing complexity illustrate the ability of the method to handle flows across a range of Reynolds numbers and flow regimes. Laminar steady and unsteady flows past a sphere and the oblique vortex shedding from a circular cylinder mounted between two end walls demonstrate the accuracy, the efficiency and the smooth transition of scales and coherent structures across refinement levels. Large-eddy simulation (LES) past a miniature wind turbine rotor, parameterized using the actuator line approach, indicates the ability of the fully unstructured solver to simulate complex turbulent flows. Finally, a geometry resolving LES of turbulent flow past a complete hydrokinetic turbine illustrates

Curvilinear immersed-boundary method for simulating unsteady flows in shallow natural streams with arbitrarily complex obstacles

Science.gov (United States)

Kang, Seokkoo; Borazjani, Iman; Sotiropoulos, Fotis

2008-11-01

Unsteady 3D simulations of flows in natural streams is a challenging task due to the complexity of the bathymetry, the shallowness of the flow, and the presence of multiple nature- and man-made obstacles. This work is motivated by the need to develop a powerful numerical method for simulating such flows using coherent-structure-resolving turbulence models. We employ the curvilinear immersed boundary method of Ge and Sotiropoulos (Journal of Computational Physics, 2007) and address the critical issue of numerical efficiency in large aspect ratio computational domains and grids such as those encountered in long and shallow open channels. We show that the matrix-free Newton-Krylov method for solving the momentum equations coupled with an algebraic multigrid method with incomplete LU preconditioner for solving the Poisson equation yield a robust and efficient procedure for obtaining time-accurate solutions in such problems. We demonstrate the potential of the numerical approach by carrying out a direct numerical simulation of flow in a long and shallow meandering stream with multiple hydraulic structures.

An Improved Ghost-cell Immersed Boundary Method for Compressible Inviscid Flow Simulations

KAUST Repository

Chi, Cheng

2015-01-01

This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary

Modeling of Airfoil Trailing Edge Flap with Immersed Boundary Method

DEFF Research Database (Denmark)

Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær

2011-01-01

The present work considers incompressible flow over a 2D airfoil with a deformable trailing edge. The aerodynamic characteristics of an airfoil with a trailing edge flap is numerically investigated using computational fluid dynamics. A novel hybrid immersed boundary (IB) technique is applied...... to simulate the moving part of the trailing edge. Over the main fixed part of the airfoil the Navier-Stokes (NS) equations are solved using a standard body-fitted finite volume technique whereas the moving trailing edge flap is simulated with the immersed boundary method on a curvilinear mesh. The obtained...... results show that the hybrid approach is an efficient and accurate method for solving turbulent flows past airfoils with a trailing edge flap and flow control using trailing edge flap is an efficient way to regulate the aerodynamic loading on airfoils....

Immersed boundary method combined with a high order compact scheme on half-staggered meshes

International Nuclear Information System (INIS)

Księżyk, M; Tyliszczak, A

2014-01-01

This paper presents the results of computations of incompressible flows performed with a high-order compact scheme and the immersed boundary method. The solution algorithm is based on the projection method implemented using the half-staggered grid arrangement in which the velocity components are stored in the same locations while the pressure nodes are shifted half a cell size. The time discretization is performed using the predictor-corrector method in which the forcing terms used in the immersed boundary method acts in both steps. The solution algorithm is verified based on 2D flow problems (flow in a lid-driven skewed cavity, flow over a backward facing step) and turns out to be very accurate on computational meshes comparable with ones used in the classical approaches, i.e. not based on the immersed boundary method.

An efficient strongly coupled immersed boundary method for deforming bodies

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Goza, Andres; Colonius, Tim

2016-11-01

Immersed boundary methods treat the fluid and immersed solid with separate domains. As a result, a nonlinear interface constraint must be satisfied when these methods are applied to flow-structure interaction problems. This typically results in a large nonlinear system of equations that is difficult to solve efficiently. Often, this system is solved with a block Gauss-Seidel procedure, which is easy to implement but can require many iterations to converge for small solid-to-fluid mass ratios. Alternatively, a Newton-Raphson procedure can be used to solve the nonlinear system. This typically leads to convergence in a small number of iterations for arbitrary mass ratios, but involves the use of large Jacobian matrices. We present an immersed boundary formulation that, like the Newton-Raphson approach, uses a linearization of the system to perform iterations. It therefore inherits the same favorable convergence behavior. However, we avoid large Jacobian matrices by using a block LU factorization of the linearized system. We derive our method for general deforming surfaces and perform verification on 2D test problems of flow past beams. These test problems involve large amplitude flapping and a wide range of mass ratios. This work was partially supported by the Jet Propulsion Laboratory and Air Force Office of Scientific Research.

Porous Media and Immersed Boundary Hybrid-Modelling for Simulating Flow in Stone Cover-Layers

DEFF Research Database (Denmark)

Jensen, Bjarne; Liu, Xiaofeng; Christensen, Erik Damgaard

In this paper we present a new numerical modelling approach for coastal and marine applications where a porous media conceptual model was combined with a free surface volume-of-fluid (VOF) model and an immersed boundary method (IBM). The immersed boundary model covers the method of describing....... In this paper, the model is applied to investigate two practical cases in terms of a cover layer of stones on a flat bed under oscillatory flow at different packing densities, and a rock toe structure at a breakwater....

FULL GPU Implementation of Lattice-Boltzmann Methods with Immersed Boundary Conditions for Fast Fluid Simulations

Directory of Open Access Journals (Sweden)

G Boroni

2017-03-01

Full Text Available Lattice Boltzmann Method (LBM has shown great potential in fluid simulations, but performance issues and difficulties to manage complex boundary conditions have hindered a wider application. The upcoming of Graphic Processing Units (GPU Computing offered a possible solution for the performance issue, and methods like the Immersed Boundary (IB algorithm proved to be a flexible solution to boundaries. Unfortunately, the implicit IB algorithm makes the LBM implementation in GPU a non-trivial task. This work presents a fully parallel GPU implementation of LBM in combination with IB. The fluid-boundary interaction is implemented via GPU kernels, using execution configurations and data structures specifically designed to accelerate each code execution. Simulations were validated against experimental and analytical data showing good agreement and improving the computational time. Substantial reductions of calculation rates were achieved, lowering down the required time to execute the same model in a CPU to about two magnitude orders.

An Immersed Boundary Method for Solving the Compressible Navier-Stokes Equations with Fluid Structure Interaction

Science.gov (United States)

Brehm, Christoph; Barad, Michael F.; Kiris, Cetin C.

2016-01-01

An immersed boundary method for the compressible Navier-Stokes equation and the additional infrastructure that is needed to solve moving boundary problems and fully coupled fluid-structure interaction is described. All the methods described in this paper were implemented in NASA's LAVA solver framework. The underlying immersed boundary method is based on the locally stabilized immersed boundary method that was previously introduced by the authors. In the present paper this method is extended to account for all aspects that are involved for fluid structure interaction simulations, such as fast geometry queries and stencil computations, the treatment of freshly cleared cells, and the coupling of the computational fluid dynamics solver with a linear structural finite element method. The current approach is validated for moving boundary problems with prescribed body motion and fully coupled fluid structure interaction problems in 2D and 3D. As part of the validation procedure, results from the second AIAA aeroelastic prediction workshop are also presented. The current paper is regarded as a proof of concept study, while more advanced methods for fluid structure interaction are currently being investigated, such as geometric and material nonlinearities, and advanced coupling approaches.

Simulation of Thermal Flow Problems via a Hybrid Immersed Boundary-Lattice Boltzmann Method

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J. Wu

2012-01-01

Full Text Available A hybrid immersed boundary-lattice Boltzmann method (IB-LBM is presented in this work to simulate the thermal flow problems. In current approach, the flow field is resolved by using our recently developed boundary condition-enforced IB-LBM (Wu and Shu, (2009. The nonslip boundary condition on the solid boundary is enforced in simulation. At the same time, to capture the temperature development, the conventional energy equation is resolved. To model the effect of immersed boundary on temperature field, the heat source term is introduced. Different from previous studies, the heat source term is set as unknown rather than predetermined. Inspired by the idea in (Wu and Shu, (2009, the unknown is calculated in such a way that the temperature at the boundary interpolated from the corrected temperature field accurately satisfies the thermal boundary condition. In addition, based on the resolved temperature correction, an efficient way to compute the local and average Nusselt numbers is also proposed in this work. As compared with traditional implementation, no approximation for temperature gradients is required. To validate the present method, the numerical simulations of forced convection are carried out. The obtained results show good agreement with data in the literature.

Stability Analysis of Algebraic Reconstruction for Immersed Boundary Methods with Application in Flow and Transport in Porous Media

Science.gov (United States)

Yousefzadeh, M.; Battiato, I.

2017-12-01

Flow and reactive transport problems in porous media often involve complex geometries with stationary or evolving boundaries due to absorption and dissolution processes. Grid based methods (e.g. finite volume, finite element, etc.) are a vital tool for studying these problems. Yet, implementing these methods requires one to answer a very first question of what type of grid is to be used. Among different possible answers, Cartesian grids are one of the most attractive options as they possess simple discretization stencil and are usually straightforward to generate at roughly no computational cost. The Immersed Boundary Method, a Cartesian based methodology, maintains most of the useful features of the structured grids while exhibiting a high-level resilience in dealing with complex geometries. These features make it increasingly more attractive to model transport in evolving porous media as the cost of grid generation reduces greatly. Yet, stability issues and severe time-step restriction due to explicit-time implementation combined with limited studies on the implementation of Neumann (constant flux) and linear and non-linear Robin (e.g. reaction) boundary conditions (BCs) have significantly limited the applicability of IBMs to transport in porous media. We have developed an implicit IBM capable of handling all types of BCs and addressed some numerical issues, including unconditional stability criteria, compactness and reduction of spurious oscillations near the immersed boundary. We tested the method for several transport and flow scenarios, including dissolution processes in porous media, and demonstrate its capabilities. Successful validation against both experimental and numerical data has been carried out.

An immersed boundary method for modeling a dirty geometry data

Science.gov (United States)

Onishi, Keiji; Tsubokura, Makoto

2017-11-01

We present a robust, fast, and low preparation cost immersed boundary method (IBM) for simulating an incompressible high Re flow around highly complex geometries. The method is achieved by the dispersion of the momentum by the axial linear projection and the approximate domain assumption satisfying the mass conservation around the wall including cells. This methodology has been verified against an analytical theory and wind tunnel experiment data. Next, we simulate the problem of flow around a rotating object and demonstrate the ability of this methodology to the moving geometry problem. This methodology provides the possibility as a method for obtaining a quick solution at a next large scale supercomputer. This research was supported by MEXT as ``Priority Issue on Post-K computer'' (Development of innovative design and production processes) and used computational resources of the K computer provided by the RIKEN Advanced Institute for Computational Science.

Boundaries immersed in a scalar quantum field

International Nuclear Information System (INIS)

Actor, A.A.; Bender, I.

1996-01-01

We study the interaction between a scalar quantum field φ(x), and many different boundary configurations constructed from (parallel and orthogonal) thin planar surfaces on which φ(x) is constrained to vanish, or to satisfy Neumann conditions. For most of these boundaries the Casimir problem has not previously been investigated. We calculate the canonical and improved vacuum stress tensors left angle T μv (x) right angle and left angle direct difference μv (x) right angle of φ(x) for each example. From these we obtain the local Casimir forces on all boundary planes. For massless fields, both vacuum stress tensors yield identical attractive local Casimir forces in all Dirichlet examples considered. This desirable outcome is not a priori obvious, given the quite different features of left angle T μv (x) right angle and left angle direct difference μv (x) right angle. For Neumann conditions, left angle T μv (x) right angle and left angle direct difference μv (x) right angle lead to attractive Casimir stresses which are not always the same. We also consider Dirichlet and Neumann boundaries immersed in a common scalar quantum field, and find that these repel. The extensive catalogue of worked examples presented here belongs to a large class of completely solvable Casimir problems. Casimir forces previously unknown are predicted, among them ones which might be measurable. (orig.)

A fast immersed boundary method for external incompressible viscous flows using lattice Green's functions

Science.gov (United States)

Liska, Sebastian; Colonius, Tim

2017-02-01

A new parallel, computationally efficient immersed boundary method for solving three-dimensional, viscous, incompressible flows on unbounded domains is presented. Immersed surfaces with prescribed motions are generated using the interpolation and regularization operators obtained from the discrete delta function approach of the original (Peskin's) immersed boundary method. Unlike Peskin's method, boundary forces are regarded as Lagrange multipliers that are used to satisfy the no-slip condition. The incompressible Navier-Stokes equations are discretized on an unbounded staggered Cartesian grid and are solved in a finite number of operations using lattice Green's function techniques. These techniques are used to automatically enforce the natural free-space boundary conditions and to implement a novel block-wise adaptive grid that significantly reduces the run-time cost of solutions by limiting operations to grid cells in the immediate vicinity and near-wake region of the immersed surface. These techniques also enable the construction of practical discrete viscous integrating factors that are used in combination with specialized half-explicit Runge-Kutta schemes to accurately and efficiently solve the differential algebraic equations describing the discrete momentum equation, incompressibility constraint, and no-slip constraint. Linear systems of equations resulting from the time integration scheme are efficiently solved using an approximation-free nested projection technique. The algebraic properties of the discrete operators are used to reduce projection steps to simple discrete elliptic problems, e.g. discrete Poisson problems, that are compatible with recent parallel fast multipole methods for difference equations. Numerical experiments on low-aspect-ratio flat plates and spheres at Reynolds numbers up to 3700 are used to verify the accuracy and physical fidelity of the formulation.

Discrete Lattice effect of various forcing methods of body force on immersed Boundary-Lattice Boltzmann method

Energy Technology Data Exchange (ETDEWEB)

Son, Sung Wan; Ha, Man Yeong; Yoon, Hyun Sik [Pusan National University, Busan (Korea, Republic of); Jeong, Hae Kwon [POSCO, Pohang (Korea, Republic of); Balachandar, S. [University of Florida, Florida (United States)

2013-02-15

We investigate the discrete lattice effect of various forcing methods in the lattice Boltzmann method (LBM) to include the body force obtained from the immersed boundary method (IBM). In the immersed boundary lattice Boltzmann method (IB-LBM), the LBM needs a forcing method to involve the body force on a forcing point near the immersed boundary that is calculated by IBM. The proper forcing method in LBM is derived to include the body force, which appears to resolve problems such as multiphase flow, non-ideal gas behavior, etc. Many researchers have adopted different forcing methods in LBM to involve the body force from IBM, even when they solved similar problems. However, it is necessary to evaluate the discrete lattice effect, which originates from different forcing methods in LBM, to include the effect of the body force from IBM on the results. Consequently, in this study, a rigorous analysis of the discrete lattice effect for different forcing methods in IB-LBM is performed by solving various problems.

Discrete Lattice effect of various forcing methods of body force on immersed Boundary-Lattice Boltzmann method

International Nuclear Information System (INIS)

Son, Sung Wan; Ha, Man Yeong; Yoon, Hyun Sik; Jeong, Hae Kwon; Balachandar, S.

2013-01-01

We investigate the discrete lattice effect of various forcing methods in the lattice Boltzmann method (LBM) to include the body force obtained from the immersed boundary method (IBM). In the immersed boundary lattice Boltzmann method (IB-LBM), the LBM needs a forcing method to involve the body force on a forcing point near the immersed boundary that is calculated by IBM. The proper forcing method in LBM is derived to include the body force, which appears to resolve problems such as multiphase flow, non-ideal gas behavior, etc. Many researchers have adopted different forcing methods in LBM to involve the body force from IBM, even when they solved similar problems. However, it is necessary to evaluate the discrete lattice effect, which originates from different forcing methods in LBM, to include the effect of the body force from IBM on the results. Consequently, in this study, a rigorous analysis of the discrete lattice effect for different forcing methods in IB-LBM is performed by solving various problems.

Numerical simulation of two-dimensional flows over a circular cylinder using the immersed boundary method

International Nuclear Information System (INIS)

Lima E Silva, A.L.F.; Silveira-Neto, A.; Damasceno, J.J.R.

2003-01-01

In this work, a virtual boundary method is applied to the numerical simulation of a uniform flow over a cylinder. The force source term, added to the two-dimensional Navier-Stokes equations, guarantees the imposition of the no-slip boundary condition over the body-fluid interface. These equations are discretized, using the finite differences method. The immersed boundary is represented with a finite number of Lagrangian points, distributed over the solid-fluid interface. A Cartesian grid is used to solve the fluid flow equations. The key idea is to propose a method to calculate the interfacial force without ad hoc constants that should usually be adjusted for the type of flow and the type of the numerical method, when this kind of model is used. In the present work, this force is calculated using the Navier-Stokes equations applied to the Lagrangian points and then distributed over the Eulerian grid. The main advantage of this approach is that it enables calculation of this force field, even if the interface is moving or deforming. It is unnecessary to locate the Eulerian grid points near this immersed boundary. The lift and drag coefficients and the Strouhal number, calculated for an immersed cylinder, are compared with previous experimental and numerical results, for different Reynolds numbers

Taylor-Couette fluid flow with force oscillation in the inner-cylinder using the immersed boundary method

Energy Technology Data Exchange (ETDEWEB)

Borges, Jonatas Emmanuel; Lourenco, Marcos Antonio de Souza; Padilla, Elie Luis Martinez; Silveira Neto, Aristeu da [Federal University of Uberlandia , MG (Brazil)], e-mails: lourenco@mecanica.ufu.br, epadilla@mecanica.ufu.br, aristeus@mecanica.ufu.br; Leibsohn, Andre Martins [CENPES/Petrobras, Rio de Janeiro, RJ (Brazil)], e-mail: aleibsohn@petrobras.com

2010-07-01

As new challenges arise in the exploration of deep and ultra-deep water oil fields by PETROBRAS more knowledge and research are needed, so that tools could be developed to assist in the critical operations and make things practicable. In the context of the drilling process, the complexity of the fluid flow inside the riser is associated with the nature of the non-Newtonian flow, immersed solid particles, variable eccentricity and the superimposed traveling azimuthal waves on the inflow and outflow boundaries of the Taylor vortices. This work presents the numerical three-dimensional results of the following simplified fluid flows: Taylor-Couette, Taylor-Couette with varying imposed eccentricity and Taylor-Couette with forced oscillation in the inner cylinder. Using the Navier-Stokes equations, a finite volume method discretization with second order accuracy in both time and space was utilized to simulate the Newtonian, single-phase incompressible fluid flow in the three cases. The circular walls of the inner and outer cylinders are represented by the immersed boundary method, with the direct multi-forcing model. The determined results allow to evidence the flow structures in the three cases in a very qualitative way, even so in the presence of the inner cylinder oscillation. (author)

A Newton-Krylov method with approximate Jacobian for implicit solution of Navier-Stokes on staggered overset-curvilinear grids with immersed boundaries

Science.gov (United States)

Asgharzadeh, Hafez; Borazjani, Iman

2014-11-01

Time step-size restrictions and low convergence rates are major bottle necks for implicit solution of the Navier-Stokes in simulations involving complex geometries with moving boundaries. Newton-Krylov method (NKM) is a combination of a Newton-type method for super-linearly convergent solution of nonlinear equations and Krylov subspace methods for solving the Newton correction equations, which can theoretically address both bottle necks. The efficiency of this method vastly depends on the Jacobian forming scheme e.g. automatic differentiation is very expensive and Jacobian-free methods slow down as the mesh is refined. A novel, computationally efficient analytical Jacobian for NKM was developed to solve unsteady incompressible Navier-Stokes momentum equations on staggered curvilinear grids with immersed boundaries. The NKM was validated and verified against Taylor-Green vortex and pulsatile flow in a 90 degree bend and efficiently handles complex geometries such as an intracranial aneurysm with multiple overset grids, pulsatile inlet flow and immersed boundaries. The NKM method is shown to be more efficient than the semi-implicit Runge-Kutta methods and Jabobian-free Newton-Krylov methods. We believe NKM can be applied to many CFD techniques to decrease the computational cost. This work was supported partly by the NIH Grant R03EB014860, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

On deformation of complex continuum immersed in a plane space

Science.gov (United States)

Kovalev, V. A.; Murashkin, E. V.; Radayev, Y. N.

2018-05-01

The present paper is devoted to mathematical modelling of complex continua deformations considered as immersed in an external plane space. The complex continuum is defined as a differential manifold supplied with metrics induced by the external space. A systematic derivation of strain tensors by notion of isometric immersion of the complex continuum into a plane space of a higher dimension is proposed. Problem of establishing complete systems of irreducible objective strain and extrastrain tensors for complex continuum immersed in an external plane space is resolved. The solution to the problem is obtained by methods of the field theory and the theory of rational algebraic invariants. Strain tensors of the complex continuum are derived as irreducible algebraic invariants of contravariant vectors of the external space emerging as functional arguments in the complex continuum action density. Present analysis is restricted to rational algebraic invariants. Completeness of the considered systems of rational algebraic invariants is established for micropolar elastic continua. Rational syzygies for non-quadratic invariants are discussed. Objective strain tensors (indifferent to frame rotations in the external plane space) for micropolar continuum are alternatively obtained by properly combining multipliers of polar decompositions of deformation and extra-deformation gradients. The latter is realized only for continua immersed in a plane space of the equal mathematical dimension.

A minimally-resolved immersed boundary model for reaction-diffusion problems

OpenAIRE

Pal Singh Bhalla, A; Griffith, BE; Patankar, NA; Donev, A

2013-01-01

We develop an immersed boundary approach to modeling reaction-diffusion processes in dispersions of reactive spherical particles, from the diffusion-limited to the reaction-limited setting. We represent each reactive particle with a minimally-resolved "blob" using many fewer degrees of freedom per particle than standard discretization approaches. More complicated or more highly resolved particle shapes can be built out of a collection of reactive blobs. We demonstrate numerically that the blo...

Strongly Coupled Fluid-Body Dynamics in the Immersed Boundary Projection Method

Science.gov (United States)

Wang, Chengjie; Eldredge, Jeff D.

2014-11-01

A computational algorithm is developed to simulate dynamically coupled interaction between fluid and rigid bodies. The basic computational framework is built upon a multi-domain immersed boundary method library, whirl, developed in previous work. In this library, the Navier-Stokes equations for incompressible flow are solved on a uniform Cartesian grid by the vorticity-based immersed boundary projection method of Colonius and Taira. A solver for the dynamics of rigid-body systems is also included. The fluid and rigid-body solvers are strongly coupled with an iterative approach based on the block Gauss-Seidel method. Interfacial force, with its intimate connection with the Lagrange multipliers used in the fluid solver, is used as the primary iteration variable. Relaxation, developed from a stability analysis of the iterative scheme, is used to achieve convergence in only 2-4 iterations per time step. Several two- and three-dimensional numerical tests are conducted to validate and demonstrate the method, including flapping of flexible wings, self-excited oscillations of a system of linked plates and three-dimensional propulsion of flexible fluked tail. This work has been supported by AFOSR, under Award FA9550-11-1-0098.

The boundary data immersion method for compressible flows with application to aeroacoustics

Energy Technology Data Exchange (ETDEWEB)

Schlanderer, Stefan C., E-mail: stefan.schlanderer@unimelb.edu.au [Faculty for Engineering and the Environment, University of Southampton, SO17 1BJ Southampton (United Kingdom); Weymouth, Gabriel D., E-mail: G.D.Weymouth@soton.ac.uk [Faculty for Engineering and the Environment, University of Southampton, SO17 1BJ Southampton (United Kingdom); Sandberg, Richard D., E-mail: richard.sandberg@unimelb.edu.au [Department of Mechanical Engineering, University of Melbourne, Melbourne VIC 3010 (Australia)

2017-03-15

This paper introduces a virtual boundary method for compressible viscous fluid flow that is capable of accurately representing moving bodies in flow and aeroacoustic simulations. The method is the compressible extension of the boundary data immersion method (BDIM, Maertens & Weymouth (2015), ). The BDIM equations for the compressible Navier–Stokes equations are derived and the accuracy of the method for the hydrodynamic representation of solid bodies is demonstrated with challenging test cases, including a fully turbulent boundary layer flow and a supersonic instability wave. In addition we show that the compressible BDIM is able to accurately represent noise radiation from moving bodies and flow induced noise generation without any penalty in allowable time step.

IB2d: a Python and MATLAB implementation of the immersed boundary method.

Science.gov (United States)

Battista, Nicholas A; Strickland, W Christopher; Miller, Laura A

2017-03-29

The development of fluid-structure interaction (FSI) software involves trade-offs between ease of use, generality, performance, and cost. Typically there are large learning curves when using low-level software to model the interaction of an elastic structure immersed in a uniform density fluid. Many existing codes are not publicly available, and the commercial software that exists usually requires expensive licenses and may not be as robust or allow the necessary flexibility that in house codes can provide. We present an open source immersed boundary software package, IB2d, with full implementations in both MATLAB and Python, that is capable of running a vast range of biomechanics models and is accessible to scientists who have experience in high-level programming environments. IB2d contains multiple options for constructing material properties of the fiber structure, as well as the advection-diffusion of a chemical gradient, muscle mechanics models, and artificial forcing to drive boundaries with a preferred motion.

Simulation of hypersonic rarefied flows with the immersed-boundary method

Science.gov (United States)

Bruno, D.; De Palma, P.; de Tullio, M. D.

2011-05-01

This paper provides a validation of an immersed boundary method for computing hypersonic rarefied gas flows. The method is based on the solution of the Navier-Stokes equation and is validated versus numerical results obtained by the DSMC approach. The Navier-Stokes solver employs a flexible local grid refinement technique and is implemented on parallel machines using a domain-decomposition approach. Thanks to the efficient grid generation process, based on the ray-tracing technique, and the use of the METIS software, it is possible to obtain the partitioned grids to be assigned to each processor with a minimal effort by the user. This allows one to by-pass the expensive (in terms of time and human resources) classical generation process of a body fitted grid. First-order slip-velocity boundary conditions are employed and tested for taking into account rarefied gas effects.

Survey and research of the latest works of LES about models near wall boundary and applications to complex flow path

International Nuclear Information System (INIS)

Sakai, Norio; Shimizu, Takeshi

2005-02-01

Since treatments for wall boundaries and flows around complex paths are issues in LES modeling, a literature research on the LES methods for wall boundaries and applications to flows at complex paths was conducted to investigate the latest trend. Publications of domestic or international societies, workshops, symposiums, and journals about for past 3 years (2001-2004) were searched and collected, from which 23 research papers were selected and investigated. For the investigation, the treatments for wall boundaries used in the literature were classified roughly into five methods, i.e. (1) no-slip condition, (2) algebraic wall model (wall function), (3) wall model based on boundary-layer approximations (differential equation wall model), (4) hybrid method, (5) immersed boundary method. No-slip conditions were widely applied in recent works. For algebraic wall models, new wall functions that considered the effect of the velocity component vertical to a wall or circulation regions were examined. There were also some researches that devised the process of calculating the wall-shear stress with a conventional wall function. The researches using differential equation wall models presented the dynamic modification of model coefficients, or the application of high-order turbulence model such as the k-e model to the solution of Navier-Stokes equation in the boundary layer. The researches of hybrid methods focused on the discontinuity of velocity and eddy viscosity at the LES/RANS interface. Several researches that adopted immersed boundary methods for Cartesian girds with curved wall boundaries introduced the investigation of the Poisson solvers and the numerical modification of pressure boundary conditions. Many of investigated researches used hybrid methods. Thus, it is expected that they will be mainly applied to large-scale and complex simulations if the standard treatment for the discontinuity at the interface is developed. (author)

Numerical analysis of the immersed boundary method applied to the flow around a forced oscillating cylinder

International Nuclear Information System (INIS)

Pinto, L C; Silvestrini, J H; Schettini, E B C

2011-01-01

In present paper, Navier-Stokes and Continuity equations for incompressible flow around an oscillating cylinder were numerically solved. Sixth order compact difference schemes were used to solve the spatial derivatives, while the time advance was carried out through second order Adams Bashforth accurate scheme. In order to represent the obstacle in the flow, the Immersed Boundary Method was adopted. In this method a force term is added to the Navier-Stokes equations representing the body. The simulations present results regarding the hydrodynamic coefficients and vortex wakes in agreement to experimental and numerical previous works and the physical lock-in phenomenon was identified. Comparing different methods to impose the IBM, it can be concluded that no alterations regarding the vortex shedding mode were observed. The Immersed Boundary Method techniques used here can represent the surface of an oscillating cylinder in the flow.

An immersed boundary method for the interaction of turbulence with particles of arbitrary shape

Science.gov (United States)

Wang, Shizhao; Vanella, Marcos; Balaras, Elias

2014-11-01

In this work we present a computational scheme applicable to turbulence/particle interactions, targeting applications involving millions of particles of arbitrary shape. Immersed boundary methods have been frequently applied in simulating such problems, but are usually confined to spherical particles. Extension to rigid/deformable particles of arbitrary shape introduces significant challenges in achieving parallel efficiency. The proposed method is based on the moving least squares immersed boundary approach (Vanella & Balaras, J. Comput. Physics, 228(18), 6617, 2009) on uniform and adaptive block-structured grids. We will present a novel parallelization strategy based on a master/slave model: the processor on which a body/structure resides is designated the master processor, while all the processors that contain at least one block overlapping with the body are designated the slaves. As the particle moves through the fluid, its blocks association and therefore the participating processors change. Effective ways of replicating the mesh metadata on all processors will be discussed. Results for homogeneous turbulence interacting with spherical and ellipsoidal particles and comparisons with experimental results will be given.

Non-Newtonian particulate flow simulation: A direct-forcing immersed boundary-lattice Boltzmann approach

Science.gov (United States)

Amiri Delouei, A.; Nazari, M.; Kayhani, M. H.; Kang, S. K.; Succi, S.

2016-04-01

In the current study, a direct-forcing immersed boundary-non-Newtonian lattice Boltzmann method (IB-NLBM) is developed to investigate the sedimentation and interaction of particles in shear-thinning and shear-thickening fluids. In the proposed IB-NLBM, the non-linear mechanics of non-Newtonian particulate flows is detected by combination of the most desirable features of immersed boundary and lattice Boltzmann methods. The noticeable roles of non-Newtonian behavior on particle motion, settling velocity and generalized Reynolds number are investigated by simulating benchmark problem of one-particle sedimentation under the same generalized Archimedes number. The effects of extra force due to added accelerated mass are analyzed on the particle motion which have a significant impact on shear-thinning fluids. For the first time, the phenomena of interaction among the particles, such as Drafting, Kissing, and Tumbling in non-Newtonian fluids are investigated by simulation of two-particle sedimentation and twelve-particle sedimentation. The results show that increasing the shear-thickening behavior of fluid leads to a significant increase in the kissing time. Moreover, the transverse position of particles for shear-thinning fluids during the tumbling interval is different from Newtonian and the shear-thickening fluids. The present non-Newtonian particulate study can be applied in several industrial and scientific applications, like the non-Newtonian sedimentation behavior of particles in food industrial and biological fluids.

An improved ghost-cell immersed boundary method for compressible flow simulations

KAUST Repository

Chi, Cheng

2016-05-20

This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary described using a level-set method to farther image points, incorporating a higher-order extra/interpolation scheme for the ghost cell values. A sensor is introduced to deal with image points near the discontinuities in the flow field. Adaptive mesh refinement (AMR) is used to improve the representation of the geometry efficiently in the Cartesian grid system. The improved ghost-cell method is validated against four test cases: (a) double Mach reflections on a ramp, (b) smooth Prandtl-Meyer expansion flows, (c) supersonic flows in a wind tunnel with a forward-facing step, and (d) supersonic flows over a circular cylinder. It is demonstrated that the improved ghost-cell method can reach the accuracy of second order in L1 norm and higher than first order in L∞ norm. Direct comparisons against the cut-cell method demonstrate that the improved ghost-cell method is almost equally accurate with better efficiency for boundary representation in high-fidelity compressible flow simulations. Copyright © 2016 John Wiley & Sons, Ltd.

A second-order coupled immersed boundary-SAMR construction for chemically reacting flow over a heat-conducting Cartesian grid-conforming solid

KAUST Repository

Kedia, Kushal S.; Safta, Cosmin; Ray, Jaideep; Najm, Habib N.; Ghoniem, Ahmed F.

2014-01-01

In this paper, we present a second-order numerical method for simulations of reacting flow around heat-conducting immersed solid objects. The method is coupled with a block-structured adaptive mesh refinement (SAMR) framework and a low-Mach number operator-split projection algorithm. A "buffer zone" methodology is introduced to impose the solid-fluid boundary conditions such that the solver uses symmetric derivatives and interpolation stencils throughout the interior of the numerical domain; irrespective of whether it describes fluid or solid cells. Solid cells are tracked using a binary marker function. The no-slip velocity boundary condition at the immersed wall is imposed using the staggered mesh. Near the immersed solid boundary, single-sided buffer zones (inside the solid) are created to resolve the species discontinuities, and dual buffer zones (inside and outside the solid) are created to capture the temperature gradient discontinuities. The development discussed in this paper is limited to a two-dimensional Cartesian grid-conforming solid. We validate the code using benchmark simulations documented in the literature. We also demonstrate the overall second-order convergence of our numerical method. To demonstrate its capability, a reacting flow simulation of a methane/air premixed flame stabilized on a channel-confined bluff-body using a detailed chemical kinetics model is discussed. © 2014 Elsevier Inc.

A second-order coupled immersed boundary-SAMR construction for chemically reacting flow over a heat-conducting Cartesian grid-conforming solid

KAUST Repository

Kedia, Kushal S.

2014-09-01

In this paper, we present a second-order numerical method for simulations of reacting flow around heat-conducting immersed solid objects. The method is coupled with a block-structured adaptive mesh refinement (SAMR) framework and a low-Mach number operator-split projection algorithm. A "buffer zone" methodology is introduced to impose the solid-fluid boundary conditions such that the solver uses symmetric derivatives and interpolation stencils throughout the interior of the numerical domain; irrespective of whether it describes fluid or solid cells. Solid cells are tracked using a binary marker function. The no-slip velocity boundary condition at the immersed wall is imposed using the staggered mesh. Near the immersed solid boundary, single-sided buffer zones (inside the solid) are created to resolve the species discontinuities, and dual buffer zones (inside and outside the solid) are created to capture the temperature gradient discontinuities. The development discussed in this paper is limited to a two-dimensional Cartesian grid-conforming solid. We validate the code using benchmark simulations documented in the literature. We also demonstrate the overall second-order convergence of our numerical method. To demonstrate its capability, a reacting flow simulation of a methane/air premixed flame stabilized on a channel-confined bluff-body using a detailed chemical kinetics model is discussed. © 2014 Elsevier Inc.

Some recent developments of the immersed interface method for flow simulation

Science.gov (United States)

Xu, Sheng

2017-11-01

The immersed interface method is a general methodology for solving PDEs subject to interfaces. In this talk, I will give an overview of some recent developments of the method toward the enhancement of its robustness for flow simulation. In particular, I will present with numerical results how to capture boundary conditions on immersed rigid objects, how to adopt interface triangulation in the method, and how to parallelize the method for flow with moving objects. With these developments, the immersed interface method can achieve accurate and efficient simulation of a flow involving multiple moving complex objects. Thanks to NSF for the support of this work under Grant NSF DMS 1320317.

An immersed-boundary method for conjugate heat transfer analysis

Energy Technology Data Exchange (ETDEWEB)

Song, Jeong Chul; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of); Ahn, Joon [Kookmin University, Seoul (Korea, Republic of)

2017-05-15

An immersed-boundary method is proposed for the analysis of conjugate problems of convective heat transfer in conducting solids. In- side the solid body, momentum forcing is applied to set the velocity to zero. A thermal conductivity ratio and a heat capacity ratio, between the solid body and the fluid, are introduced so that the energy equation is reduced to the heat diffusion equation. At the solid fluid interface, an effective conductivity is introduced to satisfy the heat flux continuity. The effective thermal conductivity is obtained by considering the heat balance at the interface or by using a harmonic mean formulation. The method is first validated against the analytic solution to the heat transfer problem in a fully developed laminar channel flow with conducting solid walls. Then it is applied to a laminar channel flow with a heated, block-shaped obstacle to show its validity for geometry with sharp edges. Finally the validation for a curvilinear solid body is accomplished with a laminar flow through arrayed cylinders.

Numerical simulations of conjugate convection combined with surface thermal radiation using an Immersed-Boundary Method

International Nuclear Information System (INIS)

Favre, F.; Colomer, G.; Lehmkuhl, O.; Oliva, A.

2016-01-01

Dynamic and thermal interaction problems involving fluids and solids were studied through a finite volume-based Navier-Stokes solver, combined with immersed-boundary techniques and the net radiation method. Source terms were included in the momentum and energy equations to enforce the non-slip condition and the conjugate boundary condition including the radiative heat exchange. Code validation was performed through the simulation of two cases from the literature: conjugate natural convection in a square cavity with a conducting side wall; and a cubical cavity with conducting walls and a heat source. The accuracy of the methodology and the validation of the inclusion of moving bodies into the simulation was performed via a theoretical case (paper)

A highly efficient sharp-interface immersed boundary method with adaptive mesh refinement for bio-inspired flow simulations

Science.gov (United States)

Deng, Xiaolong; Dong, Haibo

2017-11-01

Developing a high-fidelity, high-efficiency numerical method for bio-inspired flow problems with flow-structure interaction is important for understanding related physics and developing many bio-inspired technologies. To simulate a fast-swimming big fish with multiple finlets or fish schooling, we need fine grids and/or a big computational domain, which are big challenges for 3-D simulations. In current work, based on the 3-D finite-difference sharp-interface immersed boundary method for incompressible flows (Mittal et al., JCP 2008), we developed an octree-like Adaptive Mesh Refinement (AMR) technique to enhance the computational ability and increase the computational efficiency. The AMR is coupled with a multigrid acceleration technique and a MPI +OpenMP hybrid parallelization. In this work, different AMR layers are treated separately and the synchronization is performed in the buffer regions and iterations are performed for the convergence of solution. Each big region is calculated by a MPI process which then uses multiple OpenMP threads for further acceleration, so that the communication cost is reduced. With these acceleration techniques, various canonical and bio-inspired flow problems with complex boundaries can be simulated accurately and efficiently. This work is supported by the MURI Grant Number N00014-14-1-0533 and NSF Grant CBET-1605434.

An Improved Ghost-cell Immersed Boundary Method for Compressible Inviscid Flow Simulations

KAUST Repository

Chi, Cheng

2015-05-01

This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary described using a level-set method to farther image points, incorporating a higher-order extra/interpolation scheme for the ghost cell values. In addition, a shock sensor is in- troduced to deal with image points near the discontinuities in the flow field. Adaptive mesh refinement (AMR) is used to improve the representation of the geometry efficiently. The improved ghost-cell method is validated against five test cases: (a) double Mach reflections on a ramp, (b) supersonic flows in a wind tunnel with a forward- facing step, (c) supersonic flows over a circular cylinder, (d) smooth Prandtl-Meyer expansion flows, and (e) steady shock-induced combustion over a wedge. It is demonstrated that the improved ghost-cell method can reach the accuracy of second order in L1 norm and higher than first order in L∞ norm. Direct comparisons against the cut-cell method demonstrate that the improved ghost-cell method is almost equally accurate with better efficiency for boundary representation in high-fidelity compressible flow simulations. Implementation of the improved ghost-cell method in reacting Euler flows further validates its general applicability for compressible flow simulations.

The LS-STAG immersed boundary/cut-cell method for non-Newtonian flows in 3D extruded geometries

Science.gov (United States)

Nikfarjam, F.; Cheny, Y.; Botella, O.

2018-05-01

The LS-STAG method is an immersed boundary/cut-cell method for viscous incompressible flows based on the staggered MAC arrangement for Cartesian grids, where the irregular boundary is sharply represented by its level-set function, results in a significant gain in computer resources (wall time, memory usage) compared to commercial body-fitted CFD codes. The 2D version of LS-STAG method is now well-established (Cheny and Botella, 2010), and this paper presents its extension to 3D geometries with translational symmetry in the z direction (hereinafter called 3D extruded configurations). This intermediate step towards the fully 3D implementation can be applied to a wide variety of canonical flows and will be regarded as the keystone for the full 3D solver, since both discretization and implementation issues on distributed memory machines are tackled at this stage of development. The LS-STAG method is then applied to various Newtonian and non-Newtonian flows in 3D extruded geometries (axisymmetric pipe, circular cylinder, duct with an abrupt expansion) for which benchmark results and experimental data are available. The purpose of these investigations are (a) to investigate the formal order of accuracy of the LS-STAG method, (b) to assess the versatility of method for flow applications at various regimes (Newtonian and shear-thinning fluids, steady and unsteady laminar to turbulent flows) (c) to compare its performance with well-established numerical methods (body-fitted and immersed boundary methods).

The Perfectly Matched Layer absorbing boundary for fluid-structure interactions using the Immersed Finite Element Method.

Science.gov (United States)

Yang, Jubiao; Yu, Feimi; Krane, Michael; Zhang, Lucy T

2018-01-01

In this work, a non-reflective boundary condition, the Perfectly Matched Layer (PML) technique, is adapted and implemented in a fluid-structure interaction numerical framework to demonstrate that proper boundary conditions are not only necessary to capture correct wave propagations in a flow field, but also its interacted solid behavior and responses. While most research on the topics of the non-reflective boundary conditions are focused on fluids, little effort has been done in a fluid-structure interaction setting. In this study, the effectiveness of the PML is closely examined in both pure fluid and fluid-structure interaction settings upon incorporating the PML algorithm in a fully-coupled fluid-structure interaction framework, the Immersed Finite Element Method. The performance of the PML boundary condition is evaluated and compared to reference solutions with a variety of benchmark test cases including known and expected solutions of aeroacoustic wave propagation as well as vortex shedding and advection. The application of the PML in numerical simulations of fluid-structure interaction is then investigated to demonstrate the efficacy and necessity of such boundary treatment in order to capture the correct solid deformation and flow field without the requirement of a significantly large computational domain.

The complex variable boundary element method: Applications in determining approximative boundaries

Science.gov (United States)

Hromadka, T.V.

1984-01-01

The complex variable boundary element method (CVBEM) is used to determine approximation functions for boundary value problems of the Laplace equation such as occurs in potential theory. By determining an approximative boundary upon which the CVBEM approximator matches the desired constant (level curves) boundary conditions, the CVBEM is found to provide the exact solution throughout the interior of the transformed problem domain. Thus, the acceptability of the CVBEM approximation is determined by the closeness-of-fit of the approximative boundary to the study problem boundary. ?? 1984.

Is Learning in Low Immersive Environments Carried over to High Immersive Environments?

Directory of Open Access Journals (Sweden)

Dror David Lev

2012-01-01

Full Text Available One of the more debated issues regarding training simulators is their validity for transfer of skills to sensory environments that differ from the simulator. In two experiments, the advantages of three-dimensional (3D and collocated (Col visual displays were evaluated in a realistic and complex visuomotor task. The two factors were evaluated independently, comparing Col-2D with dislocated-2D (experiment 1 and with Col-3D (experiment 2. As expected, in both cases the more immersive presentation condition facilitated better performance. Furthermore, improvement following training in the more immersive condition carried over to the following less immersive condition but there was no carry over in the opposing order of presentation. This is taken as an indication for the differential development of skills conditioned by the level of immersiveness of the training environment. This further suggests that learning of complex realistic tasks is not carried over from less immersive simulator to the complex sensory environment of reality, due to the large gap in sensory patterns.

Domain Immersion Technique And Free Surface Computations Applied To Extrusion And Mixing Processes

Science.gov (United States)

Valette, Rudy; Vergnes, Bruno; Basset, Olivier; Coupez, Thierry

2007-04-01

This work focuses on the development of numerical techniques devoted to the simulation of mixing processes of complex fluids such as twin-screw extrusion or batch mixing. In mixing process simulation, the absence of symmetry of the moving boundaries (the screws or the rotors) implies that their rigid body motion has to be taken into account by using a special treatment. We therefore use a mesh immersion technique (MIT), which consists in using a P1+/P1-based (MINI-element) mixed finite element method for solving the velocity-pressure problem and then solving the problem in the whole barrel cavity by imposing a rigid motion (rotation) to nodes found located inside the so called immersed domain, each subdomain (screw, rotor) being represented by a surface CAD mesh (or its mathematical equation in simple cases). The independent meshes are immersed into a unique backgound computational mesh by computing the distance function to their boundaries. Intersections of meshes are accounted for, allowing to compute a fill factor usable as for the VOF methodology. This technique, combined with the use of parallel computing, allows to compute the time-dependent flow of generalized Newtonian fluids including yield stress fluids in a complex system such as a twin screw extruder, including moving free surfaces, which are treated by a "level set" and Hamilton-Jacobi method.

Animal imaging using immersion

Science.gov (United States)

Kalogerakis, Konstantinos S.; Kotz, Kenneth T.; Rand, Kendra; Faris, Gregory W.

2003-07-01

We are using rodent animal models to study and compare contrast mechanisms for detection of breast cancer. These measurements are performed with the animals immersed in a matching scattering medium. The matching scattering medium or liquid tissue phantom comprises a mixture of Ropaque (hollow acrylic/styrene microspheres) and ink. We have previously applied matched imaging to imaging in humans. Surrounding the imaged region with a matched tissue phantom compensates for variations in tissue thickness and geometry, provides more uniform illumination, and allows better use of the dynamic range of the imaging system. If the match is good, the boundaries of the imaged region should almost vanish, enhancing the contrast from internal structure as compared to contrast from the boundaries and surface topography. For our measurements in animals, the immersion plays two additional roles. First, we can readily study tumors through tissue thickness similar to that of a human breast. Although the heterogeneity of the breast is lost, this is a practical method to study the detection of small tumors and monitor changes as they grow. Second, the immersion enhances our ability to quantify the contrast mechanisms for peripheral tumors on the animal because the boundary effects on photon migration are eliminated. We are currently developing two systems for these measurements. One is a continuous-wave (CW) system based on near-infrared LED illumination and a CCD (charge-coupled device) camera. The second system, a frequency domain system, can help quantify the changes observed with the CW system.

An efficient immersed boundary-lattice Boltzmann method for the hydrodynamic interaction of elastic filaments

Science.gov (United States)

Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Liao, James C.; Lu, Xi-Yun

2012-01-01

We have introduced a modified penalty approach into the flow-structure interaction solver that combines an immersed boundary method (IBM) and a multi-block lattice Boltzmann method (LBM) to model an incompressible flow and elastic boundaries with finite mass. The effect of the solid structure is handled by the IBM in which the stress exerted by the structure on the fluid is spread onto the collocated grid points near the boundary. The fluid motion is obtained by solving the discrete lattice Boltzmann equation. The inertial force of the thin solid structure is incorporated by connecting this structure through virtual springs to a ghost structure with the equivalent mass. This treatment ameliorates the numerical instability issue encountered in this type of problems. Thanks to the superior efficiency of the IBM and LBM, the overall method is extremely fast for a class of flow-structure interaction problems where details of flow patterns need to be resolved. Numerical examples, including those involving multiple solid bodies, are presented to verify the method and illustrate its efficiency. As an application of the present method, an elastic filament flapping in the Kármán gait and the entrainment regions near a cylinder is studied to model fish swimming in these regions. Significant drag reduction is found for the filament, and the result is consistent with the metabolic cost measured experimentally for the live fish. PMID:23564971

An efficient immersed boundary-lattice Boltzmann method for the hydrodynamic interaction of elastic filaments

Science.gov (United States)

Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Liao, James C.; Lu, Xi-Yun

2011-08-01

We have introduced a modified penalty approach into the flow-structure interaction solver that combines an immersed boundary method (IBM) and a multi-block lattice Boltzmann method (LBM) to model an incompressible flow and elastic boundaries with finite mass. The effect of the solid structure is handled by the IBM in which the stress exerted by the structure on the fluid is spread onto the collocated grid points near the boundary. The fluid motion is obtained by solving the discrete lattice Boltzmann equation. The inertial force of the thin solid structure is incorporated by connecting this structure through virtual springs to a ghost structure with the equivalent mass. This treatment ameliorates the numerical instability issue encountered in this type of problems. Thanks to the superior efficiency of the IBM and LBM, the overall method is extremely fast for a class of flow-structure interaction problems where details of flow patterns need to be resolved. Numerical examples, including those involving multiple solid bodies, are presented to verify the method and illustrate its efficiency. As an application of the present method, an elastic filament flapping in the Kármán gait and the entrainment regions near a cylinder is studied to model fish swimming in these regions. Significant drag reduction is found for the filament, and the result is consistent with the metabolic cost measured experimentally for the live fish.

An immersed boundary-lattice Boltzmann model for biofilm growth and its impact on the NAPL dissolution in porous media

Science.gov (United States)

Benioug, M.; Yang, X.

2017-12-01

The evolution of microbial phase within porous medium is a complex process that involves growth, mortality, and detachment of the biofilm or attachment of moving cells. A better understanding of the interactions among biofilm growth, flow and solute transport and a rigorous modeling of such processes are essential for a more accurate prediction of the fate of pollutants (e.g. NAPLs) in soils. However, very few works are focused on the study of such processes in multiphase conditions (oil/water/biofilm systems). Our proposed numerical model takes into account the mechanisms that control bacterial growth and its impact on the dissolution of NAPL. An Immersed Boundary - Lattice Boltzmann Model (IB-LBM) is developed for flow simulations along with non-boundary conforming finite volume methods (volume of fluid and reconstruction methods) used for reactive solute transport. A sophisticated cellular automaton model is also developed to describe the spatial distribution of bacteria. A series of numerical simulations have been performed on complex porous media. A quantitative diagram representing the transitions between the different biofilm growth patterns is proposed. The bioenhanced dissolution of NAPL in the presence of biofilms is simulated at the pore scale. A uniform dissolution approach has been adopted to describe the temporal evolution of trapped blobs. Our simulations focus on the dissolution of NAPL in abiotic and biotic conditions. In abiotic conditions, we analyze the effect of the spatial distribution of NAPL blobs on the dissolution rate under different assumptions (blobs size, Péclet number). In biotic conditions, different conditions are also considered (spatial distribution, reaction kinetics, toxicity) and analyzed. The simulated results are consistent with those obtained from the literature.

Numerical Simulation of Flows about a Stationary and a Free-Falling Cylinder Using Immersed Boundary-Finite Difference Lattice Boltzmann Method

Directory of Open Access Journals (Sweden)

Roberto Rojas

2013-03-01

Full Text Available The applicability of the immersed boundary-finite difference lattice Boltzmann method (IB-FDLBM to high Reynolds number flows about a circular cylinder is examined. Two-dimensional simulations of flows past a stationary circular cylinder are carried out for a wide range of the Reynolds number, Re, i.e., 1 ≤ Re ≤ 1×105. An immersed boundary-lattice Boltzmann method (IB-LBM is also used for comparison. Then free-falling circular cylinders are simulated to demonstrate the feasibility of predicting moving particles at high Reynolds numbers. The main conclusions obtained are as follows: (1 steady and unsteady flows about a stationary cylinder are well predicted with IB-LBM and IB-FDLBM, provided that the spatial resolution is high enough to satisfy the conditions of numerical stability, (2 high spatial resolution is required for stable IB-LBM simulation of high Reynolds number flows, (3 IB-FDLBM can stably simulate flows at very high Reynolds numbers without increasing the spatial resolution, (4 IB-FDLBM gives reasonable predictions of the drag coefficient for 1 ≤ Re ≤ 1×105, and (5 IB-FDLBM gives accurate predictions for the motion of free-falling cylinders at intermediate Reynolds numbers.

Immersion freezing of ice nucleation active protein complexes

Directory of Open Access Journals (Sweden)

S. Hartmann

2013-06-01

Full Text Available Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS, the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between −5 °C to −38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about −6 °C to about −10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice

A two-dimensional embedded-boundary method for convection problems with moving boundaries

NARCIS (Netherlands)

Y.J. Hassen (Yunus); B. Koren (Barry)

2010-01-01

htmlabstractIn this work, a two-dimensional embedded-boundary algorithm for convection problems is presented. A moving body of arbitrary boundary shape is immersed in a Cartesian finite-volume grid, which is fixed in space. The boundary surface is reconstructed in such a way that only certain fluxes

A DNS study of jet control with microjets using an immersed boundary method

Science.gov (United States)

Gautier, Rémi; Laizet, Sylvain; Lamballais, Eric

2014-07-01

In this work, a microjet arrangement to control a turbulent jet is studied by means of direct numerical simulation. A customised numerical strategy was developed to investigate the interactions between the microjets and the turbulent jet. This approach is based on an improved immersed boundary method in order to reproduce realistically the control device while being compatible with the accuracy and the parallel strategy of the in-house code Incompact3d. The 16 converging microjets, so-called fluidevrons, lead to an increase of the turbulent kinetic energy in the near-nozzle region through an excitation at small scale caused by the interaction between the fluidevrons and the main jet. As a consequence, very intense unstable ejections are produced from the centre of the jet toward its surrounding. Further downstream, the turbulent kinetic energy levels are lower with a lengthening of the potential core compared to a natural jet, in agreement with experimental results.

A second-order accurate immersed boundary-lattice Boltzmann method for particle-laden flows

Science.gov (United States)

Zhou, Qiang; Fan, Liang-Shih

2014-07-01

A new immersed boundary-lattice Boltzmann method (IB-LBM) is presented for fully resolved simulations of incompressible viscous flows laden with rigid particles. The immersed boundary method (IBM) recently developed by Breugem (2012) [19] is adopted in the present method, development including the retraction technique, the multi-direct forcing method and the direct account of the inertia of the fluid contained within the particles. The present IB-LBM is, however, formulated with further improvement with the implementation of the high-order Runge-Kutta schemes in the coupled fluid-particle interaction. The major challenge to implement high-order Runge-Kutta schemes in the LBM is that the flow information such as density and velocity cannot be directly obtained at a fractional time step from the LBM since the LBM only provides the flow information at an integer time step. This challenge can be, however, overcome as given in the present IB-LBM by extrapolating the flow field around particles from the known flow field at the previous integer time step. The newly calculated fluid-particle interactions from the previous fractional time steps of the current integer time step are also accounted for in the extrapolation. The IB-LBM with high-order Runge-Kutta schemes developed in this study is validated by several benchmark applications. It is demonstrated, for the first time, that the IB-LBM has the capacity to resolve the translational and rotational motion of particles with the second-order accuracy. The optimal retraction distances for spheres and tubes that help the method achieve the second-order accuracy are found to be around 0.30 and -0.47 times of the lattice spacing, respectively. Simulations of the Stokes flow through a simple cubic lattice of rotational spheres indicate that the lift force produced by the Magnus effect can be very significant in view of the magnitude of the drag force when the practical rotating speed of the spheres is encountered. This finding

Numerical study of ship airwake characteristics immersed in atmospheric boundary-layer flow

Science.gov (United States)

Thedin, Regis; Kinzel, Michael; Schmitz, Sven

2017-11-01

Helicopter pilot workload is known to increase substantially in the vicinity of a ship flight deck due to the unsteady flowfield past the superstructure. In this work, the influence of atmospheric turbulence on a ship airwake is investigated. A ship geometry representing the Simple Frigate Shape 2 is immersed into a Large-Eddy-Simulation-resolved Atmospheric Boundary Layer (ABL). Specifically, we aim in identifying the fundamental topology differences between a uniform-inflow model of the incoming wind and those representative of a neutral atmospheric stability state. Thus, airwake characteristics due to a shear-driven ABL are evaluated and compared. Differences in the energy content of the airwakes are identified and discussed. The framework being developed allows for future coupling of flight dynamic models of helicopters to investigate flight envelope testing. Hence, this work represents the first step towards the goal of identifying the effects a modified airwake due to the atmospheric turbulence imposes on the handling of a helicopter and pilot workload. This research was partially supported by the University Graduate Fellowship program at The Pennsylvania State University and by the Government under Agreement No. W911W6-17-2-0003.

