Study of weak solutions for parabolic variational inequalities with nonstandard growth conditions.

PubMed

Dong, Yan

2018-01-01

In this paper, we study the degenerate parabolic variational inequality problem in a bounded domain. First, the weak solutions of the variational inequality are defined. Second, the existence and uniqueness of the solutions in the weak sense are proved by using the penalty method and the reduction method.

Chronology of DIC technique based on the fundamental mathematical modeling and dehydration impact.

PubMed

Alias, Norma; Saipol, Hafizah Farhah Saipan; Ghani, Asnida Che Abd

2014-12-01

A chronology of mathematical models for heat and mass transfer equation is proposed for the prediction of moisture and temperature behavior during drying using DIC (Détente Instantanée Contrôlée) or instant controlled pressure drop technique. DIC technique has the potential as most commonly used dehydration method for high impact food value including the nutrition maintenance and the best possible quality for food storage. The model is governed by the regression model, followed by 2D Fick's and Fourier's parabolic equation and 2D elliptic-parabolic equation in a rectangular slice. The models neglect the effect of shrinkage and radiation effects. The simulations of heat and mass transfer equations with parabolic and elliptic-parabolic types through some numerical methods based on finite difference method (FDM) have been illustrated. Intel®Core™2Duo processors with Linux operating system and C programming language have been considered as a computational platform for the simulation. Qualitative and quantitative differences between DIC technique and the conventional drying methods have been shown as a comparative.

Computational methods for internal flows with emphasis on turbomachinery

NASA Technical Reports Server (NTRS)

Mcnally, W. D.; Sockol, P. M.

1981-01-01

Current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are presented. The methods are divided into two classes. The inviscid methods deal specifically with turbomachinery applications. Viscous methods, deal with generalized duct flows as well as flows in turbomachinery passages. Inviscid methods are categorized into the potential, stream function, and Euler aproaches. Viscous methods are treated in terms of parabolic, partially parabolic, and elliptic procedures. Various grids used in association with these procedures are also discussed.

X-ray clusters from a high-resolution hydrodynamic PPM simulation of the cold dark matter universe

NASA Technical Reports Server (NTRS)

Bryan, Greg L.; Cen, Renyue; Norman, Michael L.; Ostriker, Jermemiah P.; Stone, James M.

1994-01-01

A new three-dimensional hydrodynamic code based on the piecewise parabolic method (PPM) is utilized to compute the distribution of hot gas in the standard Cosmic Background Explorer (COBE)-normalized cold dark matter (CDM) universe. Utilizing periodic boundary conditions, a box with size 85 h(exp-1) Mpc, having cell size 0.31 h(exp-1) Mpc, is followed in a simulation with 270(exp 3)=10(exp 7.3) cells. Adopting standard parameters determined from COBE and light-element nucleosynthesis, Sigma(sub 8)=1.05, Omega(sub b)=0.06, we find the X-ray-emitting clusters, compute the luminosity function at several wavelengths, the temperature distribution, and estimated sizes, as well as the evolution of these quantities with redshift. The results, which are compared with those obtained in the preceding paper (Kang et al. 1994a), may be used in conjuction with ROSAT and other observational data sets. Overall, the results of the two computations are qualitatively very similar with regard to the trends of cluster properties, i.e., how the number density, radius, and temeprature depend on luminosity and redshift. The total luminosity from clusters is approximately a factor of 2 higher using the PPM code (as compared to the 'total variation diminishing' (TVD) code used in the previous paper) with the number of bright clusters higher by a similar factor. The primary conclusions of the prior paper, with regard to the power spectrum of the primeval density perturbations, are strengthened: the standard CDM model, normalized to the COBE microwave detection, predicts too many bright X-ray emitting clusters, by a factor probably in excess of 5. The comparison between observations and theoretical predictions for the evolution of cluster properties, luminosity functions, and size and temperature distributions should provide an important discriminator among competing scenarios for the development of structure in the universe.

Discontinuous Galerkin Finite Element Method for Parabolic Problems

NASA Technical Reports Server (NTRS)

Kaneko, Hideaki; Bey, Kim S.; Hou, Gene J. W.

2004-01-01

In this paper, we develop a time and its corresponding spatial discretization scheme, based upon the assumption of a certain weak singularity of parallel ut(t) parallel Lz(omega) = parallel ut parallel2, for the discontinuous Galerkin finite element method for one-dimensional parabolic problems. Optimal convergence rates in both time and spatial variables are obtained. A discussion of automatic time-step control method is also included.

Extending the Utility of the Parabolic Approximation in Medical Ultrasound Using Wide-Angle Diffraction Modeling.

PubMed

Soneson, Joshua E

2017-04-01

Wide-angle parabolic models are commonly used in geophysics and underwater acoustics but have seen little application in medical ultrasound. Here, a wide-angle model for continuous-wave high-intensity ultrasound beams is derived, which approximates the diffraction process more accurately than the commonly used Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation without increasing implementation complexity or computing time. A method for preventing the high spatial frequencies often present in source boundary conditions from corrupting the solution is presented. Simulations of shallowly focused axisymmetric beams using both the wide-angle and standard parabolic models are compared to assess the accuracy with which they model diffraction effects. The wide-angle model proposed here offers improved focusing accuracy and less error throughout the computational domain than the standard parabolic model, offering a facile method for extending the utility of existing KZK codes.

Udzawa-type iterative method with parareal preconditioner for a parabolic optimal control problem

NASA Astrophysics Data System (ADS)

Lapin, A.; Romanenko, A.

2016-11-01

The article deals with the optimal control problem with the parabolic equation as state problem. There are point-wise constraints on the state and control functions. The objective functional involves the observation given in the domain at each moment. The conditions for convergence Udzawa's type iterative method are given. The parareal method to inverse preconditioner is given. The results of calculations are presented.

Performance of Infinitely Wide Parabolic and Inclined Slider Bearings Lubricated with Couple Stress or Magnetic Fluids

NASA Astrophysics Data System (ADS)

Oladeinde, Mobolaji Humphrey; Akpobi, John Ajokpaoghene

2011-10-01

The hydrodynamic and magnetohydrodynamic (MHD) lubrication problem of infinitely wide inclined and parabolic slider bearings is solved numerically using the finite element method. The bearing configurations are discretized into three-node isoparametric quadratic elements. Stiffness integrals obtained from the weak form of the governing equations are solved using Gauss quadrature to obtain a finite number of stiffness matrices. The global system of equations obtained from enforcing nodal continuity of pressure for the bearings are solved using the Gauss-Seidel iterative scheme with a convergence criterion of 10-10. Numerical computations reveal that, when compared for similar profile and couple stress parameters, greater pressure builds up in a parabolic slider compared to an inclined slider, indicating a greater wedge effect in the parabolic slider. The parabolic slider bearing is also shown to develop a greater load capacity when lubricated with magnetic fluids. The superior performance of parabolic slider bearing is more pronounced at greater Hartmann numbers for identical bearing structural parameters. It is also shown that when load carrying capacity is the yardstick for comparison, the parabolic slider bearings are superior to the inclined bearings when lubricated with couple stress or magnetic lubricants.

Influence of Γ-X band mixing on the excited donor in a parabolic quantum well

NASA Astrophysics Data System (ADS)

Raghuvaran, T.; Shanthi, R. Vijaya; D'Reuben, A. Merwyn Jasper; Nithiananthi, P.

2013-06-01

Equally spaced energy levels of Parabolic Quantum Well are perturbed due to the application of hydrostatic pressure. It will modify the electronic and optical behavior of high Potential devices. The variation of excited state donor binding energy due to Γ-X band mixing at critical cross over pressures in a Parabolic GaAs/AlxGa1-x As quantum well has been investigated in the effective mass approximation using variational method.

Alternating direction implicit methods for parabolic equations with a mixed derivative

NASA Technical Reports Server (NTRS)

Beam, R. M.; Warming, R. F.

1980-01-01

Alternating direction implicit (ADI) schemes for two-dimensional parabolic equations with a mixed derivative are constructed by using the class of all A(0)-stable linear two-step methods in conjunction with the method of approximate factorization. The mixed derivative is treated with an explicit two-step method which is compatible with an implicit A(0)-stable method. The parameter space for which the resulting ADI schemes are second-order accurate and unconditionally stable is determined. Some numerical examples are given.

Alternating direction implicit methods for parabolic equations with a mixed derivative

NASA Technical Reports Server (NTRS)

Beam, R. M.; Warming, R. F.

1979-01-01

Alternating direction implicit (ADI) schemes for two-dimensional parabolic equations with a mixed derivative are constructed by using the class of all A sub 0-stable linear two-step methods in conjunction with the method of approximation factorization. The mixed derivative is treated with an explicit two-step method which is compatible with an implicit A sub 0-stable method. The parameter space for which the resulting ADI schemes are second order accurate and unconditionally stable is determined. Some numerical examples are given.

Electric field effect on the second-order nonlinear optical properties of parabolic and semiparabolic quantum wells

NASA Astrophysics Data System (ADS)

Zhang, Li; Xie, Hong-Jing

2003-12-01

By using the compact-density-matrix approach and iterative procedure, a detailed procedure for the calculation of the second-harmonic generation (SHG) susceptibility tensor is given in the electric-field-biased parabolic and semiparabolic quantum wells (QW’s). The simple analytical formula for the SHG susceptibility in the systems is also deduced. By adopting the methods of envelope wave function and displacement harmonic oscillation, the electronic states in parabolic and semi parabolic QW’s with applied electric fields are exactly solved. Numerical results on typical AlxGa1-xAl/GaAs materials show that, for the same effective widths, the SHG susceptibility in semiparabolic QW is larger than that in parabolic QW due to the self-asymmetry of the semiparabolic QW, and the applied electric field can make the SHG susceptibilities in both systems enhance remarkably. Moreover, the SHG susceptibility also sensitively depends on the relaxation rate of the systems.

75 FR 35801 - Notice of Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-23

....05 ppm; grass, hay at 0.05 ppm; and grass, forage at 1.5 ppm. An enforcement method for plants has...; sorghum, stover at 0.35 ppm; grass, hay at 2.5 ppm; and grass, forage at 10 ppm. The analytical method is... on sorghum, grain at 0.2 ppm; grass, hay at 5.0 ppm; and grass, forage at 18 ppm. Since bromoxynil...

Explicit Nonlinear Finite Element Geometric Analysis of Parabolic Leaf Springs under Various Loads

PubMed Central

Kong, Y. S.; Omar, M. Z.; Chua, L. B.; Abdullah, S.

2013-01-01

This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability. PMID:24298209

Explicit nonlinear finite element geometric analysis of parabolic leaf springs under various loads.

PubMed

Kong, Y S; Omar, M Z; Chua, L B; Abdullah, S

2013-01-01

This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability.

On High-Order Upwind Methods for Advection

NASA Technical Reports Server (NTRS)

Huynh, Hung T.

2017-01-01

Scheme III (piecewise linear) and V (piecewise parabolic) of Van Leer are shown to yield identical solutions provided the initial conditions are chosen in an appropriate manner. This result is counter intuitive since it is generally believed that piecewise linear and piecewise parabolic methods cannot produce the same solutions due to their different degrees of approximation. The result also shows a key connection between the approaches of discontinuous and continuous representations.

Treatment of ice cover and other thin elastic layers with the parabolic equation method.

PubMed

Collins, Michael D

2015-03-01

The parabolic equation method is extended to handle problems involving ice cover and other thin elastic layers. Parabolic equation solutions are based on rational approximations that are designed using accuracy constraints to ensure that the propagating modes are handled properly and stability constrains to ensure that the non-propagating modes are annihilated. The non-propagating modes are especially problematic for problems involving thin elastic layers. It is demonstrated that stable results may be obtained for such problems by using rotated rational approximations [Milinazzo, Zala, and Brooke, J. Acoust. Soc. Am. 101, 760-766 (1997)] and generalizations of these approximations. The approach is applied to problems involving ice cover with variable thickness and sediment layers that taper to zero thickness.

Scalable Parallel Computation for Extended MHD Modeling of Fusion Plasmas

NASA Astrophysics Data System (ADS)

Glasser, Alan H.

2008-11-01

Parallel solution of a linear system is scalable if simultaneously doubling the number of dependent variables and the number of processors results in little or no increase in the computation time to solution. Two approaches have this property for parabolic systems: multigrid and domain decomposition. Since extended MHD is primarily a hyperbolic rather than a parabolic system, additional steps must be taken to parabolize the linear system to be solved by such a method. Such physics-based preconditioning (PBP) methods have been pioneered by Chac'on, using finite volumes for spatial discretization, multigrid for solution of the preconditioning equations, and matrix-free Newton-Krylov methods for the accurate solution of the full nonlinear preconditioned equations. The work described here is an extension of these methods using high-order spectral element methods and FETI-DP domain decomposition. Application of PBP to a flux-source representation of the physics equations is discussed. The resulting scalability will be demonstrated for simple wave and for ideal and Hall MHD waves.

On-line monitoring of H2 generation and the HTF degradation in parabolic trough solar thermal power plants: Development of an optical sensor based on an innovative approach

NASA Astrophysics Data System (ADS)

Pagola, Iñigo; Funcia, Ibai; Sánchez, Marcelino; Gil, Javier; González-Vallejo, Victoria; Bedoya, Maxi; Orellana, Guillermo

2017-06-01

The work presented in this paper offers a robust, effective and economically competitive method for online detection and monitoring of the presence of molecular hydrogen in the heat transfer fluids of parabolic trough collector plants. The novel method is based on a specific fluorescent sensor according to the ES2425002 patent ("Method for the detection and quantification of hydrogen in a heat transfer fluid").

A stabilized Runge–Kutta–Legendre method for explicit super-time-stepping of parabolic and mixed equations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Chad D.; Balsara, Dinshaw S.; Aslam, Tariq D.

2014-01-15

Parabolic partial differential equations appear in several physical problems, including problems that have a dominant hyperbolic part coupled to a sub-dominant parabolic component. Explicit methods for their solution are easy to implement but have very restrictive time step constraints. Implicit solution methods can be unconditionally stable but have the disadvantage of being computationally costly or difficult to implement. Super-time-stepping methods for treating parabolic terms in mixed type partial differential equations occupy an intermediate position. In such methods each superstep takes “s” explicit Runge–Kutta-like time-steps to advance the parabolic terms by a time-step that is s{sup 2} times larger than amore » single explicit time-step. The expanded stability is usually obtained by mapping the short recursion relation of the explicit Runge–Kutta scheme to the recursion relation of some well-known, stable polynomial. Prior work has built temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Chebyshev polynomials. Since their stability is based on the boundedness of the Chebyshev polynomials, these methods have been called RKC1 and RKC2. In this work we build temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Legendre polynomials. We call these methods RKL1 and RKL2. The RKL1 method is first-order accurate in time; the RKL2 method is second-order accurate in time. We verify that the newly-designed RKL1 and RKL2 schemes have a very desirable monotonicity preserving property for one-dimensional problems – a solution that is monotone at the beginning of a time step retains that property at the end of that time step. It is shown that RKL1 and RKL2 methods are stable for all values of the diffusion coefficient up to the maximum value. We call this a convex monotonicity preserving property and show by examples that it is very useful in parabolic problems with variable diffusion coefficients. This includes variable coefficient parabolic equations that might give rise to skew symmetric terms. The RKC1 and RKC2 schemes do not share this convex monotonicity preserving property. One-dimensional and two-dimensional von Neumann stability analyses of RKC1, RKC2, RKL1 and RKL2 are also presented, showing that the latter two have some advantages. The paper includes several details to facilitate implementation. A detailed accuracy analysis is presented to show that the methods reach their design accuracies. A stringent set of test problems is also presented. To demonstrate the robustness and versatility of our methods, we show their successful operation on problems involving linear and non-linear heat conduction and viscosity, resistive magnetohydrodynamics, ambipolar diffusion dominated magnetohydrodynamics, level set methods and flux limited radiation diffusion. In a prior paper (Meyer, Balsara and Aslam 2012 [36]) we have also presented an extensive test-suite showing that the RKL2 method works robustly in the presence of shocks in an anisotropically conducting, magnetized plasma.« less

A stabilized Runge-Kutta-Legendre method for explicit super-time-stepping of parabolic and mixed equations

NASA Astrophysics Data System (ADS)

Meyer, Chad D.; Balsara, Dinshaw S.; Aslam, Tariq D.

2014-01-01

Parabolic partial differential equations appear in several physical problems, including problems that have a dominant hyperbolic part coupled to a sub-dominant parabolic component. Explicit methods for their solution are easy to implement but have very restrictive time step constraints. Implicit solution methods can be unconditionally stable but have the disadvantage of being computationally costly or difficult to implement. Super-time-stepping methods for treating parabolic terms in mixed type partial differential equations occupy an intermediate position. In such methods each superstep takes “s” explicit Runge-Kutta-like time-steps to advance the parabolic terms by a time-step that is s2 times larger than a single explicit time-step. The expanded stability is usually obtained by mapping the short recursion relation of the explicit Runge-Kutta scheme to the recursion relation of some well-known, stable polynomial. Prior work has built temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Chebyshev polynomials. Since their stability is based on the boundedness of the Chebyshev polynomials, these methods have been called RKC1 and RKC2. In this work we build temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Legendre polynomials. We call these methods RKL1 and RKL2. The RKL1 method is first-order accurate in time; the RKL2 method is second-order accurate in time. We verify that the newly-designed RKL1 and RKL2 schemes have a very desirable monotonicity preserving property for one-dimensional problems - a solution that is monotone at the beginning of a time step retains that property at the end of that time step. It is shown that RKL1 and RKL2 methods are stable for all values of the diffusion coefficient up to the maximum value. We call this a convex monotonicity preserving property and show by examples that it is very useful in parabolic problems with variable diffusion coefficients. This includes variable coefficient parabolic equations that might give rise to skew symmetric terms. The RKC1 and RKC2 schemes do not share this convex monotonicity preserving property. One-dimensional and two-dimensional von Neumann stability analyses of RKC1, RKC2, RKL1 and RKL2 are also presented, showing that the latter two have some advantages. The paper includes several details to facilitate implementation. A detailed accuracy analysis is presented to show that the methods reach their design accuracies. A stringent set of test problems is also presented. To demonstrate the robustness and versatility of our methods, we show their successful operation on problems involving linear and non-linear heat conduction and viscosity, resistive magnetohydrodynamics, ambipolar diffusion dominated magnetohydrodynamics, level set methods and flux limited radiation diffusion. In a prior paper (Meyer, Balsara and Aslam 2012 [36]) we have also presented an extensive test-suite showing that the RKL2 method works robustly in the presence of shocks in an anisotropically conducting, magnetized plasma.

Application of the Parabolic Approximation to Predict Acoustical Propagation in the Ocean.

ERIC Educational Resources Information Center

McDaniel, Suzanne T.

1979-01-01

A simplified derivation of the parabolic approximation to the acoustical wave equation is presented. Exact solutions to this approximate equation are compared with solutions to the wave equation to demonstrate the applicability of this method to the study of underwater sound propagation. (Author/BB)

Constrained-transport Magnetohydrodynamics with Adaptive Mesh Refinement in CHARM

NASA Astrophysics Data System (ADS)

Miniati, Francesco; Martin, Daniel F.

2011-07-01

We present the implementation of a three-dimensional, second-order accurate Godunov-type algorithm for magnetohydrodynamics (MHD) in the adaptive-mesh-refinement (AMR) cosmological code CHARM. The algorithm is based on the full 12-solve spatially unsplit corner-transport-upwind (CTU) scheme. The fluid quantities are cell-centered and are updated using the piecewise-parabolic method (PPM), while the magnetic field variables are face-centered and are evolved through application of the Stokes theorem on cell edges via a constrained-transport (CT) method. The so-called multidimensional MHD source terms required in the predictor step for high-order accuracy are applied in a simplified form which reduces their complexity in three dimensions without loss of accuracy or robustness. The algorithm is implemented on an AMR framework which requires specific synchronization steps across refinement levels. These include face-centered restriction and prolongation operations and a reflux-curl operation, which maintains a solenoidal magnetic field across refinement boundaries. The code is tested against a large suite of test problems, including convergence tests in smooth flows, shock-tube tests, classical two- and three-dimensional MHD tests, a three-dimensional shock-cloud interaction problem, and the formation of a cluster of galaxies in a fully cosmological context. The magnetic field divergence is shown to remain negligible throughout.

Modeling Pulse Transmission in the Monterey Bay Using Parabolic Equation Methods

DTIC Science & Technology

1991-12-01

Collins 9-13 was chosen for this purpose due its energy conservation scheme , and its ability to efficiently incorporate higher order terms in its...pressure field generated by the PE model into normal modes. Additionally, this process provides increased physical understanding of mode coupling and...separation of variables (i.e. normal modes or fast field), as well as pure numerical schemes such as the parabolic equation methods, can be used. However, as

Approximation Methods for Inverse Problems Governed by Nonlinear Parabolic Systems

DTIC Science & Technology

1999-12-17

We present a rigorous theoretical framework for approximation of nonlinear parabolic systems with delays in the context of inverse least squares...numerical results demonstrating the convergence are given for a model of dioxin uptake and elimination in a distributed liver model that is a special case of the general theoretical framework .

Fast wavelet based algorithms for linear evolution equations

NASA Technical Reports Server (NTRS)

Engquist, Bjorn; Osher, Stanley; Zhong, Sifen

1992-01-01

A class was devised of fast wavelet based algorithms for linear evolution equations whose coefficients are time independent. The method draws on the work of Beylkin, Coifman, and Rokhlin which they applied to general Calderon-Zygmund type integral operators. A modification of their idea is applied to linear hyperbolic and parabolic equations, with spatially varying coefficients. A significant speedup over standard methods is obtained when applied to hyperbolic equations in one space dimension and parabolic equations in multidimensions.

Alignment method for parabolic trough solar concentrators

DOEpatents

Diver, Richard B [Albuquerque, NM

2010-02-23

A Theoretical Overlay Photographic (TOP) alignment method uses the overlay of a theoretical projected image of a perfectly aligned concentrator on a photographic image of the concentrator to align the mirror facets of a parabolic trough solar concentrator. The alignment method is practical and straightforward, and inherently aligns the mirror facets to the receiver. When integrated with clinometer measurements for which gravity and mechanical drag effects have been accounted for and which are made in a manner and location consistent with the alignment method, all of the mirrors on a common drive can be aligned and optimized for any concentrator orientation.

Hybrid LES/RANS Simulation of Transverse Sonic Injection into a Mach 2 Flow

NASA Technical Reports Server (NTRS)

Boles, John A.; Edwards, Jack R.; Baurle, Robert A.

2008-01-01

A computational study of transverse sonic injection of air and helium into a Mach 1.98 cross-flow is presented. A hybrid large-eddy simulation / Reynolds-averaged Navier-Stokes (LES/RANS) turbulence model is used, with the two-equation Menter baseline (Menter-BSL) closure for the RANS part of the flow and a Smagorinsky-type model for the LES part of the flow. A time-dependent blending function, dependent on modeled turbulence variables, is used to shift the closure from RANS to LES. Turbulent structures are initiated and sustained through the use of a recycling / rescaling technique. Two higher-order discretizations, the Piecewise Parabolic Method (PPM) of Colella and Woodward, and the SONIC-A ENO scheme of Suresh and Huyhn are used in the study. The results using the hybrid model show reasonably good agreement with time-averaged Mie scattering data and with experimental surface pressure distributions, even though the penetration of the jet into the cross-flow is slightly over-predicted. The LES/RANS results are used to examine the validity of commonly-used assumptions of constant Schmidt and Prandtl numbers in the intense mixing zone downstream of the injection location.

Unsteady transonic flow analysis for low aspect ratio, pointed wings.

NASA Technical Reports Server (NTRS)

Kimble, K. R.; Ruo, S. Y.; Wu, J. M.; Liu, D. Y.

1973-01-01

Oswatitsch and Keune's parabolic method for steady transonic flow is applied and extended to thin slender wings oscillating in the sonic flow field. The parabolic constant for the wing was determined from the equivalent body of revolution. Laplace transform methods were used to derive the asymptotic equations for pressure coefficient, and the Adams-Sears iterative procedure was employed to solve the equations. A computer program was developed to find the pressure distributions, generalized force coefficients, and stability derivatives for delta, convex, and concave wing planforms.

Effect of non-parabolicity and confinement potential on exciton binding energy in a quantum well

NASA Astrophysics Data System (ADS)

Vignesh, G.; Nithiananthi, P.

2018-04-01

The effect of non-parabolicity(NP) (both conduction and valance band) on the binding energy(EB) of a ground state exciton in GaAs/AlxGa1-xAs single Quantum Well(QW) has been calculated using variational method. Confinement of a light hole(LH-CB1-X) and heavy hole(HH-CB1-X) exciton have been numerically evaluated as a function of well width and barrier heights by imposing three different confinement potentials such as square(SQW), parabolic(PQW) and triangular(TQW). Due to NP effects, EB of exciton is increasedin the narrow well region irrespective of the type of exciton, barrier height and nature of the confinement potentials applied. Non-parabolicity effect is prominent in abrupt(SQW) and linearlyvarying(TQW) confinement potentials. All these effects are attributed to be an inter-play between the Coulombic interaction and NP effects among the subband structures.

Finite element simulation of cracks formation in parabolic flume above fixed service live

NASA Astrophysics Data System (ADS)

Bandurin, M. A.; Volosukhin, V. A.; Mikheev, A. V.; Volosukhin, Y. V.; Bandurina, I. P.

2018-03-01

In the article, digital simulation data on influence of defect different characteristics on cracks formation in a parabolic flume are presented. The finite element method is based on general hypotheses of the theory of elasticity. The studies showed that the values of absolute movements satisfy the standards of design. The results of the digital simulation of stresses and strains for cracks formation in concrete parabolic flumes after long-term service above the fixed service life are described. Stressed and strained state of reinforced concrete bearing elements under different load combinations is considered. Intensive threshold of danger to form longitudinal cracks in reinforced concrete elements is determined.

A numerical method for shock driven multiphase flow with evaporating particles

NASA Astrophysics Data System (ADS)

Dahal, Jeevan; McFarland, Jacob A.

2017-09-01

A numerical method for predicting the interaction of active, phase changing particles in a shock driven flow is presented in this paper. The Particle-in-Cell (PIC) technique was used to couple particles in a Lagrangian coordinate system with a fluid in an Eulerian coordinate system. The Piecewise Parabolic Method (PPM) hydrodynamics solver was used for solving the conservation equations and was modified with mass, momentum, and energy source terms from the particle phase. The method was implemented in the open source hydrodynamics software FLASH, developed at the University of Chicago. A simple validation of the methods is accomplished by comparing velocity and temperature histories from a single particle simulation with the analytical solution. Furthermore, simple single particle parcel simulations were run at two different sizes to study the effect of particle size on vorticity deposition in a shock-driven multiphase instability. Large particles were found to have lower enstrophy production at early times and higher enstrophy dissipation at late times due to the advection of the particle vorticity source term through the carrier gas. A 2D shock-driven instability of a circular perturbation is studied in simulations and compared to previous experimental data as further validation of the numerical methods. The effect of the particle size distribution and particle evaporation is examined further for this case. The results show that larger particles reduce the vorticity deposition, while particle evaporation increases it. It is also shown that for a distribution of particles sizes the vorticity deposition is decreased compared to single particle size case at the mean diameter.

On the parallel solution of parabolic equations

NASA Technical Reports Server (NTRS)

Gallopoulos, E.; Saad, Youcef

1989-01-01

Parallel algorithms for the solution of linear parabolic problems are proposed. The first of these methods is based on using polynomial approximation to the exponential. It does not require solving any linear systems and is highly parallelizable. The two other methods proposed are based on Pade and Chebyshev approximations to the matrix exponential. The parallelization of these methods is achieved by using partial fraction decomposition techniques to solve the resulting systems and thus offers the potential for increased time parallelism in time dependent problems. Experimental results from the Alliant FX/8 and the Cray Y-MP/832 vector multiprocessors are also presented.

Calculation of three dimensional viscous flows in annular cascades using parabolized Navier-Stokes equations

NASA Astrophysics Data System (ADS)

Lawerenz, M.

Numerical algorithms for describing the endwall boundary layers and secondary flows in high turning turbine cascades are described. Partially-parabolic methods which cover three-dimensional viscous flow effects are outlined. Introduction of tip-clearance models and modifications of no-slip conditions without the use of wall functions expand the range of application and improve accuracy. Simultaneous computation of the profile boundary layers by refinement of the mesh size in the circumferential direction makes it possible to describe the boundary layer interaction in the corners formed by the bladings and the endwalls. The partially-parabolic method means that the streamwise elliptic coupling is well represented by the given pressure field and that separation does not occur, but it is not possible to describe the separation of the endwall boundary layer near the leading edge and the horse-shoe vortex there properly.

Volatile chemicals identified in extracts from leaves of Japanese mugwort (Artemisia princeps pamp.).

PubMed

Umano, K; Hagi, Y; Nakahara, K; Shoji, A; Shibamoto, T

2000-08-01

Extracts from leaves of Japanese mugwort (Artemisia princeps Pamp.) were obtained using two methods: steam distillation under reduced pressure followed by dichloromethane extraction (DRP) and simultaneous purging and extraction (SPSE). A total of 192 volatile chemicals were identified in the extracts obtained by both methods using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). They included 47 monoterpenoids (oxygenated monoterpenes), 26 aromatic compounds, 19 aliphatic esters, 18 aliphatic alcohols, 17 monoterpenes (hydrocarbon monoterpenes), 17 sesquiterpenes (hydrocarbon sesquiterpenes), 13 sesquiterpenoids (oxygenated sesquiterpenes), 12 aliphatic aldehydes, 8 aliphatic hydrocarbons, 7 aliphatic ketones, and 9 miscellaneous compounds. The major volatile constituents of the extract by DRP were borneol (10.27 ppm), alpha-thujone (3.49 ppm), artemisia alcohol (2.17 ppm), verbenone (1.85 ppm), yomogi alcohol (1.50 ppm), and germacren-4-ol (1.43 ppm). The major volatile constituents of the extract by SPSE were 1,8-cineole (8.12 ppm), artemisia acetate (4.22 ppm), alpha-thujone (3.20 ppm), beta-caryophyllene (2.39 ppm), bornyl acetate (2.05 ppm), borneol (1.80 ppm), and trans-beta-farnesene (1. 78 ppm).

Two new methods used to simulate the circumferential solar flux density concentrated on the absorber of a parabolic trough solar collector

NASA Astrophysics Data System (ADS)

Guo, Minghuan; Wang, Zhifeng; Sun, Feihu

2016-05-01

The optical efficiencies of a solar trough concentrator are important to the whole thermal performance of the solar collector, and the outer surface of the tube absorber is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated solar flux density distributions on the tube absorber of a parabolic trough solar collector for various sun beam incident angles, with main optical errors considered. Since the solar trough concentrators are linear focusing, it is much of interest to investigate the solar flux density distribution on the cross-section profile of the tube absorber, rather than the flux density distribution along the focal line direction. Although a few integral approaches based on the "solar cone" concept were developed to compute the concentrated flux density for some simple trough concentrator geometries, all those integral approaches needed special integration routines, meanwhile, the optical parameters and geometrical properties of collectors also couldn't be changed conveniently. Flexible Monte Carlo ray trace (MCRT) methods are widely used to simulate the more accurate concentrated flux density distribution for compound parabolic solar trough concentrators, while generally they are quite time consuming. In this paper, we first mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the cross-section flux density on the region of interest of the tube absorber. For BRT, bundles of rays are launched at absorber-surface points of interest, directly go through the glass cover of the absorber, strike on the uniformly sampled mirror segment centers in the close-related surface region of the parabolic reflector, and then direct to the effective solar cone around the incident sun beam direction after the virtual backward reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is supposed to be circular Gaussian type. Then a parabolic trough solar collector of Euro Trough 150 is used as an example object to apply this BRT method. Euro Trough 150 is composed of RP3 mirror facets, with the focal length of 1.71m, aperture width of 5.77m, outer tube diameter of 0.07m. Also to verify the simulated flux density distributions, we establish a modified MCRT method. For this modified MCRT method, the random rays with weighted energy elements are launched in the close-related rectangle region in the aperture plane of the parabolic concentrator and the optical errors are statistically modeled in the stages of forward ray tracing process. Given the same concentrator geometric parameters and optical error values, the simulated results from these two ray tracing methods are in good consistence. The two highlights of this paper are the new optical simulation method, BRT, and figuring out the close-related mirror surface region for BRT and the close-related aperture region for MCRT in advance to effectively simulate the solar flux distribution on the absorber surface of a parabolic trough collector.

Quasilinear parabolic variational inequalities with multi-valued lower-order terms

NASA Astrophysics Data System (ADS)

Carl, Siegfried; Le, Vy K.

2014-10-01

In this paper, we provide an analytical frame work for the following multi-valued parabolic variational inequality in a cylindrical domain : Find and an such that where is some closed and convex subset, A is a time-dependent quasilinear elliptic operator, and the multi-valued function is assumed to be upper semicontinuous only, so that Clarke's generalized gradient is included as a special case. Thus, parabolic variational-hemivariational inequalities are special cases of the problem considered here. The extension of parabolic variational-hemivariational inequalities to the general class of multi-valued problems considered in this paper is not only of disciplinary interest, but is motivated by the need in applications. The main goals are as follows. First, we provide an existence theory for the above-stated problem under coercivity assumptions. Second, in the noncoercive case, we establish an appropriate sub-supersolution method that allows us to get existence, comparison, and enclosure results. Third, the order structure of the solution set enclosed by sub-supersolutions is revealed. In particular, it is shown that the solution set within the sector of sub-supersolutions is a directed set. As an application, a multi-valued parabolic obstacle problem is treated.

Interpolation of unevenly spaced data using a parabolic leapfrog correction method and cubic splines

Treesearch

Julio L. Guardado; William T. Sommers

1977-01-01

The technique proposed allows interpolation of data recorded at unevenly spaced sites to a regular grid or to other sites. Known data are interpolated to an initial guess field grid of unevenly spaced rows and columns by a simple distance weighting procedure. The initial guess field is then adjusted by using a parabolic leapfrog correction and the known data. The final...

Calculation of stability derivatives for slowly oscillating bodies of revolution at Mach 1.0

NASA Technical Reports Server (NTRS)

Ruo, S. Y.; Liu, D. D.

1971-01-01

A parabolic method for steady transonic flow is extended to bodies of revolution oscillating in a sonic flow field. A Laplace transform technique is employed to derive the dipole solution, and the Adams-Sears iterative technique is used in the stability derivative calculation. A computer program is developed to perform the stability derivative calculation for the slowly oscillating cone and parabolic ogive. Inputs for the program are body geometry thickness ratio, acceleration constant, and pitch axis location. Sample calculations were performed for the parabolic ogive and circular cone and results are compared with those obtained by using other techniques and the available experimental data for circular cones.

Transesophageal echocardiographic evaluation of baboons during microgravity induced by parabolic flight

NASA Technical Reports Server (NTRS)

Vernalis, Marina N.; Latham, Ricky D.; Fanton, John W.; Geffney, F. Andrew

1993-01-01

Transthoracic echocardiography (TTE) is a feasible method to noninvasively examine cardiac anatomy during parabolic flight. However, transducer placement on the chest wall is very difficult to maintain during transition to microgravity. In addition, TTE requires the use of low frequency transponders which limit resolution. Transesophical echocardiography (TEE) is an established imaging technique which obtains echocardiographic information from the esophagus. It is a safe procedure and provides higher quality images of cardiac structure than obtained with TTE. This study is designed to determine whether TEE was feasible to perform during parabolic flight and to determine whether acute central volume responses occur in acute transition to zero gravity by direct visualization of the cardiac chambers.

Absorber design for a compound parabolic concentrator collector without transmission loss.

PubMed

Suzuki, A; Kobayashi, S

1994-10-01

A new design method for a compound parabolic concentrator heat collector is described. The conventional design of the ideal compound parabolic concentrator collector has a touching point between a light absorber and the reflectors. This structure is not preferable from the standpoint of conductive heat leakage and thermal stress on reflector materials. On the other hand, if the absorber and the reflectors are separated from each other, the gap between them usually causes optical errors such as light transmission loss or an increase in the reflection number. We discuss the fact that ideal heat collection is possible, in spite of the gap, by introducing the idea of an effective heat concentration ratio.

Effects of acute altered gravity during parabolic flight and/or vestibular loss on cell proliferation in the rat dentate gyrus.

PubMed

Zheng, Yiwen; Gliddon, Catherine M; Aitken, Phillip; Stiles, Lucy; Machado, Marie-Laure; Philoxene, Bruno; Denise, Pierre; Smith, Paul F; Besnard, Stephane

2017-07-27

Both parabolic flight, i.e. a condition of altered gravity, and loss of vestibular function, have been suggested to affect spatial learning and memory, which is known to be influenced by neurogenesis in the hippocampus. In this study we investigated whether short alternated micro- and hyper-gravity stimulations during parabolic flight and/or loss of vestibular function, would alter cell proliferation in the hippocampal dentate gyrus of rats, by measuring the number of bromodeoxyuridine (BrdU)-incorporated cells. Rats were randomly allocated to the following experimental groups: (1) sham transtympanic saline injection only (n=5); (2) bilateral vestibular deafferentation (BVD) by sodium arsanilate transtympanic injection only (n=5); (3) sham treatment and parabolic flight (n=5); (4) BVD and parabolic flight (n=6). Forty-two days following transtympanic injection, the animals were subjected to parabolic flight in an awake restrained condition after habituation. A modified Airbus A300 aircraft was flown on a parabolic path, creating 20s of 1.8G during both climbing and descending and 22s of 0G at the apex of each parabola. The no flight animals were subjected to the same housing for the same duration. Immediately after the parabolic flight or control ground condition, animals were injected with BrdU (300mg/kg, i.p). Twenty-four hs after BrdU injection, rats were sacrificed. BrdU immunolabelling was performed and the number of BrdU +ve cells in the dentate gyrus of the hippocampus was quantified using a modified fractionator method. BVD caused a large and significant reduction in the number of BrdU-positive cells compared to sham animals (P≤0.0001); however, flight and all interactions were non-significant. These results indicate that BVD significantly decreased cell proliferation irrespective of the short exposure to altered/modified gravity. Copyright © 2017 Elsevier B.V. All rights reserved.

UPC BarcelonaTech Platform. Innovative aerobatic parabolic flights for life sciences experiments.

NASA Astrophysics Data System (ADS)

Perez-Poch, Antoni; Gonzalez, Daniel

We present an innovative method of performing parabolic flights with aerobatic single-engine planes. A parabolic platform has been established in Sabadell Airport (Barcelona, Spain) to provide an infraestructure ready to allow Life Sciences reduced gravity experiments to be conducted in parabolic flights. Test flights have demonstrated that up to 8 seconds of reduced gravity can be achieved by using a two-seat CAP10B aircraft, with a gravity range between 0.1 and 0.01g in the three axis. A parabolic flight campaign may be implemented with a significant reduction in budget compared to conventional parabolic flight campaigns, and with a very short time-to-access to the platform. Operational skills and proficiency of the pilot controling the aircraft during the maneuvre, sensitivity to wind gusts, and aircraft balance are the key issues that make a parabola successful. Efforts are focused on improving the total “zero-g” time and the quality of reduced gravity achieved, as well as providing more space for experiments. We report results of test flights that have been conducted in order to optimize the quality and total microgravity time. A computer sofware has been developed and implemented to help the pilot optimize his or her performance. Finally, we summarize the life science experiments that have been conducted in this platform. Specific focus is given to the very successful 'Barcelona ZeroG Challenge', this year in its third edition. This educational contest gives undergraduate and graduate students worldwide the opportunity to design their research within our platform and test it on flight, thus becoming real researchers. We conclude that aerobatic parabolic flights have proven to be a safe, unexpensive and reliable way to conduct life sciences reduced gravity experiments.

Modeling the photocatalytic mineralization in water of commercial formulation of estrogens 17-β estradiol (E2) and nomegestrol acetate in contraceptive pills in a solar powered compound parabolic collector.

PubMed

Colina-Márquez, José; Machuca-Martínez, Fiderman; Li Puma, Gianluca

2015-07-22

Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC) was used to remove commercial estradiol formulations (17-β estradiol and nomegestrol acetate) from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC). In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25) and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir-Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM).

Energy levels of a hydrogenic impurity in a parabolic quantum well with a magnetic field

NASA Astrophysics Data System (ADS)

Zang, J. X.; Rustgi, M. L.

1993-07-01

In this paper, we present a calculation of the energy levels of a hydrogenic impurity (or a hydrogenic atom) at the bottom of a one-dimensional parabolic quantum well with a magnetic field normal to the plane of the well. The finite-basis-set variational method is used to calculate the ground state and the excited states with major quantum number less than or equal to 3. The limit of small radial distance and the limit of great radial distance are considered to choose a set of proper basis functions. The results in the limit that the parabolic parameter α=0 are compared with the data of Rösner et al. [J. Phys. B 17, 29 (1984)]. The comparison shows that the present calculation is quite accurate. It is found that the energy levels increase with increasing parabolic parameter α and increase with increasing normalized magnetic-field strength γ except those levels with magnetic quantum number m<0 at small γ.

(2 + 1)-dimensional bright optical solitons in metamaterials with Kerr, power and parabolic law nonlinearities

NASA Astrophysics Data System (ADS)

Boubir, Badreddine

2018-06-01

In this paper, we investigate the dynamics of bright optical solitons in nonlinear metamaterials governed by a (2 + 1)-dimensional nonlinear Schrödinger equation. Three types of nonlinearities have been considered, Kerr law, power law and parabolic law. We based on the solitary wave ansatz method to find these optical soliton solutions. All necessary parametric conditions for their existence are driven.

Backward semi-linear parabolic equations with time-dependent coefficients and local Lipschitz source

NASA Astrophysics Data System (ADS)

Nho Hào, Dinh; Van Duc, Nguyen; Van Thang, Nguyen

2018-05-01

Let H be a Hilbert space with the inner product and the norm , a positive self-adjoint unbounded time-dependent operator on H and . We establish stability estimates of Hölder type and propose a regularization method with error estimates of Hölder type for the ill-posed backward semi-linear parabolic equation with the source function f satisfying a local Lipschitz condition.

Investigation of a Parabolic Iterative Solver for Three-dimensional Configurations

NASA Technical Reports Server (NTRS)

Nark, Douglas M.; Watson, Willie R.; Mani, Ramani

2007-01-01

A parabolic iterative solution procedure is investigated that seeks to extend the parabolic approximation used within the internal propagation module of the duct noise propagation and radiation code CDUCT-LaRC. The governing convected Helmholtz equation is split into a set of coupled equations governing propagation in the positive and negative directions. The proposed method utilizes an iterative procedure to solve the coupled equations in an attempt to account for possible reflections from internal bifurcations, impedance discontinuities, and duct terminations. A geometry consistent with the NASA Langley Curved Duct Test Rig is considered and the effects of acoustic treatment and non-anechoic termination are included. Two numerical implementations are studied and preliminary results indicate that improved accuracy in predicted amplitude and phase can be obtained for modes at a cut-off ratio of 1.7. Further predictions for modes at a cut-off ratio of 1.1 show improvement in predicted phase at the expense of increased amplitude error. Possible methods of improvement are suggested based on analytic and numerical analysis. It is hoped that coupling the parabolic iterative approach with less efficient, high fidelity finite element approaches will ultimately provide the capability to perform efficient, higher fidelity acoustic calculations within complex 3-D geometries for impedance eduction and noise propagation and radiation predictions.

Ultra-flat SPM-broadened spectra in a highly nonlinear fiber using parabolic pulses formed in a fiber Bragg grating

NASA Astrophysics Data System (ADS)

Parmigiani, Francesca; Finot, Christophe; Mukasa, Kazunori; Ibsen, Morten; Roelens, Michael A.; Petropoulos, Periklis; Richardson, David J.

2006-08-01

We propose a new method for generating flat self-phase modulation (SPM)-broadened spectra based on seeding a highly nonlinear fiber (HNLF) with chirp-free parabolic pulses generated using linear pulse shaping in a superstructured fiber Bragg grating (SSFBG). We show that the use of grating reshaped parabolic pulses allows substantially better performance in terms of the extent of SPM-based spectral broadening and flatness relative to conventional hyperbolic secant (sech) pulses. We demonstrate both numerically and experimentally the generation of SPM-broadened pulses centred at 1542 nm with 92% of the pulse energy remaining within the 29 nm 3 dB spectral bandwidth. Applications in spectra slicing and pulse compression are demonstrated.

Validating a High Performance Liquid Chromatography-Ion Chromatography (HPLC-IC) Method with Conductivity Detection After Chemical Suppression for Water Fluoride Estimation.

PubMed

Bondu, Joseph Dian; Selvakumar, R; Fleming, Jude Joseph

2018-01-01

A variety of methods, including the Ion Selective Electrode (ISE), have been used for estimation of fluoride levels in drinking water. But as these methods suffer many drawbacks, the newer method of IC has replaced many of these methods. The study aimed at (1) validating IC for estimation of fluoride levels in drinking water and (2) to assess drinking water fluoride levels of villages in and around Vellore district using IC. Forty nine paired drinking water samples were measured using ISE and IC method (Metrohm). Water samples from 165 randomly selected villages in and around Vellore district were collected for fluoride estimation over 1 year. Standardization of IC method showed good within run precision, linearity and coefficient of variance with correlation coefficient R 2  = 0.998. The limit of detection was 0.027 ppm and limit of quantification was 0.083 ppm. Among 165 villages, 46.1% of the villages recorded water fluoride levels >1.00 ppm from which 19.4% had levels ranging from 1 to 1.5 ppm, 10.9% had recorded levels 1.5-2 ppm and about 12.7% had levels of 2.0-3.0 ppm. Three percent of villages had more than 3.0 ppm fluoride in the water tested. Most (44.42%) of these villages belonged to Jolarpet taluk with moderate to high (0.86-3.56 ppm) water fluoride levels. Ion Chromatography method has been validated and is therefore a reliable method in assessment of fluoride levels in the drinking water. While the residents of Jolarpet taluk (Vellore distict) are found to be at a high risk of developing dental and skeletal fluorosis.

Solar photo-degradation of a pharmaceutical wastewater effluent in a semi-industrial autonomous plant.

PubMed

Expósito, Antonio J; Durán, Antonio; Monteagudo, José M; Acevedo, Alba

2016-05-01

An industrial wastewater effluent coming from a pharmaceutical laboratory has been treated in a semi-industrial autonomous solar compound parabolic collector (CPC) plant. A photo-Fenton process assisted with ferrioxalate has been used. Up to 79% of TOC can be removed in 2 h depending on initial conditions when treating an aqueous effluent containing up to 400 ppm of initial organic carbon concentration (TOC). An initial ratio of Fe(II)/TOC higher than 0.5 guarantees a high removal. It can be seen that most of TOC removal occurs early in the first hour of reaction. After this time, mineralization was very slow, although H2O2 was still present in solution. Indeed it decomposed to form oxygen in inefficient reactions. It is clear that remaining TOC was mainly due to the presence of acetates which are difficult to degrade. Copyright © 2016 Elsevier Ltd. All rights reserved.

Some remarks on the numerical solution of parabolic partial differential equations

NASA Astrophysics Data System (ADS)

Campagna, R.; Cuomo, S.; Leveque, S.; Toraldo, G.; Giannino, F.; Severino, G.

2017-11-01

Numerous environmental/engineering applications relying upon the theory of diffusion phenomena into chaotic environments have recently stimulated the interest toward the numerical solution of parabolic partial differential equations (PDEs). In the present paper, we outline a formulation of the mathematical problem underlying a quite general diffusion mechanism in the natural environments, and we shortly emphasize some remarks concerning the applicability of the (straightforward) finite difference method. An illustration example is also presented.

Error Rates and Channel Capacities in Multipulse PPM

NASA Technical Reports Server (NTRS)

Hamkins, Jon; Moision, Bruce

2007-01-01

A method of computing channel capacities and error rates in multipulse pulse-position modulation (multipulse PPM) has been developed. The method makes it possible, when designing an optical PPM communication system, to determine whether and under what conditions a given multipulse PPM scheme would be more or less advantageous, relative to other candidate modulation schemes. In conventional M-ary PPM, each symbol is transmitted in a time frame that is divided into M time slots (where M is an integer >1), defining an M-symbol alphabet. A symbol is represented by transmitting a pulse (representing 1) during one of the time slots and no pulse (representing 0 ) during the other M 1 time slots. Multipulse PPM is a generalization of PPM in which pulses are transmitted during two or more of the M time slots.

Incompressible Navier-Stokes and parabolized Navier-Stokes solution procedures and computational techniques

NASA Technical Reports Server (NTRS)

Rubin, S. G.

1982-01-01

Recent developments with finite-difference techniques are emphasized. The quotation marks reflect the fact that any finite discretization procedure can be included in this category. Many so-called finite element collocation and galerkin methods can be reproduced by appropriate forms of the differential equations and discretization formulas. Many of the difficulties encountered in early Navier-Stokes calculations were inherent not only in the choice of the different equations (accuracy), but also in the method of solution or choice of algorithm (convergence and stability, in the manner in which the dependent variables or discretized equations are related (coupling), in the manner that boundary conditions are applied, in the manner that the coordinate mesh is specified (grid generation), and finally, in recognizing that for many high Reynolds number flows not all contributions to the Navier-Stokes equations are necessarily of equal importance (parabolization, preferred direction, pressure interaction, asymptotic and mathematical character). It is these elements that are reviewed. Several Navier-Stokes and parabolized Navier-Stokes formulations are also presented.

Application of an Extended Parabolic Equation to the Calculation of the Mean Field and the Transverse and Longitudinal Mutual Coherence Functions Within Atmospheric Turbulence

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2005-01-01

Solutions are derived for the generalized mutual coherence function (MCF), i.e., the second order moment, of a random wave field propagating through a random medium within the context of the extended parabolic equation. Here, "generalized" connotes the consideration of both the transverse as well as the longitudinal second order moments (with respect to the direction of propagation). Such solutions will afford a comparison between the results of the parabolic equation within the pararaxial approximation and those of the wide-angle extended theory. To this end, a statistical operator method is developed which gives a general equation for an arbitrary spatial statistical moment of the wave field. The generality of the operator method allows one to obtain an expression for the second order field moment in the direction longitudinal to the direction of propagation. Analytical solutions to these equations are derived for the Kolmogorov and Tatarskii spectra of atmospheric permittivity fluctuations within the Markov approximation.

Effect of a third application of toothpastes (1450 and 5000 ppm F), including a 'massage' method on fluoride retention and pH drop in plaque.

PubMed

Nordström, Anna; Birkhed, Dowen

2013-01-01

The aim was to investigate fluoride (F) retention in plaque, saliva and pH drop in plaque using high-F toothpaste (5000 ppm F) or standard toothpaste (1450 ppm F) twice a day or 3-times a day. A method using the toothpaste as a 'lotion' and massaging the buccal surfaces with the fingertip was also evaluated. The investigation had a randomized, single-blinded, cross-over design and 16 subjects participated in six brushing regimes: (1) 5000 ppm F; twice a day, (2) 5000 ppm; 3-times/day, (3) 5000 ppm; twice a day, plus the 'massage' method once a day, (4) 1450 ppm F; twice a day, (5) 1450 ppm; 3-times/day and (6) 1450 ppm; twice a day, plus the 'massage' method once a day. The outcome measure was F retention in plaque, saliva and the plaque-pH change after a sucrose rinse. The highest F concentration was found using high-F toothpaste (No 1-3) and differed significantly from those with 1450 ppm (No 4-6). Brushing with high-F toothpaste 3-times a day (No 2) resulted in a 3.6-times higher F saliva value compared with standard toothpaste twice a day (No 4) (p < 0.001). Increasing the frequency of application, from twice to 3-times a day, increased the F retention in plaque significantly when the two methods for application 3-times a day were pooled (p < 0.05). Brushing with 5000 and 1450 ppm toothpastes twice a day plus the 'massage' once a day resulted in the same F concentration in saliva and plaque as brushing 3-times a day with the same paste. A third application of toothpaste is increasing the F retention and toothpaste as a 'lotion' and massaging the buccal surfaces with the fingertip may be a simple and inexpensive way of delivering F a third time during the day.

[An Analysis of the Controversy on the Psychoprophylaxis Method in the Japanese Medical Journal "Obstetrics and Gynecology," 1954-1957].

PubMed

Fujihara, Satoko; Tsukisawa, Miyoko

2015-06-01

The methods of painless childbirth are generally divided into two kinds: "with drugs" and "without drugs." In Japan, the full-scale initiation of these two types of painless childbirth methods in clinical practice started in the early 1950s. The practice of the psychoprophylaxis method (PPM)--one of the painless childbirth methods "without drugs"--started in 1953. Japanese obstetricians had discussed the practicability of PPM for painless childbirth and had doubted the scientific nature and originality of PPM as a viable method. Therefore, they published a series of articles in the Japanese medical journal "Obstetrics and Gynecology" from 1954 to 1957. Two representative obstetricians developed this controversy. Naotaro KUJI, the director of the Central Maternity Hospital of the Japanese Red Cross Society and the chief practitioner of PPM, emphasized that PPM was a more practical method, considering the Japanese medical legal situation where midwives were prohibited to use drugs. On the other hand, Kakuichi ANDO, the chief professor of the Department of Obstetrics and Gynecology of Keio University and the team leader of the practitioners of painless childbirth "with drugs," doubted the practicability of PPM. In the course of these discussions, both groups of obstetricians gradually came to a consensus to use the concept of "pain relief" in labor, instead of "painless" childbirth. They also agreed to adopt methods "with drugs" and "without drugs," including PPM, according to the presented case.

Growth of vegetative explant Moringa oleifera on different composition of auxin and cytokinin and its synthetic seed germination

NASA Astrophysics Data System (ADS)

Muslihatin, Wirdhatul; Jadid, Nurul; Puspitasari, Ika D.; Safitri, Chusnul E.

2017-06-01

The spread of Moringa oleifera is also rare for seed germination and viability or survival are low, and the lack of vegetative propagation method. The purpose of this study are to determine the effect of auxin and cytokinin on growth vegetative explants Moringa oleifera and its synthetic seed germination. The explants grown on MS medium with sucrose content of 30% and a range of additional hormone. Addition concentration and different types of hormone made in order to know the sensitivity and response explant growth on a variety of media to get a good callus and embryosomatic. The composition of the hormone given is MS + 2.4 D 3 ppm; MS + 2,4D 2 ppm + BAP 2 ppm; MS + NAA + 0.5 ppm kinetin 1 ppm; MS + NAA 1 ppm + kinetin 1 ppm; MS + NAA 1 ppm + 0.5 ppm kinetin. The explants were incubated at a temperature of 18-20 ° C with a photoperiod 16/8. Explants and MS medium is incubated to form embryonic callus. Seeds synthetic made from embryonic callus growing on medium 1 ppm kinetin + NAA 1 ppm with encapsulation method with sodium alginate 2%. Seed synthetic germinated in some kind of medium that medium ms0 solid (M1), ms0 liquid (M2), MS0 semi-solid (M3), MS solid NAA 1ppm + Kinetin 1 ppm (M4), MS liquid NAA 1 ppm + kinetin (M5), and semi-solid MS + NAA 1 ppm kinetin 1 ppm (M6). Synthetic seed viability was observed with the parameters of the fresh weight of synthetic seed, germination percentage and seedling. Chlorophyll content was measured by spectrophotometric method with solvent asseton. Best callus generated in this study are embryonic callus that grew on media NAA 1 ppm + kinetin 1 ppm. Embryonic callus on M6 + NAA 1 ppm kinetin 1 ppm capable of germination with an average weight of callus and sprouts of 40.38 mg. Of the entire amount of a synthetic seed on M6, just 5 seed germinate, so the percentage of germination of seeds is equal to 41.67%. with an average length of sprouts 1 cm with an average total chlorophyll content of 8.66 mg / g.

Dense-array concentrator photovoltaic system using non-imaging dish concentrator and crossed compound parabolic concentrator

NASA Astrophysics Data System (ADS)

Chong, Kok-Keong; Yew, Tiong-Keat; Wong, Chee-Woon; Tan, Ming-Hui; Tan, Woei-Chong; Lai, An-Chow; Lim, Boon-Han; Lau, Sing-Liong; Rahman, Faidz Abdul

2015-04-01

Solar concentrating device plays an important role by making use of optical technology in the design, which can be either reflector or lens to deliver high flux of sunlight onto the Concentrator Photovoltaic (CPV) module receiver ranging from hundreds to thousand suns. To be more competitive compared with fossil fuel, the current CPV systems using Fresnel lens and Parabolic dish as solar concentrator that are widely deployed in United States, Australia and Europe are facing great challenge to produce uniformly focused sunlight on the solar cells as to reduce the cost of electrical power generation. The concept of non-imaging optics is not new, but it has not fully explored by the researchers over the world especially in solving the problem of high concentration solar energy, which application is only limited to be a secondary focusing device or low concentration device using Compound Parabolic Concentrator. With the current advancement in the computer processing power, we has successfully invented the non-imaging dish concentrator (NIDC) using numerical simulation method to replace the current parabolic dish as primary focusing device with high solar concentration ratio (more than 400 suns) and large collective area (from 25 to 125 m2). In this paper, we disclose our research and development on dense array CPV system based on non-imaging optics. The geometry of the NIDC is determined using a special computational method. In addition, an array of secondary concentrators, namely crossed compound parabolic concentrators, is also proposed to further focus the concentrated sunlight by the NIDC onto active area of solar cells of the concentrator photovoltaic receiver. The invention maximizes the absorption of concentrated sunlight for the electric power generation system.

Stability of the parabolic Poincaré bundle

NASA Astrophysics Data System (ADS)

Basu, Suratno; Biswas, Indranil; Dan, Krishanu

Given a compact Riemann surface X and a moduli space Mα(Λ) of parabolic stable bundles on it of fixed determinant of complete parabolic flags, we prove that the Poincaré parabolic bundle on X × Mα(Λ) is parabolic stable with respect to a natural polarization on X × Mα(Λ).

