Extending Local Canonical Correlation Analysis to Handle General Linear Contrasts for fMRI Data

Directory of Open Access Journals (Sweden)

Mingwu Jin

2012-01-01

Full Text Available Local canonical correlation analysis (CCA is a multivariate method that has been proposed to more accurately determine activation patterns in fMRI data. In its conventional formulation, CCA has several drawbacks that limit its usefulness in fMRI. A major drawback is that, unlike the general linear model (GLM, a test of general linear contrasts of the temporal regressors has not been incorporated into the CCA formalism. To overcome this drawback, a novel directional test statistic was derived using the equivalence of multivariate multiple regression (MVMR and CCA. This extension will allow CCA to be used for inference of general linear contrasts in more complicated fMRI designs without reparameterization of the design matrix and without reestimating the CCA solutions for each particular contrast of interest. With the proper constraints on the spatial coefficients of CCA, this test statistic can yield a more powerful test on the inference of evoked brain regional activations from noisy fMRI data than the conventional t-test in the GLM. The quantitative results from simulated and pseudoreal data and activation maps from fMRI data were used to demonstrate the advantage of this novel test statistic.

Holocene evolution of a wave-dominated fan-delta: Godavari delta, India

Science.gov (United States)

Saito, Y.; Nageswara Rao, K.; Nagakumar, K.; Demudu, G.; Rajawat, A.; Kubo, S.; Li, Z.

2013-12-01

The Godavari delta is one of the world's largest wave-dominated deltas. The Godavari River arises in the Western Ghats near the west coast of India and drains an area of about 3.1x10^5 km^2, flowing about 1465 km southeast across the Indian peninsula to the Bay of Bengal. The Godavari delta consists of a gentle seaward slope from its apex (12 m elevation) at Rajahmundry and a coastal beach-ridge plain over a distance of about 75 km and covers ~5200 km^2 as a delta plain. The river splits into two major distributary channels, the Gautami and the Vasishta, at a barrage constructed in the mid-1800s. The coastal environment of the deltaic coast is microtidal (~1 m mean tidal range) and wave-dominated (~1.5 m mean wave height in the June-September SW monsoon season, ~0.8 m in the NE monsoon season). Models of the Holocene evolution of the Godavari delta have changed from a zonal progradation model (e.g. Nageswara Rao & Sadakata, 1993) to a truncated cuspate delta model (Nageswara Rao et al., 2005, 2012). Twelve borehole cores (340 m total length), taken in the coastal delta plain during 2010-2013, yielded more than 100 C-14 dates. Sediment facies and C-14 dates from these and previous cores and remote-sensing data support a new delta evolution model. The Holocene coastal delta plain is divided into two parts by a set of linear beach ridges 12-14 km landward from the present shoreline in the central part of the delta. The location of the main depocenter (lobe) has shifted during the Holocene from 1) the center to 2) the west, 3) east, 4) center, 5) west, and 6) east. The linear beach ridges separate the first three from the last three stages. These lobe shifts are controlled by river channel shifts near the apex. Just as the current linear shoreline of the central part of the delta and the concave-up nearshore topography are the result of coastal erosion of a cuspate delta, the linear beach ridges indicate a former eroded shoreline. An unconformity within the deltaic

Over-production, renaturation and reconstitution of delta and epsilon subunits from chloroplast and cyanobacterial F1

NARCIS (Netherlands)

Steinemann, D.; Lill, H; Junge, Wolfgang; Engelbrecht, Siegfried

1994-01-01

We studied the functioning of chimeric F0F1-ATPases by replacing subunits delta and epsilon of spinach CF1 with their counterparts from Synechocystis sp. PCC 6803. The sequence identities between these subunits are 26 and 41%, respectively. For a systematic approach to such studies and later

Linear regression models and k-means clustering for statistical analysis of fNIRS data.

Science.gov (United States)

Bonomini, Viola; Zucchelli, Lucia; Re, Rebecca; Ieva, Francesca; Spinelli, Lorenzo; Contini, Davide; Paganoni, Anna; Torricelli, Alessandro

2015-02-01

We propose a new algorithm, based on a linear regression model, to statistically estimate the hemodynamic activations in fNIRS data sets. The main concern guiding the algorithm development was the minimization of assumptions and approximations made on the data set for the application of statistical tests. Further, we propose a K-means method to cluster fNIRS data (i.e. channels) as activated or not activated. The methods were validated both on simulated and in vivo fNIRS data. A time domain (TD) fNIRS technique was preferred because of its high performances in discriminating cortical activation and superficial physiological changes. However, the proposed method is also applicable to continuous wave or frequency domain fNIRS data sets.

Application of linear logic to simulation

Science.gov (United States)

Clarke, Thomas L.

1998-08-01

Linear logic, since its introduction by Girard in 1987 has proven expressive and powerful. Linear logic has provided natural encodings of Turing machines, Petri nets and other computational models. Linear logic is also capable of naturally modeling resource dependent aspects of reasoning. The distinguishing characteristic of linear logic is that it accounts for resources; two instances of the same variable are considered differently from a single instance. Linear logic thus must obey a form of the linear superposition principle. A proportion can be reasoned with only once, unless a special operator is applied. Informally, linear logic distinguishes two kinds of conjunction, two kinds of disjunction, and also introduces a modal storage operator that explicitly indicates propositions that can be reused. This paper discuses the application of linear logic to simulation. A wide variety of logics have been developed; in addition to classical logic, there are fuzzy logics, affine logics, quantum logics, etc. All of these have found application in simulations of one sort or another. The special characteristics of linear logic and its benefits for simulation will be discussed. Of particular interest is a connection that can be made between linear logic and simulated dynamics by using the concept of Lie algebras and Lie groups. Lie groups provide the connection between the exponential modal storage operators of linear logic and the eigen functions of dynamic differential operators. Particularly suggestive are possible relations between complexity result for linear logic and non-computability results for dynamical systems.

Iterative solution of linear equations in ODE codes. [Krylov subspaces

Energy Technology Data Exchange (ETDEWEB)

Gear, C. W.; Saad, Y.

1981-01-01

Each integration step of a stiff equation involves the solution of a nonlinear equation, usually by a quasi-Newton method that leads to a set of linear problems. Iterative methods for these linear equations are studied. Of particular interest are methods that do not require an explicit Jacobian, but can work directly with differences of function values using J congruent to f(x + delta) - f(x). Some numerical experiments using a modification of LSODE are reported. 1 figure, 2 tables.

Linear theory of equatorial spread F

International Nuclear Information System (INIS)

Hudson, M.K.; Kennel, C.F.

1975-01-01

A fluid dispersion relation for the drift and interchange (Rayleigh-Taylor) modes in a collisional plasma forms the basis for a linear theory of equatorial spread F. The collisional drift mode growth rate will exceed the growth rate of the Rayleigh-Taylor mode at short perpendicular wavelengths and density gradient scale lengths, and the drift mode can grow on top side as well as on bottom side density gradients. However, below the F peak, where spread F predominates, it is concluded that both the drift and the Rayleigh-Taylor modes contribute to the total spread F spectrum, the Rayleigh-Taylor mode dominating at long and the drift mode at short perpendicular wavelengths above the ion Larmor radius

Linear zonal atmospheric prediction for adaptive optics

Science.gov (United States)

McGuire, Patrick C.; Rhoadarmer, Troy A.; Coy, Hanna A.; Angel, J. Roger P.; Lloyd-Hart, Michael

2000-07-01

We compare linear zonal predictors of atmospheric turbulence for adaptive optics. Zonal prediction has the possible advantage of being able to interpret and utilize wind-velocity information from the wavefront sensor better than modal prediction. For simulated open-loop atmospheric data for a 2- meter 16-subaperture AO telescope with 5 millisecond prediction and a lookback of 4 slope-vectors, we find that Widrow-Hoff Delta-Rule training of linear nets and Back- Propagation training of non-linear multilayer neural networks is quite slow, getting stuck on plateaus or in local minima. Recursive Least Squares training of linear predictors is two orders of magnitude faster and it also converges to the solution with global minimum error. We have successfully implemented Amari's Adaptive Natural Gradient Learning (ANGL) technique for a linear zonal predictor, which premultiplies the Delta-Rule gradients with a matrix that orthogonalizes the parameter space and speeds up the training by two orders of magnitude, like the Recursive Least Squares predictor. This shows that the simple Widrow-Hoff Delta-Rule's slow convergence is not a fluke. In the case of bright guidestars, the ANGL, RLS, and standard matrix-inversion least-squares (MILS) algorithms all converge to the same global minimum linear total phase error (approximately 0.18 rad2), which is only approximately 5% higher than the spatial phase error (approximately 0.17 rad2), and is approximately 33% lower than the total 'naive' phase error without prediction (approximately 0.27 rad2). ANGL can, in principle, also be extended to make non-linear neural network training feasible for these large networks, with the potential to lower the predictor error below the linear predictor error. We will soon scale our linear work to the approximately 108-subaperture MMT AO system, both with simulations and real wavefront sensor data from prime focus.

Correlation of BOLD Signal with Linear and Nonlinear Patterns of EEG in Resting State EEG-Informed fMRI

Directory of Open Access Journals (Sweden)

Galina V. Portnova

2018-01-01

Full Text Available Concurrent EEG and fMRI acquisitions in resting state showed a correlation between EEG power in various bands and spontaneous BOLD fluctuations. However, there is a lack of data on how changes in the complexity of brain dynamics derived from EEG reflect variations in the BOLD signal. The purpose of our study was to correlate both spectral patterns, as linear features of EEG rhythms, and nonlinear EEG dynamic complexity with neuronal activity obtained by fMRI. We examined the relationships between EEG patterns and brain activation obtained by simultaneous EEG-fMRI during the resting state condition in 25 healthy right-handed adult volunteers. Using EEG-derived regressors, we demonstrated a substantial correlation of BOLD signal changes with linear and nonlinear features of EEG. We found the most significant positive correlation of fMRI signal with delta spectral power. Beta and alpha spectral features had no reliable effect on BOLD fluctuation. However, dynamic changes of alpha peak frequency exhibited a significant association with BOLD signal increase in right-hemisphere areas. Additionally, EEG dynamic complexity as measured by the HFD of the 2–20 Hz EEG frequency range significantly correlated with the activation of cortical and subcortical limbic system areas. Our results indicate that both spectral features of EEG frequency bands and nonlinear dynamic properties of spontaneous EEG are strongly associated with fluctuations of the BOLD signal during the resting state condition.

Simulation of linear Switched Reluctance Motor drives

OpenAIRE

Garcia Amoros, Jordi; Blanqué Molina, Balduino; Andrada Gascón, Pedro

2011-01-01

This paper presents a simulation model of linear switched reluctance motor drives. A Matlab-Simulink environment coupled with finite element analysis is used to perform the simulations. Experimental and simulation results for a double sided linear switched motor drive prototype are reported and compared to verify the simulation model.

Linear MALDI-ToF simultaneous spectrum deconvolution and baseline removal.

Science.gov (United States)

Picaud, Vincent; Giovannelli, Jean-Francois; Truntzer, Caroline; Charrier, Jean-Philippe; Giremus, Audrey; Grangeat, Pierre; Mercier, Catherine

2018-04-05

Thanks to a reasonable cost and simple sample preparation procedure, linear MALDI-ToF spectrometry is a growing technology for clinical microbiology. With appropriate spectrum databases, this technology can be used for early identification of pathogens in body fluids. However, due to the low resolution of linear MALDI-ToF instruments, robust and accurate peak picking remains a challenging task. In this context we propose a new peak extraction algorithm from raw spectrum. With this method the spectrum baseline and spectrum peaks are processed jointly. The approach relies on an additive model constituted by a smooth baseline part plus a sparse peak list convolved with a known peak shape. The model is then fitted under a Gaussian noise model. The proposed method is well suited to process low resolution spectra with important baseline and unresolved peaks. We developed a new peak deconvolution procedure. The paper describes the method derivation and discusses some of its interpretations. The algorithm is then described in a pseudo-code form where the required optimization procedure is detailed. For synthetic data the method is compared to a more conventional approach. The new method reduces artifacts caused by the usual two-steps procedure, baseline removal then peak extraction. Finally some results on real linear MALDI-ToF spectra are provided. We introduced a new method for peak picking, where peak deconvolution and baseline computation are performed jointly. On simulated data we showed that this global approach performs better than a classical one where baseline and peaks are processed sequentially. A dedicated experiment has been conducted on real spectra. In this study a collection of spectra of spiked proteins were acquired and then analyzed. Better performances of the proposed method, in term of accuracy and reproductibility, have been observed and validated by an extended statistical analysis.

Inclusive photoproduction of delta(980) and B(1235) at high xsub(F)

International Nuclear Information System (INIS)

Lassalle, J.C.; Patrick, G.N.; Storr, K.M.; Atkinson, M.; Axon, T.J.; Barberis, D.; Brodbeck, T.J.; Brookes, G.R.; Bunn, J.J.; Bussey, P.J.; Clegg, A.B.; Dainton, J.B.; Davenport, M.; Dickinson, B.; Diekmann, B.; Donnachie, A.; Ellison, R.J.; Flower, P.; Flynn, P.J.; Galbraith, W.; Heinloth, K.; Henderson, R.C.W.; Hughes-Jones, R.E.; Hutton, J.S.; Ibbotson, M.; Jakob, H.P.; Jung, M.; Kumar, B.R.; Laberrigue, J.; Lafferty, G.D.; Lane, J.B.; Levy, J.M.; Liebenau, V.; McClatchey, R.; Mercer, D.; Morris, J.A.G.; Morris, J.V.; Newton, D.; Paterson, C.; Paul, E.; Raine, C.; Reidenbach, M.; Rotscheidt, H.; Schloesser, A.; Sharp, P.H.; Skillicorn, I.O.; Smith, K.M.; Thompson, R.J.; Vaissiere, C. de la; Waite, A.P.; Worsell, M.F.; Yiou, T.P.

1984-01-01

Inclusive photoproduction of deltasup(+-)(980) and Bsup(+-0) (1235) at high xsub(F) is reported. Production of B 0 is largely due to double diffractive dissociation. The charged states are produced as leading particles, their production being described by the quark recombination picture. The relatively strong production of the delta(980) by this process is evidence that it is a anti qanti q state rather than a qqanti qanti q state. (orig.)