Sensitivity analysis of Immersed Boundary Method simulations of fluid flow in dense polydisperse random grain packings

Directory of Open Access Journals (Sweden)

Knight Chris

2017-01-01

Full Text Available Polydisperse granular materials are ubiquitous in nature and industry. Despite this, knowledge of the momentum coupling between the fluid and solid phases in dense saturated grain packings comes almost exclusively from empirical correlations [2–4, 8] with monosized media. The Immersed Boundary Method (IBM is a Computational Fluid Dynamics (CFD modelling technique capable of resolving pore scale fluid flow and fluid-particle interaction forces in polydisperse media at the grain scale. Validation of the IBM in the low Reynolds number, high concentration limit was performed by comparing simulations of flow through ordered arrays of spheres with the boundary integral results of Zick and Homsy [10]. Random grain packings were studied with linearly graded particle size distributions with a range of coefficient of uniformity values (Cu = 1.01, 1.50, and 2.00 at a range of concentrations (ϕ ∈ [0.396; 0.681] in order to investigate the influence of polydispersity on drag and permeability. The sensitivity of the IBM results to the choice of radius retraction parameter [1] was investigated and a comparison was made between the predicted forces and the widely used Ergun correlation [3].

A two pressure-velocity approach for immersed boundary methods in three dimensional incompressible flows

International Nuclear Information System (INIS)

Sabir, O; Ahmad, Norhafizan; Nukman, Y; Tuan Ya, T M Y S

2013-01-01

This paper describes an innovative method for computing fluid solid interaction using Immersed boundary methods with two stage pressure-velocity corrections. The algorithm calculates the interactions between incompressible viscous flows and a solid shape in three-dimensional domain. The fractional step method is used to solve the Navier-Stokes equations in finite difference schemes. Most of IBMs are concern about exchange of the momentum between the Eulerian variables (fluid) and the Lagrangian nodes (solid). To address that concern, a new algorithm to correct the pressure and the velocity using Simplified Marker and Cell method is added. This scheme is applied on staggered grid to simulate the flow past a circular cylinder and study the effect of the new stage on calculations cost. To evaluate the accuracy of the computations the results are compared with the previous software results. The paper confirms the capacity of new algorithm for accurate and robust simulation of Fluid Solid Interaction with respect to pressure field

Immersive CAD

Energy Technology Data Exchange (ETDEWEB)

Ames, A.L.

1999-02-01

This paper documents development of a capability for performing shape-changing editing operations on solid model representations in an immersive environment. The capability includes part- and assembly-level operations, with part modeling supporting topology-invariant and topology-changing modifications. A discussion of various design considerations in developing an immersive capability is included, along with discussion of a prototype implementation we have developed and explored. The project investigated approaches to providing both topology-invariant and topology-changing editing. A prototype environment was developed to test the approaches and determine the usefulness of immersive editing. The prototype showed exciting potential in redefining the CAD interface. It is fun to use. Editing is much faster and friendlier than traditional feature-based CAD software. The prototype algorithms did not reliably provide a sufficient frame rate for complex geometries, but has provided the necessary roadmap for development of a production capability.

Lift generation by a two-dimensional symmetric flapping wing: immersed boundary-lattice Boltzmann simulations

Energy Technology Data Exchange (ETDEWEB)

Ota, Keigo; Suzuki, Kosuke; Inamuro, Takaji, E-mail: inamuro@kuaero.kyoto-u.ac.jp [Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan)

2012-08-01

Two-dimensional (2D) symmetric flapping flight is investigated by an immersed boundary-lattice Boltzmann method (IB-LBM). In this method, we can treat the moving boundary problem efficiently on the Cartesian grid. We consider a model consisting of 2D symmetric flapping wings without mass connected by a hinge with mass. Firstly, we investigate the effect of the Reynolds number in the range of 40-200 on flows around symmetric flapping wings under no gravity field and find that for high Reynolds numbers (Re Greater-Than-Or-Slanted-Equal-To 55), asymmetric vortices with respect to the horizontal line appear and the time-averaged lift force is induced on the wings, whereas for low Reynolds numbers (Re Less-Than-Or-Slanted-Equal-To 50), only symmetric vortices appear around the wings and no lift force is induced. Secondly, the effect of the initial position of the wings is investigated, and the range of the initial phases where the upward flight is possible is found. The effects of the mass and flapping amplitude are also studied. Finally, we carry out free flight simulations under gravity field for various Reynolds numbers in the range 60 Less-Than-Or-Slanted-Equal-To Re Less-Than-Or-Slanted-Equal-To 300 and Froude numbers in the range 3 Less-Than-Or-Slanted-Equal-To Fr Less-Than-Or-Slanted-Equal-To 60 and identify the region where upward flight is possible. (paper)

An implementation of the direct-forcing immersed boundary method using GPU power

Directory of Open Access Journals (Sweden)

Bulent Tutkun

2017-01-01

Full Text Available A graphics processing unit (GPU is utilized to apply the direct-forcing immersed boundary method. The code running on the GPU is generated with the help of the Compute Unified Device Architecture (CUDA. The first and second spatial derivatives of the incompressible Navier-Stokes equations are discretized by the sixth-order central compact finite-difference schemes. Two flow fields are simulated. The first test case is the simulated flow around a square cylinder, with the results providing good estimations of the wake region mechanics and vortex shedding. The second test case is the simulated flow around a circular cylinder. This case was selected to better understand the effects of sharp corners on the force coefficients. It was observed that the estimation of the force coefficients did not result in any troubles in the case of a circular cylinder. Additionally, the performance values obtained for the calculation time for the solution of the Poisson equation are compared with the values for other CPUs and GPUs from the literature. Consequently, approximately 3× and 20× speedups are achieved in comparison with GPU (using CUSP library and CPU, respectively. CUSP is an open-source library for sparse linear algebra and graph computations on CUDA.

The Rufous Hummingbird in hovering flight -- full-body 3D immersed boundary simulation

Science.gov (United States)

Ferreira de Sousa, Paulo; Luo, Haoxiang; Bocanegra Evans, Humberto

2009-11-01

Hummingbirds are an interesting case study for the development of micro-air vehicles since they combine the high flight stability of insects with the low metabolic power per unit of body mass of bats, during hovering flight. In this study, simulations of a full-body hummingbird in hovering flight were performed at a Reynolds number around 3600. The simulations employ a versatile sharp-interface immersed boundary method recently enhanced at our lab that can treat thin membranes and solid bodies alike. Implemented on a Cartesian mesh, the numerical method allows us to capture the vortex dynamics of the wake accurately and efficiently. The whole-body simulation will allow us to clearly identify the three general patterns of flow velocity around the body of the hummingbird referred in Altshuler et al. (Exp Fluids 46 (5), 2009). One focus of the current study is to understand the interaction between the wakes of the two wings at the end of the upstroke, and how the tail actively defects the flow to contribute to pitch stability. Another focus of the study will be to identify the pair of unconnected loops underneath each wing.

Immersive Technology for Human-Centric Cyberphysical Systems in Complex Manufacturing Processes: A Comprehensive Overview of the Global Patent Profile Using Collective Intelligence

Directory of Open Access Journals (Sweden)

Usharani Hareesh Govindarajan

2018-01-01

Full Text Available Immersive technology for human-centric cyberphysical systems includes broad concepts that enable users in the physical world to connect with the cyberworld with a sense of immersion. Complex systems such as virtual reality, augmented reality, brain-computer interfaces, and brain-machine interfaces are emerging as immersive technologies that have the potential for improving manufacturing systems. Industry 4.0 includes all technologies, standards, and frameworks for the fourth industrial revolution to facilitate intelligent manufacturing. Industrial immersive technologies will be used for smart manufacturing innovation in the context of Industry 4.0’s human machine interfaces. This research provides a thorough review of the literature, construction of a domain ontology, presentation of patent metatrend statistical analysis, and data mining analysis using a technology function matrix and highlights technical and functional development trends using latent Dirichlet allocation (LDA models. A total of 179 references from the IEEE and IET databases and 2,672 patents are systematically analyzed to identify current trends. The paper establishes an essential foundation for the development of advanced human-centric cyberphysical systems in complex manufacturing processes.

Functional Requirements for Fab-7 Boundary Activity in the Bithorax Complex

Science.gov (United States)

Wolle, Daniel; Cleard, Fabienne; Aoki, Tsutomu; Deshpande, Girish; Karch, Francois

2015-01-01

Chromatin boundaries are architectural elements that determine the three-dimensional folding of the chromatin fiber and organize the chromosome into independent units of genetic activity. The Fab-7 boundary from the Drosophila bithorax complex (BX-C) is required for the parasegment-specific expression of the Abd-B gene. We have used a replacement strategy to identify sequences that are necessary and sufficient for Fab-7 boundary function in the BX-C. Fab-7 boundary activity is known to depend on factors that are stage specific, and we describe a novel ∼700-kDa complex, the late boundary complex (LBC), that binds to Fab-7 sequences that have insulator functions in late embryos and adults. We show that the LBC is enriched in nuclear extracts from late, but not early, embryos and that it contains three insulator proteins, GAF, Mod(mdg4), and E(y)2. Its DNA binding properties are unusual in that it requires a minimal sequence of >65 bp; however, other than a GAGA motif, the three Fab-7 LBC recognition elements display few sequence similarities. Finally, we show that mutations which abrogate LBC binding in vitro inactivate the Fab-7 boundary in the BX-C. PMID:26303531

Functional Requirements for Fab-7 Boundary Activity in the Bithorax Complex.

Science.gov (United States)

Wolle, Daniel; Cleard, Fabienne; Aoki, Tsutomu; Deshpande, Girish; Schedl, Paul; Karch, Francois

2015-11-01

Chromatin boundaries are architectural elements that determine the three-dimensional folding of the chromatin fiber and organize the chromosome into independent units of genetic activity. The Fab-7 boundary from the Drosophila bithorax complex (BX-C) is required for the parasegment-specific expression of the Abd-B gene. We have used a replacement strategy to identify sequences that are necessary and sufficient for Fab-7 boundary function in the BX-C. Fab-7 boundary activity is known to depend on factors that are stage specific, and we describe a novel ∼700-kDa complex, the late boundary complex (LBC), that binds to Fab-7 sequences that have insulator functions in late embryos and adults. We show that the LBC is enriched in nuclear extracts from late, but not early, embryos and that it contains three insulator proteins, GAF, Mod(mdg4), and E(y)2. Its DNA binding properties are unusual in that it requires a minimal sequence of >65 bp; however, other than a GAGA motif, the three Fab-7 LBC recognition elements display few sequence similarities. Finally, we show that mutations which abrogate LBC binding in vitro inactivate the Fab-7 boundary in the BX-C. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

A second-order accurate immersed boundary-lattice Boltzmann method for particle-laden flows

Energy Technology Data Exchange (ETDEWEB)

Zhou, Qiang; Fan, Liang-Shih, E-mail: fan.1@osu.edu

2014-07-01

A new immersed boundary-lattice Boltzmann method (IB-LBM) is presented for fully resolved simulations of incompressible viscous flows laden with rigid particles. The immersed boundary method (IBM) recently developed by Breugem (2012) [19] is adopted in the present method, development including the retraction technique, the multi-direct forcing method and the direct account of the inertia of the fluid contained within the particles. The present IB-LBM is, however, formulated with further improvement with the implementation of the high-order Runge–Kutta schemes in the coupled fluid–particle interaction. The major challenge to implement high-order Runge–Kutta schemes in the LBM is that the flow information such as density and velocity cannot be directly obtained at a fractional time step from the LBM since the LBM only provides the flow information at an integer time step. This challenge can be, however, overcome as given in the present IB-LBM by extrapolating the flow field around particles from the known flow field at the previous integer time step. The newly calculated fluid–particle interactions from the previous fractional time steps of the current integer time step are also accounted for in the extrapolation. The IB-LBM with high-order Runge–Kutta schemes developed in this study is validated by several benchmark applications. It is demonstrated, for the first time, that the IB-LBM has the capacity to resolve the translational and rotational motion of particles with the second-order accuracy. The optimal retraction distances for spheres and tubes that help the method achieve the second-order accuracy are found to be around 0.30 and −0.47 times of the lattice spacing, respectively. Simulations of the Stokes flow through a simple cubic lattice of rotational spheres indicate that the lift force produced by the Magnus effect can be very significant in view of the magnitude of the drag force when the practical rotating speed of the spheres is encountered

Simulations of two sedimenting-interacting spheres with different sizes and initial configurations using immersed boundary method

Science.gov (United States)

Liao, Chuan-Chieh; Hsiao, Wen-Wei; Lin, Ting-Yu; Lin, Chao-An

2015-06-01

Numerical investigations are carried out for the drafting, kissing and tumbling (DKT) phenomenon of two freely falling spheres within a long container by using an immersed-boundary method. The method is first validated with flows induced by a sphere settling under gravity in a small container for which experimental data are available. The hydrodynamic interactions of two spheres are then studied with different sizes and initial configurations. When a regular sphere is placed below the larger one, the duration of kissing decreases in pace with the increase in diameter ratio. On the other hand, the time duration of the kissing stage increases in tandem with the increase in diameter ratio as the large sphere is placed below the regular one, and there is no DKT interactions beyond threshold diameter ratio. Also, the gap between homogeneous spheres remains constant at the terminal velocity, whereas the gaps between the inhomogeneous spheres increase due to the differential terminal velocity.

A Newton-Krylov method with an approximate analytical Jacobian for implicit solution of Navier-Stokes equations on staggered overset-curvilinear grids with immersed boundaries.

Science.gov (United States)

Asgharzadeh, Hafez; Borazjani, Iman

2017-02-15

The explicit and semi-implicit schemes in flow simulations involving complex geometries and moving boundaries suffer from time-step size restriction and low convergence rates. Implicit schemes can be used to overcome these restrictions, but implementing them to solve the Navier-Stokes equations is not straightforward due to their non-linearity. Among the implicit schemes for nonlinear equations, Newton-based techniques are preferred over fixed-point techniques because of their high convergence rate but each Newton iteration is more expensive than a fixed-point iteration. Krylov subspace methods are one of the most advanced iterative methods that can be combined with Newton methods, i.e., Newton-Krylov Methods (NKMs) to solve non-linear systems of equations. The success of NKMs vastly depends on the scheme for forming the Jacobian, e.g., automatic differentiation is very expensive, and matrix-free methods without a preconditioner slow down as the mesh is refined. A novel, computationally inexpensive analytical Jacobian for NKM is developed to solve unsteady incompressible Navier-Stokes momentum equations on staggered overset-curvilinear grids with immersed boundaries. Moreover, the analytical Jacobian is used to form preconditioner for matrix-free method in order to improve its performance. The NKM with the analytical Jacobian was validated and verified against Taylor-Green vortex, inline oscillations of a cylinder in a fluid initially at rest, and pulsatile flow in a 90 degree bend. The capability of the method in handling complex geometries with multiple overset grids and immersed boundaries is shown by simulating an intracranial aneurysm. It was shown that the NKM with an analytical Jacobian is 1.17 to 14.77 times faster than the fixed-point Runge-Kutta method, and 1.74 to 152.3 times (excluding an intensively stretched grid) faster than automatic differentiation depending on the grid (size) and the flow problem. In addition, it was shown that using only the

A Newton–Krylov method with an approximate analytical Jacobian for implicit solution of Navier–Stokes equations on staggered overset-curvilinear grids with immersed boundaries

Science.gov (United States)

Asgharzadeh, Hafez; Borazjani, Iman

2016-01-01

The explicit and semi-implicit schemes in flow simulations involving complex geometries and moving boundaries suffer from time-step size restriction and low convergence rates. Implicit schemes can be used to overcome these restrictions, but implementing them to solve the Navier-Stokes equations is not straightforward due to their non-linearity. Among the implicit schemes for nonlinear equations, Newton-based techniques are preferred over fixed-point techniques because of their high convergence rate but each Newton iteration is more expensive than a fixed-point iteration. Krylov subspace methods are one of the most advanced iterative methods that can be combined with Newton methods, i.e., Newton-Krylov Methods (NKMs) to solve non-linear systems of equations. The success of NKMs vastly depends on the scheme for forming the Jacobian, e.g., automatic differentiation is very expensive, and matrix-free methods without a preconditioner slow down as the mesh is refined. A novel, computationally inexpensive analytical Jacobian for NKM is developed to solve unsteady incompressible Navier-Stokes momentum equations on staggered overset-curvilinear grids with immersed boundaries. Moreover, the analytical Jacobian is used to form preconditioner for matrix-free method in order to improve its performance. The NKM with the analytical Jacobian was validated and verified against Taylor-Green vortex, inline oscillations of a cylinder in a fluid initially at rest, and pulsatile flow in a 90 degree bend. The capability of the method in handling complex geometries with multiple overset grids and immersed boundaries is shown by simulating an intracranial aneurysm. It was shown that the NKM with an analytical Jacobian is 1.17 to 14.77 times faster than the fixed-point Runge-Kutta method, and 1.74 to 152.3 times (excluding an intensively stretched grid) faster than automatic differentiation depending on the grid (size) and the flow problem. In addition, it was shown that using only the

Fictitious domain methods for elliptic problems with general boundary conditions with an application to the numerical simulation of two phase flows

International Nuclear Information System (INIS)

Ramiere, I.

2006-09-01

This work is dedicated to the introduction of two original fictitious domain methods for the resolution of elliptic problems (mainly convection-diffusion problems) with general and eventually mixed boundary conditions: Dirichlet, Robin or Neumann. The originality lies in the approximation of the immersed boundary by an approximate interface derived from the fictitious domain Cartesian mesh, which is generally not boundary-fitted to the physical domain. The same generic numerical scheme is used to impose the embedded boundary conditions. Hence, these methods require neither a surface mesh of the immersed boundary nor the local modification of the numerical scheme. We study two modelling of the immersed boundary. In the first one, called spread interface, the approximate immersed boundary is the union of the cells crossed by the physical immersed boundary. In the second one, called thin interface, the approximate immersed boundary lies on sides of mesh cells. Additional algebraic transmission conditions linking both flux and solution jumps through the thin approximate interface are introduced. The fictitious problem to solve as well as the treatment of the embedded boundary conditions are detailed for the two methods. A Q1 finite element scheme is implemented for the numerical validation of the spread interface approach while a new cell-centered finite volume scheme is derived for the thin interface approach with immersed jumps. Each method is then combined to multilevel local mesh refinement algorithms (with solution or flux residual) to increase the precision of the solution in the vicinity of the immersed interface. A convergence analysis of a Q1 finite element method with non-boundary fitted meshes is also presented. This study proves the convergence rates of the present methods. Among the various industrial applications, the simulation on a model of heat exchanger in french nuclear power plants enables us to appreciate the performances of the fictitious domain

Effect of Binding Components in Complex Sample Matrices on Recovery in Direct Immersion Solid-Phase Microextraction: Friends or Foe?

Science.gov (United States)

Alam, Md Nazmul; Pawliszyn, Janusz

2018-02-20

The development of matrix compatible coatings for solid-phase microextraction (SPME) has enabled direct extraction of analytes from complex sample matrices. The direct immersion (DI) mode of SPME when utilized in conjunction with such extraction phases facilitates extraction of a wide range of analytes from complex matrices without the incurrence of fouling or coating saturation. In this work, mathematical models and computational simulations were employed to investigate the effect of binding components present in complex samples on the recovery of small molecules varying in logP for extractions carried out using the direct immersion approach. The presented findings corroborate that the studied approach indeed enables the extraction of both polar and nonpolar analytes from complex matrices, provided a suitable sorbent is employed. Further results indicated that, in certain cases, the kinetics of extraction of a given analyte in its free form might be dependent on the desorption kinetics of their bound form from matrix components, which might lower total recoveries of analytes with high affinity for the matrix. However, the binding of analytes to matrix components also enables SPME to extract a balanced quantity of different logP analytes, facilitated by multiphase equilibria, with a single extraction device.

Boundaries of a complex world

CERN Document Server

Ludu, Andrei

2016-01-01

The central theme of this book is the extent to which the structure of the free dynamical boundaries of a system controls the evolution of the system as a whole. Applying three orthogonal types of thinking - mathematical, constructivist and morphological, it illustrates these concepts using applications to selected problems from the social and life sciences, as well as economics. In a broader context, it introduces and reviews some modern mathematical approaches to the science of complex systems. Standard modeling approaches (based on non-linear differential equations, dynamic systems, graph theory, cellular automata, stochastic processes, or information theory) are suitable for studying local problems. However they cannot simultaneously take into account all the different facets and phenomena of a complex system, and new approaches are required to solve the challenging problem of correlations between phenomena at different levels and hierarchies, their self-organization and memory-evolutive aspects, the grow...

Investigation of the flow inside an urban canopy immersed into an atmospheric boundary layer using laser Doppler anemometry

Science.gov (United States)

Herpin, Sophie; Perret, Laurent; Mathis, Romain; Tanguy, Christian; Lasserre, Jean-Jacques

2018-05-01

Laser Doppler anemometry (LDA) is used to investigate the flow inside an idealized urban canopy consisting of a staggered array of cubes with a 25% density immersed into an atmospheric boundary layer with a Reynolds number of δ ^+=32{,}300. The boundary layer thickness to cube height ratio (δ /h=22.7) is large enough to be representative of atmospheric surface layer in neutral conditions. The LDA measurements give access to pointwise time-resolved data at several positions inside the canopy (z=h/4, h/2, and h). Synchronized hot-wire measurements above the canopy (inertial region and roughness sublayer) are also realized to get access to interactions between the different flow regions. The wall-normal mean velocity profile and Reynolds stresses show a good agreement with available data in the literature, although some differences are observed on the standard deviation of the spanwise component. A detailed spectral and integral time scale analysis inside the canopy is then carried out. No clear footprint of a periodic vortex shedding on the sides of the cubes could be identified on the power spectra, owing to the multiple cube-to-cube interactions occuring within a canopy with a building density in the wake interference regime. Results also suggest that interactions between the most energetics scales of the boundary layer and those related to the cube canopy take place, leading to a broadening of the energy peak in the spectra within the canopy. This is confirmed by the analysis of coherence results between the flow inside and above the canopy. It is shown that linear interactions mechanisms are significant, but reduced compared to smooth-wall boundary-layer flow. To our knowledge, this is the first time such results are shown on the dynamics of the flow inside an urban canopy.

Scalable smoothing strategies for a geometric multigrid method for the immersed boundary equations

Energy Technology Data Exchange (ETDEWEB)

Bhalla, Amneet Pal Singh [Univ. of North Carolina, Chapel Hill, NC (United States); Knepley, Matthew G. [Rice Univ., Houston, TX (United States); Adams, Mark F. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Guy, Robert D. [Univ. of California, Davis, CA (United States); Griffith, Boyce E. [Univ. of North Carolina, Chapel Hill, NC (United States)

2016-12-20

The immersed boundary (IB) method is a widely used approach to simulating fluid-structure interaction (FSI). Although explicit versions of the IB method can suffer from severe time step size restrictions, these methods remain popular because of their simplicity and generality. In prior work (Guy et al., Adv Comput Math, 2015), some of us developed a geometric multigrid preconditioner for a stable semi-implicit IB method under Stokes flow conditions; however, this solver methodology used a Vanka-type smoother that presented limited opportunities for parallelization. This work extends this Stokes-IB solver methodology by developing smoothing techniques that are suitable for parallel implementation. Specifically, we demonstrate that an additive version of the Vanka smoother can yield an effective multigrid preconditioner for the Stokes-IB equations, and we introduce an efficient Schur complement-based smoother that is also shown to be effective for the Stokes-IB equations. We investigate the performance of these solvers for a broad range of material stiffnesses, both for Stokes flows and flows at nonzero Reynolds numbers, and for thick and thin structural models. We show here that linear solver performance degrades with increasing Reynolds number and material stiffness, especially for thin interface cases. Nonetheless, the proposed approaches promise to yield effective solution algorithms, especially at lower Reynolds numbers and at modest-to-high elastic stiffnesses.

Using complexity science and negotiation theory to resolve boundary-crossing water issues

Science.gov (United States)

Islam, Shafiqul; Susskind, Lawrence

2018-07-01

Many water governance and management issues are complex. The complexity of these issues is related to crossing of multiple boundaries: political, social and jurisdictional, as well as physical, ecological and biogeochemical. Resolution of these issues usually requires interactions of many parties with conflicting values and interests operating across multiple boundaries and scales to make decisions. The interdependence and feedback among interacting variables, processes, actors and institutions are hard to model and difficult to forecast. Thus, decision-making related to complex water problems needs be contingent and adaptive. This paper draws on a number of ideas from complexity science and negotiation theory that may make it easier to cope with the complexities and difficulties of managing boundary crossing water disputes. It begins with the Water Diplomacy Framework that was developed and tested over the past several years. Then, it uses three key ideas from complexity science (interdependence and interconnectedness; uncertainty and feedback; emergence and adaptation) and three from negotiation theory (stakeholder identification and engagement; joint fact finding; and value creation through option generation) to show how application of these ideas can help enhance effectiveness of water management.

Modeling of the Gecko's skin microfibrillar structures using the Immersed Boundary method via DNS

Science.gov (United States)

Arenas, Isnardo; Carrasquillo, Kenneth; Leonardi, Stefano; Araya, Guillermo; Hussain, Fazle; Castillo, Luciano

2013-11-01

There is a current interest in surfaces that mimic the skin of some species (i.e., sharks, dolphins and geckos) in order to achieve drag reduction. The surface considered is based on the microfribrillar structures of a gecko's skin (Aksak et al. 2008). The structures are modeled by means of the immersed boundary method proposed by Fadlun et al. (2000). Direct simulations are performed to predict flow dynamics with a Reynolds number of 7000 based on the height of the channel and centerline velocity. The ratio of the height of the structure with respect to the height of the channel is approximately 0.05. The main motivation is to study how the microfribillar structures affect the momentum transfer from the viscous layer to the outer layer. The surface shows a reduction of the area affected by the shear stress due to the cavities formed by the pattern. As expected, the cavities create a low velocity zone thus decreasing the Reynolds shear stresses. Lambda-2 and Q-criterion were implemented to identify the elongated streamwise vortices. The results show that when compared to a flat channel the microfribillar structures tend to preserve these streamwise vortices instead of bursting into the outer layer which is a source of drag increase.

A Monotone, Higher-Order Accurate, Fixed-Grid Finite-Volume Method for Advection Problems with Moving Boundaries

NARCIS (Netherlands)

Y.J. Hassen (Yunus); B. Koren (Barry)

2008-01-01

textabstractIn this paper, an accurate method, using a novel immersed-boundary approach, is presented for numerically solving linear, scalar convection problems. As is standard in immersed-boundary methods, moving bodies are embedded in a fixed Cartesian grid. The essence of the present method is

A finite-volume method for convection problems with embedded moving boundaries

NARCIS (Netherlands)

Y.J. Hassen (Yunus); B. Koren (Barry)

2009-01-01

htmlabstractAn accurate method, using a novel immersed-boundary approach, is presented for numerically solving linear, scalar convection problems. Moving interior boundary conditions are embedded in the fixed-grid fluxes in the direct neighborhood of the moving boundaries. Tailor-made limiters are

Piloting and Path Integration within and across Boundaries

Science.gov (United States)

Mou, Weimin; Wang, Lin

2015-01-01

Three experiments investigated whether navigation is less efficient across boundaries than within boundaries. In an immersive virtual environment, participants learned objects' locations in a large room or a small room. Participants then pointed to the objects' original locations after physically walking a circuitous path without vision.…

Numerical simulation of heat transfer in particulate flows using a thermal immersed boundary lattice Boltzmann method

International Nuclear Information System (INIS)

Eshghinejadfard, A.; Thévenin, D.

2016-01-01

In the current work the lattice Boltzmann method (LBM) is applied to investigate heat transfer phenomena in particulate flows. Different cases involving both two- and three-dimensional configurations are studied. For the fluid–particle interactions the direct-forcing and direct-heating immersed boundary (IB) method are applied to calculate the hydrodynamic force and energy exchange between the particle and the fluid, respectively. This Eulerian–Lagrangian approach captures the fluid flow around the particles with high accuracy. The Boussinesq approximation is applied to the coupling between flow and temperature fields. The energy equation is solved using a double-population model in the LBM framework. Numerical simulations reveal that this thermal IB-LBM can accurately predict the particle motion. A particularly interesting case involves particles with a variable temperature, where the competition between gravity and buoyancy induced by the temperature gradient can make particles sink or rise. It is observed that cold particles settle down faster than hot particles. Also, the thermal IB-LBM has been implemented for a collection of spherical particles. In this manner, the behavior of catalyst particles can be accurately predicted, as demonstrated in the last application, involving 60 particles interacting in an enclosure.

Simulation of Moving Trailing Edge Flaps on a Wind Turbine Blade using a Navier-Stokes based Immersed Boundary Method

DEFF Research Database (Denmark)

Behrens, Tim

. Simulations demonstrated the feasibility and robustness of the approach. The hybrid immersed boundary approach proved to be able to handle 3D airfoil sections with span-wise flap gaps. The flow around and in the wake of a deflected flap at a Reynolds number of 1.63mio was investigated for steady inflow......As the rotor diameter of wind turbines increases, turbine blades with distributed aerodynamic control surfaces promise significant load reductions. Therefore, they are coming into focus in relation to research in academia and industry. Trailing edge flaps are of particular interest in terms...... conditions. A control for two span-wise independent flaps was implemented and first load reductions could be achieved. The hybrid method has demonstrated to be a versatile tool in the research of moving trailing edge flaps. The results shall serve as the basis for future investigations of the unsteady flow...

Three Dimensional Plenoptic PIV Measurements of a Turbulent Boundary Layer Overlying a Hemispherical Roughness Element

Science.gov (United States)

Johnson, Kyle; Thurow, Brian; Kim, Taehoon; Blois, Gianluca; Christensen, Kenneth

2016-11-01

Three-dimensional, three-component (3D-3C) measurements were made using a plenoptic camera on the flow around a roughness element immersed in a turbulent boundary layer. A refractive index matched approach allowed whole-field optical access from a single camera to a measurement volume that includes transparent solid geometries. In particular, this experiment measures the flow over a single hemispherical roughness element made of acrylic and immersed in a working fluid consisting of Sodium Iodide solution. Our results demonstrate that plenoptic particle image velocimetry (PIV) is a viable technique to obtaining statistically-significant volumetric velocity measurements even in a complex separated flow. The boundary layer to roughness height-ratio of the flow was 4.97 and the Reynolds number (based on roughness height) was 4.57×103. Our measurements reveal key flow features such as spiraling legs of the shear layer, a recirculation region, and shed arch vortices. Proper orthogonal decomposition (POD) analysis was applied to the instantaneous velocity and vorticity data to extract these features. Supported by the National Science Foundation Grant No. 1235726.

Immersion revisited

DEFF Research Database (Denmark)

Nilsson, Niels Chr.; Nordahl, Rolf; Serafin, Stefania

2016-01-01

of existing definitions of immersion originating within the study of video games, virtual environments, and literary works of fiction. Based on this review, a three-dimensional taxonomy of the various conceptualizations of immersion is proposed. That is, the existing definitions of immersion may be broadly...... divided into three categories, each representing a dimension of the taxonomy: immersion as a property of a system, a subjective response to narrative contents, or a subjective response to challenges within the virtual environment. Finally, four distinct theories of presence are introduced and, based...... on the established taxonomy, we discuss how the individual theories relate to existing definitions of immersion....

Ultra-low friction between boundary layers of hyaluronan-phosphatidylcholine complexes.

Science.gov (United States)

Zhu, Linyi; Seror, Jasmine; Day, Anthony J; Kampf, Nir; Klein, Jacob

2017-09-01

The boundary layers coating articular cartilage in synovial joints constitute unique biomaterials, providing lubricity at levels unmatched by any human-made materials. The underlying molecular mechanism of this lubricity, essential to joint function, is not well understood. Here we study the interactions between surfaces bearing attached hyaluronan (hyaluronic acid, or HA) to which different phosphatidylcholine (PC) lipids had been added, in the form of small unilamellar vesicles (SUVs or liposomes), using a surface force balance, to shed light on possible cartilage boundary lubrication by such complexes. Surface-attached HA was complexed with different PC lipids (hydrogenated soy PC (HSPC), 1,2-dimyristoyl-sn-glycero-3-PC (DMPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-PC (POPC)), followed by rinsing. Atomic force microscopy (AFM) and cryo-scanning electron microscopy (Cryo-SEM) were used to image the HA-PC surface complexes following addition of the SUVs. HA-HSPC complexes provide very efficient lubrication, with friction coefficients as low as μ∼0.001 at physiological pressures P≈150atm, while HA-DMPC and HA-POPC complexes are efficient only at low P (up to 10-20atm). The friction reduction in all cases is attributed to hydration lubrication by highly-hydrated phosphocholine groups exposed by the PC-HA complexes. The greater robustness at high P of the HSPC (C 16(15%) ,C 18(85%) ) complexes relative to the DMPC ((C 14 ) 2 ) or POPC (C 16 , C 18:1 ) complexes is attributed to the stronger van der Waals attraction between the HSPC acyl tails, relative to the shorter or un-saturated tails of the other two lipids. Our results shed light on possible lubrication mechanisms at the articular cartilage surface in joints. Can designed biomaterials emulate the unique lubrication ability of articular cartilage, and thus provide potential alleviation to friction-related joint diseases? This is the motivation behind the present study. The principles of cartilage lubrication

Immersive Learning: Realism, Authenticity & Audience

OpenAIRE

Livingstone, Daniel

2016-01-01

For almost 20 years the Digital Design Studio has been exploring and applying virtual reality for a wide range of industrial, commercial and educational applications. Drawing from a range of recent projects, we explore the complex relationships between realism, authenticity and audience for effective engagement and education in immersive learning.

Remarks on the boundary curve of a constant mean curvature topological disc

DEFF Research Database (Denmark)

Brander, David; Lopéz, Rafael

2017-01-01

We discuss some consequences of the existence of the holomorphic quadratic Hopf differential on a conformally immersed constant mean curvature topological disc with analytic boundary. In particular, we derive a formula for the mean curvature as a weighted average of the normal curvature of the bo......We discuss some consequences of the existence of the holomorphic quadratic Hopf differential on a conformally immersed constant mean curvature topological disc with analytic boundary. In particular, we derive a formula for the mean curvature as a weighted average of the normal curvature...

Lattice Boltzmann methods for moving boundary flows

International Nuclear Information System (INIS)

Inamuro, Takaji

2012-01-01

The lattice Boltzmann methods (LBMs) for moving boundary flows are presented. The LBM for two-phase fluid flows with the same density and the LBM combined with the immersed boundary method are described. In addition, the LBM on a moving multi-block grid is explained. Three numerical examples (a droplet moving in a constricted tube, the lift generation of a flapping wing and the sedimentation of an elliptical cylinder) are shown in order to demonstrate the applicability of the LBMs to moving boundary problems. (invited review)

Lattice Boltzmann methods for moving boundary flows

Energy Technology Data Exchange (ETDEWEB)

Inamuro, Takaji, E-mail: inamuro@kuaero.kyoto-u.ac.jp [Department of Aeronautics and Astronautics, and Advanced Research Institute of Fluid Science and Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan)

2012-04-01

The lattice Boltzmann methods (LBMs) for moving boundary flows are presented. The LBM for two-phase fluid flows with the same density and the LBM combined with the immersed boundary method are described. In addition, the LBM on a moving multi-block grid is explained. Three numerical examples (a droplet moving in a constricted tube, the lift generation of a flapping wing and the sedimentation of an elliptical cylinder) are shown in order to demonstrate the applicability of the LBMs to moving boundary problems. (invited review)

A Numerical Scheme Based on an Immersed Boundary Method for Compressible Turbulent Flows with Shocks: Application to Two-Dimensional Flows around Cylinders

Directory of Open Access Journals (Sweden)

Shun Takahashi

2014-01-01

Full Text Available A computational code adopting immersed boundary methods for compressible gas-particle multiphase turbulent flows is developed and validated through two-dimensional numerical experiments. The turbulent flow region is modeled by a second-order pseudo skew-symmetric form with minimum dissipation, while the monotone upstream-centered scheme for conservation laws (MUSCL scheme is employed in the shock region. The present scheme is applied to the flow around a two-dimensional cylinder under various freestream Mach numbers. Compared with the original MUSCL scheme, the minimum dissipation enabled by the pseudo skew-symmetric form significantly improves the resolution of the vortex generated in the wake while retaining the shock capturing ability. In addition, the resulting aerodynamic force is significantly improved. Also, the present scheme is successfully applied to moving two-cylinder problems.

A parallel implementation of the ghost-cell immersed boundary ...

Indian Academy of Sciences (India)

S Peter

cylinder. Keywords. Taylor series; inverse distance weighting; Neumann boundary condition; ... Kim et al [4], for controlling the production of spurious force ..... continuously increases with a because of the Magnus effect. 7. Conclusions.

In Situ Demonstration and Characteristic Analysis of the Protease Using Substrate Immersing Zymography.

Science.gov (United States)

He, HaiLun; Li, Hao; Liu, Dan

2017-01-01

Zymography, the detection of proteolytic activities on the basis of protein substrate degradation, has been a technique described in the literature for at least in the past 50 years. In this study, we used substrate immersing zymography to analyze proteolysis of proteases. Instead of being directly added into a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel, the substrates were added into the immersing solution after electrophoresis. With substrate immersing zymography, some characters of proteases, such as enzyme forms, potential proteolytic activity, molecular weights, presence of complexes, and potentially active enzyme fragments in complex biological samples, can be determined.

How incorporation of scents could enhance immersive virtual experiences

Directory of Open Access Journals (Sweden)

Matthieu Jeremiah Ischer

2014-07-01

Full Text Available Under normal everyday conditions, senses all work together to create experiences that fill a typical person´s life. Unfortunately for behavioral and cognitive researchers who investigate such experiences, standard laboratory tests are usually conducted in a nondescript room in front of a computer screen. They are very far from replicating the complexity of real world experiences. Recently, immersive virtual reality (IVR environments became promising methods to immerse people into an almost real environment that involves more senses. IVR environments provide many similarities to the complexity of the real world and at the same time allow experimenters to constrain experimental parameters to obtain empirical data. This can eventually lead to better treatment options and/or new mechanistic hypotheses. The idea that increasing sensory modalities improve the realism of immersive virtual reality environments has been empirically supported, but the senses used did not usually include olfaction. In this technology report, we will present an odor delivery system applied to a state-of-the-art IVR technology. The platform provides a three-dimensional, immersive, and fully interactive visualization environment called Brain and Behavioral Laboratory - Immersive System (BBL-IS. The solution we propose can reliably deliver various complex scents during different virtual scenarios, at a precise time and space and without contamination of the environment. The main features of this platform are: i the limited cross-contamination between odorant streams with a fast odor delivery (< 500 ms, ii the ease of use and control, and iii the possibility to synchronize the delivery of the odorant with pictures, videos or sounds. How this unique technology could be used to investigate typical research questions in olfaction (e.g., emotional elicitation, memory encoding or attentional capture by scents will also be addressed.

Headspace versus direct immersion solid phase microextraction in complex matrixes: investigation of analyte behavior in multicomponent mixtures.

Science.gov (United States)

Gionfriddo, Emanuela; Souza-Silva, Érica A; Pawliszyn, Janusz

2015-08-18

This work aims to investigate the behavior of analytes in complex mixtures and matrixes with the use of solid-phase microextraction (SPME). Various factors that influence analyte uptake such as coating chemistry, extraction mode, the physicochemical properties of analytes, and matrix complexity were considered. At first, an aqueous system containing analytes bearing different hydrophobicities, molecular weights, and chemical functionalities was investigated by using commercially available liquid and solid porous coatings. The differences in the mass transfer mechanisms resulted in a more pronounced occurrence of coating saturation in headspace mode. Contrariwise, direct immersion extraction minimizes the occurrence of artifacts related to coating saturation and provides enhanced extraction of polar compounds. In addition, matrix-compatible PDMS-modified solid coatings, characterized by a new morphology that avoids coating fouling, were compared to their nonmodified analogues. The obtained results indicate that PDMS-modified coatings reduce artifacts associated with coating saturation, even in headspace mode. This factor, coupled to their matrix compatibility, make the use of direct SPME very practical as a quantification approach and the best choice for metabolomics studies where wide coverage is intended. To further understand the influence on analyte uptake on a system where additional interactions occur due to matrix components, ex vivo and in vivo sampling conditions were simulated using a starch matrix model, with the aim of mimicking plant-derived materials. Our results corroborate the fact that matrix handling can affect analyte/matrix equilibria, with consequent release of high concentrations of previously bound hydrophobic compounds, potentially leading to coating saturation. Direct immersion SPME limited the occurrence of the artifacts, which confirms the suitability of SPME for in vivo applications. These findings shed light into the implementation of in

Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

DEFF Research Database (Denmark)

Chivaee, Hamid Sarlak; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

2012-01-01

Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM......) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation...... and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically...

Immersed radioactive wastes

International Nuclear Information System (INIS)

2017-03-01

This document presents a brief overview of immersed radioactive wastes worldwide: historical aspects, geographical localization, type of wastes (liquid, solid), radiological activity of immersed radioactive wastes in the NE Atlantic Ocean, immersion sites and monitoring

Enabling immersive simulation.

Energy Technology Data Exchange (ETDEWEB)

McCoy, Josh (University of California Santa Cruz, Santa Cruz, CA); Mateas, Michael (University of California Santa Cruz, Santa Cruz, CA); Hart, Derek H.; Whetzel, Jonathan; Basilico, Justin Derrick; Glickman, Matthew R.; Abbott, Robert G.

2009-02-01

The object of the 'Enabling Immersive Simulation for Complex Systems Analysis and Training' LDRD has been to research, design, and engineer a capability to develop simulations which (1) provide a rich, immersive interface for participation by real humans (exploiting existing high-performance game-engine technology wherever possible), and (2) can leverage Sandia's substantial investment in high-fidelity physical and cognitive models implemented in the Umbra simulation framework. We report here on these efforts. First, we describe the integration of Sandia's Umbra modular simulation framework with the open-source Delta3D game engine. Next, we report on Umbra's integration with Sandia's Cognitive Foundry, specifically to provide for learning behaviors for 'virtual teammates' directly from observed human behavior. Finally, we describe the integration of Delta3D with the ABL behavior engine, and report on research into establishing the theoretical framework that will be required to make use of tools like ABL to scale up to increasingly rich and realistic virtual characters.

Immersive Learning Technologies

Science.gov (United States)

2009-08-20

Immersive Learning Technologies Mr. Peter Smith Lead, ADL Immersive Learning Team 08/20/2009 Report Documentation Page Form ApprovedOMB No. 0704...to 00-00-2009 4. TITLE AND SUBTITLE Immersive Learning Technologies 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR...unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Why Immersive Learning Technologies

A Conceptual Framework of Immersive Shared Environments Emphasizing Social Interaction

Directory of Open Access Journals (Sweden)

Mi Jeong Kim

2015-11-01

Full Text Available The effectiveness of visual displays has often been linked to the sense of presence embodied by immersive visualization. However, efforts analyzing how presence is associated with multi-users’ quality of communication, including visualization capabilities to assist in architecture, engineering and construction (AEC, are still unfolding. This research is an exploratory study on social interaction, which aims to improve the presentation and communication of complex data through immersive simulation techniques. This paper reviews key concepts such as presence and immersion to identify factors that influence communication in the representative literature. It then introduces the Hub for Immersive Visualization and eResearch (HIVE with a focus on the technological components. Finally it presents a conceptual framework of immersive shared environment, which enables multi-users to understand how to implement social interaction in a system efficiently or to determine whether a visualization system could support communication effectively. Future studies to validate the proposed framework are discussed, particularly in the context of cognitive factors in a shared environment.

Immersive video

Science.gov (United States)

Moezzi, Saied; Katkere, Arun L.; Jain, Ramesh C.

1996-03-01

Interactive video and television viewers should have the power to control their viewing position. To make this a reality, we introduce the concept of Immersive Video, which employs computer vision and computer graphics technologies to provide remote users a sense of complete immersion when viewing an event. Immersive Video uses multiple videos of an event, captured from different perspectives, to generate a full 3D digital video of that event. That is accomplished by assimilating important information from each video stream into a comprehensive, dynamic, 3D model of the environment. Using this 3D digital video, interactive viewers can then move around the remote environment and observe the events taking place from any desired perspective. Our Immersive Video System currently provides interactive viewing and `walkthrus' of staged karate demonstrations, basketball games, dance performances, and typical campus scenes. In its full realization, Immersive Video will be a paradigm shift in visual communication which will revolutionize television and video media, and become an integral part of future telepresence and virtual reality systems.

Shear Rheology of a Suspension of Deformable Solids in Viscoelastic Fluid via Immersed Boundary Techniques

Science.gov (United States)

Guido, Christopher; Shaqfeh, Eric

2017-11-01

The simulation of fluids with suspended deformable solids is important to the design of microfluidic devices with soft particles and the examination of blood flow in complex channels. The fluids in these applications are often viscoelastic, motivating the development of a high-fidelity simulation tool with general constitutive model implementations for both the viscoelastic fluid and deformable solid. The Immersed Finite Element Method (IFEM) presented by Zhang et al. (2007) allows for distinct fluid and solid grids to be utilized reducing the need for costly re-meshing when particles translate. We discuss a modified version of the IFEM that allows for the simulation of deformable particles in viscoelastic flows. This simulation tool is validated for simple Newtonian shear flows with elastic particles that obey a Neo-Hookean Law. The tool is used to further explore the rheology of a dilute suspension of Neo-Hookean particles in a Giesekus fluid. The results show that dilute suspensions of soft particles have viscosities that decrease as the Capillary number becomes higher in both the case of a Newtonian and viscoelastic fluid. A discussion of multiple particle results will be included. NSF CBET-1066263 and 1066334.

Immersive 3D geovisualisation in higher education

Science.gov (United States)

Philips, Andrea; Walz, Ariane; Bergner, Andreas; Graeff, Thomas; Heistermann, Maik; Kienzler, Sarah; Korup, Oliver; Lipp, Torsten; Schwanghart, Wolfgang; Zeilinger, Gerold

2014-05-01

Through geovisualisation we explore spatial data, we analyse it towards a specific questions, we synthesise results, and we present and communicate them to a specific audience (MacEachren & Kraak 1997). After centuries of paper maps, the means to represent and visualise our physical environment and its abstract qualities have changed dramatically since the 1990s - and accordingly the methods how to use geovisualisation in teaching. Whereas some people might still consider the traditional classroom as ideal setting for teaching and learning geographic relationships and its mapping, we used a 3D CAVE (computer-animated virtual environment) as environment for a problem-oriented learning project called "GEOSimulator". Focussing on this project, we empirically investigated, if such a technological advance like the CAVE make 3D visualisation, including 3D geovisualisation, not only an important tool for businesses (Abulrub et al. 2012) and for the public (Wissen et al. 2008), but also for educational purposes, for which it had hardly been used yet. The 3D CAVE is a three-sided visualisation platform, that allows for immersive and stereoscopic visualisation of observed and simulated spatial data. We examined the benefits of immersive 3D visualisation for geographic research and education and synthesized three fundamental technology-based visual aspects: First, the conception and comprehension of space and location does not need to be generated, but is instantaneously and intuitively present through stereoscopy. Second, optical immersion into virtual reality strengthens this spatial perception which is in particular important for complex 3D geometries. And third, a significant benefit is interactivity, which is enhanced through immersion and allows for multi-discursive and dynamic data exploration and knowledge transfer. Based on our problem-oriented learning project, which concentrates on a case study on flood risk management at the Wilde Weisseritz in Germany, a river

Validation of the simpleFoam (RANS solver for the atmospheric boundary layer in complex terrain

Directory of Open Access Journals (Sweden)

Peralta C.

2014-01-01

Full Text Available We validate the simpleFoam (RANS solver in OpenFOAM (version 2.1.1 for simulating neutral atmospheric boundary layer flows in complex terrain. Initial and boundary conditions are given using Richards and Hoxey proposal [1]. In order to obtain stable simulation of the ABL, modified wall functions are used to set the near-wall boundary conditions, following Blocken et al remedial measures [2]. A structured grid is generated with the new library terrainBlockMesher [3,4], based on OpenFOAM's blockMesh native mesher. The new tool is capable of adding orographic features and the forest canopy. Additionally, the mesh can be refined in regions with complex orography. We study both the classical benchmark case of Askervein hill [5] and the more recent Bolund island data set [6]. Our purpose is two-folded: to validate the performance of OpenFOAM steady state solvers, and the suitability of the new meshing tool to generate high quality structured meshes, which will be used in the future for performing more computationally intensive LES simulations in complex terrain.

Wave propagation in a piezoelectric solid bar of circular cross-section immersed in fluid

International Nuclear Information System (INIS)

Ponnusamy, P.

2013-01-01

Wave propagation in a piezoelectric solid bar of circular cross-section immersed in fluid is discussed using three-dimensional theory of piezoelectricity. The equations of motion of the cylinder are formulated using the constitutive equations of a piezoelectric material. The equations of motion of the fluid are formulated using the constitutive equations of an inviscid fluid. Three displacement potential functions are introduced to uncouple the equations of motion, electric conduction. The frequency equation of the coupled system consisting of cylinder and fluid is developed under the assumption of perfect-slip boundary conditions at the fluid–solid interfaces. The frequency equations are obtained for longitudinal and flexural modes of vibration and are studied numerically for PZT-4 material bar immersed in fluid. The computed non-dimensional wave numbers are presented in the form of dispersion curves. The secant method is used to obtain the roots of the frequency equation. -- Highlights: ► Wave propagation in a piezoelectric solid bar of circular cross-section immersed in fluid is analyzed using secant method. ► Solid–fluid interaction for piezoelectric material of PZT-4 is analyzed using the boundary conditions. ► The computed non-dimensional wave numbers are plotted in the form of dispersion curves and studied its characters. ► A comparison is made between the non-dimensional wave numbers obtained by the author with the literature results

Fictitious domain methods for elliptic problems with general boundary conditions with an application to the numerical simulation of two phase flows; Methodes de domaine fictif pour des problemes elliptiques avec conditions aux limites generales en vue de la simulation numerique d'ecoulements diphasiques

Energy Technology Data Exchange (ETDEWEB)

Ramiere, I

2006-09-15

This work is dedicated to the introduction of two original fictitious domain methods for the resolution of elliptic problems (mainly convection-diffusion problems) with general and eventually mixed boundary conditions: Dirichlet, Robin or Neumann. The originality lies in the approximation of the immersed boundary by an approximate interface derived from the fictitious domain Cartesian mesh, which is generally not boundary-fitted to the physical domain. The same generic numerical scheme is used to impose the embedded boundary conditions. Hence, these methods require neither a surface mesh of the immersed boundary nor the local modification of the numerical scheme. We study two modelling of the immersed boundary. In the first one, called spread interface, the approximate immersed boundary is the union of the cells crossed by the physical immersed boundary. In the second one, called thin interface, the approximate immersed boundary lies on sides of mesh cells. Additional algebraic transmission conditions linking both flux and solution jumps through the thin approximate interface are introduced. The fictitious problem to solve as well as the treatment of the embedded boundary conditions are detailed for the two methods. A Q1 finite element scheme is implemented for the numerical validation of the spread interface approach while a new cell-centered finite volume scheme is derived for the thin interface approach with immersed jumps. Each method is then combined to multilevel local mesh refinement algorithms (with solution or flux residual) to increase the precision of the solution in the vicinity of the immersed interface. A convergence analysis of a Q1 finite element method with non-boundary fitted meshes is also presented. This study proves the convergence rates of the present methods. Among the various industrial applications, the simulation on a model of heat exchanger in french nuclear power plants enables us to appreciate the performances of the fictitious domain

Learning to manage complexity through simulation: students' challenges and possible strategies.

Science.gov (United States)

Gormley, Gerard J; Fenwick, Tara

2016-06-01

Many have called for medical students to learn how to manage complexity in healthcare. This study examines the nuances of students' challenges in coping with a complex simulation learning activity, using concepts from complexity theory, and suggests strategies to help them better understand and manage complexity.Wearing video glasses, participants took part in a simulation ward-based exercise that incorporated characteristics of complexity. Video footage was used to elicit interviews, which were transcribed. Using complexity theory as a theoretical lens, an iterative approach was taken to identify the challenges that participants faced and possible coping strategies using both interview transcripts and video footage.Students' challenges in coping with clinical complexity included being: a) unprepared for 'diving in', b) caught in an escalating system, c) captured by the patient, and d) unable to assert boundaries of acceptable practice.Many characteristics of complexity can be recreated in a ward-based simulation learning activity, affording learners an embodied and immersive experience of these complexity challenges. Possible strategies for managing complexity themes include: a) taking time to size up the system, b) attuning to what emerges, c) reducing complexity, d) boundary practices, and e) working with uncertainty. This study signals pedagogical opportunities for recognizing and dealing with complexity.

A New Boundary for the High Plains - Ogallala Aquifer Complex

Science.gov (United States)

Haacker, E. M.; Nozari, S.; Kendall, A. D.

2017-12-01

In the semi-arid Great Plains, water is the key ingredient for crop growth: the difference between meager yields for many crops and an agricultural bonanza. The High Plains-Ogallala Aquifer complex (HPA) underlies 452,000 square kilometers of the region, and over 95% of water withdrawn from the aquifer is used for irrigation. Much of the HPA is being pumped unsustainably, and since the region is heavily reliant on this resource for its social and economic health, the High Plains has been a leader in groundwater management planning. However, the geographic boundary of the High Plains region fails to reflect the hydrogeological realities of the aquifer. The current boundary, recognizable from countless textbooks and news articles, is only slightly modified from a version from the 1980's, and largely follows the physiographic borders of the High Plains - defined by surface features such as escarpments and rivers - rather than the edges of water-bearing sediment sufficient for high-volume pumping. This is supported by three lines of evidence: hydrogeological observations from the original aquifer boundary determination; the extent of irrigated land, as estimated by MODIS-MIrAD data; and statistical estimates of saturated thickness, incorporating improved maps of the aquifer base and an additional 35 years of water table measurements. In this project, new maps of saturated thickness are used to create an updated aquifer boundary, which conforms with the standard definition of an aquifer as a package of sediment that yields enough water to be economically pumped. This has major implications for social and physical models, as well as water planning and estimates of sustainability for the HPA. Much of the area of the HPA that has been labeled `sustainable' based upon estimates of recharge relative to pumping estimates falls outside the updated aquifer boundary. In reality, the sustainably-pumped area of this updated aquifer boundary is far smaller—a fact that if more

Stress accumulation and release at complex transform plate boundaries

Energy Technology Data Exchange (ETDEWEB)

Verdonck, D.; Furlong, K.P. (Pennsylvania State Univ., University Park (United States))

1992-10-01

Finite element methods are used to model the dynamics of deformation along complex transform plate boundaries, specifically the San Andreas fault system, California. Effects of mantle rheology and fault geometry on the stress buildup and release are investigated. No prior knowledge of the earthquake cycle time or amount of fault slip is assumed that the results suggest that the San Andreas fault slips at low shear stress (about 15 MPa). Although the maximum stress on the fault is 15 MPa, models with an upper mantle shear zone deforming entirely by dislocation creep accumulate stresses that exceed 100 MPa, a stress level high enough to drive localized dynamic recrystallization and a shift in dominant deformation mechanism to diffusion creep. Models in which the mantle shear zone deform locally by diffusion creep reach a dynamic steady state where lithospheric shear stresses never exceed the specified fault stress anywhere in the model and indicate that the strength of the upper mantle is an important parameter in the dynamics of plate boundary deformation. 17 refs.