Pre-treating water with non-thermal plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Young I.; Fridman, Alexander; Rabinovich, Alexander

The present invention consists of a method of pre-treatment of adulterated water for distillation, including adulterated water produced during hydraulic fracturing ("fracking") of shale rock during natural gas drilling. In particular, the invention is directed to a method of treating adulterated water, said adulterated water having an initial level of bicarbonate ion in a range of about 250 ppm to about 5000 ppm and an initial level of calcium ion in a range of about 500 ppm to about 50,000 ppm, said method comprising contacting the adulterated water with a non-thermal arc discharge plasma to produce plasma treated water havingmore » a level of bicarbonate ion of less than about 100 ppm. Optionally, the plasma treated water may be further distilled.« less

Scalable explicit implementation of anisotropic diffusion with Runge-Kutta-Legendre super-time stepping

NASA Astrophysics Data System (ADS)

Vaidya, Bhargav; Prasad, Deovrat; Mignone, Andrea; Sharma, Prateek; Rickler, Luca

2017-12-01

An important ingredient in numerical modelling of high temperature magnetized astrophysical plasmas is the anisotropic transport of heat along magnetic field lines from higher to lower temperatures. Magnetohydrodynamics typically involves solving the hyperbolic set of conservation equations along with the induction equation. Incorporating anisotropic thermal conduction requires to also treat parabolic terms arising from the diffusion operator. An explicit treatment of parabolic terms will considerably reduce the simulation time step due to its dependence on the square of the grid resolution (Δx) for stability. Although an implicit scheme relaxes the constraint on stability, it is difficult to distribute efficiently on a parallel architecture. Treating parabolic terms with accelerated super-time-stepping (STS) methods has been discussed in literature, but these methods suffer from poor accuracy (first order in time) and also have difficult-to-choose tuneable stability parameters. In this work, we highlight a second-order (in time) Runge-Kutta-Legendre (RKL) scheme (first described by Meyer, Balsara & Aslam 2012) that is robust, fast and accurate in treating parabolic terms alongside the hyperbolic conversation laws. We demonstrate its superiority over the first-order STS schemes with standard tests and astrophysical applications. We also show that explicit conduction is particularly robust in handling saturated thermal conduction. Parallel scaling of explicit conduction using RKL scheme is demonstrated up to more than 104 processors.

The Extended Parabolic Equation Method and Implication of Results for Atmospheric Millimeter-Wave and Optical Propagation

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2004-01-01

The extended wide-angle parabolic wave equation applied to electromagnetic wave propagation in random media is considered. A general operator equation is derived which gives the statistical moments of an electric field of a propagating wave. This expression is used to obtain the first and second order moments of the wave field and solutions are found that transcend those which incorporate the full paraxial approximation at the outset. Although these equations can be applied to any propagation scenario that satisfies the conditions of application of the extended parabolic wave equation, the example of propagation through atmospheric turbulence is used. It is shown that in the case of atmospheric wave propagation and under the Markov approximation (i.e., the -correlation of the fluctuations in the direction of propagation), the usual parabolic equation in the paraxial approximation is accurate even at millimeter wavelengths. The methodology developed here can be applied to any qualifying situation involving random propagation through turbid or plasma environments that can be represented by a spectral density of permittivity fluctuations.

Analysis of Aircraft Fuels and Related Materials

DTIC Science & Technology

1982-09-01

content by the Karl Fischer method . Each 2040 solvent sample represented a different step in a clean-up procedure conducted by Aero Propulsion...izes a potentiometric titration with alcoholic silver nitrate. This method has a minimum detectability of 1 ppm. It has a re- peatability of 0.1 ppm... Method 163-80, which util- izes a potentiometric titration with alcoholic silver nitrate. This method has a minimum detectability of 1 ppm and has a

Crowned spur gears - Methods for generation and Tooth Contact Analysis. II - Generation of the pinion tooth surface by a surface of revolution

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Handschuh, R. F.; Zhang, J.

1988-01-01

A method for generation of crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc second for the numerical examples). Tooth Contact Analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and the bearing contact.

A modified dodge algorithm for the parabolized Navier-Stokes equations and compressible duct flows

NASA Technical Reports Server (NTRS)

Cooke, C. H.

1981-01-01

A revised version of a split-velocity method for numerical calculation of compressible duct flow was developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front-to-back continuity during the calculation. The (checkerboard) zebra algorithm is applied to solution of the three-dimensional continuity equation in conservative form. A second-order A-stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A checkerboard successive overrelaxation iteration is used to solve the resulting implicit nonlinear systems of finite-difference equations which govern stepwise transition.

Analysis of the stress-deformed condition of the disassembly parabolic antenna

NASA Astrophysics Data System (ADS)

Odinets, M. N.; Kaygorodtseva, N. V.; Krysova, I. V.

2018-01-01

Active development of satellite communications and computer-aided design systems raises the problem of designing parabolic antennas on a new round of development. The aim of the work was to investigate the influence of the design of the mirror of a parabolic antenna on its endurance under wind load. The research task was an automated analysis of the stress-deformed condition of various designs of computer models of a paraboloid mirror (segmented or holistic) at modeling the exploitation conditions. The peculiarity of the research was that the assembly model of the antenna’s mirror was subjected to rigid connections on the contacting surfaces of the segments and only then the finite element grid was generated. The analysis showed the advantage of the design of the demountable antenna, which consists of cyclic segments, in front of the construction of the holistic antenna. Calculation of the stress-deformed condition of the antennas allows us to conclude that dividing the design of the antenna’s mirror on parabolic and cyclic segments increases it strength and rigidity. In the future, this can be used to minimize the mass of antenna and the dimensions of the disassembled antenna. The presented way of modeling a mirror of a parabolic antenna using to the method of the finite-element analysis can be used in the production of antennas.

Exposure assessment of ETBE in gas station workers and gasoline tanker truck drivers.

PubMed

Eitaki, Yoko; Kawai, Toshio; Omae, Kazuyuki

2011-01-01

In order to measure occupational exposure concentrations of ethyl tertiary-butyl ether (ETBE), we developed a diffusive sampling method for monitoring ETBE and performed an ETBE exposure assessment. The applicability of diffusive samplers was examined by exposing the samplers to ETBE vapor in test chambers. The personal exposure levels of workers and airborne concentrations were measured at 4 gas stations. The ETBE sampling rate for the diffusive samplers (VOC-SD, Sigma-Aldrich Japan) was 25.04 ml/min (25°C). Compared with the active sampling method, the diffusive samplers could be used for short-term measurements and in environments containing a mixture of organic solvents. The geometric mean (GM) of TWA-8h ETBE was 0.08 ppm (0.02-0.28 ppm) in 28 gas station workers and 0.04 ppm (0.01-0.21 ppm) in 2 gasoline tanker truck drivers. With regard to ETBE airborne concentrations, the GM was 4.12 ppm (0.93-8.71 ppm) at the handles of hanging pumps but dropped to less than 0.01 ppm (less than 0.01-0.01 ppm) at the side of a public road. The diffusive sampling method can be used for the measurement of occupational ETBE exposure. The threshold limit of TLV-TWA 5 ppm recommended by the ACGIH was not exceeded in any of the workers in this study.

40 CFR Figure C-1 to Subpart C of... - Suggested Format for Reporting Test Results for Methods for SO 2, CO, O 3, NO 2

Code of Federal Regulations, 2011 CFR

2011-07-01

... Results for Methods for SO 2, CO, O 3, NO 2 C Figure C-1 to Subpart C of Part 53 Protection of Environment... Pt. 53, Subpt. C, Fig. C-1 Figure C-1 to Subpart C of Part 53—Suggested Format for Reporting Test... Difference Table C-1 spec. Pass or fail Low 1 ____ ppm 2 to ____ ppm 3 4 5 6 Medium 1 ____ ppm 2 to ____ ppm...

40 CFR Figure C-1 to Subpart C of... - Suggested Format for Reporting Test Results for Methods for SO 2, CO, O 3, NO 2

Code of Federal Regulations, 2014 CFR

2014-07-01

... Results for Methods for SO 2, CO, O 3, NO 2 C Figure C-1 to Subpart C of Part 53 Protection of Environment... Pt. 53, Subpt. C, Fig. C-1 Figure C-1 to Subpart C of Part 53—Suggested Format for Reporting Test... Difference Table C-1 spec. Pass or fail Low 1 ____ ppm 2 to ____ ppm 3 4 5 6 Medium 1 ____ ppm 2 to ____ ppm...

40 CFR Figure C-1 to Subpart C of... - Suggested Format for Reporting Test Results for Methods for SO 2, CO, O 3, NO 2

Code of Federal Regulations, 2012 CFR

2012-07-01

... Results for Methods for SO 2, CO, O 3, NO 2 C Figure C-1 to Subpart C of Part 53 Protection of Environment... Pt. 53, Subpt. C, Fig. C-1 Figure C-1 to Subpart C of Part 53—Suggested Format for Reporting Test... Difference Table C-1 spec. Pass or fail Low 1 ____ ppm 2 to ____ ppm 3 4 5 6 Medium 1 ____ ppm 2 to ____ ppm...

40 CFR Figure C-1 to Subpart C of... - Suggested Format for Reporting Test Results for Methods for SO 2, CO, O 3, NO 2

Code of Federal Regulations, 2010 CFR

2010-07-01

... Results for Methods for SO 2, CO, O 3, NO 2 C Figure C-1 to Subpart C of Part 53 Protection of Environment... Pt. 53, Subpt. C, Fig. C-1 Figure C-1 to Subpart C of Part 53—Suggested Format for Reporting Test... Difference Table C-1 spec. Pass or fail Low 1 ____ ppm 2 to ____ ppm 3 4 5 6 Medium 1 ____ ppm 2 to ____ ppm...

Testing large aspheric surfaces with complementary annular subaperture interferometric method

NASA Astrophysics Data System (ADS)

Hou, Xi; Wu, Fan; Lei, Baiping; Fan, Bin; Chen, Qiang

2008-07-01

Annular subaperture interferometric method has provided an alternative solution to testing rotationally symmetric aspheric surfaces with low cost and flexibility. However, some new challenges, particularly in the motion and algorithm components, appear when applied to large aspheric surfaces with large departure in the practical engineering. Based on our previously reported annular subaperture reconstruction algorithm with Zernike annular polynomials and matrix method, and the experimental results for an approximate 130-mm diameter and f/2 parabolic mirror, an experimental investigation by testing an approximate 302-mm diameter and f/1.7 parabolic mirror with the complementary annular subaperture interferometric method is presented. We have focused on full-aperture reconstruction accuracy, and discuss some error effects and limitations of testing larger aspheric surfaces with the annular subaperture method. Some considerations about testing sector segment with complementary sector subapertures are provided.

Terrain and refractivity effects on non-optical paths

NASA Astrophysics Data System (ADS)

Barrios, Amalia E.

1994-07-01

The split-step parabolic equation (SSPE) has been used extensively to model tropospheric propagation over the sea, but recent efforts have extended this method to propagation over arbitrary terrain. At the Naval Command, Control and Ocean Surveillance Center (NCCOSC), Research, Development, Test and Evaluation Division, a split-step Terrain Parabolic Equation Model (TPEM) has been developed that takes into account variable terrain and range-dependent refractivity profiles. While TPEM has been previously shown to compare favorably with measured data and other existing terrain models, two alternative methods to model radiowave propagation over terrain, implemented within TPEM, will be presented that give a two to ten-fold decrease in execution time. These two methods are also shown to agree well with measured data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diaz, J. I.; Henry, J.; Ramos, A. M.

We prove the approximate controllability of several nonlinear parabolic boundary-value problems by means of two different methods: the first one can be called a Cancellation method and the second one uses the Kakutani fixed-point theorem.

RKKY exchange interaction within the parabolic quantum-well

NASA Astrophysics Data System (ADS)

Baķ, Zygmunt

2001-03-01

Indirect magnetic exchange in a semimagnetic semiconductor heterostructure with the parabolic quantum-well barrier potential is considered. Within the analytical method, we provide the exact derivation of the spatial dependence of the RKKY exchange integral. Using the effective dimensionality approach, we show that the spectral dimensionality of the free electron (hole) system equals four. We prove, that the RKKY exchange integral shows conventional, sign reversal variation with the 2 kF period, however, the envelope function falls off in a manner characteristic to 4D systems.

Multiscale techniques for parabolic equations.

PubMed

Målqvist, Axel; Persson, Anna

2018-01-01

We use the local orthogonal decomposition technique introduced in Målqvist and Peterseim (Math Comput 83(290):2583-2603, 2014) to derive a generalized finite element method for linear and semilinear parabolic equations with spatial multiscale coefficients. We consider nonsmooth initial data and a backward Euler scheme for the temporal discretization. Optimal order convergence rate, depending only on the contrast, but not on the variations of the coefficients, is proven in the [Formula: see text]-norm. We present numerical examples, which confirm our theoretical findings.

Electron transport in electrically biased inverse parabolic double-barrier structure

NASA Astrophysics Data System (ADS)

M, Bati; S, Sakiroglu; I, Sokmen

2016-05-01

A theoretical study of resonant tunneling is carried out for an inverse parabolic double-barrier structure subjected to an external electric field. Tunneling transmission coefficient and density of states are analyzed by using the non-equilibrium Green’s function approach based on the finite difference method. It is found that the resonant peak of the transmission coefficient, being unity for a symmetrical case, reduces under the applied electric field and depends strongly on the variation of the structure parameters.

Synchronization for Optical PPM Signals

NASA Technical Reports Server (NTRS)

Vilnrotter, V. A.

1985-01-01

Method based on statistical properties of weak pulse-positionmodulated (PPM) signal enables synchronization of receiver clock with received-signal time base. Method applies to weak optical M-ary PPM signals, for which there is only one pulse of length Tp transmitted during one of timeslots of length T in each successive interval of M timeslots. Method requires small dead time, Td, at beginning and end of each timeslot, during which pulse amplitude is zero.

Parabolic transformation cloaks for unbounded and bounded cloaking of matter waves

NASA Astrophysics Data System (ADS)

Chang, Yu-Hsuan; Lin, De-Hone

2014-01-01

Parabolic quantum cloaks with unbounded and bounded invisible regions are presented with the method of transformation design. The mass parameters of particles for perfect cloaking are shown to be constant along the parabolic coordinate axes of the cloaking shells. The invisibility performance of the cloaks is inspected from the viewpoints of waves and probability currents. The latter shows the controllable characteristic of a probability current by a quantum cloak. It also provides us with a simpler and more efficient way of exhibiting the performance of a quantum cloak without the solutions of the transformed wave equation. Through quantitative analysis of streamline structures in the cloaking shell, one defines the efficiency of the presented quantum cloak in the situation of oblique incidence. The cloaking models presented here give us more choices for testing and applying quantum cloaking.

Femtosecond parabolic pulse shaping in normally dispersive optical fibers.

PubMed

Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel

2013-07-29

Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented.

Evaluation and optimization of the optical performance of low-concentrating dielectric compound parabolic concentrator using ray-tracing methods.

PubMed

Sarmah, Nabin; Richards, Bryce S; Mallick, Tapas K

2011-07-01

We present a detailed design concept and optical performance evaluation of stationary dielectric asymmetric compound parabolic concentrators (DiACPCs) using ray-tracing methods. Three DiACPC designs, DiACPC-55, DiACPC-66, and DiACPC-77, of acceptance half-angles (0° and 55°), (0° and 66°), and (0° and 77°), respectively, are designed in order to optimize the concentrator for building façade photovoltaic applications in northern latitudes (>55 °N). The dielectric concentrator profiles have been realized via truncation of the complete compound parabolic concentrator profiles to achieve a geometric concentration ratio of 2.82. Ray-tracing simulation results show that all rays entering the designed concentrators within the acceptance half-angle range can be collected without escaping from the parabolic sides and aperture. The maximum optical efficiency of the designed concentrators is found to be 83%, which tends to decrease with the increase in incidence angle. The intensity is found to be distributed at the receiver (solar cell) area in an inhomogeneous pattern for a wide range of incident angles of direct solar irradiance with high-intensity peaks at certain points of the receiver. However, peaks become more intense for the irradiation incident close to the extreme acceptance angles, shifting the peaks to the edge of the receiver. Energy flux distribution at the receiver for diffuse radiation is found to be homogeneous within ±12% with an average intensity of 520 W/m².

40 CFR Figure C-1 to Subpart C of... - Suggested Format for Reporting Test Results for Methods for SO 2, CO, O 3, NO 2

Code of Federal Regulations, 2013 CFR

2013-07-01

... Results for Methods for SO 2, CO, O 3, NO 2 C Figure C-1 to Subpart C of Part 53 Protection of Environment... Pt. 53, Subpt. C, Fig. C-1 Figure C-1 to Subpart C of Part 53—Suggested Format for Reporting Test... Difference Table C-1 spec. Pass or fail Low 1 ____ pPM 2 to ____ pPM 3 4 5 6 Medium 1 ____ pPM 2 to ____ pPM...

Production of reactive species using vacuum ultraviolet photodissociation as a tool for studying their effects in plasma medicine: simulations and measurements

NASA Astrophysics Data System (ADS)

Ono, Ryo; Tokumitsu, Yusuke; Zen, Shungo; Yonemori, Seiya

2014-11-01

We propose a method for producing OH, H, O, O3, and O2(a1Δg) using the vacuum ultraviolet photodissociation of H2O and O2 as a tool for studying the reaction processes of plasma medicine. For photodissociation, an H2O/He or O2/He mixture flowing in a quartz tube is irradiated by a Xe2 or Kr2 excimer lamp. The effluent can be applied to a target. Simulations show that the Xe2 lamp method can produce OH radicals within 0.1-1 ppm in the effluent at 5 mm from a quartz tube nozzle. This is comparable to those produced by a helium atmospheric-pressure plasma jet (He-APPJ) currently used in plasma medicine. The Xe2 lamp method also produces H atoms of, at most, 6 ppm. In contrast, the maximum O densities produced by the Xe2 and Kr2 lamp methods are 0.15 ppm and 2.5 ppm, respectively; these are much lower than those from He-APPJ (several tens of ppm). Both lamp methods can produce ozone at concentrations above 1000 ppm and O2(a1Δg) at tens of ppm. The validity of the simulations is verified by measuring the O3 and OH densities produced by the Xe2 lamp method using ultraviolet absorption and laser-induced fluorescence. The differences between the measured and simulated densities for O3 and OH are 20% and factors of 3-4, respectively.

A hybridized method for computing high-Reynolds-number hypersonic flow about blunt bodies

NASA Technical Reports Server (NTRS)

Weilmuenster, K. J.; Hamilton, H. H., II

1979-01-01

A hybridized method for computing the flow about blunt bodies is presented. In this method the flow field is split into its viscid and inviscid parts. The forebody flow field about a parabolic body is computed. For the viscous solution, the Navier-Stokes equations are solved on orthogonal parabolic coordinates using explicit finite differencing. The inviscid flow is determined by using a Moretti type scheme in which the Euler equations are solved, using explicit finite differences, on a nonorthogonal coordinate system which uses the bow shock as an outer boundary. The two solutions are coupled along a common data line and are marched together in time until a converged solution is obtained. Computed results, when compared with experimental and analytical results, indicate the method works well over a wide range of Reynolds numbers and Mach numbers.

Reliable use of determinants to solve nonlinear structural eigenvalue problems efficiently

NASA Technical Reports Server (NTRS)

Williams, F. W.; Kennedy, D.

1988-01-01

The analytical derivation, numerical implementation, and performance of a multiple-determinant parabolic interpolation method (MDPIM) for use in solving transcendental eigenvalue (critical buckling or undamped free vibration) problems in structural mechanics are presented. The overall bounding, eigenvalue-separation, qualified parabolic interpolation, accuracy-confirmation, and convergence-recovery stages of the MDPIM are described in detail, and the numbers of iterations required to solve sample plane-frame problems using the MDPIM are compared with those for a conventional bisection method and for the Newtonian method of Simpson (1984) in extensive tables. The MDPIM is shown to use 31 percent less computation time than bisection when accuracy of 0.0001 is required, but 62 percent less when accuracy of 10 to the -8th is required; the time savings over the Newtonian method are about 10 percent.

Accurate spectral solutions for the parabolic and elliptic partial differential equations by the ultraspherical tau method

NASA Astrophysics Data System (ADS)

Doha, E. H.; Abd-Elhameed, W. M.

2005-09-01

We present a double ultraspherical spectral methods that allow the efficient approximate solution for the parabolic partial differential equations in a square subject to the most general inhomogeneous mixed boundary conditions. The differential equations with their boundary and initial conditions are reduced to systems of ordinary differential equations for the time-dependent expansion coefficients. These systems are greatly simplified by using tensor matrix algebra, and are solved by using the step-by-step method. Numerical applications of how to use these methods are described. Numerical results obtained compare favorably with those of the analytical solutions. Accurate double ultraspherical spectral approximations for Poisson's and Helmholtz's equations are also noted. Numerical experiments show that spectral approximation based on Chebyshev polynomials of the first kind is not always better than others based on ultraspherical polynomials.

The very good property for parabolic vector bundles over curves

NASA Astrophysics Data System (ADS)

Soibelman, Alexander

2018-06-01

The purpose of this note is to extend Beilinson and Drinfeld's "very good" property to moduli stacks of parabolic vector bundles on curves of genuses g = 0 and g = 1. Beilinson and Drinfeld show that for g > 1 a trivial parabolic structure is sufficient for the moduli stacks to be "very good." We give a sufficient condition on the parabolic structure for this property to hold in the case of nontrivial parabolic structure.

Analysis of band structure, transmission properties, and dispersion behavior of THz wave in one-dimensional parabolic plasma photonic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Askari, Nasim; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir; Mirzaie, Reza

2015-11-15

The photonic band gap of obliquely incident terahertz electromagnetic waves in a one-dimensional plasma photonic crystal is studied. The periodic structure consists of lossless dielectric and inhomogeneous plasma with a parabolic density profile. The dispersion relation and the THz wave transmittance are analyzed based on the electromagnetic equations and transfer matrix method. The dependence of effective plasma frequency and photonic band gap characteristics on dielectric and plasma thickness, plasma density, and incident angle are discussed in detail. A theoretical calculation for effective plasma frequency is presented and compared with numerical results. Results of these two methods are in good agreement.

New method of design of nonimaging concentrators.

PubMed

Miñano, J C; González, J C

1992-06-01

A new method of designing nonimaging concentrators is presented and two new types of concentrators are developed. The first is an aspheric lens, and the second is a lens-mirror combination. A ray tracing of three-dimensional concentrators (with rotational symmetry) is also done, showing that the lens-mirror combination has a total transmission as high as that of the full compound parabolic concentrators, while their depth is much smaller than the classical parabolic mirror-nonimaging concentrator combinations. Another important feature of this concentrator is that the optically active surfaces are not in contact with the receiver, as occurs in other nonimaging concentrators in which the rim of the mirror coincides with the rim of the receiver.

A comparison between GO/aperture-field and physical-optics methods for offset reflectors

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Y.

1984-01-01

Both geometrical optics (GO)/aperture-field and physical-optics (PO) methods are used extensively in the diffraction analysis of offset parabolic and dual reflectors. An analytical/numerical comparative study is performed to demonstrate the limitations of the GO/aperture-field method for accurately predicting the sidelobe and null positions and levels. In particular, it is shown that for offset parabolic reflectors and for feeds located at the focal point, the predicted far-field patterns (amplitude) by the GO/aperture-field method will always be symmetric even in the offset plane. This, of course, is inaccurate for the general case and it is shown that the physical-optics method can result in asymmetric patterns for cases in which the feed is located at the focal point. Representative numerical data are presented and a comparison is made with available measured data.

A fast numerical method for the valuation of American lookback put options

NASA Astrophysics Data System (ADS)

Song, Haiming; Zhang, Qi; Zhang, Ran

2015-10-01

A fast and efficient numerical method is proposed and analyzed for the valuation of American lookback options. American lookback option pricing problem is essentially a two-dimensional unbounded nonlinear parabolic problem. We reformulate it into a two-dimensional parabolic linear complementary problem (LCP) on an unbounded domain. The numeraire transformation and domain truncation technique are employed to convert the two-dimensional unbounded LCP into a one-dimensional bounded one. Furthermore, the variational inequality (VI) form corresponding to the one-dimensional bounded LCP is obtained skillfully by some discussions. The resulting bounded VI is discretized by a finite element method. Meanwhile, the stability of the semi-discrete solution and the symmetric positive definiteness of the full-discrete matrix are established for the bounded VI. The discretized VI related to options is solved by a projection and contraction method. Numerical experiments are conducted to test the performance of the proposed method.

A boundary condition to the Khokhlov-Zabolotskaya equation for modeling strongly focused nonlinear ultrasound fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosnitskiy, P., E-mail: pavrosni@yandex.ru; Yuldashev, P., E-mail: petr@acs366.phys.msu.ru; Khokhlova, V., E-mail: vera@acs366.phys.msu.ru

2015-10-28

An equivalent source model was proposed as a boundary condition to the nonlinear parabolic Khokhlov-Zabolotskaya (KZ) equation to simulate high intensity focused ultrasound (HIFU) fields generated by medical ultrasound transducers with the shape of a spherical shell. The boundary condition was set in the initial plane; the aperture, the focal distance, and the initial pressure of the source were chosen based on the best match of the axial pressure amplitude and phase distributions in the Rayleigh integral analytic solution for a spherical transducer and the linear parabolic approximation solution for the equivalent source. Analytic expressions for the equivalent source parametersmore » were derived. It was shown that the proposed approach allowed us to transfer the boundary condition from the spherical surface to the plane and to achieve a very good match between the linear field solutions of the parabolic and full diffraction models even for highly focused sources with F-number less than unity. The proposed method can be further used to expand the capabilities of the KZ nonlinear parabolic equation for efficient modeling of HIFU fields generated by strongly focused sources.« less

Stationary swarming motion of active Brownian particles in parabolic external potential

NASA Astrophysics Data System (ADS)

Zhu, Wei Qiu; Deng, Mao Lin

2005-08-01

We investigate the stationary swarming motion of active Brownian particles in parabolic external potential and coupled to its mass center. Using Monte Carlo simulation we first show that the mass center approaches to rest after a sufficient long period of time. Thus, all the particles of a swarm have identical stationary motion relative to the mass center. Then the stationary probability density obtained by using the stochastic averaging method for quasi integrable Hamiltonian systems in our previous paper for the motion in 4-dimensional phase space of single active Brownian particle with Rayleigh friction model in parabolic potential is used to describe the relative stationary motion of each particle of the swarm and to obtain more probability densities including that for the total energy of the swarm. The analytical results are confirmed by comparing with those from simulation and also shown to be consistent with the existing deterministic exact steady-state solution.

Low-frequency sound propagation modeling over a locally-reacting boundary using the parabolic approximation

NASA Technical Reports Server (NTRS)

Robertson, J. S.; Siegman, W. L.; Jacobson, M. J.

1989-01-01

There is substantial interest in the analytical and numerical modeling of low-frequency, long-range atmospheric acoustic propagation. Ray-based models, because of frequency limitations, do not always give an adequate prediction of quantities such as sound pressure or intensity levels. However, the parabolic approximation method, widely used in ocean acoustics, and often more accurate than ray models for lower frequencies of interest, can be applied to acoustic propagation in the atmosphere. Modifications of an existing implicit finite-difference implementation for computing solutions to the parabolic approximation are discussed. A locally-reacting boundary is used together with a one-parameter impedance model. Intensity calculations are performed for a number of flow resistivity values in both quiescent and windy atmospheres. Variations in the value of this parameter are shown to have substantial effects on the spatial variation of the acoustic signal.

Development and testing of Parabolic Dish Concentrator No. 1

NASA Technical Reports Server (NTRS)

Dennison, E. W.; Thostesen, T. O.

1984-01-01

Parabolic Dish Concentrator No. 1 (PDC-1) is a 12-m-diameter prototype concentrator with low life-cycle costs for use with thermal-to-electric energy conversion devices. The concentrator assembly features panels made of a resin transfer molded balsa core/fiberglass sandwich with plastic reflective film as the reflective surface and a ribbed framework to hold the panels in place. The concentrator assembly tracks in azimuth and elevation on a base frame riding on a circular track. It is shown that the panels do not exhibit the proper parabolic contour. However, thermal gradients were discovered in the panels with daily temperature changes. The PDC-1 has sufficient optical quality to operate satisfactorily in a dish-electric system. The PDC-1 development provides the impetus for creating innovative optical testing methods and valuable information for use in designing and fabricating concentrators of future dish-electric systems.

Altered osteoblast structure and function in parabolic flight

NASA Astrophysics Data System (ADS)

Zhong-Quan, Dai; Ying-Hui, Li; Fen, Yang; Bai, Ding; Ying-Jun, Tan

Introduction Bone loss has a significant impact on astronauts during spaceflight being one of the main obstacles preventing interplanetary missions However the exact mechanism is not well understood In the present study we investigated the effects of acute gravitational changes generated by parabolic flight on the structure and function of osteoblasts ROS17 2 8 carried by airbus A300 Methods The alteration of microfilament cytoskeleton was observed by the Texas red conjugated Phalloidin and Alexa Fluor 488 conjugated DNase I immunofluorescence stain ALP activity and expression COL1A1 expression osteocalcin secrete which presenting the osteoblast function were detected by modified calcium and cobalt method RT-PCR and radioimmunity methods respectively Results The changed gravity induced the reorganization of microfilament cytoskeleton of osteoblast After 3 hours parabolic flight F-actin of osteoblast cytoskeleton became more thickness and directivity whereas G-actin reduced and relatively concentrated at the edge of nucleus observed by confocal fluorescence microscopy This phenomenon is identical with structure alternation observed in hypergravity but the osteoblast function decrease The excretion of osteocalcin the activity and mRNA expression of ALP decrease but the COL1A1 expression has no changes These results were similar to the changes in simulated or real microgravity Conclusion Above results suggest that short time gravity alternative change induce osteoblast structure and function

The Ubiquitous Parabola

ERIC Educational Resources Information Center

Hyde, Hartley

2008-01-01

Parabolic shapes are easy to find. Many homes outside the cable area have parabolic antennas to receive television transmissions from a satellite far out in space. Parabolic extrusions are used as reflectors behind fluorescent tubes and solar heated water pipes. Parabolic reflectors are used to build solar ovens, searchlights and radio telescopes.…

Production of Monomeric Aromatic Compounds from Oil Palm Empty Fruit Bunch Fiber Lignin by Chemical and Enzymatic Methods.

PubMed

Tang, Pei-Ling; Hassan, Osman; Maskat, Mohamad Yusof; Badri, Khairiah

2015-01-01

In this study, oil palm empty fruit bunch (OPEFBF) was pretreated with alkali, and lignin was extracted for further degradation into lower molecular weight phenolic compounds using enzymes and chemical means. Efficiency of monomeric aromatic compounds production from OPEFBF lignin via chemical (nitrobenzene versus oxygen) and enzymatic [cutinase versus manganese peroxidase (MnP)] approaches was investigated. The effects of sodium hydroxide concentration (2, 5, and 10% wt.) and reaction time (30, 90, and 180 minutes) on the yield of aromatic compounds were studied. The results obtained indicated that nitrobenzene oxidation produced the highest yield (333.17 ± 49.44 ppm hydroxybenzoic acid, 5.67 ± 0.25 ppm p-hydroxybenzaldehyde, 25.57 ± 1.64 ppm vanillic acid, 168.68 ± 23.23 ppm vanillin, 75.44 ± 6.71 ppm syringic acid, 815.26 ± 41.77 ppm syringaldehyde, 15.21 ± 2.19 ppm p-coumaric acid, and 44.75 ± 3.40 ppm ferulic acid), among the tested methods. High sodium hydroxide concentration (10% wt.) was needed to promote efficient nitrobenzene oxidation. However, less severe oxidation condition was preferred to preserve the hydroxycinnamic acids (p-coumaric acid and ferulic acid). Cutinase-catalyzed hydrolysis was found to be more efficient than MnP-catalyzed oxidation in the production of aromatic compounds. By hydrolyzed 8% wt. of lignin with 0.625 mL cutinase g(-1) lignin at pH 8 and 55°C for 24 hours, about 642.83 ± 14.45 ppm hydroxybenzoic acid, 70.19 ± 3.31 ppm syringaldehyde, 22.80 ± 1.04 ppm vanillin, 27.06 ± 1.20 ppm p-coumaric acid, and 50.19 ± 2.23 ppm ferulic acid were produced.

Generation of a crowned pinion tooth surface by a surface of revolution

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Zhang, J.; Handschuh, R. F.

1988-01-01

A method of generating crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc sec for the numerical examples). Tooth contact analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and determine the bearing contact.

3D depth-to-basement and density contrast estimates using gravity and borehole data

NASA Astrophysics Data System (ADS)

Barbosa, V. C.; Martins, C. M.; Silva, J. B.

2009-05-01

We present a gravity inversion method for simultaneously estimating the 3D basement relief of a sedimentary basin and the parameters defining the parabolic decay of the density contrast with depth in a sedimentary pack assuming the prior knowledge about the basement depth at a few points. The sedimentary pack is approximated by a grid of 3D vertical prisms juxtaposed in both horizontal directions, x and y, of a right-handed coordinate system. The prisms' thicknesses represent the depths to the basement and are the parameters to be estimated from the gravity data. To produce stable depth-to-basement estimates we impose smoothness on the basement depths through minimization of the spatial derivatives of the parameters in the x and y directions. To estimate the parameters defining the parabolic decay of the density contrast with depth we mapped a functional containing prior information about the basement depths at a few points. We apply our method to synthetic data from a simulated complex 3D basement relief with two sedimentary sections having distinct parabolic laws describing the density contrast variation with depth. Our method retrieves the true parameters of the parabolic law of density contrast decay with depth and produces good estimates of the basement relief if the number and the distribution of boreholes are sufficient. We also applied our method to real gravity data from the onshore and part of the shallow offshore Almada Basin, on Brazil's northeastern coast. The estimated 3D Almada's basement shows geologic structures that cannot be easily inferred just from the inspection of the gravity anomaly. The estimated Almada relief presents steep borders evidencing the presence of gravity faults. Also, we note the existence of three terraces separating two local subbasins. These geologic features are consistent with Almada's geodynamic origin (the Mesozoic breakup of Gondwana and the opening of the South Atlantic Ocean) and they are important in understanding the basin evolution and in detecting structural oil traps.

Method for inhibiting corrosion in aqueous systems

DOEpatents

DeMonbrun, James R.; Schmitt, Charles R.; Schreyer, James M.

1980-01-01

This invention is a method for inhibiting corrosion in aqueous systems containing components composed of aluminum, copper, iron, or alloys thereof. The method comprises (a) incorporating in the aqueous medium 2-10 ppm by weight of tolyltriazole; an effective amount of a biodegradable organic biocide; 500-1000 ppm by weight of sodium metasilicate; 500-2000 ppm by weight of sodium nitrite; and 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in the system; and (b) maintaining the pH of the resulting system in the range of 7.5 to 8.0. The method permits longterm operation with very low corrosion rates and bacteria counts. All of the additives to the system are biodegradable, permitting the treated aqueous medium to be discharged to the environment without violating current regulations. The method has special application to solar systems in which an aqueous medium is circulated through aluminum-alloy heat exchangers.

Concentrating Solar Power Projects - Chabei 64MW Molten Salt Parabolic

Science.gov Websites

project Status Date: September 29, 2016 Project Overview Project Name: Chabei 64MW Molten Salt Parabolic Technology: Parabolic trough Turbine Capacity: Net: 64.0 MW Gross: 64.0 MW Status: Under development Do you have more information, corrections, or comments? Background Technology: Parabolic trough Status: Under

Convection in Slab and Spheroidal Geometries

NASA Technical Reports Server (NTRS)

Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.

2000-01-01

Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.

Model-based estimation and control for off-axis parabolic mirror alignment

NASA Astrophysics Data System (ADS)

Fang, Joyce; Savransky, Dmitry

2018-02-01

This paper propose an model-based estimation and control method for an off-axis parabolic mirror (OAP) alignment. Current studies in automated optical alignment systems typically require additional wavefront sensors. We propose a self-aligning method using only focal plane images captured by the existing camera. Image processing methods and Karhunen-Loève (K-L) decomposition are used to extract measurements for the observer in closed-loop control system. Our system has linear dynamic in state transition, and a nonlinear mapping from the state to the measurement. An iterative extended Kalman filter (IEKF) is shown to accurately predict the unknown states, and nonlinear observability is discussed. Linear-quadratic regulator (LQR) is applied to correct the misalignments. The method is validated experimentally on the optical bench with a commercial OAP. We conduct 100 tests in the experiment to demonstrate the consistency in between runs.

Impact of post-processing methods on apparent diffusion coefficient values.

PubMed

Zeilinger, Martin Georg; Lell, Michael; Baltzer, Pascal Andreas Thomas; Dörfler, Arnd; Uder, Michael; Dietzel, Matthias

2017-03-01

The apparent diffusion coefficient (ADC) is increasingly used as a quantitative biomarker in oncological imaging. ADC calculation is based on raw diffusion-weighted imaging (DWI) data, and multiple post-processing methods (PPMs) have been proposed for this purpose. We investigated whether PPM has an impact on final ADC values. Sixty-five lesions scanned with a standardized whole-body DWI-protocol at 3 T served as input data (EPI-DWI, b-values: 50, 400 and 800 s/mm 2 ). Using exactly the same ROI coordinates, four different PPM (ADC_1-ADC_4) were executed to calculate corresponding ADC values, given as [10 -3 mm 2 /s] of each lesion. Statistical analysis was performed to intra-individually compare ADC values stratified by PPM (Wilcoxon signed-rank tests: α = 1 %; descriptive statistics; relative difference/∆; coefficient of variation/CV). Stratified by PPM, mean ADCs ranged from 1.136-1.206 *10 -3 mm 2 /s (∆ = 7.0 %). Variances between PPM were pronounced in the upper range of ADC values (maximum: 2.540-2.763 10 -3 mm 2 /s, ∆ = 8 %). Pairwise comparisons identified significant differences between all PPM (P ≤ 0.003; mean CV = 7.2 %) and reached 0.137 *10 -3 mm 2 /s within the 25th-75th percentile. Altering the PPM had a significant impact on the ADC value. This should be considered if ADC values from different post-processing methods are compared in patient studies. • Post-processing methods significantly influenced ADC values. • The mean coefficient of ADC variation due to PPM was 7.2 %. • To achieve reproducible ADC values, standardization of post-processing is recommended.

Comparative efficiency of different methods of gluten extraction in indigenous varieties of wheat.

PubMed

Imran, Samra; Hussain, Zaib; Ghafoor, Farkhanda; Nagra, Saeedahmad; Ziai, Naheeda Ashbeal

2013-06-01

The present study investigated six varieties of locally grown wheat (Lasani, Sehar, Miraj-08, Chakwal-50, Faisalabad-08 and Inqlab) procured from Punjab Seed Corporation, Lahore, Pakistan for their proximate contents. On the basis of protein content and ready availability, Faisalabad-08 (FD-08) was selected to be used for the assessment of comparative efficiency of various methods used for gluten extraction. Three methods, mechanical, chemical and microbiological were used for the extraction of gluten from FD-08. Each method was carried out under ambient conditions using a drying temperature of 55 degrees C. Mechanical method utilized four different processes viz:- dough process, dough batter process, batter process and ethanol washing process using standard 150 mesh. The starch thus obtained was analyzed for its proximate contents. Dough batter process proved to be the most efficient mechanical method and was further investigated using 200 and 300 mesh. Gluten content was determined using sandwich omega-gliadin enzyme-linked immunosorbent assay (ELISA).The results of dough batter process using 200 mesh indicated a starch product with gluten content of 678 ppm. Chemical method indicated high gluten content of more than 5000 ppm and the microbiological method reduced the gluten content from 2500 ppm to 398 ppm. From the results it was observed that no gluten extraction method is viable to produce starch which can fulfill the criteria of a gluten free product (20 ppm).

A modified Dodge algorithm for the parabolized Navier-Stokes equation and compressible duct flows

NASA Technical Reports Server (NTRS)

Cooke, C. H.

1981-01-01

A revised version of Dodge's split-velocity method for numerical calculation of compressible duct flow was developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front-to-back continuity during the calculation. The (checkerboard) zebra algorithm is applied to solution of the three dimensional continuity equation in conservative form. A second-order A-stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A checkerboard iteration is used to solve the resulting implicit nonlinear systems of finite-difference equations which govern stepwise transition. Qualitive agreement with analytical predictions and experimental results was obtained for some flows with well-known solutions.

Fast Multilevel Solvers for a Class of Discrete Fourth Order Parabolic Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Bin; Chen, Luoping; Hu, Xiaozhe

2016-03-05

In this paper, we study fast iterative solvers for the solution of fourth order parabolic equations discretized by mixed finite element methods. We propose to use consistent mass matrix in the discretization and use lumped mass matrix to construct efficient preconditioners. We provide eigenvalue analysis for the preconditioned system and estimate the convergence rate of the preconditioned GMRes method. Furthermore, we show that these preconditioners only need to be solved inexactly by optimal multigrid algorithms. Our numerical examples indicate that the proposed preconditioners are very efficient and robust with respect to both discretization parameters and diffusion coefficients. We also investigatemore » the performance of multigrid algorithms with either collective smoothers or distributive smoothers when solving the preconditioner systems.« less

High Energy Laser Beam Propagation in the Atmosphere: The Integral Invariants of the Nonlinear Parabolic Equation and the Method of Moments

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2012-01-01

The method of moments is used to define and derive expressions for laser beam deflection and beam radius broadening for high-energy propagation through the Earth s atmosphere. These expressions are augmented with the integral invariants of the corresponding nonlinear parabolic equation that describes the electric field of high-energy laser beam to propagation to yield universal equations for the aforementioned quantities; the beam deflection is a linear function of the propagation distance whereas the beam broadening is a quadratic function of distance. The coefficients of these expressions are then derived from a thin screen approximation solution of the nonlinear parabolic equation to give corresponding analytical expressions for a target located outside the Earth s atmospheric layer. These equations, which are graphically presented for a host of propagation scenarios, as well as the thin screen model, are easily amenable to the phase expansions of the wave front for the specification and design of adaptive optics algorithms to correct for the inherent phase aberrations. This work finds application in, for example, the analysis of beamed energy propulsion for space-based vehicles.

Calcium dependent current recordings in Xenopus laevis oocytes in microgravity

NASA Astrophysics Data System (ADS)

Wuest, Simon L.; Roesch, Christian; Ille, Fabian; Egli, Marcel

2017-12-01

Mechanical unloading by microgravity (or weightlessness) conditions triggers profound adaptation processes at the cellular and organ levels. Among other mechanisms, mechanosensitive ion channels are thought to play a key role in allowing cells to transduce mechanical forces. Previous experiments performed under microgravity have shown that gravity affects the gating properties of ion channels. Here, a method is described to record a calcium-dependent current in native Xenopus laevis oocytes under microgravity conditions during a parabolic flight. A 3-voltage-step protocol was applied to provoke a calcium-dependent current. This current increased with extracellular calcium concentration and could be reduced by applying extracellular gadolinium. The custom-made ;OoClamp; hardware was validated by comparing the results of the 3-voltage-step protocol to results obtained with a well-established two-electrode voltage clamp (TEVC). In the context of the 2nd Swiss Parabolic Flight Campaign, we tested the OoClamp and the method. The setup and experiment protocol worked well in parabolic flight. A tendency that the calcium-dependent current was smaller under microgravity than under 1 g condition could be observed. However, a conclusive statement was not possible due to the small size of the data base that could be gathered.

Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations.

PubMed

Kim, Kyunghan; Guo, Zhixiong

2007-05-01

A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent.

Krylov Deferred Correction Accelerated Method of Lines Transpose for Parabolic Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Jun; Jingfang, Huang

2008-01-01

In this paper, a new class of numerical methods for the accurate and efficient solutions of parabolic partial differential equations is presented. Unlike traditional method of lines (MoL), the new {\\bf \\it Krylov deferred correction (KDC) accelerated method of lines transpose (MoL^T)} first discretizes the temporal direction using Gaussian type nodes and spectral integration, and symbolically applies low-order time marching schemes to form a preconditioned elliptic system, which is then solved iteratively using Newton-Krylov techniques such as Newton-GMRES or Newton-BiCGStab method. Each function evaluation in the Newton-Krylov method is simply one low-order time-stepping approximation of the error by solving amore » decoupled system using available fast elliptic equation solvers. Preliminary numerical experiments show that the KDC accelerated MoL^T technique is unconditionally stable, can be spectrally accurate in both temporal and spatial directions, and allows optimal time-step sizes in long-time simulations.« less

An Operator Method for Field Moments from the Extended Parabolic Wave Equation and Analytical Solutions of the First and Second Moments for Atmospheric Electromagnetic Wave Propagation

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2004-01-01

The extended wide-angle parabolic wave equation applied to electromagnetic wave propagation in random media is considered. A general operator equation is derived which gives the statistical moments of an electric field of a propagating wave. This expression is used to obtain the first and second order moments of the wave field and solutions are found that transcend those which incorporate the full paraxial approximation at the outset. Although these equations can be applied to any propagation scenario that satisfies the conditions of application of the extended parabolic wave equation, the example of propagation through atmospheric turbulence is used. It is shown that in the case of atmospheric wave propagation and under the Markov approximation (i.e., the delta-correlation of the fluctuations in the direction of propagation), the usual parabolic equation in the paraxial approximation is accurate even at millimeter wavelengths. The comprehensive operator solution also allows one to obtain expressions for the longitudinal (generalized) second order moment. This is also considered and the solution for the atmospheric case is obtained and discussed. The methodology developed here can be applied to any qualifying situation involving random propagation through turbid or plasma environments that can be represented by a spectral density of permittivity fluctuations.

Modeling of ultrashort pulsed laser irradiation in the cornea based on parabolic and hyperbolic heat equations using electrical analogy

NASA Astrophysics Data System (ADS)

Gheitaghy, A. M.; Takabi, B.; Alizadeh, M.

2014-03-01

Hyperbolic and parabolic heat equations are formulated to study a nonperfused homogeneous transparent cornea irradiated by high power and ultrashort pulsed laser in the Laser Thermo Keratoplasty (LTK) surgery. Energy absorption inside the cornea is modeled using the Beer-Lambert law that is incorporated as an exponentially decaying heat source. The hyperbolic and parabolic bioheat models of the tissue were solved by exploiting the mathematical analogy between thermal and electrical systems, by using robust circuit simulation program called Hspice to get the solutions of simultaneous RLC and RC transmission line networks. This method can be used to rapidly calculate the temperature in laser-irradiated tissue at time and space domain. It is found that internal energy gained from the irradiated field results in a rapid rise of temperature in the cornea surface during the early heating period, while the hyperbolic wave model predicts a higher temperature rise than the classical heat diffusion model. In addition, this paper investigates and examines the effect of some critical parameters such as relaxation time, convection coefficient, radiation, tear evaporation and variable thermal conductivity of cornea. Accordingly, it is found that a better accordance between hyperbolic and parabolic models will be achieved by time.

Coating compositions and method for the treatment of metal surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, N.; Stastny, P.M.

1984-09-11

An aqeuous acidic composition provides improved coating for aluminum. The composition comprises from about 10 to about 150 ppm zirconium, from about 20 to about 250 ppm fluoride, from 30 to about 125 ppm tannin, from about about 15 to about 100 ppm phosphate and from about 5 to about 50 ppm zinc, said coating solution having a tannin to phosphate ratio in the range of at least about 1:1 to about 2:1 and a pH in the range of about 2.3 to about 2.95.

Spectral collocation methods

NASA Technical Reports Server (NTRS)

Hussaini, M. Y.; Kopriva, D. A.; Patera, A. T.

1987-01-01

This review covers the theory and application of spectral collocation methods. Section 1 describes the fundamentals, and summarizes results pertaining to spectral approximations of functions. Some stability and convergence results are presented for simple elliptic, parabolic, and hyperbolic equations. Applications of these methods to fluid dynamics problems are discussed in Section 2.

Noniterative three-dimensional grid generation using parabolic partial differential equations

NASA Technical Reports Server (NTRS)

Edwards, T. A.

1985-01-01

A new algorithm for generating three-dimensional grids has been developed and implemented which numerically solves a parabolic partial differential equation (PDE). The solution procedure marches outward in two coordinate directions, and requires inversion of a scalar tridiagonal system in the third. Source terms have been introduced to control the spacing and angle of grid lines near the grid boundaries, and to control the outer boundary point distribution. The method has been found to generate grids about 100 times faster than comparable grids generated via solution of elliptic PDEs, and produces smooth grids for finite-difference flow calculations.

Optical design with Wood lenses

NASA Astrophysics Data System (ADS)

Caldwell, J. Brian

1991-01-01

Spherical aberration in a flat surfaced radial gradient-index lens (a Wood lens) with a parabolic index profile can be corrected by altering the profile to Include higher order terms. However this results in a large amowfl of third order coma. This paper presents an alternative method of aberration correction similar to that used in the catadiopthc Schmidtsystem. A Wood lens with a parabolic profile is used to provide all or most of the optical power. Coma is corrected by stop shifting and Spherical aberration is corrected by placing a powerless Wood lens corrector plate at the stop. 1.

Production of Monomeric Aromatic Compounds from Oil Palm Empty Fruit Bunch Fiber Lignin by Chemical and Enzymatic Methods

PubMed Central

Tang, Pei-Ling; Hassan, Osman; Maskat, Mohamad Yusof; Badri, Khairiah

2015-01-01

In this study, oil palm empty fruit bunch (OPEFBF) was pretreated with alkali, and lignin was extracted for further degradation into lower molecular weight phenolic compounds using enzymes and chemical means. Efficiency of monomeric aromatic compounds production from OPEFBF lignin via chemical (nitrobenzene versus oxygen) and enzymatic [cutinase versus manganese peroxidase (MnP)] approaches was investigated. The effects of sodium hydroxide concentration (2, 5, and 10% wt.) and reaction time (30, 90, and 180 minutes) on the yield of aromatic compounds were studied. The results obtained indicated that nitrobenzene oxidation produced the highest yield (333.17 ± 49.44 ppm hydroxybenzoic acid, 5.67 ± 0.25 ppm p-hydroxybenzaldehyde, 25.57 ± 1.64 ppm vanillic acid, 168.68 ± 23.23 ppm vanillin, 75.44 ± 6.71 ppm syringic acid, 815.26 ± 41.77 ppm syringaldehyde, 15.21 ± 2.19 ppm p-coumaric acid, and 44.75 ± 3.40 ppm ferulic acid), among the tested methods. High sodium hydroxide concentration (10% wt.) was needed to promote efficient nitrobenzene oxidation. However, less severe oxidation condition was preferred to preserve the hydroxycinnamic acids (p-coumaric acid and ferulic acid). Cutinase-catalyzed hydrolysis was found to be more efficient than MnP-catalyzed oxidation in the production of aromatic compounds. By hydrolyzed 8% wt. of lignin with 0.625 mL cutinase g−1 lignin at pH 8 and 55°C for 24 hours, about 642.83 ± 14.45 ppm hydroxybenzoic acid, 70.19 ± 3.31 ppm syringaldehyde, 22.80 ± 1.04 ppm vanillin, 27.06 ± 1.20 ppm p-coumaric acid, and 50.19 ± 2.23 ppm ferulic acid were produced. PMID:26798644

Parabolic Flight Evaluation of Bacterial Adhesion on Multiple Antimicrobial Surface Treatments

NASA Technical Reports Server (NTRS)

Birmele, Michele

2011-01-01

This report describes the development of a test method and the evaluation of the effectiveness of antimicrobial technologies in reduced gravity based on parabolic flight experiments. Microbial growth is a common occurrence on fully immersed wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and/or physical \\disinfection. Many materials and surface treatments with antimicrobial properties are commercially available but none have been vetted for spaceflight applications. Herein a test method is explained that included ground and reduced gravity parabolic flight experiments with a standard microorganism recovered from spacecraft, Pseudomonas aeruginosa, added at a concentration of 1 x 10(exp 5) cells per milliliter (mL) onto challenge material coupon surfaces. Several experimental materials were observed to slightly reduce microbial attachment in reduced gravity flight experiments, but none were capable of eliminating all challenge bacteria. Lunar gravity had an increased antimicrobial effect in 28 out of 36 test coupons compared to microgravity when provided otherwise identical conditions for growth, suggesting trace .amounts of gravity may be required for maximum antimicrobial performance. Bacterial cells exposed to variable gravity had more than twice as ,much intracellular adenosine triphosphate (ATP) when compared to control cells exposed only to Earth gravity due to a short duration response to environmental stress. An ATP luminescence assay was the method most amenable to development of an in-flight microbial monitoring assay

Composite isogrid structures for parabolic surfaces

NASA Technical Reports Server (NTRS)

Silverman, Edward M. (Inventor); Boyd, Jr., William E. (Inventor); Rhodes, Marvin D. (Inventor); Dyer, Jack E. (Inventor)

2000-01-01

The invention relates to high stiffness parabolic structures utilizing integral reinforced grids. The parabolic structures implement the use of isogrid structures which incorporate unique and efficient orthotropic patterns for efficient stiffness and structural stability.

Non-Parabolic Hydrodynamic Formulations for the Simulation of Inhomogeneous Semiconductor Devices

NASA Technical Reports Server (NTRS)

Smith, A. W.; Brennan, K. F.

1996-01-01

Hydrodynamic models are becoming prevalent design tools for small scale devices and other devices in which high energy effects can dominate transport. Most current hydrodynamic models use a parabolic band approximation to obtain fairly simple conservation equations. Interest in accounting for band structure effects in hydrodynamic device simulation has begun to grow since parabolic models cannot fully describe the transport in state of the art devices due to the distribution populating non-parabolic states within the band. This paper presents two different non-parabolic formulations or the hydrodynamic model suitable for the simulation of inhomogeneous semiconductor devices. The first formulation uses the Kane dispersion relationship ((hk)(exp 2)/2m = W(1 + alphaW). The second formulation makes use of a power law ((hk)(exp 2)/2m = xW(exp y)) for the dispersion relation. Hydrodynamic models which use the first formulation rely on the binomial expansion to obtain moment equations with closed form coefficients. This limits the energy range over which the model is valid. The power law formulation readily produces closed form coefficients similar to those obtained using the parabolic band approximation. However, the fitting parameters (x,y) are only valid over a limited energy range. The physical significance of the band non-parabolicity is discussed as well as the advantages/disadvantages and approximations of the two non-parabolic models. A companion paper describes device simulations based on the three dispersion relationships; parabolic, Kane dispersion and power law dispersion.

Non-parabolic hydrodynamic formulations for the simulation of inhomogeneous semiconductor devices

NASA Technical Reports Server (NTRS)

Smith, Arlynn W.; Brennan, Kevin F.

1995-01-01

Hydrodynamic models are becoming prevalent design tools for small scale devices and other devices in which high energy effects can dominate transport. Most current hydrodynamic models use a parabolic band approximation to obtain fairly simple conservation equations. Interest in accounting for band structure effects in hydrodynamic device simulation has begun to grow since parabolic models can not fully describe the transport in state of the art devices due to the distribution populating non-parabolic states within the band. This paper presents two different non-parabolic formulations of the hydrodynamic model suitable for the simulation of inhomogeneous semiconductor devices. The first formulation uses the Kane dispersion relationship (hk)(exp 2)/2m = W(1 + alpha(W)). The second formulation makes use of a power law ((hk)(exp 2)/2m = xW(sup y)) for the dispersion relation. Hydrodynamic models which use the first formulation rely on the binomial expansion to obtain moment equations with closed form coefficients. This limits the energy range over which the model is valid. The power law formulation readily produces closed form coefficients similar to those obtained using the parabolic band approximation. However, the fitting parameters (x,y) are only valid over a limited energy range. The physical significance of the band non-parabolicity is discussed as well as the advantages/disadvantages and approximations of the two non-parabolic models. A companion paper describes device simulations based on the three dispersion relationships: parabolic, Kane dispersion, and power low dispersion.

75 FR 5790 - Notice of Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-04

... on banana at 0.05 parts per million (ppm). An adequate, validated method (GRM006.01B) is available... insecticide fluazifop-p-butyl, in or on potato, tuber at 1.1 ppm; potato, peel (wet) at 1.1 ppm; potato, chips...

AN EXPERIMENTAL EVALUATION OF THREE METHODS FOR INCREASING THE LEADING EDGE THICKNESS OF SUPERCAVITATING PROPELLERS.

DTIC Science & Technology

An experimental investigation of three methods of increasing the leading-edge thickness of supercavitating propeller sections was conducted. The...addition of a parabolic thickness to both the face and back of the section. Five supercavitating propeller models incorporating these three methods of

Comparison of Non-Parabolic Hydrodynamic Simulations for Semiconductor Devices

NASA Technical Reports Server (NTRS)

Smith, A. W.; Brennan, K. F.

1996-01-01

Parabolic drift-diffusion simulators are common engineering level design tools for semiconductor devices. Hydrodynamic simulators, based on the parabolic band approximation, are becoming more prevalent as device dimensions shrink and energy transport effects begin to dominate device characteristic. However, band structure effects present in state-of-the-art devices necessitate relaxing the parabolic band approximation. This paper presents simulations of ballistic diodes, a benchmark device, of Si and GaAs using two different non-parabolic hydrodynamic formulations. The first formulation uses the Kane dispersion relationship in the derivation of the conservation equations. The second model uses a power law dispersion relation {(hk)(exp 2)/2m = xW(exp Y)}. Current-voltage relations show that for the ballistic diodes considered. the non-parabolic formulations predict less current than the parabolic case. Explanations of this will be provided by examination of velocity and energy profiles. At low bias, the simulations based on the Kane formulation predict greater current flow than the power law formulation. As the bias is increased this trend changes and the power law predicts greater current than the Kane formulation. It will be shown that the non-parabolicity and energy range of the hydrodynamic model based on the Kane dispersion relation are limited due to the binomial approximation which was utilized in the derivation.

