Monte Carlo variance reduction
NASA Technical Reports Server (NTRS)
Byrn, N. R.
1980-01-01
Computer program incorporates technique that reduces variance of forward Monte Carlo method for given amount of computer time in determining radiation environment in complex organic and inorganic systems exposed to significant amounts of radiation.
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.
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.
Variance Reduction for a Discrete Velocity Gas
NASA Astrophysics Data System (ADS)
Morris, A. B.; Varghese, P. L.; Goldstein, D. B.
2011-05-01
We extend a variance reduction technique developed by Baker and Hadjiconstantinou [1] to a discrete velocity gas. In our previous work, the collision integral was evaluated by importance sampling of collision partners [2]. Significant computational effort may be wasted by evaluating the collision integral in regions where the flow is in equilibrium. In the current approach, substantial computational savings are obtained by only solving for the deviations from equilibrium. In the near continuum regime, the deviations from equilibrium are small and low noise evaluation of the collision integral can be achieved with very coarse statistical sampling. Spatially homogenous relaxation of the Bobylev-Krook-Wu distribution [3,4], was used as a test case to verify that the method predicts the correct evolution of a highly non-equilibrium distribution to equilibrium. When variance reduction is not used, the noise causes the entropy to undershoot, but the method with variance reduction matches the analytic curve for the same number of collisions. We then extend the work to travelling shock waves and compare the accuracy and computational savings of the variance reduction method to DSMC over Mach numbers ranging from 1.2 to 10.
Variance Reduction Using Nonreversible Langevin Samplers
NASA Astrophysics Data System (ADS)
Duncan, A. B.; Lelièvre, T.; Pavliotis, G. A.
2016-05-01
A standard approach to computing expectations with respect to a given target measure is to introduce an overdamped Langevin equation which is reversible with respect to the target distribution, and to approximate the expectation by a time-averaging estimator. As has been noted in recent papers [30, 37, 61, 72], introducing an appropriately chosen nonreversible component to the dynamics is beneficial, both in terms of reducing the asymptotic variance and of speeding up convergence to the target distribution. In this paper we present a detailed study of the dependence of the asymptotic variance on the deviation from reversibility. Our theoretical findings are supported by numerical simulations.
Some variance reduction methods for numerical stochastic homogenization.
Blanc, X; Le Bris, C; Legoll, F
2016-04-28
We give an overview of a series of recent studies devoted to variance reduction techniques for numerical stochastic homogenization. Numerical homogenization requires that a set of problems is solved at the microscale, the so-called corrector problems. In a random environment, these problems are stochastic and therefore need to be repeatedly solved, for several configurations of the medium considered. An empirical average over all configurations is then performed using the Monte Carlo approach, so as to approximate the effective coefficients necessary to determine the macroscopic behaviour. Variance severely affects the accuracy and the cost of such computations. Variance reduction approaches, borrowed from other contexts in the engineering sciences, can be useful. Some of these variance reduction techniques are presented, studied and tested here. PMID:27002065
A multicomb variance reduction scheme for Monte Carlo semiconductor simulators
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.
Monte Carlo variance reduction approaches for non-Boltzmann tallies
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.
Automated variance reduction for Monte Carlo shielding analyses with MCNP
NASA Astrophysics Data System (ADS)
Radulescu, Georgeta
Variance reduction techniques are employed in Monte Carlo analyses to increase the number of particles in the space phase of interest and thereby lower the variance of statistical estimation. Variance reduction parameters are required to perform Monte Carlo calculations. It is well known that adjoint solutions, even approximate ones, are excellent biasing functions that can significantly increase the efficiency of a Monte Carlo calculation. In this study, an automated method of generating Monte Carlo variance reduction parameters, and of implementing the source energy biasing and the weight window technique in MCNP shielding calculations has been developed. The method is based on the approach used in the SAS4 module of the SCALE code system, which derives the biasing parameters from an adjoint one-dimensional Discrete Ordinates calculation. Unlike SAS4 that determines the radial and axial dose rates of a spent fuel cask in separate calculations, the present method provides energy and spatial biasing parameters for the entire system that optimize the simulation of particle transport towards all external surfaces of a spent fuel cask. The energy and spatial biasing parameters are synthesized from the adjoint fluxes of three one-dimensional Discrete Ordinates adjoint calculations. Additionally, the present method accommodates multiple source regions, such as the photon sources in light-water reactor spent nuclear fuel assemblies, in one calculation. With this automated method, detailed and accurate dose rate maps for photons, neutrons, and secondary photons outside spent fuel casks or other containers can be efficiently determined with minimal efforts.
Variance reduction methods applied to deep-penetration problems
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.
Methods for variance reduction in Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Bixler, Joel N.; Hokr, Brett H.; Winblad, Aidan; Elpers, Gabriel; Zollars, Byron; Thomas, Robert J.
2016-03-01
Monte Carlo simulations are widely considered to be the gold standard for studying the propagation of light in turbid media. However, due to the probabilistic nature of these simulations, large numbers of photons are often required in order to generate relevant results. Here, we present methods for reduction in the variance of dose distribution in a computational volume. Dose distribution is computed via tracing of a large number of rays, and tracking the absorption and scattering of the rays within discrete voxels that comprise the volume. Variance reduction is shown here using quasi-random sampling, interaction forcing for weakly scattering media, and dose smoothing via bi-lateral filtering. These methods, along with the corresponding performance enhancements are detailed here.
Advanced Variance Reduction Strategies for Optimizing Mesh Tallies in MAVRIC
Peplow, Douglas E.; Blakeman, Edward D; Wagner, John C
2007-01-01
More often than in the past, Monte Carlo methods are being used to compute fluxes or doses over large areas using mesh tallies (a set of region tallies defined on a mesh that overlays the geometry). For problems that demand that the uncertainty in each mesh cell be less than some set maximum, computation time is controlled by the cell with the largest uncertainty. This issue becomes quite troublesome in deep-penetration problems, and advanced variance reduction techniques are required to obtain reasonable uncertainties over large areas. The CADIS (Consistent Adjoint Driven Importance Sampling) methodology has been shown to very efficiently optimize the calculation of a response (flux or dose) for a single point or a small region using weight windows and a biased source based on the adjoint of that response. This has been incorporated into codes such as ADVANTG (based on MCNP) and the new sequence MAVRIC, which will be available in the next release of SCALE. In an effort to compute lower uncertainties everywhere in the problem, Larsen's group has also developed several methods to help distribute particles more evenly, based on forward estimates of flux. This paper focuses on the use of a forward estimate to weight the placement of the source in the adjoint calculation used by CADIS, which we refer to as a forward-weighted CADIS (FW-CADIS).
Automated Variance Reduction Applied to Nuclear Well-Logging Problems
Wagner, John C; Peplow, Douglas E.; Evans, Thomas M
2009-01-01
The Monte Carlo method enables detailed, explicit geometric, energy and angular representations, and hence is considered to be the most accurate method available for solving complex radiation transport problems. Because of its associated accuracy, the Monte Carlo method is widely used in the petroleum exploration industry to design, benchmark, and simulate nuclear well-logging tools. Nuclear well-logging tools, which contain neutron and/or gamma sources and two or more detectors, are placed in boreholes that contain water (and possibly other fluids) and that are typically surrounded by a formation (e.g., limestone, sandstone, calcites, or a combination). The response of the detectors to radiation returning from the surrounding formation is used to infer information about the material porosity, density, composition, and associated characteristics. Accurate computer simulation is a key aspect of this exploratory technique. However, because this technique involves calculating highly precise responses (at two or more detectors) based on radiation that has interacted with the surrounding formation, the transport simulations are computationally intensive, requiring significant use of variance reduction techniques, parallel computing, or both. Because of the challenging nature of these problems, nuclear well-logging problems have frequently been used to evaluate the effectiveness of variance reduction techniques (e.g., Refs. 1-4). The primary focus of these works has been on improving the computational efficiency associated with calculating the response at the most challenging detector location, which is typically the detector furthest from the source. Although the objective of nuclear well-logging simulations is to calculate the response at multiple detector locations, until recently none of the numerous variance reduction methods/techniques has been well-suited to simultaneous optimization of multiple detector (tally) regions. Therefore, a separate calculation is
Automated Variance Reduction Applied to Nuclear Well-Logging Problems
Wagner, John C; Peplow, Douglas E.; Evans, Thomas M
2008-01-01
The Monte Carlo method enables detailed, explicit geometric, energy and angular representations, and hence is considered to be the most accurate method available for solving complex radiation transport problems. Because of its associated accuracy, the Monte Carlo method is widely used in the petroleum exploration industry to design, benchmark, and simulate nuclear well-logging tools. Nuclear well-logging tools, which contain neutron and/or gamma sources and two or more detectors, are placed in boreholes that contain water (and possibly other fluids) and that are typically surrounded by a formation (e.g., limestone, sandstone, calcites, or a combination). The response of the detectors to radiation returning from the surrounding formation is used to infer information about the material porosity, density, composition, and associated characteristics. Accurate computer simulation is a key aspect of this exploratory technique. However, because this technique involves calculating highly precise responses (at two or more detectors) based on radiation that has interacted with the surrounding formation, the transport simulations are computationally intensive, requiring significant use of variance reduction techniques, parallel computing, or both. Because of the challenging nature of these problems, nuclear well-logging problems have frequently been used to evaluate the effectiveness of variance reduction techniques (e.g., Refs. 1-4). The primary focus of these works has been on improving the computational efficiency associated with calculating the response at the most challenging detector location, which is typically the detector furthest from the source. Although the objective of nuclear well-logging simulations is to calculate the response at multiple detector locations, until recently none of the numerous variance reduction methods/techniques has been well-suited to simultaneous optimization of multiple detector (tally) regions. Therefore, a separate calculation is
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.
Fringe biasing: A variance reduction technique for optically thick meshes
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)
Monte Carlo calculation of specific absorbed fractions: variance reduction techniques.
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 · 10(5) 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. PMID
AVATAR -- Automatic variance reduction in Monte Carlo calculations
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.
MC Estimator Variance Reduction with Antithetic and Common Random Fields
NASA Astrophysics Data System (ADS)
Guthke, P.; Bardossy, A.
2011-12-01
Monte Carlo methods are widely used to estimate the outcome of complex physical models. For physical models with spatial parameter uncertainty, it is common to apply spatial random functions to the uncertain variables, which can then be used to interpolate between known values or to simulate a number of equally likely realizations .The price, that has to be paid for such a stochastic approach, are many simulations of the physical model instead of just running one model with one 'best' input parameter set. The number of simulations is often limited because of computational constraints, so that a modeller has to make a compromise between the benefit in terms of an increased accuracy of the results and the effort in terms of a massively increased computational time. Our objective is, to reduce the estimator variance of dependent variables in Monte Carlo frameworks. Therefore, we adapt two variance reduction techniques (antithetic variates and common random numbers) to a sequential random field simulation scheme that uses copulas as spatial dependence functions. The proposed methodology leads to pairs of spatial random fields with special structural properties, that are advantageous in MC frameworks. Antithetic Random fields (ARF) exhibit a reversed structure on the large scale, while the dependence on the local scale is preserved. Common random fields (CRF) show the same large scale structures, but different spatial dependence on the local scale. The performances of the proposed methods are examined with two typical applications of stochastic hydrogeology. It is shown, that ARF have the property to massively reduce the number of simulation runs required for convergence in Monte Carlo frameworks while keeping the same accuracy in terms of estimator variance. Furthermore, in multi-model frameworks like in sensitivity analysis of the spatial structure, where more than one spatial dependence model is used, the influence of different dependence structures becomes obvious
NASA Astrophysics Data System (ADS)
Lai, Yongzeng; Zeng, Yan; Xi, Xiaojing
2011-11-01
In this paper, we discuss control variate methods for Asian option pricing under exponential jump diffusion model for the underlying asset prices. Numerical results show that the new control variate XNCV is much more efficient than the classical control variate XCCV when used in pricing Asian options. For example, the variance reduction ratios by XCCV are no more than 120 whereas those by XNCV vary from 15797 to 49171 on average over sample sizes 1024, 2048, 4096, 8192, 16384 and 32768.
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.
Improving computational efficiency of Monte Carlo simulations with variance reduction
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)
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.
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.
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.
Sensor/Actuator Selection for the Constrained Variance Control Problem
NASA Technical Reports Server (NTRS)
Delorenzo, M. L.; Skelton, R. E.
1985-01-01
The problem of designing a linear controller for systems subject to inequality variance constraints is considered. A quadratic penalty function approach is used to yield a linear controller. Both the weights in the quadratic penalty function and the locations of sensors and actuators are selected by successive approximations to obtain an optimal design which satisfies the input/output variance constraints. The method is applied to NASA's 64 meter Hoop-Column Space Antenna for satellite communications. In addition the solution for the control law, the main feature of these results is the systematic determination of actuator design requirements which allow the given input/output performance constraints to be satisfied.
Verification of the history-score moment equations for weight-window variance reduction
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,
Self-Tuning Continuous-Time Generalized Minimum Variance Control
NASA Astrophysics Data System (ADS)
Hoshino, Ryota; Mori, Yasuchika
The generalized minimum variance control (GMVC) is one of the design methods of self-tuning control (STC). In general, STC is applied as a discrete-time (DT) design technique. However, by some selection of the sampling period, the DT design technique has possibilities of generating unstable zeros and time-delays, and of failing in getting a clear grasp of the controlled object. For this reason, we propose a continuous-time (CT) design technique of GMVC, which we call CGMVC. In this paper, we confirm some advantages of CGMVC, and provide a numerical example.
Automatic variance reduction for Monte Carlo simulations via the local importance function transform
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.
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.
ADVANTG 3.0.1: AutomateD VAriaNce reducTion Generator
Energy Science and Technology Software Center (ESTSC)
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
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 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).
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.
Variance reduction for Fokker–Planck based particle Monte Carlo schemes
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.
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.
Models of Postural Control: Shared Variance in Joint and COM Motions
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. PMID:25973896
Models of Postural Control: Shared Variance in Joint and COM Motions.
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. PMID:25973896
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
Application of fuzzy sets to estimate cost savings due to variance reduction
NASA Astrophysics Data System (ADS)
Munoz, Jairo; Ostwald, Phillip F.
1993-12-01
One common assumption of models to evaluate the cost of variation is that the quality characteristic can be approximated by a standard normal distribution. Such an assumption is invalid for three important cases: (a) when the random variable is always positive, (b) when manual intervention distorts random variation, and (c) when the variable of interest is evaluated by linguistic terms. This paper applies the Weibull distribution to address nonnormal situations and fuzzy logic theory to study the case of quality evaluated via lexical terms. The approach concentrates on the cost incurred by inspection to formulate a probabilistic-possibilistic model that determines cost savings due to variance reduction. The model is tested with actual data from a manual TIG welding process.
Comparison of hybrid methods for global variance reduction in shielding calculations
Peplow, D. E.
2013-07-01
For Monte Carlo shielding problems that calculate a mesh tally over the entire problem, the statistical uncertainties computed for each voxel can vary widely. This can lead to unacceptably long run times in order to reduce the uncertainties in all areas of the problem to a reasonably low level. Hybrid methods - using estimates from deterministic calculations to create importance maps for variance reduction in Monte Carlo calculations - have been successfully used to optimize the calculation of specific tallies. For the global problem, several methods have been proposed to create importance maps that distribute Monte Carlo particles in such a way as to achieve a more uniform distribution of relative uncertainty across the problem. The goal is to compute a mesh tally with nearly the same relative uncertainties in the low flux/dose areas as in the high flux/dose areas. Methods based on only forward deterministic estimates and methods using both forward and adjoint deterministic methods have been implemented in the SCALE/MAVRIC package and have been compared against each other by computing global mesh tallies on several representative shielding problems. Methods using both forward and adjoint estimates provide better performance for computing more uniform relative uncertainties across a global mesh tally. (authors)
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)
PWR Facility Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology
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.
Extensions of output variance constrained controllers to hard constraints
NASA Technical Reports Server (NTRS)
Skelton, R.; Zhu, G.
1989-01-01
Covariance Controllers assign specified matrix values to the state covariance. A number of robustness results are directly related to the covariance matrix. The conservatism in known upperbounds on the H infinity, L infinity, and L (sub 2) norms for stability and disturbance robustness of linear uncertain systems using covariance controllers is illustrated with examples. These results are illustrated for continuous and discrete time systems. **** ONLY 2 BLOCK MARKERS FOUND -- RETRY *****
Generalized minimum variance control under long-range prediction horizon setups.
Silveira, Antonio; Trentini, Rodrigo; Coelho, Antonio; Kutzner, Rüdiger; Hofmann, Lutz
2016-05-01
This paper presents the design and evaluation of a minimal order Generalized Minimum Variance controller with long-range prediction horizon and how it affects the controller and plant output variances. This study investigates how the increased prediction horizon can contribute to mitigate stochastic disturbances and attenuate oscillations. In order to design high order prediction minimum variance filters, a design procedure independent of the Diophantine Equation solution is used. The evaluation is conducted through simulations and practical essays with two different plants: a first order water flow rate problem and a second order under-damped electronic circuit. Both problems are assessed under an incremental control scheme and based on identified stochastic models. Also, two optimal tuning procedures for the algorithm are proposed. PMID:26899555
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.
NASA Astrophysics Data System (ADS)
Milias-Argeitis, Andreas; Lygeros, John; Khammash, Mustafa
2014-07-01
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.
Crystallographic Control in Ilmenite Reduction
NASA Astrophysics Data System (ADS)
de Vries, M. L.; Grey, I. E.; Fitz Gerald, J. D.
2007-04-01
Scanning electron microscopy and transmission electron microscopy techniques were used to characterize the products from hydrogen reduction of polygranular synthetic ilmenite discs at temperatures in the range 823 to 1173 K and pressures in the range 1 to 13 atm. Reduction commences at grain boundaries and cracks and advances progressively to grain interiors. Within individual grains, the morphology of the reduction products was found to be crystallographically controlled. Near parallel bands of metallic iron (Fe m ) form within each grain, aligned with the basal plane of ilmenite (il) (0001) il . The separation between bands is of the order of 1 μm and is relatively constant with change of pressure and temperature. In the interband region, conversion of ilmenite to rutile occurs preferentially parallel to \\{ 11ifmmodeexpandafterbarelseexpandafter\\=fi{2}0\\} _{{il}} ilmenite planes, generating platelets of rutile that grow normal to the Fe m bands. The intergrain duplex morphology of the reduction products closely resembles cellular precipitation in alloys. At reduction temperatures above ˜1000 K, the interband region comprises dense, nonporous oriented intergrowths of rutile platelets and residual ilmenite, whereas below ˜900 K, the interband region contains a fine, filamentary network of pores. In the intermediate temperature regime, a change from dense to porous interband region occurs with increasing pressure. The observations have been interpreted in terms of the relative rates of interfacial chemical reaction and solid-state diffusion, with the latter having a controlling influence at lower temperatures or higher pressures.
Advanced Variance Reduction for Global k-Eigenvalue Simulations in MCNP
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
Sampson, Andrew; Le Yi; Williamson, Jeffrey F.
2012-02-15
heterogeneous doses. 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 x 1 x 1 mm{sup 3}) and breast (0.67 x 0.67 x 0.8 mm{sup 3}) 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.
A Proposal of Partial Model Matching Method for Continuous-Time Generalized Minimum Variance Control
NASA Astrophysics Data System (ADS)
Tajima, Jyun-Ichi; Doi, Masayoshi; Mori, Yasuchika
The proposed method can improve the response for the servo type Continuous-time Generalized Minimum Variance Control (CGMVC). The conventional CGMVC, which is tuned due to the controlled input weighting of the cost function, cannot freely adjust the response in the case of the servo type. This study proposes a new servo CGMVC of tuning the output weighting of the cost function. The proposed CGMVC is applied by the Partial Model Matching (PMM) method. The CGMVC with PMM and tuning the output weighting can improve both the response of tracking the reference signal and the load-disturbance rejection.
Robust Hotelling T2 control chart using reweighted minimum vector variance estimators
NASA Astrophysics Data System (ADS)
Ali, Hazlina; Yahaya, Sharipah Soaad Syed; Omar, Zurni
2014-12-01
Hotelling T2 control chart is employed to monitor the stability of a multivariate process in Phase I and II. Traditional Hotelling T2 control chart using classical estimators in Phase I, however, suffers from masking and swamping effects and thus jeorpadizes its performance. To alleviate this problem, robust location and scale estimators are recommended instead. In this paper, a new Hotelling T2 control chart based on highly robust and efficient estimators of location and scatter estimators, known as reweighted minimum vector variance estimators, is proposed. Numerical results show that the new chart is not only capable of detecting outliers but it can also control the alarm rates better than the existing charts.
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.
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
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.
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
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.
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.
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
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
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
Drift reduction with drift control adjuvants
Technology Transfer Automated Retrieval System (TEKTRAN)
Numerous drift reduction adjuvants and spray deposition aids are available to applicators of crop production and protection chemicals. Performance of many of the newly introduced drift control adjuvants has not been well documented for aerial application. Five new drift control adjuvants were sele...
Drift reduction with drift control adjuvants
Technology Transfer Automated Retrieval System (TEKTRAN)
Numerous drift reduction adjuvants and spray deposition aids are available to applicators of crop production and protection chemicals. Performance of many of the newly introduced drift control adjuvants has not been well documented for aerial application. Four new drift control adjuvants were sele...