Low-sensitivity H ∞ filter design for linear delta operator systems with sampling time jitter

Science.gov (United States)

Guo, Xiang-Gui; Yang, Guang-Hong

2012-04-01

This article is concerned with the problem of designing H ∞ filters for a class of linear discrete-time systems with low-sensitivity to sampling time jitter via delta operator approach. Delta-domain model is used to avoid the inherent numerical ill-condition resulting from the use of the standard shift-domain model at high sampling rates. Based on projection lemma in combination with the descriptor system approach often used to solve problems related to delay, a novel bounded real lemma with three slack variables for delta operator systems is presented. A sensitivity approach based on this novel lemma is proposed to mitigate the effects of sampling time jitter on system performance. Then, the problem of designing a low-sensitivity filter can be reduced to a convex optimisation problem. An important consideration in the design of correlation filters is the optimal trade-off between the standard H ∞ criterion and the sensitivity of the transfer function with respect to sampling time jitter. Finally, a numerical example demonstrating the validity of the proposed design method is given.

Lava delta deformation as a proxy for submarine slope instability

Science.gov (United States)

Di Traglia, Federico; Nolesini, Teresa; Solari, Lorenzo; Ciampalini, Andrea; Frodella, William; Steri, Damiano; Allotta, Benedetto; Rindi, Andrea; Marini, Lorenzo; Monni, Niccolò; Galardi, Emanuele; Casagli, Nicola

2018-04-01

The instability of lava deltas is a recurrent phenomenon affecting volcanic islands, which can potentially cause secondary events such as littoral explosions (due to interactions between hot lava and seawater) and tsunamis. It has been shown that Interferometric Synthetic Aperture Radar (InSAR) is a powerful technique to forecast the collapse of newly emplaced lava deltas. This work goes further, demonstrating that the monitoring of lava deltas is a successful strategy by which to observe the long-term deformation of subaerial-submarine landslide systems on unstable volcanic flanks. In this paper, displacement measurements derived from Synthetic Aperture Radar (SAR) imagery were used to detect lava delta instability at Stromboli volcano (Italy). Recent flank eruptions (2002-2003, 2007 and 2014) affected the Sciara del Fuoco (SdF) depression, created a "stacked" lava delta, which overlies a pre-existing scar produced by a submarine-subaerial tsunamigenic landslide that occurred on 30 December 2002. Space-borne X-band COSMO-SkyMED (CSK) and C-band SENTINEL-1A (SNT) SAR data collected between February 2010 and October 2016 were processed using the SqueeSAR algorithm. The obtained ground displacement maps revealed the differential ground motion of the lava delta in both CSK and SNT datasets, identifying a stable area (characterized by less than 2 mm/y in both datasets) within the northern sector of the SdF and an unstable area (characterized by velocity fields on the order of 30 mm/y and 160 mm/y in the CSK and SNT datasets, respectively) in the central sector of the SdF. The slope stability of the offshore part of the SdF, as reconstructed based on a recently performed multibeam bathymetric survey, was evaluated using a 3D Limit Equilibrium Method (LEM). In all the simulations, Factor of Safety (F) values between 0.9 and 1.1 always characterized the submarine slope between the coastline and -250 m a.s.l. The critical surfaces for all the search volumes corresponded to

Properties of Confined Star-Branched and Linear Chains. A Monte Carlo Simulation Study

International Nuclear Information System (INIS)

Romiszowski, P.; Sikorski, A.

2004-01-01

A model of linear and star-branched polymer chains confined between two parallel and impenetrable surfaces was built. The polymer chains were restricted to a simple cubic lattice. Two macromolecular architectures of the chain: linear and star branched (consisted of f = 3 branches of equal length) were studied. The excluded volume was the only potential introduced into the model (the athermal system). Monte Carlo simulations were carried out using a sampling algorithm based on chain's local changes of conformation. The simulations were carried out at different confinement conditions: from light to high chain's compression. The scaling of chain's size with the chain length was studied and discussed. The influence of the confinement and the macromolecular architecture on the shape of a chain was studied. The differences in the shape of linear and star-branched chains were pointed out. (author)

f (T) Non-linear Massive Gravity and the Cosmic Acceleration

International Nuclear Information System (INIS)

Wu You; Chen Zu-Cheng; Wei Hao; Wang Jia-Xin

2015-01-01

Inspired by the f (R) non-linear massive gravity, we propose a new kind of modified gravity model, namely f (T) non-linear massive gravity, by adding the dRGT mass term reformulated in the vierbein formalism, to the f (T) theory. We then investigate the cosmological evolution of f (T) massive gravity, and constrain it by using the latest observational data. We find that it slightly favors a crossing of the phantom divide line from the quintessence-like phase (w_d_e > −1) to the phantom-like one (w_d_e < −1) as redshift decreases. (paper)

A Collection of Nonlinear Aircraft Simulations in MATLAB

Science.gov (United States)

Garza, Frederico R.; Morelli, Eugene A.

2003-01-01

Nonlinear six degree-of-freedom simulations for a variety of aircraft were created using MATLAB. Data for aircraft geometry, aerodynamic characteristics, mass / inertia properties, and engine characteristics were obtained from open literature publications documenting wind tunnel experiments and flight tests. Each nonlinear simulation was implemented within a common framework in MATLAB, and includes an interface with another commercially-available program to read pilot inputs and produce a three-dimensional (3-D) display of the simulated airplane motion. Aircraft simulations include the General Dynamics F-16 Fighting Falcon, Convair F-106B Delta Dart, Grumman F-14 Tomcat, McDonnell Douglas F-4 Phantom, NASA Langley Free-Flying Aircraft for Sub-scale Experimental Research (FASER), NASA HL-20 Lifting Body, NASA / DARPA X-31 Enhanced Fighter Maneuverability Demonstrator, and the Vought A-7 Corsair II. All nonlinear simulations and 3-D displays run in real time in response to pilot inputs, using contemporary desktop personal computer hardware. The simulations can also be run in batch mode. Each nonlinear simulation includes the full nonlinear dynamics of the bare airframe, with a scaled direct connection from pilot inputs to control surface deflections to provide adequate pilot control. Since all the nonlinear simulations are implemented entirely in MATLAB, user-defined control laws can be added in a straightforward fashion, and the simulations are portable across various computing platforms. Routines for trim, linearization, and numerical integration are included. The general nonlinear simulation framework and the specifics for each particular aircraft are documented.

Volumetric BOLD fMRI simulation: from neurovascular coupling to multivoxel imaging

International Nuclear Information System (INIS)

Chen, Zikuan; Calhoun, Vince

2012-01-01

The blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) modality has been numerically simulated by calculating single voxel signals. However, the observation on single voxel signals cannot provide information regarding the spatial distribution of the signals. Specifically, a single BOLD voxel signal simulation cannot answer the fundamental question: is the magnetic resonance (MR) image a replica of its underling magnetic susceptibility source? In this paper, we address this problem by proposing a multivoxel volumetric BOLD fMRI simulation model and a susceptibility expression formula for linear neurovascular coupling process, that allow us to examine the BOLD fMRI procedure from neurovascular coupling to MR image formation. Since MRI technology only senses the magnetism property, we represent a linear neurovascular-coupled BOLD state by a magnetic susceptibility expression formula, which accounts for the parameters of cortical vasculature, intravascular blood oxygenation level, and local neuroactivity. Upon the susceptibility expression of a BOLD state, we carry out volumetric BOLD fMRI simulation by calculating the fieldmap (established by susceptibility magnetization) and the complex multivoxel MR image (by intravoxel dephasing). Given the predefined susceptibility source and the calculated complex MR image, we compare the MR magnitude (phase, respectively) image with the predefined susceptibility source (the calculated fieldmap) by spatial correlation. The spatial correlation between the MR magnitude image and the magnetic susceptibility source is about 0.90 for the settings of T E = 30 ms, B 0 = 3 T, voxel size = 100 micron, vessel radius = 3 micron, and blood volume fraction = 2%. Using these parameters value, the spatial correlation between the MR phase image and the susceptibility-induced fieldmap is close to 1.00. Our simulation results show that the MR magnitude image is not an exact replica of the magnetic susceptibility

Multiple linear regression and artificial neural networks for delta-endotoxin and protease yields modelling of Bacillus thuringiensis.

Science.gov (United States)

Ennouri, Karim; Ben Ayed, Rayda; Triki, Mohamed Ali; Ottaviani, Ennio; Mazzarello, Maura; Hertelli, Fathi; Zouari, Nabil

2017-07-01

The aim of the present work was to develop a model that supplies accurate predictions of the yields of delta-endotoxins and proteases produced by B. thuringiensis var. kurstaki HD-1. Using available medium ingredients as variables, a mathematical method, based on Plackett-Burman design (PB), was employed to analyze and compare data generated by the Bootstrap method and processed by multiple linear regressions (MLR) and artificial neural networks (ANN) including multilayer perceptron (MLP) and radial basis function (RBF) models. The predictive ability of these models was evaluated by comparison of output data through the determination of coefficient (R 2 ) and mean square error (MSE) values. The results demonstrate that the prediction of the yields of delta-endotoxin and protease was more accurate by ANN technique (87 and 89% for delta-endotoxin and protease determination coefficients, respectively) when compared with MLR method (73.1 and 77.2% for delta-endotoxin and protease determination coefficients, respectively), suggesting that the proposed ANNs, especially MLP, is a suitable new approach for determining yields of bacterial products that allow us to make more appropriate predictions in a shorter time and with less engineering effort.

3-D electromagnetic plasma particle simulations on the Intel Delta parallel computer

International Nuclear Information System (INIS)

Wang, J.; Liewer, P.C.

1994-01-01

A three-dimensional electromagnetic PIC code has been developed on the 512 node Intel Touchstone Delta MIMD parallel computer. This code is based on the General Concurrent PIC algorithm which uses a domain decomposition to divide the computation among the processors. The 3D simulation domain can be partitioned into 1-, 2-, or 3-dimensional sub-domains. Particles must be exchanged between processors as they move among the subdomains. The Intel Delta allows one to use this code for very-large-scale simulations (i.e. over 10 8 particles and 10 6 grid cells). The parallel efficiency of this code is measured, and the overall code performance on the Delta is compared with that on Cray supercomputers. It is shown that their code runs with a high parallel efficiency of ≥ 95% for large size problems. The particle push time achieved is 115 nsecs/particle/time step for 162 million particles on 512 nodes. Comparing with the performance on a single processor Cray C90, this represents a factor of 58 speedup. The code uses a finite-difference leap frog method for field solve which is significantly more efficient than fast fourier transforms on parallel computers. The performance of this code on the 128 node Cray T3D will also be discussed

Improvements on nonlinear gyrokinetic particle simulations based on δf-discretization scheme

International Nuclear Information System (INIS)

Zorat, R.; Tessarotto, M.

1998-01-01

In this work various issues regarding the definition of improved theoretical models appropriate to describe the dynamics of confined magnetoplasmas by particle simulation methods are proposed. These concern in particular an improved non linear δf discretization scheme and the treatment of binary, i.e. Coulomb, and collective interactions. (orig.)

Impact of the [delta]F508 Mutation in First Nucleotide-binding Domain of Human Cystic Fibrosis Transmembrane Conductance Regulator on Domain Folding and Structure

Energy Technology Data Exchange (ETDEWEB)

Lewis, Hal A.; Zhao, Xun; Wang, Chi; Sauder, J. Michael; Rooney, Isabelle; Noland, Brian W.; Lorimer, Don; Kearins, Margaret C.; Conners, Kris; Condon, Brad; Maloney, Peter C.; Guggino, William B.; Hunt, John F.; Emtage, Spencer (SG); (Columbia); (JHU)

2010-07-19

Cystic fibrosis is caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR), commonly the deletion of residue Phe-508 (DeltaF508) in the first nucleotide-binding domain (NBD1), which results in a severe reduction in the population of functional channels at the epithelial cell surface. Previous studies employing incomplete NBD1 domains have attributed this to aberrant folding of DeltaF508 NBD1. We report structural and biophysical studies on complete human NBD1 domains, which fail to demonstrate significant changes of in vitro stability or folding kinetics in the presence or absence of the DeltaF508 mutation. Crystal structures show minimal changes in protein conformation but substantial changes in local surface topography at the site of the mutation, which is located in the region of NBD1 believed to interact with the first membrane spanning domain of CFTR. These results raise the possibility that the primary effect of DeltaF508 is a disruption of proper interdomain interactions at this site in CFTR rather than interference with the folding of NBD1. Interestingly, increases in the stability of NBD1 constructs are observed upon introduction of second-site mutations that suppress the trafficking defect caused by the DeltaF508 mutation, suggesting that these suppressors might function indirectly by improving the folding efficiency of NBD1 in the context of the full-length protein. The human NBD1 structures also solidify the understanding of CFTR regulation by showing that its two protein segments that can be phosphorylated both adopt multiple conformations that modulate access to the ATPase active site and functional interdomain interfaces.

Numerical simulation of incidence and sweep effects on delta wing vortex breakdown

Science.gov (United States)

Ekaterinaris, J. A.; Schiff, Lewis B.

1994-01-01

The structure of the vortical flowfield over delta wings at high angles of attack was investigated. Three-dimensional Navier-Stokes numerical simulations were carried out to predict the complex leeward-side flowfield characteristics, including leading-edge separation, secondary separation, and vortex breakdown. Flows over a 75- and a 63-deg sweep delta wing with sharp leading edges were investigated and compared with available experimental data. The effect of variation of circumferential grid resolution grid resolution in the vicinity of the wing leading edge on the accuracy of the solutions was addressed. Furthermore, the effect of turbulence modeling on the solutions was investigated. The effects of variation of angle of attack on the computed vortical flow structure for the 75-deg sweep delta wing were examined. At moderate angles of attack no vortex breakdown was observed. When a critical angle of attack was reached, bubble-type vortex breakdown was found. With further increase in angle of attack, a change from bubble-type breakdown to spiral-type vortex breakdown was predicted by the numerical solution. The effects of variation of sweep angle and freestream Mach number were addressed with the solutions on a 63-deg sweep delta wing.