Cryogenic immersion microscope

Science.gov (United States)

Le Gros, Mark; Larabell, Carolyn A.

2010-12-14

A cryogenic immersion microscope whose objective lens is at least partially in contact with a liquid reservoir of a cryogenic liquid, in which reservoir a sample of interest is immersed is disclosed. When the cryogenic liquid has an index of refraction that reduces refraction at interfaces between the lens and the sample, overall resolution and image quality are improved. A combination of an immersion microscope and x-ray microscope, suitable for imaging at cryogenic temperatures is also disclosed.

Hovering and targeting flight simulations of a dragonfly-like flapping wing-body model by the immersed boundary-lattice Boltzmann method

Energy Technology Data Exchange (ETDEWEB)

Hirohashi, Kensuke; Inamuro, Takaji, E-mail: inamuro@kuaero.kyoto-u.ac.jp [Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto 615-8540 (Japan)

2017-08-15

Hovering and targeting flights of the dragonfly-like flapping wing-body model are numerically investigated by using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re , the Froude number Fr , and the non-dimensional mass m . We set the parameters at Re = 200, Fr = 15 and m  = 51. First, we simulate free flights of the model for various values of the phase difference angle ϕ between the forewing and the hindwing motions and for various values of the stroke angle β between the stroke plane and the horizontal plane. We find that the vertical motion of the model depends on the phase difference angle ϕ , and the horizontal motion of the model depends on the stroke angle β . Secondly, using the above results we try to simulate the hovering flight by dynamically changing the phase difference angle ϕ and the stroke angle β . The hovering flight can be successfully simulated by a simple proportional controller of the phase difference angle and the stroke angle. Finally, we simulate a targeting flight by dynamically changing the stroke angle β . (paper)

Hovering and targeting flight simulations of a dragonfly-like flapping wing-body model by the immersed boundary-lattice Boltzmann method

International Nuclear Information System (INIS)

Hirohashi, Kensuke; Inamuro, Takaji

2017-01-01

Hovering and targeting flights of the dragonfly-like flapping wing-body model are numerically investigated by using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re , the Froude number Fr , and the non-dimensional mass m . We set the parameters at Re = 200, Fr = 15 and m  = 51. First, we simulate free flights of the model for various values of the phase difference angle ϕ between the forewing and the hindwing motions and for various values of the stroke angle β between the stroke plane and the horizontal plane. We find that the vertical motion of the model depends on the phase difference angle ϕ , and the horizontal motion of the model depends on the stroke angle β . Secondly, using the above results we try to simulate the hovering flight by dynamically changing the phase difference angle ϕ and the stroke angle β . The hovering flight can be successfully simulated by a simple proportional controller of the phase difference angle and the stroke angle. Finally, we simulate a targeting flight by dynamically changing the stroke angle β . (paper)

Low Complexity Connectivity Driven Dynamic Geometry Compression for 3D Tele-Immersion

NARCIS (Netherlands)

R.N. Mekuria (Rufael); D.C.A. Bulterman (Dick); P.S. Cesar Garcia (Pablo Santiago)

2014-01-01

htmlabstractGeometry based 3D Tele-Immersion is a novel emerging media application that involves on the fly reconstructed 3D mesh geometry. To enable real-time communication of such live reconstructed mesh geometry over a bandwidth limited link, fast dynamic geometry compression is needed. However,

Establishing Relationships and Navigating Boundaries When Caring for Children With Medical Complexity at Home.

Science.gov (United States)

Nageswaran, Savithri; Golden, Shannon L

Children with medical complexity receive care from many healthcare providers including home healthcare nurses. The objective of our study, based on a conceptual framework, was to describe the relationships between parents/caregivers of children with medical complexity and home healthcare nurses caring for these children. We collected qualitative data in 20 semistructured in-depth interviews (15 English, 5 Spanish) with 26 primary caregivers of children with medical complexity, and 4 focus groups of 18 home healthcare nurses inquiring about their experiences about home healthcare nursing services for children with medical complexity. During an iterative analysis process, we identified recurrent themes related to caregiver-nurse relationships. Our study showed that: (1) caregiver-nurse relationships evolved over time and were determined by multiple factors; (2) communication and trust were essential to the establishment of caregiver-nurse relationships; (3) both caregivers and nurses described difficulties of navigating physical, professional, personal, and emotional boundaries, and identified strategies to maintain these boundaries; and (4) good caregiver-nurse relationships helped in the care of children with medical complexity, reduced caregiver burden, resulted in less stress for nurses, and was a factor in nurse retention. We conclude that trusted relationships between caregivers and nurses are important to the home care of children with medical complexity. Interventions to develop and maintain good caregiver-nurse relationships are necessary.

Water immersion in preeclampsia.

Science.gov (United States)

Elvan-Taşpinar, Ayten; Franx, Arie; Delprat, Constance C; Bruinse, Hein W; Koomans, Hein A

2006-12-01

Preeclampsia is associated with profound vasoconstriction in most organ systems and reduced plasma volume. Because water immersion produces a marked central redistribution of blood volume and suppresses the renin-angiotensin system response and sympathetic activity, we hypothesized that water immersion might be useful in the treatment of preeclampsia. The effects of thermoneutral water immersion for 3 hours on central and peripheral hemodynamics were evaluated in 7 preeclamptic patients, 7 normal pregnant control patients, and 7 nonpregnant women. Finger plethysmography was used to determine hemodynamic measurements (cardiac output and total peripheral resistance), and forearm blood flow was measured by strain gauge plethysmography. Postischemic hyperemia was used to determine endothelium-dependent vasodilation. Analysis was by analysis of variance for repeated measurements. During water immersion cardiac output increased while diastolic blood pressure and heart rate decreased, although systolic blood pressure remained unchanged in each group. Forearm blood flow increased significantly in the normal pregnant and preeclamptic subjects. Total peripheral resistance decreased in all groups, but values in preeclamptic patients remained above those of normotensive pregnant women. Water immersion had no effect on endothelium-dependent vasodilation in the preeclamptic group, and most hemodynamic changes that were observed reversed to baseline within 2 hours of completion of the procedure. Although water immersion results in hemodynamic alterations in a manner that is theoretically therapeutic for women with preeclampsia, the effect was limited and short-lived. In addition water immersion had no effect on endothelium-dependent vasodilation in women with preeclampsia. The therapeutic potential for water immersion in preeclampsia appears to be limited.

But Do They Speak French? A Comparison of French Immersion Programs in Immersion Only and English/Immersion Settings. Research Report 79-01.

Science.gov (United States)

Parkin, Michael

Students' use of French in unsupervised classroom situations and outside the classroom was investigated in immersion center schools (all students are involved in French immersion programs) and dual track schools (French immersion programs co-exist with regular English language programs). A total of 414 students in grades 3 and 4 were observed…

Constructing IGA-suitable planar parameterization from complex CAD boundary by domain partition and global/local optimization

Science.gov (United States)

Xu, Gang; Li, Ming; Mourrain, Bernard; Rabczuk, Timon; Xu, Jinlan; Bordas, Stéphane P. A.

2018-01-01

In this paper, we propose a general framework for constructing IGA-suitable planar B-spline parameterizations from given complex CAD boundaries consisting of a set of B-spline curves. Instead of forming the computational domain by a simple boundary, planar domains with high genus and more complex boundary curves are considered. Firstly, some pre-processing operations including B\\'ezier extraction and subdivision are performed on each boundary curve in order to generate a high-quality planar parameterization; then a robust planar domain partition framework is proposed to construct high-quality patch-meshing results with few singularities from the discrete boundary formed by connecting the end points of the resulting boundary segments. After the topology information generation of quadrilateral decomposition, the optimal placement of interior B\\'ezier curves corresponding to the interior edges of the quadrangulation is constructed by a global optimization method to achieve a patch-partition with high quality. Finally, after the imposition of C1=G1-continuity constraints on the interface of neighboring B\\'ezier patches with respect to each quad in the quadrangulation, the high-quality B\\'ezier patch parameterization is obtained by a C1-constrained local optimization method to achieve uniform and orthogonal iso-parametric structures while keeping the continuity conditions between patches. The efficiency and robustness of the proposed method are demonstrated by several examples which are compared to results obtained by the skeleton-based parameterization approach.

An evaluation of hand immersion for rewarming individuals cooled by immersion in cold water.

Science.gov (United States)

Cahill, C J; Balmi, P J; Tipton, M J

1995-05-01

The hypothesis that hypothermic individuals can be actively rewarmed in the field by immersion of the extremities in hot water was investigated. Three techniques for rewarming subjects with lowered deep body temperatures were compared: a) whole body immersion to the neck in water at 40 degrees C; b) immersion of two hands plus forearms only in water at 42 degrees C; and c) passive rewarming. The suggestion that the fall in deep body temperature resulting from immersion to the neck in water at 15 degrees C could be arrested by immersing both arms in water at 42 degrees C was also investigated. Results indicated that immersion to the neck in hot water was clearly the most effective rewarming technique. No significant difference (p > 0.05) was observed in the deep body temperature response during passive rewarming or during immersion of both hands and forearms in water at 42 degrees C. In the later condition some increase in peripheral blood flow to the hands may have occurred and resulted in a heat input of approximately 12 W, but any benefit from this was negated by an associated significant decrease (p > 0.05) in intrinsic heat production. Immersing the arms in hot water during immersion to the neck in cold water appeared to accelerate rather than decelerate the rate of fall of deep body temperature. We concluded that hand rewarming, although theoretically attractive, is ineffective in practice and could be detrimental in some circumstances, by suppressing intrinsic heat production or precipitating rewarming collapse.

Immersive journalism: immersive virtual reality for the first-person experience of news

OpenAIRE

Peña, Nonny de la; Weil, Peggy; Llobera, Joan; Giannopoulos, Elias; Pomés Freixa, Ausiàs; Spanlang, Bernhard; Friedman, Doron; Sánchez-Vives, María Victoria; Slater, Mel

2010-01-01

This paper introduces the concept, and discusses the implications of Immersive Journalism, that is the production of news in a form in which people can gain first- 2 person experiences of the events or situation described in news stories. The fundamental idea of Immersive Journalism is to allow the participant, typically represented as a digital avatar, to actually enter a virtually recreated scenario representing the news story. The sense of presence obtained through an immersive system (whe...

Numerical Simulation of Complex Multi-Fluid Flows using a Combined Immersed Boundary and Volume of Fluid Approach

NARCIS (Netherlands)

Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

2007-01-01

In this paper a simulation model is presented for the Direct Numerical Simulation (DNS) of complex multi-fluid flows in which simultaneously (moving) deformable (drops or bubbles) and non-deformable (moving) elements (particles) are present, possibly with the additional presence of free surfaces.

Direct numerical simulation of complex multi-fluid flows using a combined front tracking and immersed boundary method

NARCIS (Netherlands)

Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

2009-01-01

In this paper a simulation model is presented for the Direct Numerical Simulation (DNS) of complex multi-fluid flows in which simultaneously (moving) deformable (drops or bubbles) and non-deformable (moving) elements (particles) are present, possibly with the additional presence of free surfaces.

Immersion in Movement-Based Interaction

NARCIS (Netherlands)

Pasch, M.; Bianchi-Berthouze, N.; van Dijk, Elisabeth M.A.G.; Nijholt, Antinus; Nijholt, A.; Reidsma, Dennis; Reidsma, D.; Hondorp, G.H.W.

2009-01-01

The phenomenon of immersing oneself into virtual environments has been established widely. Yet to date (to our best knowledge) the physical dimension has been neglected in studies investigating immersion in Human-Computer Interaction (HCI). In this paper we investigate how the concept of immersion

Desires for beverages and liking of skin care product odors in imaginative and immersive virtual reality beach contexts

DEFF Research Database (Denmark)

Andersen, Ida Ninett Skovgaard K; Kraus, Alexandra A.; Ritz, Christian

2018-01-01

Immersive technologies simulating real-life environments allow repeated simulation of complex real-life situations at one location and, therefore, bear potential for consumer product evaluations and food behavior studies. This study aimed to assess whether a contextual exposure by immersive virtu...... on beverage-related desires. The VR technology seems to be a promising tool for evaluating contextual influences in food consumer research.......Immersive technologies simulating real-life environments allow repeated simulation of complex real-life situations at one location and, therefore, bear potential for consumer product evaluations and food behavior studies. This study aimed to assess whether a contextual exposure by immersive virtual...... in the same room but without the contextual exposure was also performed (Neutral). Subjects rated their desires for hot and cold beverages during and just after the contextual exposure. Liking for skin care samples (sun screen and regular lotion) were assessed during exposure. The retention of the contextual...

Revisiting the use of the immersed-boundary lattice-Boltzmann method for simulations of suspended particles

Science.gov (United States)

Mountrakis, L.; Lorenz, E.; Hoekstra, A. G.

2017-07-01

The immersed-boundary lattice-Boltzmann method (IB-LBM) is increasingly being used in simulations of dense suspensions. These systems are computationally very expensive and can strongly benefit from lower resolutions that still maintain the desired accuracy for the quantities of interest. IB-LBM has a number of free parameters that have to be defined, often without exact knowledge of the tradeoffs, since their behavior in low resolutions is not well understood. Such parameters are the lattice constant Δ x , the number of vertices Nv, the interpolation kernel ϕ , and the LBM relaxation time τ . We investigate the effect of these IB-LBM parameters on a number of straightforward but challenging benchmarks. The systems considered are (a) the flow of a single sphere in shear flow, (b) the collision of two spheres in shear flow, and (c) the lubrication interaction of two spheres. All benchmarks are performed in three dimensions. The first two systems are used for determining two effective radii: the hydrodynamic radius rhyd and the particle interaction radius rinter. The last system is used to establish the numerical robustness of the lubrication forces, used to probe the hydrodynamic interactions in the limit of small gaps. Our results show that lower spatial resolutions result in larger hydrodynamic and interaction radii, while surface densities should be chosen above two vertices per LU2 result to prevent fluid penetration in underresolved meshes. Underresolved meshes also failed to produce the migration of particles toward the center of the domain due to lift forces in Couette flow, mostly noticeable for IBM-kernel ϕ2. Kernel ϕ4, despite being more robust toward mesh resolution, produces a notable membrane thickness, leading to the breakdown of the lubrication forces in larger gaps, and its use in dense suspensions where the mean particle distances are small can result in undesired behavior. rhyd is measured to be different from rinter, suggesting that there is

Immersion Revisited: A Review of Existing Definitions of Immersion and Their Relation to Different Theories of Presence

Directory of Open Access Journals (Sweden)

Niels Christian Nilsson

2016-11-01

Full Text Available The term immersion continues to be applied inconsistently within and across different fields of research connected with the study of virtual reality and interactive media. Moreover, immersion is oftentimes used interchangeably with the terms presence and engagement. This article details a review of existing definitions of immersion originating within the study of video games, virtual environments, and literary works of fiction. Based on this review, a three-dimensional taxonomy of the various conceptualizations of immersion is proposed. That is, the existing definitions of immersion may be broadly divided into three categories, each representing a dimension of the taxonomy: immersion as a property of a system, a subjective response to narrative contents, or a subjective response to challenges within the virtual environment. Finally, four distinct theories of presence are introduced and, based on the established taxonomy, we discuss how the individual theories relate to existing definitions of immersion.

Managing SMEs’ Collaboration Across Organizational Boundaries Within a Regional Business Ecosystem

DEFF Research Database (Denmark)

Radziwon, Agnieszka; Bogers, Marcel

2018-01-01

’ perspective on managing and organizing inter-company collaboration within a regional business ecosystem. We explore how purposefully managed mutual knowledge flows across organizational boundaries applied by SMEs contribute to the development of the ecosystem they are immersed in. Our key findings include...... insights into the advantages offered by being embedded within regional ecosystem boundaries, such as low transaction costs and reduced risks of opportunistic behaviors, environmental opportunities for external knowledge sourcing or increase of the sphere of influence. We also highlight accompanied...

Free flight simulations of a dragonfly-like flapping wing-body model using the immersed boundary-lattice Boltzmann method

International Nuclear Information System (INIS)

Minami, Keisuke; Suzuki, Kosuke; Inamuro, Takaji

2015-01-01

Free flights of the dragonfly-like flapping wing-body model are numerically investigated using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re, the Froude number Fr, and the non-dimensional mass m, and we set the parameters at Re = 200, Fr = 15, and m = 51. First, we simulate free flights of the model without the pitching rotation for various values of the phase lag angle ϕ between the forewing and the hindwing motions. We find that the wing-body model goes forward in spite of ϕ, and the model with ϕ = 0 ∘ and 90 ∘ goes upward against gravity. The model with ϕ =180 ∘ goes almost horizontally, and the model with ϕ =270 ∘ goes downward. That is, the moving direction of the model depends on the phase lag angle ϕ. Secondly, we simulate free flights with the pitching rotation for various values of the phase lag angle ϕ. It is found that in spite of ϕ the wing-body model turns gradually in the nose-up direction and goes back and down as the pitching angle Θ c increases. That is, the wing-body model cannot make a stable forward flight without control. Finally, we show a way to control the pitching motion by changing the lead–lag angle γ(t). We propose a simple proportional controller of γ(t) which makes stable flights within Θ c =±5 ∘ and works well even for a large disturbance. (paper)

Numerical study on the rotation of an elastic rod in a viscous fluid using an immersed boundary method

International Nuclear Information System (INIS)

Maniyeri, Ranjith; Kang, Sang Mo

2012-01-01

We present a three dimensional computational model based on an immersed boundary (IB) method to study the hydrodynamic features of a solid flexible cylindrical rod in a viscous fluid driven at one side by a tiny motor. The elastic rod is modelled by a number of circular cross-sections with twelve IB points on each cross-section. Three types of elastic links are created from each IB point to obtain an elastic network model of the rod and the first cross-section is modelled as the motor part. The elastic forces are computed based on an elastic energy approach and the motor forces are obtained from the applied angular frequency of rotation of the motor. The Stokes equations governing the fluid are solved on a staggered Cartesian grid system using the fractional-step based finite-volume method. Numerical simulations are performed to demonstrate the three dynamical stages of rod motion- twirling, whirling and overwhirling for different rotational frequency of the motor. It is revealed that for low rotational frequencies, the rod undergoes stable rigid body motion known as twirling. For high rotational frequencies of the motor, it is observed that the rod initially undergoes whirling motion and attains an unstable helical shape. Further, it is noticed that a discontinuous shape transition occurs for the rod and it folds back on itself. This unstable motion is referred to as overwhirling. It is also found that there exists a critical value of angular frequency of rotation of the motor below which the rod is subjected to twirling motion and above which it undergoes overwhirling motion

Fisher's Zeros as the Boundary of Renormalization Group Flows in Complex Coupling Spaces

International Nuclear Information System (INIS)

Denbleyker, A.; Du Daping; Liu Yuzhi; Meurice, Y.; Zou Haiyuan

2010-01-01

We propose new methods to extend the renormalization group transformation to complex coupling spaces. We argue that Fisher's zeros are located at the boundary of the complex basin of attraction of infrared fixed points. We support this picture with numerical calculations at finite volume for two-dimensional O(N) models in the large-N limit and the hierarchical Ising model. We present numerical evidence that, as the volume increases, the Fisher's zeros of four-dimensional pure gauge SU(2) lattice gauge theory with a Wilson action stabilize at a distance larger than 0.15 from the real axis in the complex β=4/g 2 plane. We discuss the implications for proofs of confinement and searches for nontrivial infrared fixed points in models beyond the standard model.

Embedding Versus Immersion in General Relativity

OpenAIRE

Monte, Edmundo M.

2009-01-01

We briefly discuss the concepts of immersion and embedding of space-times in higher-dimensional spaces. We revisit the classical work by Kasner in which he constructs a model of immersion of the Schwarzschild exterior solution into a six-dimensional pseudo-Euclidean manifold. We show that, from a physical point of view, this model is not entirely satisfactory since the causal structure of the immersed space-time is not preserved by the immersion.

Complete spacelike immersions with topology

International Nuclear Information System (INIS)

Harris, S.G.

1988-01-01

A fairly large class of Lorentz manifolds is defined, called WH normal manifolds, which are approximately those for which timelike infinity is a single point. It is shown that, in such a space, an immersed spacelike hypersurface which is complete must, if it is self-intersecting, not achronal or proper, satisfy strong topological conditions; in particular, if the immersion is injective in the fundamental group, then the hypersurface must be closed, embedded and achronal (i.e. a partial Cauchy surface). WH normal spaces include products of any Riemannian manifold with Minkowski 1-space; in such space, a complete immersed spacelike hypersurface must be immersed as a covering space for the Riemannian factor. (author)

Functional Dissection of the Blocking and Bypass Activities of the Fab-8 Boundary in the Drosophila Bithorax Complex.

Science.gov (United States)

Kyrchanova, Olga; Mogila, Vladic; Wolle, Daniel; Deshpande, Girish; Parshikov, Alexander; Cléard, Fabienne; Karch, Francois; Schedl, Paul; Georgiev, Pavel

2016-07-01

Functionally autonomous regulatory domains direct the parasegment-specific expression of the Drosophila Bithorax complex (BX-C) homeotic genes. Autonomy is conferred by boundary/insulator elements that separate each regulatory domain from its neighbors. For six of the nine parasegment (PS) regulatory domains in the complex, at least one boundary is located between the domain and its target homeotic gene. Consequently, BX-C boundaries must not only block adventitious interactions between neighboring regulatory domains, but also be permissive (bypass) for regulatory interactions between the domains and their gene targets. To elucidate how the BX-C boundaries combine these two contradictory activities, we have used a boundary replacement strategy. We show that a 337 bp fragment spanning the Fab-8 boundary nuclease hypersensitive site and lacking all but 83 bp of the 625 bp Fab-8 PTS (promoter targeting sequence) fully rescues a Fab-7 deletion. It blocks crosstalk between the iab-6 and iab-7 regulatory domains, and has bypass activity that enables the two downstream domains, iab-5 and iab-6, to regulate Abdominal-B (Abd-B) transcription in spite of two intervening boundary elements. Fab-8 has two dCTCF sites and we show that they are necessary both for blocking and bypass activity. However, CTCF sites on their own are not sufficient for bypass. While multimerized dCTCF (or Su(Hw)) sites have blocking activity, they fail to support bypass. Moreover, this bypass defect is not rescued by the full length PTS. Finally, we show that orientation is critical for the proper functioning the Fab-8 replacement. Though the inverted Fab-8 boundary still blocks crosstalk, it disrupts the topology of the Abd-B regulatory domains and does not support bypass. Importantly, altering the orientation of the Fab-8 dCTCF sites is not sufficient to disrupt bypass, indicating that orientation dependence is conferred by other factors.

Influence of surface sealant on the translucency of composite resin: effect of immersion time and immersion media

Directory of Open Access Journals (Sweden)

Patrícia Petromilli Nordi Sasso Garcia

2008-06-01

Full Text Available This study evaluated the effect of surface sealant on the translucency of composite resin immersed in different solutions. The study involved the following materials: Charisma, Fortify and coffee, Coca-Cola®, tea and artificial saliva as solutions. Sixty-four specimens (n = 8 were manufactured and immersed in artificial saliva at 37 ± 1 °C. Samples were immersed in the solutions for three times a day and re-immersed in artificial saliva until the translucency readings. The measurements were carried out at nine times: T1 - 24 hours after specimen preparation, T2 - 24 hours after immersion in the solutions, T3 - 48 hours and T4 to T9 - 7, 14, 21, 30, 60 and 90 days, respectively, after immersion. The translucency values were measured using a JOUAN device. The results were subjected to ANOVA and Tukey's test at 5%. The surface sealant was not able to protect the composite resin against staining, the coffee showed the strongest staining action, followed by tea and regarding immersion time, a significant alteration was noted in the translucency of composite resin after 21 days.

Cardiovascular regulation during water immersion.

Science.gov (United States)

Park, K S; Choi, J K; Park, Y S

1999-11-01

Head-out water immersion at thermoneutral temperature (34-35 degrees C) increases cardiac output for a given O2 consumption, leading to a relative hyperperfusion of peripheral tissues. To determine if subjects immersed in water at a colder temperature show similar responses and to explore the significance of the hyperperfusion, cardiovascular functions were investigated (impedance cardiography) on 10 men at rest and while performing exercise on a leg cycle ergometer (delta M = approximately 95 W.m-2) in air and in water at 34.5 degrees C and 30 degrees C, respectively. In subjects resting in water, the cardiac output increased by approximately 50% compared to that in air, mainly due to a rise in stroke volume. The stroke volume change tended to be greater in 30 degrees C water than in 34.5 degrees C water, and this was due to a greater increase in cardiac preload, as indicated by a significantly greater left ventricular end-diastolic volume. Arterial systolic pressure rose slightly during water immersion. Arterial diastolic pressure remained unchanged in 34.5 degrees C water, but it rose in 30 degrees C water. The total peripheral resistance fell 37% in 34.5 degrees C water and 32% in 30 degrees C water. Both in air and in water, mild exercise increased the cardiac output, and this was mainly due to an increase in heart rate. Since, however, the stroke volume increased with water immersion, cardiac output at a given work load appeared to be significantly higher in water than in air. The arterial pressures did not decrease with water immersion, despite a marked reduction in total peripheral resistance. These results suggest that 1) during cold water immersion, peripheral vasoconstriction provides an additional increase in cardiac preload, leading to a further increase in the stroke volume compared to that of the thermoneutral water immersion, 2) the mechanism of cardiovascular adjustment during dynamic exercise is not changed by the persistent increase in cardiac

Study on Surface Permeability of Concrete under Immersion

OpenAIRE

Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

2014-01-01

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured af...

Warming by immersion or exercise affects initial cooling rate during subsequent cold water immersion.

Science.gov (United States)

Scott, Chris G; Ducharme, Michel B; Haman, François; Kenny, Glen P

2004-11-01

We examined the effect of prior heating, by exercise and warm-water immersion, on core cooling rates in individuals rendered mildly hypothermic by immersion in cold water. There were seven male subjects who were randomly assigned to one of three groups: 1) seated rest for 15 min (control); 2) cycling ergometry for 15 min at 70% Vo2 peak (active warming); or 3) immersion in a circulated bath at 40 degrees C to an esophageal temperature (Tes) similar to that at the end of exercise (passive warming). Subjects were then immersed in 7 degrees C water to a Tes of 34.5 degrees C. Initial Tes cooling rates (initial approximately 6 min cooling) differed significantly among the treatment conditions (0.074 +/- 0.045, 0.129 +/- 0.076, and 0.348 +/- 0.117 degrees C x min(-1) for control, active, and passive warming conditions, respectively); however, secondary cooling rates (rates following initial approximately 6 min cooling to the end of immersion) were not different between treatments (average of 0.102 +/- 0.085 degrees C x min(-1)). Overall Tes cooling rates during the full immersion period differed significantly and were 0.067 +/- 0.047, 0.085 +/- 0.045, and 0.209 +/- 0.131 degrees C x min(-1) for control, active, and passive warming, respectively. These results suggest that prior warming by both active and, to a greater extent, passive warming, may predispose a person to greater heat loss and to experience a larger decline in core temperature when subsequently exposed to cold water. Thus, functional time and possibly survival time could be reduced when cold water immersion is preceded by whole-body passive warming, and to a lesser degree by active warming.

FIJI: A Framework for the Immersion-Journalism Intersection

Directory of Open Access Journals (Sweden)

Gary M. Hardee

2017-07-01

Full Text Available As journalists experiment with developing immersive journalism—first-person, interactive experiences of news events—guidelines are needed to help bridge a disconnect between the requirements of journalism and the capabilities of emerging technologies. Many journalists need to better understand the fundamental concepts of immersion and the capabilities and limitations of common immersive technologies. Similarly, developers of immersive journalism works need to know the fundamentals that define journalistic professionalism and excellence and the key requirements of various types of journalistic stories. To address these gaps, we have developed a Framework for the Immersion-Journalism Intersection (FIJI. In FIJI, we have identified four domains of knowledge that intersect to define the key requirements of immersive journalism: the fundamentals of immersion, common immersive technologies, the fundamentals of journalism, and the major types of journalistic stories. Based on these key requirements, we have formally defined four types of immersive journalism that are appropriate for public dissemination. In this article, we discuss the history of immersive journalism, present the four domains and key intersection of FIJI, and provide a number of guidelines for journalists new to creating immersive experiences.

Implementation and Testing of Advanced Surface Boundary Conditions Over Complex Terrain in A Semi-idealized Model

Science.gov (United States)

Li, Y.; Epifanio, C.

2017-12-01

In numerical prediction models, the interaction between the Earth's surface and the atmosphere is typically accounted for in terms of surface layer parameterizations, whose main job is to specify turbulent fluxes of heat, moisture and momentum across the lower boundary of the model domain. In the case of a domain with complex geometry, implementing the flux conditions (particularly the tensor stress condition) at the boundary can be somewhat subtle, and there has been a notable history of confusion in the CFD community over how to formulate and impose such conditions generally. In the atmospheric case, modelers have largely been able to avoid these complications, at least until recently, by assuming that the terrain resolved at typical model resolutions is fairly gentle, in the sense of having relatively shallow slopes. This in turn allows the flux conditions to be imposed as if the lower boundary were essentially flat. Unfortunately, while this flat-boundary assumption is acceptable for coarse resolutions, as grids become more refined and the geometry of the resolved terrain becomes more complex, the appproach is less justified. With this in mind, the goal of our present study is to explore the implementation and usage of the full, unapproximated version of the turbulent flux/stress conditions in atmospheric models, thus taking full account of the complex geometry of the resolved terrain. We propose to implement the conditions using a semi-idealized model developed by Epifanio (2007), in which the discretized boundary conditions are reduced to a large, sparse-matrix problem. The emphasis will be on fluxes of momentum, as the tensor nature of this flux makes the associated stress condition more difficult to impose, although the flux conditions for heat and moisture will be considered as well. With the resulotion of 90 meters, some of the results show that the typical differences between flat-boundary cases and full/stress cases are on the order of 10%, with extreme

[Immersion pulmonary edema].

Science.gov (United States)

Desgraz, Benoît; Sartori, Claudio; Saubade, Mathieu; Héritier, Francis; Gabus, Vincent

2017-07-12

Immersion pulmonary edema may occur during scuba diving, snorke-ling or swimming. It is a rare and often recurrent disease, mainly affecting individuals aged over 50 with high blood pressure. However it also occurs in young individuals with a healthy heart. The main symptoms are dyspnea, cough and hemoptysis. The outcome is often favorable under oxygen treatment but deaths are reported. A cardiac and pulmonary assessment is necessary to evaluate the risk of recurrence and possible contraindications to immersion.

Study on Surface Permeability of Concrete under Immersion.

Science.gov (United States)

Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

2014-01-28

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due to hydration. The two effects work simultaneously and compete throughout the immersion period. The proposed mechanisms get support from microscopic measurements and observations.

The effect of boundaries on the asymptotic wavenumber of spiral wave solutions of the complex Ginzburg–Landau equation

KAUST Repository

Aguareles, M.

2014-06-01

In this paper we consider an oscillatory medium whose dynamics are modeled by the complex Ginzburg-Landau equation. In particular, we focus on n-armed spiral wave solutions of the complex Ginzburg-Landau equation in a disk of radius d with homogeneous Neumann boundary conditions. It is well-known that such solutions exist for small enough values of the twist parameter q and large enough values of d. We investigate the effect of boundaries on the rotational frequency of the spirals, which is an unknown of the problem uniquely determined by the parameters d and q. We show that there is a threshold in the parameter space where the effect of the boundary on the rotational frequency switches from being algebraic to exponentially weak. We use the method of matched asymptotic expansions to obtain explicit expressions for the asymptotic wavenumber as a function of the twist parameter and the domain size for small values of q. © 2014 Elsevier B.V. All rights reserved.

A Theory of Immersion Freezing

Science.gov (United States)

Barahona, Donifan

2017-01-01

Immersion freezing is likely involved in the initiation of precipitation and determines to large extent the phase partitioning in convective clouds. Theoretical models commonly used to describe immersion freezing in atmospheric models are based on the classical nucleation theory which however neglects important interactions near the immersed particle that may affect nucleation rates. This work introduces a new theory of immersion freezing based on two premises. First, immersion ice nucleation is mediated by the modification of the properties of water near the particle-liquid interface, rather than by the geometry of the ice germ. Second, the same mechanism that leads to the decrease in the work of germ formation also decreases the mobility of water molecules near the immersed particle. These two premises allow establishing general thermodynamic constraints to the ice nucleation rate. Analysis of the new theory shows that active sites likely trigger ice nucleation, but they do not control the overall nucleation rate nor the probability of freezing. It also suggests that materials with different ice nucleation efficiency may exhibit similar freezing temperatures under similar conditions but differ in their sensitivity to particle surface area and cooling rate. Predicted nucleation rates show good agreement with observations for a diverse set of materials including dust, black carbon and bacterial ice nucleating particles. The application of the new theory within the NASA Global Earth System Model (GEOS-5) is also discussed.

Clinical vocabulary as a boundary object in multidisciplinary care management of multiple chemical sensitivity, a complex and chronic condition.

Science.gov (United States)

Sampalli, Tara; Shepherd, Michael; Duffy, Jack

2011-04-14

Research has shown that accurate and timely communication between multidisciplinary clinicians involved in the care of complex and chronic health conditions is often challenging. The domain knowledge for these conditions is heterogeneous, with poorly categorized, unstructured, and inconsistent clinical vocabulary. The potential of boundary object as a technique to bridge communication gaps is explored in this study. A standardized and controlled clinical vocabulary was developed as a boundary object in the domain of a complex and chronic health condition, namely, multiple chemical sensitivity, to improve communication among multidisciplinary clinicians. A convenience sample of 100 patients with a diagnosis of multiple chemical sensitivity, nine multidisciplinary clinicians involved in the care of patients with multiple chemical sensitivity, and 36 clinicians in the community participated in the study. Eighty-two percent of the multidisciplinary and inconsistent vocabulary was standardized using the Systematized Nomenclature of Medicine - Clinical Terms (SNOMED(®) CT as a reference terminology. Over 80% of the multidisciplinary clinicians agreed on the overall usefulness of having a controlled vocabulary as a boundary object. Over 65% of clinicians in the community agreed on the overall usefulness of the vocabulary. The results from this study are promising and will be further evaluated in the domain of another complex chronic condition, ie, chronic pain. The study was conducted as a preliminary analysis for developing a boundary object in a heterogeneous domain of knowledge.

An analysis of species boundaries and biogeographic patterns in a cryptic species complex: the rotifer--Brachionus plicatilis.

Science.gov (United States)

Suatoni, Elizabeth; Vicario, Saverio; Rice, Sean; Snell, Terry; Caccone, Adalgisa

2006-10-01

Since the advent of molecular phylogenetics, there is increasing evidence that many small aquatic and marine invertebrates--once believed to be single, cosmopolitan species--are in fact cryptic species complexes. Although the application of the biological species concept is central to the identification of species boundaries in these cryptic complexes, tests of reproductive isolation do not frequently accompany phylogenetic studies. Because different species concepts generally identify different boundaries in cryptic complexes, studies that apply multiple species concepts are needed to gain a more detailed understanding of patterns of diversification in these taxa. Here we explore different methods of empirically delimiting species boundaries in the salt water rotifer Brachionus plicatilis by comparing reproductive data (i.e., the traditional biological species concept) to phylogenetic data (the genealogical species concept). Based on a high degree of molecular sequence divergence and largely concordant genetic patterns in COI and ITS1, the genealogical species hypothesis indicates the existence of at least 14 species--the highest estimate for the group thus far. A test of the genealogical species concept with biological crosses shows a fairly high level of concordance, depending on the degree of reproductive success used to draw boundaries. The convergence of species concepts in this group suggests that many of the species within the group may be old. Although the diversity of the group is higher than previously understood, geographic distributions remain broad. Efficient passive dispersal has resulted in global distributions for many species with some evidence of isolation by distance over large geographic scales. These patterns concur with expectations that micro-meiofauna (0.1-1mm) have biogeographies intermediate to microbial organisms and large vertebrates. Sympatry of genetically distant strains is common.

Photogrammetric Applications of Immersive Video Cameras

Science.gov (United States)

Kwiatek, K.; Tokarczyk, R.

2014-05-01

The paper investigates immersive videography and its application in close-range photogrammetry. Immersive video involves the capture of a live-action scene that presents a 360° field of view. It is recorded simultaneously by multiple cameras or microlenses, where the principal point of each camera is offset from the rotating axis of the device. This issue causes problems when stitching together individual frames of video separated from particular cameras, however there are ways to overcome it and applying immersive cameras in photogrammetry provides a new potential. The paper presents two applications of immersive video in photogrammetry. At first, the creation of a low-cost mobile mapping system based on Ladybug®3 and GPS device is discussed. The amount of panoramas is much too high for photogrammetric purposes as the base line between spherical panoramas is around 1 metre. More than 92 000 panoramas were recorded in one Polish region of Czarny Dunajec and the measurements from panoramas enable the user to measure the area of outdoors (adverting structures) and billboards. A new law is being created in order to limit the number of illegal advertising structures in the Polish landscape and immersive video recorded in a short period of time is a candidate for economical and flexible measurements off-site. The second approach is a generation of 3d video-based reconstructions of heritage sites based on immersive video (structure from immersive video). A mobile camera mounted on a tripod dolly was used to record the interior scene and immersive video, separated into thousands of still panoramas, was converted from video into 3d objects using Agisoft Photoscan Professional. The findings from these experiments demonstrated that immersive photogrammetry seems to be a flexible and prompt method of 3d modelling and provides promising features for mobile mapping systems.

Immersion cooling of silicon photomultipliers (SiPM) for nuclear medicine imaging applications

International Nuclear Information System (INIS)

Raylman, R.R.; Stolin, A.V.

2016-01-01

Silicon photomultipliers (SiPM) are compact, high amplification light detection devices that have recently been incorporated into magnetic field-compatible positron emission tomography (PET) scanners. To take full advantage of these devices, it is preferable to cool them below room temperature. Most current methods are limited to the cooling of individual detector modules, increasing complexity and cost of scanners made-up of a large number of modules. In this work we investigated a new method of cooling, immersion of the detector modules in non-electrically conductive, cooled liquid. A small-scale prototype system was constructed to cool a relatively large area SiPM-based, scintillator detector module by immersing it in a circulating bath of mineral oil. Testing demonstrated that the system rapidly decreased and stabilized the temperature of the device. Operation of the detector illustrated the expected benefits of cooling, with no apparent degradation of performance attributable to immersion in fluid. - Highlights: • Immersion cooling is new, simple and inexpensive method to cool solid state based nuclear medicine scanner. • Method successfully tested on a scaled version of an SiPM-based PET detector module. • Can be scaled up to cool a complete PET scanner.

A framework for WRF to WRF-IBM grid nesting to enable multiscale simulations

Energy Technology Data Exchange (ETDEWEB)

Wiersema, David John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Berkeley, CA (United States); Lundquist, Katherine A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chow, Fotini Katapodes [Univ. of California, Berkeley, CA (United States)

2016-09-29

With advances in computational power, mesoscale models, such as the Weather Research and Forecasting (WRF) model, are often pushed to higher resolutions. As the model’s horizontal resolution is refined, the maximum resolved terrain slope will increase. Because WRF uses a terrain-following coordinate, this increase in resolved terrain slopes introduces additional grid skewness. At high resolutions and over complex terrain, this grid skewness can introduce large numerical errors that require methods, such as the immersed boundary method, to keep the model accurate and stable. Our implementation of the immersed boundary method in the WRF model, WRF-IBM, has proven effective at microscale simulations over complex terrain. WRF-IBM uses a non-conforming grid that extends beneath the model’s terrain. Boundary conditions at the immersed boundary, the terrain, are enforced by introducing a body force term to the governing equations at points directly beneath the immersed boundary. Nesting between a WRF parent grid and a WRF-IBM child grid requires a new framework for initialization and forcing of the child WRF-IBM grid. This framework will enable concurrent multi-scale simulations within the WRF model, improving the accuracy of high-resolution simulations and enabling simulations across a wide range of scales.

Research on evaluation techniques for immersive multimedia

Science.gov (United States)

Hashim, Aslinda M.; Romli, Fakaruddin Fahmi; Zainal Osman, Zosipha

2013-03-01

Nowadays Immersive Multimedia covers most usage in tremendous ways, such as healthcare/surgery, military, architecture, art, entertainment, education, business, media, sport, rehabilitation/treatment and training areas. Moreover, the significant of Immersive Multimedia to directly meet the end-users, clients and customers needs for a diversity of feature and purpose is the assembly of multiple elements that drive effective Immersive Multimedia system design, so evaluation techniques is crucial for Immersive Multimedia environments. A brief general idea of virtual environment (VE) context and `realism' concept that formulate the Immersive Multimedia environments is then provided. This is followed by a concise summary of the elements of VE assessment technique that is applied in Immersive Multimedia system design, which outlines the classification space for Immersive Multimedia environments evaluation techniques and gives an overview of the types of results reported. A particular focus is placed on the implications of the Immersive Multimedia environments evaluation techniques in relation to the elements of VE assessment technique, which is the primary purpose of producing this research. The paper will then conclude with an extensive overview of the recommendations emanating from the research.

An immersed body method for coupled neutron transport and thermal hydraulic simulations of PWR assemblies

International Nuclear Information System (INIS)

Jewer, S.; Buchan, A.G.; Pain, C.C.; Cacuci, D.G.

2014-01-01

Highlights: • A new method of coupled radiation transport, heat and momentum exchanges on fluids, and heat transfer simulations. • Simulation of the thermal hydraulics and radiative properties within whole PWR assemblies. • An immersed body method for modelling complex solid domains on practical computational meshes. - Abstract: A recently developed immersed body method is adapted and used to model a typical pressurised water reactor (PWR) fuel assembly. The approach is implemented with the numerical framework of the finite element, transient criticality code, FETCH which is composed of the neutron transport code, EVENT, and the CFD code, FLUIDITY. Within this framework the neutron transport equation, Navier–Stokes equations and a fluid energy conservation equation are solved in a coupled manner on a coincident structured or unstructured mesh. The immersed body method has been used to model the solid fuel pins. The key feature of this method is that the fluid/neutronic domain and the solid domain are represented by overlapping and non-conforming meshes. The main difficulty of this approach, for which a solution is proposed in this work, is the conservative mapping of the energy and momentum exchange between the fluid/neutronic mesh and the solid fuel pin mesh. Three numerical examples are presented which include a validation of the fuel pin submodel against an analytical solution; an uncoupled (no neutron transport solution) PWR fuel assembly model with a specified power distribution which was validated against the COBRA-EN subchannel analysis code; and finally a coupled model of a PWR fuel assembly with reflective neutron boundary conditions. Coupling between the fluid and neutron transport solutions is through the nuclear cross sections dependence on Doppler fuel temperature, coolant density and temperature, which was taken into account by using pre-calculated cross-section lookup tables generated using WIMS9a. The method was found to show good agreement

How Engineers Negotiate Domain Boundaries in a Complex, Interdisciplinary Engineering Project

Science.gov (United States)

Panther, Grace; Montfort, Devlin; Pirtle, Zachary

2017-01-01

Engineering educators have an essential role in preparing engineers to work in a complex, interdisciplinary workforce. While much engineering education focuses on teaching students to develop disciplinary expertise in specific engineering domains, there is a strong need to teach engineers about the knowledge that they develop or use in their work (Bucciarelli 1994, Allenby Sarewitz, 2011; Frodeman, 2013). The purpose of this research is to gain a better understanding of the knowledge systems of practicing engineers through observations of their practices such that the insights learned can guide future education efforts. Using an example from a complex and interdisciplinary engineering project, this paper presents a case study overviewing the types of epistemological (or knowledge-acquiring or using) complexities that engineers navigate. Specifically, we looked at a discussion of the thermal design of a CubeSat that occurred during an engineering review at NASA. We analyzed the review using a framework that we call 'peak events', or pointed discussions between reviewers, project engineers, and managers. We examined the dialog within peak events to identify the ways that knowledge was brought to bear, highlighting discussions of uncertainty and the boundaries of knowledge claims. We focus on one example discussion surrounding the thermal design of the CubeSat, which provides a particularly thorough example of a knowledge system since the engineers present explained, justified, negotiated, and defended knowledge within a social setting. Engineering students do not get much practice or instruction in explicitly negotiating knowledge systems and epistemic standards in this way. We highlight issues that should matter to engineering educators, such as the need to discuss what level of uncertainty is sufficient and the need to negotiate boundaries of system responsibility. Although this analysis is limited to a single discussion or 'peak event', our case shows that this

Immersive visualization of dynamic CFD model results

International Nuclear Information System (INIS)

Comparato, J.R.; Ringel, K.L.; Heath, D.J.

2004-01-01

With immersive visualization the engineer has the means for vividly understanding problem causes and discovering opportunities to improve design. Software can generate an interactive world in which collaborators experience the results of complex mathematical simulations such as computational fluid dynamic (CFD) modeling. Such software, while providing unique benefits over traditional visualization techniques, presents special development challenges. The visualization of large quantities of data interactively requires both significant computational power and shrewd data management. On the computational front, commodity hardware is outperforming large workstations in graphical quality and frame rates. Also, 64-bit commodity computing shows promise in enabling interactive visualization of large datasets. Initial interactive transient visualization methods and examples are presented, as well as development trends in commodity hardware and clustering. Interactive, immersive visualization relies on relevant data being stored in active memory for fast response to user requests. For large or transient datasets, data management becomes a key issue. Techniques for dynamic data loading and data reduction are presented as means to increase visualization performance. (author)

Delimiting Species Boundaries within a Paraphyletic Species Complex: Insights from Morphological, Genetic, and Molecular Data on Paramecium sonneborni (Paramecium aurelia species complex, Ciliophora, Protozoa).

Science.gov (United States)

Przyboś, Ewa; Tarcz, Sebastian; Rautian, Maria; Sawka, Natalia

2015-09-01

The demarcation of boundaries between protist species is often problematic because of the absence of a uniform species definition, the abundance of cryptic diversity, and the occurrence of convergent morphology. The ciliates belonging to the Paramecium aurelia complex, consisting of 15 species, are a good model for such systematic and evolutionary studies. One member of the complex is P. sonneborni, previously known only from one stand in Texas (USA), but recently found in two new sampling sites in Cyprus (creeks running to Salt Lake and Oroklini Lake near Larnaca). The studied Paramecium sonneborni strains (from the USA and Cyprus) reveal low viability in the F1 and F2 generations of interstrain hybrids and may be an example of ongoing allopatric speciation. Despite its molecular distinctiveness, we postulate that P. sonneborni should remain in the P. aurelia complex, making it a paraphyletic taxon. Morphological studies have revealed that some features of the nuclear apparatus of P. sonneborni correspond to the P. aurelia spp. complex, while others are similar to P. jenningsi and P. schewiakoffi. The observed discordance indicates rapid splitting of the P. aurelia-P. jenningsi-P. schewiakoffi group, in which genetic, morphological, and molecular boundaries between species are not congruent. Copyright © 2015 Elsevier GmbH. All rights reserved.

Using Charge Distributions to "Immerse" Your Classroom in an Electric Field

Science.gov (United States)

Gaffney, Jon D. H.; Richards, Evan; Foote, Kathleen; Beichner, Robert J.

2013-01-01

Because electric fields are both invisible and three dimensional, they can be quite difficult to introduce to students. Simple diagrams are unable to convey the complexity or depth of the field, and computer simulations in isolation do not provide a familiar spatial context for students to understand what they see. Through "immersing"…

Interaction with virtual crowd in Immersive and semi‐Immersive Virtual Reality systems

OpenAIRE

Kyriakou, Marios; Pan, Xueni; Chrysanthou, Yiorgos

2016-01-01

This study examines attributes of virtual human behavior that may increase the plausibility of a simulated crowd and affect the user's experience in Virtual Reality. Purpose-developed experiments in both Immersive and semi-Immersive Virtual Reality systems queried the impact of collision and basic interaction between real-users and the virtual crowd and their effect on the apparent realism and ease of navigation within Virtual Reality (VR). Participants' behavior and subjective measurements i...

Immersion in Movement-Based Interaction

Science.gov (United States)

Pasch, Marco; Bianchi-Berthouze, Nadia; van Dijk, Betsy; Nijholt, Anton

The phenomenon of immersing oneself into virtual environments has been established widely. Yet to date (to our best knowledge) the physical dimension has been neglected in studies investigating immersion in Human-Computer Interaction (HCI). In movement-based interaction the user controls the interface via body movements, e.g. direct manipulation of screen objects via gestures or using a handheld controller as a virtual tennis racket. It has been shown that physical activity affects arousal and that movement-based controllers can facilitate engagement in the context of video games. This paper aims at identifying movement features that influence immersion. We first give a brief survey on immersion and movement-based interfaces. Then, we report results from an interview study that investigates how users experience their body movements when interacting with movement-based interfaces. Based on the interviews, we identify four movement-specific features. We recommend them as candidates for further investigation.

Immersion lithography defectivity analysis at DUV inspection wavelength

Science.gov (United States)

Golan, E.; Meshulach, D.; Raccah, N.; Yeo, J. Ho.; Dassa, O.; Brandl, S.; Schwarz, C.; Pierson, B.; Montgomery, W.

2007-03-01

Significant effort has been directed in recent years towards the realization of immersion lithography at 193nm wavelength. Immersion lithography is likely a key enabling technology for the production of critical layers for 45nm and 32nm design rule (DR) devices. In spite of the significant progress in immersion lithography technology, there remain several key technology issues, with a critical issue of immersion lithography process induced defects. The benefits of the optical resolution and depth of focus, made possible by immersion lithography, are well understood. Yet, these benefits cannot come at the expense of increased defect counts and decreased production yield. Understanding the impact of the immersion lithography process parameters on wafer defects formation and defect counts, together with the ability to monitor, control and minimize the defect counts down to acceptable levels is imperative for successful introduction of immersion lithography for production of advanced DR's. In this report, we present experimental results of immersion lithography defectivity analysis focused on topcoat layer thickness parameters and resist bake temperatures. Wafers were exposed on the 1150i-α-immersion scanner and 1200B Scanner (ASML), defect inspection was performed using a DUV inspection tool (UVision TM, Applied Materials). Higher sensitivity was demonstrated at DUV through detection of small defects not detected at the visible wavelength, indicating on the potential high sensitivity benefits of DUV inspection for this layer. The analysis indicates that certain types of defects are associated with different immersion process parameters. This type of analysis at DUV wavelengths would enable the optimization of immersion lithography processes, thus enabling the qualification of immersion processes for volume production.

Immersive Technologies and Language Learning

Science.gov (United States)

Blyth, Carl

2018-01-01

This article briefly traces the historical conceptualization of linguistic and cultural immersion through technological applications, from the early days of locally networked computers to the cutting-edge technologies known as virtual reality and augmented reality. Next, the article explores the challenges of immersive technologies for the field…

Learning immersion without getting wet

Science.gov (United States)

Aguilera, Julieta C.

2012-03-01

This paper describes the teaching of an immersive environments class on the Spring of 2011. The class had students from undergraduate as well as graduate art related majors. Their digital background and interests were also diverse. These variables were channeled as different approaches throughout the semester. Class components included fundamentals of stereoscopic computer graphics to explore spatial depth, 3D modeling and skeleton animation to in turn explore presence, exposure to formats like a stereo projection wall and dome environments to compare field of view across devices, and finally, interaction and tracking to explore issues of embodiment. All these components were supported by theoretical readings discussed in class. Guest artists presented their work in Virtual Reality, Dome Environments and other immersive formats. Museum professionals also introduced students to space science visualizations, which utilize immersive formats. Here I present the assignments and their outcome, together with insights as to how the creation of immersive environments can be learned through constraints that expose students to situations of embodied cognition.

A computational approach to modeling cellular-scale blood flow in complex geometry

Science.gov (United States)

Balogh, Peter; Bagchi, Prosenjit

2017-04-01

We present a computational methodology for modeling cellular-scale blood flow in arbitrary and highly complex geometry. Our approach is based on immersed-boundary methods, which allow modeling flows in arbitrary geometry while resolving the large deformation and dynamics of every blood cell with high fidelity. The present methodology seamlessly integrates different modeling components dealing with stationary rigid boundaries of complex shape, moving rigid bodies, and highly deformable interfaces governed by nonlinear elasticity. Thus it enables us to simulate 'whole' blood suspensions flowing through physiologically realistic microvascular networks that are characterized by multiple bifurcating and merging vessels, as well as geometrically complex lab-on-chip devices. The focus of the present work is on the development of a versatile numerical technique that is able to consider deformable cells and rigid bodies flowing in three-dimensional arbitrarily complex geometries over a diverse range of scenarios. After describing the methodology, a series of validation studies are presented against analytical theory, experimental data, and previous numerical results. Then, the capability of the methodology is demonstrated by simulating flows of deformable blood cells and heterogeneous cell suspensions in both physiologically realistic microvascular networks and geometrically intricate microfluidic devices. It is shown that the methodology can predict several complex microhemodynamic phenomena observed in vascular networks and microfluidic devices. The present methodology is robust and versatile, and has the potential to scale up to very large microvascular networks at organ levels.

Forcing clique immersions through chromatic number

OpenAIRE

Gauthier, Gregory; Le, Tien-Nam; Wollan, Paul

2017-01-01

Building on recent work of Dvo\\v{r}\\'ak and Yepremyan, we show that every simple graph of minimum degree $7t+7$ contains $K_t$ as an immersion and that every graph with chromatic number at least $3.54t + 4$ contains $K_t$ as an immersion. We also show that every graph on $n$ vertices with no stable set of size three contains $K_{2\\lfloor n/5 \\rfloor}$ as an immersion.

Application of vacuum-assisted closure in seawater-immersed wound treatment under different negative pressures.

Science.gov (United States)

Cao, L; Peng, M M; Sun, J J; Yu, X C; Shi, B

2015-06-11

The therapeutic effect of vacuum-assisted closure (VAC) has been confirmed in many types of complex wounds, but there are few relevant reports regarding seawater-immersed wounds. The aim of this study was to determine the effect of VAC on seawater-immersed wound healing under different negative pressures and explore the optimal negative pressure value. Four purebred miniature pigs were used as the experimental animal models. Four acute, symmetrical wounds were made on each side of the spine and designated as the experimental group (wounds with 2 h of seawater immersion) and the control group (wounds without seawater immersion). Wounds were divided into a conventional dressing group and 3 further groups with different VAC therapies (negative pressure at either 120, 180, or 240 mmHg). The extent of wound healing, and speed of granulation growth and re-epithelialization were measured. Bacterial flora distribution in the wounds was observed, and fibronectin levels in the exudate of the wounds were tested. Results showed that seawater immersion aggravated wound injury and that VAC therapy with 180 mmHg negative pressure induced the fastest epidermis migration, obvious edema elimination, significant capillary proliferation, and the highest level of fibronectin, and that in wounds, the proportion of Gram-negative bacteria tended to decrease and that of Gram-positive bacteria tended to increase. Our results show that VAC promotes seawater-immersed wound healing and that 180 mmHg negative pressure may be optimal for wound healing.