NASA Astrophysics Data System (ADS)
Maboodi, Mohsen; Camacho, Eduardo F.; Khaki-Sedigh, Ali
2015-10-01
This paper presents a non-linear generalised minimum variance (NGMV) controller for a second-order Volterra series model with a general linear additive disturbance. The Volterra series models provide a natural extension of a linear convolution model with the nonlinearity considered in an additive term. The design procedure is entirely carried out in the state space framework, which facilitates the application of other analysis and design methods in this framework. First, the non-linear minimum variance (NMV) controller is introduced and then by changing the cost function, NGMV controller is defined as an extended version of the linear cases. The cost function is used in the simplest form and can be easily extended to the general case. Simulation results show the effectiveness of the proposed non-linear method.
NASA Technical Reports Server (NTRS)
Kotob, S.; Kaufman, H.
1976-01-01
An on-line minimum variance parameter identifier is developed which embodies both accuracy and computational efficiency. The formulation results in a linear estimation problem with both additive and multiplicative noise. The resulting filter which utilizes both the covariance of the parameter vector itself and the covariance of the error in identification is proven to be mean square convergent and mean square consistent. The MV parameter identification scheme is then used to construct a stable state and parameter estimation algorithm.
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
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.
NASA Technical Reports Server (NTRS)
Jacobson, R. A.
1975-01-01
Difficulties arise in guiding a solar electric propulsion spacecraft due to nongravitational accelerations caused by random fluctuations in the magnitude and direction of the thrust vector. These difficulties may be handled by using a low thrust guidance law based on the linear-quadratic-Gaussian problem of stochastic control theory with a minimum terminal miss performance criterion. Explicit constraints are imposed on the variances of the control parameters, and an algorithm based on the Hilbert space extension of a parameter optimization method is presented for calculation of gains in the guidance law. The terminal navigation of a 1980 flyby mission to the comet Encke is used as an example.
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. PMID:25281584
NASA Astrophysics Data System (ADS)
Huenges, Ernst
This paper presents a statistical analysis of about 50000 petrophysical data measured on core samples from the Continental Deep Drilling Project (KTB) of the Federal Republic of Germany. The scattering of the data must be taken into consideration using empirical relationships between pairs of parameters, e.g., sound velocity, density, heat production and thermal conductivity. Such covariances of parameters were calculated and used to find the principle components by applying factor analysis. The reduction of parameters by factor analysis may help other scientists to concentrate on the essential parameters to be measured. About 50% of the variance of all data can be explained by one background variable, the so-called “lithology factor”. The variables that load a factor are either highly correlated or anticorrelated. The lithology factor combines gamma spectroscopy data, density and the mineral contents of quartz, amphibole, garnet and white mica. Seismic velocities and porosity data, however, were less well related to the lithology factor. Therefore, the KTB data indicate that correlation between seismic velocity and one of the lithology factor loading variables is unlikely. The lithology factor distinguishes 3 major “rock types”: metabasites, gneisses and an intermediate type. The variance of the petrophysical parameters within the rock types, plotted in crossplots, show the level of validity of commonly used relationships among these parameters. Measurements under ambient and simulated in-situ conditions are included to enable discussion of chemical, mineralogical and microstructural characteristics of the rocks.
Wind Turbine Control for Load Reduction
NASA Astrophysics Data System (ADS)
Bossanyi, E. A.
2003-07-01
This article reviews techniques for the control of wind turbines during power production. Pitch control is used primarily to limit power in high winds, but it also has an important effect on structural loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable-speed turbines is used primarily to maximize energy capture below rated wind speed, and to limit the torque above rated, but it can also be used to reduce certain loads. The design of the control algorithms is clearly of prime importance. Additional sensors such as accelerometers and load sensors can also help the controller to achieve its objectives more effectively. By controlling the pitch of each blade independently, it is also possible to achieve important further reductions in loading. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials.
Feedback Control for Noise Reduction Program
NASA Astrophysics Data System (ADS)
Tucker, Jerry H.
2002-12-01
As part of Langley Research Center's continuing noise reduction program, an active noise control system (ANC) is being developed to suppress noise inside an aircraft cabin. This interior noise reduction system consists of the following major components: 1. Several accelerometers. 2. An input amplifier. 3. A digital signal processor (DSP) system that includes an analog to digital converter (ADC) and a digital to analog converter (DAC). 4. A high voltage power amplifier. 5. PZT actuators. 6. Power supply and distribution. The accelerometers detect interior panel vibrations. The accelerometer signals are fed to the input amplifier where they are conditioned prior to being sent to the ADC. The DSP receives the digitized signals form the ADC, processes these signals, and sends the result to the DAC. The DAC's analog output is used as input to the high voltage power amplifier. The power amplifier drives the PZT actuators to cancel noise form 50 to 1,300 Hz. The specific area of concern for this work was development of a DSP system that could be used for an actual flight demonstration. It was decided to base the system on a commercially available DSP board, the Spectrum Digital eZdsp. This was complicated by the fact that the ADC and DAC capabilities available on the eZdsp board were not sufficient to meet the system specification. Designing and fabricating a special ADC and DAC daughter card for the eZdsp circumvented this problem. The DSP system hardware has been successfully tested and is currently being integrated into the complete noise reduction system. This work has been completed in collaboration with another ASEE Fellow, Dr.William Edmonson from Hampton University and was conducted under the direction of the principle investigator, Dr. Qamar A. Shams of the Instrumentation Systems Development Branch, as part of a continuing noise reduction program.
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.
Orthogonal control of expression mean and variance by epigenetic features at different genomic loci
Dey, Siddharth S; Foley, Jonathan E; Limsirichai, Prajit; Schaffer, David V; Arkin, Adam P
2015-01-01
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. PMID:25943345
Orthogonal control of expression mean and variance by epigenetic features at different genomic loci
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
Orthogonal control of expression mean and variance by epigenetic features at different genomic loci
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.
Helicopter Control Energy Reduction Using Moving Horizontal Tail
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
[Harm reduction strategy in tobacco control].
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
NASA Astrophysics Data System (ADS)
Maboodi, M.; Khaki-Sedigh, A.; Camacho, E. F.
2015-08-01
In this paper, control performance assessment for a class of nonlinear systems modelled by autoregressive second-order Volterra series with a general linear additive disturbance is presented. The proposed approach employs the nonlinear generalised minimum variance (NGMV) controller concept. The Volterra series models provide a natural extension of a linear convolution model with the nonlinearity considered in an additive term. The polynomial operator form is used throughout this paper for the description of the system input-output model. The closed form formulation of NGMV controller for autoregressive second-order Volterra series is presented in a polynomial form then a control assessment criterion based on the NGMV control is given. Simulation results and comparison studies are used to show the effectiveness of the proposed approach for a class of nonlinear systems.
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.
Practice reduces task relevant variance modulation and forms nominal trajectory.
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
Practice reduces task relevant variance modulation and forms nominal trajectory
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
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.
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.
Feedback controllers for broadband active noise reduction
NASA Astrophysics Data System (ADS)
Petitjean, Benoit; Legrain, Isabelle
1994-09-01
The aim of the present paper is to demonstrate the efficiency of an LQG-based controller for the active control of the acoustic field radiated by a rectangular panel. This topic has been of interest for numerous researchers in the past 10 or 15 years, but very little attention has been paid to broadband disturbances occurring in a relatively high frequency range. These are unfortunately common features of noise perturbations in realistic structures such as airplanes or helicopters. The few articles that deal with this problem provide very scarce experimental results and are related to frequency bands where the structure dynamics is rather poor. From the outset, the problem at hand involves numerous difficulties, such as the modeling of the active structure itself and the possible large size of the controller. In the following, the experimental setup is described, then the controller design procedure is developed and finally some experimental results are shown that prove the efficiency of the method.
Magnetostrictively actuated control flaps for vibration reduction in helicopter rotors
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.
Higher Harmonic Control for Tiltrotor Vibration Reduction
NASA Technical Reports Server (NTRS)
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5- scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing 1P and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasion-al on-line recalculations of the system transfer matrix.
Tiltrotor Vibration Reduction Through Higher Harmonic Control
NASA Technical Reports Server (NTRS)
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5-scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing IP and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasional on-line recalculations of the system transfer matrix. HHC had only a small (usually beneficial) effect on blade loads but increased pitch link loads by 25%. No degradation in aeroelastic stability was noted for any of the conditions tested.
Control of fracture reduction robot using force/torque measurement.
Douke, T; Nakajima, Y; Mori, Y; Onogi, S; Sugita, N; Mitsuishi, M; Bessho, M; Ohhashi, S; Tobita, K; Ohnishi, I; Sakuma, I; Dohi, T; Maeda, Y; Koyama, T; Sugano, N; Yonenobu, K; Matsumoto, Y; Nakamura, K
2008-01-01
We have developed a surgical robotic system for femoral fracture reduction employing indirect traction. Indirect traction in fracture reduction is a generally used surgical method for preventing complications such as bone splits caused by high stress on bones. For traction, a patient's foot is gripped by a jig and pulled to the distal side. Indirect traction has the advantage of distributing bone stress by utilizing a strong traction force; however, this procedure does not accurately control the proper positioning of fractured fragments when a surgical robot is used. The human leg has knee and an ankle joints, and thus robotic motion presents problems in not being able to directly propagate reduction motion to a fractured femoral fragment, rendering control of bone position difficult. We propose a control method for fracture reduction robots using external force/torque measurements of the human leg to achieve precise fracture reduction. Results showed that the proposed method reduced repositioning error from 6.8 mm and 15.9 degrees to 0.7 mm and 5.3 degrees, respectively. PMID:19163404
Control of the ST7 Disturbance Reduction System Flight Experiment
NASA Technical Reports Server (NTRS)
Maghami, P. G.; Hsu, O. C,; ODonnell, J. R., Jr.
2007-01-01
The Space Technology 7 (ST7) experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: colloidal micronewton thrusters and drag-free control. The ST7 Disturbance Reduction System (DRS) is designed to maintain the spacecraft s position with respect to a free-floating test mass while limiting the residual accelerations of that test mass over the frequency range of 1 to 30 mHz. This paper presents the overall design and analysis of the spacecraft drag-free and attitude controllers, with particular attention given to its primary mission mode. These controllers close the loop between the drag-free sensors and the colloidal micronewton thrusters.
Reduction of tilt rotor download using circulation control
NASA Technical Reports Server (NTRS)
Felker, Fort F.; Light, Jeffrey S.; Faye, Robert E.
1987-01-01
The effect of boundary layer control blowing on the download of a wing in the wake of a hovering rotor was measured in a small scale experiment. The objective was to evaluate the potential of boundary layer control blowing for reducing tilt rotor download. Variations were made in rotor thrust coefficient, blowing pressure ratio, and blowing slot height. The effect of these parameter variations on the wing download and wing surface pressures is presented. The boundary layer control blowing caused reductions in the wing download of 25 to 55 percent.
Formoso-Rafferty, N; Cervantes, I; Ibáñez-Escriche, N; Gutiérrez, J P
2016-06-01
Data from seven generations of a divergent selection experiment designed for environmental variability of birth weight were analysed to estimate genetic parameters and to explore signs of selection response. A total of 10 783 birth weight records from 638 females and 1127 litters in combination with 10 007 pedigree records were used. Each record of birth weight was assigned to the mother of the pup in a heteroscedastic model, and after seven generations of selection, evidence of success in the selection process was shown. A Bayesian analysis showed that success of the selection process started from the first generation for birth weight and from the second generation for its environmental variability. Genetic parameters were estimated across generations. However, only from the third generation onwards were the records useful to consider the results to be reliable. The results showed a consistent positive and low genetic correlation between the birth weight trait and its environmental variability, which could allow an independent selection process. This study has demonstrated that the genetic control of the birth weight environmental variability is possible in mice. Nevertheless, before the results are applied directly in farm animals, it would be worth confirming any other implications on other important traits, such as robustness, longevity and welfare. PMID:26150168
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
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
Integrated Model Reduction and Control of Aircraft with Flexible Wings
NASA Technical Reports Server (NTRS)
Swei, Sean Shan-Min; Zhu, Guoming G.; Nguyen, Nhan T.
2013-01-01
This paper presents an integrated approach to the modeling and control of aircraft with exible wings. The coupled aircraft rigid body dynamics with a high-order elastic wing model can be represented in a nite dimensional state-space form. Given a set of desired output covariance, a model reduction process is performed by using the weighted Modal Cost Analysis (MCA). A dynamic output feedback controller, which is designed based on the reduced-order model, is developed by utilizing output covariance constraint (OCC) algorithm, and the resulting OCC design weighting matrix is used for the next iteration of the weighted cost analysis. This controller is then validated for full-order evaluation model to ensure that the aircraft's handling qualities are met and the uttering motion of the wings suppressed. An iterative algorithm is developed in CONDUIT environment to realize the integration of model reduction and controller design. The proposed integrated approach is applied to NASA Generic Transport Model (GTM) for demonstration.
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%.
Responsible and controlled use: Older cannabis users and harm reduction
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
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.
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.
"APEC Blue": Secondary Aerosol Reductions from Emission Controls in Beijing.
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
Getting around cosmic variance
Kamionkowski, M.; Loeb, A.
1997-10-01
Cosmic microwave background (CMB) anisotropies probe the primordial density field at the edge of the observable Universe. There is a limiting precision ({open_quotes}cosmic variance{close_quotes}) with which anisotropies can determine the amplitude of primordial mass fluctuations. This arises because the surface of last scatter (SLS) probes only a finite two-dimensional slice of the Universe. Probing other SLS{close_quote}s observed from different locations in the Universe would reduce the cosmic variance. In particular, the polarization of CMB photons scattered by the electron gas in a cluster of galaxies provides a measurement of the CMB quadrupole moment seen by the cluster. Therefore, CMB polarization measurements toward many clusters would probe the anisotropy on a variety of SLS{close_quote}s within the observable Universe, and hence reduce the cosmic-variance uncertainty. {copyright} {ital 1997} {ital The American Physical Society}
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.
Multivariable frequency weighted model order reduction for control synthesis
NASA Technical Reports Server (NTRS)
Schmidt, David K.
1989-01-01
Quantitative criteria are presented for model simplification, or order reduction, such that the reduced order model may be used to synthesize and evaluate a control law, and the stability robustness obtained using the reduced order model will be preserved when controlling the full-order system. The error introduced due to model simplification is treated as modeling uncertainty, and some of the results from multivariate robustness theory are brought to bear on the model simplification problem. A numerical procedure developed previously is shown to lead to results that meet the necessary criteria. The procedure is applied to reduce the model of a flexible aircraft. Also, the importance of the control law itself, in meeting the modeling criteria, is underscored. An example is included that demonstrates that an apparently robust control law actually amplifies modest modeling errors in the critical frequency region, and leads to undesirable results. The cause of this problem is associated with the canceling of lightly damped transmission zeroes in the plant. An attempt is made to expand on some of the earlier results and to further clarify the theoretical basis behind the proposed methodology.
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…
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.
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…
Controller Design for the ST7 Disturbance Reduction System
NASA Technical Reports Server (NTRS)
Maghami, Peiman; Markley, F. Landis; Dennehey, Neil; Houghton, Martin B.; Folkner, William M.; Bauer, Frank (Technical Monitor)
2002-01-01
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 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 micro-Newton 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.
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...
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
Spectral Ambiguity of Allan Variance
NASA Technical Reports Server (NTRS)
Greenhall, C. A.
1996-01-01
We study the extent to which knowledge of Allan variance and other finite-difference variances determines the spectrum of a random process. The variance of first differences is known to determine the spectrum. We show that, in general, the Allan variance does not. A complete description of the ambiguity is given.
Automated Boiler Combustion Controls for Emission Reduction and Efficiency Improvement
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.
Adaptive control of an active seat for occupant vibration reduction
NASA Astrophysics Data System (ADS)
Gan, Zengkang; Hillis, Andrew J.; Darling, Jocelyn
2015-08-01
The harmful effects on human performance and health caused by unwanted vibration from vehicle seats are of increasing concern. This paper presents an active seat system to reduce the vibration level transmitted to the seat pan and the occupants' body under low frequency periodic excitation. Firstly, the detail of the mechanical structure is given and the active seat dynamics without external load are characterized by vibration transmissibility and frequency responses under different excitation forces. Owing the nonlinear and time-varying behaviour of the proposed system, a Filtered-x least-mean-square (FXLMS) adaptive control algorithm with on-line Fast-block LMS (FBLMS) identification process is employed to manage the system operation for high vibration cancellation performance. The effectiveness of the active seat system is assessed through real-time experimental tests using different excitation profiles. The system identification results show that an accurate estimation of the secondary path is achieved by using the FBLMS on-line technique. Substantial reduction is found for cancelling periodic vibration containing single and multiple frequencies. Additionally, the robustness and stability of the control system are validated through transient switching frequency tests.
Nuclear Material Variance Calculation
Energy Science and Technology Software Center (ESTSC)
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
Biclustering with heterogeneous variance.
Chen, Guanhua; Sullivan, Patrick F; Kosorok, Michael R
2013-07-23
In cancer research, as in all of medicine, it is important to classify patients into etiologically and therapeutically relevant subtypes to improve diagnosis and treatment. One way to do this is to use clustering methods to find subgroups of homogeneous individuals based on genetic profiles together with heuristic clinical analysis. A notable drawback of existing clustering methods is that they ignore the possibility that the variance of gene expression profile measurements can be heterogeneous across subgroups, and methods that do not consider heterogeneity of variance can lead to inaccurate subgroup prediction. Research has shown that hypervariability is a common feature among cancer subtypes. In this paper, we present a statistical approach that can capture both mean and variance structure in genetic data. We demonstrate the strength of our method in both synthetic data and in two cancer data sets. In particular, our method confirms the hypervariability of methylation level in cancer patients, and it detects clearer subgroup patterns in lung cancer data. PMID:23836637
40 CFR 59.509 - Can I get a variance?
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Can I get a variance? 59.509 Section 59... Volatile Organic Compound Emission Standards for Aerosol Coatings § 59.509 Can I get a variance? (a) Any... its reasonable control may apply in writing to the Administrator for a temporary variance....
40 CFR 52.1390 - Missoula variance provision.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Missoula variance provision. 52.1390... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Montana § 52.1390 Missoula variance provision. The Missoula City-County Air Pollution Control Program's Chapter X, Variances, which was...
COST OF SELECTIVE CATALYTIC REDUCTION (SCR) APPLICATION FOR NOX CONTROL ON COAL-FIRED BOILERS
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...
Microbial and geochemical controls on dissimilatory Fe(III) reduction
Urrutia, M.M.; Roden, E.E.; Zachara, J.M.
1995-12-31
This study investigates the influence of coating bacterial oxide surfaces with Fe(II) on the rate and extent of Fe(III) reduction. Limitations imposed by the microorganisms themselves on the rate and extent of reduction of solid phase Fe(III) were also examined. Shewanella alga (strain BrY) cells were coated with Fe(II) and used as inocula for Fe(III) reduction experiments. The coating considerably slowed down the initial rate of Fe(III) reduction in comparison with uncoated cells, proceeding at a rate similar to that exhibited by uncoated cells at the latest stages of growth. Furthermore, the presence of chelators (EDTA and NTA) with a high affinity for Fe(II) was related to further reduction of medium surface area Goethite (MSA Gt) by BrY, which supports the idea of cessation of reduction by occlusion of the active surfaces. Reinoculation experiments, in which fresh cells were added after completion of a whole cell cycle, showed further reduction of Fe(III) with either MSA Gt, or hematite, high surface area and MSA Gt. Together, findings support the hypothesis that the binding, and eventual coating, of Fe(III) oxide and bacterial surfaces with Fe(II) is involved in the slowdown and eventual cessation of Fe(III) reduction within a cell growth cycle.
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
Spectral variance of aeroacoustic data
NASA Technical Reports Server (NTRS)
Rao, K. V.; Preisser, J. S.
1981-01-01
An asymptotic technique for estimating the variance of power spectra is applied to aircraft flyover noise data. The results are compared with directly estimated variances and they are in reasonable agreement. The basic time series need not be Gaussian for asymptotic theory to apply. The asymptotic variance formulae can be useful tools both in the design and analysis phase of experiments of this type.
NASA Astrophysics Data System (ADS)
Daraji, A. H.; Hale, J. M.
2014-09-01
This paper concerns the active vibration reduction of a flexible structure with discrete piezoelectric sensors and actuators in collocated pairs bonded to its surface. In this study, a new fitness and objective function is proposed to determine the optimal number of actuators, based on variations in the average closed loop dB gain margin reduction for all of the optimal piezoelectric pairs and on the modes that are required to be attenuated using the optimal linear quadratic control scheme. The aim of this study is to find the minimum number of optimally located sensor/actuator pairs, which can achieve the same vibration reduction as a greater number, in order to reduce the cost, complexity and power requirement of the control system. This optimization was done using a genetic algorithm. The technique may be applied to any lightly damped structure, and is demonstrated here by attenuating the first six vibration modes of a flat cantilever plate. It is shown that two sensor/actuator pairs, located and controlled optimally, give almost the same vibration reduction as ten pairs. These results are validated by comparing the open and closed loop time responses and actuator feedback voltages for various numbers of piezoelectric pairs using the ANSYS finite element package and a proportional differential control scheme.