Application of the implicit MacCormack scheme to the PNS equations

NASA Technical Reports Server (NTRS)

Lawrence, S. L.; Tannehill, J. C.; Chaussee, D. S.

1983-01-01

The two-dimensional parabolized Navier-Stokes equations are solved using MacCormack's (1981) implicit finite-difference scheme. It is shown that this method for solving the parabolized Navier-Stokes equations does not require the inversion of block tridiagonal systems of algebraic equations and allows the original explicit scheme to be employed in those regions where implicit treatment is not needed. The finite-difference algorithm is discussed and the computational results for two laminar test cases are presented. Results obtained using this method for the case of a flat plate boundary layer are compared with those obtained using the conventional Beam-Warming scheme, as well as those obtained from a boundary layer code. The computed results for a more severe test of the method, the hypersonic flow past a 15 deg compression corner, are found to compare favorably with experiment and a numerical solution of the complete Navier-Stokes equations.

Higher order turbulence closure models

NASA Technical Reports Server (NTRS)

Amano, Ryoichi S.; Chai, John C.; Chen, Jau-Der

1988-01-01

Theoretical models are developed and numerical studies conducted on various types of flows including both elliptic and parabolic. The purpose of this study is to find better higher order closure models for the computations of complex flows. This report summarizes three new achievements: (1) completion of the Reynolds-stress closure by developing a new pressure-strain correlation; (2) development of a parabolic code to compute jets and wakes; and, (3) application to a flow through a 180 deg turnaround duct by adopting a boundary fitted coordinate system. In the above mentioned models near-wall models are developed for pressure-strain correlation and third-moment, and incorporated into the transport equations. This addition improved the results considerably and is recommended for future computations. A new parabolic code to solve shear flows without coordinate tranformations is developed and incorporated in this study. This code uses the structure of the finite volume method to solve the governing equations implicitly. The code was validated with the experimental results available in the literature.

A Nomographic Methodology for Use in Performance Trade-Off Studies of Parabolic Dish Solar Power Modules

NASA Technical Reports Server (NTRS)

Selcuk, M. K.; Fujita, T.

1984-01-01

A simple graphical method was developed to undertake technical design trade-off studies for individual parabolic dish models comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies are then used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module were arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included.

The Discrete Hanging Cable

ERIC Educational Resources Information Center

Peters, James V.

2004-01-01

Using the methods of finite difference equations the discrete analogue of the parabolic and catenary cable are analysed. The fibonacci numbers and the golden ratio arise in the treatment of the catenary.

Method to improve lubricity of low-sulfur diesel and gasoline fuels

DOEpatents

Erdemir, Ali

2004-08-31

A method for providing lubricity in fuels and lubricants includes adding a boron compound to a fuel or lubricant to provide a boron-containing fuel or lubricant. The fuel or lubricant may contain a boron compound at a concentration between about 30 ppm and about 3,000 ppm and a sulfur concentration of less than about 500 ppm. A method of powering an engine to minimize wear, by burning a fuel containing boron compounds. The boron compounds include compound that provide boric acid and/or BO.sub.3 ions or monomers to the fuel or lubricant.

Low-pass parabolic FFT filter for airborne and satellite lidar signal processing.

PubMed

Jiao, Zhongke; Liu, Bo; Liu, Enhai; Yue, Yongjian

2015-10-14

In order to reduce random errors of the lidar signal inversion, a low-pass parabolic fast Fourier transform filter (PFFTF) was introduced for noise elimination. A compact airborne Raman lidar system was studied, which applied PFFTF to process lidar signals. Mathematics and simulations of PFFTF along with low pass filters, sliding mean filter (SMF), median filter (MF), empirical mode decomposition (EMD) and wavelet transform (WT) were studied, and the practical engineering value of PFFTF for lidar signal processing has been verified. The method has been tested on real lidar signal from Wyoming Cloud Lidar (WCL). Results show that PFFTF has advantages over the other methods. It keeps the high frequency components well and reduces much of the random noise simultaneously for lidar signal processing.

A modified Dodge algorithm for the parabolized Navier-Stokes equations and compressible duct flows

NASA Technical Reports Server (NTRS)

Cooke, C. H.; Dwoyer, D. M.

1983-01-01

A revised version of Dodge's split-velocity method for numerical calculation of compressible duct flow was developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front-to-back continuity during the calculation. The (checkerboard) zebra algorithm is applied to solution of the three dimensional continuity equation in conservative form. A second-order A-stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A checkerboard iteration is used to solve the resulting implicit nonlinear systems of finite-difference equations which govern stepwise transition. Qualitative agreement with analytical predictions and experimental results was obtained for some flows with well-known solutions. Previously announced in STAR as N82-16363

The Chebyshev-Legendre method: Implementing Legendre methods on Chebyshev points

NASA Technical Reports Server (NTRS)

Don, Wai Sun; Gottlieb, David

1993-01-01

We present a new collocation method for the numerical solution of partial differential equations. This method uses the Chebyshev collocation points, but because of the way the boundary conditions are implemented, it has all the advantages of the Legendre methods. In particular, L2 estimates can be obtained easily for hyperbolic and parabolic problems.

Uniqueness of complete maximal hypersurfaces in spatially parabolic generalized Robertson-Walker spacetimes

NASA Astrophysics Data System (ADS)

Romero, Alfonso; Rubio, Rafael M.; Salamanca, Juan J.

2013-06-01

A new technique for the study of noncompact complete spacelike hypersurfaces in generalized Robertson-Walker (GRW) spacetimes whose fiber is a parabolic Riemannian manifold is introduced. This class of spacetimes allows us to model open universes which extend to spacelike closed GRW spacetimes from the viewpoint of the geometric analysis of the fiber, and which, unlike those spacetimes, could be compatible with the holographic principle. First, under reasonable assumptions on the restriction of the warping function to the spacelike hypersurface and on the hyperbolic angle between the unit normal vector field and a certain timelike vector field, a complete spacelike hypersurface in a spatially parabolic GRW spacetime is shown to be parabolic, and the existence of a simply connected parabolic spacelike hypersurface in a GRW spacetime also leads to the parabolicity of its fiber. Then, all the complete maximal hypersurfaces in spatially parabolic GRW spacetimes are determined in several cases, extending, in particular, to this family of open cosmological models several well-known uniqueness results for the case of spatially closed GRW spacetimes. Moreover, new Calabi-Bernstein problems are solved.

Pulmonary responses of healthy young adults exposed to 0.06 and 0.08 ppm ozone

EPA Science Inventory

Background. Previous studies have shown small but significant decreases in spirometric lung function in healthy young adults exposed to 0.08 ppm ozone. It is unclear, however, if such effects may are seen at concentrations below 0.08 ppm. Methods. A group of 30 healthy young adul...

Parabolic dune development modes according to shape at the southern fringes of the Hobq Desert, Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Guan, Chao; Hasi, Eerdun; Zhang, Ping; Tao, Binbin; Liu, Dan; Zhou, Yanguang

2017-10-01

Since the 1970s, parabolic dunes at the southern fringe of the Hobq Desert, Inner Mongolia, China have exhibited many different shapes (V-shaped, U-shaped, and palmate) each with a unique mode of development. In the study area, parabolic dunes are mainly distributed in Regions A, B, and C with an intermittent river running from the south to the north. We used high-resolution remote-sensing images from 1970 to 2014 and RTK-GPS measurements to study the development modes of different dune shapes; the modes are characterized by the relationship between the intermittent river and dunes, formation of the incipient dune patterns, the predominant source supply of dunes, and the primary formation of different shapes (V-shaped, U-shaped, and palmate). Most parabolic dunes in Region A are V-shaped and closer to the bank of the river. The original barchans in this region exhibit "disconnected arms" behavior. With the sand blown out of the riverbed through gullies, the nebkhas on the disconnected arms acquire the external sand source through the "fertile island effect", thereby developing into triangular sand patches and further developing into V-shaped parabolic dunes. Most parabolic dunes in Regions B and C are palmate. The residual dunes cut by the re-channelization of river from transverse dune fields on the west bank are the main sand source of Region B. The parabolic dunes in Region C are the original barchans having then been transformed. The stoss slopes of V-shaped parabolic dunes along the riverbank are gradual and the dunes are flat in shape. The dune crest of V-shaped parabolic dune is the deposition area, which forms the "arc-shaped sand ridge". Their two arms are non-parallel; the lateral airflow of the arms jointly transport sand to the middle part of dunes, resulting in a narrower triangle that gradually becomes V-shaped. Palmate parabolic dunes have a steeper stoss slope and height. The dune crest of the palmate parabolic dune is the erosion area, which forms a long and narrow trough between nebkhas by the "funnelling effect". This process forces sand towards lee slopes, which transform from concave (original barchans) into convex, ultimately resulting in the formation of palmate parabolic dunes.

Review of Large Spacecraft Deployable Membrane Antenna Structures

NASA Astrophysics Data System (ADS)

Liu, Zhi-Quan; Qiu, Hui; Li, Xiao; Yang, Shu-Li

2017-11-01

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer (SMP)-inflation, and electrostatic forming. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials (including polyester film and polyimide film) for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different tensioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures, materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.

Whole surface image reconstruction for machine vision inspection of fruit

NASA Astrophysics Data System (ADS)

Reese, D. Y.; Lefcourt, A. M.; Kim, M. S.; Lo, Y. M.

2007-09-01

Automated imaging systems offer the potential to inspect the quality and safety of fruits and vegetables consumed by the public. Current automated inspection systems allow fruit such as apples to be sorted for quality issues including color and size by looking at a portion of the surface of each fruit. However, to inspect for defects and contamination, the whole surface of each fruit must be imaged. The goal of this project was to develop an effective and economical method for whole surface imaging of apples using mirrors and a single camera. Challenges include mapping the concave stem and calyx regions. To allow the entire surface of an apple to be imaged, apples were suspended or rolled above the mirrors using two parallel music wires. A camera above the apples captured 90 images per sec (640 by 480 pixels). Single or multiple flat or concave mirrors were mounted around the apple in various configurations to maximize surface imaging. Data suggest that the use of two flat mirrors provides inadequate coverage of a fruit but using two parabolic concave mirrors allows the entire surface to be mapped. Parabolic concave mirrors magnify images, which results in greater pixel resolution and reduced distortion. This result suggests that a single camera with two parabolic concave mirrors can be a cost-effective method for whole surface imaging.

Bound States and the Third Harmonic Generation in an Electric Field Biased Semi-parabolic Quantum Well

NASA Astrophysics Data System (ADS)

Zhang, Li; Xie, Hong-Jing

2003-11-01

Within the framework of the compact density matrix approach, the third-harmonic generation (THG) in an electric-field-biased semi-parabolic quantum well (QW) has been deduced and investigated. Via variant of displacement harmonic oscillation, the exact electronic states in the semi-parabolic QW with an applied electric field have also been obtained and discussed. Numerical results on typical GaAs material reveal that, electric fields and confined potential frequency of semi-parabolic QW have obvious influences on the energy levels of electronic states and the THG in the semi-parabolic QW systems. The project supported in part by Guangdong Provincial Natural Science Foundation of China

Efficient solution of parabolic equations by Krylov approximation methods

NASA Technical Reports Server (NTRS)

Gallopoulos, E.; Saad, Y.

1990-01-01

Numerical techniques for solving parabolic equations by the method of lines is addressed. The main motivation for the proposed approach is the possibility of exploiting a high degree of parallelism in a simple manner. The basic idea of the method is to approximate the action of the evolution operator on a given state vector by means of a projection process onto a Krylov subspace. Thus, the resulting approximation consists of applying an evolution operator of a very small dimension to a known vector which is, in turn, computed accurately by exploiting well-known rational approximations to the exponential. Because the rational approximation is only applied to a small matrix, the only operations required with the original large matrix are matrix-by-vector multiplications, and as a result the algorithm can easily be parallelized and vectorized. Some relevant approximation and stability issues are discussed. We present some numerical experiments with the method and compare its performance with a few explicit and implicit algorithms.

The ABCD matrix for parabolic reflectors and its application to astigmatism free four-mirror cavities

NASA Astrophysics Data System (ADS)

Dupraz, K.; Cassou, K.; Martens, A.; Zomer, F.

2015-10-01

The ABCD matrix for parabolic reflectors is derived for any incident angles. It is used in numerical studies of four-mirror cavities composed of two flat and two parabolic mirrors. Constraints related to laser beam injection efficiency, optical stability, cavity-mode, beam-waist size and high stacking power are satisfied. A dedicated alignment procedure leading to stigmatic cavity-modes is employed to overcome issues related to the optical alignment of parabolic reflectors.

Comparative study on conventional, ultrasonication and microwave assisted extraction of γ-oryzanol from rice bran.

PubMed

Kumar, Pramod; Yadav, Devbrat; Kumar, Pradyuman; Panesar, Paramjeet Singh; Bunkar, Durga Shankar; Mishra, Diwaker; Chopra, H K

2016-04-01

In present study, conventional, ultrasonic and microwave assisted extraction methods were compared with the aim of optimizing best fitting solvent and method, solvent concentration and digestion time for high yield of γ-oryzanol from rice bran. Petroleum ether, hexane and methanol were used to prepare extracts. Extraction yield were evaluated for giving high crude oil yield, total phenolic content (TPC) and γ-oryzanol content. Gas chromatography-mass spectrophotometry was used for the determination of γ-oryzanol concentration. The highest concentration of γ-oryzanol was detected in methanolic extracts of microwave treatment (85.0 ppm) followed by ultrasonication (82.0 ppm) and conventional extraction method (73.5 ppm). Concentration of γ-oryzanol present in the extracts was found to be directly proportional to the total phenolic content. A combination of 80 % methanolic concentration and 55 minutes digestion time of microwave treatment yielded the best extraction method for TPC and thus γ-oryzanol (105 ppm).

γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

NASA Astrophysics Data System (ADS)

Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

2017-05-01

This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 106 and detection limit of 1.0 × 10-7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

Compound parabolic concentrator probe for efficient light collection in spectroscopy of biological tissue

NASA Astrophysics Data System (ADS)

Tanaka, Kazunori; Pacheco, Marcos T. T.; Brennan, James F., III; Itzkan, Irving; Berger, Andrew J.; Dasari, Ramachandra R.; Feld, Michael S.

1996-02-01

We describe a compound parabolic concentrator (CPC)-based probe for enhanced signal collection in the spectroscopy of biological tissues. Theoretical considerations governing signal enhancement compared with conventional collection methods are given. A ray-tracing program was used to analyze the throughput of CPC's with shape deviations and surface imperfections. A modified CPC shape with 99% throughput was discovered. A 4.4-mm-long CPC was manufactured and incorporated into an optical fiber-based near-infrared Raman spectrometer system. For human tissue samples, light collection was enhanced by a factor of 7 compared with collection with 0.29-NA optical fibers.

Parabolic features and the erosion rate on Venus

NASA Technical Reports Server (NTRS)

Strom, Robert G.

1993-01-01

The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

Possibility of exchange of a rectilinear three-body system with zero energy

NASA Astrophysics Data System (ADS)

Koda, Eiji

The possibility of exchange for a rectilinear three-body system with zero energy is examined by introducing regularized coordinates which are closely related to McGehee's (1974) coordinates. It is shown that all of the HE(-)-HE(+) orbits are of exchange type in a critical system whose orbits of parabolic-parabolic escape type experience odd times of binary collision. No exchange occurs in critical systems whose orbits of parabolic-parabolic escape type experience even times of binary collision.

Chromatographic methods for determination of macrolide antibiotic residues in tissues and milk of food-producing animals.

PubMed

Moats, W A

1985-01-01

Tylosin, an antibiotic developed specifically for agricultural use, and erythromycin are the main macrolide antibiotics used in animal production. Two-dimensional thin layer chromatography has been used for detection of tylosin in poultry meat, eggs, and milk and for erythromycin in poultry meat. Detection limits reported are, for tylosin, 0.1 ppm in poultry meat, 0.05 ppm in egg, and 0.01 ppm in milk, and for erythromycin, 0.25 ppm in poultry meat. Liquid chromatography (LC) has also been used for determination of tylosin in milk, blood, and tissues of animals. Samples (milk, blood serum, or tissue homogenates in water or pH 2.2 buffer) were deproteinized with acetonitrile, tylosin was partitioned into methylene chloride, and the extracts were concentrated and dissolved in acetonitrile. Chromatography was done on a reverse phase end-capped C18 column using 0.002-0.005 M ammonium dihydrogen phosphate-acetonitrile-methanol (10 + 60 + 30-5 + 80 + 15). Solvent composition was varied with the type of sample analyzed. The method will detect 0.1 ppm tylosin in tissues and less in milk and blood serum. The LC method was more sensitive than microbiological assays for detection of tylosin in tissues of treated swine; recoveries of tylosin by the LC method were frequently several-fold higher.

Use of a Parabolic Microphone to Detect Hidden Subjects in Search and Rescue.

PubMed

Bowditch, Nathaniel L; Searing, Stanley K; Thomas, Jeffrey A; Thompson, Peggy K; Tubis, Jacqueline N; Bowditch, Sylvia P

2018-03-01

This study compares a parabolic microphone to unaided hearing in detecting and comprehending hidden callers at ranges of 322 to 2510 m. Eight subjects were placed 322 to 2510 m away from a central listening point. The subjects were concealed, and their calling volume was calibrated. In random order, subjects were asked to call the name of a state for 5 minutes. Listeners with parabolic microphones and others with unaided hearing recorded the direction of the call (detection) and name of the state (comprehension). The parabolic microphone was superior to unaided hearing in both detecting subjects and comprehending their calls, with an effect size (Cohen's d) of 1.58 for detection and 1.55 for comprehension. For each of the 8 hidden subjects, there were 24 detection attempts with the parabolic microphone and 54 to 60 attempts by unaided listeners. At the longer distances (1529-2510 m), the parabolic microphone was better at detecting callers (83% vs 51%; P<0.00001 by χ 2 ) and comprehension (57% vs 12%; P<0.00001). At the shorter distances (322-1190 m), the parabolic microphone offered advantages in detection (100% vs 83%; P=0.000023) and comprehension (86% vs 51%; P<0.00001), although not as pronounced as at the longer distances. Use of a 66-cm (26-inch) parabolic microphone significantly improved detection and comprehension of hidden calling subjects at distances between 322 and 2510 m when compared with unaided hearing. This study supports the use of a parabolic microphone in search and rescue to locate responsive subjects in favorable weather and terrain. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Wall jet analysis for circulation control aerodynamics. Part 1: Fundamental CFD and turbulence modeling concepts

NASA Technical Reports Server (NTRS)

Dash, S. M.; York, B. J.; Sinha, N.; Dvorak, F. A.

1987-01-01

An overview of parabolic and PNS (Parabolized Navier-Stokes) methodology developed to treat highly curved sub and supersonic wall jets is presented. The fundamental data base to which these models were applied is discussed in detail. The analysis of strong curvature effects was found to require a semi-elliptic extension of the parabolic modeling to account for turbulent contributions to the normal pressure variations, as well as an extension to the turbulence models utilized, to account for the highly enhanced mixing rates observed in situations with large convex curvature. A noniterative, pressure split procedure is shown to extend parabolic models to account for such normal pressure variations in an efficient manner, requiring minimal additional run time over a standard parabolic approach. A new PNS methodology is presented to solve this problem which extends parabolic methodology via the addition of a characteristic base wave solver. Applications of this approach to analyze the interaction of wave and turbulence processes in wall jets is presented.

Nonlinear Landau damping and formation of Bernstein-Greene-Kruskal structures for plasmas with q-nonextensive velocity distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghunathan, M.; Ganesh, R.

2013-03-15

In the past, long-time evolution of an initial perturbation in collisionless Maxwellian plasma (q = 1) has been simulated numerically. The controversy over the nonlinear fate of such electrostatic perturbations was resolved by Manfredi [Phys. Rev. Lett. 79, 2815-2818 (1997)] using long-time simulations up to t=1600{omega}{sub p}{sup -1}. The oscillations were found to continue indefinitely leading to Bernstein-Greene-Kruskal (BGK)-like phase-space vortices (from here on referred as 'BGK structures'). Using a newly developed, high resolution 1D Vlasov-Poisson solver based on piecewise-parabolic method (PPM) advection scheme, we investigate the nonlinear Landau damping in 1D plasma described by toy q-distributions for long times,more » up to t=3000{omega}{sub p}{sup -1}. We show that BGK structures are found only for a certain range of q-values around q = 1. Beyond this window, for the generic parameters, no BGK structures were observed. We observe that for values of q<1 where velocity distributions have long tails, strong Landau damping inhibits the formation of BGK structures. On the other hand, for q>1 where distribution has a sharp fall in velocity, the formation of BGK structures is rendered difficult due to high wave number damping imposed by the steep velocity profile, which had not been previously reported. Wherever relevant, we compare our results with past work.« less

Parabolic flight induces changes in gene expression patterns in Arabidopsis thaliana.

PubMed

Paul, Anna-Lisa; Manak, Michael S; Mayfield, John D; Reyes, Matthew F; Gurley, William B; Ferl, Robert J

2011-10-01

Our primary objective was to evaluate gene expression changes in Arabidopsis thaliana in response to parabolic flight as part of a comprehensive approach to the molecular biology of spaceflight-related adaptations. In addition, we wished to establish parabolic flight as a tractable operations platform for molecular biology studies. In a succession of experiments on NASA's KC-135 and C-9 parabolic aircraft, Arabidopsis plants were presented with replicated exposure to parabolic flight. Transcriptome profiling revealed that parabolic flight caused changes in gene expression patterns that stood the statistical tests of replication on three different flight days. The earliest response, after 20 parabolas, was characterized by a prominence of genes associated with signal transduction. After 40 parabolas, this prominence was largely replaced by genes associated with biotic and abiotic stimuli and stress. Among these responses, three metabolic processes stand out in particular: the induction of auxin metabolism and signaling, the differential expression of genes associated with calcium-mediated signaling, and the repression of genes associated with disease resistance and cell wall biochemistry. Many, but not all, of these responses are known to be involved in gravity sensing in plants. Changes in auxin-related gene expression were also recorded by reporter genes tuned to auxin signal pathways. These data demonstrate that the parabolic flight environment is appropriate for molecular biology research involving the transition to microgravity, in that with replication, proper controls, and analyses, gene expression changes can be observed in the time frames of typical parabolic flight experiments.

Parallel SOR methods with a parabolic-diffusion acceleration technique for solving an unstructured-grid Poisson equation on 3D arbitrary geometries

NASA Astrophysics Data System (ADS)

Zapata, M. A. Uh; Van Bang, D. Pham; Nguyen, K. D.

2016-05-01

This paper presents a parallel algorithm for the finite-volume discretisation of the Poisson equation on three-dimensional arbitrary geometries. The proposed method is formulated by using a 2D horizontal block domain decomposition and interprocessor data communication techniques with message passing interface. The horizontal unstructured-grid cells are reordered according to the neighbouring relations and decomposed into blocks using a load-balanced distribution to give all processors an equal amount of elements. In this algorithm, two parallel successive over-relaxation methods are presented: a multi-colour ordering technique for unstructured grids based on distributed memory and a block method using reordering index following similar ideas of the partitioning for structured grids. In all cases, the parallel algorithms are implemented with a combination of an acceleration iterative solver. This solver is based on a parabolic-diffusion equation introduced to obtain faster solutions of the linear systems arising from the discretisation. Numerical results are given to evaluate the performances of the methods showing speedups better than linear.

Estimation of the Thermal Process in the Honeycomb Panel by a Monte Carlo Method

NASA Astrophysics Data System (ADS)

Gusev, S. A.; Nikolaev, V. N.

2018-01-01

A new Monte Carlo method for estimating the thermal state of the heat insulation containing honeycomb panels is proposed in the paper. The heat transfer in the honeycomb panel is described by a boundary value problem for a parabolic equation with discontinuous diffusion coefficient and boundary conditions of the third kind. To obtain an approximate solution, it is proposed to use the smoothing of the diffusion coefficient. After that, the obtained problem is solved on the basis of the probability representation. The probability representation is the expectation of the functional of the diffusion process corresponding to the boundary value problem. The process of solving the problem is reduced to numerical statistical modelling of a large number of trajectories of the diffusion process corresponding to the parabolic problem. It was used earlier the Euler method for this object, but that requires a large computational effort. In this paper the method is modified by using combination of the Euler and the random walk on moving spheres methods. The new approach allows us to significantly reduce the computation costs.

Spectral methods for partial differential equations

NASA Technical Reports Server (NTRS)

Hussaini, M. Y.; Streett, C. L.; Zang, T. A.

1983-01-01

Origins of spectral methods, especially their relation to the Method of Weighted Residuals, are surveyed. Basic Fourier, Chebyshev, and Legendre spectral concepts are reviewed, and demonstrated through application to simple model problems. Both collocation and tau methods are considered. These techniques are then applied to a number of difficult, nonlinear problems of hyperbolic, parabolic, elliptic, and mixed type. Fluid dynamical applications are emphasized.

Recent applications of spectral methods in fluid dynamics

NASA Technical Reports Server (NTRS)

Zang, T. A.; Hussaini, M. Y.

1985-01-01

Origins of spectral methods, especially their relation to the method of weighted residuals, are surveyed. Basic Fourier and Chebyshev spectral concepts are reviewed and demonstrated through application to simple model problems. Both collocation and tau methods are considered. These techniques are then applied to a number of difficult, nonlinear problems of hyperbolic, parabolic, elliptic and mixzed type. Fluid dynamical applications are emphasized.

Tracking of Ball and Players in Beach Volleyball Videos

PubMed Central

Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

2014-01-01

This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

Solar parabolic dish technology evaluation report

NASA Technical Reports Server (NTRS)

Lucas, J. W.

1984-01-01

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1983 are summarized. Included are discussions on designs of module development including concentrator, receiver, and power conversion subsystems together with a separate discussion of field tests, Small Community Experiment system development, and tests at the Parabolic Dish Test Site.

Proceedings of the Fifth Parabolic Dish Solar Thermal Power Program

NASA Technical Reports Server (NTRS)

Lucas, J. W. (Editor)

1984-01-01

The proceedings of the Fifth Parabolic Dish Solar Thermal Power Program Annual Review are presented. The results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program were emphasized. Among the topics discussed were: overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development along with associated hardware and test results; distributed systems operating experience; international parabolic dish development activities; and non-DOE-sponsored domestic dish activities. Solar electric generation was also addressed.

Nonimaging secondary concentrators for large rim angle parabolic troughs with tubular absorbers.

PubMed

Ries, H; Spirkl, W

1996-05-01

For parabolic trough solar collectors with tubular absorbers, we design new tailored secondary concentrators. The design is applicable for any rim angle of a parabolic reflector. With the secondary, the concentration can be increased by a factor of more than 2 with a compact secondary reflector consisting of a single piece, even for the important case of a rim angle of 90 deg. The parabolic reflector can be used without changes; the reduced absorber is still tubular but smaller than the original absorber and slightly displaced toward the primary.

A systematic assessment of the concept and practice of public-private mix for tuberculosis care and control

PubMed Central

2011-01-01

Introduction The STOP TB Partnership aims to improve global tuberculosis (TB) control through expanding access to the directly observed treatment short course (DOTS) strategy. One approach to this is 'Engaging all Care Providers', which evolved from 'Public-Private Mix (PPM) DOTS'. The overall aim of this study was to systematically assess whether and to what degree the STOP TB Partnership's four global objectives of engaging all care providers are met through existing PPM interventions. These four objectives are; 1) Increase TB case detection; 2) Improve TB treatment outcomes; 3) Enhance access and equity; 4) Reduce financial burden on patients. The specific objectives of this assessment were to 1) Understand what PPM means to the STOP TB Partnership's PPM Subgroup and to National Tuberculosis Programme managers; 2) Scope the nature of existing country-level PPM interventions and 3) Review PPM practice against the global PPM objectives. Methods We undertook a systematic, multi-facetted assessment. The methods included interviews with National Tuberculosis Programme managers from high burden countries, clarification of key issues with the STOP TB Partnership PPM secretariat and a review of publicly accessible reports and published articles on PPM projects. Both the literature review and interviews with the National Tuberculosis Programme managers yielded data on project characteristics; PPM models at country level; National Tuberculosis Programme partners; and mechanisms for engagement. Matrices were developed from the literature review and the interviews to show the relationship between services and service providers for different PPM projects. Data from the literature were assessed against each of the four global PPM objectives. Results Twelve National Tuberculosis Programme managers from high burden countries were interviewed about the scope of PPM partnerships. Understanding of PPM and types of engaged providers varied considerably; 'private-for-profit qualified clinical providers' were the dominant category. The literature review yielded information on 22 projects in which 'private-for-profit qualified clinical providers' were again the dominant category. The contributions made by 'private-for-profit qualified clinical providers' and 'Non Governmental Organisation qualified clinical providers', were assessed against the four global PPM objectives. Reporting on tuberculosis case detection and treatment outcomes was generally good and demonstrated important PPM contributions in these areas. Reporting on equity, access and reduced patient costs was often lacking or inconclusive. Conclusions PPM has improved case detection and treatment outcomes among patients seeking care with private providers. Evidence on reducing patient costs is inconclusive, and there is scope for increasing equity in access to care by systematically engaging those providers who are the primary agents for poor people seeking health care. Guidelines outlining which types of providers best contribute to achieving the four global objectives, along with the resources required by National Tuberculosis Programs for such engagement is needed. PMID:22074377

Determination of the content of fatty acid methyl esters (FAME) in biodiesel samples obtained by esterification using 1H-NMR spectroscopy.

PubMed

Mello, Vinicius M; Oliveira, Flavia C C; Fraga, William G; do Nascimento, Claudia J; Suarez, Paulo A Z

2008-11-01

Three different calibration curves based on (1)H-NMR spectroscopy (300 MHz) were used for quantifying the reaction yield during biodiesel synthesis by esterification of fatty acids mixtures and methanol. For this purpose, the integrated intensities of the hydrogens of the ester methoxy group (3.67 ppm) were correlated with the areas related to the various protons of the alkyl chain (olefinic hydrogens: 5.30-5.46 ppm; aliphatic: 2.67-2.78 ppm, 2.30 ppm, 1.96-2.12 ppm, 1.56-1.68 ppm, 1.22-1.42 ppm, 0.98 ppm, and 0.84-0.92 ppm). The first curve was obtained using the peaks relating the olefinic hydrogens, a second with the parafinic protons and the third curve using the integrated intensities of all the hydrogens. A total of 35 samples were examined: 25 samples to build the three different calibration curves and ten samples to serve as external validation samples. The results showed no statistical differences among the three methods, and all presented prediction errors less than 2.45% with a co-efficient of variation (CV) of 4.66%. 2008 John Wiley & Sons, Ltd.

Interactive effect of elevated CO2 and temperature on coral physiology

NASA Astrophysics Data System (ADS)

Grottoli, A. G.; Cai, W.; Warner, M.; Melman, T.; Schoepf, V.; Baumann, J.; Matsui, Y.; Pettay, D. T.; Hoadley, K.; Xu, H.; Wang, Y.; Li, Q.; Hu, X.

2011-12-01

Increases in ocean acidification and temperature threaten coral reefs globally. However, the interactive effect of both lower pH and higher temperature on coral physiology and growth are poorly understood. Here, we present preliminary findings from a replicated controlled experiment where four species of corals (Acorpora millepora, Pocillopora damicornis, Montipora monasteriata, Turbinaria reniformis) were reared under the following six treatments for three weeks: 1) 400ppm CO2 and ambient temperature, 2) 400ppm CO2 and elevated temperature, 3) 650ppm CO2 and ambient temperature, 4) 650ppm CO2 and elevated temperature, 5) 800ppm CO2 and ambient temperature, 6) 800ppm CO2 and elevated temperature. Initial findings of photophysiological health (Fv/Fm), calcification rates (as measured by both buoyant weight and the total alkalinity methods), and energy reserves will be presented.

Assignment of the molecular origins of CEST signals at 2 ppm in rat brain.

PubMed

Zhang, Xiao-Yong; Xie, Jingping; Wang, Feng; Lin, Eugene C; Xu, Junzhong; Gochberg, Daniel F; Gore, John C; Zu, Zhongliang

2017-09-01

Chemical exchange saturation transfer effects at 2 ppm (CEST@2ppm) in brain have previously been interpreted as originating from creatine. However, protein guanidino amine protons may also contribute to CEST@2ppm. This study aims to investigate the molecular origins and specificity of CEST@2ppm in brain. Two experiments were performed: (i) samples containing egg white albumin and creatine were dialyzed using a semipermeable membrane to demonstrate that proteins and creatine can be separated by this method; and (ii) tissue homogenates of rat brain with and without dialysis to remove creatine were studied to measure the relative contributions of proteins and creatine to CEST@2ppm. The experiments indicate that dialysis can successfully remove creatine from proteins. Measurements on tissue homogenates show that, with the removal of creatine via dialysis, CEST@2ppm decreases to approximately 34% of its value before dialysis, which indicates that proteins and creatine have comparable contribution to the CEST@2ppm in brain. However, considering the contribution from peptides and amino acids to CEST@2ppm, creatine may have much less contribution to CEST@2ppm. The contribution of proteins, peptides, and amino acids to CEST@2ppm cannot be neglected. The CEST@2ppm measurements of creatine in rat brain should be interpreted with caution. Magn Reson Med 78:881-887, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Stability derivatives for bodies of revolution at subsonic speeds

NASA Technical Reports Server (NTRS)

Liu, D. D.; Platzer, M. F.; Ruo, S. Y.

1976-01-01

The paper considers a rigid pointed body of revolution in a steady uniform subsonic flow. The body performs harmonic small-amplitude pitching oscillations around its zero angle of attack position. The body is assumed to be smooth and sufficiently slender so that the small perturbation concept can be applied. The basis of the method used, following Revell (1960), is the relation of a body-fixed perturbation potential to the general velocity potential. Normal force distributions as well as total force and moment coefficients are calculated for parabolic spindles and the numerical results show good agreement between Revell's second-order slender body theory and the present theory for the static stability derivatives of the parabolic spindles.

Optimization method for an evolutional type inverse heat conduction problem

NASA Astrophysics Data System (ADS)

Deng, Zui-Cha; Yu, Jian-Ning; Yang, Liu

2008-01-01

This paper deals with the determination of a pair (q, u) in the heat conduction equation u_t-u_{xx}+q(x,t)u=0, with initial and boundary conditions u(x,0)=u_0(x),\\qquad u_x|_{x=0}=u_x|_{x=1}=0, from the overspecified data u(x, t) = g(x, t). By the time semi-discrete scheme, the problem is transformed into a sequence of inverse problems in which the unknown coefficients are purely space dependent. Based on the optimal control framework, the existence, uniqueness and stability of the solution (q, u) are proved. A necessary condition which is a couple system of a parabolic equation and parabolic variational inequality is deduced.

A Pseudo-Temporal Multi-Grid Relaxation Scheme for Solving the Parabolized Navier-Stokes Equations

NASA Technical Reports Server (NTRS)

White, J. A.; Morrison, J. H.

1999-01-01

A multi-grid, flux-difference-split, finite-volume code, VULCAN, is presented for solving the elliptic and parabolized form of the equations governing three-dimensional, turbulent, calorically perfect and non-equilibrium chemically reacting flows. The space marching algorithms developed to improve convergence rate and or reduce computational cost are emphasized. The algorithms presented are extensions to the class of implicit pseudo-time iterative, upwind space-marching schemes. A full approximate storage, full multi-grid scheme is also described which is used to accelerate the convergence of a Gauss-Seidel relaxation method. The multi-grid algorithm is shown to significantly improve convergence on high aspect ratio grids.

Preliminary study: Formaldehyde exposure in laboratories of Sharjah university in UAE

PubMed Central

Ahmed, Hafiz Omer

2011-01-01

Objectives Laboratory technicians, students, and instructors are at high risk, because they deal with chemicals including formaldehyde. Thus, this preliminary study was conducted to measure the concentration of formaldehyde in the laboratories of the University of Sharjah in UAE. Materials and Methods: Thirty-two air samples were collected and analyzed for formaldehyde using National Institute for Occupational Safety and Health (NIOSH) method 3500. In this method, formaldehyde reacts with chromotropic acid in the presence of sulfuric acid to form a colored solution. The absorbance of the colored solution is read in spectrophotometer at wavelength 580 nm and is proportional to the quantity of the formaldehyde in the solution. Results: For the anatomy laboratory and in the presence of the covered cadaver, the mean concentration of formaldehyde was found to be 0.100 ppm with a range of 0.095–0.105 ppm. Whereas for the other laboratories, the highest mean concentration of formaldehyde was 0.024 ppm in the general microbiology laboratory and the lowest mean concentration of formaldehyde was 0.001 ppm in the environmental health laboratory. The 8-hour (time-weighted average) concentration of formaldehyde was found to be ranging between 0.0003 ppm in environmental health laboratory and 0.026 ppm in the anatomy laboratory. Conclusions: The highest level of concentration of formaldehyde in the presence of the covered cadaver in anatomy laboratory exceeded the recommended ceiling standard established by USA-NIOSH which is 0.1 ppm, but below the ceiling standard established by American Conference of Governmental Industrial Hygienists which is 0.3 ppm. Thus, it is recommended that formaldehyde levels should be measured periodically specially during the dissection in the anatomy laboratory, and local exhaust ventilation system should be installed and personal protective equipment such as safety glass and gloves should be available and be used to prevent direct skin or eye contact. PMID:21808499

A new method research of monitoring low concentration NO and SO2 mixed gas

NASA Astrophysics Data System (ADS)

Bo, Peng; Gao, Chao; Guo, Yongcai; Chen, Fang

2018-01-01

In order to reduce the pollution of the environment, China has implemented a new ultra-low emission control regulations for polluting gas, requiring new coal-fired power plant emissions SO2 less than 30ppm, NO less than 75ppm, NO2 less than 50ppm, Monitoring low concentration of NO and SO2 mixed gases , DOAS technology facing new challenges, SO2 absorb significantly weaken at the original absorption peak, what more the SNR is very low, it is difficult to extract the characteristic signal, and thus cannot obtain its concentration. So it cannot separate the signal of NO from the mixed gas at the wavelength of 200 230nm through the law of spectral superposition, it cannot calculate the concentration of NO. The classical DOAS technology cannot meet the needs of monitoring. In this paper, we found another absorption spectrum segment of SO2, the SNR is 10 times higher than before, Will not be affected by NO, can calculate the concentration of SO2 accurately, A new method of segmentation and demagnetization separation technology of spectral signals is proposed, which achieves the monitoring the low concentration mixed gas accurately. This function cannot be achieved by the classical DOAS. Detection limit of this method is 0.1ppm per meter which is higher than before, The relative error below 5% when the concentration between 0 5ppm, the concentration of NO between 6 75ppm and SO2 between 6 30ppm the relative error below 1.5%, it has made a great breakthrough In the low concentration of NO and SO2 monitoring. It has great scientific significance and reference value for the development of coal-fired power plant emission control, atmospheric environmental monitoring and high-precision on-line instrumentation.

40 CFR 80.580 - What are the sampling and testing methods for sulfur?

Code of Federal Regulations, 2010 CFR

2010-07-01

...,000 ppm sulfur standard of § 80.510(k), sulfur content may be determined using ASTM D2622... the 500 ppm sulfur standard of § 80.510(a)(1), sulfur content may be determined using ASTM D2622... to the 1,000 ppm sulfur standard of § 80.510(k), sulfur content may be determined using ASTM D4294...

Concentrating Solar Power Projects - Delingha 50MW Thermal Oil Parabolic

Science.gov Websites

Trough project | Concentrating Solar Power | NREL Delingha 50MW Thermal Oil Parabolic Trough project Status Date: April 17, 2017 Project Overview Project Name: Delingha 50MW Thermal Oil Parabolic Contractor: IDOM : Thermal energy storage system engineering Plant Configuration Solar Field # of Loops: 190

Concentrating Solar Power Projects - Gulang 100MW Thermal Oil Parabolic

Science.gov Websites

Trough project | Concentrating Solar Power | NREL Gulang 100MW Thermal Oil Parabolic Trough project Status Date: September 29, 2016 Project Overview Project Name: Gulang 100MW Thermal Oil Parabolic ): Webmaster Solar Participants Developer(s): Changzhou Royal Tech Solar Thermal Equipment Co., Ltd. Owner(s

Hyperbolic/parabolic development for the GIM-STAR code. [flow fields in supersonic inlets

NASA Technical Reports Server (NTRS)

Spradley, L. W.; Stalnaker, J. F.; Ratliff, A. W.

1980-01-01

Flow fields in supersonic inlet configurations were computed using the eliptic GIM code on the STAR computer. Spillage flow under the lower cowl was calculated to be 33% of the incoming stream. The shock/boundary layer interaction on the upper propulsive surface was computed including separation. All shocks produced by the flow system were captured. Linearized block implicit (LBI) schemes were examined to determine their application to the GIM code. Pure explicit methods have stability limitations and fully implicit schemes are inherently inefficient; however, LBI schemes show promise as an effective compromise. A quasiparabolic version of the GIM code was developed using elastical parabolized Navier-Stokes methods combined with quasitime relaxation. This scheme is referred to as quasiparabolic although it applies equally well to hyperbolic supersonic inviscid flows. Second order windward differences are used in the marching coordinate and either explicit or linear block implicit time relaxation can be incorporated.

On asymptotic behavior and energy distribution for some one-dimensional non-parabolic diffusion problems

NASA Astrophysics Data System (ADS)

Kim, Seonghak; Yan, Baisheng

2018-06-01

We study some non-parabolic diffusion problems in one space dimension, where the diffusion flux exhibits forward and backward nature of the Perona–Malik, Höllig or non-Fourier type. Classical weak solutions to such problems are constructed in a way to capture some expected and unexpected properties, including anomalous asymptotic behaviors and energy dissipation or allocation. Specific properties of solutions will depend on the type of the diffusion flux, but the primary method of our study relies on reformulating diffusion equations involved as an inhomogeneous partial differential inclusion and on constructing solutions from the differential inclusion by a combination of the convex integration and Baire’s category methods. In doing so, we introduce the appropriate notion of subsolutions of the partial differential inclusion and their transition gauge, which plays a pivotal role in dealing with some specific features of the constructed weak solutions.

Monitoring of formaldehyde in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balmat, J.L.; Meadows, G.W.

1985-10-01

Any one of several monitoring methods, depending on requirement and circumstance, can be used to measure employee exposure to formaldehyde. Ordinarily, monitoring at DuPont is performed by sampling with impingers containing 1% aqueous sodium bisulfite or with silica gel tubes. The collected formaldehyde is measured spectrophotometrically after reaction with chromotropic acid. Results from studies on a selected number of formaldehyde monitoring methods reveal that reliable methods are available for area and personnel monitoring over both short term and long term. Accurate results are obtained from short-term monitoring (15 min at 1 L/min) with impingers of formaldehyde concentrations as low asmore » 0.14 ppm. The current studies show that long-term monitoring (8 hr at 0.5 L/min) can be performed accurately at concentrations as low as 0.05 ppm. Accurate results also are obtained from short-term monitoring (15 min at 500 mL/min) with silica gel tubes of concentrations as low as 0.11 ppm formaldehyde. Passive monitors provide the most convenient means of obtaining 8-hour time-weighted average (TWA) data. The Pro-Tek Formaldehyde Badge was demonstrated to reliably monitor formaldehyde concentrations varying from 0-0.5 ppm or 0-3 ppm. Investigation of the Lion Formaldemeter disclosed that instantaneous and accurate (+/- 5%) measurement of formaldehyde in air can be made over a concentration range of 0.3-5 ppm in the absence of other substances that are oxidizable in its fuel cell detector.« less

An X-band parabolic antenna based on gradient metasurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Wang; Yang, Helin, E-mail: emyang@mail.ccnu.edu.cn; Tian, Ying

We present a novel parabolic antenna by employing reflection gradient metasurface which is composed of a series of circle patches on a grounded dielectric substrate. Similar to the traditional parabolic antenna, the proposed antenna take the metasurface as a “parabolic reflector” and a patch antenna was placed at the focal point of the metasurface as a feed source, then the quasi-spherical wave emitted by the source is reflected and transformed to plane wave with high efficiency. Due to the focus effect of reflection, the beam width of the antenna has been decreased from 85.9° to 13° and the gain hasmore » been increased from 6.5 dB to 20.8 dB. Simulation and measurement results of both near and far-field plots demonstrate good focusing properties of the proposed parabolic antenna.« less

Hormonal responses of metoclopramide-treated subjects experiencing nausea or emesis during parabolic flight

NASA Technical Reports Server (NTRS)

Kohl, Randall L.

1987-01-01

The concentrations of adrenocorticotropic hormone (ACTH), vasopressin (AVP), epinephrine (EPI), and norepinephrine (NE) in 22 subjects administered 10 to 20 mg of metoclopramide prior to parabolic flight are measured. The effect of metoclopramide on motion sickness is examined. It is observed that metoclopramide is ineffective in the modulation of motion sickness due to stressful linear and angular acceleration and orbital flight, and it does not affect serum hormones prior to parabolic flight. It is detected that the serum level of AVP declines following emesis induced by parabolic flight and stressful angular acceleration; the serum levels of ACTH and EPI are elevated by parabolic flight and stressful angular acceleration; and serum NE is significantly elevated immediately following emesis. The possible roles of these hormones in the etiology of space motion sickness are discussed.

A new method of imposing boundary conditions for hyperbolic equations

NASA Technical Reports Server (NTRS)

Funaro, D.; ative.

1987-01-01

A new method to impose boundary conditions for pseudospectral approximations to hyperbolic equations is suggested. This method involves the collocation of the equation at the boundary nodes as well as satisfying boundary conditions. Stability and convergence results are proven for the Chebyshev approximation of linear scalar hyperbolic equations. The eigenvalues of this method applied to parabolic equations are shown to be real and negative.

Analysis of the Quality of Parabolic Flight

NASA Technical Reports Server (NTRS)

Lambot, Thomas; Ord, Stephan F.

2016-01-01

Parabolic flights allow researchers to conduct several 20 second micro-gravity experiments in the course of a single day. However, the measurement can have large variations over the course of a single parabola, requiring the knowledge of the actual flight environment as a function of time. The NASA Flight Opportunities program (FO) reviewed the acceleration data of over 400 parabolic flights and investigated the quality of micro-gravity for scientific purposes. It was discovered that a parabolic flight can be segmented into multiple parts of different quality and duration, a fact to be aware of when planning an experiment.

Growth of analog Al(x)Ga(1-x)As/GaAs parabolic quantum wells by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Wang, S. M.; Treideris, G.; Chen, W. Q.; Andersson, T. G.

1993-01-01

Parabolic Al(x)Ga(1-x)As/GaAs quantum wells have been grown by molecular beam epitaxy with linear ramping of the Al effusion cell temperature, where the ramping rate was carefully analyzed to avoid a flux lag. The calculated potential profile from the temperature variation was very close to the parabolic one. Low-temperature photoluminescence showed clear interband transitions up to the n = 3 sublevels. The equal energy spacing between adjacent transitions involving heavy-hole states confirmed the parabolic shape of the quantum well.

Identifying the principal coefficient of parabolic equations with non-divergent form

NASA Astrophysics Data System (ADS)

Jiang, L. S.; Bian, B. J.

2005-01-01

We deal with an inverse problem of determining a coefficient a(x, t) of principal part for second order parabolic equations with non-divergent form when the solution is known. Such a problem has important applications in a large fields of applied science. We propose a well-posed approximate algorithm to identify the coefficient. The existence, uniqueness and stability of such solutions a(x, t) are proved. A necessary condition which is a couple system of a parabolic equation and a parabolic variational inequality is deduced. Our numerical simulations show that the coefficient is recovered very well.

Photovoltaic applications of Compound Parabolic Concentrator (CPC)

NASA Technical Reports Server (NTRS)

Winston, R.

1975-01-01

The use of a compound parabolic concentrator as field collector, in conjunction with a primary focusing concentrator for photovoltaic applications is studied. The primary focusing concentrator can be a parabolic reflector, an array of Fresnel mirrors, a Fresnel lens or some other lens. Silicon solar cell grid structures are proposed that increase efficiency with concentration up to 10 suns. A ray tracing program has been developed to determine energy distribution at the exit of a compound parabolic concentrator. Projected total cost of a CPC/solar cell system will be between 4 and 5 times lower than for flat plate silicon cell arrays.

Determination of low ppm levels of dimethyl sulfate in an aqueous soluble API intermediate using liquid-liquid extraction and GC-MS.

PubMed

Zheng, Jie; Pritts, Wayne A; Zhang, Shuhong; Wittenberger, Steve

2009-12-05

Dimethyl sulfate (DMS) is an alkylating reagent commonly used in organic syntheses and pharmaceutical manufacturing processes. Due to its potential carcinogenicity, the level of DMS in the API process needs to be carefully monitored. However, in-process testing for DMS is challenging because of its reactivity and polarity as well as complex matrix effects. In this short communication, we report a GC-MS method for determination of DMS in an API intermediate that is a methyl sulfate salt. To overcome the complex matrix interference, DMS and an internal standard, d6-DMS, were extracted from the matrix with methyl tert-butyl ether. GC separation was conducted on a DB-624 column (30 m long, 0.32 mm ID, 1.8 microm film thickness). MS detection was performed on a single-quad Agilent MSD equipped with an electron impact source while the MSD signal was acquired in selected ion monitoring mode. This GC/MS method showed a linear response for DMS equivalent from 1.0 to 60 ppm. The practical quantitation limit for DMS was 1.0 ppm and the practical detection limit was 0.3 ppm. The relative standard derivation for analyte response was found as 0.1% for six injections of a working standard equivalent to 18.6 ppm of DMS. The spike recovery was ranged from 102.1 to 108.5% for a sample of API intermediate spiked with 8.0 ppm of DMS. In summary, the GC/MS method showed adequate specificity, linearity, sensitivity, repeatability and accuracy for determination of DMS in the API intermediate. This method has been successfully applied to study the efficiency of removing DMS from the process.

Clinical and cost effectiveness of eight disinfection methods for terminal disinfection of hospital isolation rooms contaminated with Clostridium difficile 027.

PubMed

Doan, L; Forrest, H; Fakis, A; Craig, J; Claxton, L; Khare, M

2012-10-01

Clostridium difficile spores can survive in the environment for months or years, and contaminated environmental surfaces are important sources of nosocomial C. difficile transmission. To compare the clinical and cost effectiveness of eight C. difficile environmental disinfection methods for the terminal cleaning of hospital rooms contaminated with C. difficile spores. This was a novel randomized prospective study undertaken in three phases. Each empty hospital room was disinfected, then contaminated with C. difficile spores and disinfected with one of eight disinfection products: hydrogen peroxide vapour (HPV; Bioquell Q10) 350-700 parts per million (ppm); dry ozone at 25 ppm (Meditrox); 1000 ppm chlorine-releasing agent (Actichlor Plus); microfibre cloths (Vermop) used in combination with and without a chlorine-releasing agent; high temperature over heated dry atomized steam cleaning (Polti steam) in combination with a sanitizing solution (HPMed); steam cleaning (Osprey steam); and peracetic acid wipes (Clinell). Swabs were inoculated on to C. difficile-selective agar and colony counts were performed pre and post disinfection for each method. A cost-effectiveness analysis was also undertaken comparing all methods to the current method of 1000 ppm chlorine-releasing agent (Actichlor Plus). Products were ranked according to the log(10) reduction in colony count from contamination phase to disinfection. The three statistically significant most effective products were hydrogen peroxide (2.303); 1000 ppm chlorine-releasing agent (2.223) and peracetic acid wipes (2.134). The cheaper traditional method of using a chlorine-releasing agent for disinfection was as effective as modern methods. Copyright © 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

40 CFR 264.1034 - Test methods and procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... gases shall be: (i) Zero air (less than 10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5... exiting control device, as determined by Method 2, dscm/h; n = Number of organic compounds in the vent gas...

40 CFR 264.1034 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... gases shall be: (i) Zero air (less than 10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5... exiting control device, as determined by Method 2, dscm/h; n = Number of organic compounds in the vent gas...

40 CFR 264.1034 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... gases shall be: (i) Zero air (less than 10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5... exiting control device, as determined by Method 2, dscm/h; n = Number of organic compounds in the vent gas...

40 CFR 264.1034 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... gases shall be: (i) Zero air (less than 10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5... exiting control device, as determined by Method 2, dscm/h; n = Number of organic compounds in the vent gas...

Enhanced propagation modeling of directional aviation noise: A hybrid parabolic equation-fast field program method

NASA Astrophysics Data System (ADS)

Rosenbaum, Joyce E.

2011-12-01

Commercial air traffic is anticipated to increase rapidly in the coming years. The impact of aviation noise on communities surrounding airports is, therefore, a growing concern. Accurate prediction of noise can help to mitigate the impact on communities and foster smoother integration of aerospace engineering advances. The problem of accurate sound level prediction requires careful inclusion of all mechanisms that affect propagation, in addition to correct source characterization. Terrain, ground type, meteorological effects, and source directivity can have a substantial influence on the noise level. Because they are difficult to model, these effects are often included only by rough approximation. This dissertation presents a model designed for sound propagation over uneven terrain, with mixed ground type and realistic meteorological conditions. The model is a hybrid of two numerical techniques: the parabolic equation (PE) and fast field program (FFP) methods, which allow for physics-based inclusion of propagation effects and ensure the low frequency content, a factor in community impact, is predicted accurately. Extension of the hybrid model to a pseudo-three-dimensional representation allows it to produce aviation noise contour maps in the standard form. In order for the model to correctly characterize aviation noise sources, a method of representing arbitrary source directivity patterns was developed for the unique form of the parabolic equation starting field. With this advancement, the model can represent broadband, directional moving sound sources, traveling along user-specified paths. This work was prepared for possible use in the research version of the sound propagation module in the Federal Aviation Administration's new standard predictive tool.

Interlaboratory comparison of chemical analysis of uranium mononitride

NASA Technical Reports Server (NTRS)

Merkle, E. J.; Davis, W. F.; Halloran, J. T.; Graab, J. W.

1974-01-01

Analytical methods were established in which the critical variables were controlled, with the result that acceptable interlaboratory agreement was demonstrated for the chemical analysis of uranium mononitride. This was accomplished by using equipment readily available to laboratories performing metallurgical analyses. Agreement among three laboratories was shown to be very good for uranium and nitrogen. Interlaboratory precision of + or - 0.04 percent was achieved for both of these elements. Oxygen was determined to + or - 15 parts per million (ppm) at the 170-ppm level. The carbon determination gave an interlaboratory precision of + or - 46 ppm at the 320-ppm level.

Numerical Optimization Using Desktop Computers

DTIC Science & Technology

1980-09-11

concentrating compound parabolic trough solar collector . Thermophysical, geophysical, optical and economic analyses were used to compute a life-cycle...third computer program, NISCO, was developed to model a nonimaging concentrating compound parabolic trough solar collector using thermophysical...concentrating compound parabolic trough Solar Collector . C. OBJECTIVE The objective of this thesis was to develop a system of interactive programs for the Hewlett

Solar Parabolic Dish Annual Technology Evaluation Report

NASA Technical Reports Server (NTRS)

1983-01-01

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1982 are summarized. Included are discussions on designs of module development including their concentrator, receiver, and power conversion subsystems. Analyses and test results, along with progress on field tests, Small Community Experiment System development, and tests at the Parabolic Dish Test Site are also included.

A New Look at an Old Work Problem

ERIC Educational Resources Information Center

Waits, Bert K.; Silver, Jerry L.

1973-01-01

Two approaches are discussed for calculating the work necessary to pump water from a conical or parabolic container. The direct method derived from the definition of work is easy to misuse, as illustrated by a student's incorrect solution. (JP)

Fabrication of parabolic cylindrical microlens array by shaped femtosecond laser

NASA Astrophysics Data System (ADS)

Luo, Zhi; Yin, Kai; Dong, Xinran; Duan, Ji'an

2018-04-01

A simple and efficient technique for fabricating parabolic cylindrical microlens arrays (CMLAs) on the surface of fused silica by shaped femtosecond (fs) laser direct-writing is demonstrated. By means of spatially shaping of a Gaussian fs laser beam to a Bessel distribution, an inversed cylindrical shape laser intensity profile is formed in a specific cross-sectional plane among the shaped optical field. Applying it to experiments, large area close-packed parabolic CMLAs with line-width of 37.5 μm and array size of about 5 × 5 mm are produced. The cross-sectional outline of obtained lenslets has a satisfied parabolic profile and the numerical aperture (NA) of lenslets is more than 0.35. Furthermore, the focusing performance of the fabricated CMLA is also tested in this work and it has been demonstrated that the focusing power of the CMLA with a parabolic profile is better than that with a semi-circular one.

Higher and lowest order mixed finite element approximation of subsurface flow problems with solutions of low regularity

NASA Astrophysics Data System (ADS)

Bause, Markus

2008-02-01

In this work we study mixed finite element approximations of Richards' equation for simulating variably saturated subsurface flow and simultaneous reactive solute transport. Whereas higher order schemes have proved their ability to approximate reliably reactive solute transport (cf., e.g. [Bause M, Knabner P. Numerical simulation of contaminant biodegradation by higher order methods and adaptive time stepping. Comput Visual Sci 7;2004:61-78]), the Raviart- Thomas mixed finite element method ( RT0) with a first order accurate flux approximation is popular for computing the underlying water flow field (cf. [Bause M, Knabner P. Computation of variably saturated subsurface flow by adaptive mixed hybrid finite element methods. Adv Water Resour 27;2004:565-581, Farthing MW, Kees CE, Miller CT. Mixed finite element methods and higher order temporal approximations for variably saturated groundwater flow. Adv Water Resour 26;2003:373-394, Starke G. Least-squares mixed finite element solution of variably saturated subsurface flow problems. SIAM J Sci Comput 21;2000:1869-1885, Younes A, Mosé R, Ackerer P, Chavent G. A new formulation of the mixed finite element method for solving elliptic and parabolic PDE with triangular elements. J Comp Phys 149;1999:148-167, Woodward CS, Dawson CN. Analysis of expanded mixed finite element methods for a nonlinear parabolic equation modeling flow into variably saturated porous media. SIAM J Numer Anal 37;2000:701-724]). This combination might be non-optimal. Higher order techniques could increase the accuracy of the flow field calculation and thereby improve the prediction of the solute transport. Here, we analyse the application of the Brezzi- Douglas- Marini element ( BDM1) with a second order accurate flux approximation to elliptic, parabolic and degenerate problems whose solutions lack the regularity that is assumed in optimal order error analyses. For the flow field calculation a superiority of the BDM1 approach to the RT0 one is observed, which however is less significant for the accompanying solute transport.

