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Sample records for control variance reduction

  1. MCNP variance reduction overview

    SciTech Connect

    Hendricks, J.S.; Booth, T.E.

    1985-01-01

    The MCNP code is rich in variance reduction features. Standard variance reduction methods found in most Monte Carlo codes are available as well as a number of methods unique to MCNP. We discuss the variance reduction features presently in MCNP as well as new ones under study for possible inclusion in future versions of the code.

  2. Ant colony method to control variance reduction techniques in the Monte Carlo simulation of clinical electron linear accelerators

    NASA Astrophysics Data System (ADS)

    García-Pareja, S.; Vilches, M.; Lallena, A. M.

    2007-09-01

    The ant colony method is used to control the application of variance reduction techniques to the simulation of clinical electron linear accelerators of use in cancer therapy. In particular, splitting and Russian roulette, two standard variance reduction methods, are considered. The approach can be applied to any accelerator in a straightforward way and permits, in addition, to investigate the "hot" regions of the accelerator, an information which is basic to develop a source model for this therapy tool.

  3. Ant colony method to control variance reduction techniques in the Monte Carlo simulation of clinical electron linear accelerators of use in cancer therapy

    NASA Astrophysics Data System (ADS)

    García-Pareja, S.; Vilches, M.; Lallena, A. M.

    2010-01-01

    The Monte Carlo simulation of clinical electron linear accelerators requires large computation times to achieve the level of uncertainty required for radiotherapy. In this context, variance reduction techniques play a fundamental role in the reduction of this computational time. Here we describe the use of the ant colony method to control the application of two variance reduction techniques: Splitting and Russian roulette. The approach can be applied to any accelerator in a straightforward way and permits the increasing of the efficiency of the simulation by a factor larger than 50.

  4. Variance Reduction Factor of Nuclear Data for Integral Neutronics Parameters

    SciTech Connect

    Chiba, G. Tsuji, M.; Narabayashi, T.

    2015-01-15

    We propose a new quantity, a variance reduction factor, to identify nuclear data for which further improvements are required to reduce uncertainties of target integral neutronics parameters. Important energy ranges can be also identified with this variance reduction factor. Variance reduction factors are calculated for several integral neutronics parameters. The usefulness of the variance reduction factors is demonstrated.

  5. Variance Design and Air Pollution Control

    ERIC Educational Resources Information Center

    Ferrar, Terry A.; Brownstein, Alan B.

    1975-01-01

    Air pollution control authorities were forced to relax air quality standards during the winter of 1972 by granting variances. This paper examines the institutional characteristics of these variance policies from an economic incentive standpoint, sets up desirable structural criteria for institutional design and arrives at policy guidelines for…

  6. A multicomb variance reduction scheme for Monte Carlo semiconductor simulators

    SciTech Connect

    Gray, M.G.; Booth, T.E.; Kwan, T.J.T.; Snell, C.M.

    1998-04-01

    The authors adapt a multicomb variance reduction technique used in neutral particle transport to Monte Carlo microelectronic device modeling. They implement the method in a two-dimensional (2-D) MOSFET device simulator and demonstrate its effectiveness in the study of hot electron effects. The simulations show that the statistical variance of hot electrons is significantly reduced with minimal computational cost. The method is efficient, versatile, and easy to implement in existing device simulators.

  7. Monte Carlo variance reduction approaches for non-Boltzmann tallies

    SciTech Connect

    Booth, T.E.

    1992-12-01

    Quantities that depend on the collective effects of groups of particles cannot be obtained from the standard Boltzmann transport equation. Monte Carlo estimates of these quantities are called non-Boltzmann tallies and have become increasingly important recently. Standard Monte Carlo variance reduction techniques were designed for tallies based on individual particles rather than groups of particles. Experience with non-Boltzmann tallies and analog Monte Carlo has demonstrated the severe limitations of analog Monte Carlo for many non-Boltzmann tallies. In fact, many calculations absolutely require variance reduction methods to achieve practical computation times. Three different approaches to variance reduction for non-Boltzmann tallies are described and shown to be unbiased. The advantages and disadvantages of each of the approaches are discussed.

  8. Variance reduction methods applied to deep-penetration problems

    SciTech Connect

    Cramer, S.N.

    1984-01-01

    All deep-penetration Monte Carlo calculations require variance reduction methods. Before beginning with a detailed approach to these methods, several general comments concerning deep-penetration calculations by Monte Carlo, the associated variance reduction, and the similarities and differences of these with regard to non-deep-penetration problems will be addressed. The experienced practitioner of Monte Carlo methods will easily find exceptions to any of these generalities, but it is felt that these comments will aid the novice in understanding some of the basic ideas and nomenclature. Also, from a practical point of view, the discussions and developments presented are oriented toward use of the computer codes which are presented in segments of this Monte Carlo course.

  9. Monte Carlo calculation of specific absorbed fractions: variance reduction techniques

    NASA Astrophysics Data System (ADS)

    Díaz-Londoño, G.; García-Pareja, S.; Salvat, F.; Lallena, A. M.

    2015-04-01

    The purpose of the present work is to calculate specific absorbed fractions using variance reduction techniques and assess the effectiveness of these techniques in improving the efficiency (i.e. reducing the statistical uncertainties) of simulation results in cases where the distance between the source and the target organs is large and/or the target organ is small. The variance reduction techniques of interaction forcing and an ant colony algorithm, which drives the application of splitting and Russian roulette, were applied in Monte Carlo calculations performed with the code penelope for photons with energies from 30 keV to 2 MeV. In the simulations we used a mathematical phantom derived from the well-known MIRD-type adult phantom. The thyroid gland was assumed to be the source organ and urinary bladder, testicles, uterus and ovaries were considered as target organs. Simulations were performed, for each target organ and for photons with different energies, using these variance reduction techniques, all run on the same processor and during a CPU time of 1.5 · 105 s. For energies above 100 keV both interaction forcing and the ant colony method allowed reaching relative uncertainties of the average absorbed dose in the target organs below 4% in all studied cases. When these two techniques were used together, the uncertainty was further reduced, by a factor of 0.5 or less. For photons with energies below 100 keV, an adapted initialization of the ant colony algorithm was required. By using interaction forcing and the ant colony algorithm, realistic values of the specific absorbed fractions can be obtained with relative uncertainties small enough to permit discriminating among simulations performed with different Monte Carlo codes and phantoms. The methodology described in the present work can be employed to calculate specific absorbed fractions for arbitrary arrangements, i.e. energy spectrum of primary radiation, phantom model and source and target organs.

  10. Fringe biasing: A variance reduction technique for optically thick meshes

    SciTech Connect

    Smedley-Stevenson, R. P.

    2013-07-01

    Fringe biasing is a stratified sampling scheme applicable to Monte Carlo thermal radiation transport codes. The thermal emission source in optically thick cells is partitioned into separate contributions from the cell interiors (where the likelihood of the particles escaping the cells is virtually zero) and the 'fringe' regions close to the cell boundaries. Thermal emission in the cell interiors can now be modelled with fewer particles, the remaining particles being concentrated in the fringes so that they are more likely to contribute to the energy exchange between cells. Unlike other techniques for improving the efficiency in optically thick regions (such as random walk and discrete diffusion treatments), fringe biasing has the benefit of simplicity, as the associated changes are restricted to the sourcing routines with the particle tracking routines being unaffected. This paper presents an analysis of the potential for variance reduction achieved from employing the fringe biasing technique. The aim of this analysis is to guide the implementation of this technique in Monte Carlo thermal radiation codes, specifically in order to aid the choice of the fringe width and the proportion of particles allocated to the fringe (which are interrelated) in multi-dimensional simulations, and to confirm that the significant levels of variance reduction achieved in simulations can be understood by studying the behaviour for simple test cases. The variance reduction properties are studied for a single cell in a slab geometry purely absorbing medium, investigating the accuracy of the scalar flux and current tallies on one of the interfaces with the surrounding medium. (authors)

  11. AVATAR -- Automatic variance reduction in Monte Carlo calculations

    SciTech Connect

    Van Riper, K.A.; Urbatsch, T.J.; Soran, P.D.

    1997-05-01

    AVATAR{trademark} (Automatic Variance And Time of Analysis Reduction), accessed through the graphical user interface application, Justine{trademark}, is a superset of MCNP{trademark} that automatically invokes THREEDANT{trademark} for a three-dimensional deterministic adjoint calculation on a mesh independent of the Monte Carlo geometry, calculates weight windows, and runs MCNP. Computational efficiency increases by a factor of 2 to 5 for a three-detector oil well logging tool model. Human efficiency increases dramatically, since AVATAR eliminates the need for deep intuition and hours of tedious handwork.

  12. A comparison of variance reduction techniques for radar simulation

    NASA Astrophysics Data System (ADS)

    Divito, A.; Galati, G.; Iovino, D.

    Importance sampling and extreme value technique (EVT) and its generalization (G-EVT) were compared as to reduction of the variance of radar simulation estimates. Importance sampling has a greater potential for including a priori information in the simulation experiment, and subsequently to reduce the estimation errors. This feature is paid for by a lack of generality of the simulation procedure. The EVT technique is only valid when a probability tail should be estimated (false alarm problems) and requires, as the only a priori information, that the considered variate belongs to the exponential class. The G-EVT introducing a shape parameter to be estimated (when unknown), allows smaller estimation error to be attained than EVT. The G-EVT and, to a greater extent, the EVT, lead to a straightforward and general simulation procedure for probability tails estimations.

  13. Improving computational efficiency of Monte Carlo simulations with variance reduction

    SciTech Connect

    Turner, A.

    2013-07-01

    CCFE perform Monte-Carlo transport simulations on large and complex tokamak models such as ITER. Such simulations are challenging since streaming and deep penetration effects are equally important. In order to make such simulations tractable, both variance reduction (VR) techniques and parallel computing are used. It has been found that the application of VR techniques in such models significantly reduces the efficiency of parallel computation due to 'long histories'. VR in MCNP can be accomplished using energy-dependent weight windows. The weight window represents an 'average behaviour' of particles, and large deviations in the arriving weight of a particle give rise to extreme amounts of splitting being performed and a long history. When running on parallel clusters, a long history can have a detrimental effect on the parallel efficiency - if one process is computing the long history, the other CPUs complete their batch of histories and wait idle. Furthermore some long histories have been found to be effectively intractable. To combat this effect, CCFE has developed an adaptation of MCNP which dynamically adjusts the WW where a large weight deviation is encountered. The method effectively 'de-optimises' the WW, reducing the VR performance but this is offset by a significant increase in parallel efficiency. Testing with a simple geometry has shown the method does not bias the result. This 'long history method' has enabled CCFE to significantly improve the performance of MCNP calculations for ITER on parallel clusters, and will be beneficial for any geometry combining streaming and deep penetration effects. (authors)

  14. Variance reduction in Monte Carlo analysis of rarefied gas diffusion.

    NASA Technical Reports Server (NTRS)

    Perlmutter, M.

    1972-01-01

    The problem of rarefied diffusion between parallel walls is solved using the Monte Carlo method. The diffusing molecules are evaporated or emitted from one of the two parallel walls and diffuse through another molecular species. The Monte Carlo analysis treats the diffusing molecule as undergoing a Markov random walk, and the local macroscopic properties are found as the expected value of the random variable, the random walk payoff. By biasing the transition probabilities and changing the collision payoffs, the expected Markov walk payoff is retained but its variance is reduced so that the Monte Carlo result has a much smaller error.

  15. Variance reduction in Monte Carlo analysis of rarefied gas diffusion

    NASA Technical Reports Server (NTRS)

    Perlmutter, M.

    1972-01-01

    The present analysis uses the Monte Carlo method to solve the problem of rarefied diffusion between parallel walls. The diffusing molecules are evaporated or emitted from one of two parallel walls and diffused through another molecular species. The analysis treats the diffusing molecule as undergoing a Markov random walk and the local macroscopic properties are found as the expected value of the random variable, the random walk payoff. By biasing the transition probabilities and changing the collision payoffs the expected Markov walk payoff is retained but its variance is reduced so that the M. C. result has a much smaller error.

  16. Irreversible Langevin samplers and variance reduction: a large deviations approach

    NASA Astrophysics Data System (ADS)

    Rey-Bellet, Luc; Spiliopoulos, Konstantinos

    2015-07-01

    In order to sample from a given target distribution (often of Gibbs type), the Monte Carlo Markov chain method consists of constructing an ergodic Markov process whose invariant measure is the target distribution. By sampling the Markov process one can then compute, approximately, expectations of observables with respect to the target distribution. Often the Markov processes used in practice are time-reversible (i.e. they satisfy detailed balance), but our main goal here is to assess and quantify how the addition of a non-reversible part to the process can be used to improve the sampling properties. We focus on the diffusion setting (overdamped Langevin equations) where the drift consists of a gradient vector field as well as another drift which breaks the reversibility of the process but is chosen to preserve the Gibbs measure. In this paper we use the large deviation rate function for the empirical measure as a tool to analyze the speed of convergence to the invariant measure. We show that the addition of an irreversible drift leads to a larger rate function and it strictly improves the speed of convergence of ergodic average for (generic smooth) observables. We also deduce from this result that the asymptotic variance decreases under the addition of the irreversible drift and we give an explicit characterization of the observables whose variance is not reduced reduced, in terms of a nonlinear Poisson equation. Our theoretical results are illustrated and supplemented by numerical simulations.

  17. Application of variance reduction techniques in Monte Carlo simulation of clinical electron linear accelerator

    NASA Astrophysics Data System (ADS)

    Zoubair, M.; El Bardouni, T.; El Gonnouni, L.; Boulaich, Y.; El Bakkari, B.; El Younoussi, C.

    2012-01-01

    Computation time constitutes an important and a problematic parameter in Monte Carlo simulations, which is inversely proportional to the statistical errors so there comes the idea to use the variance reduction techniques. These techniques play an important role in reducing uncertainties and improving the statistical results. Several variance reduction techniques have been developed. The most known are Transport cutoffs, Interaction forcing, Bremsstrahlung splitting and Russian roulette. Also, the use of a phase space seems to be appropriate to reduce enormously the computing time. In this work, we applied these techniques on a linear accelerator (LINAC) using the MCNPX computer Monte Carlo code. This code gives a rich palette of variance reduction techniques. In this study we investigated various cards related to the variance reduction techniques provided by MCNPX. The parameters found in this study are warranted to be used efficiently in MCNPX code. Final calculations are performed in two steps that are related by a phase space. Results show that, comparatively to direct simulations (without neither variance-reduction nor phase space), the adopted method allows an improvement in the simulation efficiency by a factor greater than 700.

  18. Verification of the history-score moment equations for weight-window variance reduction

    SciTech Connect

    Solomon, Clell J; Sood, Avneet; Booth, Thomas E; Shultis, J. Kenneth

    2010-12-06

    The history-score moment equations that describe the moments of a Monte Carlo score distribution have been extended to weight-window variance reduction, The resulting equations have been solved deterministically to calculate the population variance of the Monte Carlo score distribution for a single tally, Results for one- and two-dimensional one-group problems are presented that predict the population variances to less than 1% deviation from the Monte Carlo for one-dimensional problems and between 1- 2% for two-dimensional problems,

  19. Variance reduction techniques for estimation of integrals over a set of branching trajectories

    NASA Astrophysics Data System (ADS)

    Tsvetkov, E. A.

    2014-02-01

    Monte Carlo variance reduction techniques within the supertrack approach are justified as applied to estimating non-Boltzmann tallies equal to the mean of a random variable defined on the set of all branching trajectories. For this purpose, a probability space is constructed on the set of all branching trajectories, and the unbiasedness of this method is proved by averaging over all trajectories. Variance reduction techniques, such as importance sampling, splitting, and Russian roulette, are discussed. A method is described for extending available codes based on the von Neumann-Ulam scheme in order to cover the supertrack approach.

  20. Reduction of variance in measurements of average metabolite concentration in anatomically-defined brain regions

    NASA Astrophysics Data System (ADS)

    Larsen, Ryan J.; Newman, Michael; Nikolaidis, Aki

    2016-11-01

    Multiple methods have been proposed for using Magnetic Resonance Spectroscopy Imaging (MRSI) to measure representative metabolite concentrations of anatomically-defined brain regions. Generally these methods require spectral analysis, quantitation of the signal, and reconciliation with anatomical brain regions. However, to simplify processing pipelines, it is practical to only include those corrections that significantly improve data quality. Of particular importance for cross-sectional studies is knowledge about how much each correction lowers the inter-subject variance of the measurement, thereby increasing statistical power. Here we use a data set of 72 subjects to calculate the reduction in inter-subject variance produced by several corrections that are commonly used to process MRSI data. Our results demonstrate that significant reductions of variance can be achieved by performing water scaling, accounting for tissue type, and integrating MRSI data over anatomical regions rather than simply assigning MRSI voxels with anatomical region labels.

  1. Automatic variance reduction for Monte Carlo simulations via the local importance function transform

    SciTech Connect

    Turner, S.A.

    1996-02-01

    The author derives a transformed transport problem that can be solved theoretically by analog Monte Carlo with zero variance. However, the Monte Carlo simulation of this transformed problem cannot be implemented in practice, so he develops a method for approximating it. The approximation to the zero variance method consists of replacing the continuous adjoint transport solution in the transformed transport problem by a piecewise continuous approximation containing local biasing parameters obtained from a deterministic calculation. He uses the transport and collision processes of the transformed problem to bias distance-to-collision and selection of post-collision energy groups and trajectories in a traditional Monte Carlo simulation of ``real`` particles. He refers to the resulting variance reduction method as the Local Importance Function Transform (LIFI) method. He demonstrates the efficiency of the LIFT method for several 3-D, linearly anisotropic scattering, one-group, and multigroup problems. In these problems the LIFT method is shown to be more efficient than the AVATAR scheme, which is one of the best variance reduction techniques currently available in a state-of-the-art Monte Carlo code. For most of the problems considered, the LIFT method produces higher figures of merit than AVATAR, even when the LIFT method is used as a ``black box``. There are some problems that cause trouble for most variance reduction techniques, and the LIFT method is no exception. For example, the author demonstrates that problems with voids, or low density regions, can cause a reduction in the efficiency of the LIFT method. However, the LIFT method still performs better than survival biasing and AVATAR in these difficult cases.

  2. Discrete velocity computations with stochastic variance reduction of the Boltzmann equation for gas mixtures

    SciTech Connect

    Clarke, Peter; Varghese, Philip; Goldstein, David

    2014-12-09

    We extend a variance reduced discrete velocity method developed at UT Austin [1, 2] to gas mixtures with large mass ratios and flows with trace species. The mixture is stored as a collection of independent velocity distribution functions, each with a unique grid in velocity space. Different collision types (A-A, A-B, B-B, etc.) are treated independently, and the variance reduction scheme is formulated with different equilibrium functions for each separate collision type. The individual treatment of species enables increased focus on species important to the physics of the flow, even if the important species are present in trace amounts. The method is verified through comparisons to Direct Simulation Monte Carlo computations and the computational workload per time step is investigated for the variance reduced method.

  3. A local'' exponential transform method for global variance reduction in Monte Carlo transport problems

    SciTech Connect

    Baker, R.S. ); Larsen, E.W. . Dept. of Nuclear Engineering)

    1992-01-01

    Numerous variance reduction techniques, such as splitting/Russian roulette, weight windows, and the exponential transform exist for improving the efficiency of Monte Carlo transport calculations. Typically, however, these methods, while reducing the variance in the problem area of interest tend to increase the variance in other, presumably less important, regions. As such, these methods tend to be not as effective in Monte Carlo calculations which require the minimization of the variance everywhere. Recently, Local'' Exponential Transform (LET) methods have been developed as a means of approximating the zero-variance solution. A numerical solution to the adjoint diffusion equation is used, along with an exponential representation of the adjoint flux in each cell, to determine local'' biasing parameters. These parameters are then used to bias the forward Monte Carlo transport calculation in a manner similar to the conventional exponential transform, but such that the transform parameters are now local in space and energy, not global. Results have shown that the Local Exponential Transform often offers a significant improvement over conventional geometry splitting/Russian roulette with weight windows. Since the biasing parameters for the Local Exponential Transform were determined from a low-order solution to the adjoint transport problem, the LET has been applied in problems where it was desirable to minimize the variance in a detector region. The purpose of this paper is to show that by basing the LET method upon a low-order solution to the forward transport problem, one can instead obtain biasing parameters which will minimize the maximum variance in a Monte Carlo transport calculation.

  4. A ``local`` exponential transform method for global variance reduction in Monte Carlo transport problems

    SciTech Connect

    Baker, R.S.; Larsen, E.W.

    1992-08-01

    Numerous variance reduction techniques, such as splitting/Russian roulette, weight windows, and the exponential transform exist for improving the efficiency of Monte Carlo transport calculations. Typically, however, these methods, while reducing the variance in the problem area of interest tend to increase the variance in other, presumably less important, regions. As such, these methods tend to be not as effective in Monte Carlo calculations which require the minimization of the variance everywhere. Recently, ``Local`` Exponential Transform (LET) methods have been developed as a means of approximating the zero-variance solution. A numerical solution to the adjoint diffusion equation is used, along with an exponential representation of the adjoint flux in each cell, to determine ``local`` biasing parameters. These parameters are then used to bias the forward Monte Carlo transport calculation in a manner similar to the conventional exponential transform, but such that the transform parameters are now local in space and energy, not global. Results have shown that the Local Exponential Transform often offers a significant improvement over conventional geometry splitting/Russian roulette with weight windows. Since the biasing parameters for the Local Exponential Transform were determined from a low-order solution to the adjoint transport problem, the LET has been applied in problems where it was desirable to minimize the variance in a detector region. The purpose of this paper is to show that by basing the LET method upon a low-order solution to the forward transport problem, one can instead obtain biasing parameters which will minimize the maximum variance in a Monte Carlo transport calculation.

  5. ADVANTG 3.0.1: AutomateD VAriaNce reducTion Generator

    2015-08-17

    Version 00 ADVANTG is an automated tool for generating variance reduction parameters for fixed-source continuous-energy Monte Carlo simulations with MCNP5 V1.60 (CCC-810, not included in this distribution) based on approximate 3-D multigroup discrete ordinates adjoint transport solutions generated by Denovo (included in this distribution). The variance reduction parameters generated by ADVANTG consist of space and energy-dependent weight-window bounds and biased source distributions, which are output in formats that can be directly used with unmodified versionsmore » of MCNP5. ADVANTG has been applied to neutron, photon, and coupled neutron-photon simulations of real-world radiation detection and shielding scenarios. ADVANTG is compatible with all MCNP5 geometry features and can be used to accelerate cell tallies (F4, F6, F8), surface tallies (F1 and F2), point-detector tallies (F5), and Cartesian mesh tallies (FMESH).« less

  6. ADVANTG 3.0.1: AutomateD VAriaNce reducTion Generator

    SciTech Connect

    2015-08-17

    Version 00 ADVANTG is an automated tool for generating variance reduction parameters for fixed-source continuous-energy Monte Carlo simulations with MCNP5 V1.60 (CCC-810, not included in this distribution) based on approximate 3-D multigroup discrete ordinates adjoint transport solutions generated by Denovo (included in this distribution). The variance reduction parameters generated by ADVANTG consist of space and energy-dependent weight-window bounds and biased source distributions, which are output in formats that can be directly used with unmodified versions of MCNP5. ADVANTG has been applied to neutron, photon, and coupled neutron-photon simulations of real-world radiation detection and shielding scenarios. ADVANTG is compatible with all MCNP5 geometry features and can be used to accelerate cell tallies (F4, F6, F8), surface tallies (F1 and F2), point-detector tallies (F5), and Cartesian mesh tallies (FMESH).

  7. A model and variance reduction method for computing statistical outputs of stochastic elliptic partial differential equations

    SciTech Connect

    Vidal-Codina, F.; Nguyen, N.C.; Giles, M.B.; Peraire, J.

    2015-09-15

    We present a model and variance reduction method for the fast and reliable computation of statistical outputs of stochastic elliptic partial differential equations. Our method consists of three main ingredients: (1) the hybridizable discontinuous Galerkin (HDG) discretization of elliptic partial differential equations (PDEs), which allows us to obtain high-order accurate solutions of the governing PDE; (2) the reduced basis method for a new HDG discretization of the underlying PDE to enable real-time solution of the parameterized PDE in the presence of stochastic parameters; and (3) a multilevel variance reduction method that exploits the statistical correlation among the different reduced basis approximations and the high-fidelity HDG discretization to accelerate the convergence of the Monte Carlo simulations. The multilevel variance reduction method provides efficient computation of the statistical outputs by shifting most of the computational burden from the high-fidelity HDG approximation to the reduced basis approximations. Furthermore, we develop a posteriori error estimates for our approximations of the statistical outputs. Based on these error estimates, we propose an algorithm for optimally choosing both the dimensions of the reduced basis approximations and the sizes of Monte Carlo samples to achieve a given error tolerance. We provide numerical examples to demonstrate the performance of the proposed method.

  8. Importance sampling variance reduction for the Fokker-Planck rarefied gas particle method

    NASA Astrophysics Data System (ADS)

    Collyer, B. S.; Connaughton, C.; Lockerby, D. A.

    2016-11-01

    The Fokker-Planck approximation to the Boltzmann equation, solved numerically by stochastic particle schemes, is used to provide estimates for rarefied gas flows. This paper presents a variance reduction technique for a stochastic particle method that is able to greatly reduce the uncertainty of the estimated flow fields when the characteristic speed of the flow is small in comparison to the thermal velocity of the gas. The method relies on importance sampling, requiring minimal changes to the basic stochastic particle scheme. We test the importance sampling scheme on a homogeneous relaxation, planar Couette flow and a lid-driven-cavity flow, and find that our method is able to greatly reduce the noise of estimated quantities. Significantly, we find that as the characteristic speed of the flow decreases, the variance of the noisy estimators becomes independent of the characteristic speed.

  9. Output Power Control of Wind Turbine Generator by Pitch Angle Control using Minimum Variance Control

    NASA Astrophysics Data System (ADS)

    Senjyu, Tomonobu; Sakamoto, Ryosei; Urasaki, Naomitsu; Higa, Hiroki; Uezato, Katsumi; Funabashi, Toshihisa

    In recent years, there have been problems such as exhaustion of fossil fuels, e. g., coal and oil, and environmental pollution resulting from consumption. Effective utilization of renewable energies such as wind energy is expected instead of the fossil fuel. Wind energy is not constant and windmill output is proportional to the cube of wind speed, which cause the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuating components, there is a method to control pitch angle of blades of the windmill. In this paper, output power leveling of wind turbine generator by pitch angle control using an adaptive control is proposed. A self-tuning regulator is used in adaptive control. The control input is determined by the minimum variance control. It is possible to compensate control input to alleviate generating power fluctuation with using proposed controller. The simulation results with using actual detailed model for wind power system show effectiveness of the proposed controller.

  10. Variance reduction for Fokker–Planck based particle Monte Carlo schemes

    SciTech Connect

    Gorji, M. Hossein Andric, Nemanja; Jenny, Patrick

    2015-08-15

    Recently, Fokker–Planck based particle Monte Carlo schemes have been proposed and evaluated for simulations of rarefied gas flows [1–3]. In this paper, the variance reduction for particle Monte Carlo simulations based on the Fokker–Planck model is considered. First, deviational based schemes were derived and reviewed, and it is shown that these deviational methods are not appropriate for practical Fokker–Planck based rarefied gas flow simulations. This is due to the fact that the deviational schemes considered in this study lead either to instabilities in the case of two-weight methods or to large statistical errors if the direct sampling method is applied. Motivated by this conclusion, we developed a novel scheme based on correlated stochastic processes. The main idea here is to synthesize an additional stochastic process with a known solution, which is simultaneously solved together with the main one. By correlating the two processes, the statistical errors can dramatically be reduced; especially for low Mach numbers. To assess the methods, homogeneous relaxation, planar Couette and lid-driven cavity flows were considered. For these test cases, it could be demonstrated that variance reduction based on parallel processes is very robust and effective.

  11. Variance reduction for Fokker-Planck based particle Monte Carlo schemes

    NASA Astrophysics Data System (ADS)

    Gorji, M. Hossein; Andric, Nemanja; Jenny, Patrick

    2015-08-01

    Recently, Fokker-Planck based particle Monte Carlo schemes have been proposed and evaluated for simulations of rarefied gas flows [1-3]. In this paper, the variance reduction for particle Monte Carlo simulations based on the Fokker-Planck model is considered. First, deviational based schemes were derived and reviewed, and it is shown that these deviational methods are not appropriate for practical Fokker-Planck based rarefied gas flow simulations. This is due to the fact that the deviational schemes considered in this study lead either to instabilities in the case of two-weight methods or to large statistical errors if the direct sampling method is applied. Motivated by this conclusion, we developed a novel scheme based on correlated stochastic processes. The main idea here is to synthesize an additional stochastic process with a known solution, which is simultaneously solved together with the main one. By correlating the two processes, the statistical errors can dramatically be reduced; especially for low Mach numbers. To assess the methods, homogeneous relaxation, planar Couette and lid-driven cavity flows were considered. For these test cases, it could be demonstrated that variance reduction based on parallel processes is very robust and effective.

  12. Models of Postural Control: Shared Variance in Joint and COM Motions.

    PubMed

    Kilby, Melissa C; Molenaar, Peter C M; Newell, Karl M

    2015-01-01

    This paper investigated the organization of the postural control system in human upright stance. To this aim the shared variance between joint and 3D total body center of mass (COM) motions was analyzed using multivariate canonical correlation analysis (CCA). The CCA was performed as a function of established models of postural control that varied in their joint degrees of freedom (DOF), namely, an inverted pendulum ankle model (2DOF), ankle-hip model (4DOF), ankle-knee-hip model (5DOF), and ankle-knee-hip-neck model (7DOF). Healthy young adults performed various postural tasks (two-leg and one-leg quiet stances, voluntary AP and ML sway) on a foam and rigid surface of support. Based on CCA model selection procedures, the amount of shared variance between joint and 3D COM motions and the cross-loading patterns we provide direct evidence of the contribution of multi-DOF postural control mechanisms to human balance. The direct model fitting of CCA showed that incrementing the DOFs in the model through to 7DOF was associated with progressively enhanced shared variance with COM motion. In the 7DOF model, the first canonical function revealed more active involvement of all joints during more challenging one leg stances and dynamic posture tasks. Furthermore, the shared variance was enhanced during the dynamic posture conditions, consistent with a reduction of dimension. This set of outcomes shows directly the degeneracy of multivariate joint regulation in postural control that is influenced by stance and surface of support conditions.

  13. MCNPX--PoliMi Variance Reduction Techniques for Simulating Neutron Scintillation Detector Response

    NASA Astrophysics Data System (ADS)

    Prasad, Shikha

    Scintillation detectors have emerged as a viable He-3 replacement technology in the field of nuclear nonproliferation and safeguards. The scintillation light produced in the detectors is dependent on the energy deposited and the nucleus with which the interaction occurs. For neutrons interacting with hydrogen in organic liquid scintillation detectors, the energy-to-light conversion process is nonlinear. MCNPX-PoliMi is a Monte Carlo Code that has been used for simulating this detailed scintillation physics; however, until now, simulations have only been done in analog mode. Analog Monte Carlo simulations can take long times to run, especially in the presence of shielding and large source-detector distances, as in the case of typical nonproliferation problems. In this thesis, two nonanalog approaches to speed up MCNPX-PoliMi simulations of neutron scintillation detector response have been studied. In the first approach, a response matrix method (RMM) is used to efficiently calculate neutron pulse height distributions (PHDs). This method combines the neutron current incident on the detector face with an MCNPX-PoliMi-calculated response matrix to generate PHDs. The PHD calculations and their associated uncertainty are compared for a polyethylene-shielded and lead-shielded Cf-252 source for three different techniques: fully analog MCNPX-PoliMi, the RMM, and the RMM with source biasing. The RMM with source biasing reduces computation time or increases the figure-of-merit on an average by a factor of 600 for polyethylene and 300 for lead shielding (when compared to the fully analog calculation). The simulated neutron PHDs show good agreement with the laboratory measurements, thereby validating the RMM. In the second approach, MCNPX-PoliMi simulations are performed with the aid of variance reduction techniques. This is done by separating the analog and nonanalog components of the simulations. Inside the detector region, where scintillation light is produced, no variance

  14. Variance reduction techniques for fast Monte Carlo CBCT scatter correction calculations

    NASA Astrophysics Data System (ADS)

    Mainegra-Hing, Ernesto; Kawrakow, Iwan

    2010-08-01

    Several variance reduction techniques improving the efficiency of the Monte Carlo estimation of the scatter contribution to a cone beam computed tomography (CBCT) scan were implemented in {\\tt egs\\_cbct}, an EGSnrc-based application for CBCT-related calculations. The largest impact on the efficiency comes from the splitting + Russian Roulette techniques which are described in detail. The fixed splitting technique is outperformed by both the position-dependent importance splitting (PDIS) and the region-dependent importance splitting (RDIS). The superiority of PDIS over RDIS observed for a water phantom with bone inserts is not observed when applying these techniques to a more realistic human chest phantom. A maximum efficiency improvement of several orders of magnitude over an analog calculation is obtained. A scatter calculation combining the reported efficiency gain with a smoothing algorithm is already in the proximity of being of practical use if a medium size computer cluster is available.

  15. A combined approach of variance-reduction techniques for the efficient Monte Carlo simulation of linacs

    NASA Astrophysics Data System (ADS)

    Rodriguez, M.; Sempau, J.; Brualla, L.

    2012-05-01

    A method based on a combination of the variance-reduction techniques of particle splitting and Russian roulette is presented. This method improves the efficiency of radiation transport through linear accelerator geometries simulated with the Monte Carlo method. The method named as ‘splitting-roulette’ was implemented on the Monte Carlo code \\scriptsize{{PENELOPE}} and tested on an Elekta linac, although it is general enough to be implemented on any other general-purpose Monte Carlo radiation transport code and linac geometry. Splitting-roulette uses any of the following two modes of splitting: simple splitting and ‘selective splitting’. Selective splitting is a new splitting mode based on the angular distribution of bremsstrahlung photons implemented in the Monte Carlo code \\scriptsize{{PENELOPE}}. Splitting-roulette improves the simulation efficiency of an Elekta SL25 linac by a factor of 45.

  16. Attention-Induced Variance and Noise Correlation Reduction in Macaque V1 Is Mediated by NMDA Receptors

    PubMed Central

    Herrero, Jose L.; Gieselmann, Marc A.; Sanayei, Mehdi; Thiele, Alexander

    2013-01-01

    Summary Attention improves perception by affecting different aspects of the neuronal code. It enhances firing rates, it reduces firing rate variability and noise correlations of neurons, and it alters the strength of oscillatory activity. Attention-induced rate enhancement in striate cortex requires cholinergic mechanisms. The neuropharmacological mechanisms responsible for attention-induced variance and noise correlation reduction or those supporting changes in oscillatory activity are unknown. We show that ionotropic glutamatergic receptor activation is required for attention-induced rate variance, noise correlation, and LFP gamma power reduction in macaque V1, but not for attention-induced rate modulations. NMDA receptors mediate attention-induced variance reduction and attention-induced noise correlation reduction. Our results demonstrate that attention improves sensory processing by a variety of mechanisms that are dissociable at the receptor level. PMID:23719166

  17. Investigation of variance reduction techniques for Monte Carlo photon dose calculation using XVMC

    NASA Astrophysics Data System (ADS)

    Kawrakow, Iwan; Fippel, Matthias

    2000-08-01

    Several variance reduction techniques, such as photon splitting, electron history repetition, Russian roulette and the use of quasi-random numbers are investigated and shown to significantly improve the efficiency of the recently developed XVMC Monte Carlo code for photon beams in radiation therapy. It is demonstrated that it is possible to further improve the efficiency by optimizing transport parameters such as electron energy cut-off, maximum electron energy step size, photon energy cut-off and a cut-off for kerma approximation, without loss of calculation accuracy. These methods increase the efficiency by a factor of up to 10 compared with the initial XVMC ray-tracing technique or a factor of 50 to 80 compared with EGS4/PRESTA. Therefore, a common treatment plan (6 MV photons, 10×10 cm2 field size, 5 mm voxel resolution, 1% statistical uncertainty) can be calculated within 7 min using a single CPU 500 MHz personal computer. If the requirement on the statistical uncertainty is relaxed to 2%, the calculation time will be less than 2 min. In addition, a technique is presented which allows for the quantitative comparison of Monte Carlo calculated dose distributions and the separation of systematic and statistical errors. Employing this technique it is shown that XVMC calculations agree with EGSnrc on a sub-per cent level for simulations in the energy and material range of interest for radiation therapy.

  18. Implementation of hybrid variance reduction methods in a multi group Monte Carlo code for deep shielding problems

    SciTech Connect

    Somasundaram, E.; Palmer, T. S.

    2013-07-01

    In this paper, the work that has been done to implement variance reduction techniques in a three dimensional, multi group Monte Carlo code - Tortilla, that works within the frame work of the commercial deterministic code - Attila, is presented. This project is aimed to develop an integrated Hybrid code that seamlessly takes advantage of the deterministic and Monte Carlo methods for deep shielding radiation detection problems. Tortilla takes advantage of Attila's features for generating the geometric mesh, cross section library and source definitions. Tortilla can also read importance functions (like adjoint scalar flux) generated from deterministic calculations performed in Attila and use them to employ variance reduction schemes in the Monte Carlo simulation. The variance reduction techniques that are implemented in Tortilla are based on the CADIS (Consistent Adjoint Driven Importance Sampling) method and the LIFT (Local Importance Function Transform) method. These methods make use of the results from an adjoint deterministic calculation to bias the particle transport using techniques like source biasing, survival biasing, transport biasing and weight windows. The results obtained so far and the challenges faced in implementing the variance reduction techniques are reported here. (authors)

  19. Control of quality of fluidization in a tall bed using variance of pressure fluctuations

    SciTech Connect

    Lee, P.L.; Chong, Y.O.; Leung, L.S.

    1985-01-01

    A quantitative relation was established experimentally between excess gas flow above minimum fluidization and the variance of differential pressure fluctuations in a bed. The variance was used as part of a computer control scheme to maintain the quality of fluidization in a tall bed constant. This was achieved by controlling the amount of gas bled from the fluidized bed at different bed levels. Successful demonstration of the control strategy in a 200mm diameter 2.7m tall fluidized bed is described.

  20. PWR Facility Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology

    SciTech Connect

    Blakeman, Edward D; Peplow, Douglas E.; Wagner, John C; Murphy, Brian D; Mueller, Don

    2007-09-01

    The feasibility of modeling a pressurized-water-reactor (PWR) facility and calculating dose rates at all locations within the containment and adjoining structures using MCNP5 with mesh tallies is presented. Calculations of dose rates resulting from neutron and photon sources from the reactor (operating and shut down for various periods) and the spent fuel pool, as well as for the photon source from the primary coolant loop, were all of interest. Identification of the PWR facility, development of the MCNP-based model and automation of the run process, calculation of the various sources, and development of methods for visually examining mesh tally files and extracting dose rates were all a significant part of the project. Advanced variance reduction, which was required because of the size of the model and the large amount of shielding, was performed via the CADIS/ADVANTG approach. This methodology uses an automatically generated three-dimensional discrete ordinates model to calculate adjoint fluxes from which MCNP weight windows and source bias parameters are generated. Investigative calculations were performed using a simple block model and a simplified full-scale model of the PWR containment, in which the adjoint source was placed in various regions. In general, it was shown that placement of the adjoint source on the periphery of the model provided adequate results for regions reasonably close to the source (e.g., within the containment structure for the reactor source). A modification to the CADIS/ADVANTG methodology was also studied in which a global adjoint source is weighted by the reciprocal of the dose response calculated by an earlier forward discrete ordinates calculation. This method showed improved results over those using the standard CADIS/ADVANTG approach, and its further investigation is recommended for future efforts.

  1. Optimization under uncertainty: Adaptive variance reduction, adaptive metamodeling, and investigation of robustness measures

    NASA Astrophysics Data System (ADS)

    Medina, Juan Camilo

    This dissertation offers computational and theoretical advances for optimization under uncertainty problems that utilize a probabilistic framework for addressing such uncertainties, and adopt a probabilistic performance as objective function. Emphasis is placed on applications that involve potentially complex numerical and probability models. A generalized approach is adopted, treating the system model as a "black-box" and relying on stochastic simulation for evaluating the probabilistic performance. This approach can impose, though, an elevated computational cost, and two of the advances offered in this dissertation aim at decreasing the computational burden associated with stochastic simulation when integrated with optimization applications. The first one develops an adaptive implementation of importance sampling (a popular variance reduction technique) by sharing information across the iterations of the numerical optimization algorithm. The system model evaluations from the current iteration are utilized to formulate importance sampling densities for subsequent iterations with only a small additional computational effort. The characteristics of these densities as well as the specific model parameters these densities span are explicitly optimized. The second advancement focuses on adaptive tuning of a kriging metamodel to replace the computationally intensive system model. A novel implementation is considered, establishing a metamodel with respect to both the uncertain model parameters as well as the design variables, offering significant computational savings. Additionally, the adaptive selection of certain characteristics of the metamodel, such as support points or order of basis functions, is considered by utilizing readily available information from the previous iteration of the optimization algorithm. The third advancement extends to a different application and considers the assessment of the appropriateness of different candidate robust designs. A novel

  2. Does Public Sector Control Reduce Variance in School Quality?

    ERIC Educational Resources Information Center

    Pritchett, Lant; Viarengo, Martina

    2015-01-01

    Does the government control of school systems facilitate equality in school quality? Whether centralized or localized control produces more equality depends not only on what "could" happen in principle, but also on what does happen in practice. We use the Programme for International Student Assessment (PISA) database to examine the…

  3. Joule Heating Food Process Using Minimum Variance Control

    NASA Astrophysics Data System (ADS)

    Naganawa, Akihiro; Ito, Hiroki; Akiyama, Yoshinobu

    On a food heating process, a heat transmission system has been used widely. Recently, the Joule heating system has been received keen attentions as a sophisticated heating system because of non-scorching and cleanness. This system is based on a Joule heat phenomenon, that is, an electric resistance of food generates the heat, and then heats up food itself. However, control performance for the Joule heating system is not known well. In this paper, experimental results of the heating control for NaCl solution and soymilk are reported as basic verification of the Joule heating method.

  4. Variance reduction through robust design of boundary conditions for stochastic hyperbolic systems of equations

    SciTech Connect

    Nordström, Jan Wahlsten, Markus

    2015-02-01

    We consider a hyperbolic system with uncertainty in the boundary and initial data. Our aim is to show that different boundary conditions give different convergence rates of the variance of the solution. This means that we can with the same knowledge of data get a more or less accurate description of the uncertainty in the solution. A variety of boundary conditions are compared and both analytical and numerical estimates of the variance of the solution are presented. As an application, we study the effect of this technique on Maxwell's equations as well as on a subsonic outflow boundary for the Euler equations.

  5. An automated variance reduction method for global Monte Carlo neutral particle transport problems

    NASA Astrophysics Data System (ADS)

    Cooper, Marc Andrew

    A method to automatically reduce the variance in global neutral particle Monte Carlo problems by using a weight window derived from a deterministic forward solution is presented. This method reduces a global measure of the variance of desired tallies and increases its associated figure of merit. Global deep penetration neutron transport problems present difficulties for analog Monte Carlo. When the scalar flux decreases by many orders of magnitude, so does the number of Monte Carlo particles. This can result in large statistical errors. In conjunction with survival biasing, a weight window is employed which uses splitting and Russian roulette to restrict the symbolic weights of Monte Carlo particles. By establishing a connection between the scalar flux and the weight window, two important concepts are demonstrated. First, such a weight window can be constructed from a deterministic solution of a forward transport problem. Also, the weight window will distribute Monte Carlo particles in such a way to minimize a measure of the global variance. For Implicit Monte Carlo solutions of radiative transfer problems, an inefficient distribution of Monte Carlo particles can result in large statistical errors in front of the Marshak wave and at its leading edge. Again, the global Monte Carlo method is used, which employs a time-dependent weight window derived from a forward deterministic solution. Here, the algorithm is modified to enhance the number of Monte Carlo particles in the wavefront. Simulations show that use of this time-dependent weight window significantly improves the Monte Carlo calculation.

  6. Fast variance reduction for steady-state simulation and sensitivity analysis of stochastic chemical systems using shadow function estimators

    SciTech Connect

    Milias-Argeitis, Andreas Khammash, Mustafa; Lygeros, John

    2014-07-14

    We address the problem of estimating steady-state quantities associated to systems of stochastic chemical kinetics. In most cases of interest, these systems are analytically intractable, and one has to resort to computational methods to estimate stationary values of cost functions. In this work, we introduce a novel variance reduction algorithm for stochastic chemical kinetics, inspired by related methods in queueing theory, in particular the use of shadow functions. Using two numerical examples, we demonstrate the efficiency of the method for the calculation of steady-state parametric sensitivities and evaluate its performance in comparison to other estimation methods.

  7. VR-BFDT: A variance reduction based binary fuzzy decision tree induction method for protein function prediction.

    PubMed

    Golzari, Fahimeh; Jalili, Saeed

    2015-07-21

    In protein function prediction (PFP) problem, the goal is to predict function of numerous well-sequenced known proteins whose function is not still known precisely. PFP is one of the special and complex problems in machine learning domain in which a protein (regarded as instance) may have more than one function simultaneously. Furthermore, the functions (regarded as classes) are dependent and also are organized in a hierarchical structure in the form of a tree or directed acyclic graph. One of the common learning methods proposed for solving this problem is decision trees in which, by partitioning data into sharp boundaries sets, small changes in the attribute values of a new instance may cause incorrect change in predicted label of the instance and finally misclassification. In this paper, a Variance Reduction based Binary Fuzzy Decision Tree (VR-BFDT) algorithm is proposed to predict functions of the proteins. This algorithm just fuzzifies the decision boundaries instead of converting the numeric attributes into fuzzy linguistic terms. It has the ability of assigning multiple functions to each protein simultaneously and preserves the hierarchy consistency between functional classes. It uses the label variance reduction as splitting criterion to select the best "attribute-value" at each node of the decision tree. The experimental results show that the overall performance of the proposed algorithm is promising.

  8. Advanced Variance Reduction for Global k-Eigenvalue Simulations in MCNP

    SciTech Connect

    Edward W. Larsen

    2008-06-01

    The "criticality" or k-eigenvalue of a nuclear system determines whether the system is critical (k=1), or the extent to which it is subcritical (k<1) or supercritical (k>1). Calculations of k are frequently performed at nuclear facilities to determine the criticality of nuclear reactor cores, spent nuclear fuel storage casks, and other fissile systems. These calculations can be expensive, and current Monte Carlo methods have certain well-known deficiencies. In this project, we have developed and tested a new "functional Monte Carlo" (FMC) method that overcomes several of these deficiencies. The current state-of-the-art Monte Carlo k-eigenvalue method estimates the fission source for a sequence of fission generations (cycles), during each of which M particles per cycle are processed. After a series of "inactive" cycles during which the fission source "converges," a series of "active" cycles are performed. For each active cycle, the eigenvalue and eigenfunction are estimated; after N >> 1 active cycles are performed, the results are averaged to obtain estimates of the eigenvalue and eigenfunction and their standard deviations. This method has several disadvantages: (i) the estimate of k depends on the number M of particles per cycle, (iii) for optically thick systems, the eigenfunction estimate may not converge due to undersampling of the fission source, and (iii) since the fission source in any cycle depends on the estimated fission source from the previous cycle (the fission sources in different cycles are correlated), the estimated variance in k is smaller than the real variance. For an acceptably large number M of particles per cycle, the estimate of k is nearly independent of M; this essentially takes care of item (i). Item (ii) can be addressed by taking M sufficiently large, but for optically thick systems a sufficiently large M can easily be unrealistic. Item (iii) cannot be accounted for by taking M or N sufficiently large; it is an inherent deficiency due

  9. Fast patient-specific Monte Carlo brachytherapy dose calculations via the correlated sampling variance reduction technique

    PubMed Central

    Sampson, Andrew; Le, Yi; Williamson, Jeffrey F.

    2012-01-01

    . On an AMD 1090T processor, computing times of 38 and 21 sec were required to achieve an average statistical uncertainty of 2% within the prostate (1 × 1 × 1 mm3) and breast (0.67 × 0.67 × 0.8 mm3) CTVs, respectively. Conclusions: CMC supports an additional average 38–60 fold improvement in average efficiency relative to conventional uncorrelated MC techniques, although some voxels experience no gain or even efficiency losses. However, for the two investigated case studies, the maximum variance within clinically significant structures was always reduced (on average by a factor of 6) in the therapeutic dose range generally. CMC takes only seconds to produce an accurate, high-resolution, low-uncertainly dose distribution for the low-energy PSB implants investigated in this study. PMID:22320816

  10. Risk-sensitivity and the mean-variance trade-off: decision making in sensorimotor control

    PubMed Central

    Nagengast, Arne J.; Braun, Daniel A.; Wolpert, Daniel M.

    2011-01-01

    Numerous psychophysical studies suggest that the sensorimotor system chooses actions that optimize the average cost associated with a movement. Recently, however, violations of this hypothesis have been reported in line with economic theories of decision-making that not only consider the mean payoff, but are also sensitive to risk, that is the variability of the payoff. Here, we examine the hypothesis that risk-sensitivity in sensorimotor control arises as a mean-variance trade-off in movement costs. We designed a motor task in which participants could choose between a sure motor action that resulted in a fixed amount of effort and a risky motor action that resulted in a variable amount of effort that could be either lower or higher than the fixed effort. By changing the mean effort of the risky action while experimentally fixing its variance, we determined indifference points at which participants chose equiprobably between the sure, fixed amount of effort option and the risky, variable effort option. Depending on whether participants accepted a variable effort with a mean that was higher, lower or equal to the fixed effort, they could be classified as risk-seeking, risk-averse or risk-neutral. Most subjects were risk-sensitive in our task consistent with a mean-variance trade-off in effort, thereby, underlining the importance of risk-sensitivity in computational models of sensorimotor control. PMID:21208966

  11. Robust control chart for change point detection of process variance in the presence of disturbances

    NASA Astrophysics Data System (ADS)

    Huat, Ng Kooi; Midi, Habshah

    2015-02-01

    A conventional control chart for detecting shifts in variance of a process is typically developed where in most circumstances the nominal value of variance is unknown and based upon one of the essential assumptions that the underlying distribution of the quality characteristic is normal. However, this is not always the case as it is fairly evident that the statistical estimates used for these charts are very sensitive to the occurrence of occasional outliers. This is for the reason that the robust control charts are put forward when the underlying normality assumption is not met, and served as a remedial measure to the problem of contamination in process data. Realizing that the existing approach, namely Biweight A pooled residuals method, appears to be resistance to localized disturbances but lack of efficiency when there are diffuse disturbances. To be concrete, diffuse disturbances are those that have equal change of being perturbed by any observation, while a localized disturbance will have effect on every member of a certain subsample or subsamples. Since the efficiency of estimators in the presence of disturbances can rely heavily upon whether the disturbances are distributed throughout the observations or concentrated in a few subsamples. Hence, to this end, in this paper we proposed a new robust MBAS control chart by means of subsample-based robust Modified Biweight A scale estimator in estimating the process standard deviation. It has strong resistance to both localized and diffuse disturbances as well as high efficiency when no disturbances are present. The performance of the proposed robust chart was evaluated based on some decision criteria through Monte Carlo simulation study.

  12. FW-CADIS Method for Global and Semi-Global Variance Reduction of Monte Carlo Radiation Transport Calculations

    SciTech Connect

    Wagner, John C; Peplow, Douglas E.; Mosher, Scott W

    2014-01-01

    This paper presents a new hybrid (Monte Carlo/deterministic) method for increasing the efficiency of Monte Carlo calculations of distributions, such as flux or dose rate distributions (e.g., mesh tallies), as well as responses at multiple localized detectors and spectra. This method, referred to as Forward-Weighted CADIS (FW-CADIS), is an extension of the Consistent Adjoint Driven Importance Sampling (CADIS) method, which has been used for more than a decade to very effectively improve the efficiency of Monte Carlo calculations of localized quantities, e.g., flux, dose, or reaction rate at a specific location. The basis of this method is the development of an importance function that represents the importance of particles to the objective of uniform Monte Carlo particle density in the desired tally regions. Implementation of this method utilizes the results from a forward deterministic calculation to develop a forward-weighted source for a deterministic adjoint calculation. The resulting adjoint function is then used to generate consistent space- and energy-dependent source biasing parameters and weight windows that are used in a forward Monte Carlo calculation to obtain more uniform statistical uncertainties in the desired tally regions. The FW-CADIS method has been implemented and demonstrated within the MAVRIC sequence of SCALE and the ADVANTG/MCNP framework. Application of the method to representative, real-world problems, including calculation of dose rate and energy dependent flux throughout the problem space, dose rates in specific areas, and energy spectra at multiple detectors, is presented and discussed. Results of the FW-CADIS method and other recently developed global variance reduction approaches are also compared, and the FW-CADIS method outperformed the other methods in all cases considered.

  13. Minimum Variance Distortionless Response Beamformer with Enhanced Nulling Level Control via Dynamic Mutated Artificial Immune System

    PubMed Central

    Kiong, Tiong Sieh; Salem, S. Balasem; Paw, Johnny Koh Siaw; Sankar, K. Prajindra

    2014-01-01

    In smart antenna applications, the adaptive beamforming technique is used to cancel interfering signals (placing nulls) and produce or steer a strong beam toward the target signal according to the calculated weight vectors. Minimum variance distortionless response (MVDR) beamforming is capable of determining the weight vectors for beam steering; however, its nulling level on the interference sources remains unsatisfactory. Beamforming can be considered as an optimization problem, such that optimal weight vector should be obtained through computation. Hence, in this paper, a new dynamic mutated artificial immune system (DM-AIS) is proposed to enhance MVDR beamforming for controlling the null steering of interference and increase the signal to interference noise ratio (SINR) for wanted signals. PMID:25003136

  14. Monte Carlo simulation of X-ray imaging and spectroscopy experiments using quadric geometry and variance reduction techniques

    NASA Astrophysics Data System (ADS)

    Golosio, Bruno; Schoonjans, Tom; Brunetti, Antonio; Oliva, Piernicola; Masala, Giovanni Luca

    2014-03-01

    The simulation of X-ray imaging experiments is often performed using deterministic codes, which can be relatively fast and easy to use. However, such codes are generally not suitable for the simulation of even slightly more complex experimental conditions, involving, for instance, first-order or higher-order scattering, X-ray fluorescence emissions, or more complex geometries, particularly for experiments that combine spatial resolution with spectral information. In such cases, simulations are often performed using codes based on the Monte Carlo method. In a simple Monte Carlo approach, the interaction position of an X-ray photon and the state of the photon after an interaction are obtained simply according to the theoretical probability distributions. This approach may be quite inefficient because the final channels of interest may include only a limited region of space or photons produced by a rare interaction, e.g., fluorescent emission from elements with very low concentrations. In the field of X-ray fluorescence spectroscopy, this problem has been solved by combining the Monte Carlo method with variance reduction techniques, which can reduce the computation time by several orders of magnitude. In this work, we present a C++ code for the general simulation of X-ray imaging and spectroscopy experiments, based on the application of the Monte Carlo method in combination with variance reduction techniques, with a description of sample geometry based on quadric surfaces. We describe the benefits of the object-oriented approach in terms of code maintenance, the flexibility of the program for the simulation of different experimental conditions and the possibility of easily adding new modules. Sample applications in the fields of X-ray imaging and X-ray spectroscopy are discussed. Catalogue identifier: AERO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERO_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland

  15. Model reduction methods for control design

    NASA Technical Reports Server (NTRS)

    Dunipace, K. R.

    1988-01-01

    Several different model reduction methods are developed and detailed implementation information is provided for those methods. Command files to implement the model reduction methods in a proprietary control law analysis and design package are presented. A comparison and discussion of the various reduction techniques is included.