Designing immersion exhibits as border-crossing environments

DEFF Research Database (Denmark)

Mortensen, Marianne Foss

2010-01-01

be applied to achieve an understanding of the immersion exhibit form. The argument proceeds by demonstrating how the characteristics of immersion exhibits, and visitors to them, classify them as microcultures, and examining the implications of this for exhibit design using a hypothetical immersion exhibit...

Complex variable boundary elements for fluid flow; Robni elementi kompleksne spremenljivke za pretok fluidov

Energy Technology Data Exchange (ETDEWEB)

Bizjak, D; Alujevic, A [Institut ' Jozef Stefan' , Ljubljana (Yugoslavia)

1988-07-01

The Complex Variable Boundary Element Method is a numerical method for solving two-dimensional problems of Laplace or Poisson type. It is based on the theory of analytic functions. This paper resumes the basic facts about the method. Application of the method to the stationary incompressible irrotational flow is carried out after that. At the end, a sample problem of flow through an abrupt area change channel is shown. (author)

"A Pesar De Las Fronteras"/"In Spite of the Boundaries": Exploring Solidarity in the Context of International Service Immersion

Science.gov (United States)

Gates, Alice B.; Fletcher, C. Vail; Ruíz-Tolento, María Guadalupe; Goble, Laura; Velloso, Tadeu

2014-01-01

The move to "internationalize" United States universities has contributed to increased interest in global service-learning. This article presents qualitative data collected by a team of faculty and students during a service immersion in Nicaragua. The solidarity model of service-learning attempts to address shortcomings of earlier…

Reshaping Spectatorship: Immersive and Distributed Aesthetics

Directory of Open Access Journals (Sweden)

Edwina Bartlem

2005-01-01

Full Text Available Although discourses of immersive aesthetics and distributed aesthetics may evoke associations with different media, creative processes, modes of audience engagement and even political ideologies, artists using these aesthetics often share similar interests in transforming and enhancing notions of the body and perception through technological intervention. This paper undertakes a comparison between immersive and distributed aesthetics in relation to Virtual Reality (VR and Networked Art (net.art, particularly networked installation art. It focuses on the ways in which both VR and networked installations immerse the viewer in states of perceptual and cognitive transition. Central to this article is the argument that VR and net.art are able to generate immersive experiences in the viewer by creating the sensation of being (tele-present in an electronically mediated environment that is illusionistic and sometimes remote from the physical body of the participant. Furthermore, the immersive and distributed aesthetics generated by specific VR and net.art projects have revolutionary consequences for traditional aesthetic theories of spectatorship and art appreciation that assert the need for critical and physical distance.

Reorganization of the 3D matrix of polyelectrolytes complexes of chitosan/chondroitin sulfate swollen in different conditions of pH and immersion time

International Nuclear Information System (INIS)

Fajardo, Andre R.; Piai, Juliana F.; Rubira, Adley F.; Muniz, Edvani C.

2009-01-01

The chitosan (CT), a polysaccharide that has excellent properties for use as biomaterials, shows cationic nature and properties of high charge density in acidic solutions, thus CT can form complex polyelectrolyte (PEC) with polyanionic moieties such as the chondroitin sulfate (CS), a key component of cartilage matrix. We studied the reorganization of chains on 3D matrix of CT/CS PEC at swollen state in different conditions of pH and immersion time. It was verified that this PEC (QT/CS) has the capacity to reorganize its 3D matrix but it depends of the pH of the medium in which it is swelled and the time that remains immersed. The reorganization of the 3D matrix is caused by the reordering of the chains forming the PEC after the release of the CS, that occurs mainly at pH values higher than or close to the pKa of CT (pKa CT) . Such reorganization was detected by X-ray diffraction profiles and allows an increase in crystallinity, thermal stability and pore size of the PEC. This shows that the PEC produced can be processed to suit its use as bio material, applied i.e. as drugs release devices. (author)

Reorganization of the 3D matrix of polyelectrolytes complexes of chitosan/chondroitin sulfate swollen in different conditions of pH and immersion time

Energy Technology Data Exchange (ETDEWEB)

Fajardo, Andre R.; Piai, Juliana F.; Rubira, Adley F.; Muniz, Edvani C., E-mail: ecmuniz@uem.b [Universidade Estadual de Maringa (DG/UEM), PR (Brazil). Dept. de Quimica. Grupo de Materiais Polimericos e Compositos

2009-07-01

The chitosan (CT), a polysaccharide that has excellent properties for use as biomaterials, shows cationic nature and properties of high charge density in acidic solutions, thus CT can form complex polyelectrolyte (PEC) with polyanionic moieties such as the chondroitin sulfate (CS), a key component of cartilage matrix. We studied the reorganization of chains on 3D matrix of CT/CS PEC at swollen state in different conditions of pH and immersion time. It was verified that this PEC (QT/CS) has the capacity to reorganize its 3D matrix but it depends of the pH of the medium in which it is swelled and the time that remains immersed. The reorganization of the 3D matrix is caused by the reordering of the chains forming the PEC after the release of the CS, that occurs mainly at pH values higher than or close to the pKa of CT (pKa CT) . Such reorganization was detected by X-ray diffraction profiles and allows an increase in crystallinity, thermal stability and pore size of the PEC. This shows that the PEC produced can be processed to suit its use as bio material, applied i.e. as drugs release devices. (author)

FIJI: A Framework for the Immersion-Journalism Intersection

OpenAIRE

Hardee, Gary M.; McMahan, Ryan P.

2017-01-01

As journalists experiment with developing immersive journalism—first-person, interactive experiences of news events—guidelines are needed to help bridge a disconnect between the requirements of journalism and the capabilities of emerging technologies. Many journalists need to better understand the fundamental concepts of immersion and the capabilities and limitations of common immersive technologies. Similarly, developers of immersive journalism works need to know the fundamentals that define...

A sharp interface immersed boundary method for vortex-induced vibration in the presence of thermal buoyancy

Science.gov (United States)

Garg, Hemanshul; Soti, Atul K.; Bhardwaj, Rajneesh

2018-02-01

We report the development of an in-house fluid-structure interaction solver and its application to vortex-induced vibration (VIV) of an elastically mounted cylinder in the presence of thermal buoyancy. The flow solver utilizes a sharp interface immersed boundary method, and in the present work, we extend it to account for the thermal buoyancy using Boussinesq approximation and couple it with a spring-mass system of the VIV. The one-way coupling utilizes an explicit time integration scheme and is computationally efficient. We present benchmark code verifications of the solver for natural convection, mixed convection, and VIV. In addition, we verify a coupled VIV-thermal buoyancy problem at a Reynolds number, Re = 150. We numerically demonstrate the onset of the VIV in the presence of the thermal buoyancy for an insulated cylinder at low Re. The buoyancy is induced by two parallel plates, kept in the direction of flow and symmetrically placed around the cylinder. The plates are maintained at the hot and cold temperature to the same degree relative to the ambient. In the absence of the thermal buoyancy (i.e., the plates are at ambient temperature), the VIV does not occur for Re ≤ 20 due to stable shear layers. By contrast, the thermal buoyancy induces flow instability and the vortex shedding helps us to achieve the VIV at Re ≤ 20, lower than the critical value of Re (≈21.7), reported in the literature, for a self-sustained VIV in the absence of the thermal buoyancy. The present simulations show that the lowest Re to achieve VIV in the presence of the thermal buoyancy is around Re ≈ 3, at Richardson number, Ri = 1. We examine the effect of the reduced velocity (UR), mass ratio (m), Prandtl number (Pr), Richardson number (Ri) on the displacement of the cylinder, lift coefficient, oscillation frequency, the phase difference between displacement and lift force, and wake structures. We obtain a significantly larger vibration amplitude of the cylinder over a wide

Immersion and Gameplay Experience: A Contingency Framework

Directory of Open Access Journals (Sweden)

Daniel Örtqvist

2010-01-01

Full Text Available The nature of the relationship between immersion and gameplay experience is investigated, focusing primarily on the literature related to flow. In particular, this paper proposes that immersion and gameplay experience are conceptually different, but empirically positively related through mechanisms related to flow. Furthermore, this study examines gamers' characteristics to determine the influence between immersion and gameplay experiences. The study involves 48 observations in one game setting. Regression analyses including tests for moderation and simple slope analysis are used to reveal gamers' age, experience, and understanding of the game, which moderate the relationship between immersion and gameplay experience. The results suggest that immersion is more positive for gameplay experience when the gamer lacks experience and understanding of the game as well as when the gamer is relatively older. Implications and recommendations for future research are discussed at length in the paper.

On the compactification of the moduli space of branched minimal immersions of S2 into S4

International Nuclear Information System (INIS)

Loo, B.

1992-01-01

We study the natural compactification of the moduli space of branched minimal immersions of S 2 into S 4 . We prove that the (compactified) moduli space M d is a connected projective variety of dimension 2d+4. It is irreducible when d=1,2, and it has two irreducible components when d ≥ 3. We discuss the bubbling phenomenon at the boundary of the moduli space. (author). 26 refs, 3 figs

Prediction of radiation ratio and sound transmission of complex extruded panel using wavenumber domain Unite element and boundary element methods

International Nuclear Information System (INIS)

Kim, H; Ryue, J; Thompson, D J; Müller, A D

2016-01-01

Recently, complex shaped aluminium panels have been adopted in many structures to make them lighter and stronger. The vibro-acoustic behaviour of these complex panels has been of interest for many years but conventional finite element and boundary element methods are not efficient to predict their performance at higher frequencies. Where the cross-sectional properties of the panels are constant in one direction, wavenumber domain numerical analysis can be applied and this becomes more suitable for panels with complex cross-sectional geometries. In this paper, a coupled wavenumber domain finite element and boundary element method is applied to predict the sound radiation from and sound transmission through a double-layered aluminium extruded panel, having a typical shape used in railway carriages. The predicted results are compared with measured ones carried out on a finite length panel and good agreement is found. (paper)

Personal protective clothing against accidental immersion

Energy Technology Data Exchange (ETDEWEB)

Elliott, David; Tipton, Michael [Surrey Univ., Robens Inst. of Health and Safety, Guildford (United Kingdom)

1997-12-31

The requirements for protective clothing against accidental immersion are discussed and the advantages and limitations of the main types of immersion protection available are analysed. The variety of designs available reflects the various circumstances under which they may be used. In broad terms in the offshore industry these include the following activities: normal work without risk of immersion but with a possible need to abandon the rig or ship; work in areas where there is risk of accidentally falling into the sea; flying over the sea in a helicopter. The first response to sudden immersion in sea water, which must usually be considered to be cold, is a sudden gasp often followed by an immediate phase of uncontrolled breathing. Since control of ones breathing between and under the breaking waves is essential to staying alive, this is a critical time. After surviving this initial ``cold shock`` phase, the effects of body heat loss become hazardous. Protection against hypothermia has been the priority for those providing survival suits and protective clothing while the hazard of the immediate response to cold immersion has been unrecognised to a large extent. (UK)

L'expression orale apres treize ans d'immersion francaise (Oral Expression After Thirteen Years of French Immersion).

Science.gov (United States)

Pellerin, Micheline; Hammerly, Hector

1986-01-01

Conversations with six twelfth graders who had been in French immersion since kindergarten found a high rate of incorrect sentences, suggesting a faulty interlanguage fossilized at grade six and a need for immersion program revision. (MSE)

Development of the immersed sodium flowmeter

International Nuclear Information System (INIS)

Chen Daolong

1994-09-01

An immersed sodium flowmeter of the range 3 m 3 /h is developed. It is a flowmeter of entire-sealed construction, it can be operated in sodium. Its construction, the theoretical calculation of the calibration characteristic and the pressure loss, the test facility and the calibration test are presented in detail. It analytical expression of the calibration characteristic in the temperature limit 200∼600 degree C and the error analysis are given. The basic error of this immersed sodium flowmeter is below +-2.3% of the measuring range. The immersed sodium flowmeter can be used to resolve the sodium flowrate measuring problems of the in-reactor component of LMFBR, for example, the flowrate measuring of the in-reactor sodium purification loop, the flowrate measuring of the immersed sodium pump and the flowrate measuring of the in-reactor test component

Numerical Study on the Effect of Air–Sea–Land Interaction on the Atmospheric Boundary Layer in Coastal Area

Directory of Open Access Journals (Sweden)

Zixuan Yang

2018-02-01

Full Text Available We have performed large-eddy simulations (LES to study the effect of complex land topography on the atmospheric boundary layer (ABL in coastal areas. The areas under investigation are located at three beaches in Monterey Bay, CA, USA. The sharp-interface immersed boundary method is employed to resolve the land topography down to grid scale. We have considered real-time and what-if cases. In the real-time cases, measurement data and realistic land topographies are directly incorporated. In the what-if cases, the effects of different scenarios of wind speed, wind direction, and terrain pattern on the momentum flux at the beach are studied. The LES results are compared with simulations using the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS and field measurement data. We find that the land topography imposes a critical influence on the ABL in the coastal area. The momentum fluxes obtained from our LES agree with measurement data. Our results indicate the importance of capturing the effects of land topographies in simulations.

The pedagogical practices of a teacher of Portuguese Foreign Language (PLE in immersion and non-immersion context

Directory of Open Access Journals (Sweden)

Nildicéia Aparecida Rocha

2016-05-01

Full Text Available The aim of this paper is to present a reflection on the specifics of teaching Portuguese as a Foreign Language (PLE both in the context of immersion and outside it, from the observations carried out in two stages: first, the practice of a teacher PLE will be described in immersion situation at a university in the state of São Paulo, Brazil; and then practice the same teacher in a course of PLE out of the immersion context, at a university in Spain, in a provincial capital. In this sense, the teaching practice will be analyzed from a teacher of PLE in immersion situation and beyond when the didactic and pedagogical treatment of the inseparable relationship between language and culture within an intercultural communicative approach. It is a qualitative research in which it is a case of state, showing the practice of one teacher (research subjects in two socio-historically different contexts, but with the same approach. The survey results indicate that the teacher's practice in non-immersion context had to be re-signified to enable PLE learning in such a context. In fact, the teacher had to redefine their practice and deconstruct a belief and turn to the theory, according to their didactic and pedagogical and linguistic concerns, finding that the examination of social, historical and cultural data should always be the guiding and / or determinants as regards the teaching of a foreign language, in particular PLE out of immersion.

IQ-Station: A Low Cost Portable Immersive Environment

Energy Technology Data Exchange (ETDEWEB)

Eric Whiting; Patrick O' Leary; William Sherman; Eric Wernert

2010-11-01

The emergence of inexpensive 3D TV’s, affordable input and rendering hardware and open-source software has created a yeasty atmosphere for the development of low-cost immersive environments (IE). A low cost IE system, or IQ-station, fashioned from commercial off the shelf technology (COTS), coupled with a targeted immersive application can be a viable laboratory instrument for enhancing scientific workflow for exploration and analysis. The use of an IQ-station in a laboratory setting also has the potential of quickening the adoption of a more sophisticated immersive environment as a critical enabler in modern scientific and engineering workflows. Prior work in immersive environments generally required either a head mounted display (HMD) system or a large projector-based implementation both of which have limitations in terms of cost, usability, or space requirements. The solution presented here provides an alternative platform providing a reasonable immersive experience that addresses those limitations. Our work brings together the needed hardware and software to create a fully integrated immersive display and interface system that can be readily deployed in laboratories and common workspaces. By doing so, it is now feasible for immersive technologies to be included in researchers’ day-to-day workflows. The IQ-Station sets the stage for much wider adoption of immersive environments outside the small communities of virtual reality centers.

Immersion Pulmonary Edema in Female Triathletes

Directory of Open Access Journals (Sweden)

Eric A. Carter

2011-01-01

Full Text Available Pulmonary edema has been reported in SCUBA divers, apnea divers, and long-distance swimmers however, no instances of pulmonary edema in triathletes exist in the scientific literature. Pulmonary edema may cause seizures and loss of consciousness which in a water environment may become life threatening. This paper describes pulmonary edema in three female triathletes. Signs and symptoms including cough, fatigue, dyspnea, haemoptysis, and rales may occur within minutes of immersion. Contributing factors include hemodynamic changes due to water immersion, cold exposure, and exertion which elevate cardiac output, causing pulmonary capillary stress failure, resulting in extravasation of fluid into the airspace of the lung. Previous history is a major risk factor. Treatment involves immediate removal from immersion and in more serious cases, hospitalization, and oxygen administration. Immersion pulmonary edema is a critical environmental illness of which triathletes, race organizers, and medical staff, should be made aware.

Whole body cooling by immersion in water at moderate temperatures.

Science.gov (United States)

Marino, F; Booth, J

1998-06-01

This study investigated the potential use of whole body cooling by water immersion for lowering body temperatures prior to endurance exercise. Rectal temperature (Tre), mean skin temperature (Tsk), oxygen consumption (VO2), and ventilation (VE) were measured in 7 male and 3 female subjects who were immersed in a water bath for up to 60 min. Initial water temperature was 28.8+/-1.5 degrees C and decreased to 23.8+/-1.1 degrees C by the end of immersion. Pre-immersion Tre of 37.34+/-0.36 degrees C was not altered by 60 min water immersion but decreased to 36.64+/-0.34 degrees C at 3 min post immersion (p immersion. Reductions in Tre and Tsk resulted in reduced body heat content (Hc) of approximately 545 kJ (p immersion. VO2 and VE increased from pre-immersion values of 0.34+/-0.08 L x min(-1) and 6.2+/-1.4 L x min(-1) to 0.54+/-0.09 L x min(-) and 11.5+/-5.4 L x min(-1) at the end of immersion, respectively. Heart rate remained unchanged throughout immersion. These results indicate that whole body immersion in moderately cold water temperatures is an effective cooling maneuver for lowering body temperatures and body Hc in the absence of severe physiological responses generally associated with sudden cold stress.

A versatile embedded boundary adaptive mesh method for compressible flow in complex geometry

KAUST Repository

Almarouf, Mohamad Abdulilah Alhusain Alali

2017-02-25

We present an embedded ghost-fluid method for numerical solutions of the compressible Navier Stokes (CNS) equations in arbitrary complex domains. A PDE multidimensional extrapolation approach is used to reconstruct the solution in the ghost-fluid regions and imposing boundary conditions on the fluid-solid interface, coupled with a multi-dimensional algebraic interpolation for freshly cleared cells. The CNS equations are numerically solved by the second order multidimensional upwind method. Block-structured adaptive mesh refinement, implemented with the Chombo framework, is utilized to reduce the computational cost while keeping high resolution mesh around the embedded boundary and regions of high gradient solutions. The versatility of the method is demonstrated via several numerical examples, in both static and moving geometry, ranging from low Mach number nearly incompressible flows to supersonic flows. Our simulation results are extensively verified against other numerical results and validated against available experimental results where applicable. The significance and advantages of our implementation, which revolve around balancing between the solution accuracy and implementation difficulties, are briefly discussed as well.

A versatile embedded boundary adaptive mesh method for compressible flow in complex geometry

KAUST Repository

Almarouf, Mohamad Abdulilah Alhusain Alali; Samtaney, Ravi

2017-01-01

We present an embedded ghost-fluid method for numerical solutions of the compressible Navier Stokes (CNS) equations in arbitrary complex domains. A PDE multidimensional extrapolation approach is used to reconstruct the solution in the ghost-fluid regions and imposing boundary conditions on the fluid-solid interface, coupled with a multi-dimensional algebraic interpolation for freshly cleared cells. The CNS equations are numerically solved by the second order multidimensional upwind method. Block-structured adaptive mesh refinement, implemented with the Chombo framework, is utilized to reduce the computational cost while keeping high resolution mesh around the embedded boundary and regions of high gradient solutions. The versatility of the method is demonstrated via several numerical examples, in both static and moving geometry, ranging from low Mach number nearly incompressible flows to supersonic flows. Our simulation results are extensively verified against other numerical results and validated against available experimental results where applicable. The significance and advantages of our implementation, which revolve around balancing between the solution accuracy and implementation difficulties, are briefly discussed as well.

Immersion Ethnography of Elites

DEFF Research Database (Denmark)

Harrington, Brooke

2016-01-01

This chapter examines an innovative form of data-gathering that brings together two of the greatest methodological challenges social scientists face: conducting classical immersion ethnography and gaining access to elites. The difficulties of accessing elites for research purposes have been well......-documented (Conti and O’Neill 2007; Gilding 2010; Harrington 2003). There has been less scholarly discussion of the challenges posed by traditional ethnography, a method whose claim to scientific status is based on the length and depth of the investigator’s immersion in an organization or culture....

Formation of Wear Resistant Steel Surfaces by Plasma Immersion Ion Implantation

Science.gov (United States)

Mändl, S.; Rauschenbach, B.

2003-08-01

Plasma immersion ion implantation (PIII) is a versatile and fast method for implanting energetic ions into large and complex shaped three-dimensional objects where the ions are accelerated by applying negative high voltage pulses to a substrate immersed in a plasma. As the line-of-sight restrictions of conventional implanters are circumvented, it results in a fast and cost-effective technology. Implantation of nitrogen at 30 - 40 keV at moderate temperatures of 200 - 400 °C into steel circumvents the diminishing thermal nitrogen activation encountered, e.g., in plasma nitriding in this temperature regime, thus enabling nitriding of additional steel grades. Nitride formation and improvement of the mechanical properties after PIII are presented for several steel grades, including AISI 316Ti (food industry), AISI D2 (used for bending tools) and AISI 1095 (with applications in the textile industry).

Formation of Wear Resistant Steel Surfaces by Plasma Immersion Ion Implantation

International Nuclear Information System (INIS)

Maendl, S.; Rauschenbach, B.

2003-01-01

Plasma immersion ion implantation (PIII) is a versatile and fast method for implanting energetic ions into large and complex shaped three-dimensional objects where the ions are accelerated by applying negative high voltage pulses to a substrate immersed in a plasma. As the line-of-sight restrictions of conventional implanters are circumvented, it results in a fast and cost-effective technology. Implantation of nitrogen at 30 - 40 keV at moderate temperatures of 200 - 400 deg. C into steel circumvents the diminishing thermal nitrogen activation encountered, e.g., in plasma nitriding in this temperature regime, thus enabling nitriding of additional steel grades. Nitride formation and improvement of the mechanical properties after PIII are presented for several steel grades, including AISI 316Ti (food industry), AISI D2 (used for bending tools) and AISI 1095 (with applications in the textile industry)

KinImmerse: Macromolecular VR for NMR ensembles

Directory of Open Access Journals (Sweden)

Vinson E Claire

2009-02-01

Full Text Available Abstract Background In molecular applications, virtual reality (VR and immersive virtual environments have generally been used and valued for the visual and interactive experience – to enhance intuition and communicate excitement – rather than as part of the actual research process. In contrast, this work develops a software infrastructure for research use and illustrates such use on a specific case. Methods The Syzygy open-source toolkit for VR software was used to write the KinImmerse program, which translates the molecular capabilities of the kinemage graphics format into software for display and manipulation in the DiVE (Duke immersive Virtual Environment or other VR system. KinImmerse is supported by the flexible display construction and editing features in the KiNG kinemage viewer and it implements new forms of user interaction in the DiVE. Results In addition to molecular visualizations and navigation, KinImmerse provides a set of research tools for manipulation, identification, co-centering of multiple models, free-form 3D annotation, and output of results. The molecular research test case analyzes the local neighborhood around an individual atom within an ensemble of nuclear magnetic resonance (NMR models, enabling immersive visual comparison of the local conformation with the local NMR experimental data, including target curves for residual dipolar couplings (RDCs. Conclusion The promise of KinImmerse for production-level molecular research in the DiVE is shown by the locally co-centered RDC visualization developed there, which gave new insights now being pursued in wider data analysis.

A simple atmospheric boundary layer model applied to large eddy simulations of wind turbine wakes

DEFF Research Database (Denmark)

Troldborg, Niels; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

2014-01-01

A simple model for including the influence of the atmospheric boundary layer in connection with large eddy simulations of wind turbine wakes is presented and validated by comparing computed results with measurements as well as with direct numerical simulations. The model is based on an immersed...... boundary type technique where volume forces are used to introduce wind shear and atmospheric turbulence. The application of the model for wake studies is demonstrated by combining it with the actuator line method, and predictions are compared with field measurements. Copyright © 2013 John Wiley & Sons, Ltd....

Immersion Strategies.

Science.gov (United States)

Lorenz, Eileen B.

Four classroom activities useful for language immersion instruction are described and specific applications and extensions are noted. All are best used to teach content and language at the same time. The first, entitled "Think-Pair-Share," is a cooperative learning technique that increases student participation in classroom experiences and…

Foreign language learning in immersive virtual environments

Science.gov (United States)

Chang, Benjamin; Sheldon, Lee; Si, Mei; Hand, Anton

2012-03-01

Virtual reality has long been used for training simulations in fields from medicine to welding to vehicular operation, but simulations involving more complex cognitive skills present new design challenges. Foreign language learning, for example, is increasingly vital in the global economy, but computer-assisted education is still in its early stages. Immersive virtual reality is a promising avenue for language learning as a way of dynamically creating believable scenes for conversational training and role-play simulation. Visual immersion alone, however, only provides a starting point. We suggest that the addition of social interactions and motivated engagement through narrative gameplay can lead to truly effective language learning in virtual environments. In this paper, we describe the development of a novel application for teaching Mandarin using CAVE-like VR, physical props, human actors and intelligent virtual agents, all within a semester-long multiplayer mystery game. Students travel (virtually) to China on a class field trip, which soon becomes complicated with intrigue and mystery surrounding the lost manuscript of an early Chinese literary classic. Virtual reality environments such as the Forbidden City and a Beijing teahouse provide the setting for learning language, cultural traditions, and social customs, as well as the discovery of clues through conversation in Mandarin with characters in the game.

A comparative study of various inflow boundary conditions and turbulence models for wind turbine wake predictions

Science.gov (United States)

Tian, Lin-Lin; Zhao, Ning; Song, Yi-Lei; Zhu, Chun-Ling

2018-05-01

This work is devoted to perform systematic sensitivity analysis of different turbulence models and various inflow boundary conditions in predicting the wake flow behind a horizontal axis wind turbine represented by an actuator disc (AD). The tested turbulence models are the standard k-𝜀 model and the Reynolds Stress Model (RSM). A single wind turbine immersed in both uniform flows and in modeled atmospheric boundary layer (ABL) flows is studied. Simulation results are validated against the field experimental data in terms of wake velocity and turbulence intensity.

Fuselage Boundary Layer Ingestion Propulsion Applied to a Thin Haul Commuter Aircraft for Optimal Efficiency

Science.gov (United States)

Mikic, Gregor Veble; Stoll, Alex; Bevirt, JoeBen; Grah, Rok; Moore, Mark D.

2016-01-01

Theoretical and numerical aspects of aerodynamic efficiency of propulsion systems are studied. Focus is on types of propulsion that closely couples to the aerodynamics of the complete vehicle. We discuss the effects of local flow fields, which are affected both by conservative flow acceleration as well as total pressure losses, on the efficiency of boundary layer immersed propulsion devices. We introduce the concept of a boundary layer retardation turbine that helps reduce skin friction over the fuselage. We numerically investigate efficiency gains offered by boundary layer and wake interacting devices. We discuss the results in terms of a total energy consumption framework and show that efficiency gains offered depend on all the elements of the propulsion system.

Buckling transition and boundary layer in non-Euclidean plates.

Science.gov (United States)

Efrati, Efi; Sharon, Eran; Kupferman, Raz

2009-07-01

Non-Euclidean plates are thin elastic bodies having no stress-free configuration, hence exhibiting residual stresses in the absence of external constraints. These bodies are endowed with a three-dimensional reference metric, which may not necessarily be immersible in physical space. Here, based on a recently developed theory for such bodies, we characterize the transition from flat to buckled equilibrium configurations at a critical value of the plate thickness. Depending on the reference metric, the buckling transition may be either continuous or discontinuous. In the infinitely thin plate limit, under the assumption that a limiting configuration exists, we show that the limit is a configuration that minimizes the bending content, among all configurations with zero stretching content (isometric immersions of the midsurface). For small but finite plate thickness, we show the formation of a boundary layer, whose size scales with the square root of the plate thickness and whose shape is determined by a balance between stretching and bending energies.

System Architecture and Mobility Management for Mobile Immersive Communications

Directory of Open Access Journals (Sweden)

Mehran Dowlatshahi

2007-01-01

Full Text Available We propose a system design for delivery of immersive communications to mobile wireless devices based on a distributed proxy model. It is demonstrated that this architecture addresses key technical challenges for the delivery of these services, that is, constraints on link capacity and power consumption in mobile devices. However, additional complexity is introduced with respect to application layer mobility management. The paper proposes three possible methods for updating proxy assignments in response to mobility management and compares the performance of these methods.

The Influence of Hand Immersion Duration on Manual Performance.

Science.gov (United States)

Ray, Matthew; Sanli, Elizabeth; Brown, Robert; Ennis, Kerri Ann; Carnahan, Heather

2017-08-01

To investigate the effect of hand immersion duration on manipulative ability and tactile sensitivity. Individuals in maritime settings often work with hands that have been immersed in water. Although research has shown that hand immersion duration differentially impacts skin adhesion and tactile sensitivity, the effect of hand immersion on manipulative ability has not been directly tested. Given how critical manipulative ability is for the safety and performance of those working at sea, the effect of hand immersion duration on manual performance was investigated. Tests of manipulative ability (Purdue Pegboard, Grooved Pegboard, reef knot untying) and tactile sensitivity (Touch-Test) were completed following no-exposure, short-exposure, and long-exposure hand immersions in thermoneutral water. Compared to the no immersion condition, the Purdue Pegboard performance was reduced in both immersion conditions (short exposure, -11%; long exposure, -8%). A performance decrement was only observed in the short exposure condition (+15% in time to complete task) for the reef knot untying task. There were no statistical differences in the Grooved Pegboard or Touch-Test scores between exposure conditions. Immersing the hands in water decreases manipulative ability except for when object properties reduce the slipperiness between the hand and object. Manual performance in a wet environment may be conserved by designing tools and objects with edges and textures that can offset the slipperiness of wet hands. To maintain safety, the time requirements for working with wet hands needs to be considered.

46 CFR 199.214 - Immersion suits and thermal protective aids.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Immersion suits and thermal protective aids. 199.214... Passenger Vessels § 199.214 Immersion suits and thermal protective aids. (a) Each passenger vessel must... an immersion suit. (c) The immersion suits and thermal protective aids required under paragraphs (a...

The Balancing Act of Bilingual Immersion

Science.gov (United States)

Hadi-Tabassum, Samina

2005-01-01

Hadi-Tabassum believes having a separate life context for each language she learned in childhood enabled her to switch easily among five different tongues. She states that the success of dual immersion bilingual programs is largely dependent on whether they immerse students in each of the involved languages separately and help students have a…

Immersion microcalorimetry of a carbon black

International Nuclear Information System (INIS)

Mendelbaum, Georges

1966-01-01

This research thesis first reports a detailed bibliographical study on various topics (fabrication of carbon black, oxidation, immersion heat, adsorptions, main existing theories, and thermodynamics) and then the development of immersion and adsorption microcalorimetry apparatuses aimed at studying the surface of a carbon black and the influence of the oxidation of this carbon black on the adsorption of polar and non-polar solvents. Immersion heats of a raw or oxidised carbon black have been measured in water, in cyclohexane and in methanol. The adsorption of methanol at 20 C and that of nitrogen at -196 C have also been measured. The author outlines that degassing conditions had to be taken into account before performing measurements [fr

Effects of Aspect Ratio on Water Immersion into Deep Silica Nanoholes.

Science.gov (United States)

Zheng, Jing; Zhang, Junqiao; Tan, Lu; Li, Debing; Huang, Liangliang; Wang, Qi; Liu, Yingchun

2016-08-30

Understanding the influence of aspect ratio on water immersion into silica nanoholes is of significant importance to the etching process of semiconductor fabrication and other water immersion-related physical and biological processes. In this work, the processes of water immersion into silica nanoholes with different height/width aspect ratios (ϕ = 0.87, 1.92, 2.97, 4.01, 5.06) and different numbers of water molecules (N = 9986, 19972, 29958, 39944) were studied by molecular dynamics simulations. A comprehensive analysis has been conducted about the detailed process of water immersion and the influence of aspect ratios on water immersion rates. Five distinguishable stages were identified for the immersion process with all studied models. The results reveal that water can easily immerse into the silica nanoholes with larger ϕ and smaller N. The calculation also suggests that aspect ratios have a greater effect on water immersion rates for larger N numbers. The mechanism of the water immersion process is discussed in this work. We also propose a mathematical model to correlate the complete water immersion process for different aspect ratios.

Metal ion implantation: Conventional versus immersion

International Nuclear Information System (INIS)

Brown, I.G.; Anders, A.; Anders, S.; Dickinson, M.R.; MacGill, R.A.

1994-01-01

Vacuum-arc-produced metal plasma can be used as the ion feedstock material in an ion source for doing conventional metal ion implantation, or as the immersing plasma for doing plasma immersion ion implantation. The basic plasma production method is the same in both cases; it is simple and efficient and can be used with a wide range of metals. Vacuum arc ion sources of different kinds have been developed by the authors and others and their suitability as a metal ion implantation tool has been well established. Metal plasma immersion surface processing is an emerging tool whose characteristics and applications are the subject of present research. There are a number of differences between the two techniques, both in the procedures used and in the modified surfaces created. For example, the condensibility of metal plasma results in thin film formation and subsequent energetic implantation is thus done through the deposited layer; in the usual scenario, this recoil implantation and the intermixing it produces is a feature of metal plasma immersion but not of conventional energetic ion implantation. Metal plasma immersion is more suited (but not limited) to higher doses (>10 17 cm -2 ) and lower energies (E i < tens of keV) than the usual ranges of conventional metal ion implantation. These and other differences provide these vacuum-arc-based surface modification tools with a versatility that enhances the overall technological attractiveness of both

Story Immersion in a Health Videogame for Childhood Obesity Prevention.

Science.gov (United States)

Lu, Amy Shirong; Thompson, Debbe; Baranowski, Janice; Buday, Richard; Baranowski, Tom

2012-02-15

Stories can serve as powerful tools for health interventions. Story immersion refers to the experience of being absorbed in a story. This is among the first studies to analyze story immersion's role in health videogames among children by addressing two main questions: Will children be more immersed when the main characters are similar to them? Do increased levels of immersion relate to more positive health outcomes? Eighty-seven 10-12-year-old African-American, Caucasian, and Hispanic children from Houston, TX, played a health videogame, "Escape from Diab" (Archimage, Houston, TX), featuring a protagonist with both African-American and Hispanic phenotypic features. Children's demographic information, immersion, and health outcomes (i.e., preference, motivation, and self-efficacy) were recorded and then correlated and analyzed. African-American and Hispanic participants reported higher immersion scores than Caucasian participants ( P = 0.01). Story immersion correlated positively ( P values videogame characters and players enhanced immersion and several health outcomes. Effectively embedding characters with similar phenotypic features to the target population in interactive health videogame narratives may be important when motivating children to adopt obesity prevention behaviors.

Comparison of phase boundaries between kagomé and honeycomb superconducting wire networks

Science.gov (United States)

Xiao, Yi; Huse, David A.; Chaikin, Paul M.; Higgins, Mark J.; Bhattacharya, Shobo; Spencer, David

2002-06-01

We measure resistively the mean-field superconducting-normal phase boundaries of both kagomé and honeycomb wire networks immersed in a transverse magnetic field. In addition to their agreement with theory about the overall shapes of phase diagrams, they show striking one-to-one correspondence between the cusps in the honeycomb phase boundary and those in the kagomé curve. This correspondence is due to their geometric arrangements and agrees with Lin and Nori's recent calculation. We also find that for the frustrated honeycomb network at f=1/2, the current patterns in the superconducting phase differ between the low-temperature London regime and the higher-temperature Ginzburg-Landau regime near Tc.

Effect of inlet conditions for numerical modelling of the urban boundary layer

Science.gov (United States)

Gnatowska, Renata

2018-01-01

The paper presents the numerical results obtained with the use of the ANSYS FLUENT commercial code for analysing the flow structure around two rectangular inline surface-mounted bluff bodies immersed in a boundary layer. The effects of the inflow boundary layer for the accuracy of the numerical modelling of the flow field around a simple system of objects are described. The analysis was performed for two concepts. In the former case, the inlet velocity profile was defined using the power law, whereas the kinetic and dissipation energy was defined from the equations according to Richards and Hoxey [1]. In the latter case, the inlet conditions were calculated for the flow over the rough area composed of the rectangular components.

Comparison of experimental target currents with analytical model results for plasma immersion ion implantation

International Nuclear Information System (INIS)

En, W.G.; Lieberman, M.A.; Cheung, N.W.

1995-01-01

Ion implantation is a standard fabrication technique used in semiconductor manufacturing. Implantation has also been used to modify the surface properties of materials to improve their resistance to wear, corrosion and fatigue. However, conventional ion implanters require complex optics to scan a narrow ion beam across the target to achieve implantation uniformity. An alternative implantation technique, called Plasma Immersion Ion Implantation (PIII), immerses the target into a plasma. The ions are extracted from the plasma directly and accelerated by applying negative high-voltage pulses to the target. An analytical model of the voltage and current characteristics of a remote plasma is presented. The model simulates the ion, electron and secondary electron currents induced before, during and after a high voltage negative pulse is applied to a target immersed in a plasma. The model also includes analytical relations that describe the sheath expansion and collapse due to negative high voltage pulses. The sheath collapse is found to be important for high repetition rate pulses. Good correlation is shown between the model and experiment for a wide variety of voltage pulses and plasma conditions

Generating wind fluctuations for Large Eddy Simulation inflow boundary condition

International Nuclear Information System (INIS)

Bekele, S.A.; Hangan, H.

2004-01-01

Large Eddy Simulation (LES) studies of flows over bluff bodies immersed in a boundary layer wind environment require instantaneous wind characteristics. The influences of the wind environment on the building pressure distribution are a well-established fact in the experimental study of wind engineering. Measured wind data of full or model scale are available only at a limited number of points. A method of obtaining instantaneous wind data at all mesh points of the inlet boundary for LES computation is necessary. Herein previous and new wind inflow generation techniques are presented. The generated wind data is then applied to a LES computation of a channel flow. The characteristics of the generated wind fluctuations in comparison to the measured data and the properties of the flow field computed from these two wind data are discussed. (author)

Immersive Training Systems: Virtual Reality and Education and Training.

Science.gov (United States)

Psotka, Joseph

1995-01-01

Describes virtual reality (VR) technology and VR research on education and training. Focuses on immersion as the key added value of VR, analyzes cognitive variables connected to immersion, how it is generated in synthetic environments and its benefits. Discusses value of tracked, immersive visual displays over nonimmersive simulations. Contains 78…

Story Immersion in a Health Videogame for Childhood Obesity Prevention

Science.gov (United States)

Thompson, Debbe; Baranowski, Janice; Buday, Richard; Baranowski, Tom

2012-01-01

Abstract Objective Stories can serve as powerful tools for health interventions. Story immersion refers to the experience of being absorbed in a story. This is among the first studies to analyze story immersion's role in health videogames among children by addressing two main questions: Will children be more immersed when the main characters are similar to them? Do increased levels of immersion relate to more positive health outcomes? Subjects and Methods Eighty-seven 10–12-year-old African-American, Caucasian, and Hispanic children from Houston, TX, played a health videogame, “Escape from Diab” (Archimage, Houston, TX), featuring a protagonist with both African-American and Hispanic phenotypic features. Children's demographic information, immersion, and health outcomes (i.e., preference, motivation, and self-efficacy) were recorded and then correlated and analyzed. Results African-American and Hispanic participants reported higher immersion scores than Caucasian participants (P=0.01). Story immersion correlated positively (P valuesvideogame characters and players enhanced immersion and several health outcomes. Effectively embedding characters with similar phenotypic features to the target population in interactive health videogame narratives may be important when motivating children to adopt obesity prevention behaviors. PMID:24066276

Spectral Solutions of Self-adjoint Elliptic Problems with Immersed Interfaces

International Nuclear Information System (INIS)

Auchmuty, G.; Klouček, P.

2011-01-01

This paper describes a spectral representation of solutions of self-adjoint elliptic problems with immersed interfaces. The interface is assumed to be a simple non-self-intersecting closed curve that obeys some weak regularity conditions. The problem is decomposed into two problems, one with zero interface data and the other with zero exterior boundary data. The problem with zero interface data is solved by standard spectral methods. The problem with non-zero interface data is solved by introducing an interface space H Γ (Ω) and constructing an orthonormal basis of this space. This basis is constructed using a special class of orthogonal eigenfunctions analogously to the methods used for standard trace spaces by Auchmuty (SIAM J. Math. Anal. 38, 894–915, 2006). Analytical and numerical approximations of these eigenfunctions are described and some simulations are presented.

Exploring the Design Space of Immersive Urban Analytics

OpenAIRE

Chen, Zhutian; Wang, Yifang; Sun, Tianchen; Gao, Xiang; Chen, Wei; Pan, Zhigeng; Qu, Huamin; Wu, Yingcai

2017-01-01

Recent years have witnessed the rapid development and wide adoption of immersive head-mounted devices, such as HTC VIVE, Oculus Rift, and Microsoft HoloLens. These immersive devices have the potential to significantly extend the methodology of urban visual analytics by providing critical 3D context information and creating a sense of presence. In this paper, we propose an theoretical model to characterize the visualizations in immersive urban analytics. Further more, based on our comprehensiv...

Advancing Analytical and LES Based Predictions Of Turbulence Ingestion Noise in Complex Environments An Experimental Study

Science.gov (United States)

2017-09-14

to be a function of the proportion of the rotor disk area immersed in the turbulent field and its distribution across the rotor disk area. 15...strike location across the rotor disk is to change the sound level according to the degree of immersion of the rotor, and to shift the region of...rotors, in the absence of inflow turbulence, using trailing edge boundary layer modification devices known as finlets (Clark et al. AIAA Journal

Framework to Define Structure and Boundaries of Complex Health Intervention Systems: The ALERT Project

Directory of Open Access Journals (Sweden)

Elena Boriani

2017-07-01

Full Text Available Health intervention systems are complex and subject to multiple variables in different phases of implementation. This constitutes a concrete challenge for the application of translational science in real life. Complex systems as health-oriented interventions call for interdisciplinary approaches with carefully defined system boundaries. Exploring individual components of such systems from different viewpoints gives a wide overview and helps to understand the elements and the relationships that drive actions and consequences within the system. In this study, we present an application and assessment of a framework with focus on systems and system boundaries of interdisciplinary projects. As an example on how to apply our framework, we analyzed ALERT [an integrated sensors and biosensors’ system (BEST aimed at monitoring the quality, health, and traceability of the chain of the bovine milk], a multidisciplinary and interdisciplinary project based on the application of measurable biomarkers at strategic points of the milk chain for improved food security (including safety, human, and ecosystem health (1. In fact, the European food safety framework calls for science-based support to the primary producers’ mandate for legal, scientific, and ethical responsibility in food supply. Because of its multidisciplinary and interdisciplinary approach involving human, animal, and ecosystem health, ALERT can be considered as a One Health project. Within the ALERT context, we identified the need to take into account the main actors, interactions, and relationships of stakeholders to depict a simplified skeleton of the system. The framework can provide elements to highlight how and where to improve the project development when project evaluations are required.

Immersive Earth: Teaching Earth and Space with inexpensive immersive technology

Science.gov (United States)

Reiff, P. H.; Sumners, C.; Law, C. C.; Handron, K.

2003-12-01

In 1995 we pioneered "Space Update", the Digital Library for the rest of us", software that was so simple that a child could use it without a keyboard and yet would allow one-click updating of the daily earth and space science images without the dangers of having an open web browser on display. Thanks to NASA support, it allowed museums and schools to have a powerful exhibit for a tiny price. Over 40,000 disks in our series have been distributed so far to educators and the public. In 2003, with our partners we are again revolutionizing educational technology with a low-cost hardware and software solution to creating and displaying immersive content. Recently selected for funding as part of the REASoN competition, Immersive Earth is a partnership of scientists, museums, educators, and content providers. The hardware consists of a modest projector with a special fisheye lens to be used in an inflatable dome which many schools already have. This, coupled with a modest personal computer, can now easily project images and movies of earth and space, allows training students in 3-D content at a tiny fraction of the cost of a cave or fullscale dome theater. Another low-cost solution is the "Imove" system, where spherical movies can play on a personal computer, with the user changing the viewing direction with a joystick. We were the first to create immersive earth science shows, remain the leader in creating educational content that people want to see. We encourage people with "allsky" images or movies to bring it and see what it looks like inside a dome! Your content could be in our next show!

High performance Si immersion gratings patterned with electron beam lithography

Science.gov (United States)

Gully-Santiago, Michael A.; Jaffe, Daniel T.; Brooks, Cynthia B.; Wilson, Daniel W.; Muller, Richard E.

2014-07-01

Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error

Intrapericardial Denervation: Responses to Water Immersion in Rhesus Monkeys

Science.gov (United States)

McKeever, Kenneth H.; Keil, Lanny C.; Sandler, Harold

1995-01-01

Eleven anesthetized rhesus monkeys were used to study cardiovascular, renal, and endocrine alterations associated with 120 min of head-out water immersion. Five animals underwent complete intrapericardial denervation using the Randall technique, while the remaining six monkeys served as intact controls. Each animal was chronically instrumented with an electromagnetic flow probe on the ascending aorta, a strain gauge pressure transducer implanted in the apex of the left ventricle (LV), and electrocardiogram leads anchored to the chest wall and LV. During immersion, LV end-diastolic pressure, urine flow, glomerular filtration rate, sodium excretion, and circulating atrial natriuretic peptide (ANP) each increased (P less than 0.05) for intact and denervated monkeys. There were no alterations in free water clearance in either group during immersion, yet fractional excretion of free water increased (P less than 0.05) in the intact monkeys. Plasma renin activity (PRA) decreased (P less than 0.05) during immersion in intact monkeys but not the denervated animals. Plasma vasopressin (PVP) concentration decreased (P less than 0.05) during the first 30 min of immersion in both groups but was not distinguishable from control by 60 min of immersion in denervated monkeys. These data demonstrate that complete cardiac denervation does not block the rise in plasma ANP or prevent the natriuresis associated with head-out water immersion. The suppression of PVP during the first minutes of immersion after complete cardiac denervation suggests that extracardiac sensing mechanisms associated with the induced fluid shifts may be responsible for the findings.

Managing SMEs’ Collaboration Across Organizational Boundaries Within a Regional Business Ecosystem

DEFF Research Database (Denmark)

Radziwon, Agnieszka; Bogers, Marcel

2018-01-01

autonomy and control over the partners and indicate shared issues and responsibilities crucial for further ecosystem development. As a conclusion, we offer a set of recommendations both for managers and policymakers concerning general organizational requirements and governing structures.......’ perspective on managing and organizing inter-company collaboration within a regional business. We explore how purposefully managed mutual knowledge flows across organizational boundaries applied by SMEs contribute to the development of the ecosystem they are immersed in. Our key findings include insights...

Application of headspace and direct immersion solid-phase microextraction in the analysis of organothiophosphates related to the Chemical Weapons Convention from water and complex matrices.

Science.gov (United States)

Althoff, Marc André; Bertsch, Andreas; Metzulat, Manfred; Klapötke, Thomas M; Karaghiosoff, Konstantin L

2017-11-01

The successful application of headspace (HS) and direct immersion (DI) solid phase microextraction (SPME) for the unambiguous identification and characterization of a series of toxic thiophosphate esters, such as Amiton (I), from aqueous phases and complex matrices (e.g. grass and foliage) has been demonstrated. A Thermo Scientific gas chromatograph (GC) - tandem mass spectrometer (MS/MS) system with a TriPlus RSH® autosampler and a SPME tool was used to investigate the effect of different parameters that influence the extraction efficiency: e.g. pH of the sample matrix and extraction temperature. The developed methods were employed for the detection of several Amiton derivatives (Schedule II of the CWC) that are structurally closely related to each other; some of which are new and have not been reported in literature previously. In addition, a novel DI SPME method from complex matrices for the analysis of organophosphates related to the CWC was developed. The studies clearly show that DI SPME for complex matrices is superior to HS extraction and can potentially be applied to other related compounds controlled under the CWC. Copyright © 2017. Published by Elsevier B.V.

The ALIVE Project: Astronomy Learning in Immersive Virtual Environments

Science.gov (United States)

Yu, K. C.; Sahami, K.; Denn, G.

2008-06-01

The Astronomy Learning in Immersive Virtual Environments (ALIVE) project seeks to discover learning modes and optimal teaching strategies using immersive virtual environments (VEs). VEs are computer-generated, three-dimensional environments that can be navigated to provide multiple perspectives. Immersive VEs provide the additional benefit of surrounding a viewer with the simulated reality. ALIVE evaluates the incorporation of an interactive, real-time ``virtual universe'' into formal college astronomy education. In the experiment, pre-course, post-course, and curriculum tests will be used to determine the efficacy of immersive visualizations presented in a digital planetarium versus the same visual simulations in the non-immersive setting of a normal classroom, as well as a control case using traditional classroom multimedia. To normalize for inter-instructor variability, each ALIVE instructor will teach at least one of each class in each of the three test groups.

Social Interaction Development through Immersive Virtual Environments

Science.gov (United States)

Beach, Jason; Wendt, Jeremy

2014-01-01

The purpose of this pilot study was to determine if participants could improve their social interaction skills by participating in a virtual immersive environment. The participants used a developing virtual reality head-mounted display to engage themselves in a fully-immersive environment. While in the environment, participants had an opportunity…

Distortion of calculated whole-body hematocrit during lower-body immersion in water.

Science.gov (United States)

Knight, D R; Santoro, T; Bondi, K R

1986-11-01

We found a difference between the venous hematocrits of immersed and nonimmersed arms during immersion of the lower body in cold water but not during a comparable exposure to warm water. Fourteen healthy men were exposed to three different experimental conditions: arm immersion, body immersion, and control. The men always sat upright while both upper extremities hung vertically at their sides. During arm immersion, one forearm was completely immersed for 30 min in either cold water (28 degrees C, n = 7) or warm water (38 degrees C, n = 7). This cold-warm water protocol was repeated on separate days for exposure to the remaining conditions of body immersion (immersion of 1 forearm and all tissues below the xiphoid process) and control (no immersion). Blood samples were simultaneously drawn from cannulated veins in both antecubital fossae. Hematocrit difference (Hct diff) was measured by subtracting the nonimmersed forearm's hematocrit (Hct dry) from the immersed forearm's hematocrit (Hct wet). Hct diff was approximately zero when the men were exposed to the control condition and body immersion in warm water. In the remaining conditions, Hct wet dropped below Hct dry (P less than 0.01, 3-way analysis of variance). The decrements of Hct diff showed there were differences between venous hematocrits in immersed and nonimmersed regions of the body, indicating that changes of the whole-body hematocrit cannot be calculated from a large-vessel hematocrit soon after immersing the lower body in cold water.

Cardiovascular autonomic control during short-term thermoneutral and cool head-out immersion.

Science.gov (United States)

Mourot, Laurent; Bouhaddi, Malika; Gandelin, Emmanuel; Cappelle, Sylvie; Dumoulin, Gilles; Wolf, Jean-Pierre; Rouillon, Jean Denis; Regnard, Jacques

2008-01-01

Moderately cold head-out water immersion stimulates both baro- and cold-receptors, and triggers complex and contradictory effects on the cardiovascular system and its autonomic nervous control. To assess the effects of water immersion and cold on cardiovascular status and related autonomic nervous activity. Hemodynamic variables and indexes of autonomic nervous activity (analysis of heart rate and blood pressure variability) were evaluated in 12 healthy subjects during 3 exposures of 20 min each in the upright position, i.e., in air (AIR, 24-25 degrees C), and during head-out water immersion at 35-36 degrees C (WIn) and 26-27 degrees C (WIc). Plasma noradrenaline, systolic and diastolic blood pressure, and total peripheral resistances were reduced during WIn compared to AIR (263.9 +/- 39.4 vs. 492.5 +/- 35.7 pg x ml(-1), 116.5 +/- 3.7 and 65.4 +/- 1.7 mmHg vs. 140.8 +/- 4.7 and 89.8 +/- 2.8 mmHg, 14.1 +/- 1.0 vs. 16.3 +/- 0.9 mmHg x L(-1) x min, respectively) while they were increased during WIc (530.8 +/- 84.7 pg ml(-1), 148.0 +/- 7.0 mmHg, 80.8 +/- 3.0 mmHg, and 25.8 +/- 1.9 mmHg x L(-1) x min, respectively). The blood pressure variability was reduced to the same extent during WIc and Win compared to AIR. Heart rate decreased during WIn (67.8 +/- 2.7 vs. 81.2 +/- 2.7 bpm during AIR), in parallel with an increased cardiac parasympathetic activity. This pattern was strengthened during WIc (55.3 +/- 2.2 bpm). Thermoneutral WI lowered sympathetic activity and arterial tone, while moderate whole-body skin cooling triggered vascular sympathetic activation. Conversely, both WI and cold triggered cardiac parasympathetic activation, highlighting a complex autonomic control of the cardiovascular system.

Numerical simulation of X-wing type biplane flapping wings in 3D using the immersed boundary method

International Nuclear Information System (INIS)

Tay, W B; Van Oudheusden, B W; Bijl, H

2014-01-01

The numerical simulation of an insect-sized ‘X-wing’ type biplane flapping wing configuration is performed in 3D using an immersed boundary method solver at Reynolds numbers equal to 1000 (1 k) and 5 k, based on the wing's root chord length. This X-wing type flapping configuration draws its inspiration from Delfly, a bio-inspired ornithopter MAV which has two pairs of wings flapping in anti-phase in a biplane configuration. The objective of the present investigation is to assess the aerodynamic performance when the original Delfly flapping wing micro-aerial vehicle (FMAV) is reduced to the size of an insect. Results show that the X-wing configuration gives more than twice the average thrust compared with only flapping the upper pair of wings of the X-wing. However, the X-wing's average thrust is only 40% that of the upper wing flapping at twice the stroke angle. Despite this, the increased stability which results from the smaller lift and moment variation of the X-wing configuration makes it more suited for sharp image capture and recognition. These advantages make the X-wing configuration an attractive alternative design for insect-sized FMAVS compared to the single wing configuration. In the Reynolds number comparison, the vorticity iso-surface plot at a Reynolds number of 5 k revealed smaller, finer vortical structures compared to the simulation at 1 k, due to vortices’ breakup. In comparison, the force output difference is much smaller between Re = 1 k and 5 k. Increasing the body inclination angle generates a uniform leading edge vortex instead of a conical one along the wingspan, giving higher lift. Understanding the force variation as the body inclination angle increases will allow FMAV designers to optimize the thrust and lift ratio for higher efficiency under different operational requirements. Lastly, increasing the spanwise flexibility of the wings increases the thrust slightly but decreases the efficiency. The thrust result is similar

A Study on Immersion and Presence of a Portable Hand Haptic System for Immersive Virtual Reality.