Evaluation on determination of iodine in coal by energy dispersive X-ray fluorescence

USGS Publications Warehouse

Wang, B.; Jackson, J.C.; Palmer, C.; Zheng, B.; Finkelman, R.B.

2005-01-01

A quick and inexpensive method of relative high iodine determination from coal samples was evaluated. Energy dispersive X-ray fluorescence (EDXRF) provided a detection limit of about 14 ppm (3 times of standard deviations of the blank sample), without any complex sample preparation. An analytical relative standard deviation of 16% was readily attainable for coal samples. Under optimum conditions, coal samples with iodine concentrations higher than 5 ppm can be determined using this EDXRF method. For the time being, due to the general iodine concentrations of coal samples lower than 5 ppm, except for some high iodine content coal, this method can not effectively been used for iodine determination. More work needed to meet the requirement of determination of iodine from coal samples for this method. Copyright ?? 2005 by The Geochemical Society of Japan.

Optical Phase Recovery and Locking in a PPM Laser Communication Link

NASA Technical Reports Server (NTRS)

Aveline, David C.; Yu, Nan; Farr, William H.

2012-01-01

Free-space optical communication holds great promise for future space missions requiring high data rates. For data communication in deep space, the current architecture employs pulse position modulation (PPM). In this scheme, the light is transmitted and detected as pulses within an array of time slots. While the PPM method is efficient for data transmission, the phase of the laser light is not utilized. The phase coherence of a PPM optical signal has been investigated with the goal of developing a new laser communication and ranging scheme that utilizes optical coherence within the established PPM architecture and photon-counting detection (PCD). Experimental measurements of a PPM modulated optical signal were conducted, and modeling code was developed to generate random PPM signals and simulate spectra via FFT (Fast Fourier Transform) analysis. The experimental results show very good agreement with the simulations and confirm that coherence is preserved despite modulation with high extinction ratios and very low duty cycles. A real-time technique has been developed to recover the phase information through the mixing of a PPM signal with a frequency-shifted local oscillator (LO). This mixed signal is amplified, filtered, and integrated to generate a voltage proportional to the phase of the modulated signal. By choosing an appropriate time constant for integration, one can maintain a phase lock despite long dark times between consecutive pulses with low duty cycle. A proof-of-principle demonstration was first achieved with an RF-based PPM signal and test setup. With the same principle method, an optical carrier within a PPM modulated laser beam could also be tracked and recovered. A reference laser was phase-locked to an independent pulsed laser signal with low-duty-cycle pseudo-random PPM codes. In this way, the drifting carrier frequency in the primary laser source is tracked via its phase change in the mixed beat note, while the corresponding voltage feedback maintains the phase lock between the two laser sources. The novelty and key significance of this work is that the carrier phase information can be harnessed within an optical communication link based on PPM-PCD architecture. This technology development could lead to quantum-limited efficient performance within the communication link itself, as well as enable high-resolution optical tracking capabilities for planetary science and spacecraft navigation.

Determination of arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc in geological materials by atomic-absorption spectrometry

USGS Publications Warehouse

Viets, J.G.; O'Leary, R. M.; Clark, Robert J.

1984-01-01

Arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc are very useful elements in geochemical exploration. In the proposed method, geological samples are fused with potassium pyrosulphate and the fusate is dissolved in a solution of hydrochloric acid, ascorbic acid and potassium iodide. When this solution is shaken with a 10% V/V Aliquat 336 - isobutyl methyl ketone organic phase, the nine elements of interest are selectively partitioned in the organic phase. All nine elements can then be determined in the organic phase using flame atomic-absorption spectrometry. The method is rapid and allows the determination of Ag and Cd at levels down to 0.1 p.p.m., Cu, Mo, and Zn down to 0.5 p.p.m., Pb, Bi and Sb down to 1 p.p.m. and As down to 5 p.p.m. in geological materials.

Content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured in modern farm at BLUPPB, Karawang, West Java

NASA Astrophysics Data System (ADS)

Takarina, N. D.; Rahman, A.; Siswanting, T.; Pin, T. J.

2018-03-01

Heavy metal is one of the hazardous substances which often found in shrimp farm. Since this shrimp become mostly favorable food, it is necessary to determine the content of metal in this shrimps. This research was aimed to determine the content of Cr, Cu, Pb, and Zn on Pacific white shrimp cultured on the modern farm at BLUPPB, Karawang, West Java. Samples were taken from five farms. During transport, samples were kept in a more relaxed box. Farms used were designed using black plastic as the bottom layer to separate contact with soil. Heavy metal of Cr, Cu, Pb, and Zn on shrimp meat was analyzed using Atomic Absorption Spectrophotometry method. The content of Cr was ranged from 0.06 – 0.38 ppm and Pb were 0.02 – 0.05 ppm. The content of Cu was ranged from 1.89 – 15.25 ppm and Zn were 2.16 – 3.92 ppm. According to government rules and literature, those content were below a threshold which was 0.4 ppm for Cu, 0.5 ppm for Pb, 20 ppm for Cu and 0.2 ppm for Zn.

Space Qualification Testing of a Shape Memory Alloy Deployable CubeSat Antenna

DTIC Science & Technology

2016-09-15

the SMA deployment in the space environment. The HCT QHA successfully passed all required NASA General Environmental Verification Standards space... NASA /JPL parabolic deployable antenna design [28] .................. 19 Figure 11. SERC and NASA /JPL parabolic antenna prototype [28...19 Figure 12. SERC and NASA /JPL parabolic antenna stowed configuration [28] ............. 20 Figure 13. JPL KaPDA antenna [29

Schottky diode model for non-parabolic dispersion in narrow-gap semiconductor and few-layer graphene

NASA Astrophysics Data System (ADS)

Ang, Yee Sin; Ang, L. K.; Zubair, M.

Despite the fact that the energy dispersions are highly non-parabolic in many Schottky interfaces made up of 2D material, experimental results are often interpreted using the conventional Schottky diode equation which, contradictorily, assumes a parabolic energy dispersion. In this work, the Schottky diode equation is derived for narrow-gap semiconductor and few-layer graphene where the energy dispersions are highly non-parabolic. Based on Kane's non-parabolic band model, we obtained a more general Kane-Schottky scaling relation of J (T2 + γkBT3) which connects the contrasting J T2 in the conventional Schottky interface and the J T3 scaling in graphene-based Schottky interface via a non-parabolicity parameter, γ. For N-layer graphene of ABC -stacking and of ABA -stacking, the scaling relation follows J T 2 / N + 1 and J T3 respectively. Intriguingly, the Richardson constant extracted from the experimental data using an incorrect scaling can differ with the actual value by more than two orders of magnitude. Our results highlights the importance of using the correct scaling relation in order to accurately extract important physical properties, such as the Richardson constant and the Schottky barrier's height.

Simultaneous gas chromatographic determination of four toxic gases generally present in combustion atmospheres.

PubMed

Endecott, B R; Sanders, D C; Chaturvedi, A K

1996-01-01

The measurement of combustion gases produced by burning aircraft cabin materials poses a continuing limitation for smoke toxicity research. Because toxic effects of gases depend on both their concentrations and the duration of exposure, frequent atmosphere sampling is necessary to define the gas concentration-exposure time curve. A gas chromatographic (GC) method was developed for the simultaneous analyses of carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), and hydrogen cyanide (HCN). The method used an MTI M200 dual-column gas chromatograph equipped with 4-m molecular sieve-5A and 8-m PoraPlot-U wall-coated capillary columns and two low-volume, high-sensitivity thermal conductivity detectors. Detectability (in parts per million [ppm]) and retention times (in seconds) for the gases were as follows: CO, 100 ppm, 28 s; H2S, 50 ppm, 26 s; SO2, 125 ppm, 76 s; and HCN, 60 ppm, 108 s. The method was effective for determining these gases in mixtures and in the combustion atmospheres generated by burning wool (CO, HCN, and H2S) and modacrylic fabrics (CO and HCN). Common atmospheric gaseous or combustion products (oxygen, carbon dioxide, nitrogen, water vapor, and other volatiles) did not interfere with the analyses. However, filtration of the combustion atmospheres was necessary to prevent restriction of the GC sampling inlet by smoke particulates. The speed, sensitivity, and selectivity of this method make it suitable for smoke toxicity research and for evaluating performance of passenger protective breathing equipment. Also, this method can potentially be modified to analyze these gases when they are liberated from biosamples.

Stoichiometric determination of moisture in edible oils by Mid-FTIR spectroscopy.

PubMed

van de Voort, F R; Tavassoli-Kafrani, M H; Curtis, J M

2016-04-28

A simple and accurate method for the determination of moisture in edible oils by differential FTIR spectroscopy has been devised based on the stoichiometric reaction of the moisture in oil with toluenesulfonyl isocyanate (TSI) to produce CO2. Calibration standards were devised by gravimetrically spiking dry dioxane with water, followed by the addition of neat TSI and examination of the differential spectra relative to the dry dioxane. In the method, CO2 peak area changes are measured at 2335 cm(-1) and were shown to be related to the amount of moisture added, with any CO2 inherent to residual moisture in the dry dioxane subtracted ratioed out. CO2 volatility issues were determined to be minimal, with the overall SD of dioxane calibrations being ∼18 ppm over a range of 0-1000 ppm. Gravimetrically blended dry and water-saturated oils analysed in a similar manner produced linear CO2 responses with SD's of <15 ppm on average. One set of dry-wet blends was analysed in duplicate by FTIR and by two independent laboratories using coulometric Karl Fischer (KF) procedures. All 3 methods produced highly linear moisture relationships with SD's of 7, 16 and 28 ppm, respectively over a range of 200-1500 ppm. Although the absolute moisture values obtained by each method did not exactly coincide, each tracked the expected moisture changes proportionately. The FTIRTSI-H2O method provides a simple and accurate instrumental means of determining moisture in oils rivaling the accuracy and specificity of standard KF procedures and has the potential to be automated. It could also be applied to other hydrophobic matrices and possibly evolve into a more generalized method, if combined with polar aprotic solvent extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

A new method to search for high-redshift clusters using photometric redshifts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castignani, G.; Celotti, A.; Chiaberge, M.

2014-09-10

We describe a new method (Poisson probability method, PPM) to search for high-redshift galaxy clusters and groups by using photometric redshift information and galaxy number counts. The method relies on Poisson statistics and is primarily introduced to search for megaparsec-scale environments around a specific beacon. The PPM is tailored to both the properties of the FR I radio galaxies in the Chiaberge et al. sample, which are selected within the COSMOS survey, and to the specific data set used. We test the efficiency of our method of searching for cluster candidates against simulations. Two different approaches are adopted. (1) Wemore » use two z ∼ 1 X-ray detected cluster candidates found in the COSMOS survey and we shift them to higher redshift up to z = 2. We find that the PPM detects the cluster candidates up to z = 1.5, and it correctly estimates both the redshift and size of the two clusters. (2) We simulate spherically symmetric clusters of different size and richness, and we locate them at different redshifts (i.e., z = 1.0, 1.5, and 2.0) in the COSMOS field. We find that the PPM detects the simulated clusters within the considered redshift range with a statistical 1σ redshift accuracy of ∼0.05. The PPM is an efficient alternative method for high-redshift cluster searches that may also be applied to both present and future wide field surveys such as SDSS Stripe 82, LSST, and Euclid. Accurate photometric redshifts and a survey depth similar or better than that of COSMOS (e.g., I < 25) are required.« less

Analysis of Phenolic Antioxidants in Navy Mobility Fuels by Gas Chromatography-Mass Spectrometry

DTIC Science & Technology

2013-06-19

8.0 LITERATURE CITED .........................................................................................14 APPENDIX A: Calibration Curves for...chromatogram from an F-76 diesel fuel containing 24 ppm of the AO-37 additive package, analyzed using single column GC-MS-SIM method...sulfur diesel fuel containing 6.25 ppm of the AO-37 additive package, analyzed using dual column Deans switch GC-MS-SIM method

Dark optical, singular solitons and conservation laws to the nonlinear Schrödinger’s equation with spatio-temporal dispersion

NASA Astrophysics Data System (ADS)

Inc, Mustafa; Aliyu, Aliyu Isa; Yusuf, Abdullahi

2017-05-01

This paper studies the dynamics of solitons to the nonlinear Schrödinger’s equation (NLSE) with spatio-temporal dispersion (STD). The integration algorithm that is employed in this paper is the Riccati-Bernoulli sub-ODE method. This leads to dark and singular soliton solutions that are important in the field of optoelectronics and fiber optics. The soliton solutions appear with all necessary constraint conditions that are necessary for them to exist. There are four types of nonlinear media studied in this paper. They are Kerr law, power law, parabolic law and dual law. The conservation laws (Cls) for the Kerr law and parabolic law nonlinear media are constructed using the conservation theorem presented by Ibragimov.

Numerical solution of supersonic three-dimensional free-mixing flows using the parabolic-elliptic Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Hirsh, R. S.

1976-01-01

A numerical method is presented for solving the parabolic-elliptic Navier-Stokes equations. The solution procedure is applied to three-dimensional supersonic laminar jet flow issuing parallel with a supersonic free stream. A coordinate transformation is introduced which maps the boundaries at infinity into a finite computational domain in order to eliminate difficulties associated with the imposition of free-stream boundary conditions. Results are presented for an approximate circular jet, a square jet, varying aspect ratio rectangular jets, and interacting square jets. The solution behavior varies from axisymmetric to nearly two-dimensional in character. For cases where comparisons of the present results with those obtained from shear layer calculations could be made, agreement was good.

SETI-ITALIA 2008: On-going searches and future prospects

NASA Astrophysics Data System (ADS)

Montebugnoli, S.; Bartolini, M.; Bianchi, G.; Cosmovici, C.; Monari, J.; Orlati, A.; Perini, F.; Pluchino, S.; Pupillo, G.; Salerno, E.; Schillirò, F.; Zoni, L.

2010-12-01

The Medicina Radioastronomical Station is located nearby Bologna, in Italy. It consists of two receiving antennas currently dedicated to the astronomical research at radio frequencies. The 32 m diameter parabolic dish performs observations from 1.4 to 22 GHz whereas the Northern Cross (a 30.000 m 2 wide T-shaped array transit antenna) works at 408 MHz. So far SETI observations have been performed using a SERENDIP IV high resolution spectrometer connected to the parabolic antenna. Data acquisition were performed meanwhile the antenna was employed in ordinary astronomical observations (piggy-back mode). An innovative method to search for possible extraterrestrial signals could be provided by using the UHF Northern Cross transit telescope. In this paper observational modalities and the required technological set-up are investigated.

FIBER OPTICS: Method of calculation of the propagation constant for guided modes

NASA Astrophysics Data System (ADS)

Ardasheva, L. I.; Sadykov, Nail R.; Chernyakov, V. E.

1992-09-01

A new method of calculating the propagation constants and wave eigenfunctions of guided modes is proposed for axisymmetric translationally invariant fiber-optic waveguides with arbitrary refractive index profiles. The method is based on solving a parabolic scalar wave equation. A comparison is made between the numerical solution under steady-state conditions and the eigenfunctions of single-mode and multimode waveguides.

Coalescing neutron stars - gravitational waves from polytropic models.

NASA Astrophysics Data System (ADS)

Ruffert, M.; Rampp, M.; Janka, H.-T.

1997-05-01

The dynamics, time evolution of the mass distribution, and gravitational wave signature of coalescing neutron stars described by polytropes are compared with three simulations published previously: (a) "Run 2" of Zhuge et al. (1994PhRvD..50.6247Z), (b) "Model III" of Shibata et al. (1992, Prog, Theor. Phys. 88, 1079), and (c) "Model A64" of Ruffert et al. (1996A&A...311..532R). We aim at studying the differences due to the use of different numerical methods, different implementations of the gravitational wave backreaction, and different equations of state. We integrate the three-dimensional Newtonian equations of hydrodynamics by the Riemann-solver based "Piecewise Parabolic Method" on an equidistant Cartesian grid. Comparison (a) confronts the results of our grid-based PPM scheme with those from an SPH code. We find that due to the lower numerical viscosity of the PPM code, the post-merging oscillations and pulsations can be followed for a longer time and lead to larger secondary and tertiary maxima of the gravitational wave luminosity and to a stronger peak of the gravitational wave spectrum at a frequency of about f=~1.8KHz when compared to the results of Zhuge et al. (1994PhRvD..50.6247Z). In case (b) two grid based codes with the same backreaction formalism but differing hydrodynamic integrators and slightly different initial conditions are compared. Instead of rotationally deformed initial neutron stars we use spherically shaped stars. Satisfactory agreement of the amplitude of the gravitational wave luminosity is established, although due to the different initial conditions a small time delay develops in the onset of the dynamical instability setting in when the two stars come very close. In (c) we find that using a polytropic equation of state instead of the high-density equation of state of Lattimer & Swesty (1991, Nucl. Phys. A535, 331) employed by Ruffert et al. (1996A&A...311..532R) does not change the overall dynamical evolution of the merger and yields agreement of the gravitational wave signature to within 20% accuracy. Whereas the polytropic law describes the dynamical behaviour of the bulk of the matter at and above nuclear density sufficiently well, we, however, find clear differences of the structure and evolution of the outer layers of the neutron stars where the stiffness of the equation of state is largely overestimated. This has important implications for questions like mass loss and disk formation during the merging of binary neutron stars.

Larvicidal and repellent potential of Moringa oleifera against malarial vector, Anopheles stephensi Liston (Insecta: Diptera: Culicidae)

PubMed Central

Prabhu, K; Murugan, K; Nareshkumar, A; Ramasubramanian, N; Bragadeeswaran, S

2011-01-01

Objective To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera (M. oleifera) plant seeds against malarial vector Anopheles stephensi (A. stephensi) mosquitoes at different concentrations (20, 40, 60, 80 and 100 ppm). Methods M. oleifera was collected from the area of around Bharathiar University, Coimbatore. The dried plant materials were powdered by an electrical blender. From each sample, 100 g of the plant material were extracted with 300 mL of methanol for 8 h in a Soxhlet apparatus. The extracts were evaporated to dryness in rotary vacuum evaporator to yield 122 mg and 110 mg of dark greenish material (residue) from Arcang amara and Ocimum basilicum, respectively. One gram of the each plant residue was dissolved separately in 100 mL of acetone (stock solution) from which different concentrations, i.e., 20, 40, 60, 80 and 100 ppm were prepared. Results Larvicidal activity of M. oleifera exhibited in the first to fourth instar larvae of the A. stephensi, and the LC50 and LC90 values were 57.79 ppm and 125.93 ppm for the first instar, 63.90 ppm and 133.07 ppm for the second instar, 72.45 ppm and 139.82 ppm for the third instar, 78.93 ppm and 143.20 ppm for the fourth instar, respectively. During the pupal stage the methanolic extract of M. oleifera showed that the LC50 and LC90 values were 67.77 ppm and 141.00 ppm, respectively. Conclusions The present study indicates that the phytochemicals derived from M. oleifera seeds extracts are effective mosquito vector control agents and the plant extracts may be used for further integrated pest management programs. PMID:23569741

[Effects of parabolic flight on redox status in SH-SY5Y cells].

PubMed

Bi, Lei; Qu, Li-Na; Huang, Zeng-Ming; Wang, Chun-Yan; Li, Qi; Tan, Ying-Jun; Li, Ying-Hui

2009-10-25

Space flight is known to produce a number of neurological disturbances. The etiology is unknown, but it may involve increased oxidative stress. A line of experimental evidence indicates that space flight may disrupt antioxidant defense system and result in increased oxidative stress. In vitro studies found that abundant of NO was produced in rat pheochromocytoma (PC12) cells, SHSY5Y neuroblastoma cells, and protein nitration was increased in PC12 cells within a simulated microgravity rotating wall bioreactor high aspect ratio vessel system or clinostat system. In the present study, we observed the change of redox status in SH-SY5Y cells after parabolic flight, and studied the effects of key redox molecule, thioredoxin (TRX), during the altered gravity. SH-SY5Y cells were divided into four groups: control cells, control cells transfected with TRX, flight cells and flight cells transfected with TRX. The expression levels of 3-nitrotyrosine (3-NT), inducible nitric oxide synthase (iNOS), TRX and thioredoxin reductase (TRXR) were observed by immunocytochemical method. It was shown that after parabolic flight, the staining of 3-NT and TRX were enhanced, while the expression level of TRXR was down-regulated compared with control. As for flight cells transfected with TRX, the staining of 3-NT and iNOS were weakened compared with flight cells. These results obtained suggest that altered gravity may increase protein nitration, down-regulate TRXR and elicit oxidative stress in SH-SY5Y cells, while TRX transfection could partly protect cells against oxidative stress induced by parabolic flight.

Parabolic replicator dynamics and the principle of minimum Tsallis information gain

PubMed Central

2013-01-01

Background Non-linear, parabolic (sub-exponential) and hyperbolic (super-exponential) models of prebiological evolution of molecular replicators have been proposed and extensively studied. The parabolic models appear to be the most realistic approximations of real-life replicator systems due primarily to product inhibition. Unlike the more traditional exponential models, the distribution of individual frequencies in an evolving parabolic population is not described by the Maximum Entropy (MaxEnt) Principle in its traditional form, whereby the distribution with the maximum Shannon entropy is chosen among all the distributions that are possible under the given constraints. We sought to identify a more general form of the MaxEnt principle that would be applicable to parabolic growth. Results We consider a model of a population that reproduces according to the parabolic growth law and show that the frequencies of individuals in the population minimize the Tsallis relative entropy (non-additive information gain) at each time moment. Next, we consider a model of a parabolically growing population that maintains a constant total size and provide an “implicit” solution for this system. We show that in this case, the frequencies of the individuals in the population also minimize the Tsallis information gain at each moment of the ‘internal time” of the population. Conclusions The results of this analysis show that the general MaxEnt principle is the underlying law for the evolution of a broad class of replicator systems including not only exponential but also parabolic and hyperbolic systems. The choice of the appropriate entropy (information) function depends on the growth dynamics of a particular class of systems. The Tsallis entropy is non-additive for independent subsystems, i.e. the information on the subsystems is insufficient to describe the system as a whole. In the context of prebiotic evolution, this “non-reductionist” nature of parabolic replicator systems might reflect the importance of group selection and competition between ensembles of cooperating replicators. Reviewers This article was reviewed by Viswanadham Sridhara (nominated by Claus Wilke), Puushottam Dixit (nominated by Sergei Maslov), and Nick Grishin. For the complete reviews, see the Reviewers’ Reports section. PMID:23937956

Elastic parabolic equation solutions for underwater acoustic problems using seismic sources.

PubMed

Frank, Scott D; Odom, Robert I; Collis, Jon M

2013-03-01

Several problems of current interest involve elastic bottom range-dependent ocean environments with buried or earthquake-type sources, specifically oceanic T-wave propagation studies and interface wave related analyses. Additionally, observed deep shadow-zone arrivals are not predicted by ray theoretic methods, and attempts to model them with fluid-bottom parabolic equation solutions suggest that it may be necessary to account for elastic bottom interactions. In order to study energy conversion between elastic and acoustic waves, current elastic parabolic equation solutions must be modified to allow for seismic starting fields for underwater acoustic propagation environments. Two types of elastic self-starter are presented. An explosive-type source is implemented using a compressional self-starter and the resulting acoustic field is consistent with benchmark solutions. A shear wave self-starter is implemented and shown to generate transmission loss levels consistent with the explosive source. Source fields can be combined to generate starting fields for source types such as explosions, earthquakes, or pile driving. Examples demonstrate the use of source fields for shallow sources or deep ocean-bottom earthquake sources, where down slope conversion, a known T-wave generation mechanism, is modeled. Self-starters are interpreted in the context of the seismic moment tensor.

Effect of reactive element oxide coating on the high temperature oxidation behaviour of FeCrAl alloys

NASA Astrophysics Data System (ADS)

Cueff, R.; Buscail, H.; Caudron, E.; Riffard, F.; Issartel, C.; El Messki, S.

2004-05-01

The influence of yttrium oxide coating (processed by the sol-gel method) on the oxidation behaviour of a commercial FeCrAl alloy (Kanthal A1) has been investigated during isothermal exposures in air at 1373 K. The scale growth kinetics of the uncoated alloy obey a parabolic rate law during the whole oxidation test, whereas the kinetic curves of the Y-coated specimen exhibit an initial transient stage for the first few hours, followed by a parabolic regime. The yttrium sol-gel coating deposited on the bare alloy does not provide the beneficial effect usually ascribed to reactive elements. No oxidation rate improvement of the coated alloy is observed, the parabolic rate constant values are strictly identical for both specimens. In situ X-ray diffraction reveals a marked influence of the reactive element on the composition of the oxide scale. The oxide layer formed on the yttrium-coated specimen comprised, in addition to α-alumina which is the main oxide also identified on the bare specimen, the presence of yttrium aluminates (YAlO 3, Y 3Al 5O 12) located in the outermost part of the layer.

Exciton binding energy in a pyramidal quantum dot

NASA Astrophysics Data System (ADS)

Anitha, A.; Arulmozhi, M.

2018-05-01

The effects of spatially dependent effective mass, non-parabolicity of the conduction band and dielectric screening function on exciton binding energy in a pyramid-shaped quantum dot of GaAs have been investigated by variational method as a function of base width of the pyramid. We have assumed that the pyramid has a square base with area a× a and height of the pyramid H=a/2. The trial wave function of the exciton has been chosen according to the even mirror boundary condition, i.e. the wave function of the exciton at the boundary could be non-zero. The results show that (i) the non-parabolicity of the conduction band affects the light hole (lh) and heavy hole (hh) excitons to be more bound than that with parabolicity of the conduction band, (ii) the dielectric screening function (DSF) affects the lh and hh excitons to be more bound than that without the DSF and (iii) the spatially dependent effective mass (SDEM) affects the lh and hh excitons to be less bound than that without the SDEM. The combined effects of DSF and SDEM on exciton binding energy have also been calculated. The results are compared with those available in the literature.

Determination of molybenum in soils and rocks: A geochemical semimicro field method

USGS Publications Warehouse

Ward, F.N.

1951-01-01

Reconnaissance work in geochemical prospecting requires a simple, rapid, and moderately accurate method for the determination of small amounts of molybdenum in soils and rocks. The useful range of the suggested procedure is from 1 to 32 p.p.m. of molybdenum, but the upper limit can be extended. Duplicate determinations on eight soil samples containing less than 10 p.p.m. of molybdenum agree within 1 p.p.m., and a comparison of field results with those obtained by a conventional laboratory procedure shows that the method is sufficiently accurate for use in geochemical prospecting. The time required for analysis and the quantities of reagents needed have been decreased to provide essentially a "test tube" method for the determination of molybdenum in soils and rocks. With a minimum amount of skill, one analyst can make 30 molybdenum determinations in an 8-hour day.

Passive particle dosimetry. [silver halide crystal growth

NASA Technical Reports Server (NTRS)

Childs, C. B.

1977-01-01

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Comparison of the incipient lesion enamel fluoride uptake from various prescription and OTC fluoride toothpastes and gels.

PubMed

Schemehorn, B R; DiMarino, J C; Movahed, N

2014-01-01

The objective of this in vitro study was to compare the fluoride uptake into incipient enamel lesions of a novel 970 ppm F- ion SnF2 over-the-counter (OTC) gel (Enamelon Preventive Treatment Gel) and a novel 1150 ppm F- ion OTC toothpaste (Enamelon), each delivering amorphous calcium phosphate (ACP), to the uptake from two different prescription strength, 5000 ppm F- ion dentifrices containing tri-calcium phosphate (TCP) and a prescription 900 ppm F- ion paste containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). The test procedure followed method #40 in the US-FDA Anticaries Drug Products for OTC Human Use, Final Monograph testing procedures. Eight sets of twelve incisor enamel cores were mounted in Plexiglas rods and the exposed surfaces were polished. The indigenous fluoride levels of each specimen were determined prior to treatment. The treatments were performed using slurries of a negative control (water) and the following products applied to a set of sound enamel cores: 5000 ppm F- ion, sodium fluoride (NaF) prescription (Rx) dentifrice "A" containing TCP; 5000 ppm F- ion, NaF Rx dentifrice "B" containing TCP; 900 ppm F- ion, NaF Rx paste with CPP-ACP; 1150 ppm F- ion, NaF OTC toothpaste; 1150 ppm F- ion, stannous fluoride (SnF2) OTC toothpaste delivering ACP (Enamelon); 1100 ppm F- ion, SnF2 OTC toothpaste; and 970 ppm F- ion, SnF2 OTC gel delivering ACP (Enamelon Preventive Treatment Gel). The twelve specimens of each group were immersed into 25 ml of their assigned slurry with constant stirring (350 rpm) for 30 minutes. Following treatment, one layer of enamel was removed from each specimen and analyzed for fluoride and calcium. The pre-treatment fluoride (indigenous) level of each specimen was subtracted from the post-treatment value to determine the change in enamel fluoride due to the test treatment. The increase in the average fluoride uptake for treated enamel cores was: 10,263 ± 295 ppm for the 970 ppm F- ion, Enamelon Preventive Treatment Gel; 7,016 ± 353 ppm for the 1150 ppm F- ion Enamelon Toothpaste; 4,138 ± 120 ppm for the 5000 ppm F- ion, NaF prescription dentifrice "A" with TCP; 3801 ± 121 ppm for the 5000 ppm F- ion, NaF prescription dentifrice "B" with TCP; 2,647 ± 57 ppm for the 1100 ppm F- ion, SnF2 OTC toothpaste; 1470 ± 40 ppm for the 1150 ppm F- ion, NaF OTC toothpaste; and 316 ± 9 ppm for the 900 ppm F- ion, NaF paste with CPP-ACP. The differences among all the products tested were statistically significant (p < 0.05), except for the two 5000 ppm F- ion products with TCP that were not statistically different from one another, and the 900 ppm F ion, NaF paste with CPP-ACP that was not statistically different from the negative water control. The Enamelon products (970 ppm and 150 ppm F ion, SnF2OTC dentifrices) delivering ACP provide statistically significantly more fluoride to incipient enamel lesions than two prescription strength 5000 ppm F- ion toothpastes containing TCP, the 900 ppm F- ion prescription paste containing CPP-ACP, and the other OTC toothpastes compared in this study.

Low Sidelobe Scanning Beams for Parabolic Reflectors,

DTIC Science & Technology

Parabolic antennas, *Sidelobes, *Electronic scanners, Parabolas, Far field, Antenna feeds , Reflectors, Low level, Amplitude, Distortion, Configurations, Secondary, Compensation, Feeding , Symposia, Taper

A novel method for the determination of synthetic colors in ice cream samples.

PubMed

Tripathi, Meenakshi; Khanna, Subhash K; Das, Mukul

2004-01-01

A simple method has been developed for the extraction, separation, and determination of synthetic colors in ice cream samples. The process involves the breakdown of emulsion by neutral detergents (Triton X-100 and Tween 20) followed by extraction with petroleum ether for removal of fat. The aqueous colored solution obtained is treated with 5% acetic acid, and the uptake of color is carried out by a wool-dyeing technique. The color is eluted from the wool with 5% ammonia solution, the solution is evaporated to dryness, and the residue is dissolved in 60% ethanol for paper chromatography using trisodium citrate-ammonia-water (2 + 5 + 95, w/v/v) as the mobile phase. The colored spots from the paper chromatogram are cut and eluted with 60% ethanol, and the absorbance is measured at the respective lambda maximum corresponding to the Rf value of the appropriate standard. The recoveries of 6 colors, including sunset yellow FCF (SSYFCF), tartrazine, carmoisine, ponceau 4R, brilliant blue FCF (BBFCF), and fast green FCF from spiked samples with either detergent were found to be >90%. However, recoveries of erythrosine were 21 and 65% with Triton X-100 and Tween 20, respectively. Indigo carmine could not be recovered at all because of its fugitive property in 5% ammonia solution, which is used to strip the color from the wool. The sensitivity of the method with the use of Tween 20 is 1 ppm (1 microg/g) for the colors in spiked ice cream samples. With this method, we analyzed samples of 20 branded colored ice cream. The results showed the presence of tartrazine (8.4-43.3 ppm), SSYFCF (23.5-117.6 ppm), carmoisine (traces-53.2 ppm), erythrosine (3.5 ppm), and BBFCF (4.1 ppm) in the ice cream samples. Apart from 2 samples of tuttifruity, all of the ice cream samples showed the presence of permitted synthetic colors below the permissible level of 100 ppm established by the Prevention of Food Adulteration Act of India.

Rapid analysis of 2,4-D in soil samples by modified Soxhlet apparatus using HPLC with UV detection.

PubMed

Kashyap, Sanjay M; Pandya, Girish H; Kondawar, Vivek K; Gabhane, Sanjay S

2005-02-01

The 2,4-dichlorophenoxy acetic acid (2,4-D) is used as a systemic herbicide to control broadleaf weeds in wheat, corn, range land/pasture land, sorghum, and barley. In this study, a fast and efficient method is developed by selection of modified extraction apparatus and high-performance liquid chromatography (HPLC)-UV conditions for the determination of 2,4-D in soil samples. The method is applied to the study of soil samples collected from the agricultural field. The herbicide is extracted from soil samples by acetonitrile in a modified Soxhlet apparatus. The advantages of the apparatus are that it uses small volume of organic solvent, reduced time of extraction, and better recovery of the analyte. The extract is filtered using a very fine microfiber paper. The total extract is concentrated in a rotatory evaporator, dried under ultrahigh pure N2, and finally reconstituted in 1 mL of acetonitrile. HPLC-UV at 228 nm is used for analysis. The herbicide is identified and quantitated using the HPLC system. The method is validated by the analysis of spiked soil samples. Recoveries obtained varied from 85% to 100% for spiked soil samples. The limit of quantitation (LOQ) and the limit of detection (LOD) are 0.010 and 0.005 parts per million (ppm), respectively, for spiked soil samples. The LOQ and LOD are 0.006 and 0.003 ppm for unspiked soil samples. The measured concentrations of 2,4-D in spiked soil samples are between 0.010 and 0.020 ppm with an average of 0.016 +/- 0.003 ppm. For unspiked soil samples it is between 0.006 ppm and 0.012 ppm with an average of 0.009 +/- 0.002 ppm. The measured concentrations of 2,4-D in soil samples are generally low and do not exceed the regulatory agencies guidelines.

Effects of dressing and cooking on DDT concentrations in certain fish from Lake Michigan

USGS Publications Warehouse

Reinert, Robert E.; Stewart, Donald; Seagran, Harry L.

1972-01-01

Concentrations of DDT residues were highest in parts of the body with the highest oil content in four species of fish from Lake Michigan: yellow perch (Perca flavescens), bloater (Coregonus hoyi), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch). Dressing reduced the DDT residues and oil content by more than 90% in yellow perch but had little effect in the other three species. The concentration of DDT residues in bloaters was changed little by smoking but was reduced 64–72% by other methods of cooking: from 8.0 ppm (raw) to 2.2 ppm after frying in corn oil; from 10.7 to 3.9 ppm after frying in lard; and from 9.1 to 3.2 ppm after broiling. The concentration of DDT residues in fillets of yellow perch changed only from 0.3 ppm (raw) to 0.4 or 0.5 ppm after baking, frying, or broiling.

Parabolic flight experience is related to increased release of stress hormones.

PubMed

Schneider, Stefan; Brümmer, Vera; Göbel, Simon; Carnahan, Heather; Dubrowski, Adam; Strüder, Heiko K

2007-06-01

Numerous studies have shown significant effects of weightlessness on adaptational processes of the CNS, cardiovascular and/or muscular system. Most of these studies have been carried out during parabolic flights, using the recurring 20 s of weightlessness at each parabola. Although some of these studies reported on potential influences not only of weightlessness but also of the stressful situation within a parabolic flight, especially provoked by the ongoing changes between 1.8, 1 and 0 G, so far there seems to be only marginal information about objective parameters of stress evoked by parabolic flights. By collecting blood samples from a permanent venous catheter several times during parabolic flights, we were able to show an increase of prolactin, cortisol and ACTH in the course of a 120 min flight. We conclude, therefore, that previous reported effects of weightlessness on adaptational processes may be affected not only by weightlessness but also by the exposure to other stressors experienced within the environment of a Zero-G airbus.

A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

NASA Astrophysics Data System (ADS)

Arumugam, S.; Ramakrishna, P.; Sangavi, S.

2018-02-01

Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

Structure-based predictions of 13C-NMR chemical shifts for a series of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles derivatives using GA-based MLR method

NASA Astrophysics Data System (ADS)

Ghavami, Raouf; Sadeghi, Faridoon; Rasouli, Zolikha; Djannati, Farhad

2012-12-01

Experimental values for the 13C NMR chemical shifts (ppm, TMS = 0) at 300 K ranging from 96.28 ppm (C4' of indole derivative 17) to 159.93 ppm (C4' of indole derivative 23) relative to deuteride chloroform (CDCl3, 77.0 ppm) or dimethylsulfoxide (DMSO, 39.50 ppm) as internal reference in CDCl3 or DMSO-d6 solutions have been collected from literature for thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indole derivatives containing different substituted groups. An effective quantitative structure-property relationship (QSPR) models were built using hybrid method combining genetic algorithm (GA) based on stepwise selection multiple linear regression (SWS-MLR) as feature-selection tools and correlation models between each carbon atom of indole derivative and calculated descriptors. Each compound was depicted by molecular structural descriptors that encode constitutional, topological, geometrical, electrostatic, and quantum chemical features. The accuracy of all developed models were confirmed using different types of internal and external procedures and various statistical tests. Furthermore, the domain of applicability for each model which indicates the area of reliable predictions was defined.

Application of the cohesive zone model for the evaluation of stiffness losses in a rotor with a transverse breathing crack

NASA Astrophysics Data System (ADS)

Toni Liong, Rugerri; Proppe, Carsten

2013-04-01

The breathing mechanism of a transversely cracked rotor and its influence on a rotor system that appears due to shaft weight and inertia forces is studied. A method is proposed for the evaluation of the stiffness losses in the cross-section that contains the crack. This method is based on a cohesive zone model (CZM) instead of linear elastic fracture mechanics (LEFM). The CZM is developed for mode-I plane strain conditions and accounts explicitly for triaxiality of the stress state by using constitutive relations. The breathing crack is modelled by a parabolic shape. As long as the relative crack depth is small, a crack closure straight line model may be used, while the crack closure parabolic line should be used in the case of a deep crack. The CZM is also implemented in a one-dimensional continuum rotor model by means of finite element (FE) discretisation in order to predict and to analyse the dynamic behavior of a cracked rotor. The proposed method provides a useful tool for the analysis of rotor systems containing cracks.

Spectral methods for time dependent partial differential equations

NASA Technical Reports Server (NTRS)

Gottlieb, D.; Turkel, E.

1983-01-01

The theory of spectral methods for time dependent partial differential equations is reviewed. When the domain is periodic Fourier methods are presented while for nonperiodic problems both Chebyshev and Legendre methods are discussed. The theory is presented for both hyperbolic and parabolic systems using both Galerkin and collocation procedures. While most of the review considers problems with constant coefficients the extension to nonlinear problems is also discussed. Some results for problems with shocks are presented.

40 CFR 60.696 - Performance test methods and procedures and compliance provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... ppm of hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall...

40 CFR 60.696 - Performance test methods and procedures and compliance provisions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... ppm of hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall...

40 CFR 60.696 - Performance test methods and procedures and compliance provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... ppm of hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall...

40 CFR 60.696 - Performance test methods and procedures and compliance provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ppm of hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall...

40 CFR 60.696 - Performance test methods and procedures and compliance provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... ppm of hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall...

Analysis of geological materials containing uranium using laser-induced breakdown spectroscopy (LIBS)

NASA Astrophysics Data System (ADS)

Barefield, James E.; Judge, Elizabeth J.; Campbell, Keri R.; Colgan, James P.; Kilcrease, David P.; Johns, Heather M.; Wiens, Roger C.; McInroy, Rhonda E.; Martinez, Ronald K.; Clegg, Samuel M.

2016-06-01

Laser induced breakdown spectroscopy (LIBS) is a rapid atomic emission spectroscopy technique that can be configured for a variety of applications including space, forensics, and industry. LIBS can also be configured for stand-off distances or in-situ, under vacuum, high pressure, atmospheric or different gas environments, and with different resolving-power spectrometers. The detection of uranium in a complex geological matrix under different measurement schemes is explored in this paper. Although many investigations have been completed in an attempt to detect and quantify uranium in different matrices at in-situ and standoff distances, this work detects and quantifies uranium in a complex matrix under Martian and ambient air conditions. Investigation of uranium detection using a low resolving-power LIBS system at stand-off distances (1.6 m) is also reported. The results are compared to an in-situ LIBS system with medium resolving power and under ambient air conditions. Uranium has many thousands of emission lines in the 200-800 nm spectral region. In the presence of other matrix elements and at lower concentrations, the limit of detection of uranium is significantly reduced. The two measurement methods (low and high resolving-power spectrometers) are compared for limit of detection (LOD). Of the twenty-one potential diagnostic uranium emission lines, seven (409, 424, 434, 435, 436, 591, and 682 nm) have been used to determine the LOD for pitchblende in a dunite matrix using the ChemCam test bed LIBS system. The LOD values determined for uranium transitions in air are 409.013 nm (24,700 ppm), 424.167 nm (23,780 ppm), 434.169 nm (24,390 ppm), 435.574 nm (35,880 ppm), 436.205 nm (19,340 ppm), 591.539 nm (47,310 ppm), and 682.692 nm (18,580 ppm). The corresponding LOD values determined for uranium transitions in 7 Torr CO2 are 424.167 nm (25,760 ppm), 434.169 nm (40,800 ppm), 436.205 nm (32,050 ppm), 591.539 nm (15,340 ppm), and 682.692 nm (29,080 ppm). The LOD values determine for uranium emission lines using the medium resolving power (10,000 λ/Δλ) LIBS system for the dunite matrix in air are 409.013 nm (6120 ppm), 424.167 nm (5356 ppm), 434.169 nm (5693 ppm), 435.574 nm (6329 ppm), 436.205 nm (2142 ppm), and 682.692 nm (10,741 ppm). The corresponding LOD values determined for uranium transitions in a SiO2 matrix are 409.013 nm (272 ppm), 424.167 nm (268 ppm), 434.169 nm (402 ppm), 435.574 nm (1067 ppm), 436.205 nm (482 ppm), and 682.692 nm (720 ppm). The impact of spectral resolution, atmospheric conditions, matrix elements, and measurement distances on LOD is discussed. The measurements will assist one in selecting the proper system components based upon the application and the required analytical performance.

A gas chromatography-mass spectrometry method for the determination of delta-aminolevulinic acid in plant leaves.

PubMed

Hijaz, Faraj; Killiny, Nabil

2016-05-20

Delta-aminolevulinic (δ-ALA) acid is an important intermediate for tetrapyrroles biosynthesis and it has recently received great attention in plant physiology and human toxicology. However, the colorimetric method which is the most common method for determination of δ-ALA is time consuming and is not specific. In this study, a method for determination of δ-ALA in plant tissues was developed based on the trimethylsilyl (TMS) derivative of the pyrrole formed from the reaction of δ-ALA with ethyl acetoacetate via Knorr condensation. The δ-ALA in the HCl extract was reacted with ethyl acetoacetate to form a pyrrole. Then, the pyrrole compound was extracted using ethyl acetate and the solvent was evaporated to dryness. The dried sample was derivatized to its TMS ester and analyzed using GC-MS. The concentration of δ-ALA in citrus leaves incubated with levulinic acid was also determined by the conventional colorimetric method. The linear range was 10-200ppm in the full scan mode and 0.1-20ppm in the selected ion monitoring (SIM). The limit of detection was 6ppm in the full scan and 0.05ppm in SIM mode, representing a four-fold increase in sensitivity compared to the colorimetric method. The GC-MS method developed in this study is simple, accurate, sensitive, and could also be used to measure δ-ALA in other biological samples. Copyright © 2016 Elsevier B.V. All rights reserved.

A Simple and Direct LC-MS Method for Determination of Genotoxic Impurity Hydroxylamine in Pharmaceutical compounds.

PubMed

Kumar, Thangarathinam; Ramya, Mohandass; Srinivasan, Viswanathan; Xavier, N

2017-08-01

Hydroxylamine is a known genotoxic impurity compound that needs to be controlled down to ppm level in pharmaceutical processes. It is difficult to detect using conventional analytical techniques due to its physio-chemical properties like lack of chromophore, low molecular weight, absence of carbon atom and high polarity. In addition to that, analysis of the pharmaceutical samples encounters considerable obstruction from matrix components that greatly overshadow the response of hydroxylamine. This study describes a simple, sensitive and direct Liquid Chromatographic-Mass Spectrometric method (LC-MS) for detection of hydroxylamine in pharmaceutical compounds. The LC-MS method was detected up to 0.008 ppm of hydroxylamine with S/N > 3.0 and quantified up to 0.025 ppm of hydroxylamine with S/N ratio >10.0. This validated method can be applied as a generic method to detect the hydroxylamine for pharmaceutical process control and drug substance release. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Frequency dependent Qα and Qβ in the Umbria-Marche (Italy) region using a quadratic approximation of the coda-normalization method

NASA Astrophysics Data System (ADS)

de Lorenzo, Salvatore; Bianco, Francesca; Del Pezzo, Edoardo

2013-06-01

The coda normalization method is one of the most used methods in the inference of attenuation parameters Qα and Qβ. Since, in this method, the geometrical spreading exponent γ is an unknown model parameter, the most part of studies assumes a fixed γ, generally equal to 1. However γ and Q could be also jointly inferred from the non-linear inversion of coda-normalized logarithms of amplitudes, but the trade-off between γ and Q could give rise to unreasonable values of these parameters. To minimize the trade-off between γ and Q, an inversion method based on a parabolic expression of the coda-normalization equation has been developed. The method has been applied to the waveforms recorded during the 1997 Umbria-Marche seismic crisis. The Akaike criterion has been used to compare results of the parabolic model with those of the linear model, corresponding to γ = 1. A small deviation from the spherical geometrical spreading has been inferred, but this is accompanied by a significant variation of Qα and Qβ values. For almost all the considered stations, Qα smaller than Qβ has been inferred, confirming that seismic attenuation, in the Umbria-Marche region, is controlled by crustal pore fluids.

Enhanced Biocide Treatments with D-amino Acid Mixtures against a Biofilm Consortium from a Water Cooling Tower.

PubMed

Jia, Ru; Li, Yingchao; Al-Mahamedh, Hussain H; Gu, Tingyue

2017-01-01

Different species of microbes form mixed-culture biofilms in cooling water systems. They cause microbiologically influenced corrosion (MIC) and biofouling, leading to increased operational and maintenance costs. In this work, two D-amino acid mixtures were found to enhance two non-oxidizing biocides [tetrakis hydroxymethyl phosphonium sulfate (THPS) and NALCO 7330 (isothiazoline derivatives)] and one oxidizing biocide [bleach (NaClO)] against a biofilm consortium from a water cooling tower in lab tests. Fifty ppm (w/w) of an equimass mixture of D-methionine, D-leucine, D-tyrosine, D-tryptophan, D-serine, D-threonine, D-phenylalanine, and D-valine (D8) enhanced 15 ppm THPS and 15 ppm NALCO 7330 with similar efficacies achieved by the 30 ppm THPS alone treatment and the 30 ppm NALCO 7330 alone treatment, respectively in the single-batch 3-h biofilm removal test. A sequential treatment method was used to enhance bleach because D-amino acids react with bleach. After a 4-h biofilm removal test, the sequential treatment of 5 ppm bleach followed by 50 ppm D8 achieved extra 1-log reduction in sessile cell counts of acid producing bacteria, sulfate reducing bacteria, and general heterotrophic bacteria compared with the 5 ppm bleach alone treatment. The 10 ppm bleach alone treatment showed a similar efficacy with the sequential treatment of 5 ppm bleach followed by 50 ppm D8. The efficacy of D8 was found better than that of D4 (an equimass mixture of D-methionine, D-leucine, D-tyrosine, and D-tryptophan) in the enhancement of the three individual biocides against the biofilm consortium.

Photoreduction of mercury metal (Hg) using catalyst of oxalic acid from cellulose of rice husks (Oryza sativa L.)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sumiardi, Ade, E-mail: zulfasalmasaodah@gmail.com; Novi, Cory; Sukaesih, Esih

Photoreduction of mercury metal using catalyst of oxalic acid from cellulose of rice husks (Oryza sativa L.) is one of methods to reduce toxicity properties of the mercury metal in the society. The purpose of this research is to enhance photoreduction of mercury metal using catalyst of oxalic acid from cellulose of rice husks (Oryza sativa L.) at various concentrations. Photoreduction process is carried out in a closed reactor equipped with UV light and magnetic stirrer. Analysis of the influence of oxalic acid is determined by adding 25 mL of Hg (II) 5 ppm without oxalic acid, 25 mL of Hg (II) 5 ppmmore » + 25 mL of oxalic acid 3 ppm, 25 mL of Hg (II) 5 ppm + 25 mL of oxalic acid 6 ppm, 25 mL of Hg (II) 5 ppm + 25 mL of oxalic acid 9 ppm, 25 mL of Hg (II) 5 ppm + 25 mL of oxalic acid 12 ppm and 25 mL of Hg (II) 5 ppm + 25 mL of oxalic acid 15 ppm. All treatments are followed by centrifugation for 15 minutes, then the concentration of Hg residual in the solution is measured by mercury analyzer. The research results showed that addition of oxalic acid concentration from the cellulose of rice husks (Oryza sativa L.) can enhance photoreduction of mercury metal. Optimum concentration reduction of mercury metal with addition of oxalic acid is obtained as many as 9-12 ppm. It can reduce the concentration of mercury metal (II) by 68.8% to 88.6%.« less

Enhanced Biocide Treatments with D-amino Acid Mixtures against a Biofilm Consortium from a Water Cooling Tower

PubMed Central

Jia, Ru; Li, Yingchao; Al-Mahamedh, Hussain H.; Gu, Tingyue

2017-01-01

Different species of microbes form mixed-culture biofilms in cooling water systems. They cause microbiologically influenced corrosion (MIC) and biofouling, leading to increased operational and maintenance costs. In this work, two D-amino acid mixtures were found to enhance two non-oxidizing biocides [tetrakis hydroxymethyl phosphonium sulfate (THPS) and NALCO 7330 (isothiazoline derivatives)] and one oxidizing biocide [bleach (NaClO)] against a biofilm consortium from a water cooling tower in lab tests. Fifty ppm (w/w) of an equimass mixture of D-methionine, D-leucine, D-tyrosine, D-tryptophan, D-serine, D-threonine, D-phenylalanine, and D-valine (D8) enhanced 15 ppm THPS and 15 ppm NALCO 7330 with similar efficacies achieved by the 30 ppm THPS alone treatment and the 30 ppm NALCO 7330 alone treatment, respectively in the single-batch 3-h biofilm removal test. A sequential treatment method was used to enhance bleach because D-amino acids react with bleach. After a 4-h biofilm removal test, the sequential treatment of 5 ppm bleach followed by 50 ppm D8 achieved extra 1-log reduction in sessile cell counts of acid producing bacteria, sulfate reducing bacteria, and general heterotrophic bacteria compared with the 5 ppm bleach alone treatment. The 10 ppm bleach alone treatment showed a similar efficacy with the sequential treatment of 5 ppm bleach followed by 50 ppm D8. The efficacy of D8 was found better than that of D4 (an equimass mixture of D-methionine, D-leucine, D-tyrosine, and D-tryptophan) in the enhancement of the three individual biocides against the biofilm consortium. PMID:28861053

Advancing parabolic operators in thermodynamic MHD models: Explicit super time-stepping versus implicit schemes with Krylov solvers

NASA Astrophysics Data System (ADS)

Caplan, R. M.; Mikić, Z.; Linker, J. A.; Lionello, R.

2017-05-01

We explore the performance and advantages/disadvantages of using unconditionally stable explicit super time-stepping (STS) algorithms versus implicit schemes with Krylov solvers for integrating parabolic operators in thermodynamic MHD models of the solar corona. Specifically, we compare the second-order Runge-Kutta Legendre (RKL2) STS method with the implicit backward Euler scheme computed using the preconditioned conjugate gradient (PCG) solver with both a point-Jacobi and a non-overlapping domain decomposition ILU0 preconditioner. The algorithms are used to integrate anisotropic Spitzer thermal conduction and artificial kinematic viscosity at time-steps much larger than classic explicit stability criteria allow. A key component of the comparison is the use of an established MHD model (MAS) to compute a real-world simulation on a large HPC cluster. Special attention is placed on the parallel scaling of the algorithms. It is shown that, for a specific problem and model, the RKL2 method is comparable or surpasses the implicit method with PCG solvers in performance and scaling, but suffers from some accuracy limitations. These limitations, and the applicability of RKL methods are briefly discussed.

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

NASA Technical Reports Server (NTRS)

Kreider, Kevin L.; Baumeister, Kenneth J.

1996-01-01

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

Amide proton transfer imaging of brain tumors using a self-corrected 3D fast spin-echo dixon method: Comparison With separate B0 correction.

PubMed

Togao, Osamu; Keupp, Jochen; Hiwatashi, Akio; Yamashita, Koji; Kikuchi, Kazufumi; Yoneyama, Masami; Honda, Hiroshi

2017-06-01

To assess the quantitative performance of three-dimensional (3D) fast spin-echo (FSE) Dixon amide proton transfer (APT) imaging of brain tumors compared with B 0 correction with separate mapping methods. Twenty-two patients with brain tumors (54.2 ± 18.7 years old, 12 males and 10 females) were scanned at 3 Tesla (T). Z-spectra were obtained at seven different frequency offsets at ±3.1 ppm, ± 3.5 ppm, ± 3.9 ppm, and -1560 ppm. The scan was repeated three times at +3.5 ppm with echo shifts for Dixon B 0 mapping. The APT image corrected by a three-point Dixon-type B 0 map from the same scan (3D-Dixon) or a separate B 0 map (2D-separate and 3D-separate), and an uncorrected APT image (3D-uncorrected) were generated. We compared the APT-weighted signals within a tumor obtained with each 3D method with those obtained with 2D-separate as a reference standard. Excellent agreements and correlations with the 2D-separate were obtained by the 3D-Dixon method for both mean (ICC = 0.964, r = 0.93, P < 0.0001) and 90th-percentile (ICC = 0.972, r = 0.95, P < 0.0001) APT-weighted signals. These agreements and correlations for 3D-Dixon were better than those obtained by the 3D-uncorrected and 3D-separate methods. The 3D FSE Dixon APT method with intrinsic B 0 correction offers a quantitative performance that is similar to that of established two-dimensional (2D) methods. Magn Reson Med 77:2272-2279, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Method for transition prediction in high-speed boundary layers, phase 2

NASA Astrophysics Data System (ADS)

Herbert, T.; Stuckert, G. K.; Lin, N.

1993-09-01

The parabolized stability equations (PSE) are a new and more reliable approach to analyzing the stability of streamwise varying flows such as boundary layers. This approach has been previously validated for idealized incompressible flows. Here, the PSE are formulated for highly compressible flows in general curvilinear coordinates to permit the analysis of high-speed boundary-layer flows over fairly general bodies. Vigorous numerical studies are carried out to study convergence and accuracy of the linear-stability code LSH and the linear/nonlinear PSE code PSH. Physical interfaces are set up to analyze the M = 8 boundary layer over a blunt cone calculated by using a thin-layer Navier Stokes (TNLS) code and the flow over a sharp cone at angle of attack calculated using the AFWAL parabolized Navier-Stokes (PNS) code. While stability and transition studies at high speeds are far from routine, the method developed here is the best tool available to research the physical processes in high-speed boundary layers.

Comparison of Fresnel lenses and parabolic mirrors as solar energy concentrators.

PubMed

Lorenzo, E; Luque, A

1982-05-15

This paper compares the gain that can be achieved with a one- or two-stage concentrator, when the first stage is a Fresnel lens or a parabolic mirror, as a function of the luminosity of the concentrator. The results show that the achievable gain using a parabolic mirror is greater than that obtained using a flat or roof lens but is lower than that obtained using a curved lens.

Crank-Nicholson difference scheme for a stochastic parabolic equation with a dependent operator coefficient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashyralyev, Allaberen; Okur, Ulker

In the present paper, the Crank-Nicolson difference scheme for the numerical solution of the stochastic parabolic equation with the dependent operator coefficient is considered. Theorem on convergence estimates for the solution of this difference scheme is established. In applications, convergence estimates for the solution of difference schemes for the numerical solution of three mixed problems for parabolic equations are obtained. The numerical results are given.

On the Behavior of Eisenstein Series Through Elliptic Degeneration

NASA Astrophysics Data System (ADS)

Garbin, D.; Pippich, A.-M. V.

2009-12-01

Let Γ be a Fuchsian group of the first kind acting on the hyperbolic upper half plane {mathbb{H}}, and let {M = Γbackslash mathbb{H}} be the associated finite volume hyperbolic Riemann surface. If γ is a primitive parabolic, hyperbolic, resp. elliptic element of Γ, there is an associated parabolic, hyperbolic, resp. elliptic Eisenstein series. In this article, we study the limiting behavior of these Eisenstein series on an elliptically degenerating family of finite volume hyperbolic Riemann surfaces. In particular, we prove the following result. The elliptic Eisenstein series associated to a degenerating elliptic element converges up to a factor to the parabolic Eisenstein series associated to the parabolic element which fixes the newly developed cusp on the limit surface.