  16. Noise Reduction Through Circulation Control

    NASA Technical Reports Server (NTRS)

    Munro, Scott E.; Ahuja, K. K.; Englar, Robert J.

    2005-01-01

    Circulation control technology uses tangential blowing around a rounded trailing edge or a leading edge to change the force and moment characteristics of an aerodynamic body. This technology has been applied to circular cylinders, wings, helicopter rotors, and even to automobiles for improved aerodynamic performance. Only limited research has been conducted on the acoustic of this technology. Since wing flaps contribute to the environmental noise of an aircraft, an alternate blown high lift system without complex mechanical flaps could prove beneficial in reducing the noise of an approaching aircraft. Thus, in this study, a direct comparison of the acoustic characteristics of high lift systems employing a circulation control wing configuration and a conventional wing flapped configuration has been made. These results indicate that acoustically, a circulation control wing high lift system could be considerably more acceptable than a wing with conventional mechanical flaps.

  17. Budgeting and controllable cost variances. The case of multiple diagnoses, multiple services, and multiple resources.

    PubMed

    Broyles, R W; Lay, C M

    1982-12-01

    This paper examines an unfavorable cost variance in an institution which employs multiple resources to provide stay specific and ancillary services to patients presenting multiple diagnoses. It partitions the difference between actual and expected costs into components that are the responsibility of an identifiable individual or group of individuals. The analysis demonstrates that the components comprising an unfavorable cost variance are attributable to factor prices, the use of real resources, the mix of patients, and the composition of care provided by the institution. In addition, the interactive effects of these factors are also identified. PMID:7183731

  18. Directional variance adjustment: bias reduction in covariance matrices based on factor analysis with an application to portfolio optimization.

    PubMed

    Bartz, Daniel; Hatrick, Kerr; Hesse, Christian W; Müller, Klaus-Robert; Lemm, Steven

    2013-01-01

    Robust and reliable covariance estimates play a decisive role in financial and many other applications. An important class of estimators is based on factor models. Here, we show by extensive Monte Carlo simulations that covariance matrices derived from the statistical Factor Analysis model exhibit a systematic error, which is similar to the well-known systematic error of the spectrum of the sample covariance matrix. Moreover, we introduce the Directional Variance Adjustment (DVA) algorithm, which diminishes the systematic error. In a thorough empirical study for the US, European, and Hong Kong stock market we show that our proposed method leads to improved portfolio allocation. PMID:23844016

  19. Directional Variance Adjustment: Bias Reduction in Covariance Matrices Based on Factor Analysis with an Application to Portfolio Optimization

    PubMed Central

    Bartz, Daniel; Hatrick, Kerr; Hesse, Christian W.; Müller, Klaus-Robert; Lemm, Steven

    2013-01-01

    Robust and reliable covariance estimates play a decisive role in financial and many other applications. An important class of estimators is based on factor models. Here, we show by extensive Monte Carlo simulations that covariance matrices derived from the statistical Factor Analysis model exhibit a systematic error, which is similar to the well-known systematic error of the spectrum of the sample covariance matrix. Moreover, we introduce the Directional Variance Adjustment (DVA) algorithm, which diminishes the systematic error. In a thorough empirical study for the US, European, and Hong Kong stock market we show that our proposed method leads to improved portfolio allocation. PMID:23844016

  20. Efficiency control in large-scale genotyping using analysis of variance.

    PubMed

    Spijker, Geert T; Bruinenberg, Marcel; te Meerman, Gerard J

    2005-01-01

    The efficiency of the genotyping process is determined by many simultaneous factors. In actual genotyping, a production run is often preceded by small-scale experiments to find optimal conditions. We propose to use statistical analysis of production run data as well, to gain insight into factors important for the outcome of genotyping. As an example, we show that analysis of variance (ANOVA) applied to the first-pass results of a genetic study reveals important determinants of genotyping success. The largest factor limiting genotyping appeared to be interindividual variation among DNA samples, explaining 20% of the variance, and a smaller reaction volume, sizing failure, and differences among markers all explained approximately 10%. Other potentially important factors, such as sample position within the plate and reusing electrophoresis matrix, appeared to be of minor influence. About 55% of the total variance could be explained by systematic factors. These results show that ANOVA can provide valuable feedback to improve genotyping efficiency. We propose to adjust genotype production runs using principles of experimental design in order to maximize genotyping efficiency at little additional cost.

  1. Environmental Factors That Control Microbial Perchlorate Reduction

    PubMed Central

    Chaudhuri, Swades K.; O'Connor, Susan M.; Gustavson, Ruth L.; Achenbach, Laurie A.; Coates, John D.

    2002-01-01

    As part of a study to elucidate the environmental parameters that control microbial perchlorate respiration, we investigated the reduction of perchlorate by the dissimilatory perchlorate reducer Dechlorosoma suillum under a diverse set of environmental conditions. Our results demonstrated that perchlorate reduction by D. suillum only occurred under anaerobic conditions in the presence of perchlorate and was dependent on the presence of molybdenum. Perchlorate reduction was dependent on the presence of the enzyme chlorite dismutase, which was induced during metabolism of perchlorate. Anaerobic conditions alone were not enough to induce expression of this enzyme. Dissolved oxygen concentrations less than 2 mg liter−1 were enough to inhibit perchlorate reduction by D. suillum. Similarly to oxygen, nitrate also regulated chlorite dismutase expression and repressed perchlorate reduction by D. suillum. Perchlorate-grown cultures of D. suillum preferentially reduced nitrate in media with equimolar amounts of perchlorate and nitrate. In contrast, an extended (40 h) lag phase was observed if a similar nitrate-perchlorate medium was inoculated with a nitrate-grown culture. Perchlorate reduction commenced only when nitrate was completely removed in either of these experiments. In contrast to D. suillum, nitrate had no inhibitory effects on perchlorate reduction by the perchlorate reducer Dechloromonas agitata strain CKB. Nitrate was reduced to nitrite concomitant with perchlorate reduction to chloride. These studies demonstrate that microbial respiration of perchlorate is significantly affected by environmental conditions and perchlorate reduction is directly dependent on bioavailable molybdenum and the presence or absence of competing electron acceptors. A microbial treatment strategy can achieve and maintain perchlorate concentrations below the recommended regulatory level, but only in environments in which the variables described above can be controlled. PMID:12200296

  2. Three Averaging Techniques for Reduction of Antenna Temperature Variance Measured by a Dicke Mode, C-Band Radiometer

    NASA Technical Reports Server (NTRS)

    Mackenzie, Anne I.; Lawrence, Roland W.

    2000-01-01

    As new radiometer technologies provide the possibility of greatly improved spatial resolution, their performance must also be evaluated in terms of expected sensitivity and absolute accuracy. As aperture size increases, the sensitivity of a Dicke mode radiometer can be maintained or improved by application of any or all of three digital averaging techniques: antenna data averaging with a greater than 50% antenna duty cycle, reference data averaging, and gain averaging. An experimental, noise-injection, benchtop radiometer at C-band showed a 68.5% reduction in Delta-T after all three averaging methods had been applied simultaneously. For any one antenna integration time, the optimum 34.8% reduction in Delta-T was realized by using an 83.3% antenna/reference duty cycle.

  3. Innovative Flow Control Concepts for Drag Reduction

    NASA Technical Reports Server (NTRS)

    Lin, John C.; Whalen, Edward A.; Eppink, Jenna L.; Siochi, Emilie J.; Alexander, Michael G.; Andino, Marlyn Y.

    2016-01-01

    This paper highlights the technology development of two flow control concepts for aircraft drag reduction. The NASA Environmentally Responsible Aviation (ERA) project worked with Boeing to demonstrate these two concepts on a specially outfitted Boeing 757 ecoDemonstrator during the spring of 2015. The first flow control concept used Active Flow Control (AFC) to delay flow separation on a highly deflected rudder and increase the side force that it generates. This may enable a smaller vertical tail to provide the control authority needed in the event of an engine failure during takeoff and landing, while still operating in a conventional manner over the rest of the flight envelope. Thirty-one sweeping jet AFC actuators were installed and successfully flight-tested on the vertical tail of the 757 ecoDemonstrator. Pilot feedback, flow cone visualization, and analysis of the flight test data confirmed that the AFC is effective, as a smoother flight and enhanced rudder control authority were reported. The second flow control concept is the Insect Accretion Mitigation (IAM) innovation where surfaces were engineered to mitigate insect residue adhesion on a wing's leading edge. This is necessary because something as small as an insect residue on the leading edge of a laminar flow wing design can cause turbulent wedges that interrupt laminar flow, resulting in an increase in drag and fuel use. Several non-stick coatings were developed by NASA and applied to panels that were mounted on the leading edge of the wing of the 757 ecoDemonstrator. The performance of the coated surfaces was measured and validated by the reduction in the number of bug adhesions relative to uncoated control panels flown simultaneously. Both flow control concepts (i.e., sweeping jet actuators and non-stick coatings) for drag reduction were the culmination of several years of development, from wind tunnel tests to flight tests, and produced valuable data for the advancement of modern aircraft designs

  4. Robust fuzzy control subject to state variance and passivity constraints for perturbed nonlinear systems with multiplicative noises.

    PubMed

    Chang, Wen-Jer; Huang, Bo-Jyun

    2014-11-01

    The multi-constrained robust fuzzy control problem is investigated in this paper for perturbed continuous-time nonlinear stochastic systems. The nonlinear system considered in this paper is represented by a Takagi-Sugeno fuzzy model with perturbations and state multiplicative noises. The multiple performance constraints considered in this paper include stability, passivity and individual state variance constraints. The Lyapunov stability theory is employed to derive sufficient conditions to achieve the above performance constraints. By solving these sufficient conditions, the contribution of this paper is to develop a parallel distributed compensation based robust fuzzy control approach to satisfy multiple performance constraints for perturbed nonlinear systems with multiplicative noises. At last, a numerical example for the control of perturbed inverted pendulum system is provided to illustrate the applicability and effectiveness of the proposed multi-constrained robust fuzzy control method.

  5. Model reduction for axisymmetric tokamak control

    SciTech Connect

    Tinios, G.; Horne, S. F.; Hutchinson, I. H.; Wolfe, S. M.

    1992-12-31

    We deal with the problem of reducing a complicated electromagnetic passive structure model coupled to a linear plasma response model to a size that allows rapid calculations of gains for plasma position and shape control. We find that model reduction through eigenmode decomposition does not reproduce the input-to-output relationship of the system, unless one has a good idea of which eigenmodes are important. Hankel singular mode decomposition, on the other hand, provides an orthogonal basis for the system response, where the modes are ordered by their importance to the input-to-output relationship. A perturbed equilibrium plasma response model is used together with an electromagnetic model of the Alcator C-MOD passive structure to assess the performance of different model reduction schemes. We find that between 10 and 20 modes are required to give an adequate representation of the passive system. Emphasis is placed on keeping the reduction process independent of the parameters of the plasma we are trying to control.

  6. A MODEL AND CONTROLLER REDUCTION METHOD FOR ROBUST CONTROL DESIGN.

    SciTech Connect

    YUE,M.; SCHLUETER,R.

    2003-10-20

    A bifurcation subsystem based model and controller reduction approach is presented. Using this approach a robust {micro}-synthesis SVC control is designed for interarea oscillation and voltage control based on a small reduced order bifurcation subsystem model of the full system. The control synthesis problem is posed by structured uncertainty modeling and control configuration formulation using the bifurcation subsystem knowledge of the nature of the interarea oscillation caused by a specific uncertainty parameter. Bifurcation subsystem method plays a key role in this paper because it provides (1) a bifurcation parameter for uncertainty modeling; (2) a criterion to reduce the order of the resulting MSVC control; and (3) a low order model for a bifurcation subsystem based SVC (BMSVC) design. The use of the model of the bifurcation subsystem to produce a low order controller simplifies the control design and reduces the computation efforts so significantly that the robust {micro}-synthesis control can be applied to large system where the computation makes robust control design impractical. The RGA analysis and time simulation show that the reduced BMSVC control design captures the center manifold dynamics and uncertainty structure of the full system model and is capable of stabilizing the full system and achieving satisfactory control performance.

  7. Model Reduction for Control System Design

    NASA Technical Reports Server (NTRS)

    Enns, D. F.

    1985-01-01

    An approach and a technique for effectively obtaining reduced order mathematical models of a given large order model for the purposes of synthesis, analysis and implementation of control systems is developed. This approach involves the use of an error criterion which is the H-infinity norm of a frequency weighted error between the full and reduced order models. The weightings are chosen to take into account the purpose for which the reduced order model is intended. A previously unknown error bound in the H-infinity norm for reduced order models obtained from internally balanced realizations was obtained. This motivated further development of the balancing technique to include the frequency dependent weightings. This resulted in the frequency weighted balanced realization and a new model reduction technique. Two approaches to designing reduced order controllers were developed. The first involves reducing the order of a high order controller with an appropriate weighting. The second involves linear quadratic Gaussian synthesis based on a reduced order model obtained with an appropriate weighting.

  8. Orthogonal control of expression mean and variance by epigenetic features at different genomic loci

    SciTech Connect

    Dey, Siddharth S.; Foley, Jonathan E.; Limsirichai, Prajit; Schaffer, David V.; Arkin, Adam P.

    2015-05-05

    While gene expression noise has been shown to drive dramatic phenotypic variations, the molecular basis for this variability in mammalian systems is not well understood. Gene expression has been shown to be regulated by promoter architecture and the associated chromatin environment. However, the exact contribution of these two factors in regulating expression noise has not been explored. Using a dual-reporter lentiviral model system, we deconvolved the influence of the promoter sequence to systematically study the contribution of the chromatin environment at different genomic locations in regulating expression noise. By integrating a large-scale analysis to quantify mRNA levels by smFISH and protein levels by flow cytometry in single cells, we found that mean expression and noise are uncorrelated across genomic locations. Furthermore, we showed that this independence could be explained by the orthogonal control of mean expression by the transcript burst size and noise by the burst frequency. Finally, we showed that genomic locations displaying higher expression noise are associated with more repressed chromatin, thereby indicating the contribution of the chromatin environment in regulating expression noise.

  9. Orthogonal control of expression mean and variance by epigenetic features at different genomic loci

    DOE PAGESBeta

    Dey, Siddharth S.; Foley, Jonathan E.; Limsirichai, Prajit; Schaffer, David V.; Arkin, Adam P.

    2015-05-05

    While gene expression noise has been shown to drive dramatic phenotypic variations, the molecular basis for this variability in mammalian systems is not well understood. Gene expression has been shown to be regulated by promoter architecture and the associated chromatin environment. However, the exact contribution of these two factors in regulating expression noise has not been explored. Using a dual-reporter lentiviral model system, we deconvolved the influence of the promoter sequence to systematically study the contribution of the chromatin environment at different genomic locations in regulating expression noise. By integrating a large-scale analysis to quantify mRNA levels by smFISH andmore » protein levels by flow cytometry in single cells, we found that mean expression and noise are uncorrelated across genomic locations. Furthermore, we showed that this independence could be explained by the orthogonal control of mean expression by the transcript burst size and noise by the burst frequency. Finally, we showed that genomic locations displaying higher expression noise are associated with more repressed chromatin, thereby indicating the contribution of the chromatin environment in regulating expression noise.« less

  10. [Harm reduction strategy in tobacco control].

    PubMed

    Gorini, Giuseppe

    2011-01-01

    .Thus, California Department of Health Services prohibits promotion of snus and medicinal nicotine as a harm reduction strategy. However, the US Federal Family Smoking Prevention and Tobacco Control Act, signed by President Obama in 2009, places tobacco products under FDA jurisdiction: FDA must define criteria for lowering carcinogens and toxicants in tobacco products, making more available medicinal nicotine, evaluating PREPs, creating a federal Tobacco Control Agency.Which approaches is Italy going to follow? PMID:21926451

  11. Helicopter Control Energy Reduction Using Moving Horizontal Tail.

    PubMed

    Oktay, Tugrul; Sal, Firat

    2015-01-01

    Helicopter moving horizontal tail (i.e., MHT) strategy is applied in order to save helicopter flight control system (i.e., FCS) energy. For this intention complex, physics-based, control-oriented nonlinear helicopter models are used. Equations of MHT are integrated into these models and they are together linearized around straight level flight condition. A specific variance constrained control strategy, namely, output variance constrained Control (i.e., OVC) is utilized for helicopter FCS. Control energy savings due to this MHT idea with respect to a conventional helicopter are calculated. Parameters of helicopter FCS and dimensions of MHT are simultaneously optimized using a stochastic optimization method, namely, simultaneous perturbation stochastic approximation (i.e., SPSA). In order to observe improvement in behaviors of classical controls closed loop analyses are done.

  12. Helicopter Control Energy Reduction Using Moving Horizontal Tail

    PubMed Central

    Oktay, Tugrul; Sal, Firat

    2015-01-01

    Helicopter moving horizontal tail (i.e., MHT) strategy is applied in order to save helicopter flight control system (i.e., FCS) energy. For this intention complex, physics-based, control-oriented nonlinear helicopter models are used. Equations of MHT are integrated into these models and they are together linearized around straight level flight condition. A specific variance constrained control strategy, namely, output variance constrained Control (i.e., OVC) is utilized for helicopter FCS. Control energy savings due to this MHT idea with respect to a conventional helicopter are calculated. Parameters of helicopter FCS and dimensions of MHT are simultaneously optimized using a stochastic optimization method, namely, simultaneous perturbation stochastic approximation (i.e., SPSA). In order to observe improvement in behaviors of classical controls closed loop analyses are done. PMID:26180841

  13. The entropy reduction engine: Integrating planning, scheduling, and control

    NASA Technical Reports Server (NTRS)

    Drummond, Mark; Bresina, John L.; Kedar, Smadar T.

    1991-01-01

    The Entropy Reduction Engine, an architecture for the integration of planning, scheduling, and control, is described. The architecture is motivated, presented, and analyzed in terms of its different components; namely, problem reduction, temporal projection, and situated control rule execution. Experience with this architecture has motivated the recent integration of learning. The learning methods are described along with their impact on architecture performance.

  14. Practice reduces task relevant variance modulation and forms nominal trajectory

    PubMed Central

    Osu, Rieko; Morishige, Ken-ichi; Nakanishi, Jun; Miyamoto, Hiroyuki; Kawato, Mitsuo

    2015-01-01

    Humans are capable of achieving complex tasks with redundant degrees of freedom. Much attention has been paid to task relevant variance modulation as an indication of online feedback control strategies to cope with motor variability. Meanwhile, it has been discussed that the brain learns internal models of environments to realize feedforward control with nominal trajectories. Here we examined trajectory variance in both spatial and temporal domains to elucidate the relative contribution of these control schemas. We asked subjects to learn reaching movements with multiple via-points, and found that hand trajectories converged to stereotyped trajectories with the reduction of task relevant variance modulation as learning proceeded. Furthermore, variance reduction was not always associated with task constraints but was highly correlated with the velocity profile. A model assuming noise both on the nominal trajectory and motor command was able to reproduce the observed variance modulation, supporting an expression of nominal trajectories in the brain. The learning-related decrease in task-relevant modulation revealed a reduction in the influence of optimal feedback around the task constraints. After practice, the major part of computation seems to be taken over by the feedforward controller around the nominal trajectory with feedback added only when it becomes necessary. PMID:26639942

  15. Practice reduces task relevant variance modulation and forms nominal trajectory

    NASA Astrophysics Data System (ADS)

    Osu, Rieko; Morishige, Ken-Ichi; Nakanishi, Jun; Miyamoto, Hiroyuki; Kawato, Mitsuo

    2015-12-01

    Humans are capable of achieving complex tasks with redundant degrees of freedom. Much attention has been paid to task relevant variance modulation as an indication of online feedback control strategies to cope with motor variability. Meanwhile, it has been discussed that the brain learns internal models of environments to realize feedforward control with nominal trajectories. Here we examined trajectory variance in both spatial and temporal domains to elucidate the relative contribution of these control schemas. We asked subjects to learn reaching movements with multiple via-points, and found that hand trajectories converged to stereotyped trajectories with the reduction of task relevant variance modulation as learning proceeded. Furthermore, variance reduction was not always associated with task constraints but was highly correlated with the velocity profile. A model assuming noise both on the nominal trajectory and motor command was able to reproduce the observed variance modulation, supporting an expression of nominal trajectories in the brain. The learning-related decrease in task-relevant modulation revealed a reduction in the influence of optimal feedback around the task constraints. After practice, the major part of computation seems to be taken over by the feedforward controller around the nominal trajectory with feedback added only when it becomes necessary.

  16. Practice reduces task relevant variance modulation and forms nominal trajectory.

    PubMed

    Osu, Rieko; Morishige, Ken-ichi; Nakanishi, Jun; Miyamoto, Hiroyuki; Kawato, Mitsuo

    2015-01-01

    Humans are capable of achieving complex tasks with redundant degrees of freedom. Much attention has been paid to task relevant variance modulation as an indication of online feedback control strategies to cope with motor variability. Meanwhile, it has been discussed that the brain learns internal models of environments to realize feedforward control with nominal trajectories. Here we examined trajectory variance in both spatial and temporal domains to elucidate the relative contribution of these control schemas. We asked subjects to learn reaching movements with multiple via-points, and found that hand trajectories converged to stereotyped trajectories with the reduction of task relevant variance modulation as learning proceeded. Furthermore, variance reduction was not always associated with task constraints but was highly correlated with the velocity profile. A model assuming noise both on the nominal trajectory and motor command was able to reproduce the observed variance modulation, supporting an expression of nominal trajectories in the brain. The learning-related decrease in task-relevant modulation revealed a reduction in the influence of optimal feedback around the task constraints. After practice, the major part of computation seems to be taken over by the feedforward controller around the nominal trajectory with feedback added only when it becomes necessary. PMID:26639942

  17. Boundary-layer control for drag reduction

    NASA Technical Reports Server (NTRS)

    Harvey, William D.

    1988-01-01

    Although the number of possible applications of boundary-layer control is large, a discussion is given only of those that have received the most attention recently at NASA Langley Research Center to improve airfoil drag characteristics. This research concerns stabilizing the laminar boundary layer through geometric shaping (natural laminar flow, NLF) and active control involving the removal of a portion of the laminar boundary layer (laminar flow control, LFC) either through discrete slots or a perforated surface. At low Reynolds numbers, a combination of shaping and forced transition has been used to achieve the desired run of laminar flow and control of laminar separation. In the design of both natural laminar flow and laminar flow control airfoils and wings, boundary layer stability codes play an important role. A discussion of some recent stability calculations using both incompressible and compressible codes is given.

  18. Magnetostrictively actuated control flaps for vibration reduction in helicopter rotors

    SciTech Connect

    Millott, T.; Friedmann, P.P.

    1994-12-31

    High vibration levels can impose constraints on helicopter operations and hinder passenger acceptance. Vibration reduction using blade root pitch control introduces a significant power penalty and may adversely affect the airworthiness of the flight control system. Comparable levels of vibration reduction can be achieved using considerably less power through an actively controlled trailing edge flap mounted on the blade. Such a device would have no effect on helicopter airworthiness since it is controlled by a loop separate from the primary flight control system which utilizes the swashplate. Control flap actuation using the magnetostrictive material Terfenol-D is studied in this paper by designing a minimum weight actuator, subject to a set of actuation and stress constraints. The resulting device is capable of producing vibration reduction in excess of 90% at cruise conditions.

  19. Active flow control for Aeolian tone noise reduction

    NASA Technical Reports Server (NTRS)

    Hardin, Jay C.; Pope, D. Stuart

    1989-01-01

    This paper examines the use of active flow control for the purpose of noise reduction. As a simple demonstration of such techniques, several methods for controlling the wake and resulting noise production by a cylinder in a uniform stream are evaluated numerically.

  20. Reporting explained variance

    NASA Astrophysics Data System (ADS)

    Good, Ron; Fletcher, Harold J.

    The importance of reporting explained variance (sometimes referred to as magnitude of effects) in ANOVA designs is discussed in this paper. Explained variance is an estimate of the strength of the relationship between treatment (or other factors such as sex, grade level, etc.) and dependent variables of interest to the researcher(s). Three methods that can be used to obtain estimates of explained variance in ANOVA designs are described and applied to 16 studies that were reported in recent volumes of this journal. The results show that, while in most studies the treatment accounts for a relatively small proportion of the variance in dependent variable scores., in., some studies the magnitude of the treatment effect is respectable. The authors recommend that researchers in science education report explained variance in addition to the commonly reported tests of significance, since the latter are inadequate as the sole basis for making decisions about the practical importance of factors of interest to science education researchers.

  1. Abiotic Reduction of Selenite and Antimonate Under Controlled Oxygen Conditions

    NASA Astrophysics Data System (ADS)

    Belzile, N.; Truong, H. T.; Polack, R.; Chen, Y.

    2008-12-01

    Laboratory and field studies have reported the oxidation of elemental Se to selenite or selenate or that of antimonite to antimonate but the reduction studies of the two elements, especially in absence of bacteria are more scarce. We have performed experiments on the abiotic reduction of Se(IV) and Sb(V) under controlled oxygen conditions in presence of naturally-encountered reducing agents such as Fe(II) and dissolved sulfide. In the case of selenite, the reduction by ferrous iron is barely detectable at very low concentrations of oxygen. However, at concentrations of 200 ± 50 ppmv in the controlled atmosphere glove box, more iron oxide particles were formed at a higher initial Fe(II) concentration in the system and with time. In the pellets collected after filtration, a significant amount of Se(0) was found. Our field geochemical studies on Se also showed the same phenomenon, i.e. a higher level of Se(0) in lake sediments was accompanied by a higher presence of iron oxides. In the case of antimony, the reduction of Sb(V) by dissolved sulfide was extensive and far more rapid at more acidic pH values. Half lives for Sb(V) in the presence of excess dissolved sulfide at pH values of 5 to 7 were calculated and the reaction was found to be first order with respect to all three of [Sb(V)], [dissolved sulfide] and [H+]. Metastibnite precipitated after reduction of Sb(V) in working experimental samples at buffered pH of 5 and 6. The oxidation product of dissolved sulfide was identified as elemental sulfur. This study has demonstrated the ability of dissolved sulfide to reduce Sb(V) under a variety of environmentally relevant concentrations and conditions.

  2. A COSMIC VARIANCE COOKBOOK

    SciTech Connect

    Moster, Benjamin P.; Rix, Hans-Walter; Somerville, Rachel S.; Newman, Jeffrey A. E-mail: rix@mpia.de E-mail: janewman@pitt.edu

    2011-04-20

    Deep pencil beam surveys (<1 deg{sup 2}) are of fundamental importance for studying the high-redshift universe. However, inferences about galaxy population properties (e.g., the abundance of objects) are in practice limited by 'cosmic variance'. This is the uncertainty in observational estimates of the number density of galaxies arising from the underlying large-scale density fluctuations. This source of uncertainty can be significant, especially for surveys which cover only small areas and for massive high-redshift galaxies. Cosmic variance for a given galaxy population can be determined using predictions from cold dark matter theory and the galaxy bias. In this paper, we provide tools for experiment design and interpretation. For a given survey geometry, we present the cosmic variance of dark matter as a function of mean redshift z-bar and redshift bin size {Delta}z. Using a halo occupation model to predict galaxy clustering, we derive the galaxy bias as a function of mean redshift for galaxy samples of a given stellar mass range. In the linear regime, the cosmic variance of these galaxy samples is the product of the galaxy bias and the dark matter cosmic variance. We present a simple recipe using a fitting function to compute cosmic variance as a function of the angular dimensions of the field, z-bar , {Delta}z, and stellar mass m{sub *}. We also provide tabulated values and a software tool. The accuracy of the resulting cosmic variance estimates ({delta}{sigma}{sub v}/{sigma}{sub v}) is shown to be better than 20%. We find that for GOODS at z-bar =2 and with {Delta}z = 0.5, the relative cosmic variance of galaxies with m{sub *}>10{sup 11} M{sub sun} is {approx}38%, while it is {approx}27% for GEMS and {approx}12% for COSMOS. For galaxies of m{sub *} {approx} 10{sup 10} M{sub sun}, the relative cosmic variance is {approx}19% for GOODS, {approx}13% for GEMS, and {approx}6% for COSMOS. This implies that cosmic variance is a significant source of uncertainty at z

  3. A Cosmic Variance Cookbook

    NASA Astrophysics Data System (ADS)

    Moster, Benjamin P.; Somerville, Rachel S.; Newman, Jeffrey A.; Rix, Hans-Walter

    2011-04-01

    Deep pencil beam surveys (<1 deg2) are of fundamental importance for studying the high-redshift universe. However, inferences about galaxy population properties (e.g., the abundance of objects) are in practice limited by "cosmic variance." This is the uncertainty in observational estimates of the number density of galaxies arising from the underlying large-scale density fluctuations. This source of uncertainty can be significant, especially for surveys which cover only small areas and for massive high-redshift galaxies. Cosmic variance for a given galaxy population can be determined using predictions from cold dark matter theory and the galaxy bias. In this paper, we provide tools for experiment design and interpretation. For a given survey geometry, we present the cosmic variance of dark matter as a function of mean redshift \\bar{z} and redshift bin size Δz. Using a halo occupation model to predict galaxy clustering, we derive the galaxy bias as a function of mean redshift for galaxy samples of a given stellar mass range. In the linear regime, the cosmic variance of these galaxy samples is the product of the galaxy bias and the dark matter cosmic variance. We present a simple recipe using a fitting function to compute cosmic variance as a function of the angular dimensions of the field, \\bar{z}, Δz, and stellar mass m *. We also provide tabulated values and a software tool. The accuracy of the resulting cosmic variance estimates (δσ v /σ v ) is shown to be better than 20%. We find that for GOODS at \\bar{z}=2 and with Δz = 0.5, the relative cosmic variance of galaxies with m *>1011 M sun is ~38%, while it is ~27% for GEMS and ~12% for COSMOS. For galaxies of m * ~ 1010 M sun, the relative cosmic variance is ~19% for GOODS, ~13% for GEMS, and ~6% for COSMOS. This implies that cosmic variance is a significant source of uncertainty at \\bar{z}=2 for small fields and massive galaxies, while for larger fields and intermediate mass galaxies, cosmic variance is

  4. Supersonic impinging jet noise reduction using a hybrid control technique

    NASA Astrophysics Data System (ADS)

    Wiley, Alex; Kumar, Rajan

    2015-07-01

    Control of the highly resonant flowfield associated with supersonic impinging jet has been experimentally investigated. Measurements were made in the supersonic impinging jet facility at the Florida State University for a Mach 1.5 ideally expanded jet. Measurements included unsteady pressures on a surface plate near the nozzle exit, acoustics in the nearfield and beneath the impingement plane, and velocity field using particle image velocimetry. Both passive control using porous surface and active control with high momentum microjet injection are effective in reducing nearfield noise and flow unsteadiness over a range of geometrical parameters; however, the type of noise reduction achieved by the two techniques is different. The passive control reduces broadband noise whereas microjet injection attenuates high amplitude impinging tones. The hybrid control, a combination of two control methods, reduces both broadband and high amplitude impinging tones and surprisingly its effectiveness is more that the additive effect of the two control techniques. The flow field measurements show that with hybrid control the impinging jet is stabilized and the turbulence quantities such as streamwise turbulence intensity, transverse turbulence intensity and turbulent shear stress are significantly reduced.

  5. Possibilities for drag reduction by boundary layer control

    NASA Technical Reports Server (NTRS)

    Naiman, I.

    1946-01-01

    The mechanics of laminar boundary layer transition are reviewed. Drag possibilities for boundary layer control are analyzed using assumed conditions of transition Reynolds number, inlet loss, number of slots, blower efficiency, and duct losses. Although the results of such analysis are highly favorable, those obtained by experimental investigations yield conflicting results, showing only small gains, and sometimes losses. Reduction of this data indicates that there is a lower limit to the quantity of air which must be removed at the slot in order to stabilize the laminar flow. The removal of insufficient air permits transition to occur while the removal of excessive amounts of air results in high power costs, with a net drag increases. With the estimated value of flow coefficient and duct losses equal to half the dynamic pressure, drag reductions of 50% may be obtained; with twice this flow coefficient, the drag saving is reduced to 25%.

  6. Responsible and controlled use: Older cannabis users and harm reduction

    PubMed Central

    Lau, Nicholas; Sales, Paloma; Averill, Sheigla; Murphy, Fiona; Sato, Sye-Ok; Murphy, Sheigla

    2015-01-01

    Background Cannabis use is becoming more accepted in mainstream society. In this paper, we use Zinberg’s classic theoretical framework of drug, set, and setting to elucidate how older adult cannabis users managed health, social and legal risks in a context of normalized cannabis use. Methods We present selected findings from our qualitative study of Baby Boomer (born 1946–1964) cannabis users in the San Francisco Bay Area. Data collection consisted of a recorded, in-depth life history interview followed by a questionnaire and health survey. Qualitative interviews were analyzed to discover the factors of cannabis harm reduction from the users’ perspectives. Results Interviewees made harm reduction choices based on preferred cannabis derivatives and routes of administration, as well as why, when, where, and with whom to use. Most interviewees minimized cannabis-related harms so they could maintain social functioning in their everyday lives. Responsible and controlled use was described as moderation of quantity and frequency of cannabis used, using in appropriate settings, and respect for non-users. Users contributed to the normalization of cannabis use through normification. Conclusion Participants followed rituals or cultural practices, characterized by sanctions that helped define “normal” or “acceptable” cannabis use. Users contributed to cannabis normalization through their harm reduction methods. These cultural practices may prove to be more effective than formal legal prohibitions in reducing cannabis-related harms. Findings also suggest that users with access to a regulated market (medical cannabis dispensaries) were better equipped to practice harm reduction. More research is needed on both cannabis culture and alternative routes of administration as harm reduction methods. PMID:25911027

  7. Reduction of wind tunnel wall interference by controlled wall flow

    NASA Technical Reports Server (NTRS)

    Bernstein, S. (Editor); Joppa, R. G.

    1975-01-01

    An alternate method of testing was developed in which flow through the porous walls of the tunnel was actively controlled so as to approximate free air conditions in the neighborhood of the model during the test. The amount and distribution of the controlled flow through the walls is computed using a potential flow representation of the model based on the measured lift. Theoretical analysis is presented to prove the convergence of the method to free air conditions and to substantiate the general three-dimensional theory of operation when the normal flow distribution is continuous. A two-dimensional tunnel was constructed to evaluate the concept. Results show that substantial reduction of wall interference may be achieved with relatively low values of porosity of actively controlled walls.

  8. Space Technology 7 Disturbance Reduction System - precision control flight Validation

    NASA Technical Reports Server (NTRS)

    Carmain, Andrew J.; Dunn, Charles; Folkner, William; Hruby, Vlad; Spence, Doug; O'Donnell, James; Markley, Landis; Maghami, Peiman; Hsu, Oscar; Demmons, N.; Roy, T.; Gasdaska, C.; Young, J.; Connolly, W.; McCormick, R.; Gasdaska, C.

    2005-01-01

    The NASA New Millennium Program Space Technology 7 (ST7) project will validate technology for precision spacecraft control. The Disturbance Reduction System (DRS) will be part of the European Space Agency's LISA Pathfinder project. The DRS will control the position of the spacecraft relative to a reference to an accuracy of one nanometer over time scales of several thousand seconds. To perform the control, the spacecraft will use a new colloid thruster technology. The thrusters will operate over the range of 5 to 30 micro-Newtons with precision of 0.1 micro- Newton. The thrust will be generated by using a high electric field to extract charged droplets of a conducting colloid fluid and accelerating them with a precisely adjustable voltage. The control reference will be provided by the European LISA Technology Package, which will include two nearly freefloating test masses. The test mass positions and orientations will be measured using a capacitance bridge. The test mass position and attitude will be adjustable using electrostatically applied forces and torques. The DRS will control the spacecraft position with respect to one test mass while minimizing disturbances on the second test mass. The dynamic control system will cover eighteen degrees of freedom: six for each of the test masses and six for the spacecraft. After launch in late 2009 to a low Earth orbit, the LISA Pathfinder spacecraft will be maneuvered to a halo orbit about the Earth-Sun L1 Lagrange point for operations.

  9. The quantum Allan variance

    NASA Astrophysics Data System (ADS)

    Chabuda, Krzysztof; Leroux, Ian D.; Demkowicz-Dobrzański, Rafał

    2016-08-01

    The instability of an atomic clock is characterized by the Allan variance, a measure widely used to describe the noise of frequency standards. We provide an explicit method to find the ultimate bound on the Allan variance of an atomic clock in the most general scenario where N atoms are prepared in an arbitrarily entangled state and arbitrary measurement and feedback are allowed, including those exploiting coherences between succeeding interrogation steps. While the method is rigorous and general, it becomes numerically challenging for large N and long averaging times.

  10. "APEC Blue": Secondary Aerosol Reductions from Emission Controls in Beijing.

    PubMed

    Sun, Yele; Wang, Zifa; Wild, Oliver; Xu, Weiqi; Chen, Chen; Fu, Pingqing; Du, Wei; Zhou, Libo; Zhang, Qi; Han, Tingting; Wang, Qingqing; Pan, Xiaole; Zheng, Haitao; Li, Jie; Guo, Xiaofeng; Liu, Jianguo; Worsnop, Douglas R

    2016-01-01

    China implemented strict emission control measures in Beijing and surrounding regions to ensure good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. We conducted synchronous aerosol particle measurements with two aerosol mass spectrometers at different heights on a meteorological tower in urban Beijing to investigate the variations in particulate composition, sources and size distributions in response to emission controls. Our results show consistently large reductions in secondary inorganic aerosol (SIA) of 61-67% and 51-57%, and in secondary organic aerosol (SOA) of 55% and 37%, at 260 m and ground level, respectively, during the APEC summit. These changes were mainly caused by large reductions in accumulation mode particles and by suppression of the growth of SIA and SOA by a factor of 2-3, which led to blue sky days during APEC commonly referred to as "APEC Blue". We propose a conceptual framework for the evolution of primary and secondary species and highlight the importance of regional atmospheric transport in the formation of severe pollution episodes in Beijing. Our results indicate that reducing the precursors of secondary aerosol over regional scales is crucial and effective in suppressing the formation of secondary particulates and mitigating PM pollution. PMID:26891104

  11. Variance Anisotropy in Kinetic Plasmas

    NASA Astrophysics Data System (ADS)

    Parashar, Tulasi N.; Oughton, Sean; Matthaeus, William H.; Wan, Minping

    2016-06-01

    Solar wind fluctuations admit well-documented anisotropies of the variance matrix, or polarization, related to the mean magnetic field direction. Typically, one finds a ratio of perpendicular variance to parallel variance of the order of 9:1 for the magnetic field. Here we study the question of whether a kinetic plasma spontaneously generates and sustains parallel variances when initiated with only perpendicular variance. We find that parallel variance grows and saturates at about 5% of the perpendicular variance in a few nonlinear times irrespective of the Reynolds number. For sufficiently large systems (Reynolds numbers) the variance approaches values consistent with the solar wind observations.

  12. Conversations across Meaning Variance

    ERIC Educational Resources Information Center

    Cordero, Alberto

    2013-01-01

    Progressive interpretations of scientific theories have long been denounced as naive, because of the inescapability of meaning variance. The charge reportedly applies to recent realist moves that focus on theory-parts rather than whole theories. This paper considers the question of what "theory-parts" of epistemic significance (if any) relevantly…

  13. Naive Analysis of Variance

    ERIC Educational Resources Information Center

    Braun, W. John

    2012-01-01

    The Analysis of Variance is often taught in introductory statistics courses, but it is not clear that students really understand the method. This is because the derivation of the test statistic and p-value requires a relatively sophisticated mathematical background which may not be well-remembered or understood. Thus, the essential concept behind…

  14. Minimum variance geographic sampling

    NASA Technical Reports Server (NTRS)

    Terrell, G. R. (Principal Investigator)

    1980-01-01

    Resource inventories require samples with geographical scatter, sometimes not as widely spaced as would be hoped. A simple model of correlation over distances is used to create a minimum variance unbiased estimate population means. The fitting procedure is illustrated from data used to estimate Missouri corn acreage.

  15. Automated Boiler Combustion Controls for Emission Reduction and Efficiency Improvement

    SciTech Connect

    None, None

    1998-12-02

    In the late 1980s, then President Bush visited Krakow, Poland. The terrible air quality theremotivated him to initiate a USAID-funded program, managed by DOE, entitled "Krakow Clean Fossil Fuels and Energy Efficiency Program." The primary objective of this program was to encourage the formation of commercial ventures between U.S. and Polish firms to provide equipment and/or services to reduce pollution from low-emission sources in Krakow, Poland. This program led to the award of a number of cooperative agreements, including one to Control Techtronics International. The technical objective of CTI's cooperative agreement is to apply combustion controls to existing boiler plants in Krakow and transfer knowledge and technology through a joint U.S. and Polish commercial venture. CTI installed automatic combustion controls on five coal boilers for the district heating system in Krakow. Three of these were for domestic hot-water boilers, and two were for steam for industrial boilers. The following results have occurred due to the addition of CTI's combustion controls on these five existing boilers: ! 25% energy savings ! 85% reduction in particulate emissions The joint venture company CTI-Polska was then established. Eleven additional technical and costing proposals were initiated to upgrade other coal boilers in Krakow. To date, no co-financing has been made available on the Polish side. CTI-Polska continues in operation, serving customers in Russia and Ukraine. Should the market in Poland materialize, the joint venture company is established there to provide equipment and service.

  16. INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

    EPA Science Inventory

    The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

  17. Active control for drag reduction in turbulent channel flow: the opposition control schemes revisited

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Shan; Huang, Wei-Xi; Xu, Chun-Xiao

    2016-10-01

    The opposition control schemes first proposed by Choi et al (1994 J. Fluid Mech. 262 75) employing wall-normal (v) and spanwise (w) velocity are revisited in the present study by performing direct numerical simulation to turbulent channel flow at R{e}τ = 180. Special attention is paid to the combined control, in which the wall-normal and spanwise velocities are imposed at the wall just instantaneously opposite to those at a small distance to the wall. In comparison to the v- and w-controls, combined-control could achieve the best drag reduction rate and control efficiency, with the greatest suppression of turbulence intensities. The influence of control on the statistical properties of vortices is scrutinized. By control, the numbers of vortices with every circulation and radius apparently decrease at the same normal location near the wall, while the vortex radius scaled by the actual wall-friction velocity almost remains the same. The streamwise vortices and the induced Reynolds shear stress undergo the greatest suppression by combined control. It is shown that combined control achieves a better efficacy, attributed to the co-work of the mechanisms of the v- and w-controls. At a higher Reynolds number R{e}τ = 1000, combined control is also more effective than v- and w-controls. The better suppression effect on the outer large scales is the primary reason for the larger drag reduction rate in combined control.

  18. Control, Transport Reduction and Diagnostic use of Feedback

    NASA Astrophysics Data System (ADS)

    Sen, A. K.

    1999-11-01

    In the past we have reported on feedback suppression of a variety of micro-instabilities in the Columbia Linear Machine via an electron/ion beam suppressor. These include a curvature driven trapped particle mode, an E×B flute mode and an ITG mode; sometimes two of them simultaneously. We now report on reduction and scaling of transport under feedback. The anomalous particle transport due to an E×B centrifugally driven mode has been measured via cross-correlation of density and potential fluctuations. The transport is found to be reduced by up to a factor of three under feedback. By controlling the fluctuation amplitudes and consequently the transport via feedback, we find the scaling of diffusion coefficient to be linear with RMS fluctuation level. The scaling appears not to agree with any generic theory. Recently, we have performed a numerical experiment on feedback control of dissipative drift wave instability in collaboration with ETP, University of Marseille. The preliminary result is that even a highly chaotic state of the instability can be suppressed, if the feedback delay is less than the correlation time of fluctuations. We will explore the implication of these results for the remote prospect of reduction of micro-turbulence and associated transport. We are also persuing a variety of diagnostic uses of feedback. The primary goal is an experimental methodology for the determination of dynamic models of plasma turbulence, both for better transport understanding and more credible feedback controller designs. A specific motivation is to search for a low order dynamic model, suitable for the convenient study of both transport and feedback. First, we use time series analysis method for the determination of chaotic attractor dimension of plasma fluctuations. For E×B rotational flute modes it is found to be close to three, indicating that a model of three coupled modes may be adequate for transport prediction and feedback controller design. Secondly, we have

  19. Nuclear Material Variance Calculation

    1995-01-01

    MAVARIC (Materials Accounting VARIance Calculations) is a custom spreadsheet that significantly reduces the effort required to make the variance and covariance calculations needed to determine the detection sensitivity of a materials accounting system and loss of special nuclear material (SNM). The user is required to enter information into one of four data tables depending on the type of term in the materials balance (MB) equation. The four data tables correspond to input transfers, output transfers,more » and two types of inventory terms, one for nondestructive assay (NDA) measurements and one for measurements made by chemical analysis. Each data entry must contain an identification number and a short description, as well as values for the SNM concentration, the bulk mass (or solution volume), the measurement error standard deviations, and the number of measurements during an accounting period. The user must also specify the type of error model (additive or multiplicative) associated with each measurement, and possible correlations between transfer terms. Predefined spreadsheet macros are used to perform the variance and covariance calculations for each term based on the corresponding set of entries. MAVARIC has been used for sensitivity studies of chemical separation facilities, fuel processing and fabrication facilities, and gas centrifuge and laser isotope enrichment facilities.« less

  20. Nominal analysis of "variance".

    PubMed

    Weiss, David J

    2009-08-01

    Nominal responses are the natural way for people to report actions or opinions. Because nominal responses do not generate numerical data, they have been underutilized in behavioral research. On those occasions in which nominal responses are elicited, the responses are customarily aggregated over people or trials so that large-sample statistics can be employed. A new analysis is proposed that directly associates differences among responses with particular sources in factorial designs. A pair of nominal responses either matches or does not; when responses do not match, they vary. That analogue to variance is incorporated in the nominal analysis of "variance" (NANOVA) procedure, wherein the proportions of matches associated with sources play the same role as do sums of squares in an ANOVA. The NANOVA table is structured like an ANOVA table. The significance levels of the N ratios formed by comparing proportions are determined by resampling. Fictitious behavioral examples featuring independent groups and repeated measures designs are presented. A Windows program for the analysis is available.

  1. COST OF SELECTIVE CATALYTIC REDUCTION (SCR) APPLICATION FOR NOX CONTROL ON COAL-FIRED BOILERS

    EPA Science Inventory

    The report provides a methodology for estimating budgetary costs associated with retrofit applications of selective catalytic reduction (SCR) technology on coal-fired boilers. SCR is a postcombustion nitrogen oxides (NOx) control technology capable of providing NOx reductions >90...

  2. Lead-Lag Control for Helicopter Vibration and Noise Reduction

    NASA Technical Reports Server (NTRS)

    Gandhi, Farhan

    1995-01-01

    As a helicopter transitions from hover to forward flight, the main rotor blades experience an asymmetry in flow field around the azimuth, with the blade section tangential velocities increasing on the advancing side and decreasing on the retreating side. To compensate for the reduced dynamic pressure on the retreating side, the blade pitch angles over this part of the rotor disk are increased. Eventually, a high enough forward speed is attained to produce compressibility effects on the advancing side of the rotor disk and stall on the retreating side. The onset of these two phenomena drastically increases the rotor vibratory loads and power requirements, thereby effectively establishing a limit on the maximum achievable forward speed. The alleviation of compressibility and stall (and the associated decrease in vibratory loads and power) would potentially result in an increased maximum forward speed. In the past, several methods have been examined and implemented to reduce the vibratory hub loads. Some of these methods are aimed specifically at alleviating vibration at very high flight speeds and increasing the maximum flight speed, while others focus on vibration reduction within the conventional flight envelope. Among the later are several types passive as well as active schemes. Passive schemes include a variety of vibration absorbers such as mechanical springs, pendulums, and bifilar absorbers. These mechanism are easy to design and maintain, but incur significant weight and drag penalties. Among the popular active control schemes in consideration are Higher Harmonic Control (HHC) and Individual Blade Control (IBC). HHC uses a conventional swash plate to generate a multi-cyclic pitch input to the blade. This requires actuators capable of sufficiently high power and bandwidth, increasing the cost and weight of the aircraft. IBC places actuators in the rotating reference frame, requiring the use of slip rings capable of transferring enough power to the actuators

  3. Empowerment, span of control, and safety performance in work teams after workforce reduction.

    PubMed

    Hechanova-Alampay, R; Beehr, T A

    2001-10-01

    Relationships of empowerment and span of control with 2 safety measures (unsafe behaviors and accidents) were investigated among 24 workgroups comprising 531 employees of a large chemical company in 3 U.S. states. The company recently implemented a reengineering process. Data were from an anonymous survey (unsafe behaviors), company records (accidents, span of control), and trained expert raters (empowerment). Span of control (positively) and level of empowerment (negatively) correlated with both measures of poor safety performance, but only empowerment predicted unique variance in safety criteria. Together, these structural measures predicted one third of the variance in safety measures. Structural variables such as span of control and team empowerment have been largely overlooked in past safety research but can be important.

  4. 29 CFR 1918.4 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... § 1918.4 OMB control numbers under the Paperwork Reduction Act. The following list identifies the 29 CFR... number 1218-0003 expires on July 31, 2001. The list follows: 29 CFR citation OMB control No. 1918.22(g... 29 Labor 7 2013-07-01 2013-07-01 false OMB control numbers under the Paperwork Reduction Act....

  5. Variance of gene expression identifies altered network constraints in neurological disease.

    PubMed

    Mar, Jessica C; Matigian, Nicholas A; Mackay-Sim, Alan; Mellick, George D; Sue, Carolyn M; Silburn, Peter A; McGrath, John J; Quackenbush, John; Wells, Christine A

    2011-08-01

    Gene expression analysis has become a ubiquitous tool for studying a wide range of human diseases. In a typical analysis we compare distinct phenotypic groups and attempt to identify genes that are, on average, significantly different between them. Here we describe an innovative approach to the analysis of gene expression data, one that identifies differences in expression variance between groups as an informative metric of the group phenotype. We find that genes with different expression variance profiles are not randomly distributed across cell signaling networks. Genes with low-expression variance, or higher constraint, are significantly more connected to other network members and tend to function as core members of signal transduction pathways. Genes with higher expression variance have fewer network connections and also tend to sit on the periphery of the cell. Using neural stem cells derived from patients suffering from Schizophrenia (SZ), Parkinson's disease (PD), and a healthy control group, we find marked differences in expression variance in cell signaling pathways that shed new light on potential mechanisms associated with these diverse neurological disorders. In particular, we find that expression variance of core networks in the SZ patient group was considerably constrained, while in contrast the PD patient group demonstrated much greater variance than expected. One hypothesis is that diminished variance in SZ patients corresponds to an increased degree of constraint in these pathways and a corresponding reduction in robustness of the stem cell networks. These results underscore the role that variation plays in biological systems and suggest that analysis of expression variance is far more important in disease than previously recognized. Furthermore, modeling patterns of variability in gene expression could fundamentally alter the way in which we think about how cellular networks are affected by disease processes.

  6. Cosmology without cosmic variance

    DOE PAGESBeta

    Bernstein, Gary M.; Cai, Yan -Chuan

    2011-10-01

    The growth of structures in the Universe is described by a function G that is predicted by the combination of the expansion history of the Universe and the laws of gravity within it. We examine the improvements in constraints on G that are available from the combination of a large-scale galaxy redshift survey with a weak gravitational lensing survey of background sources. We describe a new combination of such observations that in principle this yields a measure of the growth rate that is free of sample variance, i.e. the uncertainty in G can be reduced without bound by increasing themore » number of redshifts obtained within a finite survey volume. The addition of background weak lensing data to a redshift survey increases information on G by an amount equivalent to a 10-fold increase in the volume of a standard redshift-space distortion measurement - if the lensing signal can be measured to sub-per cent accuracy. This argues that a combined lensing and redshift survey over a common low-redshift volume of the Universe is a more powerful test of general relativity than an isolated redshift survey over larger volume at high redshift, especially as surveys begin to cover most of the available sky.« less

  7. Cosmology without cosmic variance

    SciTech Connect

    Bernstein, Gary M.; Cai, Yan -Chuan

    2011-10-01

    The growth of structures in the Universe is described by a function G that is predicted by the combination of the expansion history of the Universe and the laws of gravity within it. We examine the improvements in constraints on G that are available from the combination of a large-scale galaxy redshift survey with a weak gravitational lensing survey of background sources. We describe a new combination of such observations that in principle this yields a measure of the growth rate that is free of sample variance, i.e. the uncertainty in G can be reduced without bound by increasing the number of redshifts obtained within a finite survey volume. The addition of background weak lensing data to a redshift survey increases information on G by an amount equivalent to a 10-fold increase in the volume of a standard redshift-space distortion measurement - if the lensing signal can be measured to sub-per cent accuracy. This argues that a combined lensing and redshift survey over a common low-redshift volume of the Universe is a more powerful test of general relativity than an isolated redshift survey over larger volume at high redshift, especially as surveys begin to cover most of the available sky.

  8. Variance Components in Discrete Force Production Tasks

    PubMed Central

    SKM, Varadhan; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2010-01-01

    tasks was associated with better adjustments of the timing accuracy, which helps achieve comparable force variance in tasks with different rates of force production. This does not happen in discrete tasks. The lack of scaling of the anticipatory changes in the synergy index with ramp time represent is the first reported feature that distinguishes anticipatory synergy adjustments from anticipatory postural adjustments. We discuss the differences between the cyclic and discrete tasks within a hierarchical control scheme offered by Schöner. PMID:20680251

  9. Application of Circulation Control Technology to Airframe Noise Reduction

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Sankar, L. N.; Englar, R. J.; Munro, Scott E.; Li, Yi; Gaeta, R. J.

    2003-01-01

    This report is a summary of the work performed by Georgia Tech Research Institute (GTRI) under NASA Langley Grant NAG-1-2146, which was awarded as a part of NASA's Breakthrough Innovative Technologies (BIT) initiative. This was a three-year program, with a one-year no-cost extension. Each year's study has been an integrated effort consisting of computational fluid dynamics, experimental aerodynamics, and detailed noise and flow measurements. Year I effort examined the feasibility of reducing airframe noise by replacing the conventional wing systems with a Circulation Control Wing (CCW), where steady blowing was used through the trailing edge of the wing over a Coanda surface. It was shown that the wing lift increases with CCW blowing and indeed for the same lift, a CCW wing was shown to produce less noise. Year 2 effort dealt with a similar study on the role of pulsed blowing on airframe noise. The main objective of this portion of the study was to assess whether pulse blowing from the trailing edge of a CCW resulted in more, less, or the same amount of radiated noise to the farfield. Results show that a reduction in farfield noise of up to 5 dB is measured when pulse flow is compared with steady flow for an equivalent lift configuration. This reduction is in the spectral region associated with the trailing edge jet noise. This result is due to the unique advantage that pulsed flow has over steady flow. For a range of frequencies, more lift is experienced with the same mass flow as the steady case. Thus, for an equivalent lift and slot height, the pulsed system can operate at lower jet velocities, and hence lower jet noise. The computational analysis showed that for a given time-averaged mass flow rate, pulsed jets give a higher value of C(sub l) and a higher L/D than equivalent steady jets. This benefit is attributable to higher instantaneous jet velocities, and higher instantaneous C(sub mu) values for the pulsed jet. Pulsed jet benefits increase at higher

  10. The Space Technology-7 Disturbance Reduction System Precision Control Flight Validation Experiment Control System Design

    NASA Technical Reports Server (NTRS)

    O'Donnell, James R.; Hsu, Oscar C.; Maghami, Peirman G.; Markley, F. Landis

    2006-01-01

    As originally proposed, the Space Technology-7 Disturbance Reduction System (DRS) project, managed out of the Jet Propulsion Laboratory, was designed to validate technologies required for future missions such as the Laser Interferometer Space Antenna (LISA). The two technologies to be demonstrated by DRS were Gravitational Reference Sensors (GRSs) and Colloidal MicroNewton Thrusters (CMNTs). Control algorithms being designed by the Dynamic Control System (DCS) team at the Goddard Space Flight Center would control the spacecraft so that it flew about a freely-floating GRS test mass, keeping it centered within its housing. For programmatic reasons, the GRSs were descoped from DRS. The primary goals of the new mission are to validate the performance of the CMNTs and to demonstrate precise spacecraft position control. DRS will fly as a part of the European Space Agency (ESA) LISA Pathfinder (LPF) spacecraft along with a similar ESA experiment, the LISA Technology Package (LTP). With no GRS, the DCS attitude and drag-free control systems make use of the sensor being developed by ESA as a part of the LTP. The control system is designed to maintain the spacecraft s position with respect to the test mass, to within 10 nm/the square root of Hz over the DRS science frequency band of 1 to 30 mHz.