Controller reduction for effective interdisciplinary design of active structures
NASA Technical Reports Server (NTRS)
Balas, Mark J.; Quan, Ralph
1989-01-01
Control problems of large aerospace structures are intrinsically interdisciplinary and require strategies which address the complete interaction between flexible structures, electromechanical actuators and sensors, and feedback control algorithms. Current research and future directions which will require an interdisciplinary team effort in dynamics, control and optimization of such structures are being surveyed. It is generally agreed that the dynamics of space structures require large scale discrete modeling, resulting in thousands of discrete unknowns. Proven control strategies, on the other hand, employ a low order controller that is based on a reduced order model of structures. Integration of such low order controllers and large scale dynamics models often leads to serious deterioration of the closed loop stability margin and even instability. To alleviate this stability deterioration while low order controllers remain effective, the following approach was investigated: (1) retain low order controllers based on reduced order models of structures as the basic control strategy; (2) introduce a compensator that will directly account for the deterioration of stability margin due to controller-structure integration; and (3) assess overall performance of the integrated control structure system by developing measures of suboptimality in the combination of (1) and (2). The benefits include: simplicity in the design of basic controllers, thus facilitating the optimization of structure control interactions; increased understanding of the roles of the compensator so as to modify the structure as well as the basic controller, if necessary, for improved performance; and adaptability to localize controllers by viewing the compensator as a systems integration filter.
Cosmology without cosmic variance
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.
Cosmology without cosmic variance
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
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
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
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.
46 CFR 110.01-2 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 4 2011-10-01 2011-10-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 110.01-2 Section 110.01-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to the Paperwork Reduction Act....
Budget variance analysis using RVUs.
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
Energy scaling and reduction in controlling complex networks
Chen, Yu-Zhong; Wang, Le-Zhi; Wang, Wen-Xu; Lai, Ying-Cheng
2016-01-01
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
Energy scaling and reduction in controlling complex networks.
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
Active Flap Control of the SMART Rotor for Vibration Reduction
NASA Technical Reports Server (NTRS)
Hall, Steven R.; Anand, R. Vaidyanathan; Straub, Friedrich K.; Lau, Benton H.
2009-01-01
Active control methodologies were applied to a full-scale active flap rotor obtained during a joint Boeing/ DARPA/NASA/Army test in the Air Force National Full-Scale Aerodynamic Complex 40- by 80-foot anechoic wind tunnel. The active flap rotor is a full-scale MD 900 helicopter main rotor with each of its five blades modified to include an on-blade piezoelectric actuator-driven flap with a span of 18% of radius, 25% of chord, and located at 83% radius. Vibration control demonstrated the potential of active flaps for effective control of vibratory loads, especially normal force loads. Active control of normal force vibratory loads using active flaps and a continuous-time higher harmonic control algorithm was very effective, reducing harmonic (1-5P) normal force vibratory loads by 95% in both cruise and approach conditions. Control of vibratory roll and pitch moments was also demonstrated, although moment control was less effective than normal force control. Finally, active control was used to precisely control blade flap position for correlation with pretest predictions of rotor aeroacoustics. Flap displacements were commanded to follow specific harmonic profiles of 2 deg or more in amplitude, and the flap deflection errors obtained were less than 0.2 deg r.m.s.
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…
Biogeochemical Processes Controlling Microbial Reductive Precipitation of Radionuclides
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.
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.
COST OF SELECTIVE CATALYTIC REDUCTION (SCR) APPLICATION FOR NOX CONTROL ON COAL-FIRED BOILERS
The report provides a methodology for estimating budgetary costs associ-ated with retrofit applications of selec-tive catalytic reduction (SCR) technology on coal-fired boilers. SCR is a post-combustion nitrogen oxides (NOX) con-trol technology capable of providing NOX reductions...
46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 9 2011-10-01 2011-10-01 false OMB control numbers assigned pursuant to the Paperwork 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 SHIPPING ACT OF 1984 Paperwork Reduction...
Shock wave strength reduction by passive control using perforated plates
NASA Astrophysics Data System (ADS)
Doerffer, Piotr; Szulc, Oskar
2007-05-01
Strong, normal shock wave, terminating a local supersonic area on an airfoil, not only limits aerodynamic performance but also becomes a source of a high-speed impulsive helicopter noise. The application of a passive control system (a cavity covered by a perforated plate) on a rotor blade should reduce the noise created by a moving shock. This article covers the numerical implementation of the Bohning/Doerffer transpiration law into the SPARC code and includes an extended validation against the experimental data for relatively simple geometries of transonic nozzles. It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducing passive control device in hover and in forward flight conditions.
Worktime control-dependent reductions in fatigue, sleep problems, and depression.
Takahashi, Masaya; Iwasaki, Kenji; Sasaki, Takeshi; Kubo, Tomohide; Mori, Ippei; Otsuka, Yasumasa
2011-01-01
We investigated the association between worktime control and fatigue, sleep problems, and depressive symptoms in a sample of daytime and shift workers. A total of 3681 permanent daytime workers and 599 shift workers completed a questionnaire designed to assess the above variables. Worktime control was evaluated in terms of both "control over daily working hours" and "control over days off". Worktime control × work schedule × gender analysis of covariance, adjusted for age and employment status, showed overall reductions in incomplete recovery, insomnia symptoms, daytime sleepiness, and depressive symptoms with increasing levels of worktime control. However, no associations between control over daily working hours and insomnia symptoms were observed in women. The reductions appeared to be more evident for control over days off. These results remained consistent after adjustments for other potential covariates. The present findings indicate that increased worktime control and enhanced control over days off in particular, may be associated with favorable health outcomes. PMID:20638650
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
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.
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.
Model reduction and feedback control of transitional channel flow
NASA Astrophysics Data System (ADS)
Ilak, Milos
This dissertation examines the use of reduced-order models for design of linear feedback controllers for fluid flows. The focus is on transitional channel flow, a canonical shear flow case with a simple geometry yet complex dynamics. Reduced-order models of the linearized Navier-Stokes equations, which describe the evolution of perturbations in transitional channel flow, are computed using two methods for snapshot-based balanced truncation, Balanced Proper Orthogonal Decomposition (BPOD) and Eigensystem Realization Algorithm (ERA). The performance of these models in feedback control is evaluated in both linearized and nonlinear Direct Numerical Simulations (DNS) of channel flow. The first part of the dissertation describes the application of BPOD to very large systems, and the detailed evaluation of the resulting reduced-order models. Exact balanced truncation, a standard method from control theory, is not computationally tractable for very large systems, such as those typically encountered in fluid flow simulations. The BPOD method, introduced by Rowley (2005), provides a close approximation. We first show that the approximation is indeed close by applying the method to a 1-D linear perturbation to channel flow at a single spatial wavenumber pair, for which exact balanced truncation is tractable. Next, as the first application of BPOD to a very high-dimensional linear system, we show that reduced-order BPOD models of a localized 3-D perturbation capture the dynamics very well. Moreover, the BPOD models significantly outperform standard Proper Orthogonal Decomposition (POD) models, as illustrated by a striking example where models using the POD modes that capture most of the perturbation energy fail to capture the perturbation dynamics. Next, reduced-order models of a complete control system for linearized channel flow are obtained using ERA, a computationally efficient method that results in the same reduced-order models as BPOD. Linear Quadratic Gaussian (LQG
Reduction of helicopter blade-vortex interaction noise by active rotor control technology
NASA Astrophysics Data System (ADS)
Yu, Yung H.; Gmelin, Bernd; Splettstoesser, Wolf; Philippe, Jean J.; Prieur, Jean; Brooks, Thomas F.
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.
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.
Particle reduction and control in EUV etching process
NASA Astrophysics Data System (ADS)
Jun, JeaYoung; Ha, TaeJoong; Kim, SangPyo; Yim, DongGyu
2014-10-01
As the device design rule shrinks, photomask manufacturers need to have advanced defect controllability during the ARC (Anti-Reflection Coating) and ABS (Absorber) etch in an EUV (extreme ultraviolet) mask. Therefore we studied etching techniques of EUV absorber film to find out the evasion method of particle generation. Usually, Particles are generated by plasma ignition step in etching process. When we use the standard etching process, ARC and ABS films are etched step by step. To reduce the particle generation, the number of ignition steps need to decrease. In this paper, we present the experimental results of in-situ EUV dry etching process technique for ARC and ABS, which reduces the defect level significantly. Analysis tools used for this study are as follows; TEM (for cross-sectional inspection) , SEM (for in-line monitoring ) and OES (for checking optical emission spectrum)
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
Collins, Susan E.; Saxon, Andrew J.; Duncan, Mark H.; Smart, Brian F.; Merrill, Joseph O.; Malone, Daniel K.; Jackson, T. Ron; Clifasefi, Seema L.; Joesch, Jutta; Ries, Richard K.
2014-01-01
Background Interventions requiring abstinence from alcohol are neither preferred by nor shown to be highly effective with many homeless individuals with alcohol dependence. It is therefore important to develop lower-threshold, patient-centered interventions for this multimorbid and high-utilizing population. Harm-reduction counseling requires neither abstinence nor use reduction and pairs a compassionate style with patient-driven goal-setting. Extended-release naltrexone (XR-NTX), a monthly injectable formulation of an opioid receptor antagonist, reduces craving and may support achievement of harm-reduction goals. Together, harm-reduction counseling and XR-NTX may support alcohol harm reduction and quality-of-life improvement. Aims Study aims include testing: a) the relative efficacy of XR-NTX and harm-reduction counseling compared to a community-based, supportive-services-as-usual control, b) theory-based mediators of treatment effects, and c) treatment effects on publicly funded service costs. Methods This RCT involves four arms: a) XR-NTX+harm-reduction counseling, b) placebo+harm-reduction counseling, c) harm-reduction counseling only, and d) community-based, supportive-services-as-usual control conditions. Participants are currently/formerly homeless, alcohol dependent individuals (N=300). Outcomes include alcohol variables (i.e., craving, quantity/frequency, problems and biomarkers), health-related quality of life, and publicly funded service utilization and associated costs. Mediators include 10-point motivation rulers and the Penn Alcohol Craving Scale. XR-NTX and harm-reduction counseling are administered every 4 weeks over the 12-week treatment course. Follow-up assessments are conducted at weeks 24 and 36. Discussion If found efficacious, XR-NTX and harm-reduction counseling will be well-positioned to support reductions in alcohol-related harm, decreases in costs associated with publicly funded service utilization, and increases in quality of life among
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.
Climate Control Load Reduction Strategies for Electric Drive Vehicles in Warm Weather
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.
46 CFR 50.01-20 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
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46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
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46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
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46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-10-01
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46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2012 CFR
2012-10-01
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46 CFR 540.91 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
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46 CFR 525.4 - OMB control number assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
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46 CFR 525.4 - OMB control number assigned pursuant to the Paperwork Reduction Act.
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2013-10-01
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Code of Federal Regulations, 2012 CFR
2012-10-01
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Code of Federal Regulations, 2014 CFR
2014-10-01
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2011-10-01
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2010-10-01
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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.
Latitude dependence of eddy variances
NASA Technical Reports Server (NTRS)
Bowman, Kenneth P.; Bell, Thomas L.
1987-01-01
The eddy variance of a meteorological field must tend to zero at high latitudes due solely to the nature of spherical polar coordinates. The zonal averaging operator defines a length scale: the circumference of the latitude circle. When the circumference of the latitude circle is greater than the correlation length of the field, the eddy variance from transient eddies is the result of differences between statistically independent regions. When the circumference is less than the correlation length, the eddy variance is computed from points that are well correlated with each other, and so is reduced. The expansion of a field into zonal Fourier components is also influenced by the use of spherical coordinates. As is well known, a phenomenon of fixed wavelength will have different zonal wavenumbers at different latitudes. Simple analytical examples of these effects are presented along with an observational example from satellite ozone data. It is found that geometrical effects can be important even in middle latitudes.
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.
Technology Transfer Automated Retrieval System (TEKTRAN)
Genotype variant effects of calpastatin (CAST) and µ-calpain (CAPN1) on mean beef tenderness have been widely characterized. We have tested whether these genetic variants also control residual (non-genetic) variation, and subsequently total phenotypic variation, of tenderness. Observation of rare ...
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.
NASA Astrophysics Data System (ADS)
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 Id, 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 Id 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 Id 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.
Distributed Parameter Control of Selective Catalytic Reduction (SCR) for Diesel-Powered Vehicles
NASA Astrophysics Data System (ADS)
Pakravesh, Hallas
The main scope of this work is to design a distributed parameter control for SCR, which is modelled by using coupled hyperbolic and parabolic partial differential equations (PDEs). This is a boundary control problem where the control objectives are to reduce the amount of NOx emissions and ammonia slip as far as possible. Two strategies are used to control SCR. The first strategy includes using the direct transcription (DT) as the open-loop control technique. The second strategy includes the design of a closed-loop control technique that uses a new numerical method developed in this work, which combines the method of characteristics and spectral decomposition, and the characteristic-based nonlinear model predictive control (CBNMPC) as the control algorithm. The results show that the designed advanced controllers are able to achieve very high control performance in terms of NOx and ammonia slip reduction.
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.
Combined wind turbine fatigue and ultimate load reduction by individual blade control
NASA Astrophysics Data System (ADS)
Han, Y.; Leithead, W. E.
2014-06-01
If each blade of the wind turbine has individual pitch actuator, there is possibility of employing the pitch system to mitigate structural loads through advanced control methods. Previously, considerable reduction of blade lifetime equivalent fatigue loads has been achieved by Individual Blade Control (IBC) and in addition, it has also been shown the potential in blade ultimate loads reduction. However, both fatigue and ultimate loads impact on the design and life of wind turbine blades. In this paper, the design and application of IBC that concurrently reduce both blade fatigue and ultimate loads is investigated. The contributions of blade load spectral components, which are 1P, 2P and edgewise mode from blade in-plane and/or out-of-plane bending moments, are firstly explored. Four different control options for reducing various combinations of these load components are compared. In response to the different spectral peaks of both fatigue and ultimate loads, the controller has been designed so that it can act on different frequency components which vary with wind speed. The performance of the IBC controller on fatigue and ultimate load reduction is assessed by simulating a 5MW exemplar wind turbine. Simulation results show that with a proper selection of controlling inputs at different wind speed, the use of a single combined IBC can achieve satisfactory reduction on both fatigue and ultimate loads.
Vibration reduction in helicopter rotors using an active control surface located on the blade
NASA Technical Reports Server (NTRS)
Millott, T. A.; Friedmann, P. P.
1992-01-01
A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.
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…
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…
Variance of a Few Observations
ERIC Educational Resources Information Center
Joarder, Anwar H.
2009-01-01
This article demonstrates that the variance of three or four observations can be expressed in terms of the range and the first order differences of the observations. A more general result, which holds for any number of observations, is also stated.
Comparison of individual pitch and smart rotor control strategies for load reduction
NASA Astrophysics Data System (ADS)
Plumley, C.; Leithead, W.; Jamieson, P.; Bossanyi, E.; Graham, M.
2014-06-01
Load reduction is increasingly seen as an essential part of controller and wind turbine design. On large multi-MW wind turbines that experience high levels of wind shear and turbulence across the rotor, individual pitch control and smart rotor control are being considered. While individual pitch control involves adjusting the pitch of each blade individually to reduce the cyclic loadings on the rotor, smart rotor control involves activating control devices distributed along the blades to alter the local aerodynamics of the blades. Here we investigate the effectiveness of using a DQ-axis control and a distributed (independent) control for both individual pitch and trailing edge flap smart rotor control. While load reductions are similar amongst the four strategies across a wide range of variables, including blade root bending moments, yaw bearing and shaft, the pitch actuator requirements vary. The smart rotor pitch actuator has reduced travel, rates, accelerations and power requirements than that of the individual pitch controlled wind turbines. This benefit alone however would be hard to justify the added design complexities of using a smart rotor, which can be seen as an alternative to upgrading the pitch actuator and bearing. In addition, it is found that the independent control strategy is apt at roles that the collective pitch usually targets, such as tower motion and speed control, and it is perhaps here, in supplementing other systems, that the future of the smart rotor lies.
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.
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.
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.
Numerical Experiments and Flow Visualization of Drag Reduction using EMHD Control
NASA Astrophysics Data System (ADS)
O'Sullivan, Peter; Biringen, Sedat
1997-11-01
Turbulent channel flow of saltwater is studied numerically with the aim of achieving drag reduction via EMHD control using the Lorentz force of flush-mounted microtiles developed by Bandyopadhyay at NUWC. Previous numerical simulations have indicated significant local spatial deviations on the time-average skin friction (± 10%) in the vicinity of the control actuators. However, there was only negligible net viscous drag reduction (<2%). In an attempt to better understand the physics of the interaction of the controlling Lorentz force with the passage of an advecting incipient burst we have performed numerous short simulations. We scanned a wide variety of archival data from our previous simulations and extracted a good sample of burst ``candidate'' initial conditions. We then advanced these flows forward in time both with and without control. We studied the resulting burst/control dynamics with respect to control strength, duration, temporal frequency, spanwise offset and streamwise spacing of the microtiles. The spatio-temporal response of the burst and sweep structures is crucial to a successful drag reduction strategy. By identifying the key parameters in the control space we aim to narrow the focus of the design problem. We will present our findings of these numerical experiments which are based on data analysis together with flow visualization.
10 CFR 851.31 - Variance process.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Variance process. 851.31 Section 851.31 Energy DEPARTMENT OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.31 Variance process. (a) Application. Contractors desiring a variance from a safety and health standard, or portion thereof, may submit a...
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....22 Variances. EDA may approve variances to the requirements contained in this subpart, provided such variances: (a) Are consistent with the goals of the Economic Adjustment Assistance program and with an...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 7 2010-07-01 2010-07-01 false Variances. 1920.2 Section 1920.2 Labor Regulations Relating...' COMPENSATION ACT § 1920.2 Variances. (a) Variances from standards in parts 1915 through 1918 of this chapter may be granted in the same circumstances in which variances may be granted under sections 6(b)...
Salins, Serina Ruth; Kumar, Amar Nandha; Korula, Grace
2016-01-01
Introduction Fluid management in neurosurgery presents specific challenges to the anaesthesiologist. Dynamic para-meters like Pulse Pressure Variation (PPV) have been used successfully to guide fluid management. Aim To compare PPV against Central Venous Pressure (CVP) in neurosurgical patients to assess hemodynamic stability and perfusion status. Materials and Methods This was a single centre prospective randomised control trial at a tertiary care centre. A total of 60 patients undergoing intracranial tumour excision in supine and lateral positions were randomised to two groups (Group 1, CVP n=30), (Group 2, PPV n=30). Intra-operative fluid management was titrated to maintain baseline CVP in Group 1(5-10cm of water) and in Group 2 fluids were given to maintain PPV less than 13%. Acid base status, vital signs and blood loss were monitored. Results Although intra-operative hypotension and acid base changes were comparable between the groups, the patients in the CVP group had more episodes of hypotension requiring fluid boluses in the first 24 hours post surgery. {CVP group median (25, 75) 2400ml (1850, 3110) versus PPV group 2100ml (1350, 2200) p=0.03} The patients in the PPV group received more fluids than the CVP group which was clinically significant. {2250 ml (1500, 3000) versus 1500ml (1200, 2000) median (25, 75) (p=0.002)}. The blood loss was not significantly different between the groups The median blood loss in the CVP group was 600ml and in the PPV group was 850 ml; p value 0.09. Conclusion PPV can be used as a reliable index to guide fluid management in neurosurgical patients undergoing tumour excision surgery in supine and lateral positions and can effectively augment CVP as a guide to fluid management. Patients in PPV group had better hemodynamic stability and less post operative fluid requirement. PMID:27437329
Quantitative Cyber Risk Reduction Estimation Methodology for a Small Scada Control System
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.
The role of harm reduction in controlling HIV among injecting drug users
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
27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 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...
27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 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...
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...
27 CFR 25.5 - OMB control numbers assigned under the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 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...
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...
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 10 2010-01-01 2010-01-01 false Information collection requirements under the Paperwork Reduction Act; OMB control number. 1437.404 Section 1437.404 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS NONINSURED...
7 CFR 900.601 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 8 2010-01-01 2010-01-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 900.601 Section 900.601 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE GENERAL...
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...
46 CFR 110.01-2 - 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 section where identified or...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to... Management and Budget (OMB) pursuant to the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.)....
46 CFR 50.01-20 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
... for each approved agency information collection requirement. (b) Display. 46 CFR Part or Section where...) MARINE ENGINEERING GENERAL PROVISIONS Basis and Purpose of Regulations § 50.01-20 OMB control numbers... the Office of Management and Budget (OMB) pursuant to the Paperwork Reduction Act of 1980 (44...
46 CFR 110.01-2 - 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...) ELECTRICAL ENGINEERING GENERAL PROVISIONS Applicability § 110.01-2 OMB control numbers assigned pursuant to... Management and Budget (OMB) pursuant to the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.)....
FINAL REPORT. ADVANCED EXPERIMENTAL ANALYSIS OF CONTROLS ON MICROBIAL FE(III) OXIDE REDUCTION
The objectives of this research project were to refine existing models of microbiological and geochemical controls on Fe(III) oxide reduction, using laboratory reactor systems which mimic to varying degrees the physical and chemical conditions of the subsurface. Novel experimenta...
29 CFR 1917.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-07-01
... under the Paperwork Reduction Act. The following list identifies the 29 CFR citations for sections or..., 2001. The list follows: 29 CFR citation OMB control number. 1917.17(n) 1218-0196 1917.17(o) 1218-0196....4 Section 1917.4 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...
Federal Register 2010, 2011, 2012, 2013, 2014
2013-11-01
... is codifying the control numbers that have been issued by the Office of Management and Budget (OMB... numbers assigned by the Office of Management and Budget (OMB) pursuant to the Paperwork Reduction Act of... CFR 1022.43. 0145 640; 12 CFR 1022.70. 0150 318. 0156 12 CFR part 1014. 0157 12 CFR part 1015. ]...