Theoretical study of energy states of two-dimensional electron gas in pseudomorphically strained InAs HEMTs taking into account the non-parabolicity of the conduction band

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishio, Yui; Yamaguchi, Satoshi; Yamazaki, Youichi

2013-12-04

We determined rigorously the energy states of a two-dimensional electron gas (2DEG) in high electron mobility transistors (HEMTs) with a pseudomorphically strained InAs channel (InAs PHEMTs) taking into account the non-parabolicity of the conduction band for InAs. The sheet carrier concentration of 2DEG for the non-parabolic energy band was about 50% larger than that for the parabolic energy band and most of the electrons are confined strongly in the InAs layer. In addition, the threshold voltage for InAs PHEMTs was about 0.21 V lower than that for conventional InGaAs HEMTs.

Magneto-optical properties of semi-parabolic plus semi-inverse squared quantum wells

NASA Astrophysics Data System (ADS)

Tung, Luong V.; Vinh, Pham T.; Phuc, Huynh V.

2018-06-01

We theoretically study the optical absorption in a quantum well with the semi-parabolic potential plus the semi-inverse squared potential (SPSIS) in the presence of a static magnetic field in which both one- and two-photon absorption processes have been taken into account. The expression of the magneto-optical absorption coefficient (MOAC) is expressed by the second-order golden rule approximation including the electron-LO phonon interaction. We also use the profile method to obtain the full width at half maximum (FWHM) of the absorption peaks. Our numerical results show that either MOAC or FWHM strongly depends on the confinement frequency, temperature, and magnetic field but their dependence on the parameter β is very weak. The temperature dependence of FWHM is consistent with the previous theoretical and experimental works.

TE modes of UV-laser generated waveguides in a planar polymer chip of parabolic refractive index profile

NASA Astrophysics Data System (ADS)

Shams El-Din, M. A.

2018-04-01

The UV-laser lithographic method is used for the preparation of Polymeric integrated-optical waveguides in a planar polymer chip. The waveguide samples are irradiated by an excimer laser of wavelength 248 nm with different doses and with the same fluencies. The refractive index depth profile for the waveguides, in the first zone is found to have a parabolic shape and Gaussian shape in the second one that can be determined by Mach-Zehnder interferometer. Both the mode field distribution and the effective mode indices for the first zone only are determined by making use of the theoretical mode and the experimental data. It is found that the model field distribution is strongly dependent on the refractive indices for each zone.

Localization or tunneling in asymmetric double-well potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Dae-Yup, E-mail: dsong@sunchon.ac.kr

An asymmetric double-well potential is considered, assuming that the wells are parabolic around the minima. The WKB wave function of a given energy is constructed inside the barrier between the wells. By matching the WKB function to the exact wave functions of the parabolic wells on both sides of the barrier, for two almost degenerate states, we find a quantization condition for the energy levels which reproduces the known energy splitting formula between the two states. For the other low-lying non-degenerate states, we show that the eigenfunction should be primarily localized in one of the wells with negligible magnitude inmore » the other. Using Dekker’s method (Dekker, 1987), the present analysis generalizes earlier results for weakly biased double-well potentials to systems with arbitrary asymmetry.« less

CASTRO: A NEW COMPRESSIBLE ASTROPHYSICAL SOLVER. II. GRAY RADIATION HYDRODYNAMICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, W.; Almgren, A.; Bell, J.

We describe the development of a flux-limited gray radiation solver for the compressible astrophysics code, CASTRO. CASTRO uses an Eulerian grid with block-structured adaptive mesh refinement based on a nested hierarchy of logically rectangular variable-sized grids with simultaneous refinement in both space and time. The gray radiation solver is based on a mixed-frame formulation of radiation hydrodynamics. In our approach, the system is split into two parts, one part that couples the radiation and fluid in a hyperbolic subsystem, and another parabolic part that evolves radiation diffusion and source-sink terms. The hyperbolic subsystem is solved explicitly with a high-order Godunovmore » scheme, whereas the parabolic part is solved implicitly with a first-order backward Euler method.« less

Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

NASA Technical Reports Server (NTRS)

Opila, Elizabeth; Boyd, Meredith K.

2010-01-01

SiC-fiber reinforced SiC matrix composites with a BN interphase were oxidized in reduced oxygen partial pressures of oxygen to simulate the environment for hypersonic vehicle leading edge applications. The constituent fibers as well as composite coupons were oxidized in oxygen partial pressures ranging from 1000 ppm O2 to 5% O2 balance argon. Exposure temperatures ranged from 816 C to 1353 C (1500 F to 2450 F). The oxidation kinetics of the coated fibers were monitored by thermogravimetric analysis (TGA). An initial rapid transient weight gain was observed followed by parabolic kinetics. Possible mechanisms for the transient oxidation are discussed. One edge of the composite coupon seal coat was ground off to simulate damage to the composite which allowed oxygen ingress to the interior of the composite. Oxidation kinetics of the coupons were characterized by scanning electron microscopy since the weight changes were minimal. It was found that sealing of the coupon edge by silica formation occurred. Differences in the amount and morphology of the sealing silica as a function of time, temperature and oxygen partial pressure are discussed. Implications for use of these materials for hypersonic vehicle leading edge materials are summarized.

Gold grade of epithermal gold ore at Lamuntet, Brang Rea, West Sumbawa District, West Nusa Tenggara Province, Indonesia

NASA Astrophysics Data System (ADS)

Ernawati, Rika; Idrus, Arifudin; TBMP, Himawan

2017-06-01

Lamuntet is one of gold ore mining area carried out by the Artisanal Small scale Gold Mining (ASGM) located in West Sumbawa, Indonesia. Most of the miners at this area are not the local miners but also those from other regions. Mineralization of this area is strong identified as low sulfidation epithermal system. There are two blocks of this mining location, namely, Ngelampar block with an area of 0.164 km2 and Song block with an area of 0.067 km2. This study was focused on Ngelampar block. The characteristic of epithermal system is the existence of quartz vein with comb, vuggy, and sugary texture. The aim of this research was to analyze the gold grade and other metals, such as Cu, Ag, Pb, As, Zn, and Hg. The research methods included literature study from previous researches, field work, laboratory work, and interpretation. The literature study was performed on previous researches with similar study area. The field work comprised of direct observation and sampling. Fieldwork was done for a week to obtain gold ore/vein. Sixteen samples were analyzed to obtain the grade of ore/metal. The Hg laboratory analysis was then performed on the six samples with the highest gold grade. Laboratory works were conducted at Intertek Jakarta by using Fire Assay (FA) for gold grade and Atomic Absorption Spectrophotometry (AAS) for Cu, Ag, Pb, As, Zn, and Hg. Results of the analysis showed the range of Au was grade (0.1 ppm - 27.8 ppm), Cu was 26 ppm -1740 ppm, Pb was 101 ppm- >4000 ppm, Zn of 73 ppm- >10,000 ppm, Ag of 3 ppm -185 ppm, As was 150 ppm-6530 ppm, and Hg of 0.08 ppm - 1.89 ppm. L1 and L15 had high grade for all values (Au, Ag, Zn, Cu, As, and Hg). Gold mineralization was formed as electrum because of Ag content is higher than 20%. Associated minerals of the samples in the study area were galena, sphalerite, arsenopyrite, and chalcopyrite which showed the characteristic of rich base metal of Pb, Zn, and Cu at LS epithermal.

PHARMACEUTICAL EVALUATION AND TOXICOLOGICAL QUANTIFICATION OF HEAVY METALS AND ADULTERATED ALLOPATHIC CONTENTS IN RAW AND FINISHED DOSAGE FORM OF ANTIHYPERTENSIVE HERBAL PRODUCTS

PubMed Central

Khan, Muhammad Asif; Badshah, Amir; Shahid, Muhammad

2016-01-01

Background: Herbal products of questionable quality create major concern for human population since their production is often not controlled and regulated. Material and Methods: Antihypertensive herbal products were subjected to pharmaceutical quality control parameters specified in Pharmacopoeias, toxic quantification of heavy metals by flame atomic absorption spectrophotometer and adulterated allopathic contents were quantified using advanced HPLC techniques. Results: A lot of variations in pharmaceutical parameters like moisture contents and LOD% values were observed. Also deviations to a greater extent in weight variation, (P1, P2, P6, P12, P16, P17, P19, and P20), and hardness of the tablets of products (P1, P3, P8 and P11) were found. Friability of tablets of the Products (P3, P9 and P11) was found failed. Heavy metals i-e Fe (1597.20ppm, 1648ppm) in P5, P9, Pb (61.32ppm, 16.59 ppm) in P5, Cr (96.91ppm,108.48 ppm) in P4, P14, Cd (39.53ppm, 32.31 ppm) in P11, P12, Cu (28.22ppm, 21.04 ppm) in P15, P17, Zn (80.31ppm,76.27 ppm) in P15, P16, Ni (45.46ppm,22.18ppm) in P9, P13 in toxic concentrations were detected. Adulterated allopathic contents of Amlpdopine in higher quantities, administered according to manufacturer dose were found in P12 (20.30 mg/day), Verapamil in P2 (93.50 mg/day), Nifedipine (38.65 mg/day) in P6. Products P4, P5 and P7 were found to have a combination of Amlodipine and Hydrochlorothiazide and higher concentrations were found in P5 (10.72 mg/day, 24.75 mg/day). Conclusion: The antihypertensive herbal products contained different kind of adulterants. Our findings suggest that effective regulatory measures should be put in place to address this problem. This will help to decrease the toxic effects of these remedies and increase the commercialization, internationalization and harmonization of antihypertensive herbal products. PMID:28480360

The finite element method scheme for a solution of an evolution variational inequality with a nonlocal space operator

NASA Astrophysics Data System (ADS)

Glazyrina, O. V.; Pavlova, M. F.

2016-11-01

We consider the parabolic inequality with monotone with respect to a gradient space operator, which is depended on integral with respect to space variables solution characteristic. We construct a two-layer differential scheme for this problem with use of penalty method, semidiscretization with respect to time variable method and the finite element method (FEM) with respect to space variables. We proved a convergence of constructed mothod.

Parabolic dune reactivation and migration at Napeague, NY, USA: Insights from aerial and GPR imagery

NASA Astrophysics Data System (ADS)

Girardi, James D.; Davis, Dan M.

2010-02-01

Observations from mapping since the 19th century and aerial imagery since 1930 have been used to study changes in the aeolian geomorphology of coastal parabolic dunes over the last ~ 170 years in the Walking Dune Field, Napeague, NY. The five large parabolic dunes of the Walking Dune Field have all migrated across, or are presently interacting with, a variably forested area that has affected their migration, stabilization and morphology. This study has concentrated on a dune with a particularly complex history of stabilization, reactivation and migration. We have correlated that dune's surface evolution, as revealed by aerial imagery, with its internal structures imaged using 200 MHz and 500 MHz Ground Penetrating Radar (GPR) surveys. Both 2D (transect) and high-resolution 3D GPR imagery image downwind dipping bedding planes which can be grouped by apparent dip angle into several discrete packages of beds that reflect distinct decadal-scale episodes of dune reactivation and growth. From aerial and high resolution GPR imagery, we document a unique mode of reactivation and migration linked to upwind dune formation and parabolic dune interactions with forest trees. This study documents how dune-dune and dune-vegetation interactions have influenced a unique mode of blowout deposition that has alternated on a decadal scale between opposite sides of a parabolic dune during reactivation and migration. The pattern of recent parabolic dune reactivation and migration in the Walking Dune Field appears to be somewhat more complex, and perhaps more sensitive to subtle environmental pressures, than an idealized growth model with uniform deposition and purely on-axis migration. This pattern, believed to be prevalent among other parabolic dunes in the Walking Dune Field, may occur also in many other places where similar observational constraints are unavailable.

A fourth-order box method for solving the boundary layer equations

NASA Technical Reports Server (NTRS)

Wornom, S. F.

1977-01-01

A fourth order box method for calculating high accuracy numerical solutions to parabolic, partial differential equations in two variables or ordinary differential equations is presented. The method is the natural extension of the second order Keller Box scheme to fourth order and is demonstrated with application to the incompressible, laminar and turbulent boundary layer equations. Numerical results for high accuracy test cases show the method to be significantly faster than other higher order and second order methods.

Parabolic dish test site: History and operating experience

NASA Technical Reports Server (NTRS)

Selcuk, M. K. (Compiler)

1985-01-01

The parabolic dish test site (PDTS) was established for testing point-focusing solar concentrator systems operating at temperatures approaching 1650 C. Among tests run were evaluation and performance characterization of parabolic dish concentrators, receivers, power conversion units, and solar/fossil-fuel hybrid systems. The PDTS was fully operational until its closure in June, 1984. The evolution of the test program, a chronological listing of the experiments run, and data summaries for most of the tests conducted are presented.

Interband magneto-spectroscopy in InSb square and parabolic quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasturiarachchi, T.; Edirisooriya, M.; Mishima, T. D.

We measure the magneto-optical absorption due to intersubband optical transitions between conduction and valence subband Landau levels in InSb square and parabolic quantum wells. InSb has the narrowest band gap (0.24 eV at low temperature) of the III–V semiconductors leading to a small effective mass (0.014 m{sub 0}) and a large g–factor (−51). As a result, the Landau level spacing is large at relatively small magnetic fields (<8 T), and one can observe spin-splitting of the Landau levels. We examine two structures: (i) a multiple-square-well structure and (ii) a structure containing multiple parabolic wells. The energies and intensities of the strongest featuresmore » are well explained by a modified Pidgeon-Brown model based on an 8-band k•p model that explicitly incorporates pseudomorphic strain. The strain is essential for obtaining agreement between theory and experiment. While modeling the square well is relatively straight-forward, the parabolic well consists of 43 different layers of various thickness to approximate a parabolic potential. Agreement between theory and experiment for the parabolic well validates the applicability of the model to complicated structures, which demonstrates the robustness of our model and confirms its relevance for developing electronic and spintronic devices that seek to exploit the properties of the InSb band structure.« less

Commercialization of parabolic dish systems

NASA Technical Reports Server (NTRS)

Washom, B.

1982-01-01

The impact of recent federal tax and regulatory legislation on the commercialization of parabolic solar reflector technology is assessed. Specific areas in need of technical or economic improvement are noted.

Commercialization of parabolic dish systems

NASA Astrophysics Data System (ADS)

Washom, B.

1982-07-01

The impact of recent federal tax and regulatory legislation on the commercialization of parabolic solar reflector technology is assessed. Specific areas in need of technical or economic improvement are noted.

PPM mixtures of formaldehyde in gas cylinders: Stability and analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, K.C.; Miller, S.B.; Patterson, L.M.

1999-07-01

Scott Specialty Gases has been successful in producing stable calibration gases of formaldehyde at low concentration. Critical to this success has been the development of a treatment process for high pressure aluminum cylinders. Formaldehyde cylinders having concentrations of 20ppm and 4ppm were found to show only small decline in concentrations over a period of approximately 12 months. Since no NIST traceable formaldehyde standards (or Standard Reference Material) are available, all Scott's formaldehyde cylinders were originally certified by traditional impinger method. This method involves an extremely tedious purification procedure for 2,4-dinitrophenylhydrazine (2,4-DNPH). A modified version of the impinger method has beenmore » developed and does not require extensive reagent purification for formaldehyde analysis. Extremely low formaldehyde blanks have been obtained with the modified method. The HPLC conditions in the original method were used for chromatographic separations. The modified method results in a lower analytical uncertainty for the formaldehyde standard mixtures. Consequently, it is possible to discern small differences between analytical results that are important for stability study.« less

Orthostatic Intolerance and Motion Sickness After Parabolic Flight

NASA Technical Reports Server (NTRS)

Schlegel, Todd T.; Brown, Troy E.; Wood, Scott J.; Benavides, Edgar W.; Bondar, Roberta L.; Stein, Flo; Moradshahi, Peyman; Harm, Deborah L.; Low, Phillip A.

1999-01-01

Orthostatic intolerance is common in astronauts after prolonged space flight. However, the "push-pull effect" in military aviators suggests that brief exposures to transitions between hypo- and hypergravity are sufficient to induce untoward autonomic cardiovascular physiology in susceptible individuals. We therefore investigated orthostatic tolerance and autonomic cardiovascular function in 16 healthy test subjects before and after a seated 2-hr parabolic flight. At the same time, we also investigated relationships between parabolic flight-induced vomiting and changes in orthostatic and autonomic cardiovascular function. After parabolic flight, 8 of 16 subjects could not tolerate a 30-min upright tilt test, compared to 2 of 16 before flight. Whereas new intolerance in non-Vomiters resembled the clinical postural tachycardia syndrome (POTS), new intolerance in Vomiters was characterized by comparatively isolated upright hypocapnia and cerebral vasoconstriction. As a group, Vomiters also had evidence for increased postflight fluctuations in efferent vagal-cardiac nerve traffic occurring independently of any superimposed change in respiration. Results suggest that syndromes of orthostatic intolerance resembling those occurring after space flight can occur after a brief (i.e., 2-hr) parabolic flight.

Robustness of Light-Transport Processes to Bending Deformations in Graded-Index Multimode Waveguides

NASA Astrophysics Data System (ADS)

Boonzajer Flaes, Dirk E.; Stopka, Jan; Turtaev, Sergey; de Boer, Johannes F.; Tyc, Tomáš; Čižmár, Tomáš

2018-06-01

Light transport through a multimode optical waveguide undergoes changes when subjected to bending deformations. We show that optical waveguides with a perfectly parabolic refractive index profile are almost immune to bending, conserving the structure of propagation-invariant modes. Moreover, we show that changes to the transmission matrix of parabolic-index fibers due to bending can be expressed with only two free parameters, regardless of how complex a particular deformation is. We provide detailed analysis of experimentally measured transmission matrices of a commercially available graded-index fiber as well as a gradient-index rod lens featuring a very faithful parabolic refractive index profile. Although parabolic-index fibers with a sufficiently precise refractive index profile are not within our reach, we show that imaging performance with standard commercially available graded-index fibers is significantly less influenced by bending deformations than step-index types under the same conditions. Our work thus predicts that the availability of ultraprecise parabolic-index fibers will make endoscopic applications with flexible probes feasible and free from extremely elaborate computational challenges.

Gaussian Finite Element Method for Description of Underwater Sound Diffraction

NASA Astrophysics Data System (ADS)

Huang, Dehua

A new method for solving diffraction problems is presented in this dissertation. It is based on the use of Gaussian diffraction theory. The Rayleigh integral is used to prove the core of Gaussian theory: the diffraction field of a Gaussian is described by a Gaussian function. The parabolic approximation used by previous authors is not necessary to this proof. Comparison of the Gaussian beam expansion and Fourier series expansion reveals that the Gaussian expansion is a more general and more powerful technique. The method combines the Gaussian beam superposition technique (Wen and Breazeale, J. Acoust. Soc. Am. 83, 1752-1756 (1988)) and the Finite element solution to the parabolic equation (Huang, J. Acoust. Soc. Am. 84, 1405-1413 (1988)). Computer modeling shows that the new method is capable of solving for the sound field even in an inhomogeneous medium, whether the source is a Gaussian source or a distributed source. It can be used for horizontally layered interfaces or irregular interfaces. Calculated results are compared with experimental results by use of a recently designed and improved Gaussian transducer in a laboratory water tank. In addition, the power of the Gaussian Finite element method is demonstrated by comparing numerical results with experimental results from use of a piston transducer in a water tank.

Local spatiotemporal time-frequency peak filtering method for seismic random noise reduction

NASA Astrophysics Data System (ADS)

Liu, Yanping; Dang, Bo; Li, Yue; Lin, Hongbo

2014-12-01

To achieve a higher level of seismic random noise suppression, the Radon transform has been adopted to implement spatiotemporal time-frequency peak filtering (TFPF) in our previous studies. Those studies involved performing TFPF in full-aperture Radon domain, including linear Radon and parabolic Radon. Although the superiority of this method to the conventional TFPF has been tested through processing on synthetic seismic models and field seismic data, there are still some limitations in the method. Both full-aperture linear Radon and parabolic Radon are applicable and effective for some relatively simple situations (e.g., curve reflection events with regular geometry) but inapplicable for complicated situations such as reflection events with irregular shapes, or interlaced events with quite different slope or curvature parameters. Therefore, a localized approach to the application of the Radon transform must be applied. It would serve the filter method better by adapting the transform to the local character of the data variations. In this article, we propose an idea that adopts the local Radon transform referred to as piecewise full-aperture Radon to realize spatiotemporal TFPF, called local spatiotemporal TFPF. Through experiments on synthetic seismic models and field seismic data, this study demonstrates the advantage of our method in seismic random noise reduction and reflection event recovery for relatively complicated situations of seismic data.

ANALYTICAL METHOD FOR THE ABSORPTIOMETRIC DETERMINATION OF BORON IN SODIUM METAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1963-01-01

Sodium metal is dissolved in water under an inert atmosphere of argon, and the resulting sodium hydroxide solution is evaporated to dryness. Rosocyanin is formed, separated from excess curcumin, and dissolved in ethanol for absorptiometric measurement. The method is applicable to sodium metal containing 0.1 to 1 ppm boron. The precision should be within plus or minus 20% (95% confidence limits) at the 0.5 ppm boron level. (auth)

Method for Reduction of Silver Biocide Plating on Metal Surfaces

NASA Technical Reports Server (NTRS)

Steele, John; Nalette, Timothy; Beringer, Durwood

2013-01-01

Silver ions in aqueous solutions (0.05 to 1 ppm) are used for microbial control in water systems. The silver ions remain in solution when stored in plastic containers, but the concentration rapidly decreases to non-biocidal levels when stored in metal containers. The silver deposits onto the surface and is reduced to non-biocidal silver metal when it contacts less noble metal surfaces, including stainless steel, titanium, and nickel-based alloys. Five methods of treatment of contact metal surfaces to deter silver deposition and reduction are proposed: (1) High-temperature oxidation of the metal surface; (2) High-concentration silver solution pre-treatment; (3) Silver plating; (4) Teflon coat by vapor deposition (titanium only); and (5) A combination of methods (1) and (2), which proved to be the best method for the nickel-based alloy application. The mechanism associated with surface treatments (1), (2), and (5) is thought to be the development of a less active oxide layer that deters ionic silver deposition. Mechanism (3) is an attempt to develop an equilibrium ionic silver concentration via dissolution of metallic silver. Mechanism (4) provides a non-reactive barrier to deter ionic silver plating. Development testing has shown that ionic silver in aqueous solution was maintained at essentially the same level of addition (0.4 ppm) for up to 15 months with method (5) (a combination of methods (1) and (2)), before the test was discontinued for nickel-based alloys. Method (1) resulted in the maintenance of a biocidal level (approximately 0.05 ppm) for up to 10 months before that test was discontinued for nickel-based alloys. Methods (1) and (2) used separately were able to maintain ionic silver in aqueous solution at essentially the same level of addition (0.4 ppm) for up to 10 months before the test was discontinued for stainless steel alloys. Method (3) was only utilized for titanium alloys, and was successful at maintaining ionic silver in aqueous solution at essentially the same level of addition (0.4 ppm) for up to 10 months before the test was discontinued for simple flat geometries, but not for geometries that are difficult to Teflon coat.

A parabolic analogue of the higher-order comparison theorem of De Silva and Savin

NASA Astrophysics Data System (ADS)

Banerjee, Agnid; Garofalo, Nicola

2016-01-01

We show that the quotient of two caloric functions which vanish on a portion of the lateral boundary of a H k + α domain is H k + α up to the boundary for k ≥ 2. In the case k = 1, we show that the quotient is in H 1 + α if the domain is assumed to be space-time C 1 , α regular. This can be thought of as a parabolic analogue of a recent important result in [8], and we closely follow the ideas in that paper. We also give counterexamples to the fact that analogous results are not true at points on the parabolic boundary which are not on the lateral boundary, i.e., points which are at the corner and base of the parabolic boundary.

Null Angular Momentum and Weak KAM Solutions of the Newtonian N-Body Problem

NASA Astrophysics Data System (ADS)

Percino-Figueroa, Boris A.

2017-08-01

In [Arch. Ration. Mech. Anal. 213 (2014), 981-991] it has been proved that in the Newtonian N-body problem, given a minimal central configuration a and an arbitrary configuration x, there exists a completely parabolic orbit starting on x and asymptotic to the homothetic parabolic motion of a, furthermore such an orbit is a free time minimizer of the action functional. In this article we extend this result in abundance of completely parabolic motions by proving that under the same hypothesis it is possible to get that the completely parabolic motion starting at x has zero angular momentum. We achieve this by characterizing the rotation invariant weak KAM solutions as those defining a lamination on the configuration space by free time minimizers with zero angular momentum.

Environmental assessment of NH3 injection for an industrial package boiler. Volume 2. Data supplement. Final report, January 1983-January 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castaldini, C.; DeRosier, R.; Waterland, L.R.

1986-02-01

The report discusses emission results from comprehensive flue-gas sampling of a gas- and oil-fired industrial boiler equipped with Exxon's Thermal DeNOx Ammonia Injection Process for NOx reduction. Comprehensive emission measurements included continuous monitoring of flue gas emissions; source assessment sampling system (SASS) tests; EPA Method 5/17 for solid and condensible particulate emissions and ammonia emissions; controlled condensation system for SO2 and SO3; and N2O emission sampling. Ammonia injection at a NH3/NO molar ratio of 2.52 gave a NOx reduction of 41% from an uncontrolled level of 234 ppm to a controlled level of 137 ppm. NH3 emissions increased from 11more » ppm for the baseline to an average of 430 ppm for ammonia injection. Nitrous oxide, N2O, was reduced 68% from a 50 ppm baseline level to a 17 ppm controlled level. Total particulate emissions increased by an order of magnitude from a baseline of 17.7 ng/J to a controlled level of 182 ng/J.« less

Fluoride Content of Bottled Waters in Hong Kong and Qatar.

PubMed

Al-Mulla, Hessa I; Anthonappa, Robert P; King, Nigel M

2016-01-01

To determine the F concentration of bottled waters that was available in Hong Kong and Qatar. The F concentrations of bottled waters collected from Hong Kong (n=81) and Qatar (n=32) were analysed. The F ion selective electrode method was used to measure the F concentration in the samples. Three measurements were obtained for every sample to ensure reproducibility and appropriate statistical analyses were employed. Qatar group: F concentrations ranged from 0.06 ppm to 3.0 ppm with a mean value of 0.8 ppm. The F concentrations displayed on the labels of the samples (60%) were significantly lower than the measured F concentration (p < 0.0001). Hong Kong group: F concentrations ranged from 0.04 ppm to 2.52 ppm with a mean value of 0.44 ppm. The F concentrations displayed on the samples (16%) were significantly lower than the measured F concentration (p< 0.0001). Wide variations exist in the F concentration among the different brands of bottled water available in Hong Kong and Qatar. The F concentrations displayed on the labels were not consistent with the measured F concentrations.

Geometry of Conservation Laws for a Class of Parabolic Partial Differential Equations

NASA Astrophysics Data System (ADS)

Clelland, Jeanne Nielsen

1996-08-01

I consider the problem of computing the space of conservation laws for a second-order, parabolic partial differential equation for one function of three independent variables. The PDE is formulated as an exterior differential system {cal I} on a 12 -manifold M, and its conservation laws are identified with the vector space of closed 3-forms in the infinite prolongation of {cal I} modulo the so -called "trivial" conservation laws. I use the tools of exterior differential systems and Cartan's method of equivalence to study the structure of the space of conservation laws. My main result is:. Theorem. Any conservation law for a second-order, parabolic PDE for one function of three independent variables can be represented by a closed 3-form in the differential ideal {cal I} on the original 12-manifold M. I show that if a nontrivial conservation law exists, then {cal I} has a deprolongation to an equivalent system {cal J} on a 7-manifold N, and any conservation law for {cal I} can be expressed as a closed 3-form on N which lies in {cal J}. Furthermore, any such system in the real analytic category is locally equivalent to a system generated by a (parabolic) equation of the formA(u _{xx}u_{yy}-u_sp {xy}{2}) + B_1u_{xx }+2B_2u_{xy} +B_3u_ {yy}+C=0crwhere A, B_{i}, C are functions of x, y, t, u, u_{x}, u _{y}, u_{t}. I compute the space of conservation laws for several examples, and I begin the process of analyzing the general case using Cartan's method of equivalence. I show that the non-linearizable equation u_{t} = {1over2}e ^{-u}(u_{xx}+u_ {yy})has an infinite-dimensional space of conservation laws. This stands in contrast to the two-variable case, for which Bryant and Griffiths showed that any equation whose space of conservation laws has dimension 4 or more is locally equivalent to a linear equation, i.e., is linearizable.

Parabolic Flights with Single-Engine Aerobatic Aircraft: Flight Profile and a Computer Simulator for its Optimization

NASA Astrophysics Data System (ADS)

Brigos, Miguel; Perez-Poch, Antoni; Alpiste, Francesc; Torner, Jordi; González Alonso, Daniel Ventura

2014-11-01

We report the results of residual acceleration obtained from initial tests of parabolic flights (more than 100 hours) performed with a small single-engine aerobatic aircraft (CAP10B), and propose a method that improves these figures. Such aircraft have proved capable of providing researchers with periods of up to 8 seconds of reduced gravity in the cockpit, with a gravity quality in the range of 0.1 g 0, where g 0 is the gravitational acceleration of the Earth. Such parabolas may be of interest to experimenters in the reduced gravity field, when this range of reduced gravity is acceptable for the experiment undertaken. They have also proven to be useful for motivational and educational campaigns. Furthermore, these flights may be of interest to researchers as a test-bed for obtaining a proof-of-concept for subsequent access to parabolic flights with larger aircraft or other microgravity platforms. The limited cost of the operations with these small aircraft allows us to perform them as part of a non-commercial joint venture between the Universitat Politècnica de Catalunya - BarcelonaTech (UPC), the Barcelona cluster BAIE and the Aeroclub Barcelona-Sabadell. Any improvements in the length and quality of reduced gravity would increase the capabilities of these small aircraft. To that end, we have developed a method based on a simulator for training aerobatic pilots. The simulation is performed with the CAD software for mechanical design Solidworks Motion{circledR }, which is widely distributed in industry and in universities. It specifically simulates the parabolic flight manoeuvre for our small aircraft and enables us to improve different aspects of the manoeuvre. The simulator is first validated with experimental data from the test flights. We have conducted an initial intensive period of specific pilot training with the aid of the simulator output. After such initial simulation-aided training, results show that the reduced gravity quality has significantly improved from 0.1 g 0 to 0.05 g 0. We conclude that single-engine aerobatic aircraft are capable of conducting small hypogravity experiments with the limitations described in the paper.

Antimicrobial activity of tempeh gembus hydrolyzate

NASA Astrophysics Data System (ADS)

Noviana, A.; Dieny, F. F.; Rustanti, N.; Anjani, G.; Afifah, D. N.

2018-02-01

Tropical disease can be prevented by consumming fermented foods that have antimicrobial activity. One of them is tempeh gembus that has short shelf life. It can be overcome by processing it into hydrolyzate. This study aimed to determine antimicrobial activity of tempeh gembus hydrolyzate. Tempeh gembus was made of local soybean from Grobogan. They were added 5,000 ppm, 8,000 ppm, and 10,000 ppm of bromelain enzyme (TGH BE). Antimicrobial effects of TGH BE were tested against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Steptococcus mutans. Antimicrobial test was carried out using Kirby-Bauer Disc Diffussion method. Soluble protein test used Bradford method. The largest inhibition zone against S. aureus and S. mutans were shown by TGH BE 8,000 ppm, 0.89±0.53 mm and 2.40±0.72 mm. The largest inhibition zone of B. subtilis, 7.33±2,25 mm, was shown by TGH BE 5,000 ppm. There wasn’t antimicrobial effect of TGH BE against E. coli. There weren’t significant differences of soluble protein (P=0.293) and the inhibition zones againt S. aureus (P = 0.967), E. coli (P = 1.000), B. subtilis (P = 0.645), S. mutans (P=0.817) of all treatments. There were antimicrobial activities of TGH BE against S. aureus, B. subtilis, and S. mutans.

Adaptive sensor-based ultra-high accuracy solar concentrator tracker

NASA Astrophysics Data System (ADS)

Brinkley, Jordyn; Hassanzadeh, Ali

2017-09-01

Conventional solar trackers use information of the sun's position, either by direct sensing or by GPS. Our method uses the shading of the receiver. This, coupled with nonimaging optics design allows us to achieve ultra-high concentration. Incorporating a sensor based shadow tracking method with a two stage concentration solar hybrid parabolic trough allows the system to maintain high concentration with acute accuracy.

The numerical modelling of MHD astrophysical flows with chemistry

NASA Astrophysics Data System (ADS)

Kulikov, I.; Chernykh, I.; Protasov, V.

2017-10-01

The new code for numerical simulation of magnetic hydrodynamical astrophysical flows with consideration of chemical reactions is given in the paper. At the heart of the code - the new original low-dissipation numerical method based on a combination of operator splitting approach and piecewise-parabolic method on the local stencil. The chemodynamics of the hydrogen while the turbulent formation of molecular clouds is modeled.

Near-parabolic comets observed in 2006-2010. The individualized approach to 1/a-determination and the new distribution of original and future orbits

NASA Astrophysics Data System (ADS)

Królikowska, Małgorzata; Dybczyński, Piotr A.

2013-10-01

Dynamics of a complete sample of small perihelion distance near-parabolic comets discovered in the years 2006-2010 are studied (i.e. of 22 comets of qosc < 3.1 au). First, osculating orbits are obtained after a very careful positional data inspection and processing, including where appropriate, the method of data partitioning for determination of pre- and post-perihelion orbit for tracking then its dynamical evolution. The non-gravitational acceleration in the motion is detected for 50 per cent of investigated comets, in a few cases for the first time. Different sets of non-gravitational parameters are determined from pre- and post-perihelion data for some of them. The influence of the positional data structure on the possibility of the detection of non-gravitational effects and the overall precision of orbit determination is widely discussed. Secondly, both original and future orbits were derived by means of numerical integration of swarms of virtual comets obtained using a Monte Carlo cloning method. This method allows us to follow the uncertainties of orbital elements at each step of dynamical evolution. The complete statistics of original and future orbits that includes significantly different uncertainties of 1/a-values is presented, also in the light of our results obtained earlier. Basing on 108 comets examined by us so far, we conclude that only one of them, C/2007 W1 Boattini, seems to be a serious candidate for an interstellar comet. We also found that 53 per cent of 108 near-parabolic comets escaping in the future from the Solar system, and the number of comets leaving the Solar system as so called Oort spike comets (i.e. comets suffering very small planetary perturbations) is 14 per cent. A new method for cometary orbit quality assessment is also proposed by means of modifying the original method, introduced by Marsden, Sekanina & Everhart. This new method leads to a better diversification of orbit quality classes for contemporary comets.

Prediction of quantum interference in molecular junctions using a parabolic diagram: Understanding the origin of Fano and anti- resonances

NASA Astrophysics Data System (ADS)

Nozaki, Daijiro; Avdoshenko, Stanislav M.; Sevinçli, Hâldun; Gutierrez, Rafael; Cuniberti, Gianaurelio

2013-03-01

Recently the interest in quantum interference (QI) phenomena in molecular devices (molecular junctions) has been growing due to the unique features observed in the transmission spectra. In order to design single molecular devices exploiting QI effects as desired, it is necessary to provide simple rules for predicting the appearance of QI effects such as anti-resonances or Fano line shapes and for controlling them. In this study, we derive a transmission function of a generic molecular junction with a side group (T-shaped molecular junction) using a minimal toy model. We developed a simple method to predict the appearance of quantum interference, Fano resonances or anti- resonances, and its position in the conductance spectrum by introducing a simple graphical representation (parabolic model). Using it we can easily visualize the relation between the key electronic parameters and the positions of normal resonant peaks and anti-resonant peaks induced by quantum interference in the conductance spectrum. We also demonstrate Fano and anti-resonance in T-shaped molecular junctions using a simple tight-binding model. This parabolic model enables one to infer on-site energies of T-shaped molecules and the coupling between side group and main conduction channel from transmission spectra.

In situ X-ray diffraction contribution to the study of reactive element oxide coating effect on the high temperature oxidation behaviour of FeCrAl alloys

NASA Astrophysics Data System (ADS)

Cueff, R.; Buscail, H.; Caudron, E.; Riffard, F.; Issartel, C.; Perrier, S.; El Messki, S.

2004-11-01

The influence of yttrium oxide coating (processed by sol-gel method) on the oxidation behaviour of a commercial FeCrAl alloy (Kanthal A1) has been investigated during isothermal exposures in air at 1373K. The scale growth kinetic of the uncoated alloy obeys a parabolic rate law during the whole oxidation test whereas the kinetic curve of the Y-coated specimen exhibits an initial transient stage during the first hours, followed by a parabolic regime. The yttrium sol-gel coating deposited on the bare alloy does not conduct to the beneficial effect usually ascribed to the reactive elements. No oxidation rate improvement of the coated alloy is observed, the parabolic rate constants values are strictly identical for the both specimens. In situ X-ray diffraction reveals a marked influence of the reactive element on the composition of the oxide scale. The oxide layer formed on the yttrium-coated specimen revealed, in addition to α-alumina which is the main oxide also identified on the bare specimen, the presence of yttrium aluminates (YAlO{3}, Y{3}Al{5}O{12}) located in the outermost part of the layer.

A parabolic velocity-decomposition method for wind turbines

NASA Astrophysics Data System (ADS)

Mittal, Anshul; Briley, W. Roger; Sreenivas, Kidambi; Taylor, Lafayette K.

2017-02-01

An economical parabolized Navier-Stokes approximation for steady incompressible flow is combined with a compatible wind turbine model to simulate wind turbine flows, both upstream of the turbine and in downstream wake regions. The inviscid parabolizing approximation is based on a Helmholtz decomposition of the secondary velocity vector and physical order-of-magnitude estimates, rather than an axial pressure gradient approximation. The wind turbine is modeled by distributed source-term forces incorporating time-averaged aerodynamic forces generated by a blade-element momentum turbine model. A solution algorithm is given whose dependent variables are streamwise velocity, streamwise vorticity, and pressure, with secondary velocity determined by two-dimensional scalar and vector potentials. In addition to laminar and turbulent boundary-layer test cases, solutions for a streamwise vortex-convection test problem are assessed by mesh refinement and comparison with Navier-Stokes solutions using the same grid. Computed results for a single turbine and a three-turbine array are presented using the NREL offshore 5-MW baseline wind turbine. These are also compared with an unsteady Reynolds-averaged Navier-Stokes solution computed with full rotor resolution. On balance, the agreement in turbine wake predictions for these test cases is very encouraging given the substantial differences in physical modeling fidelity and computer resources required.

Survey mirrors and lenses and their required surface accuracy. Volume 2. Concentrator optical performance software (COPS) user's manual. Final report for September 15, 1978-December 1, 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-01-01

The mathematical modeling of 11 different concentrating collectors is documented and instructions are given for use of the computer code. The 11 concentrators modeled are: faceted mirror concentration; fixed mirror, two-axis tracking receiver; parabolic trough collector; linear Fresnel; incremental reflector; inflated cylindrical concentrator; CPC-involute reflector with evacuated receiver; CPC-parabolic/involute reflector; V trough collectors, imaging collapsing concentrator; and parabolic dish collector. (MHR)

A parabolic function to modify Thornthwaite estimates of potential evapotranspiration for the eastern United States

USGS Publications Warehouse

McCabe, G.J.

1989-01-01

Errors of the Thornthwaite model can be analyzed using adjusted pan evaporation as an index of potential evapotranspiration. An examination of ratios of adjusted pan evaporation to Thornthwaite potential evapotranspiration indicates that the ratios are highest in the winter and lowest during summer months. This trend suggests a parabolic pattern. In this study a parabolic function is used to adjust Thornthwaite estimates of potential evapotranspiration. Forty locations east of the Rocky Mountains are analyzed. -from Author

Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

NASA Astrophysics Data System (ADS)

Yan, Na; Baas, Andreas

2015-04-01

Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation and a parabolic-to-barchan dune transformation have been identified. These zones exhibit different characteristics and dynamics that are sensitive to changes in environmental forces, and can be potentially used as a proxy to monitor the mobility of a dune system.

Planar dielectric waveguides in rotation are optical fibers: comparison with the classical model.

PubMed

Peña García, Antonio; Pérez-Ocón, Francisco; Jiménez, José Ramón

2008-01-21

A novel and simpler method to calculate the main parameters in fiber optics is presented. This method is based in a planar dielectric waveguide in rotation and, as an example, it is applied to calculate the turning points and the inner caustic in an optical fiber with a parabolic refractive index. It is shown that the solution found using this method agrees with the standard (and more complex) method, whose solutions for these points are also summarized in this paper.

Analysis of compound parabolic concentrators and aperture averaging to mitigate fading on free-space optical links

NASA Astrophysics Data System (ADS)

Wasiczko, Linda M.; Smolyaninov, Igor I.; Davis, Christopher C.

2004-01-01

Free space optics (FSO) is one solution to the bandwidth bottleneck resulting from increased demand for broadband access. It is well known that atmospheric turbulence distorts the wavefront of a laser beam propagating through the atmosphere. This research investigates methods of reducing the effects of intensity scintillation and beam wander on the performance of free space optical communication systems, by characterizing system enhancement using either aperture averaging techniques or nonimaging optics. Compound Parabolic Concentrators, nonimaging optics made famous by Winston and Welford, are inexpensive elements that may be easily integrated into intensity modulation-direct detection receivers to reduce fading caused by beam wander and spot breakup in the focal plane. Aperture averaging provides a methodology to show the improvement of a given receiver aperture diameter in averaging out the optical scintillations over the received wavefront.

Influences of temperature and impurity on excited state of bound polaron in the parabolic quantum dots

NASA Astrophysics Data System (ADS)

Xiao, Jing-Lin

2014-06-01

On the condition of strong electron-LO phonon coupling in parabolic quantum dot (QD), the first excited state energy, the excitation energy and the transition frequency between the first excited and the ground states of the bound polaron are calculated by using the linear combination operator and the unitary transformation methods. The variation of the above quantities with the temperature, the Coulombic impurity potential and the QD confinement strength are studied in detail. We find that (1) These physical quantities will increase with increasing temperature. (2) They are increasing functions of the confinement strength due to the existence of the Coulombic impurity potential between the electron and the hydrogen-like impurity. (3) We obtain three ways of tuning them via controlling the temperature, the Coulombic impurity potential and the confinement strength.

Numerical Simulations of Free Surface Magnetohydrodynamic Flows

NASA Astrophysics Data System (ADS)

Samulyak, Roman; Glimm, James; Oh, Wonho; Prykarpatskyy, Yarema

2003-11-01

We have developed a numerical algorithm and performed simulations of magnetohydrodynamic (MHD) free surface flows. The corresponding system of MHD equations is a system of strongly coupled hyperbolic and parabolic/elliptic equations in moving and geometrically complex domains. The hyperbolic system is solved using the front tracking technique for the free fluid interface. Parallel algorithms for solving elliptic and parabolic equations are based on a finite element discretization on moving grids dynamically conforming to fluid interfaces. The method has been implemented as an MHD extension of the FronTier code. The code has been applied for modeling the behavior of lithium and mercury jets in magnetic fields, laser ablation plumes, and the Richtmyer-Meshkov instability of a liquid mercury jet interacting with a high energy proton pulse in a strong magnetic field. Such an instability occurs in the target for the Muon Collider.

An improved method for calculating power density in the Fresnel region of circular parabolic reflector antennas

NASA Astrophysics Data System (ADS)

Mize, Johnnie E.

1988-03-01

A computer program is presented which calculates power density in the Fresnel region of circular parabolic reflector antennas. The aperture illumination model is the one-parameter circular distribution developed by Hansen. The program is applicable to the analysis of electrically large, center-fed (or Cassegrain) paraboloids with linearly polarized feeds. The scalar Kirchoff diffraction integral is solved numerically by Romberg integration for points both on and perpendicular to the antenna boresight. Axial results cannot be directly compared to any others obtained with this illumination model, but they are consistent with what is expected in the Fresnel region where a quadratic must be added to the linear phase term of the integral expression. Graphical results are presented for uniform illumination and for cases where the first sidelobe ratio is 20, 25, 30, and 35 dB.

Antenna cab interior showing waveguide from external parabolic antenna (later ...

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

Antenna cab interior showing waveguide from external parabolic antenna (later addition), looking north. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

Concentrating Solar Power Projects | Concentrating Solar Power | NREL

Science.gov Websites

construction, or under development. CSP technologies include parabolic trough, linear Fresnel reflector, power Technology-listing by parabolic trough, linear Fresnel reflector, power tower, or dish/engine systems Status

Finite-time blow-up for quasilinear degenerate Keller-Segel systems of parabolic-parabolic type

NASA Astrophysics Data System (ADS)

Hashira, Takahiro; Ishida, Sachiko; Yokota, Tomomi

2018-05-01

This paper deals with the quasilinear degenerate Keller-Segel systems of parabolic-parabolic type in a ball of RN (N ≥ 2). In the case of non-degenerate diffusion, Cieślak-Stinner [3,4] proved that if q > m + 2/N, where m denotes the intensity of diffusion and q denotes the nonlinearity, then there exist initial data such that the corresponding solution blows up in finite time. As to the case of degenerate diffusion, it is known that a solution blows up if q > m + 2/N (see Ishida-Yokota [13]); however, whether the blow-up time is finite or infinite has been unknown. This paper gives an answer to the unsolved problem. Indeed, the finite-time blow-up of energy solutions is established when q > m + 2/N.

Efficient dispersion tailoring by designing alternately arranged dispersion compensating fibers and fiber amplifiers to create self-similar parabolic pulses

NASA Astrophysics Data System (ADS)

Ghosh, Dipankar; Basu, Mousumi

2010-11-01

The parabolic similariton pulse formation by alternate arrangements of passive and active dispersion compensating fibers (DCFs) is presented here. These combinations of passive and active DCFs with constant core radii and constant nonlinearities are suggested as equivalent profiles of a dispersion tailored fiber amplifier in normal dispersion regime. The dispersion tailored fibers, usually known as dispersion decreasing fibers (DDFs) in normal dispersion regime, are capable of producing linearly chirped parabolic self-similar pulses. The DDF is designed and optimized with proper choice of fiber parameters so that considerable variation of nonlinearity can be achieved, which in turn enhances the effective gain coefficient of the fiber. Inclusion of this nonlinear variation along the DDF amplifier length leads to obtain the simulated output pulses with very small misfit parameters with respect to perfect parabolic pulse at sufficiently reduced optimum length. At the same time to avoid the fabrication difficulties of the DDF, the alternately arranged passive and active DCFs are suggested as suitable alternatives of the DDF. The performances of the cascaded systems for generation of self-similar parabolic pulses are compared with that of the DDF amplifier as well as combined systems consisting of DCFs with equal gain. The results show that the proposed alternately arranged cascaded system with less pumping requirements, are efficient enough to produce similar parabolic pulses as compared to the previously designed DDF, even when considerable amount of splice loss at each joint is included.

The effect of São Paulo's smoke-free legislation on carbon monoxide concentration in hospitality venues and their workers

PubMed Central

Abe, Tania M O; Pereira, Alexandre C; Megid, Maria Cristina; Shimabukuro, Cristina E; Valentin, Luis Sergio O; da C Ferreira, Marizete M; Nobre, Moacyr R C; Lancarotte, Ines; Barretto, Antonio Carlos Pereira

2010-01-01

Background Studies have shown that there is no safe level of secondhand smoke (SHS) exposure and there is a close link between SHS and the risk of coronary heart disease and stroke. Carbon monoxide (CO) is one of the most important components present in SHS. Objective To evaluate the impact of the smoking ban law in the city of Sao Paulo, Brazil, on the CO concentration in restaurants, bars, night clubs and similar venues and in their workers. Methods In the present study we measured CO concentration in 585 hospitality venues. CO concentration was measured in different environments (indoor, semi-open and open areas) from visited venues, as well as, in the exhaled air from approximately 627 workers of such venues. Measurements were performed twice, before and 12 weeks after the law implementation. In addition, the quality of the air in the city during the same period of our study was verified. Results The CO concentration pre-ban and pot-ban in hospitality venues was indoor area 4.57 (3.70) ppm vs 1.35 (1.66) ppm (p<0.0001); semi-open 3.79 (2.49) ppm vs 1.16 (1.14) ppm (p<0.0001); open area 3.31(2.2) ppm vs 1.31 (1.39) ppm (p<0.0001); smoking employees 15.78 (9.76) ppm vs 11.50 (7.53) ppm (p<0.0001) and non-smoking employees 6.88 (5.32) ppm vs 3.50 (2.21) ppm (p<0.0001). The average CO concentration measured in the city was lower than 1 ppm during both pre-ban and post-ban periods. Conclusion São Paulo's smoking-free legislation reduced significantly the CO concentration in hospitality venues and in their workers, whether they smoke or not. PMID:21109684

Field determination of microgram quantities of niobium in rocks

USGS Publications Warehouse

Ward, F.N.; Marranzino, A.P.

1955-01-01

A rapid, simple, and moderately accurate method was needed for the determination of traces of niobium in rocks. The method developed is based on the reaction of niobium(V) with thiocyanate ion in a 4M hydrochloric acid and 0.5M tartaric acid medium, after which the complex is extracted with ethyl ether. The proposed procedure is applicable to rocks containing from 50 to 2000 p.p.m. of niobium, and, with modifications, can be used on rocks containing larger amounts. Five determinations on two rocks containing 100 p.p.m. or less of niobium agree within 5 p.p.m. of the mean, and the confidence limits at the 95% level are, respectively, ??6 and ??4 p.p.m. The addition of acetone to the ether extract of the niobium thiocyanate inhibits the polymerization of the thiocyanate ion and stabilizes the solution for at least 20 hours. The proposed procedure permits the determination of 20 ?? of niobium in the presence of 1000 ?? of iron, titanium, or uranium; 500 ?? of vanadium; or 100 ?? of tungsten or molybdenum or both.

Finite Difference Time Marching in the Frequency Domain: A Parabolic Formulation for the Convective Wave Equation

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Kreider, K. L.

1996-01-01

An explicit finite difference iteration scheme is developed to study harmonic sound propagation in ducts. To reduce storage requirements for large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable, time is introduced into the Fourier transformed (steady-state) acoustic potential field as a parameter. Under a suitable transformation, the time dependent governing equation in frequency space is simplified to yield a parabolic partial differential equation, which is then marched through time to attain the steady-state solution. The input to the system is the amplitude of an incident harmonic sound source entering a quiescent duct at the input boundary, with standard impedance boundary conditions on the duct walls and duct exit. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.

Contour-Based Corner Detection and Classification by Using Mean Projection Transform

PubMed Central

Kahaki, Seyed Mostafa Mousavi; Nordin, Md Jan; Ashtari, Amir Hossein

2014-01-01

Image corner detection is a fundamental task in computer vision. Many applications require reliable detectors to accurately detect corner points, commonly achieved by using image contour information. The curvature definition is sensitive to local variation and edge aliasing, and available smoothing methods are not sufficient to address these problems properly. Hence, we propose Mean Projection Transform (MPT) as a corner classifier and parabolic fit approximation to form a robust detector. The first step is to extract corner candidates using MPT based on the integral properties of the local contours in both the horizontal and vertical directions. Then, an approximation of the parabolic fit is calculated to localize the candidate corner points. The proposed method presents fewer false-positive (FP) and false-negative (FN) points compared with recent standard corner detection techniques, especially in comparison with curvature scale space (CSS) methods. Moreover, a new evaluation metric, called accuracy of repeatability (AR), is introduced. AR combines repeatability and the localization error (Le) for finding the probability of correct detection in the target image. The output results exhibit better repeatability, localization, and AR for the detected points compared with the criteria in original and transformed images. PMID:24590354

Contour-based corner detection and classification by using mean projection transform.

PubMed

Kahaki, Seyed Mostafa Mousavi; Nordin, Md Jan; Ashtari, Amir Hossein

2014-02-28

Image corner detection is a fundamental task in computer vision. Many applications require reliable detectors to accurately detect corner points, commonly achieved by using image contour information. The curvature definition is sensitive to local variation and edge aliasing, and available smoothing methods are not sufficient to address these problems properly. Hence, we propose Mean Projection Transform (MPT) as a corner classifier and parabolic fit approximation to form a robust detector. The first step is to extract corner candidates using MPT based on the integral properties of the local contours in both the horizontal and vertical directions. Then, an approximation of the parabolic fit is calculated to localize the candidate corner points. The proposed method presents fewer false-positive (FP) and false-negative (FN) points compared with recent standard corner detection techniques, especially in comparison with curvature scale space (CSS) methods. Moreover, a new evaluation metric, called accuracy of repeatability (AR), is introduced. AR combines repeatability and the localization error (Le) for finding the probability of correct detection in the target image. The output results exhibit better repeatability, localization, and AR for the detected points compared with the criteria in original and transformed images.

Finite Difference Time Marching in the Frequency Domain: A Parabolic Formulation for Aircraft Acoustic Nacelle Design

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1996-01-01

An explicit finite difference iteration scheme is developed to study harmonic sound propagation in aircraft engine nacelles. To reduce storage requirements for large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable, time is introduced into the Fourier transformed (steady-state) acoustic potential field as a parameter. Under a suitable transformation, the time dependent governing equation in frequency space is simplified to yield a parabolic partial differential equation, which is then marched through time to attain the steady-state solution. The input to the system is the amplitude of an incident harmonic sound source entering a quiescent duct at the input boundary, with standard impedance boundary conditions on the duct walls and duct exit. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.

An efficient mode-splitting method for a curvilinear nearshore circulation model

USGS Publications Warehouse

Shi, Fengyan; Kirby, James T.; Hanes, Daniel M.

2007-01-01

A mode-splitting method is applied to the quasi-3D nearshore circulation equations in generalized curvilinear coordinates. The gravity wave mode and the vorticity wave mode of the equations are derived using the two-step projection method. Using an implicit algorithm for the gravity mode and an explicit algorithm for the vorticity mode, we combine the two modes to derive a mixed difference–differential equation with respect to surface elevation. McKee et al.'s [McKee, S., Wall, D.P., and Wilson, S.K., 1996. An alternating direction implicit scheme for parabolic equations with mixed derivative and convective terms. J. Comput. Phys., 126, 64–76.] ADI scheme is then used to solve the parabolic-type equation in dealing with the mixed derivative and convective terms from the curvilinear coordinate transformation. Good convergence rates are found in two typical cases which represent respectively the motions dominated by the gravity mode and the vorticity mode. Time step limitations imposed by the vorticity convective Courant number in vorticity-mode-dominant cases are discussed. Model efficiency and accuracy are verified in model application to tidal current simulations in San Francisco Bight.

Geochemical study of urban soils in public areas of an industrialized town (Ajka, western Hungary)

NASA Astrophysics Data System (ADS)

Zacháry, D.; Jordán, Gy.; Szabó, Cs.

2012-04-01

Soil is one of the most essential parts of urban ecosystem contributing to the biogeochemical cycles along the rock-soil-plant-animal and human pathway. Soil plays a fundamental role in plant nutrient uptake and groundwater filtration, too. Urban soils differ from non-urban soils in many aspects, including their origin, and they may also concentrate contaminants in large quantities due to intensive human activities. The pollution sources are industry, traffic, fertilizer, tailing and waste. In addition to the increasing rate of urban areas, urban soils are under growing interest and their pollution have received significant attention in the past few decades. This work focuses on the toxic element (As, Hg, Pb, Cu, Zn, Cd, Ni) content of soils and their spatial distribution in order to find a link between contamination sources and the receiving urban soils at sensitive receptor locations such as children's playgrounds and parks. Ajka town is located in western Hungary. It has an old-established industrial history with multiple contamination sources of heavy alumina industry and coal-based power plants supplied by the nearby bauxite and coal mines. At 44 locations 46 soil samples have been collected at a depth of 0-10 cm along a 1x1 km grid. The whole grid covers an area of 48 km2. In each grid cell a sampling site was selected at public areas. Sample preparation included drying at 40 C°, thorough homogenization and sieving to 2 mm fine earth before chemical analysis. Grain size distribution and soil pH were also determined. Samples were analyzed with ICP-OES and SEM methods. The As, Hg, Pb, Cu, Zn, Cd and Ni concentrations range from 2.07 ppm to 9.48 ppm, 0.02 ppm to 2.84 ppm, 5.08 ppm to 35.74 ppm, 2.55 ppm to 47.78 ppm, 17.00 ppm to 91.00 ppm, 0.07 ppm to 0.61 ppm and 5.57 ppm to 32.09 ppm, respectively. The results revealed the contaminated areas associated with past industrial sites. This study also identified locations with considerable contamination at sensitive receptors in urban public areas, thus supporting contamination risk assessment for environmental decisions.

Doubly labelled water assessment of energy expenditure: principle, practice, and promise.

PubMed

Westerterp, Klaas R

2017-07-01

The doubly labelled water method for the assessment of energy expenditure was first published in 1955, application in humans started in 1982, and it has become the gold standard for human energy requirement under daily living conditions. The method involves enriching the body water of a subject with heavy hydrogen ( 2 H) and heavy oxygen ( 18 O), and then determining the difference in washout kinetics between both isotopes, being a function of carbon dioxide production. In practice, subjects get a measured amount of doubly labelled water ( 2 H 2 18 O) to increase background enrichment of body water for 18 O of 2000 ppm with at least 180 ppm and background enrichment of body water for 2 H of 150 ppm with 120 ppm. Subsequently, the difference between the apparent turnover rates of the hydrogen and oxygen of body water is assessed from blood-, saliva-, or urine samples, collected at the start and end of the observation interval of 1-3 weeks. Samples are analyzed for 18 O and 2 H with isotope ratio mass spectrometry. The doubly labelled water method is the indicated method to measure energy expenditure in any environment, especially with regard to activity energy expenditure, without interference with the behavior of the subjects. Applications include the assessment of energy requirement from total energy expenditure, validation of dietary assessment methods and validation of physical activity assessment methods with doubly labelled water measured energy expenditure as reference, and studies on body mass regulation with energy expenditure as a determinant of energy balance.