  11. Turbulent Drag Reduction: Studies of Feedback Control and Flow Over Riblets

    NASA Astrophysics Data System (ADS)

    Choi, Haecheon

    The objective of this study is to explore concepts for control of turbulent boundary layers leading to skin -friction reduction using the direct numerical simulation technique. This report is divided into three parts where three different control methods are investigated; a passive control by longitudinal riblets, an active control by sensing and perturbing structures near the wall, and a feedback control procedure guided by control theory. In PART I significant drag reduction is achieved when the surface boundary condition is modified to suppress the dynamically significant coherent structures present in the wall region. The drag reduction is accompanied with significant reduction in the intensity of the wall -layer structures and reductions in the magnitude of Reynolds shear stress throughout the flow. Two essential drag reduction mechanisms are presented. In PART II mathematical methods of control theory are applied to the problem of control of fluid flow. The procedure of how to cast the problem of controlling turbulence into a problem in optimal control theory is presented through the formalism and language of control theory. Then a suboptimal control and feedback procedure are presented using methods of calculus of variations through the adjoint state and gradient algorithms. This suboptimal feedback control procedure is applied to the distributed and boundary controls of the stochastic Burgers equation. Most cases considered show significant reductions of the costs. In PART III direct numerical simulation is performed to analyze turbulent flow over longitudinal riblets, and to educe the mechanism of drag reduction by riblets. The computed drags on the riblet surfaces are in good agreement with the existing experimental data. Differences in the mean-velocity profile and turbulence quantities are found to be limited to the inner region of the boundary layer. Velocity and vorticity fluctuations as well as the Reynolds shear stresses above the riblets are

  12. Budget variance analysis using RVUs.

    PubMed

    Berlin, M F; Budzynski, M R

    1998-01-01

    This article details the use of the variance analysis as management tool to evaluate the financial health of the practice. A common financial tool for administrators has been a simple calculation measuring the difference between actual financials vs. budget financials. Standard cost accounting provides a methodology known as variance analysis to better understand the actual vs. budgeted financial streams. The standard variance analysis has been modified by applying relative value units (RVUs) as standards for the practice. PMID:10387247

  13. Energy scaling and reduction in controlling complex networks.

    PubMed

    Chen, Yu-Zhong; Wang, Le-Zhi; Wang, Wen-Xu; Lai, Ying-Cheng

    2016-04-01

    Recent works revealed that the energy required to control a complex network depends on the number of driving signals and the energy distribution follows an algebraic scaling law. If one implements control using a small number of drivers, e.g. as determined by the structural controllability theory, there is a high probability that the energy will diverge. We develop a physical theory to explain the scaling behaviour through identification of the fundamental structural elements, the longest control chains (LCCs), that dominate the control energy. Based on the LCCs, we articulate a strategy to drastically reduce the control energy (e.g. in a large number of real-world networks). Owing to their structural nature, the LCCs may shed light on energy issues associated with control of nonlinear dynamical networks. PMID:27152220

  14. Energy scaling and reduction in controlling complex networks

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Zhong; Wang, Le-Zhi; Wang, Wen-Xu; Lai, Ying-Cheng

    2016-04-01

    Recent works revealed that the energy required to control a complex network depends on the number of driving signals and the energy distribution follows an algebraic scaling law. If one implements control using a small number of drivers, e.g. as determined by the structural controllability theory, there is a high probability that the energy will diverge. We develop a physical theory to explain the scaling behaviour through identification of the fundamental structural elements, the longest control chains (LCCs), that dominate the control energy. Based on the LCCs, we articulate a strategy to drastically reduce the control energy (e.g. in a large number of real-world networks). Owing to their structural nature, the LCCs may shed light on energy issues associated with control of nonlinear dynamical networks.

  15. Statistical tests against systematic errors in data sets based on the equality of residual means and variances from control samples: theory and applications.

    PubMed

    Henn, Julian; Meindl, Kathrin

    2015-03-01

    Statistical tests are applied for the detection of systematic errors in data sets from least-squares refinements or other residual-based reconstruction processes. Samples of the residuals of the data are tested against the hypothesis that they belong to the same distribution. For this it is necessary that they show the same mean values and variances within the limits given by statistical fluctuations. When the samples differ significantly from each other, they are not from the same distribution within the limits set by the significance level. Therefore they cannot originate from a single Gaussian function in this case. It is shown that a significance cutoff results in exactly this case. Significance cutoffs are still frequently used in charge-density studies. The tests are applied to artificial data with and without systematic errors and to experimental data from the literature.

  16. Biogeochemical Processes Controlling Microbial Reductive Precipitation of Radionuclides

    SciTech Connect

    Fredrickson, James K.; Brooks, Scott C.

    2004-03-17

    This project is focused on elucidating the principal biogeochemical reactions that govern the concentrations, chemical speciation, and distribution of the redox sensitive contaminants uranium (U) and technetium (Tc) between the aqueous and solid phases. The research is designed to provide new insights into the under-explored areas of competing geochemical and microbiological oxidation-reduction reactions that govern the fate and transport of redox sensitive contaminants and to generate fundamental scientific understanding of the identity and stoichiometry of competing microbial reduction and geochemical oxidation reactions. These goals and objectives are met through a series of hypothesis-driven tasks that focus on (1) the use of well-characterized microorganisms and synthetic and natural mineral oxidants, (2) advanced spectroscopic and microscopic techniques to monitor redox transformations of U and Tc, and (3) the use of flow-through experiments to more closely approximate groundwater environments. The results are providing an improved understanding and predictive capability of the mechanisms that govern the redox dynamics of radionuclides in subsurface environments. For purposes of this poster, the results are divided into three sections: (1) influence of Ca on U(VI) bioreduction; (2) localization of biogenic UO{sub 2} and TcO{sub 2}; and (3) reactivity of Mn(III/IV) oxides.

  17. Multiple Comparison Procedures when Population Variances Differ.

    ERIC Educational Resources Information Center

    Olejnik, Stephen; Lee, JaeShin

    A review of the literature on multiple comparison procedures suggests several alternative approaches for comparing means when population variances differ. These include: (1) the approach of P. A. Games and J. F. Howell (1976); (2) C. W. Dunnett's C confidence interval (1980); and (3) Dunnett's T3 solution (1980). These procedures control the…

  18. Sampling Errors of Variance Components.

    ERIC Educational Resources Information Center

    Sanders, Piet F.

    A study on sampling errors of variance components was conducted within the framework of generalizability theory by P. L. Smith (1978). The study used an intuitive approach for solving the problem of how to allocate the number of conditions to different facets in order to produce the most stable estimate of the universe score variance. Optimization…

  19. Control strategies for afterload reduction with an artificial vasculature device.

    PubMed

    Giridharan, Guruprasad A; Cheng, Rolando Chip; Glower, Jacob S; Ewert, Daniel L; Sobieski, Michael A; Slaughter, Mark S; Koenig, Steven C

    2012-01-01

    Ventricular assist devices (VADs) have been used successfully as a bridge to transplant in heart failure patients by unloading ventricular volume and restoring the circulation. An artificial vasculature device (AVD) is being developed that may better facilitate myocardial recovery than VAD by controlling the afterload experienced by the native heart and controlling the pulsatile energy entering into the arterial system from the device, potentially reconditioning the arterial system properties. The AVD is a valveless, 80 ml blood chamber with a servo-controlled pusher plate connected to the ascending aorta by a vascular graft. Control algorithms for the AVD were developed to maintain any user-defined systemic input impedance (IM) including resistance, elastance, and inertial components. Computer simulation and mock circulation models of the cardiovascular system were used to test the efficacy of two control strategies for the AVD: 1) average impedance position control (AIPC)-to maintain an average value of resistance during left ventricular (LV) systole and 2) instantaneous impedance force feedback (IIFF) and position control (IIPC)-to maintain a desired value or profile of resistance and compliance. Computer simulations and mock loop tests were performed to predict resulting cardiovascular pressures, volumes, flows, and the resistance and compliance experienced by the native LV during ejection for simulated normal, failing, and recovering LV. These results indicate that the LV volume and pressure decreased, and the LV stroke volume increased with decreasing IM, resulting in an increased ejection fraction. Although the AIPC algorithm is more stable and can tolerate higher levels of sensor errors and noise, the IIFF and IIPC control algorithms are better suited to maintain any instantaneous IM or an IM profile. The developed AVD impedance control algorithms may be implemented with current VADs to promote myocardial recovery and facilitate weaning. PMID:22635010

  20. Control strategies for afterload reduction with an artificial vasculature device.

    PubMed

    Giridharan, Guruprasad A; Cheng, Rolando Chip; Glower, Jacob S; Ewert, Daniel L; Sobieski, Michael A; Slaughter, Mark S; Koenig, Steven C

    2012-01-01

    Ventricular assist devices (VADs) have been used successfully as a bridge to transplant in heart failure patients by unloading ventricular volume and restoring the circulation. An artificial vasculature device (AVD) is being developed that may better facilitate myocardial recovery than VAD by controlling the afterload experienced by the native heart and controlling the pulsatile energy entering into the arterial system from the device, potentially reconditioning the arterial system properties. The AVD is a valveless, 80 ml blood chamber with a servo-controlled pusher plate connected to the ascending aorta by a vascular graft. Control algorithms for the AVD were developed to maintain any user-defined systemic input impedance (IM) including resistance, elastance, and inertial components. Computer simulation and mock circulation models of the cardiovascular system were used to test the efficacy of two control strategies for the AVD: 1) average impedance position control (AIPC)-to maintain an average value of resistance during left ventricular (LV) systole and 2) instantaneous impedance force feedback (IIFF) and position control (IIPC)-to maintain a desired value or profile of resistance and compliance. Computer simulations and mock loop tests were performed to predict resulting cardiovascular pressures, volumes, flows, and the resistance and compliance experienced by the native LV during ejection for simulated normal, failing, and recovering LV. These results indicate that the LV volume and pressure decreased, and the LV stroke volume increased with decreasing IM, resulting in an increased ejection fraction. Although the AIPC algorithm is more stable and can tolerate higher levels of sensor errors and noise, the IIFF and IIPC control algorithms are better suited to maintain any instantaneous IM or an IM profile. The developed AVD impedance control algorithms may be implemented with current VADs to promote myocardial recovery and facilitate weaning.

  1. Actively Controlled Landing Gear for Aircraft Vibration Reduction

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Daugherty, Robert H.; Martinson, Veloria J.

    1999-01-01

    Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads using actively controlled landing gears. A facility has been developed to test various active landing gear control concepts and their performance. The facility uses a NAVY A6-intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented including modifications to actuate the gear externally and test data is used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  2. Reduction of hinge moments of airplane control surfaces by tabs

    NASA Technical Reports Server (NTRS)

    Harris, Thomas A

    1936-01-01

    This report presents the results of an investigation conducted in the NACA 7 by 10-foot wind tunnel of control surfaces equipped with tabs for reducing the control forces or trimming the aircraft. Two sizes of ordinary ailerons with several sizes of attached and inset tabs were tested on a Clark y wing. Tabs were also tested in combination with auxiliary balances of the horn and paddle types, and with a frise balance aileron. A tail-surface model of symmetrical section, equipped with tabs, was tested with 40 percent of the area movable (elevator) when used as a horizontal tail and 60 percent of the area movable (rudder) when used as a vertical tail. The half-span tail-surface model was tested with and without a reflection plane. The results of the tests indicated that inset tabs were superior to attached tabs for the same ratio of tab/control surface deflection.

  3. Ripple reduction control of the undulation pump total artificial heart.

    PubMed

    Saito, Itsuro; Chinzei, Tsuneo; Mochizuki, Shuichi; Abe, Yusuke; Isoyama, Takashi; Iwasaki, Kiyotaka; Suzuki, Takafumi; Karita, Tatsuro; Ono, Toshiya; Kouno, Akimasa; Ishimaru, Mitsuhiko; Baba, Atsushi; Ozeki, Toshinaga; Tohyama, Takahiro; Kobayashi Si, Shin-ichi; Imachi, Kou

    2002-01-01

    An undulation pump total artificial heart (UPTAH) in which the revolutions of the motor are converted to undulation motion of a disk has been developed. In an experiment, a goat using the UPTAH survived for 54 days. However, a large ripple was observed in the device's output pressure and flow waveform. In calculating the spectrum of the ripple, we found that the ripple mainly comprised 2 frequency sine waves: 1 having the same frequency as and 1 having double the frequency of the motor revolutions. To reduce the ripple, 2 sine waves, 1 having the same frequency as and 1 having double the frequency of the motor revolutions, were provided to the motor current to modulate the pulse width of the pulse width modulation controlling the motor revolutions. This ripple control method reduced the pressure ripple by 90% in a mock circulation and by 70% in animal experiments. These results revealed that the ripple generated in the UPTAH could be controlled through the use of motor control software.

  4. Thermal study of battery charge control by temperature derivative reduction

    NASA Astrophysics Data System (ADS)

    Halkjaerjacobsen, P.; Schmidt, K. A.; Otto, S.; Dudley, G. J.; Spruijt, H. J. N.

    1989-08-01

    A battery charge control technique, invented at ESTEC in 1983, which relies upon the changes in the battery cell temperature time derivative which accompany the onset of overcharge is described. A thermally realistic portion of a typical flight battery is constructed and tested in parallel with detailed thermal modeling in order to develop the technique further. Comparisons between thermal model and test results are presented and show satisfactory agreement. Optimum positions for the temperature sensors within the battery are identified, taking into account sensitivity to cell temperature changes as well as to thermal perturbations due to external effects.

  5. Integrated instrumentation and control digital upgrades for cost reduction

    SciTech Connect

    Naser, J.

    1995-03-01

    Most nuclear power plants continue to operate with analog instrumentation and control technology designed 20 to 40 years ago. This equipment is approaching or exceeding its life expectancy, resulting in increasing maintenance efforts to sustain system performance. Decreasing availability of replacement parts and the accelerating deterioration of the infrastructure of manufacturers that support analog technology exacerbate obsolescence problems and resultant operation and maintenance cost increases. Modern digital technology holds a significant potential to improve the safety, cost-effectiveness, productivity, and; therefore, competitiveness of nuclear power plants. Reliable, integrated information is a critical element for protecting the utility`s capital investment and increasing availability, reliability, and productivity. Integrated systems with integrated information can perform more effectively to increase productivity, to enhance safety, and to reduce operation and maintenance costs. The plant communications and computing architecture is the infrastructure needed to allow the implementation of instrumentation and control systems in an integrated manner. Modern technology for distributed digital systems, plant process computers, and plant networks support the integration of systems and information.

  6. 29 CFR 1904.45 - OMB control numbers under the Paperwork Reduction Act

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Management and Budget under the control number listed 29 CFR citation OMB Control No. 1904.4-35 1218-0176... 29 Labor 5 2011-07-01 2011-07-01 false OMB control numbers under the Paperwork Reduction Act 1904.45 Section 1904.45 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  7. 29 CFR 1904.45 - OMB control numbers under the Paperwork Reduction Act

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Management and Budget under the control number listed 29 CFR citation OMB Control No. 1904.4-35 1218-0176... 29 Labor 5 2010-07-01 2010-07-01 false OMB control numbers under the Paperwork Reduction Act 1904.45 Section 1904.45 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  8. 29 CFR 1915.8 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of Management and Budget under the control number listed. 29 CFR citation OMB control No. 1915.11... 29 Labor 7 2010-07-01 2010-07-01 false OMB control numbers under the Paperwork Reduction Act. 1915.8 Section 1915.8 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  9. 29 CFR 1910.8 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS General § 1910.8 OMB control numbers... number listed. 29 CFR citation OMB control No. 1910.7 1218-0147 1910.23 1218-0199 1910.66 1218-0121 1910... 29 Labor 5 2010-07-01 2010-07-01 false OMB control numbers under the Paperwork Reduction Act....

  10. 29 CFR 1915.8 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of Management and Budget under the control number listed. 29 CFR citation OMB control No. 1915.11... 29 Labor 7 2013-07-01 2013-07-01 false OMB control numbers under the Paperwork Reduction Act. 1915.8 Section 1915.8 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  11. 29 CFR 1904.45 - OMB control numbers under the Paperwork Reduction Act

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Management and Budget under the control number listed 29 CFR citation OMB Control No. 1904.4-35 1218-0176... 29 Labor 5 2012-07-01 2012-07-01 false OMB control numbers under the Paperwork Reduction Act 1904.45 Section 1904.45 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  12. Method of controlled reduction of nitroaromatics by enzymatic reaction with oxygen sensitive nitroreductase enzymes

    DOEpatents

    Shah, M.M.; Campbell, J.A.

    1998-07-07

    A method is described for the controlled reduction of nitroaromatic compounds such as nitrobenzene and 2,4,6-trinitrotoluene by enzymatic reaction with oxygen sensitive nitroreductase enzymes, such as ferredoxin NADP oxidoreductase. 6 figs.

  13. Method of controlled reduction of nitroaromatics by enzymatic reaction with oxygen sensitive nitroreductase enzymes

    DOEpatents

    Shah, Manish M.; Campbell, James A.

    1998-01-01

    A method for the controlled reduction of nitroaromatic compounds such as nitrobenzene and 2,4,6-trinitrotoluene by enzymatic reaction with oxygen sensitive nitroreductase enzymes, such as ferredoxin NADP oxidoreductase.

  14. Reduction of chronic abdominal pain in patients with inflammatory bowel disease through transcranial direct current stimulation: a randomized controlled trial.

    PubMed

    Volz, Magdalena S; Farmer, Annabelle; Siegmund, Britta

    2016-02-01

    Inflammatory bowel disease (IBD) is frequently associated with chronic abdominal pain (CAP). Transcranial direct current stimulation (tDCS) has been proven to reduce chronic pain. This study aimed to investigate the effects of tDCS in patients with CAP due to IBD. This randomized, sham-controlled, double blind, parallel-designed study included 20 patients with either Crohn disease or ulcerative colitis with CAP (≥3/10 on the visual analog scale (VAS) in 3/6 months). Anodal or sham tDCS was applied over the primary motor cortex for 5 consecutive days (2 mA, 20 minutes). Assessments included VAS, pressure pain threshold, inflammatory markers, and questionnaires on quality of life, functional and disease specific symptoms (Irritable Bowel Syndrome-Severity Scoring System [IBS-SSS]), disease activity, and pain catastrophizing. Follow-up data were collected 1 week after the end of the stimulation. Statistical analyses were performed using analysis of variance and t tests. There was a significant reduction of abdominal pain in the anodal tDCS group compared with sham tDCS. This effect was evident in changes in VAS and pressure pain threshold on the left and right sides of the abdomen. In addition, 1 week after stimulation, pain reduction remained significantly decreased in the right side of the abdomen. There was also a significant reduction in scores on pain catastrophizing and on IBS-SSS when comparing both groups. Inflammatory markers and disease activity did not differ significantly between groups throughout the experiment. Transcranial direct current stimulation proved to be an effective and clinically relevant therapeutic strategy for CAP in IBD. The analgesic effects observed are unrelated to inflammation and disease activity, which emphasizes central pain mechanisms in CAP.

  15. Pipeline reductions of VLTI/MIDI data and quality control

    NASA Astrophysics Data System (ADS)

    Hummel, Christian A.; Percheron, Isabelle

    2006-06-01

    Since April of 2004, the MIDI mid-infrared beam combiner has been used on the VLTI of the European Southern Observatory on Cerro Paranal for service and visitor mode observations. All calibrator data taken are in the public archive, and tools are being developed and used by Paranal Science Operations and Garching Data Flow Operations and Quality Control to study instrument performance and provide users with nightly performance parameters. These tools are also available to the visitors of Paranal. We report on strategies and results for the first interferometric instrument which had been offered to the astronomical community in service mode. That operation model, with users not necessarily experts in interferometry, deserves special attention to the issues of successful use and reliability of the data.

  16. Reduction of interior sound fields in flexible cylinders by active vibration control

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1988-01-01

    The mechanisms of interior sound reduction through active control of a thin flexible shell's vibrational response are presently evaluated in view of an analytical model. The noise source is a single exterior acoustic monopole. The active control model is evaluated for harmonic excitation; the results obtained indicate spatially-averaged noise reductions in excess of 20 dB over the source plane, for acoustic resonant conditions inside the cavity.

  17. Identifying sensitive sources and key control handles for the reduction of greenhouse gas emissions from wastewater treatment.

    PubMed

    Sweetapple, Christine; Fu, Guangtao; Butler, David

    2014-10-01

    This research investigates the effects of adjusting control handle values on greenhouse gas emissions from wastewater treatment, and reveals critical control handles and sensitive emission sources for control through the combined use of local and global sensitivity analysis methods. The direction of change in emissions, effluent quality and operational cost resulting from variation of control handles individually is determined using one-factor-at-a-time sensitivity analysis, and corresponding trade-offs are identified. The contribution of each control handle to variance in model outputs, taking into account the effects of interactions, is then explored using a variance-based sensitivity analysis method, i.e., Sobol's method, and significant second order interactions are discovered. This knowledge will assist future control strategy development and aid an efficient design and optimisation process, as it provides a better understanding of the effects of control handles on key performance indicators and identifies those for which dynamic control has the greatest potential benefits. Sources with the greatest variance in emissions, and therefore the greatest need to monitor, are also identified. It is found that variance in total emissions is predominantly due to changes in direct N2O emissions and selection of suitable values for wastage flow rate and aeration intensity in the final activated sludge reactor is of key importance. To improve effluent quality, costs and/or emissions, it is necessary to consider the effects of adjusting multiple control handles simultaneously and determine the optimum trade-off.

  18. Identifying sensitive sources and key control handles for the reduction of greenhouse gas emissions from wastewater treatment.

    PubMed

    Sweetapple, Christine; Fu, Guangtao; Butler, David

    2014-10-01

    This research investigates the effects of adjusting control handle values on greenhouse gas emissions from wastewater treatment, and reveals critical control handles and sensitive emission sources for control through the combined use of local and global sensitivity analysis methods. The direction of change in emissions, effluent quality and operational cost resulting from variation of control handles individually is determined using one-factor-at-a-time sensitivity analysis, and corresponding trade-offs are identified. The contribution of each control handle to variance in model outputs, taking into account the effects of interactions, is then explored using a variance-based sensitivity analysis method, i.e., Sobol's method, and significant second order interactions are discovered. This knowledge will assist future control strategy development and aid an efficient design and optimisation process, as it provides a better understanding of the effects of control handles on key performance indicators and identifies those for which dynamic control has the greatest potential benefits. Sources with the greatest variance in emissions, and therefore the greatest need to monitor, are also identified. It is found that variance in total emissions is predominantly due to changes in direct N2O emissions and selection of suitable values for wastage flow rate and aeration intensity in the final activated sludge reactor is of key importance. To improve effluent quality, costs and/or emissions, it is necessary to consider the effects of adjusting multiple control handles simultaneously and determine the optimum trade-off. PMID:24960125

  19. Interior Noise Reduction by Adaptive Feedback Vibration Control

    NASA Technical Reports Server (NTRS)

    Lim, Tae W.

    1998-01-01

    The objective of this project is to investigate the possible use of adaptive digital filtering techniques in simultaneous, multiple-mode identification of the modal parameters of a vibrating structure in real-time. It is intended that the results obtained from this project will be used for state estimation needed in adaptive structural acoustics control. The work done in this project is basically an extension of the work on real-time single mode identification, which was performed successfully using a digital signal processor (DSP) at NASA, Langley. Initially, in this investigation the single mode identification work was duplicated on a different processor, namely the Texas Instruments TMS32OC40 DSP. The system identification results for the single mode case were very good. Then an algorithm for simultaneous two mode identification was developed and tested using analytical simulation. When it successfully performed the expected tasks, it was implemented in real-time on the DSP system to identify the first two modes of vibration of a cantilever aluminum beam. The results of the simultaneous two mode case were good but some problems were identified related to frequency warping and spurious mode identification. The frequency warping problem was found to be due to the bilinear transformation used in the algorithm to convert the system transfer function from the continuous-time domain to the discrete-time domain. An alternative approach was developed to rectify the problem. The spurious mode identification problem was found to be associated with high sampling rates. Noise in the signal is suspected to be the cause of this problem but further investigation will be needed to clarify the cause. For simultaneous identification of more than two modes, it was found that theoretically an adaptive digital filter can be designed to identify the required number of modes, but the algebra became very complex which made it impossible to implement in the DSP system used in this study

  20. Reduction of Helicopter Blade-Vortex Interaction Noise by Active Rotor Control Technology

    NASA Technical Reports Server (NTRS)

    Yu, Yung H.; Gmelin, Bernd; Splettstoesser, Wolf; Brooks, Thomas F.; Philippe, Jean J.; Prieur, Jean

    1997-01-01

    Helicopter blade-vortex interaction noise is one of the most severe noise sources and is very important both in community annoyance and military detection. Research over the decades has substantially improved basic physical understanding of the mechanisms generating rotor blade-vortex interaction noise and also of controlling techniques, particularly using active rotor control technology. This paper reviews active rotor control techniques currently available for rotor blade vortex interaction noise reduction, including higher harmonic pitch control, individual blade control, and on-blade control technologies. Basic physical mechanisms of each active control technique are reviewed in terms of noise reduction mechanism and controlling aerodynamic or structural parameters of a blade. Active rotor control techniques using smart structures/materials are discussed, including distributed smart actuators to induce local torsional or flapping deformations, Published by Elsevier Science Ltd.

  1. An overview of flow control for fan noise reduction

    NASA Astrophysics Data System (ADS)

    Langford, Matthew; Burdisso, R. A.; Ng, W.

    2005-09-01

    The dominant tonal noise source from modern high-bypass-ratio turbofan aircraft engines is due to the impingement of viscous fan rotor wakes onto the downstream stator row. Prior research conducted at NASA Glenn Research Center's Active Noise Control Fan (ANCF) rig has demonstrated that significant tonal noise attenuation can be achieved by injecting 1.2% to 1.8% of the fan throughflow along a slot in the trailing edge of the rotor. Efforts presented in this paper have focused on reducing the required blowing mass flow while maintaining equivalent noise attenuation levels. Two primary approaches were investigated: blowing in circumferentially non-uniform patterns (i.e., blowing on every other blade), and optimizing the injection scheme itself. The concept of blowing on alternate rotors was experimentally tested in the ANCF rig using NASA's current slot-blown rotors, and improved attenuation efficiencies were found (although the overall attenuation levels were less). Cascade wind tunnel tests of several different injection schemes were conducted, and the best-performing configuration was incorporated into a new rotor design for experimental validation in the ANCF rig. These rotors achieved similar tonal noise attenuation levels as the slot-blown configuration, but they required injecting less than 0.75% of the fan throughflow.

  2. Controller design for wind turbine load reduction via multiobjective parameter synthesis

    NASA Astrophysics Data System (ADS)

    Hoffmann, A. F.; Weiβ, F. A.

    2016-09-01

    During the design process for a wind turbine load reduction controller many different, sometimes conflicting requirements must be fulfilled simultaneously. If the requirements can be expressed as mathematical criteria, such a design problem can be solved by a criterion-vector and multi-objective design optimization. The software environment MOPS (Multi-Objective Parameter Synthesis) supports the engineer for such a design optimization. In this paper MOPS is applied to design a multi-objective load reduction controller for the well-known DTU 10 MW reference wind turbine. A significant reduction in the fatigue criteria especially the blade damage can be reached by the use of an additional Individual Pitch Controller (IPC) and an additional tower damper. This reduction is reached as a trade-off with an increase of actuator load.

  3. Climate Control Load Reduction Strategies for Electric Drive Vehicles in Warm Weather

    SciTech Connect

    Jeffers, M. A.; Chaney, L.; Rugh, J. P.

    2015-04-30

    Passenger compartment climate control is one of the largest auxiliary loads on a vehicle. Like conventional vehicles, electric vehicles (EVs) require climate control to maintain occupant comfort and safety, but cabin heating and air conditioning have a negative impact on driving range for all electric vehicles. Range reduction caused by climate control and other factors is a barrier to widespread adoption of EVs. Reducing the thermal loads on the climate control system will extend driving range, thereby reducing consumer range anxiety and increasing the market penetration of EVs. Researchers at the National Renewable Energy Laboratory have investigated strategies for vehicle climate control load reduction, with special attention toward EVs. Outdoor vehicle thermal testing was conducted on two 2012 Ford Focus Electric vehicles to evaluate thermal management strategies for warm weather, including solar load reduction and cabin pre-ventilation. An advanced thermal test manikin was used to assess a zonal approach to climate control. In addition, vehicle thermal analysis was used to support testing by exploring thermal load reduction strategies, evaluating occupant thermal comfort, and calculating EV range impacts. Through stationary cooling tests and vehicle simulations, a zonal cooling configuration demonstrated range improvement of 6%-15%, depending on the drive cycle. A combined cooling configuration that incorporated thermal load reduction and zonal cooling strategies showed up to 33% improvement in EV range.

  4. Skid Prevention Control for IPMSM Driven EVs Based on Improved Torque Reduction Characteristics

    NASA Astrophysics Data System (ADS)

    Satake, Masamitsu; Kawashima, Kiyotaka; Uchida, Toshiyuki; Hori, Yoichi

    In this paper, skid prevention control based on torque reduction is proposed for EVs driven by an IPMSM. The traction characteristics of the electric vehicle are improved by using a modified current controller to rapidly reduce the torque of the driving motor. In order to compensate for back-EMF, a disturbance observer is introduced. In addition, we propose skid prevention for an IPMSM by torque reduction using both the dq-axes currents. Further, we verify the effect of each control method by conducting experiments in which the electric vehicle is driven on a slippery road.

  5. 27 CFR 19.1010 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false OMB control numbers... Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Paperwork Reduction Act § 19.1010 OMB control numbers assigned pursuant to the Paperwork...

  6. 29 CFR 1917.4 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., 2001. The list follows: 29 CFR citation OMB control number. 1917.17(n) 1218-0196 1917.17(o) 1218-0196... 29 Labor 7 2013-07-01 2013-07-01 false OMB control numbers under the Paperwork Reduction Act. 1917.4 Section 1917.4 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...

  7. 46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Reduction Act. 540.91 Section 540.91 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN... that agencies display a current control number assigned by the Director of the Office of Management and Budget (OMB) for each agency information collection requirement: Section Current OMB Control No....

  8. 46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Reduction Act. 540.91 Section 540.91 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN... that agencies display a current control number assigned by the Director of the Office of Management and Budget (OMB) for each agency information collection requirement: Section Current OMB Control No....

  9. 46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Reduction Act. 540.91 Section 540.91 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN... that agencies display a current control number assigned by the Director of the Office of Management and Budget (OMB) for each agency information collection requirement: Section Current OMB Control No....

  10. 46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Reduction Act. 540.91 Section 540.91 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN... that agencies display a current control number assigned by the Director of the Office of Management and Budget (OMB) for each agency information collection requirement: Section Current OMB Control No....

  11. 46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Reduction Act. 540.91 Section 540.91 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN... that agencies display a current control number assigned by the Director of the Office of Management and Budget (OMB) for each agency information collection requirement: Section Current OMB Control No....

  12. 46 CFR 25.01-5 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 25.01-5 Section 25.01-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED... requirement. (b) Display. 46 CFR part or section where identified or described Current OMB control No. §...

  13. Highly controllable and green reduction of graphene oxide to flexible graphene film with high strength

    SciTech Connect

    Wan, Wubo; Zhao, Zongbin; Hu, Han; Gogotsi, Yury; Qiu, Jieshan

    2013-11-15

    Graphical abstract: Highly controllable and green reduction of GO to chemical converted graphene (CCG) was achieved with sodium citrate as a facile reductant. Self-assembly of the as-made CCG sheets results in a flexible CCG film, of which the tensile strength strongly depends on the deoxygenation degree of graphene sheets. - Highlights: • Graphene was synthesized by an effective and environmentally friendly approach. • We introduced a facile X-ray diffraction analysis method to investigate the reduction process from graphene oxide to graphene. • Flexible graphene films were prepared by self-assembly of the graphene sheets. • The strength of the graphene films depends on the reduction degree of graphene. - Abstract: Graphene film with high strength was fabricated by the assembly of graphene sheets derived from graphene oxide (GO) in an effective and environmentally friendly approach. Highly controllable reduction of GO to chemical converted graphene (CCG) was achieved with sodium citrate as a facile reductant, in which the reduction process was monitored by XRD analysis and UV–vis absorption spectra. Self-assembly of the as-made CCG sheets results in a flexible CCG film. This method may open an avenue to the easy and scalable preparation of graphene film with high strength which has promising potentials in many fields where strong, flexible and electrically conductive films are highly demanded.

  14. Thermodynamic Versus Surface Area Control of Microbial Fe(III) Oxide Reduction Kinetics

    NASA Astrophysics Data System (ADS)

    Roden, E. E.

    2003-12-01

    Recent experimental studies of synthetic and natural Fe(III) oxide reduction permit development of conceptual and quantitative models of enzymatic Fe(III) oxide reduction at circumneutral pH that can be compared to and contrasted with established models of abiotic mineral dissolution. The findings collectively support a model for controls on enzymatic reduction that differs fundamentally from those applied to abiotic reductive dissolution as a result of two basic phenomena: (1) the relatively minor influence of oxide mineralogical and thermodynamic properties on surface area-normalized rates of enzymatic reduction compared to abiotic reductive dissolution; and (2) the major limitation which sorption and/or surface precipitation of biogenic Fe(II) on residual oxide and Fe(III)-reducing bacterial cell surfaces poses to enzymatic electron transfer in the presence of excess electron donor. Parallel studies with two major Fe(III)-reducing bacteria genera (Shewanella and Geobacter) lead to common conclusions regarding the importance of these phenomena in regulating the rate and long-term extent of Fe(III) oxide reduction. Although the extent to which these phenomena can be traced to underlying kinetic vs. thermodynamic effects cannot be resolved with current information, models in which rates of enzymatic reduction are limited kinetically by the abundance of "available" oxide surface sites (as controlled by oxide surface area and the abundance of surface-bound Fe(II)) provide an adequate macroscopic description of controls on the initial rate and long-term extent of oxide reduction. In some instances, thermodynamic limitation posed by the accumulation of aqueous reaction end-products (i.e. Fe(II) and alkalinity) must also be invoked to explain observed long-term patterns of reduction. In addition, the abundance of Fe(III)-reducing microorganisms plays an important role in governing rates of reduction and needs to be considered in models of Fe(III) reduction in nonsteady

  15. Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization

    NASA Technical Reports Server (NTRS)

    Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

    2014-01-01

    This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.

  16. Back propagation neural network based control for the heating system of a polysilicon reduction furnace.

    PubMed

    Cheng, Yuhua; Chen, Kai; Bai, Libing; Dai, Meizhi

    2013-12-01

    In this paper, the Back Propagation (BP) neural network based control strategy is proposed for the heating system of a polysilicon reduction furnace. It is applied to obtain the control signal I(d), which is used to adjust the heating power through operations of the silicon core temperature, furnace temperature, silicon core voltage, and resistance of the current control cycle. With the control signal I(d) the polycrystalline silicon can be heated from room temperature to the required temperature smoothly and steadily. The proposed BP network applied in this paper can obtain the accurate control signal I(d) and achieve the precise control purpose. This paper presents the principle of the BP network and demonstrates the effectiveness of the BP network in the heating system of a polysilicon reduction furnace by combining the simulation analysis with experimental results.

  17. Uncovering hidden variance: pair-wise SNP analysis accounts for additional variance in nicotine dependence

    PubMed Central

    Culverhouse, Robert C.; Saccone, Nancy L.; Stitzel, Jerry A.; Wang, Jen C.; Steinbach, Joseph H.; Goate, Alison M.; Schwantes-An, Tae-Hwi; Grucza, Richard A.; Stevens, Victoria L.; Bierut, Laura J.

    2010-01-01

    Results from genome-wide association studies of complex traits account for only a modest proportion of the trait variance predicted to be due to genetics. We hypothesize that joint analysis of polymorphisms may account for more variance. We evaluated this hypothesis on a case–control smoking phenotype by examining pairs of nicotinic receptor single-nucleotide polymorphisms (SNPs) using the Restricted Partition Method (RPM) on data from the Collaborative Genetic Study of Nicotine Dependence (COGEND). We found evidence of joint effects that increase explained variance. Four signals identified in COGEND were testable in independent American Cancer Society (ACS) data, and three of the four signals replicated. Our results highlight two important lessons: joint effects that increase the explained variance are not limited to loci displaying substantial main effects, and joint effects need not display a significant interaction term in a logistic regression model. These results suggest that the joint analyses of variants may indeed account for part of the genetic variance left unexplained by single SNP analyses. Methodologies that limit analyses of joint effects to variants that demonstrate association in single SNP analyses, or require a significant interaction term, will likely miss important joint effects. PMID:21079997

  18. The Variance Reaction Time Model

    ERIC Educational Resources Information Center

    Sikstrom, Sverker

    2004-01-01

    The variance reaction time model (VRTM) is proposed to account for various recognition data on reaction time, the mirror effect, receiver-operating-characteristic (ROC) curves, etc. The model is based on simple and plausible assumptions within a neural network: VRTM is a two layer neural network where one layer represents items and one layer…

  19. Analysis of Variance: Variably Complex

    ERIC Educational Resources Information Center

    Drummond, Gordon B.; Vowler, Sarah L.

    2012-01-01

    These authors have previously described how to use the "t" test to compare two groups. In this article, they describe the use of a different test, analysis of variance (ANOVA) to compare more than two groups. ANOVA is a test of group differences: do at least two of the means differ from each other? ANOVA assumes (1) normal distribution of…

  20. An active control system for helicopter vibration reduction by higher harmonic pitch

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.; Farrar, F. A.; Miao, W.

    1980-01-01

    An analytical study defining the basic configuration of an active control system to reduce helicopter vibrations is presented. Theoretical results for a nonlinear four-bladed single rotor helicopter simulation are discussed, showing that vibration reductions on the order of 80-90% for airspeeds up to 150 kn can be expected when using a higher harmonic pitch in an active feedback control system. The rotor performance penalty associated with this level of vibration reduction is about 1-3% and the increase in rotor blade stresses is considered to be low. The location of sensor accelerometers proved to be significant for vibration reductions, and it is noted that the RTSA controller is tolerant of sensor signal noise.

  1. Population reduction as a factor in the control of skunk rabies in Alberta.

    PubMed

    Rosatte, R C; Pybus, M J; Gunson, J R

    1986-10-01

    Population reduction is being used currently to combat skunk rabies in Alberta. A total of 2,398 striped skunks (Mephitis mephitis) were removed from three counties of southern Alberta during 1980-1983 in an effort to combat rabies outbreaks in those areas. The methods employed included trapping, poisoning, and shooting. Skunks in Forty Mile County have been rabies-free for 4 yr and the outbreaks in Newell and Warner counties appear to be under control. The data suggest that population reduction has been effective in controlling rabies in those areas.

  2. Numerical Investigation of Rotorcraft Fuselage Drag Reduction Using Active Flow Control

    NASA Technical Reports Server (NTRS)

    Allan, Brian G.; Schaeffler, Norman W.

    2011-01-01

    The effectiveness of unsteady zero-net-mass-flux jets for fuselage drag reduction was evaluated numerically on a generic rotorcraft fuselage in forward flight with a rotor. Previous efforts have shown significant fuselage drag reduction using flow control for an isolated fuselage by experiment and numerical simulation. This work will evaluate a flow control strategy, that was originally developed on an isolated fuselage, in a more relevant environment that includes the effects of a rotor. Evaluation of different slot heights and jet velocity ratios were performed. Direct comparisons between an isolated fuselage and rotor/fuselage simulations were made showing similar flow control performance at a -3deg fuselage angle-of-attack condition. However, this was not the case for a -5deg angle-of-attack condition where the performance between the isolated fuselage and rotor/fuselage were different. The fuselage flow control resulted in a 17% drag reduction for a peak C(sub mu) of 0.0069 in a forward flight simulation where mu = 0:35 and CT/sigma = 0:08. The CFD flow control results also predicted a favorable 22% reduction of the fuselage download at this same condition, which can have beneficial compounding effects on the overall performance of the vehicle. This numerical investigation was performed in order to provide guidance for a future 1/3 scale wind tunnel experiment to be performed at the NASA 14-by 22-Foot Subsonic Tunnel.

  3. Torque Ripple Reduction in Direct Torque Control Based Induction Motor using Intelligent Controllers

    NASA Astrophysics Data System (ADS)

    Sudhakar, Ambarapu; Vijaya Kumar, M.

    2015-09-01

    This paper presents intelligent control scheme together with conventional control scheme to overcome the problems with uncertainties in the structure encountered with classical model based design of induction motor drive based on direct torque control (DTC). It allows high dynamic performance to be obtained with very simple hysteresis control scheme. Direct control of the torque and flux is achieved by proper selection of inverter voltage space vector through a lookup table. This paper also presents the application of intelligent controllers like neural network and fuzzy logic controllers to control induction machines with DTC. Intelligent controllers are used to emulate the state selector of the DTC. With implementation of intelligent controllers the system is also verified and proved to be operated stably with reduced torque ripple. The proposed method validity and effectiveness has been verified by computer simulations using Matlab/Simulink®. These results are compared with the ones obtained with a classical DTC using proportional integral speed controller.

  4. Variance decomposition in stochastic simulators

    NASA Astrophysics Data System (ADS)

    Le Maître, O. P.; Knio, O. M.; Moraes, A.

    2015-06-01

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  5. Variance decomposition in stochastic simulators.

    PubMed

    Le Maître, O P; Knio, O M; Moraes, A

    2015-06-28

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  6. Variance decomposition in stochastic simulators

    SciTech Connect

    Le Maître, O. P.; Knio, O. M.; Moraes, A.

    2015-06-28

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  7. Quantitative Cyber Risk Reduction Estimation Methodology for a Small Scada Control System

    SciTech Connect

    Miles A. McQueen; Wayne F. Boyer; Mark A. Flynn; George A. Beitel

    2006-01-01

    We propose a new methodology for obtaining a quick quantitative measurement of the risk reduction achieved when a control system is modified with the intent to improve cyber security defense against external attackers. The proposed methodology employs a directed graph called a compromise graph, where the nodes represent stages of a potential attack and the edges represent the expected time-to-compromise for differing attacker skill levels. Time-to-compromise is modeled as a function of known vulnerabilities and attacker skill level. The methodology was used to calculate risk reduction estimates for a specific SCADA system and for a specific set of control system security remedial actions. Despite an 86% reduction in the total number of vulnerabilities, the estimated time-to-compromise was increased only by about 3 to 30% depending on target and attacker skill level.

  8. The role of harm reduction in controlling HIV among injecting drug users

    PubMed Central

    Wodak, Alex; McLeod, Leah

    2012-01-01

    Injecting drug users (IDU) now account for one in 10 new HIV infections world wide. Yet it has been known since the early 1990s that HIV among IDU can be effectively, safely and cost-effectively controlled by the early and vigorous implementation of a comprehensive package of strategies known as ’harm reduction’. This concept means that decreasing drug-related harms is accorded an even higher priority than reduction of drug consumption. Strategies required involve: explicit and peer-based education about the risk of HIV from sharing injecting equipment; needle syringe programmes; drug treatment (including especially opiate substitution treatment) and community development. Many countries experiencing or threatened by an HIV epidemic among IDU have now adopted harm reduction but often implementation has been too little and too late. Although coverage is slowly improving in many countries, HIV is still spreading faster among IDU than harm reduction programmes while coverage in correctional centres lags far behind community settings. The scientific debate about harm reduction is now over. National and international support for harm reduction is growing while almost all the major UN organizations responsible for drug policy now support harm reduction. Only a small number of countries, led by the USA, are still vehemently opposed to harm reduction. Excessive reliance on drug law enforcement remains the major barrier to increased adoption of harm reduction. Sometimes zealous drug law enforcement undermines harm reduction. A more balanced approach to drug law enforcement is required with illicit drug use recognized primarily as a health and social problem. PMID:18641473

  9. Relating the Hadamard Variance to MCS Kalman Filter Clock Estimation

    NASA Technical Reports Server (NTRS)

    Hutsell, Steven T.

    1996-01-01

    The Global Positioning System (GPS) Master Control Station (MCS) currently makes significant use of the Allan Variance. This two-sample variance equation has proven excellent as a handy, understandable tool, both for time domain analysis of GPS cesium frequency standards, and for fine tuning the MCS's state estimation of these atomic clocks. The Allan Variance does not explicitly converge for the nose types of alpha less than or equal to minus 3 and can be greatly affected by frequency drift. Because GPS rubidium frequency standards exhibit non-trivial aging and aging noise characteristics, the basic Allan Variance analysis must be augmented in order to (a) compensate for a dynamic frequency drift, and (b) characterize two additional noise types, specifically alpha = minus 3, and alpha = minus 4. As the GPS program progresses, we will utilize a larger percentage of rubidium frequency standards than ever before. Hence, GPS rubidium clock characterization will require more attention than ever before. The three sample variance, commonly referred to as a renormalized Hadamard Variance, is unaffected by linear frequency drift, converges for alpha is greater than minus 5, and thus has utility for modeling noise in GPS rubidium frequency standards. This paper demonstrates the potential of Hadamard Variance analysis in GPS operations, and presents an equation that relates the Hadamard Variance to the MCS's Kalman filter process noises.

  10. Neutrino mass without cosmic variance

    NASA Astrophysics Data System (ADS)

    LoVerde, Marilena

    2016-05-01

    Measuring the absolute scale of the neutrino masses is one of the most exciting opportunities available with near-term cosmological data sets. Two quantities that are sensitive to neutrino mass, scale-dependent halo bias b (k ) and the linear growth parameter f (k ) inferred from redshift-space distortions, can be measured without cosmic variance. Unlike the amplitude of the matter power spectrum, which always has a finite error, the error on b (k ) and f (k ) continues to decrease as the number density of tracers increases. This paper presents forecasts for statistics of galaxy and lensing fields that are sensitive to neutrino mass via b (k ) and f (k ). The constraints on neutrino mass from the auto- and cross-power spectra of spectroscopic and photometric galaxy samples are weakened by scale-dependent bias unless a very high density of tracers is available. In the high-density limit, using multiple tracers allows cosmic variance to be beaten, and the forecasted errors on neutrino mass shrink dramatically. In practice, beating the cosmic-variance errors on neutrino mass with b (k ) will be a challenge, but this signal is nevertheless a new probe of neutrino effects on structure formation that is interesting in its own right.

  11. Controlled Reduction with Unactuated Cyclic Variables: Application to 3D Bipedal Walking with Passive Yaw Rotation

    PubMed Central

    Righetti, Ludovic

    2014-01-01

    This paper shows that viscous damping can shape momentum conservation laws in a manner that stabilizes yaw rotation and enables steering for underactuated 3D walking. We first show that unactuated cyclic variables can be controlled by passively shaped conservation laws given a stabilizing controller in the actuated coordinates. We then exploit this result to realize controlled geometric reduction with multiple unactuated cyclic variables. We apply this underactuated control strategy to a five-link 3D biped to produce exponentially stable straight-ahead walking and steering in the presence of passive yawing. PMID:25554709

  12. Fit 5 Kids TV reduction program for Latino preschoolers: A cluster randomized controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing Latino preschoolers' TV viewing is needed to reduce their risk of obesity and other chronic diseases. This study's objective was to evaluate the Fit 5 Kids (F5K) TV reduction program's impact on Latino preschooler's TV viewing. The study design was a cluster randomized controlled trial (RCT...

  13. 46 CFR 167.01-20 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS General Provisions § 167.01-20 OMB control numbers assigned... of Management and Budget (OMB) pursuant to the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  14. 49 CFR 171.6 - Control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... information. (2) Table. Current OMBcontrol No. Title Title 49 CFR part or section where identified and... 49 Transportation 2 2014-10-01 2014-10-01 false Control numbers under the Paperwork Reduction Act... requirements of 5 CFR 1320.7(f), 1320.12, 1320.13 and 1320.14 (OMB regulations implementing the...

  15. 49 CFR 171.6 - Control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... information. (2) Table. Current OMBcontrol No. Title Title 49 CFR part or section where identified and... 49 Transportation 2 2013-10-01 2013-10-01 false Control numbers under the Paperwork Reduction Act... requirements of 5 CFR 1320.7(f), 1320.12, 1320.13 and 1320.14 (OMB regulations implementing the...

  16. 49 CFR 171.6 - Control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... information. (2) Table. Current OMBcontrol No. Title Title 49 CFR part or section where identified and... 49 Transportation 2 2011-10-01 2011-10-01 false Control numbers under the Paperwork Reduction Act... requirements of 5 CFR 1320.7(f), 1320.12, 1320.13 and 1320.14 (OMB regulations implementing the...

  17. 46 CFR 401.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Reduction Act. 401.105 Section 401.105 Shipping COAST GUARD (GREAT LAKES PILOTAGE), DEPARTMENT OF HOMELAND SECURITY GREAT LAKES PILOTAGE REGULATIONS General § 401.105 OMB control numbers assigned pursuant to the... collection requirement. (b) Display. 46 CFR part of section where identified or described Current OMB...

  18. 7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... FOR GRADES OF DAIRY PRODUCTS 1 General Specifications for Dairy Plants Approved for USDA Inspection... 7 CFR part 58, subpart B, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1980, Pub. L. 96-511. 7 CFR section where requirements are described Current OMB control No....

  19. Assessment of methods for methyl iodide emission reduction and pest control using a simulation model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Various methods have been developed to reduce atmospheric emissions from the agricultural use of highly volatile pesticides and mitigate their adverse environmental effects. The effectiveness of various methods on emissions reduction and pest control was assessed using simulation model in this study...

  20. 18 CFR 389.101 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Director of OMB for each agency information collection requirement. (b) Display. 18 CFR part or section... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 389.101 Section 389.101 Conservation of Power and...

  1. 18 CFR 389.101 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Director of OMB for each agency information collection requirement. (b) Display. 18 CFR part or section... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 389.101 Section 389.101 Conservation of Power and...

  2. 18 CFR 389.101 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Director of OMB for each agency information collection requirement. (b) Display. 18 CFR part or section... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 389.101 Section 389.101 Conservation of Power and...

  3. 18 CFR 389.101 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Director of OMB for each agency information collection requirement. (b) Display. 18 CFR part or section... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 389.101 Section 389.101 Conservation of Power and...

  4. INVESTIGATION OF SELECTIVE CATALYTIC REDUCTION IMPACT ON MERCURY SPECIATION UNDER SIMULATED NOX EMISSION CONTROL CONDITIONS

    EPA Science Inventory

    Selective catalytic reduction (SCR) technology is being increasingly applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury in the coal com...

  5. 46 CFR 50.01-20 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 50.01-20 Section 50.01-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... for each approved agency information collection requirement. (b) Display. 46 CFR Part or Section...

  6. 27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Management and Budget contained in 27 CFR Part 25 under the Paperwork Reduction Act of 1980, Pub. L. 96-511... sections in 27 CFR Part 25: §§ 25.23, 25.25, 25.52, 25.61, 25.62, 25.64, 25.66, 25.67, 25.68, 25.71, 25.72... control number 1512-0052. OMB control number 1512-0052 is assigned to the following sections in 27...

  7. 27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Management and Budget contained in 27 CFR Part 25 under the Paperwork Reduction Act of 1980, Pub. L. 96-511... sections in 27 CFR Part 25: §§ 25.23, 25.25, 25.52, 25.61, 25.62, 25.64, 25.66, 25.67, 25.68, 25.71, 25.72... control number 1512-0052. OMB control number 1512-0052 is assigned to the following sections in 27...

  8. Active breathing control (ABC): Determination and reduction of breathing-induced organ motion in the chest

    SciTech Connect

    Gagel, Bernd . E-mail: BGagel@UKAachen.de; Demirel, Cengiz M.P.; Kientopf, Aline; Pinkawa, Michael; Piroth, Marc; Stanzel, Sven; Breuer, Christian; Asadpour, Branka; Jansen, Thomas; Holy, Richard; Wildberger, Joachim E.; Eble, Michael J.

    2007-03-01

    Purpose: Extensive radiotherapy volumes for tumors of the chest are partly caused by interfractional organ motion. We evaluated the feasibility of respiratory observation tools using the active breathing control (ABC) system and the effect on breathing cycle regularity and reproducibility. Methods and Materials: Thirty-six patients with unresectable tumors of the chest were selected for evaluation of the ABC system. Computed tomography scans were performed at various respiratory phases starting at the same couch position without patient movement. Threshold levels were set at minimum and maximum volume during normal breathing cycles and at a volume defined as shallow breathing, reflecting the subjective maximal tolerable reduction of breath volume. To evaluate the extent of organ movement, 13 landmarks were considering using commercial software for image coregistration. In 4 patients, second examinations were performed during therapy. Results: Investigating the differences in a normal breathing cycle versus shallow breathing, a statistically significant reduction of respiratory motion in the upper, middle, and lower regions of the chest could be detected, representing potential movement reduction achieved through reduced breath volume. Evaluating interfraction reproducibility, the mean displacement ranged between 0.24 mm (chest wall/tracheal bifurcation) to 3.5 mm (diaphragm) for expiration and shallow breathing and 0.24 mm (chest wall) to 5.25 mm (diaphragm) for normal inspiration. Conclusions: By modifying regularity of the respiratory cycle through reduction of breath volume, a significant and reproducible reduction of chest and diaphragm motion is possible, enabling reduction of treatment planning margins.

  9. 14 CFR 11.201 - Office of Management and Budget (OMB) control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... PROCEDURES Paperwork Reduction Act Control Numbers § 11.201 Office of Management and Budget (OMB) control... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Office of Management and Budget (OMB) control numbers assigned under the Paperwork Reduction Act. 11.201 Section 11.201 Aeronautics and...

  10. Hybrid modal nodal method for multibody smart structure model reduction: application to modal feedback control

    NASA Astrophysics Data System (ADS)

    Matichard, Fabrice; Gaudiller, Luc

    2006-12-01

    The hybrid modal nodal (HMN) method, designed for multibody smart structure model reduction and feedback control development, is based on the independent modeling of structural and electromechanical behavior. Firstly, this approach permits reducing the model of substructures independently of the electromechanical behavior. This allows choosing the most adapted component mode synthesis (CMS) method and corresponding code for any application, something that is not permitted by classical multi-physics projection-based methods. Thus, the substructuring process used in this paper is based on super-elements directly adapted for multibody dynamics modeling. Secondly, the electromechanical behavior of distributed components is introduced into the structural modal model via a nodal formulation. Its independence of any projection guarantees accuracy and its formulation is valid whatever the multibody assembly and its modal shapes. The proposed application is composed of successive developments and experiments designed to validate the model reduction method, its implementation and its use for modal feedback control, i.e. a smart beam, actively controlled by piezoelectric ceramics. It is successively clamped to illustrate the electromechanical coupling reduction, articulated to introduce the rigid-body/flexible mode coupling reduction and, finally, bi-articulated in order to deal with the nonlinear problem.

  11. Early Implementation of THAM for ICP Control: Therapeutic Hypothermia Avoidance and Reduction in Hypertonics/Hyperosmotics

    PubMed Central

    Zeiler, F. A.; Gillman, L. M.; Teitelbaum, J.; West, M.