Science.gov (United States)

Kim, Mingyu; Jeon, Changyu; Kim, Jinmo

2017-05-17

This paper proposes a portable hand haptic system using Leap Motion as a haptic interface that can be used in various virtual reality (VR) applications. The proposed hand haptic system was designed as an Arduino-based sensor architecture to enable a variety of tactile senses at low cost, and is also equipped with a portable wristband. As a haptic system designed for tactile feedback, the proposed system first identifies the left and right hands and then sends tactile senses (vibration and heat) to each fingertip (thumb and index finger). It is incorporated into a wearable band-type system, making its use easy and convenient. Next, hand motion is accurately captured using the sensor of the hand tracking system and is used for virtual object control, thus achieving interaction that enhances immersion. A VR application was designed with the purpose of testing the immersion and presence aspects of the proposed system. Lastly, technical and statistical tests were carried out to assess whether the proposed haptic system can provide a new immersive presence to users. According to the results of the presence questionnaire and the simulator sickness questionnaire, we confirmed that the proposed hand haptic system, in comparison to the existing interaction that uses only the hand tracking system, provided greater presence and a more immersive environment in the virtual reality.

A Study on Immersion and Presence of a Portable Hand Haptic System for Immersive Virtual Reality

Science.gov (United States)

Kim, Mingyu; Jeon, Changyu; Kim, Jinmo

2017-01-01

This paper proposes a portable hand haptic system using Leap Motion as a haptic interface that can be used in various virtual reality (VR) applications. The proposed hand haptic system was designed as an Arduino-based sensor architecture to enable a variety of tactile senses at low cost, and is also equipped with a portable wristband. As a haptic system designed for tactile feedback, the proposed system first identifies the left and right hands and then sends tactile senses (vibration and heat) to each fingertip (thumb and index finger). It is incorporated into a wearable band-type system, making its use easy and convenient. Next, hand motion is accurately captured using the sensor of the hand tracking system and is used for virtual object control, thus achieving interaction that enhances immersion. A VR application was designed with the purpose of testing the immersion and presence aspects of the proposed system. Lastly, technical and statistical tests were carried out to assess whether the proposed haptic system can provide a new immersive presence to users. According to the results of the presence questionnaire and the simulator sickness questionnaire, we confirmed that the proposed hand haptic system, in comparison to the existing interaction that uses only the hand tracking system, provided greater presence and a more immersive environment in the virtual reality. PMID:28513545

Boundary as Bridge: An Analysis of the Educational Neuroscience Literature from a Boundary Perspective

Science.gov (United States)

Beauchamp, Catherine; Beauchamp, Miriam H.

2013-01-01

Within the emerging field of educational neuroscience, concerns exist that the impact of neuroscience research on education has been less effective than hoped. In seeking a way forward, it may be useful to consider the problems of integrating two complex fields in the context of disciplinary boundaries. Here, a boundary perspective is used as a…

Immersive Virtual Environments and Multisensory Interfaces

DEFF Research Database (Denmark)

Stenslie, Ståle

2009-01-01

Based on my work with virtual environments dating back to the early 1990s, and with practical and engineering limitations on building tactile bodysuits that enhance the sense of immersion within detailed and dynamic virtual worlds overcome, this paper will take as its subject the example of my...... immersive artwork the Erotogod experiment (2001). A key aspect of interaction and immersion for the participant was the use of tactile bodysuit. I will analyze the multisensory nature of this experience, how tactility was engendered and, in fact, engineered through a mixture of technologies and approaches....... The paper will focus on the multisensory aspect of my interfaces as they have evolved through my projects, discussing how engineering problems were overcome to enhance tactility, the experimentations with tactile technologies in order to engineer the right feeling, and what is involved in the multisensory...

Maintenance system for immersed seals, specifically for nuclear reactors

International Nuclear Information System (INIS)

Poindexter, A.M.; Ricks, H.E.

1977-01-01

The invention concerns the immersed seals of nuclear reactors and specifically a maintenance system for the immersed seals of the revolving closing plugs of liquid metal breeder nuclear reactors. A liquid sodium immersed joint may be located at a given place or be surrounded by heating elements so that the sodium stays liquid whilst the reactor is working. In other cases, the sodium in the immersed seal is allowed to solidify whilst the reactor is working, thereby increasing the efficiency of the seal. At all events, the sodium must be in a liquid state during reloading with fuel to enable the plug to turn. The invention consists in fitting an ultrasonic transducer to the closure head of the reactor vessel so that the vibration emitting surface directs these vibrations towards the immersed seals so as to detach the deposits of impurities on them and ensure the wetting of the metal surfaces of which they are formed. Additionally, an envelope that can be placed around the ultrasonic transducer in conjunction with a suction appliance provides a mechanism through which the impurities can be removed from the area of the immersed seal [fr

Prolonged whole-body cold water immersion: fluid and ion shifts.

Science.gov (United States)

Deuster, P A; Smith, D J; Smoak, B L; Montgomery, L C; Singh, A; Doubt, T J

1989-01-01

To characterize fluid and ion shifts during prolonged whole-body immersion, 16 divers wearing dry suits completed four whole-body immersions in 5 degrees C water during each of two 5-day air saturation dives at 6.1 msw. One immersion was conducted at 1000 (AM) and one at 2200 (PM) so that diurnal variations could be evaluated. Fifty-four hours separated the immersions, which lasted up to 6 h; 9 days separated each air saturation dive. Blood was collected before and after immersion; urine was collected for 12 h before, during, and after immersion for a total of 24 h. Plasma volume decreased significantly and to the same extent (approximately 17%) during both AM and PM immersions. Urine flow increased by 236.1 +/- 38.7 and 296.3 +/- 52.0%, urinary excretion of Na increased by 290.4 +/- 89.0 and 329.5 +/- 77.0%, K by 245.0 +/- 73.4 and 215.5 +/- 44.6%, Ca by 211.0 +/- 31.4 and 241.1 +/- 50.4%, Mg by 201.4 +/- 45.9 and 165.3 +/- 287%, and Zn by 427.8 +/- 93.7 and 301.9 +/- 75.4% during AM and PM immersions, respectively, compared with preimmersion. Urine flow and K excretion were significantly higher during the AM than PM. In summary, when subjects are immersed in cold water for prolonged periods, combined with a slow rate of body cooling afforded by thermal protection and enforced intermittent exercise, there is diuresis, decreased plasma volume, and increased excretions of Na, K, Ca, Mg, and Zn.

Communication: X-ray coherent diffractive imaging by immersion in nanodroplets

Directory of Open Access Journals (Sweden)

Rico Mayro P. Tanyag

2015-09-01

Full Text Available Lensless x-ray microscopy requires the recovery of the phase of the radiation scattered from a specimen. Here, we demonstrate a de novo phase retrieval technique by encapsulating an object in a superfluid helium nanodroplet, which provides both a physical support and an approximate scattering phase for the iterative image reconstruction. The technique is robust, fast-converging, and yields the complex density of the immersed object. Images of xenon clusters embedded in superfluid helium droplets reveal transient configurations of quantum vortices in this fragile system.

Immersive 3D Geovisualization in Higher Education

Science.gov (United States)

Philips, Andrea; Walz, Ariane; Bergner, Andreas; Graeff, Thomas; Heistermann, Maik; Kienzler, Sarah; Korup, Oliver; Lipp, Torsten; Schwanghart, Wolfgang; Zeilinger, Gerold

2015-01-01

In this study, we investigate how immersive 3D geovisualization can be used in higher education. Based on MacEachren and Kraak's geovisualization cube, we examine the usage of immersive 3D geovisualization and its usefulness in a research-based learning module on flood risk, called GEOSimulator. Results of a survey among participating students…

Immersion technique in soft tissue radiography of the hands

International Nuclear Information System (INIS)

Maekelae, P.; Haaslahti, J.O.

1978-01-01

Soft tissue radiography of hands using the technique of mammary radiography and immersion in a 2.5 cm layer of 1 : 1 water-ethanol solution is evaluated. Using immersion the average background density decreases with a factor of about 2.5 : 1, with little deterioration in resolution (MTF). The immersion procedure makes the demonstration and evaluation of soft tisse swelling and periarticular oedema easier. (Auth.)

Is Immersion of Any Value? Whether, and to What Extent, Game Immersion Experience during Serious Gaming Affects Science Learning

Science.gov (United States)

Cheng, Meng-Tzu; Lin, Yu-Wen; She, Hsiao-Ching; Kuo, Po-Chih

2017-01-01

Many studies have shown the positive impact of serious gaming on learning outcomes, but few have explored the relationships between game immersion and science learning. Accordingly, this study was conducted to investigate the effectiveness of learning by playing, as well as the dynamic process of game immersion experiences, and to further identify…

Surface modification of coronary artery stent by Ti-O/Ti-N complex film coating prepared with plasma immersion ion implantation and deposition

International Nuclear Information System (INIS)

Huang, N.; Leng, Y.X.; Yang, P.

2006-01-01

This paper reported the work of surface coating of Ti-O/Ti-N complex films on coronary stents by means of the plasma immersion ion implantation/deposition process. The deformation behavior of the Ti-O/Ti-N coated stainless steel stents was investigated. In vivo investigation of the anticoagulation behavior of Ti-O coated coronary stents was also performed. The results of mechanical characterization of the Ti-O/Ti-N coated stents show that the film has strong binding strength, and to some extent the ability to withstand plastic deformation. The biological response behavior of the coated stent surface was significantly different from the uncoated. The results of implantation of stents into rabbit ventral aorta show no thrombus formation on the surfaces of the Ti-O coated stents, although serious coagulation had occurred on the surfaces of unmodified stents over a period of 4 weeks under conditions with no anticoagulant

Interactions of impurities with a moving grain boundary

Energy Technology Data Exchange (ETDEWEB)

Bauer, C L [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

1975-01-01

Most theories developed to explain interaction of impurities with a moving grain boundary involve a uniform excess impurity concentration distributed along a planar grain boundary. As boundary velocity increases, the excess impurities exert a net drag force on the boundary until a level is reached whereat the drag force no longer can balance the driving force and breakaway of the boundary from these impurities occurs. In this investigation, assumptions of a uniform lateral impurity profile and a planar grain boundary shape are relaxed by allowing both forward and lateral diffusion of impurities in the vicinity of a grain boundary. It is found that the two usual regions (drag of impurities by, and breakaway of a planar grain boundary) are separated by an extensive region wherein a uniform lateral impurity profile and a planar grain boundary shape are unstable. It is suspected that, in this unstable region, grain boundaries assume a spectrum of more complex morphologies and that elucidation of these morphologies can provide the first definitive description of the breakaway process and insight to more complex phenomena such as solid-solution strengthening, grain growth and secondary recrystallization.

Changes in landing mechanics after cold-water immersion.

Science.gov (United States)

Wang, He; Toner, Michael M; Lemonda, Thomas J; Zohar, Mor

2010-06-01

The purpose of this study was to investigate the influence of cold-water immersion on kinematics and kinetics during a drop-landing task. On four separate occasions, 9 men performed drop-landings from a 0.6-m platform to a force platform following 30-min immersion to the hip-joint in thermoneutral water (control; 34 degrees C) and in cold water (20 degrees C) to the ankle (low level), knee (medium level), and hip (high level) joints. Sagittal plane kinematics and kinetics were determined. One-way repeated measures multivariate analysis of variance was used for statistical analysis. Compared to the control, the low-level condition had similar joint mechanics, the medium level showed 26% less ankle mechanical work (p = .003), and the high level showed 9% less vertical ground reaction force (p = .025) and 23% less ankle mechanical work (p = .023) with 18% greater trunk flexion (p = .024). In summary, the low-level cold-water immersion had no effect on landing mechanics. The medium- and high-level cold-water immersion resulted in a reduction in impact absorption at the ankle joint during landing. The increased trunk flexion after high-level immersion helped dissipate landing impact.

The emotional and cognitive effect of immersion in film viewing

NARCIS (Netherlands)

Visch, V.T.; Tan, E.S.; Molenaar, D.

2010-01-01

This brief report presents an experiment testing the effect of immersion on emotional responses and cognitive genre categorisation of film viewers. Immersion of a film presentation was varied by presenting an animated movie either in a 3D-viewing condition (low immersive condition) or in a CAVE

Altered Perspectives: Immersive Environments

Science.gov (United States)

Shipman, J. S.; Webley, P. W.

2016-12-01

Immersive environments provide an exciting experiential technology to visualize the natural world. Given the increasing accessibility of 360o cameras and virtual reality headsets we are now able to visualize artistic principles and scientific concepts in a fully immersive environment. The technology has become popular for photographers as well as designers, industry, educational groups, and museums. Here we show a sci-art perspective on the use of optics and light in the capture and manipulation of 360o images and video of geologic phenomena and cultural heritage sites in Alaska, England, and France. Additionally, we will generate intentionally altered perspectives to lend a surrealistic quality to the landscapes. Locations include the Catacombs of Paris, the Palace of Versailles, and the Northern Lights over Fairbanks, Alaska. Some 360o view cameras now use small portable dual lens technology extending beyond the 180o fish eye lens previously used, providing better coverage and image quality. Virtual reality headsets range in level of sophistication and cost, with the most affordable versions using smart phones and Google Cardboard viewers. The equipment used in this presentation includes a Ricoh Theta S spherical imaging camera. Here we will demonstrate the use of 360o imaging with attendees being able to be part of the immersive environment and experience our locations as if they were visiting themselves.

Immersion Gratings for Infrared High-resolution Spectroscopy

Science.gov (United States)

Sarugaku, Yuki; Ikeda, Yuji; Kobayashi, Naoto; Kaji, Sayumi; Sukegawa, Takashi; Sugiyama, Shigeru; Nakagawa, Takao; Arasaki, Takayuki; Kondo, Sohei; Nakanishi, Kenshi; Yasui, Chikako; Kawakita, Hideyo

2016-10-01

High-resolution spectroscopy in the infrared wavelength range is essential for observations of minor isotopologues, such as HDO for water, and prebiotic organic molecules like hydrocarbons/P-bearing molecules because numerous vibrational molecular bands (including non-polar molecules) are located in this wavelength range. High spectral resolution enables us to detect weak lines without spectral line confusion. This technique has been widely used in planetary sciences, e.g., cometary coma (H2O, CO, and organic molecules), the martian atmosphere (CH4, CO2, H2O and HDO), and the upper atmosphere of gas giants (H3+ and organic molecules such as C2H6). Spectrographs with higher resolution (and higher sensitivity) still have a potential to provide a plenty of findings. However, because the size of spectrographs scales with the spectral resolution, it is difficult to realize it.Immersion grating (IG), which is a diffraction grating wherein the diffraction surface is immersed in a material with a high refractive index (n > 2), provides n times higher spectral resolution compared to a reflective grating of the same size. Because IG reduces the size of spectrograph to 1/n compared to the spectrograph with the same spectral resolution using a conventional reflective grating, it is widely acknowledged as a key optical device to realize compact spectrographs with high spectral resolution.Recently, we succeeded in fabricating a CdZnTe immersion grating with the theoretically predicted diffraction efficiency by machining process using an ultrahigh-precision five-axis processing machine developed by Canon Inc. Using the same technique, we completed a practical germanium (Ge) immersion grating with both a reflection coating on the grating surface and the an AR coating on the entrance surface. It is noteworthy that the wide wavelength range from 2 to 20 um can be covered by the two immersion gratings.In this paper, we present the performances and the applications of the immersion

Managing SMEs’ Collaboration Across Organizational Boundaries Within a Regional Business Ecosystem

DEFF Research Database (Denmark)

Radziwon, Agnieszka; Bogers, Marcel

2017-01-01

’ perspective on managing and organizing inter-company collaboration within a regional business ecosystem. We explore how purposefully managed mutual knowledge flows across organizational boundaries applied by SMEs contribute to the development of the ecosystem they are immersed in. Our key findings include...... challenges, such as low autonomy and control over the partners and indicate shared issues and responsibilities crucial for further ecosystem development. As a conclusion, we offer a set of recommendations both for managers and policymakers concerning general organizational requirements and governing...... structures....

Photogrammetric Applications of Immersive Video Cameras

OpenAIRE

Kwiatek, K.; Tokarczyk, R.

2014-01-01

The paper investigates immersive videography and its application in close-range photogrammetry. Immersive video involves the capture of a live-action scene that presents a 360° field of view. It is recorded simultaneously by multiple cameras or microlenses, where the principal point of each camera is offset from the rotating axis of the device. This issue causes problems when stitching together individual frames of video separated from particular cameras, however there are ways to ov...

Water immersion and changes in the foetoplacental and uteroplacental circulation

DEFF Research Database (Denmark)

Thisted, Dorthe Louise Ahrenkiel; Nørgaard, Lone Nikoline; Meyer, Helle Mølgaard

2015-01-01

Abstract Objective: To evaluate the effect of immersion into water on maternal blood pressure, amount of amniotic fluid and on the foetoplacental- and uteroplacental circulation in healthy women with an uncomplicated singleton pregnancy. Methods: Twenty-five healthy women were included. Recordings...... of blood pressure, deepest vertical pocket of amniotic fluid and pulsatility index (PI) measured by Doppler in the umbilical and uterine arteries were obtained. The participants were immersed into water and the measurements were repeated after 5 and 25 min in water and again 15 and 30 min post immersion....... Results: The amount of amniotic fluid increased significantly (p immersion (p immersion on either umbilical- or uterine artery PI. All changes returned toward baseline-level within 30 min...

Progress in video immersion using Panospheric imaging

Science.gov (United States)

Bogner, Stephen L.; Southwell, David T.; Penzes, Steven G.; Brosinsky, Chris A.; Anderson, Ron; Hanna, Doug M.

1998-09-01

Having demonstrated significant technical and marketplace advantages over other modalities for video immersion, PanosphericTM Imaging (PI) continues to evolve rapidly. This paper reports on progress achieved since AeroSense 97. The first practical field deployment of the technology occurred in June-August 1997 during the NASA-CMU 'Atacama Desert Trek' activity, where the Nomad mobile robot was teleoperated via immersive PanosphericTM imagery from a distance of several thousand kilometers. Research using teleoperated vehicles at DRES has also verified the exceptional utility of the PI technology for achieving high levels of situational awareness, operator confidence, and mission effectiveness. Important performance enhancements have been achieved with the completion of the 4th Generation PI DSP-based array processor system. The system is now able to provide dynamic full video-rate generation of spatial and computational transformations, resulting in a programmable and fully interactive immersive video telepresence. A new multi- CCD camera architecture has been created to exploit the bandwidth of this processor, yielding a well-matched PI system with greatly improved resolution. While the initial commercial application for this technology is expected to be video tele- conferencing, it also appears to have excellent potential for application in the 'Immersive Cockpit' concept. Additional progress is reported in the areas of Long Wave Infrared PI Imaging, Stereo PI concepts, PI based Video-Servoing concepts, PI based Video Navigation concepts, and Foveation concepts (to merge localized high-resolution views with immersive views).

Whole body immersion and hydromineral homeostasis: effect of water temperature.

Science.gov (United States)

Jimenez, Chantal; Regnard, Jacques; Robinet, Claude; Mourot, Laurent; Gomez-Merino, Danielle; Chennaoui, Mounir; Jammes, Yves; Dumoulin, Gilles; Desruelle, Anne-Virginie; Melin, Bruno

2010-01-01

This experiment was designed to assess the effects of prolonged whole body immersion (WBI) in thermoneutral and cold conditions on plasma volume and hydromineral homeostasis.10 navy "combat swimmers" performed three static 6-h immersions at 34 degrees C (T34), 18 degrees C (T18) and 10 degrees C (T10). Rectal temperature, plasma volume (PV) changes, plasma proteins, plasma and urine ions, plasma osmolality, renin, aldosterone and antidiuretic hormone (ADH) were measured. Results show that compared to pre-immersion levels, PV decreased throughout WBI sessions, the changes being markedly accentuated in cold conditions. At the end of WBI, maximal PV variations were -6.9% at T34, -14.3% at T18, and -16.3% at T10. Plasma osmolality did not change during and after T34 immersion, while hyperosmolality was present at the end of T18 immersion and began after only 1 h of T10 immersion. In the three temperature conditions, significant losses of water (1.6-1.7 l) and salt (6-8 g) occurred and were associated with similar increases in osmolar and free water clearances. Furthermore, T18 and T10 immersions increased the glomerular filtration rate. There was little or no change in plasma renin and ADH, while the plasma level of aldosterone decreased equally in the three temperature conditions. In conclusion, our data indicate that cold water hastened PV changes induced by immersion, and increased the glomerular filtration rate, causing larger accumulated water losses. The iso-osmotic hypovolemia may impede the resumption of baseline fluid balance. Results are very similar to those repeatedly described by various authors during head-out water immersion.

Near-wake flow structure downwind of a wind turbine in a turbulent boundary layer

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei; Markfort, Corey D. [University of Minnesota, Saint Anthony Falls Laboratory, Department of Civil Engineering, Minneapolis, MN (United States); Porte-Agel, Fernando [Ecole Polytechnique Federale de Lausanne (EPFL), ENAC-IIE-WIRE, Wind Engineering and Renewable Energy Laboratory (WIRE), Lausanne (Switzerland)

2012-05-15

Wind turbines operate in the surface layer of the atmospheric boundary layer, where they are subjected to strong wind shear and relatively high turbulence levels. These incoming boundary layer flow characteristics are expected to affect the structure of wind turbine wakes. The near-wake region is characterized by a complex coupled vortex system (including helicoidal tip vortices), unsteadiness and strong turbulence heterogeneity. Limited information about the spatial distribution of turbulence in the near wake, the vortex behavior and their influence on the downwind development of the far wake hinders our capability to predict wind turbine power production and fatigue loads in wind farms. This calls for a better understanding of the spatial distribution of the 3D flow and coherent turbulence structures in the near wake. Systematic wind-tunnel experiments were designed and carried out to characterize the structure of the near-wake flow downwind of a model wind turbine placed in a neutral boundary layer flow. A horizontal-axis, three-blade wind turbine model, with a rotor diameter of 13 cm and the hub height at 10.5 cm, occupied the lowest one-third of the boundary layer. High-resolution particle image velocimetry (PIV) was used to measure velocities in multiple vertical stream-wise planes (x-z) and vertical span-wise planes (y-z). In particular, we identified localized regions of strong vorticity and swirling strength, which are the signature of helicoidal tip vortices. These vortices are most pronounced at the top-tip level and persist up to a distance of two to three rotor diameters downwind. The measurements also reveal strong flow rotation and a highly non-axisymmetric distribution of the mean flow and turbulence structure in the near wake. The results provide new insight into the physical mechanisms that govern the development of the near wake of a wind turbine immersed in a neutral boundary layer. They also serve as important data for the development and

A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

Science.gov (United States)

Spandan, Vamsi; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

2017-11-01

In this paper we show and discuss how the deformation dynamics of closed liquid-liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid-liquid interfaces is based on the fundamental principle of minimum potential energy where the total potential energy depends on the extent of deformation of a spring network distributed on the surface of the immersed drop or bubble. Simulating liquid-liquid interfaces using this model require computing ad-hoc elastic constants which is done through a reverse-engineered approach. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as a deforming drop in a shear flow or cross flow. The interaction potential model is highly versatile, computationally efficient and can be easily incorporated into generic single phase fluid solvers to also simulate complex fluid-structure interaction problems. This is shown by simulating flow in the left ventricle of the heart with mechanical and natural mitral valves where the imposed flow, motion of ventricle and valves dynamically govern the behaviour of each other. Results from these simulations are compared with ad-hoc in-house experimental measurements. Finally, we present a simple and easy to implement parallelisation scheme, as high performance computing is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies in highly turbulent flows.

Kenaf Fibre Reinforced Polypropylene Composites: Effect of Cyclic Immersion on Tensile Properties

Directory of Open Access Journals (Sweden)

W. H. Haniffah

2015-01-01

Full Text Available This research studied the degradation of tensile properties of kenaf fibre reinforced polypropylene composites due to cyclic immersion into two different solutions, as well as comparison of the developed composites’ tensile properties under continuous and cyclic immersion. Composites with 40% and 60% fibre loadings were immersed in tap water and bleach for 4 cycles. Each cycle consisted of 3 days of immersion and 4 days of conditioning in room temperature (28°C and 55% humidity. The tensile strength and modulus of composites were affected by fibre composition, type of liquid of immersion, and number of cycles. The number of immersion cycles and conditioning caused degradation to tensile strength and modulus of kenaf fibre reinforced polypropylene composites. Continuous and cyclic immersion in bleach caused tensile strength of the composites to differ significantly whereas, for tensile modulus, the difference was insignificant in any immersion and fibre loadings. However, continuous immersion in the bleach reduced the tensile strength of composites more compared to cyclic immersion. These preliminary results suggest further evaluation of the suitability of kenaf fibre reinforced polypropylene composites for potential bathroom application where the composites will be exposed to water/liquid in cyclic manner due to discontinuous usage of bathroom.

Immersive virtual reality simulations in nursing education.

Science.gov (United States)

Kilmon, Carol A; Brown, Leonard; Ghosh, Sumit; Mikitiuk, Artur

2010-01-01

This article explores immersive virtual reality as a potential educational strategy for nursing education and describes an immersive learning experience now being developed for nurses. This pioneering project is a virtual reality application targeting speed and accuracy of nurse response in emergency situations requiring cardiopulmonary resuscitation. Other potential uses and implications for the development of virtual reality learning programs are discussed.

Aberration characteristics of immersion lenses for LVSEM

International Nuclear Information System (INIS)

Khursheed, Anjam

2002-01-01

This paper investigates the on-axis aberration characteristics of various immersion objective lenses for low voltage scanning electron microscopy (LVSEM). A simple aperture lens model is used to generate smooth axial field distributions. The simulation results show that mixed field electric-magnetic immersion lenses are predicted to have between 1.5 and 2 times smaller aberration limited probe diameters than their pure-field counterparts. At a landing energy of 1 keV, mixed field immersion lenses operating at the vacuum electrical field breakdown limit are predicted to have on-axis aberration coefficients between 50 and 60 μm, yielding an ultimate image resolution of below 1 nm. These aberrations lie in the same range as those for LVSEM systems that employ aberration correctors

$f$-Biminimal immersions

OpenAIRE

GÜRLER, FATMA; ÖZGÜR, CİHAN

2017-01-01

In the present paper, we define $f$-biminimal immersions. We consider $f$-biminimal curves in a Riemannian manifold and $f$-biminimal submanifolds of codimension $1$ in a Riemannian manifold, and we give examples of $f$-biminimal surfaces. Finally, we consider $f$-biminimal Legendre curves in Sasakian space forms and give an example.

Interorganizational Boundary Spanning in Global Software Development

DEFF Research Database (Denmark)

Søderberg, Anne-Marie; Romani, Laurence

, and which skills and competencies they draw on in their efforts to deal with emerging cross-cultural issues in a way that paves ground for developing a shared understanding and common platform for the client and vendor representatives. A framework of boundary spanning leadership practices is adapted...... to virtuality and cultural diversity. This paper, which draws on a case study of collaborative work in a global software development project, focuses on key boundary spanners in an Indian vendor company, who are responsible for developing trustful and sustainable client relations and coordinating complex...... projects across multiple cultures, languages, organisational boundaries, time zones and geographical distances. It looks into how these vendor managers get prepared for their complex boundary spanning work, which cross-cultural challenges they experience in their collaboration with Western clients...

Immersible solar heater for fluids

Science.gov (United States)

Kronberg, James W.

1995-01-01

An immersible solar heater comprising a light-absorbing panel attached to a frame for absorbing heat energy from the light and transferring the absorbed heat energy directly to the fluid in which the heater is immersed. The heater can be used to heat a swimming pool, for example, and is held in position and at a preselected angle by a system of floats, weights and tethers so that the panel can operate efficiently. A skid can be used in one embodiment to prevent lateral movement of the heater along the bottom of the pool. Alternative embodiments include different arrangements of the weights, floats and tethers and methods for making the heater.

A common path forward for the immersive visualization community

Energy Technology Data Exchange (ETDEWEB)

Eric A. Wernert; William R. Sherman; Patrick O' Leary; Eric Whiting

2012-03-01

Immersive visualization makes use of the medium of virtual reality (VR) - it is a subset of virtual reality focused on the application of VR technologies to scientific and information visualization. As the name implies, there is a particular focus on the physically immersive aspect of VR that more fully engages the perceptual and kinesthetic capabilities of the scientist with the goal of producing greater insight. The immersive visualization community is uniquely positioned to address the analysis needs of the wide spectrum of domain scientists who are becoming increasingly overwhelmed by data. The outputs of computational science simulations and high-resolution sensors are creating a data deluge. Data is coming in faster than it can be analyzed, and there are countless opportunities for discovery that are missed as the data speeds by. By more fully utilizing the scientists visual and other sensory systems, and by offering a more natural user interface with which to interact with computer-generated representations, immersive visualization offers great promise in taming this data torrent. However, increasing the adoption of immersive visualization in scientific research communities can only happen by simultaneously lowering the engagement threshold while raising the measurable benefits of adoption. Scientists time spent immersed with their data will thus be rewarded with higher productivity, deeper insight, and improved creativity. Immersive visualization ties together technologies and methodologies from a variety of related but frequently disjoint areas, including hardware, software and human-computer interaction (HCI) disciplines. In many ways, hardware is a solved problem. There are well established technologies including large walk-in systems such as the CAVE{trademark} and head-based systems such as the Wide-5{trademark}. The advent of new consumer-level technologies now enable an entirely new generation of immersive displays, with smaller footprints and costs

Cardiovascular responses to apneic facial immersion during altered cardiac filling.

Science.gov (United States)

Journeay, W Shane; Reardon, Francis D; Kenny, Glen P

2003-06-01

The hypothesis that reduced cardiac filling, as a result of lower body negative pressure (LBNP) and postexercise hypotension (PEH), would attenuate the reflex changes to heart rate (HR), skin blood flow (SkBF), and mean arterial pressure (MAP) normally induced by facial immersion was tested. The purpose of this study was to investigate the cardiovascular control mechanisms associated with apneic facial immersion during different cardiovascular challenges. Six subjects randomly performed 30-s apneic facial immersions in 6.0 +/- 1.2 degrees C water under the following conditions: 1) -20 mmHg LBNP, 2) +40 mmHg lower body positive pressure (LBPP), 3) during a period of PEH, and 4) normal resting (control). Measurements included SkBF at one acral (distal phalanx of the thumb) and one nonacral region of skin (ventral forearm), HR, and MAP. Facial immersion reduced HR and SkBF at both sites and increased MAP under all conditions (P filling during LBNP and PEH significantly attenuated the absolute HR nadir observed during the control immersion (P facial immersion can be attenuated when cardiac filling is compromised.

Simulation of biological flow and transport in complex geometries using embedded boundary/volume-of-fluid methods

International Nuclear Information System (INIS)

Trebotich, David

2007-01-01

We have developed a simulation capability to model multiscale flow and transport in complex biological systems based on algorithms and software infrastructure developed under the SciDAC APDEC CET. The foundation of this work is a new hybrid fluid-particle method for modeling polymer fluids in irregular microscale geometries that enables long-time simulation of validation experiments. Both continuum viscoelastic and discrete particle representations have been used to model the constitutive behavior of polymer fluids. Complex flow environment geometries are represented on Cartesian grids using an implicit function. Direct simulation of flow in the irregular geometry is then possible using embedded boundary/volume-of-fluid methods without loss of geometric detail. This capability has been used to simulate biological flows in a variety of application geometries including biomedical microdevices, anatomical structures and porous media

Experience dans une classe d'immersion francaise aux Milles-Iles (An Experience in a French Immersion Class in Mille-Iles)

Science.gov (United States)

Pariseau, Cecile

1978-01-01

A description of an immersion program for 6-year-old anglophone children modeled on "les classes d'accueil" for immigrant children. The program of intensive instruction in oral and written French is outlined. This school district has found this type of immersion superior to the usual kind. (The text is in French.) (AMH)

Immersed acoustical transducers and their potential uses in LMFBR

International Nuclear Information System (INIS)

Argous, J.P.; Brunet, M.; Baron, J.; Lhuillier, C.; Segui, J.L.

1980-04-01

Six years satisfactory operation in PHENIX has proved the reliability and effectivness of under-sodium viewing (VISUS) and Acoustic Detection. This fact has been strong incentive to maintain, on the future LMFBR the visus as well as the Acoustic Detection functions. These two functions are performed on SUPER PHENIX, by two sets of distinct systems using the well-known solution. Taking into account of recent improvements in sodium immersible acoustic transducers technology, CEA decided to undertake the development of a multi-functions instrument. This paper gives an outline of this new concept, which should be able to reduce the cost and the complexity of core instrumentation

Immersion Suit Usage Within the RAAF

Science.gov (United States)

1992-01-01

IMMERSION SUIT USED UVIC QDIS HOLDINGS 202. in 12 Sizes, held by ALSS 492SQN REQUIREMENTS No comment USAGE POLICY REFERENCE DIRAF) AAP 7215.004-1 (P3C...held by ALSS 492SQN. REQUIREMENTS No comment ISACE POLICY REFERENCE DIIAF) AAP 7215.004-1 (P3C Flight Manual) RAAF Supplement No 92 USAGE POUICY UVIC...TYPE P3C REFERENCE Telecon FLTLT Toft I I SQNfRESO AVMED Dated 22 Mar 91 IMMERSION SUIT USED UVIC QDIS HOLDINGS No comment REQUIREMENTS No comment USAGE

Human fear conditioning conducted in full immersion 3-dimensional virtual reality.

Science.gov (United States)

Huff, Nicole C; Zeilinski, David J; Fecteau, Matthew E; Brady, Rachael; LaBar, Kevin S

2010-08-09

Fear conditioning is a widely used paradigm in non-human animal research to investigate the neural mechanisms underlying fear and anxiety. A major challenge in conducting conditioning studies in humans is the ability to strongly manipulate or simulate the environmental contexts that are associated with conditioned emotional behaviors. In this regard, virtual reality (VR) technology is a promising tool. Yet, adapting this technology to meet experimental constraints requires special accommodations. Here we address the methodological issues involved when conducting fear conditioning in a fully immersive 6-sided VR environment and present fear conditioning data. In the real world, traumatic events occur in complex environments that are made up of many cues, engaging all of our sensory modalities. For example, cues that form the environmental configuration include not only visual elements, but aural, olfactory, and even tactile. In rodent studies of fear conditioning animals are fully immersed in a context that is rich with novel visual, tactile and olfactory cues. However, standard laboratory tests of fear conditioning in humans are typically conducted in a nondescript room in front of a flat or 2D computer screen and do not replicate the complexity of real world experiences. On the other hand, a major limitation of clinical studies aimed at reducing (extinguishing) fear and preventing relapse in anxiety disorders is that treatment occurs after participants have acquired a fear in an uncontrolled and largely unknown context. Thus the experimenters are left without information about the duration of exposure, the true nature of the stimulus, and associated background cues in the environment. In the absence of this information it can be difficult to truly extinguish a fear that is both cue and context-dependent. Virtual reality environments address these issues by providing the complexity of the real world, and at the same time allowing experimenters to constrain fear

Construction of codimension 1 immersions of spacetime: the exceptional case

International Nuclear Information System (INIS)

Edelen, Dominic G B

2005-01-01

The Frobenius theorem was used in Edelen (2003 Class. Quantum Grav. 20 3661) to obtain a general body of results for the immersion of spacetime in flat spaces of higher dimension. This addendum completes those results for the exceptional case of immersions of codimension 1 where the Frobenius theorem need not be applied. Local actions of the Poincare groups SO(2, 3)--T(5) or SO(1, 4) -- T(5) are used to obtain immersions of spacetime of codimension 1 that involve six arbitrary functions of the four immersion parameters and an arbitrary constant. Explicit calculations are given for several cases. (addendum)

Color stability of ceramic brackets immersed in potentially staining solutions.

Science.gov (United States)

Guignone, Bruna Coser; Silva, Ludimila Karsbergen; Soares, Rodrigo Villamarim; Akaki, Emilio; Goiato, Marcelo Coelho; Pithon, Matheus Melo; Oliveira, Dauro Douglas

2015-01-01

To assess the color stability of five types of ceramic brackets after immersion in potentially staining solutions. Ninety brackets were divided into 5 groups (n = 18) according to brackets commercial brands and the solutions in which they were immersed (coffee, red wine, coke and artificial saliva). The brackets assessed were Transcend (3M/Unitek, Monrovia, CA, USA), Radiance (American Orthodontics, Sheboygan, WI, USA), Mystique (GAC International Inc., Bohemia, NY, USA) and Luxi II (Rocky Mountain Orthodontics, Denver, CO, USA). Chromatic changes were analyzed with the aid of a reflectance spectrophotometer and by visual inspection at five specific time intervals. Assessment periods were as received from the manufacturer (T0), 24 hours (T1), 72 hours (T2), as well as 7 days (T3) and 14 days (T4) of immersion in the aforementioned solutions. Results were submitted to statistical analysis with ANOVA and Bonferroni correction, as well as to a multivariate profile analysis for independent and paired samples with significance level set at 5%. The duration of the immersion period influenced color alteration of all tested brackets, even though these changes could not always be visually observed. Different behaviors were observed for each immersion solution; however, brackets immersed in one solution progressed similarly despite minor variations. Staining became more intense over time and all brackets underwent color alterations when immersed in the aforementioned solutions.

Bayesian Statistics and Uncertainty Quantification for Safety Boundary Analysis in Complex Systems

Science.gov (United States)

He, Yuning; Davies, Misty Dawn

2014-01-01

The analysis of a safety-critical system often requires detailed knowledge of safe regions and their highdimensional non-linear boundaries. We present a statistical approach to iteratively detect and characterize the boundaries, which are provided as parameterized shape candidates. Using methods from uncertainty quantification and active learning, we incrementally construct a statistical model from only few simulation runs and obtain statistically sound estimates of the shape parameters for safety boundaries.

Immersive Virtual Reality with Applications to Tele-Operation and Training

Science.gov (United States)

2016-03-07

reviewed journals : Number of Papers published in non peer-reviewed journals : Final Report: Immersive Virtual Reality with Applications to Tele-Operation... Immersive Virtual Reality with Applications to Tele-Operation and Training The proposed project aims to develop a fundamental framework for...establishing an immersive virtual reality environment for robust and scalable human robotics interaction in a cooperative intelligent architecture at the

Sprint cycling performance is maintained with short-term contrast water immersion.

Science.gov (United States)

Crampton, David; Donne, Bernard; Egaña, Mikel; Egana, Mikel; Warmington, Stuart A

2011-11-01

Given the widespread use of water immersion during recovery from exercise, we aimed to investigate the effect of contrast water immersion on recovery of sprint cycling performance, HR and, blood lactate. Two groups completed high-intensity sprint exercise before and after a 30-min randomized recovery. The Wingate group (n = 8) performed 3 × 30-s Wingate tests (4-min rest periods). The repeated intermittent sprint group (n = 8) cycled for alternating 30-s periods at 40% of predetermined maximum power and 120% maximum power, until exhaustion. Both groups completed three trials using a different recovery treatment for each trial (balanced randomized application). Recovery treatments were passive rest, 1:1 contrast water immersion (2.5 min of cold (8°C) to 2.5 min of hot (40°C)), and 1:4 contrast water immersion (1 min of cold to 4 min of hot). Blood lactate and HR were recorded throughout, and peak power and total work for pre- and postrecovery Wingate performance and exercise time and total work for repeated sprinting were recorded. Recovery of Wingate peak power was 8% greater after 1:4 contrast water immersion than after passive rest, whereas both contrast water immersion ratios provided a greater recovery of exercise time (∼ 10%) and total work (∼ 14%) for repeated sprinting than for passive rest. Blood lactate was similar between trials. Compared with passive rest, HR initially declined more slowly during contrast water immersion but increased with each transition to a cold immersion phase. These data support contrast water immersion being effective in maintaining performance during a short-term recovery from sprint exercise. This effect needs further investigation but is likely explained by cardiovascular mechanisms, shown here by an elevation in HR upon each cold immersion.

Comparative study on collaborative interaction in non-immersive and immersive systems

Science.gov (United States)

Shahab, Qonita M.; Kwon, Yong-Moo; Ko, Heedong; Mayangsari, Maria N.; Yamasaki, Shoko; Nishino, Hiroaki

2007-09-01

This research studies the Virtual Reality simulation for collaborative interaction so that different people from different places can interact with one object concurrently. Our focus is the real-time handling of inputs from multiple users, where object's behavior is determined by the combination of the multiple inputs. Issues addressed in this research are: 1) The effects of using haptics on a collaborative interaction, 2) The possibilities of collaboration between users from different environments. We conducted user tests on our system in several cases: 1) Comparison between non-haptics and haptics collaborative interaction over LAN, 2) Comparison between non-haptics and haptics collaborative interaction over Internet, and 3) Analysis of collaborative interaction between non-immersive and immersive display environments. The case studies are the interaction of users in two cases: collaborative authoring of a 3D model by two users, and collaborative haptic interaction by multiple users. In Virtual Dollhouse, users can observe physics law while constructing a dollhouse using existing building blocks, under gravity effects. In Virtual Stretcher, multiple users can collaborate on moving a stretcher together while feeling each other's haptic motions.

Immersive Virtual Reality in a University Setting: Creating an Authentic Learning Environment Through the Virtual Golden Foods Corporation

Directory of Open Access Journals (Sweden)

Ros A. Yahaya

2009-12-01

Full Text Available An authentic learning environment is learning that involves real world problems that are relevant to the learners and relate to their real life experience. Research indicates that Information and Communication Technology (ICT tools can facilitate in creating authentic learning environment, thus improving student learning, interaction and satisfaction. Previous research has focused on using various forms of ICT such as online learning and web-based learning into the classroom. However, little attempt has been made to investigate the effectiveness of incorporating immersive Virtual Reality (VR technology into the university classroom. Virtual Golden Foods Corporation (VGFC is a simulated Virtual Reality (VR organization being developed for use in teaching and learning at a large technology based university in Australia. This study focuses on authentic learning environment where students learn about decision making in complex business contexts throughout the semester which culminates in immersive VR exposure. The findings report that immersive VR environment helps to increase students’ understanding of decision making concepts.

Boundary Drawing in Clinical Work

DEFF Research Database (Denmark)

Meier, Ninna

The aim of this paper is to show how health care professionals temporarily dissolve and redraw boundaries in their everyday work, in order to coordinate clinical work and facilitate collaboration in patient pathways. Boundaries are social constructions that help us make sense of our complex, social...... world. In health care, formal boundaries are important distinctions that separate health care practitioners into medical specialties, professions and organizational departments. But clinical work also relies on the ability of health care practitioners to collaborate around patients in formal...... arrangements or emergent, temporary teams. Focusing on the cognitive and social boundaries we draw to establish identity and connection (to a profession, team or person) the paper shows how health care professionals can use inter-personal relationships to temporarily dismiss formal boundaries. By redrawing...

Through-flow cell of immersion sensor

International Nuclear Information System (INIS)

Svandelik, J.

1986-01-01

The cell consists of a jacket in shape of a triangular pyramid whose two opposite and skew edges are truncated. It is provided with inlet and outlet openings. The measuring immersion sensor is inserted through the outlet opening or through an opening provided in one of the jacket side walls. The immersion sensor cell is mainly used for in-service inspection of radioactivity of the ion exchanger at the output of the elution column in the manufacture of chemical concentrates of uranium from ores. (J.B.). 4 figs

Water immersion in neonatal bereavement photography.

Science.gov (United States)

Duffey, Heather

2014-01-01

Water immersion in neonatal bereavement photography is a new technique intended to enhance the quality of the photographs provided to families following their loss. Water immersion appears to be most helpful following a second trimester fetal demise. This technique can be used by nurses, professional photographers and others in addition to more traditional neonatal bereavement photography. It does not require special skills or equipment and can be implemented in virtually any perinatal setting. The enhanced quality of photographs produced with this method can potentially provide a source of comfort to grieving families. © 2014 AWHONN.

Influence of pyridostigmine bromide on human thermoregulation during cold-water immersion

Energy Technology Data Exchange (ETDEWEB)

Cadarette, B.S.; Prusaczyk, W.K.; Sawka, M.N. (Army Research Inst. of Environmental Medicine, Natick, MA (United States))

1991-03-11

This study examined the effects of an oral 30 mg dose of pyridostigmine bromide (PYR) on thermoregulatory and physiological responses during cold stress. Six men were immersed in chilled stirred water for up to 180 minutes; once 2 hours following ingestion of PYR and once 2 hours following ingestion of a placebo (CON). With PYR, mean ({plus minus} SD) red blood cell cholinesterase inhibition was 33 ({plus minus}12)% at 110 minutes post-ingestion. Cholinesterase inhibition was negatively related to lean body mass. Abdominal discomfort caused termination in 3 of 6 PYR experiments ({bar X} immersion time = 117 min) but in no CON experiments ({bar X} immersion time = 142 min, p > 0.05). During immersion, metabolic rate increased significantly over pre-immersion levels, and increased with duration of immersion, but did not differ between conditions. PYR had no significant effect on rectal temperature, mean body temperature, thermal sensation, heart rate, or plasma cortisol concentration. It was concluded that a 30 mg dose of PYR does not increase susceptibility to hypothermia in humans immersed in cold-water; however, in combination with cold-stress, PYR may result in marked abdominal cramping and limit cold tolerance.

Isometric immersions and embeddings of locally Euclidean metrics in R2

International Nuclear Information System (INIS)

Sabitov, I Kh

1999-01-01

This paper deals with the problem of isometric immersions and embeddings of two-dimensional locally Euclidean metrics in the Euclidean plane. We find explicit formulae for the immersions of metrics defined on a simply connected domain and a number of sufficient conditions for the existence of isometric embeddings. In the case when the domain is multiply connected we find necessary conditions for the existence of isometric immersions and classify the cases when the metric admits no isometric immersion in the Euclidean plane

The Worldviews Network: Transformative Global Change Education in Immersive Environments

Science.gov (United States)

Hamilton, H.; Yu, K. C.; Gardiner, N.; McConville, D.; Connolly, R.; "Irving, Lindsay", L. S.

2011-12-01

Our modern age is defined by an astounding capacity to generate scientific information. From DNA to dark matter, human ingenuity and technologies create an endless stream of data about ourselves and the world of which we are a part. Yet we largely founder in transforming information into understanding, and understanding into rational action for our society as a whole. Earth and biodiversity scientists are especially frustrated by this impasse because the data they gather often point to a clash between Earth's capacity to sustain life and the decisions that humans make to garner the planet's resources. Immersive virtual environments offer an underexplored link in the translation of scientific data into public understanding, dialogue, and action. The Worldviews Network is a collaboration of scientists, artists, and educators focused on developing best practices for the use of immersive environments for science-based ecological literacy education. A central tenet of the Worldviews Network is that there are multiple ways to know and experience the world, so we are developing scientifically accurate, geographically relevant, and culturally appropriate programming to promote ecological literacy within informal science education programs across the United States. The goal of Worldviews Network is to offer transformative learning experiences, in which participants are guided on a process integrating immersive visual explorations, critical reflection and dialogue, and design-oriented approaches to action - or more simply, seeing, knowing, and doing. Our methods center on live presentations, interactive scientific visualizations, and sustainability dialogues hosted at informal science institutions. Our approach uses datasets from the life, Earth, and space sciences to illuminate the complex conditions that support life on earth and the ways in which ecological systems interact. We are leveraging scientific data from federal agencies, non-governmental organizations, and our

Declarative Knowledge Acquisition in Immersive Virtual Learning Environments

Science.gov (United States)

Webster, Rustin

2016-01-01

The author investigated the interaction effect of immersive virtual reality (VR) in the classroom. The objective of the project was to develop and provide a low-cost, scalable, and portable VR system containing purposely designed and developed immersive virtual learning environments for the US Army. The purpose of the mixed design experiment was…

Immersion enthalpies of activated carbon cloths as physical chemistry characterization parameter

International Nuclear Information System (INIS)

Rodriguez, Giovanny; Giraldo, Liliana; Moreno Juan Carlos

2009-01-01

The immersion enthalpies of five activated carbon cloths in carbon, CCl 4 , H 2 O and NaOH and HCl 0.1 M solutions are determined. The surface area values of the cloths are between 243 and 848 m 2 g-1 and exhibit a linear relationship with the immersion enthalpies in CCl 4 . The immersion enthalpies of carbon cloths are between 5.49 and 42.3 Jg-1 for CCl 4 and 3.83 and 7.54 Jg-1 for H 2 O. The immersion enthalpies in the solutions are related to the contents of acidic and basic groups and find that in the first case to increase the immersion enthalpy in NaOH increases the total acidity. Hydrophobic factor is calculated from the immersion enthalpies in CCl 4 and H 2 O, that indicate the interaction with polar and a polar compounds, and also relates to pHPZC each sample.

Multi-level emulation of complex climate model responses to boundary forcing data

Science.gov (United States)

Tran, Giang T.; Oliver, Kevin I. C.; Holden, Philip B.; Edwards, Neil R.; Sóbester, András; Challenor, Peter

2018-04-01

Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1's energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM's spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.

Color stability of ceramic brackets immersed in potentially staining solutions

Directory of Open Access Journals (Sweden)

Bruna Coser Guignone

2015-08-01

Full Text Available OBJECTIVE: To assess the color stability of five types of ceramic brackets after immersion in potentially staining solutions.METHODS: Ninety brackets were divided into 5 groups (n = 18 according to brackets commercial brands and the solutions in which they were immersed (coffee, red wine, coke and artificial saliva. The brackets assessed were Transcend (3M/Unitek, Monrovia, CA, USA, Radiance (American Orthodontics, Sheboygan, WI, USA, Mystique (GAC International Inc., Bohemia, NY, USA and Luxi II (Rocky Mountain Orthodontics, Denver, CO, USA. Chromatic changes were analyzed with the aid of a reflectance spectrophotometer and by visual inspection at five specific time intervals. Assessment periods were as received from the manufacturer (T0, 24 hours (T1, 72 hours (T2, as well as 7 days (T3 and 14 days (T4 of immersion in the aforementioned solutions. Results were submitted to statistical analysis with ANOVA and Bonferroni correction, as well as to a multivariate profile analysis for independent and paired samples with significance level set at 5%.RESULTS: The duration of the immersion period influenced color alteration of all tested brackets, even though these changes could not always be visually observed. Different behaviors were observed for each immersion solution; however, brackets immersed in one solution progressed similarly despite minor variations.CONCLUSIONS: Staining became more intense over time and all brackets underwent color alterations when immersed in the aforementioned solutions.

COGNITIVE AND PHYSIOLOGICAL INITIAL RESPONSES DURING COOL WATER IMMERSION

Directory of Open Access Journals (Sweden)

Alex Buoite Stella

2014-12-01

Full Text Available The initial responses during water immersion are the first mechanisms reacting to a strong stimulation of superficial nervous cold receptors. Cold shock induces tachycardia, hypertension, tachypnea, hyperventilation, and reduced end-tidal carbon dioxide fraction. These initial responses are observed immediately after the immersion, they last for about 3 min and have been also reported in water temperatures up to 25 °C. the aim of the present study was to observe cognitive and physiological functions during immersion in water at cool temperature. Oxygen consumption, ventilation, respiratory frequency, heart rate and expired fraction of oxygen were measured during the experiment. A code substitution test was used to evaluate executive functions and, specifically, working memory. This cognitive test was repeated consecutively 6 times, for a total duration of 5 minutes. Healthy volunteers (n = 9 performed the test twice in a random order, once in a dry thermoneutral environment and once while immersed head-out in 18 °C water. The results indicated that all the physiological parameters were increased during cool water immersion when compared with the dry thermoneutral condition (p < 0.05. Cognitive performance was reduced during the cool water immersion when compared to the control condition only during the first 2 min (p < 0.05. Our results suggest that planning the best rescue strategy could be partially impaired not only because of panic, but also because of the cold shock.

Thermal effects of dorsal head immersion in cold water on nonshivering humans.

Science.gov (United States)

Giesbrecht, Gordon G; Lockhart, Tamara L; Bristow, Gerald K; Steinman, Allan M

2005-11-01

Personal floatation devices maintain either a semirecumbent flotation posture with the head and upper chest out of the water or a horizontal flotation posture with the dorsal head and whole body immersed. The contribution of dorsal head and upper chest immersion to core cooling in cold water was isolated when the confounding effect of shivering heat production was inhibited with meperidine (Demerol, 2.5 mg/kg). Six male volunteers were immersed four times for up to 60 min, or until esophageal temperature = 34 degrees C. An insulated hoodless dry suit or two different personal floatation devices were used to create four conditions: 1) body insulated, head out; 2) body insulated, dorsal head immersed; 3) body exposed, head (and upper chest) out; and 4) body exposed, dorsal head (and upper chest) immersed. When the body was insulated, dorsal head immersion did not affect core cooling rate (1.1 degrees C/h) compared with head-out conditions (0.7 degrees C/h). When the body was exposed, however, the rate of core cooling increased by 40% from 3.6 degrees C/h with the head out to 5.0 degrees C/h with the dorsal head and upper chest immersed (P immersed (approximately 10%). The exaggerated core cooling during dorsal head immersion (40% increase) may result from the extra heat loss affecting a smaller thermal core due to intense thermal stimulation of the body and head and resultant peripheral vasoconstriction. Dorsal head and upper chest immersion in cold water increases the rate of core cooling and decreases potential survival time.

Adoption of the Creative Process According to the Immersive Method

Directory of Open Access Journals (Sweden)

Sonja Vuk

2015-09-01

Full Text Available The immersive method is a new concept of visual education that is better suited to the needs of students in contemporary post-industrial society. The features of the immersive method are: 1 it emerges from interaction with visual culture; 2 it encourages understanding of contemporary art (as an integral part of visual culture; and 3 it implements the strategies and processes of the dominant tendencies in contemporary art (new media art and relational art with the goal of adopting the creative process, expressing one’s thoughts and emotions, and communicating with the environment. The immersive method transfers the creative process from art to the process of creation by the students themselves. This occurs with the mediation of an algorithmic scheme that enables students to adopt ways to solve problems, to express thoughts and emotions, to develop ideas and to transfer these ideas to form, medium and material. The immersive method uses transfer in classes, the therapeutic aspect of art and “flow state” (the optimal experience of being immersed in an activity/aesthetic experience (a total experience that has a beginning, a process and a conclusion/immersive experience (comprehensive immersion in the present moment. This is a state leading to the sublimative effect of creation (identification with what has been expressed, as well as to self-actualisation. The immersive method teaches one to connect the context, social relations and the artwork as a whole in which one lives as an individual. The adopted creative process is implemented in a critical manner on one’s surrounding through analysis, aesthetic interventions, and ecologically and socially aware inclusion in the life of a community. The students gain the crucial meta-competence of a creative thinking process.