7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 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. 58.139 0581-0110 58.148 0581-0110 58.441 0581-0110...
7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 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. 58.139 0581-0110 58.148 0581-0110 58.441 0581-0110...
7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 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. 58.139 0581-0110 58.148 0581-0110 58.441 0581-0110...
7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 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. 58.139 0581-0110 58.148 0581-0110 58.441 0581-0110...
7 CFR 58.100 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 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. 58.139 0581-0110 58.148 0581-0110 58.441 0581-0110...
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...
15 CFR 902.1 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 15 Commerce and Foreign Trade 3 2013-01-01 2013-01-01 false OMB control numbers assigned pursuant to the Paperwork Reduction Act. 902.1 Section 902.1 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE GENERAL REGULATIONS NOAA...
Generation of Control by SU(2) Reduction for the Anisotropic Ising Model
NASA Astrophysics Data System (ADS)
Delgado, F.
2016-03-01
Control of entanglement is fundamental in Quantum Information and Quantum Computation towards scalable spin-based quantum devices. For magnetic systems, Ising interaction with driven magnetic fields modifies entanglement properties of matter based quantum systems. This work presents a procedure for dynamics reduction on SU(2) subsystems using a non-local description. Some applications for Quantum Information are discussed.
49 CFR 171.6 - Control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Control numbers under the Paperwork Reduction Act. 171.6 Section 171.6 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS GENERAL INFORMATION, REGULATIONS, AND...
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...
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...
29 CFR 1918.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-07-01
....4 Section 1918.4 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING General Provisions § 1918.4 OMB control numbers under the Paperwork Reduction Act. The following list identifies the 29...
29 CFR 1918.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-07-01
....4 Section 1918.4 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING General Provisions § 1918.4 OMB control numbers under the Paperwork Reduction Act. The following list identifies the 29...
29 CFR 1917.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-07-01
... under the Paperwork Reduction Act. The following list identifies the 29 CFR citations for sections or..., 2001. The list follows: 29 CFR citation OMB control number. 1917.17(n) 1218-0196 1917.17(o) 1218-0196....4 Section 1917.4 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND...
Variance decomposition in stochastic simulators
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.
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.
Estimating the Modified Allan Variance
NASA Technical Reports Server (NTRS)
Greenhall, Charles
1995-01-01
The third-difference approach to modified Allan variance (MVAR) leads to a tractable formula for a measure of MVAR estimator confidence, the equivalent degrees of freedom (edf), in the presence of power-law phase noise. The effect of estimation stride on edf is tabulated. A simple approximation for edf is given, and its errors are tabulated. A theorem allowing conservative estimates of edf in the presence of compound noise processes is given.
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.
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.
Roden, E.E.; Urrutia, M.M.
1998-06-01
'Understanding factors which control the long-term survival and activity of Fe(III)-reducing bacteria (FeRB) in subsurface sedimentary environments is important for predicting their ability to serve as agents for bioremediation of organic and inorganic contaminants. This project seeks to refine the authors quantitative understanding of microbiological and geochemical controls on bacterial Fe(III) oxide reduction and growth of FeRB, using laboratory reactor systems which mimic to varying degrees the physical and chemical conditions of subsurface sedimentary environments. Methods for studying microbial Fe(III) oxide reduction and FeRB growth in experimental systems which incorporate advective aqueous phase flux are being developed for this purpose. These methodologies, together with an accumulating database on the kinetics of Fe(III) reduction and bacterial growth with various synthetic and natural Fe(III) oxide minerals, will be applicable to experimental and modeling studies of subsurface contaminant transformations directly coupled to or influenced by bacterial Fe(III) oxide reduction and FeRB activity. This report summarizes research accomplished after approximately 1.5 yr of a 3-yr project. A central hypothesis of the research is that advective elimination of the primary end-product of Fe(III) oxide reduction, Fe(II), will enhance the rate and extent of microbial Fe(III) oxide reduction in open experimental systems. This hypothesis is based on previous studies in the laboratory which demonstrated that association of evolved Fe(II) with oxide and FeRB cell surfaces (via adsorption or surface precipitation) is a primary cause for cessation of Fe(III) oxide reduction activity in batch culture experiments. Semicontinuous culturing was adopted as a first approach to test this basic hypothesis. Synthetic goethite or natural Fe(III) oxide-rich subsoils were used as Fe(III) sources, with the Fe(III)-reducing bacterium Shewanella alga as the test organism.'
Adaptive Vibration Reduction Controls for a Cryocooler With a Passive Balancer
NASA Technical Reports Server (NTRS)
Kopasakis, George; Cairelli, James E.; Traylor, Ryan M.
2001-01-01
In this paper an adaptive vibration reduction control (AVRC) design is described for a Stirling cryocooler combined with a passive balancer. The AVRC design was based on a mass-spring model of the cooler and balancer, and the AVRC algorithm described in this paper was based on an adaptive binary search. Results are shown comparing the baseline uncontrolled cooler with no balancer, the cooler with the balancer, and, finally, the cooler with the balancer and the AVRC. The comparison shows that it may be possible to meet stringent vibration reduction requirements without an active balancer.
NASA Technical Reports Server (NTRS)
Sissingh, G. J.; Donham, R. E.
1974-01-01
A preliminary evaluation is made of the concept of vibration reduction by properly selected oscillatory collective and cyclic control applications. The investigations are based on experimental frequency response data covering advance ratios from approximately 0.2 to 0.85. Because there was no instrumentation for the measurement of the pitch and roll vibrations, these values were obtained by properly adding up the flap-bending moments at 3.3 in. Any other quantity representing pitch/roll vibrations can be compensated for in the same fashion. The calculated control inputs required for vibration reduction stay within acceptable limits. For four of the five conditions tested they are smaller than the values used for the frequency response tests. As to be expected, the compensating controls greatly affect the blade loads, i.e., torsion, flap- and chordwise bending.
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.
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
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.
Analytic variance estimates of Swank and Fano factors
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.
Variance estimation for systematic designs in spatial surveys.
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
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.
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
A Wavelet Perspective on the Allan Variance.
Percival, Donald B
2016-04-01
The origins of the Allan variance trace back 50 years ago to two seminal papers, one by Allan (1966) and the other by Barnes (1966). Since then, the Allan variance has played a leading role in the characterization of high-performance time and frequency standards. Wavelets first arose in the early 1980s in the geophysical literature, and the discrete wavelet transform (DWT) became prominent in the late 1980s in the signal processing literature. Flandrin (1992) briefly documented a connection between the Allan variance and a wavelet transform based upon the Haar wavelet. Percival and Guttorp (1994) noted that one popular estimator of the Allan variance-the maximal overlap estimator-can be interpreted in terms of a version of the DWT now widely referred to as the maximal overlap DWT (MODWT). In particular, when the MODWT is based on the Haar wavelet, the variance of the resulting wavelet coefficients-the wavelet variance-is identical to the Allan variance when the latter is multiplied by one-half. The theory behind the wavelet variance can thus deepen our understanding of the Allan variance. In this paper, we review basic wavelet variance theory with an emphasis on the Haar-based wavelet variance and its connection to the Allan variance. We then note that estimation theory for the wavelet variance offers a means of constructing asymptotically correct confidence intervals (CIs) for the Allan variance without reverting to the common practice of specifying a power-law noise type a priori. We also review recent work on specialized estimators of the wavelet variance that are of interest when some observations are missing (gappy data) or in the presence of contamination (rogue observations or outliers). It is a simple matter to adapt these estimators to become estimators of the Allan variance. Finally we note that wavelet variances based upon wavelets other than the Haar offer interesting generalizations of the Allan variance. PMID:26529757
Randomized controlled trial of a nonpharmacologic cholesterol reduction program at the worksite.
Bruno, R; Arnold, C; Jacobson, L; Winick, M; Wynder, E
1983-07-01
Under experimental clinical conditions diet modification has been shown to reduce serum cholesterol levels. This paper reports such a positive response to a nonpharmacologic, behavioral education program at the worksite. Employees at the New York Telephone Company corporate headquarters were assigned randomly to treatment and control groups. Treatment consisted of an 8-week group cholesterol reduction program conducted during employee lunch hours. It comprised a multiple-treatment approach--food behavior change techniques combined with nutrition education, physical activity planning, and self-management skills. The treatment group showed substantial change compared with the control group at the program's completion. Those treated displayed a significant 6.4% reduction in total serum cholesterol (266 mg% average at baseline) as compared with control subjects with a corresponding decrease in high-density lipoprotein levels. A significant increase in nutrition knowledge and moderate weight loss were also documented for this group. The magnitudes of a participant's baseline serum cholesterol level and his/her reduction in percentage of ideal body weight were positively and independently correlated with percentage changes in serum cholesterol levels. Over the same period, decreases in high-density lipoprotein levels and no changes in serum cholesterol, weight, and nutrition knowledge were observed for the control group. Overall, participants in the treatment program successfully reduced the coronary heart disease risk factors of elevated cholesterol and weight. Directions for future study are suggested. PMID:6622436
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.
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
Estimating the Modified Allan Variance
NASA Technical Reports Server (NTRS)
Greenhall, Charles
1995-01-01
A paper at the 1992 FCS showed how to express the modified Allan variance (mvar) in terms of the third difference of the cumulative sum of time residuals. Although this reformulated definition was presented merely as a computational trick for simplifying the calculation of mvar estimates, it has since turned out to be a powerful theoretical tool for deriving the statistical quality of those estimates in terms of their equivalent degrees of freedom (edf), defined for an estimator V by edf V = 2(EV)2/(var V). Confidence intervals for mvar can then be constructed from levels of the appropriate 2 distribution.
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
Advanced Experiment Analysis of controls on Microbial FE(III) Oxide Reduction
Roden, Eric E.; Urrutia, Matilde M.
1999-06-01
Understanding factors which control the long-term survival and activity of Fe(III)-reducing bacteria (FeRB) in subsurface sedimentary environments is important for predicting the ability of these organisms to serve as agents for bioremediation of organic and inorganic contaminants. This project seeks to refine our quantitative understanding of microbiological and geochemical controls on bacterial Fe(III) oxide reduction and growth of FeRB, using laboratory reactor systems which mimic to varying degrees the physical and chemical conditions of subsurface sedimentary environments. Methods for studying microbial Fe(III) oxide reduction and FeRB growth in experimental systems which incorporate advective aqueous phase flux are being developed for this purpose. These methodologies, together with an accumulating database on the kinetics of Fe(III) reduction and bacterial growth with various synthetic and natural Fe(III) oxide minerals, will be applicable to experimental and modeling studies of subsurface contaminant transformations directly coupled to or influenced by bacterial Fe(III) oxide reduction activity.
A synchronous generator stabilizer design using neuro inverse controller and error reduction network
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.
Kugler, Jan-Michael; Chen, Ya-Wen; Weng, Ruifen; Cohen, Stephen M
2013-09-01
MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression that may act as buffering agents to stabilize gene-regulatory networks. Here, we identify two miRNAs that are maternally required for normal embryonic primordial germ cell development in Drosophila melanogaster. Embryos derived from miR-969 and miR-9c mutant mothers had, on average, reduced germ cell numbers. Intriguingly, this reduction correlated with an increase in the variance of this quantitative phenotypic trait. Analysis of an independent set of maternal mutant genotypes suggests that reduction of germ cell number need not lead to increased variance. Our observations are consistent with the hypothesis that miR-969 and miR-9c contribute to stabilizing the processes that control germ number, supporting phenotypic robustness. PMID:23893743
Numerical Experiments and Flow Visualization of Drag Reduction using EMHD Control
NASA Astrophysics Data System (ADS)
O'Sullivan, Peter; Biringen, Sedat
1998-11-01
Turbulent channel flow of saltwater is studied numerically with the aim of achieving drag reduction via EMHD control using the Lorentz force of flush-mounted microtiles similar to those developed by Bandyopadhyay at NUWC. Our prior numerical simulations indicated significant local spatial deviations on the time-average skin friction (± 10%) in the vicinity of the control actuators. However, there was negligible net viscous drag reduction (<1%). To better understand the physics of the interaction of the controlling Lorentz force with the passage of advecting burst events we have performed short-duration simulations. We implement a burst detection scheme based on that of Alfredsson and Johansson (1984) in order to locate and track the strongest Q2 events in the flow. Subsequently, we compare the evolution of these structures, both with and without EMHD control. We find that the specific designs we have studied do not succeed in reducing the primary Reynolds stress as a burst advects above an actuator. Via flow visualization of large-scale coherent structures we find that the classic hairpin vortices which populate the boundary layer are not significantly affected by the applied control - apart from a temporary spatial phase shift. We will present our findings of these numerical experiments and discuss the prospects for a more successful design and control strategy.
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
Variance decomposition in stochastic simulators.
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. PMID:26133418
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.
Dramatic reduction of read disturb through pulse width control in spin torque random access memory
NASA Astrophysics Data System (ADS)
Wang, Zihui; Wang, Xiaobin; Gan, Huadong; Jung, Dongha; Satoh, Kimihiro; Lin, Tsann; Zhou, Yuchen; Zhang, Jing; Huai, Yiming; Chang, Yao-Jen; Wu, Te-ho
2013-09-01
Magnetizations dynamic effect in low current read disturb region is studied both experimentally and theoretically. Dramatic read error rate reduction through read pulse width control is theoretically predicted and experimentally observed. The strong dependence of read error rate upon pulse width contrasts conventional energy barrier approach and can only be obtained considering detailed magnetization dynamics at long time thermal magnetization reversal region. Our study provides a design possibility for ultra-fast low current spin torque random access memory.
29 CFR 1917.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-07-01
... under the Paperwork Reduction Act. The following list identifies the 29 CFR citations for sections or..., 2001. The list follows: 29 CFR citation OMB control number. 1917.17(n) 1218-0196 1917.17(o) 1218-0196... 1917.45(f)(1)(i) 1218-0196 1917.45(f)(4)(iv) 1218-0196 1917.45(f)(6) 1218-0196 1917.45(g)(2)...
29 CFR 1917.4 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-07-01
... under the Paperwork Reduction Act. The following list identifies the 29 CFR citations for sections or..., 2001. The list follows: 29 CFR citation OMB control number. 1917.17(n) 1218-0196 1917.17(o) 1218-0196... 1917.45(f)(1)(i) 1218-0196 1917.45(f)(4)(iv) 1218-0196 1917.45(f)(6) 1218-0196 1917.45(g)(2)...
Variance analysis. Part I, Extending flexible budget variance analysis to acuity.
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
40 CFR 52.2183 - Variance provision.
Code of Federal Regulations, 2012 CFR
2012-07-01
...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) South Dakota § 52.2183 Variance provision. The revisions to the variance provisions in Chapter 74:26:01:31.01 of the South Dakota Air...
40 CFR 52.2183 - Variance provision.
Code of Federal Regulations, 2014 CFR
2014-07-01
...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) South Dakota § 52.2183 Variance provision. The revisions to the variance provisions in Chapter 74:26:01:31.01 of the South Dakota Air...
40 CFR 52.2183 - Variance provision.
Code of Federal Regulations, 2013 CFR
2013-07-01
...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) South Dakota § 52.2183 Variance provision. The revisions to the variance provisions in Chapter 74:26:01:31.01 of the South Dakota Air...
Theophilus, Eugenia H; Coggins, Christopher R E; Chen, Peter; Schmidt, Eckhardt; Borgerding, Michael F
2015-03-01
Tobacco toxicant-related exposure reduction is an important tool in harm reduction. Cigarette per day reduction (CPDR) occurs as smokers migrate from smoking cigarettes to using alternative tobacco/nicotine products, or quit smoking. Few reports characterize the dose-response relationships between CPDR and effects on exposure biomarkers, especially at the low end of CPD exposure (e.g., 5 CPD). We present data on CPDR by characterizing magnitudes of biomarker reductions. We present data from a well-controlled, one-week clinical confinement study in healthy smokers who were switched from smoking 19-25 CPD to smoking 20, 10, 5 or 0 CPD. Biomarkers were measured in blood, plasma, urine, and breath, and included smoke-related toxicants, urine mutagenicity, smoked cigarette filter analyses (mouth level exposure), and vital signs. Many of the biomarkers (e.g., plasma nicotine) showed strong CPDR dose-response reductions, while others (e.g., plasma thiocyanate) showed weaker dose-response reductions. Factors that lead to lower biomarker reductions include non-CPD related contributors to the measured response (e.g., other exposure sources from environment, life style, occupation; inter-individual variability). This study confirms CPDR dose-responsive biomarkers and suggests that a one-week design is appropriate for characterizing exposure reductions when smokers switch from cigarettes to new tobacco products. PMID:25572415
Minimum variance lower bound estimation and realization for desired structures.
Alipouri, Yousef; Poshtan, Javad
2014-05-01
The Minimum Variance Lower Bound (MVLB) represents the best achievable controller capability in a variance sense. Estimation and realization of MVLB for nonlinear systems confront some difficulties. Hence, almost all methods introduced so far estimate MVLB for a certain structure (e.g., NARMAX) or controller (e.g. PID). In this paper, MVLB for desired structures (not restricted to a certain type) is studied. The situation when the model is not in hand, is not accurate, or is not invertible has been considered. Moreover, in order to realize minimum variance controllers for nonlinear structures, a recursive model-free MVC design is utilized. Finally, a simulation study has been used to clarify the effectiveness of the proposed control scheme. PMID:24642244
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...
Poverty impacts of foot-and-mouth disease and the poverty reduction implications of its control.
Perry, B D; Rich, K M
2007-02-17
Foot-and-mouth disease (FMD) remains one of the most important livestock diseases of the world, given its highly infectious nature, its broad economic impacts on animal wellbeing and productivity, and its implications for successful access to domestic and export markets for livestock and products. The impacts of the disease vary markedly between developed and developing countries, and also within many developing countries. These differences in impact shape some markedly heterogeneous incentives for FMD control and eradication, which become of particular importance when setting priorities for poverty reduction in developing countries. Some consider that the benefits from FMD control accrue only to the better off in such societies and, as such, may not be a priority for investments targeted at poverty reduction. But is that view justified? Others see the control of FMD as a major development opportunity in a globalised environment. In this paper, Brian Perry and Karl Rich summarise the differential impacts of FMD and its control, and link these findings with the growing understanding of how the control of this globally important disease may contribute to the processes of pro-poor growth in certain countries of the developing world. PMID:17308024
The Validation of an Active Control Intervention for Mindfulness Based Stress Reduction (MBSR)
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
NASA Astrophysics Data System (ADS)
Pawar, Prashant M.; Jung, Sung Nam
2009-03-01
In this work, an active vibration reduction of hingeless composite rotor blades with dissimilarity is investigated using the active twist concept and the optimal control theory. The induced shear strain on the actuation mechanism by the piezoelectric constant d15 from the PZN-8% PT-based single-crystal material is used to achieve more active twisting to suppress the extra vibrations. The optimal control algorithm is based on the minimization of an objective function comprised of quadratic functions of vibratory hub loads and voltage control harmonics. The blade-to-blade dissimilarity is modeled using the stiffness degradation of composite blades. The optimal controller is applied to various possible dissimilarities arising from different damage patterns of composite blades. The governing equations of motion are derived using Hamilton's principle. The effects of composite materials and smart actuators are incorporated into the comprehensive aeroelastic analysis system. Numerical results showing the impact of addressing the blade dissimilarities on hub vibrations and voltage inputs required to suppress the vibrations are demonstrated. It is observed that all vibratory shear forces are reduced considerably and the major harmonics of moments are reduced significantly. However, the controller needs further improvement to suppress 1/rev moment loads. A mechanism to achieve vibration reduction for the dissimilar rotor system has also been identified.
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
Speed Variance and Its Influence on Accidents.
ERIC Educational Resources Information Center
Garber, Nicholas J.; Gadirau, Ravi
A study was conducted to investigate the traffic engineering factors that influence speed variance and to determine to what extent speed variance affects accident rates. Detailed analyses were carried out to relate speed variance with posted speed limit, design speeds, and other traffic variables. The major factor identified was the difference…
Code of Federal Regulations, 2013 CFR
2013-04-01
... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Variances. 1010.4 Section 1010.4 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) RADIOLOGICAL HEALTH PERFORMANCE STANDARDS FOR ELECTRONIC PRODUCTS: GENERAL General Provisions § 1010.4 Variances. (a) Criteria for variances. (1) Upon application by...
40 CFR 52.2183 - Variance provision.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Variance provision. 52.2183 Section 52...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) South Dakota § 52.2183 Variance provision. The revisions to the variance provisions in Chapter 74:26:01:31.01 of the South Dakota Air...
40 CFR 142.41 - Variance request.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Variance request. 142.41 Section 142...) NATIONAL PRIMARY DRINKING WATER REGULATIONS IMPLEMENTATION Variances Issued by the Administrator Under Section 1415(a) of the Act § 142.41 Variance request. A supplier of water may request the granting of...
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...
10 CFR 851.31 - Variance process.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 10 Energy 4 2011-01-01 2011-01-01 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...
10 CFR 851.31 - Variance process.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 4 2013-01-01 2013-01-01 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...
10 CFR 851.31 - Variance process.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 10 Energy 4 2012-01-01 2012-01-01 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...
40 CFR 52.2183 - Variance provision.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Variance provision. 52.2183 Section 52.2183 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) South Dakota § 52.2183 Variance provision. The revisions to the variance provisions...