Antioxidant activities of nano-bubble hydrogen-dissolved water assessed by ESR and 2,2'-bipyridyl methods.

PubMed

Kato, Shinya; Matsuoka, Daigo; Miwa, Nobuhiko

2015-08-01

We prepared nano-bubble hydrogen-dissolved water (nano-H water) which contained hydrogen nano-bubbles of <717-nm diameter for 54% of total bubbles. In the DMPO-spin trap electron spin resonance (ESR) method, the DMPO-OH:MnO ratio, being attributed to amounts of hydroxyl radicals (OH), was 2.78 for pure water (dissolved hydrogen [DH]≤0.01 ppm, oxidation-reduction potential [ORP]=+324 mV), 2.73 for tap water (0.01 ppm, +286 mV), 2.93 for commercially available hydrogen water (0.075 ppm, +49 mV), and 2.66 for manufactured hydrogen water (0.788 ppm, -614 mV), whereas the nano-H water (0.678 ppm, -644 mV) exhibited 2.05, showing the superiority of nano-H water to other types of hydrogen water in terms of OH-scavenging activity. Then, the reduction activity of nano-H water was assessed spectrophotometrically by the 2,2'-bipyridyl method. Differential absorbance at 530 nm was in the order: 0.018 for pure water, 0.055 for tap water, 0.079 for nano-H water, 0.085 for commercially available hydrogen water, and 0.090 for manufactured hydrogen water, indicating a prominent reduction activity of hydrogen water and nano-H water against oxidation in ascorbate-coupled ferric ion-bipyridyl reaction. Thus, nano-H water has an improved antioxidant activity as compared to hydrogen water of similar DH-level, indicating the more marked importance of nano-bubbles rather than the concentration of hydrogen in terms of OH-scavenging. Copyright © 2015 Elsevier B.V. All rights reserved.

The dynamics of parabolic flight: flight characteristics and passenger percepts.

PubMed

Karmali, Faisal; Shelhamer, Mark

2008-09-01

Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 seconds of freefall (0 g) followed by 40 seconds of enhanced force (1.8 g), repeated 30-60 times. Although passengers perceive gravity to be zero, in actuality acceleration, and not gravity, has changed, and thus we caution against the terms "microgravity" and "zero gravity. " Despite the aircraft trajectory including large (45°) pitch-up and pitch-down attitudes, the occupants experience a net force perpendicular to the floor of the aircraft. This is because the aircraft generates appropriate lift and thrust to produce the desired vertical and longitudinal accelerations, respectively, although we measured moderate (0.2 g) aft-ward accelerations during certain parts of these trajectories. Aircraft pitch rotation (average 3°/s) is barely detectable by the vestibular system, but could influence some physics experiments. Investigators should consider such details in the planning, analysis, and interpretation of parabolic-flight experiments.

Penning Ionization Electron Spectroscopy in Glow Discharge: A New Dimension for Gas Chromatography Detectors

NASA Technical Reports Server (NTRS)

Sheverev, V. A.; Khromov, N. A.; Kojiro, D. R.; Fonda, Mark (Technical Monitor)

2002-01-01

Admixtures to helium of 100 ppm and 5 ppm of nitrogen, and 100 ppm and 10 ppm of carbon monoxide were identified and measured in the helium discharge afterglow using an electrical probe placed into the plasma. For nitrogen and carbon monoxide gases, the measured electron energy spectra display distinct characteristic peaks (fingerprints). Location of the peaks on the energy scale is determined by the ionization energies of the analyte molecules. Nitrogen and carbon monoxide fingerprints were also observed in a binary mixture of these gases in helium, and the relative concentration analytes has been predicted. The technically simple and durable method is considered a good candidate for a number of analytical applications, and in particular, in GC and for analytical flight instrumentation.

Solutions to variational inequalities of parabolic type

NASA Astrophysics Data System (ADS)

Zhu, Yuanguo

2006-09-01

The existence of strong solutions to a kind of variational inequality of parabolic type is investigated by the theory of semigroups of linear operators. As an application, an abstract semi permeable media problem is studied.

A practical derivatization LC/MS approach for determination of trace level alkyl sulfonates and dialkyl sulfates genotoxic impurities in drug substances.

PubMed

An, Jianguo; Sun, Mingjiang; Bai, Lin; Chen, Ted; Liu, David Q; Kord, Alireza

2008-11-04

Derivatization LC/MS methodology has been developed for the determination of a group of commonly encountered alkyl esters of sulfonates or sulfates in drug substances at low ppm levels. This general method uses trimethylamine as the derivatizing reagent for ethyl/propyl/isopropyl esters and triethylamine for methyl esters. The resulting quaternary ammonium derivatization products are highly polar (ionic) and can be retained by a hydrophilic interaction liquid chromatography (HILIC) column and readily separated from the main interfering active pharmaceutical ingredient (API) peak that is usually present at very high concentration. The method gives excellent sensitivity for all the alkyl esters at typical target analyte level of 1-2 ppm when the API samples were prepared at 5mg/mL. The recoveries at 1-2 ppm were generally above 85% for all the alkyl esters in the various APIs tested. The injection precisions of the lowest concentration standards were excellent with R.S.D.=0.4-4%. A linear range for concentrations from 0.2 to 20 ppm has been established with R(2)>or=0.99. This general method has been tested in a number of API matrices and used successfully for determination of alkyl sulfonates or dialkyl sulfates in support of API batch releases at GlaxoSmithKline.

Rapid, quantitative analysis of ppm/ppb nicotine using surface-enhanced Raman scattering from polymer-encapsulated Ag nanoparticles (gel-colls).

PubMed

Bell, Steven E J; Sirimuthu, Narayana M S

2004-11-01

Rapid, quantitative SERS analysis of nicotine at ppm/ppb levels has been carried out using stable and inexpensive polymer-encapsulated Ag nanoparticles (gel-colls). The strongest nicotine band (1030 cm(-1)) was measured against d(5)-pyridine internal standard (974 cm(-1)) which was introduced during preparation of the stock gel-colls. Calibration plots of I(nic)/I(pyr) against the concentration of nicotine were non-linear but plotting I(nic)/I(pyr) against [nicotine](x)(x = 0.6-0.75, depending on the exact experimental conditions) gave linear calibrations over the range (0.1-10 ppm) with R(2) typically ca. 0.998. The RMS prediction error was found to be 0.10 ppm when the gel-colls were used for quantitative determination of unknown nicotine samples in 1-5 ppm level. The main advantages of the method are that the gel-colls constitute a highly stable and reproducible SERS medium that allows high throughput (50 sample h(-1)) measurements.

Spectral methods for time dependent problems

NASA Technical Reports Server (NTRS)

Tadmor, Eitan

1990-01-01

Spectral approximations are reviewed for time dependent problems. Some basic ingredients from the spectral Fourier and Chebyshev approximations theory are discussed. A brief survey was made of hyperbolic and parabolic time dependent problems which are dealt with by both the energy method and the related Fourier analysis. The ideas presented above are combined in the study of accuracy stability and convergence of the spectral Fourier approximation to time dependent problems.

Accelerating Airy beams with non-parabolic trajectories

NASA Astrophysics Data System (ADS)

Besieris, Ioannis M.; Shaarawi, Amr M.

2014-11-01

A class of Airy accelerating beams with non-parabolic trajectories are derived by means of a novel application of a conformal transformation originally due to Bateman. It is also shown that the salient features of these beams are very simply incorporated in a solution which is derived by applying a conventional conformal transformation together with a Galilean translation to the basic accelerating Airy beam solution of the two-dimensional paraxial equation. Motivation for the non-parabolic beam trajectories is provided and the effects of finite-energy requirements are discussed.

Critical spaces for quasilinear parabolic evolution equations and applications

NASA Astrophysics Data System (ADS)

Prüss, Jan; Simonett, Gieri; Wilke, Mathias

2018-02-01

We present a comprehensive theory of critical spaces for the broad class of quasilinear parabolic evolution equations. The approach is based on maximal Lp-regularity in time-weighted function spaces. It is shown that our notion of critical spaces coincides with the concept of scaling invariant spaces in case that the underlying partial differential equation enjoys a scaling invariance. Applications to the vorticity equations for the Navier-Stokes problem, convection-diffusion equations, the Nernst-Planck-Poisson equations in electro-chemistry, chemotaxis equations, the MHD equations, and some other well-known parabolic equations are given.

A Harnack's inequality for mixed type evolution equations

NASA Astrophysics Data System (ADS)

Paronetto, Fabio

2016-03-01

We define a homogeneous parabolic De Giorgi classes of order 2 which suits a mixed type class of evolution equations whose simplest example is μ (x)∂u/∂t - Δu = 0 where μ can be positive, null and negative, so in particular elliptic-parabolic and forward-backward parabolic equations are included. For functions belonging to this class we prove local boundedness and show a Harnack inequality which, as by-products, gives Hölder-continuity, in particular in the interface I where μ changes sign, and a maximum principle.

Numerical solution of the stochastic parabolic equation with the dependent operator coefficient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashyralyev, Allaberen; Department of Mathematics, ITTU, Ashgabat; Okur, Ulker

2015-09-18

In the present paper, a single step implicit difference scheme for the numerical solution of the stochastic parabolic equation with the dependent operator coefficient is presented. Theorem on convergence estimates for the solution of this difference scheme is established. In applications, this abstract result permits us to obtain the convergence estimates for the solution of difference schemes for the numerical solution of initial boundary value problems for parabolic equations. The theoretical statements for the solution of this difference scheme are supported by the results of numerical experiments.

Word and frame synchronization with verification for PPM optical communications

NASA Technical Reports Server (NTRS)

Marshall, William K.

1986-01-01

A method for obtaining word and frame synchronization in pulse position modulated optical communication systems is described. The method uses a short sync sequence inserted at the beginning of each data frame and a verification procedure to distinguish between inserted and randomly occurring sequences at the receiver. This results in an easy to implement sync system which provides reliable synchronization even at high symbol error rates. Results are given for the application of this approach to a highly energy efficient 256-ary PPM test system.

Interpolator for numerically controlled machine tools

DOEpatents

Bowers, Gary L.; Davenport, Clyde M.; Stephens, Albert E.

1976-01-01

A digital differential analyzer circuit is provided that depending on the embodiment chosen can carry out linear, parabolic, circular or cubic interpolation. In the embodiment for parabolic interpolations, the circuit provides pulse trains for the X and Y slide motors of a two-axis machine to effect tool motion along a parabolic path. The pulse trains are generated by the circuit in such a way that parabolic tool motion is obtained from information contained in only one block of binary input data. A part contour may be approximated by one or more parabolic arcs. Acceleration and initial velocity values from a data block are set in fixed bit size registers for each axis separately but simultaneously and the values are integrated to obtain the movement along the respective axis as a function of time. Integration is performed by continual addition at a specified rate of an integrand value stored in one register to the remainder temporarily stored in another identical size register. Overflows from the addition process are indicative of the integral. The overflow output pulses from the second integration may be applied to motors which position the respective machine slides according to a parabolic motion in time to produce a parabolic machine tool motion in space. An additional register for each axis is provided in the circuit to allow "floating" of the radix points of the integrand registers and the velocity increment to improve position accuracy and to reduce errors encountered when the acceleration integrand magnitudes are small when compared to the velocity integrands. A divider circuit is provided in the output of the circuit to smooth the output pulse spacing and prevent motor stall, because the overflow pulses produced in the binary addition process are spaced unevenly in time. The divider has the effect of passing only every nth motor drive pulse, with n being specifiable. The circuit inputs (integrands, rates, etc.) are scaled to give exactly n times the desired number of pulses out, in order to compensate for the divider.

Activity of Kaempferia pandurata (Roxb.) rhizome ethanol extract against MRSA, MRCNS, MSSA, Bacillus subtilis and Salmonella typhi.

PubMed

Sukandar, Elin Yulinah; Sunderam, Nethiyakalyani; Fidrianny, Irda

2014-01-01

Temu kunci (Kaempferia pandurata (Roxb.)) has a number of benefits and one of these is antibacterial. The rhizome is said to have antibacterial activity against Streptococcus mutans, Lactocillus sp. and Candida albicans. The aim of the study is to test the antibacterial activity of Kaempferia pandurata (Roxb.) rhizome ethanol extract on methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase negative Staphylococci (MRCNS), methicillin-sensitive Staphylococcus aureus (MSSA), Bacillus subtilis and Salmonella typhi. Antimicrobial activity of the extract was assayed by the microdilution method using Mueller Hinton Broth with sterilized 96 round-bottomed microwells to determine the Minimum Inhibitory Concentration (MIC) as well as to determine the time-kill activity. The MIC of the extract was 16 ppm for both Bacillus subtilis and MRSA; 8 ppm for both MSSA and Salmonella typhi and 4 ppm for MRCNS. Ethanol extract of Kaempferia pandurata (Roxb.) showed antibacterial activity against all the tested bacteria and was the most potent against MRCNS, with MIC 4 ppm. The killing profile test of the extract displayed bactericidal activity at 8-16 ppm against MRSA, MSSA, Bacillus subtilis and Salmonella typhi and bacteriostatic activity at 4 ppm towards MRCNS.

Simultaneous screening and confirmation of multiple classes of drug residues in fish by liquid chromatography-ion trap mass spectrometry.

PubMed

Smith, Shani; Gieseker, Charles; Reimschuessel, Renate; Decker, Christie-Sue; Carson, Mary C

2009-11-13

LC-ion trap mass spectrometry was used to screen and confirm 38 compounds from a variety of drug classes in four species of fish: trout, salmon, catfish, and tilapia. Samples were extracted with acetonitrile and hexane. The acetonitrile phase was evaporated, redissolved in water and acetonitrile, and analyzed by gradient chromatography on a phenyl column. MS(2) or MS(3) spectra were monitored for each compound. Qualitative method performance was evaluated by the analysis over several days of replicate samples of control fish, fish fortified with a drug mixture at 1 ppm, 0.1 ppm and 0.01 ppm, and fish dosed with a representative from each drug class. Half of the 38 drugs were confirmed at 0.01 ppm, the lowest fortification level. This included all of the quinolones and fluoroquinolones, the macrolides, malachite green, and most of the imidazoles. Florfenicol amine, metronidazole, sulfonamides, tetracyclines, and most of the betalactams were confirmed at 0.1 ppm. Ivermectin and penicillin G were only detectable in the 1 ppm fortified samples. With the exception of amoxicillin, emamectin, metronidazole, and tylosin, residue presence was confirmed in all the dosed fish.

High temperature oxidation of alumina forming cast austenitic stainless steels within an environment of pure steam

NASA Astrophysics Data System (ADS)

Prenzlow, Elmer A.

Steam cracking of hydrocarbons in the petrochemical industry is a multibillion dollar industry. The processes performed in these plants create byproducts that negatively affect the integrity of stainless steel piping through high temperature corrosion. Alloys used presently in industry rely on the formation of chromium oxide (chromia) as a protective layer between the bulk metal pipe and chemical byproducts. However, chromia can become susceptible to attack from aggressive species such as carbon, water vapor, and sulfur compounds, thus creating a need for a better protection method. A new series of austenitic stainless steels have been developed in recent years that, rather than forming chromia, create a protective layer of aluminum oxide (alumina) under oxidative conditions. These alloys have high nickel content for the stabilization of the austenitic phase, and a more thermodynamically stable oxide layer relative to the traditional chromia formers. Consequently, alumina forming alloys have been proposed as replacements for chromia forming alloys in the petrochemical industry. General oxidation testing has been performed on alumina forming alloys under dry and 10% water vapor conditions. However, oxidation conditions in industry resemble a 100% steam environment. Therefore, test methods to mimic such conditions are needed so that alloys can be tested and developed further for these applications. Four alloys with aluminum contents ranging from 2.6 to 3.9 wt% were cut from centrifugally cast pipes and subjected to oxidation in an environment of pure steam for up to 30 hours, at temperatures of 800 °C and 950 °C. Samples were analyzed using Raman, SEM, and EDS and showed a continuous alumina layer free of cracks. The alumina layer thickness increased with time. Additionally, larger thicknesses were observed in samples oxidized at 950 °C from those of 800 °C. Thickness measurements were used to calculate parabolic and non-parabolic oxidation rate constants. Samples were compared using calculated parabolic and modified parabolic rates of oxidation. Plots for the prediction of oxide layer thickness were generated both for the Wagner model of parabolic oxidation, and an experimentally determined modification to said model. Oxide scale thickness as formed in pure steam was shown to be related to the aluminum content of the alloy and the temperature and time of exposure. Further testing of alumina forming stainless steels in other concentrations of steam would allow for the determination of steam's effect on alumina formation kinetics. In addition, tests at additional temperatures between 800 and 950 °C would allow for the calculation of activation energies and full understanding of the oxide layer. Finally, the analysis of alumina layer thickness effects on coking performance in a petrochemical application would allow for the potential transition of these alloys into the commercial market.

Detail, external parabolic antenna (later addition). Note how waveguide was ...

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

Detail, external parabolic antenna (later addition). Note how waveguide was cut to remove active portion of antenna. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

Reflective Properties of a Parabolic Mirror.

ERIC Educational Resources Information Center

Ramsey, Gordon P.

1991-01-01

An incident light ray parallel to the optical axis of a parabolic mirror will be reflected at the focal point and vice versa. Presents a mathematical proof that uses calculus, algebra, and geometry to prove this reflective property. (MDH)

Solar thermal technology evaluation, fiscal year 1982. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1983-01-01

Three primary solar concepts the central receiver, parabolic dish, and parabolic trough are investigated. To a lesser extent, the hemispherical bowl and salt-gradient solar pond are also being studied. Each technology is described.

FASTRACK (TM): Parabolic and Suborbital Experiment Support Facility

NASA Technical Reports Server (NTRS)

Richards, Stephanie E. (Compiler); Levine, Howard G.; Romero, V.

2016-01-01

FASTRACK was developed by NASA Kennedy Space Center and Space Florida to provide capabilities to conduct frequent, affordable, and responsive flight opportunities for reduced gravity experiments, technology development, and hardware testing on suborbital vehicles and parabolic flights.

D and 18O enrichment measurements in biological fluids in a continuous-flow elemental analyser with an isotope-ratio mass spectrometer using two configurations.

PubMed

Ripoche, N; Ferchaud-Roucher, V; Krempf, M; Ritz, P

2006-09-01

In doubly labelled water studies, biological sample enrichments are mainly measured using off-line techniques (equilibration followed by dual-inlet introduction) or high-temperature elemental analysis (HT-EA), coupled with an isotope-ratio mass spectrometer (IRMS). Here another continuous-flow method, (CF-EA/IRMS), initially dedicated to water, is tested for plasma and urine analyses. The elemental analyser configuration is adapted for each stable isotope: chromium tube for deuterium reduction and glassy carbon reactor for 18O pyrolysis. Before on-line conversion of water into gas, each matrix is submitted to a short and easy treatment, which is the same for the analysis of the two isotopes. Plasma is passed through centrifugal filters. Urine is cleaned with black carbon and filtered (0.45 microm diameter). Tested between 150 and 300 ppm in these fluids, the D/H ratio response is linear with good repeatability (SD<0.2 ppm) and reproducibility (SD<0.5 ppm). For 18O/16O ratios (from 2000 to 2200 ppm), the same repeatability is obtained with a between-day precision lower than 1.4 ppm. The accuracy on biological samples is validated by comparison to classical dual-inlet methods: 18O analyses give more accurate results. The data show that enriched physiological fluids can be successfully analysed in CF-EA/IRMS. Copyright (c) 2006 John Wiley & Sons, Ltd.

Molten salt parabolic trough system with synthetic oil preheating

NASA Astrophysics Data System (ADS)

Yuasa, Minoru; Hino, Koichi

2017-06-01

Molten salt parabolic trough system (MSPT), which can heat the heat transfer fluid (HTF) to 550 °C has a better performance than a synthetic oil parabolic trough system (SOPT), which can heat the HTF to 400 °C or less. The utilization of HTF at higher temperature in the parabolic trough system is able to realize the design of a smaller size of storage tank and higher heat to electricity conversion efficiency. However, with MSPT there is a great amount of heat loss at night so it is necessary to circulate the HTF at a high temperature of about 290 °C in order to prevent solidification. A new MSPT concept with SOPT preheating (MSSOPT) has been developed to reduce the heat loss at night. In this paper, the MSSOPT system, its performance by steady state analysis and annual performance analysis are introduced.

First Middle East Aircraft Parabolic Flights for ISU Participant Experiments

NASA Astrophysics Data System (ADS)

Pletser, Vladimir; Frischauf, Norbert; Cohen, Dan; Foster, Matthew; Spannagel, Ruven; Szeszko, Adam; Laufer, Rene

2017-06-01

Aircraft parabolic flights are widely used throughout the world to create microgravity environment for scientific and technology research, experiment rehearsal for space missions, and for astronaut training before space flights. As part of the Space Studies Program 2016 of the International Space University summer session at the Technion - Israel Institute of Technology, Haifa, Israel, a series of aircraft parabolic flights were organized with a glider in support of departmental activities on `Artificial and Micro-gravity' within the Space Sciences Department. Five flights were organized with manoeuvres including several parabolas with 5 to 6 s of weightlessness, bank turns with acceleration up to 2 g and disorientation inducing manoeuvres. Four demonstration experiments and two experiments proposed by SSP16 participants were performed during the flights by on board operators. This paper reports on the microgravity experiments conducted during these parabolic flights, the first conducted in the Middle East for science and pedagogical experiments.

Lightweight, low-cost solar energy collector

NASA Technical Reports Server (NTRS)

Hochberg, Eric B. (Inventor); Costen, Michael K. (Inventor)

2006-01-01

A lightweight solar concentrator of the reflecting parabolic or trough type is realized via a thin reflecting film, an inflatable structural housing and tensioned fibers. The reflector element itself is a thin, flexible, specularly-reflecting sheet or film. The film is maintained in the parabolic trough shape by means of a plurality of identical tensioned fibers arranged to be parallel to the longitudinal axis of the parabola. Fiber ends are terminated in two identical spaced anchorplates, each containing a plurality of holes which lie on the desired parabolic contour. In a preferred embodiment, these fibers are arrayed in pairs with one fiber contacting the front side of the reflecting film and the other contacting the back side of the reflecting film. The reflective surface is thereby slidably captured between arrays of fibers which control the shape and position of the reflective film. Gas pressure in the inflatable housing generates fiber tension to achieve a truer parabolic shape.

Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Da-Shuai; Wu, Ge; Gao, Bo; Tian, Xiao-Jian

2013-01-01

We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the inter-cavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.

System for the production of plasma

DOEpatents

Bakken, George S.

1978-01-01

The present invention provides a system for the production of a plasma by concentrating and focusing a laser beam on the plasma-forming material with a lightfocusing member which comprises a parabolic axicon in conjunction with a coaxial conical mirror. The apex of the conical mirror faces away from the focus of the parabolic axicon such that the conical mirror serves to produce a virtual line source along the axis of the cone. Consequently, irradiation from a laser parallel to the axis toward the apex of the conical mirror will be concentrated at the focus of the parabolic axicon, impinging upon the plasma-forming material there introduced to produce a plasma. The system is adaptable to irradiation of a target pellet introduced at the focus of the parabolic axicon and offers an advantage in that the target pellet can be irradiated with a high degree of radial and spherical symmetry.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Optimal two-mirror system for laser radiation focusing

NASA Astrophysics Data System (ADS)

Gitin, Andrey V.

2009-10-01

An optical system for laser radiation focusing, which consists of parabolic and elliptic mirrors, is considered. It is shown by the method of elementary reflections that the maximum concentration of laser radiation on the target can be achieved at a certain position of these mirrors.

Identification of HMX1 target genes: A predictive promoter model approach

PubMed Central

Boulling, Arnaud; Wicht, Linda

2013-01-01

Purpose A homozygous mutation in the H6 family homeobox 1 (HMX1) gene is responsible for a new oculoauricular defect leading to eye and auricular developmental abnormalities as well as early retinal degeneration (MIM 612109). However, the HMX1 pathway remains poorly understood, and in the first approach to better understand the pathway’s function, we sought to identify the target genes. Methods We developed a predictive promoter model (PPM) approach using a comparative transcriptomic analysis in the retina at P15 of a mouse model lacking functional Hmx1 (dmbo mouse) and its respective wild-type. This PPM was based on the hypothesis that HMX1 binding site (HMX1-BS) clusters should be more represented in promoters of HMX1 target genes. The most differentially expressed genes in the microarray experiment that contained HMX1-BS clusters were used to generate the PPM, which was then statistically validated. Finally, we developed two genome-wide target prediction methods: one that focused on conserving PPM features in human and mouse and one that was based on the co-occurrence of HMX1-BS pairs fitting the PPM, in human or in mouse, independently. Results The PPM construction revealed that sarcoglycan, gamma (35kDa dystrophin-associated glycoprotein) (Sgcg), teashirt zinc finger homeobox 2 (Tshz2), and solute carrier family 6 (neurotransmitter transporter, glycine) (Slc6a9) genes represented Hmx1 targets in the mouse retina at P15. Moreover, the genome-wide target prediction revealed that mouse genes belonging to the retinal axon guidance pathway were targeted by Hmx1. Expression of these three genes was experimentally validated using a quantitative reverse transcription PCR approach. The inhibitory activity of Hmx1 on Sgcg, as well as protein tyrosine phosphatase, receptor type, O (Ptpro) and Sema3f, two targets identified by the PPM, were validated with luciferase assay. Conclusions Gene expression analysis between wild-type and dmbo mice allowed us to develop a PPM that identified the first target genes of Hmx1. PMID:23946633

Print Still Matters in an E-Learning World, and Training Companies Need to Properly Manage It

ERIC Educational Resources Information Center

Kriesen, Gretchen L.

2011-01-01

This report demonstrates how the application of Behavioral Systems Analysis (BSA) methods assisted in assessing a small training company's Print Production Management (PPM) system. PPM is the process by which printed materials are conceptualized, estimated, released to a commercial printer, proofed, and delivered to the client. The current PPM…

Distinguishing between respiratory syncytial virus subgroups by protein profile analysis.

PubMed Central

Walpita, P; Mufson, M A; Stanek, R J; Pfeifer, D; Connor, J D

1992-01-01

We subgrouped 75 strains of respiratory syncytial virus by a protein profile method (PPM) which relies on different mobilities of the phosphoprotein in one-dimensional polyacrylamide gel electrophoresis and does not require monoclonal antibodies. When compared with enzyme immunoassay, PPM correctly subgrouped 54 of 56 subgroup A and all 19 subgroup B strains. Images PMID:1572961

IR Spectrometer Using 90-degree Off-axis Parabolic Mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert M. Malone, Richard, G. Hacking, Ian J. McKenna, and Daniel H. Dolan

2008-09-02

A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light ource at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output IR recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the secondmore » parabolic mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement singlepoint pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.« less

Chaotic motion of comets in near-parabolic orbit: Mapping aproaches

NASA Astrophysics Data System (ADS)

Liu, Jie; Sun, Yi-Sui

1994-09-01

There exist many comets with near-parabolic orbits in the solar system. Among various theories proposed to explain their origin, the Oort cloud hypothesis seems to be the most reasonable. The theory assumes that there is a cometary cloud at a distance 103 to 107 from the sun and that perturbing forces from planets or stars make orbits of some of these comets become the near-parabolic type. Concerning the evolution of these orbits under planetary perturbations, we can raise the question: Will they stay in the solar system forever or will they escape from it? This is an attractive dynamical problem. If we go ahead by directly solving the dynamical differential equations, we may encounter the difficulty of long-time computation. For the orbits of these comets are near-parabolic and their periods are too long to study on their long-term evolution. With mapping approaches the difficulty will be overcome. In another aspect, the study of this model has special meaning for chaotic dynamics. We know that in the neighborhood of any separatrix i.e. the trajectory with zero frequency of the uperturbed motion of a Hamiltonian system, some chaotic motions have to be expected. Actually, the simplest example of separatrix is the parabolic trajectory of the two-body problem which separates the bounded and unbounded motion. From this point of view, the dynamical study of near-parabolic motion is very important. Petrosky's elegant but more abstract deduction gives a Kepler mapping which describes the dynamics of the cometary motion. In this paper we derive a similar mapping directly and discuss its dynamical characters.

Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: a comparison of three relativistic computational methods.

PubMed

Arcisauskaite, Vaida; Melo, Juan I; Hemmingsen, Lars; Sauer, Stephan P A

2011-07-28

We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL(2) (L = Cl, Br, I, CH(3)) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH(3))(2) within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ∼2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr(2) and HgI(2) when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ∼500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ∼100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible. © 2011 American Institute of Physics

A new method of analysis of peroxydisulfate using ion chromatography and its application to the simultaneous determination of peroxydisulfate and other common inorganic ions in a peroxydisulfate matrix.

PubMed

Khan, Nymul E; Adewuyi, Yusuf G

2011-01-21

A new method for the determination of peroxydisulfate using ion chromatography has been developed. Elution of peroxydisulfate was effected by isocratic elution using 200 mM NaOH at 40°C. A modification of the method using gradient elution was able to simultaneously determine other common inorganic ions (nitrate, nitrite, sulfate and chloride) down to significantly low concentrations in a peroxydisulfate matrix. The relative standard deviations (RSD) were in the range of 0.5-5%, for peak areas and <0.2% for peak retention times. The recoveries were between 95% and 120% for a concentration range of about 0.5-42 ppm. The limit of detection for peroxydisulfate ion was 0.2 ppm and for the other ions were ≤2×10(-2) ppm. The calibration curves were linear with slope and intercepts close to 1 and 0, respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

Inactivation of Bacillus anthracis Spores by a Combination of Biocides and Heating under High-Temperature Short-Time Pasteurization Conditions ▿

PubMed Central

Xu, Sa; Labuza, Theodore P.; Diez-Gonzalez, Francisco

2008-01-01

The milk supply is considered a primary route for a bioterrorism attack with Bacillus anthracis spores because typical high-temperature short-time (HTST) pasteurization conditions cannot inactivate spores. In the event of intentional contamination, an effective method to inactivate the spores in milk under HTST processing conditions is needed. This study was undertaken to identify combinations and concentrations of biocides that can inactivate B. anthracis spores at temperatures in the HTST range in less than 1 min. Hydrogen peroxide (HP), sodium hypochlorite (SH), and peroxyacetic acid (PA) were evaluated for their efficacy in inactivating spores of strains 7702, ANR-1, and 9131 in milk at 72, 80, and 85°C using a sealed capillary tube technique. Strains ANR-1 and 9131 were more resistant to all of the biocide treatments than strain 7702. Addition of 1,260 ppm SH to milk reduced the number of viable spores of each strain by 6 log CFU/ml in less than 90 and 60 s at 72 and 80°C, respectively. After neutralization, 1,260 ppm SH reduced the time necessary to inactivate 6 log CFU/ml (TTI6-log) at 80°C to less than 20 s. Treatment of milk with 7,000 ppm HP resulted in a similar level of inactivation in 60 s. Combined treatment with 1,260 ppm SH and 1,800 ppm HP inactivated spores of all strains in less than 20 s at 80°C. Mixing 15 ppm PA with milk containing 1,260 ppm SH resulted in TTI6-log of 25 and 12 s at 72 and 80°C, respectively. TTI6-log of less than 20 s were also achieved at 80°C by using two combinations of biocides: 250 ppm SH, 700 ppm HP, and 150 ppm PA; and 420 ppm SH (pH 7), 1,100 ppm HP, and 15 ppm PA. These results indicated that different combinations of biocides could consistently result in 6-log reductions in the number of B. anthracis spores in less than 1 min at temperatures in the HTST range. This information could be useful for developing more effective thermal treatment strategies which could be used in HTST milk plants to process contaminated milk for disposal and decontamination, as well as for potential protective measures. PMID:18390680

Inactivation of Bacillus anthracis spores by a combination of biocides and heating under high-temperature short-time pasteurization conditions.

PubMed

Xu, Sa; Labuza, Theodore P; Diez-Gonzalez, Francisco

2008-06-01

The milk supply is considered a primary route for a bioterrorism attack with Bacillus anthracis spores because typical high-temperature short-time (HTST) pasteurization conditions cannot inactivate spores. In the event of intentional contamination, an effective method to inactivate the spores in milk under HTST processing conditions is needed. This study was undertaken to identify combinations and concentrations of biocides that can inactivate B. anthracis spores at temperatures in the HTST range in less than 1 min. Hydrogen peroxide (HP), sodium hypochlorite (SH), and peroxyacetic acid (PA) were evaluated for their efficacy in inactivating spores of strains 7702, ANR-1, and 9131 in milk at 72, 80, and 85 degrees C using a sealed capillary tube technique. Strains ANR-1 and 9131 were more resistant to all of the biocide treatments than strain 7702. Addition of 1,260 ppm SH to milk reduced the number of viable spores of each strain by 6 log CFU/ml in less than 90 and 60 s at 72 and 80 degrees C, respectively. After neutralization, 1,260 ppm SH reduced the time necessary to inactivate 6 log CFU/ml (TTI6-log) at 80 degrees C to less than 20 s. Treatment of milk with 7,000 ppm HP resulted in a similar level of inactivation in 60 s. Combined treatment with 1,260 ppm SH and 1,800 ppm HP inactivated spores of all strains in less than 20 s at 80 degrees C. Mixing 15 ppm PA with milk containing 1,260 ppm SH resulted in TTI6-log of 25 and 12 s at 72 and 80 degrees C, respectively. TTI6-log of less than 20 s were also achieved at 80 degrees C by using two combinations of biocides: 250 ppm SH, 700 ppm HP, and 150 ppm PA; and 420 ppm SH (pH 7), 1,100 ppm HP, and 15 ppm PA. These results indicated that different combinations of biocides could consistently result in 6-log reductions in the number of B. anthracis spores in less than 1 min at temperatures in the HTST range. This information could be useful for developing more effective thermal treatment strategies which could be used in HTST milk plants to process contaminated milk for disposal and decontamination, as well as for potential protective measures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ranieri, M.G.A., E-mail: gabi.ranieri@ig.com.br; Aguiar, E.C.; Cilense, M.

Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12} thick films were obtained by SSR and PPM methods. • Both systems crystallize in an orthorhombic structure. • Textured characteristics were evidenced. • Grain morphology affects the P–E loops. - Abstract: Bismuth titanate powders (Bi{sub 4}Ti{sub 3}O{sub 12}-BIT) were fabricated by solid state reaction (SSR) and polymeric precursor method (PPM). From these powders, Bi{sub 4}Ti{sub 3}O{sub 12} pellets were obtained by tape-casting using plate-like templates particles prepared by a molten salt method. The BIT phase crystallizes in an orthorhombic structure type with space group Fmmm. Agglomeration of the particles, which affects the densification ofmore » the ceramic, electrical conduction and leakage current at high electric fields, was monitored by transmission electronic microscopy (TEM) analyses. FEG-SEM indicated that different shape of grains of BIT ceramics was influenced by the processing route. Both SSR and PPM methods lead to unsaturated P–E loops of BIT ceramics originating from the highly c-axis orientation and high conductivity which was affected by charge carriers flowing normally to the grain boundary of the crystal lattice.« less

Detection of glucose in the human brain with 1 H MRS at 7 Tesla.

PubMed

Kaiser, Lana G; Hirokazu, Kawaguchi; Fukunaga, Masaki; B Matson, Gerald

2016-12-01

A new method is proposed for noninvasive detection of glucose in vivo using proton MR spectroscopy at 7 Tesla. The proposed method utilizes J-difference editing to uncover the resonance of beta-glucose (β-glc) at 3.23 ppm, which is strongly overlapped with choline. Calculations using the density matrix formalism are used to maximize the signal-to-noise ratio of the β-glc resonance at 3.23 ppm. The calculations are verified using phantom and in vivo data collected at 7 Tesla. The proposed method allows observation of the glucose signal at 3.23 ppm in the human brain spectrum. Additional co-edited resonances of N-acetylaspartylglutamatate and glutathione are also detected in the same experiment. The proposed method does not require carbon ( 13 C)- labeled glucose injections and 13 C hardware; as such, it has a potential to provide valuable information on intrinsic glucose concentration in the human brain in vivo. Magn Reson Med 76:1653-1660, 2016. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Building blocks for automated elucidation of metabolites: machine learning methods for NMR prediction.

PubMed

Kuhn, Stefan; Egert, Björn; Neumann, Steffen; Steinbeck, Christoph

2008-09-25

Current efforts in Metabolomics, such as the Human Metabolome Project, collect structures of biological metabolites as well as data for their characterisation, such as spectra for identification of substances and measurements of their concentration. Still, only a fraction of existing metabolites and their spectral fingerprints are known. Computer-Assisted Structure Elucidation (CASE) of biological metabolites will be an important tool to leverage this lack of knowledge. Indispensable for CASE are modules to predict spectra for hypothetical structures. This paper evaluates different statistical and machine learning methods to perform predictions of proton NMR spectra based on data from our open database NMRShiftDB. A mean absolute error of 0.18 ppm was achieved for the prediction of proton NMR shifts ranging from 0 to 11 ppm. Random forest, J48 decision tree and support vector machines achieved similar overall errors. HOSE codes being a notably simple method achieved a comparatively good result of 0.17 ppm mean absolute error. NMR prediction methods applied in the course of this work delivered precise predictions which can serve as a building block for Computer-Assisted Structure Elucidation for biological metabolites.

The French thermo-helio-electricity-KW parabolic dish program

NASA Technical Reports Server (NTRS)

Audibert, M.; Peri, G.

1982-01-01

The testing and development of parabolic dish solar thermal power plants to produce, thermal mechanical, or electrical energy are discussed. The design, construction, and experiments of prototype collectors to prove the feasibility of such collectors is described.

Parabolic tapers for overmoded waveguides

DOEpatents

Doane, J.L.

1983-11-25

A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.

Convergence analysis of a monotonic penalty method for American option pricing

NASA Astrophysics Data System (ADS)

Zhang, Kai; Yang, Xiaoqi; Teo, Kok Lay

2008-12-01

This paper is devoted to study the convergence analysis of a monotonic penalty method for pricing American options. A monotonic penalty method is first proposed to solve the complementarity problem arising from the valuation of American options, which produces a nonlinear degenerated parabolic PDE with Black-Scholes operator. Based on the variational theory, the solvability and convergence properties of this penalty approach are established in a proper infinite dimensional space. Moreover, the convergence rate of the combination of two power penalty functions is obtained.

Parameter estimation problems for distributed systems using a multigrid method

NASA Technical Reports Server (NTRS)

Ta'asan, Shlomo; Dutt, Pravir

1990-01-01

The problem of estimating spatially varying coefficients of partial differential equations is considered from observation of the solution and of the right hand side of the equation. It is assumed that the observations are distributed in the domain and that enough observations are given. A method of discretization and an efficient multigrid method for solving the resulting discrete systems are described. Numerical results are presented for estimation of coefficients in an elliptic and a parabolic partial differential equation.

[Bloodstain pattern analysis on examples from practice: Are calculations with application parabolic trajectory usable?].

PubMed

Makovický, Peter; Matlach, Radek; Pokorná, Olga; Mošna, František; Makovický, Pavol

2015-01-01

The bloodstain pattern analysis (BPA) is useful in the forensic medicine. In Czechoslovakian criminology is this method not commonly used. The objective of this work is to calculate the impact length, height and distance splashing of blood drops. The results are compared with the real values for specific cases. It is also compared to calculate the angle of incidence of blood drops, using sinα with a form using tgα. For this purposes we used two different character cases from practice with well-preserved condition and readable blood stains. Selected blood stains were documented in order to calculate the angle of incidence of blood drops and to calculateorigin splashes. For this drop of blood, the distance of impact of the drops of blood (x), the height of the sprayed blood drops (y) and the length of the flight path the drop of blood (l). The obtained data was retrospectively analysed for the two models. The first straight line is represented by the triangle (M1) and the other is the parabolic model (M2). The formulae were derived using the Euler substitution. The results show that the angle of incidence of the drop of blood can be calculated as sinα and the tgα. When applying, the triangle is appropriate to consider the application and sinα parabolic requires the calculation of the angle of incidence drops of blood tgα. Parabola is useful for the BPA. In Czechoslovakian should be providing workplace training seminars BPA primarily intended for forensic investigators.We recommend the use of this method during investigations, verification of acts in forensic practice.

Scalable algorithms for 3D extended MHD.

NASA Astrophysics Data System (ADS)

Chacon, Luis

2007-11-01

In the modeling of plasmas with extended MHD (XMHD), the challenge is to resolve long time scales while rendering the whole simulation manageable. In XMHD, this is particularly difficult because fast (dispersive) waves are supported, resulting in a very stiff set of PDEs. In explicit schemes, such stiffness results in stringent numerical stability time-step constraints, rendering them inefficient and algorithmically unscalable. In implicit schemes, it yields very ill-conditioned algebraic systems, which are difficult to invert. In this talk, we present recent theoretical and computational progress that demonstrate a scalable 3D XMHD solver (i.e., CPU ˜N, with N the number of degrees of freedom). The approach is based on Newton-Krylov methods, which are preconditioned for efficiency. The preconditioning stage admits suitable approximations without compromising the quality of the overall solution. In this work, we employ optimal (CPU ˜N) multilevel methods on a parabolized XMHD formulation, which renders the whole algorithm scalable. The (crucial) parabolization step is required to render XMHD multilevel-friendly. Algebraically, the parabolization step can be interpreted as a Schur factorization of the Jacobian matrix, thereby providing a solid foundation for the current (and future extensions of the) approach. We will build towards 3D extended MHDootnotetextL. Chac'on, Comput. Phys. Comm., 163 (3), 143-171 (2004)^,ootnotetextL. Chac'on et al., 33rd EPS Conf. Plasma Physics, Rome, Italy, 2006 by discussing earlier algorithmic breakthroughs in 2D reduced MHDootnotetextL. Chac'on et al., J. Comput. Phys. 178 (1), 15- 36 (2002) and 2D Hall MHD.ootnotetextL. Chac'on et al., J. Comput. Phys., 188 (2), 573-592 (2003)

Altered Actin Dynamics and Functions of Osteoblast-Like Cells in Parabolic Flight may Involve ERK1/2

NASA Astrophysics Data System (ADS)

Dai, Zhongquan; Tan, Yingjun; Yang, Fen; Qu, Lina; Zhang, Hongyu; Wan, Yumin; Li, Yinghui

2011-01-01

Osteoblasts are sensitive to mechanical stressors such as gravity and alter their cytoskeletons and functions to adapt; however, the contribution of gravity to this phenomenon is not well understood. In this study, we investigated the effects of acute gravitational changes on the structure and function of osteoblast ROS17/2.8 as generated by parabolic flight. The changes in microfilament cytoskeleton was observed by immunofluorescence stain of Texas red conjugated Phalloidin and Alexa Fluor 488 conjugated DNase I for F-actin and G-actin, respectively. To examine osteoblast function, ALP (alkaline phosphatase) activity, osteocalcin secretions and the expression of ALP, COL1A1 (collagen type I alpha 1 chain) and osteocalcin were detected by modified Gomori methods, radioimmunity and RT-PCR, respectively. Double fluorescence staining of phosphorylated p44/42 and F-actin were performed to observe their colocalization relationship. The established semi-quantitative analysis method of fluorescence intensity of EGFP was used to detect the activity changes of COL1A1 promoter in EGFP-ROS cells with MAPK inhibitor PD98059 or F-actin inhibitor cytochalasin B. Results indicate that the altered gravity induced the reorganization of microfilament cytoskeletons of osteoblasts. After 3 h parabolic flight, F-actin of osteoblast cytoskeleton became thicker and directivity, whereas G-actin shrunk and became more concentrated at the edge of nucleus. The excretion of osteocalcin, the activity of ALP and the expression of mRNA decreased. Colocalization analysis indicated that phosphorylated p44/42 MAPK was coupled with F-actin. Inhibitor PD98059 and cytochalasin B decreased the fluorescence intensity of EGFP-ROS cells. Above results suggest that short time gravity variations induce the adjustment of osteoblast structure and functional and ERK1/2 signaling maybe involve these responses. We believe that it is an adaptive method of the osteoblasts to gravity alteration that structure alteration inhibits the function performing.

Seaweed-synthesized silver nanoparticles: an eco-friendly tool in the fight against Plasmodium falciparum and its vector Anopheles stephensi?

PubMed

Murugan, Kadarkarai; Samidoss, Christina Mary; Panneerselvam, Chellasamy; Higuchi, Akon; Roni, Mathath; Suresh, Udaiyan; Chandramohan, Balamurugan; Subramaniam, Jayapal; Madhiyazhagan, Pari; Dinesh, Devakumar; Rajaganesh, Rajapandian; Alarfaj, Abdullah A; Nicoletti, Marcello; Kumar, Suresh; Wei, Hui; Canale, Angelo; Mehlhorn, Heinz; Benelli, Giovanni

2015-11-01

Malaria, the most widespread mosquito-borne disease, affects 350-500 million people each year. Eco-friendly control tools against malaria vectors are urgently needed. This research proposed a novel method of plant-mediated synthesis of silver nanoparticles (AgNP) using a cheap seaweed extract of Ulva lactuca, acting as a reducing and capping agent. AgNP were characterized by UV-vis spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The U. lactuca extract and the green-synthesized AgNP were tested against larvae and pupae of the malaria vector Anopheles stephensi. In mosquitocidal assays, LC50 values of U. lactuca extract against A. stephensi larvae and pupae were 18.365 ppm (I instar), 23.948 ppm (II), 29.701 ppm (III), 37.517 ppm (IV), and 43.012 ppm (pupae). LC50 values of AgNP against A. stephensi were 2.111 ppm (I), 3.090 ppm (II), 4.629 ppm (III), 5.261 ppm (IV), and 6.860 ppm (pupae). Smoke toxicity experiments conducted against mosquito adults showed that U. lactuca coils evoked mortality rates comparable to the permethrin-based positive control (66, 51, and 41%, respectively). Furthermore, the antiplasmodial activity of U. lactuca extract and U. lactuca-synthesized AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. Fifty percent inhibitory concentration (IC50) values of U. lactuca were 57.26 μg/ml (CQ-s) and 66.36 μg/ml (CQ-r); U. lactuca-synthesized AgNP IC50 values were 76.33 μg/ml (CQ-s) and 79.13 μg/ml (CQ-r). Overall, our results highlighted out that U. lactuca-synthesized AgNP may be employed to develop newer and safer agents for malaria control.

Nonuniform depth grids in parabolic equation solutions.

PubMed

Sanders, William M; Collins, Michael D

2013-04-01

The parabolic wave equation is solved using a finite-difference solution in depth that involves a nonuniform grid. The depth operator is discretized using Galerkin's method with asymmetric hat functions. Examples are presented to illustrate that this approach can be used to improve efficiency for problems in ocean acoustics and seismo-acoustics. For shallow water problems, accuracy is sensitive to the precise placement of the ocean bottom interface. This issue is often addressed with the inefficient approach of using a fine grid spacing over all depth. Efficiency may be improved by using a relatively coarse grid with nonuniform sampling to precisely position the interface. Efficiency may also be improved by reducing the sampling in the sediment and in an absorbing layer that is used to truncate the computational domain. Nonuniform sampling may also be used to improve the implementation of a single-scattering approximation for sloping fluid-solid interfaces.

Perception of time in microgravity and hypergravity during parabolic flight.

PubMed

Clément, Gilles

2018-03-07

We explored the effect of gravity on the accuracy for estimating durations of 3.5, 7, and 14 s. Experiments were performed on board an Airbus A310 during parabolic flights eliciting repeated exposures to short periods of 0, 1, and 1.8 g. Two methods for obtaining duration estimates were used, reproduction and production of duration, in two conditions: a control counting condition and a concurrent reading condition. Simple reaction times were also measured to assess attention. The results showed that the temporal accuracies during the reproduction task in the concurrent reading condition were significantly underestimated in 0 g compared with 1 g. Reaction times were also longer in 0 g. However, there was no difference in duration estimates in the production tasks. These results suggest that the temporal underestimation in 0 g is caused by decreased selective attention and impaired retrieval of information in episodic memory.

Focusing short-wavelength surface plasmons by a plasmonic mirror.

PubMed

Ogut, Erdem; Yanik, Cenk; Kaya, Ismet Inonu; Ow-Yang, Cleva; Sendur, Kursat

2018-05-01

Emerging applications in nanotechnology, such as superresolution imaging, ultra-sensitive biomedical detection, and heat-assisted magnetic recording, require plasmonic devices that can generate intense optical spots beyond the diffraction limit. One of the important drawbacks of surface plasmon focusing structures is their complex design, which is significant for ease of integration with other nanostructures and fabrication at low cost. In this study, a planar plasmonic mirror without any nanoscale features is investigated that can focus surface plasmons to produce intense optical spots having lateral and vertical dimensions of λ/9.7 and λ/80, respectively. Intense optical spots beyond the diffraction limit were produced from the plasmonic parabolic mirror by exciting short-wavelength surface plasmons. The refractive index and numerical aperture of the plasmonic parabolic mirror were varied to excite short-wavelength surface plasmons. Finite-element method simulations of the plasmonic mirror and scanning near-field optical microscopy experiments have shown very good agreement.

Binding of alpha-fetoprotein by immobilized monoclonal antibodies during episodes of zero-gravity obtained by parabolic flight

NASA Technical Reports Server (NTRS)

Spooner, Brian S.; Guikema, James A.; Barnes, Grady

1990-01-01

Alpha-fetoprotein (AFP), a single-chain polypeptide which is synthesized by the liver and yolk sac of the human fetus, provided a model ligand for assessing the effects of microgravity on ligand binding to surface-immobilized model receptor molecules. Monoclonal antibodies, used as receptors for AFP, were immobilized by covalent attachment to latex microparticles. Zero gravity environment was obtained by parabolic flight aboard NASA 930, a modified KC-135 aircraft. Buring the onset of an episode of zero gravity, ligand and receptor were mixed. Timed incubation (20 s) was terminated by centrifugation, the supernatant removed, and microparticies were assessed for bound AFP by immunochemical methods. The extent of binding was not influenced by microgravity, when compared with 1-G controls, which suggests that aberrant cellular activities observed in microgravity are not the simple expression of altered macromolecular interactions.

Spatial optimal disturbances in swept-wing boundary layers

NASA Astrophysics Data System (ADS)

Chen, Cheng

2018-04-01

With the use of the adjoint-based optimization method proposed by Tempelmann et al. (J. Fluid Mech., vol. 704, 2012, pp. 251-279), in which the parabolized stability equation (PSE) and so-called adjoint parabolized stability equation (APSE) are solved iteratively, we obtain the spatial optimal disturbance shape and investigate its dependence on the parameters of disturbance wave and wall condition, such as radial frequency ω and wall temperature Twall, in a swept-wing boundary layer flow. Further, the non-modal growth mechanism of this optimal disturbance has been also discussed, regarding its spatial evolution way in the streamwise direction. The results imply that the spanwise wavenumber, disturbance frequency and wall cooling do not change the physical mechanism of perturbation growth, just with a substantial effect on the magnitude of perturbation growth. Further, wall cooling may have enhancing or suppressing effect on spatial optimal disturbance growth, depending on the streamwise location.

Existence of evolutionary variational solutions via the calculus of variations

NASA Astrophysics Data System (ADS)

Bögelein, Verena; Duzaar, Frank; Marcellini, Paolo

In this paper we introduce a purely variational approach to time dependent problems, yielding the existence of global parabolic minimizers, that is ∫0T ∫Ω [uṡ∂tφ+f(x,Du)] dx dt⩽∫0T ∫Ω f(x,Du+Dφ) dx dt, whenever T>0 and φ∈C0∞(Ω×(0,T),RN). For the integrand f:Ω×R→[0,∞] we merely assume convexity with respect to the gradient variable and coercivity. These evolutionary variational solutions are obtained as limits of maps depending on space and time minimizing certain convex variational functionals. In the simplest situation, with some growth conditions on f, the method provides the existence of global weak solutions to Cauchy-Dirichlet problems of parabolic systems of the type ∂tu-divDξf(x,Du)=0 in Ω×(0,∞).

Marching iterative methods for the parabolized and thin layer Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Israeli, M.

1985-01-01

Downstream marching iterative schemes for the solution of the Parabolized or Thin Layer (PNS or TL) Navier-Stokes equations are described. Modifications of the primitive equation global relaxation sweep procedure result in efficient second-order marching schemes. These schemes take full account of the reduced order of the approximate equations as they behave like the SLOR for a single elliptic equation. The improved smoothing properties permit the introduction of Multi-Grid acceleration. The proposed algorithm is essentially Reynolds number independent and therefore can be applied to the solution of the subsonic Euler equations. The convergence rates are similar to those obtained by the Multi-Grid solution of a single elliptic equation; the storage is also comparable as only the pressure has to be stored on all levels. Extensions to three-dimensional and compressible subsonic flows are discussed. Numerical results are presented.

Shaping of parabolic cylindrical membrane reflectors for the DART precision test bed

NASA Technical Reports Server (NTRS)

White, C.; Salama, M.; Dragovan, M.; Schroeder, J.; Barber, D.; Dooley, J.

2003-01-01

The DART is a new telescope architecture consisting of two cylindrical parabolic reflectors. The system is ideally suited to using tensioned membranes for the reflective surfaces, owing to the zero Gaussian curvature of a cylindrical parabola.

A Semi-linear Backward Parabolic Cauchy Problem with Unbounded Coefficients of Hamilton–Jacobi–Bellman Type and Applications to Optimal Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Addona, Davide, E-mail: d.addona@campus.unimib.it

2015-08-15

We obtain weighted uniform estimates for the gradient of the solutions to a class of linear parabolic Cauchy problems with unbounded coefficients. Such estimates are then used to prove existence and uniqueness of the mild solution to a semi-linear backward parabolic Cauchy problem, where the differential equation is the Hamilton–Jacobi–Bellman equation of a suitable optimal control problem. Via backward stochastic differential equations, we show that the mild solution is indeed the value function of the controlled equation and that the feedback law is verified.

High resolution imaging and lithography with hard x rays using parabolic compound refractive lenses

NASA Astrophysics Data System (ADS)

Schroer, C. G.; Benner, B.; Günzler, T. F.; Kuhlmann, M.; Zimprich, C.; Lengeler, B.; Rau, C.; Weitkamp, T.; Snigirev, A.; Snigireva, I.; Appenzeller, J.

2002-03-01

Parabolic compound refractive lenses are high quality optical components for hard x rays. They are particularly suited for full field imaging, with applications in microscopy and x-ray lithography. Taking advantage of the large penetration depth of hard x rays, the interior of opaque samples can be imaged with submicrometer resolution. To obtain the three-dimensional structure of a sample, microscopy is combined with tomographic techniques. In a first hard x-ray lithography experiment, parabolic compound refractive lenses have been used to project the reduced image of a lithography mask onto a resist. Future developments are discussed.

Mechanisms of Corrosion of Copper-Nickel Alloys in Sulfide-Polluted Seawater

DTIC Science & Technology

1981-02-01

anaerobic bacteria, which convert the natural sulfate content of the seawater into sulfides. Also, the putrefaction of organic compounds containing...corrosion rate bozause the Cu2 0 growth3 292 probably follows a parabolic rate law. The corrosion behavior at high oxygen concentrations (> 7.0 g/m ) is...determined using the rotating ring disk electrode method or SRI’s recently developed rotating cylinder- collector electrode.3 In these methods, the

The dynamics of parabolic flight: flight characteristics and passenger percepts

PubMed Central

Karmali, Faisal; Shelhamer, Mark

2008-01-01

Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 seconds of freefall (0 g) followed by 40 seconds of enhanced force (1.8 g), repeated 30–60 times. Although passengers perceive gravity to be zero, in actuality acceleration, and not gravity, has changed, and thus we caution against the terms "microgravity" and "zero gravity. " Despite the aircraft trajectory including large (45°) pitch-up and pitch-down attitudes, the occupants experience a net force perpendicular to the floor of the aircraft. This is because the aircraft generates appropriate lift and thrust to produce the desired vertical and longitudinal accelerations, respectively, although we measured moderate (0.2 g) aft-ward accelerations during certain parts of these trajectories. Aircraft pitch rotation (average 3°/s) is barely detectable by the vestibular system, but could influence some physics experiments. Investigators should consider such details in the planning, analysis, and interpretation of parabolic-flight experiments. PMID:19727328

Orthostatic intolerance and motion sickness after parabolic flight

NASA Technical Reports Server (NTRS)

Schlegel, T. T.; Brown, T. E.; Wood, S. J.; Benavides, E. W.; Bondar, R. L.; Stein, F.; Moradshahi, P.; Harm, D. L.; Fritsch-Yelle, J. M.; Low, P. A.

2001-01-01

Because it is not clear that the induction of orthostatic intolerance in returning astronauts always requires prolonged exposure to microgravity, we investigated orthostatic tolerance and autonomic cardiovascular function in 16 healthy subjects before and after the brief micro- and hypergravity of parabolic flight. Concomitantly, we investigated the effect of parabolic flight-induced vomiting on orthostatic tolerance, R-wave-R-wave interval and arterial pressure power spectra, and carotid-cardiac baroreflex and Valsalva responses. After parabolic flight 1) 8 of 16 subjects could not tolerate 30 min of upright tilt (compared to 2 of 16 before flight); 2) 6 of 16 subjects vomited; 3) new intolerance to upright tilt was associated with exaggerated falls in total peripheral resistance, whereas vomiting was associated with increased R-wave-R-wave interval variability and carotid-cardiac baroreflex responsiveness; and 4) the proximate mode of new orthostatic failure differed in subjects who did and did not vomit, with vomiters experiencing comparatively isolated upright hypocapnia and cerebral vasoconstriction and nonvomiters experiencing signs and symptoms reminiscent of the clinical postural tachycardia syndrome. Results suggest, first, that syndromes of orthostatic intolerance resembling those developing after space flight can develop after a brief (i.e., 2-h) parabolic flight and, second, that recent vomiting can influence the results of tests of autonomic cardiovascular function commonly utilized in returning astronauts.