Nonlinear vs. linear biasing in Trp-cage folding simulations

Energy Technology Data Exchange (ETDEWEB)

Spiwok, Vojtěch, E-mail: spiwokv@vscht.cz; Oborský, Pavel; Králová, Blanka [Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Technická 3, Prague 6 166 28 (Czech Republic); Pazúriková, Jana [Institute of Computer Science, Masaryk University, Botanická 554/68a, 602 00 Brno (Czech Republic); Křenek, Aleš [Institute of Computer Science, Masaryk University, Botanická 554/68a, 602 00 Brno (Czech Republic); Center CERIT-SC, Masaryk Univerzity, Šumavská 416/15, 602 00 Brno (Czech Republic)

2015-03-21

Biased simulations have great potential for the study of slow processes, including protein folding. Atomic motions in molecules are nonlinear, which suggests that simulations with enhanced sampling of collective motions traced by nonlinear dimensionality reduction methods may perform better than linear ones. In this study, we compare an unbiased folding simulation of the Trp-cage miniprotein with metadynamics simulations using both linear (principle component analysis) and nonlinear (Isomap) low dimensional embeddings as collective variables. Folding of the mini-protein was successfully simulated in 200 ns simulation with linear biasing and non-linear motion biasing. The folded state was correctly predicted as the free energy minimum in both simulations. We found that the advantage of linear motion biasing is that it can sample a larger conformational space, whereas the advantage of nonlinear motion biasing lies in slightly better resolution of the resulting free energy surface. In terms of sampling efficiency, both methods are comparable.

Superconducting bandpass delta-sigma modulator

International Nuclear Information System (INIS)

Bulzacchelli, J.F.; Lee, H.-S.; Misewich, J.A.; Ketchen, M.B.

1999-01-01

Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS. (author)

Quantitative analysis and simulation of land use changes in the Pearl River Delta, China

Science.gov (United States)

Zhang, Honghui; Zeng, Yongnian; Zou, Bin; Xiao, Pengfeng; Hu, Deyong; Peng, Jianchao

2007-06-01

This paper analyzes and simulates the land use changes in the Pearl River Delta, China, using Longgang City as a case study. The region has pioneered the nation in economic development and urbanization process. Tremendous land use changes have been witnessed since the economic reform in 1978. Land use changes are analyzed and simulated by using stochastic cellular automata model, land use trajectories analysis, spatial indices and multi-temporal TM images of Longgang City (TM1987, TM1991, TM1995, TM1999, TM2003, TM2005) in order to understand how urbanization has transformed the non-urban land to urban land and estimate the consequent environment and ecological impacts in this region. The analysis and simulation results show that urban land continues to sprawl along road and fringe of towns, and concomitant to this development is the loss of agricultural land, orchards and fish ponds. This study provides new evidence with spatial details about the uneven land development in the Pearl River Delta.

Electronic Structure of TlBa2CaCu2O(7-Delta)

Science.gov (United States)

Vasquez, R. P.; Novikov, D. L.; Freeman, A. J.; Siegal, M. P.

1997-01-01

The core levels of TlBa2CaCu2O(7-delta) (Tl-1212) epitaxial films have been measured with X-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin-tin-orbital band-structure method and measured with XPS. The calculations show that a van Hove singularity (VHS) lies above the Fermi level (E(sub F)) for the stoichiometric compound (delta = 0.5), while for 50% oxygen vacancies in the Tl-O layer (delta = 0.5) E(sub F) is in close proximity to the VHS. Samples annealed in nitrogen (to reduce the hole overdoping by the removal of oxygen) exhibit higher core-level binding energies and a higher T(sub c), consistent with a shift of E(sub F) closer to the VHS. Comparisons are made to the core levels and valence bands of Tl2Ba2CaCu2O(8 + delta)(Tl-2212) and HgBa2CaCu2O)6 + delta) (Hg- 1212). The similarity of the Cu 2p(sub 3/2) spectra for Tl-1212 and Tl-2212 indicates that the number of Tl-O layers has little effect on the Cu-O bonding. However, the Tl-1212 and Hg-1212 Cu 2p(sub 3/2) signals exhibit differences which suggest that the replacement of T(sup 3+) with Hg(sup 2+) results in a decrease in the O 2p right arrow Cu 3d charge-transfer energy and differences in the probabilities of planar vs apical oxygen charge transfer and/or Zhang-Rice singlet-state formation. Differences between the Tl-1212 and the Tl-2212 and Hg-1212 measured valence bands are consistent with the calculated Cu 3d and (Tl,Hg) 6s/5d partial densities of states.

Delayed detached-eddy simulation of vortex breakdown over a 70 .deg. delta wing

International Nuclear Information System (INIS)

Son, Mi So; Sa, Jeong Hwan; Park, Soo Hyung; Byun, Yung Hwan; Cho, Kum Won

2015-01-01

To investigate the vortex breakdown over the ONERA70 delta wing at an angle-of-attack of 27 .deg., unsteady simulations were performed using Reynolds-averaged Navier-Stokes and Spalart-Allmaras delayed detached-eddy simulations. A low-diffusive preconditioned Roe scheme with third-order MUSCL interpolation scheme was applied, along with second-order dual-time stepping combined with diagonalized alternating direction implicit method for unsteady simulation. Vortex breakdown was investigated through an examination of total pressure loss, axial velocity, and axial vorticity around the primary vortex. Delayed dtached-eddy simulation provided good agreement with experimental data and predicted all physical phenomena related to vortex breakdown well.

Plant delta 15N correlates with the transpiration efficiency of nitrogen acquisition in tropical trees.

Science.gov (United States)

Cernusak, Lucas A; Winter, Klaus; Turner, Benjamin L

2009-11-01

Based upon considerations of a theoretical model of (15)N/(14)N fractionation during steady-state nitrate uptake from soil, we hypothesized that, for plants grown in a common soil environment, whole-plant delta(15)N (deltaP) should vary as a function of the transpiration efficiency of nitrogen acquisition (F(N)/v) and the difference between deltaP and root delta(15)N (deltaP - deltaR). We tested these hypotheses with measurements of several tropical tree and liana species. Consistent with theoretical expectations, both F(N)/v and deltaP - deltaR were significant sources of variation in deltaP, and the relationship between deltaP and F(N)/v differed between non-N(2)-fixing and N(2)-fixing species. We interpret the correlation between deltaP and F(N)/v as resulting from variation in mineral nitrogen efflux-to-influx ratios across plasma membranes of root cells. These results provide a simple explanation of variation in delta(15)N of terrestrial plants and have implications for understanding nitrogen cycling in ecosystems.

CFD flowfield simulation of Delta Launch Vehicles in a power-on configuration

Science.gov (United States)

Pavish, D. L.; Gielda, T. P.; Soni, B. K.; Deese, J. E.; Agarwal, R. K.

1993-01-01

This paper summarizes recent work at McDonnell Douglas Aerospace (MDA) to develop and validate computational fluid dynamic (CFD) simulations of under expanded rocket plume external flowfields for multibody expendable launch vehicles (ELVs). Multi engine reacting gas flowfield predictions of ELV base pressures are needed to define vehicle base drag and base heating rates for sizing external nozzle and base region insulation thicknesses. Previous ELV design programs used expensive multibody power-on wind tunnel tests that employed chamber/nozzle injected high pressure cold or hot-air. Base heating and pressure measurements were belatedly made during the first flights of past ELV's to correct estimates from semi-empirical engineering models or scale model tests. Presently, CFD methods for use in ELV design are being jointly developed at the Space Transportation Division (MDA-STD) and New Aircraft Missiles Division (MDA-NAMD). An explicit three dimensional, zonal, finite-volume, full Navier-Stokes (FNS) solver with finite rate hydrocarbon/air and aluminum combustion kinetics was developed to accurately compute ELV power-on flowfields. Mississippi State University's GENIE++ general purpose interactive grid generation code was chosen to create zonal, finite volume viscous grids. Axisymmetric, time dependent, turbulent CFD simulations of a Delta DSV-2A vehicle with a MB-3 liquid main engine burning RJ-1/LOX were first completed. Hydrocarbon chemical kinetics and a k-epsilon turbulence model were employed and predictions were validated with flight measurements of base pressure and temperature. Zonal internal/external grids were created for a Delta DSV-2C vehicle with a MB-3 and three Castor-1 solid motors burning and a Delta-2 with an RS-27 main engine (LOX/RP-1) and 9 GEM's attached/6 burning. Cold air, time dependent FNS calculations were performed for DSV-2C during 1992. Single phase simulations that employ finite rate hydrocarbon and aluminum (solid fuel) combustion

Linearity of bulk-controlled inverter ring VCO in weak and strong inversion

DEFF Research Database (Denmark)

Wismar, Ulrik Sørensen; Wisland, D.; Andreani, Pietro

2007-01-01

In this paper linearity of frequency modulation in voltage controlled inverter ring oscillators for non feedback sigma delta converter applications is studied. The linearity is studied through theoretical models of the oscillator operating at supply voltages above and below the threshold voltage......, process variations and temperature variations have also been simulated to indicate the advantages of having the soft rail bias transistor in the VCO....

Growth laws for sub-delta crevasses in the Mississippi River Delta

Science.gov (United States)

Yocum, T. A.; Georgiou, I. Y.; Straub, K. M.

2017-12-01

River deltas are threatened by environmental change, including subsidence, global sea level rise, reduced sediment inputs and other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions to reinitiate the delta cycle. Deltas were studied extensively using numerical models, theoretical and conceptual frameworks, empirical scaling relationships, laboratory models and field observations. But predicting the future of deltas relies on field observations where for most deltas data are still lacking. Moreover, empirical and theoretical scaling laws may be influenced by the data used to develop them, while laboratory deltas may be influenced by scaling issues. Anthropogenic crevasses in the MRD are large enough to overcome limitations of laboratory deltas, and small enough to allow for rapid channel and wetland development, providing an ideal setting to investigate delta development mechanics. Here we assessed growth laws of sub-delta crevasses (SDC) in the MRD, in two experimental laboratory deltas (LD - weakly and strongly cohesive) and compared them to river dominated deltas worldwide. Channel and delta geometry metrics for each system were obtained using geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Results show that SDC follow growth laws similar to large river dominated deltas, with the exception of some that exhibit anomalous behavior with respect to the frequency and distance to a bifurcation and the fraction of wetted delta shoreline (allometry metrics). Most SDC exhibit a systematic decrease of non-dimensional channel geometries with increased bifurcation order, indicating that channels are adjusting to decreased flow after bifurcations occur, and exhibit linear trends for land allometry and width-depth ratio, although geometries decrease more rapidly per bifurcation order. Measured distance to bifurcations in SDC

Application Value of Slider-Crank Mechanism in Pick-and-Place Operation of Delta Robot

Directory of Open Access Journals (Sweden)

Zhe QIN

2018-01-01

Full Text Available By absorbing the advantages of the rotary-driven Delta robot and linear-driven Delta robot, a Delta robot for pick-and-place operation that forms a crank-slider at the drive joint is designed.To take the most common gate shaped curve in Cartesian space as the motion trail of robotic pick-and-place operation, according to the kinematics inverse solution theory of Delta robot, this thesis mainly solves the output angular velocity of robot-driven joint. Establishing the static transfer mathematical model and solving the forced condition of driving joint. The simulation analysis show that after the upper slider-crank mechanism is connected to the driving joint, the angular velocity of the driving joint changes suddenly, which caused a rigid impact on the robot in the picking and releasing operation, though the force of the driving joint can be made smaller.

Dose calibrator linearity test: {sup 99m}Tc versus {sup 18}F radioisotopes

Energy Technology Data Exchange (ETDEWEB)

Willegaignon, Jose; Coura-Filho, George Barberio; Garcez, Alexandre Teles, E-mail: willegaignon@hotmail.com [Instituto do Cancer do Estado de Sao Paulo Octavio Frias de Oliveira (ICESP), Sao Paulo, SP (Brazil); Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto [Universidade de Sao Paulo (FM/USP), Sao Paulo, SP (Brazil). Fac. de Medicina; Alves, Carlos Eduardo Gonzalez Ribeiro; Cardona, Marissa Anabel Rivera; Gutterres, Ricardo Fraga [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

2015-01-15

Objective: the present study was aimed at evaluating the viability of replacing {sup 18}F with {sup 99m}Tc in dose calibrator linearity testing. Materials and methods: the test was performed with sources of {sup 99m}Tc (62 GBq) and {sup 18}F (12 GBq) whose activities were measured up to values lower than 1 MBq. Ratios and deviations between experimental and theoretical {sup 99m}Tc and {sup 18}F sources activities were calculated and subsequently compared. Results: mean deviations between experimental and theoretical {sup 99m}Tc and {sup 18}F sources activities were 0.56 (± 1.79)% and 0.92 (± 1.19)%, respectively. The mean ratio between activities indicated by the device for the {sup 99m}Tc source as measured with the equipment precalibrated to measure {sup 99m}Tc and {sup 18}F was 3.42 (± 0.06), and for the {sup 18}F source this ratio was 3.39 (± 0.05), values considered constant over the measurement time. Conclusion: the results of the linearity test using {sup 99m}Tc were compatible with those obtained with the {sup 18}F source, indicating the viability of utilizing both radioisotopes in dose calibrator linearity testing. Such information in association with the high potential of radiation exposure and costs involved in {sup 18}F acquisition suggest {sup 99m}Tc as the element of choice to perform dose calibrator linearity tests in centers that use {sup 18}F, without any detriment to the procedure as well as to the quality of the nuclear medicine service. (author)

Multivariate linear regression of high-dimensional fMRI data with multiple target variables.

Science.gov (United States)

Valente, Giancarlo; Castellanos, Agustin Lage; Vanacore, Gianluca; Formisano, Elia

2014-05-01

Multivariate regression is increasingly used to study the relation between fMRI spatial activation patterns and experimental stimuli or behavioral ratings. With linear models, informative brain locations are identified by mapping the model coefficients. This is a central aspect in neuroimaging, as it provides the sought-after link between the activity of neuronal populations and subject's perception, cognition or behavior. Here, we show that mapping of informative brain locations using multivariate linear regression (MLR) may lead to incorrect conclusions and interpretations. MLR algorithms for high dimensional data are designed to deal with targets (stimuli or behavioral ratings, in fMRI) separately, and the predictive map of a model integrates information deriving from both neural activity patterns and experimental design. Not accounting explicitly for the presence of other targets whose associated activity spatially overlaps with the one of interest may lead to predictive maps of troublesome interpretation. We propose a new model that can correctly identify the spatial patterns associated with a target while achieving good generalization. For each target, the training is based on an augmented dataset, which includes all remaining targets. The estimation on such datasets produces both maps and interaction coefficients, which are then used to generalize. The proposed formulation is independent of the regression algorithm employed. We validate this model on simulated fMRI data and on a publicly available dataset. Results indicate that our method achieves high spatial sensitivity and good generalization and that it helps disentangle specific neural effects from interaction with predictive maps associated with other targets. Copyright © 2013 Wiley Periodicals, Inc.