DEMONSTRATION OF AN ADVANCED INTEGRATED CONTROL SYSTEM FOR SIMULTANEOUS EMISSIONS REDUCTION
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.
Extended Onshore Control of a Floating Wind Turbine with Wave Disturbance Reduction
NASA Astrophysics Data System (ADS)
Christiansen, S.; Knudsen, T.; Bak, T.
2014-12-01
Reaching for higher wind resources beyond the water depth limitations of monopile wind turbines, there has arisen the alternative of using floating wind turbines. But the response of wave induced loads significantly increases for floating wind turbines. Applying conventional onshore control strategies to floating wind turbines has been shown to impose negative damped oscillations in fore-aft due to the low natural frequency of the floating structure. Thus, we suggest a control loop extension of the onshore controller which stabilizes the system and reduces the wave disturbance. The results shows that when adding the suggested control loop with disturbance reduction to the system, improved performance is observed in power fluctuations, blade pitch activity, and platform oscillations.
Building virtual 3D bone fragment models to control diaphyseal fracture reduction
NASA Astrophysics Data System (ADS)
Leloup, Thierry; Schuind, Frederic; Lasudry, Nadine; Van Ham, Philippe
1999-05-01
Most fractures of the long bones are displaced and need to be surgically reduced. External fixation is often used but the crucial point of this technique is the control of reduction, which is effected with a brilliance amplifier. This system, giving instantly a x-ray image, has many disadvantages. It implies frequent irradiation to the patient and the surgical team, the visual field is limited, the supplied images are distorted and it only gives 2D information. Consequently, the reduction is occasionally imperfect although intraoperatively it appears acceptable. Using the pains inserted in each fragment as markers and an optical tracker, it is possible to build a virtual 3D model for each principal fragment and to follow its movement during the reduction. This system will supply a 3D image of the fracture in real time and without irradiation. The brilliance amplifier could then be replaced by such a virtual reality system to provide the surgeon with an accurate tool facilitating the reduction of the fracture. The purpose of this work is to show how to build the 3D model for each principal bone fragment.
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. PMID:26540265
Minimum variance beamformer weights revisited.
Moiseev, Alexander; Doesburg, Sam M; Grunau, Ruth E; Ribary, Urs
2015-10-15
Adaptive minimum variance beamformers are widely used analysis tools in MEG and EEG. When the target brain activity presents in the form of spatially localized responses, the procedure usually involves two steps. First, positions and orientations of the sources of interest are determined. Second, the filter weights are calculated and source time courses reconstructed. This last step is the object of the current study. Despite different approaches utilized at the source localization stage, basic expressions for the weights have the same form, dictated by the minimum variance condition. These classic expressions involve covariance matrix of the measured field, which includes contributions from both the sources of interest and the noise background. We show analytically that the same weights can alternatively be obtained, if the full field covariance is replaced with that of the noise, provided the beamformer points to the true sources precisely. In practice, however, a certain mismatch is always inevitable. We show that such mismatch results in partial suppression of the true sources if the traditional weights are used. To avoid this effect, the "alternative" weights based on properly estimated noise covariance should be applied at the second, source time course reconstruction step. We demonstrate mathematically and using simulated and real data that in many situations the alternative weights provide significantly better time course reconstruction quality than the traditional ones. In particular, they a) improve source-level SNR and yield more accurately reconstructed waveforms; b) provide more accurate estimates of inter-source correlations; and c) reduce the adverse influence of the source correlations on the performance of single-source beamformers, which are used most often. Importantly, the alternative weights come at no additional computational cost, as the structure of the expressions remains the same. PMID:26143207
40 CFR 142.43 - Disposition of a variance request.
Code of Federal Regulations, 2014 CFR
2014-07-01
...) Compliance (including increments of progress) by the public water system with each contaminant level... control measures as the Administrator may require for each contaminant covered by the variance. (d) The... the Administrator. (f) The proposed schedule for implementation of additional interim control...
Reduction of turbulent boundary layer induced interior noise through active impedance control.
Remington, Paul J; Curtis, Alan R D; Coleman, Ronald B; Knight, J Scott
2008-03-01
The use of a single actuator tuned to an optimum impedance to control the sound power radiated from a turbulent boundary layer (TBL) excited aircraft panel into the aircraft interior is examined. An approach to calculating the optimum impedance is defined and the limitations on the reduction in radiated power by a single actuator tuned to that impedance are examined. It is shown that there are too many degrees of freedom in the TBL and in the radiation modes of the panel to allow a single actuator to control the radiated power. However, if the panel modes are lightly damped and well separated in frequency, significant reductions are possible. The implementation of a controller that presents a desired impedance to a structure is demonstrated in a laboratory experiment, in which the structure is a mass. The performance of such a controller on an aircraft panel is shown to be effective, if the actuator impedance is similar to but not the same as the desired impedance, provided the panel resonances are well separated in frequency and lightly damped. PMID:18345832
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%).
Analysis of Variance Components for Genetic Markers with Unphased Genotypes
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. PMID:27468297
Global variance reduction for Monte Carlo reactor physics calculations
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)
ADVANTG An Automated Variance Reduction Parameter Generator, Rev. 1
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.
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.
Ma, Ming; Djanashvili, Kristina; Smith, Wilson A
2016-06-01
In this work, the effect of Cu nanowire morphology on the selective electrocatalytic reduction of CO2 is presented. Cu nanowire arrays were prepared through a two-step synthesis of Cu(OH)2 and CuO nanowire arrays on Cu foil substrates and a subsequent electrochemical reduction of the CuO nanowire arrays to Cu nanowire arrays. By this simple synthesis method, Cu nanowire array electrodes with different length and density were able to be controllably synthesized. We show that the selectivity for hydrocarbons (ethylene, n-propanol, ethane, and ethanol) on Cu nanowire array electrodes at a fixed potential can be tuned by systematically altering the Cu nanowire length and density. The nanowire morphology effect is linked to the increased local pH in the Cu nanowire arrays and a reaction scheme detailing the local pH-induced formation of C2 products is also presented by a preferred CO dimerization pathway. PMID:27098996
Investigation of passive shock wave-boundary layer control for transonic airfoil drag reduction
NASA Technical Reports Server (NTRS)
Nagamatsu, H. T.; Brower, W. B., Jr.; Bahi, L.; Ross, J.
1982-01-01
The passive drag control concept, consisting of a porous surface with a cavity beneath it, was investigated with a 12-percent-thick circular arc and a 14-percent-thick supercritical airfoil mounted on the test section bottom wall. The porous surface was positioned in the shock wave/boundary layer interaction region. The flow circulating through the porous surface, from the downstream to the upstream of the terminating shock wave location, produced a lambda shock wave system and a pressure decrease in the downstream region minimizing the flow separation. The wake impact pressure data show an appreciably drag reduction with the porous surface at transonic speeds. To determine the optimum size of porosity and cavity, tunnel tests were conducted with different airfoil porosities, cavities and flow Mach numbers. A higher drag reduction was obtained by the 2.5 percent porosity and the 1/4-inch deep cavity.
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.
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
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.
An Overview of Latest Model Reduction and Control Methods of Large Flexible Space Structures
NASA Technical Reports Server (NTRS)
Santiago, J. M.; Lange, W. J., Jr.; Jamshidi, M.
1985-01-01
The latest trends and theoretical developments involved with the modeling and control of Large Flexible Space Structures (LFSS) are described. The paper addresses first the basic problems, characteristics, and difficulties inherent in modeling and control of LFSS. Major sources of difficulties and errors are the stiffness and damping operators of the dynamic model. Extensions of Linear Quadratic Gaussian (LQG) theory as applied to LFSS are presented, including frequency-shaped cost functionals and perturbation methods. The minimum data/maximum entropy approach which uses a stochastic design model to overcome difficulties found in the LQG-based methods is described. Latest trends in system theory including balanced realization and singular-value analysis are used to determine reduced order controllers and models. Ad hoc methods such as component cost analysis and modal cost analysis are discussed in context with the closed-loop reduction problem of controller order versus performance. The minimum data/maximum entropy approach also addresses controller order versus performance. Those areas of control science and large scale systems that appear to have an important role in understanding and solving LFSS modeling and control are also identified.
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.
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.
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
Joseph, Anne M; Hecht, Stephen S; Murphy, Sharon E; Lando, Harry; Carmella, Steven G; Gross, Myron; Bliss, Robin; Le, Chap T; Hatsukami, Dorothy K
2008-03-01
Cigarette reduction has been proposed as a treatment goal for smokers who are not interested in stopping completely. This randomized controlled trial was designed to determine the effect of a smoking reduction intervention on smoking behavior, symptoms of heart disease, and biomarkers of tobacco exposure. It included 152 patients with heart disease who did not intend to stop smoking in the next 30 days. Participants were randomly assigned to smoking reduction (SR) or usual care (UC). SR subjects received counseling and nicotine replacement therapy to encourage > or =50% reduction in cigarettes per day (CPD). They were followed at 1, 3, 6, 12 and 18 months to assess smoking, heart disease symptoms, quality of life and nicotine, cotinine, carbon monoxide (CO), white blood cell (WBC) count, fibrinogen, hs-C-reactive protein (hs-CRP), F2-isoprostane, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), and 1-hydroxypyrene (1-HOP). At 6 months SR participants reduced by 10.9 CPD, compared with 7.4 CPD in UC (difference NS). At 18 months, 9/78 SR vs. 9/74 UC participants quit smoking. There were no significant differences between treatment groups in angina, quality of life or adverse events, nicotine, cotinine, CO, WBC count, fibrinogen, hs-CRP, F2-isoprostane, total NNAL or 1-HOP levels at any time point. To determine if smoking reduction, regardless of treatment condition, was associated with improved outcomes, we compared all subjects at 6 months to baseline (mean reduction in CPD from 27.4 to 18.1, p<.01). There were no significant changes in outcome variables except CO, which decreased by 5.5 ppm (p<.01). There were also no significant improvements considering only subjects who reduced by > or =50%, or those who had no history of reduction prior to enrollment in the study. The SR intervention did not significantly reduce CPD or toxin exposure, or improve smoking cessation or clinical outcomes compared to UC. These results emphasize the
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.
Reduction of blade-vortex interaction noise using higher harmonic pitch control
NASA Technical Reports Server (NTRS)
Brooks, Thomas F.; Booth, Earl R., Jr.; Jolly, J. Ralph, Jr.; Yeager, William T., Jr.; Wilbur, Matthew L.
1989-01-01
An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4 to 5 dB) were found for low-speed descent conditions, where helicopter BVI noise is most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.
Reduction of blade-vortex interaction noise through higher harmonic pitch control
NASA Technical Reports Server (NTRS)
Brooks, Thomas F.; Booth, Earl R., Jr.; Jolly, J. Ralph, Jr.; Yeager, William T., Jr.; Wilbur, Matthew L.
1990-01-01
An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4 to 5 dB) were found for low-speed descent conditions, where helicopter BVI noise is most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.
Wiederhold, Jan G; Kraemer, Stephan M; Teutsch, Nadya; Borer, Paul M; Halliday, Alex N; Kretzschmar, Ruben
2006-06-15
Iron isotope fractionation during dissolution of goethite (alpha-FeOOH) was studied in laboratory batch experiments. Proton-promoted (HCl), ligand-controlled (oxalate dark), and reductive (oxalate light) dissolution mechanisms were compared in order to understand the behavior of iron isotopes during natural weathering reactions. Multicollector ICP-MS was used to measure iron isotope ratios of dissolved iron in solution. The influence of kinetic and equilibrium isotope fractionation during different time scales of dissolution was investigated. Proton-promoted dissolution did not cause iron isotope fractionation, concurrently demonstrating the isotopic homogeneity of the goethite substrate. In contrast, both ligand-controlled and reductive dissolution of goethite resulted in significant iron isotope fractionation. The kinetic isotope effect, which caused an enrichment of light isotopes in the early dissolved fractions, was modeled with an enrichment factor for the 57Fe/ 54Fe ratio of -2.6 per thousandth between reactive surface sites and solution. Later dissolved fractions of the ligand-controlled experiments exhibit a reverse trend with a depletion of light isotopes of approximately 0.5 per thousandth in solution. We interpret this as an equilibrium isotope effect between Fe(III)-oxalate complexes in solution and the goethite surface. In conclusion, different dissolution mechanisms cause diverse iron isotope fractionation effects and likely influence the iron isotope signature of natural soil and weathering environments. PMID:16830543
Boolean Models of Genomic Regulatory Networks: Reduction Mappings, Inference, and External Control
Ivanov, Ivan
2009-01-01
Computational modeling of genomic regulation has become an important focus of systems biology and genomic signal processing for the past several years. It holds the promise to uncover both the structure and dynamical properties of the complex gene, protein or metabolic networks responsible for the cell functioning in various contexts and regimes. This, in turn, will lead to the development of optimal intervention strategies for prevention and control of disease. At the same time, constructing such computational models faces several challenges. High complexity is one of the major impediments for the practical applications of the models. Thus, reducing the size/complexity of a model becomes a critical issue in problems such as model selection, construction of tractable subnetwork models, and control of its dynamical behavior. We focus on the reduction problem in the context of two specific models of genomic regulation: Boolean networks with perturbation (BNP) and probabilistic Boolean networks (PBN). We also compare and draw a parallel between the reduction problem and two other important problems of computational modeling of genomic networks: the problem of network inference and the problem of designing external control policies for intervention/altering the dynamics of the model. PMID:20190953
Motion Detection Using Mean Normalized Temporal Variance
Chan, C W
2003-08-04
Scene-Based Wave Front Sensing uses the correlation between successive wavelets to determine the phase aberrations which cause the blurring of digital images. Adaptive Optics technology uses that information to control deformable mirrors to correct for the phase aberrations making the image clearer. The correlation between temporal subimages gives tip-tilt information. If these images do not have identical image content, tip-tilt estimations may be incorrect. Motion detection is necessary to help avoid errors initiated by dynamic subimage content. With a finely limited number of pixels per subaperature, most conventional motion detection algorithms fall apart on our subimages. Despite this fact, motion detection based on the normalized variance of individual pixels proved to be effective.
Parallel pivoting combined with parallel reduction and fill-in control
NASA Technical Reports Server (NTRS)
Alaghband, Gita
1989-01-01
Parallel algorithms for triangularization of large, sparse, and unsymmetric matrices are presented. The method combines the parallel reduction with a new parallel pivoting technique, control over generation of fill-ins and check for numerical stability, all done in parallel with the work being distributed over the active processes. The parallel pivoting technique uses the compatibility relation between pivots to identify parallel pivot candidates and uses the Markowitz number of pivots to minimize fill-in. This technique is not a preordering of the sparse matrix and is applied dynamically as the decomposition proceeds.
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.
NASA Astrophysics Data System (ADS)
Zeng, Ruijie; Cai, Ximing
2015-05-01
Understanding the temporal variance of evapotranspiration (ET) at the catchment scale remains a challenging task, because ET variance results from the complex interactions among climate, soil, vegetation, groundwater and human activities. This study extends the framework for ET variance analysis of Koster and Suarez (1999) by incorporating the water balance and the Budyko hypothesis. ET variance is decomposed into the variance/covariance of precipitation, potential ET, and catchment storage change. The contributions to ET variance from those components are quantified by long-term climate conditions (i.e., precipitation and potential ET) and catchment properties through the Budyko equation. It is found that climate determines ET variance under cool-wet, hot-dry and hot-wet conditions; while both catchment storage change and climate together control ET variance under cool-dry conditions. Thus the major factors of ET variance can be categorized based on the conditions of climate and catchment storage change. To demonstrate the analysis, both the inter- and intra-annul ET variances are assessed in the Murray-Darling Basin, and it is found that the framework corrects the over-estimation of ET variance in the arid basin. This study provides an extended theoretical framework to assess ET temporal variance under the impacts from both climate and storage change at the catchment scale.
Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling
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.
A yoga intervention for type 2 diabetes risk reduction: a pilot randomized controlled trial
2014-01-01
Background Type 2 diabetes is a major health problem in many countries including India. Yoga may be an effective type 2 diabetes prevention strategy in India, particularly given its cultural familiarity. Methods This was a parallel, randomized controlled pilot study to collect feasibility and preliminary efficacy data on yoga for diabetes risk factors among people at high risk of diabetes. Primary outcomes included: changes in BMI, waist circumference, fasting blood glucose, postprandial blood glucose, insulin, insulin resistance, blood pressure, and cholesterol. We also looked at measures of psychological well-being including changes in depression, anxiety, positive and negative affect and perceived stress. Forty-one participants with elevated fasting blood glucose in Bangalore, India were randomized to either yoga (n = 21) or a walking control (n = 20). Participants were asked to either attend yoga classes or complete monitored walking 3–6 days per week for eight weeks. Randomization and allocation was performed using computer-generated random numbers and group assignments delivered in sealed, opaque envelopes generated by off-site study staff. Data were analyzed based on intention to treat. Results This study was feasible in terms of recruitment, retention and adherence. In addition, yoga participants had significantly greater reductions in weight, waist circumference and BMI versus control (weight −0.8 ± 2.1 vs. 1.4 ± 3.6, p = 0.02; waist circumference −4.2 ± 4.8 vs. 0.7 ± 4.2, p < 0.01; BMI −0.2 ± 0.8 vs. 0.6 ± 1.6, p = 0.05). There were no between group differences in fasting blood glucose, postprandial blood glucose, insulin resistance or any other factors related to diabetes risk or psychological well-being. There were significant reductions in systolic and diastolic blood pressure, total cholesterol, anxiety, depression, negative affect and perceived stress in both the yoga intervention and walking
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.
Acupoint Stimulation on Weight Reduction for Obesity: A Randomized Sham-Controlled Study.
Yeh, Mei-Ling; Chu, Nain-Feng; Hsu, Man-Ying F; Hsu, Chin-Che; Chung, Yu-Chu
2015-12-01
Auricular acupoint stimulation has become a popular weight loss method. However, its efficacy for obesity treatment has not been fully studied. This study aimed to investigate the effect of a 10-week intervention of auricular electrical stimulation combined with auricular acupressure on weight reduction in obese outpatients. In this single-blind randomized sham-controlled study, 134 participants were randomly assigned to an experimental group receiving stimulation at true acupoints, or a sham group receiving stimulation delivered in the same manner but at sham acupoints. Each participant received nutrition counseling by a nutritionist weekly. The results showed significant differences in body mass index, blood pressure, total cholesterol, triglyceride, and leptin or adiponectin over time within the group, but not between the groups. This study could not exclude the effect of placebo and dietary consultation. Further study that adds a control group receiving no treatment is therefore needed to confirm the effects of auricular acupressure. PMID:25183702
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.
Optimal guidance and control for investigating aircraft noise-impact reduction
NASA Technical Reports Server (NTRS)
Stewart, E. C.; Carson, T. M.
1978-01-01
A methodology for investigating the reduction of community noise impact is reported. This report is concerned with the development of two models to provide data: a guidance generator and an aircraft control generator suitable for various current and advanced types of aircraft. The guidance generator produces the commanded path information from inputs chosen by an operator from a graphic scope display of a land-use map of the terminal area. The guidance generator also produces smoothing at the junctions of straight-line paths.The aircraft control generator determines the optimal set of the available controls such that the aircraft will follow the commanded path. The solutions for the control functions are given and shown to be dependent on the class of aircraft to be considered, that is, whether the thrust vector is rotatable and whether the thrust vector affects the aerodynamic forces. For the class of aircraft possessing a rotatable thrust vector, the solution is redundant; this redundancy is removed by the additional condition that the noise inpact be minimized. Information from both the guidance generator and the aircraft control generator is used by the footprint program to construct the noise footprint.
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.
Numerical study of linear feedback control for form-drag reduction
NASA Astrophysics Data System (ADS)
Dahan, Jeremy; Morgans, Aimee
2012-11-01
The present work is a numerical investigation of linear system identification and model-based feedback control methods for form-drag reduction. Large-Eddy Simulation (LES) is used to represent the flow over a simple bluff body with a sharp trailing edge, with a turbulent separation. For actuation, two types of perturbations are considered: a model of zero-net-mass-flux slot jets and momentum sources. Pressure measurements distributed over the base of the body provide the sensor information. The first part of the study will focus on the open-loop characterization of the flow. The base pressure field will be studied in relation to the wake dynamics. The effect of key actuation and flow parameters, such as actuation type, actuation location and Reynolds number, will be investigated. A black-box model of the flow response, obtained via system identification, will be examined. The second part will look at the design of robust controllers. It will be shown that uncertainties in the model and inflow conditions can be partially mitigated by the robustness of the controller. The behaviour of the feedback-controlled flow will be compared with the results achievable using open-loop forcing to draw conclusions about the success of the flow response model and the controller synthesis. PhD student in Department of Aeronautics.
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.
Code of Federal Regulations, 2011 CFR
2011-01-01
... Under the Paperwork Reduction Act: OMB Control Numbers No. Supplement No. 1 to Part 730 Commerce and... Supplement No. 1 to Part 730—Information Collection Requirements Under the Paperwork Reduction Act: OMB...-0033 License Exception, Humanitarian Donations §§ 740.12(b)(7), 762.2(b), Supp. No. 2 to part 740....
“APEC Blue”: Secondary Aerosol Reductions from Emission Controls in Beijing
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
Bangkok 2004. Drug control, human rights, and harm reduction in the age of AIDS.
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
“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.
Simulation testing of unbiasedness of variance estimators
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.
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...
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...
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...
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...
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...
Reward Pays the Cost of Noise Reduction in Motor and Cognitive Control.