    2014-01-01

    Background. Tromethamine (THAM) has been demonstrated to reduce intracranial pressure (ICP). Early consideration for THAM may reduce the need for other measures for ICP control. Objective. To describe 4 cases of early THAM therapy for ICP control and highlight the potential to avoid TH and paralytics and achieve reduction in sedation and hypertonic/hyperosmotic agent requirements. Methods. We reviewed the charts of 4 patients treated with early THAM for ICP control. Results. We identified 2 patients with aneurysmal subarachnoid hemorrhage (SAH) and 2 with traumatic brain injury (TBI) receiving early THAM for ICP control. The mean time to initiation of THAM therapy was 1.8 days, with a mean duration of 5.3 days. In all patients, after 6 to 12 hours of THAM administration, ICP stability was achieved, with reduction in requirements for hypertonic saline and hyperosmotic agents. There was a relative reduction in mean hourly hypertonic saline requirements of 89.1%, 96.1%, 82.4%, and 97.0% for cases 1, 2, 3, and 4, respectively, comparing pre- to post-THAM administration. Mannitol, therapeutic hypothermia, and paralytics were avoided in all patients. Conclusions. Early administration of THAM for ICP control could potentially lead to the avoidance of other ICP directed therapies. Prospective studies of early THAM administration are warranted. PMID:25544901

  12. Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic control

    NASA Technical Reports Server (NTRS)

    Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.

    1991-01-01

    A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.

  13. A Multifactorial Weight Reduction Programme for Children with Overweight and Asthma: A Randomized Controlled Trial

    PubMed Central

    Willeboordse, Maartje; van de Kant, Kim D. G.; Tan, Frans E. S.; Mulkens, Sandra; Schellings, Julia; Crijns, Yvonne; van der Ploeg, Liesbeth; van Schayck, Constant P.; Dompeling, Edward

    2016-01-01

    Background There is increasing evidence that obesity is related to asthma development and severity. However, it is largely unknown whether weight reduction can influence asthma management, especially in children. Objective To determine the effects of a multifactorial weight reduction intervention on asthma management in overweight/obese children with (a high risk of developing) asthma. Methods An 18-month weight-reduction randomized controlled trial was conducted in 87 children with overweight/obesity and asthma. Every six months, measurements of anthropometry, lung function, lifestyle parameters and inflammatory markers were assessed. Analyses were performed with linear mixed models for longitudinal analyses. Results After 18 months, the body mass index-standard deviation score decreased by -0.14±0.29 points (p<0.01) in the intervention group and -0.12±0.34 points (p<0.01) in the control group. This change over time did not differ between groups (p>0.05). Asthma features (including asthma control and asthma-related quality of life) and lung function indices (static and dynamic) improved significantly over time in both groups. The FVC% predicted improved over time by 10.1 ± 8.7% in the intervention group (p<0.001), which was significantly greater than the 6.1 ± 8.4% in the control group (p<0.05). Conclusions & clinical relevance Clinically relevant improvements in body weight, lung function and asthma features were found in both the intervention and control group, although some effects were more pronounced in the intervention group (FVC, asthma control, and quality of life). This implies that a weight reduction intervention could be clinically beneficial for children with asthma. Trial Registration ClinicalTrials.gov NCT00998413 PMID:27294869

  14. Controlled Reduction of a Five-Link 3D Biped with Unactuated Yaw

    PubMed Central

    Gregg, Robert D.

    2014-01-01

    This paper presents a formulation of controlled geometric reduction with one degree of underactuation for mechanical systems with an unactuated cyclic variable subject to passive damping. We show that the first control term in the fully actuated case reduces to passive joint-velocity feedback, which can be equivalently provided by viscous friction. The underactuated control strategy is applied to a five-link 3D biped with a hip, torso, knees, and unactuated yaw at the foot contact point. We show asymptotically stable walking in the presence of passive yawing for realistic friction coefficients. PMID:25663742

  15. Large space structure model reduction and control system design based upon actuator and sensor influence functions

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Lang, J. H.; Johnson, T. L.; Shih, S.; Staelin, D. H.

    1983-01-01

    A model reduction procedure based on aggregation with respect to sensor and actuator influences rather than modes is presented for large systems of coupled second-order differential equations. Perturbation expressions which can predict the effects of spillover on both the aggregated and residual states are derived. These expressions lead to the development of control system design constraints which are sufficient to guarantee, to within the validity of the perturbations, that the residual states are not destabilized by control systems designed from the reduced model. A numerical example is provided to illustrate the application of the aggregation and control system design method.

  16. Fuzzy crane control with sensorless payload deflection feedback for vibration reduction

    NASA Astrophysics Data System (ADS)

    Smoczek, Jaroslaw

    2014-05-01

    Different types of cranes are widely used for shifting cargoes in building sites, shipping yards, container terminals and many manufacturing segments where the problem of fast and precise transferring a payload suspended on the ropes with oscillations reduction is frequently important to enhance the productivity, efficiency and safety. The paper presents the fuzzy logic-based robust feedback anti-sway control system which can be applicable either with or without a sensor of sway angle of a payload. The discrete-time control approach is based on the fuzzy interpolation of the controllers and crane dynamic model's parameters with respect to the varying rope length and mass of a payload. The iterative procedure combining a pole placement method and interval analysis of closed-loop characteristic polynomial coefficients is proposed to design the robust control scheme. The sensorless anti-sway control application developed with using PAC system with RX3i controller was verified on the laboratory scaled overhead crane.

  17. Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

    PubMed Central

    Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

    2013-01-01

    In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water. PMID:23389344

  18. Variance estimation for systematic designs in spatial surveys.

    PubMed

    Fewster, R M

    2011-12-01

    In spatial surveys for estimating the density of objects in a survey region, systematic designs will generally yield lower variance than random designs. However, estimating the systematic variance is well known to be a difficult problem. Existing methods tend to overestimate the variance, so although the variance is genuinely reduced, it is over-reported, and the gain from the more efficient design is lost. The current approaches to estimating a systematic variance for spatial surveys are to approximate the systematic design by a random design, or approximate it by a stratified design. Previous work has shown that approximation by a random design can perform very poorly, while approximation by a stratified design is an improvement but can still be severely biased in some situations. We develop a new estimator based on modeling the encounter process over space. The new "striplet" estimator has negligible bias and excellent precision in a wide range of simulation scenarios, including strip-sampling, distance-sampling, and quadrat-sampling surveys, and including populations that are highly trended or have strong aggregation of objects. We apply the new estimator to survey data for the spotted hyena (Crocuta crocuta) in the Serengeti National Park, Tanzania, and find that the reported coefficient of variation for estimated density is 20% using approximation by a random design, 17% using approximation by a stratified design, and 11% using the new striplet estimator. This large reduction in reported variance is verified by simulation. PMID:21534940

  19. Variance estimation for systematic designs in spatial surveys.

    PubMed

    Fewster, R M

    2011-12-01

    In spatial surveys for estimating the density of objects in a survey region, systematic designs will generally yield lower variance than random designs. However, estimating the systematic variance is well known to be a difficult problem. Existing methods tend to overestimate the variance, so although the variance is genuinely reduced, it is over-reported, and the gain from the more efficient design is lost. The current approaches to estimating a systematic variance for spatial surveys are to approximate the systematic design by a random design, or approximate it by a stratified design. Previous work has shown that approximation by a random design can perform very poorly, while approximation by a stratified design is an improvement but can still be severely biased in some situations. We develop a new estimator based on modeling the encounter process over space. The new "striplet" estimator has negligible bias and excellent precision in a wide range of simulation scenarios, including strip-sampling, distance-sampling, and quadrat-sampling surveys, and including populations that are highly trended or have strong aggregation of objects. We apply the new estimator to survey data for the spotted hyena (Crocuta crocuta) in the Serengeti National Park, Tanzania, and find that the reported coefficient of variation for estimated density is 20% using approximation by a random design, 17% using approximation by a stratified design, and 11% using the new striplet estimator. This large reduction in reported variance is verified by simulation.

  20. Analytic variance estimates of Swank and Fano factors

    SciTech Connect

    Gutierrez, Benjamin; Badano, Aldo; Samuelson, Frank

    2014-07-15

    Purpose: Variance estimates for detector energy resolution metrics can be used as stopping criteria in Monte Carlo simulations for the purpose of ensuring a small uncertainty of those metrics and for the design of variance reduction techniques. Methods: The authors derive an estimate for the variance of two energy resolution metrics, the Swank factor and the Fano factor, in terms of statistical moments that can be accumulated without significant computational overhead. The authors examine the accuracy of these two estimators and demonstrate how the estimates of the coefficient of variation of the Swank and Fano factors behave with data from a Monte Carlo simulation of an indirect x-ray imaging detector. Results: The authors' analyses suggest that the accuracy of their variance estimators is appropriate for estimating the actual variances of the Swank and Fano factors for a variety of distributions of detector outputs. Conclusions: The variance estimators derived in this work provide a computationally convenient way to estimate the error or coefficient of variation of the Swank and Fano factors during Monte Carlo simulations of radiation imaging systems.

  1. A Comparison of Model Reduction Approaches for Feedback Control Design of Thermal Flows in Buildings

    NASA Astrophysics Data System (ADS)

    Borggaard, Jeff; Ahuja, Sunil; Burns, John; Cliff, Eugene; Surana, Amit

    2010-11-01

    The application of distributed parameter control to spatiotemporal thermo-fluid systems requires the use of model reduction methods. The form of the optimal feedback control can inform design decisions, such as sensor and actuator selection and placement. A number of model reduction approaches for fluid systems have been put forward that are based on the proper orthogonal decomposition (POD). In this talk, we examine three approaches, the traditional POD-Galerkin model, the POD-Sensitivity model, and the Balanced-POD models. Our work is motivated by the building indoor environment control problem. Energy performance in building cooling and heating systems can be substantially improved by exploiting spatial temperature stratification and buoyancy that are prevalent in passive systems. We consider the control of airflow in a room with a passively cooled radiant ceiling and displacement ventilation provided near the room floor. For this problem, we approximate the full-order solution to compute the control gains, develop reduced-order models and associated controllers, and simulate the full-order closed-loop system for comparison with the reduced-order model-based control design.

  2. Quantitative Risk reduction estimation Tool For Control Systems, Suggested Approach and Research Needs

    SciTech Connect

    Miles McQueen; Wayne Boyer; Mark Flynn; Sam Alessi

    2006-03-01

    For the past year we have applied a variety of risk assessment technologies to evaluate the risk to critical infrastructure from cyber attacks on control systems. More recently, we identified the need for a stand alone control system risk reduction estimation tool to provide owners and operators of control systems with a more useable, reliable, and credible method for managing the risks from cyber attack. Risk is defined as the probability of a successful attack times the value of the resulting loss, typically measured in lives and dollars. Qualitative and ad hoc techniques for measuring risk do not provide sufficient support for cost benefit analyses associated with cyber security mitigation actions. To address the need for better quantitative risk reduction models we surveyed previous quantitative risk assessment research; evaluated currently available tools; developed new quantitative techniques [17] [18]; implemented a prototype analysis tool to demonstrate how such a tool might be used; used the prototype to test a variety of underlying risk calculational engines (e.g. attack tree, attack graph); and identified technical and research needs. We concluded that significant gaps still exist and difficult research problems remain for quantitatively assessing the risk to control system components and networks, but that a useable quantitative risk reduction estimation tool is not beyond reach.

  3. Progress Towards Fuselage Drag Reduction via Active Flow Control: A Combined CFD and Experimental Effort

    NASA Technical Reports Server (NTRS)

    Schaefler, Norman W.; Allan, Brian G.; Lienard, Caroline; LePape, Arnaud

    2010-01-01

    A combined computational and experimental effort has been undertaken to study fuselage drag reduction on a generic, non-proprietary rotorcraft fuselage by the application of active ow control. Fuselage drag reduction is an area of research interest to both the United States and France and this area is being worked collaboratively as a task under the United States/France Memorandum of Agreement on Helicopter Aeromechanics. In the first half of this task, emphasis is placed on the US generic fuselage, the ROBIN-mod7, with the experimental work being conducted on the US side and complementary US and French CFD analysis of the baseline and controlled cases. Fuselage simulations were made using Reynolds-averaged Navier-Stokes ow solvers and with multiple turbulence models. Comparisons were made to experimental data for numerical simulations of the isolated fuselage and for the fuselage as installed in the tunnel, which includes modeling of the tunnel contraction, walls, and support fairing. The numerical simulations show that comparisons to the experimental data are in good agreement when the tunnel and model support are included. The isolated fuselage simulations compare well to each other, however, there is a positive shift in the centerline pressure when compared to the experiment. The computed flow separation locations on the rear ramp region had only slight differences with and without the tunnel walls and model support. For the simulations, the flow control slots were placed at several locations around the flow separation lines as a series of eight slots that formed a nearly continuous U-shape. Results from the numerical simulations resulted in an estimated 35% fuselage drag reduction from a steady blowing flow control configuration and a 26% drag reduction for unsteady zero-net-mass flow control configuration. Simulations with steady blowing show a delayed flow separation at the rear ramp of the fuselage that increases the surface pressure acting on the ramp

  4. Oxidative Homeostasis Regulates the Response to Reductive Endoplasmic Reticulum Stress through Translation Control.

    PubMed

    Maity, Shuvadeep; Rajkumar, Asher; Matai, Latika; Bhat, Ajay; Ghosh, Asmita; Agam, Ganesh; Kaur, Simarjot; Bhatt, Niraj R; Mukhopadhyay, Arnab; Sengupta, Shantanu; Chakraborty, Kausik

    2016-07-19

    Reductive stress leads to the loss of disulfide bond formation and induces the unfolded protein response of the endoplasmic reticulum (UPR(ER)), necessary to regain proteostasis in the compartment. Here we show that peroxide accumulation during reductive stress attenuates UPR(ER) amplitude by altering translation without any discernible effect on transcription. Through a comprehensive genetic screen in Saccharomyces cerevisiae, we identify modulators of reductive stress-induced UPR(ER) and demonstrate that oxidative quality control (OQC) genes modulate this cellular response in the presence of chronic but not acute reductive stress. Using a combination of microarray and relative quantitative proteomics, we uncover a non-canonical translation attenuation mechanism that acts in a bipartite manner to selectively downregulate highly expressed proteins, decoupling the cell's transcriptional and translational response during reductive ER stress. Finally, we demonstrate that PERK, a canonical translation attenuator in higher eukaryotes, helps in bypassing a ROS-dependent, non-canonical mode of translation attenuation. PMID:27373166

  5. Coupled rotor-fuselage vibration reduction with multiple frequency blade pitch control

    NASA Technical Reports Server (NTRS)

    Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.

    1991-01-01

    A nonlinear coupled rotor/flexible fuselage analysis has been developed and used to study the effects of higher harmonic blade pitch control on the vibratory hub loads and fuselage acceleration levels. Previous results, obtained with this model have shown that conventional higher harmonic control (HHC) inputs aimed at hub shear reduction cause an increase in the fuselage accelerations and vice-versa. It was also found that for simultaneous reduction of hub shears and fuselage accelerations, a pitch input representing a combination of two higher harmonic components of different frequencies was needed. Subsequently, it was found that this input could not be implemented through a conventional swashplate. This paper corrects a mistake originally made in the representation of the multiple frequency pitch input and shows that such a pitch input can be only implemented in the rotating reference frame. A rigorous mathematical solution is found, for the pitch input in the rotating reference frame, which produces simultaneous reduction of hub shears and fuselage acceleration. New insight on vibration reduction in coupled rotor/fuselage systems is obtained from the sensitivity of hub shears to the frequency and amplitude of the open loop HHC signal in the rotating reference frame. Finally the role of fuselage flexibility in this class of problems is determined.

  6. A synchronous generator stabilizer design using neuro inverse controller and error reduction network

    SciTech Connect

    Park, Y.M.; Hyun, S.H.; Lee, J.H.

    1996-11-01

    A neuro power system stabilizer (PSS) is developed for multimachine power systems. Each machine is identified in its inverse relation by an artificial neural network named Inverse Dynamics Neural Network (IDNN) off line, which is used as a local inverse controller. The control error due to the interactions between generators is predicted and compensated through another network called Error Reduction Network (ERN). The ERN consists of several IDNNs in the linear combination form. In most neuro controllers, two neural nets are required, one for system emulation, the other for control. In the proposed controller, the only network requiring training is the IDNN. Simulations are performed on two typical cases: an unstable single machine power system of non-minimum phase, and a multimachine power system.

  7. Size control of noble metal clusters and metallic heterostructures through the reduction kinetics of metal precursors

    NASA Astrophysics Data System (ADS)

    Sevonkaev, Igor V.; Herein, Daniel; Jeske, Gerald; Goia, Dan V.

    2014-07-01

    Eight precious metal salts/complexes were reduced in propylene glycol at temperatures ranging between 110 and 170 °C. We found that the reduction temperature and the size of precipitated metallic nanoparticles formed were significantly affected by the structure and reactivity of the metal precursors. The choice of noble metal precursor offers flexibility for designing, fabricating and controlling the size of metallic heterostructures with tunable properties.Eight precious metal salts/complexes were reduced in propylene glycol at temperatures ranging between 110 and 170 °C. We found that the reduction temperature and the size of precipitated metallic nanoparticles formed were significantly affected by the structure and reactivity of the metal precursors. The choice of noble metal precursor offers flexibility for designing, fabricating and controlling the size of metallic heterostructures with tunable properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03045a

  8. Variance analysis. Part I, Extending flexible budget variance analysis to acuity.

    PubMed

    Finkler, S A

    1991-01-01

    The author reviews the concepts of flexible budget variance analysis, including the price, quantity, and volume variances generated by that technique. He also introduces the concept of acuity variance and provides direction on how such a variance measure can be calculated. Part II in this two-part series on variance analysis will look at how personal computers can be useful in the variance analysis process. PMID:1870002

  9. Global Gravity Wave Variances from Aura MLS: Characteristics and Interpretation

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Eckermann, Stephen D.

    2008-01-01

    The gravity wave (GW)-resolving capabilities of 118-GHz saturated thermal radiances acquired throughout the stratosphere by the Microwave Limb Sounder (MLS) on the Aura satellite are investigated and initial results presented. Because the saturated (optically thick) radiances resolve GW perturbations from a given altitude at different horizontal locations, variances are evaluated at 12 pressure altitudes between 21 and 51 km using the 40 saturated radiances found at the bottom of each limb scan. Forward modeling simulations show that these variances are controlled mostly by GWs with vertical wavelengths z 5 km and horizontal along-track wavelengths of y 100-200 km. The tilted cigar-shaped three-dimensional weighting functions yield highly selective responses to GWs of high intrinsic frequency that propagate toward the instrument. The latter property is used to infer the net meridional component of GW propagation by differencing the variances acquired from ascending (A) and descending (D) orbits. Because of improved vertical resolution and sensitivity, Aura MLS GW variances are 5?8 times larger than those from the Upper Atmosphere Research Satellite (UARS) MLS. Like UARS MLS variances, monthly-mean Aura MLS variances in January and July 2005 are enhanced when local background wind speeds are large, due largely to GW visibility effects. Zonal asymmetries in variance maps reveal enhanced GW activity at high latitudes due to forcing by flow over major mountain ranges and at tropical and subtropical latitudes due to enhanced deep convective generation as inferred from contemporaneous MLS cloud-ice data. At 21-28-km altitude (heights not measured by the UARS MLS), GW variance in the tropics is systematically enhanced and shows clear variations with the phase of the quasi-biennial oscillation, in general agreement with GW temperature variances derived from radiosonde, rocketsonde, and limb-scan vertical profiles.

  10. Reduction of threshold voltage fluctuation in field-effect transistors by controlling individual dopant position

    NASA Astrophysics Data System (ADS)

    Hori, Masahiro; Taira, Keigo; Komatsubara, Akira; Kumagai, Kuninori; Ono, Yukinori; Tanii, Takashi; Endoh, Tetsuo; Shinada, Takahiro

    2012-07-01

    To investigate the impact of only the dopant position on threshold voltage (Vth) in nanoscale field-effect transistors, we fabricated transistors with ordered dopant arrays and conventional random channel doping. Electrical measurements revealed that device performance could be enhanced by controlling the dopant position alone, despite varying dopant number according to a Poisson distribution. Furthermore, device-to-device fluctuations in Vth could be suppressed by implanting a heavier ion such as arsenic owing to the reduction of the projected ion struggling. The results of our study highlight potential improvements in device performance by controlling individual dopant positions.

  11. Spatially controlled synthesis of silver nanoparticles and nanowires by photosensitized reduction.

    PubMed

    Jradi, S; Balan, L; Zeng, X H; Plain, J; Lougnot, D J; Royer, P; Bachelot, R; Akil, S; Soppera, O; Vidal, L

    2010-03-01

    The present paper reports on the spatially controlled synthesis of silver nanoparticles (NPs) and silver nanowires by photosensitized reduction. In a first approach, direct photogeneration of silver NPs at the end of an optical fiber was carried out. Control of both size and density of silver NPs was possible by changing the photonic conditions. In a further development, a photochemically assisted procedure allowing silver to be deposited at the surface of a polymer microtip was implemented. Finally, polymer tips terminated by silver nanowires were fabricated by simultaneous photopolymerization and silver photoreduction. The silver NPs were characterized by UV-visible spectroscopy and scanning electron microscopy.

  12. Warped functional analysis of variance.

    PubMed

    Gervini, Daniel; Carter, Patrick A

    2014-09-01

    This article presents an Analysis of Variance model for functional data that explicitly incorporates phase variability through a time-warping component, allowing for a unified approach to estimation and inference in presence of amplitude and time variability. The focus is on single-random-factor models but the approach can be easily generalized to more complex ANOVA models. The behavior of the estimators is studied by simulation, and an application to the analysis of growth curves of flour beetles is presented. Although the model assumes a smooth latent process behind the observed trajectories, smootheness of the observed data is not required; the method can be applied to irregular time grids, which are common in longitudinal studies.

  13. 29 CFR 1920.2 - Variances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Variances. 1920.2 Section 1920.2 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED...' COMPENSATION ACT § 1920.2 Variances. (a) Variances from standards in parts 1915 through 1918 of this...

  14. Estimation of Variance Components Using Computer Packages.

    ERIC Educational Resources Information Center

    Chastain, Robert L.; Willson, Victor L.

    Generalizability theory is based upon analysis of variance (ANOVA) and requires estimation of variance components for the ANOVA design under consideration in order to compute either G (Generalizability) or D (Decision) coefficients. Estimation of variance components has a number of alternative methods available using SAS, BMDP, and ad hoc…

  15. 10 CFR 851.31 - Variance process.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Variance process. 851.31 Section 851.31 Energy DEPARTMENT OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.31 Variance process. (a) Application..., practices, means, methods, operations, or processes used or proposed to be used by the contractor; and...

  16. The Validation of an Active Control Intervention for Mindfulness Based Stress Reduction (MBSR)

    PubMed Central

    MacCoon, Donal G.; Imel, Zac E.; Rosenkranz, Melissa A.; Sheftel, Jenna G.; Weng, Helen Y.; Sullivan, Jude C.; Bonus, Katherine A.; Stoney, Catherine M.; Salomons, Tim V.; Davidson, Richard J.; Lutz, Antoine

    2011-01-01

    Most of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. The current article specifies and validates an active control condition, the Health Enhancement Program (HEP), thus providing the foundation necessary for rigorous investigations of the relative efficacy of Mindfulness Based Stress Reduction (MBSR) and for testing mindfulness as an active ingredient. 63 participants were randomized to either MBSR (n=31) or HEP (n=32). Compared to HEP, MBSR led to reductions in thermal pain ratings in the mindfulness- but not the HEP-related instruction condition (η2=.18). There were significant improvements over time for general distress (η2=.09), anxiety (η2=.08), hostility (η2=.07), and medical symptoms (η2=.14), but no effects of intervention. Practice was not related to change. HEP is an active control condition for MBSR while remaining inert to mindfulness. These claims are supported by results from a pain task. Participant-reported outcomes (PROs) replicate previous improvements to well-being in MBSR, but indicate that MBSR is no more effective than a rigorous active control in improving these indices. These results emphasize the importance of using an active control condition like HEP in studies evaluating the effectiveness of MBSR. PMID:22137364

  17. The validation of an active control intervention for Mindfulness Based Stress Reduction (MBSR).

    PubMed

    MacCoon, Donal G; Imel, Zac E; Rosenkranz, Melissa A; Sheftel, Jenna G; Weng, Helen Y; Sullivan, Jude C; Bonus, Katherine A; Stoney, Catherine M; Salomons, Tim V; Davidson, Richard J; Lutz, Antoine

    2012-01-01

    Most of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. The current article specifies and validates an active control condition, the Health Enhancement Program (HEP), thus providing the foundation necessary for rigorous investigations of the relative efficacy of Mindfulness Based Stress Reduction (MBSR) and for testing mindfulness as an active ingredient. 63 participants were randomized to either MBSR (n = 31) or HEP (n = 32). Compared to HEP, MBSR led to reductions in thermal pain ratings in the mindfulness- but not the HEP-related instruction condition (η(2) = .18). There were significant improvements over time for general distress (η(2) = .09), anxiety (η(2) = .08), hostility (η(2) = .07), and medical symptoms (η(2) = .14), but no effects of intervention. Practice was not related to change. HEP is an active control condition for MBSR while remaining inert to mindfulness. These claims are supported by results from a pain task. Participant-reported outcomes (PROs) replicate previous improvements to well-being in MBSR, but indicate that MBSR is no more effective than a rigorous active control in improving these indices. These results emphasize the importance of using an active control condition like HEP in studies evaluating the effectiveness of MBSR.

  18. 78 FR 38730 - Announcement of Funding Awards for Lead-Based Paint Hazard Control, and Lead Hazard Reduction...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-27

    ... Lead Based Paint Hazard Control and the Lead Hazard Reduction Demonstration Programs (FR-5700-N-04... URBAN DEVELOPMENT Announcement of Funding Awards for Lead-Based Paint Hazard Control, and Lead Hazard Reduction Demonstration Grant Programs for Fiscal Year (FY) 2013 AGENCY: Office of Healthy Homes and...

  19. Preliminary Assessment of Optimal Longitudinal-Mode Control for Drag Reduction through Distributed Aeroelastic Shaping

    NASA Technical Reports Server (NTRS)

    Ippolito, Corey; Nguyen, Nhan; Lohn, Jason; Dolan, John

    2014-01-01

    The emergence of advanced lightweight materials is resulting in a new generation of lighter, flexible, more-efficient airframes that are enabling concepts for active aeroelastic wing-shape control to achieve greater flight efficiency and increased safety margins. These elastically shaped aircraft concepts require non-traditional methods for large-scale multi-objective flight control that simultaneously seek to gain aerodynamic efficiency in terms of drag reduction while performing traditional command-tracking tasks as part of a complete guidance and navigation solution. This paper presents results from a preliminary study of a notional multi-objective control law for an aeroelastic flexible-wing aircraft controlled through distributed continuous leading and trailing edge control surface actuators. This preliminary study develops and analyzes a multi-objective control law derived from optimal linear quadratic methods on a longitudinal vehicle dynamics model with coupled aeroelastic dynamics. The controller tracks commanded attack-angle while minimizing drag and controlling wing twist and bend. This paper presents an overview of the elastic aircraft concept, outlines the coupled vehicle model, presents the preliminary control law formulation and implementation, presents results from simulation, provides analysis, and concludes by identifying possible future areas for research

  20. DEMONSTRATION OF AN ADVANCED INTEGRATED CONTROL SYSTEM FOR SIMULTANEOUS EMISSIONS REDUCTION

    SciTech Connect

    Suzanne Shea; Randhir Sehgal; Ilga Celmins; Andrew Maxson

    2002-02-01

    The primary objective of the project titled ''Demonstration of an Advanced Integrated Control System for Simultaneous Emissions Reduction'' was to demonstrate at proof-of-concept scale the use of an online software package, the ''Plant Environmental and Cost Optimization System'' (PECOS), to optimize the operation of coal-fired power plants by economically controlling all emissions simultaneously. It combines physical models, neural networks, and fuzzy logic control to provide both optimal least-cost boiler setpoints to the boiler operators in the control room, as well as optimal coal blending recommendations designed to reduce fuel costs and fuel-related derates. The goal of the project was to demonstrate that use of PECOS would enable coal-fired power plants to make more economic use of U.S. coals while reducing emissions.

  1. Vibration isolation and reduction by spring-stiffness control based on theory of variable structure systems

    SciTech Connect

    Yamaguchi, H.; Shioya, S.; Oda, M.

    1995-12-31

    By controlling spring stiffness, vibration reduction and isolation for the mass-spring system are achieved in this paper. The control algorithm of the spring stiffness is based on the variable structure systems (VSS) theory. The stiffness-controllable spring is achieved by using two straight bars that are hinged to the mass in a line perpendicular to the direction of mass motion and are applied axial force. Since the axial force causes restoring force equivalent to the spring, the stiffness is controlled by the axial force. In the numerical simulations and experiments, the settling time of the impulse response and the displacement transmissibility are investigated. The results show that the proposed method is effective in suppressing shock motion and isolating vibration transmitted from the floor.

  2. Industrial boiler retrofit for NO{sub x} control: Combined selective noncatalytic reduction and selective catalytic reduction

    SciTech Connect

    Groff, P.W.; Gullett, B.K.

    1996-01-01

    A 590 kW (2 MMBtu/hr), oil-fired, three-pass, fire-tube package boiler was retrofit with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system and demonstrated 85% nitrogen oxide (NO{sub x}) reduction with less than 6 ppm ammonia slip. A urea-based SNCR solution was injected in the first pass, reducing NO{sub x} and providing ammonia reagent for the SCR. A catalyst housing was designed to fit between the second and third passes, where the access doors of the boiler normally attach. The SCR catalyst volume of 0.04 m{sup 3} (1.5 ft{sup 3}) provided a space velocity of 10,000 hr{sup -1} at a pressure drop of less than 1.5 cm (0.5 in) of water. Numerous runs demonstrated system repeatability and ease of operation.

  3. ADVANTG An Automated Variance Reduction Parameter Generator, Rev. 1

    SciTech Connect

    Mosher, Scott W.; Johnson, Seth R.; Bevill, Aaron M.; Ibrahim, Ahmad M.; Daily, Charles R.; Evans, Thomas M.; Wagner, John C.; Johnson, Jeffrey O.; Grove, Robert E.

    2015-08-01

    The primary objective of ADVANTG is to reduce both the user effort and the computational time required to obtain accurate and precise tally estimates across a broad range of challenging transport applications. ADVANTG has been applied to simulations of real-world radiation shielding, detection, and neutron activation problems. Examples of shielding applications include material damage and dose rate analyses of the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source and High Flux Isotope Reactor (Risner and Blakeman 2013) and the ITER Tokamak (Ibrahim et al. 2011). ADVANTG has been applied to a suite of radiation detection, safeguards, and special nuclear material movement detection test problems (Shaver et al. 2011). ADVANTG has also been used in the prediction of activation rates within light water reactor facilities (Pantelias and Mosher 2013). In these projects, ADVANTG was demonstrated to significantly increase the tally figure of merit (FOM) relative to an analog MCNP simulation. The ADVANTG-generated parameters were also shown to be more effective than manually generated geometry splitting parameters.

  4. Global variance reduction for Monte Carlo reactor physics calculations

    SciTech Connect

    Zhang, Q.; Abdel-Khalik, H. S.

    2013-07-01

    Over the past few decades, hybrid Monte-Carlo-Deterministic (MC-DT) techniques have been mostly focusing on the development of techniques primarily with shielding applications in mind, i.e. problems featuring a limited number of responses. This paper focuses on the application of a new hybrid MC-DT technique: the SUBSPACE method, for reactor analysis calculation. The SUBSPACE method is designed to overcome the lack of efficiency that hampers the application of MC methods in routine analysis calculations on the assembly level where typically one needs to execute the flux solver in the order of 10{sup 3}-10{sup 5} times. It places high premium on attaining high computational efficiency for reactor analysis application by identifying and capitalizing on the existing correlations between responses of interest. This paper places particular emphasis on using the SUBSPACE method for preparing homogenized few-group cross section sets on the assembly level for subsequent use in full-core diffusion calculations. A BWR assembly model is employed to calculate homogenized few-group cross sections for different burn-up steps. It is found that using the SUBSPACE method significant speedup can be achieved over the state of the art FW-CADIS method. While the presented speed-up alone is not sufficient to render the MC method competitive with the DT method, we believe this work will become a major step on the way of leveraging the accuracy of MC calculations for assembly calculations. (authors)

  5. Photocatalytic and photoelectrocatalytic reduction of CO2 using heterogeneous catalysts with controlled nanostructures.

    PubMed

    Xie, Shunji; Zhang, Qinghong; Liu, Guodong; Wang, Ye

    2016-01-01

    The development of efficient artificial photocatalysts and photoelectrocatalysts for the reduction of CO2 with H2O to fuels and chemicals has attracted much attention in recent years. Although the state-of-the-art for the production of fuels or chemicals from CO2 using solar energy is still far from practical consideration, rich knowledge has been accumulated to understand the key factors that determine the catalytic performances. This Feature article highlights recent advances in the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O using heterogeneous semiconductor-based catalysts. The effects of structural aspects of semiconductors, such as crystalline phases, particle sizes, morphologies, exposed facets and heterojunctions, on their catalytic behaviours are discussed. The roles of different types of cocatalysts and the impact of their nanostructures on surface CO2 chemisorption and reduction are also analysed. The present article aims to provide insights into the rational design of efficient heterogeneous catalysts with controlled nanostructures for the photocatalytic and photoelectrocatalytic reduction of CO2 with H2O.

  6. Increasing selection response by Bayesian modeling of heterogeneous environmental variances

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heterogeneity of environmental variance among genotypes reduces selection response because genotypes with higher variance are more likely to be selected than low-variance genotypes. Modeling heterogeneous variances to obtain weighted means corrected for heterogeneous variances is difficult in likel...

  7. Improved myocardial preservation by control of the oxidation-reduction potential.

    PubMed

    Miller, L W; Jellinek, M; Codd, J E; Kolata, R J

    1985-05-01

    Simple cold storage remains the current method of preservation of human heart allografts between removal and transplantation, but this technique is not adequate for prolonged periods of preservation. An alternative to cold storage is machine perfusion of the isolated organ. Although this technique has yielded promising results in kidney preservation, there is limited experience with the heart. One factor limiting the effectiveness of perfusion preservation is the toxicity of oxygen free radicals generated during the perfusion. The generation and reduction of these radicals results in an electron transfer, producing an electrochemical potential known as the redox potential. This study examines the role of machine perfusion in heart preservation with and without the use of a new electrochemical cell that is able to control the redox potential during the perfusion. Hearts were preserved for twenty-four hours by either simple cold storage (Group I), or by machine perfusion with redox monitoring (Group II), or redox control (Group III). Control of the oxidation-reduction potential of the perfusate during machine perfusion of isolated hearts resulted in significantly improved systolic and diastolic function after perfusion compared to hearts that underwent machine perfusion without redox control or simple cold storage.

  8. The reduction of rotorcraft power and vibration using optimally controlled active gurney flap

    NASA Astrophysics Data System (ADS)

    Bae, Eui Sung

    The main topic of the present study is the application of active control scheme for the reduction of rotorcraft main rotor power reduction and vibratory load. When the helicopter is operated near its flight boundary, the required power and vibratory loads rapidly increases which impose a limit on the helicopter operation. Various methods were proposed and studied in order to achieve performance improvement under such operating condition. The effect of active control scheme was examined for its impact on the performance improvement and vibration reduction in the present study. Numerical simulations are based on the UH-60A Blackhawk helicopter with an active Gurney flap spanning from 70%R to 80%R of the main rotor. For obtaining the aeroelastic response of the rotor blade, finite element method was used to represent elastic blade. The aerodynamic loads acting on the blade are provided by CFD based 2D lookup table. Prescribed wake model was used to resolve the induced inflow over the rotor disk. The unsteady aerodynamic behavior due to the higher harmonic actuation of active Gurney flap was resolved by the time-domain unsteady aerodynamic model. The first part of preliminary study covers parametric study using Gurney flap. Starting with simple rigid blade representation of the rotor blade, the effect of 1/rev Gurney flap actuation was examined on three different gross weights. The effect of active Gurney flap width, the chordwise location of active Gurney flap, the effect of unsteady aerodynamic model, and the effect of 2/rev actuation frequency were examined. The second part of preliminary study was conducted with the elastic blade model to include the effect of torsion dynamics. Performance improvement using active Gurney flap was examined for maximizing thrust capability at two flight speeds. 1/rev Gurney flap actuation increased the gross weight capability up to 1,000 lbs. Also, 1/rev actuation of Gurney flap increased maximum altitude limit of baseline rotor by 1

  9. Investigation to optimize the passive shock wave-boundary layer control for supercritical airfoil drag reduction

    NASA Technical Reports Server (NTRS)

    Nagamatsu, H. T.; Ficarra, R.; Orozco, R.

    1983-01-01

    The optimization of passive shock wave/boundary layer control for supercritical airfoil drag reduction was investigated in a 3 in. x 15.4 in. Transonic Blowdown Wind Tunnel. A 14% thick supercritical airfoil was tested with 0%, 1.42% and 2.8% porosities at Mach numbers of .70 to .83. The 1.42% case incorporated a linear increase in porosity with the flow direction while the 2.8% case was uniform porosity. The static pressure distributions over the airfoil, the wake impact pressure data for determining the profile drag, and the Schlieren photographs for porous surface airfoils are presented and compared with the results for solid-surface airfoils. While the results show that linear 1.42% porosity actually led to a slight increase in drag it was found that the uniform 2.8% porosity can lead to a drag reduction of 46% at M = .81.

  10. Ecological Intensification Through Pesticide Reduction: Weed Control, Weed Biodiversity and Sustainability in Arable Farming

    NASA Astrophysics Data System (ADS)

    Petit, Sandrine; Munier-Jolain, Nicolas; Bretagnolle, Vincent; Bockstaller, Christian; Gaba, Sabrina; Cordeau, Stéphane; Lechenet, Martin; Mézière, Delphine; Colbach, Nathalie

    2015-11-01

    Amongst the biodiversity components of agriculture, weeds are an interesting model for exploring management options relying on the principle of ecological intensification in arable farming. Weeds can cause severe crop yield losses, contribute to farmland functional biodiversity and are strongly associated with the generic issue of pesticide use. In this paper, we address the impacts of herbicide reduction following a causal framework starting with herbicide reduction and triggering changes in (i) the management options required to control weeds, (ii) the weed communities and functions they provide and (iii) the overall performance and sustainability of the implemented land management options. The three components of this framework were analysed in a multidisciplinary project that was conducted on 55 experimental and farmer's fields that included conventional, integrated and organic cropping systems. Our results indicate that the reduction of herbicide use is not antagonistic with crop production, provided that alternative practices are put into place. Herbicide reduction and associated land management modified the composition of in-field weed communities and thus the functions of weeds related to biodiversity and production. Through a long-term simulation of weed communities based on alternative (?) cropping systems, some specific management pathways were identified that delivered high biodiversity gains and limited the negative impacts of weeds on crop production. Finally, the multi-criteria assessment of the environmental, economic and societal sustainability of the 55 systems suggests that integrated weed management systems fared better than their conventional and organic counterparts. These outcomes suggest that sustainable management could possibly be achieved through changes in weed management, along a pathway starting with herbicide reduction.

  11. Ecological Intensification Through Pesticide Reduction: Weed Control, Weed Biodiversity and Sustainability in Arable Farming.

    PubMed

    Petit, Sandrine; Munier-Jolain, Nicolas; Bretagnolle, Vincent; Bockstaller, Christian; Gaba, Sabrina; Cordeau, Stéphane; Lechenet, Martin; Mézière, Delphine; Colbach, Nathalie

    2015-11-01

    Amongst the biodiversity components of agriculture, weeds are an interesting model for exploring management options relying on the principle of ecological intensification in arable farming. Weeds can cause severe crop yield losses, contribute to farmland functional biodiversity and are strongly associated with the generic issue of pesticide use. In this paper, we address the impacts of herbicide reduction following a causal framework starting with herbicide reduction and triggering changes in (i) the management options required to control weeds, (ii) the weed communities and functions they provide and (iii) the overall performance and sustainability of the implemented land management options. The three components of this framework were analysed in a multidisciplinary project that was conducted on 55 experimental and farmer's fields that included conventional, integrated and organic cropping systems. Our results indicate that the reduction of herbicide use is not antagonistic with crop production, provided that alternative practices are put into place. Herbicide reduction and associated land management modified the composition of in-field weed communities and thus the functions of weeds related to biodiversity and production. Through a long-term simulation of weed communities based on alternative (?) cropping systems, some specific management pathways were identified that delivered high biodiversity gains and limited the negative impacts of weeds on crop production. Finally, the multi-criteria assessment of the environmental, economic and societal sustainability of the 55 systems suggests that integrated weed management systems fared better than their conventional and organic counterparts. These outcomes suggest that sustainable management could possibly be achieved through changes in weed management, along a pathway starting with herbicide reduction.

  12. Ecological Intensification Through Pesticide Reduction: Weed Control, Weed Biodiversity and Sustainability in Arable Farming.

    PubMed

    Petit, Sandrine; Munier-Jolain, Nicolas; Bretagnolle, Vincent; Bockstaller, Christian; Gaba, Sabrina; Cordeau, Stéphane; Lechenet, Martin; Mézière, Delphine; Colbach, Nathalie

    2015-11-01

    Amongst the biodiversity components of agriculture, weeds are an interesting model for exploring management options relying on the principle of ecological intensification in arable farming. Weeds can cause severe crop yield losses, contribute to farmland functional biodiversity and are strongly associated with the generic issue of pesticide use. In this paper, we address the impacts of herbicide reduction following a causal framework starting with herbicide reduction and triggering changes in (i) the management options required to control weeds, (ii) the weed communities and functions they provide and (iii) the overall performance and sustainability of the implemented land management options. The three components of this framework were analysed in a multidisciplinary project that was conducted on 55 experimental and farmer's fields that included conventional, integrated and organic cropping systems. Our results indicate that the reduction of herbicide use is not antagonistic with crop production, provided that alternative practices are put into place. Herbicide reduction and associated land management modified the composition of in-field weed communities and thus the functions of weeds related to biodiversity and production. Through a long-term simulation of weed communities based on alternative (?) cropping systems, some specific management pathways were identified that delivered high biodiversity gains and limited the negative impacts of weeds on crop production. Finally, the multi-criteria assessment of the environmental, economic and societal sustainability of the 55 systems suggests that integrated weed management systems fared better than their conventional and organic counterparts. These outcomes suggest that sustainable management could possibly be achieved through changes in weed management, along a pathway starting with herbicide reduction. PMID:26071767

  13. Analysis of Variance Components for Genetic Markers with Unphased Genotypes.

    PubMed

    Wang, Tao

    2016-01-01

    An ANOVA type general multi-allele (GMA) model was proposed in Wang (2014) on analysis of variance components for quantitative trait loci or genetic markers with phased or unphased genotypes. In this study, by applying the GMA model, we further examine estimation of the genetic variance components for genetic markers with unphased genotypes based on a random sample from a study population. In one locus and two loci cases, we first derive the least square estimates (LSE) of model parameters in fitting the GMA model. Then we construct estimators of the genetic variance components for one marker locus in a Hardy-Weinberg disequilibrium population and two marker loci in an equilibrium population. Meanwhile, we explore the difference between the classical general linear model (GLM) and GMA based approaches in association analysis of genetic markers with quantitative traits. We show that the GMA model can retain the same partition on the genetic variance components as the traditional Fisher's ANOVA model, while the GLM cannot. We clarify that the standard F-statistics based on the partial reductions in sums of squares from GLM for testing the fixed allelic effects could be inadequate for testing the existence of the variance component when allelic interactions are present. We point out that the GMA model can reduce the confounding between the allelic effects and allelic interactions at least for independent alleles. As a result, the GMA model could be more beneficial than GLM for detecting allelic interactions.

  14. Efficient control of ultrafast optical nonlinearity of reduced graphene oxide by infrared reduction

    NASA Astrophysics Data System (ADS)

    Bhattachraya, S.; Maiti, R.; Das, A. C.; Saha, S.; Mondal, S.; Ray, S. K.; Bhaktha, S. N. B.; Datta, P. K.

    2016-07-01

    Simultaneous occurrence of saturable absorption nonlinearity and two-photon absorption nonlinearity in the same medium is well sought for the devices like optical limiter and laser mode-locker. Pristine graphene sheet consisting entirely of sp2-hybridized carbon atoms has already been identified having large optical nonlinearity. However, graphene oxide (GO), a precursor of graphene having both sp2 and sp3-hybridized carbon atom, is increasingly attracting cross-discipline researchers for its controllable properties by reduction of oxygen containing groups. In this work, GO has been prepared by modified Hummers method, and it has been further reduced by infrared (IR) radiation. Characterization of reduced graphene oxide (RGO) by means of Raman spectroscopy, X-ray photoelectron spectroscopy, and UV-Visible absorption measurements confirms an efficient reduction with infrared radiation. Here, we report precise control of non-linear optical properties of RGO in femtosecond regime with increased degrees of IR reduction measured by open aperture z-scan technique. Depending on the intensity, both saturable absorption and two-photon absorption effects are found to contribute to the non-linearity of all the samples. Saturation dominates at low intensity (˜127 GW/cm2) while two-photon absorption becomes prominent at higher intensities (from 217 GW/cm2 to 302 GW/cm2). The values of two-photon absorption co-efficient (˜0.0022-0.0037 cm/GW for GO, and ˜0.0128-0.0143 cm/GW for RGO) and the saturation intensity (˜57 GW/cm2 for GO, and ˜194 GW/cm2 for RGO) increase with increasing reduction, indicating GO and RGO as novel tunable photonic devices. We have also explained the reason of tunable nonlinear optical properties by using amorphous carbon model.

  15. A Control Method Switching from Vibration Reduction to Positioning for Power Assisted Moving Flexible Structures

    NASA Astrophysics Data System (ADS)

    Fujimoto, Isao; Hara, Susumu; Yamada, Yoji; Morita, Yoshifumi; Seshimo, Kiyoshi; Higashi, Masatake

    This paper shows control methods of the smooth switching from vibration reduction when a worker conveys flexible structures to their positioning. One of the important issues in this study is there are no knowledge of the goal position before conveying an object and the terminal time when worker finishes conveying. Then one of sensors can detect the displacement of the object not anytime but only the time when the position is settled. Additionally, an overshoot has to be prevented when there are other objects at the goal position. For clearing up these issues, we applied an adaptive nonstationary control method and showed its effectiveness. And two methods for determining the goal position with limited sensor signals are proposed. For showing the utility of the proposed methods, we conducted four kinds of experiments of positioning a flexible object: 1) only the power assist control, 2) the vibration control with power assist control, 3) the vibration and position control with power assist control and laser sensor, 4) the vibration and position control with power assist control without laser sensor. The results show that the first method is useful for accurate positioning in a short time. The second method does not need an additional sensor used in the first method. However, this method takes a longer time for accurate positioning settling. Adaptive nonstationary control with smooth mode switching is useful when the additional sensor signal is input in the positioning stage only. Then, the results also show that vibration control is important when not only conveying but also positioning because of preventing the overshoot. The proposed methods are useful because it can position any undetermined goal position before conveying.

  16. Flexible system model reduction and control system design based upon actuator and sensor influence functions

    NASA Technical Reports Server (NTRS)

    Yam, Yeung; Johnson, Timothy L.; Lang, Jeffrey H.

    1987-01-01

    A model reduction technique based on aggregation with respect to sensor and actuator influence functions rather than modes is presented for large systems of coupled second-order differential equations. Perturbation expressions which can predict the effects of spillover on both the reduced-order plant model and the neglected plant model are derived. For the special case of collocated actuators and sensors, these expressions lead to the derivation of constraints on the controller gains that are, given the validity of the perturbation technique, sufficient to guarantee the stability of the closed-loop system. A case study demonstrates the derivation of stabilizing controllers based on the present technique. The use of control and observation synthesis in modifying the dimension of the reduced-order plant model is also discussed. A numerical example is provided for illustration.

  17. Intelligent Control for Drag Reduction on the X-48B Vehicle

    NASA Technical Reports Server (NTRS)

    Griffin, Brian Joseph; Brown, Nelson Andrew; Yoo, Seung Yeun

    2011-01-01

    This paper focuses on the development of an intelligent control technology for in-flight drag reduction. The system is integrated with and demonstrated on the full X-48B nonlinear simulation. The intelligent control system utilizes a peak-seeking control method implemented with a time-varying Kalman filter. Performance functional coordinate and magnitude measurements, or independent and dependent parameters respectively, are used by the Kalman filter to provide the system with gradient estimates of the designed performance function which is used to drive the system toward a local minimum in a steepestdescent approach. To ensure ease of integration and algorithm performance, a single-input single-output approach was chosen. The framework, specific implementation considerations, simulation results, and flight feasibility issues related to this platform are discussed.

  18. Assessment of methods for methyl iodide emission reduction and pest control using a simulation model

    NASA Astrophysics Data System (ADS)

    Luo, Lifang; Ashworth, Daniel J.; Šimunek, Jirka; Xuan, Richeng; Yates, Scott R.

    2013-02-01

    The increasing registration of the fumigant methyl iodide within the USA has led to more concerns about its toxicity to workers and bystanders. Emission mitigation strategies are needed to protect the public and environmental health while providing effective pest control. The effectiveness of various methods on emissions reduction and pest control was assessed using a process-based mathematical model in this study. Firstly, comparisons between the simulated and laboratory measured emission fluxes and cumulative emissions were made for methyl iodide (MeI) under four emission reduction treatments: 1) control, 2) using soil with high organic matter content (HOM), 3) being covered by virtually impermeable film (VIF), and 4) irrigating soil surface following fumigation (Irrigation). Then the model was extended to simulate a broader range of emission reduction strategies for MeI, including 5) being covered by high density polyethylene (HDPE), 6) increasing injection depth from 30 cm to 46 cm (Deep), 7) HDPE + Deep, 8) adding a reagent at soil surface (Reagent), 9) Reagent + Irrigation, and 10) Reagent + HDPE. Furthermore, the survivability of three types of soil-borne pests (citrus nematodes [Tylenchulus semipenetrans], barnyard seeds [Echinochloa crus-galli], fungi [Fusarium oxysporum]) was also estimated for each scenario. Overall, the trend of the measured emission fluxes as well as total emission were reasonably reproduced by the model for treatments 1 through 4. Based on the numerical simulation, the ranking of effectiveness in total emission reduction was VIF (82.4%) > Reagent + HDPE (73.2%) > Reagent + Irrigation (43.0%) > Reagent (23.5%) > Deep + HDPE (19.3%) > HOM (17.6%) > Deep (13.0%) > Irrigation (11.9%) > HDPE (5.8%). The order for pest control efficacy suggests, VIF had the highest pest control efficacy, followed by Deep + HDPE, Irrigation, Reagent + Irrigation, HDPE, Deep, Reagent + HDPE, Reagent, and HOM. Therefore, VIF is the optimal method disregarding

  19. Importance of NOx control for peak ozone reduction in the Pearl River Delta region

    NASA Astrophysics Data System (ADS)

    Li, Ying; Lau, Alexis K. H.; Fung, Jimmy C. H.; Zheng, Junyu; Liu, Shawchen

    2013-08-01

    As major air pollutants and key precursors of several secondary air pollutants, nitrogen oxide (NOx) emissions are regulated in many countries. However, NOx control increases ozone concentrations when the ozone formation regime is volatile organic compound (VOC) limited. Although many studies have shown that NOx regulation reduces ozone levels over the long term, it is still of concern that NOx regulation increases short-term ozone levels in metropolitan regions, where ozone formation is found to be predominantly VOC-limited. The Pearl River Delta (PRD) in China is such a region. Our modeling sensitivity study shows that while NOx reduction in the PRD region may raise the mean ozone concentration, it can also decrease peak ozone levels. Similar changes are observed in the NOx and ozone data of the PRD regional air quality monitoring network (2006-2012), lending further credence to our results. In the model, this NOx control effect is a result of the complicated spatial and diurnal variations of the ozone formation regime. In most of the PRD region, the formation regime is VOC-limited in the morning and becomes NOx-limited during peak ozone hours. Although some areas are always VOC-limited, their ozone concentrations are relatively low, and the ozone increases caused by NOx reduction generally do not cause higher ozone levels than the region's original ozone maxima. Several control scenarios are simulated to evaluate the effects of various possible control regulations. Our results show that in addition to VOC control, NOx control can be effective for reducing peak ozone concentrations in the PRD region.

  20. Restricted sample variance reduces generalizability.

    PubMed

    Lakes, Kimberley D

    2013-06-01

    One factor that affects the reliability of observed scores is restriction of range on the construct measured for a particular group of study participants. This study illustrates how researchers can use generalizability theory to evaluate the impact of restriction of range in particular sample characteristics on the generalizability of test scores and to estimate how changes in measurement design could improve the generalizability of the test scores. An observer-rated measure of child self-regulation (Response to Challenge Scale; Lakes, 2011) is used to examine scores for 198 children (Grades K through 5) within the generalizability theory (GT) framework. The generalizability of ratings within relatively developmentally homogeneous samples is examined and illustrates the effect of reduced variance among ratees on generalizability. Forecasts for g coefficients of various D study designs demonstrate how higher generalizability could be achieved by increasing the number of raters or items. In summary, the research presented illustrates the importance of and procedures for evaluating the generalizability of a set of scores in a particular research context. PMID:23205627

  1. Hingeless rotor theory and experiment on vibration reduction by periodic variation of conventional controls

    NASA Technical Reports Server (NTRS)

    Sissingh, G. J.; Donham, R. E.

    1974-01-01

    The reduction of the n per rev. pitch-, roll- and vertical vibrations of an n-bladed rotor by n per rev. sinusoidal variations of the collective and cyclic controls is investigated. The numerical results presented refer to a four-bladed, 7.5-foot model and are based on frequency response tests conducted under an Army-sponsored research program. The following subjects are treated: extraction of the rotor transfer functions (.073R hub flapping and model thrust versus servo valve command, amplitude and phase), calculation of servo commands (volts) required to compensate .073R hub flapping (3P and 5P) and model thrust (4P), evaluation of the effect of the vibratory control inputs on blade loads, and theoretical prediction of the root flapbending moments generated by 0 to 5P perturbations of the feathering angle and rotor angle of attack. Five operating conditions are investigated covering advance ratios from approximately 0.2 to 0.85. The feasibility of vibration reduction by periodic variation on conventional controls is evaluated.

  2. Supply-side harm reduction strategies: Bolivia's experiment with social control.

    PubMed

    Farthing, Linda; Kohl, Benjamin

    2012-11-01

    Harm reduction approaches to drug control have almost exclusively focussed on consumers in northern countries. This article supports recent analysis that indicates that such policies also hold relevance for producer countries by drawing on recent policy innovations in Bolivia. When Evo Morales, the president of the national coca grower confederation, was elected the country's first indigenous president in 2005, he promised to fundamentally change 25 years of the U.S.-funded "drug war" that had generated repeated human rights violations. The new policy, which implicitly incorporates harm reduction principles combined with respect for human rights, recognizes coca leaf's traditional use and cultural importance and relies on vigorous local organizations to implement a community-based programme called social control. Results to date indicate that Bolivia's social control experience has reduced violence in coca growing communities, ensured small farmers a subsistence income from coca and increased sovereignty, while making a modest contribution to containing expansion of coca cultivation. The programme has registered 50,000 farmers who are allowed to cultivate limited quantities of coca to supply traditional users and helped them gain secure title to their land. This registration is combined with satellite surveillance to guarantee that farmers do not exceed limits established by law. To date, the programme's reach is incomplete and coca is still diverted to the drug trade. Nonetheless, the approach may offer lessons for other drug producer countries, particularly where strong socio-political organizations are found in combination with closeknit communities holding shared cultural values.