Helicon plasma with additional immersed antenna

International Nuclear Information System (INIS)

Aanesland, A; Charles, C; Boswell, R W; Fredriksen, A

2004-01-01

A 'primary' RF power (H-power) at 13.56 MHz is coupled to a plasma source excited by an external double saddle field Helicon antenna. A 'secondary' RF power (S-power), also at 13.56 MHz but with variable phase, is additionally coupled by inserting a second antenna in contact with the plasma through one end of the source. The immersed antenna can be grounded or floating, allowing a self-bias to form in the latter case. Changes in the plasma density and electron temperature are measured in both cases with varying power on the immersed antenna. The plasma potential increases dramatically with S-power in the grounded case, and is found to be similar in size to the sum of the plasma potential and the self-bias formed in the floating case for all powers. Hence, the sheath between the immersed antenna and the plasma is shown to be equal in both the grounded and floating cases. Although the power efficiency does not vary significantly as a function of the S-power, it is consistently lower for the grounded case possibly as a result of a dc current to ground. The plasma parameters are drastically changed as the phase between the two antennae are varied (floating case), and a sinusoidal function was fitted to the plasma parameters as a function of the phase shift. The calculated power loss to the antenna indicates that the power efficiency of the immersed antenna, as the phase is changed, is altered from 80% to 10%

Simulation Exploration through Immersive Parallel Planes

Energy Technology Data Exchange (ETDEWEB)

Brunhart-Lupo, Nicholas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bush, Brian W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gruchalla, Kenny M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Smith, Steve [Los Alamos Visualization Associates

2017-05-25

We present a visualization-driven simulation system that tightly couples systems dynamics simulations with an immersive virtual environment to allow analysts to rapidly develop and test hypotheses in a high-dimensional parameter space. To accomplish this, we generalize the two-dimensional parallel-coordinates statistical graphic as an immersive 'parallel-planes' visualization for multivariate time series emitted by simulations running in parallel with the visualization. In contrast to traditional parallel coordinate's mapping the multivariate dimensions onto coordinate axes represented by a series of parallel lines, we map pairs of the multivariate dimensions onto a series of parallel rectangles. As in the case of parallel coordinates, each individual observation in the dataset is mapped to a polyline whose vertices coincide with its coordinate values. Regions of the rectangles can be 'brushed' to highlight and select observations of interest: a 'slider' control allows the user to filter the observations by their time coordinate. In an immersive virtual environment, users interact with the parallel planes using a joystick that can select regions on the planes, manipulate selection, and filter time. The brushing and selection actions are used to both explore existing data as well as to launch additional simulations corresponding to the visually selected portions of the input parameter space. As soon as the new simulations complete, their resulting observations are displayed in the virtual environment. This tight feedback loop between simulation and immersive analytics accelerates users' realization of insights about the simulation and its output.

Degradation of partially immersed glass: A new perspective

Science.gov (United States)

Chinnam, R. K.; Fossati, P. C. M.; Lee, W. E.

2018-05-01

The International Simple Glass (ISG) is a six-component borosilicate glass which was developed as a reference for international collaborative studies on high level nuclear waste encapsulation. Its corrosion behaviour is typically examined when it is immersed in a leaching solution, or when it is exposed to water vapour. In this study, an alternative situation is considered in which the glass is only partially immersed for 7 weeks at a temperature of 90 °C. In this case, half of the glass sample is directly in the solution itself, and the other half is in contact with a water film formed by condensation of water vapour that evaporated from the solution. This results in a different degradation behaviour compared to standard tests in which the material is fully immersed. In particular, whilst in standard tests the system reaches a steady state with a very low alteration rate thanks to the formation of a protective gel layer, in partially-immersed tests this steady state could not be reached because of the continuous alteration from the condensate water film. The constant input of ions from the emerged part of the sample caused a supersaturation of the solution, which resulted in early precipitation of secondary crystalline phases. This setup mimics storage conditions once small amounts of water have entered a glass waste form containing canister. It offers a more realistic outlook of corrosion mechanisms happening in such situations than standard fully-immersed corrosion tests.

[Blood plasma volume dynamics in monkeys during immersion].

Science.gov (United States)

Krotov, V P; Burkovskaia, T E; Dotsenko, M A; Gordeev, Iu V; Nosovskiĭ, A M; Chel'naia, N A

2004-01-01

Dynamics of blood plasma volume (PV) was studied with indirect methods (hematocrit count, hemoglobin, total protein and high-molecular protein) during 9-d immersion of monkeys Macaca mulatta. The animals were donned in waterproof suits, motor restrained in space seat liners and immersed down to the xiphisternum. Two monkeys were immersed in the bath at one time. The suits were changed every day under ketamine (10 mg/kg of body mass). There were two groups with 12 animals in each. The first group was kept in the bath 3 days and the second--9 days. Prior to the experiment, the animals had been trained to stay in the seat liner put down into the dry bath. It was shown that already two days of exposure to the hydrostatic forces (approximately 15 mm Hg) and absence of negative pressure breathing reduced PV by 18-20% on the average in all animals. Subsequent PV dynamics was individual by character; however, PV deficit persisted during 4 days of immersion in the whole group. In this period, albumin filtration was increased significantly, whereas high-molecular protein filtration was increased to a less degree. During the remaining days in immersion PV regained normal values. Ten days of readaptation (reclined positioning of monkeys brought back into cage) raised VP beyond baseline values. This phenomenon can be attributed to the necessity to provide appropriate venous return and sufficient blood supply of organs and tissues following extension of blood vessels capacity.

Immersive bilingualism reshapes the core of the brain.

Science.gov (United States)

Pliatsikas, Christos; DeLuca, Vincent; Moschopoulou, Elisavet; Saddy, James Douglas

2017-05-01

Bilingualism has been shown to affect the structure of the brain, including cortical regions related to language. Less is known about subcortical structures, such as the basal ganglia, which underlie speech monitoring and language selection, processes that are crucial for bilinguals, as well as other linguistic functions, such as grammatical and phonological acquisition and processing. Simultaneous bilinguals have demonstrated significant reshaping of the basal ganglia and the thalamus compared to monolinguals. However, it is not clear whether these effects are due to learning of the second language (L2) at a very young age or simply due to continuous usage of two languages. Here, we show that bilingualism-induced subcortical effects are directly related to the amount of continuous L2 usage, or L2 immersion. We found significant subcortical reshaping in non-simultaneous (or sequential) bilinguals with extensive immersion in a bilingual environment, closely mirroring the recent findings in simultaneous bilinguals. Importantly, some of these effects were positively correlated to the amount of L2 immersion. Conversely, sequential bilinguals with comparable proficiency and age of acquisition (AoA) but limited immersion did not show similar effects. Our results provide structural evidence to suggestions that L2 acquisition continuously occurs in an immersive environment, and is expressed as dynamic reshaping of the core of the brain. These findings propose that second language learning in the brain is a dynamic procedure which depends on active and continuous L2 usage.

Estimation of debonded area in bearing babbitt metal by C-Scan method

Energy Technology Data Exchange (ETDEWEB)

Jung, Gye-jo; Park, Sang-ki [Korea Electric Power Research Inst., Taejeon (Korea); Cha, Seok-ju [Korea South Eastern Power Corp., Seoul (Korea). GEN Sector; Park, Young-woo [Chungnam National Univ., Taejeon (Korea). Mechatronics

2006-07-01

The debonding area which had a complex boundary was imaged with a immersion technique, and the acoustic image was compared with the actual area. The amplitude information from focused transducer can discriminate between a defected boundary area and a sound interface of dissimilar metal. The shape of irregular boundary and area was processed by a histogram equalization, after that, through the clustering and labelling, it makes the defect area cleared. Each pixel has ultrasonic intensity rate and represents a position data. The estimation error in measuring debonding area was within 4% by image processing technique. The validity of this immersion method and image equalizing technique has been done for the inspection of power plant turbine's thrust bearings. (orig.)

Influence of a peracetic acid-based immersion on indirect composite resin.

Science.gov (United States)

Samuel, Susana Maria Werner; Fracaro, Gisele Baggio; Collares, Fabrício Mezzomo; Leitune, Vicente Castelo Branco; Campregher, Ulisses Bastos

2011-06-01

The aim of this study was to evaluate the influence of immersion in a 0.2% peracetic acid-based disinfectant on the three-point flexural strength, water sorption and water solubility of an indirect composite resin. Specimens were produced according to ISO 4049:2000 specifications and were divided in two groups: Control group, with no disinfection and Disinfected group, with three 10 min immersions in the peracetic acid intercalated with 10 min immersions in sterile distilled water. All evaluations were conducted in compliance with ISO specifications. Three-point flexural strength, water sorption and solubility of indirect composite resin before and after immersion showed no statistical significant differences (p > 0.05) and met ISO standard requirements. Immersion in peracetic acid solution showed no influence in indirect composite resin tested properties.

Immersive Learning Simulations in Aircraft Maintenance Training

Science.gov (United States)

2010-02-15

You might just get a “serious game,” or “as proposed by the eLearning Guild, you could get an Immersive Learning Simulation.”3 Quoting the... eLearning Guild, Caspian Learning, in a report for the United Kingdom Ministry of Defense, defined an Immersive Learning Simulation (ILS) as “an optimized...training is necessary, and will be for the foreseeable future , our current computer systems can provide realistic training that could save substantial time

Plasma immersion ion implantation into insulating materials

International Nuclear Information System (INIS)

Tian Xiubo; Yang Shiqin

2006-01-01

Plasma immersion ion implantation (PIII) is an effective surface modification tool. During PIII processes, the objects to be treated are immersed in plasmas and then biased to negative potential. Consequently the plasma sheath forms and ion implantation may be performed. The pre-requirement of plasma implantation is that the object is conductive. So it seems difficult to treat the insulating materials. The paper focuses on the possibilities of plasma implantation into insulting materials and presents some examples. (authors)

Immersive Interaction, Manipulation and Analysis of Large 3D Datasets for Planetary and Earth Sciences

Science.gov (United States)

Pariser, O.; Calef, F.; Manning, E. M.; Ardulov, V.

2017-12-01

We will present implementation and study of several use-cases of utilizing Virtual Reality (VR) for immersive display, interaction and analysis of large and complex 3D datasets. These datasets have been acquired by the instruments across several Earth, Planetary and Solar Space Robotics Missions. First, we will describe the architecture of the common application framework that was developed to input data, interface with VR display devices and program input controllers in various computing environments. Tethered and portable VR technologies will be contrasted and advantages of each highlighted. We'll proceed to presenting experimental immersive analytics visual constructs that enable augmentation of 3D datasets with 2D ones such as images and statistical and abstract data. We will conclude by presenting comparative analysis with traditional visualization applications and share the feedback provided by our users: scientists and engineers.

The Feel Good Factor: Comparing Immersion by Design and Immersion by Default Models

Science.gov (United States)

Gallagher, Fiona; Leahy, Angela

2014-01-01

This article presents findings from an exploratory research project entitled "Gaelscoileanna and Multicultural classrooms: the potential for transfer to enhance L2 learning experiences". The project focussed on two language immersion contexts in Ireland which, despite obvious differences, share a range of significant commonalities. One…

Measuring participants' immersion in healthcare simulation: the development of an instrument.

Science.gov (United States)

Hagiwara, Magnus Andersson; Backlund, Per; Söderholm, Hanna Maurin; Lundberg, Lars; Lebram, Mikael; Engström, Henrik

2016-01-01

Immersion is important for simulation-based education; however, questionnaire-based instruments to measure immersion have some limitations. The aim of the present work is to develop a new instrument to measure immersion among participants in healthcare simulation scenarios. The instrument was developed in four phases: trigger identification, content validity scores, inter-rater reliability analysis and comparison with an existing immersion measure instrument. A modified Delphi process was used to develop the instrument and to establish validity and reliability. The expert panel consisted of 10 researchers. All the researchers in the team had previous experience of simulation in the health and/or fire and rescue services as researchers and/or educators and simulation designers. To identify triggers, the panel members independently screened video recordings from simulation scenarios. Here, a trigger is an event in a simulation that is considered a sign of reduced or enhanced immersion among simulation participants. The result consists of the Immersion Score Rating Instrument (ISRI). It contains 10 triggers, of which seven indicate reduced and three enhanced immersion. When using ISRI, a rater identifies trigger occurrences and assigns them strength between 1 and 3. The content validity analysis shows that all the 10 triggers meet an acceptable content validity index for items (I-CVI) standard. The inter-rater reliability (IRR) among raters was assessed using a two-way mixed, consistency, average-measures intra-class correlation (ICC). The ICC for the difference between weighted positive and negative triggers was 0.92, which indicates that the raters are in agreement. Comparison with results from an immersion questionnaire mirrors the ISRI results. In conclusion, we present a novel and non-intrusive instrument for identifying and rating the level of immersion among participants in healthcare simulation scenarios.

Using heart rate to prescribe physical exercise during head-out water immersion.

Science.gov (United States)

Kruel, Luiz F M; Peyré-Tartaruga, Leonardo A; Coertjens, Marcelo; Dias, Adriana B C; Da Silva, Rafael C; Rangel, Antônio C B

2014-01-01

The purpose of this study was to compare and correlate the effect of age group, sex, depth of water immersion, and the heart rate (HR) assessed out of the water on the HR behavior in individuals subjected to head-out water immersion. A total of 395 healthy individuals of both sexes, aged between 07 and 75 years, underwent vertical head-out water immersion. Heart rate was assessed out of the water in the supine and orthostatic (OHR) positions and at immersion depths corresponding to the ankle, knee, hip, umbilicus, xiphoid process, acromion, neck, and also the neck with the arms out of the water. The formula (ΔHR = OHR - HR immersion depth) was used to calculate the reduction in HR at each immersion depth. No age-based or sex-based differences in HR were found. The greater the depth of the water, the greater was the decrease in HR (p water-based exercise intensity performed during vertical immersion: OHR should be measured before the individual entering the aquatic environment; ΔHR should be measured according to the depth at which exercise is to be performed, and we suggest an adaptation to Karvonen's HRmax prediction formula (predicted HRmax: 220 - age - ΔHR) to prescribe and control the intensity of the exercise performed during vertical immersion.

Immersion Music: a Progress Report

OpenAIRE

Nakra, Teresa M.

2003-01-01

This paper describes the artistic projects undertaken at ImmersionMusic, Inc. (www.immersionmusic.org) during its three-yearexistence. We detail work in interactive performance systems,computer-based training systems, and concert production.

Changes in Landing Mechanics after Cold-Water Immersion

Science.gov (United States)

Wang, He; Toner, Michael M.; Lemonda, Thomas J.; Zohar, Mor

2010-01-01

The purpose of this study was to investigate the influence of cold-water immersion on kinematics and kinetics during a drop-landing task. On four separate occasions, 9 men performed drop-landings from a 0.6-m platform to a force platform following 30-min immersion to the hip-joint in thermoneutral water (control; 34 [degrees]C) and in cold water…

Ground-based remote sensing observation of the complex behaviour of the Marseille boundary layer during ESCOMPTE

Science.gov (United States)

Delbarre, H.; Augustin, P.; Saïd, F.; Campistron, B.; Bénech, B.; Lohou, F.; Puygrenier, V.; Moppert, C.; Cousin, F.; Fréville, P.; Fréjafon, E.

2005-03-01

Ground-based remote sensing systems have been used during the ESCOMPTE campaign, to continuously characterize the boundary-layer behaviour through many atmospheric parameters (wind, extinction and ozone concentration distribution, reflectivity, turbulence). This analysis is focused on the comparison of the atmospheric stratification retrieved from a UV angular ozone lidar, an Ultra High Frequency wind profiler and a sodar, above the area of Marseille, on June 26th 2001 (Intensive Observation Period 2b). The atmospheric stratification is shown to be very complex including two superimposed sea breezes, with an important contribution of advection. The temporal and spatial evolution of the stratification observed by the UV lidar and by the UHF radar are in good agreement although the origin of the echoes of these systems is quite different. The complexity of the dynamic situation has only partially been retrieved by a non-hydrostatic mesoscale model used with a 3 km resolution.

Practical boundary surveying legal and technical principles

CERN Document Server

Gay, Paul

2015-01-01

This guide to boundary surveying provides landowners, land surveyors, students and others with the necessary foundation to understand boundary surveying techniques and the common legal issues that govern boundary establishment.  Boundary surveying is sometimes mistakenly considered a strictly technical discipline with simple and straightforward technical solutions.  In reality, boundary establishment is often a difficult and complex matter, requiring years of experience and a thorough understanding of boundary law.  This book helps readers to understand the challenges often encountered by boundary surveyors and some of the available solutions. Using only simple and logically explained mathematics, the principles and practice of boundary surveying are demystified for those without prior experience, and the focused coverage of pivotal issues such as easements and setting lot corners will aid even licensed practitioners in untangling thorny cases. Practical advice on using both basic and advanced instruments ...

Calculation of the line shapes of radiators immersed in plasma

International Nuclear Information System (INIS)

Hayrapetian, A.S.

1987-01-01

This work reports the results of theoretical calculations of line shapes of radiators immersed in plasma. The fluctuating electric field of the plasma perturbs the atomic structure of the immersed ions or atoms. The perturbed line shape is an important diagnostic tool for the temperature and density measurements of plasma. The line-shape calculation here is done by first deriving the line-shape expression, then it is shown that the problem is equivalent to calculating the temperature Green's function of the bound electron. The total Hamiltonian of the system includes the atomic, plasma, and atom-plasma parts. The temperature Green's function is calculated perturbatively by expanding in orders of atom-plasma interaction. By solving a Dyson equation, the dressed Green's functions of the bound electrons are obtained. At this point, the line shape is calculated by an analytic continuation from the complex frequency plane to real line. To derive the atomic electron Green's function, the momentum integral in the self-energy is approximated by a Riemann sum. With this approximation, the algebraic form of the line shape is obtained for an undetermined number of terms in the Riemann sum. Numerical calculation of line shape is done by using this result

Immersive Exhibitions

DEFF Research Database (Denmark)

Achiam, Marianne

2015-01-01

The immersive exhibition is a specialized exhibition genre in museums, which creates the illusion of time and place by representing key characteristics of a reference world and by integrating the visitor in this three-dimensionally reconstructed world (Mortensen 2010). A successful representation...... of the reference world depends on three criteria: whether the exhibition is staged as a coherent whole with all the displayed objects supporting the representation, whether the visitor is integrated as a component of the exhibition, and whether the content and message of the exhibition become dramatized...

Significant improvement of optical traps by tuning standard water immersion objectives

International Nuclear Information System (INIS)

Reihani, S Nader S; Mir, Shahid A; Richardson, Andrew C; Oddershede, Lene B

2011-01-01

Focused infrared lasers are widely used for micromanipulation and visualization of biological specimens. An inherent practical problem is that off-the-shelf commercial microscope objectives are designed for use with visible and not infrared wavelengths. Less aberration is introduced by water immersion objectives than by oil immersion ones, however, even water immersion objectives induce significant aberration. We present a simple method to reduce the spherical aberration induced by water immersion objectives, namely by tuning the correction collar of the objective to a value that is ∼ 10% lower than the physical thickness of the coverslip. This results in marked improvements in optical trapping strengths of up to 100% laterally and 600% axially from a standard microscope objective designed for use in the visible range. The results are generally valid for any water immersion objective with any numerical aperture

Complexity of the AdS soliton

Science.gov (United States)

Reynolds, Alan P.; Ross, Simon F.

2018-05-01

We consider the holographic complexity conjectures in the context of the AdS soliton, which is the holographic dual of the ground state of a field theory on a torus with antiperiodic boundary conditions for fermions on one cycle. The complexity is a non-trivial function of the size of the circle with antiperiodic boundary conditions, which sets an IR scale in the dual geometry. We find qualitative differences between the calculations of complexity from spatial volume and action (CV and CA). In the CV calculation, the complexity for antiperiodic boundary conditions is smaller than for periodic, and decreases monotonically with increasing IR scale. In the CA calculation, the complexity for antiperiodic boundary conditions is larger than for periodic, and initially increases with increasing IR scale, eventually decreasing to zero as the IR scale becomes of order the UV cutoff. We compare these results to a simple calculation for free fermions on a lattice, where we find the complexity for antiperiodic boundary conditions is larger than for periodic.

An investigation of ozone and planetary boundary layer dynamics over the complex topography of Grenoble combining measurements and modeling

OpenAIRE

Couach , O.; Balin , I.; Jiménez , R.; Ristori , P.; Perego , S.; Kirchner , F.; Simeonov , V.; Calpini , B.; Van Den Bergh , H.

2003-01-01

This paper concerns an evaluation of ozone (O3) and planetary boundary layer (PBL) dynamics over the complex topography of the Grenoble region through a combination of measurements and mesoscale model (METPHOMOD) predictions for three days, during July 1999. The measurements of O3 and PBL structure were obtained with a Differential Absorption Lidar (DIAL) system, situated 20 km south of Grenoble at Vif (310 m ASL). The combined lidar observations ...

Effects of immersion water temperature on whole-body fluid distribution in humans.

Science.gov (United States)

Stocks, J M; Patterson, M J; Hyde, D E; Jenkins, A B; Mittleman, K D; Taylor, N A S

2004-09-01

In this study, we quantified acute changes in the intracellular and extracellular fluid compartments during upright neutral- and cold-water immersion. We hypothesized that, during short-term cold immersion, fluid shifts would be wholly restricted to the extracellular space. Seven males were immersed 30 days apart: control (33.3 degrees SD 0.6 degrees C); and cold (18.1 degrees SD 0.3 degrees C). Posture was controlled for 4 h prior to a 60-min seated immersion. Significant reductions in terminal oesophageal (36.9 degrees +/- 0.1 degrees -36.3 degrees +/- 0.1 degrees C) and mean skin temperatures (30.3 degrees +/- 0.3 degrees -23.0 degrees +/- 0.3 degrees C) were observed during the cold, but not the control immersion. Both immersions elicited a reduction in intracellular fluid [20.17 +/- 6.02 mL kg(-1) (control) vs. 22.72 +/- 9.90 mL kg(-1)], while total body water (TBW) remained stable. However, significant plasma volume (PV) divergence was apparent between the trials at 60 min [12.5 +/- 1.0% (control) vs. 6.1 +/- 3.1%; P cold immersion, consistent with its role in PV regulation. We observed that, regardless of the direction of the PV change, both upright immersions elicited reductions in intracellular fluid. These observations have two implications. First, one cannot assume that PV changes reflect those of the entire extracellular compartment. Second, since immersion also increases interstitial fluid pressure, fluid leaving the interstitium must have been rapidly replaced by intracellular water.

Upper Domination: Towards a Dichotomy Through Boundary Properties

KAUST Repository

AbouEisha, Hassan M.

2017-07-14

An upper dominating set in a graph is a minimal dominating set of maximum cardinality. The problem of finding an upper dominating set is generally NP-hard. We study the complexity of this problem in finitely defined classes of graphs and conjecture that the problem admits a complexity dichotomy in this family. A helpful tool to study the complexity of an algorithmic problem is the notion of boundary classes. However, none of such classes has been identified so far for the upper dominating set problem. We discover the first boundary class for this problem and prove the dichotomy for monogenic classes.

Voluntary respiratory control and cerebral blood flow velocity upon ice-water immersion

DEFF Research Database (Denmark)

Mantoni, Teit; Rasmussen, Jakob Højlund; Belhage, Bo

2008-01-01

INTRODUCTION: In non-habituated subjects, cold-shock response to cold-water immersion causes rapid reduction in cerebral blood flow velocity (approximately 50%) due to hyperventilation, increasing risk of syncope, aspiration, and drowning. Adaptation to the response is possible, but requires...... velocity (CBFV) was measured together with ventilatory parameters and heart rate before, during, and after immersion. RESULTS: Within seconds after immersion in ice-water, heart rate increased significantly from 95 +/- 8 to 126 +/- 7 bpm (mean +/- SEM). Immersion was associated with an elevation...

Secondary immune response of rainbow trout following repeated immersion vaccination

DEFF Research Database (Denmark)

Jaafar, R. M.; Al-Jubury, A.; Chettri, J. K.

2017-01-01

Teleosts are able to raise a protective immune response, comprising both innate and adaptive elements, against various pathogens. This is the basis for a widespread use of vaccines, administered as injection or immersion, in the aquaculture industry. It has been described that repeated injection...... vaccination of fish raises a secondary immune response, consisting of rapid, accelerated and increased antibody reaction. This study reports how rainbow trout responds to repeated immersion vaccination against yersiniosis (ERM) caused by the bacterial pathogen Yersinia ruckeri. It was found that rainbow trout...... does not raise a classical secondary response following repeated immersion vaccination. Serum antibody titres were merely slightly increased even after three immunizations, using 30-s immersion into a bacterin consisting of formalin-inactivated Y. ruckeri (serotype O1, biotypes 1 and 2), performed over...

Secondary immune response of rainbow trout following repeated immersion vaccination

DEFF Research Database (Denmark)

Jaafar, R. M.; Al-Jubury, Azmi; Chettri, Jiwan Kumar

2018-01-01

Teleosts are able to raise a protective immune response, comprising both innate and adaptive elements, against various pathogens. This is the basis for a widespread use of vaccines, administered as injection or immersion, in the aquaculture industry. It has been described that repeated injection...... vaccination of fish raises a secondary immune response, consisting of rapid, accelerated and increased antibody reaction. This study reports how rainbow trout responds to repeated immersion vaccination against yersiniosis (ERM) caused by the bacterial pathogen Yersinia ruckeri. It was found that rainbow trout...... does not raise a classical secondary response following repeated immersion vaccination. Serum antibody titres were merely slightly increased even after three immunizations, using 30-s immersion into a bacterin consisting of formalin-inactivated Y. ruckeri (serotype O1, biotypes 1 and 2), performed over...

HIFU scattering by the ribs: constrained optimisation with a complex surface impedance boundary condition

Science.gov (United States)

Gélat, P.; ter Haar, G.; Saffari, N.

2014-04-01

High intensity focused ultrasound (HIFU) enables highly localised, non-invasive tissue ablation and its efficacy has been demonstrated in the treatment of a range of cancers, including those of the kidney, prostate and breast. HIFU offers the ability to treat deep-seated tumours locally, and potentially bears fewer side effects than more established treatment modalities such as resection, chemotherapy and ionising radiation. There remains however a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to ablate tissue at the required foci whilst minimising the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. This sometimes results in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. Previously, a boundary element (BE) approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data [1]. Dissipative mechanisms inside the propagating medium have since been implemented, together with a complex surface impedance condition at the surface of the ribs. A reformulation of the boundary element equations as a constrained optimisation problem was carried out to determine the complex surface velocities of a multi-element HIFU array which generated the acoustic pressure field that best fitted a required acoustic pressure distribution in a least-squares sense. This was done whilst ensuring that an acoustic dose rate parameter at the surface of the ribs was kept below a specified threshold. The methodology was tested at an

Comparing contact and immersion freezing from continuous flow diffusion chambers

Directory of Open Access Journals (Sweden)

B. Nagare

2016-07-01

Full Text Available Ice nucleating particles (INPs in the atmosphere are responsible for glaciating cloud droplets between 237 and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. To date, direct comparisons of contact and immersion freezing with the same INP, for similar residence times and concentrations, are lacking. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data were obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH using 80 µm diameter droplets, which can interact with INPs for residence times of 2 and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter Arizona Test Dust (ATD and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm−3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm−3 for AgI. For concentrations  <  5000 cm−3, the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with immersion freezing or adhesion freezing. With “adhesion freezing”, we refer to a contact nucleation

The effects of cold immersion and hand protection on grip strength.

Science.gov (United States)

Vincent, M J; Tipton, M J

1988-08-01

The maximal voluntary grip strength (MVGS) of male volunteers was examined following a series of five intermittent 2 min cold water (5 degrees C) immersions of the unprotected hand or forearm. MVGS changes due to wearing a protective glove were also investigated. The surface electrical activity over the hand flexor muscles was recorded, as was the skin temperature of the hand and forearm. MVGS decreased significantly (p less than 0.01) following hand immersions (16%) and forearm immersion (13%). The majority of these reductions occurred during the first 2-min period of immersion. The effect of wearing a glove after unprotected hand cooling also produced significant (p less than 0.01) MVGS reductions which averaged 14%. These reductions were in addition to those caused by hand cooling. We conclude that both hand and forearm protection are important for the maintenance of hand-grip strength following cold water immersion.

From Perceptual Apparatus to Immersive Field of Experience

DEFF Research Database (Denmark)

Wieczorek, Izabela

2014-01-01

Peter Sloterdijk ascribes to architecture the “the design of immersions” and hence the “production of embedding situations” or atmosphere (2011 (2006): 108-109), which as devised by Gernot Böhme becomes a fundamental concept of a new aesthetics (1993). Atmosphere implies affective immersion...... the immersive experiences relocate the vision within a “carnal density” (1992: 150), regaining all sensory modalities. Diverse perceptual apparatuses also defined a larger disciplinary expansion in the field of architecture and design. Conceived as sensorial activators, intensifiers of phenomena......, constitute a framework for a re-invention of perceptual worlds, providing a basis for tracing the conceptual contours of atmospheric perception, as well as for discerning the means of the production of space understood as an immersive field of experience. References: Böhme, G. (1993). "Atmosphere...

Complexity of formation in holography

International Nuclear Information System (INIS)

Chapman, Shira; Marrochio, Hugo; Myers, Robert C.

2017-01-01

It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the ‘complexity of formation’ (DOI: 10.1103/PhysRevLett.116.191301; 10.1103/PhysRevD.93.086006), i.e. the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions d>2, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case d=2, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

Complexity of formation in holography

Energy Technology Data Exchange (ETDEWEB)

Chapman, Shira [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Marrochio, Hugo [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Department of Physics & Astronomy and Guelph-Waterloo Physics Institute,University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Myers, Robert C. [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada)

2017-01-16

It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the ‘complexity of formation’ (DOI: 10.1103/PhysRevLett.116.191301; 10.1103/PhysRevD.93.086006), i.e. the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions d>2, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case d=2, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

Bulk and boundary invariants for complex topological insulators from K-theory to physics

CERN Document Server

Prodan, Emil

2016-01-01

This monograph offers an overview of rigorous results on fermionic topological insulators from the complex classes, namely, those without symmetries or with just a chiral symmetry. Particular focus is on the stability of the topological invariants in the presence of strong disorder, on the interplay between the bulk and boundary invariants and on their dependence on magnetic fields. The first part presents motivating examples and the conjectures put forward by the physics community, together with a brief review of the experimental achievements. The second part develops an operator algebraic approach for the study of disordered topological insulators. This leads naturally to use analysis tools from K-theory and non-commutative geometry, such as cyclic cohomology, quantized calculus with Fredholm modules and index pairings. New results include a generalized Streda formula and a proof of the delocalized nature of surface states in topological insulators with non-trivial invariants. The concluding chapter connect...

Coating manganese oxide onto graphite electrodes by immersion for electrochemical capacitors

International Nuclear Information System (INIS)

Lin, C.-C.; Chen, H.-W.

2009-01-01

In this study, manganese oxide was coated on a graphite electrode by immersion. Durations for immersion were varied to control the amount of manganese oxide coated onto the electrode surface. Maximum capacitance of 556 mF cm -2 was obtained in 0.5 M LiCl and with better/superior conditions (immersion time = 80 min and potential scan rate = 10 mV s -1 ). In addition, cyclic voltammograms of the prepared electrode at different potential scan rates exhibited the approximately rectangular and symmetric current-potential characteristics of a capacitor. Furthermore, the chronopotentiometry (CP) charge-discharge curves of the electrode prepared at 80 min of immersion time with a constant current of 1 mA were symmetric and similar isosceles triangles, which demonstrate its high electrochemical reversibility and good stability. Finally, under scanning electron microscope (SEM), the surface of the electrode prepared at 80 min of immersion time and after 1500 cycles of potential cycling revealed that numerously three-dimensional network of macropores appeared on large spherical grains

Enhanced biodiversity beyond marine reserve boundaries: the cup spillith over.

Science.gov (United States)

Russ, Garry R; Alcala, Angel C

2011-01-01

Overfishing can have detrimental effects on marine biodiversity and the structure of marine ecosystems. No-take marine reserves (NTMRs) are much advocated as a means of protecting biodiversity and ecosystem structure from overharvest. In contrast to terrestrial protected areas, NTMRs are not only expected to conserve or recover biodiversity and ecosystems within their boundaries, but also to enhance biodiversity beyond their boundaries by exporting species richness and more complex biological communities. Here we show that species richness of large predatory reef fish increased fourfold and 11-fold inside two Philippine no-take marine reserves over 14 and 25 years, respectively. Outside one reserve (Apo) the species richness also increased. This increase beyond the Apo reserve boundary was 78% higher closer to the boundary (200-250 m) than farther from it (250-500 m). The increase in richness beyond the boundary could not be explained by improvements over time in habitat or prey availability. Furthermore, community composition of predatory fish outside but close to (200-250 m) the Apo reserve became very similar to that inside the reserve over time, almost converging with it in multivariate space after 26 years of reserve protection. This is consistent with the suggestion that, as community composition inside Apo reserve increased in complexity, this complexity spilled over the boundary into nearby fished areas. Clearly, the spillover of species richness and community complexity is a direct consequence of the spillover of abundance of multiple species. However, this spillover of species richness and community complexity demonstrates an important benefit of biodiversity and ecosystem export from reserves, and it provides hope that reserves can help to reverse the decline of marine ecosystems and biodiversity.

Takotsubo Cardiomyopathy in the Setting of Immersion Pulmonary Edema: Case Series

OpenAIRE

Reed, Tara; Sorrentino, Dante; Azuma, Steven

2015-01-01

Immersion Pulmonary Edema is a unique medical condition being increasingly described in the medical literature as sudden-onset pulmonary edema in the setting of scuba diving and or swimming. Case reports have associated immersion pulmonary edema with cardiac dysfunction, but there are no known case reports describing submersion pulmonary edema resulting in Takotsubo cardiomyopathy. We report on three patients with unique presentations of immersion pulmonary edema with associated Takotsubo car...

Strategies for Teaching English Abroad: The Immersion Classroom

Directory of Open Access Journals (Sweden)

Ishrat Suri

2016-06-01

Full Text Available English language development is best laid on the foundation of natural and social interactions which requires a great deal of sacrifice from educators who teach abroad (Snow, 1997. Learning to speak a new language grants learners a passport and highly coveted citizenship to a culturally interconnected world (Met & Lorenz, 1993; however, educators often face a daunting challenge. They must come up with comprehensive strategies which ensure that learners obtain requisite skills faster than might otherwise be deemed necessary. They must also employ non-verbal communication in place of the native language and secure a total commitment from students (Fortune, 2000. Finally, educators must leverage the brain’s information processing and retention ability against a very formidable threat: forgetting. The paper focuses on language immersion classroom strategies currently being used around the world, along with a discussion on how technology has been used to increase language and cultural competencies. This research has implications for educators and administrators who are interested in the impact that technology access has on learning when paired with a total immersion approach. This paper will present recommendations for international English language immersion programs, whose goals are to develop a total cultural competency for students aged 5-25 in environments where there are limited resources to aid in language immersion.

Immersion in water in labour and birth

Directory of Open Access Journals (Sweden)

Elizabeth R. Cluett

Full Text Available BACKGROUND: Enthusiasts suggest that labouring in water and waterbirth increase maternal relaxation, reduce analgesia requirements and promote a midwifery model of care. Critics cite the risk of neonatal water inhalation and maternal/neonatal infection. OBJECTIVES: To assess the evidence from randomised controlled trials about immersion in water during labour and waterbirth on maternal, fetal, neonatal and caregiver outcomes. METHODS: Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2011 and reference lists of retrieved studies. Selection criteria: Randomised controlled trials comparing immersion in any bath tub/pool with no immersion, or other non-pharmacological forms of pain management during labour and/or birth, in women during labour who were considered to be at low risk of complications, as defined by the researchers. Data collection and analysis: We assessed trial eligibility and quality and extracted data independently. One review author entered data and the other checked for accuracy. MAIN RESULTS: This review includes 12 trials (3,243 women: 8 related to just the first stage of labour: one to early versus late immersion in the first stage of labour; two to the first and second stages; and another to the second stage only. We identified no trials evaluating different baths/pools, or the management of third stage of labour. Results for the first stage of labour showed there was a significant reduction in the epidural/spinal/paracervical analgesia/anaesthesia rate amongst women allocated to water immersion compared to controls (478/1,254 versus 529/1,245; risk ratio (RR 0.90; 95% confidence interval (CI 0.82 to 0.99, six trials. There was also a reduction in duration of the first stage of labour (mean difference -32.4 minutes; 95% CI -58.7 to -6.13. There was no difference in assisted vaginal deliveries (RR 0.86; 95% CI 0.71 to 1.05, seven trials, caesarean sections (RR 1.21; 95% CI 0

Evaluating the Effects of Immersive Embodied Interaction on Cognition in Virtual Reality

Science.gov (United States)

Parmar, Dhaval

Virtual reality is on its advent of becoming mainstream household technology, as technologies such as head-mounted displays, trackers, and interaction devices are becoming affordable and easily available. Virtual reality (VR) has immense potential in enhancing the fields of education and training, and its power can be used to spark interest and enthusiasm among learners. It is, therefore, imperative to evaluate the risks and benefits that immersive virtual reality poses to the field of education. Research suggests that learning is an embodied process. Learning depends on grounded aspects of the body including action, perception, and interactions with the environment. This research aims to study if immersive embodiment through the means of virtual reality facilitates embodied cognition. A pedagogical VR solution which takes advantage of embodied cognition can lead to enhanced learning benefits. Towards achieving this goal, this research presents a linear continuum for immersive embodied interaction within virtual reality. This research evaluates the effects of three levels of immersive embodied interactions on cognitive thinking, presence, usability, and satisfaction among users in the fields of science, technology, engineering, and mathematics (STEM) education. Results from the presented experiments show that immersive virtual reality is greatly effective in knowledge acquisition and retention, and highly enhances user satisfaction, interest and enthusiasm. Users experience high levels of presence and are profoundly engaged in the learning activities within the immersive virtual environments. The studies presented in this research evaluate pedagogical VR software to train and motivate students in STEM education, and provide an empirical analysis comparing desktop VR (DVR), immersive VR (IVR), and immersive embodied VR (IEVR) conditions for learning. This research also proposes a fully immersive embodied interaction metaphor (IEIVR) for learning of computational

Prolonged whole body immersion in cold water: hormonal and metabolic changes.

Science.gov (United States)

Smith, D J; Deuster, P A; Ryan, C J; Doubt, T J

1990-03-01

To characterize metabolic and hormonal responses during prolonged whole body immersion, 16 divers wearing dry suits completed four immersions in 5 degrees C water during each of two 5-day air saturation dives at 6.1 meters of sea water. One immersion began in the AM (1000 h) and one began in the PM (2200 h) to evaluate diurnal variations. Venous blood samples were obtained before and after completion of each immersion. Cortisol and ACTH levels demonstrated diurnal variation, with larger increases occurring after PM immersions. A greater than three-fold postimmersion increase occurred in norepinephrine (NE). There were significant increases in triiodothyronine (T3) uptake and epinephrine, but no change in T3, thyroxine, thyrotrophic hormone, and dopamine. Postimmersion free fatty acid levels increased 409% from preimmersion levels; glucose levels declined, and lactate increased significantly. Only changes in NE correlated significantly with changes in rectal temperature. In summary, when subjects are immersed in cold water for prolonged periods, with a slow rate of body cooling afforded by thermal protection and intermittent exercise, hormonal and metabolic changes occur that are similar in direction and magnitude to short-duration unprotected exposures. Except for cortisol and ACTH, none of the other measured variables exhibited diurnal alterations.

Evaluation of Spatial Perspective Taking Skills using a Digital Game with Different Levels of Immersion

Directory of Open Access Journals (Sweden)

Laura Freina

2017-09-01

Full Text Available The present paper presents the results of an experiment aimed at assessing the impact of different levels of immersion on performance in a Spatial Perspective Taking (SPT task. Since SPT is an embodied skill, the hypothesis was that the more immersive a tool is, the better the performance should be. Ninety-eight students from a local primary school have played with three different versions of a game: (i completely immersive with a Head Mounted Display, (ii semi immersive on a computer screen and (iii non-immersive where no movements were possible for the player. Results showed that in the immersive versions of the game, players obtained higher scores than in the non-immersive version, suggesting that an immersive tool can better support performance in a SPT task.

The impact of immersion protection requirements on hair dryer electrocutions in the USA.

Science.gov (United States)

Rodgers, Gregory B; Garland, Sarah

2012-12-01

To evaluate the effectiveness of the immersion protection requirements of a voluntary safety standard for portable handheld hair dryers in preventing electrocution deaths in the USA. The present work was an interrupted time series study design. Data on annual hair dryer-related electrocution deaths resulting from water contact were developed for the 1980-2007 study period. A multivariate Poisson regression model for rate data was used to evaluate the impact of the immersion protection requirements during the post-intervention period. The analysis controlled for the estimated number of hair dryers in use and the estimated number of US homes equipped with ground fault circuit interrupters, safety devices that would address hair dryer electrocutions even in the absence of the immersion protection requirements of the voluntary standard. The implementation of the 1987 and 1991 immersion protection requirements of the voluntary standard for portable handheld hair dryers was the intervention studied. The main outcome measure was the estimated reduction in the hair dryer electrocution rate associated with the immersion protection requirements of the voluntary standard. After controlling for covariates, the immersion protection requirements were estimated to reduce the rate of hair dryer immersion electrocution deaths by 96.6% (95% CI, 90.8% to 98.8%). This suggests the prevention of about 280 immersion electrocution deaths involving hair dryers during the post-intervention period (1987-2007). The immersion protection requirements of the voluntary safety standard for hair dryers have been highly effective in reducing hair dryer electrocutions.

Airborne measurements of turbulent trace gas fluxes and analysis of eddy structure in the convective boundary layer over complex terrain

Science.gov (United States)

Hasel, M.; Kottmeier, Ch.; Corsmeier, U.; Wieser, A.

2005-03-01

Using the new high-frequency measurement equipment of the research aircraft DO 128, which is described in detail, turbulent vertical fluxes of ozone and nitric oxide have been calculated from data sampled during the ESCOMPTE program in the south of France. Based on airborne turbulence measurements, radiosonde data and surface energy balance measurements, the convective boundary layer (CBL) is examined under two different aspects. The analysis covers boundary-layer convection with respect to (i) the control of CBL depth by surface heating and synoptic scale influences, and (ii) the structure of convective plumes and their vertical transport of ozone and nitric oxides. The orographic structure of the terrain causes significant differences between planetary boundary layer (PBL) heights, which are found to exceed those of terrain height variations on average. A comparison of boundary-layer flux profiles as well as mean quantities over flat and complex terrain and also under different pollution situations and weather conditions shows relationships between vertical gradients and corresponding turbulent fluxes. Generally, NO x transports are directed upward independent of the terrain, since primary emission sources are located near the ground. For ozone, negative fluxes are common in the lower CBL in accordance with the deposition of O 3 at the surface. The detailed structure of thermals, which largely carry out vertical transports in the boundary layer, are examined with a conditional sampling technique. Updrafts mostly contain warm, moist and NO x loaded air, while the ozone transport by thermals alternates with the background ozone gradient. Evidence for handover processes of trace gases to the free atmosphere can be found in the case of existing gradients across the boundary-layer top. An analysis of the size of eddies suggests the possibility of some influence of the heterogeneous terrain in mountainous area on the length scales of eddies.

A nearest-neighbour discretisation of the regularized stokeslet boundary integral equation

Science.gov (United States)

Smith, David J.

2018-04-01

The method of regularized stokeslets is extensively used in biological fluid dynamics due to its conceptual simplicity and meshlessness. This simplicity carries a degree of cost in computational expense and accuracy because the number of degrees of freedom used to discretise the unknown surface traction is generally significantly higher than that required by boundary element methods. We describe a meshless method based on nearest-neighbour interpolation that significantly reduces the number of degrees of freedom required to discretise the unknown traction, increasing the range of problems that can be practically solved, without excessively complicating the task of the modeller. The nearest-neighbour technique is tested against the classical problem of rigid body motion of a sphere immersed in very viscous fluid, then applied to the more complex biophysical problem of calculating the rotational diffusion timescales of a macromolecular structure modelled by three closely-spaced non-slender rods. A heuristic for finding the required density of force and quadrature points by numerical refinement is suggested. Matlab/GNU Octave code for the key steps of the algorithm is provided, which predominantly use basic linear algebra operations, with a full implementation being provided on github. Compared with the standard Nyström discretisation, more accurate and substantially more efficient results can be obtained by de-refining the force discretisation relative to the quadrature discretisation: a cost reduction of over 10 times with improved accuracy is observed. This improvement comes at minimal additional technical complexity. Future avenues to develop the algorithm are then discussed.

Fifty Years of Boundary-Layer Theory and Experiment

Science.gov (United States)

Dryden, Hugh L.

1955-01-01

The year 1954 marked the 50th anniversary of the Prandtl boundary-layer theory from which we may date the beginning of man's understanding of the dynamics of real fluids. A backward look at this aspect of the history of the last 50 years may be instructive. This paper (1) attempts to compress the events of those 50 years into a few thousand words, to tell in this brief space the interesting story of the development of a new concept, its slow acceptance and growth, its spread from group to group within its country of origin, and its diffusion to other countries of the world. The original brief paper of Prandtl (2) was presented at the Third International Mathematical Congress at Heidelberg in 1904 and published in the following year. It was an attempt to explain the d'Alembert paradox, namely, that the neglect of the small friction of air in the theory resulted in the prediction of zero resistance to motion. Prandtl set himself the task of computing the motion of a fluid of small friction, so small that its effect could be neglected everywhere except where large velocity differences were present or a cumulative effect of friction occurred This led to the concept of boundary layer, or transition layer, near the wall of a body immersed in a fluid stream in which the velocity rises from zero to the free-stream value. It is interesting that Prandtl used the term Grenzsehicht (boundary layer) only once and the term Ubergangsschicht (transition layer) seven times in the brief article. Later writers also used Reibungsschicht (friction layer), but most writers today use Grenzschicht (boundary layer).

Cold-water immersion (cryotherapy for preventing and treating muscle soreness after exercise

Directory of Open Access Journals (Sweden)

Chris Bleakley

Full Text Available BACKGROUND: Many strategies are in use with the intention of preventing or minimizing delayed onset muscle soreness and fatigue after exercise. Cold-water immersion, in water temperatures of less than 15 °C, is currently one of the most popular interventional strategies used after exercise. OBJECTIVES: To determine the effects of cold-water immersion in the management of muscle soreness after exercise. SEARCH METHODS: In February 2010, we searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library (2010, Issue 1, Medline, Embase, Cumulative Index to Nursing and Allied Health (CINAHL, British Nursing Index and archive (BNI, and the Physiotherapy Evidence Database (PEDro. We also searched the reference lists of articles, handsearched journals and conference proceedings and contacted experts. In November 2011, we updated the searches of Central (2011, Issue 4, Medline (up to November Week 3 2011, Embase (to 2011 Week 46 and CINAHL (to 28 November 2011 to check for more recent publications. SELECTION CRITERIA: Randomized and quasi-randomized trials comparing the effect of using cold-water immersion after exercise with: passive intervention (rest/no intervention, contrast immersion, warm-water immersion, active recovery, compression, or a different duration/dosage of cold-water immersion. Primary outcomes were pain (muscle soreness or tenderness (pain on palpation, and subjective recovery (return to previous activities without signs or symptoms. DATA COLLECTION AND ANALYSIS: Three authors independently evaluated study quality and extracted data. Some of the data were obtained following author correspondence or extracted from graphs in the trial reports. Where possible, data were pooled using the fixed-effect model. MAIN RESULTS: Seventeen small trials were included, involving a total of 366 participants. Study quality was low. The temperature, duration and

The "Total Immersion" Meeting Environment.

Science.gov (United States)

Finkel, Coleman

1980-01-01

The designing of intelligently planned meeting facilities can aid management communication and learning. The author examines the psychology of meeting attendance; architectural considerations (lighting, windows, color, etc.); design elements and learning modes (furniture, walls, audiovisuals, materials); and the idea of "total immersion meeting…

Simulation Exploration through Immersive Parallel Planes: Preprint

Energy Technology Data Exchange (ETDEWEB)

Brunhart-Lupo, Nicholas; Bush, Brian W.; Gruchalla, Kenny; Smith, Steve

2016-03-01

We present a visualization-driven simulation system that tightly couples systems dynamics simulations with an immersive virtual environment to allow analysts to rapidly develop and test hypotheses in a high-dimensional parameter space. To accomplish this, we generalize the two-dimensional parallel-coordinates statistical graphic as an immersive 'parallel-planes' visualization for multivariate time series emitted by simulations running in parallel with the visualization. In contrast to traditional parallel coordinate's mapping the multivariate dimensions onto coordinate axes represented by a series of parallel lines, we map pairs of the multivariate dimensions onto a series of parallel rectangles. As in the case of parallel coordinates, each individual observation in the dataset is mapped to a polyline whose vertices coincide with its coordinate values. Regions of the rectangles can be 'brushed' to highlight and select observations of interest: a 'slider' control allows the user to filter the observations by their time coordinate. In an immersive virtual environment, users interact with the parallel planes using a joystick that can select regions on the planes, manipulate selection, and filter time. The brushing and selection actions are used to both explore existing data as well as to launch additional simulations corresponding to the visually selected portions of the input parameter space. As soon as the new simulations complete, their resulting observations are displayed in the virtual environment. This tight feedback loop between simulation and immersive analytics accelerates users' realization of insights about the simulation and its output.

A numerical method for osmotic water flow and solute diffusion with deformable membrane boundaries in two spatial dimension

Science.gov (United States)

Yao, Lingxing; Mori, Yoichiro

2017-12-01

Osmotic forces and solute diffusion are increasingly seen as playing a fundamental role in cell movement. Here, we present a numerical method that allows for studying the interplay between diffusive, osmotic and mechanical effects. An osmotically active solute obeys a advection-diffusion equation in a region demarcated by a deformable membrane. The interfacial membrane allows transmembrane water flow which is determined by osmotic and mechanical pressure differences across the membrane. The numerical method is based on an immersed boundary method for fluid-structure interaction and a Cartesian grid embedded boundary method for the solute. We demonstrate our numerical algorithm with the test case of an osmotic engine, a recently proposed mechanism for cell propulsion.

Acute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failure.

Science.gov (United States)

Radtke, Thomas; Poerschke, Daniel; Wilhelm, Matthias; Trachsel, Lukas D; Tschanz, Hansueli; Matter, Friederike; Jauslin, Daniel; Saner, Hugo; Schmid, Jean-Paul

2016-04-01

The haemodynamic response to Finnish sauna and subsequent cold-water immersion in heart failure patients is unknown. Haemodynamic response to two consecutive Finnish sauna (80℃) exposures, followed by a final head-out cold-water immersion (12℃) was measured in 37 male participants: chronic heart failure (n = 12, 61.8 ± 9.2 years), coronary artery disease (n = 13, 61.2 ± 10.6 years) and control subjects (n = 12, 60.9 ± 8.9 years). Cardiac output was measured non-invasively with an inert gas rebreathing method prior to and immediately after the first sauna exposure and after cold-water immersion, respectively. Blood pressure was measured before, twice during and after sauna. The autonomic nervous system was assessed by power spectral analysis of heart rate variability. Total power, low-frequency and high-frequency components were evaluated. The low frequency/high frequency ratio was used as a marker of sympathovagal balance. Sauna and cold-water immersion were well tolerated by all subjects. Cardiac output and heart rate significantly increased in all groups after sauna and cold-water immersion (p heart failure patients. In coronary artery disease patients and controls a prolonged increase in low frequency/high frequency ratio was observed after the first sauna exposure. Acute exposure to Finnish sauna and cold-water immersion causes haemodynamic alterations in chronic heart failure patients similarly to control subjects and in particular did not provoke an excessive increase in adrenergic activity or complex arrhythmias. © The European Society of Cardiology 2015.

A semi-implicit augmented IIM for Navier-Stokes equations with open, traction, or free boundary conditions.

Science.gov (United States)

Li, Zhilin; Xiao, Li; Cai, Qin; Zhao, Hongkai; Luo, Ray

2015-08-15

In this paper, a new Navier-Stokes solver based on a finite difference approximation is proposed to solve incompressible flows on irregular domains with open, traction, and free boundary conditions, which can be applied to simulations of fluid structure interaction, implicit solvent model for biomolecular applications and other free boundary or interface problems. For some problems of this type, the projection method and the augmented immersed interface method (IIM) do not work well or does not work at all. The proposed new Navier-Stokes solver is based on the local pressure boundary method, and a semi-implicit augmented IIM. A fast Poisson solver can be used in our algorithm which gives us the potential for developing fast overall solvers in the future. The time discretization is based on a second order multi-step method. Numerical tests with exact solutions are presented to validate the accuracy of the method. Application to fluid structure interaction between an incompressible fluid and a compressible gas bubble is also presented.

A semi-implicit augmented IIM for Navier–Stokes equations with open, traction, or free boundary conditions

Science.gov (United States)

Li, Zhilin; Xiao, Li; Cai, Qin; Zhao, Hongkai; Luo, Ray

2016-01-01

In this paper, a new Navier–Stokes solver based on a finite difference approximation is proposed to solve incompressible flows on irregular domains with open, traction, and free boundary conditions, which can be applied to simulations of fluid structure interaction, implicit solvent model for biomolecular applications and other free boundary or interface problems. For some problems of this type, the projection method and the augmented immersed interface method (IIM) do not work well or does not work at all. The proposed new Navier–Stokes solver is based on the local pressure boundary method, and a semi-implicit augmented IIM. A fast Poisson solver can be used in our algorithm which gives us the potential for developing fast overall solvers in the future. The time discretization is based on a second order multi-step method. Numerical tests with exact solutions are presented to validate the accuracy of the method. Application to fluid structure interaction between an incompressible fluid and a compressible gas bubble is also presented. PMID:27087702

Exploring the design space of immersive urban analytics

Directory of Open Access Journals (Sweden)

Zhutian Chen

2017-06-01

Full Text Available Recent years have witnessed the rapid development and wide adoption of immersive head-mounted devices, such as HTC VIVE, Oculus Rift, and Microsoft HoloLens. These immersive devices have the potential to significantly extend the methodology of urban visual analytics by providing critical 3D context information and creating a sense of presence. In this paper, we propose a theoretical model to characterize the visualizations in immersive urban analytics. Furthermore, based on our comprehensive and concise model, we contribute a typology of combination methods of 2D and 3D visualizations that distinguishes between linked views, embedded views, and mixed views. We also propose a supporting guideline to assist users in selecting a proper view under certain circumstances by considering visual geometry and spatial distribution of the 2D and 3D visualizations. Finally, based on existing work, possible future research opportunities are explored and discussed.

Masculinization of Nile tilapia (Oreochromis niloticus) by immersion in androgens

Science.gov (United States)

Gale, W.L.; Fitzpatrick, M.S.; Lucero, M.; Contreras-Sanchez, W.M.; Schreck, C. B.

1999-01-01

The use of all-male populations increases the efficiency and feasibility of tilapia aquaculture. The objective of this study was to determine the efficacy of a short-term immersion procedure for masculinizing Nile tilapia (Oreochromis niloticus). Two synthetic androgens were evaluated: 17α-methyldihydrotestosterone (MDHT) and 17α-methyltestosterone (MT). Exposure (3 h) on 10 and again on 13 days post-fertilization to MDHT at 500 μg/1 successfully masculinized fry in all experiments, resulting in 100, 94 and 83 ± 2% males in Experiments 1, 2 and 3, respectively. Immersions in MDHT or MT at 100 μg/1 resulted in significantly skewed sex ratios in Experiments 1 and 3 (MT resulted in 73 and 83 ± 3% males; and MDHT resulted in 72 and 91 ± 1% males) but not in Experiment 2. Immersion in MT at 500 μg/1 only caused masculinization in Experiment 3. Although further research and refinement is needed, immersion of Nile tilapia in MDHT may provide a practical alternative to the use of steroid-treated feed. Furthermore, when compared with current techniques for steroid-induced sex inversion of tilapia, short-term immersion reduces the period of time that workers are exposed to anabolic steroids.

Lipid-induced thermogenesis is up-regulated by the first cold-water immersions in juvenile penguins.