Manohar, Sanjay G; Chong, Trevor T-J; Apps, Matthew A J; Batla, Amit; Stamelou, Maria; Jarman, Paul R; Bhatia, Kailash P; Husain, Masud
2015-06-29
Speed-accuracy trade-off is an intensively studied law governing almost all behavioral tasks across species. Here we show that motivation by reward breaks this law, by simultaneously invigorating movement and improving response precision. We devised a model to explain this paradoxical effect of reward by considering a new factor: the cost of control. Exerting control to improve response precision might itself come at a cost--a cost to attenuate a proportion of intrinsic neural noise. Applying a noise-reduction cost to optimal motor control predicted that reward can increase both velocity and accuracy. Similarly, application to decision-making predicted that reward reduces reaction times and errors in cognitive control. We used a novel saccadic distraction task to quantify the speed and accuracy of both movements and decisions under varying reward. Both faster speeds and smaller errors were observed with higher incentives, with the results best fitted by a model including a precision cost. Recent theories consider dopamine to be a key neuromodulator in mediating motivational effects of reward. We therefore examined how Parkinson's disease (PD), a condition associated with dopamine depletion, alters the effects of reward. Individuals with PD showed reduced reward sensitivity in their speed and accuracy, consistent in our model with higher noise-control costs. Including a cost of control over noise explains how reward may allow apparent performance limits to be surpassed. On this view, the pattern of reduced reward sensitivity in PD patients can specifically be accounted for by a higher cost for controlling noise. PMID:26096975
Reward Pays the Cost of Noise Reduction in Motor and Cognitive Control
Manohar, Sanjay G.; Chong, Trevor T.-J.; Apps, Matthew A.J.; Batla, Amit; Stamelou, Maria; Jarman, Paul R.; Bhatia, Kailash P.; Husain, Masud
2015-01-01
Summary Speed-accuracy trade-off is an intensively studied law governing almost all behavioral tasks across species. Here we show that motivation by reward breaks this law, by simultaneously invigorating movement and improving response precision. We devised a model to explain this paradoxical effect of reward by considering a new factor: the cost of control. Exerting control to improve response precision might itself come at a cost—a cost to attenuate a proportion of intrinsic neural noise. Applying a noise-reduction cost to optimal motor control predicted that reward can increase both velocity and accuracy. Similarly, application to decision-making predicted that reward reduces reaction times and errors in cognitive control. We used a novel saccadic distraction task to quantify the speed and accuracy of both movements and decisions under varying reward. Both faster speeds and smaller errors were observed with higher incentives, with the results best fitted by a model including a precision cost. Recent theories consider dopamine to be a key neuromodulator in mediating motivational effects of reward. We therefore examined how Parkinson’s disease (PD), a condition associated with dopamine depletion, alters the effects of reward. Individuals with PD showed reduced reward sensitivity in their speed and accuracy, consistent in our model with higher noise-control costs. Including a cost of control over noise explains how reward may allow apparent performance limits to be surpassed. On this view, the pattern of reduced reward sensitivity in PD patients can specifically be accounted for by a higher cost for controlling noise. PMID:26096975
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
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.
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.
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.
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). PMID:20060564
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,…
Relevance of aerodynamic modelling for load reduction control strategies of two-bladed wind turbines
NASA Astrophysics Data System (ADS)
Luhmann, B.; Cheng, P. W.
2014-06-01
A new load reduction concept is being developed for the two-bladed prototype of the Skywind 3.5MW wind turbine. Due to transport and installation advantages both offshore and in complex terrain two-bladed turbine designs are potentially more cost-effective than comparable three-bladed configurations. A disadvantage of two-bladed wind turbines is the increased fatigue loading, which is a result of asymmetrically distributed rotor forces. The innovative load reduction concept of the Skywind prototype consists of a combination of cyclic pitch control and tumbling rotor kinematics to mitigate periodic structural loading. Aerodynamic design tools must be able to model correctly the advanced dynamics of the rotor. In this paper the impact of the aerodynamic modelling approach is investigated for critical operational modes of a two-bladed wind turbine. Using a lifting line free wake vortex code (FVM) the physical limitations of the classical blade element momentum theory (BEM) can be evaluated. During regular operation vertical shear and yawed inflow are the main contributors to periodic blade load asymmetry. It is shown that the near wake interaction of the blades under such conditions is not fully captured by the correction models of BEM approach. The differing prediction of local induction causes a high fatigue load uncertainty especially for two-bladed turbines. The implementation of both cyclic pitch control and a tumbling rotor can mitigate the fatigue loading by increasing the aerodynamic and structural damping. The influence of the time and space variant vorticity distribution in the near wake is evaluated in detail for different cyclic pitch control functions and tumble dynamics respectively. It is demonstrated that dynamic inflow as well as wake blade interaction have a significant impact on the calculated blade forces and need to be accounted for by the aerodynamic modelling approach. Aeroelastic simulations are carried out using the high fidelity multi body
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
Hsu, Michael C.; Lumley, Mark A.; Stracks, John S.; Clauw, Daniel J.; Williams, David A.
2010-01-01
BACKGROUND AND OBJECTIVE Affect and how it is regulated plays a role in pain perception, maintenance of pain, and its resolution. This randomized, controlled trial evaluated an innovative affective self-awareness (ASA) intervention, which was designed to reduce pain and improve functioning in individuals with fibromyalgia. PARTICIPANTS AND METHODS Forty-five women with fibromyalgia were randomized to a manualized ASA intervention (n = 24) or wait-list control (n = 21). The intervention began with a one-time physician consultation, followed by 3 weekly, 2-h group sessions based upon a mind-body model of pain. Sessions focused on structured written emotional disclosure and emotional awareness exercises. Outcomes in both conditions were measured by a blinded assessor at baseline, post-intervention, and 6-month follow-up. MEASURES The primary outcome was pain severity (Brief Pain Inventory); secondary outcomes included tender-point threshold and physical function (SF-36 Physical Component Summary). Intent-to-treat analyses compared groups on outcomes using analysis of covariance and on the proportion of patients achieving ≥30% and ≥50% pain reduction at 6 months. RESULTS Adjusting for baseline scores, the intervention group had significantly lower pain severity (p < 0.001), higher self-reported physical function (p < 0.001), and higher tender-point threshold (p = 0.02) at 6 months compared to the control group. From baseline to 6 months, 45.8% of the ASA intervention group had ≥30% reduction in pain severity, compared to none of the controls (p < 0.001). CONCLUSIONS The affective self-awareness intervention improved pain, tenderness, and self-reported physical function for at least 6 months in women with fibromyalgia compared to wait-list control. This study suggests the value of interventions targeting emotional processes in fibromyalgia, although further studies should evaluate the efficacy of this intervention relative to active
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
Code of Federal Regulations, 2011 CFR
2011-04-01
... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Variances. 654.402 Section 654.402 Employees' 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) An employer may apply for a...
Code of Federal Regulations, 2010 CFR
2010-04-01
... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Variances. 654.402 Section 654.402 Employees' 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....
40 CFR 142.41 - Variance request.
Code of Federal Regulations, 2012 CFR
2012-07-01
... nature and duration of variance requested. (b) Relevant analytical results of water quality sampling of... relevant to ability to comply. (3) Analytical results of raw water quality relevant to the variance request... request made under § 142.40(b), a statement that the system will perform monitoring and other...
40 CFR 142.41 - Variance request.
Code of Federal Regulations, 2013 CFR
2013-07-01
... nature and duration of variance requested. (b) Relevant analytical results of water quality sampling of... relevant to ability to comply. (3) Analytical results of raw water quality relevant to the variance request... request made under § 142.40(b), a statement that the system will perform monitoring and other...
40 CFR 142.41 - Variance request.
Code of Federal Regulations, 2014 CFR
2014-07-01
... nature and duration of variance requested. (b) Relevant analytical results of water quality sampling of... relevant to ability to comply. (3) Analytical results of raw water quality relevant to the variance request... request made under § 142.40(b), a statement that the system will perform monitoring and other...
Code of Federal Regulations, 2014 CFR
2014-04-01
... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...
Code of Federal Regulations, 2012 CFR
2012-04-01
... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...
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...
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…
Code of Federal Regulations, 2010 CFR
2010-01-01
... Procedures § 1021.343 Variances. (a) Emergency actions. DOE may take an action without observing all provisions of this part or the CEQ Regulations, in accordance with 40 CFR 1506.11, in emergency situations... 10 Energy 4 2010-01-01 2010-01-01 false Variances. 1021.343 Section 1021.343 Energy DEPARTMENT...
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... § 1304.408 Variances. The Vice President or the designee thereof is authorized, following...
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…
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.
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
Lechel, U; Becker, C; Langenfeld-Jäger, G; Brix, G
2009-04-01
The aim of this study was to investigate the potential of dose reduction in multidetector computed tomography (MDCT) by current-modulated automatic exposure control (AEC) and to test the reliability of the dose estimation by the conventional CT dosimetry program CT-EXPO, when an average tube current is used. Phantom measurements were performed at a CT system with 64 detector rows for four representative examination protocols, each without and with current-modulated AEC. Organ and effective doses were measured by thermoluminescence dosimeters (TLD) at an anthropomorphic Alderson phantom and compared with those given by the calculation with CT-EXPO. The application of AEC yielded dose reductions between 27 and 40% (TLD measurements). While good linearity was observed between measured and computed effective dose values both without and with AEC, the organ doses showed large deviations between measurement and calculation. The dose to patients undergoing a MDCT examination can be reduced considerably by applying a current-modulated AEC. Dosimetric algorithms using a constant current-time product provide reliable estimates of the effective dose. PMID:18987864
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.
JV Task 104 - Risk Reduction Using Innovative Vacuum-Enhanced Plume Controls
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.
Characterization of synthetic jet actuators used for jet noise reduction by flow control
NASA Astrophysics Data System (ADS)
Zelenyak, Alexis; Berger, Zachary; Berry, Matthew; Shea, Patrick; Glauser, Mark
2013-11-01
The issue of jet noise introduces various opportunities for advancements in flow control and fluid dynamics. One such method for jet noise reduction involves the use of synthetic jet actuators as shear layer excitation on the flow produced by a fully compressible, turbulent jet. A set of eight zero-net-mass flux actuators are organized around the periphery of the jet in an actuation glove fitting on the nozzle. As some noise reduction has been achieved through the use of this actuation system, further characterization of the system is necessary to fully quantify its capabilities and understand its effect on the flow physics in the shear layer. The synthetic jet actuators are driven by several different frequencies based on the Helmholtz resonance of the cavities, with measurements taken at several locations along the actuator orifice. Velocity profiles are then constructed from the measured response using hot wire anemometry. Such experimental results provide vital insight into the flow field created by the synthetic jet actuator system, allowing for more effective modification to the actuation glove.
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.
A Computational Study of BVI Noise Reduction Using Active Twist Control
NASA Technical Reports Server (NTRS)
Fogarty, David E.; Wilbur, Matthew L.; Sekula, Martin K.
2010-01-01
The results of a computational study examining the effects of active-twist control on blade-vortex interaction (BVI) noise using the Apache Active Twist Rotor are presented. The primary goal of this activity is to reduce BVI noise during a low-speed descent flight condition using active-twist control. Rotor aeroelastic behavior was modeled using the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics code and the rotor noise was predicted using the acoustics code PSU-WOPWOP. The accuracy of the analysis was validated through comparisons with experimental acoustic data for the first generation Active Twist Rotor at an advance ratio of mu=0.14. The application of active-twist to the main rotor blade system consisted of harmonic actuation frequencies ranging from 2P to 5P, control phase angles from 0' to 360 , and tip-twist amplitudes ranging from 0.5 to 4.0 . The acoustic analysis was conducted for a single low-speed flight condition of advance ratio =0.14 and shaft angle-of-attack, c^=+6 , with BVI noise levels predicted on a flat plane of observers located 1.1 rotor diameters beneath the rotor. The results indicated reductions of up to 11dB in BVI noise using 1.25 tip-twist amplitude with negligible effects on 4P vertical hub shear.
Isolated metal active site concentration and stability control catalytic CO2 reduction selectivity.
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
Kawakami, N; Haratani, T; Iwata, N; Imanaka, Y; Murata, K; Araki, S
1999-04-01
We conducted a randomized controlled trial (RCT) to examine the effects of mailed advice on reducing psychological distress, blood pressure, serum lipids, and sick leave of workers employed in a manufacturing plant in Japan. Those who indicated higher psychological distress (defined as having GHQ scores of three or greater) in the baseline questionnaire survey (n = 226) were randomly assigned to an intervention group or a control group. Individualized letters were sent to the subjects of the intervention group, informing them of their stress levels and recommending an improvement in daily habits and other behaviors to reduce stress. Eighty-one and 77 subjects in the intervention and control groups, respectively, responded to the one-year follow-up survey. No significant intervention effect was observed for the GHQ scores, blood pressure, serum lipids, or sick leave (p > 0.05). The intervention effect was marginally significant for changes in regular breakfasts and daily alcohol consumption (p = 0.09). The intervention effect was marginally significant for the GHQ scores among those who initially did not eat breakfast regularly (p = 0.06). The study suggests that only sending mailed advice is not an effective measure for worksite stress reduction. Mailed advice which focuses on a particular subgroup (e.g., those who do not eat breakfast regularly) may be more effective. PMID:10319572
Delayed feedback control and phase reduction of unstable quasi-periodic orbits.
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. PMID:25273217
18-Degree-of-Freedom Controller Design for the ST7 Disturbance Reduction System
NASA Technical Reports Server (NTRS)
Markley, F. L.; Maghami, P. G.; Houghton, M. B.; Hsu, O. C.
2003-01-01
The Space Technology 7 experiment will perform an on-orbit system-level validation of a Disturbance Reduction System employing gravitational reference sensors and micronewton colloidal thrusters to maintain a spacecraft s position with respect to free-floating test masses in the gravitational reference sensors to less than 10 nm/dHz over the frequency range 1 to 30 mHz. This paper presents the design and analysis of the control system that closes the loop between the gravitational reference sensors and the micronewton thrusters while incorporating star tracker data at low frequencies. The effects of disturbances and actuation and measurement noise are evaluated in a eighteen-degree-of-freedom model.
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.
Encoding of natural sounds by variance of the cortical local field potential.
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
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.
Radl, B.J.; Corfman, D.; Kish, B.
1995-12-31
This paper discusses the operational experience gained from installing a neural network based supervisor setpoint control system for selected combustion parameters at Penn Power`s New Castle station. The primary goal of the program is to reduce NOx emissions while maintaining or improving heat rate. The program was jointly funded by Ohio Edison, U.S. Department of Energy (DOE) and Pegasus Technologies Corp. The target power station, Penn Power`s New Castle Unit 5, is a 1950`s vintage Babcock & Wilcox wall fired furnace with gross generation capacity of 150 MW. Before installation of the neural network system (NeuSIGHT), NOx averaged 0.75 to 0.80 lbs/mbtu at full load conditions. Previous testing reduced this from 1.0 lbs/mbtu under normal operating conditions. To meet the new Pennsylvania DER limits, which set an absolute tonnage limit on NOx, and operate for a full year, a further NOx reduction of 20% was required. The control system setup interfaced a Unix workstation to a Bailey Controls N90 DCS. The neural network and data collection/processing system resided on the workstation. New setpoints were determined by the neural network periodically. These setpoints were constrained within existing control system limits. The objective was to model the multi-dimensional and non-linear problem of NOx formation in the furnace with a neural network. Once modeled the neural network performed many {open_quote}what if{close_quote} simulations to optimize setpoints for the current operating conditions. To keep up with changes in operating conditions the neural network was set to continually learn from the most recent set of measurements. Conditioning algorithms for the input data and output setpoints were developed to handle the inherently {open_quote}noisy{close_quote} input data and to provide stable output recommendations. Test results and parameters used for combustion optimization are summarized in this paper.
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
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.
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.
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.
Yang, Jinlong; Huang, Yinjuan; Gao, Chunmei; Liu, Mingzhu; Zhang, Xinjie
2014-03-01
A novel type of reduction-sensitive starch nanoparticles was prepared via the reversed-phase microemulsion method by using crosslinker, N,N-bisacryloylcystamine (BAC) with the disulfide linkages, which was specifically cleaved by dithiothreitol (DTT). Starch nanoparticles had a spherical morphology with a small size of 40 nm in the optimal condition. The influences of process parameters (starch amount, surfactant amount and oil/water (O/W) ratio) on the size of starch nanoparticles were studied by dynamic light scattering (DLS). BAC crosslinked starch nanoparticles were degraded into oligomers with the reducing agent of DTT due to the cleavage of the disulfide linkages. A model drug 5-aminosalicylic acid (5-ASA) could be loaded efficiently into starch nanoparticles and the in vitro drug release behaviors were also studied. The results suggested that the disulfide crosslinked starch nanoparticles exhibited an accelerated drug release behavior in the presence of DTT. In vitro methyl thiazolyl tetrazolium (MTT) assays indicated that BAC crosslinked starch nanoparticles had a good biocompatibility when cocultured with human HeLa cancer cells. Hence, with excellent biocompatibility and biodegradability, and rapid drug release in response to DTT, BAC crosslinked starch nanoparticles showed a great potential as a biomaterial carrier for the application of drug controlled release. In contrast to BAC crosslinked starch nanoparticles, N,N-methylenebisacrylamine (MBA) crosslinked starch nanoparticles were prepared as the control without the disulfide linkages. PMID:24463097
NASA Astrophysics Data System (ADS)
Tsuchiya, Takeshi; Ishii, Hirokazu; Uchida, Junichi; Gomi, Hiromi; Matayoshi, Naoki; Okuno, Yoshinori
This study aims to obtain the optimal flights of a helicopter that reduce ground noise during landing approach with an optimization technique, and to conduct flight tests for confirming the effectiveness of the optimal solutions. Past experiments of Japan Aerospace Exploration Agency (JAXA) show that the noise of a helicopter varies significantly according to its flight conditions, especially depending on the flight path angle. We therefore build a simple noise model for a helicopter, in which the level of the noise generated from a point sound source is a function only of the flight path angle. Using equations of motion for flight in a vertical plane, we define optimal control problems for minimizing noise levels measured at points on the ground surface, and obtain optimal controls for specified initial altitudes, flight constraints, and wind conditions. The obtained optimal flights avoid the flight path angle which generates large noise and decrease the flight time, which are different from conventional flight. Finally, we verify the validity of the optimal flight patterns through flight experiments. The actual flights following the optimal paths resulted in noise reduction, which shows the effectiveness of the optimization.
Enhancing area of review capabilities: Implementing a variance program
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.
Rapid and controllable flame reduction of TiO2 nanowires for enhanced solar water-splitting.
Cho, In Sun; Logar, Manca; Lee, Chi Hwan; Cai, Lili; Prinz, Fritz B; Zheng, Xiaolin
2014-01-01
We report a new flame reduction method to generate controllable amount of oxygen vacancies in TiO2 nanowires that leads to nearly three times improvement in the photoelectrochemical (PEC) water-splitting performance. The flame reduction method has unique advantages of a high temperature (>1000 °C), ultrafast heating rate, tunable reduction environment, and open-atmosphere operation, so it enables rapid formation of oxygen vacancies (less than one minute) without damaging the nanowire morphology and crystallinity and is even applicable to various metal oxides. Significantly, we show that flame reduction greatly improves the saturation photocurrent densities of TiO2 nanowires (2.7 times higher), α-Fe2O3 nanowires (9.4 times higher), ZnO nanowires (2.0 times higher), and BiVO4 thin film (4.3 times higher) in comparison to untreated control samples for PEC water-splitting applications. PMID:24295287
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
Explanatory Variance in Maximal Oxygen Uptake
Robert McComb, Jacalyn J.; Roh, Daesung; Williams, James S.
2006-01-01
The purpose of this study was to develop a prediction equation that could be used to estimate maximal oxygen uptake (VO2max) from a submaximal water running protocol. Thirty-two volunteers (n =19 males, n = 13 females), ages 18 - 24 years, underwent the following testing procedures: (a) a 7-site skin fold assessment; (b) a land VO2max running treadmill test; and (c) a 6 min water running test. For the water running submaximal protocol, the participants were fitted with an Aqua Jogger Classic Uni-Sex Belt and a Polar Heart Rate Monitor; the participants’ head, shoulders, hips and feet were vertically aligned, using a modified running/bicycle motion. A regression model was used to predict VO2max. The criterion variable, VO2max, was measured using open-circuit calorimetry utilizing the Bruce Treadmill Protocol. Predictor variables included in the model were percent body fat (% BF), height, weight, gender, and heart rate following a 6 min water running protocol. Percent body fat accounted for 76% (r = -0.87, SEE = 3.27) of the variance in VO2max. No other variables significantly contributed to the explained variance in VO2max. The equation for the estimation of VO2max is as follows: VO2max ml.kg-1·min-1 = 56.14 - 0.92 (% BF). Key Points Body Fat is an important predictor of VO2 max. Individuals with low skill level in water running may shorten their stride length to avoid the onset of fatigue at higher work-loads, therefore, the net oxygen cost of the exercise cannot be controlled in inexperienced individuals in water running at fatiguing workloads. Experiments using water running protocols to predict VO2max should use individuals trained in the mechanics of water running. A submaximal water running protocol is needed in the research literature for individuals trained in the mechanics of water running, given the popularity of water running rehabilitative exercise programs and training programs. PMID:24260003
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...
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...
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...
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...
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...
Reducing variance in batch partitioning measurements
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.