The study, design and simulation of a free piston Stirling engine linear alternatorThe study, design and simulation of a free piston Stirling engine linear alternator

Directory of Open Access Journals (Sweden)

Teodora Susana Oros

2014-12-01

Full Text Available This paper presents a study, design and simulation of a Free Piston Stirling Engine Linear Alternator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally, a detailed thermal, mechanical and electrical model for a Stirling engine linear alternator have been made in SIMULINK simulation program. The linear alternator simulation model uses a controllable DC voltage which simulates the linear alternator combined with a rectifier, a variable load and a DC-DC converter, which compensates for the variable nature of Stirling engine operation, and ensures a constant voltage output regardless of the load.

Simulation of a medical linear accelerator for teaching purposes.

Science.gov (United States)

Anderson, Rhys; Lamey, Michael; MacPherson, Miller; Carlone, Marco

2015-05-08

Simulation software for medical linear accelerators that can be used in a teaching environment was developed. The components of linear accelerators were modeled to first order accuracy using analytical expressions taken from the literature. The expressions used constants that were empirically set such that realistic response could be expected. These expressions were programmed in a MATLAB environment with a graphical user interface in order to produce an environment similar to that of linear accelerator service mode. The program was evaluated in a systematic fashion, where parameters affecting the clinical properties of medical linear accelerator beams were adjusted independently, and the effects on beam energy and dose rate recorded. These results confirmed that beam tuning adjustments could be simulated in a simple environment. Further, adjustment of service parameters over a large range was possible, and this allows the demonstration of linear accelerator physics in an environment accessible to both medical physicists and linear accelerator service engineers. In conclusion, a software tool, named SIMAC, was developed to improve the teaching of linear accelerator physics in a simulated environment. SIMAC performed in a similar manner to medical linear accelerators. The authors hope that this tool will be valuable as a teaching tool for medical physicists and linear accelerator service engineers.

Time-dependent correlation of cerebral blood flow with oxygen metabolism in activated human visual cortex as measured by fMRI.

Science.gov (United States)

Lin, Ai-Ling; Fox, Peter T; Yang, Yihong; Lu, Hanzhang; Tan, Li-Hai; Gao, Jia-Hong

2009-01-01

The aim of this study was to investigate the relationship between relative cerebral blood flow (delta CBF) and relative cerebral metabolic rate of oxygen (delta CMRO(2)) during continuous visual stimulation (21 min at 8 Hz) with fMRI biophysical models by simultaneously measuring of BOLD, CBF and CBV fMRI signals. The delta CMRO(2) was determined by both a newly calibrated single-compartment model (SCM) and a multi-compartment model (MCM) and was in agreement between these two models (P>0.5). The duration-varying delta CBF and delta CMRO(2) showed a negative correlation with time (r=-0.97, PSCM, an incorrect and even an opposite appearance of the flow-metabolism relationship during prolonged visual stimulation (positively linear coupling) can result. The time-dependent negative correlation between flow and metabolism demonstrated in this fMRI study is consistent with a previous PET observation and further supports the view that the increase in CBF is driven by factors other than oxygen demand and the energy demands will eventually require increased aerobic metabolism as stimulation continues.

Inclusive production of. delta. /sup + +/(1232) in pn interactions at 19 GeV/c

Energy Technology Data Exchange (ETDEWEB)

Bakken, V.; Breivik, F.O.; Jacobsen, T.; Rudjord, A.L. (Oslo Univ. (Norway) Fysisk Inst.)

1982-12-21

We present a study of ..delta../sup + +/ production in pn interactions at 19 GeV/c, where the ..delta../sup + +/ is emitted in the protonlike (..delta..sub(F)/sup + +/) and neutron-like (..delta..sub(B)/sup + +/) c.m. hemispheres. The cross-section sigma(pn->..delta..sub(F)/sup + +/+X)=(3.09+-0.43) mb is about three times larger than sigma(pn->..delta..sub(B)/sup + +/+X)=(0.94+-0.34) mb. About 2/3 of ..delta..sub(F)/sup + +/ is peripherally produced with vertical stroketsub(p,..delta..)vertical stroke<1 (GeV/c)/sup 2/, while the cross-section for ..delta..sub(B)/sup + +/ production is nearly zero for vertical stroketsub(n,..delta..)vertical stroke<1 (GeV/c)/sup 2/. We have made a detailed study of the energy dependence of the reaction ap->..delta../sup + +/+X (a=p, anti p, n, ..pi..sup(+-), Ksup(+-)) for vertical stroketsub(p,..delta..)vertical stroke<1 (GeV/c)/sup 2/, by applying the same fitting procedure to extract the ..delta../sup + +/ cross-section to all available mass spectra. All the normalized cross-sections R=sigma(..delta../sup + +/)/sigmasub(inel) can be well described by R=R/sub 0/+R/sub 1/sup(a)psup(-..cap alpha..)sub(lab), where R/sub 0/ and ..cap alpha.. are the same for all reactions, while R/sub 1/sup(a) varies with the beam type a. The value of ..cap alpha.. is slightly below unity. The differential cross section of pn->..delta..sub(F)/sup + +/+X has been determined as a function of the variables t, t', x, y, psub(T)/sup 2/ and Msub(X)/sup 2/ both in the whole kinematical region and for vertical stroketsub(p,..delta..)vertical stroke<1 (GeV/c)/sup 2/. We show that the peripherally produced ..delta..sub(F)/sup + +/ is consistent with the dominance of the one-pion exchange mechanism. This follows from a study of the density matrix elements, the comparison of some properties of the system X with real ..pi../sup +/p data and from the results of a triple-Regge analysis.

Comparison of Simulated and Measured Non-linear Ultrasound Fields

DEFF Research Database (Denmark)

Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

2011-01-01

In this paper results from a non-linear AS (angular spectrum) based ultrasound simulation program are compared to water-tank measurements. A circular concave transducer with a diameter of 1 inch (25.4 mm) is used as the emitting source. The measured pulses are rst compared with the linear...... simulation program Field II, which will be used to generate the source for the AS simulation. The generated non-linear ultrasound eld is measured by a hydrophone in the focal plane. The second harmonic component from the measurement is compared with the AS simulation, which is used to calculate both...... fundamental and second harmonic elds. The focused piston transducer with a center frequency of 5 MHz is excited by a waveform generator emitting a 6-cycle sine wave. The hydrophone is mounted in the focal plane 118 mm from the transducer. The point spread functions at the focal depth from Field II...

Delta-9-tetrahydrocannabinol-induced dopamine release as a function of psychosis risk: 18F-fallypride positron emission tomography study.

Directory of Open Access Journals (Sweden)

Rebecca Kuepper

Full Text Available Cannabis use is associated with psychosis, particularly in those with expression of, or vulnerability for, psychotic illness. The biological underpinnings of these differential associations, however, remain largely unknown. We used Positron Emission Tomography and (18F-fallypride to test the hypothesis that genetic risk for psychosis is expressed by differential induction of dopamine release by Δ(9-THC (delta-9-tetrahydrocannabinol, the main psychoactive ingredient of cannabis. In a single dynamic PET scanning session, striatal dopamine release after pulmonary administration of Δ(9-THC was measured in 9 healthy cannabis users (average risk psychotic disorder, 8 patients with psychotic disorder (high risk psychotic disorder and 7 un-related first-degree relatives (intermediate risk psychotic disorder. PET data were analyzed applying the linear extension of the simplified reference region model (LSRRM, which accounts for time-dependent changes in (18F-fallypride displacement. Voxel-based statistical maps, representing specific D2/3 binding changes, were computed to localize areas with increased ligand displacement after Δ(9-THC administration, reflecting dopamine release. While Δ(9-THC was not associated with dopamine release in the control group, significant ligand displacement induced by Δ(9-THC in striatal subregions, indicative of dopamine release, was detected in both patients and relatives. This was most pronounced in caudate nucleus. This is the first study to demonstrate differential sensitivity to Δ(9-THC in terms of increased endogenous dopamine release in individuals at risk for psychosis.

Multipole analysis in the radiation field for linearized f (R ) gravity with irreducible Cartesian tensors

Science.gov (United States)

Wu, Bofeng; Huang, Chao-Guang

2018-04-01

The 1 /r expansion in the distance to the source is applied to the linearized f (R ) gravity, and its multipole expansion in the radiation field with irreducible Cartesian tensors is presented. Then, the energy, momentum, and angular momentum in the gravitational waves are provided for linearized f (R ) gravity. All of these results have two parts, which are associated with the tensor part and the scalar part in the multipole expansion of linearized f (R ) gravity, respectively. The former is the same as that in General Relativity, and the latter, as the correction to the result in General Relativity, is caused by the massive scalar degree of freedom and plays an important role in distinguishing General Relativity and f (R ) gravity.

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

Energy Technology Data Exchange (ETDEWEB)

Mishra, S.; Gammon, W.J.; Pappas, D.P. [Virginia Commonwealth Univ., Richmond, VA (United States)] [and others

1997-04-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield.

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

International Nuclear Information System (INIS)

Mishra, S.; Gammon, W.J.; Pappas, D.P.

1997-01-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield

Simulator For The Linear Collider (SLIC): A Tool For ILC Detector Simulations

International Nuclear Information System (INIS)

Graf, Norman; McCormick, Jeremy

2006-01-01

The Simulator for the Linear Collider (SLIC) is a detector simulation program based on the GEANT4 toolkit. It is intended to enable end users to easily model detector concepts by providing the ability to fully describe detectors using plain text files read in by a common executable at runtime. The detector geometry, typically the most complex part of a detector simulation, is described at runtime using the Linear Collider Detector Description (LCDD). This system allows end users to create complex detector geometries in a standard XML format rather than procedural code such as C++. The LCDD system is based on the Geometry Description Markup Language (GDML) from the LHC Applications Group (LCG). The geometry system facilitates the study of different full detector design and their variations. SLIC uses the StdHep format to read input created by event generators and outputs events in the Linear Collider IO (LCIO) format. The SLIC package provides a binding to GEANT4 and many additional commands and features for the end user

Simulator for the Linear Collider (SLIC): a Tool for ILC Detector Simulations

International Nuclear Information System (INIS)

Graf, N.; McCormick, J.

2007-01-01

The Simulator for the Linear Collider (SLIC) is a detector simulation program based on the GEANT4 toolkit. It is intended to enable end users to easily model detector concepts by providing the ability to fully describe detectors using plain text files read in by a common executable at runtime. The detector geometry, typically the most complex part of a detector simulation, is described at runtime using the Linear Collider Detector Description (LCDD). This system allows end users to create complex detector geometries in a standard XML format rather than procedural code such as C++. The LCDD system is based on the Geometry Description Markup Language (GDML) from the LHC Applications Group (LCG). The geometry system facilitates the study of different full detector design and their variations. SLIC uses the StdHep format to read input created by event generators and outputs events in the Linear Collider IO (LCIO) format. The SLIC package provides a binding to GEANT4 and many additional commands and features for the end user

On the Universality of CP Violation in Delta F = 1 Processes

CERN Document Server

Gedalia, Oram; Ligeti, Zoltan; Perez, Gilad

2012-01-01

We show that new physics that breaks the left-handed SU(3)_Q quark flavor symmetry induces contributions to CP violation in Delta F = 1 processes which are approximately universal, in that they are not affected by flavor rotations between the up and the down mass bases. Therefore, such flavor violation cannot be aligned, and is constrained by the strongest bound from either the up or the down sectors. We use this result to show that the bound from eps'/eps prohibits an SU(3)_Q breaking explanation of the recent LHCb evidence for CP violation in D meson decays. Another consequence of this universality is that supersymmetric alignment models with a moderate mediation scale are consistent with the data, and are harder to probe via CP violating observables. With current constraints, therefore, squarks need not be degenerate. However, future improvements in the measurement of CP violation in D-Dbar mixing will start to probe alignment models.

Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

Science.gov (United States)

Xie, Xianjun; Wang, Yanxin; Su, Chunli; Duan, Mengyu

2013-02-01

To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin.

Sensitivity study of surface wind flow of a limited area model simulating the extratropical storm Delta affecting the Canary Islands

OpenAIRE

Marrero, C.; Jorba, O.; Cuevas, E.; Baldasano, J. M.

2009-01-01

In November 2005 an extratropical storm named Delta affected the Canary Islands (Spain). The high sustained wind and intense gusts experienced caused significant damage. A numerical sensitivity study of Delta was conducted using the Weather Research & Forecasting Model (WRF-ARW). A total of 27 simulations were performed. Non-hydrostatic and hydrostatic experiments were designed taking into account physical parameterizations and geometrical factors (size and position of the outer domain, d...

Development of a global river-coastal coupling model and its application to flood simulation in Asian mega-delta regions

Science.gov (United States)

Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip; Verlaan, Martin; Winsemius, Hessel; Kanae, Shinjiro

2017-04-01

The world's mega-delta regions and estuaries are susceptible to various water-related disasters, such as river flooding and storm surge. Moreover, simultaneous occurrence of them would be more devastating than a situation where they occur in isolation. Therefore, it is important to provide information about compound risks of fluvial and coastal floods at a large scale, both their statistical dependency as well as their combined resulting flooding in delta regions. Here we report on a first attempt to address this issue globally by developing a method to couple a global river model (CaMa-Flood) and a global tide and surge reanalysis (GTSR) dataset. A state-of-the-art global river routing model, CaMa-Flood, was modified to represent varying sea levels due to tides and storm surges as downstream boundary condition, and the GTSR dataset was post-processed to serve as inputs to the CaMa-Flood river routing simulation and a long-term simulation was performed to incorporate the temporal dependency between coastal tide and surge on the one hand, and discharge on the other. The coupled model was validated against observations, showing better simulation results of water levels in deltaic regions than simulation without GTSR. For example in the Ganges Delta, correlation coefficients were increased by 0.06, and root mean square errors were reduced by 0.22 m. Global coupling simulations revealed that storm surges affected river water levels in coastal regions worldwide, especially in low-lying flat areas with increases in water level larger than 0.5 m. By employing enhanced storm surge simulation with tropical storm tracks, we also applied the model to examine impacts of past hurricane and cyclone storm events on river flood inundation.

Monte Carlo simulations with Symanzik's improved actions in the lattice 0(3) non-linear sigma-model

International Nuclear Information System (INIS)

Berg, B.; Montvay, I.; Meyer, S.

1983-10-01

The scaling properties of the lattice 0(3) non-linear delta-model are studied. The mass-gap, energy-momentum dispersion, correlation functions are measured by numerical Monte Carlo methods. Symanzik's tree-level and 1-loop improved actions are compared to the standard (nearest neigbour) action. (orig.)