Science.gov (United States)

Teulier, Loïc; Rey, Benjamin; Tornos, Jérémy; Le Coadic, Marion; Monternier, Pierre-Axel; Bourguignon, Aurore; Dolmazon, Virginie; Romestaing, Caroline; Rouanet, Jean-Louis; Duchamp, Claude; Roussel, Damien

2016-07-01

The passage from shore to marine life is a critical step in the development of juvenile penguins and is characterized by a fuel selection towards lipid oxidation concomitant to an enhancement of lipid-induced thermogenesis. However, mechanisms of such thermogenic improvement at fledging remain undefined. We used two different groups of pre-fledging king penguins (Aptenodytes patagonicus) to investigate the specific contribution of cold exposure during water immersion to lipid metabolism. Terrestrial penguins that had never been immersed in cold water were compared with experimentally cold-water immersed juveniles. Experimentally immersed penguins underwent ten successive immersions at approximately 9-10 °C for 5 h over 3 weeks. We evaluated adaptive thermogenesis by measuring body temperature, metabolic rate and shivering activity in fully immersed penguins exposed to water temperatures ranging from 12 to 29 °C. Both never-immersed and experimentally immersed penguins were able to maintain their homeothermy in cold water, exhibiting similar thermogenic activity. In vivo, perfusion of lipid emulsion at thermoneutrality induced a twofold larger calorigenic response in experimentally immersed than in never-immersed birds. In vitro, the respiratory rates and the oxidative phosphorylation efficiency of isolated muscle mitochondria were not improved with cold-water immersions. The present study shows that acclimation to cold water only partially reproduced the fuel selection towards lipid oxidation that characterizes penguin acclimatization to marine life.

Project Oriented Immersion Learning: Method and Results

DEFF Research Database (Denmark)

Icaza, José I.; Heredia, Yolanda; Borch, Ole M.

2005-01-01

A pedagogical approach called “project oriented immersion learning” is presented and tested on a graduate online course. The approach combines the Project Oriented Learning method with immersion learning in a virtual enterprise. Students assumed the role of authors hired by a fictitious publishing...... house that develops digital products including e-books, tutorials, web sites and so on. The students defined the problem that their product was to solve; choose the type of product and the content; and built the product following a strict project methodology. A wiki server was used as a platform to hold...

Multi-arm multilateral haptics-based immersive tele-robotic system (HITS) for improvised explosive device disposal

Science.gov (United States)

Erickson, David; Lacheray, Hervé; Lai, Gilbert; Haddadi, Amir

2014-06-01

This paper presents the latest advancements of the Haptics-based Immersive Tele-robotic System (HITS) project, a next generation Improvised Explosive Device (IED) disposal (IEDD) robotic interface containing an immersive telepresence environment for a remotely-controlled three-articulated-robotic-arm system. While the haptic feedback enhances the operator's perception of the remote environment, a third teleoperated dexterous arm, equipped with multiple vision sensors and cameras, provides stereo vision with proper visual cues, and a 3D photo-realistic model of the potential IED. This decentralized system combines various capabilities including stable and scaled motion, singularity avoidance, cross-coupled hybrid control, active collision detection and avoidance, compliance control and constrained motion to provide a safe and intuitive control environment for the operators. Experimental results and validation of the current system are presented through various essential IEDD tasks. This project demonstrates that a two-armed anthropomorphic Explosive Ordnance Disposal (EOD) robot interface can achieve complex neutralization techniques against realistic IEDs without the operator approaching at any time.

Immersive viewing engine

Science.gov (United States)

Schonlau, William J.

2006-05-01

An immersive viewing engine providing basic telepresence functionality for a variety of application types is presented. Augmented reality, teleoperation and virtual reality applications all benefit from the use of head mounted display devices that present imagery appropriate to the user's head orientation at full frame rates. Our primary application is the viewing of remote environments, as with a camera equipped teleoperated vehicle. The conventional approach where imagery from a narrow field camera onboard the vehicle is presented to the user on a small rectangular screen is contrasted with an immersive viewing system where a cylindrical or spherical format image is received from a panoramic camera on the vehicle, resampled in response to sensed user head orientation and presented via wide field eyewear display, approaching 180 degrees of horizontal field. Of primary interest is the user's enhanced ability to perceive and understand image content, even when image resolution parameters are poor, due to the innate visual integration and 3-D model generation capabilities of the human visual system. A mathematical model for tracking user head position and resampling the panoramic image to attain distortion free viewing of the region appropriate to the user's current head pose is presented and consideration is given to providing the user with stereo viewing generated from depth map information derived using stereo from motion algorithms.

Heat Acclimation and Water-Immersion Deconditioning: Responses to Exercise

Science.gov (United States)

Shvartz, E.; Bhattacharya, A.; Sperinde, S. J.; Brock, P. J.; Sciaraffa, D.; Haines, R. F.; Greenleaf, J. E.

1977-01-01

Simulated subgravity conditions, such as bed rest and water immersion, cause a decrease in a acceleration tolerance (3, 4), tilt tolerance (3, 9, 10), work capacity (5, 7), and plasma volume (1, 8-10). Moderate exercise training performed during bed rest (4) and prior to water immersion (5) provides some protection against the adverse effects of deconditioning, but the relationship between exercise and changes due to deconditioning remains unclear. Heat acclimation increases plasma and interstitial volumes, total body water, stroke volume (11), and tilt tolerance (6) and may, therefore, be a more efficient method of ameliorating deconditioning than physical training alone. The present study was undertaken to determine the effects of heat acclimation and moderate physical training, performed in cool conditions, on water-immersion deconditioning.

Reduced cerebral perfusion on sudden immersion in ice water: a possible cause of drowning

DEFF Research Database (Denmark)

Mantoni, Teit; Belhage, Bo; Pedersen, Lars M

2007-01-01

INTRODUCTION: Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored the imme......INTRODUCTION: Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored...... cerebral artery (MCA) was measured together with ventilatory parameters and heart rate before, during, and after immersion. RESULTS: Within seconds after immersion in ice water, heart rate increased from 74 +/- 16 to 107 +/- 18 bpm (mean +/- SD; p elevation...

Growth hormone and prolactin responses during partial and whole body warm-water immersions.

Science.gov (United States)

Koska, J; Rovensky, J; Zimanova, T; Vigas, M

2003-05-01

To elucidate the role of core and skin thermoreceptors in the release of growth hormone (GH) and prolactin (PRL), a sequence of two experiments using whole-body (head-out) and partial (one forearm) hot water immersions was performed. Experiment 1: Nine healthy men were exposed to head-out and partial water immersions (25 min, 38-39 degrees C). Head-out immersion increased the core temperature (38.0 +/- 0.1 vs. 36.7 +/- 0.1 degrees C, P immersion the core temperature was slightly elevated (36.8 +/- 0.1 vs. 36.6 +/- 0.1, P immersed one forearm once in 39 degrees C and once in 38 degrees C water. The measurements were performed in 5-min intervals. The GH concentration increased gradually from the beginning of the immersions (min 10; 39 degrees C: 1.9 +/- 1.0 vs. 0.6 +/- 0.3 ng mL(-1), P Immersion in 38 degrees C water did not induce core temperature changes. Peripheral thermoreceptors are involved in GH release when the body is exposed to elevated environmental temperature while a substantial elevation of core temperature is a precondition of PRL release.

A Culturally Competent Immersion Protocol: Petit Goâve, Haiti

Science.gov (United States)

Streets, Barbara Faye; Wolford, Karen; Nicolas, Guerda

2015-01-01

In the human services professions, cultural immersion experiences help satisfy multicultural training standards established by national accreditation bodies. Immersion in a culturally sensitive manner is necessary as we prepare professionals to work with and serve citizens of the globe. The authors describe an international cultural immersion…

Cranial implant design using augmented reality immersive system.

Science.gov (United States)

Ai, Zhuming; Evenhouse, Ray; Leigh, Jason; Charbel, Fady; Rasmussen, Mary

2007-01-01

Software tools that utilize haptics for sculpting precise fitting cranial implants are utilized in an augmented reality immersive system to create a virtual working environment for the modelers. The virtual environment is designed to mimic the traditional working environment as closely as possible, providing more functionality for the users. The implant design process uses patient CT data of a defective area. This volumetric data is displayed in an implant modeling tele-immersive augmented reality system where the modeler can build a patient specific implant that precisely fits the defect. To mimic the traditional sculpting workspace, the implant modeling augmented reality system includes stereo vision, viewer centered perspective, sense of touch, and collaboration. To achieve optimized performance, this system includes a dual-processor PC, fast volume rendering with three-dimensional texture mapping, the fast haptic rendering algorithm, and a multi-threading architecture. The system replaces the expensive and time consuming traditional sculpting steps such as physical sculpting, mold making, and defect stereolithography. This augmented reality system is part of a comprehensive tele-immersive system that includes a conference-room-sized system for tele-immersive small group consultation and an inexpensive, easily deployable networked desktop virtual reality system for surgical consultation, evaluation and collaboration. This system has been used to design patient-specific cranial implants with precise fit.

Degradation of Epoxy-Steel Single Lap Joints Immersed in Water

DEFF Research Database (Denmark)

Goglio, L; Rezaei, Mohsen

2015-01-01

Exposure to environmental factors, especially moisture, is recognized as the major cause of degradation of adhesive joints. In this work, complementing a previous study on exposure to moisture, single lap joints were subjected to immersion in water, up to five weeks, at room temperature and 50 °C....... The material of the adherends was mild steel, and the adhesive was a bi-component epoxy. The specimens were fabricated using the open-face technique. Mechanical testing at the end of the relevant period of immersion showed an initial loss of ultimate load, after one week at 50 °C or two at room temperature......; then, the strength remained practically constant over the remaining time. The loss was more accentuated after immersion at 50 °C, about 70%, than at room temperature, about 30%. Also a reduction in stiffness of the joints was measured, again dramatic (about 70%) after immersion at 50 °C, moderate...

Lovelock action with nonsmooth boundaries

Science.gov (United States)

Cano, Pablo A.

2018-05-01

We examine the variational problem in Lovelock gravity when the boundary contains timelike and spacelike segments nonsmoothly glued. We show that two kinds of contributions have to be added to the action. The first one is associated with the presence of a boundary in every segment and it depends on intrinsic and extrinsic curvatures. We can think of this contribution as adding a total derivative to the usual surface term of Lovelock gravity. The second one appears in every joint between two segments and it involves the integral along the joint of the Jacobson-Myers entropy density weighted by the Lorentz boost parameter, which relates the orthonormal frames in each segment. We argue that this term can be straightforwardly extended to the case of joints involving null boundaries. As an application, we compute the contribution of these terms to the complexity of global anti-de Sitter space in Lovelock gravity by using the "complexity =action " proposal and we identify possible universal terms for arbitrary values of the Lovelock couplings. We find that they depend on the charge a* controlling the holographic entanglement entropy and on a new constant that we characterize.

Bound states in waveguides with complex Robin boundary conditions

Czech Academy of Sciences Publication Activity Database

Novák, Radek

2016-01-01

Roč. 96, 3-4 (2016), s. 251-281 ISSN 0921-7134 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : non-self-adjointness * waveguide * Robin boundary conditions * spectral analysis * essential spectrum * weak coupling * Birman-Schwinger principle * reality of the spectrum Subject RIV: BE - Theoretical Physics Impact factor: 0.933, year: 2016

Story immersion in a health videogame for childhood obesity prevention

Science.gov (United States)

Stories can serve as powerful tools for health interventions. Story immersion refers to the experience of being absorbed in a story. This is among the first studies to analyze story immersion’s role in health video games among children by addressing two main questions: Will children be more immersed...

Authoring Immersive Mixed Reality Experiences

Science.gov (United States)

Misker, Jan M. V.; van der Ster, Jelle

Creating a mixed reality experience is a complicated endeavour. From our practice as a media lab in the artistic domain we found that engineering is “only” a first step in creating a mixed reality experience. Designing the appearance and directing the user experience are equally important for creating an engaging, immersive experience. We found that mixed reality artworks provide a very good test bed for studying these topics. This chapter details three steps required for authoring mixed reality experiences: engineering, designing and directing. We will describe a platform (VGE) for creating mixed reality environments that incorporates these steps. A case study (EI4) is presented in which this platform was used to not only engineer the system, but in which an artist was given the freedom to explore the artistic merits of mixed reality as an artistic medium, which involved areas such as the look and feel, multimodal experience and interaction, immersion as a subjective emotion and game play scenarios.

Static respiratory muscle work during immersion with positive and negative respiratory loading.

Science.gov (United States)

Taylor, N A; Morrison, J B

1999-10-01

Upright immersion imposes a pressure imbalance across the thorax. This study examined the effects of air-delivery pressure on inspiratory muscle work during upright immersion. Eight subjects performed respiratory pressure-volume relaxation maneuvers while seated in air (control) and during immersion. Hydrostatic, respiratory elastic (lung and chest wall), and resultant static respiratory muscle work components were computed. During immersion, the effects of four air-delivery pressures were evaluated: mouth pressure (uncompensated); the pressure at the lung centroid (PL,c); and at PL,c +/-0.98 kPa. When breathing at pressures less than the PL,c, subjects generally defended an expiratory reserve volume (ERV) greater than the immersed relaxation volume, minus residual volume, resulting in additional inspiratory muscle work. The resultant static inspiratory muscle work, computed over a 1-liter tidal volume above the ERV, increased from 0.23 J. l(-1), when subjects were breathing at PL,c, to 0.83 J. l(-1) at PL,c -0.98 kPa (P work was minimal. When breathing at PL,c +0.98 kPa, subjects adopted an ERV less than the immersed relaxation volume, minus residual volume, resulting in 0.36 J. l(-1) of expiratory muscle work. Thus static inspiratory muscle work varied with respiratory loading, whereas PL,c air supply minimized this work during upright immersion, restoring lung-tissue, chest-wall, and static muscle work to levels obtained in the control state.

Immersive Environment Development for Training: Opportunities for Cooperation, Coordination, and Cost Savings

International Nuclear Information System (INIS)

Tackentien, J.; Hoffheins, B.; Brown, R.

2015-01-01

Immersive environments are increasingly demonstrating their utility for a number of nuclear safeguards, nuclear safety, and nuclear and physical security applications. Although training is an obvious use, the immersive (or sometimes called virtual) environment allows the user to ''visit'' nuclear facilities and sites that might have access restrictions because of security, high radiation or other hazards; are difficult and expensive to visit. An immersive environment can also be reconfigured to study various scenarios, processes, and other what-if situations, which can aid planning and design of new facilities or evaluate safeguards, safety and/or security measures before they are implemented. As the International Atomic Energy Agency, other international organizations, State Authorities, industry, and academia continue development and use of immersive environments and other electronic training technologies, more and more applications can be envisioned. Immersive environments are not a direct or always a desirable replacement for hands-on learning; however, the demand for electronic training media, particularly immersive environments, will grow. The resulting increase of system features and libraries presents opportunities to shorten development time frames, reduce costs and increase availability of immersive environments for a wider audience looking to balance the need for quality training with limited resources. Substantial time and cost savings can be realized by the sharing of raw assets among developers and organizations. This paper will explore potential guidelines, criteria, and mechanisms for such cooperation, including a prototype asset repository website. (author)

Microclump effects in magnetically-immersed electron diodes

International Nuclear Information System (INIS)

Olson, C.L.

1998-01-01

Magnetically-immersed electron diodes are being developed to produce needle-like, high-current, electron beams for radiography applications. An immersed diode consists of a needle cathode and a planar anode/bremmstrahlung converter which are both immersed in a strong solenoidal magnetic field (12--50 T); nominal parameters are 10 MV, 40 kA, 0.5 mm radius cathode, and 5--35 cm anode-cathode gaps. A physical picture of normal and abnormal diode behavior is emerging. Normal diode behavior occurs for times 0 ≤ t ≤ τ, where the transition time τ is typically 30 ns; during this time, bipolar space-charge limited flow occurs, which scales well to desired radiography parameters of high dose and small spot size. Abnormal diode behavior occurs for t ≥ τ, which results in substantial increases in spot size and current (impedance reduction). This abnormal behavior appears to be caused by an increase in ion charge in the gap, which may result from poor vacuum, impurity ions undergoing ion-ion stripping collisions during transit, or microclumps undergoing stripping collisions during transit. The potential effects of microclumps on diode behavior are reported here

Virtually numbed: immersive video gaming alters real-life experience.

Science.gov (United States)

Weger, Ulrich W; Loughnan, Stephen

2014-04-01

As actors in a highly mechanized environment, we are citizens of a world populated not only by fellow humans, but also by virtual characters (avatars). Does immersive video gaming, during which the player takes on the mantle of an avatar, prompt people to adopt the coldness and rigidity associated with robotic behavior and desensitize them to real-life experience? In one study, we correlated participants' reported video-gaming behavior with their emotional rigidity (as indicated by the number of paperclips that they removed from ice-cold water). In a second experiment, we manipulated immersive and nonimmersive gaming behavior and then likewise measured the extent of the participants' emotional rigidity. Both studies yielded reliable impacts, and thus suggest that immersion into a robotic viewpoint desensitizes people to real-life experiences in oneself and others.

Immersion hand radiography in the evaluation of musculoskeletal disorders

International Nuclear Information System (INIS)

Ngo, C.; Yaghmai, I.; Zach, R.

1987-01-01

A prospective study is undertaken to evaluate a new soft-tissue immersion technique. The hand is immersed in a plastic tray containing a mixture solution of alcohol and water. Exposures are made employing low-kilovolt technique. Conventional x-rays of the hands are obtained to serve as baseline studies and for the purpose of comparison. Soft-tissue immersion technique has proven sensitive and efficient in outlining the skin, subcutaneous fat layers, and fat layers between muscle planes. More importantly, the tendons and the joint capsules, which are hardly seen on standard hand radiographs, are easily highlighted with this technique. In conclusion, this technique appears to be superior to conventional plain radiographs in the evaluation and early detection of soft-tissue changes related to musculoskeletal disorders, especially in cases of arthritides

Body cooling in human males by cold-water immersion after vigorous exercise.

Science.gov (United States)

McDonald, A; Goode, R C; Livingstone, S D; Duffin, J

1984-03-01

Five male subjects were immersed to neck level in a whole-body water calorimeter (water temperature 19 degrees C) on two occasions. One immersion was preceded by 30 min of exercise on a treadmill at 80% of the subjects' maximum heart rate, while the other was preceded by no exercise (control). Ventilation, oxygen consumption, hand-grip strength, and heat loss (measured by calorimetry) results showed no significant differences between resting and exercise trials. Minute ventilation and oxygen consumption increased during the immersion but the magnitude of the increase varied among subjects. There was a significant decrease is isometric hand-grip strength after 30 min of immersion. Rectal temperatures fell faster (0.031 degree C +/- 0.004 degree C/min) for exercised subjects than for controls (0.019 degree C +/- 0.005 degree C/min) between 10 and 45 min of immersion (P less than 0.01). It appears that vigorous preimmersion exercise may shorten survival time in cold water due to an increase in cooling rate.

Story Immersion of Videogames for Youth Health Promotion: A Review of Literature.

Science.gov (United States)

Lu, Amy Shirong; Baranowski, Tom; Thompson, Debbe; Buday, Richard

2012-06-01

This article reviews research in the fields of psychology, literature, communication, human-computer interaction, public health, and consumer behavior on narrative and its potential relationships with videogames and story immersion. It also reviews a narrative's role in complementing behavioral change theories and the potential of story immersion for health promotion through videogames. Videogames have potential for health promotion and may be especially promising when attempting to reach youth. An understudied characteristic of videogames is that many contain a narrative, or story. Story immersion (transportation) is a mechanism through which a narrative influences players' cognition, affect, and, potentially, health behavior. Immersion promotes the suspension of disbelief and the reduction of counterarguments, enables the story experience as a personal experience, and creates the player's deep affection for narrative protagonists. Story immersion complements behavioral change theories, including the Theory of Planned Behavior, Social Cognitive Theory, and Self-Determination Theory. Systematic investigations are needed to realize the powerful potential of interactive narratives within theory-driven research.

Metal deposition on porous silicon by immersion plating to improve photoluminescence properties

Energy Technology Data Exchange (ETDEWEB)

Haddadi, Ikbel, E-mail: haded.ikbel@yahoo.fr; Amor, Sana Ben; Bousbih, Rabaa; Whibi, Seif El; Bardaoui, Afrah; Dimassi, Wissem; Ezzaouia, Hatem

2016-05-15

Metal deposition into porous silicon (PS) by immersion plating in aqueous solution during different times was investigated. The influence of immersion time on optical properties of porous silicon treated with Lithium (Li) was studied by photoluminescence (PL). From experimental results, we suggest that the treatment, for critical immersion time provides an easy way to achieve an improvement in the PL intensity. To identify surface modification, Fourier transmission infrared spectroscopy and atomic force microscopy were performed. The reflectivity spectra showed that the variation of light absorption can be probably due to the newly formed layer during the chemical deposition of Li. - Highlights: • We have varied the immersion time of PS in LiBr solution. • PL intensity shows significant variation as function of immersion time. • We observe reduction of Si–O–Li bands with increasing treatment time. • Concurrent with the loss of Li we observe a decrease of the PL.

Metal deposition on porous silicon by immersion plating to improve photoluminescence properties

International Nuclear Information System (INIS)

Haddadi, Ikbel; Amor, Sana Ben; Bousbih, Rabaa; Whibi, Seif El; Bardaoui, Afrah; Dimassi, Wissem; Ezzaouia, Hatem

2016-01-01

Metal deposition into porous silicon (PS) by immersion plating in aqueous solution during different times was investigated. The influence of immersion time on optical properties of porous silicon treated with Lithium (Li) was studied by photoluminescence (PL). From experimental results, we suggest that the treatment, for critical immersion time provides an easy way to achieve an improvement in the PL intensity. To identify surface modification, Fourier transmission infrared spectroscopy and atomic force microscopy were performed. The reflectivity spectra showed that the variation of light absorption can be probably due to the newly formed layer during the chemical deposition of Li. - Highlights: • We have varied the immersion time of PS in LiBr solution. • PL intensity shows significant variation as function of immersion time. • We observe reduction of Si–O–Li bands with increasing treatment time. • Concurrent with the loss of Li we observe a decrease of the PL.

Second-mode control in hypersonic boundary layers over assigned complex wall impedance

Science.gov (United States)

Sousa, Victor; Patel, Danish; Chapelier, Jean-Baptiste; Scalo, Carlo

2017-11-01

The durability and aerodynamic performance of hypersonic vehicles greatly relies on the ability to delay transition to turbulence. Passive aerodynamic flow control devices such as porous acoustic absorbers are a very attractive means to damp ultrasonic second-mode waves, which govern transition in hypersonic boundary layers under idealized flow conditions (smooth walls, slender geometries, small angles of attack). The talk will discuss numerical simulations modeling such absorbers via the time-domain impedance boundary condition (TD-IBC) approach by Scalo et al. in a hypersonic boundary layer flow over a 7-degree wedge at freestream Mach numbers M∞ = 7.3 and Reynolds numbers Rem = 1.46 .106 . A three-parameter impedance model tuned to the second-mode waves is tested first with varying resistance, R, and damping ratio, ζ, revealing complete mode attenuation for R workers at DLR-Göttingen.

33 CFR 150.518 - What are the inspection requirements for work vests and immersion suits?

Science.gov (United States)

2010-07-01

... requirements for work vests and immersion suits? 150.518 Section 150.518 Navigation and Navigable Waters COAST... vests and immersion suits? (a) All work vests and immersion suits must be inspected by the owner or... a work vest or immersion suit is inspected and is in serviceable condition, then it may remain in...

Seawater immersion aggravates burn-associated lung injury and inflammatory and oxidative-stress responses.

Science.gov (United States)

Ma, Jun; Wang, Ying; Wu, Qi; Chen, Xiaowei; Wang, Jiahan; Yang, Lei

2017-08-01

With the increasing frequency of marine development activities and local wars at sea, the incidence of scald burns in marine accidents or wars has been increasing yearly. Various studies have indicated that immersion in seawater has a systemic impact on some organs of animals or humans with burn. Thus, for burn/scald injuries after immersion in seawater, it is desirable to study the effects and mechanisms of action on important organs. In the present study, we aimed to investigate the effect of immersion in seawater on lung injury, inflammatory and oxidative-stress responses in scalded rats. The structural damage to lungs was detected by hematoxylin and eosin staining and the results showed that seawater immersion aggravated structural lung injury in scalded rats. The expression of HMGB1 in lung tissues was detected by immunohistochemical analysis and the results showed that seawater immersion increased HMGB1 expression in lung tissues of scalded rats. Apoptosis in lung tissues was detected by terminal deoxynucleotidyl transfer-mediated dUTP nick end-labeling (TUNEL) staining and the results showed that seawater immersion increased apoptosis rate in lung tissues of scalded rats. In addition, the expression levels of TNF-α, IL-6, IL-8, SOD, and MDA in serum were analyzed by enzyme-linked immunosorbent assays (ELISAs) and the results showed that seawater immersion induced secretion of proinflammatory factors (TNF-α, IL-6, and IL-8), increased MDA protein level, and suppressed SOD activity in the serum of scalded rats. Furthermore, measurement of plasma volume and pH showed that seawater immersion decreased plasma volume and pH value. Overall, the results indicated that all effects induced by immersion in seawater in scalded rats are more pronounced than those induced by freshwater. In conclusion, seawater immersion may aggravate lung injury and enhance inflammatory and oxidative-stress responses after burn. Copyright © 2017 Elsevier Ltd and ISBI. All rights

Photonic nanojet super-resolution in immersed ordered assembly of dielectric microspheres

International Nuclear Information System (INIS)

Geints, Y.E.; Zemlyanov, A.A.

2017-01-01

Highlights: • Ordered microassemblies of dielectric microspheres immersed in a transparent matrix exposed to a light wave produce an array of the “photonic nanojets” coupled through the field interference. • “Photonic nanojet” parameters depend on the inter-sphere gap and immersion depth. • Sphere microassembly can produce the jets with the sub-diffraction spatial resolution if the particles are loosely packed and semi-immersed. - Abstract: Specific spatially-localized optical field structure, which is often referred to as a photonic nanojet (PNJ), is formed in the near-field scattering area of non-absorbing dielectric micron-sized particle exposed to an optical radiation. By virtue of the finite-difference time-domain technique we numerically simulate the two-dimensional array of PNJs created by an ordered single-layer microassembly of glass microspheres immersed in a transparent polymer matrix. The behavior of the main PNJ parameters (length, diameter, and intensity) is analyzed subject to the immersion depth of the microparticles and cooperative interference effects of the neighboring microspheres. We show that depending on microassembly configuration, the PNJ quality can be significantly improved; in particular, the PNJ spatial resolution better than λ/5 can be achieved.

Submicron hollow spot generation by solid immersion lens and structured illumination

International Nuclear Information System (INIS)

Kim, M-S; Scharf, T; Herzig, H P; Assafrao, A C; Wachters, A J H; Pereira, S F; Urbach, H P; Brun, M; Olivier, S; Nicoletti, S

2012-01-01

We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (μ-SIL) made of SiO 2 . Such structured focal spots are characterized by a doughnut-shaped intensity distribution, whose central dark region is of great interest for optical trapping of nano-size particles, super-resolution microscopy and lithography. In this work, we have used a high-resolution interference microscopy technique to measure the structured immersed focal spots, whose dimensions were found to be significantly reduced due to the immersion effect of the μ-SIL. In particular, a reduction of 37% of the dark central region was verified. The measurements were compared with a rigorous finite element method model for the μ-SIL, revealing excellent agreement between them. (paper)

Introduction of English Immersion in China: A Transplant with Modifications

Science.gov (United States)

Qiang, Haiyan; Siegel, Linda S.

2012-01-01

This article presents an overview of replicating the French immersion model used in Canada to English immersion programs in China. It provides the Chinese context of this program highlighting the importance of English education and the defect of traditional English teaching and learning. The paper explains the borrowable features of the French…

Use of French, Attitudes and Motivations of French Immersion Students.

Science.gov (United States)

Van der Keilen, Marguerite

1995-01-01

Compares the degree to which pupils in the French immersion and regular English school programs speak French and initiate contact with French people. Attitudes and motivations were significantly more positive, and social tolerance and self-rated competency in French were much higher in the immersion than in English program subjects. (29…

A moving control volume method for smooth computation of hydrodynamic forces and torques on immersed bodies

Science.gov (United States)

Nangia, Nishant; Patankar, Neelesh A.; Bhalla, Amneet P. S.

2017-11-01

Fictitious domain methods for simulating fluid-structure interaction (FSI) have been gaining popularity in the past few decades because of their robustness in handling arbitrarily moving bodies. Often the transient net hydrodynamic forces and torques on the body are desired quantities for these types of simulations. In past studies using immersed boundary (IB) methods, force measurements are contaminated with spurious oscillations due to evaluation of possibly discontinuous spatial velocity of pressure gradients within or on the surface of the body. Based on an application of the Reynolds transport theorem, we present a moving control volume (CV) approach to computing the net forces and torques on a moving body immersed in a fluid. The approach is shown to be accurate for a wide array of FSI problems, including flow past stationary and moving objects, Stokes flow, and high Reynolds number free-swimming. The approach only requires far-field (smooth) velocity and pressure information, thereby suppressing spurious force oscillations and eliminating the need for any filtering. The proposed moving CV method is not limited to a specific IB method and is straightforward to implement within an existing parallel FSI simulation software. This work is supported by NSF (Award Numbers SI2-SSI-1450374, SI2-SSI-1450327, and DGE-1324585), the US Department of Energy, Office of Science, ASCR (Award Number DE-AC02-05CH11231), and NIH (Award Number HL117163).

Duration and setting of rural immersion during the medical degree relates to rural work outcomes.

Science.gov (United States)

O'Sullivan, Belinda; McGrail, Matthew; Russell, Deborah; Walker, Judi; Chambers, Helen; Major, Laura; Langham, Robyn

2018-04-19

Providing year-long rural immersion as part of the medical degree is commonly used to increase the number of doctors with an interest in rural practice. However, the optimal duration and setting of immersion has not been fully established. This paper explores associations between various durations and settings of rural immersion during the medical degree and whether doctors work in rural areas after graduation. Eligible participants were medical graduates of Monash University between 2008 and 2016 in postgraduate years 1-9, whose characteristics, rural immersion information and work location had been prospectively collected. Separate multiple logistic regression and multinomial logit regression models tested associations between the duration and setting of any rural immersion they did during the medical degree and (i) working in a rural area and (ii) working in large or smaller rural towns, in 2017. The adjusted odds of working in a rural area were significantly increased if students were immersed for one full year (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.15-2.79), for between 1 and 2 years (OR, 2.26; 95% CI, 1.54-3.32) and for 2 or more years (OR, 4.43; 95% CI, 3.03-6.47) relative to no rural immersion. The strongest association was for immersion in a mix of both regional hospitals and rural general practice (OR, 3.26; 95% CI, 2.31-4.61), followed by immersion in regional hospitals only (OR, 1.94; 95% CI, 1.39-2.70) and rural general practice only (OR, 1.91; 95% CI, 1.06-3.45). More than 1 year's immersion in a mix of regional hospitals and rural general practices was associated with working in smaller regional or rural towns (immersion programmes. Longer rural immersion and immersion in both regional hospitals and rural general practices are likely to increase rural work and rural distribution of early career doctors. © 2018 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

A unique enhancer boundary complex on the mouse ribosomal RNA genes persists after loss of Rrn3 or UBF and the inactivation of RNA polymerase I transcription.

Science.gov (United States)

Herdman, Chelsea; Mars, Jean-Clement; Stefanovsky, Victor Y; Tremblay, Michel G; Sabourin-Felix, Marianne; Lindsay, Helen; Robinson, Mark D; Moss, Tom

2017-07-01

Transcription of the several hundred of mouse and human Ribosomal RNA (rRNA) genes accounts for the majority of RNA synthesis in the cell nucleus and is the determinant of cytoplasmic ribosome abundance, a key factor in regulating gene expression. The rRNA genes, referred to globally as the rDNA, are clustered as direct repeats at the Nucleolar Organiser Regions, NORs, of several chromosomes, and in many cells the active repeats are transcribed at near saturation levels. The rDNA is also a hotspot of recombination and chromosome breakage, and hence understanding its control has broad importance. Despite the need for a high level of rDNA transcription, typically only a fraction of the rDNA is transcriptionally active, and some NORs are permanently silenced by CpG methylation. Various chromatin-remodelling complexes have been implicated in counteracting silencing to maintain rDNA activity. However, the chromatin structure of the active rDNA fraction is still far from clear. Here we have combined a high-resolution ChIP-Seq protocol with conditional inactivation of key basal factors to better understand what determines active rDNA chromatin. The data resolve questions concerning the interdependence of the basal transcription factors, show that preinitiation complex formation is driven by the architectural factor UBF (UBTF) independently of transcription, and that RPI termination and release corresponds with the site of TTF1 binding. They further reveal the existence of an asymmetric Enhancer Boundary Complex formed by CTCF and Cohesin and flanked upstream by phased nucleosomes and downstream by an arrested RNA Polymerase I complex. We find that the Enhancer Boundary Complex is the only site of active histone modification in the 45kbp rDNA repeat. Strikingly, it not only delimits each functional rRNA gene, but also is stably maintained after gene inactivation and the re-establishment of surrounding repressive chromatin. Our data define a poised state of rDNA chromatin

A unique enhancer boundary complex on the mouse ribosomal RNA genes persists after loss of Rrn3 or UBF and the inactivation of RNA polymerase I transcription.

Directory of Open Access Journals (Sweden)

Chelsea Herdman

2017-07-01

Full Text Available Transcription of the several hundred of mouse and human Ribosomal RNA (rRNA genes accounts for the majority of RNA synthesis in the cell nucleus and is the determinant of cytoplasmic ribosome abundance, a key factor in regulating gene expression. The rRNA genes, referred to globally as the rDNA, are clustered as direct repeats at the Nucleolar Organiser Regions, NORs, of several chromosomes, and in many cells the active repeats are transcribed at near saturation levels. The rDNA is also a hotspot of recombination and chromosome breakage, and hence understanding its control has broad importance. Despite the need for a high level of rDNA transcription, typically only a fraction of the rDNA is transcriptionally active, and some NORs are permanently silenced by CpG methylation. Various chromatin-remodelling complexes have been implicated in counteracting silencing to maintain rDNA activity. However, the chromatin structure of the active rDNA fraction is still far from clear. Here we have combined a high-resolution ChIP-Seq protocol with conditional inactivation of key basal factors to better understand what determines active rDNA chromatin. The data resolve questions concerning the interdependence of the basal transcription factors, show that preinitiation complex formation is driven by the architectural factor UBF (UBTF independently of transcription, and that RPI termination and release corresponds with the site of TTF1 binding. They further reveal the existence of an asymmetric Enhancer Boundary Complex formed by CTCF and Cohesin and flanked upstream by phased nucleosomes and downstream by an arrested RNA Polymerase I complex. We find that the Enhancer Boundary Complex is the only site of active histone modification in the 45kbp rDNA repeat. Strikingly, it not only delimits each functional rRNA gene, but also is stably maintained after gene inactivation and the re-establishment of surrounding repressive chromatin. Our data define a poised state

Immersive virtual reality in destination marketing : evidence from lab and field experiments

OpenAIRE

Vekony, David; Korneliussen, Simen

2016-01-01

Although the concept of virtual reality (VR) has been studied and used for many years, recent technological development has led to the commercial availability of immersive VR, specifically head-mounted displays. Little research has been conducted on the potential for immersive VR to influence consumer behavior. The aim of this thesis is to give insight into how immersive VR can be utilized in destination marketing, through investigating its effect on consumer outcomes directly,...

Immersive Education, an Annotated Webliography

Science.gov (United States)

Pricer, Wayne F.

2011-01-01

In this second installment of a two-part feature on immersive education a webliography will provide resources discussing the use of various types of computer simulations including: (a) augmented reality, (b) virtual reality programs, (c) gaming resources for teaching with technology, (d) virtual reality lab resources, (e) virtual reality standards…

Correction factors for assessing immersion suits under harsh conditions.

Science.gov (United States)

Power, Jonathan; Tikuisis, Peter; Ré, António Simões; Barwood, Martin; Tipton, Michael

2016-03-01

Many immersion suit standards require testing of thermal protective properties in calm, circulating water while these suits are typically used in harsher environments where they often underperform. Yet it can be expensive and logistically challenging to test immersion suits in realistic conditions. The goal of this work was to develop a set of correction factors that would allow suits to be tested in calm water yet ensure they will offer sufficient protection in harsher conditions. Two immersion studies, one dry and the other with 500 mL of water within the suit, were conducted in wind and waves to measure the change in suit insulation. In both studies, wind and waves resulted in a significantly lower immersed insulation value compared to calm water. The minimum required thermal insulation for maintaining heat balance can be calculated for a given mean skin temperature, metabolic heat production, and water temperature. Combining the physiological limits of sustainable cold water immersion and actual suit insulation, correction factors can be deduced for harsh conditions compared to calm. The minimum in-situ suit insulation to maintain thermal balance is 1.553-0.0624·TW + 0.00018·TW(2) for a dry calm condition. Multiplicative correction factors to the above equation are 1.37, 1.25, and 1.72 for wind + waves, 500 mL suit wetness, and both combined, respectively. Calm water certification tests of suit insulation should meet or exceed the minimum in-situ requirements to maintain thermal balance, and correction factors should be applied for a more realistic determination of minimum insulation for harsh conditions. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

Science.gov (United States)

Curtis, Colin K; Marek, Antonin; Smirnov, Alex I

2017-01-01

This article reports a comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated) or negatively (carboxylated) charged nanodiamonds (ND). Immersion in −ND suspensions resulted in a decrease in the macroscopic friction coefficients to values in the range 0.05–0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts. Quartz crystal microbalance (QCM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements were employed to assess nanoparticle uptake, surface polishing, and resistance to solid–liquid interfacial shear motion. The QCM studies revealed abrupt changes to the surfaces of both alumina and stainless steel upon injection of –ND into the surrounding water environment that are consistent with strong attachment of NDs and/or chemical changes to the surfaces. AFM images of the surfaces indicated slight increases in the surface roughness upon an exposure to both +ND and −ND suspensions. A suggested mechanism for these observations is that carboxylated −NDs from aqueous suspensions are forming robust lubricious deposits on stainless and alumina surfaces that enable gliding of the surfaces through the −ND suspensions with relatively low resistance to shear. In contrast, +ND suspensions are failing to improve tribological performance for either of the surfaces and may have abraded existing protective boundary layers in the case of stainless steel contacts. This study therefore reveals atomic scale details associated with systems that exhibit starkly different macroscale tribological properties, enabling future efforts to predict and design complex lubricant interfaces. PMID:29046852

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

Directory of Open Access Journals (Sweden)

Colin K. Curtis

2017-09-01

Full Text Available This article reports a comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated or negatively (carboxylated charged nanodiamonds (ND. Immersion in −ND suspensions resulted in a decrease in the macroscopic friction coefficients to values in the range 0.05–0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts. Quartz crystal microbalance (QCM, atomic force microscopy (AFM and scanning electron microscopy (SEM measurements were employed to assess nanoparticle uptake, surface polishing, and resistance to solid–liquid interfacial shear motion. The QCM studies revealed abrupt changes to the surfaces of both alumina and stainless steel upon injection of –ND into the surrounding water environment that are consistent with strong attachment of NDs and/or chemical changes to the surfaces. AFM images of the surfaces indicated slight increases in the surface roughness upon an exposure to both +ND and −ND suspensions. A suggested mechanism for these observations is that carboxylated −NDs from aqueous suspensions are forming robust lubricious deposits on stainless and alumina surfaces that enable gliding of the surfaces through the −ND suspensions with relatively low resistance to shear. In contrast, +ND suspensions are failing to improve tribological performance for either of the surfaces and may have abraded existing protective boundary layers in the case of stainless steel contacts. This study therefore reveals atomic scale details associated with systems that exhibit starkly different macroscale tribological properties, enabling future efforts to predict and design complex lubricant interfaces.

The frequency of occurrence and severity of side-effects of immersion virtual reality.

Science.gov (United States)

Regan, E C; Price, K R

1994-06-01

Virtual reality (VR) has become increasingly well-known over the last few years. However, little is known about the side-effects of prolonged immersion in VR. This study set out to investigate the frequency of occurrence and severity of side-effects of using an immersion VR system. Out of 146 subjects, 61% reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. These ranged from symptoms such as dizziness, stomach awareness, headaches, eyestrain and lightheadedness to severe nausea. These symptoms caused 5% of the subjects to withdraw from the experiment before completing their 20-min immersion period. Further research needs to be conducted that attempts to identify those factors that play a causative role in the side-effects of the VR system, and that looks for methods of reducing these side-effects.

Swelling and gas release of grain-boundary pores in uranium dioxide

International Nuclear Information System (INIS)

Schrire, D.I.

1983-12-01

The swelling and gas release of overpressured grain boundary pores is sintered unirradiated uranium dioxide were investigated under isothermal conditions. The pores became overpressured when the ambient pressure was reduced, and the excess pressure driving force caused growth and interconnection of the pores, leading to eventual gas release. Swelling was measured continuously by a linear variable differential transformer, and open and closed porosity fractions were determined after the tests by immersion density and quantitative microscopy measurements. The sinter porosity consisted of pores situated on grain faces, grain edges, and grain corners. Isolated pores maintained their equilibrium shape while growing, without any measurable change in dihedral angle. Interconnection occurred predominantly along grain edges, without any evidence of pore sharpening or crack propagation at low driving forces. Extensive open porosity occurred at a threshold density of about 85% TD. There was an almost linear dependence of the initial swelling rate on the driving force, with an activation energy of 200+- 8 kJ/mole, in good agreement with published values of the activation energy for grain boundary diffusion

Immersive Environments and Virtual Reality: Systematic Review and Advances in Communication, Interaction and Simulation

Directory of Open Access Journals (Sweden)

Jose Luis Rubio-Tamayo

2017-09-01

Full Text Available Today, virtual reality and immersive environments are lines of research which can be applied to numerous scientific and educational domains. Immersive digital media needs new approaches regarding its interactive and immersive features, which means the design of new narratives and relationships with users. Additionally, ICT (information and communication theory evolves through more immersive and interactive scenarios, it being necessary to design and conceive new forms of representing information and improving users’ interaction with immersive environments. Virtual reality and technologies associated with the virtuality continuum, such as immersive and digital environments, are emerging media. As a medium, this approach may help to build and represent ideas and concepts, as well as developing new languages. This review analyses the cutting-edge expressive, interactive and representative potential of immersive digital technologies. It also considers future possibilities regarding the evolution of these immersive technologies, such as virtual reality, in coming years, in order to apply them to diverse scientific, artistic or informational and educational domains. We conclude that virtual reality is an ensemble of technological innovations, but also a concept, and propose models to link it with the latest in other domains such as UX (user experience, interaction design. This concept can help researchers and developers to design new experiences and conceive new expressive models that can be applied to a wide range of scientific lines of research and educational dynamics.

Neoproterozoic igneous complex emplaced along major tectonic boundary in the Kaoko Belt (NW Namibia): ion probe and LA-ICP-MS dating of magmatic and metamorphic zircons

Czech Academy of Sciences Publication Activity Database

Konopásek, J.; Košler, J.; Tajčmanová, L.; Ulrich, Stanislav; Kitt, S. L.

2008-01-01

Roč. 165, č. 1 (2008), s. 153-166 ISSN 0016-7649 Institutional research plan: CEZ:AV0Z30120515 Keywords : boundary igneous complex * Kaoko Belt * zircon Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.797, year: 2008

Wave propagation in a transversely isotropic magneto-electro-elastic solid bar immersed in an inviscid fluid

Directory of Open Access Journals (Sweden)

R. Selvamani

2016-01-01

Full Text Available Wave propagation in a transversely isotropic magneto-electro-elastic solid bar immersed in an inviscid fluid is discussed within the frame work of linearized three dimensional theory of elasticity. Three displacement potential functions are introduced to uncouple the equations of motion, electric and magnetic induction. The frequency equations that include the interaction between the solid bar and fluid are obtained by the perfect slip boundary conditions using the Bessel functions. The numerical calculations are carried out for the non-dimensional frequency, phase velocity and attenuation coefficient by fixing wave number and are plotted as the dispersion curves. The results reveal that the proposed method is very effective and simple and can be applied to other bar of different cross section by using proper geometric relation.

Dynamic analysis of multibody system immersed in a fluid medium

International Nuclear Information System (INIS)

Wu, R.W.; Liu, L.K.; Levy, S.

1977-01-01

This paper is concerned primarily with the development and evaluation of an analysis method for the reponse prediction of immersed systems to seismic and other dynamic excitations. For immersed multibody systems, the hydrodynamic interaction causes coupled motion among the solid bodies. Also, under intense external excitations, impact between bodies may occur. The complex character of such systems inhibit the use of conventional analytical solutions in closed form. Therefore, approximate numerical schemes have been devised. For an incompressible, inviscid fluid, the hydrodynamic forces exerted by the fluid on solid bodies are determined to be linearly proportional to the acceleration of the vibrating solid bodies; i.e., the presence of the fluid only affects the inertia of the solid body system. A finite element computer program has been developed for computing this hydrodynamic (or added) mass effect. This program can be used to determine the hydrodynamic mass of a two-dimensional fluid field with solid bodies of arbitrary geometry. Triangular elements and linear pressure interpolation function are used to discretize the fluid region. The component element method is used to determine the dynamic response of the multibody system to externally applied mechanical loading or support excitation. The present analysis method for predicting the dynamic response of submerged multibody system is quite general and pertains to any number of solid bodies. However in this paper, its application is demonstrated only for 4 and 25 body systems. (Auth.)

Immersive volume rendering of blood vessels

Science.gov (United States)

Long, Gregory; Kim, Han Suk; Marsden, Alison; Bazilevs, Yuri; Schulze, Jürgen P.

2012-03-01

In this paper, we present a novel method of visualizing flow in blood vessels. Our approach reads unstructured tetrahedral data, resamples it, and uses slice based 3D texture volume rendering. Due to the sparse structure of blood vessels, we utilize an octree to efficiently store the resampled data by discarding empty regions of the volume. We use animation to convey time series data, wireframe surface to give structure, and utilize the StarCAVE, a 3D virtual reality environment, to add a fully immersive element to the visualization. Our tool has great value in interdisciplinary work, helping scientists collaborate with clinicians, by improving the understanding of blood flow simulations. Full immersion in the flow field allows for a more intuitive understanding of the flow phenomena, and can be a great help to medical experts for treatment planning.

Institutional interventions in complex urban systems: Coping with boundary issues in urban planning projects

NARCIS (Netherlands)

S. Verweij (Stefan); I.F. van Meerkerk (Ingmar); J.F.M. Koppenjan (Joop); H. Geerlings (Harry)

2014-01-01

markdownabstract__Abstract__ Urban planning projects are planned and organized through arrangements between actors. These arrangements are institutional interventions: they intervene in the institutional landscape as existing organizational boundaries are (temporarily) redrawn. Such boundary

Surface hardness of hybrid ionomer cement after immersion in antiseptic solution

Directory of Open Access Journals (Sweden)

Anita Yuliati

2006-06-01

Full Text Available Hybrid ionomer cement or resin modified glass ionomer cement is a developed form of conventional glass ionomer cement. This hybrid ionomer cement can be eroded if in direct contact with acid solution which will affect surface hardness. The aim of this study is to learn surface hardness of hybrid ionomer cement after immersion in methyl salicylate 0.06% (pH 3.6 and povidon iodine 1% (pH 2.9 solution. Sample of hybrid ionomer cement with 5 mm diameter and 3 mm thickness was immersed in sterile aquadest solution (control, methyl salicylate pH 3.6, povidon iodine pH 2.9 for 1 minute, 7 and 14 minutes. Surface hardness was measured with Micro Vickers Hardness Tester. The obtained data was analyzed statistically with ANOVA followed by LSD test. The result of hybrid ionomer cement after immersion in sterile aquadest, methyl salicylate 0.06% pH 3.6 and povidon iodine 1% pH 2.9 for one minute, showed no significant difference; while immersion for 7 and 14 minutes showed a significant difference. The conclusion states that hybrid ionomer cement after 14 minutes immersion in povidon iodine 1% pH 2.9 has the lowest surface hardness.

In vitro multiplication of Morinda royoc L. in Temporary Immersion Systems

Directory of Open Access Journals (Sweden)

Elio Jiménez

2011-04-01

Full Text Available Morinda royoc L. is a medicinal plant which has identified numerous secondary metabolites important for medical and pharmaceutical industry. The use of in vitro culture techniques could contribute to the production of these. The aim of this work was to multiply M. royoc using Temporary Immersion System (TIS. It was used TIS of 1000 ml capacity. Each contained 250 ml MS medium with 4.4 μM benzyladenine (BA and 2.9 μM indole acetic acid (IAA. The SIT were inoculated with 30 individual explants (shoot tips and nodal segments. It was determined the effect of the immersion frequency (two, four and six immersions of two minutes per day and the type of explants (shoot tips, nodal segments on the multiplication of shoots and biomass production. It was found that with four and six immersions per day the highest values of multiplication coefficient and shoot length were obtained. The maximum biomass production was achieved with six immersions per day. No hyperhidricity symptoms were observed in shoots. It was noted that the nodal segments produced more shoots per explant, increased multiplication coefficient and biomass than the apex, while the latter resulted in longer shoots. Keywords: micropropagation, shoots multiplication

An immersed interface vortex particle-mesh solver

Science.gov (United States)

Marichal, Yves; Chatelain, Philippe; Winckelmans, Gregoire

2014-11-01

An immersed interface-enabled vortex particle-mesh (VPM) solver is presented for the simulation of 2-D incompressible viscous flows, in the framework of external aerodynamics. Considering the simulation of free vortical flows, such as wakes and jets, vortex particle-mesh methods already provide a valuable alternative to standard CFD methods, thanks to the interesting numerical properties arising from its Lagrangian nature. Yet, accounting for solid bodies remains challenging, despite the extensive research efforts that have been made for several decades. The present immersed interface approach aims at improving the consistency and the accuracy of one very common technique (based on Lighthill's model) for the enforcement of the no-slip condition at the wall in vortex methods. Targeting a sharp treatment of the wall calls for substantial modifications at all computational levels of the VPM solver. More specifically, the solution of the underlying Poisson equation, the computation of the diffusion term and the particle-mesh interpolation are adapted accordingly and the spatial accuracy is assessed. The immersed interface VPM solver is subsequently validated on the simulation of some challenging impulsively started flows, such as the flow past a cylinder and that past an airfoil. Research Fellow (PhD student) of the F.R.S.-FNRS of Belgium.

A question of fit: reflections on boundaries, organizations and social-ecological systems.

Science.gov (United States)

Sternlieb, Faith; Bixler, R Patrick; Huber-Stearns, Heidi; Huayhuaca, Ch'aska

2013-11-30

Although there is acknowledgment that the complexity of social-ecological systems governance demands representation from diverse perspectives, there is little agreement in the literature on how to cross both fiat (human-demarcated) and bona fide (physical) boundaries to address such complexities. As a cohort of interdisciplinary scholars, we navigate the boundary between science and practice to address the question of fit regarding the role of organizations in transcending boundaries. We found there is a need to rectify discrepancies between theories about boundaries and theories about organizations. To this end, we propose a conceptual framework to analyze transboundary organizations, an umbrella term to group the literature on boundary organizations, intermediaries and bridging organizations; we introduce this term to illustrate they are not mutually exclusive and to facilitate interdisciplinary research. We first examine social-ecological systems (SES), a framework intended to improve understandings of boundaries and governance. We then continue to unpack the complexity of boundaries and organizations, specifically through important transboundary concepts such as scale and organizational learning. This helps frame our examination of the literature on: 1) boundary organizations; 2) bridging organizations (third-party entities); and 3) intermediaries (distinguished by their position between other actors). Our review identifies a number of discrepancies that pertain to the types of boundaries discussed and the roles assigned to organizations governing SES. Important characteristics have emerged from our review of transboundary organizations including legitimacy, saliency, urgency, and credibility. In developing a conceptual framework, we argue that transboundary organizations: 1) expand upon the boundary spectrum, 2) incorporate transboundary concepts, and 3) hybridize characteristics of boundary, bridging, and intermediary organizations. We conclude with a number

Immersive visualization of rail simulation data.

Science.gov (United States)

2016-01-01

The prime objective of this project was to create scientific, immersive visualizations of a Rail-simulation. This project is a part of a larger initiative that consists of three distinct parts. The first step consists of performing a finite element a...

Immersive Simulation Training for the Dismounted Soldier

National Research Council Canada - National Science Library

Knerr, Bruce W

2007-01-01

... R&D organizations during the period 1997 - 2005. The major findings are organized around the topics of training effectiveness, Soldier task performance, and advantages and disadvantages of immersive...

Immersive Virtual Reality for Visualization of Abdominal CT.

Science.gov (United States)

Lin, Qiufeng; Xu, Zhoubing; Li, Bo; Baucom, Rebeccah; Poulose, Benjamin; Landman, Bennett A; Bodenheimer, Robert E

2013-03-28

Immersive virtual environments use a stereoscopic head-mounted display and data glove to create high fidelity virtual experiences in which users can interact with three-dimensional models and perceive relationships at their true scale. This stands in stark contrast to traditional PACS-based infrastructure in which images are viewed as stacks of two-dimensional slices, or, at best, disembodied renderings. Although there has substantial innovation in immersive virtual environments for entertainment and consumer media, these technologies have not been widely applied in clinical applications. Here, we consider potential applications of immersive virtual environments for ventral hernia patients with abdominal computed tomography imaging data. Nearly a half million ventral hernias occur in the United States each year, and hernia repair is the most commonly performed general surgery operation worldwide. A significant problem in these conditions is communicating the urgency, degree of severity, and impact of a hernia (and potential repair) on patient quality of life. Hernias are defined by ruptures in the abdominal wall (i.e., the absence of healthy tissues) rather than a growth (e.g., cancer); therefore, understanding a hernia necessitates understanding the entire abdomen. Our environment allows surgeons and patients to view body scans at scale and interact with these virtual models using a data glove. This visualization and interaction allows users to perceive the relationship between physical structures and medical imaging data. The system provides close integration of PACS-based CT data with immersive virtual environments and creates opportunities to study and optimize interfaces for patient communication, operative planning, and medical education.

Immersive virtual reality for visualization of abdominal CT

Science.gov (United States)

Lin, Qiufeng; Xu, Zhoubing; Li, Bo; Baucom, Rebeccah; Poulose, Benjamin; Landman, Bennett A.; Bodenheimer, Robert E.

2013-03-01

Immersive virtual environments use a stereoscopic head-mounted display and data glove to create high fidelity virtual experiences in which users can interact with three-dimensional models and perceive relationships at their true scale. This stands in stark contrast to traditional PACS-based infrastructure in which images are viewed as stacks of two dimensional slices, or, at best, disembodied renderings. Although there has substantial innovation in immersive virtual environments for entertainment and consumer media, these technologies have not been widely applied in clinical applications. Here, we consider potential applications of immersive virtual environments for ventral hernia patients with abdominal computed tomography imaging data. Nearly a half million ventral hernias occur in the United States each year, and hernia repair is the most commonly performed general surgery operation worldwide. A significant problem in these conditions is communicating the urgency, degree of severity, and impact of a hernia (and potential repair) on patient quality of life. Hernias are defined by ruptures in the abdominal wall (i.e., the absence of healthy tissues) rather than a growth (e.g., cancer); therefore, understanding a hernia necessitates understanding the entire abdomen. Our environment allows surgeons and patients to view body scans at scale and interact with these virtual models using a data glove. This visualization and interaction allows users to perceive the relationship between physical structures and medical imaging data. The system provides close integration of PACS-based CT data with immersive virtual environments and creates opportunities to study and optimize interfaces for patient communication, operative planning, and medical education.