Variance anisotropy in compressible 3-D MHD
NASA Astrophysics Data System (ADS)
Oughton, S.; Matthaeus, W. H.; Wan, Minping; Parashar, Tulasi
2016-06-01
We employ spectral method numerical simulations to examine the dynamical development of anisotropy of the variance, or polarization, of the magnetic and velocity field in compressible magnetohydrodynamic (MHD) turbulence. Both variance anisotropy and spectral anisotropy emerge under influence of a large-scale mean magnetic field B0; these are distinct effects, although sometimes related. Here we examine the appearance of variance parallel to B0, when starting from a highly anisotropic state. The discussion is based on a turbulence theoretic approach rather than a wave perspective. We find that parallel variance emerges over several characteristic nonlinear times, often attaining a quasi-steady level that depends on plasma beta. Consistency with solar wind observations seems to occur when the initial state is dominated by quasi-two-dimensional fluctuations.
Another Line for the Analysis of Variance
ERIC Educational Resources Information Center
Brown, Bruce L.; Harshbarger, Thad R.
1976-01-01
A test is developed for hypotheses about the grand mean in the analysis of variance, using the known relationship between the t distribution and the F distribution with 1 df (degree of freedom) for the numerator. (Author/RC)
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)
Estimation of Model Error Variances During Data Assimilation
NASA Technical Reports Server (NTRS)
Dee, Dick
2003-01-01
Data assimilation is all about understanding the error characteristics of the data and models that are used in the assimilation process. Reliable error estimates are needed to implement observational quality control, bias correction of observations and model fields, and intelligent data selection. Meaningful covariance specifications are obviously required for the analysis as well, since the impact of any single observation strongly depends on the assumed structure of the background errors. Operational atmospheric data assimilation systems still rely primarily on climatological background error covariances. To obtain error estimates that reflect both the character of the flow and the current state of the observing system, it is necessary to solve three problems: (1) how to account for the short-term evolution of errors in the initial conditions; (2) how to estimate the additional component of error caused by model defects; and (3) how to compute the error reduction in the analysis due to observational information. Various approaches are now available that provide approximate solutions to the first and third of these problems. However, the useful accuracy of these solutions very much depends on the size and character of the model errors and the ability to account for them. Model errors represent the real-world forcing of the error evolution in a data assimilation system. Clearly, meaningful model error estimates and/or statistics must be based on information external to the model itself. The most obvious information source is observational, and since the volume of available geophysical data is growing rapidly, there is some hope that a purely statistical approach to model error estimation can be viable. This requires that the observation errors themselves are well understood and quantifiable. We will discuss some of these challenges and present a new sequential scheme for estimating model error variances from observations in the context of an atmospheric data
NASA Technical Reports Server (NTRS)
Rowe, W. S.; Sebastian, J. D.; Petrarca, J. R.
1979-01-01
Results of theoretical and numerical investigations conducted to develop economical computing procedures were applied to an existing computer program that predicts unsteady aerodynamic loadings caused by leading and trailing edge control surface motions in subsonic compressible flow. Large reductions in computing costs were achieved by removing the spanwise singularity of the downwash integrand and evaluating its effect separately in closed form. Additional reductions were obtained by modifying the incremental pressure term that account for downwash singularities at control surface edges. Accuracy of theoretical predictions of unsteady loading at high reduced frequencies was increased by applying new pressure expressions that exactly satisified the high frequency boundary conditions of an oscillating control surface. Comparative computer result indicated that the revised procedures provide more accurate predictions of unsteady loadings as well as providing reduction of 50 to 80 percent in computer usage costs.
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
Variational bayesian method of estimating variance components.
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. PMID:26877207
42 CFR 488.64 - Remote facility variances for utilization review requirements.
Code of Federal Regulations, 2011 CFR
2011-10-01
... such facility or direct responsibility for the care of the patients being reviewed or, in the case of a... requesting facility will use, if a variance is granted, to assure: (1) That effective and timely control will... improve the quality of care provided to patients. (f) The request for a variance shall include: (1)...
42 CFR 488.64 - Remote facility variances for utilization review requirements.
Code of Federal Regulations, 2012 CFR
2012-10-01
... such facility or direct responsibility for the care of the patients being reviewed or, in the case of a... requesting facility will use, if a variance is granted, to assure: (1) That effective and timely control will... improve the quality of care provided to patients. (f) The request for a variance shall include: (1)...
42 CFR 488.64 - Remote facility variances for utilization review requirements.
Code of Federal Regulations, 2014 CFR
2014-10-01
... such facility or direct responsibility for the care of the patients being reviewed or, in the case of a... requesting facility will use, if a variance is granted, to assure: (1) That effective and timely control will... improve the quality of care provided to patients. (f) The request for a variance shall include: (1)...
42 CFR 488.64 - Remote facility variances for utilization review requirements.
Code of Federal Regulations, 2013 CFR
2013-10-01
... such facility or direct responsibility for the care of the patients being reviewed or, in the case of a... requesting facility will use, if a variance is granted, to assure: (1) That effective and timely control will... improve the quality of care provided to patients. (f) The request for a variance shall include: (1)...
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…
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.
Surface controlled reduction kinetics of nominally undoped polycrystalline CeO2.
Knoblauch, Nicole; Dörrer, Lars; Fielitz, Peter; Schmücker, Martin; Borchardt, Günter
2015-02-28
Ceria is an interesting material for high temperature redox applications like solar-thermal splitting of CO2 and H2O. Technical implementation and reactor design for solar-thermal redox-based fuel generation requires reliable data for the chemical surface exchange coefficient and the chemical diffusivity of oxygen. The results of thermogravimetric relaxation experiments and equilibrium oxygen isotope exchange experiments with subsequent depth profiling analysis suggest that the reduction reaction of even dense samples of pure ceria (1 mm thickness, 93% of theoretical density) with a grain size of about 20 μm is surface reaction controlled. The chemical surface exchange coefficient exhibits a negative apparent activation energy (-64 kJ mol(-1)). This finding is corroborated by similar data from literature for the tracer surface exchange coefficient. The structure of the derived expression for the apparent activation energy further suggests that the chemical surface exchange coefficient should show only a very weak dependence on temperature for ceria doped with lower valence cations. PMID:25630597
Harmonic reduction of Direct Torque Control of six-phase induction motor.
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. PMID:26948989
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.
Biostimulation of Iron Reduction and Uranium Immobilization: Microbial and Mineralogical Controls
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.
Saion, Elias; Gharibshahi, Elham; Naghavi, Kazem
2013-01-01
Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum λmax blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0) to higher energy states (n ≥ 6; Δl = 0, ±1; Δs = 0, ±1), allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology. PMID:23579953
Nox control for high nitric oxide concentration flows through combustion-driven reduction
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.
Reduction of Urogenital Schistosomiasis with an Integrated Control Project in Sudan
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
Reduced Variance for Material Sources in Implicit Monte Carlo
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.
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…
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2012-10-01
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Code of Federal Regulations, 2014 CFR
2014-10-01
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46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
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46 CFR 535.991 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
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Cheng, V.; Kashyap, S.R.; Schauer, P.R.; Kirwan, J.P.; McCrae, K.R.
2011-01-01
Background Microparticles bud from cellular elements during inflammation and are associated with vascular dysfunction related to type 2 diabetes. Although weight loss is known to reduce inflammation, the metabolic effects of bariatric surgery on microparticle concentration and composition are not known. Objectives To determine the effect of bariatric surgery on microparticle concentration and correlate these changes with clinical parameters. Setting Multispecialty group practice Methods We studied 14 obese subjects with type 2 diabetes two weeks before and at one and 12 months following bariatric surgery. Nine of the patients underwent Roux-en-Y gastric bypass and 5 received gastric restrictive surgery. Results One month following surgery, body mass index was reduced by ~10%, glycemic control improved dramatically (P < 0.01), and there was a >60% reduction in endothelial, platelet microparticles and CRP levels (P < 0.05). Tissue factor microparticles reduced by 40% ( p = 0.1). Twelve months following surgery, BMI was reduced by ~20%, glycemic control was maintained (P < 0.01), and there was a >50% reduction in monocyte microparticles compared to pre-surgery. The reduction in monocyte microparticles one month after surgery was strongly associated with the reduction in hemoglobin A1c (P < 0.05). The reduction in monocyte microparticles 12 months following surgery correlated strongly with the reduction in body mass index (P < 0.05). Conclusion The reduction in microparticles after bariatric surgery in patients with type 2 diabetes reflects an attenuation of inflammation and this mechanism may contribute to normalization of glycemic control. PMID:22093380
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
Discrimination of frequency variance for tonal sequencesa)
Byrne, Andrew J.; Viemeister, Neal F.; Stellmack, Mark A.
2014-01-01
Real-world auditory stimuli are highly variable across occurrences and sources. The present study examined the sensitivity of human listeners to differences in global stimulus variability. In a two-interval, forced-choice task, variance discrimination was measured using sequences of five 100-ms tone pulses. The frequency of each pulse was sampled randomly from a distribution that was Gaussian in logarithmic frequency. In the non-signal interval, the sampled distribution had a variance of σSTAN2, while in the signal interval, the variance of the sequence was σSIG2 (with σSIG2 > σSTAN2). The listener's task was to choose the interval with the larger variance. To constrain possible decision strategies, the mean frequency of the sampling distribution of each interval was randomly chosen for each presentation. Psychometric functions were measured for various values of σSTAN2. Although the performance was remarkably similar across listeners, overall performance was poorer than that of an ideal observer (IO) which perfectly compares interval variances. However, like the IO, Weber's Law behavior was observed, with a constant ratio of (σSIG2-σSTAN2) to σSTAN2 yielding similar performance. A model which degraded the IO with a frequency-resolution noise and a computational noise provided a reasonable fit to the real data. PMID:25480064
A new variance-based global sensitivity analysis technique
NASA Astrophysics Data System (ADS)
Wei, Pengfei; Lu, Zhenzhou; Song, Jingwen
2013-11-01
A new set of variance-based sensitivity indices, called W-indices, is proposed. Similar to the Sobol's indices, both main and total effect indices are defined. The W-main effect indices measure the average reduction of model output variance when the ranges of a set of inputs are reduced, and the total effect indices quantify the average residual variance when the ranges of the remaining inputs are reduced. Geometrical interpretations show that the W-indices gather the full information of the variance ratio function, whereas, Sobol's indices only reflect the marginal information. Then the double-loop-repeated-set Monte Carlo (MC) (denoted as DLRS MC) procedure, the double-loop-single-set MC (denoted as DLSS MC) procedure and the model emulation procedure are introduced for estimating the W-indices. It is shown that the DLRS MC procedure is suitable for computing all the W-indices despite its highly computational cost. The DLSS MC procedure is computationally efficient, however, it is only applicable for computing low order indices. The model emulation is able to estimate all the W-indices with low computational cost as long as the model behavior is correctly captured by the emulator. The Ishigami function, a modified Sobol's function and two engineering models are utilized for comparing the W- and Sobol's indices and verifying the efficiency and convergence of the three numerical methods. Results show that, for even an additive model, the W-total effect index of one input may be significantly larger than its W-main effect index. This indicates that there may exist interaction effects among the inputs of an additive model when their distribution ranges are reduced.
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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
Benthic sulfate reduction along the Chesapeake Bay central channel. II. Temporal controls
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.
Benthic sulfate reduction along the Chesapeake Bay central channel. I. Spatial trends and controls
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.
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...
Kinetics of U(VI) reduction control kinetics of U(IV) reoxidation
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.
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.
Markham, Christine M.; Tortolero, Susan R.; Peskin, Melissa Fleschler; Shegog, Ross; Thiel, Melanie; Baumler, Elizabeth R.; Addy, Robert C.; Escobar-Chaves, Soledad Liliana; Reininger, Belinda; Robin, Leah
2016-01-01
Purpose To evaluate the efficacy of two, theory-based, multi-media, middle school sexual education programs in delaying sexual initiation. Methods Three-armed, randomized controlled trial comprising fifteen urban middle schools; 1,258 predominantly African-American and Hispanic 7th grade students followed into 9th grade. Both programs included group and individualized, computer-based activities addressing psychosocial variables. The risk avoidance (RA) program met federal abstinence education guidelines; the risk reduction (RR) program emphasized abstinence and included computer-based condom skills-training. The primary outcome assessed program impact on delayed sexual initiation; secondary outcomes assessed other sexual behaviors and psychosocial outcomes. Results Participants were 59.8% female, mean age 12.6 years. Relative to controls, the RR program delayed any type of sexual initiation (oral, vaginal or anal sex) in the overall sample (adjusted odds ratio [AOR]: 0.65, 95% CI: 0.54–0.77), among females (AOR: 0.43, 95% CI: 0.31–0.60) and African-Americans (AOR: 0.38, 95% CI: 0.18–0.79). RR students also reduced unprotected sex at last intercourse (AOR: 0.67, 95% CI: 0.47–0.96), past three months’ frequency of anal sex (AOR: 0.53, 95% CI: 0.33–0.84) and unprotected vaginal sex (AOR: 0.59, 95% CI: 0.36–0.95). The RA program delayed any sexual initiation among Hispanics (AOR: 0.40, 95% CI: 0.19–0.86), reduced unprotected sex at last intercourse (AOR: 0.70, 95% CI: 0.52–0.93) but increased the number of recent vaginal sex partners (AOR: 1.69, 95% CI: 1.01–2.82). Both programs positively impacted psychosocial outcomes. Conclusions The RR program positively impacted sexually inexperienced and experienced youth; the RA program delayed initiation among Hispanics and had mixed effects among sexually experienced youth. PMID:22325134
Cross-bispectrum computation and variance estimation
NASA Technical Reports Server (NTRS)
Lii, K. S.; Helland, K. N.
1981-01-01
A method for the estimation of cross-bispectra of discrete real time series is developed. The asymptotic variance properties of the bispectrum are reviewed, and a method for the direct estimation of bispectral variance is given. The symmetry properties are described which minimize the computations necessary to obtain a complete estimate of the cross-bispectrum in the right-half-plane. A procedure is given for computing the cross-bispectrum by subdividing the domain into rectangular averaging regions which help reduce the variance of the estimates and allow easy application of the symmetry relationships to minimize the computational effort. As an example of the procedure, the cross-bispectrum of a numerically generated, exponentially distributed time series is computed and compared with theory.
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.
Inhomogeneity-induced variance of cosmological parameters
NASA Astrophysics Data System (ADS)
Wiegand, A.; Schwarz, D. J.
2012-02-01
Context. Modern cosmology relies on the assumption of large-scale isotropy and homogeneity of the Universe. However, locally the Universe is inhomogeneous and anisotropic. This raises the question of how local measurements (at the ~102 Mpc scale) can be used to determine the global cosmological parameters (defined at the ~104 Mpc scale)? Aims: We connect the questions of cosmological backreaction, cosmic averaging and the estimation of cosmological parameters and show how they relate to the problem of cosmic variance. Methods: We used Buchert's averaging formalism and determined a set of locally averaged cosmological parameters in the context of the flat Λ cold dark matter model. We calculated their ensemble means (i.e. their global value) and variances (i.e. their cosmic variance). We applied our results to typical survey geometries and focused on the study of the effects of local fluctuations of the curvature parameter. Results: We show that in the context of standard cosmology at large scales (larger than the homogeneity scale and in the linear regime), the question of cosmological backreaction and averaging can be reformulated as the question of cosmic variance. The cosmic variance is found to be highest in the curvature parameter. We propose to use the observed variance of cosmological parameters to measure the growth factor. Conclusions: Cosmological backreaction and averaging are real effects that have been measured already for a long time, e.g. by the fluctuations of the matter density contrast averaged over spheres of a certain radius. Backreaction and averaging effects from scales in the linear regime, as considered in this work, are shown to be important for the precise measurement of cosmological parameters.
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.
Wave propagation analysis using the variance matrix.
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
Variance in binary stellar population synthesis
NASA Astrophysics Data System (ADS)
Breivik, Katelyn; Larson, Shane L.
2016-03-01
In the years preceding LISA, Milky Way compact binary population simulations can be used to inform the science capabilities of the mission. Galactic population simulation efforts generally focus on high fidelity models that require extensive computational power to produce a single simulated population for each model. Each simulated population represents an incomplete sample of the functions governing compact binary evolution, thus introducing variance from one simulation to another. We present a rapid Monte Carlo population simulation technique that can simulate thousands of populations in less than a week, thus allowing a full exploration of the variance associated with a binary stellar evolution model.
Decomposition of Variance for Spatial Cox Processes
Jalilian, Abdollah; Guan, Yongtao; Waagepetersen, Rasmus
2012-01-01
Spatial Cox point processes is a natural framework for quantifying the various sources of variation governing the spatial distribution of rain forest trees. We introduce a general criterion for variance decomposition for spatial Cox processes and apply it to specific Cox process models with additive or log linear random intensity functions. We moreover consider a new and flexible class of pair correlation function models given in terms of normal variance mixture covariance functions. The proposed methodology is applied to point pattern data sets of locations of tropical rain forest trees. PMID:23599558
Tinnis, Fredrik; Volkov, Alexey; Slagbrand, Tove; Adolfsson, Hans
2016-03-24
The chemoselective reduction of amides in the presence of other more reactive reducible functional groups is a highly challenging transformation, and successful examples thereof are most valuable in synthetic organic chemistry. Only a limited number of systems have demonstrated the chemoselective reduction of amides over ketones. Until now, the aldehyde functionality has not been shown to be compatible in any catalytic reduction protocol. Described herein is a [Mo(CO)6 ]-catalyzed protocol with an unprecedented chemoselectivity and allows for the reduction of amides in the presence of aldehydes and imines. Furthermore, the system proved to be tunable by variation of the temperature, which enabled for either C-O or C-N bond cleavage that ultimately led to the isolation of both amines and aldehydes, respectively, in high chemical yields. PMID:26934055
A Simple Algorithm for Approximating Confidence on the Modified Allan Variance and the Time Variance
NASA Technical Reports Server (NTRS)
Weiss, Marc A.; Greenhall, Charles A.
1996-01-01
An approximating algorithm for computing equvalent degrees of freedom of the Modified Allan Variance and its square root, the Modified Allan Deviation (MVAR and MDEV), and the Time Variance and Time Deviation (TVAR and TDEV) is presented, along with an algorithm for approximating the inverse chi-square distribution.
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.
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
End-state comfort and joint configuration variance during reaching
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
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…
Testing Variances in Psychological and Educational Research.
ERIC Educational Resources Information Center
Ramsey, Philip H.
1994-01-01
A review of the literature indicates that the two best procedures for testing variances are one that was proposed by O'Brien (1981) and another that was proposed by Brown and Forsythe (1974). An examination of these procedures for a variety of populations confirms their robustness and indicates how optimal power can usually be obtained. (SLD)
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...
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...
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...
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...
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...
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.
Comparing the Variances of Two Dependent Groups.
ERIC Educational Resources Information Center
Wilcox, Rand R.
1990-01-01
Recently, C. E. McCulloch (1987) suggested a modification of the Morgan-Pitman test for comparing the variances of two dependent groups. This paper demonstrates that there are situations where the procedure is not robust. A subsample approach, similar to the Box-Scheffe test, and the Sandvik-Olsson procedure are also assessed. (TJH)
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…
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... Safety and Health Act of 1970 (OSH Act; 29 U.S.C. 651, 655) in 1971 (see 36 FR 7340). Paragraphs (a)(4..., construction, and use of scaffolds (61 FR 46026). In the preamble to the final rule, OSHA stated that it...
7 CFR 205.290 - Temporary variances.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 3 2011-01-01 2011-01-01 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...
Code of Federal Regulations, 2012 CFR
2012-04-01
... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Variances. 1304.408 Section 1304.408 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY APPROVAL OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS...
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 CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS...
Gasperi, Gabriele; Amidani, Lucia; Benedetti, Francesco; Boscherini, Federico; Glatzel, Pieter; Valeri, Sergio; Luches, Paola
2016-07-27
We investigated the evolution of the electronic structure of cerium oxide ultrathin epitaxial films during reduction and oxidation processes using resonant inelastic X-ray scattering at the Ce L3 absorption edge, a technique sensitive to the electronic configurations at the 4f levels and in the 5d band thanks to its high energy resolution. We used thermal treatments in high vacuum and in oxygen partial pressure to induce a controlled and reversible degree of reduction in cerium oxide ultrathin epitaxial films of different thicknesses. Two dominant spectral components contribute to the measured spectra at the different degrees of oxidation/reduction. In ultrathin films a modification of the electronic properties associated with platinum substrate proximity and with dimensionality is identified. The different electronic properties induce a higher reducibility in ultrathin films, ascribed to a decrease of the surface oxygen vacancy formation energy. PMID:27405957
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
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.
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.
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...
R package MVR for Joint Adaptive Mean-Variance Regularization and Variance Stabilization
Dazard, Jean-Eudes; Xu, Hua; Rao, J. Sunil
2015-01-01
We present an implementation in the R language for statistical computing of our recent non-parametric joint adaptive mean-variance regularization and variance stabilization procedure. The method is specifically suited for handling difficult problems posed by high-dimensional multivariate datasets (p ≫ n paradigm), such as in ‘omics’-type data, among which are that the variance is often a function of the mean, variable-specific estimators of variances are not reliable, and tests statistics have low powers due to a lack of degrees of freedom. The implementation offers a complete set of features including: (i) normalization and/or variance stabilization function, (ii) computation of mean-variance-regularized t and F statistics, (iii) generation of diverse diagnostic plots, (iv) synthetic and real ‘omics’ test datasets, (v) computationally efficient implementation, using C interfacing, and an option for parallel computing, (vi) manual and documentation on how to setup a cluster. To make each feature as user-friendly as possible, only one subroutine per functionality is to be handled by the end-user. It is available as an R package, called MVR (‘Mean-Variance Regularization’), downloadable from the CRAN. PMID:26819572
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,...