  3. Mechanism of drag reduction on a three-dimensional model vehicle using a passive control device

    NASA Astrophysics Data System (ADS)

    Yi, Wook; Sagong, Woong; Choi, Haecheon

    2007-11-01

    It has been well known that the boat-tail device reduces drag on a three-dimensional vehicle. However, its detailed mechanism is not clearly known yet. To understand this mechanism, we conduct an experiment for flow over a three-dimensional model vehicle in ground proximity. We consider various lengths (l/H = 0.1 ˜0.5) and slant angles (θ=0^o ˜40^o) of the boat tail, and conduct velocity measurements near the boat tail and oil visualizations on the boat-tail surface. We find that the slant angle is an important parameter for drag reduction. The maximum drag reduction occurs at θ=12.5^o, 15^o and 15^o for l/H = 0.1, 0.3 and 0.5, respectively, and the amounts of maximum drag reduction are 20, 41 and 45%. For the case of l/H = 0.3, separation starts to occur from θ= 6^o at the leading edge of the boat tail. This separated flow reattaches on the boat-tail surface and forms a small secondary separation bubble, which provides strong near-wall momentum and delays main separation down to the trailing edge of boat tail. The size of secondary separation bubble increases with increasing θ. At θ>16^o, main separation occurs at the leading edge of boat tail, and drag increases from the minimum value and reaches that of no control at large θ's.

  4. Model reduction and temperature uniformity control for rapid thermal chemical vapor deposition reactors

    NASA Astrophysics Data System (ADS)

    Theodoropoulou, Artemis-Georgia

    The consideration of Rapid Thermal Processing (RTP) in semiconductor manufacturing has recently been increasing. As a result, control of RTP systems has become of great importance since it is expected to help in addressing uniformity problems that, so far, have been obstructing the acceptance of the method. The spatial distribution appearing in RTP models necessitates the use of model reduction in order to obtain models of a size suitable for use in control algorithms. This dissertation addresses model reduction as well as control issues for RTP systems. A model of a three-zone Rapid Thermal Chemical Vapor Deposition (RTCVD) system is developed to study the effects of spatial wafer temperature patterns on polysilicon deposition uniformity. A sequence of simulated runs is performed, varying the lamp power profiles so that different wafer temperature modes are excited. The dominant spatial wafer thermal modes are extracted via Proper Orthogonal Decomposition and subsequently used as a set of trial functions to represent both the wafer temperature and deposition thickness. A collocation formulation of Galerkin's method is used to discretize the original modeling equations, giving a low-order model which loses little of the original, high-order model's fidelity. We make use of the excellent predictive capabilities of the reduced model to optimize power inputs to the lamp banks to achieve a desired polysilicon deposition thickness at the end of a run with minimal deposition spatial nonuniformity. Since the results illustrate that the optimization procedure benefits from the use of the reduced-order model, we further utilize the reduced order model for real time Model Based Control. The feedback controller is designed using the Internal Model Control (IMC) structure especially modified to handle systems described by ordinary differential and algebraic equations. The IMC controller is obtained using optimal control theory on singular arcs extended for multi input systems

  5. Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling

    SciTech Connect

    Lustbader, J. A.; Kreutzer, C.; Adelman, S.; Yeakel, S.; Zehme, J.

    2015-04-29

    Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy’s National Renewable Energy Laboratory’s CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, their effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. For this study, load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, and conductive pathways. The technologies selected for a complete-cab package of technologies were “ultra-white” paint, advanced insulation, and advanced curtains. To measure the impact of these technologies, a nationally-averaged solar-weighted reflectivity long-haul truck paint color was determined and applied to the baseline test vehicle. Using the complete-cab package of technologies, electrical energy consumption for long-haul truck daytime rest period air conditioning was reduced by at least 35% for summer weather conditions in Colorado. The National Renewable Energy Laboratory's CoolCalc model was then used to extrapolate the performance of the thermal load reduction technologies nationally for 161 major U.S. cities using typical weather conditions for each location over an entire year.

  6. Algorithms for optimizing CT fluence control

    NASA Astrophysics Data System (ADS)

    Hsieh, Scott S.; Pelc, Norbert J.

    2014-03-01

    The ability to customize the incident x-ray fluence in CT via beam-shaping filters or mA modulation is known to improve image quality and/or reduce radiation dose. Previous work has shown that complete control of x-ray fluence (ray-by-ray fluence modulation) would further improve dose efficiency. While complete control of fluence is not currently possible, emerging concepts such as dynamic attenuators and inverse-geometry CT allow nearly complete control to be realized. Optimally using ray-by-ray fluence modulation requires solving a very high-dimensional optimization problem. Most optimization techniques fail or only provide approximate solutions. We present efficient algorithms for minimizing mean or peak variance given a fixed dose limit. The reductions in variance can easily be translated to reduction in dose, if the original variance met image quality requirements. For mean variance, a closed form solution is derived. The peak variance problem is recast as iterated, weighted mean variance minimization, and at each iteration it is possible to bound the distance to the optimal solution. We apply our algorithms in simulations of scans of the thorax and abdomen. Peak variance reductions of 45% and 65% are demonstrated in the abdomen and thorax, respectively, compared to a bowtie filter alone. Mean variance shows smaller gains (about 15%).

  7. DTC Based Induction Motor Speed Control Using 10-Sector Methodology for Torque Ripple Reduction

    NASA Astrophysics Data System (ADS)

    Pavithra, S.; Dinesh Krishna, A. S.; Shridharan, S.

    2014-09-01

    A direct torque control (DTC) drive allows direct and independent control of flux linkage and electromagnetic torque by the selection of optimum inverter switching modes. It is a simple method of signal processing which gives excellent dynamic performance. Also transformation of coordinates and voltage decoupling are not required. However, the possible discrete inverter switching vectors cannot always generate exact stator voltage required, to obtain the demanded electromagnetic torque and flux linkages. This results in the production of ripples in the torque as well as flux waveforms. In the present paper a torque ripple reduction methodology is proposed. In this method the circular locus of flux phasor is divided into 10 sector as compared to six sector divisions in conventional DTC method. The basic DTC scheme and the 10-sector method are simulated and compared for their performance. An analysis is done with sector increment so that finally the torque ripple varies slightly as the sector is increased.

  8. Application of the controlled boundary layer concept for the wall interference reduction

    NASA Astrophysics Data System (ADS)

    Ivanov, A. I.; Kursakov, I. A.; Streltsov, E. V.

    2016-10-01

    Traditional boundaries of transonic wind tunnels (perforated and slotted walls) have some disadvantages that do not allow to completely remove wall interference on all main aerodynamic characteristics. This article focuses on the results of implementation of new boundary condition based, in general, on the idea of jet boundaries. Authors examine the implementation of the controlled boundary layer on solid walls, which characteristics were artificially increased with the aim of near-wall spoiler grid mounted at the test section entrance. The analysis underlines significant decreasing of wall interference on all main aerodynamic characteristics, including lift coefficient and pitching moment coefficient. We conclude that realization of the controlled boundary layer might become simple and rather effective method of wall-interference reduction.

  9. Model reduction algorithms for optimal control and importance sampling of diffusions

    NASA Astrophysics Data System (ADS)

    Hartmann, Carsten; Schütte, Christof; Zhang, Wei

    2016-08-01

    We propose numerical algorithms for solving optimal control and importance sampling problems based on simplified models. The algorithms combine model reduction techniques for multiscale diffusions and stochastic optimization tools, with the aim of reducing the original, possibly high-dimensional problem to a lower dimensional representation of the dynamics, in which only a few relevant degrees of freedom are controlled or biased. Specifically, we study situations in which either a reaction coordinate onto which the dynamics can be projected is known, or situations in which the dynamics shows strongly localized behavior in the small noise regime. No explicit assumptions about small parameters or scale separation have to be made. We illustrate the approach with simple, but paradigmatic numerical examples.

  10. On the Sequential Control of ITER Poloidal Field Converters for Reactive Power Reduction

    NASA Astrophysics Data System (ADS)

    Yuan, Hongwen; Fu, Peng; Gao, Ge; Huang, Liansheng; Song, Zhiquan; He, Shiying; Wu, Yanan; Dong, Lin; Wang, Min; Fang, Tongzhen

    2014-12-01

    Sequential control applied to the International Thermonuclear Experimental Reactor (ITER) poloidal field converter system for the purpose of reactive power reduction is the subject of this investigation. Due to the inherent characteristics of thyristor-based phase-controlled converter, the poloidal field converter system consumes a huge amount of reactive power from the grid, which subsequently results in a voltage drop at the 66 kV busbar if no measure is taken. The installation of a static var compensator rated for 750 MVar at the 66 kV busbar is an essential way to compensate reactive power to the grid, which is the most effective measure to solve the problem. However, sequential control of the multi-series converters provides an additional method to improve the natural power factor and thus alleviate the pressure of reactive power demand of the converter system without any additional cost. In the present paper, by comparing with the symmetrical control technique, the advantage of sequential control in reactive power consumption is highlighted. Simulation results based on SIMULINK are found in agreement with the theoretical analysis.

  11. Design of state-feedback controllers including sensitivity reduction, with applications to precision pointing

    NASA Technical Reports Server (NTRS)

    Hadass, Z.

    1974-01-01

    The design procedure of feedback controllers was described and the considerations for the selection of the design parameters were given. The frequency domain properties of single-input single-output systems using state feedback controllers are analyzed, and desirable phase and gain margin properties are demonstrated. Special consideration is given to the design of controllers for tracking systems, especially those designed to track polynomial commands. As an example, a controller was designed for a tracking telescope with a polynomial tracking requirement and some special features such as actuator saturation and multiple measurements, one of which is sampled. The resulting system has a tracking performance comparing favorably with a much more complicated digital aided tracker. The parameter sensitivity reduction was treated by considering the variable parameters as random variables. A performance index is defined as a weighted sum of the state and control convariances that sum from both the random system disturbances and the parameter uncertainties, and is minimized numerically by adjusting a set of free parameters.

  12. Simulation testing of unbiasedness of variance estimators

    USGS Publications Warehouse

    Link, W.A.

    1993-01-01

    In this article I address the evaluation of estimators of variance for parameter estimates. Given an unbiased estimator X of a parameter 0, and an estimator V of the variance of X, how does one test (via simulation) whether V is an unbiased estimator of the variance of X? The derivation of the test statistic illustrates the need for care in substituting consistent estimators for unknown parameters.

  13. Understanding the influence of watershed storage caused by human interferences on ET variance

    NASA Astrophysics Data System (ADS)

    Zeng, R.; Cai, X.

    2014-12-01

    Understanding the temporal variance of evapotranspiration (ET) at the watershed scale remains a challenging task, because it is affected by complex climate conditions, soil properties, vegetation, groundwater and human activities. In a changing environment with extensive and intensive human interferences, understanding ET variance and its factors is important for sustainable water resources management. This study presents an analysis of the effect of storage change caused by human activities on ET variance Irrigation usually filters ET variance through the use of surface and groundwater; however, over-amount irrigation may cause the depletion of watershed storage, which changes the coincidence of water availability and energy supply for ET. This study develops a framework by incorporating the water balance and the Budyko Hypothesis. It decomposes the ET variance to the variances of precipitation, potential ET, catchment storage change, and their covariances. The contributions of ET variance from the various components are scaled by some weighting functions, expressed as long-term climate conditions and catchment properties. ET variance is assessed by records from 32 major river basins across the world. It is found that ET variance is dominated by precipitation variance under hot-dry condition and by evaporative demand variance under cool-wet condition; while the coincidence of water and energy supply controls ET variance under moderate climate condition. Watershed storage change plays an increasing important role in determining ET variance with relatively shorter time scale. By incorporating storage change caused by human interferences, this framework corrects the over-estimation of ET variance in hot-dry climate and under-estimation of ET variance in cool-wet climate. Furthermore, classification of dominant factors on ET variance shows similar patterns as geographic zonation.

  14. Bangkok 2004. Drug control, human rights, and harm reduction in the age of AIDS.

    PubMed

    Elliott, Richard

    2004-12-01

    In many countries, HIV prevalence among people who use illicit drugs is high. Yet many governments resist implementing effective HIV prevention measures, and drug users often lack access to care, treatment, and support, including for HIV/AIDS. Growing evidence indicates the dominant prohibitionist approach to illicit drugs is ineffective--and even counterproductive, blocking or undermining measures shown to reduce harms to drug users and to communities affected by open drug scenes. The growing debate over global drug control policy could shift us collectively away from the current, failed prescriptions to a more rational, pragmatic, and health-promoting framework of harm reduction. This article by Richard Elliott is an abridged version of a paper prepared for "Human Rights at the Margins: HIV/AIDS, Prisoners, Drug Users and the Law," a satellite meeting held in Bangkok on 9 July 2004, and organized by the Canadian HIV/AIDS Legal Network and the Lawyers Collective HIV/AIDS Unit (India). The article briefly outlines the impact of these two different policy approaches, examines international law on drug control, discusses how harm reduction reflects a human rights-based approach to drugs, and assesses some strategies for reforming global policy on illicit drugs. PMID:15812929

  15. “APEC Blue”: Secondary Aerosol Reductions from Emission Controls in Beijing

    NASA Astrophysics Data System (ADS)

    Sun, Yele; Wang, Zifa; Wild, Oliver; Xu, Weiqi; Chen, Chen; Fu, Pingqing; Du, Wei; Zhou, Libo; Zhang, Qi; Han, Tingting; Wang, Qingqing; Pan, Xiaole; Zheng, Haitao; Li, Jie; Guo, Xiaofeng; Liu, Jianguo; Worsnop, Douglas R.

    2016-02-01

    China implemented strict emission control measures in Beijing and surrounding regions to ensure good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. We conducted synchronous aerosol particle measurements with two aerosol mass spectrometers at different heights on a meteorological tower in urban Beijing to investigate the variations in particulate composition, sources and size distributions in response to emission controls. Our results show consistently large reductions in secondary inorganic aerosol (SIA) of 61–67% and 51–57%, and in secondary organic aerosol (SOA) of 55% and 37%, at 260 m and ground level, respectively, during the APEC summit. These changes were mainly caused by large reductions in accumulation mode particles and by suppression of the growth of SIA and SOA by a factor of 2–3, which led to blue sky days during APEC commonly referred to as “APEC Blue”. We propose a conceptual framework for the evolution of primary and secondary species and highlight the importance of regional atmospheric transport in the formation of severe pollution episodes in Beijing. Our results indicate that reducing the precursors of secondary aerosol over regional scales is crucial and effective in suppressing the formation of secondary particulates and mitigating PM pollution.

  16. Chemoselective reduction and oxidation of ketones in water through control of the electron transfer pathway.

    PubMed

    Kim, Sun Min; Yoo, Ho Sung; Hosono, Hideo; Yang, Jung Woon; Kim, Sung Wng

    2015-05-28

    The selective synthesis of different products from the same starting materials in water, which is the most abundant solvent in nature, is a crucial issue as it maximizes the utilization of materials. Realizing such reactions for ketones is of considerable importance because numerous organic functionalities can be obtained via nucleophilic addition reactions. Herein, we report chemoselective reduction and oxidation reactions of 1,2-diketones in water, which initiates anionic electron transfer from the inorganic electride [Ca24Al28O64](4+)·4e(-), through controlling the pathway of the electrons to substrates. The generation of different radical species for transient intermediates was the key process required to control the reaction selectivity, which was achieved by reacting the anionic electrons with either diketones or O2, leading to the formation of ketyl dianion and superoxide radicals in the reduction and oxidation reactions, respectively. This methodology that utilizes electrides may provide an alternative to the pulse radiolysis of water in synthetic chemistry.

  17. “APEC Blue”: Secondary Aerosol Reductions from Emission Controls in Beijing

    PubMed Central

    Sun, Yele; Wang, Zifa; Wild, Oliver; Xu, Weiqi; Chen, Chen; Fu, Pingqing; Du, Wei; Zhou, Libo; Zhang, Qi; Han, Tingting; Wang, Qingqing; Pan, Xiaole; Zheng, Haitao; Li, Jie; Guo, Xiaofeng; Liu, Jianguo; Worsnop, Douglas R.

    2016-01-01

    China implemented strict emission control measures in Beijing and surrounding regions to ensure good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. We conducted synchronous aerosol particle measurements with two aerosol mass spectrometers at different heights on a meteorological tower in urban Beijing to investigate the variations in particulate composition, sources and size distributions in response to emission controls. Our results show consistently large reductions in secondary inorganic aerosol (SIA) of 61–67% and 51–57%, and in secondary organic aerosol (SOA) of 55% and 37%, at 260 m and ground level, respectively, during the APEC summit. These changes were mainly caused by large reductions in accumulation mode particles and by suppression of the growth of SIA and SOA by a factor of 2–3, which led to blue sky days during APEC commonly referred to as “APEC Blue”. We propose a conceptual framework for the evolution of primary and secondary species and highlight the importance of regional atmospheric transport in the formation of severe pollution episodes in Beijing. Our results indicate that reducing the precursors of secondary aerosol over regional scales is crucial and effective in suppressing the formation of secondary particulates and mitigating PM pollution. PMID:26891104

  18. Chemoselective reduction and oxidation of ketones in water through control of the electron transfer pathway

    PubMed Central

    Kim, Sun Min; Yoo, Ho Sung; Hosono, Hideo; Yang, Jung Woon; Kim, Sung Wng

    2015-01-01

    The selective synthesis of different products from the same starting materials in water, which is the most abundant solvent in nature, is a crucial issue as it maximizes the utilization of materials. Realizing such reactions for ketones is of considerable importance because numerous organic functionalities can be obtained via nucleophilic addition reactions. Herein, we report chemoselective reduction and oxidation reactions of 1,2-diketones in water, which initiates anionic electron transfer from the inorganic electride [Ca24Al28O64]4+·4e−, through controlling the pathway of the electrons to substrates. The generation of different radical species for transient intermediates was the key process required to control the reaction selectivity, which was achieved by reacting the anionic electrons with either diketones or O2, leading to the formation of ketyl dianion and superoxide radicals in the reduction and oxidation reactions, respectively. This methodology that utilizes electrides may provide an alternative to the pulse radiolysis of water in synthetic chemistry. PMID:26020413

  19. The Electrochemical Reduction of Chromium Sesquioxide in Molten Calcium Chloride under Cathodic Potential Control

    NASA Astrophysics Data System (ADS)

    Schwandt, Carsten; Fray, Derek J.

    2007-11-01

    Electrochemical polarization and reduction experiments are reported which were performed with a three-terminal cell and a molten salt electrolyte consisting of calcium chloride with additions of calcium oxide. Employing a metal cathode, a graphite anode and a pseudo-reference electrode also made from graphite, polarization measurements were carried out with the aim to validate the performance of the pseudo-reference electrode and to assess the stability of the electrolyte. Using a chromium sesquioxide cathode in conjunction with a graphite anode and a graphite pseudo-reference electrode, electrochemical reduction experiments were conducted under potentiostatic control. The key results are: a graphite pseudo-reference electrode has been shown to be appropriate in the present type of molten salt electrochemical experiments that take place on a time scale of many hours; the conversion of chromium oxide into chromium metal has been accomplished under cathodic potential control and in the absence of calcium metal deposition; a significant amount of calcium oxide in the calcium chloride has been found necessary to preclude anodic chlorine formation throughout the entire experiment; a considerable overpotential has been identified at the anode.

  20. Treating fibromyalgia with mindfulness-based stress reduction: results from a 3-armed randomized controlled trial.

    PubMed

    Schmidt, Stefan; Grossman, Paul; Schwarzer, Barbara; Jena, Susanne; Naumann, Johannes; Walach, Harald

    2011-02-01

    Mindfulness-based stress reduction (MBSR) is a structured 8-week group program teaching mindfulness meditation and mindful yoga exercises. MBSR aims to help participants develop nonjudgmental awareness of moment-to-moment experience. Fibromyalgia is a clinical syndrome with chronic pain, fatigue, and insomnia as major symptoms. Efficacy of MBSR for enhanced well-being of fibromyalgia patients was investigated in a 3-armed trial, which was a follow-up to an earlier quasi-randomized investigation. A total of 177 female patients were randomized to one of the following: (1) MBSR, (2) an active control procedure controlling for nonspecific effects of MBSR, or (3) a wait list. The major outcome was health-related quality of life (HRQoL) 2 months post-treatment. Secondary outcomes were disorder-specific quality of life, depression, pain, anxiety, somatic complaints, and a proposed index of mindfulness. Of the patients, 82% completed the study. There were no significant differences between groups on primary outcome, but patients overall improved in HRQoL at short-term follow-up (P=0.004). Post hoc analyses showed that only MBSR manifested a significant pre-to-post-intervention improvement in HRQoL (P=0.02). Furthermore, multivariate analysis of secondary measures indicated modest benefits for MBSR patients. MBSR yielded significant pre-to-post-intervention improvements in 6 of 8 secondary outcome variables, the active control in 3, and the wait list in 2. In conclusion, primary outcome analyses did not support the efficacy of MBSR in fibromyalgia, although patients in the MBSR arm appeared to benefit most. Effect sizes were small compared to the earlier, quasi-randomized investigation. Several methodological aspects are discussed, e.g., patient burden, treatment preference and motivation, that may provide explanations for differences. In a 3-armed randomized controlled trial in female patients suffering from fibromyalgia, patients benefited modestly from a mindfulness

  1. 40 CFR 59.106 - Variance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings § 59.106 Variance. (a) Any regulated...

  2. 40 CFR 59.106 - Variance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings § 59.106 Variance. (a) Any regulated...

  3. Multireader multicase variance analysis for binary data.

    PubMed

    Gallas, Brandon D; Pennello, Gene A; Myers, Kyle J

    2007-12-01

    Multireader multicase (MRMC) variance analysis has become widely utilized to analyze observer studies for which the summary measure is the area under the receiver operating characteristic (ROC) curve. We extend MRMC variance analysis to binary data and also to generic study designs in which every reader may not interpret every case. A subset of the fundamental moments central to MRMC variance analysis of the area under the ROC curve (AUC) is found to be required. Through multiple simulation configurations, we compare our unbiased variance estimates to naïve estimates across a range of study designs, average percent correct, and numbers of readers and cases.

  4. 40 CFR 59.106 - Variance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings § 59.106 Variance. (a) Any regulated...

  5. 40 CFR 59.106 - Variance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings § 59.106 Variance. (a) Any regulated...

  6. 40 CFR 59.106 - Variance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings § 59.106 Variance. (a) Any regulated...

  7. Control and reduction of immersion defectivity for yield enhancement at high volume production

    NASA Astrophysics Data System (ADS)

    Nakano, Katsushi; Seki, Rei; Sekito, Toshiyuki; Yoshida, Masato; Fujiwara, Tomoharu; Iriuchijima, Yasuhiro; Owa, Soichi

    2009-03-01

    Volume device manufacturing using immersion lithography is widely accepted as the solution for patterning IC features below 40 nm half pitch. In order to ensure high yield and steady productivity tight control of defectivity is essential. A major source of defects and tool contamination is the particles introduced by incoming wafers. Particles can be categorized in two groups: particles attached to wafer surface or residues on the wafer edge. Surface or edge peeling of topcoats can also be a source of particle. Adhesion force between topcoat or topcoat-less (TC-less) resist and wafer is one of the most important parameter for particle reduction. Peeling test results proved that TC-less resist has better adhesion performance than topcoat. One of the most commonly used adhesion promoting material is hexamethyldisilazane (HMDS). Application condition of this material is an important factor in preventing wafer edge and surface topcoat peeling. Studies have shown lower temperature and longer application of HMDS shows better adhesion result. Maintaining a clean wafer surface is also a very important factor for particle reduction. Pre-rinse, which can rinse off particles before exposure, was evaluated and the efficiency was confirmed. Edge particles are more effectively reduced by pre-rinse, because weakly attached topcoat and wafer edge residues were effectively removed by pre-rinse. For further particle reduction, edge residue reduction and cut line roughness improvement were evaluated and their effectiveness was confirmed. Lower cut position achieved improved particle counts on both topcoat and TC-less resist; more frequent contact between water and cut-line can weaken the adhesion and consequently peel off topcoat or TC-less resist. Finally the relationship between defectivity and hydrophobicity is analyzed, high Receding Contact Angle (RCA) showed better defectivity result. Topcoat and TC-less process is compared for each defectivity reduction methodology and for

  8. Control of turbulent flow over an articulating turret for reduction of adverse aero-optic effects

    NASA Astrophysics Data System (ADS)

    Wallace, Ryan

    2011-12-01

    Force Research Laboratory wind tunnel at Wright-Patterson Air Force Base. Direct measurements of the aero-optic effects were taken via a Malley probe at a fixed pitch angle with and without suction control at a Mach number 0.3, and a corresponding Reynolds number of 2,000,000. Reduction of the aero-optic effects in this test demonstrated that suction control is a practical control input to reduce the near field wavefront abberations due to the turbulent flow over the aperture.

  9. Controlled reduction of red mud waste to produce active systems for environmental applications: heterogeneous Fenton reaction and reduction of Cr(VI).

    PubMed

    Costa, Regina C C; Moura, Flávia C C; Oliveira, Patrícia E F; Magalhães, Fabiano; Ardisson, José D; Lago, Rochel M

    2010-02-01

    In this work, controlled reduction of red mud with H(2) was used to produce active systems for two different environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Mössbauer, powder X-ray diffraction, thermal analyses and scanning electron microscopy analyses showed that at different temperatures, i.e. 300, 400, 500 and 600 degrees C, H(2) reduces red mud to different phases, mainly Fe(3)O(4), Fe(0)/Fe(3)O(4) and Fe(0). These Fe phases are dispersed on Al, Si and Ti oxides present in the red mud and show high reactivity towards two environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI). Reduction with H(2) at 400 degrees C showed the best results for the oxidation of the model dye methylene blue with H(2)O(2) at neutral pH due to the presence of the composite Fe(0)/Fe(3)O(4). The reduced red mud at 500-600 degrees C produced Fe(0) highly active for the reduction of Cr(VI) in aqueous medium. Another feature of these red mud based system is that after deactivation due to extensive use they can be completely regenerated by simple treatment with H(2).

  10. Control of combustion-generated nitrogen oxides by selective non-catalytic reduction.

    PubMed

    Javed, M Tayyeb; Irfan, Naseem; Gibbs, B M

    2007-05-01

    Controlling nitrogen oxides (NO(x)) emissions is becoming a daunting technical challenge as increasingly strict emission limits are being imposed. The stringent regulations have prompted the innovation and characterization of NO(x) control technologies suitable for various applications. This paper presents a review on NO(x) removal techniques with particular reference to selective non-catalytic reduction (SNCR) technology. This includes initially how SNCR emerged as a technology along with a comparison with other relevant technologies. A review of various features related to selective non-catalytic gas phase injection of ammonia and ammonium salts (as reducing agent) is presented. The use of urea solution as a reducing agent and its performance in laboratory and pilot scale tests as well as large-scale applications is also discussed. Use of cyanuric acid as a potential reducing agent is also presented. The underlying reaction mechanisms have been reviewed for ammonia, urea and cyanuric acid for the explanation of various observations. Computational fluid dynamics (CFD) modeling as applied to SNCR is also presented. Subsequently the use of SNCR coupled with other in-combustion and post-combustion NO(x) control techniques is elaborated. Additionally, a two-stage NO(x) removal strategy to control un-reacted ammonia slip and to improve overall efficiency is discussed. At the end a summary is given which highlights various areas needing further research.

  11. Reduction of Helicopter BVI Noise, Vibration, and Power Consumption Through Individual Blade Control

    NASA Technical Reports Server (NTRS)

    Jacklin, Stephen A.; Blaas, Achim; Teves, Dietrich; Kube, Roland; Warmbrodt, William (Technical Monitor)

    1994-01-01

    A wind tunnel test was conducted with a full-scale BO 105 helicopter rotor to evaluate the potential of open-loop individual blade control (IBC) to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations. The wind tunnel test was an international collaborative effort between NASA/U.S. Army AFDD, ZF Luftfahrttechnik, Eurocopter Deutschland, and the German Aerospace Laboratory (DLR) and was conducted under the auspices of the U.S./German MOU on Rotorcraft Aeromechanics. In this test the normal blade pitch links of the rotor were replaced by servo-actuators so that the pitch of each blade could be controlled independently of the other blades. The specially designed servoactuators and IBC control system were designed and manufactured by ZF Luftfahrttechnik, GmbH. The wind tunnel test was conducted in the 40- by 80-Foot Wind Tunnel at the NASA Ames Research Center. An extensive amount of measurement information was acquired for each IBC data point. These data include rotor performance, static and dynamic hub forces and moments, rotor loads, control loads, inboard and outboard blade pitch motion, and BVI noise data. The data indicated very significant (80 percent) simultaneous reductions in both BVI noise and hub vibrations could be obtained using multi-harmonic input at the critical descent (terminal approach) condition. The data also showed that performance improvements of up to 7 percent could be obtained using 2P input at high-speed forward flight conditions.

  12. An active structural acoustic control approach for the reduction of the structure-borne road noise

    NASA Astrophysics Data System (ADS)

    Douville, Hugo; Berry, Alain; Masson, Patrice

    2002-11-01

    The reduction of the structure-borne road noise generated inside the cabin of an automobile is investigated using an Active Structural Acoustic Control (ASAC) approach. First, a laboratory test bench consisting of a wheel/suspension/lower suspension A-arm assembly has been developed in order to identify the vibroacoustic transfer paths (up to 250 Hz) for realistic road noise excitation of the wheel. Frequency Response Function (FRF) measurements between the excitation/control actuators and each suspension/chassis linkage are used to characterize the different transfer paths that transmit energy through the chassis of the car. Second, a FE/BE model (Finite/Boundary Elements) was developed to simulate the acoustic field of an automobile cab interior. This model is used to predict the acoustic field inside the cabin as a response to the measured forces applied on the suspension/chassis linkages. Finally, an experimental implementation of ASAC is presented. The control approach relies on the use of inertial actuators to modify the vibration behavior of the suspension and the automotive chassis such that its noise radiation efficiency is decreased. The implemented algorithm consists of a MIMO (Multiple-Input-Multiple-Output) feedforward configuration with a filtered-X LMS algorithm using an advanced reference signal (width FIR filters) using the Simulink/Dspace environment for control prototyping.

  13. A randomised controlled trial of stress reduction for hypertension in older African Americans.

    PubMed

    Schneider, R H; Staggers, F; Alxander, C N; Sheppard, W; Rainforth, M; Kondwani, K; Smith, S; King, C G

    1995-11-01

    We tested the short-term efficacy and feasibility of two stress education approaches toe the treatment of mild hypertension in older African Americans. This was a randomized, controlled, single-blind trial with 3 months of follow-up in primary care, inner-city health center. Of 213 African American men and women screened, 127 individuals (aged 55 to 85 years with initial diastolic pressure of 90 to 109 mm Hg, systolic pressure of < or = 189 mm Hg, and final baseline blood pressure of < or = 179/104 mm Hg) were selected. Of these, 16 did not complete follow-up blood pressure measurements. Mental and physical stress reduction approaches (Transcendental Meditation and progressive muscle relaxation) were compared with a lifestyle modification education control program and with each other. The primary outcome measures were changes in clinic diastolic and systolic pressures from baseline to final follow-up, measured by blinded observers. The secondary measures were linear blood pressure trends, changes in home blood pressure, and intervention compliance. Adjusted for significant baseline differences and compared with control, Transcendental Meditation reduced systolic pressure by 10.7 mm Hg (P < .0003) and diastolic pressure by 6.4 mm Hg (P <.00005). Progressive muscle relaxation lowered systolic pressure by 4.7 mm Hg (P = 0054) and diastolic pressure by 3.3 mm Hg (P <.02). The reductions in the Transcendental Meditation group were significantly greater than in the progressive muscle relaxation group for both systolic blood pressure (P = .02) and diastolic blood pressure (P = .03). Linear trend analysis confirmed these patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Effective and viable mind-body stress reduction in the workplace: a randomized controlled trial.

    PubMed

    Wolever, Ruth Q; Bobinet, Kyra J; McCabe, Kelley; Mackenzie, Elizabeth R; Fekete, Erin; Kusnick, Catherine A; Baime, Michael

    2012-04-01

    Highly stressed employees are subject to greater health risks, increased cost, and productivity losses than those with normal stress levels. To address this issue in an evidence-based manner, worksite stress management programs must be able to engage individuals as well as capture data on stress, health indices, work productivity, and health care costs. In this randomized controlled pilot, our primary objective was to evaluate the viability and proof of concept for two mind-body workplace stress reduction programs (one therapeutic yoga-based and the other mindfulness-based), in order to set the stage for larger cost-effectiveness trials. A second objective was to evaluate 2 delivery venues of the mindfulness-based intervention (online vs. in-person). Intention-to-treat principles and 2 (pre and post) × 3 (group) repeated-measures analysis of covariance procedures examined group differences over time on perceived stress and secondary measures to clarify which variables to include in future studies: sleep quality, mood, pain levels, work productivity, mindfulness, blood pressure, breathing rate, and heart rate variability (a measure of autonomic balance). Two hundred and thirty-nine employee volunteers were randomized into a therapeutic yoga worksite stress reduction program, 1 of 2 mindfulness-based programs, or a control group that participated only in assessment. Compared with the control group, the mind-body interventions showed significantly greater improvements on perceived stress, sleep quality, and the heart rhythm coherence ratio of heart rate variability. The two delivery venues for the mindfulness program produced basically equivalent results. Both the mindfulness-based and therapeutic yoga programs may provide viable and effective interventions to target high stress levels, sleep quality, and autonomic balance in employees.

  15. Uranium reduction by Shewanella oneidensis MR-1 as a function of NaHCO3 concentration: surface complexation control of reduction kinetics.

    PubMed

    Sheng, Ling; Fein, Jeremy B

    2014-04-01

    It is crucial to determine the controls on the kinetics of U(VI) bioreduction in order to understand and model the fate and mobility of U in groundwater systems and also to enhance the effectiveness of U bioremediation strategies. In this study, we measured the rate of U(VI) reduction by Shewanella oneidensis strain MR-1 as function of NaHCO3 concentration. The experiments demonstrate that increasing concentrations of NaHCO3 in the system lead to slower U(VI) reduction kinetics. The NaHCO3 concentration also strongly affects the speciation of U(VI) on the bacterial cell envelope. We used a thermodynamic surface complexation modeling approach to determine the speciation and concentration of U(VI) adsorbed onto the bacteria as a function of the NaHCO3 concentration in the experimental systems. We observed a strong positive correlation between the measured U(VI) reduction rates and the calculated total concentration of U(VI) surface complexes formed on the bacterial cell envelope. This positive correlation indicates that the speciation and concentration of U(VI) adsorbed on the bacterial cell envelope control the kinetics of U(VI) bioreduction under the experimental conditions. The results of this study serve as a basis for developing speciation-based kinetic rate laws for enzymatic reduction of U(VI) by bacteria. PMID:24576101

  16. Supporting the President's Arms Control and Nonproliferation Agenda: Transparency and Verification for Nuclear Arms Reductions

    SciTech Connect

    Doyle, James E; Meek, Elizabeth

    2009-01-01

    The President's arms control and nonproliferation agenda is still evolving and the details of initiatives supporting it remain undefined. This means that DOE, NNSA, NA-20, NA-24 and the national laboratories can help define the agenda, and the policies and the initiatives to support it. This will require effective internal and interagency coordination. The arms control and nonproliferation agenda is broad and includes the path-breaking goal of creating conditions for the elimination of nuclear weapons. Responsibility for various elements of the agenda will be widely scattered across the interagency. Therefore an interagency mapping exercise should be performed to identify the key points of engagement within NNSA and other agencies for creating effective policy coordination mechanisms. These can include informal networks, working groups, coordinating committees, interagency task forces, etc. It will be important for NA-20 and NA-24 to get a seat at the table and a functional role in many of these coordinating bodies. The arms control and nonproliferation agenda comprises both mature and developing policy initiatives. The more mature elements such as CTBT ratification and a follow-on strategic nuclear arms treaty with Russia have defined milestones. However, recent press reports indicate that even the START follow-on strategic arms pact that is planned to be complete by the end of 2009 may take significantly longer and be more expansive in scope. The Russians called for proposals to count non-deployed as well as deployed warheads. Other elements of the agenda such as FMCT, future bilateral nuclear arms reductions following a START follow-on treaty, nuclear posture changes, preparations for an international nuclear security summit, strengthened international safeguards and multilateral verification are in much earlier stages of development. For this reason any survey of arms control capabilities within the USG should be structured to address potential needs across the

  17. Explaining Common Variance Shared by Early Numeracy and Literacy

    ERIC Educational Resources Information Center

    Davidse, N. J.; De Jong, M. T.; Bus, A. G.

    2014-01-01

    How can it be explained that early literacy and numeracy share variance? We specifically tested whether the correlation between four early literacy skills (rhyming, letter knowledge, emergent writing, and orthographic knowledge) and simple sums (non-symbolic and story condition) reduced after taking into account preschool attention control,…

  18. 21 CFR 1010.4 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Variances. 1010.4 Section 1010.4 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) RADIOLOGICAL HEALTH... and Radiological Health, Food and Drug Administration, may grant a variance from one or...

  19. On Some Representations of Sample Variance

    ERIC Educational Resources Information Center

    Joarder, Anwar H.

    2002-01-01

    The usual formula for variance depending on rounding off the sample mean lacks precision, especially when computer programs are used for the calculation. The well-known simplification of the total sums of squares does not always give benefit. Since the variance of two observations is easily calculated without the use of a sample mean, and the…

  20. Save money by understanding variance and tolerancing.

    PubMed

    Stuart, K

    2007-01-01

    Manufacturing processes are inherently variable, which results in component and assembly variance. Unless process capability, variance and tolerancing are fully understood, incorrect design tolerances may be applied, which will lead to more expensive tooling, inflated production costs, high reject rates, product recalls and excessive warranty costs. A methodology is described for correctly allocating tolerances and performing appropriate analyses.

  1. Nonlinear Epigenetic Variance: Review and Simulations

    ERIC Educational Resources Information Center

    Kan, Kees-Jan; Ploeger, Annemie; Raijmakers, Maartje E. J.; Dolan, Conor V.; van Der Maas, Han L. J.

    2010-01-01

    We present a review of empirical evidence that suggests that a substantial portion of phenotypic variance is due to nonlinear (epigenetic) processes during ontogenesis. The role of such processes as a source of phenotypic variance in human behaviour genetic studies is not fully appreciated. In addition to our review, we present simulation studies…

  2. 10 CFR 851.31 - Variance process.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.31 Variance process. (a) Application... that the contractor has taken to inform the affected workers of the application, which must include... application and specifying where a copy may be examined at the place or places where notices to workers...

  3. 10 CFR 851.31 - Variance process.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.31 Variance process. (a) Application... that the contractor has taken to inform the affected workers of the application, which must include... application and specifying where a copy may be examined at the place or places where notices to workers...

  4. 10 CFR 851.31 - Variance process.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.31 Variance process. (a) Application... that the contractor has taken to inform the affected workers of the application, which must include... application and specifying where a copy may be examined at the place or places where notices to workers...

  5. Entropy, Fisher Information and Variance with Frost-Musulin Potenial

    NASA Astrophysics Data System (ADS)

    Idiodi, J. O. A.; Onate, C. A.

    2016-09-01

    This study presents the Shannon and Renyi information entropy for both position and momentum space and the Fisher information for the position-dependent mass Schrödinger equation with the Frost-Musulin potential. The analysis of the quantum mechanical probability has been obtained via the Fisher information. The variance information of this potential is equally computed. This controls both the chemical properties and physical properties of some of the molecular systems. We have observed the behaviour of the Shannon entropy. Renyi entropy, Fisher information and variance with the quantum number n respectively.

  6. Rheostat Re-Wired: Alternative Hypotheses for the Control of Thioredoxin Reduction Potentials

    PubMed Central

    Bewley, Kathryn D.; Dey, Mishtu; Bjork, Rebekah E.; Mitra, Sangha; Chobot, Sarah E.; Drennan, Catherine L.; Elliott, Sean J.

    2015-01-01

    Thioredoxins are small soluble proteins that contain a redox-active disulfide (CXXC). These disulfides are tuned to oxidizing or reducing potentials depending on the function of the thioredoxin within the cell. The mechanism by which the potential is tuned has been controversial, with two main hypotheses: first, that redox potential (Em) is specifically governed by a molecular ‘rheostat’—the XX amino acids, which influence the Cys pKa values, and thereby, Em; and second, the overall thermodynamics of protein folding stability regulates the potential. Here, we use protein film voltammetry (PFV) to measure the pH dependence of the redox potentials of a series of wild-type and mutant archaeal Trxs, PFV and glutathionine-equilibrium to corroborate the measured potentials, the fluorescence probe BADAN to measure pKa values, guanidinium-based denaturation to measure protein unfolding, and X-ray crystallography to provide a structural basis for our functional analyses. We find that when these archaeal thioredoxins are probed directly using PFV, both the high and low potential thioredoxins display consistent 2H+:2e- coupling over a physiological pH range, in conflict with the conventional ‘rheostat’ model. Instead, folding measurements reveals an excellent correlation to reduction potentials, supporting the second hypothesis and revealing the molecular mechanism of reduction potential control in the ubiquitous Trx family. PMID:25874934

  7. JV Task 104 - Risk Reduction Using Innovative Vacuum-Enhanced Plume Controls

    SciTech Connect

    Jaroslav Solc; Barry Botnen

    2009-03-01

    The Energy & Environmental Research Center (EERC) conducted remediation of hydrocarbon-contaminated soils and groundwater at the Vining Oil site in Carrington, North Dakota. The primary technological synergies included (1) contaminant recovery using simultaneous operation of multiphase recovery and high-vacuum soil vapor extraction (SVE) and (2) vacuum-controlled air and ozone sparging on the periphery of an induced hydraulic and pneumatic depression. Final risk reduction steps included design and retrofit for the municipal well. The successful remediation effort resulted in the reduction of long-term health risks associated with rate-limited contaminant release within the capture zone for the municipal well and allowed for its reintegration into the water supply system. Contaminant recovery for the remediation period of September 2006 to June 2008 totaled over 12,653 lb (5,740 kg) of hydrocarbons, an equivalent to 2022 gallons (7653 l) of product. Integration of the air-sparging subsystem operated simultaneously with multiphase extraction and SVE systems resulted in accelerated volatile organic contaminant transport from the saturated zone and increased contaminants of concern recovery. Delivery of over 7.7 million ft{sup 3} of oxygen (219.8 thousand m{sup 3}) into the contaminated aquifer would translate into in situ biodegradation of 2007 kg (4424 lb) of benzene and provide for long term stimulation of the natural attenuation process.

  8. Design and Analysis of the ST7 Disturbance Reduction System (DRS) Spacecraft Controller

    NASA Technical Reports Server (NTRS)

    Maghami, P. G.; Markley, F. L.; Houghton, M. B.; Dennehy, C. J.

    2003-01-01

    The Space Technology 7 experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: a gravitational reference sensor employing a free-floating test mass and a set of micronewton colloidal thrusters. The Disturbance Reduction System is designed to maintain a spacecraft's position with respect to the free-floating test mass to less than 10 nm/square root of Hz, over the frequency range 10(exp -3) Hz to 10(exp -2) Hz. This paper presents the design and analysis of the coupled drag-free and attitude control system that closes the loop between the gravitational reference sensor and the micronewton thrusters while incorporating star tracker data at low frequencies. The effects of actuation and measurement noise and disturbances on the spacecraft and test masses are evaluated in a seven-degree-of-freedom planar model incorporating two translational and one rotational degrees of freedom for the spacecraft and two translational degrees of freedom for each test mass.

  9. Recruiting and retaining family caregivers to a randomized controlled trial on mindfulness-based stress reduction.

    PubMed

    Whitebird, Robin R; Kreitzer, Mary Jo; Lewis, Beth A; Hanson, Leah R; Crain, A Lauren; Enstad, Chris J; Mehta, Adele

    2011-09-01

    Caregivers for a family member with dementia experience chronic long-term stress that may benefit from new complementary therapies such as mindfulness-based stress reduction. Little is known however, about the challenges of recruiting and retaining family caregivers to research on mind-body based complementary therapies. Our pilot study is the first of its kind to successfully recruit caregivers for a family member with dementia to a randomized controlled pilot study of mindfulness-based stress reduction. The study used an array of recruitment strategies and techniques that were tailored to fit the unique features of our recruitment sources and employed retention strategies that placed high value on establishing early and ongoing communication with potential participants. Innovative recruitment methods including conducting outreach to health plan members and generating press coverage were combined with standard methods of community outreach and paid advertising. We were successful in exceeding our recruitment goal and retained 92% of the study participants at post-intervention (2 months) and 90% at 6 months. Recruitment and retention for family caregiver interventions employing mind-body based complementary therapies can be successful despite many challenges. Barriers include cultural perceptions about the use and benefit of complementary therapies, cultural differences with how the role of family caregiver is perceived, the use of group-based designs requiring significant time commitment by participants, and travel and respite care needs for busy family caregivers. PMID:21601010

  10. Recruiting and Retaining Family Caregivers to a Randomized Controlled Trial on Mindfulness-Based Stress Reduction

    PubMed Central

    Whitebird, Robin R.; Kreitzer, Mary Jo; Lewis, Beth A.; Hanson, Leah R.; Crain, A. Lauren; Enstad, Chris J.; Mehta, Adele

    2011-01-01

    Caregivers for a family member with dementia experience chronic long-term stress that may benefit from new complementary therapies such as mindfulness-based stress reduction. Little is known however, about the challenges of recruiting and retaining family caregivers to research on mind-body based complementary therapies. Our pilot study is the first of its kind to successfully recruit caregivers for a family member with dementia to a randomized controlled pilot study of mindfulness-based stress reduction. The study used an array of recruitment strategies and techniques that were tailored to fit the unique features of our recruitment sources and employed retention strategies that placed high value on establishing early and ongoing communication with potential participants. Innovative recruitment methods including conducting outreach to health plan members and generating press coverage were combined with standard methods of community outreach and paid advertising. We were successful in exceeding our recruitment goal and retained 92% of the study participants at post-intervention (2 months) and 90% at 6 months. Recruitment and retention for family caregiver interventions employing mind-body based complementary therapies can be successful despite many challenges. Barriers include cultural perceptions about the use and benefit of complementary therapies, cultural differences with how the role of family caregiver is perceived, the use of group-based designs requiring significant time commitment by participants, and travel and respite care needs for busy family caregivers. PMID:21601010

  11. Disturbance Reduction Control Design for the ST7 Flight Validation Experiment

    NASA Technical Reports Server (NTRS)

    Maghami, P. G.; Hsu, O. C.; Markley, F. L.; Houghton, M. B.

    2003-01-01

    The Space Technology 7 experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: a gravitational reference sensor employing a free-floating test mass, and a set of micro-Newton colloidal thrusters. The ST7 Disturbance Reduction System is designed to maintain the spacecraft's position with respect to a free-floating test mass to less than 10 nm/Hz, over the frequency range of 1 to 30 mHz. This paper presents the design and analysis of the coupled, drag-free and attitude control systems that close the loop between the gravitational reference sensor and the micro-Newton thrusters, while incorporating star tracker data at low frequencies. A full 18 degree-of-freedom model, which incorporates rigid-body models of the spacecraft and two test masses, is used to evaluate the effects of actuation and measurement noise and disturbances on the performance of the drag-free system.

  12. Biogeochemical controls on the product of microbial U(VI) reduction.

    PubMed

    Stylo, Malgorzata; Alessi, Daniel S; Shao, Paul PaoYun; Lezama-Pacheco, Juan S; Bargar, John R; Bernier-Latmani, Rizlan

    2013-01-01

    Biologically mediated immobilization of radionuclides in the subsurface is a promising strategy for the remediation of uranium-contaminated sites. During this process, soluble U(VI) is reduced by indigenous microorganisms to sparingly soluble U(IV). The crystalline U(IV) phase uraninite, or UO2, is the preferable end-product of bioremediation due to its relatively high stability and low solubility in comparison to biomass-associated nonuraninite U(IV) species that have been reported in laboratory and under field conditions. The goal of this study was to delineate the geochemical conditions that promote the formation of nonuraninite U(IV) versus uraninite and to decipher the mechanisms of its preferential formation. U(IV) products were prepared under varying geochemical conditions and characterized with X-ray absorption spectroscopy (XAS), scanning transmission X-ray microscopy (STXM), and various wet chemical methods. We report an increasing fraction of nonuraninite U(IV) species with decreasing initial U concentration. Additionally, the presence of several common groundwater solutes (sulfate, silicate, and phosphate) promote the formation of nonuraninite U(IV). Our experiments revealed that the presence of those solutes promotes the formation of bacterial extracellular polymeric substances (EPS) and increases bacterial viability, suggesting that the formation of nonuraninite U(IV) is due to a biological response to solute presence during U(VI) reduction. The results obtained from this laboratory-scale research provide insight into biogeochemical controls on the product(s) of uranium reduction during bioremediation of the subsurface.

  13. A Randomized, Controlled Trial of Home Injury Hazard Reduction: The HOME Injury Study

    PubMed Central

    Phelan, Kieran J.; Khoury, Jane; Xu, Yingying; Liddy, Stacey; Hornung, Richard; Lanphear, Bruce P.

    2013-01-01

    Objective Test the efficacy of an intervention of safety device installation on medically-attended injury in children birth to 3 years of age. Design A nested, prospective, randomized, controlled trial. Setting Indoor environment of housing units of mothers and children. Participants Mothers and their children enrolled in a birth cohort examining the effects of prevalent neurotoxicants on child development, the Home Observation and Measures of the Environment (HOME) Study. Intervention Installation of multiple, passive measures (stairgates, window locks, smoke & carbon monoxide detectors, to reduce exposure to injury hazards present in housing units. Outcome measure Self-reported and medically-attended and modifiable injury. Methods 1263 (14%) prenatal patients were eligible, 413 (33%) agreed to participate and 355 were randomly assigned to the experimental (n=181) or control (n=174) groups. Injury hazards were assessed at home visits by teams of trained research assistants using a validated survey. Safety devices were installed in intervention homes. Intention-to-treat analyses to test efficacy were conducted on: 1) total injury rates and 2) on injuries deemed, a priori, modifiable by the installation of safety devices. Rates of medically attended injuries (phone calls, office or emergency visits) were calculated using generalized estimating equations. Results The mean age of the children at intervention was 6 months. Injury hazards were significantly reduced in the intervention but not in control group homes at one and two years (p<0.004). There was not a significant difference in the rate for all medically-attended injuries in intervention compared with control group children, 14.3 (95%CI 9.7, 21.1) vs. 20.8 (14.4, 29.9) per 100 child-years (p=0.17) respectively; but there was a significant reduction in modifiable medically attended injuries in intervention compared with control group children, 2.3 (1.0, 5.5) vs. 7.7 (4.2, 14.2) per 100 child-years, respectively

  14. Portfolio optimization with mean-variance model

    NASA Astrophysics Data System (ADS)

    Hoe, Lam Weng; Siew, Lam Weng

    2016-06-01

    Investors wish to achieve the target rate of return at the minimum level of risk in their investment. Portfolio optimization is an investment strategy that can be used to minimize the portfolio risk and can achieve the target rate of return. The mean-variance model has been proposed in portfolio optimization. The mean-variance model is an optimization model that aims to minimize the portfolio risk which is the portfolio variance. The objective of this study is to construct the optimal portfolio using the mean-variance model. The data of this study consists of weekly returns of 20 component stocks of FTSE Bursa Malaysia Kuala Lumpur Composite Index (FBMKLCI). The results of this study show that the portfolio composition of the stocks is different. Moreover, investors can get the return at minimum level of risk with the constructed optimal mean-variance portfolio.

  15. 42 CFR 456.525 - Request for renewal of variance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., and Variances for Hospitals and Mental Hospitals Ur Plan: Remote Facility Variances from Time... variance to the Administrator at least 30 days before the variance expires. (b) The renewal request...

  16. Variance-reduced simulation of lattice discrete-time Markov chains with applications in reaction networks

    NASA Astrophysics Data System (ADS)

    Maginnis, P. A.; West, M.; Dullerud, G. E.

    2016-10-01

    We propose an algorithm to accelerate Monte Carlo simulation for a broad class of stochastic processes. Specifically, the class of countable-state, discrete-time Markov chains driven by additive Poisson noise, or lattice discrete-time Markov chains. In particular, this class includes simulation of reaction networks via the tau-leaping algorithm. To produce the speedup, we simulate pairs of fair-draw trajectories that are negatively correlated. Thus, when averaged, these paths produce an unbiased Monte Carlo estimator that has reduced variance and, therefore, reduced error. Numerical results for three example systems included in this work demonstrate two to four orders of magnitude reduction of mean-square error. The numerical examples were chosen to illustrate different application areas and levels of system complexity. The areas are: gene expression (affine state-dependent rates), aerosol particle coagulation with emission and human immunodeficiency virus infection (both with nonlinear state-dependent rates). Our algorithm views the system dynamics as a "black-box", i.e., we only require control of pseudorandom number generator inputs. As a result, typical codes can be retrofitted with our algorithm using only minor changes. We prove several analytical results. Among these, we characterize the relationship of covariances between paths in the general nonlinear state-dependent intensity rates case, and we prove variance reduction of mean estimators in the special case of affine intensity rates.

  17. Isolated metal active site concentration and stability control catalytic CO2 reduction selectivity.

    PubMed

    Matsubu, John C; Yang, Vanessa N; Christopher, Phillip

    2015-03-01

    CO2 reduction by H2 on heterogeneous catalysts is an important class of reactions that has been studied for decades. However, atomic scale details of structure-function relationships are still poorly understood. Particularly, it has been suggested that metal particle size plays a unique role in controlling the stability of CO2 hydrogenation catalysts and the distribution of active sites, which dictates reactivity and selectivity. These studies often have not considered the possible role of isolated metal active sites in the observed dependences. Here, we utilize probe molecule diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) with known site-specific extinction coefficients to quantify the fraction of Rh sites residing as atomically dispersed isolated sites (Rhiso), as well as Rh sites on the surface of Rh nanoparticles (RhNP) for a series of TiO2 supported Rh catalysts. Strong correlations were observed between the catalytic reverse water gas shift turn over frequency (TOF) and the fraction of Rhiso sites and between catalytic methanation TOF and the fraction of RhNP sites. Furthermore, it was observed that reaction condition-induced disintegration of Rh nanoparticles, forming Rhiso active sites, controls the changing reactivity with time on stream. This work demonstrates that isolated atoms and nanoparticles of the same metal on the same support can exhibit uniquely different catalytic selectivity in competing parallel reaction pathways and that disintegration of nanoparticles under reaction conditions can play a significant role in controlling stability.

  18. Composition-controlled PtCo alloy nanocubes with tuned electrocatalytic activity for oxygen reduction.

    PubMed

    Choi, Sang-Il; Lee, Su-Un; Kim, Woo Youn; Choi, Ran; Hong, Kwangwoo; Nam, Ki Min; Han, Sang Woo; Park, Joon T

    2012-11-01

    Modification of the electronic structure and lattice contraction of Pt alloy nanocatalysts through control over their morphology and composition has been a crucial issue for improving their electrocatalytic oxygen reduction reaction (ORR) activity. In the present work, we synthesized PtCo alloy nanocubes with controlled compositions (Pt(x)Co NCs, x = 2, 3, 5, 7, and 9) by regulating the ratio of surfactants and the amount of Co precursor to elucidate the effect of the composition of nanocatalysts on their ORR activity. Pt(x)Co NCs had a Pt-skin structure after electrochemical treatment. The electrocatalysis experiments revealed a strong correlation between ORR activity and Co composition. Pt₃Co NCs exhibited the best ORR performance among the various Pt(x)Co NCs. From density functional theory calculations, a typical volcano-type relationship was established between ORR activity and oxygen binding energy (E(OB)) on NC surfaces, which showed that Pt₃Co NCs had the optimal E(OB) to achieve the maximum ORR activity. X-ray photoelectron spectroscopy and X-ray diffraction measurements demonstrated that the electronic structure and lattice contraction of the Pt(x)Co NCs could be tuned by controlling the composition of NCs, which are highly correlated with the trends of E(OB) change.