On the Composition and Neutrix Composition of the Delta Function and the Function cosh^{-1}(|x|^{1/r}+1

Directory of Open Access Journals (Sweden)

Brian Fisher

2017-03-01

Full Text Available Let $F$ be a distribution in $\\mathcal{D'}$ and let $f$ be a locally summable function. The composition $F(f(x$ of $F$ and $f$ is said to exist and be equal to the distribution $h(x$ if the limit of the sequence $\\{ F_{n}(f(x\\}$ is equal to $h(x$, where $F_n(x =F(x*\\delta _n(x$ for $n=1,2, \\ldots$ and $\\{\\delta_n(x\\}$ is a certain regular sequence converging to the Dirac delta function. It is proved that the neutrix composition $ \\delta^{(s}[\\cosh^{-1} (x_+^{1/r}+1] $ exists and \\beqa \\delta^{(s}[\\cosh^{-1} (x_+^{1/r}+1] = - \\sum _{k=0} ^{M-1} \\sum_{i=0}^{kr+r} {k \\choose i}{(-1^{i+k}rc_{r,s,k} \\over (kr+rk!}\\delta ^{(k}(x, for $s =M-1,M, M+1,\\ldots$ and $r=1,2,\\ldots,$ where $$c_{r,s,k}=\\sum _{j=0}^{i} {i \\choose j}{ (-1^{kr+r-i}(2j-i^{s+1}\\over 2^{s+i+1} },$$ $M$ is the smallest integer for which $s-2r+1 < 2Mr$ and $r\\le s/(2M+2.$ Further results are also proved.

Tidal modulated flow and sediment flux through Wax Lake Delta distributary channels: Implications for delta development

Directory of Open Access Journals (Sweden)

K. Hanegan

2015-03-01

Full Text Available In this study, a Delft3D model of the Wax Lake Delta was developed to simulate flow and sediment flux through delta distributary channels. The model was calibrated for tidal constituents as well as velocity and sediment concentration across channel transects. The calibrated model was then used to simulate full spring–neap tidal cycles under constant low flow upstream boundary conditions, with grain size variation in suspended load represented using two sediment fractions. Flow and sediment flux results through distributary channel cross-sections were examined for spatial and temporal variability with the goal of characterizing the role of tides in sediment reworking and delta development. The Wax Lake Delta has prograded through channel extension, river mouth bar deposition, and channel bifurcation. Here we show that tidal modulation of currents influences suspended sand transport, and spatial acceleration through distributary channels at low tides is sufficient to suspend sand in distal reaches during lower flows. The basinward-increasing transport capacity in distributary channels indicates that erosive channel extension could be an important process, even during non-flood events.

Development of non-linear vibration analysis code for CANDU fuelling machine

International Nuclear Information System (INIS)

Murakami, Hajime; Hirai, Takeshi; Horikoshi, Kiyomi; Mizukoshi, Kaoru; Takenaka, Yasuo; Suzuki, Norio.

1988-01-01

This paper describes the development of a non-linear, dynamic analysis code for the CANDU 600 fuelling machine (F-M), which includes a number of non-linearities such as gap with or without Coulomb friction, special multi-linear spring connections, etc. The capabilities and features of the code and the mathematical treatment for the non-linearities are explained. The modeling and numerical methodology for the non-linearities employed in the code are verified experimentally. Finally, the simulation analyses for the full-scale F-M vibration testing are carried out, and the applicability of the code to such multi-degree of freedom systems as F-M is demonstrated. (author)

International linear collider simulations using BDSIM

Indian Academy of Sciences (India)

BDSIM is a Geant4 [1] extension toolkit for the simulation of particle transport in accelerator beamlines. It is a code that combines accelerator-style particle tracking with traditional Geant-style tracking based on Runga–Kutta techniques. A more detailed description of the code can be found in [2]. In an e+e− linear collider ...

Non-linear simulations of ELMs in ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Lessig, Alexander; Hoelzl, Matthias; Orain, Francois; Guenter, Sibylle [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, 85748 Garching (Germany); Becoulet, Marina; Huysmans, Guido [CEA-IRFM, Cadarache, 13108 Saint-Paul-Lez-Durance (France); Collaboration: the ASDEX Upgrade Team

2016-07-01

Large edge localized modes (ELMs) are a severe concern for the operation of future tokamak devices like ITER or DEMO due to the high transient heat loads induced on divertor targets and wall structures. It is therefore important to study ELMs both theoretically and experimentally in order to obtain a comprehensive understanding of the underlying mechanisms which is necessary for the prediction of ELM properties and the design of ELM mitigation systems. Using the non-linear MHD code JOREK, we have performed first simulations of full ELM crashes in ASDEX Upgrade, taking into account a large number of toroidal Fourier harmonics. The evolution of the toroidal mode spectrum has been investigated. In particular, we confirm the previously observed non-linear drive of linearly sub-dominant low-n components in the early non-linear phase of the ELM crash. Preliminary comparisons of the simulations with experimental observations regarding heat and particle losses, pedestal evolution and heat deposition patterns are shown. On the long run we aim at code validation as well as an improved understanding of the ELM dynamics and possibly a better characterization of different ELM types.

Backward production of mesons associated with. Delta. sup ++ (1232) in. pi. sup + p interactions at 20 GeV/c

Energy Technology Data Exchange (ETDEWEB)

Perepelitsa, V.F.; Mikhailichenko, V.I.; Nikitin, S.Ya.; Zhokin, A.S. (Institut Teoreticheskoj i Ehksperimental' noj Fiziki, Moscow (USSR)); Akopov, N.Z.; Grigoryan, A.A.; Karapetyan, V.V. (Erevanskij Fizicheskij Inst., Erevan (USSR)); Dorsaz, L.; Sonderegger, P. (European Organization for Nuclear Research, Geneva (Switzerland)); Ferrer, A. (Centro Mixto Valencia Univ./CSIC, Valencia (Spain). Inst. de Fisica Corpuscular)

1991-05-01

We have analyzed backward meson production in {pi}{sup +}p reactions at 20 GeV/c, which were measured in the CERN {Omega} spectrometer triggered by a fast proton (p{sub f}), in experiment WA 56. Production via baryon exchange of quasi-two-body final states {Delta}{sup ++}(1232) rho{sup 0}(770), {Delta}{sup ++}(1232) f{sub 2}(1270) and {Delta}{sup ++}(1232) rho{sub 3}{sup 0}(1690) is clearly identified. The density matrix elements of meson resonances and of {Delta}{sup ++}(1232) are analyzed. We have observed also the reactions {pi}{sup +}p->{Delta}{sup ++}(1232){pi}{sup 0} and {pi}{sup +}p->{Delta}{sup ++}(1232){omega} in the p{sub f}{pi}{sup +}{pi}{sup 0} and p{sub f}{pi}{sup +}{pi}{sup +}{pi}{sup -}{pi}{sup 0} final states. (orig.).

Tidal controls on river delta morphology

Science.gov (United States)

Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

2017-09-01

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

Polarized antiquark flavor asymmetry DELTA anti u(x)-DELTA anti d(x) and the pion cloud

CERN Document Server

Fries, R J; Weiss, C

2003-01-01

The flavor asymmetry of the unpolarized antiquark distributions in the proton, anti u(x)- anti d(x)0. Using a simple chiral linear sigma model as an example, we demonstrate that in the meson cloud picture a large positive DELTA anti u(x)-DELTA anti d(x) can be obtained from pi-sigma interference contributions. This calls into question previous estimates based on rho-meson contributions alone, and indicates how the results of the meson cloud picture may be reconciled with those of quark-based models. (orig.)

Experiences with linear solvers for oil reservoir simulation problems

Energy Technology Data Exchange (ETDEWEB)

Joubert, W.; Janardhan, R. [Los Alamos National Lab., NM (United States); Biswas, D.; Carey, G.

1996-12-31

This talk will focus on practical experiences with iterative linear solver algorithms used in conjunction with Amoco Production Company`s Falcon oil reservoir simulation code. The goal of this study is to determine the best linear solver algorithms for these types of problems. The results of numerical experiments will be presented.

Reliability modelling and simulation of switched linear system ...

African Journals Online (AJOL)

Reliability modelling and simulation of switched linear system control using temporal databases. ... design of fault-tolerant real-time switching systems control and modelling embedded micro-schedulers for complex systems maintenance.

Full-f gyrokinetic simulation over a confinement time

Energy Technology Data Exchange (ETDEWEB)

Idomura, Yasuhiro, E-mail: idomura.yasuhiro@jaea.go.jp [Japan Atomic Energy Agency, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8587 (Japan)

2014-02-15

A long time ion temperature gradient driven turbulence simulation over a confinement time is performed using the full-f gyrokinetic Eulerian code GT5D. The convergence of steady temperature and rotation profiles is examined, and it is shown that the profile relaxation can be significantly accelerated when the simulation is initialized with linearly unstable temperature profiles. In the steady state, the temperature profile and the ion heat diffusivity are self-consistently determined by the power balance condition, while the intrinsic rotation profile is sustained by complicated momentum transport processes without momentum input. The steady turbulent momentum transport is characterized by bursty non-diffusive fluxes, and the resulting turbulent residual stress is consistent with the profile shear stress theory [Y. Camenen et al., “Consequences of profile shearing on toroidal momentum transport,” Nucl. Fusion 51, 073039 (2011)] in which the residual stress depends not only on the profile shear and the radial electric field shear but also on the radial electric field itself. Based on the toroidal angular momentum conservation, it is found that in the steady null momentum transport state, the turbulent residual stress is cancelled by the neoclassical counterpart, which is greatly enhanced in the presence of turbulent fluctuations.

Resolution limits of migration and linearized waveform inversion images in a lossy medium

KAUST Repository

Schuster, Gerard T.; Dutta, Gaurav; Li, Jing

2017-01-01

The vertical-and horizontal-resolution limits Delta x(lossy) and Delta z(lossy) of post-stack migration and linearized waveform inversion images are derived for lossy data in the far-field approximation. Unlike the horizontal resolution limit Delta x proportional to lambda z/L in a lossless medium which linearly worsens in depth z, Delta x(lossy) proportional to z(2)/QL worsens quadratically with depth for a medium with small Q values. Here, Q is the quality factor, lambda is the effective wavelength, L is the recording aperture, and loss in the resolution formulae is accounted for by replacing lambda with z/Q. In contrast, the lossy vertical-resolution limit Delta z(lossy) only worsens linearly in depth compared to Delta z proportional to lambda for a lossless medium. For both the causal and acausal Q models, the resolution limits are linearly proportional to 1/Q for small Q. These theoretical predictions are validated with migration images computed from lossy data.

Resolution limits of migration and linearized waveform inversion images in a lossy medium

KAUST Repository

Schuster, Gerard T.

2017-03-10

The vertical-and horizontal-resolution limits Delta x(lossy) and Delta z(lossy) of post-stack migration and linearized waveform inversion images are derived for lossy data in the far-field approximation. Unlike the horizontal resolution limit Delta x proportional to lambda z/L in a lossless medium which linearly worsens in depth z, Delta x(lossy) proportional to z(2)/QL worsens quadratically with depth for a medium with small Q values. Here, Q is the quality factor, lambda is the effective wavelength, L is the recording aperture, and loss in the resolution formulae is accounted for by replacing lambda with z/Q. In contrast, the lossy vertical-resolution limit Delta z(lossy) only worsens linearly in depth compared to Delta z proportional to lambda for a lossless medium. For both the causal and acausal Q models, the resolution limits are linearly proportional to 1/Q for small Q. These theoretical predictions are validated with migration images computed from lossy data.

Oxygen Nonstoichiometry and Defect Chemistry Modeling of Ce0.8Pr0.2O2-delta

DEFF Research Database (Denmark)

Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

2010-01-01

(DeltaHPrexc=aHdelta) and a completely random distribution of defects (referred to as “delta-linear”), or a “generalized delta-linear” solution model, where the excess Gibbs energy change in the reduction reaction of the dopant linearly varies with delta (DeltaGPrexc=aGdelta). A comparison of the partial...

Numerical simulation of collision-free plasma using Vlasov hybrid simulation

International Nuclear Information System (INIS)

Nunn, D.

1990-01-01

A novel scheme for the numerical simulation of wave particle interactions in space plasmas has been developed. The method, termed VHS or Vlasov Hybrid Simulation, is applicable to hot collision free plasmas in which the unperturbed distribution functions is smooth and free of delta function singularities. The particle population is described as a continuous Vlasov fluid in phase space-granularity and collisional effects being ignored. In traditional PIC/CIC codes the charge/current due to each simulation particle is assigned to a fixed spatial grid. In the VHS method the simulation particles sample the Vlasov fluid and provide information about the value of distribution function (F(r,v) at random points in phase space. Values of F are interpolated from the simulation particles onto a fixed grid in velocity/position or phase space. With distribution function defined on a phase space grid the plasma charge/current field is quickly calculated. The simulation particles serve only to provide information, and thus the particle population may be dynamic. Particles no longer resonant with the wavefield may be discarded from the simulation, and new particles may be inserted into the Vlasov fluid where required

Monte Carlo simulation of OLS and linear mixed model inference of phenotypic effects on gene expression

Directory of Open Access Journals (Sweden)

Jeffrey A. Walker

2016-10-01

Full Text Available Background Self-contained tests estimate and test the association between a phenotype and mean expression level in a gene set defined a priori. Many self-contained gene set analysis methods have been developed but the performance of these methods for phenotypes that are continuous rather than discrete and with multiple nuisance covariates has not been well studied. Here, I use Monte Carlo simulation to evaluate the performance of both novel and previously published (and readily available via R methods for inferring effects of a continuous predictor on mean expression in the presence of nuisance covariates. The motivating data are a high-profile dataset which was used to show opposing effects of hedonic and eudaimonic well-being (or happiness on the mean expression level of a set of genes that has been correlated with social adversity (the CTRA gene set. The original analysis of these data used a linear model (GLS of fixed effects with correlated error to infer effects of Hedonia and Eudaimonia on mean CTRA expression. Methods The standardized effects of Hedonia and Eudaimonia on CTRA gene set expression estimated by GLS were compared to estimates using multivariate (OLS linear models and generalized estimating equation (GEE models. The OLS estimates were tested using O’Brien’s OLS test, Anderson’s permutation ${r}_{F}^{2}$ r F 2 -test, two permutation F-tests (including GlobalAncova, and a rotation z-test (Roast. The GEE estimates were tested using a Wald test with robust standard errors. The performance (Type I, II, S, and M errors of all tests was investigated using a Monte Carlo simulation of data explicitly modeled on the re-analyzed dataset. Results GLS estimates are inconsistent between data sets, and, in each dataset, at least one coefficient is large and highly statistically significant. By contrast, effects estimated by OLS or GEE are very small, especially relative to the standard errors. Bootstrap and permutation GLS

Real-time simulation of an F110/STOVL turbofan engine

Science.gov (United States)

Drummond, Colin K.; Ouzts, Peter J.