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,...
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,...
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,...
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
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...
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...
7 CFR 54.1034 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-01-01
... INSPECTION ACT (CONTINUED) MEATS, PREPARED MEATS, AND MEAT PRODUCTS (GRADING, CERTIFICATION, AND STANDARDS... collection requirements in 7 CFR part 54, subpart C, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35). 7 CFR section whererequirements are...
7 CFR 54.1034 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2011 CFR
2011-01-01
... INSPECTION ACT (CONTINUED) MEATS, PREPARED MEATS, AND MEAT PRODUCTS (GRADING, CERTIFICATION, AND STANDARDS... collection requirements in 7 CFR part 54, subpart C, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35). 7 CFR section whererequirements are...
7 CFR 54.1034 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2013 CFR
2013-01-01
... INSPECTION ACT (CONTINUED) MEATS, PREPARED MEATS, AND MEAT PRODUCTS (GRADING, CERTIFICATION, AND STANDARDS... collection requirements in 7 CFR part 54, subpart C, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35). 7 CFR section whererequirements are...
7 CFR 54.1034 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-01-01
... INSPECTION ACT (CONTINUED) MEATS, PREPARED MEATS, AND MEAT PRODUCTS (GRADING, CERTIFICATION, AND STANDARDS... collection requirements in 7 CFR part 54, subpart C, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35). 7 CFR section whererequirements are...
7 CFR 54.1034 - OMB control numbers assigned pursuant to the Paperwork Reduction Act.
Code of Federal Regulations, 2012 CFR
2012-01-01
... INSPECTION ACT (CONTINUED) MEATS, PREPARED MEATS, AND MEAT PRODUCTS (GRADING, CERTIFICATION, AND STANDARDS... collection requirements in 7 CFR part 54, subpart C, by the Office of Management and Budget pursuant to the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35). 7 CFR section whererequirements are...
SUPERVISORY CONTROL FOR PEAK REDUCTION IN COMMERCIAL BUILDINGS WHILE MAINTAINING COMFORT
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.
42 CFR 456.525 - Request for renewal of variance.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Request for renewal of variance. 456.525 Section..., and Variances for Hospitals and Mental Hospitals Ur Plan: Remote Facility Variances from Time Requirements § 456.525 Request for renewal of variance. (a) The agency must submit a request for renewal of...
10 CFR 851.32 - Action on variance requests.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Action on variance requests. 851.32 Section 851.32 Energy DEPARTMENT OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.32 Action on variance requests. (a... approval of a variance application, the Chief Health, Safety and Security Officer must forward to the...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Variances. 50-204.1a... and Application § 50-204.1a Variances. (a) Variances from standards in this part may be granted in the same circumstances in which variances may be granted under sections 6(b)(6)(A) or 6(d) of the...
21 CFR 898.14 - Exemptions and variances.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Exemptions and variances. 898.14 Section 898.14... variances. (a) A request for an exemption or variance shall be submitted in the form of a petition under... with the device; and (4) Other information justifying the exemption or variance. (b) An exemption...
10 CFR 851.30 - Consideration of variances.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Consideration of variances. 851.30 Section 851.30 Energy DEPARTMENT OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Variances § 851.30 Consideration of variances. (a) Variances shall be granted by the Under Secretary after considering the recommendation of the Chief...
42 CFR 456.521 - Conditions for granting variance requests.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Conditions for granting variance requests. 456.521..., and Variances for Hospitals and Mental Hospitals Ur Plan: Remote Facility Variances from Time Requirements § 456.521 Conditions for granting variance requests. (a) Except as described under paragraph...
S-Preconditioner for Multi-fold Data Reduction with Guaranteed User-Controlled Accuracy
Jin, Ye; Lakshminarasimhan, Sriram; Shah, Neil; Gong, Zhenhuan; Chang, C. S.; Chen, Jacqueline H.; Ethier, Stephane; Kolla, Hemanth; Ku, Seung-Hoe; Klasky, S.; Latham, Robert J.; Ross, Rob; Schuchardt, Karen L.; Samatova, Nagiza F.
2011-12-14
The growing gap between the massive amounts of data generated by petascale scientific simulation codes and the capability of system hardware and software to effectively analyze this data necessitates data reduction. Yet, the increasing data complexity challenges most, if not all, of the existing data compression methods. In fact, lossless compression techniques offer no more than 10% reduction on scientific data that we have experience with, which is widely regarded as effectively incompressible. To bridge this gap, in this paper, we advocate a transformative strategy that enables fast, accurate, and multi-fold reduction of double-precision floating-point scientific data. The intuition behind our method is inspired by an effective use of preconditioners for linear algebra solvers optimized for a particular class of computational dwarfs (e.g., dense or sparse matrices). Focusing on a commonly used multi-resolution wavelet compression technique as the underlying solver for data reduction we propose the S-preconditioner, which transforms scientific data into a form with high global regularity to ensure a significant decrease in the number of wavelet coefficients stored for a segment of data. Combined with the subsequent EQ-calibrator, our resultant method (called S-Preconditioned EQ-Calibrated Wavelets (SPEQC-WAVELETS)), robustly achieved a 4- to 5- fold data reduction while guaranteeing user-defined accuracy of reconstructed data to be within 1% point-by-point relative error, lower than 0:01 Normalized RMSE, and higher than 0:99 Pearson Correlation. In this paper, we show the results we obtained by testing our method on six petascale simulation codes including fusion, combustion, climate, astrophysics, and subsurface groundwater in addition to 13 publicly available scientific datasets. We also demonstrate that application-driven data mining tasks performed on decompressed variables or their derived quantities produce results of comparable quality with the ones for
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
Radtke, Gregg A; Hadjiconstantinou, Nicolas G
2009-05-01
We present an efficient variance-reduced particle simulation technique for solving the linearized Boltzmann transport equation in the relaxation-time approximation used for phonon, electron, and radiative transport, as well as for kinetic gas flows. The variance reduction is achieved by simulating only the deviation from equilibrium. We show that in the limit of small deviation from equilibrium of interest here, the proposed formulation achieves low relative statistical uncertainty that is also independent of the magnitude of the deviation from equilibrium, in stark contrast to standard particle simulation methods. Our results demonstrate that a space-dependent equilibrium distribution improves the variance reduction achieved, especially in the collision-dominated regime where local equilibrium conditions prevail. We also show that by exploiting the physics of relaxation to equilibrium inherent in the relaxation-time approximation, a very simple collision algorithm with a clear physical interpretation can be formulated. PMID:19518597
Heeren, G. Anita; Jemmott, John B.; Ngwane, Zolani; Mandeya, Andrew; Tyler, Joanne C.
2012-01-01
This pilot study used a randomized controlled trial to test the efficacy of an HIV risk-reduction intervention for university students in Eastern Cape Province, South Africa. Randomly selected second-year students were randomized to one of two interventions based on social cognitive theory and qualitative research: HIV risk-reduction, targeting sexual-risk behaviors; health-promotion control, targeting health behaviors unrelated to sexual risks. Participants completed behavioral assessments via audio computer-assisted self-interviewing pre-intervention, 6, and 12 months post intervention, with 97.2% retained at 12-month follow-up. Averaged over the 2 follow-ups, HIV risk-reduction intervention participants reported less unprotected vaginal intercourse and more frequent condom use than control participants, with greater efficacy in non-South Africans than South Africans. Positive changes were also observed on theoretical mediators of condom use that the intervention targeted. Interventions based on social cognitive theory integrated with qualitative information from the population may reduce sexual risk behaviors among university students in sub-Saharan Africa. PMID:22246515
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... ADMINISTRATION, DEPARTMENT OF LABOR RECORDING AND REPORTING OCCUPATIONAL INJURIES AND ILLNESSES Transition...
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... ADMINISTRATION, DEPARTMENT OF LABOR RECORDING AND REPORTING OCCUPATIONAL INJURIES AND ILLNESSES Transition...
29 CFR 1904.45 - OMB control numbers under the Paperwork Reduction Act
Code of Federal Regulations, 2014 CFR
2014-07-01
... Management and Budget under the control number listed 29 CFR citation OMB Control No. 1904.4-35 1218-0176... ADMINISTRATION, DEPARTMENT OF LABOR RECORDING AND REPORTING OCCUPATIONAL INJURIES AND ILLNESSES Transition...
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... ADMINISTRATION, DEPARTMENT OF LABOR RECORDING AND REPORTING OCCUPATIONAL INJURIES AND ILLNESSES Transition...
Factors that Control Catalytic Two- vs Four-Electron Reduction of Dioxygen by Copper Complexes
Tahsini, Laleh; Lee, Yong-Min; Ohkubo, Kei
2012-01-01
The selective two-electron reduction of O2 by one-electron reductants such as decamethylferrocene (Fc*) and octamethylferrocene (Me8Fc) is efficiently catalyzed by a binuclear Cu(II) complex ([CuII2(LO)(OH)]2+ (D1) {LO is a binucleating ligand with copper-bridging phenolate moiety} in the presence of trifluoroacetic acid (HOTF) in acetone. The protonation of the hydroxide group of [CuII2(LO)(OH)]2+ with HOTF to produce [CuII2(LO)(OTF)]2+ (D1-OTF) makes it possible for this to be reduced by two equiv of Fc* via a two-step electron transfer sequence. Reactions of the fully reduced complex [CuI2(LO)]+ (D3) with O2 in the presence of HOTF led to the low-temperature detection of the absorption spectra due to the peroxo complex ([CuII2(LO)(OO)]) (D) and the protonated hydroperoxo complex ([CuII2(LO)(OOH)]2+ (D4). No further Fc* reduction of D4 occurs, and it is instead further protonated by HOTF to yield H2O2 accompanied by regeneration of [CuII2(LO)(OTF)]2+ (D1-OTF) thus completing the catalytic cycle for the two-electron reduction of O2 by Fc*. Kinetic studies on the formation of Fc*+ under catalytic conditions as well as for separate examination of the electron transfer from Fc* to D1-OTF reveal there are two important reaction pathways operating. One is a rate-determining second reduction of D1-OTF, thus electron transfer from Fc* to a mixed-valent intermediate [CuIICuI(LO)]2+ (D2) which leads to [CuI2(LO)]+ which is coupled with O2 binding to produce [CuII2(LO)(OO)]+ (D). The other involves direct reaction of O2 with the mixed-valent compound D2 followed by rapid Fc* reduction of a putative superoxo-dicopper(II) species thus formed, producing D. PMID:22462521
Analysis of variance of microarray data.
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. PMID:16939792
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.
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.
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.
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.
Analysis of variance based on fuzzy observations
NASA Astrophysics Data System (ADS)
Nourbakhsh, M.; Mashinchi, M.; Parchami, A.
2013-04-01
Analysis of variance (ANOVA) is an important method in exploratory and confirmatory data analysis. The simplest type of ANOVA is one-way ANOVA for comparison among means of several populations. In this article, we extend one-way ANOVA to a case where observed data are fuzzy observations rather than real numbers. Two real-data examples are given to show the performance of this method.
The Theory of Variances in Equilibrium Reconstruction
Zakharov, Leonid E.; Lewandowski, Jerome; Foley, Elizabeth L.; Levinton, Fred M.; Yuh, Howard Y.; Drozdov, Vladimir; McDonald, Darren
2008-01-14
The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature.
Size-controlled synthesis of monodispersed gold nanoparticles via carbon monoxide gas reduction
2011-01-01
An in depth analysis of gold nanoparticle (AuNP) synthesis and size tuning, utilizing carbon monoxide (CO) gas as a reducing agent, is presented for the first time. The sizes of the AuNPs are tunable from ~4 to 100 nm by altering the concentration of HAuCl4 and inlet CO gas-injection flow rate. It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas. Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%. Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification. The time necessary to synthesize AuNPs, using CO, is less than 2 min. PMID:21711955
Facile and controllable electrochemical reduction of graphene oxide and its applications
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.
Minimum variance and variance of outgoing quality limit MDS-1(c1, c2) plans
NASA Astrophysics Data System (ADS)
Raju, C.; Vidya, R.
2016-06-01
In this article, the outgoing quality (OQ) and total inspection (TI) of multiple deferred state sampling plans MDS-1(c1,c2) are studied. It is assumed that the inspection is rejection rectification. Procedures for designing MDS-1(c1,c2) sampling plans with minimum variance of OQ and TI are developed. A procedure for obtaining a plan for a designated upper limit for the variance of the OQ (VOQL) is outlined.
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
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.
Hypothesis exploration with visualization of variance
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
Directional variance analysis of annual rings
NASA Astrophysics Data System (ADS)
Kumpulainen, P.; Marjanen, K.
2010-07-01
The wood quality measurement methods are of increasing importance in the wood industry. The goal is to produce more high quality products with higher marketing value than is produced today. One of the key factors for increasing the market value is to provide better measurements for increased information to support the decisions made later in the product chain. Strength and stiffness are important properties of the wood. They are related to mean annual ring width and its deviation. These indicators can be estimated from images taken from the log ends by two-dimensional power spectrum analysis. The spectrum analysis has been used successfully for images of pine. However, the annual rings in birch, for example are less distinguishable and the basic spectrum analysis method does not give reliable results. A novel method for local log end variance analysis based on Radon-transform is proposed. The directions and the positions of the annual rings can be estimated from local minimum and maximum variance estimates. Applying the spectrum analysis on the maximum local variance estimate instead of the original image produces more reliable estimate of the annual ring width. The proposed method is not limited to log end analysis only. It is usable in other two-dimensional random signal and texture analysis tasks.
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
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
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.
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
A modelling case study to evaluate control strategies for ozone reduction in Southwestern Spain
NASA Astrophysics Data System (ADS)
Castell, N.; Mantilla, E.; Salvador, R.; Stein, A. F.; Millán, M.
2009-09-01
Ozone is a strong oxidant and when certain concentrations are reached it has adverse effects on health, vegetation and materials. With the aim of protecting human health and ecosystems, European Directive 2008/50/EC establishes target values for ozone concentrations, to be achieved from 2010 onwards. In our study area, located in southwestern Spain, ozone levels regularly exceed the human health protection threshold defined in the European Directive. Indeed, this threshold was exceeded on 92 days in 2007, despite the fact that the Directive stipulates that it should not be exceeded on more than 25 days per calendar year averaged over three years. It is urgent, therefore, to reduce the current ozone levels, but because ozone is a secondary pollutant, this reduction must necessarily involve limiting the emission of its precursors, primarily nitrogen oxides (NOx) and volatile organic compounds (VOC). During the central months of the year, southwestern Spain is under strong insolation and weak synoptic forcing, promoting the development of sea breezes and mountain-induced winds and creating re-circulations of pollutants. The complex topography of the area induces the formation of vertical layers, into which the pollutants are injected and subjected to long distance transport and compensatory subsidence. The characteristics of these highly complex flows have important effects on the pollutant dispersion. In this study two ozone pollution episodes have been selected to assess the ozone response to reductions in NOx and VOC emissions from industry and traffic. The first corresponds to a typical summer episode, with the development of breezes in an anticyclonic situation with low gradient pressure and high temperatures, while the second episode presents a configuration characteristic of spring or early summer, with a smooth westerly flow and more moderate temperatures. Air pollution studies in complex terrain require the use of high-resolution models to resolve the complex
Minimum variance brain source localization for short data sequences.
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. PMID:24108457
Lemaître, Frédéric; Brevet, David; Lucas, Dominique; Vallat, Alain; Mugnier, Yves; Harvey, Pierre D
2002-05-01
The reduction mechanism of the title cluster has been investigated by means of cyclic voltammetry (CV), rotating disk electrode (RDE) voltammetry, and coulometry. The 2-electron reduction proceeds via two routes simultaneously. The first one involves two 1-electron reduction steps, followed by an iodide elimination to form the neutral Pd(3)(dppm)(3)(CO)(0) cluster (EEC mechanism). The second one is a 1-electron reduction process, followed by an iodide elimination, then by a second 1-electron step (ECE mechanism) to generate the same final product. Control over these two competitive mechanisms can be achieved by changing temperature, solvent polarity, iodide concentration, or sweep rate. The reoxidation of the Pd(3)(dppm)(3)(CO)(0) cluster in the presence of iodide proceeds via a pure ECE pathway. The overall results were interpreted with a six-member square scheme, and the cyclic and RDE voltammograms were simulated, in order to extract the reaction rate and equilibrium constants for iodide exchange for all three Pd(3)(dppm)(3)(CO)(I)(n)() (n = +1, 0, -1) adducts. PMID:11978100
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.
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.
18-Degree-of-Freedom Controller Design for the ST7 Disturbance Reduction System
NASA Technical Reports Server (NTRS)
Markley, F. L.; Maghami, P. G.; Houghton, M. B.; Hsu, O. C.
2003-01-01
This paper presents the overall design and analysis process of the spacecraft controller being developed at NASA's Goddard Space Flight Center to close the loop between the GRS and the micro-newton colloidal thrusters. The essential dynamics of the ST7-DRS are captured in a simulation including eighteen rigid-body dynamic degrees of freedom: three translations and three rotations for the spacecraft and for each test mass. The ST7 DRS comprises three control systems: the attitude control system (ACS) to maintain a sun-pointing attitude; the drag free control (DFC) to center the spacecraft about the test masses; and the test mass suspension control. This paper summarizes the control design and analysis of the ST7-DRS 18-DOF model, and is an extension of previous analyses employing a 7-DOF planar model of ST-7.
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.
15 CFR 806.18 - OMB control numbers assigned to the Paperwork Reduction Act.
Code of Federal Regulations, 2010 CFR
2010-01-01
... and Foreign Trade (Continued) BUREAU OF ECONOMIC ANALYSIS, DEPARTMENT OF COMMERCE DIRECT INVESTMENT... collection requirement. (b) Display. 15 CFR section where identified and described Current OMB control...
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
Raphael, Jon H; Duarte, Rui V; Southall, Jane L; Nightingale, Peter; Kitas, George D
2013-01-01
Objective This study aimed to investigate the efficacy of intrathecal morphine in the long term by hypothesising that a reduction of the intrathecal opioid dose following long-term administration would increase the level of pain intensity. Design Randomised, double-blind, controlled, parallel group trial. Setting Department of Pain Management, Russells Hall Hospital, Dudley, UK. Participants 24 patients with non-cancer pain implanted with morphine reservoirs were assessed for eligibility. Interventions Participants were randomly allocated to one of two parallel groups in which one of the groups had no change in morphine dose and the other group had a small reduction (20%) in dosage every week during a 10-week follow-up. Outcome Primary outcomes were visual analogue scale (VAS) pain score change and withdrawal from the study due to lack of efficacy. Results 9 of the patients assessed for eligibility declined to participate in the study. 15 patients were randomised to control (n=5) or intervention (n=10) and included in an intention-to-treat analysis. Owing to worsening of pain, seven patients withdrew from the study prematurely. None knew prior to withdrawal which arm of the study they were in, but all turned out to be in the dose-reduction arm. The calculation of dropout rates between groups indicated a significant statistical difference (p=0.026) and recruitment was ceased. The VAS change between baseline and the last observation was smaller in the control group (median, Mdn=11) than in the intervention group (Mdn=30.5), although not statistically significant, Z=−1.839, p=0.070; r=−0.47. Within groups, VAS was significantly lower at baseline (Mdn=49.5) than at the last observation (Mdn=77.5) for the reduction group, Z=−2.805, p=0.002; r=−0.627 but not for the control group (p=0.188). Conclusions This double-blind randomised controlled trial of chronic intrathecal morphine administration suggests the effectiveness of this therapy for the management of
Forming B-B Bonds by the Controlled Reduction of a Tetraaryl-diborane(6).
Kaese, Thomas; Hübner, Alexander; Bolte, Michael; Lerner, Hans-Wolfram; Wagner, Matthias
2016-05-18
Dimeric aryl(hydro)boranes can provide suitable platforms for the synthesis of boron-containing graphene flakes through reductive B-B coupling. Two-electron reduction of 1,2:1,2-bis(4,4'-di-tert-butyl-2,2'-biphenylylene)diborane(6) (4) with LiNaph/THF establishes a B-B σ bond but can be accompanied by substituent redistribution. In the singly rearranged product, Li2[6], only one 1,2-phenyl shift has occurred. The doubly ring-contracted product, Li2[7], consists of two 9H-9-borafluorenyl moieties that are linked via their boron atoms. When the amount of LiNaph/THF is increased to 4 equiv, Li2[6] is subsequently observed as the dominant species. Addition of 11 equiv of LiNaph/THF results in over-reduction with hydride elimination to afford the doubly boron-doped dibenzo[g,p]chrysene Li2[1]. In contrast, excess KC8 reduces 4 to the corresponding dihydro-dibenzo[g,p]chrysene, K2[5], with a trans-HB-BH core. Hydride abstraction from K2[5] with 1 equiv of 4 leads to K[8], in which the central B-B bond is bridged by a single hydrogen atom. K[8] is also obtained upon treatment of 4 with 1 equiv of KC8. All products have been characterized by multinuclear NMR spectroscopy and X-ray crystallography. PMID:27111640
29 CFR 1926.5 - OMB control numbers under the Paperwork Reduction Act.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 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...
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... 1926.1126 1218-0252 1926.1127 1218-0186 1926.1128 1218-0129 1926.1129 1218-0128 1926.1144...