  19. Isolated metal active site concentration and stability control catalytic CO2 reduction selectivity.

    PubMed

    Matsubu, John C; Yang, Vanessa N; Christopher, Phillip

    2015-03-01

    CO2 reduction by H2 on heterogeneous catalysts is an important class of reactions that has been studied for decades. However, atomic scale details of structure-function relationships are still poorly understood. Particularly, it has been suggested that metal particle size plays a unique role in controlling the stability of CO2 hydrogenation catalysts and the distribution of active sites, which dictates reactivity and selectivity. These studies often have not considered the possible role of isolated metal active sites in the observed dependences. Here, we utilize probe molecule diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) with known site-specific extinction coefficients to quantify the fraction of Rh sites residing as atomically dispersed isolated sites (Rhiso), as well as Rh sites on the surface of Rh nanoparticles (RhNP) for a series of TiO2 supported Rh catalysts. Strong correlations were observed between the catalytic reverse water gas shift turn over frequency (TOF) and the fraction of Rhiso sites and between catalytic methanation TOF and the fraction of RhNP sites. Furthermore, it was observed that reaction condition-induced disintegration of Rh nanoparticles, forming Rhiso active sites, controls the changing reactivity with time on stream. This work demonstrates that isolated atoms and nanoparticles of the same metal on the same support can exhibit uniquely different catalytic selectivity in competing parallel reaction pathways and that disintegration of nanoparticles under reaction conditions can play a significant role in controlling stability. PMID:25671686

  20. Delayed feedback control and phase reduction of unstable quasi-periodic orbits.

    PubMed

    Ichinose, Natsuhiro; Komuro, Motomasa

    2014-09-01

    The delayed feedback control (DFC) is applied to stabilize unstable quasi-periodic orbits (QPOs) in discrete-time systems. The feedback input is given by the difference between the current state and a time-delayed state in the DFC. However, there is an inevitable time-delay mismatch in QPOs. To evaluate the influence of the time-delay mismatch on the DFC, we propose a phase reduction method for QPOs and construct a phase response curve (PRC) from unstable QPOs directly. Using the PRC, we estimate the rotation number of QPO stabilized by the DFC. We show that the orbit of the DFC is consistent with the unstable QPO perturbed by a small state difference resulting from the time-delay mismatch, implying that the DFC can certainly stabilize the unstable QPO.

  1. Note: vibration reduction control of an atomic force microscope using an additional cantilever.

    PubMed

    Kim, Chulsoo; Jung, Jongkyu; Park, Kyihwan

    2011-11-01

    Since an atomic force microscope is used to measure sub-nanometer level precision, it is sensitive to external vibration. If the vibration can be measured by using an additional sensor, we can obtain the vibration-free signal by subtracting the vibration signal from the signal containing the vibration. To achieve a highly effective vibration rejection ratio, it is important to decide where to locate the additional sensor. This is because the vibration measured at the sensing position should have the same phase as that of the vibration in the signal. Vibration reduction control using this electrical sensing method is verified through time domain analysis and topology images of a standard grid sample.

  2. SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane

    NASA Astrophysics Data System (ADS)

    Akimoto, Hajime; Kurokawa, Jun`ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori

    2015-12-01

    The emissions of NOx and CO2 in East Asia (Northeast and Southeast Asia) contribute more than 30% of the global total since 2008, and consequently the control of air pollutants and CO2 alleviating regional air pollution and global climate change is of great concern of not only in this region but also worldwide. In order to arrive at a rational view of the short-lived climate pollutants (SLCPs) co-control approach in East Asia, the effectiveness of the reduction of NOx/NMVOC and CH4 emissions for the reduction of tropospheric O3 has been evaluated by individual and simultaneous 50%-reduction of the emissions in Northeast Asia (NEA) using both a global chemical climate model (CHASER/SPRINTARS-MIROC), and a regional chemical transport model (WRF-CMAQ). The simultaneous reduction of NOx/NMVOC and CH4 emissions was found to reduce the regional concentration of surface O3 in NEA, and globally averaged net radiative forcing most effectively. Global mean RF and regional air quality change were also evaluated for the climate stabilization scenario ("450-ppm"), and climate stabilization with additional air pollution mitigation strengthened scenario ("450-ppm-cntr") developed in IIASA with the aid of GAINS model. In the 450 ppm-cntr scenario, emissions of NOx NMVOC, BC and OC were further reduced respectively, for East Asia from the emissions in 450 ppm. The improvement of air quality as well as the mitigation of climate change would grant to the basis of the SLCP co-control approach in East Asia.

  3. Vibration reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade

    NASA Technical Reports Server (NTRS)

    Millott, T. A.; Friedmann, P. P.

    1994-01-01

    This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

  4. Portfolio optimization using median-variance approach

    NASA Astrophysics Data System (ADS)

    Wan Mohd, Wan Rosanisah; Mohamad, Daud; Mohamed, Zulkifli

    2013-04-01

    Optimization models have been applied in many decision-making problems particularly in portfolio selection. Since the introduction of Markowitz's theory of portfolio selection, various approaches based on mathematical programming have been introduced such as mean-variance, mean-absolute deviation, mean-variance-skewness and conditional value-at-risk (CVaR) mainly to maximize return and minimize risk. However most of the approaches assume that the distribution of data is normal and this is not generally true. As an alternative, in this paper, we employ the median-variance approach to improve the portfolio optimization. This approach has successfully catered both types of normal and non-normal distribution of data. With this actual representation, we analyze and compare the rate of return and risk between the mean-variance and the median-variance based portfolio which consist of 30 stocks from Bursa Malaysia. The results in this study show that the median-variance approach is capable to produce a lower risk for each return earning as compared to the mean-variance approach.

  5. Higher harmonic control analysis for vibration reduction of helicopter rotor systems

    NASA Technical Reports Server (NTRS)

    Nguyen, Khanh Q.

    1994-01-01

    An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor

  6. Control time reduction using virtual source projection for treating a leg sarcoma with nonlinear perfusion

    NASA Astrophysics Data System (ADS)

    Cheng, Kung-Shan; Yuan, Yu; Li, Zhen; Stauffer, Paul R.; Joines, William T.; Dewhirst, Mark W.; Das, Shiva K.

    2009-02-01

    Purpose: Blood perfusion is a well-known factor that complicates accurate control of heating during hyperthermia treatments of cancer. Since blood perfusion varies as a function of time, temperature and location, determination of appropriate power deposition pattern from multiple antenna array Hyperthermia systems and heterogeneous tissues is a difficult control problem. Therefore, we investigate the applicability of a real-time eigenvalue model reduction (virtual source - VS) reduced-order controller for hyperthermic treatments of tissue with nonlinearly varying perfusion. Methods: We impose a piecewise linear approximation to a set of heat pulses, each consisting of a 1-min heat-up, followed by a 2-min cool-down. The controller is designed for feedback from magnetic resonance temperature images (MRTI) obtained after each iteration of heat pulses to adjust the projected optimal setting of antenna phase and magnitude for selective tumor heating. Simulated temperature patterns with additive Gaussian noise with a standard deviation of 1.0°C and zero mean were used as a surrogate for MRTI. Robustness tests were conducted numerically for a patient's right leg placed at the middle of a water bolus surrounded by a 10-antenna applicator driven at 150 MHz. Robustness tests included added discrepancies in perfusion, electrical and thermal properties, and patient model simplifications. Results: The controller improved selective tumor heating after an average of 4-9 iterative adjustments of power and phase, and fulfilled satisfactory therapeutic outcomes with approximately 75% of tumor volumes heated to temperatures >43°C while maintaining about 93% of healthy tissue volume < 41°C. Adequate sarcoma heating was realized by using only 2 to 3 VSs rather than a much larger number of control signals for all 10 antennas, which reduced the convergence time to only 4 to 9% of the original value. Conclusions: Using a piecewise linear approximation to a set of heat pulses in a VS

  7. Investigation of effect of reduction of valve friction in a power control system by use of a vibrator

    NASA Technical Reports Server (NTRS)

    Phillips, William H

    1955-01-01

    Brief ground tests were made to determine the effect of reduction of valve friction in a power control system of a fighter airplane by use of a vibrator. The vibrator was found to be an effective means of overcoming adverse effects of valve friction on the control characteristics.

  8. 15 CFR 30.63 - Office of Management and Budget control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... collection requirement. (b) Display. 15 CFR section whereidentified and described Current OMB control No... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Office of Management and Budget control numbers assigned pursuant to the Paperwork Reduction Act. 30.63 Section 30.63 Commerce and...

  9. A Variance Based Active Learning Approach for Named Entity Recognition

    NASA Astrophysics Data System (ADS)

    Hassanzadeh, Hamed; Keyvanpour, Mohammadreza

    The cost of manually annotating corpora is one of the significant issues in many text based tasks such as text mining, semantic annotation and generally information extraction. Active Learning is an approach that deals with reduction of labeling costs. In this paper we proposed an effective active learning approach based on minimal variance that reduces manual annotation cost by using a small number of manually labeled examples. In our approach we use a confidence measure based on the model's variance that reaches a considerable accuracy for annotating entities. Conditional Random Field (CRF) is chosen as the underlying learning model due to its promising performance in many sequence labeling tasks. The experiments show that the proposed method needs considerably fewer manual labeled samples to produce a desirable result.

  10. Soybean products and reduction of breast cancer risk: a case–control study in Japan

    PubMed Central

    Hirose, K; Imaeda, N; Tokudome, Y; Goto, C; Wakai, K; Matsuo, K; Ito, H; Toyama, T; Iwata, H; Tokudome, S; Tajima, K

    2005-01-01

    Components of the Japanese diet, which might contribute to the relatively low breast cancer incidence rates in Japan, have not been clarified in detail. Since soybean products are widely consumed in Japan, a case–control study taking account of the menopausal status was conducted using data from the hospital-based epidemiologic research program at Aichi Cancer Center (HERPACC). In total, 167 breast cancer cases were included and 854 women confirmed as free of cancer were recruited as the control group. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by multiple logistic regression analysis. There were reductions in risk of breast cancer associated with high intake of soybean products among premenopausal women. Compared with women in the lowest tertile, the adjusted ORs for top tertile intake of tofu (soybean curd) was 0.49 (95% CI, 0.25–0.95). A significant decrease in premenopausal breast cancer risk was also observed for increasing consumption of isoflavones (OR=0.44; 95% CI, 0.22–0.89 for highest vs lowest tertile; P for trend=0.02). The present study found a statistically inverse association between tofu or isoflavone intake and risk of breast cancer in Japanese premenopausal women, while no statistically significant association was evident with the risk among postmenopausal women. PMID:15942624

  11. Encoding of natural sounds by variance of the cortical local field potential.

    PubMed

    Ding, Nai; Simon, Jonathan Z; Shamma, Shihab A; David, Stephen V

    2016-06-01

    Neural encoding of sensory stimuli is typically studied by averaging neural signals across repetitions of the same stimulus. However, recent work has suggested that the variance of neural activity across repeated trials can also depend on sensory inputs. Here we characterize how intertrial variance of the local field potential (LFP) in primary auditory cortex of awake ferrets is affected by continuous natural sound stimuli. We find that natural sounds often suppress the intertrial variance of low-frequency LFP (<16 Hz). However, the amount of the variance reduction is not significantly correlated with the amplitude of the mean response at the same recording site. Moreover, the variance changes occur with longer latency than the mean response. Although the dynamics of the mean response and intertrial variance differ, spectro-temporal receptive field analysis reveals that changes in LFP variance have frequency tuning similar to multiunit activity at the same recording site, suggesting a local origin for changes in LFP variance. In summary, the spectral tuning of LFP intertrial variance and the absence of a correlation with the amplitude of the mean evoked LFP suggest substantial heterogeneity in the interaction between spontaneous and stimulus-driven activity across local neural populations in auditory cortex. PMID:26912594

  12. Reduction of overweight and eating disorder symptoms via the Internet in adolescents: A randomized controlled trial

    PubMed Central

    Doyle, Angela Celio; Goldschmidt, Andrea; Huang, Christina; Winzelberg, Andrew J.; Taylor, C. Barr; Wilfley, Denise E.

    2008-01-01

    Purpose Overweight in adolescence is a significant problem which is associated with body dissatisfaction and eating disorder (ED) behaviors. Cost-effective methods for early intervention of obesity and prevention of ED are important due to the refractory nature of both. This multisite RCT evaluated an Internet-delivered program targeting weight loss and ED attitudes/behaviors in adolescents. Methods Eighty overweight 12-17-year olds completed Student Bodies 2 (SB2), a 16-week cognitive-behavioral program, or usual care (UC). Results BMI z-scores were reduced in the SB2 group compared to the UC group from baseline (BL) to post-intervention (p=.027; ηp2=.08). The SB2 group maintained this reduction in BMI-z at 4-month follow-up, but significant differences were not observed due to improvement in the UC group. The SB2 group evidenced greater increases in dietary restraint at post (p=.016) and less improvement on shape concerns at follow-up (p=.044), however, these differences were not clinically significant. No other statistically significant differences were noted between groups on ED attitudes/behaviors. SB2 participants reported using healthy eating- and physical activity-related skills more frequently than UC participants at post (p=.001) and follow-up (p=.012). Conclusions Findings suggest that an Internet-delivered intervention yielded a modest reduction in weight status that continued four months following treatment and that ED attitudes/behaviors were not significantly improved. Group differences on weight loss were not sustained at 4-month follow-up due to parallel improvements in the groups. Future studies are needed to improve program adherence and to further explore the efficacy of Internet-delivery of weight control programs for adolescents. PMID:18639791

  13. pH control for enhanced reductive bioremediation of chlorinated solvent source zones.

    PubMed

    Robinson, Clare; Barry, D A; McCarty, Perry L; Gerhard, Jason I; Kouznetsova, Irina

    2009-08-01

    Enhanced reductive dehalogenation is an attractive treatment technology for in situ remediation of chlorinated solvent DNAPL source areas. Reductive dehalogenation is an acid-forming process with hydrochloric acid and also organic acids from fermentation of the electron donors typically building up in the source zone during remediation. This can lead to groundwater acidification thereby inhibiting the activity of dehalogenating microorganisms. Where the soils' natural buffering capacity is likely to be exceeded, the addition of an external source of alkalinity is needed to ensure sustained dehalogenation. To assist in the design of bioremediation systems, an abiotic geochemical model was developed to provide insight into the processes influencing the groundwater acidity as dehalogenation proceeds, and to predict the amount of bicarbonate required to maintain the pH at a suitable level for dehalogenating bacteria (i.e., >6.5). The model accounts for the amount of chlorinated solvent degraded, site water chemistry, electron donor, alternative terminal electron-accepting processes, gas release and soil mineralogy. While calcite and iron oxides were shown to be the key minerals influencing the soil's buffering capacity, for the extensive dehalogenation likely to occur in a DNAPL source zone, significant bicarbonate addition may be necessary even in soils that are naturally well buffered. Results indicated that the bicarbonate requirement strongly depends on the electron donor used and availability of competing electron acceptors (e.g., sulfate, iron (III)). Based on understanding gained from this model, a simplified model was developed for calculating a preliminary design estimate of the bicarbonate addition required to control the pH for user-specified operating conditions.

  14. Enhancing area of review capabilities: Implementing a variance program

    SciTech Connect

    De Leon, F.

    1995-12-01

    The Railroad Commission of Texas (RRC) has regulated oil-field injection well operations since issuing its first injection permit in 1938. The Environmental Protection Agency (EPA) granted the RRC primary enforcement responsibility for the Class H Underground Injection Control (UIC) Program in April 1982. At that time, the added level of groundwater protection afforded by an Area of Review (AOR) on previously permitted Class H wells was not deemed necessary or cost effective. A proposed EPA rule change will require AORs to be performed on all pre-primacy Class II wells unless a variance can be justified. A variance methodology has been developed by researchers at the University of Missouri-Rolla in conjunction with the American Petroleum Institute (API). This paper will outline the RRC approach to implementing the AOR variance methodology. The RRC`s UIC program tracks 49,256 pre-primacy wells. Approximately 25,598 of these wells have active permits and will be subject to the proposed AOR requirements. The potential workload of performing AORs or granting variances for this many wells makes the development of a Geographic Information System (GIS) imperative. The RRC has recently completed a digitized map of the entire state and has spotted 890,000 of an estimated 1.2 million wells. Integrating this digital state map into a GIS will allow the RRC to tie its many data systems together. Once in place, this integrated data system will be used to evaluate AOR variances for pre-primacy wells on a field-wide basis. It will also reduce the regulatory cost of permitting by allowing the RRC staff to perform AORs or grant variances for the approximately 3,000 new and amended permit applications requiring AORs each year.

  15. Nonorthogonal Analysis of Variance Programs: An Evaluation.

    ERIC Educational Resources Information Center

    Hosking, James D.; Hamer, Robert M.

    1979-01-01

    Six computer programs for four methods of nonorthogonal analysis of variance are compared for capabilities, accuracy, cost, transportability, quality of documentation, associated computational capabilities, and ease of use: OSIRIS; SAS; SPSS; MANOVA; BMDP2V; and MULTIVARIANCE. (CTM)

  16. 40 CFR 142.41 - Variance request.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and evidence of the best available treatment technology and techniques. (2) Economic and legal factors... water in the case of an excessive rise in the contaminant level for which the variance is requested....

  17. 40 CFR 59.206 - Variances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Consumer Products § 59.206 Variances. (a) Any regulated entity who...

  18. 40 CFR 59.206 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Consumer Products § 59.206 Variances. (a) Any regulated entity who...

  19. 7 CFR 205.290 - Temporary variances.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) ORGANIC FOODS PRODUCTION ACT... notify each production or handling operation it certifies to which the temporary variance applies....

  20. Reducing variance in batch partitioning measurements

    SciTech Connect

    Mariner, Paul E.

    2010-08-11

    The partitioning experiment is commonly performed with little or no attention to reducing measurement variance. Batch test procedures such as those used to measure K{sub d} values (e.g., ASTM D 4646 and EPA402 -R-99-004A) do not explain how to evaluate measurement uncertainty nor how to minimize measurement variance. In fact, ASTM D 4646 prescribes a sorbent:water ratio that prevents variance minimization. Consequently, the variance of a set of partitioning measurements can be extreme and even absurd. Such data sets, which are commonplace, hamper probabilistic modeling efforts. An error-savvy design requires adjustment of the solution:sorbent ratio so that approximately half of the sorbate partitions to the sorbent. Results of Monte Carlo simulations indicate that this simple step can markedly improve the precision and statistical characterization of partitioning uncertainty.

  1. 13 CFR 307.22 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Variances. 307.22 Section 307.22 Business Credit and Assistance ECONOMIC DEVELOPMENT ADMINISTRATION, DEPARTMENT OF COMMERCE ECONOMIC... Federal, State and local law....

  2. 40 CFR 59.206 - Variances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Consumer Products § 59.206 Variances. (a) Any regulated entity who...

  3. 40 CFR 59.206 - Variances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Consumer Products § 59.206 Variances. (a) Any regulated entity who...

  4. 40 CFR 59.206 - Variances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS National Volatile Organic Compound Emission Standards for Consumer Products § 59.206 Variances. (a) Any regulated entity who...

  5. 40 CFR 142.60 - Variances from the maximum contaminant level for total trihalomethanes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... result in a marginal reduction in TTHM for the system. If, upon application by a system for a variance... determination as to the availability and effectiveness of such treatment methods shall be based upon studies by... economically reasonable, and that the TTHM reductions obtained will be commensurate with the costs...

  6. Variational bayesian method of estimating variance components.

    PubMed

    Arakawa, Aisaku; Taniguchi, Masaaki; Hayashi, Takeshi; Mikawa, Satoshi

    2016-07-01

    We developed a Bayesian analysis approach by using a variational inference method, a so-called variational Bayesian method, to determine the posterior distributions of variance components. This variational Bayesian method and an alternative Bayesian method using Gibbs sampling were compared in estimating genetic and residual variance components from both simulated data and publically available real pig data. In the simulated data set, we observed strong bias toward overestimation of genetic variance for the variational Bayesian method in the case of low heritability and low population size, and less bias was detected with larger population sizes in both methods examined. The differences in the estimates of variance components between the variational Bayesian and the Gibbs sampling were not found in the real pig data. However, the posterior distributions of the variance components obtained with the variational Bayesian method had shorter tails than those obtained with the Gibbs sampling. Consequently, the posterior standard deviations of the genetic and residual variances of the variational Bayesian method were lower than those of the method using Gibbs sampling. The computing time required was much shorter with the variational Bayesian method than with the method using Gibbs sampling.

  7. Simultaneous BVI noise and vibration reduction in rotorcraft using actively-controlled flaps and including performance considerations

    NASA Astrophysics Data System (ADS)

    Patt, Daniel A.

    This work presents the development and application of an active control approach for reduction of both vibration and noise induced by helicopter rotor blade vortex interaction (BVI). Control is implemented through single or dual actively controlled flaps (ACFs) on each blade. Low-speed helicopter flight is prone to severe BVI, resulting in elevated vibration and noise levels. Existing research has suggested that when some form of active control is used to reduce vibration, noise will increase and vice versa. The present research achieves simultaneous reduction of noise and vibration, and also investigates the physical sources of the observed reduction. The initial portion of this work focused on developing a tool for simulating helicopter noise and vibrations in the BVI flight regime. A method for predicting compressible unsteady blade surface pressure distribution on rotor blades was developed and combined with an enhanced free-wake model and an acoustic prediction tool with provisions for blade flexibility. These elements were incorporated within an aeroelastic analysis featuring fully coupled flap-lag-torsional blade dynamics. Subsequently, control algorithms were developed that were effective for reducing noise and vibration even in the nonlinear BVI flight regime; saturation limits were incorporated constraining flap deflections to specified limits. The resulting simulation was also validated with a wide range of experimental data, achieving excellent correlation. Finally, a number of active control studies were performed. Multi-component vibration reductions of 40--80% could be achieved, while incurring a small noise penalty. Noise was reduced using an onboard feedback microphone; reductions of 4--10 dB on the advancing side were observed on a plane beneath the rotor when using dual flaps. Finally, simultaneous noise and vibration reduction was studied. A reduction of about 5 dB in noise on the advancing side combined with a 60% reduction in vibration was

  8. Biostimulation of Iron Reduction and Uranium Immobilization: Microbial and Mineralogical Controls

    SciTech Connect

    Joel E. Kostka

    2008-02-06

    This project represented a joint effort between Florida State University (FSU), Rutgers University (RU), and the University of Illinois (U of I). FSU served as the lead institution and Dr. J.E. Kostka was responsible for project coordination, integration, and deliverables. This project was designed to elucidate the microbial ecology and geochemistry of metal reduction in subsurface environments at the U.S. DOE-NABIR Field Research Center at Oak Ridge, Tennessee (ORFRC). Our objectives were to: 1) characterize the dominant iron minerals and related geochemical parameters likely to limit U(VI) speciation, 2) directly quantify reaction rates and pathways of microbial respiration (terminal-electron-accepting) processes which control subsurface sediment chemistry, and 3) identify and enumerate the organisms mediating U(VI) transformation. A total of 31 publications and 47 seminars or meeting presentations were completed under this project. One M.S. thesis (by Nadia North) and a Ph.D. dissertation (by Lainie Petrie-Edwards) were completed at FSU during fall of 2003 and spring of 2005, respectively. Ph.D. students, Denise Akob and Thomas Gihring have continued the student involvement in this research since fall of 2004. All of the above FSU graduate students were heavily involved in the research, as evidenced by their regular attendance at PI meetings and ORFRC workshops.

  9. Rotor blade-vortex interaction noise reduction and vibration using higher harmonic control

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Booth, Earl R., Jr.

    1990-01-01

    The use of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) noise is examined by means of a rotor acoustic test. A dynamically scaled, four-bladed, articulated rotor model was tested in a heavy gas (Freon-12) medium. Acoustic and vibration measurements were made for a large range of matched flight conditions where prescribed (open loop) HHC pitch schedules were superimposed on the normal (baseline) collective and cyclic trim pitch. A novel sound power measurement technique was developed to take advantage of the reverberance in the hard walled tunnel. Quantitative sound power results are presented for a 4/rev (4P) collective pitch HHC. By comparing the results using 4P HHC to corresponding baseline (no HHC) conditions, significant midfrequency noise reductions of 5-6 dB are found for low-speed descent conditions where BVI is most intense. For other flight conditions, noise is found to increase with the use of HHC. LF loading noise, as well as fixed and rotating frame vibration levels, show increased levels.

  10. The next generation of automobile emissions reduction: Innovative control of off-cycle emissions

    SciTech Connect

    Potter, T F; Lyons, C E

    1995-03-01

    Innovative heat management technologies can reduce emissions from cars by an order of magnitude. Substantial reductions would be realized during cold starts and in evaporative emissions. Such improvements result from a new class of variable-conductance steel vacuum insulations that insulate during one time period and take advantage of beneficial thermal conditions during another. Around a catalytic converter, for example, such control allows heat from one driving cycle to catalyze engine-out emissions occurring at the beginning of the next cycle. As with other more efficient uses of heat in automobiles, reduced complexity and cost are likely compared to supplemental catalyst heating systems. In a similar way, thermal cycling of fuel and the resulting vapor release can be reduced or avoided. Urban air quality could be greatly improved by the wide availability of vehicles using these technologies early in the next century. This paper presents analyses and prototype data supporting the design, operation, and rapid market penetration of internal combustion engine vehicles with significantly lower emissions based on such improved thermal management. Potential implications for fleet emissions are discussed.

  11. Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes.

    PubMed

    Papadas, Ioannis T; Fountoulaki, Stella; Lykakis, Ioannis N; Armatas, Gerasimos S

    2016-03-18

    Iron(III) oxide is a low-cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe2O3 with high surface area-to-volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4-5 nm γ-Fe2O3 nanoparticles by a polymer-assisted aggregating self-assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open-pore structure with high surface area (up to 167 m(2)g(-1)) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ-Fe2O3 to α-Fe2O3 and to Fe3O4 under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large-scale synthesis. PMID:26880681

  12. Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes.

    PubMed

    Papadas, Ioannis T; Fountoulaki, Stella; Lykakis, Ioannis N; Armatas, Gerasimos S

    2016-03-18

    Iron(III) oxide is a low-cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe2O3 with high surface area-to-volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4-5 nm γ-Fe2O3 nanoparticles by a polymer-assisted aggregating self-assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open-pore structure with high surface area (up to 167 m(2)g(-1)) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ-Fe2O3 to α-Fe2O3 and to Fe3O4 under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large-scale synthesis.

  13. Harmonic reduction of Direct Torque Control of six-phase induction motor.

    PubMed

    Taheri, A

    2016-07-01

    In this paper, a new switching method in Direct Torque Control (DTC) of a six-phase induction machine for reduction of current harmonics is introduced. Selecting a suitable vector in each sampling period is an ordinal method in the ST-DTC drive of a six-phase induction machine. The six-phase induction machine has 64 voltage vectors and divided further into four groups. In the proposed DTC method, the suitable voltage vectors are selected from two vector groups. By a suitable selection of two vectors in each sampling period, the harmonic amplitude is decreased more, in and various comparison to that of the ST-DTC drive. The harmonics loss is greater reduced, while the electromechanical energy is decreased with switching loss showing a little increase. Spectrum analysis of the phase current in the standard and new switching table DTC of the six-phase induction machine and determination for the amplitude of each harmonics is proposed in this paper. The proposed method has a less sampling time in comparison to the ordinary method. The Harmonic analyses of the current in the low and high speed shows the performance of the presented method. The simplicity of the proposed method and its implementation without any extra hardware is other advantages of the proposed method. The simulation and experimental results show the preference of the proposed method.

  14. Porosity effect on supercritical airfoil drag reduction by shock wave/boundary layer control

    NASA Technical Reports Server (NTRS)

    Nagamatsu, H. T.; Orozco, R. D.; Ling, D. C.

    1984-01-01

    An investigation of the passive shock wave/boundary layer control for reducing the drag of 14 percent-thick supercritical airfoil was conducted in the 3 in. x 15.4 in. RPI Transonic Wind Tunnel at transonic Mach numbers. Various porous surfaces with a cavity beneath it was positioned on the area of the airfoil, mounted on the test section bottom wall, where the shock wave occurs. The static pressure distributions over the airfoil, the wake impact pressure survey for determining the profile drag and the Schlieren photographs for porous surfaces are presented and compared with the results for solid surface airfoil. With a uniform porosity surface the normal shock wave for solid surface was changed to a lambda shock wave, and the wake impact pressure data indicated an appreciable drag reduction at transonic Mach numbers. For a free stream Mach number of 0.81 the profile drag coefficient for the airfoil top surface with uniform porosity was 46 percent lower than for the solid surface airfoil.

  15. Investigation to optimize the passive shock wave/boundary layer control for supercritical airfoil drag reduction

    NASA Technical Reports Server (NTRS)

    Nagamatsu, H. T.; Dyer, R.

    1984-01-01

    The passive shock wave/boundary layer control for reducing the drag of 14%-thick supercritical airfoil was investigated in the 3 in. x 15.4 in. RPI Transonic Wind Tunnel with and without the top wall insert at transonic Mach numbers. Top wall insert was installed to increase the flow Mach number to 0.90 with the model mounted on the test section bottom wall. Various porous surfaces with a cavity underneath were positioned on the area of the airfoil where the shock wave occurs. The higher pressure behind the shock wave circulates flow through the cavity to the lower pressure ahead of the shock wave. The effects from this circulation prevent boundary layer separation and enthropy increase hrough the shock wave. The static pressure distributions over the airfoil, the wake impact pressure survey for determining the profile drag and the Schlieren photographs for porous surfaces are presented and compared with the results for solid surface airfoil. With a 2.8% uniform porosity the normal shock wave for the solid surface was changed to a lambda shock wave, and the wake impact pressure data indicate a drag coefficient reduction as much as 45% lower than for the solid surface airfoil at high transonic Mach numbers.

  16. Mortality reduction following the air pollution control measures during the 2010 Asian Games

    NASA Astrophysics Data System (ADS)

    Lin, Hualiang; Zhang, Yonghui; Liu, Tao; Xiao, Jianpeng; Xu, Yanjun; Xu, Xiaojun; Qian, Zhenmin; Tong, Shilu; Luo, Yuan; Zeng, Weilin; Ma, Wenjun

    2014-07-01

    Though increased particulate air pollution has been consistently associated with elevated mortality, evidence regarding whether diminished particulate air pollution would lead to mortality reduction is limited. Citywide air pollution mitigation program during the 2010 Asian Games in Guangzhou, China, provided such an opportunity. Daily mortality from non-accidental, cardiovascular and respiratory diseases was compared for 51 intervention days (November 1-December 21) in 2010 with the same calendar date of baseline years (2006-2009 and 2011). Relative risk (RR) and 95% confidence interval (95% CI) were estimated using a time series Poisson model, adjusting for day of week, public holidays, daily mean temperature and relative humidity. Daily PM10 (particle with aerodynamic diameter less than 10 μm) decreased from 88.64 μg/m3 during the baseline period to 80.61 μg/m3 during the Asian Games period. Other measured air pollutants and weather variables did not differ substantially. Daily mortality from non-accidental, cardiovascular and respiratory diseases decreased from 32, 11 and 6 during the baseline period to 25, 8 and 5 during the Games period, the corresponding RR for the Games period compared with the baseline period was 0.79 (95% CI: 0.73-0.86), 0.77 (95% CI: 0.66-0.89) and 0.68 (95% CI: 0.57-0.80), respectively. No significant decreases were observed in other months of 2010 in Guangzhou and intervention period in two control cities. This finding supports the efforts to reduce air pollution and improve public health through transportation restriction and industrial emission control.

  17. Nox control for high nitric oxide concentration flows through combustion-driven reduction

    DOEpatents

    Yeh, James T.; Ekmann, James M.; Pennline, Henry W.; Drummond, Charles J.

    1989-01-01

    An improved method for removing nitrogen oxides from concentrated waste gas streams, in which nitrogen oxides are ignited with a carbonaceous material in the presence of substoichiometric quantities of a primary oxidant, such as air. Additionally, reductants may be ignited along with the nitrogen oxides, carbonaceous material and primary oxidant to achieve greater reduction of nitrogen oxides. A scrubber and regeneration system may also be included to generate a concentrated stream of nitrogen oxides from flue gases for reduction using this method.

  18. Biostimulation of Iron Reduction and Uranium Immobilization: Microbial and Mineralogical Controls

    SciTech Connect

    Joel E. Kostka; Lainie Petrie; Nadia North; David L. Balkwill; Joseph W. Stucki; Lee Kerkhof

    2004-03-17

    The overall objective of our project is to understand the microbial and geochemical mechanisms controlling the reduction and immobilization of U(VI) during biostimulation in subsurface sediments of the Field Research Center (FRC) which are cocontaminated with uranium and nitrate. The focus will be on activity of microbial populations (metal- and nitrate-reducing bacteria) and iron minerals which are likely to make strong contributions to the fate of uranium during in situ bioremediation. The project will: (1) quantify the relationships between active members of the microbial communities, iron mineralogy, and nitrogen transformations in the field and in laboratory incubations under a variety of biostimulation conditions, (2) purify and physiologically characterize new model metal-reducing bacteria isolated from moderately acidophilic FRC subsurface sediments, and (3) elucidate the biotic and abiotic mechanisms by which FRC aluminosilicate clay minerals are reduced and dissolved under environmental conditions resembling those during biostimulation. Active microbial communities will be assessed using quantitative molecular techniques along with geochemical measurements to determine the different terminal-electron-accepting pathways. Iron minerals will be characterized using a suite of physical, spectroscopic, and wet chemical methods. Monitoring the activity and composition of the denitrifier community in parallel with denitrification intermediates during nitrate removal will provide a better understanding of the indirect effects of nitrate reduction on uranium speciation. Through quantification of the activity of specific microbial populations and an in-depth characterization of Fe minerals likely to catalyze U sorption/precipitation, we will provide important inputs for reaction-based biogeochemical models which will provide the basis for development of in situ U bioremediation strategies. In collaboration with Jack Istok and Lee Krumholz, we have begun to study the

  19. Reduction of Urogenital Schistosomiasis with an Integrated Control Project in Sudan

    PubMed Central

    Lee, Young-Ha; Jeong, Hoo Gn; Kong, Woo Hyun; Lee, Soon-Hyung; Cho, Han-Ik; Nam, Hae-Sung; Ismail, Hassan Ahmed Hassan Ahmed; Alla, Gibril Nouman Abd; Oh, Chung Hyeon; Hong, Sung-Tae

    2015-01-01

    Purpose Schistosomiasis remains a major public health concern in Sudan, particularly Schistosoma haematobium infection. This study presents the disease-reduction outcomes of an integrated control program for schistosomiasis in Al Jabalain locality of White Nile State, Sudan from 2009 through 2011. Methods The total population of the project sites was 482,902, and the major target group for intervention among them was 78,615 primary school students. For the cross-sectional study of the prevalence, urine and stool specimens were examined using the urine sedimentation method and the Kato cellophane thick smear method, respectively. To assess the impacts of health education for students and a drinking water supply facility at Al Hidaib village, questionnaire survey was done. Results The overall prevalence for S. haematobium and S. mansoni at baseline was 28.5% and 0.4%, respectively. At follow-up survey after 6–9 months post-treatment, the prevalence of S. haematobium infection was reduced to 13.5% (95% CI = 0.331–0.462). A higher reduction in prevalence was observed among girls, those with moderately infected status (around 20%), and residents in rural areas, than among boys, those with high prevalence (>40%), and residents in urban areas. After health education, increased awareness about schistosomiasis was checked by questionnaire survey. Also, a drinking water facility was constructed at Al Hidaib village, where infection rate was reduced more compared to that in a neighboring village within the same unit. However, we found no significant change in the prevalence of S. mansoni infection between baseline and follow-up survey (95% CI = 0.933–6.891). Conclusions At the end of the project, the prevalence of S. haematobium infection was reduced by more than 50% in comparison with the baseline rate. Approximately 200,000 subjects had received either praziquantel therapy, health education, or supply of clean water. To consolidate the achievements of this

  20. Robust Means Modeling: An Alternative for Hypothesis Testing of Independent Means under Variance Heterogeneity and Nonnormality

    ERIC Educational Resources Information Center

    Fan, Weihua; Hancock, Gregory R.

    2012-01-01

    This study proposes robust means modeling (RMM) approaches for hypothesis testing of mean differences for between-subjects designs in order to control the biasing effects of nonnormality and variance inequality. Drawing from structural equation modeling (SEM), the RMM approaches make no assumption of variance homogeneity and employ robust…

  1. Reduced Variance for Material Sources in Implicit Monte Carlo

    SciTech Connect

    Urbatsch, Todd J.

    2012-06-25

    Implicit Monte Carlo (IMC), a time-implicit method due to Fleck and Cummings, is used for simulating supernovae and inertial confinement fusion (ICF) systems where x-rays tightly and nonlinearly interact with hot material. The IMC algorithm represents absorption and emission within a timestep as an effective scatter. Similarly, the IMC time-implicitness splits off a portion of a material source directly into the radiation field. We have found that some of our variance reduction and particle management schemes will allow large variances in the presence of small, but important, material sources, as in the case of ICF hot electron preheat sources. We propose a modification of our implementation of the IMC method in the Jayenne IMC Project. Instead of battling the sampling issues associated with a small source, we bypass the IMC implicitness altogether and simply deterministically update the material state with the material source if the temperature of the spatial cell is below a user-specified cutoff. We describe the modified method and present results on a test problem that show the elimination of variance for small sources.

  2. 46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Reduction Act. 535.991 Section 535.991 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE OCEAN COMMON CARRIER AND MARINE TERMINAL OPERATOR AGREEMENTS SUBJECT TO THE... section 3507(a)(3) of the Paperwork Reduction Act, which requires that agencies display a current...

  3. 46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Reduction Act. 535.991 Section 535.991 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE OCEAN COMMON CARRIER AND MARINE TERMINAL OPERATOR AGREEMENTS SUBJECT TO THE... section 3507(a)(3) of the Paperwork Reduction Act, which requires that agencies display a current...

  4. 46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Reduction Act. 535.991 Section 535.991 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE OCEAN COMMON CARRIER AND MARINE TERMINAL OPERATOR AGREEMENTS SUBJECT TO THE... section 3507(a)(3) of the Paperwork Reduction Act, which requires that agencies display a current...

  5. 46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Reduction Act. 535.991 Section 535.991 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE OCEAN COMMON CARRIER AND MARINE TERMINAL OPERATOR AGREEMENTS SUBJECT TO THE... section 3507(a)(3) of the Paperwork Reduction Act, which requires that agencies display a current...

  6. 46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Reduction Act. 535.991 Section 535.991 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE OCEAN COMMON CARRIER AND MARINE TERMINAL OPERATOR AGREEMENTS SUBJECT TO THE... section 3507(a)(3) of the Paperwork Reduction Act, which requires that agencies display a current...

  7. Adaptive Model Predictive Control of Diesel Engine Selective Catalytic Reduction (SCR) Systems

    ERIC Educational Resources Information Center

    McKinley, Thomas L.

    2009-01-01

    Selective catalytic reduction or SCR is coming into worldwide use for diesel engine emissions reduction for on- and off-highway vehicles. These applications are characterized by broad operating range as well as rapid and unpredictable changes in operating conditions. Significant nonlinearity, input and output constraints, and stringent performance…

  8. Variance estimation for nucleotide substitution models.

    PubMed

    Chen, Weishan; Wang, Hsiuying

    2015-09-01

    The current variance estimators for most evolutionary models were derived when a nucleotide substitution number estimator was approximated with a simple first order Taylor expansion. In this study, we derive three variance estimators for the F81, F84, HKY85 and TN93 nucleotide substitution models, respectively. They are obtained using the second order Taylor expansion of the substitution number estimator, the first order Taylor expansion of a squared deviation and the second order Taylor expansion of a squared deviation, respectively. These variance estimators are compared with the existing variance estimator in terms of a simulation study. It shows that the variance estimator, which is derived using the second order Taylor expansion of a squared deviation, is more accurate than the other three estimators. In addition, we also compare these estimators with an estimator derived by the bootstrap method. The simulation shows that the performance of this bootstrap estimator is similar to the estimator derived by the second order Taylor expansion of a squared deviation. Since the latter one has an explicit form, it is more efficient than the bootstrap estimator.

  9. A noise variance estimation approach for CT

    NASA Astrophysics Data System (ADS)

    Shen, Le; Jin, Xin; Xing, Yuxiang

    2012-10-01

    The Poisson-like noise model has been widely used for noise suppression and image reconstruction in low dose computed tomography. Various noise estimation and suppression approaches have been developed and studied to enhance the image quality. Among them, the recently proposed generalized Anscombe transform (GAT) has been utilized to stabilize the variance of Poisson-Gaussian noise. In this paper, we present a variance estimation approach using GAT. After the transform, the projection data is denoised conventionally with an assumption that the noise variance is uniformly equals to 1. The difference of the original and the denoised projection is treated as pure noise and the global variance σ2 can be estimated from the residual difference. Thus, the final denoising step with the estimated σ2 is performed. The proposed approach is verified on a cone-beam CT system and demonstrated to obtain a more accurate estimation of the actual parameter. We also examine FBP algorithm with the two-step noise suppression in the projection domain using the estimated noise variance. Reconstruction results with simulated and practical projection data suggest that the presented approach could be effective in practical imaging applications.

  10. A study on sensory properties of sodium reduction and replacement in Asian food using difference-from - control test.

    PubMed

    Leong, Jasmine; Kasamatsu, Chinatsu; Ong, Evelyn; Hoi, Jia Tse; Loong, Mann Na

    2016-05-01

    This study examined the effects of sodium reduction and flavor enhancers on the sensory profile of two types of hawker foods commonly consumed in Singapore, namely chicken rice and mee soto broth. The 'difference-from-control' test was the method adopted in this study involving 24-29 trained panelists. Combinations included blind control, two levels of sodium reduction, and two levels of flavor enhancers in sodium-reduced recipes. In the sodium-reduced recipes, two levels of NaCl, 0.48% and 0.55%, for chicken rice, and 0.76% and 0.86% for mee soto (equivalent to 31% and 22% reduction in NaCl), were used. Monosodium glutamate (MSG) or Ajiplus (®) (a blend of MSG and nucleotides) at 0.20% and 0.40% were added to the recipes comprising a reduction of 40% in NaCl (equivalent to 31% and 22% reduction in sodium, respectively) compared with the control. It was found that the inclusion of MSG or Ajiplus (®) in 40% NaCl-reduced recipe resulted in a significant increase in perception of umami taste (P < 0.05) when compared to the control. By adding flavor enhancers into the 40%-reduced salt chicken rice recipes, the perception of saltiness was significantly increased when compared to 22% and 31% sodium reduced recipes. Similarly for mee soto broth, there was a significant increase in perception of chicken flavor, umami taste, mouthfeel sensation, and sweet taste (P < 0.05) with a decrease in the perception of sour and bitter taste when compared to control. By adding 0.40% MSG into the 40%-reduced salt recipes, the perception of saltiness was maintained when compared with control. PMID:27247776

  11. Size-controlled large-diameter and few-walled carbon nanotube catalysts for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Xianliang; Li, Qing; Pan, Hengyu; Lin, Ye; Ke, Yujie; Sheng, Haiyang; Swihart, Mark T.; Wu, Gang

    2015-11-01

    We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic activity was observed, in both alkaline media and more demanding acidic media. The Fe-derived N-CNTs exhibited the highest BET (~870 m2 g-1) and electrochemically accessible (~450 m2 g-1) surface areas and, more importantly, the highest concentration of nitrogen incorporated into the carbon planes. Thus, in addition to the intrinsic high activity of Fe-derived catalysts, the high surface area and nitrogen doping contribute to high ORR activity. This work, for the first time, demonstrates size-controlled synthesis of large-diameter N-doped carbon tube electrocatalysts by varying the metal used in N-CNT generation. Electrocatalytic activity of the Fe-derived catalyst is already the best among studied metals, due to the high intrinsic activity of possible Fe-N coordination. This work further provides a promising route to advanced Fe-N-C nonprecious metal catalysts by generating favorable morphology with more active sites and improved mass transfer.We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic

  12. Benthic sulfate reduction along the Chesapeake Bay central channel. II. Temporal controls

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Boynton, W.R.; Capone, D.G.

    2003-01-01

    Seasonal and interannual controls of benthic sulfate reduction (SR) were examined at 3 sites (upper [UB], mid- [MB] and lower [LB] bay) along the Chesapeake Bay central channel, from early spring through fall, for 6 yr (1989 to 1994). The combined influences of temperature, sulfate, organic loading and bioturbation affected seasonal SR rates differently in the 3 regions. Consistently low SR rates at UB resulted from low overlying-water sulfate concentrations and the dominance of refractory organic terrestrial material. Combined seasonal variation in temperature and sulfate accounted for 50% of the annual variability in 0 to 2 cm depth interval SR rates, while sediment organic content had no significant seasonal influence. In contrast, MB and LB sites had high rates of SR fostered by high levels of overlying water SO42- and organic input dominated by labile phytoplankton detritus. New organic loading (measured as chl a) stimulated 0 to 2 cm SR during spring at both sites. Combined organic quantity (as particulate C and/or N) and temperature accounted for > 75% of the variability in 0 to 2 cm SR at MB during spring and fall. Molecular diffusion supplied 25 to 45% of the SO 42- needed to fuel 0 to 12 cm depth interval SR at MB, with the balance presumably supplied by S-recycling. Interannual differences in summertime SR rates were linked to the extent of freshwater flow during spring, with high-flow years associated with high SR rates at UB and MB, and low rates at LB. The negative trend between benthic SR and river flow at LB may result from the up-estuary transport of senescing organic matter in bottom water, which increases in the lower reach of the estuary with increasing freshwater inflow.

  13. Reduction of claustrophobia during magnetic resonance imaging: methods and design of the "CLAUSTRO" randomized controlled trial

    PubMed Central

    2011-01-01

    Background Magnetic resonance (MR) imaging has been described as the most important medical innovation in the last 25 years. Over 80 million MR procedures are now performed each year and on average 2.3% (95% confidence interval: 2.0 to 2.5%) of all patients scheduled for MR imaging suffer from claustrophobia. Thus, prevention of MR imaging by claustrophobia is a common problem and approximately 2,000,000 MR procedures worldwide cannot be completed due to this situation. Patients with claustrophobic anxiety are more likely to be frightened and experience a feeling of confinement or being closed in during MR imaging. In these patients, conscious sedation and additional sequences (after sedation) may be necessary to complete the examinations. Further improvements in MR design appear to be essential to alleviate this situation and broaden the applicability of MR imaging. A more open scanner configuration might help reduce claustrophobic reactions while maintaining image quality and diagnostic accuracy. Methods/Design We propose to analyze the rate of claustrophobic reactions, clinical utility, image quality, patient acceptance, and cost-effectiveness of an open MR scanner in a randomized comparison with a recently designed short-bore but closed scanner with 97% noise reduction. The primary aim of this study is thus to determine whether an open MR scanner can reduce claustrophobic reactions, thereby enabling more examinations of claustrophobic patients without incurring the safety issues associated with conscious sedation. In this manuscript we detail the methods and design of the prospective "CLAUSTRO" trial. Discussion This randomized controlled trial will be the first direct comparison of open vertical and closed short-bore MR systems in regards to claustrophobia and image quality as well as diagnostic utility. Trial Registration ClinicalTrials.gov: NCT00715806 PMID:21310075

  14. Benthic sulfate reduction along the Chesapeake Bay central channel. I. Spatial trends and controls

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Capone, D.G.

    1998-01-01

    Factors controlling the spatial distribution of benthic sulfate reduction (SR) were investigated at 3 stations [upper (UB), mid (MB) and lower bay (LB)] along the Chesapeake Bay (eastern USA) central channel from early spring through late fall, 1989 to 1994. Annual rates of 0 to 12 cm depth-integrated SR were 0.96, 9.62 and 6.33 mol S m-2 yr-1 for UB, MB and LB, respectively, as calculated from 35SO42- incubations. SR was carbon limited at UB, LB, and at the sediment surface at MB, and SO42- limited at depth at MB. Temperature explained 33 to 68% of the variability in annual rates, with an apparent influence on SR which increased in the seaward direction in surface sediments. We speculate that the enhanced response of SR to temperature in LB surface sediments was linked to seasonal variations in macrofaunal activity associated with temperature. Estimates of reduced-S burial indicated that only 4 to 8% of sulfur reduced annually was buried as Fe-S minerals at MB and LB, with the remainder presumably being reoxidized. In contrast, >50% of the sulfur reduced annually was buried at UB, due to comparatively low SR rates and the high concentration of reactive iron in the oligohaline region. SR mineralized 18 to 32% of the annual primary production. Our results indicate that organic quality may be more important than the absolute quantity of organic loading in dictating the magnitude of benthic SR rates along an estuarine gradient. Spatial trends in SR reflected the combined influence of deposited organic matter quality and quantity, SO42- availability, the presence or absence of benthic macrofauna, overlying water dissolved O2 conditions, reduced-S reoxidation dynamics, and iron-sulfide mineral formation.

  15. Blade-Mounted Flap Control for BVI Noise Reduction Proof-of-Concept Test

    NASA Technical Reports Server (NTRS)

    Dawson, Seth; Hassan, Ahmed; Straub, Friedrich; Tadghighi, Hormoz

    1995-01-01

    This report describes a wind tunnel test of the McDonnell Douglas Helicopter Systems (MDHS) Active Flap Model Rotor at the NASA Langley 14- by 22-Foot Subsonic Tunnel. The test demonstrated that BVI noise reductions and vibration reductions were possible with the use of an active flap. Aerodynamic results supported the acoustic data trends, showing a reduction in the strength of the tip vortex with the deflection of the flap. Acoustic results showed that the flap deployment, depending on the peak deflection angle and azimuthal shift in its deployment schedule, can produce BVI noise reductions as much as 6 dB on the advancing and retreating sides. The noise reduction was accompanied by an increase in low frequency harmonic noise and high frequency broadband noise. A brief assessment of the effect of the flap on vibration showed that significant reductions were possible. The greatest vibration reductions (as much as 76%) were found in the four per rev pitching moment at the hub. Performance improvement cam results were inconclusive, as the improvements were predicted to be smaller than the resolution of the rotor balance.

  16. Kinetics of U(VI) reduction control kinetics of U(IV) reoxidation

    SciTech Connect

    Senko, J.M.; Minyard, M.L.; Dempsey, B.A.; Roden, E.E.; Yeh, G.-T.; Burgos, W.D.

    2006-04-05

    For the in situ reductive immobilization of U to be an acceptable strategy for the removal of that element from groundwater, the long-term stability of U(IV) must be determined. Rates of biotransformation of Fe species influence the mineralogy of the resulting products (Fredrickson et al., 2003; Senko et al., 2005), and we hypothesize that the rate of U(VI) reduction influences the mineralogy of resultant U(IV) precipitates. We hypothesize that slower rates of U(VI) reduction will yield U(IV) phases that are more resistant to reoxidation, and will therefore be more stable upon cessation of electron donor addition. U(IV) phases formed by relatively slow reduction may be more crystalline or larger in comparison to their relatively rapidly-formed counterparts (Figure 1), thus limiting the reactivity of slowly-formed U(IV) phases toward various oxidants. The physical location of U(IV) precipitates relative to bacterial cells may also limit the reactivity of biogenic U(IV) phases. In this situation, we expect that precipitation of U(IV) within the bacterial cell may protect U(IV) from reoxidation by limiting physical contact between U(IV) and oxidants (Figure 1). We assessed the effect of U(VI) reduction rate on the subsequent reoxidation of biogenic U(IV) and are currently conducting column scale studies to determine whether U(VI) reduction rate can be manipulated by varying the electron donor concentration used to stimulate U(VI) reduction.

  17. Watershed Controls on the Proper Scale of Economic Markets for Pollution Reduction

    NASA Astrophysics Data System (ADS)

    Rigby, J.; Doyle, M. W.; Yates, A.

    2010-12-01

    Markets for tradable discharge permits (TDPs) are an increasingly popular policy instrument for obtaining cost-effective nutrient reduction targets across watersheds. Such markets are also an emerging, dynamic coupling between economic institutions and stream hydrology/biogeochemistry as trading markets become explicit determinants for the spatial distribution of stream nutrient loads. A central problem in any environmental market program is setting the size of the market, as there are distinct trade-offs for large versus small markets. While the overall cost-effectiveness of permit trading increases with the size of the market, the potential for localized and highly damaging nutrient concentrations, or “hotspots”, also increases. Smaller market size reduces the potential for hot spots by dispersing the location of trades, but this may increase the net costs of water quality compliance significantly through both the restriction of possible trading partners and price manipulation by market participants. This project couples a microeconomic model for TDPs (based on possible configurations of mutually exclusive trading zones within the basin) with a semi-distributed water quality model to examine watershed controls on the configuration and scale of such markets. Our results show a wide variation in total annual cost of pollution abatement based on choice of market design -- often with large differences in cost between very similar configurations. This framework is also applied to a 10-member trading program among wastewater treatment plants in the Neuse River, NC, in order to assess (1) the optimum market design for the Upper Neuse basin and (2) how these costs compare with expected costs under alternative market structures (e.g., trading ratio system) and (3) the cost improvements over traditional command-and-control regulatory frameworks. We find that the optimal zone configuration is almost always a lower cost option when compared to a trading ratio scheme and

  18. ASSESSMENT OF A WIND TURBINE INTELLIGENT CONTROLLER FOR ENHANCED ENERGY PRODUCTION AND POLLUTION REDUCTION

    EPA Science Inventory

    This study assessed the enhanced energy production which is possible when variable-speed wind turbines are electronically controlled by an intelligent controller for efficiency optimization and performance improvement. The control system consists of three fuzzy- logic controllers...

  19. Integrating Variances into an Analytical Database

    NASA Technical Reports Server (NTRS)

    Sanchez, Carlos

    2010-01-01

    For this project, I enrolled in numerous SATERN courses that taught the basics of database programming. These include: Basic Access 2007 Forms, Introduction to Database Systems, Overview of Database Design, and others. My main job was to create an analytical database that can handle many stored forms and make it easy to interpret and organize. Additionally, I helped improve an existing database and populate it with information. These databases were designed to be used with data from Safety Variances and DCR forms. The research consisted of analyzing the database and comparing the data to find out which entries were repeated the most. If an entry happened to be repeated several times in the database, that would mean that the rule or requirement targeted by that variance has been bypassed many times already and so the requirement may not really be needed, but rather should be changed to allow the variance's conditions permanently. This project did not only restrict itself to the design and development of the database system, but also worked on exporting the data from the database to a different format (e.g. Excel or Word) so it could be analyzed in a simpler fashion. Thanks to the change in format, the data was organized in a spreadsheet that made it possible to sort the data by categories or types and helped speed up searches. Once my work with the database was done, the records of variances could be arranged so that they were displayed in numerical order, or one could search for a specific document targeted by the variances and restrict the search to only include variances that modified a specific requirement. A great part that contributed to my learning was SATERN, NASA's resource for education. Thanks to the SATERN online courses I took over the summer, I was able to learn many new things about computers and databases and also go more in depth into topics I already knew about.

  20. Wave propagation analysis using the variance matrix.

    PubMed

    Sharma, Richa; Ivan, J Solomon; Narayanamurthy, C S

    2014-10-01

    The propagation of a coherent laser wave-field through a pseudo-random phase plate is studied using the variance matrix estimated from Shack-Hartmann wavefront sensor data. The uncertainty principle is used as a tool in discriminating the data obtained from the Shack-Hartmann wavefront sensor. Quantities of physical interest such as the twist parameter, and the symplectic eigenvalues, are estimated from the wavefront sensor measurements. A distance measure between two variance matrices is introduced and used to estimate the spatial asymmetry of a wave-field in the experiment. The estimated quantities are then used to compare a distorted wave-field with its undistorted counterpart. PMID:25401243

  1. Analytical design and evaluation of an active control system for helicopter vibration reduction and gust response alleviation

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.; Zwicke, P. E.; Gold, P.; Miao, W.