Simultaneous determination of zinc and chromate in cooling water by differential pulse polarography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jindal, V.K.; Kham, M.A.; Bhatnagar, R.M.

1985-01-01

The use of differential pulse polarography (DPP) for the simultaneous determination of zinc and chromate in cooling water is reported where zinc (5 ppm), chromate (20 ppm), and polyphosphate (50 ppm) formulation is used as a corrosion inhibitor. This will help in effective control of cooling tower performance. The DPP method has been applied for the simultaneous determination of zinc and chromate ions in process and cooling water samples from fertilizer plants in India. The method is based on the reduction of Cr and Zn on SMDE in 1 M NH3-0.1 M NH/sub 4/Cl and 0.005% gelatine supporting electrolyte. Duemore » to interference it is essential to complex calcium ions by adding polyphosphate and to destroy NO/sub 2//sup -//NO/sub 3//sup -/ by adding sulfamic acid along with hydrochloric acid before the actual recording of DP polarograms. The present DP polarographic method for the simultaneous determination of zinc and chromate is comparable in its utility and applicability with spectrophotometric methods. The method has a better accuracy and higher sensitivity and is quick, as both of the ions can be determined in a single scan. 10 references, 4 figures, 5 tables.« less

Application of a multi-level grid method to transonic flow calculations

NASA Technical Reports Server (NTRS)

South, J. C., Jr.; Brandt, A.

1976-01-01

A multi-level grid method was studied as a possible means of accelerating convergence in relaxation calculations for transonic flows. The method employs a hierarchy of grids, ranging from very coarse to fine. The coarser grids are used to diminish the magnitude of the smooth part of the residuals. The method was applied to the solution of the transonic small disturbance equation for the velocity potential in conservation form. Nonlifting transonic flow past a parabolic arc airfoil is studied with meshes of both constant and variable step size.

Comparative evaluation of two quantitative test methods for determining the efficacy of liquid sporicides and sterilants on a hard surface: a precollaborative study.

PubMed

Tomasino, Stephen F; Hamilton, Martin A

2007-01-01

Two quantitative carrier-based test methods for determining the efficacy of liquid sporicides and sterilants on a hard surface, the Standard Quantitative Carrier Test Method-ASTM E 2111-00 and an adaptation of a quantitative micro-method as reported by Sagripanti and Bonifacino, were compared in this study. The methods were selected based on their desirable characteristics (e.g., well-developed protocol, previous use with spores, fully quantitative, and use of readily available equipment) for testing liquid sporicides and sterilants on a hard surface. In this paper, the Sagripanti-Bonifacino procedure is referred to as the Three Step Method (TSM). AOAC Official Method 966.04 was included in this study as a reference method. Three laboratories participated in the evaluation. Three chemical treatments were tested: (1) 3000 ppm sodium hypochlorite with pH adjusted to 7.0, (2) a hydrogen peroxide/peroxyacetic acid product, and (3) 3000 ppm sodium hypochlorite with pH unadjusted (pH of approximately 10.0). A fourth treatment, 6000 ppm sodium hypochlorite solution with pH adjusted to 7.0, was included only for Method 966.04 as a positive control (high level of efficacy). The contact time was 10 min for all chemical treatments except the 6000 ppm sodium hypochlorite treatment which was tested at 30 min. Each chemical treatment was tested 3 times using each of the methods. Only 2 of the laboratories performed the AOAC method. Method performance was assessed by the within-laboratory variance, between-laboratory variance, and total variance associated with the log reduction (LR) estimates generated by each quantitative method. The quantitative methods performed similarly, and the LR values generated by each method were not statistically different for the 3 treatments evaluated. Based on feedback from the participating laboratories, compared to the TSM, ASTM E 2111-00 was more resource demanding and required more set-up time. The logistical and resource concerns identified for ASTM E 2111-00 were largely associated with the filtration process and counting bacterial colonies on filters. Thus, the TSM was determined to be the most suitable method.

77 FR 50661 - Notice of Filing of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-22

... treatment and meaningful involvement of any group, including minority and/or low-income populations, in the... potential environmental justice issues, the Agency seeks information on any groups or segments of the..., cucurbit group 9 at 0.4 ppm; and vegetable, fruiting group 8-10 at 1.3 ppm. An enforcement method for plant...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitcher, C.E.; Zimmerman, D.C.; Tonn, E.M.

Methods were developed for controlling the dental team's occupational exposure to nitrous oxide. The most applicable and effective use of these methods included the use of properly maintained gas delivery equipment, a double-walled scavenging nosepiece and vented suction machine, and minimizing speech by the patient. These methods were evaluated by measuring concentrations of nitrous oxide present in the air inspired by dental personnel. Before their use, the dentist inhaled 900 ppM nitrous oxide; their application reduced his inhaled concentration to 31 ppM, representing a 97% reduction. These methods were well accepted during 157 procedures completed by a group of eightmore » dentists engaged in private practice (four general practitioners, two pedodontists, and two oral surgeons).« less

Toxicity tests, antioxidant activity, and antimicrobial activity of chitosan

NASA Astrophysics Data System (ADS)

Kurniasih, M.; Purwati; Dewi, R. S.

2018-04-01

Chitosan is a naturally occurring cationic biopolymer, obtained by alkaline deacetylation of chitin. This research aims to investigate the toxicity, antioxidant activity and antibacterial activity of chitosan from shrimp chitin. In this study, chitin extracted from shrimp waste material. Chitin is then deacetylation with 60% NaOH so that chitosan produced. Degrees of deacetylation, molecular weight, toxicity test, antioxidant activity and antimicrobial activity of chitosan then evaluated. Toxicity test using Brine Shrimp Lethality Test. The antioxidant analysis was performed using DPPH method (2, 2-diphenyl-1-picrylhydrazyl) and FTC method (ferric thiocyanate) in which the radical formed will reduce Ferro to Ferri resulting in a complex with thiocyanate. To determine the antibacterial activity of Staphylococcus aureus, antifungal in Candida albicans and Aspergillus niger by measuring antimicrobial effects and minimum inhibitory concentrations (MIC). Based on the result of research, the value of degrees of deacetylation, molecular weight, and LC50 values of chitosan synthesis was 94,32, 1052.93 g/mol and 1364.41 ppm, respectively. In general, the antioxidative activities increased as the concentration of chitosan increased. MIC value of chitosan against S. aureus, C. albicans, and A. niger was 10 ppm, 15.6 ppm, and 5 ppm, respectively.

Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method

PubMed Central

Xue, Chao; Quan, Li-Di; Yang, Shan-Qing; Wang, Bing-Peng; Wu, Jun-Fei; Shao, Cheng-Gang; Tu, Liang-Cheng; Milyukov, Vadim; Luo, Jun

2014-01-01

This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al. The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4 ppm to the value of G. The relative uncertainty of the angular acceleration of the turntable is approximately 100 ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10 ppm, and a reliable value of G with 20 ppm or below will be obtained in the near future. PMID:25201996

Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method.

PubMed

Xue, Chao; Quan, Li-Di; Yang, Shan-Qing; Wang, Bing-Peng; Wu, Jun-Fei; Shao, Cheng-Gang; Tu, Liang-Cheng; Milyukov, Vadim; Luo, Jun

2014-10-13

This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al. The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4 ppm to the value of G. The relative uncertainty of the angular acceleration of the turntable is approximately 100 ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10 ppm, and a reliable value of G with 20 ppm or below will be obtained in the near future. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Larvicidal Activity of Citrus Limonoids against Aedes albopictus Larvae

PubMed Central

Bilal, Hazrat; Akram, Waseem; Ali-Hassan, Soaib

2012-01-01

Background: Development of insecticide resistance occurred due to the continuous and misuse of synthetic insecticides therefore, the recent study was conducted to explore eco-friendly plant extracts that have some potential to suppress mosquito larval population. Methods: WHO recommended mosquito larval bioassay method for insecticide was used while for the analysis of citrus oils for limonin and nomilin content HPLC was used. Results: Among the two citrus cultivars tested as larvicide against Aedes albopictus, valencia late (Citrus sinensis) was the best in terms of LC50 (297 ppm), % mortality (97%) and LT50 (18.49 hours) then freutrall early (Citrus reticulate) with LC50 (377.4 ppm), % mortality (88%) and LT50 (31 hours), While nomilin gave lowest LC50 (121.04 ppm) than limonin (382.22 ppm) after 72 hours of exposure. Valencia late also had more limonin and nomilin (377 μg/ml and 21.19 μg/ml) than freutrall early (5.29 μg/ml and 3.89 μg/ml) respectively. Conclusion: Valencia late showed best results in term of LC50, LT50 and percentage mortality against Aedes albopictus as it has more amount of nomilin then freutrall early, however further evaluation in the field conditions is required. PMID:23378967

Stability Test and Quantitative and Qualitative Analyses of the Amino Acids in Pharmacopuncture Extracted from Scolopendra subspinipes mutilans

PubMed Central

Cho, GyeYoon; Han, KyuChul; Yoon, JinYoung

2015-01-01

Objectives: Scolopendra subspinipes mutilans (S. subspinipes mutilans) is known as a traditional medicine and includes various amino acids, peptides and proteins. The amino acids in the pharmacopuncture extracted from S. subspinipes mutilans by using derivatization methods were analyzed quantitatively and qualitatively by using high performance liquid chromatography (HPLC) over a 12 month period to confirm its stability. Methods: Amino acids of pharmacopuncture extracted from S. subspinipes mutilans were derived by using O-phthaldialdehyde (OPA) & 9-fluorenyl methoxy carbonyl chloride (FMOC) reagent and were analyzed using HPLC. The amino acids were detected by using a diode array detector (DAD) and a fluorescence detector (FLD) to compare a mixed amino acid standard (STD) to the pharmacopuncture from centipedes. The stability tests on the pharmacopuncture from centipedes were done using HPLC for three conditions: a room temperature test chamber, an acceleration test chamber, and a cold test chamber. Results: The pharmacopuncture from centipedes was prepared by using the method of the Korean Pharmacopuncture Institute (KPI) and through quantitative analyses was shown to contain 9 amino acids of the 16 amino acids in the mixed amino acid STD. The amounts of the amino acids in the pharmacopuncture from centipedes were 34.37 ppm of aspartate, 123.72 ppm of arginine, 170.63 ppm of alanine, 59.55 ppm of leucine and 57 ppm of lysine. The relative standard deviation (RSD %) results for the pharmacopuncture from centipedes had a maximum value of 14.95% and minimum value of 1.795% on the room temperature test chamber, the acceleration test chamber and the cold test chamber stability tests. Conclusion: Stability tests on and quantitative and qualitative analyses of the amino acids in the pharmacopuncture extracted from centipedes by using derivatization methods were performed by using HPLC. Through research, we hope to determine the relationship between time and the concentrations of the amino acids in the pharmacopuncture extracted from centipedes. PMID:25830058

Permeation-solid adsorbent sampling and GC analysis of formaldehyde.

PubMed

Muntuta-Kinyanta, C; Hardy, J K

1991-12-01

A passive method with membrane permeation sampling for the determination of time-weighted-average (TWA) concentration of formaldehyde in air is described. The sampling device was constructed by affixing an unbacked dimethyl silicone membrane to the base of a glass tube and by sealing the top with a rubber stopper. Formaldehyde permeates the membrane and reacts with 2-(hydroxymethyl)piperidine (2-HMP) coated on the surface of XAD-2. Sampling times from 15 min to 8 hr have been used. The formaldehyde-oxazolidine produced is thermally desorbed and determined by a packed column gas chromatograph equipped with a flame ionization detector (FID). The response of the monitor is directly proportional to the external concentration of formaldehyde over the concentration range 0.050-100 ppm. The permeation constant (the slope of the permeation curve) of the membrane is 0.333 mug ppm(-1). hr, and the detection limit of the method is 0.03 ppm for an 8-hr sampling period. Relative humidity (RH) (35-94%), temperature (0-82 degrees ) and storage period (0-25 days) do not affect the permeation process for sample collection. Moreover, potential chemical interferences, 10 ppm acetone or acrolein, respectively, have no detectable effect on the process. The method gives TWA concentration directly from the measurements, and the equipment is economical and convenient for personal or multi-location sample collections.

A method for collecting eggs of Pseudocapillaria tomentosa (Nematoda: Capillariidae) from zebrafish Danio rerio and efficacy of heat and chlorine for killing the nematode’s eggs

PubMed Central

Martins, ML; Watral, V; Rodrigues-Soares, JP; Kent, ML

2016-01-01

Pseudocapillaria tomentosa is a common pathogen of zebrafish (Danio rerio) in research facilities. We developed a method to collect and concentrate the nematode eggs using a modified sugar centrifugation method, and documented their normal development. Embryonating stages with blastomere formation followed by elongation of the embryo prior to larva formation cumulated in developed larvae inside the eggs and hatching after 5–10 d. We then evaluated the efficacy of heat and chlorine to kill them based on a larva development assay. Eggs were exposed to 40, 50, 60°C for 30 min and 1 h. Chlorine treatment was performed at 100, 250, 500, 1000, 3000 and 6000 ppm for 10 min. Samples exposed to 40°C for 30 min or 1 h showed incidences of larvated eggs similar to controls. In contrast, no larvation occurred with eggs exposed to either 50 or 60°C for 30 min or 1 h. Remarkably, in repeated assays, samples exposed to low doses of chlorine (100, 250, 500 and 1000 ppm for 10 min) showed significantly higher incidence of larvation than controls. Eggs treated with 3,000 ppm for 10 min did not develop larvae and no eggs were found after 6,000 ppm treatment. PMID:27334246

A Priori Method of Using Photon Activation Analysis to Determine Unknown Trace Element Concentrations in NIST Standards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Jaromy; Sun Zaijing; Wells, Doug

2009-03-10

Photon activation analysis detected elements in two NIST standards that did not have reported concentration values. A method is currently being developed to infer these concentrations by using scaling parameters and the appropriate known quantities within the NIST standard itself. Scaling parameters include: threshold, peak and endpoint energies; photo-nuclear cross sections for specific isotopes; Bremstrahlung spectrum; target thickness; and photon flux. Photo-nuclear cross sections and energies from the unknown elements must also be known. With these quantities, the same integral was performed for both the known and unknown elements resulting in an inference of the concentration of the un-reported elementmore » based on the reported value. Since Rb and Mn were elements that were reported in the standards, and because they had well-identified peaks, they were used as the standards of inference to determine concentrations of the unreported elements of As, I, Nb, Y, and Zr. This method was tested by choosing other known elements within the standards and inferring a value based on the stated procedure. The reported value of Mn in the first NIST standard was 403{+-}15 ppm and the reported value of Ca in the second NIST standard was 87000 ppm (no reported uncertainty). The inferred concentrations were 370{+-}23 ppm and 80200{+-}8700 ppm respectively.« less

American lookback option with fixed strike price—2-D parabolic variational inequality

NASA Astrophysics Data System (ADS)

Chen, Xiaoshan; Yi, Fahuai; Wang, Lihe

In this paper we study a 2-dimensional parabolic variational inequality with financial background. We define a suitable weak formula and obtain existence and uniqueness of the problem. Moreover we analyze the behaviors of the free boundary surface.

An Examination of the Feasibility of Ultrasonic Communications Links

DTIC Science & Technology

2010-06-01

14 Figure 6. Building 19472 compound on WSMR, NM, and its environs...21 Figure 11. Parabolic dish (narrow beam...21 Figure 12. Parabolic dish antenna pattern. Sonic intensities at 5-, 10-, and 20-kHz frequencies (green, blue, and red lines

Three-gas detection system with IR optical sensor based on NDIR technology

NASA Astrophysics Data System (ADS)

Tan, Qiulin; Tang, Licheng; Yang, Mingliang; Xue, Chenyang; Zhang, Wendong; Liu, Jun; Xiong, Jijun

2015-11-01

In this paper, a three-gas detection system with a environmental parameter compensation method is proposed based on Non-dispersive infra-red (NDIR) technique, which can be applied to detect multi-gas (methane, carbon dioxide and carbon monoxide). In this system, an IR source and four single-channel pyroelectric sensors are integrated in the miniature optical gas chamber successfully. Inner wall of the chamber coated with Au film is designed as paraboloids. The infrared light is reflected twice before reaching to detectors, thus increasing optical path. Besides, a compensation method is presented to overcome the influence in variation of environment (ambient temperature, humidity and pressure), thus leading to improve the accuracy in gas detection. Experimental results demonstrated that detection ranges are 0-50,000 ppm for CH4, 0-44,500 ppm for CO, 0-48,000 ppm for CO2 and the accuracy is ±0.05%.

Enhanced Biocide Mitigation of Field Biofilm Consortia by a Mixture of D-Amino Acids

PubMed Central

Li, Yingchao; Jia, Ru; Al-Mahamedh, Hussain H.; Xu, Dake; Gu, Tingyue

2016-01-01

Microbiologically influenced corrosion (MIC) is a major problem in the oil and gas industry as well as in many other industries. Current treatment methods rely mostly on pigging and biocide dosing. Biocide resistance is a growing concern. Thus, it is desirable to use biocide enhancers to improve the efficacy of existing biocides. D-Amino acids are naturally occurring. Our previous work demonstrated that some D-amino acids are biocide enhancers. Under a biocide stress of 50 ppm (w/w) hydroxymethyl phosphonium sulfate (THPS) biocide, 1 ppm D-tyrosine and 100 ppm D-methionine used separately successfully mitigated the Desulfovibrio vulgaris biofilm on carbon steel coupons. The data reported in this work revealed that 50 ppm of an equimolar mixture of D-methionine, D-tyrosine, D-leucine, and D-tryptophan greatly enhanced 50 ppm THPS biocide treatment of two recalcitrant biofilm consortia containing sulfate reducing bacteria (SRB), nitrate reducing bacteria (NRB), and fermentative bacteria, etc., from oil-field operations. The data also indicated that individual D-amino acids were inadequate for the biofilm consortia. PMID:27379039

A new perspective on metals and other contaminants in fluoridation chemicals*

PubMed Central

Mullenix, Phyllis J

2014-01-01

Background: Fluoride additives contain metal contaminants that must be diluted to meet drinking water regulations. However, each raw additive batch supplied to water facilities does not come labeled with concentrations per contaminant. This omission distorts exposure profiles and the risks associated with accidents and routine use. Objectives: This study provides an independent determination of the metal content of raw fluoride products. Methods: Metal concentrations were analyzed in three hydrofluorosilicic acid (HFS) and four sodium fluoride (NaF) samples using inductively coupled plasma-atomic emission spectrometry. Arsenic levels were confirmed using graphite furnace atomic absorption analysis. Results: Results show that metal content varies with batch, and all HFS samples contained arsenic (4.9–56.0 ppm) or arsenic in addition to lead (10.3 ppm). Two NaF samples contained barium (13.3–18.0 ppm) instead. All HFS (212–415 ppm) and NaF (3312–3630 ppm) additives contained a surprising amount of aluminum. Conclusions: Such contaminant content creates a regulatory blind spot that jeopardizes any safe use of fluoride additives. PMID:24999851

METHOD OF CONTROLLING CORROSION IN A NEUTRONIC REACTOR

DOEpatents

Kidder, C.P.; Sloan, C.K.

1959-10-01

A method is described for reducing or removing corrosion and iron deposits on aluminum surfaces from coolant water comprising adding to the coolant alkali metal dichromate in a concentration of between 1.8 and 2.2 ppm, adjusting the pH to between 7.3 and 7.8 by adding CaCO/sub 3/ or other similar material, and adding a silicious material such as diatomaceous earth of a particle size of 5 to 15 microns to effect a suspension of between 2 and 300 ppm and circulating it through the reactor.

Spike-adding in parabolic bursters: The role of folded-saddle canards

NASA Astrophysics Data System (ADS)

Desroches, Mathieu; Krupa, Martin; Rodrigues, Serafim

2016-09-01

The present work develops a new approach to studying parabolic bursting, and also proposes a novel four-dimensional canonical and polynomial-based parabolic burster. In addition to this new polynomial system, we also consider the conductance-based model of the Aplysia R15 neuron known as the Plant model, and a reduction of this prototypical biophysical parabolic burster to three variables, including one phase variable, namely the Baer-Rinzel-Carillo (BRC) phase model. Revisiting these models from the perspective of slow-fast dynamics reveals that the number of spikes per burst may vary upon parameter changes, however the spike-adding process occurs in an explosive fashion that involves special solutions called canards. This spike-adding canard explosion phenomenon is analysed by using tools from geometric singular perturbation theory in tandem with numerical bifurcation techniques. We find that the bifurcation structure persists across all considered systems, that is, spikes within the burst are incremented via the crossing of an excitability threshold given by a particular type of canard orbit, namely the true canard of a folded-saddle singularity. However there can be a difference in the spike-adding transitions in parameter space from one case to another, according to whether the process is continuous or discontinuous, which depends upon the geometry of the folded-saddle canard. Using these findings, we construct a new polynomial approximation of the Plant model, which retains all the key elements for parabolic bursting, including the spike-adding transitions mediated by folded-saddle canards. Finally, we briefly investigate the presence of spike-adding via canards in planar phase models of parabolic bursting, namely the theta model by Ermentrout and Kopell.

Shallow Water Propagation

DTIC Science & Technology

2010-02-26

bottom waveguide. The lower contour plot demonstrates that this method, unlike other parabolic equations, can treat seismic sources. 20100308162...solitons. One illustration in Figure 8 shows depth-averaged data at the Naval Research Laboratory vertical line array (VLA) [dashed blue curves...vertical line array about 15 km from the source. The right panel [blue curves] compares corresponding simulations from a three-dimensional adiabatic mode

The hydrogen-storing microporous silica 'Microcluster' reduces acetaldehyde contained in a distilled spirit.

PubMed

Kato, Shinya; Miwa, Nobuhiko

2016-12-01

Acetaldehyde is a detrimental substance produced in alcoholic liquor aging. We assessed an ability of hydrogen-storing microporous silica 'Microcluster' (MC+) to reduce acetaldehyde, as compared with autoclave-dehydrogenated MC+ (MC-). Acetaldehyde was quantified spectrophotometrically by an enzymatic method. Authentic acetaldehyde was treated by MC+ for 20min, and decreased from 43.4ppm to 10.9ppm, but maintained at 49.3ppm by MC-. On the other hand, acetaldehyde contained in a distilled spirit was decreased from 29.5ppm to 3.1ppm at 20min by MC+, but not decreased by MC-. Addition of MC+ or MC- to distilled water without acetaldehyde showed no seeming effect on the quantification used. Accordingly acetaldehyde in a distilled spirit is reduced to ethanol by hydrogen contained in MC+, but not by the silica moiety of MC+. Hydrogen gas of 1.2mL was released for 20min from MC+ of 0.59g in water, resulting in dissolved hydrogen of 1.09ppm and an oxidation- reduction potential of -687.0mV indicative of a marked reducing ability. Thus, MC+ has an ability to reduce acetaldehyde in a distilled spirit due to dissolved hydrogen released from MC+. Copyright © 2016 Elsevier B.V. All rights reserved.

Extracellular matrices for gastrointestinal surgery: Ex vivo testing and current applications

PubMed Central

Hoeppner, Jens; Marjanovic, Goran; Helwig, Peter; Hopt, Ulrich Theodor; Keck, Tobias

2010-01-01

AIM: To assess the effects of bile and pancreatic juice on structural and mechanical resistance of extracellular matrices (ECMs) in vitro. METHODS: Small-intestinal submucosa (SIS), porcine dermal matrix (PDM), porcine pericardial matrix (PPM) and bovine pericardial matrix (BPM) were incubated in human bile and pancreatic juice in vitro. ECMs were examined by macroscopic observation, scanning electron microscopy (SEM) and testing of mechanical resistance. RESULTS: PDM dissolved within 4 d after exposure to bile or pancreatic juice. SIS, PPM and PDM retained their integrity for > 60 d when incubated in either digestive juice. The effect of bile was found to be far more detrimental to mechanical stability than pancreatic juice in all tested materials. In SIS, the loss of mechanical stability after incubation in either of the digestive secretions was less distinct than in PPM and BPM [mFmax 4.01/14.27 N (SIS) vs 2.08/5.23 N (PPM) vs 1.48/7.89 N (BPM)]. In SIS, the extent of structural damage revealed by SEM was more evident in bile than in pancreatic juice. In PPM and BPM, structural damage was comparable in both media. CONCLUSION: PDM is less suitable for support of gastrointestinal healing. Besides SIS, PPM and BPM should also be evaluated experimentally for gastrointestinal indications. PMID:20731016

Relation of pulmonary responses induced by 6.6-h exposures to 0.08 ppm ozone and 2-h exposures to 0.30 ppm ozone via chamber and face-mask inhalation.

PubMed

Adams, William C

2003-07-01

While direct comparison of pulmonary responses to 6.6-h exposures to 0.08 to 0.12 ppm ozone O3 have demonstrated that chamber and face-mask inhalation methods yield closely similar results, no comparative study of responses to 2-h intermittent exercise (IE) exposures to higher O3 concentrations have been reported. The present study was designed to achieve three primary objectives: (1) to compare pulmonary function and symptoms effects of a 2-h IE exposure to 0.30 ppm O3 via chamber and via face mask; (2) to compare the pulmonary effects of 6.6-h chamber exposure to 0.08 ppm O3 to those observed in 2-h IE 0.30 ppm O3 exposures via chamber and via face mask; and (3) to examine filtered air (FA) recovery pulmonary and symptoms responses following chamber exposures of 6.6 h to 0.08 ppm O3 and 2 h to 0.30 ppm O3. A simple regression of postexposure percent change in FEV(1.0) for the 2-h IE, 0.30-ppm O3 chamber exposure as a function of postexposure percent change in FEV(1.0) for the 2-h IE, 0.30-ppm O3 exposure with face mask yielded an R(2) of 0.83. Further, a regression of the postexposure FEV(1.0) response to the chamber 6.6-h, 0.08-ppm O3 exposure as a function of postexposure FEV(1.0) response to the face mask 2-h IE, 0.30-ppm O3 exposure (R(2) of 0.34) was similar to the 0.40 value obtained for the two chamber exposures FEV(1.0) response comparison. Results of the 1.4-h FA recovery following the two chamber O3 exposures showed different rates of FEV(1.0) and symptoms rectification that appeared related to the total O3 dose (product of O3 concentration, ventilation rate, and duration). More data are needed to clarify short-term recovery of O3-induced pulmonary effects and how they may be related to the more abundant data available on the delayed recovery of pulmonary function seen over longer time periods, such as 24 h.

Consideration of air quality standards for vegetation with respect to ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heggestad, H.E.

1968-01-01

There is an increasing body of evidence that ozone is the most damaging of all air pollutants affecting vegetation. It is the principal oxidant in the photochemical smog complex. Concentrations measured with an ultraviolet photometer, considered specific for ozone, have exceeded 0.5 part per million (ppM) in the Los Angeles area. Only one-tenth of this level, or 0.05 ppM, for 8 hours is known to injure very sensitive tobacco varieties. Studies in several laboratories show that a broad spectrum of plant species is visibly affected after a few hours exposure at concentrations much lower than 0.5 ppM. There is alsomore » some evidence that ozone reduces plant growth. Many factors must be taken into account in considering standards for possible use in the protection of vegetation from ozone damage. These include ozone concentration and methods of measurement, time of exposure, possible additive effects of other pollutants, sensitivity of species to ozone, their economic value, and the extent of injury which can be tolerated. The response of a species to the pollutant is conditioned by genetic factors and environmental conditions. The lack of routine, specific methods for measuring ozone in ambient air is a handicap. California and Colorado established standards for oxidants at 0.15 ppM and 0.10 ppM, respectively, for 1 hour. How these standards relate to the dosage of ozone that causes acute and chronic injury to various plant species is discussed. 28 references.« less

G measurements with time-of-swing method at HUST

PubMed Central

Li, Qing; Liu, Jian-Ping; Zhao, Hui-Hui; Yang, Shan-Qing; Tu, Liang-Cheng; Liu, Qi; Shao, Cheng-Gang; Hu, Zhong-Kun; Milyukov, Vadim; Luo, Jun

2014-01-01

We review the G measurements with time-of-swing method at HUST. Two independent experiments have been completed and an improved experiment is in progress. The first G value was determined as 6.6699(7)×10−11 m3 kg−1 s−2 with a relative standard uncertainty (ur) of 105 ppm by using a long period torsion pendulum and two cylindrical source masses. Later, this result was corrected to be 6.6723(9)×10−11 m3 kg−1 s−2 with ur=130 ppm after considering the density distribution of the cylinders and the air buoyancy, which was 360 ppm larger than the previous value. In 2009, a new experiment by using a simple block pendulum and spherical source masses with more homogeneous density was carried out. A series of improvements were performed, and the G value was determined to be 6.67349(18)×10−11 m3 kg−1 s−2 with ur=26 ppm. To reduce the anelasticity of the torsion fibre, fused silica fibres with Q's of approximately 5×104 are used to measure G in the ongoing experiment. These fibres are coated with thin layers of germanium and bismuth in turn to reduce the electrostatic effect. Some other improvements include the gravity compensation, reduction of the coating layer effect, etc. The prospective uncertainty of the next G value is 20 ppm or lower. PMID:25202004

Sodium tripolyphosphate cross-linked chitosan based sensor for enhacing sensing properties towards acetone

NASA Astrophysics Data System (ADS)

Nasution, T. I.; Asrosa, R.; Nainggolan, I.; Balyan, M.; Indah, R.; Wahyudi, A.

2018-02-01

In this report, sensing properties of sodium tripolyphosphate (TPP) cross-linked chitosan based sensor has been successfully enhanced towards acetone. Chitosan solutions were cross-linked with sodium TPP in variation of 0.1%, 0.5%, 1% and 1.5% w/v, respectively. The sensors were fabricated in film form using an electrochemical deposition method. The sensing properties of the sensors were observed by exposing the pure chitosan and sodium TPP cross-linked chitosan sensors towards acetone concentrations of 5, 10, 50, 100 and 200 ppm. The measurement results revealed that the maximum response in output voltage value of pure chitosan sensor was 0.35 V while sodium TPP crosslinked chitosan sensors were above 0.35 V towards 5 ppm acetone concentration. When the sensors were exposed towards acetone concentration of 200 ppm, the maximum response of pure chitosan was 0.45 V while sodium TPP crosslinked chitosan sensors were above 0.45 V. Amongst the variation of sodium TPP, the maximum response of 1% sodium TPP was the highest since the maximum response was 0.4 V and 0.6 V towards 5 ppm and 200 ppm acetone concentration, respectively. While the maximum responses of other sodium TPP concentrations were under 0.4 V and 0.6 V towards 5 ppm and 200 ppm acetone concentration. Moreover, 1% sodium TPP cross-linked chitosan based sensor showed good reproducibility and outstanding lifetime. Therefore, 1% sodium TPP cross-linked chitosan based sensor has exhibited remarkable sensing properties as a novel acetone sensor.

Fluoride Consumption and Its Impact on Oral Health

PubMed Central

Jiménez-Farfán, María Dolores; Hernández-Guerrero, Juan Carlos; Juárez-López, Lilia Adriana; Jacinto-Alemán, Luis Fernando; de la Fuente-Hernández, Javier

2011-01-01

Objective The purpose of this study was to evaluate caries and dental fluorosis among Mexican preschoolers and school-aged children in a non-endemic zone for fluorosis and to measure its biological indicators. Methods DMFT, DMFS, dmft, dmfs, and CDI indexes were applied. Fluoride urinary excretion and fluoride concentrations in home water, table salt, bottled water, bottled drinks, and toothpaste were determined. Results Schoolchildren presented fluorosis (CDI = 0.96) and dental caries (DMFT = 2.64 and DMFS = 3.97). Preschoolers presented dmft = 4.85 and dmfs = 8.80. DMFT and DMFS were lower in children with mild to moderate dental fluorosis (DF). Variable fluoride concentrations were found in the analyzed products (home water = 0.18–0.44 ppm F, table salt = 0–485 ppm F, bottled water = 0.18–0.47 ppm F, juices = 0.08–1.42 ppm F, nectars = 0.07–1.30 ppm F, bottled drinks = 0.10–1.70 ppm F, toothpaste = 0–2,053 ppm F). Mean daily fluoride excretion was 422 ± 176 μg/24 h for schoolchildren and 367 ± 150 μg/24 h for preschoolers. Conclusions Data from our study show that, despite values of excretion within an optimal fluoride intake range, the prevalence of caries was significant in both groups, and 60% of the 11- to 12-year-old children presented with dental fluorosis. In addition, variable fluoride concentrations in products frequently consumed by children were found. PMID:21318021

Fast Time and Space Parallel Algorithms for Solution of Parabolic Partial Differential Equations

NASA Technical Reports Server (NTRS)

Fijany, Amir

1993-01-01

In this paper, fast time- and Space -Parallel agorithms for solution of linear parabolic PDEs are developed. It is shown that the seemingly strictly serial iterations of the time-stepping procedure for solution of the problem can be completed decoupled.

Spectral reflectance as an indicator of foliar concentrations of arsenic in common sunflower (Helianthus annuus)

NASA Astrophysics Data System (ADS)

Gandy, Yuridia Patricia Peralta De

Studies were conducted to investigate the use of spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination of soil. Germination method was developed for sunflower seeds, and cohorts of sunflower seedlings in hydroponic tanks were established. The cohorts were exposed to 0 ppm, 5 ppm, 7.5 ppm, and 10 ppm treatments of As (V) and reflectance measurements of foliage were collected using a spectroradiometer during two experiments. Results demonstrated the feasibility of using spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination. In both experiments, arsenic concentrations in leaf tissues were directly proportional to arsenic concentrations in hydroponic solutions in which such plants were grown. Although the effect(s) of arsenic accumulation had minimal impact on reflectance of visible wavelengths, the effects on NIR reflectance were substantial and resulted in a progressive decrease in reflectance as arsenic concentrations in foliage increased.

Fluorescence excitation-emission matrix (EEM) spectroscopy and cavity ring-down (CRD) absorption spectroscopy of oil-contaminated jet fuel using fiber-optic probes.

PubMed

Omrani, Hengameh; Barnes, Jack A; Dudelzak, Alexander E; Loock, Hans-Peter; Waechter, Helen

2012-06-21

Excitation emission matrix (EEM) and cavity ring-down (CRD) spectral signatures have been used to detect and quantitatively assess contamination of jet fuels with aero-turbine lubricating oil. The EEM spectrometer has been fiber-coupled to permit in situ measurements of jet turbine oil contamination of jet fuel. Parallel Factor (PARAFAC) analysis as well as Principal Component Analysis and Regression (PCA/PCR) were used to quantify oil contamination in a range from the limit of detection (10 ppm) to 1000 ppm. Fiber-loop cavity ring-down spectroscopy using a pulsed 355 nm laser was used to quantify the oil contamination in the range of 400 ppm to 100,000 ppm. Both methods in combination therefore permit the detection of oil contamination with a linear dynamic range of about 10,000.

Simulation of parabolic reflectors for ultraviolet phototherapy

NASA Astrophysics Data System (ADS)

Grimes, David Robert

2016-08-01

Ultraviolet (UVR) phototherapy is widely used to treat an array of skin conditions, including psoriasis, eczema and vitiligo. For such interventions, a quantified dose is vital if the treatment is to be both biologically effective and to avoid the detrimental effects of over-dosing. As dose is absorbed at surface level, the orientation of patient site with respect to the UVR lamps modulates effective dose. Previous investigations have modelled this behaviour, and examined the impact of shaped anodized aluminium reflectors typically placed around lamps in phototherapy cabins. These mirrors are effective but tend to yield complex patterns of reflection around the cabin which can result in substantial dose inhomogeneity. There has been some speculation over whether using the reflective property of parabolic mirrors might improve dose delivery or homogeneity through the treatment cabin. In this work, the effects of parabolic mirrors are simulated and compared with standard shaped mirrors. Simulation results strongly suggest that parabolic reflectors reduce total irradiance relative to standard shaped reflectors, and have a negligible impact on dose homogeneity.

Linear and Nonlinear Optical Properties of Spherical Quantum Dots: Effects of Hydrogenic Impurity and Conduction Band Non-Parabolicity

NASA Astrophysics Data System (ADS)

Rezaei, G.; Vaseghi, B.; Doostimotlagh, N. A.

2012-03-01

Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/AlxGa1-x As spherical quantum dot are theoretically investigated, using the Luttinger—Kohn effective mass equation. So, electronic structure and optical properties of the system are studied by means of the matrix diagonalization technique and compact density matrix approach, respectively. Finally, effects of an impurity, band edge non-parabolicity, incident light intensity and the dot size on the linear, the third-order nonlinear and the total optical absorption coefficients and refractive index changes are investigated. Our results indicate that, the magnitudes of these optical quantities increase and their peaks shift to higher energies as the influences of the impurity and the band edge non-parabolicity are considered. Moreover, incident light intensity and the dot size have considerable effects on the optical absorption coefficients and refractive index changes.

The Influenced of Lactobacillus plantarum Starter Addition and The Length Time of Fermentation Process on The Activity of Seaweed Antioxidant Ulva lactuca from Krakal Beach, Yogyakarta

NASA Astrophysics Data System (ADS)

Ambarsari, N. D.; Rushanti, I. R. P. A.; Setyaji, A.; Ningsih, T. R.; Nurhana, N.; Subekhi, I.; Dewi, E. N.

2018-02-01

Seaweed contains phenol compound functioning as antioxidant. Lactobacillus plantarum starter addition in a fermentation process was expected will increase the activity of antioxidant. The purpose of this research was to determine the influence of L. plantarum addition and the length of fermentation on the activity of antioxidant in U. lactuca. The experiment was conducted with factorial design. The first treatment consisted 2 different factors namely without L. plantarum addition and L. plantarum addition. While the second treatment were the different length fermentation time: 0, 12, 24, and 36 hours. Each treatment were done in thriplicate. The data was analyzed using ANOVA and BNJ test was applied if there any differences betweenthe treatments. The results showed that the fresh U. lactuca with L. plantarum addition for 36 hours fermentation had TPC BAL 9,83 CFU/ml, pH 4,26, phenol 231 ppm and antioxidant activity IC501375,12 ppm. Dried U. lactuca with L. plantarum addition that was fermentized for 36 hours had TPC BAL 9,10 CFU/ml, pH 4,75, phenol 166,24 ppm and antioxidant activity IC504070,32 ppm. The fresh U. lactuca with L. plantarum addition for 36 hours fermentation was the best treatment since the antioxidant activity is IC501375,12 ppm. Although the antioxidant activity was categorized as weak but it was still showed an increase compared to the result of antioxidant activity with maceration method using n-hexana dissolver which was 11213,76 ppm, ethyl acetate 9770,285 ppm, and ethanol extact 4921,79 ppm.

Laboratory Evaluations of the Fractions Efficacy of Annona senegalensis (Annonaceae) Leaf Extract on Immature Stage Development of Malarial and Filarial Mosquito Vectors

PubMed Central

Lame, Younoussa; Nukenine, Elias Nchiwan; Pierre, Danga Yinyang Simon; Elijah, Ajaegbu Eze; Esimone, Charles Okechukwu

2015-01-01

Background: Within the framework to control mosquitoes, ovicidal, larvicidal and pupicidal activity of Annona senegalensis leaf extract and its 4 fractions against Anopheles gambiae and Culex quinquefasciatus were evaluated in the laboratory conditions. Methods: Ovicidal test was performed by submitting at least 100 eggs of mosquitoes to 125, 250, 500, 1000 and 2000 ppm concentrations, while larvicidal and pupicidal effects were assessed by submitting 25 larvae or pupae to the concentrations of 2500, 1250, 625 and 312.5 ppm of plant extract or fractions of A. senegalensis. Results: The eggs of An. gambiae were most affected by N-hexane (0.00% hatchability) and chloroform (03.67% hatchability) fractions compared to Cx. quinquefasciatus where at least 25 % hatchability were recorded at 2000 ppm. For larvicidal test, N-hexane (LC50= 298.8 ppm) and chloroform (LC50= 418.3 ppm) fractions were more effective than other fractions on An. gambiae larvae while, a moderate effectiveness was also observed with N-hexane (LC50= 2087.6 ppm), chloroform (LC50= 9010.1 ppm) fractions on Cx. quinquefasciatus larvae. The highest mortality percent of the pupae were also recorded with N-hexane and chloroform fractions on An. gambiae at 2500 ppm. As for Cx. quinquefasciatus only 50 % and 36 % mortality were recorded with N-hexane and chloroform fractions respectively. Conclusion: The extract of A. senegalensis was toxic on immature stage of mosquito species tested. By splitting methanolic crude extract, only N-hexane and chloroform fractions were revealed to possess a mosquitocidal effects and could be considered and utilized for future immature mosquito vectors control. PMID:26623434

Generation and tooth contact analysis of spiral bevel gears with predesigned parabolic functions of transmission errors

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Lee, Hong-Tao

1989-01-01

A new approach for determination of machine-tool settings for spiral bevel gears is proposed. The proposed settings provide a predesigned parabolic function of transmission errors and the desired location and orientation of the bearing contact. The predesigned parabolic function of transmission errors is able to absorb piece-wise linear functions of transmission errors that are caused by the gear misalignment and reduce gear noise. The gears are face-milled by head cutters with conical surfaces or surfaces of revolution. A computer program for simulation of meshing, bearing contact and determination of transmission errors for misaligned gear has been developed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turchi, Craig; Kurup, Parthiv; Akar, Sertac

This study lists material composition data for two concentrating solar power (CSP) plant designs: a molten-salt power tower and a hypothetical parabolic trough plant, both of which employ a molten salt for the heat transfer fluid (HTF) and thermal storage media. The two designs have equivalent generating and thermal energy storage capacities. The material content of the saltHTF trough plant was approximately 25% lower than a comparably sized conventional oil-HTF parabolic trough plant. The significant reduction in oil, salt, metal, and insulation mass by switching to a salt-HTF design is expected to reduce the capital cost and LCOE for themore » parabolic trough system.« less

Controllable parabolic-cylinder optical rogue wave.

PubMed

Zhong, Wei-Ping; Chen, Lang; Belić, Milivoj; Petrović, Nikola

2014-10-01

We demonstrate controllable parabolic-cylinder optical rogue waves in certain inhomogeneous media. An analytical rogue wave solution of the generalized nonlinear Schrödinger equation with spatially modulated coefficients and an external potential in the form of modulated quadratic potential is obtained by the similarity transformation. Numerical simulations are performed for comparison with the analytical solutions and to confirm the stability of the rogue wave solution obtained. These optical rogue waves are built by the products of parabolic-cylinder functions and the basic rogue wave solution of the standard nonlinear Schrödinger equation. Such rogue waves may appear in different forms, as the hump and paw profiles.

Magnetic levitation in two-dimensional geometry with translational invariance

NASA Astrophysics Data System (ADS)

Lorin, C.; Mailfert, A.

2008-11-01

The development of activities in space and of the corresponding technologies requires research on the behavior of both matter and biological organisms under weightless conditions. Various methods have been invented in order to simulate weightlessness, for example, drop towers, sounding rockets, or parabolic flights. Magnetic field ground-based devices have also been developed. This paper introduces an optimization method of the magnetic field so as to obtain magnetic levitation in a two-dimensional cylindrical geometry.

Applications of Sharp Interface Method for Flow Dynamics, Scattering and Control Problems

DTIC Science & Technology

2012-07-30

Reynolds number, Advances in Applied Mathematics and Mechanics, to appear. 17. K. Ito and K. Kunisch, Optimal Control of Parabolic Variational ...provides more precise and detailed sensitivity of the solution and describes the dynamical change due to the variation in the Reynolds number. The immersed... Inequalities , Journal de Math. Pures et Appl, 93 (2010), no. 4, 329-360. 18. K. Ito and K. Kunisch, Semi-smooth Newton Methods for Time-Optimal Control for a

Parabolic Dish Concentrator (PDC-2) Development

NASA Technical Reports Server (NTRS)

Rafinejad, D.

1984-01-01

The design of the Parabolic Dish Concentrator (PDC-2) is described. The following five subsystems of the concentrator are discussed: (1) reflective surface subsystem, (2) support structure subsystem, (3) foundation, (4) drive subsystem, and (5) electrical and control subsystem. The status of the PDC-2 development project is assessed.

Recent Progress in the Development and Application of the Parabolic Equation

DTIC Science & Technology

1984-05-07

awarded a research grant to NUSC to encourage technical collaboration with university scientists at the Yale University Center for Scientific Computa...TD 7145 REFERENCES 1.F. U. Tappert, "The Parabolic Approximation Metthod ,ŕ Wave Propagation ano Unoierwater Acoustics, editeu by J. B

Reliability of ^1^H NMR analysis for assessment of lipid oxidation at frying temperatures

USDA-ARS?s Scientific Manuscript database

The reliability of a method using ^1^H NMR analysis for assessment of oil oxidation at a frying temperature was examined. During heating and frying at 180 °C, changes of soybean oil signals in the ^1^H NMR spectrum including olefinic (5.16-5.30 ppm), bisallylic (2.70-2.88 ppm), and allylic (1.94-2.1...

77 FR 59578 - Notice of Filing of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-28

...-nitroguanidine, in or on fruiting, vegetables, group 8-10, except pepper/eggplant subgroup 8-10B at 0.2 ppm; and pepper/eggplant subgroup 8-10B at 0.7 ppm. Adequate enforcement methodology (LC/MS/MS analysis) is... validated, including LC- MS/MS methods for use on tomato, pepper, melon, and cucumber. The analytical...

Effect of temperature on the breakthrough of a charcoal tube during vinyl chloride monomer sampling.

PubMed

Roh, J; Park, Y J; Kim, C N; Lim, N G; Lee, S H; Song, J S; Won, J U; Talaska, G

2000-01-01

This study evaluated the effects of temperature on breakthrough of two standard collection media at various concentrations during vinyl chloride monomer (VCM) sampling. The National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) methods were evaluated. To determine whether breakthrough of VCM would occur at the extremes of exposure and temperature that might be encountered in some workplaces, air samples containing 4 ppm (10.24 mg/m3), 8 ppm (20.45 mg/m3), 16 ppm (40.98 mg/m3), and 32 ppm (81.80 mg/m3) of VCM were collected at temperatures of 4, 22, and 40 degrees C. Five liters of air was sampled at the rate of 0.05 L/min for 100 min using the activated charcoal tube recommended by NIOSH. A second tube was added to the sampling train to collect any VCM that might not have been absorbed in the first tube. To collect VCM air samples by the OSHA method, two carbon molecular sieve tubes were connected serially and 3 L of air was sampled at the rate of 0.05 L/min for 60 min. A gas chromatograph with a flame ionization detector and ultra 2 capillary column was used to analyze VCM. Significant breakthrough was found when sampling at higher temperatures with the NIOSH method. No breakthrough was found when samples were collected using the OSHA media at different temperatures and concentrations. Therefore, under hot ambient conditions (>22 degrees C), the possibility of breakthrough should be considered when sampling VCM by the NIOSH method.

Pulse position modulation for compact all-fiber vehicle laser rangefinder development

NASA Astrophysics Data System (ADS)

Mao, Xuesong; Cheng, Yongzhi; Xiong, Ying; Inoue, Daisuke; Kagami, Manabu

2017-10-01

We propose a method for developing small all-fiber vehicle laser rangefinders that is based on pulse position modulation (PPM) and data integration and present a theoretical study on its performance. Compared with spatial coupling, which is employed by most of the current commercial vehicle laser rangefinders, fiber coupling has the advantage that it can guide laser echoes into the interior of a car, so the electronic components following the photodiode can operate in a moderate-temperature environment. However, optical fibers have numerical apertures (NAs), which means that a laser beam from a receiving lens cannot be coupled into an optical fiber if its incident angle exceeds the critical value. Therefore, the effective size of the receiving lens is typically small since it is limited by its focal length and the NA of the fiber, causing the power of the laser echoes gathered by the receiving lens to be insufficient for performing target identification. Instead of increasing the peak transmitting laser power unrestrictedly, PPM and data integration effectively compensate for the low signal-to-noise ratio that results from the effective receiving lens size reduction. We validated the proposed method by conducting numerical simulations and performance analysis. Finally, we compared the proposed method with pseudorandom noise (PN) code modulation and found that, although the two methods perform equally well in single-target measurement scenarios, PPM is more effective than PN code modulation for multitarget measurement. In addition, PPM enables the transmission of laser beams with higher peak powers and requires less computation than PN code modulation does.

Classification of Tidal Disruption Events Based on Stellar Orbital Properties

NASA Astrophysics Data System (ADS)

Hayasaki, Kimitake; Zhong, Shiyan; Li, Shuo; Berczik, Peter; Spurzem, Rainer

2018-03-01

We study the rates of tidal disruption of stars on bound to unbound orbits by intermediate-mass to supermassive black holes using high-accuracy direct N-body experiments. Stars from the star cluster approaching the black hole can have three types of orbit: eccentric, parabolic, and hyperbolic. Since the mass fallback rate shows different variabilities depending on the orbital type, we can classify tidal disruption events (TDEs) into three main categories: eccentric, parabolic, and hyperbolic. The respective TDEs are characterized by two critical values of the orbital eccentricity: the lower critical eccentricity is the one below which stars on eccentric orbits cause finite, intense accretion, and the upper critical eccentricity is the one above which stars on hyperbolic orbits cause no accretion. Moreover, we find that parabolic TDEs can be divided into three subclasses: precisely parabolic, marginally eccentric, and marginally hyperbolic. We analytically derive that the mass fallback rate of marginally eccentric TDEs can be flatter and slightly higher than the standard fallback rate proportional to t ‑5/3, whereas it can be flatter and lower for marginally hyperbolic TDEs. We confirm using N-body experiments that only a few eccentric, precisely parabolic, and hyperbolic TDEs can occur in a spherical stellar system with a single intermediate-mass to supermassive black hole. A substantial fraction of the stars approaching the black hole would cause marginally eccentric or marginally hyperbolic TDEs.

The First European Parabolic Flight Campaign with the Airbus A310 ZERO-G

NASA Astrophysics Data System (ADS)

Pletser, Vladimir; Rouquette, Sebastien; Friedrich, Ulrike; Clervoy, Jean-Francois; Gharib, Thierry; Gai, Frederic; Mora, Christophe

2016-12-01

Aircraft parabolic flights repetitively provide up to 23 seconds of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences and in Technology, to test instrumentation prior to space flights and to train astronauts before a space mission. The use of parabolic flights is complementary to other microgravity carriers (drop towers, sounding rockets), and preparatory to manned space missions on board the International Space Station and other manned spacecraft, such as Shenzhou and the future Chinese Space Station. After 17 years of using the Airbus A300 ZERO-G, the French company Novespace, a subsidiary of the ' Centre National d'Etudes Spatiales' (CNES, French Space Agency), based in Bordeaux, France, purchased a new aircraft, an Airbus A310, to perform parabolic flights for microgravity research in Europe. Since April 2015, the European Space Agency (ESA), CNES and the ` Deutsches Zentrum für Luft- und Raumfahrt e.V.' (DLR, the German Aerospace Center) use this new aircraft, the Airbus A310 ZERO-G, for research experiments in microgravity. The first campaign was a Cooperative campaign shared by the three agencies, followed by respectively a CNES, an ESA and a DLR campaign. This paper presents the new Airbus A310 ZERO-G and its main characteristics and interfaces for scientific experiments. The experiments conducted during the first European campaign are presented.

Evaluation of traditional plant extracts for innate immune mechanisms and disease resistance against fish bacterial Aeromonas hydrophila and Pseudomonas sp.

NASA Astrophysics Data System (ADS)

Hardi, E. H.; Saptiani, G.; Kusuma, I. W.; Suwinarti, W.; Nugroho, R. A.

2018-03-01

The purposes of this study were to evaluate effect of ethanol herbal extracts of Boesenbergia pandurata, Solanum ferox and Zingimber zerumbet on Tilapia (Oreochromis nilaticus) innate immune mechanisms and disease resistance against Aeromonas hydrophila and Pseudomonas sp. Fish were intramuscularly injected with 0.1 mL/fish (1010 CFU mL-1) of each bacterium on the day 6th of post treatment using extract by several methods (injection, oral administration and immersion). The doses of extract were 600 ppm of B. pandurata, 900 ppm S. ferox and 200 ppm of Z. zerumbet. The percentage mortality, Relative Percent Survival (RPS) and innate immune response were assessed on weeks 1, 2, 3 and 4. All the methods were effective to enhance the immune parameters after 2 weeks application and the RPS of treatment reached more than 90 %. The results showed that the injection method of extracts was the most effective method to control A. hydrophila and Pseudomonas sp. The result indicated that all the doses of extracts could be significantly influence the immune response and protect the health status of tilapia against A. hydrophila and Pseudomonas sp. infections.

VERA Core Simulator Methodology for PWR Cycle Depletion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kochunas, Brendan; Collins, Benjamin S; Jabaay, Daniel

2015-01-01

This paper describes the methodology developed and implemented in MPACT for performing high-fidelity pressurized water reactor (PWR) multi-cycle core physics calculations. MPACT is being developed primarily for application within the Consortium for the Advanced Simulation of Light Water Reactors (CASL) as one of the main components of the VERA Core Simulator, the others being COBRA-TF and ORIGEN. The methods summarized in this paper include a methodology for performing resonance self-shielding and computing macroscopic cross sections, 2-D/1-D transport, nuclide depletion, thermal-hydraulic feedback, and other supporting methods. These methods represent a minimal set needed to simulate high-fidelity models of a realistic nuclearmore » reactor. Results demonstrating this are presented from the simulation of a realistic model of the first cycle of Watts Bar Unit 1. The simulation, which approximates the cycle operation, is observed to be within 50 ppm boron (ppmB) reactivity for all simulated points in the cycle and approximately 15 ppmB for a consistent statepoint. The verification and validation of the PWR cycle depletion capability in MPACT is the focus of two companion papers.« less

Simple 1H NMR spectroscopic method for assay of salts of the contrast agent diatrizoate in commercial solutions.

PubMed

Hanna, G M; Lau-Cam, C A

1996-01-01

A simple, accurate, and specific 1H NMR spectroscopic method was developed for the assay of diatrizoate meglumine or the combination diatrizoate meglumine and diatrizoate sodium in commercial solutions for injection. A mixture of injectable solution and sodium acetate, the internal standard, was diluted with D2O and the 1H NMR spectrum of the solution was obtained. Two approaches were used to calculate the drug content, based on the integral values for the -N-CO-CH3 protons of diatrizoic acid at 2.23 ppm, and -N-CH3 protons of meglumine at 2.73 ppm, and the CH3-CO-protons of sodium acetate at 1.9 ppm. Recoveries (mean +/- standard deviation) of diatrizoic acid and meglumine from 10 synthetic mixtures of various amounts of these compounds with a fixed amount of internal standard were 100.3 +/- 0.55% and 100.1 +/- 0.98%, respectively. In addition to providing a direct means of simultaneously assaying diatrizoic acid and meglumine, the proposed NMR method can also be used to identify diatrizoate meglumine and each of its molecular components.

Performance predictions for a parabolic localizer antenna on Runway 28R - San Francisco Airport.

DOT National Transportation Integrated Search

1973-06-01

The TSC ILS localizer model is used to predict the performance of the Texas Instruments "wide aperture" parabolic antenna as a localizer system for runway 28R at San Francisco Airport. Course derogation caused by the new American Airlines hangar is c...

Thermal energy storage effort at JPL

NASA Technical Reports Server (NTRS)

Young, D. L.

1980-01-01

The technical, operational, and economic readiness of parabolic dish systems for electric and thermal applications was investigated. A parabolic dish system was then developed to the point at which subsequent commercialization activities can lead to successful market penetration. The immediate possible applications of the dish system to thermal energy storage are discussed.

Toxicity of seaweed-synthesized silver nanoparticles against the filariasis vector Culex quinquefasciatus and its impact on predation efficiency of the cyclopoid crustacean Mesocyclops longisetus.

PubMed

Murugan, Kadarkarai; Benelli, Giovanni; Ayyappan, Suganya; Dinesh, Devakumar; Panneerselvam, Chellasamy; Nicoletti, Marcello; Hwang, Jiang-Shiou; Kumar, Palanisamy Mahesh; Subramaniam, Jayapal; Suresh, Udaiyan

2015-06-01

Nearly 1.4 billion people in 73 countries worldwide are threatened by lymphatic filariasis, a parasitic infection that leads to a disease commonly known as elephantiasis. Filariasis is vectored by mosquitoes, with special reference to the genus Culex. The main control tool against mosquito larvae is represented by treatments with organophosphates and insect growth regulators, with negative effects on human health and the environment. Recently, green-synthesized nanoparticles have been proposed as highly effective larvicidals against mosquito vectors. In this research, we attempted a reply to the following question: do green-synthesized nanoparticles affect predation rates of copepods against mosquito larvae? We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles using the frond extract of Caulerpa scalpelliformis. The toxicity of the seaweed extract and silver nanoparticles was assessed against the filarial vector Culex quinquefasciatus. Then, we evaluated the predatory efficiency of the cyclopoid crustacean Mesocyclops longisetus against larval instars of C. quinquefasciatus in a nanoparticle-contaminated water environment. Green-synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In mosquitocidal assays, the LC₅₀ values of the C. scalpelliformis extract against C. quinquefasciatus were 31.38 ppm (I), 46.49 ppm (II), 75.79 ppm (III), 102.26 ppm (IV), and 138.89 ppm (pupa), while LC₅₀ of silver nanoparticles were 3.08 ppm, (I), 3.49 ppm (II), 4.64 ppm (III), 5.86 ppm (IV), and 7.33 ppm (pupa). The predatory efficiency of the copepod M. longisetus in the control treatment was 78 and 59% against I and II instar larvae of C. quinquefasciatus. In a nanoparticle-contaminated environment, predation efficiency was 84 and 63%, respectively. Predation was higher against first instar larvae over other instars. Overall, our study showed that seaweed-synthesized silver nanoparticles can be proposed in synergy with biological control agents against Culex larvae, since their use leads to little detrimental effects against aquatic predators, such as copepods.