Semiconductor applications of plasma immersion ion implantation ...

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 25; Issue 6. Semiconductor applications of plasma immersion ion implantation technology ... Department of Electronic Science, Kurukshetra University, Kurukshetra 136 119, India ...

Submicron hollow spot generation by solid immersion lens and structured illumination

NARCIS (Netherlands)

Kim, M.S.; Assafrao, A.C.; Scharf, T.; Wachters, A.J.H.; Pereira, S.F.; Urbach, H.P.; Brun, M.; Olivier, S.; Nicoletti, S.; Herzig, H.P.

2012-01-01

We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (?-SIL) made of SiO2. Such structured focal spots are characterized by a

Associations of Subjective Immersion, Immersion Subfactors, and Learning Outcomes in the Revised Game Engagement Model

Science.gov (United States)

Barclay, Paul A.; Bowers, Clint

2018-01-01

Serious Educational Video Games (SEGs) play a large role in education for both children and adults. However, the budget for SEGs is typically lower than traditional entertainment video games, bringing with it the need to optimize the learning experience. This article looks at the role game immersion plays in improving learning outcomes, using the…

From plasma immersion ion implantation to deposition: A historical perspective on principles and trends

Energy Technology Data Exchange (ETDEWEB)

Anders, Andre

2001-06-14

Plasma immersion techniques of surface modification are known under a myriad of names. The family of techniques reaches from pure plasma ion implantation, to ion implantation and deposition hybrid modes, to modes that are essentially plasma film deposition with substrate bias. In the most general sense, all plasma immersion techniques have in common that the surface of a substrate (target) is exposed to plasma and that relatively high substrate bias is applied. The bias is usually pulsed. In this review, the roots of immersion techniques are explored, some going back to the 1800s, followed by a discussion of the groundbreaking works of Adler and Conrad in the 1980s. In the 1990s, plasma immersion techniques matured in theoretical understanding, scaling, and the range of applications. First commercial facilities are now operational. Various immersion concepts are compiled and explained in this review. While gas (often nitrogen) ion implantation dominated the early years, film-forming immersion techniques and semiconductor processing gained importance. In the 1980s and 1990s we have seen exponential growth of the field but signs of slowdown are clear since 1998. Nevertheless, plasma immersion techniques have found, and will continue to have, an important place among surface modification techniques.

The transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion

Directory of Open Access Journals (Sweden)

Devi Rianti

2006-12-01

Full Text Available A laboratoric experimental study was conducted on the transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion. The aim of this study is to know the difference of acrylic resin transverse strengths caused by immersion time variations in a concentrate solution. The study was carried out on unpolished acrylic resin plates with 65 × 10 × 2,5 mm dimension; solution with 15% Coleus amboinicus, Lour extract, and 30, 60, 90 days immersion times to measure the transverse strength and sterilized aquadest was used as control. Acrylic resin plates transverse strength was measured using Autograph AG-10 TE. The data was analyzed using One-Way Anova and LSD with 5% degree of significance. The result showed that longer immersion time will decrease the transverse strength of the acrylic resin plates. After 90 days immersion time, the transverse strength decrease is still above the recommended standard transverse strength.

Boundary Spanning in Global Software Development

DEFF Research Database (Denmark)

Søderberg, Anne-Marie; Romani, Laurence

imbalances of power, exacerbated in the case of an Indian vendor and a European client, need to be taken into account. The paper thus contributes with a more context sensitive understanding of inter-organizational boundary work. Taking the vendor perspective also leads to problematization of common...... of Indian IT vendor managers who are responsible for developing client relations and coordinating complex global development projects. The authors revise a framework of boundary spanning leadership practices to adapt it to an offshore outsourcing context. The empirical investigation highlights how...

Predicting Participation in Dual Language Immersion Using Theory of Planned Behavior

Science.gov (United States)

Call, Andrea; Domenech Rodríguez, Melanie M.; Vázquez, Alejandro L.; Corralejo, Samantha M.

2018-01-01

Dual language immersion programs are increasing in popularity. Yet little is known about what motivates parents to enroll their children in dual language immersion. The theory of planned behavior posits that behavior is based on attitudes, subjective norms, and perceived behavioral control. The current study was an exploratory evaluation of the…

Bonding capacity of the GFRP-S on strengthened RC beams after sea water immersion

Science.gov (United States)

Sultan, Mufti Amir; Djamaluddin, Rudy

2017-11-01

Construction of concrete structures that located in extreme environments are such as coastal areas will result in decreased strength or even the damage of the structures. As well know, chloride contained in sea water is responsible for strength reduction or structure fail were hence maintenance and repairs on concrete structure urgently needed. One popular method of structural improvements which under investigation is to use the material Glass Fibre Reinforced Polymer which has one of the advantages such as corrosion resistance. This research will be conducted experimental studies to investigate the bonding capacity behavior of reinforced concrete beams with reinforcement GFRP-S immersed in sea water using immersion time of one month, three months, six months and twelve months. Test specimen consists of 12 pieces of reinforced concrete beams with dimensions (150x200x3000) mm that had been reinforced with GFRP-S in the area of bending, the beam without immersion (B0), immersion one month (B1), three months (B3), six months (B6) and twelve months (B12). Test specimen were cured for 28 days before the application of the GFRP sheet. Test specimen B1, B3, B6 and B12 that have been immersed in sea water pool with a immersion time each 1, 3, 6 and 12 months. The test specimen without immersion test by providing a static load until it reaches the failure, to record data during the test strain gauge mounted on the surface of the specimen and the GFRP to collect the strain value. From the research it obvious that there is a decrease bonding capacity on specimens immersed for one month, three months, six months and twelve months against the test object without immersion of 8.85%; 8.89%; 9.33% and 11.04%.

Analytical framework for borehole heat exchanger (BHE) simulation influenced by horizontal groundwater flow and complex top boundary conditions

Science.gov (United States)

Rivera, Jaime; Blum, Philipp; Bayer, Peter

2015-04-01

Borehole heat exchangers (BHE) are the most widely used technologies for tapping low-enthalpy energy resources in the shallow subsurface. Analysis of these systems requires a proper simulation of the relevant processes controlling the transfer of heat between the BHE and the ground. Among the available simulation approaches, analytical methods are broadly accepted, especially when low computational costs and comprehensive analyses are demanded. Moreover, these methods constitute the benchmark solutions to evaluate the performance of more complex numerical models. Within the spectrum of existing (semi-)analytical models, those based on the superposition of problem-specific Green's functions are particularly appealing. Green's functions can be derived, for instance, for nodal or line sources with constant or transient strengths. In the same manner, functional forms can be obtained for scenarios with complex top boundary conditions whose temperature may vary in space and time. Other relevant processes, such as advective heat transport, mechanical dispersion and heat transfer through the unsaturated zone could be incorporated as well. A keystone of the methodology is that individual solutions can be added up invoking the superposition principle. This leads to a flexible and robust framework for studying the interaction of multiple processes on thermal plumes of BHEs. In this contribution, we present a new analytical framework and its verification via comparison with a numerical model. It simulates a BHE as a line source, and it integrates both horizontal groundwater flow and the effect of top boundary effects due to variable land use. All these effects may be implemented as spatially and temporally variable. For validation, the analytical framework is successfully applied to study cases where highly resolved temperature data is available.

Going Outside While Staying Inside - Exercise Motivation with Immersive vs. Non–Immersive Recreational Virtual Environment Augmentation for Older Adult Nursing Home Residents

DEFF Research Database (Denmark)

Bruun-Pedersen, Jon Ram; Serafin, Stefania; Kofoed, Lise

2016-01-01

Virtual technology and immersive experiences are not very often associated with older adults. Recent studies suggest that exercise augmentation using flat screen-based virtual environments, which allow nursing home residents to experience virtual places different from the nursing home, can increase...... the intrinsic motivation of nursing home residents. In this paper, we increase the immersive properties of such augmentation through an Oculus Rift Head Mounted Display, to evaluate the effect on the older adults’ sense of presence, if it has any relation to the level of intrinsic motivation to exercise...

Atrial distension, haemodilution, and acute control of renin release during water immersion in humans

DEFF Research Database (Denmark)

Gabrielsen, A; Pump, B; Bie, P

2002-01-01

immersion. During WI, central venous pressure (CVP) and left atrial diameter (LAD) increased (P ... is not the single pivotal stimulus for the acute suppression of renin release in response to intravascular volume expansion by water immersion in humans. Haemodilution constitutes a significant and conceivably the principal stimulus for the acute immersion-induced suppression of renin-angiotensin system activity....

Immersion autometallography: histochemical in situ capturing of zinc ions in catalytic zinc-sulfur nanocrystals.

Science.gov (United States)

Danscher, Gorm; Stoltenberg, Meredin; Bruhn, Mikkel; Søndergaard, Chris; Jensen, Dorete

2004-12-01

In the mid-1980s, two versions of Timm's original immersion sulfide silver method were published. The authors used immersion of tissue in a sulfide solution as opposed to Timm, who used immersion of tissue blocks in hydrogen sulfide-bubbled alcohol. The autometallography staining resulting from the "sulfide only immersion" was not particularly impressive, but the significance of this return to an old approach became obvious when Wenzel and co-workers presented their approach in connection with introduction by the Palmiter group of zinc transporter 3 (ZnT3). The Wenzel/Palmiter pictures are the first high-resolution, high-quality pictures taken from tissues in which free and loosely bound zinc ions have been captured in zinc-sulfur nanocrystals by immersion. The trick was to place formalin-fixed blocks of mouse brains in a solution containing 3% glutaraldehyde and 0.1% sodium sulfide, ingredients used for transcardial perfusion in the zinc-specific NeoTimm method. That the NeoTimm technique results in silver enhancement of zinc-sulfur nanocrystals has been proved by proton-induced X-ray multielement analyses (PIXE) and in vivo chelation with diethyldithiocarbamate (DEDTC). The aims of the present study were (a) to make the immersion-based capturing of zinc ions in zinc-sulfur nanocrystals work directly on sections and slices of fixed brain tissue, (b) to work out protocols that ensure zinc specificity and optimal quality of the staining, (c) to apply "immersion autometallography" (iZnSAMG) to other tissues that contain zinc-enriched (ZEN) cells, and (d) to make the immersion approach work on unfixed fresh tissue.

Immersive Environments: Using Flow and Sound to Blur Inhabitant and Surroundings

Science.gov (United States)

Laverty, Luke

Following in the footsteps of motif-reviving, aesthetically-focused Postmodern and deconstructivist architecture, purely computer-generated formalist contemporary architecture (i.e. blobitecture) has been reduced to vast, empty sculptural, and therefore, purely ocularcentric gestures for their own sake. Taking precedent over the deliberate relation to the people inhabiting them beyond scaleless visual stimulation, the forms become separated from and hostile toward their inhabitants; a boundary appears. This thesis calls for a reintroduction of human-centered design beyond Modern functionalism and ergonomics and Postmodern form and metaphor into architecture by exploring ecological psychology (specifically how one becomes attached to objects) and phenomenology (specifically sound) in an attempt to reach a contemporary human scale using the technology of today: the physiological mind. Psychologist Dr. Mihaly Csikszentmihalyi's concept of flow---when one becomes so mentally immersed within the current activity and immediate surroundings that the boundary between inhabitant and environment becomes transparent through a form of trance---is the embodiment of this thesis' goal, but it is limited to only specific moments throughout the day and typically studied without regard to the environment. Physiologically, the area within the brain---the medial prefrontal cortex---stimulated during flow experiences is also stimulated by the synthesis of sound, memory, and emotion. By exploiting sound (a sense not typically focused on within phenomenology) as a form of constant nuance within the everyday productive dissonance, the engagement and complete concentration on one's own interpretation of this sensory input affords flow experiences and, therefore, a blurred boundary with one's environment. This thesis aims to answer the question: How does the built environment embody flow? The above concept will be illustrated within a ubiquitous building type---the everyday housing tower

Dissolved Gas Analysis Principle-Based Intelligent Approaches to Fault Diagnosis and Decision Making for Large Oil-Immersed Power Transformers: A Survey

Directory of Open Access Journals (Sweden)

Lefeng Cheng

2018-04-01

Full Text Available Compared with conventional methods of fault diagnosis for power transformers, which have defects such as imperfect encoding and too absolute encoding boundaries, this paper systematically discusses various intelligent approaches applied in fault diagnosis and decision making for large oil-immersed power transformers based on dissolved gas analysis (DGA, including expert system (EPS, artificial neural network (ANN, fuzzy theory, rough sets theory (RST, grey system theory (GST, swarm intelligence (SI algorithms, data mining technology, machine learning (ML, and other intelligent diagnosis tools, and summarizes existing problems and solutions. From this survey, it is found that a single intelligent approach for fault diagnosis can only reflect operation status of the transformer in one particular aspect, causing various degrees of shortcomings that cannot be resolved effectively. Combined with the current research status in this field, the problems that must be addressed in DGA-based transformer fault diagnosis are identified, and the prospects for future development trends and research directions are outlined. This contribution presents a detailed and systematic survey on various intelligent approaches to faults diagnosing and decisions making of the power transformer, in which their merits and demerits are thoroughly investigated, as well as their improvement schemes and future development trends are proposed. Moreover, this paper concludes that a variety of intelligent algorithms should be combined for mutual complementation to form a hybrid fault diagnosis network, such that avoiding these algorithms falling into a local optimum. Moreover, it is necessary to improve the detection instruments so as to acquire reasonable characteristic gas data samples. The research summary, empirical generalization and analysis of predicament in this paper provide some thoughts and suggestions for the research of complex power grid in the new environment, as

SurfCut: Free-Boundary Surface Extraction

KAUST Repository

Algarni, Marei Saeed Mohammed

2016-09-15

We present SurfCut, an algorithm for extracting a smooth simple surface with unknown boundary from a noisy 3D image and a seed point. In contrast to existing approaches that extract smooth simple surfaces with boundary, our method requires less user input, i.e., a seed point, rather than a 3D boundary curve. Our method is built on the novel observation that certain ridge curves of a front propagated using the Fast Marching algorithm are likely to lie on the surface. Using the framework of cubical complexes, we design a novel algorithm to robustly extract such ridge curves and form the surface of interest. Our algorithm automatically cuts these ridge curves to form the surface boundary, and then extracts the surface. Experiments show the robustness of our method to errors in the data, and that we achieve higher accuracy with lower computational cost than comparable methods. © Springer International Publishing AG 2016.

iCAVE: an open source tool for visualizing biomolecular networks in 3D, stereoscopic 3D and immersive 3D.

Science.gov (United States)

Liluashvili, Vaja; Kalayci, Selim; Fluder, Eugene; Wilson, Manda; Gabow, Aaron; Gümüs, Zeynep H

2017-08-01

Visualizations of biomolecular networks assist in systems-level data exploration in many cellular processes. Data generated from high-throughput experiments increasingly inform these networks, yet current tools do not adequately scale with concomitant increase in their size and complexity. We present an open source software platform, interactome-CAVE (iCAVE), for visualizing large and complex biomolecular interaction networks in 3D. Users can explore networks (i) in 3D using a desktop, (ii) in stereoscopic 3D using 3D-vision glasses and a desktop, or (iii) in immersive 3D within a CAVE environment. iCAVE introduces 3D extensions of known 2D network layout, clustering, and edge-bundling algorithms, as well as new 3D network layout algorithms. Furthermore, users can simultaneously query several built-in databases within iCAVE for network generation or visualize their own networks (e.g., disease, drug, protein, metabolite). iCAVE has modular structure that allows rapid development by addition of algorithms, datasets, or features without affecting other parts of the code. Overall, iCAVE is the first freely available open source tool that enables 3D (optionally stereoscopic or immersive) visualizations of complex, dense, or multi-layered biomolecular networks. While primarily designed for researchers utilizing biomolecular networks, iCAVE can assist researchers in any field. © The Authors 2017. Published by Oxford University Press.

Composition, structure and morphology of oxide layers formed on austenitic stainless steel by oxygen plasma immersion ion implantation

International Nuclear Information System (INIS)

Anandan, C.; Rajam, K.S.

2007-01-01

Oxygen ions were implanted in to austenitic stainless steel by plasma immersion ion implantation at 400 deg. C. The implanted samples were characterized by XPS, GIXRD, micro-Raman, AFM, optical and scanning electron microscopies. XPS studies showed the presence of Fe in elemental, as Fe 2+ in oxide form and as Fe 3+ in the form of oxyhydroxides in the substrate. Iron was present in the oxidation states of Fe 2+ and Fe 3+ in the implanted samples. Cr and Mn were present as Cr 3+ and Mn 2+ , respectively, in both the substrate and implanted samples. Nickel remained unaffected by implantation. GIXRD and micro-Raman studies showed the oxide to be a mixture of spinel and corundum structures. Optical and AFM images showed an island structure on underlying oxide. This island structure was preserved at different thicknesses. Further, near the grain boundaries more oxide growth was found. This is explained on the basis of faster diffusion of oxygen in the grain boundary regions. Measurement of total hemispherical optical aborptance, α and emittance, ε of the implanted sample show that it has good solar selective properties

Damping system immersed in a fluid

International Nuclear Information System (INIS)

1980-01-01

The invention relates to a damping system which is immersed in a fluid and allows slow motion, while opposing fast motion of a mobile or deformable system immersed in a fluid. Nuclear reactors utilize fabricated assemblies immmersed in the spent fuel storage pool to support the fuel elements placed in the pool, e.g., when refueling the reactor. These fabricated assemblies must be held in position, relative to the concrete walls of the pool, so as to allow slow deformation of the assemblies due to thermal expansion, while curbing fast motion, e.g., earthquake-induced motion. Such fast motion due to earthquakes might be the cause of resonance phenomena involving the fuel storage rack structure and the pool walls, should the rack structure and pool walls have the same resonant frequency. In the event of an earthquake, the damping system would provide for fast curbing of structure motion to prevent uncontrolled deformation which might result in breaks and destruction [fr

Influence of cold-water immersion on limb blood flow after resistance exercise.

Science.gov (United States)

Mawhinney, Chris; Jones, Helen; Low, David A; Green, Daniel J; Howatson, Glyn; Gregson, Warren

2017-06-01

This study determined the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow following resistance exercise. Twelve males completed 4 sets of 10-repetition maximum squat exercise and were then immersed, semi-reclined, into 8°C or 22°C water for 10-min, or rested in a seated position (control) in a randomized order on different days. Rectal and thigh skin temperature, muscle temperature, thigh and calf skin blood flow and superficial femoral artery blood flow were measured before and after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). The colder water reduced thigh skin temperature and deep muscle temperature to the greatest extent (P lower (55%) than the control post-immersion (P water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise.

Immersed friction stir welding of ultrafine grained accumulative roll-bonded Al alloy

International Nuclear Information System (INIS)

Hosseini, M.; Danesh Manesh, H.

2010-01-01

In this research, ultrafine grained strips of commercial pure strain hardenable aluminum (AA1050) were produced by accumulative roll-bonding (ARB) technique. These strips were joined by friction stir welding (FSW) in immersed (underwater) and conventional (in-air) conditions to investigate the effect of the immersion method on the microstructure and mechanical properties of the joint, aiming to reduce the deterioration of the mechanical properties of the joint. Transmission electron microscopy and X-ray diffraction analyses were used to evaluate the microstructure, showing smaller grains and subgrains in the stir zone of the immersed FSW condition with respect to the conventional FSW method. The hardness and tensile properties of the immersed friction stir welded sample and ARBed base metal show more similarity compared to the conventional friction stir welded sample. Moreover, the aforementioned method can result in the enhancement of the superplasticity tendency of the material.

Discoloration of various CAD/CAM blocks after immersion in coffee

Directory of Open Access Journals (Sweden)

Sasipin Lauvahutanon

2017-02-01

Full Text Available Objectives This study evaluated color differences (ΔEs and translucency parameter changes (ΔTPs of various computer-aided design/computer-aided manufacturing (CAD/CAM blocks after immersion in coffee. Materials and Methods Eight CAD/CAM blocks and four restorative composite resins were evaluated. The CIE L*a*b* values of 2.0 mm thick disk-shaped specimens were measured using the spectrophotometer on white and black backgrounds (n = 6. The ΔEs and ΔTPs of one day, one week, and one month immersion in coffee or water were calculated. The values of each material were analyzed by two-way ANOVA and Tukey's multiple comparisons (α = 0.05. The ΔEs after prophylaxis paste polishing of 1 month coffee immersion specimens, water sorption and solubility were also evaluated. Results After one month in coffee, ΔEs of CAD/CAM composite resin blocks and restorative composites ranged from 1.6 to 3.7 and from 2.1 to 7.9, respectively, and ΔTPs decreased. The ANOVA of ΔEs and ΔTPs revealed significant differences in two main factors, immersion periods and media, and their interaction except for ΔEs of TEL (Telio CAD, Ivoclar Vivadent. The ΔEs significantly decreased after prophylaxis polishing except GRA (Gradia Block, GC. There was no significant correlation between ΔEs and water sorption or solubility in water. Conclusions The ΔEs of CAD/CAM blocks after immersion in coffee varied among products and were comparable to those of restorative composite resins. The discoloration of CAD/CAM composite resin blocks could be effectively removed with prophylaxis paste polishing, while that of some restorative composites could not be removed.

The effect of head-down tilt and water immersion on intracranial pressure in nonhuman primates

Science.gov (United States)

Keil, Lanny C.; Mckeever, Kenneth H.; Skidmore, Michael G.; Hines, John; Severs, Walter B.

1992-01-01

Intracranial pressure (ICP) is investigated in primates during and after -6-deg head-down tilt (HDT) and immersion in water to examine the effects of the headward fluid shift related to spaceflight. Following the HDT the primates are subjected to head-out thermoneutral water immersion, and the ICP is subsequently measured. ICP is found to increase from 3.8 +/- 1.1 to 5.3 +/- 1.3 mm Hg during the horizontal control period. ICP stabilizes at -6.3 +/- 1.3 mm Hg and then increases to -2.2 +/- 1.9 mm Hg during partial immersion, and ICP subsequently returns to preimmersion levels after immersion. These data indicate that exposure to HDT or water immersion lead to an early sharp increase in ICP, and water immersion alone leads to higher ICP levels. A significant conclusion of the work is that the ICP did not approach pathological levels, and this finding is relevant to human spaceflight research.

VirtualizeMe: Real-time avatar creation for Tele-Immersion environments

KAUST Repository

Knoblauch, Daniel

2010-03-01

VirtualizeMe introduces a new design for a fully immersive Tele-Immersion system for remote collaboration and virtual world interaction. This system introduces a new avatar creation approach full-filling four main attributes: high resolution, scalability, flexibility and affordability. This is achieved by a total separation of reconstruction and rendering and exploiting the capabilities of modern graphic cards. The high resolution is achieved by using as much of the input information as possible through lossless compression of the input data and introducing a focused volumetric visual hull reconstruction. The resulting avatar allows eye-to-eye collaboration for remote users. The interaction with the virtual world is facilitated by the volumetric avatar model and allows a fully immersive system. This paper shows a proof of concept based on publicly available pre-recorded data to allow easier comparison. ©2010 IEEE.

A review of characteristics and outcomes of Australia's undergraduate medical education rural immersion programs.

Science.gov (United States)

O'Sullivan, Belinda G; McGrail, Matthew R; Russell, Deborah; Chambers, Helen; Major, Laura

2018-01-31

A key strategy for increasing the supply of rural doctors is rurally located medical education. In 2000, Australia introduced a national policy to increase rural immersion for undergraduate medical students. This study aims to describe the characteristics and outcomes of the rural immersion programs that were implemented in Australian medical schools. Information about 19 immersion programs was sourced in 2016 via the grey and published literature. A scoping review of the published peer-reviewed studies via Ovid MEDLINE and Informit (2000-2016) and direct journal searching included studies that focused on outcomes of undergraduate rural immersion in Australian medical schools from 2000 to 2016. Programs varied widely by selection criteria and program design, offering between 1- and 6-year immersion. Based on 26 studies from 10 medical schools, rural immersion was positively associated with rural practice in the first postgraduate year (internship) and early career (first 10 years post-qualifying). Having a rural background increased the effects of rural immersion. Evidence suggested that longer duration of immersion also increases the uptake of rural work, including by metropolitan-background students, though overall there was limited evidence about the influence of different program designs. Most evidence was based on relatively weak, predominantly cross-sectional research designs and single-institution studies. Many had flaws including small sample sizes, studying internship outcomes only, inadequately controlling for confounding variables, not using metropolitan-trained controls and providing limited justification as to the postgraduate stage at which rural practice outcomes were measured. Australia's immersion programs are moderately associated with an increased rural supply of early career doctors although metropolitan-trained students contribute equal numbers to overall rural workforce capacity. More research is needed about the influence of student interest

Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans

DEFF Research Database (Denmark)

Kjeld, Thomas; Pott, Frank C; Secher, Niels H

2009-01-01

The diving response is initiated by apnea and facial immersion in cold water and includes, besides bradycardia, peripheral vasoconstriction, while cerebral perfusion may be enhanced. This study evaluated whether facial immersion in 10 degrees C water has an independent influence on cerebral...... immersion further increased MCA V(mean) to 122 cm/s ( approximately 88%; both P ... 180-W exercise (from 47 to 53 cm/s), and this increment became larger with facial immersion (76 cm/s, approximately 62%; P 100% increase in MCA V(mean), largely...

The effect of water immersion on short-latency somatosensory evoked potentials in human

Directory of Open Access Journals (Sweden)

Sato Daisuke

2012-01-01

Full Text Available Abstract Background Water immersion therapy is used to treat a variety of cardiovascular, respiratory, and orthopedic conditions. It can also benefit some neurological patients, although little is known about the effects of water immersion on neural activity, including somatosensory processing. To this end, we examined the effect of water immersion on short-latency somatosensory evoked potentials (SEPs elicited by median nerve stimuli. Short-latency SEP recordings were obtained for ten healthy male volunteers at rest in or out of water at 30°C. Recordings were obtained from nine scalp electrodes according to the 10-20 system. The right median nerve at the wrist was electrically stimulated with the stimulus duration of 0.2 ms at 3 Hz. The intensity of the stimulus was fixed at approximately three times the sensory threshold. Results Water immersion significantly reduced the amplitudes of the short-latency SEP components P25 and P45 measured from electrodes over the parietal region and the P45 measured by central region. Conclusions Water immersion reduced short-latency SEP components known to originate in several cortical areas. Attenuation of short-latency SEPs suggests that water immersion influences the cortical processing of somatosensory inputs. Modulation of cortical processing may contribute to the beneficial effects of aquatic therapy. Trial Registration UMIN-CTR (UMIN000006492

Lack of diurnal effects on periodic exercise during prolonged cold water immersion.

Science.gov (United States)

Doubt, T J; Smith, D J

1990-03-01

Diurnal effects on periodic exercise were examined in 8 male divers wearing passive thermal protection during whole body immersions in 5 degrees C water for periods of up to 6 h. Studies were done during the course of 5-day air saturation dives at a depth of 1.61 ATA, with immersions beginning at 1000 h (AM) and 2200 h (PM). During each hour of immersion, leg exercise was done for 3 min each at workloads of 50, 70, and 90 W. Heart rate (HR) at each workload increased uniformly with immersion time, without a change in slope of HR vs. workload. No AM or PM differences occurred. AM resting VO2 increased linearly, and to the same extent as PM, with exposure time. VO2 at 50 W also increased at the same rate as resting values. VO2 at 70 and 90 W were similar for AM and PM and did not vary significantly during the 6-h immersions. Temporal increases in exercise HR may reflect cardiac compensation of diminished plasma volume. Workloads greater than or equal to 70 W generate enough metabolic heat in this specific condition to meet the thermogenic requirement. Lack of diurnal effects on exercise variables may be due to environmental conditions suppressing circadian rhythms.

'My Virtual Dream': Collective Neurofeedback in an Immersive Art Environment.

Directory of Open Access Journals (Sweden)

Natasha Kovacevic

Full Text Available While human brains are specialized for complex and variable real world tasks, most neuroscience studies reduce environmental complexity, which limits the range of behaviours that can be explored. Motivated to overcome this limitation, we conducted a large-scale experiment with electroencephalography (EEG based brain-computer interface (BCI technology as part of an immersive multi-media science-art installation. Data from 523 participants were collected in a single night. The exploratory experiment was designed as a collective computer game where players manipulated mental states of relaxation and concentration with neurofeedback targeting modulation of relative spectral power in alpha and beta frequency ranges. Besides validating robust time-of-night effects, gender differences and distinct spectral power patterns for the two mental states, our results also show differences in neurofeedback learning outcome. The unusually large sample size allowed us to detect unprecedented speed of learning changes in the power spectrum (~ 1 min. Moreover, we found that participants' baseline brain activity predicted subsequent neurofeedback beta training, indicating state-dependent learning. Besides revealing these training effects, which are relevant for BCI applications, our results validate a novel platform engaging art and science and fostering the understanding of brains under natural conditions.

Identification of complex model thermal boundary conditions based on exterior temperature measurement

International Nuclear Information System (INIS)

Lu Jianming; Ouyang Guangyao; Zhang Ping; Rong Bojun

2012-01-01

Combining the advantages of the finite element software in temperature field analyzing with the multivariate function optimization arithmetic, a feasibility method based on the exterior temperature was proposed to get the thermal boundary conditions, which was required in temperature field analyzing. The thermal boundary conditions can be obtained only by some temperature measurement values. Taking the identification of the convection heat transfer coefficient of a high power density diesel engine cylinder head as an example, the calculation result shows that when the temperature measurement error was less than 0.5℃, the maximum relative error was less than 2%. It is shown that the new method was feasible (authors)

The transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion

OpenAIRE

Rianti, Devi

2006-01-01

A laboratoric experimental study was conducted on the transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion. The aim of this study is to know the difference of acrylic resin transverse strengths caused by immersion time variations in a concentrate solution. The study was carried out on unpolished acrylic resin plates with 65 × 10 × 2,5 mm dimension; solution with 15% Coleus amboinicus, Lour extract, and 30, 60, 90 days immersion times to measure the tra...

A Study of Layout, Rendering, and Interaction Methods for Immersive Graph Visualization.

Science.gov (United States)

Kwon, Oh-Hyun; Muelder, Chris; Lee, Kyungwon; Ma, Kwan-Liu

2016-07-01

Information visualization has traditionally limited itself to 2D representations, primarily due to the prevalence of 2D displays and report formats. However, there has been a recent surge in popularity of consumer grade 3D displays and immersive head-mounted displays (HMDs). The ubiquity of such displays enables the possibility of immersive, stereoscopic visualization environments. While techniques that utilize such immersive environments have been explored extensively for spatial and scientific visualizations, contrastingly very little has been explored for information visualization. In this paper, we present our considerations of layout, rendering, and interaction methods for visualizing graphs in an immersive environment. We conducted a user study to evaluate our techniques compared to traditional 2D graph visualization. The results show that participants answered significantly faster with a fewer number of interactions using our techniques, especially for more difficult tasks. While the overall correctness rates are not significantly different, we found that participants gave significantly more correct answers using our techniques for larger graphs.

Plasma immersion ion implantation for the efficient surface modification of medical materials

International Nuclear Information System (INIS)

Slabodchikov, Vladimir A.; Borisov, Dmitry P.; Kuznetsov, Vladimir M.

2015-01-01

The paper reports on a new method of plasma immersion ion implantation for the surface modification of medical materials using the example of nickel-titanium (NiTi) alloys much used for manufacturing medical implants. The chemical composition and surface properties of NiTi alloys doped with silicon by conventional ion implantation and by the proposed plasma immersion method are compared. It is shown that the new plasma immersion method is more efficient than conventional ion beam treatment and provides Si implantation into NiTi surface layers through a depth of a hundred nanometers at low bias voltages (400 V) and temperatures (≤150°C) of the substrate. The research results suggest that the chemical composition and surface properties of materials required for medicine, e.g., NiTi alloys, can be successfully attained through modification by the proposed method of plasma immersion ion implantation and by other methods based on the proposed vacuum equipment without using any conventional ion beam treatment

Heats of immersion in the thorium oxide-water system at elevated temperatures

International Nuclear Information System (INIS)

Holmes, H.F.

1976-01-01

The surface properties of ThO 2 were studied by heat of immersion calorimetry at 25 to 200 0 C. Results show that the integral heat of immersion of thorium oxide contains contributions which reflect considerable interaction with several layers of water adjacent to the oxide surface. It would be desirable to know the heat capacity changes which occur in the multilayer adsorption of water on an oxide surface. However, such data are not available and their acquisition would be an extremely difficult task. Structuring (a negative ΔCp) of several layers of water (by increased hydrogen bonding) adjacent to an oxide surface could explain an increase in the heat of immersion as the immersion temperature is increased. The more energetic, heterogeneous, high-surface-area samples are expected to induce more order in the adjacent water layers than the less energetic samples. This interpretation is similar to that offered for the temperature dependence of the heat of solution of the alkali halides

Remote Laboratory Experiments in a Virtual Immersive Learning Environment

Directory of Open Access Journals (Sweden)

Luca Berruti

2008-01-01

Full Text Available The Virtual Immersive Learning (VIL test bench implements a virtual collaborative immersive environment, capable of integrating natural contexts and typical gestures, which may occur during traditional lectures, enhanced with advanced experimental sessions. The system architecture is described, along with the motivations, and the most significant choices, both hardware and software, adopted for its implementation. The novelty of the approach essentially relies on its capability of embedding functionalities that stem from various research results (mainly carried out within the VICOM national project, and “putting the pieces together” in a well-integrated framework. These features, along with its high portability, good flexibility, and, above all, low cost, make this approach appropriate for educational and training purposes, mainly concerning measurements on telecommunication systems, at universities and research centers, as well as enterprises. Moreover, the methodology can be employed for remote access to and sharing of costly measurement equipment in many different activities. The immersive characteristics of the framework are illustrated, along with performance measurements related to a specific application.

Immersion Cooling of Electronics in DoD Installations

Energy Technology Data Exchange (ETDEWEB)

Coles, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Herrlin, Magnus [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-08-15

A considerable amount of energy is consumed to cool electronic equipment in data centers. A method for substantially reducing the energy needed for this cooling was demonstrated. The method involves immersing electronic equipment in a non-conductive liquid that changes phase from a liquid to a gas. The liquid used was 3M Novec 649. Two-phase immersion cooling using this liquid is not viable at this time. The primary obstacles are IT equipment failures and costs. However, the demonstrated technology met the performance objectives for energy efficiency and greenhouse gas reduction. Before commercialization of this technology can occur, a root cause analysis of the failures should be completed, and the design changes proven.

A structural equation modeling investigation of the emotional value of immersive virtual reality in education

DEFF Research Database (Denmark)

Makransky, Guido; Lilleholt, Lau

2018-01-01

Virtual reality (VR) is projected to play an important role in education by increasing student engagement and motivation. However, little is known about the impact and utility of immersive VR for administering e-learning tools, or the underlying mechanisms that impact learners’ emotional processes...... consisted of 104 university students (39 females). Significantly higher scores were obtained on 11 of the 13 variables investigated using the immersive VR version of the simulation, with the largest differences occurring with regard to presence and motivation. Furthermore, we identified a model with two...... general paths by which immersion in VR impacts perceived learning outcomes. Specifically, we discovered an affective path in which immersion predicted presence and positive emotions, and a cognitive path in which immersion fostered a positive cognitive value of the task in line with the control value...

Solid-immersion fluorescence microscopy with increased emission and super resolution

Energy Technology Data Exchange (ETDEWEB)

Liau, Z. L.; Porter, J. M. [Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02420 (United States); Liau, A. A.; Chen, J. J. [Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Salmon, W. C. [Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Sheu, S. S. [Department of Medicine, Jefferson Medical College, Philadelphia, Pennsylvania 19107 (United States)

2015-01-07

We investigate solid-immersion fluorescence microscopy suitable for super-resolution nanotechnology and biological imaging, and have observed limit of resolution as small as 15 nm with microspheres, mitochondria, and chromatin fibers. We have further observed that fluorescence efficiency increases with excitation power density, implicating appreciable stimulated emission and increased resolution. We discuss potential advantages of the solid-immersion microscopy, including combined use with previously established super-resolution techniques for reaching deeper beyond the conventional diffraction limit.

Immersion francaise precoce: Arts plastiques 1-7 (Early French Immersion: Plastic Arts for Grades 1-7).

Science.gov (United States)

Burt, Andy; And Others

This curriculum guide in art education is intended for use in grades 1-7 in the early French immersion program. An introductory chapter describes the educational objectives of the art program, the role of art education in child development, general and terminal objectives, methodology, the steps in graphic evolution, and an outline of the program.…

Rotating shell eggs immersed in hot water for the purpose of pasteurization

Science.gov (United States)

Pasteurization of shell eggs for inactivation of Salmonella using hot water immersion can be used to improve their safety. The rotation of a shell egg immersed in hot water has previously been simulated by computational fluid dynamics (CFD); however, experimental data to verify the results do not ex...

Reduced cerebral perfusion on sudden immersion in ice water: a possible cause of drowning

DEFF Research Database (Denmark)

Mantoni, Teit; Belhage, Bo; Pedersen, Lars M

2007-01-01

Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored the immediate changes...... in cerebral blood flow velocity (Vmean) during cold-water immersion since cold shock induced hyperventilation may diminish Vmean and lead to syncope and drowning....

Improving the Effectiveness of Professional Education: Learning Managerial Accounting via a Complex Case.

Science.gov (United States)

Carter, Melissa; And Others

To give students more experience with real situations, many professional schools use case studies in their courses. Creating complex cases, case experiences that immerse students in complex problems, rather than mere case studies that require armchair analysis should help students gain better and more integrated knowledge. Designing, implementing,…

Postexercise cold-water immersion improves intermittent high-intensity exercise performance in normothermia.

Science.gov (United States)

McCarthy, Avina; Mulligan, James; Egaña, Mikel

2016-11-01

A brief cold water immersion between 2 continuous high-intensity exercise bouts improves the performance of the latter compared with passive recovery in the heat. We investigated if this effect is apparent in normothermic conditions (∼19 °C), employing an intermittent high-intensity exercise designed to reflect the work performed at the high-intensity domain in team sports. Fifteen young active men completed 2 exhaustive cycling protocols (Ex1 and Ex2: 12 min at 85% ventilatory threshold (VT) and then an intermittent exercise alternating 30-s at 40% peak power (P peak ) and 30 s at 90% P peak to exhaustion) separated by 15 min of (i) passive rest, (ii) 5-min cold-water immersion at 8 °C, and (iii) 10-min cold-water immersion at 8 °C. Core temperature, heart rate, rates of perceived exertion, and oxygen uptake kinetics were not different during Ex1 among conditions. Time to failure during the intermittent exercise was significantly (P immersions (7.2 ± 3.5 min and 7.3 ± 3.3 min, respectively) compared with passive rest (5.8 ± 3.1 min). Core temperature, heart rate, and rates of perceived exertion were significantly (P immersions compared with passive rest. The time constant of phase II oxygen uptake response during the 85% VT bout of Ex2 was not different among the 3 conditions. A postexercise, 5- to 10-min cold-water immersion increases subsequent intermittent high-intensity exercise compared with passive rest in normothermia due, at least in part, to reductions in core temperature, circulatory strain, and effort perception.

Cold water immersion of the ankle decreases neuromuscular response of lower limb after inversion movement.

Science.gov (United States)

Macedo, Christiane S G; Alonso, Carolina S; Liporaci, Rogério F; Vieira, Fernando; Guirro, Rinaldo R J

2014-01-01

Cryotherapy has been associated with a significant decrease in nerve conduction velocity and muscle contraction with possible effects on exercise and physical training. To quantify the electromyographic response of the lateral gastrocnemius, tibialis anterior, fibularis longus, rectus femoris and gluteus medius to ankle inversion following cold water immersion. The peak values of the root mean square (RMS) were obtained from 35 healthy and active university subjects after the use of a tilt platform to force the ankle into 30° of inversion before, immediately after, and 10, 20, and 30 minutes after water immersion at 4±2°C, for 20 minutes. The Shapiro-Wilk test, repeated measures analysis, Bonferroni's post-hoc, and linear regression analysis provided the results. Peak RMS was significantly lower at all times after cold water immersion, with residual effect of up to 30 minutes, when compared to pre-immersion for all muscles, except for immediate post-immersion for the gluteus medius. After cold water immersion of the ankle, special care should be taken in activities that require greater neuromuscular control.

Position Analysis of a Hybrid Serial-Parallel Manipulator in Immersion Lithography

Directory of Open Access Journals (Sweden)

Jie-jie Shao

2015-01-01

Full Text Available This paper proposes a novel hybrid serial-parallel mechanism with 6 degrees of freedom. The new mechanism combines two different parallel modules in a serial form. 3-P̲(PH parallel module is architecture of 3 degrees of freedom based on higher joints and specializes in describing two planes’ relative pose. 3-P̲SP parallel module is typical architecture which has been widely investigated in recent researches. In this paper, the direct-inverse position problems of the 3-P̲SP parallel module in the couple mixed-type mode are analyzed in detail, and the solutions are obtained in an analytical form. Furthermore, the solutions for the direct and inverse position problems of the novel hybrid serial-parallel mechanism are also derived and obtained in the analytical form. The proposed hybrid serial-parallel mechanism is applied to regulate the immersion hood’s pose in an immersion lithography system. Through measuring and regulating the pose of the immersion hood with respect to the wafer surface simultaneously, the immersion hood can track the wafer surface’s pose in real-time and the gap status is stabilized. This is another exploration to hybrid serial-parallel mechanism’s application.

Representing the atmospheric boundary layer in climate models of intermediate compexity

NARCIS (Netherlands)

Ronda, R.J.; Haarsma, R.J.; Holtslag, A.A.M.

2003-01-01

In this study the role of atmospheric boundary layer schemes in climate models is investigated. Including a boundary layer scheme in an Earth system model of intermediate complexity (EMIC) produces only minor differences in the estimated global distribution of sensible and latent heat fluxes over

Comparative study of c-Fos expression in rat dorsal vagal complex and nucleus ambiguus induced by different durations of restraint water-immersion stress.

Science.gov (United States)

Zhang, Yu-Yu; Cao, Guo-Hong; Zhu, Wen-Xing; Cui, Xi-Yun; Ai, Hong-Bin

2009-06-30

Restraint water-immersion stress (RWIS) of rats induces vagally-mediated gastric dysfunction. The present work explored the effects of different durations of RWIS on neuronal activities of the dorsal vagal complex (DVC) and the nucleus ambiguous (NA) in rats. Male Wistar rats were exposed to RWIS for 0, 30, 60, 120, or 180 min. Then, a c-Fos immunoperoxidase technique was utilized to assess neuronal activation. Resumptively, c-Fos expression in DVC and NA peaked at 60 min of stress, subsequently decreased gradually with increasing durations of RWIS. Interestingly, the most intense c-Fos expression was observed in the dorsal motor nucleus of the vagus (DMV) during the stress, followed by NA, nucleus of solitary tract (NTS) and area postrema (AP). The peak of c-Fos expression in caudal DMV appeared at 120 min of the stress, slower than that in rostral and intermediate DMV. The c-Fos expression in intermediate and caudal NTS was significantly more intense than that in rostral NTS. These results indicate that the neuronal hyperactivity of DMV, NA, NTS and AP, the primary center that control gastric functions, especially DMV and NA, may play an important role in the disorders of gastric motility and secretion induced by RWIS.

Measurement Tools for the Immersive Visualization Environment: Steps Toward the Virtual Laboratory.

Science.gov (United States)

Hagedorn, John G; Dunkers, Joy P; Satterfield, Steven G; Peskin, Adele P; Kelso, John T; Terrill, Judith E

2007-01-01

This paper describes a set of tools for performing measurements of objects in a virtual reality based immersive visualization environment. These tools enable the use of the immersive environment as an instrument for extracting quantitative information from data representations that hitherto had be used solely for qualitative examination. We provide, within the virtual environment, ways for the user to analyze and interact with the quantitative data generated. We describe results generated by these methods to obtain dimensional descriptors of tissue engineered medical products. We regard this toolbox as our first step in the implementation of a virtual measurement laboratory within an immersive visualization environment.

Peary caribou distribution within the Bathurst Island Complex relative to the boundary proposed for Qausuittuq National Park, Nunavut

Directory of Open Access Journals (Sweden)

Kim G. Poole

2015-12-01

Full Text Available How caribou (Rangifer tarandus, including Peary caribou (R. t. pearyi, use their annual ranges varies with changes in abundance. While fidelity to some seasonal ranges is persistent, use of other areas changes. Consequently, understanding changes in seasonal distribution is useful for designing boundaries of protected areas for caribou conservation. A case in point is the proposed Qausuittuq (Northern Bathurst Island National Park for Bathurst Island and its satellite islands in the High Arctic of Canada. Since 1961, Peary caribou have been through three periods of high and low abundance. We examined caribou distribution and composition mapped during nine systematic aerial surveys (1961–2013, unsystematic helicopter surveys (1989–98, and limited radio-collaring from 1994–97 and 2003–06. While migration patterns changed and use of southern Bathurst Island decreased during lows in abundance, use of satellite islands, especially Cameron Island for winter range, persisted during both highs and lows in abundance. The northeast coast of Bathurst Island was used to a greater extent during the rut and during summer at low abundance. We suggest that Park boundaries which include Cameron Island and the northeast coast of Bathurst Island will be more effective in contributing to the persistence of Peary caribou on the Bathurst Island Complex.

A Mesoscale Model-Based Climatography of Nocturnal Boundary-Layer Characteristics over the Complex Terrain of North-Western Utah.

Science.gov (United States)

Serafin, Stefano; De Wekker, Stephan F J; Knievel, Jason C

Nocturnal boundary-layer phenomena in regions of complex topography are extremely diverse and respond to a multiplicity of forcing factors, acting primarily at the mesoscale and microscale. The interaction between different physical processes, e.g., drainage promoted by near-surface cooling and ambient flow over topography in a statically stable environment, may give rise to special flow patterns, uncommon over flat terrain. Here we present a climatography of boundary-layer flows, based on a 2-year archive of simulations from a high-resolution operational mesoscale weather modelling system, 4DWX. The geographical context is Dugway Proving Ground, in north-western Utah, USA, target area of the field campaigns of the MATERHORN (Mountain Terrain Atmospheric Modeling and Observations Program) project. The comparison between model fields and available observations in 2012-2014 shows that the 4DWX model system provides a realistic representation of wind speed and direction in the area, at least in an average sense. Regions displaying strong spatial gradients in the field variables, thought to be responsible for enhanced nocturnal mixing, are typically located in transition areas from mountain sidewalls to adjacent plains. A key dynamical process in this respect is the separation of dynamically accelerated downslope flows from the surface.

Immersive realities: articulating the shift from VR to mobile AR through artistic practice

Science.gov (United States)

Margolis, Todd; Cornish, Tracy; Berry, Rodney; DeFanti, Thomas A.

2012-03-01

Our contemporary imaginings of technological engagement with digital environments has transitioned from flying through Virtual Reality to mobile interactions with the physical world through personal media devices. Experiences technologically mediated through social interactivity within physical environments are now being preferenced over isolated environments such as CAVEs or HMDs. Examples of this trend can be seen in early tele-collaborative artworks which strove to use advanced networking to join multiple participants in shared virtual environments. Recent developments in mobile AR allow untethered access to such shared realities in places far removed from labs and home entertainment environments, and without the bulky and expensive technologies attached to our bodies that accompany most VR. This paper addresses the emerging trend favoring socially immersive artworks via mobile Augmented Reality rather than sensorially immersive Virtual Reality installations. With particular focus on AR as a mobile, locative technology, we will discuss how concepts of immersion and interactivity are evolving with this new medium. Immersion in context of mobile AR can be redefined to describe socially interactive experiences. Having distinctly different sensory, spatial and situational properties, mobile AR offers a new form for remixing elements from traditional virtual reality with physically based social experiences. This type of immersion offers a wide array of potential for mobile AR art forms. We are beginning to see examples of how artists can use mobile AR to create social immersive and interactive experiences.

Scaling-up the biomass production of Cymbopogon citratus L. in temporary immersion system

Directory of Open Access Journals (Sweden)

Elisa Quiala

2014-04-01

Full Text Available Shoot-tips, collected from greenhouse-grown plants of Cymbopogon citratus L. (lemmon grass, were incubated on a semi-solid Murashige and Skoog (MS medium with 30% (w/v sucrose, and supplemented with 0.89 µM 6-benzyladenine (BA. After three weeks of culture shoots were individualized and then inoculated in 10 litres temporary immersion system (TIS containing 3 litres of the same basal MS liquid medium. The effects of three immersion frequency (immersion every 12, 6 and 4 hours on the production of biomass were studied. Three inoculum densities (forty, fifty and sixty shoots/TIS were also tested. The biomass growth was inûuenced by the immersion frequency. The highest proliferation rate (17.3 shoots/explants and the plant length (45.2 cm were obtained in plants immersed every 4 h. Also, the fresh and dry biomass weight (153.4 gFW and 24.8 gDW, respectively were higher in this treatment. The maximum biomass accumulation (185.2 gFW and 35.2 gDW was achieved after 30 days of culture when an inoculum density of 60 explants per TIS was used. For the first time, biomass of C. citratus has been produced in10 litres TIS. These results represent the first step in the scaling-up the biomass production of this medicinal plant in large temporary immersion bioreactors. Key words: automation, biomass growth, lemmon grass medicinal plant, tissue culture

The Multicultural Science Framework: Research on Innovative Two-Way Immersion Science Classrooms.

Science.gov (United States)

Hadi-Tabassum, Samina

2000-01-01

Reviews the different approaches to multicultural science teaching that have emerged in the past decade, focusing on the Spanish-English two-way immersion classroom, which meets the needs of Spanish speakers learning English and introduces students to the idea of collaboration across languages and cultures. Two urban two-way immersion classrooms…

Highly immersive virtual reality laparoscopy simulation: development and future aspects.

Science.gov (United States)

Huber, Tobias; Wunderling, Tom; Paschold, Markus; Lang, Hauke; Kneist, Werner; Hansen, Christian

2018-02-01

Virtual reality (VR) applications with head-mounted displays (HMDs) have had an impact on information and multimedia technologies. The current work aimed to describe the process of developing a highly immersive VR simulation for laparoscopic surgery. We combined a VR laparoscopy simulator (LapSim) and a VR-HMD to create a user-friendly VR simulation scenario. Continuous clinical feedback was an essential aspect of the development process. We created an artificial VR (AVR) scenario by integrating the simulator video output with VR game components of figures and equipment in an operating room. We also created a highly immersive VR surrounding (IVR) by integrating the simulator video output with a [Formula: see text] video of a standard laparoscopy scenario in the department's operating room. Clinical feedback led to optimization of the visualization, synchronization, and resolution of the virtual operating rooms (in both the IVR and the AVR). Preliminary testing results revealed that individuals experienced a high degree of exhilaration and presence, with rare events of motion sickness. The technical performance showed no significant difference compared to that achieved with the standard LapSim. Our results provided a proof of concept for the technical feasibility of an custom highly immersive VR-HMD setup. Future technical research is needed to improve the visualization, immersion, and capability of interacting within the virtual scenario.

Postexercise cold water immersion modulates skeletal muscle PGC-1α mRNA expression in immersed and nonimmersed limbs: evidence of systemic regulation.

Science.gov (United States)

Allan, Robert; Sharples, Adam P; Close, Graeme L; Drust, Barry; Shepherd, Sam O; Dutton, John; Morton, James P; Gregson, Warren

2017-08-01

Mechanisms mediating postexercise cold-induced increases in PGC-1α gene expression in human skeletal muscle are yet to be fully elucidated but may involve local cooling effects on AMPK and p38 MAPK-related signaling and/or increased systemic β-adrenergic stimulation. Therefore, we aimed to examine whether postexercise cold water immersion enhancement of PGC-1α mRNA is mediated through local or systemic mechanisms. Ten subjects completed acute cycling (8 × 5 min at ~80% peak power output) followed by seated-rest (CON) or single-leg cold water immersion (CWI; 10 min, 8°C). Muscle biopsies were obtained preexercise, postexercise, and 3 h postexercise from a single limb in the CON condition but from both limbs in CWI [thereby providing tissue from a CWI and nonimmersed limb (NOT)]. Muscle temperature decreased up to 2 h postexercise following CWI (-5°C) in the immersed limb, with lesser changes observed in CON and NOT (-3°C, P cold induction of PGC-1α mRNA. NEW & NOTEWORTHY We report for the first time that postexercise cold water immersion of one limb also enhances PGC-1α expression in a contralateral, nonimmersed limb. We suggest that increased systemic β-adrenergic stimulation, and not localized cooling per se, exerts regulatory effects on local signaling cascades, thereby modulating PGC-1α expression. Therefore, these data have important implications for research designs that adopt contralateral, nonimmersed limbs as a control condition while also increasing our understanding of the potential mechanisms underpinning cold-mediated PGC-1α responses. Copyright © 2017 the American Physiological Society.

In vitro multiplication of plantain cv. ‘INIVIT PV-2011’ (Musa AAB in Temporary Immersion System

Directory of Open Access Journals (Sweden)

Milagros Basail Pérez

2015-07-01

Full Text Available The work was developed in the laboratory of Plant Biotechnology at Instituto de Investigaciones de Viandas Tropicales (INIVIT with the aim of multiplying the plantain cultivar ‘INIVIT PV-2011’ (Musa AAB in Temporary Immersion Systems (10.0 liters Nalgene bottles. The effect of immersion time (10, 20 and 30 minutes, the frequency of immersion (three, six and eight hours, the volume of culture medium per explant (20, 40, 60 and 80 ml, subculture time (15, 18, 21 and 25 days and the inoculum density explants per bottle (20, 40, 60 and 80 explants / culture flask were determined. The results allowed to establish an immersion time of 10 minutes with a frequency of immersion every three hours, 60 explants per bottle, 60 ml of culture medium and subculture explant at 18 days for multiplying this cultivar. A multiplication coefficient of 8.5 and plant material with suitable characteristics were obtained. Keywords: explants density, immersion frequencies, immersion time, multiplication

Surfaces immersed in Lie algebras associated with elliptic integrals

International Nuclear Information System (INIS)

Grundland, A M; Post, S

2012-01-01

The objective of this work is to adapt the Fokas–Gel’fand immersion formula to ordinary differential equations written in the Lax representation. The formalism of generalized vector fields and their prolongation structure is employed to establish necessary and sufficient conditions for the existence and integration of immersion functions for surfaces in Lie algebras. As an example, a class of second-order, integrable, ordinary differential equations is considered and the most general solutions for the wavefunctions of the linear spectral problem are found. Several explicit examples of surfaces associated with Jacobian and P-Weierstrass elliptic functions are presented. (paper)

On a discrete version of the CP 1 sigma model and surfaces immersed in R3

International Nuclear Information System (INIS)

Grundland, A M; Levi, D; Martina, L

2003-01-01

We present a discretization of the CP 1 sigma model. We show that the discrete CP 1 sigma model is described by a nonlinear partial second-order difference equation with rational nonlinearity. To derive discrete surfaces immersed in three-dimensional Euclidean space a 'complex' lattice is introduced. The so-obtained surfaces are characterized in terms of the quadrilateral cross-ratio of four surface points. In this way we prove that all surfaces associated with the discrete CP 1 sigma model are of constant mean curvature. An explicit example of such discrete surfaces is constructed