    1980-01-01

    An analytical study was conducted to define the basic configuration of an active control system for helicopter vibration and gust response alleviation. The study culminated in a control system design which has two separate systems: narrow band loop for vibration reduction and wider band loop for gust response alleviation. The narrow band vibration loop utilizes the standard swashplate control configuration to input controller for the vibration loop is based on adaptive optimal control theory and is designed to adapt to any flight condition including maneuvers and transients. The prime characteristics of the vibration control system is its real time capability. The gust alleviation control system studied consists of optimal sampled data feedback gains together with an optimal one-step-ahead prediction. The prediction permits the estimation of the gust disturbance which can then be used to minimize the gust effects on the helicopter.

  2. Model reduction for the dynamics and control of large structural systems via neutral network processing direct numerical optimization

    NASA Technical Reports Server (NTRS)

    Becus, Georges A.; Chan, Alistair K.

    1993-01-01

    Three neural network processing approaches in a direct numerical optimization model reduction scheme are proposed and investigated. Large structural systems, such as large space structures, offer new challenges to both structural dynamicists and control engineers. One such challenge is that of dimensionality. Indeed these distributed parameter systems can be modeled either by infinite dimensional mathematical models (typically partial differential equations) or by high dimensional discrete models (typically finite element models) often exhibiting thousands of vibrational modes usually closely spaced and with little, if any, damping. Clearly, some form of model reduction is in order, especially for the control engineer who can actively control but a few of the modes using system identification based on a limited number of sensors. Inasmuch as the amount of 'control spillover' (in which the control inputs excite the neglected dynamics) and/or 'observation spillover' (where neglected dynamics affect system identification) is to a large extent determined by the choice of particular reduced model (RM), the way in which this model reduction is carried out is often critical.

  3. Sediment studies of the biological factors controlling the reduction of U(VI).

    SciTech Connect

    Lovley, derek, R.

    2004-08-04

    Studies were conducted primarily with sediments, both in laboratory incubations and in a field experiment, with supporting studies with pure cultures. To our knowledge the sediment studies were the first on microbial U(VI) reduction in actual uranium-contaminated subsurface sediments, under conditions that mimic those found in situ. Important findings included: (1) U(VI) reduction is a biotic process in subsurface sediments. (2) U(VI) reduction can be stimulated most effectively with the addition of acetate. Although it had been speculated that microbial U(VI) reduction might be capable of this type of environmental remediation ever since the discovery of microbial U(VI) reduction, this had not been previously demonstrated under environmentally relevant conditions. (3) U(VI) is reduced concurrently with Fe(III) and prior to sulfate reduction. U(VI) and Fe(III) reduction proceeded concurrently, accompanied by a dramatic enrichment in organisms in the Geobacteraceae. Sulfate-reducing microorganisms do not appear to be important components of the microbial community reducing U(VI) in these subsurface sediments. (4) Nitrate has important influences on U(VI) reduction. Nitrate inhibits the reduction of metals until nitrate is depleted. Fe(III)-reducing microorganisms such as Geobacter metallireducens and Desulfitobacterium species can oxidize Fe(II) with the reduction of nitrate which is an important consideration because our previous studies have demonstrated that freshly precipitated Fe(III) oxides can reoxidize U(IV) to U(VI). The discovery that G. metallireducens can ''run backwards'' and oxidize U(IV) when nitrate is present reveals another mechanism preventing precipitation of U(IV) in the presence of nitrate as well as potential novel strategy for removing uranium from the subsurface after a site has been remediated. (5) Importance of understanding Fe(III) forms available for microbial reduction. Fe(III) is orders of magnitude more abundant than U(VI) as an

  4. A new reduction-based LQ control for dynamic systems with a slowly time-varying delay

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Haraguchi, Masakazu; Hu, Haiyan

    2009-08-01

    Time delays in the feedback control often deteriorate the control performance or even cause the instability of a dynamic system. This paper presents a control strategy for the dynamic system with a constant or a slowly time-varying input delay based on a transformation, which simplifies the time-delay system into a delay-free one. Firstly, the relation is discussed for two existing reduction-based linear quadratic controls. One is continuous and the other is discrete. By extending the relation, a new reduction-based control is then developed with a numerical algorithm presented for practical control implementation. The controller suggested by the proposed method has such a promising property that it can be used for the cases of different values of an input time delay without redesign of controller. This property provides the potential for stabilizing the dynamic system with a time-varying input delay. Consequently, the application of the proposed method to the dynamic system with a slowly time-varying delay is discussed. Finally, numerical simulations are given to show the efficacy and the applicability of the method.

  5. 10 CFR 1022.16 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... such an action) DOE shall document the emergency actions in accordance with NEPA procedures at 10 CFR... ENERGY (GENERAL PROVISIONS) COMPLIANCE WITH FLOODPLAIN AND WETLAND ENVIRONMENTAL REVIEW REQUIREMENTS Procedures for Floodplain and Wetland Reviews § 1022.16 Variances. (a) Emergency actions. DOE may...

  6. 10 CFR 1022.16 - Variances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... such an action) DOE shall document the emergency actions in accordance with NEPA procedures at 10 CFR... ENERGY (GENERAL PROVISIONS) COMPLIANCE WITH FLOODPLAIN AND WETLAND ENVIRONMENTAL REVIEW REQUIREMENTS Procedures for Floodplain and Wetland Reviews § 1022.16 Variances. (a) Emergency actions. DOE may...

  7. 10 CFR 1022.16 - Variances.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... such an action) DOE shall document the emergency actions in accordance with NEPA procedures at 10 CFR... ENERGY (GENERAL PROVISIONS) COMPLIANCE WITH FLOODPLAIN AND WETLAND ENVIRONMENTAL REVIEW REQUIREMENTS Procedures for Floodplain and Wetland Reviews § 1022.16 Variances. (a) Emergency actions. DOE may...

  8. 10 CFR 1022.16 - Variances.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... such an action) DOE shall document the emergency actions in accordance with NEPA procedures at 10 CFR... ENERGY (GENERAL PROVISIONS) COMPLIANCE WITH FLOODPLAIN AND WETLAND ENVIRONMENTAL REVIEW REQUIREMENTS Procedures for Floodplain and Wetland Reviews § 1022.16 Variances. (a) Emergency actions. DOE may...

  9. 10 CFR 1022.16 - Variances.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... such an action) DOE shall document the emergency actions in accordance with NEPA procedures at 10 CFR... ENERGY (GENERAL PROVISIONS) COMPLIANCE WITH FLOODPLAIN AND WETLAND ENVIRONMENTAL REVIEW REQUIREMENTS Procedures for Floodplain and Wetland Reviews § 1022.16 Variances. (a) Emergency actions. DOE may...

  10. Regression Calibration with Heteroscedastic Error Variance

    PubMed Central

    Spiegelman, Donna; Logan, Roger; Grove, Douglas

    2011-01-01

    The problem of covariate measurement error with heteroscedastic measurement error variance is considered. Standard regression calibration assumes that the measurement error has a homoscedastic measurement error variance. An estimator is proposed to correct regression coefficients for covariate measurement error with heteroscedastic variance. Point and interval estimates are derived. Validation data containing the gold standard must be available. This estimator is a closed-form correction of the uncorrected primary regression coefficients, which may be of logistic or Cox proportional hazards model form, and is closely related to the version of regression calibration developed by Rosner et al. (1990). The primary regression model can include multiple covariates measured without error. The use of these estimators is illustrated in two data sets, one taken from occupational epidemiology (the ACE study) and one taken from nutritional epidemiology (the Nurses’ Health Study). In both cases, although there was evidence of moderate heteroscedasticity, there was little difference in estimation or inference using this new procedure compared to standard regression calibration. It is shown theoretically that unless the relative risk is large or measurement error severe, standard regression calibration approximations will typically be adequate, even with moderate heteroscedasticity in the measurement error model variance. In a detailed simulation study, standard regression calibration performed either as well as or better than the new estimator. When the disease is rare and the errors normally distributed, or when measurement error is moderate, standard regression calibration remains the method of choice. PMID:22848187

  11. 18 CFR 1304.408 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Variances. 1304.408 Section 1304.408 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY APPROVAL OF... whether a proposed structure or other regulated activity would adversely impact navigation, flood...

  12. 18 CFR 1304.408 - Variances.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 2 2011-04-01 2011-04-01 false Variances. 1304.408 Section 1304.408 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY APPROVAL OF... whether a proposed structure or other regulated activity would adversely impact navigation, flood...

  13. Understanding gender variance in children and adolescents.

    PubMed

    Simons, Lisa K; Leibowitz, Scott F; Hidalgo, Marco A

    2014-06-01

    Gender variance is an umbrella term used to describe gender identity, expression, or behavior that falls outside of culturally defined norms associated with a specific gender. In recent years, growing media coverage has heightened public awareness about gender variance in childhood and adolescence, and an increasing number of referrals to clinics specializing in care for gender-variant youth have been reported in the United States. Gender-variant expression, behavior, and identity may present in childhood and adolescence in a number of ways, and youth with gender variance have unique health needs. For those experiencing gender dysphoria, or distress encountered by the discordance between biological sex and gender identity, puberty is often an exceptionally challenging time. Pediatric primary care providers may be families' first resource for education and support, and they play a critical role in supporting the health of youth with gender variance by screening for psychosocial problems and health risks, referring for gender-specific mental health and medical care, and providing ongoing advocacy and support. PMID:24972420

  14. Understanding gender variance in children and adolescents.

    PubMed

    Simons, Lisa K; Leibowitz, Scott F; Hidalgo, Marco A

    2014-06-01

    Gender variance is an umbrella term used to describe gender identity, expression, or behavior that falls outside of culturally defined norms associated with a specific gender. In recent years, growing media coverage has heightened public awareness about gender variance in childhood and adolescence, and an increasing number of referrals to clinics specializing in care for gender-variant youth have been reported in the United States. Gender-variant expression, behavior, and identity may present in childhood and adolescence in a number of ways, and youth with gender variance have unique health needs. For those experiencing gender dysphoria, or distress encountered by the discordance between biological sex and gender identity, puberty is often an exceptionally challenging time. Pediatric primary care providers may be families' first resource for education and support, and they play a critical role in supporting the health of youth with gender variance by screening for psychosocial problems and health risks, referring for gender-specific mental health and medical care, and providing ongoing advocacy and support.

  15. Videotape Project in Child Variance. Final Report.

    ERIC Educational Resources Information Center

    Morse, William C.; Smith, Judith M.

    The design, production, dissemination, and evaluation of a series of videotaped training packages designed to enable teachers, parents, and paraprofessionals to interpret child variance in light of personal and alternative perspectives of behavior are discussed. The goal of each package is to highlight unique contributions of different theoretical…

  16. Variance Anisotropy of Solar Wind fluctuations

    NASA Astrophysics Data System (ADS)

    Oughton, S.; Matthaeus, W. H.; Wan, M.; Osman, K.

    2013-12-01

    Solar wind observations at MHD scales indicate that the energy associated with velocity and magnetic field fluctuations transverse to the mean magnetic field is typically much larger than that associated with parallel fluctuations [eg, 1]. This is often referred to as variance anisotropy. Various explanations for it have been suggested, including that the fluctuations are predominantly shear Alfven waves [1] and that turbulent dynamics leads to such states [eg, 2]. Here we investigate the origin and strength of such variance anisotropies, using spectral method simulations of the compressible (polytropic) 3D MHD equations. We report on results from runs with initial conditions that are either (i) broadband turbulence or (ii) fluctuations polarized in the same sense as shear Alfven waves. The dependence of the variance anisotropy on the plasma beta and Mach number is examined [3], along with the timescale for any variance anisotropy to develop. Implications for solar wind fluctuations will be discussed. References: [1] Belcher, J. W. and Davis Jr., L. (1971), J. Geophys. Res., 76, 3534. [2] Matthaeus, W. H., Ghosh, S., Oughton, S. and Roberts, D. A. (1996), J. Geophys. Res., 101, 7619. [3] Smith, C. W., B. J. Vasquez and K. Hamilton (2006), J. Geophys. Res., 111, A09111.

  17. 29 CFR 1920.2 - Variances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) or 6(d) of the Williams-Steiger Occupational Safety and Health Act of 1970 (29 U.S.C. 655). The... under the Williams-Steiger Occupational Safety and Health Act of 1970, and any variance from §§ 1910.13... from the standard under both the Longshoremen's and Harbor Workers' Compensation Act and the...

  18. 7 CFR 205.290 - Temporary variances.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Temporary variances. 205.290 Section 205.290 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) ORGANIC FOODS PRODUCTION...

  19. Number variance for arithmetic hyperbolic surfaces

    NASA Astrophysics Data System (ADS)

    Luo, W.; Sarnak, P.

    1994-03-01

    We prove that the number variance for the spectrum of an arithmetic surface is highly nonrigid in part of the universal range. In fact it is close to having a Poisson behavior. This fact was discovered numerically by Schmit, Bogomolny, Georgeot and Giannoni. It has its origin in the high degeneracy of the length spectrum, first observed by Selberg.

  20. 7 CFR 205.290 - Temporary variances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Temporary variances. 205.290 Section 205.290 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) ORGANIC FOODS PRODUCTION ACT PROVISIONS NATIONAL ORGANIC PROGRAM...

  1. Formative Use of Intuitive Analysis of Variance

    ERIC Educational Resources Information Center

    Trumpower, David L.

    2013-01-01

    Students' informal inferential reasoning (IIR) is often inconsistent with the normative logic underlying formal statistical methods such as Analysis of Variance (ANOVA), even after instruction. In two experiments reported here, student's IIR was assessed using an intuitive ANOVA task at the beginning and end of a statistics course. In…

  2. 20 CFR 654.402 - Variances.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR SPECIAL RESPONSIBILITIES OF THE EMPLOYMENT SERVICE SYSTEM Housing for Agricultural Workers Purpose and Applicability § 654.402 Variances. (a... employment service complaint procedures set forth at §§ 658.421 (i) and (j), 658.422 and 658.423 of...

  3. 78 FR 14122 - Revocation of Permanent Variances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-04

    ... OSHA's scaffolds standards for construction (77 FR 46948). Today's notice revoking the variances takes..., construction, and use of scaffolds (61 FR 46026). In the preamble to the final rule, OSHA stated that it was... for tank scaffolds under the general provisions of the final rule (see 61 FR 46033). In this...

  4. Controls on stable sulfur isotope fractionation during bacterial sulfate reduction in Arctic sediments

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Knoblauch, Christian; Jørgensen, Bo Barker

    2001-03-01

    Sulfur isotope fractionation experiments during bacterial sulfate reduction were performed with recently isolated strains of cold-adapted sulfate-reducing bacteria from Arctic marine sediments with year-round temperatures below 2°C. The bacteria represent quantitatively important members of a high-latitude anaerobic microbial community. In the experiments, cell-specific sulfate reduction rates decreased with decreasing temperature and were only slightly higher than the inferred cell-specific sulfate reduction rates in their natural habitat. The experimentally determined isotopic fractionations varied by less than 5.8‰ with respect to temperature and sulfate reduction rate, whereas the difference in sulfur isotopic fractionation between bacteria with different carbon oxidation pathways was as large as 17.4‰. Incubation of sediment slurries from two Arctic localities across an experimental temperature gradient from -4°C to 39°C yielded an isotopic fractionation of 30‰ below 7.6°C, a fractionation of 14‰ and 15.5‰ between 7.6°C and 25°C, and fractionations of 5‰ and 8‰ above 25°C, respectively. In absence of significant differences in sulfate reduction rates in the high and low temperature range, respectively, we infer that different genera of sulfate-reducing bacteria dominate the sulfate-reducing bacterial community at different temperatures. In the Arctic sediments where these bacteria are abundant the isotopic differences between dissolved sulfate, pyrite, and acid-volatile sulfide are at least twice as large as the experimentally determined isotopic fractionations. On the basis of bacterial abundance and cell-specific sulfate reduction rates, these greater isotopic differences cannot be accounted for by significantly lower in situ bacterial sulfate reduction rates. Therefore, the remaining isotopic difference between sulfate and sulfide must derive from additional isotope effects that exist in the oxidative part of the sedimentary sulfur

  5. Tiltrotor noise reduction through flight trajectory management and aircraft configuration control

    NASA Astrophysics Data System (ADS)

    Gervais, Marc

    A tiltrotor can hover, takeoff and land vertically as well as cruise at high speeds and fly long distances. Because of these unique capabilities, tiltrotors are envisioned as an aircraft that could provide a solution to the issue of airport gridlock by operating on stub runways, helipads, or from smaller regional airports. However, during an approach-to-land a tiltrotor is susceptible to radiating strong impulsive noise, in particular, Blade-Vortex Interaction noise (BVI), a phenomenon highly dependent on the vehicle's performance-state. A mathematical model was developed to predict the quasi-static performance characteristics of a tiltrotor during a converting approach in the longitudinal plane. Additionally, a neural network was designed to model the acoustic results from a flight test of the XV-15 tiltrotor as a function of the aircraft's performance parameters. The performance model was linked to the neural network to yield a combined performance/acoustic model that is capable of predicting tiltrotor noise emitted during a decelerating approach. The model was then used to study noise trends associated with different combinations of airspeed, nacelle tilt, and flight path angle. It showed that BVI noise is the dominant noise source during a descent and that its strength increases with steeper descent angles. Strong BVI noise was observed at very steep flight path angles, suggesting that the tiltrotor's high downwash prevents the wake from being pushed above the rotor, even at such steep descent angles. The model was used to study the effects of various aircraft configuration and flight trajectory parameters on the rotor inflow, which adequately captured the measured BVI noise trends. Flight path management effectively constrained the rotor inflow during a converting approach and thus limited the strength of BVI noise. The maximum deceleration was also constrained by controlling the nacelle tilt-rate during conversion. By applying these constraints, low BVI noise

  6. System and method for controlling an engine based on ammonia storage in multiple selective catalytic reduction catalysts

    DOEpatents

    Sun, MIn; Perry, Kevin L.

    2015-11-20

    A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

  7. End-state comfort and joint configuration variance during reaching.

    PubMed

    Solnik, Stanislaw; Pazin, Nemanja; Coelho, Chase J; Rosenbaum, David A; Scholz, John P; Zatsiorsky, Vladimir M; Latash, Mark L

    2013-03-01

    This study joined two approaches to motor control. The first approach comes from cognitive psychology and is based on the idea that goal postures and movements are chosen to satisfy task-specific constraints. The second approach comes from the principle of motor abundance and is based on the idea that control of apparently redundant systems is associated with the creation of multi-element synergies stabilizing important performance variables. The first approach has been tested by relying on psychophysical ratings of comfort. The second approach has been tested by estimating variance along different directions in the space of elemental variables such as joint postures. The two approaches were joined here. Standing subjects performed series of movements in which they brought a hand-held pointer to each of four targets oriented within a frontal plane, close to or far from the body. The subjects were asked to rate the comfort of the final postures, and the variance of their joint configurations during the steady state following pointing was quantified with respect to pointer endpoint position and pointer orientation. The subjects showed consistent patterns of comfort ratings among the targets, and all movements were characterized by multi-joint synergies stabilizing both pointer endpoint position and orientation. Contrary to what was expected, less comfortable postures had higher joint configuration variance than did more comfortable postures without major changes in the synergy indices. Multi-joint synergies stabilized the pointer position and orientation similarly across a range of comfortable/uncomfortable postures. The results are interpreted in terms conducive to the two theoretical frameworks underlying this work, one focusing on comfort ratings reflecting mean postures adopted for different targets and the other focusing on indices of joint configuration variance. PMID:23288326

  8. End-state comfort and joint configuration variance during reaching

    PubMed Central

    Solnik, Stanislaw; Pazin, Nemanja; Coelho, Chase J.; Rosenbaum, David A.; Scholz, John P.; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2013-01-01

    This study joined two approaches to motor control. The first approach comes from cognitive psychology and is based on the idea that goal postures and movements are chosen to satisfy task-specific constraints. The second approach comes from the principle of motor abundance and is based on the idea that control of apparently redundant systems is associated with the creation of multi-element synergies stabilizing important performance variables. The first approach has been tested by relying on psychophysical ratings of comfort. The second approach has been tested by estimating variance along different directions in the space of elemental variables such as joint postures. The two approaches were joined here. Standing subjects performed series of movements in which they brought a hand-held pointer to each of four targets oriented within a frontal plane, close to or far from the body. The subjects were asked to rate the comfort of the final postures, and the variance of their joint configurations during the steady state following pointing was quantified with respect to pointer endpoint position and pointer orientation. The subjects showed consistent patterns of comfort ratings among the targets, and all movements were characterized by multi-joint synergies stabilizing both pointer endpoint position and orientation. Contrary to what was expected, less comfortable postures had higher joint configuration variance than did more comfortable postures without major changes in the synergy indices. Multi-joint synergies stabilized the pointer position and orientation similarly across a range of comfortable/uncomfortable postures. The results are interpreted in terms conducive to the two theoretical frameworks underlying this work, one focusing on comfort ratings reflecting mean postures adopted for different targets and the other focusing on indices of joint configuration variance. PMID:23288326

  9. A cylindrical capacitor ionization source: droplet generation and controlled charge reduction for mass spectrometry.

    PubMed

    Ebeling, D D; Westphall, M S; Scalf, M; Smith, L M

    2001-01-01

    A cylindrical capacitor ionization source was used in conjunction with corona discharge charge reduction for generation of singly charged ions for mass spectrometric analysis. The source consists of a fused-silica capillary threaded with a platinum wire and placed inside a stainless steel tube. Application of an electric potential to the wire results in the production of a linear stream of charged droplets when an aqueous solution is pumped through the capillary. Subsequent solvent evaporation yields ions, providing a continuous ion source for mass spectrometry. Passage of the ions through a corona discharge charge reduction chamber permits reduction of the charge state to predominantly singly charged species, facilitating analysis of DNA and protein mixtures. The change from production of multiply charged ions to production of singly charged ions is extremely simple, requiring only modulation of the voltage applied to the corona discharge electrode. A simple technique for construction of the ionization source is reported.

  10. Advanced experimental analysis of controls on microbial Fe(III) oxide reduction. First year progress report

    SciTech Connect

    Roden, E.E.; Urrutia, M.M.

    1997-07-01

    'The authors have made considerable progress toward a number of project objectives during the first several months of activity on the project. An exhaustive analysis was made of the growth rate and biomass yield (both derived from measurements of cell protein production) of two representative strains of Fe(III)-reducing bacteria (Shewanellaalga strain BrY and Geobactermetallireducens) growing with different forms of Fe(III) as an electron acceptor. These two fundamentally different types of Fe(III)-reducing bacteria (FeRB) showed comparable rates of Fe(III) reduction, cell growth, and biomass yield during reduction of soluble Fe(III)-citrate and solid-phase amorphous hydrous ferric oxide (HFO). Intrinsic growth rates of the two FeRB were strongly influenced by whether a soluble or a solid-phase source of Fe(III) was provided: growth rates on soluble Fe(III) were 10--20 times higher than those on solid-phase Fe(III) oxide. Intrinsic FeRB growth rates were comparable during reduction of HF0 and a synthetic crystalline Fe(III) oxide (goethite). A distinct lag phase for protein production was observed during the first several days of incubation in solid-phase Fe(III) oxide medium, even though Fe(III) reduction proceeded without any lag. No such lag between protein production and Fe(III) reduction was observed during growth with soluble Fe(III). This result suggested that protein synthesis coupled to solid-phase Fe(III) oxide reduction in batch culture requires an initial investment of energy (generated by Fe(III) reduction), which is probably needed for synthesis of materials (e.g. extracellular polysaccharides) required for attachment of the cells to oxide surfaces. This phenomenon may have important implications for modeling the growth of FeRB in subsurface sedimentary environments, where attachment and continued adhesion to solid-phase materials will be required for maintenance of Fe(III) reduction activity. Despite considerable differences in the rate and pattern

  11. Thermodynamic controls on the microbial reduction of iron-bearing nontronite and uranium.

    PubMed

    Luan, Fubo; Gorski, Christopher A; Burgos, William D

    2014-01-01

    Iron-bearing phyllosilicate minerals help establish the hydrogeological and geochemical conditions of redox transition zones because of their small size, limited hydraulic conductivity, and redox buffering capacity. The bioreduction of soluble U(VI) to sparingly soluble U(IV) can promote the reduction of clay-Fe(III) through valence cycling. The reductive precipitation of U(VI) to uraninite was previously reported to occur only after a substantial percentage of clay-Fe(III) had been reduced. Using improved analytical techniques, we show that concomitant bioreduction of both U(VI) and clay-Fe(III) by Shewanella putrefaciens CN32 can occur. Soluble electron shuttles were previously shown to enhance both the rate and extent of clay-Fe(III) bioreduction. Using extended incubation periods, we show that electron shuttles enhance only the rate of reduction (overcoming a kinetic limitation) and not the final extent of reduction (a thermodynamic limitation). The first 20% of clay-Fe(III) in nontronite NAu-2 was relatively "easy" (i.e., rapid) to bioreduce; the next 15% of clay-Fe(III) was "harder" (i.e., kinetically limited) to bioreduce, and the remaining 65% of clay-Fe(III) was effectively biologically unreducible. In abiotic experiments with NAu-2 and biogenic uraninite, 16.4% of clay-Fe(III) was reduced in the presence of excess uraninite. In abiotic experiments with NAu-2 and reduced anthraquinone 2,6-disulfonate (AH2DS), 18.5-19.1% of clay-Fe(III) was reduced in the presence of excess and variable concentrations of AH2DS. A thermodynamic model based on published values of the nonstandard state reduction potentials at pH 7.0 (E'H) showed that the abiotic reactions between NAu-2 and uraninite had reached an apparent equilibrium. This model also showed that the abiotic reactions between NAu-2 and AH2DS had reached an apparent equilibrium. The final extent of clay-Fe(III) reduction correlated well with the standard state reduction potential at pH 7.0 (E°'H) of all of the

  12. GENERIC VERIFICATION PROTOCOL FOR DETERMINATION OF EMISSIONS REDUCTIONS FROM SELECTIVE CATALYTIC REDUCTIONS CONTROL TECHNOLOGIES FOR HIGHWAY, NONROAD, AND STATIONARY USE DIESEL ENGINES

    EPA Science Inventory

    The protocol describes the Environmental Technology Verification (ETV) Program's considerations and requirements for verification of emissions reduction provided by selective catalytic reduction (SCR) technologies. The basis of the ETV will be comparison of the emissions and perf...

  13. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    NASA Astrophysics Data System (ADS)

    Ho, Jen-Hsuan; Berkhoff, Arthur

    2014-03-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of two panels with air in between and offers the advantages of low sound transmission at high frequencies, low heat transmission, and low weight. The double panel structure is widely used, such as in the aerospace and automotive industries. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel's noise control performance. Applying active structural acoustic control to the panels or active noise control to the cavity has been discussed in many papers. In this paper, the resonances of the panels and the cavity are considered simultaneously to further reduce the transmitted noise through an existing double panel structure. A structural-acoustic coupled model is developed to investigate and compare various structural control and cavity control methods. Numerical analysis and real-time control results show that structural control should be applied to both panels. Three types of cavity control sources are presented and compared. The results indicate that the largest noise reduction is obtained with cavity control by loudspeakers modified to operate as incident pressure sources.

  14. Least square based sliding mode control for a quad-rotor helicopter and energy saving by chattering reduction

    NASA Astrophysics Data System (ADS)

    Sumantri, Bambang; Uchiyama, Naoki; Sano, Shigenori

    2016-01-01

    In this paper, a new control structure for a quad-rotor helicopter that employs the least squares method is introduced. This proposed algorithm solves the overdetermined problem of the control input for the translational motion of a quad-rotor helicopter. The algorithm allows all six degrees of freedom to be considered to calculate the control input. The sliding mode controller is applied to achieve robust tracking and stabilization. A saturation function is designed around a boundary layer to reduce the chattering phenomenon that is a common problem in sliding mode control. In order to improve the tracking performance, an integral sliding surface is designed. An energy saving effect because of chattering reduction is also evaluated. First, the dynamics of the quad-rotor helicopter is derived by the Newton-Euler formulation for a rigid body. Second, a constant plus proportional reaching law is introduced to increase the reaching rate of the sliding mode controller. Global stability of the proposed control strategy is guaranteed based on the Lyapunov's stability theory. Finally, the robustness and effectiveness of the proposed control system are demonstrated experimentally under wind gusts, and are compared with a regular sliding mode controller, a proportional-differential controller, and a proportional-integral-differential controller.

  15. Randomized controlled trial of the self-stigma reduction program among individuals with schizophrenia.

    PubMed

    Fung, Kelvin M T; Tsang, Hector W H; Cheung, Wai-ming

    2011-09-30

    Research evidence suggests that individuals with schizophrenia are prone to self-stigmatization, which reduces their psychosocial treatment adherence. A self-stigma reduction program was developed based on a theoretical framework proposed by our team. The effectiveness of such program to reduce self-stigma, enhance readiness for change, and promote adherent behaviors among individuals with schizophrenia was investigated. This program consisted of 12 group and four individual follow-up sessions. An integrative approach including psychoeductaion, cognitive behavioral therapy, motivational interviewing, social skills training, and goal attainment program was adopted. Sixty-six self-stigmatized individuals with schizophrenia were recruited. They were randomly allocated to the self-stigma reduction program (N=34; experimental protocol) or the newspaper reading group (N=32; comparison protocol). Measures on participants' level of self-stigma, readiness for change, insight, general self-efficacy, and treatment adherence were taken for six assessment intervals. The findings suggested that the self-stigma reduction program has potential to reduce self-esteem decrement, promote readiness for changing own problematic behaviors, and enhance psychosocial treatment adherence among the self-stigmatized individuals with schizophrenia during the active interventional stage. However, there was a lack of therapeutic maintenance effects during the 6-month follow-up period. Recommendations for further improving the effectiveness of self-stigma reduction program are suggested. PMID:21377738

  16. Randomized controlled trial of the self-stigma reduction program among individuals with schizophrenia.

    PubMed

    Fung, Kelvin M T; Tsang, Hector W H; Cheung, Wai-ming

    2011-09-30

    Research evidence suggests that individuals with schizophrenia are prone to self-stigmatization, which reduces their psychosocial treatment adherence. A self-stigma reduction program was developed based on a theoretical framework proposed by our team. The effectiveness of such program to reduce self-stigma, enhance readiness for change, and promote adherent behaviors among individuals with schizophrenia was investigated. This program consisted of 12 group and four individual follow-up sessions. An integrative approach including psychoeductaion, cognitive behavioral therapy, motivational interviewing, social skills training, and goal attainment program was adopted. Sixty-six self-stigmatized individuals with schizophrenia were recruited. They were randomly allocated to the self-stigma reduction program (N=34; experimental protocol) or the newspaper reading group (N=32; comparison protocol). Measures on participants' level of self-stigma, readiness for change, insight, general self-efficacy, and treatment adherence were taken for six assessment intervals. The findings suggested that the self-stigma reduction program has potential to reduce self-esteem decrement, promote readiness for changing own problematic behaviors, and enhance psychosocial treatment adherence among the self-stigmatized individuals with schizophrenia during the active interventional stage. However, there was a lack of therapeutic maintenance effects during the 6-month follow-up period. Recommendations for further improving the effectiveness of self-stigma reduction program are suggested.

  17. 7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR parts 905 through 998 under the Paperwork Reduction Act of 1995. (b) Display. 7 CFR part where identified and...-0149 922, Washington Apricots 0581-0095 923, Washington Sweet Cherries 0581-0133 924,...

  18. 7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR parts 905 through 998 under the Paperwork Reduction Act of 1995. (b) Display. 7 CFR part where identified and...-0149 922, Washington Apricots 0581-0095 923, Washington Sweet Cherries 0581-0133 924,...

  19. 7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR parts 905 through 998 under the Paperwork Reduction Act of 1995. (b) Display. 7 CFR part where identified and...-0149 922, Washington Apricots 0581-0095 923, Washington Sweet Cherries 0581-0133 924,...

  20. 7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR parts 905 through 998 under the Paperwork Reduction Act of 1995. (b) Display. 7 CFR part where identified and...-0149 922, Washington Apricots 0581-0095 923, Washington Sweet Cherries 0581-0133 924,...

  1. 7 CFR 28.165 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... assigned to information collection requirements of the Office of Management and Budget contained in 7 CFR part 28 under the Paperwork Reduction Act of 1980. (b) Display. 7 CFR sections where identified and... MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE...

  2. 7 CFR 1250.501 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... collection requirements by the Office of Management and Budget contained in 7 CFR part 1250 pursuant to the Paperwork Reduction Act of 1980, Pub. L. 96-511. (b) Display. 7 CFR section where identified and described... (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS...

  3. 7 CFR 28.165 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... assigned to information collection requirements of the Office of Management and Budget contained in 7 CFR part 28 under the Paperwork Reduction Act of 1980. (b) Display. 7 CFR sections where identified and... MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE...

  4. 7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR parts 905 through 998 under the Paperwork Reduction Act of 1995. (b) Display. 7 CFR part where identified and..., California Nectarines 0581-0072 917, California Pears and Peaches 0581-0080 920, California Kiwifruit...

  5. SUPERVISORY CONTROL FOR PEAK REDUCTION IN COMMERCIAL BUILDINGS WHILE MAINTAINING COMFORT

    SciTech Connect

    Nutaro, James J; Olama, Mohammed M; Kuruganti, Teja

    2016-01-01

    This paper describes a supervisory control strategy for limiting peak power demand by small and medium commercial buildings while still meeting the business needs of the occupants. This control strategy has two features that make it relevant to new and existing buildings. First, it is designed to operate with building equipment, such as air conditioning and refrigeration systems, as they are presently installed in most small and medium commercial buildings. Because of this, the supervisory control could be realized as a software-only retrofit to existing building management systems. Second, the proposed control acts as a supervisory management layer over existing control systems, rather than replacing them outright. The primary idea of this approach is that the controls for individual building equipment request energy resources for a control action and the supervisory control examines the requests and decides which control actions to allow while satisfying a limit on peak power demand.

  6. Controlled synthesis of layered Sn3O4 nanobelts by carbothermal reduction method and their gas sensor properties.

    PubMed

    Suman, P H; Longo, E; Varela, J A; Orlandi, M O

    2014-09-01

    This paper reports both the controlled synthesis of Sn3O4 nanobelts by carbothermal reduction method and the gas sensor properties of these nanostructures. The synthesized material was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and gas sensor measurements. The results showed that the Sn3O4 nanobelts grow in a layered way and the careful control of experimental parameters is fundamental for stabilization of the correct phase. From the gas sensor measurements using oxygen as analyte gas, it was observed that the Sn3O4 nanobelts exhibit n-type behavior and both the sensitivity and the response time are dependent on the oxygen concentration. A model based on molecules adsorption was proposed to illustrate the mechanism of gas detection of these nanostructures. In summary, these results indicate that Sn3O4 nanobelts synthesized by carbothermal reduction method are promising to be applied as gas sensors.

  7. Numerical study of wingtip shed vorticity reduction by wing Boundary Layer Control

    NASA Astrophysics Data System (ADS)

    Posada, Jose Alejandro

    Wingtip vortex reductions have been obtained by Boundary Layer Control application to an AR=1.5 rectangular wing using a NACA 0012 airfoil. If wingtip shed vorticity could be reduced significantly, then so would induced drag resulting in improved cruise fuel economy. Power savings would be even more impressive at low flight speed or in climb. A two dimensional wing produces lift without wingtip vorticity. Its bound vorticity, Gamma, equals the contour integral of the boundary layer vorticity gamma or Gamma = ∮gamma · dl. Where the upper and lower boundary layers meet at the cusped TE, their local static pressure pu=pl then the boundary layer outer edge inviscid velocity Vupper=Vlower and gammalower=-gamma upper. This explains the 2-D wing self cancellation of the upper and lower surface boundary layer vorticity when they meet upon shedding at the trailing edge. In finite wings, the presence of spanwise pressure gradients near the wing tips misaligns gammalower and gammaupper at the wingtip TE preventing the upper and lower surface boundary layers from completely canceling each other. To prevent them from generating wing tip vortices, the local boundary layers need to be captured in suction slots. Once vorticity is captured, it can be eliminated by viscous mixing prior to venting over board. The objective of this dissertation was to use a commercial Computational Fluid Dynamics code (Fluent) to search for the best configuration to locate BLC suction slots to capture non-parallel boundary layer vorticity prior to shedding near the wingtips. The configuration selected for running the simulations was tested by trying to duplicate a 3D wing for which sufficient experimental and computational models by others are available. The practical case selected was done by Chow et al in the 32 x 48 in. low speed wind tunnel at the Fluid Mechanics Laboratory of NASA Ames Research Center, and computationally analyzed by Dacles-Mariani et al, and Khim and Rhee. The present

  8. 42 CFR 456.521 - Conditions for granting variance requests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., and Variances for Hospitals and Mental Hospitals Ur Plan: Remote Facility Variances from Time... submits concurrently— (1) A request for the variance that documents to his satisfaction that the facility is unable to meet the time requirements for which the variance is requested; and (2) A revised...

  9. Variant evolutionary trees under phenotypic variance.

    PubMed

    Nishimura, Kinya; Isoda, Yutaka

    2004-01-01

    Evolutionary branching, which is a coevolutionary phenomenon of the development of two or more distinctive traits from a single trait in a population, is the issue of recent studies on adaptive dynamics. In previous studies, it was revealed that trait variance is a minimum requirement for evolutionary branching, and that it does not play an important role in the formation of an evolutionary pattern of branching. Here we demonstrate that the trait evolution exhibits various evolutionary branching paths starting from an identical initial trait to different evolutional terminus traits as determined by only changing the assumption of trait variance. The key feature of this phenomenon is the topological configuration of equilibria and the initial point in the manifold of dimorphism from which dimorphic branches develop. This suggests that the existing monomorphic or polymorphic set in a population is not an unique inevitable consequence of an identical initial phenotype.

  10. Analysis of Variance of Multiply Imputed Data.

    PubMed

    van Ginkel, Joost R; Kroonenberg, Pieter M

    2014-01-01

    As a procedure for handling missing data, Multiple imputation consists of estimating the missing data multiple times to create several complete versions of an incomplete data set. All these data sets are analyzed by the same statistical procedure, and the results are pooled for interpretation. So far, no explicit rules for pooling F-tests of (repeated-measures) analysis of variance have been defined. In this paper we outline the appropriate procedure for the results of analysis of variance for multiply imputed data sets. It involves both reformulation of the ANOVA model as a regression model using effect coding of the predictors and applying already existing combination rules for regression models. The proposed procedure is illustrated using three example data sets. The pooled results of these three examples provide plausible F- and p-values.

  11. Analysis of variance of microarray data.

    PubMed

    Ayroles, Julien F; Gibson, Greg

    2006-01-01

    Analysis of variance (ANOVA) is an approach used to identify differentially expressed genes in complex experimental designs. It is based on testing for the significance of the magnitude of effect of two or more treatments taking into account the variance within and between treatment classes. ANOVA is a highly flexible analytical approach that allows investigators to simultaneously assess the contributions of multiple factors to gene expression variation, including technical (dye, batch) effects and biological (sex, genotype, drug, time) ones, as well as interactions between factors. This chapter provides an overview of the theory of linear mixture modeling and the sequence of steps involved in fitting gene-specific models and discusses essential features of experimental design. Commercial and open-source software for performing ANOVA is widely available.

  12. PHD filtering with localised target number variance

    NASA Astrophysics Data System (ADS)

    Delande, Emmanuel; Houssineau, Jérémie; Clark, Daniel

    2013-05-01

    Mahler's Probability Hypothesis Density (PHD filter), proposed in 2000, addresses the challenges of the multipletarget detection and tracking problem by propagating a mean density of the targets in any region of the state space. However, when retrieving some local evidence on the target presence becomes a critical component of a larger process - e.g. for sensor management purposes - the local target number is insufficient unless some confidence on the estimation of the number of targets can be provided as well. In this paper, we propose a first implementation of a PHD filter that also includes an estimation of localised variance in the target number following each update step; we then illustrate the advantage of the PHD filter + variance on simulated data from a multiple-target scenario.

  13. Systems Engineering Programmatic Estimation Using Technology Variance

    NASA Technical Reports Server (NTRS)

    Mog, Robert A.

    2000-01-01

    Unique and innovative system programmatic estimation is conducted using the variance of the packaged technologies. Covariance analysis is performed oil the subsystems and components comprising the system of interest. Technological "returns" and "variation" parameters, are estimated. These parameters are combined with the model error to arrive at a measure of system development stability. The resulting estimates provide valuable information concerning the potential cost growth of the system under development.

  14. Systems Engineering Programmatic Estimation Using Technology Variance

    NASA Technical Reports Server (NTRS)

    Mog, Robert A.

    2000-01-01

    Unique and innovative system programmatic estimation is conducted using the variance of the packaged technologies. Covariance analysis is performed on the subsystems and components comprising the system of interest. Technological "return" and "variation" parameters are estimated. These parameters are combined with the model error to arrive at a measure of system development stability. The resulting estimates provide valuable information concerning the potential cost growth of the system under development.

  15. Uses and abuses of analysis of variance.

    PubMed Central

    Evans, S J

    1983-01-01

    Analysis of variance is a term often quoted to explain the analysis of data in experiments and clinical trials. The relevance of its methodology to clinical trials is shown and an explanation of the principles of the technique is given. The assumptions necessary are examined and the problems caused by their violation are discussed. The dangers of misuse are given with some suggestions for alternative approaches. PMID:6347228

  16. Applications of non-parametric statistics and analysis of variance on sample variances

    NASA Technical Reports Server (NTRS)

    Myers, R. H.

    1981-01-01

    Nonparametric methods that are available for NASA-type applications are discussed. An attempt will be made here to survey what can be used, to attempt recommendations as to when each would be applicable, and to compare the methods, when possible, with the usual normal-theory procedures that are avavilable for the Gaussion analog. It is important here to point out the hypotheses that are being tested, the assumptions that are being made, and limitations of the nonparametric procedures. The appropriateness of doing analysis of variance on sample variances are also discussed and studied. This procedure is followed in several NASA simulation projects. On the surface this would appear to be reasonably sound procedure. However, difficulties involved center around the normality problem and the basic homogeneous variance assumption that is mase in usual analysis of variance problems. These difficulties discussed and guidelines given for using the methods.

  17. Hypothesis exploration with visualization of variance

    PubMed Central

    2014-01-01

    Background The Consortium for Neuropsychiatric Phenomics (CNP) at UCLA was an investigation into the biological bases of traits such as memory and response inhibition phenotypes—to explore whether they are linked to syndromes including ADHD, Bipolar disorder, and Schizophrenia. An aim of the consortium was in moving from traditional categorical approaches for psychiatric syndromes towards more quantitative approaches based on large-scale analysis of the space of human variation. It represented an application of phenomics—wide-scale, systematic study of phenotypes—to neuropsychiatry research. Results This paper reports on a system for exploration of hypotheses in data obtained from the LA2K, LA3C, and LA5C studies in CNP. ViVA is a system for exploratory data analysis using novel mathematical models and methods for visualization of variance. An example of these methods is called VISOVA, a combination of visualization and analysis of variance, with the flavor of exploration associated with ANOVA in biomedical hypothesis generation. It permits visual identification of phenotype profiles—patterns of values across phenotypes—that characterize groups. Visualization enables screening and refinement of hypotheses about variance structure of sets of phenotypes. Conclusions The ViVA system was designed for exploration of neuropsychiatric hypotheses by interdisciplinary teams. Automated visualization in ViVA supports ‘natural selection’ on a pool of hypotheses, and permits deeper understanding of the statistical architecture of the data. Large-scale perspective of this kind could lead to better neuropsychiatric diagnostics. PMID:25097666

  18. Facile and controllable electrochemical reduction of graphene oxide and its applications

    SciTech Connect

    Shao, Yuyan; Wang, Jun; Engelhard, Mark H.; Wang, Chong M.; Lin, Yuehe

    2010-01-01

    Graphene oxide is electrochemically reduced which is called electrochemically reduced graphene oxide (ER-G). ER-G is characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The oxygen content is significantly decreased and the sp 2 carbon is restored after electrochemical reduction. ER-G exhibits much higher electrochemical capacitance and cycling durability than carbon nanotubes (CNTs) and chemically reduced graphene; the specific capacitance measured with cyclic voltammetry (20 mV/s) is ~165 F/g, ~86 F/g, and ~100 F/g for ER-G, CNTs, and chemically reduced graphene,1 respectively. The electrochemical reduction of oxygen and hydrogen peroxide was greatly enhanced on ER-G electrodes as compared with CNTs. ER-G has shown a good potential for applications in energy storage, biosensors, and electrocatalysis.

  19. 27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Scope of Regulations... Management and Budget contained in 27 CFR Part 25 under the Paperwork Reduction Act of 1980, Pub. L. 96-511... sections in 27 CFR Part 25: §§ 25.23, 25.25, 25.52, 25.61, 25.62, 25.64, 25.66, 25.67, 25.68, 25.71,...

  20. 27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Scope of Regulations... Management and Budget contained in 27 CFR Part 25 under the Paperwork Reduction Act of 1980, Pub. L. 96-511... sections in 27 CFR Part 25: §§ 25.23, 25.25, 25.52, 25.61, 25.62, 25.64, 25.66, 25.67, 25.68, 25.71,...

  1. 27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Scope of Regulations... Management and Budget contained in 27 CFR Part 25 under the Paperwork Reduction Act of 1980, Pub. L. 96-511... sections in 27 CFR Part 25: §§ 25.23, 25.25, 25.52, 25.61, 25.62, 25.64, 25.66, 25.67, 25.68, 25.71,...

  2. 9 CFR 590.18 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR 590 pursuant to the Paperwork Reduction Act of 1980, Pub. L. 96-511. (b) Display. 7 CFR section where identified and...-0113 § 590.320 0581-0113 § 590.402(a) 0581-0113 § 590.411(a) 0581-0113 § 590.411(b) 0581-0113 §...

  3. 9 CFR 590.18 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR 590 pursuant to the Paperwork Reduction Act of 1980, Pub. L. 96-511. (b) Display. 7 CFR section where identified and...-0113 § 590.320 0581-0113 § 590.402(a) 0581-0113 § 590.411(a) 0581-0113 § 590.411(b) 0581-0113 §...

  4. 9 CFR 590.18 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... information collection requirements by the Office of Management and Budget contained in 7 CFR 590 pursuant to the Paperwork Reduction Act of 1980, Pub. L. 96-511. (b) Display. 7 CFR section where identified and...-0113 § 590.320 0581-0113 § 590.402(a) 0581-0113 § 590.411(a) 0581-0113 § 590.411(b) 0581-0113 §...

  5. Data Reduction and Control Software for Meteor Observing Stations Based on CCD Video Systems

    NASA Technical Reports Server (NTRS)

    Madiedo, J. M.; Trigo-Rodriguez, J. M.; Lyytinen, E.

    2011-01-01

    The SPanish Meteor Network (SPMN) is performing a continuous monitoring of meteor activity over Spain and neighbouring countries. The huge amount of data obtained by the 25 video observing stations that this network is currently operating made it necessary to develop new software packages to accomplish some tasks, such as data reduction and remote operation of autonomous systems based on high-sensitivity CCD video devices. The main characteristics of this software are described here.

  6. Rates of microbial sulfate reduction control the sizes of biogenic iron sulfide aggregates

    NASA Astrophysics Data System (ADS)

    Jin, Q.

    2005-12-01

    Sulfide minerals occur widely in freshwater and marine sediments as byproducts of microbial sulfate reduction and as end products of heavy metal bioremediation. They form when metals in the environments combine with sulfide produced from the metabolism of sulfate reducing bacteria. We used chemostat bioreactors to study sizes and crystal structures of iron sulfide (FeS) minerals produced by Desulfovibrio vulgaris, D. desulfuricans strain G20, and subspecies desulfuricans. FeS nanoparticles and their aggregates are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS). FeS nanoparticles produced by sulfate reducing bacteria are extremely small, usually less than around 10 nm in diameter. Nanoparticles do not occur as individual nanoparticles, but as aggregates. The sizes of FeS aggregates are affected by sulfate reduction rates, Fe(II) concentration, pH, ionic strength, organic matter concentration, bacterial species, etc. Aggregate size ranges from about 500 nm at very large sulfate reduction rates to about 1,500 nm at very small rates. Variations in Fe(II) concentration also lead to a difference up to 500 nm in FeS aggregate size. Different bacterial species produce nanoparticle aggregates of different sizes under similar growth conditions. For example, D. vulgaris produces FeS aggregates with sizes 500 nm smaller than those by strain G20. The inverse relationship between FeS aggregate sizes and sulfate reduction rates is important in evaluating metal bioremediation strategies. Previous approaches have focused on stimulating microbial activities in natural environments. However, our experimental results suggest that increasing metabolic rates may decrease the aggregate size, increasing the mobility of colloidal aggregates. Therefore, the balance between microbial activities and sizes of biogenic aggregates may be an important consideration in the design and

  7. Nitrogen oxides from waste incineration: control by selective non-catalytic reduction.

    PubMed

    Zandaryaa, S; Gavasci, R; Lombardi, F; Fiore, A

    2001-01-01

    An experimental study of the selective non-catalytic reduction (SNCR) process was carried out to determine the efficiency of NOx removal and NH3 mass balance, the NOx reducing reagent used. Experimental tests were conducted on a full-scale SNCR system installed in a hospital waste incineration plant. Anhydrous NH3 was injected at the boiler entrance for NOx removal. Ammonia was analyzed after each flue-gas treatment unit in order to establish its mass balance and NH3 slip in the stack gas was monitored as well. The effective fraction of NH3 for the thermal NOx reduction was calculated from measured values of injected and residual NH3. Results show that a NOx reduction efficiency in the range of 46.7-76.7% is possible at a NH3/NO molar ratio of 0.9-1.5. The fraction of NH3 used in NOx removal was found to decrease with rising NH3/NO molar ratio. The NH3 slip in the stack gas was very low, below permitted limits, even at the higher NH3 dosages used. No direct correlation was found between the NH3/NO molar ratio and the NH3 slip in the stack gas since the major part of the residual NH3 was converted into ammonium salts in the dry scrubbing reactor and subsequently collected in the fabric filter. Moreover, another fraction of NH3 was dissolved in the scrubbing liquor.

  8. Design and testing of an independently controlled urea SCR retrofit system for the reduction of NOx emissions from marine diesels.

    PubMed

    Johnson, Derek R; Bedick, Clinton R; Clark, Nigel N; McKain, David L

    2009-05-15

    Diesel engine emissions for on-road, stationary and marine applications are regulated in the United States via standards set by the Environmental Protection Agency (EPA). A major component of diesel exhaust that is difficult to reduce is nitrogen oxides (NOx). Selective catalytic reduction (SCR) has been in use for many years for stationary applications, including external combustion boilers, and is promising for NOx abatement as a retrofit for mobile applications where diesel compression ignition engines are used. The research presented in this paper is the first phase of a program focused on the reduction of NOx by use of a stand-alone urea injection system, applicable to marine diesel engines typical of work boats (e.g., tugs). Most current urea SCR systems communicate with engine controls to predict NOx emissions based on signals such as torque and engine speed, however many marine engines in use still employ mechanical injection technology and lack electronic communication abilities. The system developed and discussed in this paper controls NOx emissions independentof engine operating parameters and measures NOx and exhaust flow using the following exhaust sensor inputs: absolute pressure, differential pressure, temperature, and NOx concentration. These sensor inputs were integrated into an independent controller and open loop architecture to estimate the necessary amount of urea needed, and the controller uses pulse width modulation (PWM) to power an automotive fuel injector for airless urea delivery. The system was tested in a transient test cell on a 350 hp engine certified at 4 g/bhp-hr of NOx, with a goal of reducing the engine out NOx levels by 50%. NOx reduction capabilities of 41-67% were shown on the non road transient cycle (NRTC) and ICOMIA E5 steady state cycles with system optimization during testing to minimize the dilute ammonia slip to cycle averages of 5-7 ppm. The goal of 50% reduction of NOx can be achieved dependent upon cycle. Further

  9. Stable isotope fractionation during bacterial sulfate reduction is controlled by reoxidation of intermediates

    NASA Astrophysics Data System (ADS)

    Mangalo, Muna; Meckenstock, Rainer U.; Stichler, Willibald; Einsiedl, Florian

    2007-09-01

    Bacterial sulfate reduction is one of the most important respiration processes in anoxic habitats and is often assessed by analyzing the results of stable isotope fractionation. However, stable isotope fractionation is supposed to be influenced by the reduction rate and other parameters, such as temperature. We studied here the mechanistic basics of observed differences in stable isotope fractionation during bacterial sulfate reduction. Batch experiments with four sulfate-reducing strains ( Desulfovibrio desulfuricans, Desulfobacca acetoxidans, Desulfonatronovibrio hydrogenovorans, and strain TRM1) were performed. These microorganisms metabolize different carbon sources (lactate, acetate, formate, and toluene) and showed broad variations in their sulfur isotope enrichment factors. We performed a series of experiments on isotope exchange of 18O between residual sulfate and ambient water. Batch experiments were conducted with 18O-enriched (δ 18O water = +700‰) and depleted water (δ 18O water = -40‰), respectively, and the stable 18O isotope shift in the residual sulfate was followed. For Desulfovibrio desulfuricans and Desulfonatronovibrio hydrogenovorans, which are both characterized by low sulfur isotope fractionation ( ɛS > -13.2‰), δ 18O values in the remaining sulfate increased by only 50‰ during growth when 18O-enriched water was used for the growth medium. In contrast, with Desulfobacca acetoxidans and strain TRM1 ( ɛS < -22.7‰) the residual sulfate showed an increase of the sulfate δ 18O close to the values of the enriched water of +700‰. In the experiments with δ 18O-depleted water, the oxygen isotope values in the residual sulfate stayed fairly constant for strains Desulfovibrio desulfuricans, Desulfobacca acetoxidans and Desulfonatronovibrio hydrogenovorans. However, strain TRM1, which exhibits the lowest sulfur isotope fractionation factor ( ɛS < -38.7‰) showed slightly decreasing δ 18O values. Our results give strong evidence that

  10. Adaptive inverse control for rotorcraft vibration reduction. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jacklin, S. A.

    1985-01-01

    The Least Mean Square (LMS) algorithm is extended to solve the multiple-input, multiple-output problem of alleviating N/Rev helicopter fuselage vibration by means of adaptive inverse control. A frequency domain locally linear model is used to represent the transfer matrix relating the high harmonic pitch control inputs to the harmonic vibration outputs to be controlled. By using the inverse matrix as the controller gain matrix, an adaptive inverse regulator is formed to alleviate the N/Rev vibration. The stability and rate of convergence properties of the extended LMS algorithm are discussed. It is shown that the stability ranges for the elements of the stability gain matrix are directly related to the eigenvalues of the vibration signal information matrix for the learning phase, but not for the control phase. The overall conclusion is that the LMS adaptive inverse control method can form a robust vibration control system, but will require some tuning of the input sensor gains, the stability gain matrix, and the amount of control relaxation to be used. The learning curve of the controller during the learning phase is shown to be quantitatively close to that predicted by averaging the learning curves of the normal modes. It is shown that the best selections of the stability gain matrix elements and the amount of control relaxation is basically a compromise between slow, stable convergence and fast convergence with increased possibility of unstable identification.

  11. Acidification and sulfide formation control during reductive dechlorination of 1,2-dichloroethane in groundwater: Effectiveness and mechanistic study.