A ventilation intervention study in classrooms to improve indoor air quality: the FRESH study

PubMed Central

2013-01-01

Background Classroom ventilation rates often do not meet building standards, although it is considered to be important to improve indoor air quality. Poor indoor air quality is thought to influence both children’s health and performance. Poor ventilation in The Netherlands most often occurs in the heating season. To improve classroom ventilation a tailor made mechanical ventilation device was developed to improve outdoor air supply. This paper studies the effect of this intervention. Methods The FRESH study (Forced-ventilation Related Environmental School Health) was designed to investigate the effect of a CO2 controlled mechanical ventilation intervention on classroom CO2 levels using a longitudinal cross-over design. Target CO2 concentrations were 800 and 1200 parts per million (ppm), respectively. The study included 18 classrooms from 17 schools from the north-eastern part of The Netherlands, 12 experimental classrooms and 6 control classrooms. Data on indoor levels of CO2, temperature and relative humidity were collected during three consecutive weeks per school during the heating seasons of 2010–2012. Associations between the intervention and weekly average indoor CO2 levels, classroom temperature and relative humidity were assessed by means of mixed models with random school-effects. Results At baseline, mean CO2 concentration for all schools was 1335 ppm (range: 763–2000 ppm). The intervention was able to significantly decrease CO2 levels in the intervention classrooms (F (2,10) = 17.59, p < 0.001), with a mean decrease of 491 ppm. With the target set at 800 ppm, mean CO2 was 841 ppm (range: 743–925 ppm); with the target set at 1200 ppm, mean CO2 was 975 ppm (range: 887–1077 ppm). Conclusions Although the device was not capable of precisely achieving the two predefined levels of CO2, our study showed that classroom CO2 levels can be reduced by intervening on classroom ventilation using a CO2 controlled mechanical ventilation system. PMID:24345039

Denoising in digital speckle pattern interferometry using wave atoms.

PubMed

Federico, Alejandro; Kaufmann, Guillermo H

2007-05-15

We present an effective method for speckle noise removal in digital speckle pattern interferometry, which is based on a wave-atom thresholding technique. Wave atoms are a variant of 2D wavelet packets with a parabolic scaling relation and improve the sparse representation of fringe patterns when compared with traditional expansions. The performance of the denoising method is analyzed by using computer-simulated fringes, and the results are compared with those produced by wavelet and curvelet thresholding techniques. An application of the proposed method to reduce speckle noise in experimental data is also presented.

Advanced ammonia (NH3) monitoring system for industrial applications

NASA Astrophysics Data System (ADS)

Spector, Oded; Jacobson, Esther

1999-12-01

The present paper describes an Electro-Optical Monitoring System developed for the real time in-situ monitoring of Ammonia (NH3) emissions, at very low concentrations in air, well below the hazardous levels. Ammonia is the starting chemical for almost all industrially produced nitrogen compounds and is therefore one of the most important inorganic raw materials. Due to its unique chemical and physical characteristics, the Ammonia (NH3) anhydrous gas is used in various industrial applications such as: Air Conditioning, Refrigeration (including space shuttles), Agriculture and Chemical Processing. NH3 gas, being a highly irritant toxic and flammable gas with a pungent odor detectable by human perception at 53 ppm, has a TLV-TWA of 25 ppm (TLV-STEL of 35 ppm) and a lower explosive limit (LEL) of 15% in air. Being extremely corrosive and irritating to the skin, eyes, nose and respiratory tract, (irritation begins at 130 - 200 ppm), exposures to high concentrations (above 2500 ppm) are life threatening, thus early detection of Ammonia at concentrations up to 50 ppm is essential to prevent its toxic influence. Existing detection methods for NH3 rely mainly on chemical sensors and analytical methods that require the gas to be sampled and introduced into the detection system via a probe, compared to various standards (for determining the concentration) and the result is not always reflecting the actual gas concentration. The emerging optical open path remote sensing technology that analyzes the specific 'finger print' absorption characteristics of NH3 in various narrow spectral bands, specifically in the UV solar blind band, is discussed including the rationale of the detection algorithm and system design. The system offers warning and alarm signals set at the above low concentration detection sensitivity, (10 - 50 ppm(DOT)m) thus providing reliable Ammonia detection over an air path from 3 (including air-duct applications) to 400 ft (1 - 120 m). Typical installations of Ammonia Monitoring Systems, field and laboratory test data are discussed, including spectral cross sensitivity analysis with interfering chemicals and changing environmental conditions (heat, humidity).

Development of a cw-laser-based cavity-ringdown sensor aboard a spacecraft for trace air constituents

NASA Technical Reports Server (NTRS)

Awtry, A. R.; Miller, J. H.

2002-01-01

The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 micrometers is used to pump an optical cavity absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity, selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.

Concentrating Solar Power Projects - La Africana | Concentrating Solar

Science.gov Websites

: Posadas (Córdoba) Owner(s): Ortiz/TSK/Magtel (100%) Technology: Parabolic trough Turbine Capacity: Net -Field Outlet Temp: 393°C Solar-Field Temp Difference: 100°C Power Block Turbine Capacity (Gross): 50.0 MW Turbine Capacity (Net): 50.0 MW Output Type: Steam Rankine Cooling Method: Wet cooling Thermal

Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

PubMed

Clément, Gilles; Loureiro, Nuno; Sousa, Duarte; Zandvliet, Andre

2016-01-01

We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g), hypergravity (1.8 g), and normal gravity (1 g). Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight

PubMed Central

Clément, Gilles; Loureiro, Nuno; Sousa, Duarte; Zandvliet, Andre

2016-01-01

We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5–6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g), hypergravity (1.8 g), and normal gravity (1 g). Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance. PMID:27463106

Effect of conduction band non-parabolicity on the optical gain of quantum cascade lasers based on the effective two-band finite difference method

NASA Astrophysics Data System (ADS)

Cho, Gookbin; Kim, Jungho

2017-09-01

We theoretically investigate the effect of conduction band non-parabolicity (NPB) on the optical gain spectrum of quantum cascade lasers (QCLs) using the effective two-band finite difference method. Based on the effective two-band model to consider the NPB effect in the multiple quantum wells (QWs), the wave functions and confined energies of electron states are calculated in two different active-region structures, which correspond to three-QW single-phonon and four-QW double-phonon resonance designs. In addition, intersubband optical dipole moments and polar-optical-phonon scattering times are calculated and compared without and with the conduction band NPB effect. Finally, the calculation results of optical gain spectra are compared in the two QCL structures having the same peak gain wavelength of 8.55 μm. The gain peaks are greatly shifted to longer wavelengths and the overall gain magnitudes are slightly reduced when the NPB effect is considered. Compared with the three-QW active-region design, the redshift of the peak gain is more prominent in the four-QW active-region design, which makes use of higher electronic states for the lasing transition.

Snowmelt runoff modeling in simulation and forecasting modes with the Martinec-Mango model

NASA Technical Reports Server (NTRS)

Shafer, B.; Jones, E. B.; Frick, D. M. (Principal Investigator)

1982-01-01

The Martinec-Rango snowmelt runoff model was applied to two watersheds in the Rio Grande basin, Colorado-the South Fork Rio Grande, a drainage encompassing 216 sq mi without reservoirs or diversions and the Rio Grande above Del Norte, a drainage encompassing 1,320 sq mi without major reservoirs. The model was successfully applied to both watersheds when run in a simulation mode for the period 1973-79. This period included both high and low runoff seasons. Central to the adaptation of the model to run in a forecast mode was the need to develop a technique to forecast the shape of the snow cover depletion curves between satellite data points. Four separate approaches were investigated-simple linear estimation, multiple regression, parabolic exponential, and type curve. Only the parabolic exponential and type curve methods were run on the South Fork and Rio Grande watersheds for the 1980 runoff season using satellite snow cover updates when available. Although reasonable forecasts were obtained in certain situations, neither method seemed ready for truly operational forecasts, possibly due to a large amount of estimated climatic data for one or two primary base stations during the 1980 season.

Ring-Sheared Drop (RSD): Microgravity Module for Containerless Flow Studies

NASA Astrophysics Data System (ADS)

Gulati, Shreyash; Raghunandan, Aditya; Rasheed, Fayaz; McBride, Samantha A.; Hirsa, Amir H.

2017-02-01

Microgravity is potentially a powerful tool for investigating processes that are sensitive to the presence of solid walls, since fluid containment can be achieved by surface tension. One such process is the transformation of protein in solution into amyloid fibrils; these are protein aggregates associated with neurodegenerative diseases such as Alzheimer's and Parkinson's. In addition to solid walls, experiments with gravity are also subject to influences from sedimentation of aggregates and buoyancy-driven convection. The ring-sheared drop (RSD) module is a flow apparatus currently under development to study formation of amyloid fibrils aboard the International Space Station (ISS). A 25 mm diameter drop of protein solution will be contained by surface tension and constrained by a pair of sharp-edged tubes, forming two contact rings. Shear can be imparted by rotating one ring with the other ring kept stationary. Here we report on parabolic flights conducted to test the growth and pinning of 10 mm diameter drops of water in under 10 s of microgravity. Finite element method (FEM) based fluid dynamics computations using a commercial package (COMSOL) assisted in the design of the parabolic flight experiments. Prior to the parabolic flights, the code was validated against experiments in the lab (1 g), on the growth of sessile and pendant droplets. The simulations show good agreement with the experiments. This modeling capability will enable the development of the RSD at the 25 mm scale for the ISS.

Smart reconfigurable parabolic space antenna for variable electromagnetic patterns

NASA Astrophysics Data System (ADS)

Kalra, Sahil; Datta, Rituparna; Munjal, B. S.; Bhattacharya, Bishakh

2018-02-01

An application of reconfigurable parabolic space antenna for satellite is discussed in this paper. The present study focuses on shape morphing of flexible parabolic antenna actuated with Shape Memory Alloy (SMA) wires. The antenna is able to transmit the signals to the desired footprint on earth with a desired gain value. SMA wire based actuation with a locking device is developed for a precise control of Antenna shape. The locking device is efficient to hold the structure in deformed configuration during power cutoff from the system. The maximum controllable deflection at any point using such actuation system is about 25mm with a precision of ±100 m. In order to control the shape of the antenna in a closed feedback loop, a Proportional, Integral and Derivative (PID) based controller is developed using LabVIEW (NI) and experiments are performed. Numerical modeling and analysis of the structure is carried out using finite element software ABAQUS. For data reduction and fast computation, stiffness matrix generated by ABAQUS is condensed by Guyan Reduction technique and shape optimization is performed using Non-dominated Sorting Genetic Algorithm (NSGA-II). The matching in comparative study between numerical and experimental set-up shows efficacy of our method. Thereafter, Electro-Magnetic (EM) simulations of the deformed shape is carried out using electromagnetic field simulation, High Frequency Structure Simulator (HFSS). The proposed design is envisaged to be very effective for multipurpose application of satellite system in the future missions of Indian Space Research Organization (ISRO).

Method for detecting trace impurities in gases

DOEpatents

Freund, Samuel M.; Maier, II, William B.; Holland, Redus F.; Beattie, Willard H.

1981-01-01

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (.about.2 ppm) present in commercial Xe and ppm levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Method for detecting trace impurities in gases

DOEpatents

Freund, S.M.; Maier, W.B. II; Holland, R.F.; Beattie, W.H.

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (approx. 2 ppM) present in commercial Xe and ppM levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Resolution Improvements in in Vivo1H NMR Spectra with Increased Magnetic Field Strength

NASA Astrophysics Data System (ADS)

Gruetter, Rolf; Weisdorf, Sally A.; Rajanayagan, Vasantham; Terpstra, Melissa; Merkle, Hellmut; Truwit, Charles L.; Garwood, Michael; Nyberg, Scott L.; Ugurbil, Kâmil

1998-11-01

The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from γ-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for1H NMR, which can lead to more than linear sensitivity gains.

Reproductive and developmental toxicity of hydrofluorocarbons used as refrigerants.

PubMed

Ema, Makoto; Naya, Masato; Yoshida, Kikuo; Nagaosa, Ryuichi

2010-04-01

The present paper summarizes data on the reproductive and developmental toxicity of hydrofluorocarbons (HFCs), including pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), difluoromethane (HFC-32) and 1,1,1,3,3-pentafluoropropane (HFC-245fa), used as refrigerants, published in openly available scientific literature. No developmental toxicity of HFC-125 was found even at 50,000 ppm in rats or rabbits. Although HFC-134a exhibited no dominant lethal effect or reproductive toxicity in rats, it caused low body weight in pre- and postnatal offspring and slightly retarded skeletal ossification in fetuses at 50,000 ppm in rats. No maternal or developmental toxicity was noted after exposure to HFC-143a even at 40,000 ppm in rats or rabbits or HFC-152a even at 50,000 ppm in rats. HFC-32 is slightly maternally and developmentally toxic at 50,000 ppm in rats, but not in rabbits. HFC-245fa caused decreases in maternal body weight and food consumption at 10,000 and 50,000 ppm and fetal weight at 50 000ppm. No evidence of teratogenicity for these HFCs was noted in rats or rabbits. There is limited information about the reproductive toxicity of these HFCs. Animal studies remain necessary for risk assessments of chemicals because it is difficult to find alternative methods to determine the toxic effects of chemicals. It is required to reduce emissions of organic vapors containing HFCs to reduce the risk of exposure. Copyright 2009 Elsevier Inc. All rights reserved.

A survey of the concentrations of eleven metals in vaccines, allergenic extracts, toxoids, blood, blood derivatives and other biological products.

PubMed

May, J C; Rains, T C; Maienthal, F J; Biddle, G N; Progar, J J

1986-10-01

Approximately 85 samples of injectable biological products regulated by the Center for Drugs and Biologics of the United States Food and Drug Administration were surveyed for the presence of 11 elements, namely aluminum, arsenic, barium, cadmium, chromium, lead, mercury, selenium, thallium and zinc, by flame and flameless methods of atomic absorption spectrometry and flame emission spectrometry. The range of products tested included whole blood, red cells, plasma, normal serum albumin, antihemophilic factor, and other products derived from blood; allergenic extracts including honey bee venom and house dust allergenic extracts; vaccines such as measles virus vaccine and typhoid vaccine; and tetanus toxoid. The metal concentrations found in the majority of these products were low or undetectable. The metal levels varied from manufacturer to manufacturer, product and lot-to-lot of the same manufacturer's products. House dust allergenic extracts had the highest concentrations of arsenic (2.4 ppm), cadmium (0.28 ppm), chromium (0.6 ppm) and lead (1.5 ppm) found in the study. A high zinc concentration (24 ppm) in an immune serum globulin was attributed to the zinc-containing rubber stopper in contact with the product. A range of 0.36-3.30 ppm aluminum was found for seven 25% normal serum albumin samples from seven manufacturers. Values of 8.2, 17 and 18 ppm aluminum were found in one manufacturer's 25% normal serum albumin. These aluminum values appeared to be the result of an anomaly in this manufacturer's production that has not been repeated to date.

Decontamination and Disposal Methods for Chemical Agents - A Literature Survey

DTIC Science & Technology

1982-11-01

aqueous copper (I) ammonia complex to give a red copper (1) acetylide precipitate. The precipitate was determined either iodometricaily (sensitivity of I...ppm in decontamination solution) or colorintrically by a copper (11) ammonia complex (12 ppm). Lewisite was also assayed by gas liquid chromatography...to ammonia (then degraded to nitrogen) and carbonate ion. The latter reaction is relatively slow. The reaction may thus be con- sidered to consist of

THE DETERMINATION OF BORON IN ZIRCALOY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freegarde, M.; Cartwright, J.

1962-03-01

An account is given of the development of a simple and reliable procedure for determining boron in Zircaloy at the parts per million level. The sample is dissolved in a mixture of bromine and methanol, and the boron is separated by distillation and determined as its rosocyanin complex with curcumin. The reproducibility of the method is characterized by a standard deviation of 0.03 ppm at the 0.3 ppm level. (auth)

Screening of exhaled breath by low-resolution multicomponent FT-IR spectrometry in patients attending emergency departments.

PubMed

Laakso, Olli; Haapala, Matti; Kuitunen, Tapio; Himberg, Jaakko-Juhani

2004-03-01

Interest in noninvasive methods for disease diagnosis is increasing. In this study, we tested the utility and potential of a portable Fourier transform infrared (FT-IR) multicomponent analyzer in the emergency rooms (ERs) of two Finnish hospitals. Major detected breath volatiles in this population were ethanol, carbon monoxide, methane, and acetone, in addition to carbon dioxide and water. The analysis of breath revealed an ethanol concentration of over 25 ppm (0.1 g/L in blood) in 56 out of 589 patients (9.5%). During nightshifts the proportion was 30% for all and 63% for trauma patients. Five-hundred eighty-four patients had measurable carbon monoxide in their breath. A breath carbon monoxide of over 4 ppm (4.4 micro g/L) differentiated smokers from nonsmokers. Methane over 2 ppm (1.3 micro g/L) was detected in the breath of 32% of the participants. Methane concentration was higher among aged patients. Two-hundred ninety-eight participants had detectable acetone in their breath. Elevated exhaled acetone [10-76 ppm (23-75 micro g/L)] was detected in 10 patients. The FT-IR method proved functional in the ER setting. A major advantage over blood sampling was fast and easy analysis performed by nonlaboratory personnel.

Fluoride content of clay minerals and argillaceous earth materials

USGS Publications Warehouse

Thomas, Josephus; Glass, H.D.; White, W.A.; Trandel, R.M.

1977-01-01

A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ±5% at different levels of fluoride concentration.Data are presented for various clay minerals and for the <2-µm fractions of marine and nonmarine clays and shales. Fluoride values range from 44 ppm (0.0044%) for nontronite from Colfax, WA, to 51,800 ppm (5.18%) for hectorite from Hector, CA. In general, clays formed under hydrothermal conditions are relatively high in fluoride content, provided the hydrothermal waters are high in fluoride content. Besides hectorite, dickite from Ouray, CO, was found to contain more than 50 times as much fluoride (6700 ppm) as highly crystalline geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals.It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content.

Integrated parabolic nanolenses on MicroLED color pixels

NASA Astrophysics Data System (ADS)

Demory, Brandon; Chung, Kunook; Katcher, Adam; Sui, Jingyang; Deng, Hui; Ku, Pei-Cheng

2018-04-01

A parabolic nanolens array coupled to the emission of a nanopillar micro-light emitting diode (LED) color pixel is shown to reduce the far field divergence. For a blue wavelength LED, the total emission is 95% collimated within a 0.5 numerical aperture zone, a 3.5x improvement over the same LED without a lens structure. This corresponds to a half-width at half-maximum (HWHM) line width reduction of 2.85 times. Using a resist reflow and etchback procedure, the nanolens array dimensions and parabolic shape are formed. Experimental measurement of the far field emission shows a HWHM linewidth reduction by a factor of 2x, reducing the divergence over the original LED.

Well-posedness of nonlocal parabolic differential problems with dependent operators.

PubMed

Ashyralyev, Allaberen; Hanalyev, Asker

2014-01-01

The nonlocal boundary value problem for the parabolic differential equation v'(t) + A(t)v(t) = f(t) (0 ≤ t ≤ T), v(0) = v(λ) + φ, 0 < λ ≤ T in an arbitrary Banach space E with the dependent linear positive operator A(t) is investigated. The well-posedness of this problem is established in Banach spaces C 0 (β,γ) (E α-β ) of all E α-β -valued continuous functions φ(t) on [0, T] satisfying a Hölder condition with a weight (t + τ)(γ). New Schauder type exact estimates in Hölder norms for the solution of two nonlocal boundary value problems for parabolic equations with dependent coefficients are established.

The State-of-the-Art Parabolic Equation Approximation as Applied to Underwater Acoustic Propagation with Discussions on Intensive Computations: An Invited Paper Presented at the Meeting of the Acoustical Society of America (108th) Held in Minneapolis, Minnesota on 8-12 October 1984

DTIC Science & Technology

1984-10-12

MCYwWWm M& de4 l 8.id iW d by N1wk "wt Finite Difference Reference Wavenumber Interface Split-Step Ordinary Difference Equation Wide Angle Parabolic...Problems D. Lee and S. Praiser J. Comp. & Math. with Appls., 7(2), pp. 195-202 (1981) Finite - Difference Solution to the Parabolic Wave Equation D. Lee, G...was incorporated into the ODE and finite difference models. At that time, we did not have a better implementation of the ODE solution, but we

Physiologic Pressure and Flow Changes During Parabolic Flight (Pilot Study)

NASA Technical Reports Server (NTRS)

Pantalos, George; Sharp, M. Keith; Mathias, John R.; Hargens, Alan R.; Watenpaugh, Donald E.; Buckey, Jay C.

1999-01-01

The objective of this study was to obtain measurement of cutaneous tissue perfusion central and peripheral venous pressure, and esophageal and abdominal pressure in human test subjects during parabolic flight. Hemodynamic data recorded during SLS-I and SLS-2 missions have resulted in the paradoxical finding of increased cardiac stroke volume in the presence of a decreased central venous pressure (CVP) following entry in weightlessness. The investigators have proposed that in the absence of gravity, acceleration-induced peripheral vascular compression is relieved, increasing peripheral vascular capacity and flow while reducing central and peripheral venous pressure, This pilot study seeks to measure blood pressure and flow in human test subjects during parabolic flight for different postures.

Design and resolution analysis of parabolic mirror spectrometer

NASA Astrophysics Data System (ADS)

Wu, Su; Wang, Guodong; Xia, Guo; Sun, Yanchao; Hu, Mingyong

2017-10-01

In order to further eliminate aberration and improve resolution, the paper employs parabolic mirror as the collimating mirror and the focusing mirror to design "Z" configuration and "U" configuration optical structure of parabolic spectrometer with the F number 2.5 and the spectral range varying from 250 nm to 850 nm. We conduct experiments on ZEMAX to simulate and optimize the initial parameters of two structures with the root-mean-square (RMS) radius of spots along Y axis as the optimization goal. Through analyzing the spot diagram and the root-mean-square (RMS) of Y axis, we can see that the "U" configuration spectrometers can achieve much better spectral resolution than the "Z" configuration.

Mechatronic Prototype of Parabolic Solar Tracker.

PubMed

Morón, Carlos; Díaz, Jorge Pablo; Ferrández, Daniel; Ramos, Mari Paz

2016-06-15

In the last 30 years numerous attempts have been made to improve the efficiency of the parabolic collectors in the electric power production, although most of the studies have focused on the industrial production of thermoelectric power. This research focuses on the application of this concentrating solar thermal power in the unexplored field of building construction. To that end, a mechatronic prototype of a hybrid paraboloidal and cylindrical-parabolic tracker based on the Arduido technology has been designed. The prototype is able to measure meteorological data autonomously in order to quantify the energy potential of any location. In this way, it is possible to reliably model real commercial equipment behavior before its deployment in buildings and single family houses.

Highly efficient end-side-pumped Nd:YAG solar laser by a heliostat-parabolic mirror system.

PubMed

Almeida, J; Liang, D; Vistas, C R; Guillot, E

2015-03-10

We report a large improvement in the collection and slope efficiency of an Nd:YAG solar laser pumped by a heliostat-parabolic mirror system. A conical fused silica lens was used to further concentrate the solar radiation from the focal zone of a 2 m diameter primary concentrator to a Nd:YAG single-crystal rod within a conical pump cavity, which enabled multipass pumping to the active medium. A 56 W cw laser power was measured, corresponding to 21.1  W/m2 record-high solar laser collection efficiency with the heliostat-parabolic mirror system. 4.9% slope efficiency was calculated, corresponding to 175% enhancement over our previous result.

Evaluation of the three-dimensional parabolic flow computer program SHIP

NASA Technical Reports Server (NTRS)

Pan, Y. S.

1978-01-01

The three-dimensional parabolic flow program SHIP designed for predicting supersonic combustor flow fields is evaluated to determine its capabilities. The mathematical foundation and numerical procedure are reviewed; simplifications are pointed out and commented upon. The program is then evaluated numerically by applying it to several subsonic and supersonic, turbulent, reacting and nonreacting flow problems. Computational results are compared with available experimental or other analytical data. Good agreements are obtained when the simplifications on which the program is based are justified. Limitations of the program and the needs for improvement and extension are pointed out. The present three dimensional parabolic flow program appears to be potentially useful for the development of supersonic combustors.

Mechatronic Prototype of Parabolic Solar Tracker

PubMed Central

Morón, Carlos; Díaz, Jorge Pablo; Ferrández, Daniel; Ramos, Mari Paz

2016-01-01

In the last 30 years numerous attempts have been made to improve the efficiency of the parabolic collectors in the electric power production, although most of the studies have focused on the industrial production of thermoelectric power. This research focuses on the application of this concentrating solar thermal power in the unexplored field of building construction. To that end, a mechatronic prototype of a hybrid paraboloidal and cylindrical-parabolic tracker based on the Arduido technology has been designed. The prototype is able to measure meteorological data autonomously in order to quantify the energy potential of any location. In this way, it is possible to reliably model real commercial equipment behavior before its deployment in buildings and single family houses. PMID:27314359

Topographically driven crustal flow and its implication to the development of pinned oroclines

NASA Technical Reports Server (NTRS)

Hsui, Albert T.; Wilkerson, M. Scott; Marshak, Stephen

1990-01-01

Pinned oroclines, a type of curved orogen which results from lateral pinning of a growing fold-thrust belt, tend to resemble parabolic Newtonian curvature modified by different degrees of flattening at the flow front. It is proposed that such curves can be generated by Newtonian crustal flow driven by topographic variations. In this model, regional topographic differences create a regional flow which produces a parabolic flow front on interaction with lateral bounding obstacles. Local topographic variations modify the parabolic curves and yield more flat-crested, non-Newtonian-type curvatures. A finite-difference thin-skin tectonic simulation demonstrates that both Newtonian and non-Newtonian curved orogens can be produced within a Newtonian crust.

Integrated parabolic nanolenses on MicroLED color pixels.

PubMed

Demory, Brandon; Chung, Kunook; Katcher, Adam; Sui, Jingyang; Deng, Hui; Ku, Pei-Cheng

2018-04-20

A parabolic nanolens array coupled to the emission of a nanopillar micro-light emitting diode (LED) color pixel is shown to reduce the far field divergence. For a blue wavelength LED, the total emission is 95% collimated within a 0.5 numerical aperture zone, a 3.5x improvement over the same LED without a lens structure. This corresponds to a half-width at half-maximum (HWHM) line width reduction of 2.85 times. Using a resist reflow and etchback procedure, the nanolens array dimensions and parabolic shape are formed. Experimental measurement of the far field emission shows a HWHM linewidth reduction by a factor of 2x, reducing the divergence over the original LED.

Solution of transonic flows by an integro-differential equation method

NASA Technical Reports Server (NTRS)

Ogana, W.

1978-01-01

Solutions of steady transonic flow past a two-dimensional airfoil are obtained from a singular integro-differential equation which involves a tangential derivative of the perturbation velocity potential. Subcritical flows are solved by taking central differences everywhere. For supercritical flows with shocks, central differences are taken in subsonic flow regions and backward differences in supersonic flow regions. The method is applied to a nonlifting parabolic-arc airfoil and to a lifting NACA 0012 airfoil. Results compare favorably with those of finite-difference schemes.

An Adaptive Method of Lines with Error Control for Parabolic Equations of the Reaction-Diffusion Type.

DTIC Science & Technology

1984-06-01

space discretization error . 1. I 3 1. INTRODUCTION Reaction- diffusion processes occur in many branches of biology and physical chemistry. Examples...to model reaction- diffusion phenomena. The primary goal of this adaptive method is to keep a particular norm of the space discretization error less...AD-A142 253 AN ADAPTIVE MET6 OFD LNES WITH ERROR CONTROL FOR 1 INST FOR PHYSICAL SCIENCE AND TECH. I BABUSKAAAO C7 EA OH S UMR AN UNVC EEP R

STOCK Mechanics:. a General Theory and Method of Energy Conservation with Applications on Djia

NASA Astrophysics Data System (ADS)

Tuncay, Çağlar

A new method, based on the original theory of conservation of sum of kinetic and potential energy defined for prices is proposed and applied on the Dow Jones Industrials Average (DJIA). The general trends averaged over months or years gave a roughly conserved total energy, with three different potential energies, i.e., positive definite quadratic, negative definite quadratic and linear potential energy for exponential rises (and falls), sinusoidal oscillations and parabolic trajectories, respectively. Corresponding expressions for force (impact) are also given.

New Methods for Improved Double Circular-Arc Helical Gears

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Lu, Jian

1997-01-01

The authors have extended the application of double circular-arc helical gears for internal gear drives. The geometry of the pinion and gear tooth surfaces has been determined. The influence of errors of alignment on the transmission errors and the shift of the bearing contact have been investigated. Application of a predesigned parabolic function for the reduction of transmission errors was proposed. Methods of grinding of the pinion-gear tooth surfaces by a disk-shaped tool and a grinding worm were proposed.

Numerical calculation of transonic flow about slender bodies of revolution

NASA Technical Reports Server (NTRS)

Bailey, F. R.

1971-01-01

A relaxation method is described for the numerical solution of the transonic small disturbance equation for flow about a slender body of revolution. Results for parabolic arc bodies, both with and without an attached sting, are compared with wind-tunnel measurements for a free-stream Mach number range from 0.90 to 1.20. The method is also used to show the effects of wind-tunnel wall interference by including boundary conditions representing porous-wall and open-jet wind-tunnel test sections.

On several aspects and applications of the multigrid method for solving partial differential equations

NASA Technical Reports Server (NTRS)

Dinar, N.

1978-01-01

Several aspects of multigrid methods are briefly described. The main subjects include the development of very efficient multigrid algorithms for systems of elliptic equations (Cauchy-Riemann, Stokes, Navier-Stokes), as well as the development of control and prediction tools (based on local mode Fourier analysis), used to analyze, check and improve these algorithms. Preliminary research on multigrid algorithms for time dependent parabolic equations is also described. Improvements in existing multigrid processes and algorithms for elliptic equations were studied.

Pulmonary Impairment and Risk Assessment in a Diacetyl-Exposed Population: Microwave Popcorn Workers.

PubMed

Park, Robert M; Gilbert, Stephen J

2018-06-01

The butter flavoring additive, diacetyl (DA), can cause bronchiolitis obliterans (BO) by inhalation. A risk assessment was performed using data from a microwave popcorn manufacturing plant. Current employees' medical history and pulmonary function tests together with air sampling over a 2.7-year period were used to analyze forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC). The exposure responses for declining pulmonary function and for possible early onset of BO were estimated using multiple regression methods. Several exposure metrics were investigated; benchmark dose and excess lifetime risk of impairment were calculated. Forty-six percent of the population had less than 6 months exposure to DA. Percent-of-predicted FEV1 declined with cumulative exposure (0.40 per ppm-yr, P < 10) as did percent FEV1/FVC (0.13 per ppm-yr, P = 0.0004). Lifetime respiratory impairment prevalence of one per thousand resulted from 0.005 ppm DA and one per thousand lifetime incidence of impairment was predicted for 0.002 ppm DA. DA exposures, often exceeding 1 ppm in the past, place workers at high risk of pulmonary impairment.

Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air.

PubMed

Mallik, Arun Kumar; Farrell, Gerald; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Semenova, Yuliya

2018-01-26

A silica gel coated microsphere resonator is proposed and experimentally demonstrated for measurements of ammonia (NH 3 ) concentration in air with ultra-high sensitivity. The optical properties of the porous silica gel layer change when it is exposed to low (parts per million (ppm)) and even ultra-low (parts per billion (ppb)) concentrations of ammonia vapor, leading to a spectral shift of the WGM resonances in the transmission spectrum of the fiber taper. The experimentally demonstrated sensitivity of the proposed sensor to ammonia is estimated as 34.46 pm/ppm in the low ammonia concentrations range from 4 ppm to 30 ppm using an optical spectrum analyser (OSA), and as 800 pm/ppm in the ultra-low range of ammonia concentrations from 2.5 ppb to 12 ppb using the frequency detuning method, resulting in the lowest detection limit (by two orders of magnitude) reported to date equal to 0.16 ppb of ammonia in air. In addition, the sensor exhibits excellent selectivity to ammonia and very fast response and recovery times measured at 1.5 and 3.6 seconds, respectively. Other attractive features of the proposed sensor are its compact nature, simplicity of fabrication.

Tackling the growing threat of dengue: Phyllanthus niruri-mediated synthesis of silver nanoparticles and their mosquitocidal properties against the dengue vector Aedes aegypti (Diptera: Culicidae).

PubMed

Suresh, Udaiyan; Murugan, Kadarkarai; Benelli, Giovanni; Nicoletti, Marcello; Barnard, Donald R; Panneerselvam, Chellasamy; Kumar, Palanisamy Mahesh; Subramaniam, Jayapal; Dinesh, Devakumar; Chandramohan, Balamurugan

2015-04-01

Mosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is the primary vector of dengue. The use of synthetic insecticides to control Aedes mosquitoes lead to high operational costs and adverse nontarget effects. In this scenario, eco-friendly control tools are a priority. We proposed a novel method to synthesize silver nanoparticles using the aqueous leaf extract of Phyllanthus niruri, a cheap and nontoxic material. The UV-vis spectrum of the aqueous medium containing silver nanostructures showed a peak at 420 nm corresponding to the surface plasmon resonance band of nanoparticles. SEM analyses of the synthesized nanoparticles showed a mean size of 30-60 nm. EDX spectrum showed the chemical composition of the synthesized nanoparticles. XRD highlighted that the nanoparticles are crystalline in nature with face-centered cubic geometry. Fourier transform infrared spectroscopy (FTIR) of nanoparticles exhibited prominent peaks 3,327.63, 2,125.87, 1,637.89, 644.35, 597.41, and 554.63 cm(-1). In laboratory assays, the aqueous extract of P. niruri was toxic against larval instars (I-IV) and pupae of A. aegypti. LC50 was 158.24 ppm (I), 183.20 ppm (II), 210.53 ppm (III), 210.53 ppm (IV), and 358.08 ppm (pupae). P. niruri-synthesized nanoparticles were highly effective against A. aegypti, with LC50 of 3.90 ppm (I), 5.01 ppm (II), 6.2 ppm (III), 8.9 ppm (IV), and 13.04 ppm (pupae). In the field, the application of silver nanoparticles (10 × LC50) lead to A. aegypti larval reduction of 47.6%, 76.7% and 100%, after 24, 48, and 72 h, while the P. niruri extract lead to 39.9%, 69.2 % and 100 % of reduction, respectively. In adulticidal experiments, P. niruri extract and nanoparticles showed LC50 and LC90 of 174.14 and 6.68 ppm and 422.29 and 23.58 ppm, respectively. Overall, this study highlights that the possibility to employ P. niruri leaf extract and green-synthesized silver nanoparticles in mosquito control programs is concrete, since both are effective at lower doses if compared to synthetic products currently marketed, thus they could be an advantageous alternative to build newer and safer tools against dengue vectors.

Thank You for Flying the Vomit Comet

ERIC Educational Resources Information Center

Dempsey, Robert; DiLisi, Gregory A.; DiLisi, Lori A.; Santo, Gretchen

2007-01-01

This paper describes our flight aboard NASA's C9 "Weightless Wonder," an aircraft that creates multiple periods of microgravity by conducting a series of parabolic maneuvers over the Gulf of Mexico. Because passengers often develop motion sickness during these parabolic maneuvers, the C9 is more affectionately known as the "Vomit Comet." To…

NREL, SPI Solar and Trimark Optimize Parabolic Trough Receiver Performance

Science.gov Websites

(CSP) plants. Photo of parabolic trough receiver equipment in a laboratory Photo by Dennis Schroeder Receivers in CSP plants take a lot of abuse, from dramatic temperature changes to numerous mechanical conditions can lead to big improvements in the overall efficiency of CSP plants

Forward Sound Propagation Around Seamounts: Application of Acoustic Models to the Kermit-Roosevelt and Elvis Seamounts

DTIC Science & Technology

2009-06-01

large number of range steps. Brooke et al. [73] developed a Canadian Parabolic Equation model ( PECan ). In the model, the split-step Padé algorithm... PECan : A Canadian parabolic equation model for underwater sound propagation. J. Computational Acoustics, 9(1):69-100, 2001 [74] Michael D

An Application of Calculus: Optimum Parabolic Path Problem

ERIC Educational Resources Information Center

Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali

2009-01-01

A practical and technological application of calculus problem is posed to motivate freshman students or junior high school students. A variable coefficient of friction is used in modelling air friction. The case in which the coefficient of friction is a decreasing function of altitude is considered. The optimum parabolic path for a flying object…

Concentrating Solar Power Projects - Gansu Akesai 50MW Molten Salt Trough

Science.gov Websites

project | Concentrating Solar Power | NREL Gansu Akesai 50MW Molten Salt Trough project Status . Technology: Parabolic trough Turbine Capacity: Net: 50.0 MW Gross: 50.0 MW Status: Under development Do you have more information, corrections, or comments? Background Technology: Parabolic trough Status: Under

JSC reduced gravity program and 1992 highlights

NASA Technical Reports Server (NTRS)

Williams, R. K.; Billica, L. W.

1993-01-01

A review is presented of the aircraft parabolic flight program in the U.S. including the USAF and NASA participation from 1957 to the present. The parabolic flight profile to achieve microgravity levels and intermediate g-levels is discussed. The NASA reduced gravity aircraft is described including the service provisions for this reimbursable project.

Concentrating Solar Power Projects - Urat Middle Banner 100MW Thermal Oil

Science.gov Websites

Parabolic Trough project | Concentrating Solar Power | NREL Middle Banner 100MW Thermal Oil Thermal Oil Parabolic Trough project Country: China Location: Urat Middle Banner (Inner Mongolia) Owner(s , 2017 Start Production: 2018 Participants Developer(s): Changzhou Royal Tech Solar Thermal Equipment Co

Circulatory filling pressures during transient microgravity induced by parabolic flight

NASA Technical Reports Server (NTRS)

Latham, Ricky D.; Fanton, John W.; White, C. D.; Vernalis, Mariana N.; Crisman, R. P.; Koenig, S. C.

1993-01-01

Theoretical concepts hold that blood in the gravity dependent portion of the body would relocate to more cephalad compartments under microgravity. The result is an increase in blood volume in the thoraic and cardiac chambers. However, experimental data has been somewhat contradictory and nonconclusive. Early studies of peripheral venous pressure and estimates of central venous pressure (CVP) from these data did not show an increase in CVP under microgravity. However, CVP recorded in human volunteers during a parabolic flight revealed an increase in CVP during the microgravity state. On the STS 40 shuttle mission, a payload specialist wore a fluid line that recorded CVP during the first few hours of orbital insertion. These data revealed decreased CVP. When this CVP catheter was tested during parabolic flight in four subjects, two had increased CVP recordings and two had decreased CVP measurements. In 1991, our laboratory performed parabolic flight studies in several chronic-instrumented baboons. It was again noted that centrally recorded right atrial pressure varied with exposure to microgravity, some animals having an increase, and others a decrease.

Short duration microgravity experiments in physical and life sciences during parabolic flights: the first 30 ESA campaigns.

PubMed

Pletser, Vladimir

2004-11-01

Aircraft parabolic flights provide repetitively up to 20 s of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences, to test instrumentation and to train astronauts before a space flight. The European Space Agency (ESA) has organized since 1984 thirty parabolic flight campaigns for microgravity research experiments utilizing six different airplanes. More than 360 experiments were successfully conducted during more than 2800 parabolas, representing a cumulated weightlessness time of 15 h 30 m. This paper presents the short duration microgravity research programme of ESA. The experiments conducted during these campaigns are summarized, and the different airplanes used by ESA are shortly presented. The technical capabilities of the Airbus A300 'Zero-G' are addressed. Some Physical Science, Technology and Life Science experiments performed during the last ESA campaigns with the Airbus A300 are presented to show the interest of this unique microgravity research tool to complement, support and prepare orbital microgravity investigations. c2004 Elsevier Ltd. All rights reserved.

Optimization of a multi-channel parabolic guide for the material science diffractometer STRESS-SPEC at FRM II

NASA Astrophysics Data System (ADS)

Rebelo Kornmeier, Joana; Ostermann, Andreas; Hofmann, Michael; Gibmeier, Jens

2014-02-01

Neutron strain diffractometers usually use slits to define a gauge volume within engineering samples. In this study a multi-channel parabolic neutron guide was developed to be used instead of the primary slit to minimise the loss of intensity and vertical definition of the gauge volume when using slits placed far away from the measurement position in bulky components. The major advantage of a focusing guide is that the maximum flux is not at the exit of the guide as for a slit system but at the focal point relatively far away from the exit of the guide. Monte Carlo simulations were used to optimise the multi-channel parabolic guide with respect to the instrument characteristics of the diffractometer STRESS-SPEC at the FRM II neutron source. Also the simulations are in excellent agreement with experimental measurements using the optimised multi-channel parabolic guide at the neutron diffractometer. In addition the performance of the guide was compared to the standard slit setup at STRESS-SPEC using a single bead weld sample used in earlier round robin tests for residual strain measurements.

Thermal buffering of receivers for parabolic dish solar thermal power plants

NASA Technical Reports Server (NTRS)

Manvi, R.; Fujita, T.; Gajanana, B. C.; Marcus, C. J.

1980-01-01

A parabolic dish solar thermal power plant comprises a field of parabolic dish power modules where each module is composed of a two-axis tracking parabolic dish concentrator which reflects sunlight (insolation) into the aperture of a cavity receiver at the focal point of the dish. The heat generated by the solar flux entering the receiver is removed by a heat transfer fluid. In the dish power module, this heat is used to drive a small heat engine/generator assembly which is directly connected to the cavity receiver at the focal point. A computer analysis is performed to assess the thermal buffering characteristics of receivers containing sensible and latent heat thermal energy storage. Parametric variations of the thermal inertia of the integrated receiver-buffer storage systems coupled with different fluid flow rate control strategies are carried out to delineate the effect of buffer storage, the transient response of the receiver-storage systems and corresponding fluid outlet temperature. It is concluded that addition of phase change buffer storage will substantially improve system operational characteristics during periods of rapidly fluctuating insolation due to cloud passage.

Numerical Study On Propulsion Performance Of The Parabolic Laser Thruster With Elongate Cylinder Nozzle

NASA Astrophysics Data System (ADS)

Cheng, Fuqiang; Hong, Yanji; Li, Qian; Wen, Ming

2011-11-01

Laser thrusters with a single nozzle, e.g. parabolic or conical, failed to constrict the flow field of high pressure effectively, resulting in poor propulsive performance. Under the condition of air-breathing mode, parabolic thruster models with an elongate cylinder nozzle were studied numerically by building a physical computation model. Initially, to verify the computation model, the influence of cylinder length on the momentum coupling coefficient was computed and compared with the experiments, which shows a good congruence. A model of diameter 20 mm and cylindrical length 80 mm obtains about 627.7 N/MW at single pulse energy density 1.5 J/cm2. Then, the influence of expanding angle of the parabolic nozzle on propulsion performance was gained for different laser pulse energies, and the evolution process of the flow field was analyzed. The results show: as the expanding angel increases, the momentum coupling coefficient increases remarkably at first and descends relative slowly after reaching a peak value; moreover, the peak positions stay constant around 33° with little variation when laser energy differs.

An approximate Riemann solver for real gas parabolized Navier-Stokes equations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urbano, Annafederica, E-mail: annafederica.urbano@uniroma1.it; Nasuti, Francesco, E-mail: francesco.nasuti@uniroma1.it

2013-01-15

Under specific assumptions, parabolized Navier-Stokes equations are a suitable mean to study channel flows. A special case is that of high pressure flow of real gases in cooling channels where large crosswise gradients of thermophysical properties occur. To solve the parabolized Navier-Stokes equations by a space marching approach, the hyperbolicity of the system of governing equations is obtained, even for very low Mach number flow, by recasting equations such that the streamwise pressure gradient is considered as a source term. For this system of equations an approximate Roe's Riemann solver is developed as the core of a Godunov type finitemore » volume algorithm. The properties of the approximated Riemann solver, which is a modification of Roe's Riemann solver for the parabolized Navier-Stokes equations, are presented and discussed with emphasis given to its original features introduced to handle fluids governed by a generic real gas EoS. Sample solutions are obtained for low Mach number high compressible flows of transcritical methane, heated in straight long channels, to prove the solver ability to describe flows dominated by complex thermodynamic phenomena.« less

Development of a 350ppm community carbon budget in Eugene, Oregon

NASA Astrophysics Data System (ADS)

Rice, A. L.; McRae, M.

2016-12-01

In the absence of national greenhouse gas emissions regulations, cities and county agencies across the United States have pursued a patchwork of emissions reduction targets and approaches to achieve those targeted goals. Some regions currently aim to meet efforts in mitigation with ambitious reduction targets that go beyond those pursued at national or international levels (e.g., UNFCCC, Paris, 2015). In 2014 The City of Eugene (Oregon, USA) City Council passed the Climate Recovery Ordinance which, in addition to outlining City emissions targets for 2020 and 2030, requested a proposal to adopt a community greenhouse gas reduction target consistent with achieving a global atmospheric carbon dioxide concentration of 350ppm by the year 2100. A 350ppm 2100 target, if achieved, could keep global average temperature rise to within 1°C by century-end but would necessarily limit cumulative fossil fuel carbon emissions to 500GtC (currently 375GtC). In contrast to historically-based approaches to greenhouse gas mitigation targets typically established by cities, the request of a community target based on a 350ppm target required the development of new methods by the City of Eugene. Collaborating with a Thriving Earth Exchange (TEX) scientist and working with a peer review team of regional analysts, the City of Eugene City Manager's Office produced a report which described a methodology for establishing a 350ppm community carbon budget and led a multi-session dialog with Eugene City Council members on possible action towards this goal. Here, we describe the methods developed and the collaborative effort which made it possible. The work led to the recent Eugene City Council adoption of an ambitious community-wide greenhouse gas emission reduction goal of 7.6% per year, consistent with global emissions reductions needed to achieve an atmospheric carbon dioxide concentration 350ppm by 2100.

Anesthesia and critical-care delivery in weightlessness: A challenge for research in parabolic flight analogue space surgery studies

NASA Astrophysics Data System (ADS)

Ball, Chad G.; Keaney, Marilyn A.; Chun, Rosaleen; Groleau, Michelle; Tyssen, Michelle; Keyte, Jennifer; Broderick, Timothy J.; Kirkpatrick, Andrew W.

2010-03-01

BackgroundMultiple nations are actively pursuing manned exploration of space beyond low-earth orbit. The responsibility to improve surgical care for spaceflight is substantial. Although the use of parabolic flight as a terrestrial analogue to study surgery in weightlessness (0 g) is well described, minimal data is available to guide the appropriate delivery of anesthesia. After studying anesthetized pigs in a 0 g parabolic flight environment, our group developed a comprehensive protocol describing prolonged anesthesia in a parabolic flight analogue space surgery study (PFASSS). Novel challenges included a physically remote vivarium, prolonged (>10 h) anesthetic requirements, and the provision of veterinary operating room/intensive care unit (ICU) equivalency on-board an aircraft with physical dimensions of <1.5 m 2 (Falcon 20). Identification of an effective anesthetic regime is particularly important because inhalant anesthesia cannot be used in-flight. MethodsAfter ethical approval, multiple ground laboratory sessions were conducted with combinations of anesthetic, pre-medication, and induction protocols on Yorkshire-cross specific pathogen-free (SPF) pigs. Several constant rate infusion (CRI) intravenous anesthetic combinations were tested. In each regimen, opioids were administered to ensure analgesia. Ventilation was supported mechanically with blended gradients of oxygen. The best performing terrestrial 1 g regime was flight tested in parabolic flight for its effectiveness in sustaining optimal and prolonged anesthesia, analgesia, and maintaining hemodynamic stability. Each flight day, a fully anesthetized, ventilated, and surgically instrumented pig was transported to the Flight Research Laboratory (FRL) in a temperature-controlled animal ambulance. A modular on-board surgical/ICU suite with appropriate anesthesia/ICU and surgical support capabilities was employed. ResultsThe mean duration of anesthesia (per flight day) was 10.28 h over four consecutive days. A barbiturate and ketamine-based CRI anesthetic regimen supplemented with narcotic analgesia by bolus administration offered the greatest prolonged hemodynamic stability through an IV route (within multiple transport vehicles and differing gravitational environments). Standardization and pre-packaging of anesthesia, emergency pharmaceuticals, and consumables were found to facilitate the interchange of the veterinary anesthesia team members between flights. This operational process was extremely challenging. ConclusionsWith careful organization of caregivers, equipment and protocols, providing anesthesia and life support in weightlessness is theoretically possible. Unfortunately, human resource costs are extensive and likely overwhelming. Comprehensive algorithms for extended spaceflight must recognize these costs prior to making assumptions or attempting to provide critical care in space.

Hazardous Continuation Backward in Time in Nonlinear Parabolic Equations, and an Experiment in Deblurring Nonlinearly Blurred Imagery

PubMed Central

Carasso, Alfred S

2013-01-01

Identifying sources of ground water pollution, and deblurring nanoscale imagery as well as astronomical galaxy images, are two important applications involving numerical computation of parabolic equations backward in time. Surprisingly, very little is known about backward continuation in nonlinear parabolic equations. In this paper, an iterative procedure originating in spectroscopy in the 1930’s, is adapted into a useful tool for solving a wide class of 2D nonlinear backward parabolic equations. In addition, previously unsuspected difficulties are uncovered that may preclude useful backward continuation in parabolic equations deviating too strongly from the linear, autonomous, self adjoint, canonical model. This paper explores backward continuation in selected 2D nonlinear equations, by creating fictitious blurred images obtained by using several sharp images as initial data in these equations, and capturing the corresponding solutions at some positive time T. Successful backward continuation from t=T to t = 0, would recover the original sharp image. Visual recognition provides meaningful evaluation of the degree of success or failure in the reconstructed solutions. Instructive examples are developed, illustrating the unexpected influence of certain types of nonlinearities. Visually and statistically indistinguishable blurred images are presented, with vastly different deblurring results. These examples indicate that how an image is nonlinearly blurred is critical, in addition to the amount of blur. The equations studied represent nonlinear generalizations of Brownian motion, and the blurred images may be interpreted as visually expressing the results of novel stochastic processes. PMID:26401430

Parabolic trough solar collector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eaton, J.H.

1985-01-15

A parabolic trough solar collector using reflective flexible materials is disclosed. A parabolic cylinder mirror is formed by stretching a flexible reflecting material between two parabolic end formers. The formers are held in place by a spreader bar. The resulting mirror is made to track the sun, focusing the sun's rays on a receiver tube. The ends of the reflective material are attached by glue or other suitable means to attachment straps. The flexible mirror is then attached to the formers. The attachment straps are mounted in brackets and tensioned by tightening associated nuts on the ends of the attachmentmore » straps. This serves both to stretch the flexible material orthogonal to the receiver tube and to hold the flexible material on the formers. The flexible mirror is stretched in the direction of the receiver tube by adjusting tensioning nuts. If materials with matching coefficients of expansion for temperature and humidity have been chosen, for example, aluminum foil for the flexible mirror and aluminum for the spreader bar, the mirror will stay in adjustment through temperature and humidity excursions. With dissimilar materials, e.g., aluminized mylar or other polymeric material and steel, spacers can be replaced with springs to maintain proper adjustment. The spreader bar cross section is chosen to be in the optic shadow of the receiver tube when tracking and not to intercept rays of the sun that would otherwise reach the receiver tube. This invention can also be used to make non-parabolic mirrors for other apparatus and applications.« less

Hazardous Continuation Backward in Time in Nonlinear Parabolic Equations, and an Experiment in Deblurring Nonlinearly Blurred Imagery.

PubMed

Carasso, Alfred S

2013-01-01

Identifying sources of ground water pollution, and deblurring nanoscale imagery as well as astronomical galaxy images, are two important applications involving numerical computation of parabolic equations backward in time. Surprisingly, very little is known about backward continuation in nonlinear parabolic equations. In this paper, an iterative procedure originating in spectroscopy in the 1930's, is adapted into a useful tool for solving a wide class of 2D nonlinear backward parabolic equations. In addition, previously unsuspected difficulties are uncovered that may preclude useful backward continuation in parabolic equations deviating too strongly from the linear, autonomous, self adjoint, canonical model. This paper explores backward continuation in selected 2D nonlinear equations, by creating fictitious blurred images obtained by using several sharp images as initial data in these equations, and capturing the corresponding solutions at some positive time T. Successful backward continuation from t=T to t = 0, would recover the original sharp image. Visual recognition provides meaningful evaluation of the degree of success or failure in the reconstructed solutions. Instructive examples are developed, illustrating the unexpected influence of certain types of nonlinearities. Visually and statistically indistinguishable blurred images are presented, with vastly different deblurring results. These examples indicate that how an image is nonlinearly blurred is critical, in addition to the amount of blur. The equations studied represent nonlinear generalizations of Brownian motion, and the blurred images may be interpreted as visually expressing the results of novel stochastic processes.

77 FR 27130 - Ametoctradin; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-09

...; grape at 5.0 ppm; grape, raisin at 8 ppm; hop, dried cones at 9 ppm; onion, bulb, subgroup 3-07A at 1.2 ppm; onion, green, subgroup 3-07B at 16 ppm; vegetable, cucurbit, group 9 at 4.5 ppm; vegetable... 50 ppm; grape at 4.0 ppm; grape, raisin at 8.0 ppm; hop, dried cones at 10 ppm; onion, bulb, subgroup...

Antibacterial activity of acidified sodium benzoate against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in tryptic soy broth and on cherry tomatoes.

PubMed

Chen, Huaiqiong; Zhong, Qixin

2018-06-02

Concerns about undesirable by-products from chlorine sanitation of fresh produce and the limited efficacy with the presence of organic matter, have led to studies on alternative washing solutions. The aim of this study was to evaluate the antibacterial activities of acidified sodium benzoate (NaB) solutions against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes in growth medium and on cherry tomatoes. Experimentally, the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs, >3 Log reduction) of NaB against E. coli O157:H7 ATCC 43895, S. Enteritidis, and L. monocytogenes Scott A were determined at pH 7.0-4.0 using micro-broth dilution method and agar plating method, respectively. The reduction of the three bacteria in tryptic soy broth (TSB) by 500 and 1000 ppm NaB at pH 2.0, 2.5 and 3.0 for 30 min at 21 °C was compared. Residual bacterial cocktails inoculated on cherry tomatoes were determined after soaking in 3000 ppm NaB solution adjusted to pH 2.0 for 3 min at 21 °C. Results showed that the MBC of NaB reduced from >10,000 ppm at pH 7.0 to 1000 ppm at pH 4.0 and was identical for the three bacteria. The log reduction of bacteria in TSB indicated that 1000 ppm NaB at pH 2.0 was the most effective in killing the three pathogens. The respective reduction of E. coli O157:H7 and S. enterica cocktails inoculated on cherry tomatoes immersed in 3000 ppm NaB (pH 2.0) at 21 °C for 3 min was 4.99 ± 0.57 and 4.08 ± 0.65 log CFU/g, which was significantly higher (p < 0.05) than the treatments of 200 ppm free chlorine at pH 6.5. Conversely, the reduction of L. monocytogenes on tomatoes by 3000 ppm NaB (4.88 ± 0.73 log CFU/g) was similar (p > 0.05) to 200 ppm chlorine. Furthermore, the reduction of bacterial cocktails on tomatoes by 3000 ppm NaB at pH 2.0 was not affected after adding 1% tomato puree, and bacteria were not detected in NaB washing solutions with and without 1% tomato puree and on following un-inoculated tomatoes. This study showed that acidified NaB solution may be used as an alternative post-harvest wash of produce. Copyright © 2018 Elsevier B.V. All rights reserved.

77 FR 30481 - Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-23

... Brassica vegetables) (crop group 4) at 15 ppm; milk at 0.01 ppm; milk, fat at 0.04 ppm; oilseeds, except...) at 8 ppm; cattle, fat at 0.01 ppm; cattle, liver at 0.04 ppm; cattle, meat at 0.01 ppm; cattle, meat... group 8-10) at 2 ppm; goat, fat at 0.01 ppm; goat, liver at 0.04 ppm; goat, meat at 0.01 ppm; goat, meat...

Oxidation and alpha-case formation in Ti–6Al–2Sn–4Zr–2Mo alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaddam, Raghuveer, E-mail: raghuveer.gaddam@ltu.se; Sefer, Birhan; Pederson, Robert

2015-01-15

Isothermal heat treatments in ambient air were performed on wrought Ti–6Al–2Sn–4Zr–2Mo (Ti-6242) material at 500, 593 and 700°C for times up to 500 h. In the presence of oxygen at elevated temperatures simultaneous reactions occurred in Ti-6242 alloy, which resulted in the formation of an oxide scale and a layer with higher oxygen concentration (termed as alpha-case). Total weight gain analysis showed that there was a transition in the oxidation kinetics. At 500°C, the oxidation kinetics obeyed a cubic relationship up to 200 h and thereafter changed to parabolic at prolonged exposure times. At 593°C, it followed a parabolic relationship.more » After heat treatment at 700°C, the oxidation obeyed a parabolic relationship up to 200 h and thereafter changed to linear at prolonged exposure times. The observed transition is believed to be due to the differences observed in the oxide scale. The activation energy for parabolic oxidation was estimated to be 157 kJ/mol. In addition, alpha-case layer was evaluated using optical microscope, electron probe micro-analyser and microhardness tester. The thickness of the alpha-case layer was found to be a function of temperature and time, increasing proportionally, and following a parabolic relationship. The activation energy for the formation of alpha-case layer was estimated to be 153 kJ/mol. - Highlights: • Transition in oxidation kinetics was observed in Ti–6Al–2Sn–4Zr–2Mo alloy in the temperature range 500–700°C. • The activation energy for parabolic oxidation and for alpha-case formation is about 157 kJ/mol and 153 kJ/mol. • Thickness of alpha-case layer estimated by optical microscopy and electron probe microanalysis is comparable.« less