1989-01-01

A traditional F110-type turbofan engine model was extended to include a ventral nozzle and two thrust-augmenting ejectors for Short Take-Off Vertical Landing (STOVL) aircraft applications. Development of the real-time F110/STOVL simulation required special attention to the modeling approach to component performance maps, the low pressure turbine exit mixing region, and the tailpipe dynamic approximation. Simulation validation derives by comparing output from the ADSIM simulation with the output for a validated F110/STOVL General Electric Aircraft Engines FORTRAN deck. General Electric substantiated basic engine component characteristics through factory testing and full scale ejector data.

Parallel beam dynamics simulation of linear accelerators

International Nuclear Information System (INIS)

Qiang, Ji; Ryne, Robert D.

2002-01-01

In this paper we describe parallel particle-in-cell methods for the large scale simulation of beam dynamics in linear accelerators. These techniques have been implemented in the IMPACT (Integrated Map and Particle Accelerator Tracking) code. IMPACT is being used to study the behavior of intense charged particle beams and as a tool for the design of next-generation linear accelerators. As examples, we present applications of the code to the study of emittance exchange in high intensity beams and to the study of beam transport in a proposed accelerator for the development of accelerator-driven waste transmutation technologies

Haematological and genetic features of delta beta-thalassaemia in Pakistan

International Nuclear Information System (INIS)

Ahmad, S.; Anwar, M.

2006-01-01

Objective: To describe the hematological and genetic features of delta beta-thalassaemia in Pakistani patients. Design: Descriptive case series. Place and Duration of Study: Department of Pathology, PNS Shifa, Karachi and Department of Hematology, Armed Forces Institute of Pathology, Rawalpindi, from January 1994 to April 2004. Patients and Methods: Thirteen individuals from six unrelated Pakistani families with a hematological diagnosis of delta beta-thalassaemia were studied. A brief clinical history, and the results of blood counts, absolute values, Hb-F, Hb-A/sub 2/, and hemoglobin electrophoresis were recorded. The DNA from each subject was first screened for the delta beta-thalassaemia mutations found in the Pakistani population. The samples were then screened for the Invl Del sup G/gamma(sup A/gamma delta beta). Results: The subjects included six heterozygote, six homozygotes and one compound heterozygote of delta beta and delta beta-thalassaemia. All heterozygote and 4/6 homozygotes were asymptomatic. One homo zygote had thalassaemia intermedia while another had transfusion dependent anemia. The mean Hb, TRBC, MCV, MCH, Hb-F and Hb-A/sub 2/ in delta beta-thalassaemia heterozygote were 11.6 g/dl, 5.37 x 1012/L, 70.9 fl, and 21.7 pg, 14% and 2.6% respectively. The same values in the four un transfused homo zygote were 10.6 g/dl, 5.34x1012/L, 69.211, and 20.8pg, 100% and 0% respectively. The mutation analysis revealed that all 13 individuals had the same Invl Del sup G/gamma(sup A/gamma delta beta). Conclusion: delta beta-thalassaemia is a rare disorder in Pakistan. Although the clinical picture is very mild its combination with delta beta-thalassaemia trait can produce a sever transfusion dependent thalassaemia. The DNA based diagnosis is possible in the prenatal as well as the postnatal period. (author)

QCD in the {delta}-regime

Energy Technology Data Exchange (ETDEWEB)

Bietenholz, W. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares; Cundy, N. [Seoul National Univ. (Korea, Republic of). Lattice Gauge Theory Research Center; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y. [Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2011-03-15

The {delta}-regime of QCD is characterised by light quarks in a small spatial box, but a large extent in (Euclidean) time. In this setting a specific variant of chiral perturbation theory - the {delta}-expansion - applies, based on a quantum mechanical treatment of the quasi onedimensional system. In particular, for vanishing quark masses one obtains a residual pion mass M{sup R}{sub {pi}}, which has been computed to the third order in the {delta}-expansion. A comparison with numerical measurements of this residual mass allows for a new determination of some Low Energy Constants, which appear in the chiral Lagrangian. We first review the attempts to simulate 2-flavour QCD directly in the {delta}-regime. This is very tedious, but results compatible with the predictions for M{sup R}{sub {pi}} have been obtained. Then we show that an extrapolation of pion masses measured in a larger volume towards the {delta}-regime leads to good agreement with the theoretical predictions. From those results, we also extract a value for the (controversial) sub-leading Low Energy Constant anti l{sub 3}. (orig.)

Entropy and optimality in river deltas

Science.gov (United States)

Tejedor, Alejandro; Longjas, Anthony; Edmonds, Douglas A.; Zaliapin, Ilya; Georgiou, Tryphon T.; Rinaldo, Andrea; Foufoula-Georgiou, Efi

2017-10-01

The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. To date, however, a unified theory explaining how deltas self-organize to distribute water and sediment up to the shoreline remains elusive. Here, we provide evidence for an optimality principle underlying the self-organized partition of fluxes in delta channel networks. By introducing a suitable nonlocal entropy rate (nER) and by analyzing field and simulated deltas, we suggest that delta networks achieve configurations that maximize the diversity of water and sediment flux delivery to the shoreline. We thus suggest that prograding deltas attain dynamically accessible optima of flux distributions on their channel network topologies, thus effectively decoupling evolutionary time scales of geomorphology and hydrology. When interpreted in terms of delta resilience, high nER configurations reflect an increased ability to withstand perturbations. However, the distributive mechanism responsible for both diversifying flux delivery to the shoreline and dampening possible perturbations might lead to catastrophic events when those perturbations exceed certain intensity thresholds.

A Gaussian mixture model based adaptive classifier for fNIRS brain-computer interfaces and its testing via simulation

Science.gov (United States)

Li, Zheng; Jiang, Yi-han; Duan, Lian; Zhu, Chao-zhe

2017-08-01

Objective. Functional near infra-red spectroscopy (fNIRS) is a promising brain imaging technology for brain-computer interfaces (BCI). Future clinical uses of fNIRS will likely require operation over long time spans, during which neural activation patterns may change. However, current decoders for fNIRS signals are not designed to handle changing activation patterns. The objective of this study is to test via simulations a new adaptive decoder for fNIRS signals, the Gaussian mixture model adaptive classifier (GMMAC). Approach. GMMAC can simultaneously classify and track activation pattern changes without the need for ground-truth labels. This adaptive classifier uses computationally efficient variational Bayesian inference to label new data points and update mixture model parameters, using the previous model parameters as priors. We test GMMAC in simulations in which neural activation patterns change over time and compare to static decoders and unsupervised adaptive linear discriminant analysis classifiers. Main results. Our simulation experiments show GMMAC can accurately decode under time-varying activation patterns: shifts of activation region, expansions of activation region, and combined contractions and shifts of activation region. Furthermore, the experiments show the proposed method can track the changing shape of the activation region. Compared to prior work, GMMAC performed significantly better than the other unsupervised adaptive classifiers on a difficult activation pattern change simulation: 99% versus  brain-computer interfaces, including neurofeedback training systems, where operation over long time spans is required.

Non-Linear Metamodeling Extensions to the Robust Parameter Design of Computer Simulations

Science.gov (United States)

2016-09-15

The combined-array RSM approach has been applied to a piston simulation [11] and an economic order quantity inventory model [12, 13]. A textbook ...are limited when applied to simulations. In the former case, the mean and variance models can be inadequate due to a high level of non-linearity...highly non-linear nature of typical simulations. In the multi-response RPD problem, the objective is to find the optimal control parameter levels

Quantified, Interactive Simulation of AMCW ToF Camera Including Multipath Effects.

Science.gov (United States)

Bulczak, David; Lambers, Martin; Kolb, Andreas

2017-12-22

In the last decade, Time-of-Flight (ToF) range cameras have gained increasing popularity in robotics, automotive industry, and home entertainment. Despite technological developments, ToF cameras still suffer from error sources such as multipath interference or motion artifacts. Thus, simulation of ToF cameras, including these artifacts, is important to improve camera and algorithm development. This paper presents a physically-based, interactive simulation technique for amplitude modulated continuous wave (AMCW) ToF cameras, which, among other error sources, includes single bounce indirect multipath interference based on an enhanced image-space approach. The simulation accounts for physical units down to the charge level accumulated in sensor pixels. Furthermore, we present the first quantified comparison for ToF camera simulators. We present bidirectional reference distribution function (BRDF) measurements for selected, purchasable materials in the near-infrared (NIR) range, craft real and synthetic scenes out of these materials and quantitatively compare the range sensor data.

Quantified, Interactive Simulation of AMCW ToF Camera Including Multipath Effects

Directory of Open Access Journals (Sweden)

David Bulczak

2017-12-01

Full Text Available In the last decade, Time-of-Flight (ToF range cameras have gained increasing popularity in robotics, automotive industry, and home entertainment. Despite technological developments, ToF cameras still suffer from error sources such as multipath interference or motion artifacts. Thus, simulation of ToF cameras, including these artifacts, is important to improve camera and algorithm development. This paper presents a physically-based, interactive simulation technique for amplitude modulated continuous wave (AMCW ToF cameras, which, among other error sources, includes single bounce indirect multipath interference based on an enhanced image-space approach. The simulation accounts for physical units down to the charge level accumulated in sensor pixels. Furthermore, we present the first quantified comparison for ToF camera simulators. We present bidirectional reference distribution function (BRDF measurements for selected, purchasable materials in the near-infrared (NIR range, craft real and synthetic scenes out of these materials and quantitatively compare the range sensor data.

Parallelized preconditioned BiCGStab solution of sparse linear system equations in F-COBRA-TF

International Nuclear Information System (INIS)

Geemert, Rene van; Glück, Markus; Riedmann, Michael; Gabriel, Harry

2011-01-01

Recently, the in-house development of a preconditioned and parallelized BiCGStab solver has been pursued successfully in AREVA’s advanced sub-channel code F-COBRA-TF. This solver can be run either in a sequential computation mode on a single CPU, or in a parallel computation mode on multiple parallel CPUs. The developed procedure enables the computation of several thousands of successive sparse linear system solutions in F-COBRA-TF with acceptable wall clock run times. The current paper provides general information about F-COBRA-TF in terms of modeling capabilities and application areas, and points out where the relevance arises for the efficient iterative solution of sparse linear systems. Furthermore, the preconditioning and parallelization strategies in the developed BiCGStab iterative solution approach are discussed. The paper is concluded with a number of verification examples. (author)

Linear simulations of the cylindrical Richtmyer-Meshkov instability in magnetohydrodynamics

KAUST Repository

Bakhsh, Abeer

2016-03-09

Numerical simulations and analysis indicate that the Richtmyer-Meshkov instability(RMI) is suppressed in ideal magnetohydrodynamics(MHD) in Cartesian slab geometry. Motivated by the presence of hydrodynamic instabilities in inertial confinement fusion and suppression by means of a magnetic field, we investigate the RMI via linear MHD simulations in cylindrical geometry. The physical setup is that of a Chisnell-type converging shock interacting with a density interface with either axial or azimuthal (2D) perturbations. The linear stability is examined in the context of an initial value problem (with a time-varying base state) wherein the linearized ideal MHD equations are solved with an upwind numerical method. Linear simulations in the absence of a magnetic field indicate that RMI growth rate during the early time period is similar to that observed in Cartesian geometry. However, this RMI phase is short-lived and followed by a Rayleigh-Taylor instability phase with an accompanied exponential increase in the perturbation amplitude. We examine several strengths of the magnetic field (characterized by β=2p/B^2_r) and observe a significant suppression of the instability for β ≤ 4. The suppression of the instability is attributed to the transport of vorticity away from the interface by Alfvén fronts.

Simulations of nanocrystals under pressure: Combining electronic enthalpy and linear-scaling density-functional theory

Energy Technology Data Exchange (ETDEWEB)

Corsini, Niccolò R. C., E-mail: niccolo.corsini@imperial.ac.uk; Greco, Andrea; Haynes, Peter D. [Department of Physics and Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Hine, Nicholas D. M. [Department of Physics and Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Cavendish Laboratory, J. J. Thompson Avenue, Cambridge CB3 0HE (United Kingdom); Molteni, Carla [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

2013-08-28

We present an implementation in a linear-scaling density-functional theory code of an electronic enthalpy method, which has been found to be natural and efficient for the ab initio calculation of finite systems under hydrostatic pressure. Based on a definition of the system volume as that enclosed within an electronic density isosurface [M. Cococcioni, F. Mauri, G. Ceder, and N. Marzari, Phys. Rev. Lett.94, 145501 (2005)], it supports both geometry optimizations and molecular dynamics simulations. We introduce an approach for calibrating the parameters defining the volume in the context of geometry optimizations and discuss their significance. Results in good agreement with simulations using explicit solvents are obtained, validating our approach. Size-dependent pressure-induced structural transformations and variations in the energy gap of hydrogenated silicon nanocrystals are investigated, including one comparable in size to recent experiments. A detailed analysis of the polyamorphic transformations reveals three types of amorphous structures and their persistence on depressurization is assessed.

Measurement of delta-rays in ATLAS silicon sensors

CERN Document Server

The ATLAS collaboration

2013-01-01

In the inner detector of the ATLAS experiment at the LHC, $\\delta$-rays originating from particle interactions in the silicon sensors may cause additional hit channels. A method for identifying silicon hit clusters that are enlarged due to the emission of a $\\delta$-ray is presented. Using pp collision data the expectation is confirmed that the $\\delta$-ray production rate depends linearly on the path length of the particle in silicon, independently of layer radius and detector technology. The range of the $\\delta$-rays, which is a property of the material and should not depend on anything else, is indeed found to be constant as a function of detector layer, path length in silicon and momentum of the particle traversing the silicon. As a by-product of this analysis a method is proposed that could correct for the effect of these $\\delta$-rays, and this could be used to improve track reconstruction.

Tides Stabilize Deltas until Humans Interfere

Science.gov (United States)

Hoitink, T.; Zheng Bing, W.; Vermeulen, B.; Huismans, Y.; Kastner, K.