    PubMed

    Wang, S Y; Chen, S C; Lin, Y C; Kuo, Y C; Chen, J Y; Kao, C M

    2016-10-01

    To enhance the reductive dechlorination of 1,2-dichloroethane (DCA) in groundwater, substrate injection may be required. However, substrate biodegradation causes groundwater acidification and sulfide production, which inhibits the bacteria responsible for DCA dechlorination and results in an odor problem. In the microcosm study, the effectiveness of the addition of ferrous sulfate (FS), desulfurization slag (DS), and nanoscale zero-valent iron (nZVI) on acidification and sulfide control was studied during reductive dechlorination of DCA, and the emulsified substrate (ES) was used as the substrate. Up to 94% of the sulfide was removed with FS and DS addition (0.25 wt%) (initial DCA concentration = 13.5 mg/L). FS and DS amendments resulted in the formation of a metal sulfide, which reduced the hydrogen sulfide concentration as well as the subsequent odor problem. Approximately 96% of the DCA was degraded under reductive dechlorination with nZVI or DS addition using ES as the substrate. In microcosms with nZVI or DS addition, the sulfide concentration was reduced to less than 15 μg/L. Acidification can be controlled via hydroxide ions production after nZVI oxidation and reaction of free CaO (released from DS) with water, which enhanced DCA dechlorination. The quantitative polymerase chain reaction results confirmed that the microcosms with nZVI added had the highest Dehalococcoides population (up to 2.5 × 10(8) gene copies/g soil) due to effective acidification control. The α-elimination mechanism was the main abiotic process, and reductive dechlorination dominated by Dehalococcides was the biotic mechanism that resulted in DCA removal. More than 22 bacterial species were detected, and dechlorinating bacteria existed in soils under alkaline and acidic conditions. PMID:27376861

  12. Acidification and sulfide formation control during reductive dechlorination of 1,2-dichloroethane in groundwater: Effectiveness and mechanistic study.

    PubMed

    Wang, S Y; Chen, S C; Lin, Y C; Kuo, Y C; Chen, J Y; Kao, C M

    2016-10-01

    To enhance the reductive dechlorination of 1,2-dichloroethane (DCA) in groundwater, substrate injection may be required. However, substrate biodegradation causes groundwater acidification and sulfide production, which inhibits the bacteria responsible for DCA dechlorination and results in an odor problem. In the microcosm study, the effectiveness of the addition of ferrous sulfate (FS), desulfurization slag (DS), and nanoscale zero-valent iron (nZVI) on acidification and sulfide control was studied during reductive dechlorination of DCA, and the emulsified substrate (ES) was used as the substrate. Up to 94% of the sulfide was removed with FS and DS addition (0.25 wt%) (initial DCA concentration = 13.5 mg/L). FS and DS amendments resulted in the formation of a metal sulfide, which reduced the hydrogen sulfide concentration as well as the subsequent odor problem. Approximately 96% of the DCA was degraded under reductive dechlorination with nZVI or DS addition using ES as the substrate. In microcosms with nZVI or DS addition, the sulfide concentration was reduced to less than 15 μg/L. Acidification can be controlled via hydroxide ions production after nZVI oxidation and reaction of free CaO (released from DS) with water, which enhanced DCA dechlorination. The quantitative polymerase chain reaction results confirmed that the microcosms with nZVI added had the highest Dehalococcoides population (up to 2.5 × 10(8) gene copies/g soil) due to effective acidification control. The α-elimination mechanism was the main abiotic process, and reductive dechlorination dominated by Dehalococcides was the biotic mechanism that resulted in DCA removal. More than 22 bacterial species were detected, and dechlorinating bacteria existed in soils under alkaline and acidic conditions.

  13. Minimum variance brain source localization for short data sequences.

    PubMed

    Ravan, Maryam; Reilly, James P; Hasey, Gary

    2014-02-01

    In the electroencephalogram (EEG) or magnetoencephalogram (MEG) context, brain source localization methods that rely on estimating second-order statistics often fail when the number of samples of the recorded data sequences is small in comparison to the number of electrodes. This condition is particularly relevant when measuring evoked potentials. Due to the correlated background EEG/MEG signal, an adaptive approach to localization is desirable. Previous work has addressed these issues by reducing the adaptive degrees of freedom (DoFs). This reduction results in decreased resolution and accuracy of the estimated source configuration. This paper develops and tests a new multistage adaptive processing technique based on the minimum variance beamformer for brain source localization that has been previously used in the radar statistical signal processing context. This processing, referred to as the fast fully adaptive (FFA) approach, can significantly reduce the required sample support, while still preserving all available DoFs. To demonstrate the performance of the FFA approach in the limited data scenario, simulation and experimental results are compared with two previous beamforming approaches; i.e., the fully adaptive minimum variance beamforming method and the beamspace beamforming method. Both simulation and experimental results demonstrate that the FFA method can localize all types of brain activity more accurately than the other approaches with limited data.

  14. Thermodynamic control of microbial sulfate reduction rates and consequences for the form and distribution of metal sulfide nanoparticles

    NASA Astrophysics Data System (ADS)

    Jin, Q.; Banfield, J.

    2004-12-01

    Sulfate reducing bacteria are widespread in natural environment. They derive energy for growth by reducing sulfate to sulfide. In the presence of metal ions, the sulfide byproduct precipitates as metal sulfide nanoparticles. Microorganisms can reduce sulfate through two metabolic pathways, i.e., an incomplete and a complete pathway. In the former case, microorganisms, such as Desulfovibrio sp., oxidize lactate, butyrate, ethanol, etc. to acetate, whereas in the latter, microorganisms, such as Desulfobacter sp., oxidize acetate to bicarbonate. It is important to study the kinetics of microbial sulfate reduction because microbial metabolic rates may influence the form, mobility, and reactivity of biogenic minerals. The rate of sulfate reduction is controlled not only by substrate concentrations in environments, but also by the thermodynamic driving force. The driving force is the difference between the energy available from environment and the energy conserved. The amount of energy conserved is about 80 kJ/mol lactate and 90 kJ/mol acetate for incomplete and complete pathway, respectively. Where the energy available from environments is much higher than the energy conserved, the driving force is large and sulfate reduction proceeds at high rate. The particle size of metal sulfide minerals precipitated under such conditions is extremely small. However, where the energy available is close to the energy conserved, the driving force is small and the rate of sulfate reduction is small. These conditions could favor nanoparticle transport because particle advection and dispersion may be strong enough to remove nanoparticles before large immobile aggregates can form.

  15. Effect of post heat-treatment of composition-controlled PdFe nanoparticles for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Kang, Yun Sik; Choi, Kwang-Hyun; Ahn, Docheon; Lee, Myeong Jae; Baik, Jaeyoon; Chung, Dong Young; Kim, Mi-Ju; Lee, Stanfield Youngwon; Kim, Minhyoung; Shin, Heejong; Lee, Kug-Seung; Sung, Yung-Eun

    2016-01-01

    Composition-controlled and carbon-supported PdFe nanoparticles (NPs) were prepared via a modified chemical synthesis after heat-treatment at high temperature under a reductive atmosphere. This novel synthesis, which combines the polyol reduction method and hydride method, was used to obtain monodispersed PdFe NPs. In addition, to induce structural modifications, the as-prepared PdFe NPs received heat-treatment under a reductive atmosphere. Structural characterization, including high-resolution powder diffraction (HRPD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) analysis, indicated that heat-treated PdFe NPs exhibited a higher degree of alloying and surface Pd atomic composition compared with as-prepared ones. Furthermore, new crystalline phases were detected after heat-treatment. Thanks to the structural alterations, heat-treated PdFe NPs showed ∼3 and ∼18 times higher mass- and area-normalized oxygen reduction reaction (ORR) activities, respectively than commercial Pt/C. Single cell testing with heat-treated PdFe catalysts exhibited a ∼2.5 times higher mass-normalized maximum power density than the reference cell. Surface structure analyses, including cyclic voltammetry (CV), COad oxidation, and XPS, revealed that, after heat-treatment, a downshift of the Pd d-band center occurred, which led to a decrease in the affinity of Pd for oxygen species, resulting in more favorable ORR kinetics.

  16. Smoking cessation or reduction with nicotine replacement therapy: a placebo-controlled double blind trial with nicotine gum and inhaler

    PubMed Central

    2009-01-01

    Background Even with effective smoking cessation medications, many smokers are unable to abruptly stop using tobacco. This finding has increased interest in smoking reduction as an interim step towards complete cessation. Methods This multi-center, double-blind placebo-controlled study evaluated the efficacy and safety of nicotine 4 mg gum or nicotine 10 mg inhaler in helping smokers (N = 314) to reduce or quit smoking. It included smokers willing to control their smoking, and participants could set individual goals, to reduce or quit. The study was placebo-controlled, randomized in a ratio of 2:1 (Active:Placebo), and subjects could choose inhaler or gum after randomization. Outcome was short-term (from Week 6 to Month 4) and long-term (from Month 6 to Month 12) abstinence or reduction. Abstinence was defined as not a single cigarette smoked and expired CO readings of <10 ppm. Smoking reduction was defined as a reduction in number of cigarettes per day by 50% or more versus baseline, verified by a lower-than-baseline CO reading at each visit during the same periods. Results Significantly more smokers managed to quit in the Active group than in the Placebo group. Sustained abstinence rates at 4 months were 42/209 (20.1%) subjects in the Active group and 9/105 (8.6%) subjects in the Placebo group (p = 0.009). Sustained abstinence rates at 12 months were 39/209 (18.7%) and 9/105 (8.6%), respectively (p = 0.019). Smoking reduction did not differ between the groups, either at short-term or long-term. Twelve-month reduction results were 17.2% vs. 18.1%, respectively. No serious adverse events were reported. Conclusion In conclusion, treatment with 10 mg nicotine inhaler or 4 mg nicotine chewing gum resulted in a significantly higher abstinence rate than placebo. In addition a large number of smokers managed to reduce their cigarette consumption by more than 50% compared to baseline. PMID:19943947

  17. Factorization and reduction methods for optimal control of distributed parameter systems

    NASA Technical Reports Server (NTRS)

    Burns, J. A.; Powers, R. K.

    1985-01-01

    A Chandrasekhar-type factorization method is applied to the linear-quadratic optimal control problem for distributed parameter systems. An aeroelastic control problem is used as a model example to demonstrate that if computationally efficient algorithms, such as those of Chandrasekhar-type, are combined with the special structure often available to a particular problem, then an abstract approximation theory developed for distributed parameter control theory becomes a viable method of solution. A numerical scheme based on averaging approximations is applied to hereditary control problems. Numerical examples are given.

  18. Iron Reduction and Radionuclide Immobilization: Kinetic, Thermodynamic and Hydrologic controls & Reaction-Based Modeling - Final Report

    SciTech Connect

    William D. Burgos

    2004-06-18

    Our research focused on (1) microbial reduction of Fe(III) and U(VI) individually, and concomitantly in natural sediments, (2) Fe(III) oxide surface chemistry, specifically with respect to reactions with Fe(II)and U(VI), (3) the influence of humic substances on Fe(III) and U(VI) bioreduction, and on U(VI) complexation, and (4) the development of reaction-based reactive transport biogeochemical models to numerically simulate our experimental results. We have continued our investigations on microbial reduction of Fe(III) oxides. Modeling our earlier experimental results required assumption of a hydrated surface for hematite, more reactive than predicted based on theoretical solubility (Burgos et al.2002). Subsequent studies with Shewanella putrefaciens and Geobacter sulfurreducens confirmed the rates of Fe(III) bioreduction depend on oxide surface area rather than oxide thermodynamic properties (Roden,2003a,b;2004; Burgos et al,2003). We examined the potential for bioreduction of U(VI) by Geobacter sulfurreducens in the presence of synthetic Fe(III) oxides and natural Fe(III) oxide-containing solids (Jeon et al,2004a,b) in which more than 95% of added U(VI) was sorbed to mineral surfaces. The results showed a significant portion of solid-associated U(VI) was resistant to both enzymatic and abiotic (Fe(II)-driven) reduction, but the rate and extent of bioreduction of U(VI) was increased due to the addition of anthraquinone-2,6-disulfonate (AQDS). We conducted long-term semicontinuous culture and column experiments on coupled Fe(III) oxide/U(VI) reduction. These experiments were conducted with natural subsurface sediment from the Oyster site in Virginia, whose Fe content and microbial reducibility are comparable to ORNL FRC sediments (Jeon et al, 2004b). The results conclusively demonstrated the potential for sustained removal of U(VI) from solution via DMRB activity in excess of the U(VI) sorption capacity of the natural mineral assemblages. Jang (2004) demonstrated

  19. Cluster-Randomized Controlled Trial of an HIV/Sexually Transmitted Infection Risk-Reduction Intervention for South African Men

    PubMed Central

    Jemmott, Loretta S.; O’Leary, Ann; Ngwane, Zolani; Icard, Larry D.; Heeren, G. Anita; Mtose, Xoliswa; Carty, Craig

    2014-01-01

    Objectives. We tested the efficacy of a sexual risk-reduction intervention for men in South Africa, where heterosexual exposure is the main mode of HIV transmission. Methods. Matched-pairs of neighborhoods in Eastern Cape Province, South Africa, were randomly selected and within pairs randomized to 1 of 2 interventions based on social cognitive theory and qualitative research: HIV/sexually transmitted infection (STI) risk-reduction, targeting condom use, or attention-matched control, targeting health issues unrelated to sexual risks. Sexually active men aged 18 to 45 years were eligible. The primary outcome was consistent condom use in the past 3 months. Results. Of 1181 participants, 1106 (93.6%) completed the 12-month follow-up. HIV and STI risk-reduction participants had higher odds of reporting consistent condom use (odds ratio [OR] = 1.32; 95% confidence interval [CI] = 1.03, 1.71) and condom use at last vaginal intercourse (OR = 1.40; 95% CI = 1.08, 1.82) than did attention-control participants, adjusting for baseline prevalence. No differences were observed on unprotected intercourse or multiple partnerships. Findings did not differ for sex with steady as opposed to casual partners. Conclusions. Behavioral interventions specifically targeting men can contribute to efforts to reduce sexual risk behaviors in South Africa. PMID:24432923

  20. 27 CFR 17.4 - OMB control numbers assigned under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false OMB control numbers... ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DRAWBACK ON TAXPAID DISTILLED SPIRITS USED IN MANUFACTURING NONBEVERAGE PRODUCTS General Provisions § 17.4 OMB control numbers...

  1. 18 CFR 389.101 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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  2. 29 CFR 1926.5 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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  3. 29 CFR 1926.5 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Budget under the control number listed. 29 CFR citation OMB control No. 1926.33 1218-0065 1926.50 1218... 1926.1126 1218-0252 1926.1127 1218-0186 1926.1128 1218-0129 1926.1129 1218-0128 1926.1144...

  4. 29 CFR 1926.5 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Budget under the control number listed. 29 CFR citation OMB control No. 1926.33 1218-0065 1926.50 1218...-0095 1926.800 1218-0067 1926.803 1218-0067 1926.900 1218-0217 1926.903 1218-0227 1926.1080...

  5. 29 CFR 1926.5 - OMB control numbers under the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Budget under the control number listed. 29 CFR citation OMB control No. 1926.33 1218-0065 1926.50 1218...-0095 1926.800 1218-0067 1926.803 1218-0067 1926.900 1218-0217 1926.903 1218-0227 1926.1080...

  6. Control of oxo-group functionalization and reduction of the uranyl ion.

    PubMed

    Arnold, Polly L; Pécharman, Anne-Frédérique; Lord, Rianne M; Jones, Guy M; Hollis, Emmalina; Nichol, Gary S; Maron, Laurent; Fang, Jian; Davin, Thomas; Love, Jason B

    2015-04-01

    Uranyl complexes of a large, compartmental N8-macrocycle adopt a rigid, "Pacman" geometry that stabilizes the U(V) oxidation state and promotes chemistry at a single uranyl oxo-group. We present here new and straightforward routes to singly reduced and oxo-silylated uranyl Pacman complexes and propose mechanisms that account for the product formation, and the byproduct distributions that are formed using alternative reagents. Uranyl(VI) Pacman complexes in which one oxo-group is functionalized by a single metal cation are activated toward single-electron reduction. As such, the addition of a second equivalent of a Lewis acidic metal complex such as MgN″2 (N″ = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg functionalized as a result of Mg-N bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(N″)Cl] favor the formation of weaker U-O-Zn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxo-group.

  7. In situ surface characterization and oxygen reduction reaction on shape-controlled gold nanoparticles.

    PubMed

    Hernández, J; Solla-Gullón, J; Herrero, E; Feliu, J M; Aldaz, A

    2009-04-01

    Gold nanoparticles of different shapes/surface structures were synthesized and electrochemically characterized. An in-situ surface characterization of the Au nanoparticles, which was able to obtain qualitative information about the type and relative sizes of the different facets present in the surface of the Au nanoparticles, was carried out by using Pb Under Potential Deposition (UPD) in alkaline solutions as a surface sensitive tool. The results obtained show that the final atomic arrangement on the surface can be different from that expected from the bulk structure of the well-defined shape Au nanoparticles. In this way, the development of precise in-situ methods to measure the distribution of the different sites on the nanoparticle surface, as lead UPD on gold surfaces, is highlighted. Oxygen Reduction Reaction (ORR) was performed on the different Au nanoparticles. In agreement with the particular sensitivity of the oxygen reduction to the presence of Au(100) surface domains, cubic Au nanoparticles show much better electrocatalytic activity for ORR than small spherical particles and long nanorods, in agreement with the presence of a great fraction of (100) terrace sites on the surface of cubic gold nanoparticles. PMID:19437963

  8. HIV Sexual Risk-Reduction Interventions for Youth: A Review and Methodological Critique of Randomized Controlled Trials

    PubMed Central

    Pedlow, C. Teal; Carey, Michael P.

    2008-01-01

    We review and provide a methodological critique of randomized controlled studies of HIV risk reduction interventions that measured sexual risk behavior outcomes with adolescents. Studies conducted in school, community, and health care settings were reviewed. Overall, 13 of 23 interventions (57%) were effective in reducing sexual risk behavior. Methodological strengths of extant studies included an emphasis on a theoretical framework, evaluation of both group- and individualized intervention formats, use of multiple assessments of risk behavior including biological outcomes, and inclusion of efficacy and effectiveness trials. Methodological limitations included limited evaluation of theoretical mediators of risk reduction, failure to report effect sizes, and lack of sustained findings. Inconsistencies were found in data analytic procedures and reporting, including how nested designs, skewed data, and attrition were addressed. Recommendations for designing methodologically-rigorous interventions are provided. PMID:12705104

  9. Visual SLAM Using Variance Grid Maps

    NASA Technical Reports Server (NTRS)

    Howard, Andrew B.; Marks, Tim K.

    2011-01-01

    An algorithm denoted Gamma-SLAM performs further processing, in real time, of preprocessed digitized images acquired by a stereoscopic pair of electronic cameras aboard an off-road robotic ground vehicle to build accurate maps of the terrain and determine the location of the vehicle with respect to the maps. Part of the name of the algorithm reflects the fact that the process of building the maps and determining the location with respect to them is denoted simultaneous localization and mapping (SLAM). Most prior real-time SLAM algorithms have been limited in applicability to (1) systems equipped with scanning laser range finders as the primary sensors in (2) indoor environments (or relatively simply structured outdoor environments). The few prior vision-based SLAM algorithms have been feature-based and not suitable for real-time applications and, hence, not suitable for autonomous navigation on irregularly structured terrain. The Gamma-SLAM algorithm incorporates two key innovations: Visual odometry (in contradistinction to wheel odometry) is used to estimate the motion of the vehicle. An elevation variance map (in contradistinction to an occupancy or an elevation map) is used to represent the terrain. The Gamma-SLAM algorithm makes use of a Rao-Blackwellized particle filter (RBPF) from Bayesian estimation theory for maintaining a distribution over poses and maps. The core idea of the RBPF approach is that the SLAM problem can be factored into two parts: (1) finding the distribution over robot trajectories, and (2) finding the map conditioned on any given trajectory. The factorization involves the use of a particle filter in which each particle encodes both a possible trajectory and a map conditioned on that trajectory. The base estimate of the trajectory is derived from visual odometry, and the map conditioned on that trajectory is a Cartesian grid of elevation variances. In comparison with traditional occupancy or elevation grid maps, the grid elevation variance

  10. EGR Control for Emisson Reduction Using Fast Response Sensors - Phase 1A

    SciTech Connect

    Gravel, Roland; Conley, Jason; Kittelson, David

    2008-09-30

    The overall objective of this project was to develop exhaust gas recirculation (EGR) control strategies using fast-response Particulate Matter (PM) sensors and NOx sensors to improve the quality of particulate and gaseous emissions from diesel engines. This project initially comprised three phases: (1) Phase IA - sensor requirements to meet PM sensor specifications, NOx sensor assessment, and initial model development for EGR control; (2) Phase IB - continue development on PM and NOx sensors, integrate the sensor signals into the control simulations, and finalize model development for control strategies; and (3) Phase II - validation testing of the control strategies. Only Phase 1A was funded by DOE and executed by Honeywell. The major objectives of Phase 1A of the project included: (1) Sensor validation and operation of fast-response PM and NOx sensors; (2) Control system modeling of low-pressure EGR controls, development of control strategies, and initial evaluation of these models and strategies for EGR control in diesel engines; (3) Sensor testing to understand applicability of fast-response PM sensors in determining loading rates of the particle trap; and (4) Model validation and sensor testing under steady-state and transient operational conditions of actual engines. In particular, specific objectives included demonstration of: (1) A PM sensor response time constant (T10 - T90) of better than 100 milliseconds (msec); (2) The ability to detect PM at concentrations from 0.2 to 2 Bosch smoke number (BSN) or equivalent; (3) PM sensor accuracy to within 20% BSN over the entire range of operation; and (4) PM sensor repeatability to within 10% over the PM entire sensor range equivalent to a BSN of 0.2 to 2.

  11. Sensitivity analysis of a two-dimensional probabilistic risk assessment model using analysis of variance.

    PubMed

    Mokhtari, Amirhossein; Frey, H Christopher

    2005-12-01

    This article demonstrates application of sensitivity analysis to risk assessment models with two-dimensional probabilistic frameworks that distinguish between variability and uncertainty. A microbial food safety process risk (MFSPR) model is used as a test bed. The process of identifying key controllable inputs and key sources of uncertainty using sensitivity analysis is challenged by typical characteristics of MFSPR models such as nonlinearity, thresholds, interactions, and categorical inputs. Among many available sensitivity analysis methods, analysis of variance (ANOVA) is evaluated in comparison to commonly used methods based on correlation coefficients. In a two-dimensional risk model, the identification of key controllable inputs that can be prioritized with respect to risk management is confounded by uncertainty. However, as shown here, ANOVA provided robust insights regarding controllable inputs most likely to lead to effective risk reduction despite uncertainty. ANOVA appropriately selected the top six important inputs, while correlation-based methods provided misleading insights. Bootstrap simulation is used to quantify uncertainty in ranks of inputs due to sampling error. For the selected sample size, differences in F values of 60% or more were associated with clear differences in rank order between inputs. Sensitivity analysis results identified inputs related to the storage of ground beef servings at home as the most important. Risk management recommendations are suggested in the form of a consumer advisory for better handling and storage practices.

  12. The moderation of Mindfulness-based stress reduction effects by trait mindfulness: results from a randomized controlled trial.

    PubMed

    Shapiro, Shauna L; Brown, Kirk Warren; Thoresen, Carl; Plante, Thomas G

    2011-03-01

    Mindfulness-based stress reduction (MBSR) has shown effectiveness for a variety of mental health conditions. However, it is not known for whom the intervention is most effective. In a randomized controlled trial (N = 30), we explored whether individuals with higher levels of pretreatment trait mindfulness would benefit more from MBSR intervention. Results demonstrated that relative to a control condition (n = 15), MBSR treatment (n = 15) had significant effects on several outcomes, including increased trait mindfulness, subjective well-being, and empathy measured at 2 and 12 months after treatment. However, relative to controls, MBSR participants with higher levels of pretreatment mindfulness showed a larger increase in mindfulness, subjective well-being, empathy, and hope, and larger declines in perceived stress up to 1 year after treatment.

  13. A theoretical study of the application of jet flap circulation control for reduction of rotor vibratory forces

    NASA Technical Reports Server (NTRS)

    Piziali, R. A.; Trenka, A. R.

    1974-01-01

    The results of a study to investigate the theoretical potential of a jet-flap control system for reducing the vertical and horizontal non-cancelling helicopter rotor blade root shears are presented. A computer simulation describing the jet-flap control rotor system was developed to examine the reduction of each harmonic of the transmitted shears as a function of various rotor and jet parameters, rotor operating conditions and rotor configurations. The computer simulation of the air-loads included the influences of nonuniform inflow and blade elastic motions. (no hub motions were allowed.) The rotor trim and total rotor power (including jet compressor power) were also determined. It was found that all harmonics of the transmitted horizontal and vertical shears could be suppressed simultaneously using a single jet control.

  14. Reduction of Switching Surge by Controlled Shunt Reactor Switching of Gas Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Kohyama, Haruhiko; Ito, Hiroki; Asai, Jun; Hidaka, Mikio; Yonezawa, Takashi

    Controlled switching system (CSS) with a 204kV gas circuit breaker (GCB) demonstrates to reduce an inrush current and to eliminate re-ignitions in shunt reactor switching. Target closing and opening instants for controlled switching are determined by the electrical and mechanical characteristics of GCB. Idle time dependence of the operating time, which gives a sufficient impact on controlling accuracy, is evaluated and successfully compensated by synchronous switching controller (SSC). Field operation of CSS for a year shows an effective suppression of inrush current on closing and prevention of re-ignitions on opening of shunt reactor. The operations also proved that the CSS has a satisfactory performance for electro-magnetic disturbance imposed in practical field.

  15. 7 CFR 62.400 - OMB control number assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION ACT (CONTINUED) LIVESTOCK, MEAT, AND OTHER AGRICULTURAL COMMODITIES (QUALITY SYSTEMS VERIFICATION PROGRAMS) Quality Systems Verification Programs Definitions Miscellaneous § 62.400 OMB control number...) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF...

  16. 46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to... agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  17. 46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to... agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  18. 46 CFR 107.05 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.05 OMB control numbers assigned... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  19. 46 CFR 107.05 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.05 OMB control numbers assigned... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  20. 46 CFR 107.05 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.05 OMB control numbers assigned... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  1. 46 CFR 107.05 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.05 OMB control numbers assigned... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  2. 46 CFR 107.05 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.05 OMB control numbers assigned... approved agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  3. 46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to... agency information collection requirement. (b) Display. 46 CFR part or section where identified...

  4. 46 CFR 150.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or sectionwhere identified or...) CERTAIN BULK DANGEROUS CARGOES COMPATIBILITY OF CARGOES § 150.105 OMB control numbers assigned pursuant...

  5. 46 CFR 150.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or section where identified or...) CERTAIN BULK DANGEROUS CARGOES COMPATIBILITY OF CARGOES § 150.105 OMB control numbers assigned pursuant...

  6. 46 CFR 150.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or section where identified or...) CERTAIN BULK DANGEROUS CARGOES COMPATIBILITY OF CARGOES § 150.105 OMB control numbers assigned pursuant...

  7. 46 CFR 150.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or sectionwhere identified or...) CERTAIN BULK DANGEROUS CARGOES COMPATIBILITY OF CARGOES § 150.105 OMB control numbers assigned pursuant...

  8. 46 CFR 150.105 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or sectionwhere identified or...) CERTAIN BULK DANGEROUS CARGOES COMPATIBILITY OF CARGOES § 150.105 OMB control numbers assigned pursuant...

  9. 46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or section where identified or...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant...

  10. 46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... agency information collection requirement. (b) Display. 46 CFR part or section where identified or...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant...

  11. Living with a large reduction in permited loading by using a hydrograph-controlled release scheme

    USGS Publications Warehouse

    Conrads, P.A.; Martello, W.P.; Sullins, N.R.

    2003-01-01

    The Total Maximum Daily Load (TMDL) for ammonia and biochemical oxygen demand for the Pee Dee, Waccamaw, and Atlantic Intracoastal Waterway system near Myrtle Beach, South Carolina, mandated a 60-percent reduction in point-source loading. For waters with a naturally low background dissolved-oxygen concentrations, South Carolina anti-degradation rules in the water-quality regulations allows a permitted discharger a reduction of dissolved oxygen of 0.1 milligrams per liter (mg/L). This is known as the "0.1 rule." Permitted dischargers within this region of the State operate under the "0.1 rule" and cannot cause a cumulative impact greater than 0.1 mg/L on dissolved-oxygen concentrations. For municipal water-reclamation facilities to serve the rapidly growing resort and retirement community near Myrtle Beach, a variable loading scheme was developed to allow dischargers to utilize increased assimilative capacity during higher streamflow conditions while still meeting the requirements of a recently established TMDL. As part of the TMDL development, an extensive real-time data-collection network was established in the lower Waccamaw and Pee Dee River watershed where continuous measurements of streamflow, water level, dissolved oxygen, temperature, and specific conductance are collected. In addition, the dynamic BRANCH/BLTM models were calibrated and validated to simulate the water quality and tidal dynamics of the system. The assimilative capacities for various streamflows were also analyzed. The variable-loading scheme established total loadings for three streamflow levels. Model simulations show the results from the additional loading to be less than a 0.1 mg/L reduction in dissolved oxygen. As part of the loading scheme, the real-time network was redesigned to monitor streamflow entering the study area and water-quality conditions in the location of dissolved-oxygen "sags." The study reveals how one group of permit holders used a variable-loading scheme to implement

  12. FMRI group analysis combining effect estimates and their variances

    PubMed Central

    Chen, Gang; Saad, Ziad S.; Nath, Audrey R.; Beauchamp, Michael S.; Cox, Robert W.

    2012-01-01

    Conventional functional magnetic resonance imaging (FMRI) group analysis makes two key assumptions that are not always justified. First, the data from each subject is condensed into a single number per voxel, under the assumption that within-subject variance for the effect of interest is the same across all subjects or is negligible relative to the cross-subject variance. Second, it is assumed that all data values are drawn from the same Gaussian distribution with no outliers. We propose an approach that does not make such strong assumptions, and present a computationally efficient frequentist approach to FMRI group analysis, which we term mixed-effects multilevel analysis (MEMA), that incorporates both the variability across subjects and the precision estimate of each effect of interest from individual subject analyses. On average, the more accurate tests result in higher statistical power, especially when conventional variance assumptions do not hold, or in the presence of outliers. In addition, various heterogeneity measures are available with MEMA that may assist the investigator in further improving the modeling. Our method allows group effect t-tests and comparisons among conditions and among groups. In addition, it has the capability to incorporate subject-specific covariates such as age, IQ, or behavioral data. Simulations were performed to illustrate power comparisons and the capability of controlling type I errors among various significance testing methods, and the results indicated that the testing statistic we adopted struck a good balance between power gain and type I error control. Our approach is instantiated in an open-source, freely distributed program that may be used on any dataset stored in the universal neuroimaging file transfer (NIfTI) format. To date, the main impediment for more accurate testing that incorporates both within- and cross-subject variability has been the high computational cost. Our efficient implementation makes this approach

  13. Evidence-based control of canine rabies: a critical review of population density reduction.

    PubMed

    Morters, Michelle K; Restif, Olivier; Hampson, Katie; Cleaveland, Sarah; Wood, James L N; Conlan, Andrew J K

    2013-01-01

    Control measures for canine rabies include vaccination and reducing population density through culling or sterilization. Despite the evidence that culling fails to control canine rabies, efforts to reduce canine population density continue in many parts of the world. The rationale for reducing population density is that rabies transmission is density-dependent, with disease incidence increasing directly with host density. This may be based, in part, on an incomplete interpretation of historical field data for wildlife, with important implications for disease control in dog populations. Here, we examine historical and more recent field data, in the context of host ecology and epidemic theory, to understand better the role of density in rabies transmission and the reasons why culling fails to control rabies. We conclude that the relationship between host density, disease incidence and other factors is complex and may differ between species. This highlights the difficulties of interpreting field data and the constraints of extrapolations between species, particularly in terms of control policies. We also propose that the complex interactions between dogs and people may render culling of free-roaming dogs ineffective irrespective of the relationship between host density and disease incidence. We conclude that vaccination is the most effective means to control rabies in all species.

  14. Estimated Reduction in Cancer Risk due to PAH Exposures If Source Control Measures during the 2008 Beijing Olympics Were Sustained

    PubMed Central

    Jia, Yuling; Stone, Dave; Wang, Wentao; Schrlau, Jill; Tao, Shu; Massey Simonich, Staci L.

    2011-01-01

    Background The 2008 Beijing Olympic Games provided a unique case study to investigate the effect of source control measures on the reduction in air pollution, and associated inhalation cancer risk, in a Chinese megacity. Objectives We measured 17 carcinogenic polycyclic aromatic hydrocarbons (PAHs) and estimated the lifetime excess inhalation cancer risk during different periods of the Beijing Olympic Games, to assess the effectiveness of source control measures in reducing PAH-induced inhalation cancer risks. Methods PAH concentrations were measured in samples of particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) collected during the Beijing Olympic Games, and the associated inhalation cancer risks were estimated using a point-estimate approach based on relative potency factors. Results We estimated the number of lifetime excess cancer cases due to exposure to the 17 carcinogenic PAHs [12 priority pollutant PAHs and five high-molecular-weight (302 Da) PAHs (MW 302 PAHs)] to range from 6.5 to 518 per million people for the source control period concentrations and from 12.2 to 964 per million people for the nonsource control period concentrations. This would correspond to a 46% reduction in estimated inhalation cancer risk due to source control measures, if these measures were sustained over time. Benzo[b]fluoranthene, dibenz[a,h]anthracene, benzo[a]pyrene, and dibenzo[a,l]pyrene were the most carcinogenic PAH species evaluated. Total excess inhalation cancer risk would be underestimated by 23% if we did not include the five MW 302 PAHs in the risk calculation. Conclusions Source control measures, such as those imposed during the 2008 Beijing Olympics, can significantly reduce the inhalation cancer risk associated with PAH exposure in Chinese megacities similar to Beijing. MW 302 PAHs are a significant contributor to the estimated overall inhalation cancer risk. PMID:21632310

  15. Thermal Noise Reduction of Mechanical Oscillators by Actively Controlled External Dissipative Forces

    NASA Technical Reports Server (NTRS)

    Liang, Shoudan; Medich, David; Czajkowsky, Daniel M.; Sheng, Sitong; Yuan, Jian-Yang; Shao, Zhifeng

    1999-01-01

    We show that the thermal fluctuations of very soft mechanical oscillators, such as the cantilever in an atomic force microscope (AFM), can be reduced without changing the stiffness of the spring or having to lower the environment temperature. We derive a theoretical relationship between the thermal fluctuations of an oscillator and an actively external-dissipative force. This relationship is verified by experiments with an AFM cantilever where the external active force is coupled through a magnetic field. With simple instrumentation, we have reduced the thermal noise amplitude of the cantilever by a factor of 3.4, achieving an apparent temperature of 25 K with the environment at 295K. This active noise reduction approach can significantly improve the accuracy of static position or static force measurements in a number of practical applications.

  16. Peripheral nervous control of cold-induced reduction in the respiratory quotient of the rat

    NASA Astrophysics Data System (ADS)

    Refinetti, Roberto

    1990-03-01

    Cold-exposed rats show a reduction in the respiratory quotient which is indicative of a relative shift from carbohydrates to lipids as substrates for oxidative metabolism. In the present study, the effects of food deprivation and cold exposure on the respiratory quotient were observed. In addition, the involvement of the three main branches of the peripheral nervous system (sympathetic, parasympathetic, and somatic) was investigated by means of synaptic blockade with propranolol, atropine, and quinine, respectively. Both propranolol and quinine blocked the cold-induced decrease in respiratory quotient and increase in heat production, whereas atropine had only minor and very brief effects. It is concluded that both the sympathetic and somatic branches are involved in the metabolic changes associated with cold-induced thermogenesis and that the increase in metabolic heat production involves a shift from carbohydrate to lipid utilization irrespective of which of the two branches is activated.

  17. On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

    NASA Astrophysics Data System (ADS)

    Pusede, S. E.; Duffey, K. C.; Shusterman, A. A.; Saleh, A.; Laughner, J. L.; Wooldridge, P. J.; Zhang, Q.; Parworth, C. L.; Kim, H.; Capps, S. L.; Valin, L. C.; Cappa, C. D.; Fried, A.; Walega, J.; Nowak, J. B.; Weinheimer, A. J.; Hoff, R. M.; Berkoff, T. A.; Beyersdorf, A. J.; Olson, J.; Crawford, J. H.; Cohen, R. C.

    2016-03-01

    Nitrogen oxides (NOx) have fallen steadily across the US over the last 15 years. At the same time, NOx concentrations decrease on weekends relative to weekdays, largely without co-occurring changes in other gas-phase emissions, due to patterns of diesel truck activities. These trends taken together provide two independent constraints on the role of NOx in the nonlinear chemistry of atmospheric oxidation. In this context, we interpret interannual trends in wintertime ammonium nitrate (NH4NO3) in the San Joaquin Valley of California, a location with the worst aerosol pollution in the US and where a large portion of aerosol mass is NH4NO3. Here, we show that NOx reductions have simultaneously decreased nighttime and increased daytime NH4NO3 production over the last decade. We find a substantial decrease in NH4NO3 since 2000 and conclude that this decrease is due to reduced nitrate radical-initiated production at night in residual layers that are decoupled from fresh emissions at the surface. Further reductions in NOx are imminent in California, and nationwide, and we make a quantitative prediction of the response of NH4NO3. We show that the combination of rapid chemical production and efficient NH4NO3 loss via deposition of gas-phase nitric acid implies that high aerosol days in cities in the San Joaquin Valley air basin are responsive to local changes in NOx within those individual cities. Our calculations indicate that large decreases in NOx in the future will not only lower wintertime NH4NO3 concentrations but also cause a transition in the dominant NH4NO3 source from nighttime to daytime chemistry.

  18. Geochemical signatures of thermochemical sulfate reduction in controlled hydrous pyrolysis experiments

    USGS Publications Warehouse

    Zhang, T.; Ellis, G.S.; Walters, C.C.; Kelemen, S.R.; Wang, K.-s.; Tang, Y.

    2008-01-01

    A series of gold tube hydrous pyrolysis experiments was conducted in order to investigate the effect of thermochemical sulfate reduction (TSR) on gas generation, residual saturated hydrocarbon compositional alteration, and solid pyrobitumen formation. The intensity of TSR significantly depends on the H2O/MgSO4 mole ratio, the smaller the ratio, the stronger the oxidizing conditions. Under highly oxidizing conditions (MgSO4/hydrocarbon wt/wt 20/1 and hydrocarbon/H2O wt/wt 1/1), large amounts of H2S and CO2 are generated indicating that hydrocarbon oxidation coupled with sulfate reduction is the dominant reaction. Starting with a mixture of C21-C35 n-alkanes, these hydrocarbons are consumed totally at temperatures below the onset of hydrocarbon thermal cracking in the absence of TSR (400 ??C). Moreover, once the longer chain length hydrocarbons are oxidized, secondarily formed hydrocarbons, even methane, are oxidized to CO2. Using whole crude oils as the starting reactants, the TSR reaction dramatically lowers the stability of hydrocarbons leading to increases in gas dryness and gas/oil ratio. While their concentrations decrease, the relative distributions of n-alkanes do not change appreciably from the original composition, and consequently, are non-diagnostic for TSR. However, distinct molecular changes related to TSR are observed, Pr/n-C17 and Ph/n-C18 ratios decrease at a faster rate under TSR compared to thermal chemical alteration (TCA) alone. TSR promotes aromatization and the incorporation of sulfur and oxygen into hydrocarbons leading to a decrease in the saturate to aromatic ratio in the residual oil and in the generation of sulfur and oxygen rich pyrobitumen. These experimental findings could provide useful geochemical signatures to identify TSR in settings where TSR has occurred in natural systems. ?? 2008 Elsevier Ltd. All rights reserved.

  19. Effects of auricular acupressure on weight reduction and abdominal obesity in Asian young adults: a randomized controlled trial.

    PubMed

    Hsieh, Ching Hsiu; Su, Tsann-Jnn; Fang, Yu-Wen; Chou, Pei-Hsuan

    2011-01-01

    The current study was designed to test the efficacy of auricular acupressure on weight reduction and changes of waist circumference and waist-to-hip ratio. This study used a randomized design with one control group and one experimental group consisting of Asian young adults with a waist circumference ≥80 cm in the females and ≥90cm in the males. At completion of eight weeks of auricular therapy, the total sample size was 55 young adults who ranged in age from 18 to 20 years old. Each participant was treated weekly for ear acupressure in ten-minute sessions. Sessions continued for eight weeks wherein the control group received acupressure only while the experimental group received acupressure with the Japanese Magnetic Pearl on the ear acupoints. While both the control and treatment groups showed significant reduction (p ≤ 0.05) to body weight and waist circumference after eight weeks of treatment, only the group treated with Japanese Magnetic Pearls showed decreased waist to hip ratio. Thus, auricular acupressure may be a beneficial addition to weight loss programs for young adults. Auricular acupressure is thus a reasonable option in the treatment of overweight and obesity in young adults. PMID:21598412

  20. Reduction of aerodynamic load fluctuation on wind turbine blades through active flow control

    NASA Astrophysics Data System (ADS)

    Velarde, John-Michael; Coleman, Thomas; Magstadt, Andrew; Aggarwal, Somil; Glauser, Mark

    2015-11-01

    The current set of experiments deals with implementing active flow control on a Bergey Excel 1, 1kW turbine. The previous work in our group demonstrated successfully that implementation of a simple closed-loop controller could reduce unsteady aerodynamic load fluctuation by 18% on a vertically mounted wing. Here we describe a similar flow control method adapted to work in the rotating frame of a 2.5m diameter wind turbine. Strain gages at the base of each blade measure the unsteady fluctuation in the blades and pressure taps distributed along the span of the blades feed information to the closed-loop control scheme. A realistic, unsteady flow field has been generated by placing a cylinder upstream of the turbine to induce shedding vortices at frequencies in the bandwidth of the first structural bending mode of the turbine blades. The goal of these experiments is to demonstrate closed-loop flow control as a means to reduce the unsteady fluctuation in the blades and increase the overall lifespan of the wind turbine.

  1. Graphite anode surface modification with controlled reduction of specific aryl diazonium salts for improved microbial fuel cells power output.

    PubMed

    Picot, Matthieu; Lapinsonnière, Laure; Rothballer, Michael; Barrière, Frédéric

    2011-10-15

    Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for

  2. Comparing State-Space Multivariable Controls to Multi-SISO Controls for Load Reduction of Drivetrain-Coupled Modes on Wind Turbines through Field-Testing: Preprint

    SciTech Connect

    Fleming, P. A.; van Wingerden, J. W.; Wright, A. D.

    2011-12-01

    This paper presents the structure of an ongoing controller comparison experiment at NREL's National Wind Technology Center; the design process for the two controllers compared in this phase of the experiment, and initial comparison results obtained in field-testing. The intention of the study is to demonstrate the advantage of using modern multivariable methods for designing control systems for wind turbines versus conventional approaches. We will demonstrate the advantages through field-test results from experimental turbines located at the NWTC. At least two controllers are being developed side-by-side to meet an incrementally increasing number of turbine load-reduction objectives. The first, a multiple single-input, single-output (m-SISO) approach, uses separately developed decoupled and classicially tuned controllers, which is, to the best of our knowledge, common practice in the wind industry. The remaining controllers are developed using state-space multiple-input and multiple-output (MIMO) techniques to explicity account for coupling between loops and to optimize given known frequency structures of the turbine and disturbance. In this first publication from the study, we present the structure of the ongoing controller comparison experiment, the design process for the two controllers compared in this phase, and initial comparison results obtained in field-testing.

  3. Remote electronic control in the regioselective reduction of succinimides: a practical, scalable synthesis of Ep4 antagonist MF-310.

    PubMed

    Molinaro, Carmela; Gauvreau, Danny; Hughes, Gregory; Lau, Stephen; Lauzon, Sophie; Angelaud, Rémy; O'Shea, Paul D; Janey, Jacob; Palucki, Michael; Hoerrner, Scott R; Raab, Conrad E; Sidler, Rick R; Belley, Michel; Han, Yongxin

    2009-09-01

    A practical large-scale chromatography-free synthesis of EP4 antagonist MF-310, a potential new treatment for chronic inflammation, is presented. The synthetic route provided MF-310 as its sodium salt in 10 steps and 17% overall yield from commercially available pyridine dicarboxylate 7. The key features of this sequence include a unique regioselective reduction of succinimide 2 controlled by the electronic properties of a remote pyridine ring, preparation of cyclopropane carboxylic acid 3 via a Corey-Chaykovsky cyclopropanation, and a short synthesis of sulfonamide 5.

  4. Reduction of magnetic field fluctuations in powered magnets for NMR using inductive measurements and sampled-data feedback control.

    PubMed

    Li, Mingzhou; Schiano, Jeffrey L; Samra, Jenna E; Shetty, Kiran K; Brey, William W

    2011-10-01

    Resistive and hybrid (resistive/superconducting) magnets provide substantially higher magnetic fields than those available in low-temperature superconducting magnets, but their relatively low spatial homogeneity and temporal field fluctuations are unacceptable for high resolution NMR. While several techniques for reducing temporal fluctuations have demonstrated varying degrees of success, this paper restricts attention to methods that utilize inductive measurements and feedback control to actively cancel the temporal fluctuations. In comparison to earlier studies using analog proportional control, this paper shows that shaping the controller frequency response results in significantly higher reductions in temporal fluctuations. Measurements of temporal fluctuation spectra and the frequency response of the instrumentation that cancels the temporal fluctuations guide the controller design. In particular, we describe a sampled-data phase-lead-lag controller that utilizes the internal model principle to selectively attenuate magnetic field fluctuations caused by the power supply ripple. We present a quantitative comparison of the attenuation in temporal fluctuations afforded by the new design and a proportional control design. Metrics for comparison include measurements of the temporal fluctuations using Faraday induction and observations of the effect that the fluctuations have on nuclear resonance measurements.

  5. Argentine Population Genetic Structure: Large Variance in Amerindian Contribution

    PubMed Central

    Seldin, Michael F.; Tian, Chao; Shigeta, Russell; Scherbarth, Hugo R.; Silva, Gabriel; Belmont, John W.; Kittles, Rick; Gamron, Susana; Allevi, Alberto; Palatnik, Simon A.; Alvarellos, Alejandro; Paira, Sergio; Caprarulo, Cesar; Guillerón, Carolina; Catoggio, Luis J.; Prigione, Cristina; Berbotto, Guillermo A.; García, Mercedes A.; Perandones, Carlos E.; Pons-Estel, Bernardo A.; Alarcon-Riquelme, Marta E.

    2011-01-01

    Argentine population genetic structure was examined using a set of 78 ancestry informative markers (AIMs) to assess the contributions of European, Amerindian, and African ancestry in 94 individuals members of this population. Using the Bayesian clustering algorithm STRUCTURE, the mean European contribution was 78%, the Amerindian contribution was 19.4%, and the African contribution was 2.5%. Similar results were found using weighted least mean square method: European, 80.2%; Amerindian, 18.1%; and African, 1.7%. Consistent with previous studies the current results showed very few individuals (four of 94) with greater than 10% African admixture. Notably, when individual admixture was examined, the Amerindian and European admixture showed a very large variance and individual Amerindian contribution ranged from 1.5 to 84.5% in the 94 individual Argentine subjects. These results indicate that admixture must be considered when clinical epidemiology or case control genetic analyses are studied in this population. Moreover, the current study provides a set of informative SNPs that can be used to ascertain or control for this potentially hidden stratification. In addition, the large variance in admixture proportions in individual Argentine subjects shown by this study suggests that this population is appropriate for future admixture mapping studies. PMID:17177183

  6. Stimulant Reduction Intervention using Dosed Exercise (STRIDE) - CTN 0037: Study protocol for a randomized controlled trial

    PubMed Central

    2011-01-01

    Background There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study. Methods/Design STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI) or Health Education Intervention Augmentation (HEI). Both groups will receive TAU (i.e., usual care). The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual) sessions, although other

  7. Feedback Control of a Morphing Chevron for Takeoff and Cruise Noise Reduction

    NASA Technical Reports Server (NTRS)

    Cabell, Randolph H.; Schiller, Noah H.; Mabe, James H.; Ruggeri, Robert T.; Butler, G. W.

    2004-01-01

    Noise from commercial high-bypass ratio turbofan engines is generated by turbulent mixing of the hot jet exhaust, fan stream, and ambient air. Serrated aerodynamic devices, known as chevrons, along the trailing edges of a jet engine primary and secondary exhaust nozzle have been shown to reduce jet noise at takeoff and shock-cell noise at cruise conditions. Their optimum shape is a finely tuned compromise between noise-benefit and thrust-loss. The design of a full scale Variable Geometry Chevron (VGC) fan-nozzle incorporating Shape Memory Alloy (SMA) actuators is described in a companion paper. This paper describes the development and testing of a proportional-integral control system that regulates the heating of the SMA actuators to control the VGC s tip immersion. The VGC and control system were tested under representative flow conditions in Boeing s Nozzle Test Facility (NTF). Results from the NTF test which demonstrate controllable immersion of the VGC are described. The paper also describes the correlation between strains and temperatures on the chevron with a photogrammetric measurement of the chevron's tip immersion.

  8. 15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... requirement. (b) Display. CFR part or section where the information collection requirement is located Current OMB control number (all numbers begin with 0648-) 15 CFR Part 908 -0025 Part 911 -0157 917.11 -0008....9 -0141 Part 960, subpart B -0174 Part 970 -0145 Part 971 -0170 Part 981 -0144 50 CFR 216.22...

  9. 15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... requirement. (b) Display. CFR part or section where the information collection requirement is located Current OMB control number (all numbers begin with 0648-) 15 CFR Part 908 -0025 Part 911 -0157 917.11 -0008....9 -0141 Part 960, subpart B -0174 Part 970 -0145 Part 971 -0170 Part 981 -0144 50 CFR 216.22...

  10. 15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... requirement. (b) Display. CFR part or section where the information collection requirement is located Current OMB control number (all numbers begin with 0648-) 15 CFR Part 908 -0025 Part 911 -0157 917.11 -0008....9 -0141 Part 960, subpart B -0174 Part 970 -0145 Part 971 -0170 Part 981 -0144 50 CFR 216.22...

  11. 15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... requirement. (b) Display. CFR part or section where the information collection requirement is located Current OMB control number (all numbers begin with 0648-) 15 CFR Part 908 -0025 Part 911 -0157 917.11 -0008....9 -0141 Part 960, subpart B -0174 Part 970 -0145 Part 971 -0170 Part 981 -0144 50 CFR 216.22...

  12. 15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... requirement. (b) Display. CFR part or section where the information collection requirement is located Current OMB control number (all numbers begin with 0648-) 15 CFR Part 908 -0025 Part 911 -0157 917.11 -0008....9 -0141 Part 960, subpart B -0174 Part 970 -0145 Part 971 -0170 Part 981 -0144 50 CFR 216.22...

  13. Dimensionality Reduction in Controlling Articulated Snake Robot for Endoscopy Under Dynamic Active Constraints

    PubMed Central

    Kwok, Ka-Wai; Tsoi, Kuen Hung; Vitiello, Valentina; Clark, James; Chow, Gary C. T.; Luk, Wayne; Yang, Guang-Zhong

    2014-01-01

    This paper presents a real-time control framework for a snake robot with hyper-kinematic redundancy under dynamic active constraints for minimally invasive surgery. A proximity query (PQ) formulation is proposed to compute the deviation of the robot motion from predefined anatomical constraints. The proposed method is generic and can be applied to any snake robot represented as a set of control vertices. The proposed PQ formulation is implemented on a graphic processing unit, allowing for fast updates over 1 kHz. We also demonstrate that the robot joint space can be characterized into lower dimensional space for smooth articulation. A novel motion parameterization scheme in polar coordinates is proposed to describe the transition of motion, thus allowing for direct manual control of the robot using standard interface devices with limited degrees of freedom. Under the proposed framework, the correct alignment between the visual and motor axes is ensured, and haptic guidance is provided to prevent excessive force applied to the tissue by the robot body. A resistance force is further incorporated to enhance smooth pursuit movement matched to the dynamic response and actuation limit of the robot. To demonstrate the practical value of the proposed platform with enhanced ergonomic control, detailed quantitative performance evaluation was conducted on a group of subjects performing simulated intraluminal and intracavity endoscopic tasks. PMID:24741371

  14. Solution of one problem of control connected with the reduction of iron-ore pellets

    SciTech Connect

    Glasko, V.B.; Kulagin, I.D.; Matytsyn, A.P.; Trubetskov, M.K.

    1985-06-01

    The article examines the mathematical model of the process of heating iron-ore pellets, and a gas blown through them, by high-frequency currents. On the basis of the solution of the problem of control it becomes possible to evaluate the efficiency of the heater and to choose the optimum operating conditions for it.

  15. 7 CFR 1000.93 - OMB control number assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE GENERAL PROVISIONS OF FEDERAL MILK MARKETING ORDERS Miscellaneous Provisions § 1000.93 OMB control number assigned... have been approved by the Office of Management and Budget (OMB) under the provisions of Title 44...

  16. 7 CFR 1000.93 - OMB control number assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE GENERAL PROVISIONS OF FEDERAL MILK MARKETING ORDERS Miscellaneous Provisions § 1000.93 OMB control number assigned... have been approved by the Office of Management and Budget (OMB) under the provisions of Title 44...

  17. 7 CFR 1000.93 - OMB control number assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE GENERAL PROVISIONS OF FEDERAL MILK MARKETING ORDERS Miscellaneous Provisions § 1000.93 OMB control number assigned... have been approved by the Office of Management and Budget (OMB) under the provisions of Title 44...

  18. 7 CFR 1000.93 - OMB control number assigned pursuant to the Paperwork Reduction Act.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE GENERAL PROVISIONS OF FEDERAL MILK MARKETING ORDERS Miscellaneous Provisions § 1000.93 OMB control number assigned... have been approved by the Office of Management and Budget (OMB) under the provisions of Title 44...

  19. Dimensionality Reduction in Controlling Articulated Snake Robot for Endoscopy Under Dynamic Active Constraints.

    PubMed

    Kwok, Ka-Wai; Tsoi, Kuen Hung; Vitiello, Valentina; Clark, James; Chow, Gary C T; Luk, Wayne; Yang, Guang-Zhong

    2013-02-01

    This paper presents a real-time control framework for a snake robot with hyper-kinematic redundancy under dynamic active constraints for minimally invasive surgery. A proximity query (PQ) formulation is proposed to compute the deviation of the robot motion from predefined anatomical constraints. The proposed method is generic and can be applied to any snake robot represented as a set of control vertices. The proposed PQ formulation is implemented on a graphic processing unit, allowing for fast updates over 1 kHz. We also demonstrate that the robot joint space can be characterized into lower dimensional space for smooth articulation. A novel motion parameterization scheme in polar coordinates is proposed to describe the transition of motion, thus allowing for direct manual control of the robot using standard interface devices with limited degrees of freedom. Under the proposed framework, the correct alignment between the visual and motor axes is ensured, and haptic guidance is provided to prevent excessive force applied to the tissue by the robot body. A resistance force is further incorporated to enhance smooth pursuit movement matched to the dynamic response and actuation limit of the robot. To demonstrate the practical value of the proposed platform with enhanced ergonomic control, detailed quantitative performance evaluation was conducted on a group of subjects performing simulated intraluminal and intracavity endoscopic tasks.

  20. Multi-objective Extremum Seeking Control for Enhancement of Wind Turbine Power Capture with Load Reduction

    NASA Astrophysics Data System (ADS)

    Xiao, Yan; Li, Yaoyu; Rotea, Mario A.

    2016-09-01

    The primary objective in below rated wind speed (Region 2) is to maximize the turbine's energy capture. Due to uncertainty, variability of turbine characteristics and lack of inexpensive but precise wind measurements, model-free control strategies that do not use wind measurements such as Extremum Seeking Control (ESC) have received significant attention. Based on a dither-demodulation scheme, ESC can maximize the wind power capture in real time despite uncertainty, variabilities and lack of accurate wind measurements. The existing work on ESC based wind turbine control focuses on power capture only. In this paper, a multi-objective extremum seeking control strategy is proposed to achieve nearly optimum wind energy capture while decreasing structural fatigue loads. The performance index of the ESC combines the rotor power and penalty terms of the standard deviations of selected fatigue load variables. Simulation studies of the proposed multi-objective ESC demonstrate that the damage-equivalent loads of tower and/or blade loads can be reduced with slight compromise in energy capture.