2017-12-01

Despite global concerns about river delta degradation caused by extraction of natural resources, sediment retention by reservoirs and sea-level rise, human activity in the world's largest deltas intensifies. In this review, we argue that tides tend to stabilize deltas until humans interfere. Under natural circumstances, delta channels subject to tides are more stable than their fluvial-dominated counterparts. The oscillatory tidal flow counteracts the processes responsible for bank erosion, which explains why unprotected tidal channels migrate only slowly. Peak river discharges attenuate the tides, which creates storage space to accommodate the extra river discharge during extreme events and as a consequence, reduce flood risk. With stronger tides, the river discharge is being distributed more evenly over the various branches in a delta, preventing silting up of smaller channels. Human interference in deltas is massive. Storm surge barriers are constructed, new land is being reclaimed and large-scale sand excavation takes place, to collect building material. Evidence from deltas around the globe shows that in human-controlled deltas the tidal motion often plays a destabilizing role. In channels of the Rhine-Meuse Delta, some 100 scour holes are identified, which relates to the altered tidal motion after completion of a storm surge barrier. Sand mining has led to widespread river bank failures in the tidally-influenced Mekong Delta. The catastrophic flood event in the Gauges-Brahmaputra Delta by Cyclone Aila, which caused the inundation of an embanked polder area for over two years, was preceded by river bank erosion at the mouths of formal tidal channels that were blocked by the embankment. Efforts to predict the developments of degrading deltas are few. Existing delta models are capable of reproducing expanding deltas, which is essentially a matter of simulating the transport of sediment from source in a catchment to the sink in a delta. Processes of soil

Membrane Sculpting by F-BAR Domains Studied by Molecular Dynamics Simulations

Science.gov (United States)

Yu, Hang; Schulten, Klaus

2013-01-01

Interplay between cellular membranes and their peripheral proteins drives many processes in eukaryotic cells. Proteins of the Bin/Amphiphysin/Rvs (BAR) domain family, in particular, play a role in cellular morphogenesis, for example curving planar membranes into tubular membranes. However, it is still unclear how F-BAR domain proteins act on membranes. Electron microscopy revealed that, in vitro, F-BAR proteins form regular lattices on cylindrically deformed membrane surfaces. Using all-atom and coarse-grained (CG) molecular dynamics simulations, we show that such lattices, indeed, induce tubes of observed radii. A 250 ns all-atom simulation reveals that F-BAR domain curves membranes via the so-called scaffolding mechanism. Plasticity of the F-BAR domain permits conformational change in response to membrane interaction, via partial unwinding of the domains 3-helix bundle structure. A CG simulation covering more than 350 µs provides a dynamic picture of membrane tubulation by lattices of F-BAR domains. A series of CG simulations identified the optimal lattice type for membrane sculpting, which matches closely the lattices seen through cryo-electron microscopy. PMID:23382665

Large eddy simulation of vortex breakdown behind a delta wing

International Nuclear Information System (INIS)

Mary, I.

2003-01-01

A large eddy simulation (LES) of a turbulent flow past a 70 deg. sweep angle delta wing is performed and compared with wind tunnel experiments. The angle of attack and the Reynolds number based on the root chord are equal to 27 deg. and 1.6x10 6 , respectively. Due to the high value of the Reynolds number and the three-dimensional geometry, the mesh resolution usually required by LES cannot be reached. Therefore a local mesh refinement technique based on semi-structured grids is proposed, whereas different wall functions are assessed in this paper. The goal is to evaluate if these techniques are sufficient to provide an accurate solution of such flow on available supercomputers. An implicit Miles model is retained for the subgrid scale (SGS) modelling because the resolution is too coarse to take advantage of more sophisticated SGS models. The solution sensitivity to grid refinement in the streamwise and wall normal direction is investigated

Proinflammatory effect of sodium 4-phenylbutyrate in deltaF508-cystic fibrosis transmembrane conductance regulator lung epithelial cells: involvement of extracellular signal-regulated protein kinase 1/2 and c-Jun-NH2-terminal kinase signaling.

Science.gov (United States)

Roque, Telma; Boncoeur, Emilie; Saint-Criq, Vinciane; Bonvin, Elise; Clement, Annick; Tabary, Olivier; Jacquot, Jacky

2008-09-01

Sodium 4-phenylbutyrate (4-PBA) has attracted a great deal of attention in cystic fibrosis (CF) pathology due to its capacity to traffic DeltaF508-cystic fibrosis transmembrane conductance regulator (CFTR) to the cell membrane and restore CFTR chloride function at the plasma membrane of CF lung cells in vitro and in vivo. Using two different DeltaF508-CFTR lung epithelial cell lines (CFBE41o- and IB3-1 cells, characterized with DeltaF508-homozygous and heterozygous genotype, respectively) in vitro, 4-PBA induced an increase of proinflammatory cytokine interleukin (IL)-8 production in a concentration-dependent manner. This 4-PBA-induced IL-8 production was associated with a strong reduction of proteasome and nuclear factor-kappaB transcriptional activities in the two DeltaF508-CFTR lung cells either in a resting state or after tumor necrosis factor-alpha stimulation. In contrast, a strong increase of activator protein-1 transcriptional activity was observed. The inhibition of extracellular signal-regulated protein kinase 1/2 (ERK1/2) by 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio] butadiene (U0126) and 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059) and c-Jun-NH(2)-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) by anthra[1,9-cd] pyrazol-6 (2H)-one (SP600125), respectively, was associated with a reduction (2-3.5-fold) of IL-8 production in both DeltaF508-CFTR lung cell lines treated with 4-PBA. No significant change of IL-8 production was observed after an inhibition of p38 MAPK with 4-[4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazol-2-yl] phenol (SB202190). Therefore, we suggest that inhibition of both ERK1/2 and JNK signaling may be a means to strongly reduce 4-PBA-induced IL-8 production in combination with 4-PBA treatment to restore CFTR Cl(-) channel function in lung epithelial cells of patients with CF.

Optimality and self-organization in river deltas

Science.gov (United States)

Tejedor, A.; Longjas, A.; Edmonds, D. A.; Zaliapin, I. V.; Georgiou, T. T.; Rinaldo, A.; Foufoula-Georgiou, E.

2017-12-01

Deltas are nourished by channel networks, whose connectivity constrains, if not drives, the evolution, functionality and resilience of these systems. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. However, in contrast to tributary channel networks, to date, no theory has been proposed to explain how deltas self-organize to distribute water and sediment to the delta top and the shoreline. Here, we hypothesize the existence of an optimality principle underlying the self-organized partition of fluxes in delta channel networks. Specifically, we hypothesize that deltas distribute water and sediment fluxes on a given delta topology such as to maximize the diversity of flux delivery to the shoreline. By introducing the concept of nonlocal Entropy Rate (nER) and analyzing ten field deltas in diverse environments, we present evidence that supports our hypothesis, suggesting that delta networks achieve dynamically accessible maxima of their nER. Furthermore, by analyzing six simulated deltas using the Delf3D model and following their topologic and flux re-organization before and after major avulsions, we further study the evolution of nER and confirm our hypothesis. We discuss how optimal flux distributions in terms of nER, when interpreted in terms of resilience, are configurations that reflect an increased ability to withstand perturbations.

linear accelerator simulation framework with placet and guinea-pig

CERN Document Server

Snuverink, Jochem; CERN. Geneva. ATS Department

2016-01-01

Many good tracking tools are available for simulations for linear accelerators. However, several simple tasks need to be performed repeatedly, like lattice definitions, beam setup, output storage, etc. In addition, complex simulations can become unmanageable quite easily. A high level layer would therefore be beneficial. We propose LinSim, a linear accelerator framework with the codes PLACET and GUINEA-PIG. It provides a documented well-debugged high level layer of functionality. Users only need to provide the input settings and essential code and / or use some of the many implemented imperfections and algorithms. It can be especially useful for first-time users. Currently the following accelerators are implemented: ATF2, ILC, CLIC and FACET. This note is the comprehensive manual, discusses the framework design and shows its strength in some condensed examples.

Sensitivity study of surface wind flow of a limited area model simulating the extratropical storm Delta affecting the Canary Islands

Directory of Open Access Journals (Sweden)

C. Marrero

2009-04-01

Full Text Available In November 2005 an extratropical storm named Delta affected the Canary Islands (Spain. The high sustained wind and intense gusts experienced caused significant damage. A numerical sensitivity study of Delta was conducted using the Weather Research & Forecasting Model (WRF-ARW. A total of 27 simulations were performed. Non-hydrostatic and hydrostatic experiments were designed taking into account physical parameterizations and geometrical factors (size and position of the outer domain, definition or not of nested grids, horizontal resolution and number of vertical levels. The Factor Separation Method was applied in order to identify the major model sensitivity parameters under this unusual meteorological situation. Results associated to percentage changes relatives to a control run simulation demonstrated that boundary layer and surface layer schemes, horizontal resolutions, hydrostaticity option and nesting grid activation were the model configuration parameters with the greatest impact on the 48 h maximum 10 m horizontal wind speed solution.

Further development of the V-code for recirculating linear accelerator simulations

Energy Technology Data Exchange (ETDEWEB)

Franke, Sylvain; Ackermann, Wolfgang; Weiland, Thomas [Institut fuer Theorie Elektromagnetischer Felder, Technische Universitaet Darmstadt (Germany); Eichhorn, Ralf; Hug, Florian; Kleinmann, Michaela; Platz, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany)

2011-07-01

The Superconducting Darmstaedter LINear Accelerator (S-DALINAC) installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a recirculating linear accelerator. The beam is first accelerated up to 10 MeV in the injector beam line. Then it is deflected by 180 degrees into the main linac. The linac section with eight superconducting cavities is passed up to three times, providing a maximal energy gain of 40 MeV on each passage. Due to this recirculating layout it is complicated to find an accurate setup for the various beam line elements. Fast online beam dynamics simulations can advantageously assist the operators because they provide a more detailed insight into the actual machine status. In this contribution further developments of the moment based simulation tool V-code which enables to simulate recirculating machines are presented together with simulation results.

A new identification method for energetic ion {delta}E-E telescopes

Energy Technology Data Exchange (ETDEWEB)

Martin, Cesar [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts, Universitaet zu Kiel, 24118 Kiel (Germany); Bronchalo, Enrique [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, Avda. Universidad s/n, 03202 Elche, Alicante (Spain)], E-mail: ebronchalo@umh.es; Medina, Jose [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain)

2007-11-21

A new ion identification method for {delta}E-E telescopes is presented. The method works by counting data points under {delta}E(E) curves on {delta}E-E diagrams. These curves are obtained by simulating the telescope response to a flux of energetic ions. The method is checked against three published methods applied to several experimental data sets.

The dynamic response of a linear brushless D.C. motor

Energy Technology Data Exchange (ETDEWEB)

Moghani, J.S.; Eastham, J.F. [Univ. of Bath (United Kingdom). School of Electrical and Electronic Engineering

1995-12-31

The paper describes the use of the Matlab Analogue Simulation Toolbox SIMULINK for the closed loop dynamic modeling of a linear brushless dc motor which is supplied from a delta-modulated inverter. The work is validated by experimental results taken from a large test rig. Linear version of all rotating machines are possible; a rotating machine can be notionally cut along a radial plane and unrolled to yield a linear version. The most popular form of linear machine, as judged by the quantities that have been produced is the linear induction motor. This has the advantage of first an inexpensive secondary that is often a simple iron backed conducting plate, and secondly the possibility of simple voltage control. The linear brushless synchronous motor is potentially more expensive to produce than its induction counterpart because of the permanent magnets which provide the excitation mmf and the necessity of an inverter supply. However the machine has a power factor efficiency product which can be double that of an induction motor together with about twice the tractive force per pole area.

DELTAS: A new Global Delta Sustainability Initiative (Invited)

Science.gov (United States)

Foufoula-Georgiou, E.

2013-12-01

Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

Linear switched reluctance motor control with PIC18F452 microcontroller

OpenAIRE

DURSUN, Mahir; KOÇ, Fatmagül

2014-01-01

This paper presents the simulation, control, and experimental results of the velocity of a double-sided, 6/4-poled, 3-phased, 8 A, 24 V, 250 W, and 250 N pull force linear switched reluctance motor (LSRM). In the simulation and experimental study, the reference velocity is constant depending on the position and time. The velocity versus the position of the translator was controlled with fuzzy logic control (FLC) and proportional-integral (PI) control techniques. The motor was control...

Interactions between nested sunspots. 1: The formation and breakup of a delta-type sunspot

Science.gov (United States)

Gaizauskas, V.; Harvey, K. L.; Proulx, M.

1994-01-01

We investigate a nest of sunspots in which three ordinary bipolar pairs of sunspots are aligned collinearly. The usual spreading action of the growing regions brings two spots of leading polarity together (p-p collision) and forces the leading and trailing spots of the two interior regions to overlap inot a single penumbra (p-f collision), thus forming a delta-spot. We examine digitally processed images from the Ottawa River Solar Observatory of two related events inside the delta-spot 5 days after the p-f collision begins: the violent disruption of the f-umbra, and the formation in less than a day of an hydrogen-alpha filament. The evolutionary changes in shape, area, relative motions, and brightness that we measure for each spot in the elongated nest are more compatible with Parker's (1979a) hypothesis of a sunspot as a cluster of flux tubes held together by downdrafts than with the notion of a sunspot as a monolithic plug of magnetic flux. From chromospheric developments over the delta-spot, we show that a shearing motion along a polarity inversion is more effective than convergence for creating a chromospheric filament. We invoke the release of an instability, triggered by a sequence of processes lasting 1 day or more, to explain the disruption of the f-umbra in this delta-spot. We show that the sequence is initiated when the colliding p-f umbrae reach a critical separation around 3200 +/- 200 km. We present a descriptive model in which the reconnected magnetic fields block vertical transport of convective heat flux just beneath the photosphere. We observe the formation of an unusual type of penumbra adjacent to the f-polarity portion of this delta-spot just before its disruption. A tangential penumbral band grows out of disordered matter connected to the f-umbra. We present this as evidence for the extrusion of umbral magnetic flux by thermal plumes rising through a loosely bound umbra.

On the linearity of cross-correlation delay times

Science.gov (United States)

Mercerat, E. D.; Nolet, G.

2012-12-01

We investigate the question whether a P-wave delay time Δ T estimated by locating the maximum of the cross-correlation function between data d(t) and a predicted test function s(t): γ (t) = ∫ t1t_2 s(τ ) d(τ -t) \\ {d}τ, provides an estimate of the Delta T that is (quasi-)linear with the relative velocity perturbation deltaln V_P}. Such linearity is intuitive if the data d(t) is an undeformed but delayed replica of the test signal, i.e. if d(t)=s(t-Delta T). Then the maximum of gamma (t) is shifted exactly by the delay Delta T, and linearity holds even for Delta T very large. In this case, we say that the body waves are in the ray theoretical regime and their delays, because of Fermat's Principle, depend quasi-linearly on the relative velocity (or slowness) perturbations deltaln V_P in the model. However, even if we correct for dispersion induced by the instrument response and by attenuation, body waves may show frequency dependent delay times that are caused by diffraction effects around lateral heterogeneities. It is not a-priori clear that linearity holds for Delta T, as is assumed in finite-frequency theory, if the waveforms of d(t) and s(t) differ substantially because of such dispersion. To test the linearity, we generate synthetic seismograms between two boreholes, and between the boreholes and the surface, in a 3D box of 200 × 120 × 120 m. The heterogeneity is a checkerboard with cubic anomalies of size 12 × 12 × 12 m. We test two different anomaly amplitudes: ± 2% and ± 5%, and measure Delta T using a test seismogram s(t) computed for an homogeneous medium. We also predict the delays for the 5% model from those in the 2% model by multiplying with 5/2. These predictions are in error by 10-20% of the delay, which is usually acceptable for tomography when compared with actual data errors. A slight bias in the prediction indicates that the Wielandt effect - the fact that negative delays suffer less wavefront healing than positive delays - is a

GYSELA, a full-f global gyrokinetic Semi-Lagrangian code for ITG turbulence simulations

International Nuclear Information System (INIS)

Grandgirard, V.; Sarazin, Y.; Garbet, X.; Dif-Pradalier, G.; Ghendrih, Ph.; Crouseilles, N.; Latu, G.; Sonnendruecker, E.; Besse, N.; Bertrand, P.

2006-01-01

This work addresses non-linear global gyrokinetic simulations of ion temperature gradient (ITG) driven turbulence with the GYSELA code. The particularity of GYSELA code is to use a fixed grid with a Semi-Lagrangian (SL) scheme and this for the entire distribution function. The 4D non-linear drift-kinetic version of the code already showns the interest of such a SL method which exhibits good properties of energy conservation in non-linear regime as well as an accurate description of fine spatial scales. The code has been upgrated to run 5D simulations of toroidal ITG turbulence. Linear benchmarks and non-linear first results prove that semi-lagrangian codes can be a credible alternative for gyrokinetic simulations

Accelerating transient simulation of linear reduced order models.

Energy Technology Data Exchange (ETDEWEB)

Thornquist, Heidi K.; Mei, Ting; Keiter, Eric Richard; Bond, Brad

2011-10-01

Model order reduction (MOR) techniques have been used to facilitate the analysis of dynamical systems for many years. Although existing model reduction techniques are capable of providing huge speedups in the frequency domain analysis (i.e. AC response) of linear systems, such speedups are often not obtained when performing transient analysis on the systems, particularly when coupled with other circuit components. Reduced system size, which is the ostensible goal of MOR methods, is often insufficient to improve transient simulation speed on realistic circuit problems. It can be shown that making the correct reduced order model (ROM) implementation choices is crucial to the practical application of MOR methods. In this report we investigate methods for accelerating the simulation of circuits containing ROM blocks using the circuit simulator Xyce.

Rapid Monte Carlo simulation of detector DQE(f)

Energy Technology Data Exchange (ETDEWEB)

Star-Lack, Josh, E-mail: josh.starlack@varian.com; Sun, Mingshan; Abel, Eric [Varian Medical Systems, Palo Alto, California 94304-1030 (United States); Meyer, Andre; Morf, Daniel [Varian Medical Systems, CH-5405, Baden-Dattwil (Switzerland); Constantin, Dragos; Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

2014-03-15

Purpose: Performance optimization of indirect x-ray detectors requires proper characterization of both ionizing (gamma) and optical photon transport in a heterogeneous medium. As the tool of choice for modeling detector physics, Monte Carlo methods have failed to gain traction as a design utility, due mostly to excessive simulation times and a lack of convenient simulation packages. The most important figure-of-merit in assessing detector performance is the detective quantum efficiency (DQE), for which most of the computational burden has traditionally been associated with the determination of the noise power spectrum (NPS) from an ensemble of flood images, each conventionally having 10{sup 7} − 10{sup 9} detected gamma photons. In this work, the authors show that the idealized conditions inherent in a numerical simulation allow for a dramatic reduction in the number of gamma and optical photons required to accurately predict the NPS. Methods: The authors derived an expression for the mean squared error (MSE) of a simulated NPS when computed using the International Electrotechnical Commission-recommended technique based on taking the 2D Fourier transform of flood images. It is shown that the MSE is inversely proportional to the number of flood images, and is independent of the input fluence provided that the input fluence is above a minimal value that avoids biasing the estimate. The authors then propose to further lower the input fluence so that each event creates a point-spread function rather than a flood field. The authors use this finding as the foundation for a novel algorithm in which the characteristic MTF(f), NPS(f), and DQE(f) curves are simultaneously generated from the results of a single run. The authors also investigate lowering the number of optical photons used in a scintillator simulation to further increase efficiency. Simulation results are compared with measurements performed on a Varian AS1000 portal imager, and with a previously published

Rapid Monte Carlo simulation of detector DQE(f)

International Nuclear Information System (INIS)

Star-Lack, Josh; Sun, Mingshan; Abel, Eric; Meyer, Andre; Morf, Daniel; Constantin, Dragos; Fahrig, Rebecca

2014-01-01

Purpose: Performance optimization of indirect x-ray detectors requires proper characterization of both ionizing (gamma) and optical photon transport in a heterogeneous medium. As the tool of choice for modeling detector physics, Monte Carlo methods have failed to gain traction as a design utility, due mostly to excessive simulation times and a lack of convenient simulation packages. The most important figure-of-merit in assessing detector performance is the detective quantum efficiency (DQE), for which most of the computational burden has traditionally been associated with the determination of the noise power spectrum (NPS) from an ensemble of flood images, each conventionally having 10 7 − 10 9 detected gamma photons. In this work, the authors show that the idealized conditions inherent in a numerical simulation allow for a dramatic reduction in the number of gamma and optical photons required to accurately predict the NPS. Methods: The authors derived an expression for the mean squared error (MSE) of a simulated NPS when computed using the International Electrotechnical Commission-recommended technique based on taking the 2D Fourier transform of flood images. It is shown that the MSE is inversely proportional to the number of flood images, and is independent of the input fluence provided that the input fluence is above a minimal value that avoids biasing the estimate. The authors then propose to further lower the input fluence so that each event creates a point-spread function rather than a flood field. The authors use this finding as the foundation for a novel algorithm in which the characteristic MTF(f), NPS(f), and DQE(f) curves are simultaneously generated from the results of a single run. The authors also investigate lowering the number of optical photons used in a scintillator simulation to further increase efficiency. Simulation results are compared with measurements performed on a Varian AS1000 portal imager, and with a previously published simulation

Performance of uncertainty quantification methodologies and linear solvers in cardiovascular simulations

Science.gov (United States)

Seo, Jongmin; Schiavazzi, Daniele; Marsden, Alison

2017-11-01

Cardiovascular simulations are increasingly used in clinical decision making, surgical planning, and disease diagnostics. Patient-specific modeling and simulation typically proceeds through a pipeline from anatomic model construction using medical image data to blood flow simulation and analysis. To provide confidence intervals on simulation predictions, we use an uncertainty quantification (UQ) framework to analyze the effects of numerous uncertainties that stem from clinical data acquisition, modeling, material properties, and boundary condition selection. However, UQ poses a computational challenge requiring multiple evaluations of the Navier-Stokes equations in complex 3-D models. To achieve efficiency in UQ problems with many function evaluations, we implement and compare a range of iterative linear solver and preconditioning techniques in our flow solver. We then discuss applications to patient-specific cardiovascular simulation and how the problem/boundary condition formulation in the solver affects the selection of the most efficient linear solver. Finally, we discuss performance improvements in the context of uncertainty propagation. Support from National Institute of Health (R01 EB018302) is greatly appreciated.

FAST modularization framework for wind turbine simulation: full-system linearization

Science.gov (United States)

Jonkman, J. M.; Jonkman, B. J.

2016-09-01

The wind engineering community relies on multiphysics engineering software to run nonlinear time-domain simulations e.g. for design-standards-based loads analysis. Although most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear system equations is often advantageous to understand the system response and exploit well- established methods and tools for analyzing linear systems. This paper presents the development and verification of the new linearization functionality of the open-source engineering tool FAST v8 for land-based wind turbines, as well as the concepts and mathematical background needed to understand and apply it correctly.

Duality in non-linear B and F models: equivalence between self-dual and topologically massive Born-Infeld B and F models

International Nuclear Information System (INIS)

Menezes, R.; Nascimento, J.R.S.; Ribeiro, R.F.; Wotzasek, C.

2002-01-01

We study the dual equivalence between the non-linear generalization of the self-dual (NSD BF ) and the topologically massive B and F models with particular emphasis on the non-linear electrodynamics proposed by Born and Infeld. This is done through a dynamical gauge embedding of the non-linear self-dual model yielding to a gauge invariant and dynamically equivalent theory. We clearly show that non-polinomial NSD BF models can be map, through a properly defined duality transformation into TM BF actions. The general result obtained is then particularized for a number of examples, including the Born-Infeld-BF (BIBF) model that has experienced a revival in the recent literature

Supersonic flow over a pitching delta wing using surface pressure measurements and numerical simulations

Directory of Open Access Journals (Sweden)

Mostafa HADIDOOLABI

2018-01-01

Full Text Available Experimental and numerical methods were applied to investigating high subsonic and supersonic flows over a 60° swept delta wing in fixed state and pitching oscillation. Static pressure coefficient distributions over the wing leeward surface and the hysteresis loops of pressure coefficient versus angle of attack at the sensor locations were obtained by wind tunnel tests. Similar results were obtained by numerical simulations which agreed well with the experiments. Flow structure around the wing was also demonstrated by the numerical simulation. Effects of Mach number and angle of attack on pressure distribution curves in static tests were investigated. Effects of various oscillation parameters including Mach number, mean angle of attack, pitching amplitude and frequency on hysteresis loops were investigated in dynamic tests and the associated physical mechanisms were discussed. Vortex breakdown phenomenon over the wing was identified at high angles of attack using the pressure coefficient curves and hysteresis loops, and its effects on the flow features were discussed.

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

Science.gov (United States)

Jakymiw, Clément; Vočadlo, Lidunka; Dobson, David P.; Bailey, Edward; Thomson, Andrew R.; Brodholt, John P.; Wood, Ian G.; Lindsay-Scott, Alex

2018-04-01

ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth's deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure ( Cmcm; commonly referred to as the "post-perovskite" structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 ( P63/ mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 ( P21/ m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/ mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2

Full radius linear and nonlinear gyrokinetic simulations for tokamaks and stellarators: Zonal flows, applied E x B flows, trapped electrons and finite beta

International Nuclear Information System (INIS)

Villard, L.; Allfrey, S.J.; Bottino, A.

2003-01-01

The aim of this paper is to report on recent advances made on global gyrokinetic simulations of Ion Temperature Gradient modes (ITG) and other microinstabilities. The nonlinear development and saturation of ITG modes and the role of E x B zonal flows are studied with a global nonlinear δ f formulation that retains parallel nonlinearity and thus allows for a check of the energy conservation property as a means to verify the quality of the numerical simulation. Due to an optimised loading technique the conservation property is satisfied with an unprecedented quality well into the nonlinear stage. The zonal component of the perturbation establishes a quasi-steady state with regions of ITG suppression, strongly reduced radial energy flux and steepened effective temperature profile alternating with regions of higher ITG mode amplitudes, larger radial energy flux and flattened effective temperature profile. A semi-Lagrangian approach free of statistical noise is proposed as an alternative to the nonlinear δf formulation. An ASDEX-Upgrade experiment with an Internal Transport Barrier (ITB) is analysed with a global gyrokinetic code that includes trapped electron dynamics. The weakly destabilizing effect of trapped electron dynamics on ITG modes in an axisymmetric bumpy configuration modelling W7-X is shown in global linear simulations that retain the full electron dynamics. Finite β effects on microinstabilities are investigated with a linear global spectral electromagnetic gyrokinetic formulation. The radial global structure of electromagnetic modes shows a resonant behaviour with rational q values. (author)

Is there a self-organization principle of river deltas?

Science.gov (United States)

Tejedor, Alejandro; Longjas, Anthony; Foufoula-Georgiou, Efi

2017-04-01

River deltas are known to possess a complex topological and flux-partitioning structure which has recently been quantified using spectral graph theory [Tejedor et al., 2015a,b]. By analysis of real and simulated deltas it has also been shown that there is promise in formalizing relationships between this topo-dynamic delta structure and the underlying delta forming processes [e.g., Tejedor et al., 2016]. The question we pose here is whether there exists a first order organizational principle behind the self-organization of river deltas and whether this principle can be unraveled from the co-evolving topo-dynamic structure encoded in the delta planform. To answer this question, we introduce a new metric, the nonlocal Entropy Rate (nER) that captures the information content of a delta network in terms of the degree of uncertainty in delivering fluxes from any point of the network to the shoreline. We hypothesize that if the "guiding principle" of undisturbed deltas is to efficiently and robustly build land by increasing the diversity of their flux pathways over the delta plane, then they would exhibit maximum nonlocal Entropy Rate at states at which geometry and flux dynamics are at equilibrium. At the same time, their nER would be non-optimal at transient states, such as before and after major avulsions during which topology and dynamics adjust to each other to reach a new equilibrium state. We will present our results for field and simulated deltas, which confirm this hypothesis and open up new ways of thinking about self-organization, complexity and robustness in river deltas. One particular connection of interest might have important implications since entropy rate and resilience are related by the fluctuation theorem [Demetrius and Manke, 2005], and therefore our results suggest that deltas might in fact self-organize to maximize their resilience to structural and dynamic perturbations. References: Tejedor, A., A. Longjas, I. Zaliapin, and E. Foufoula

Quality of computerized blast load simulation for non-linear dynamic ...

African Journals Online (AJOL)

Quality of computerized blast load simulation for non-linear dynamic response ... commercial software system and a special-purpose, blast-specific software product to ... depend both on the analysis model of choice and the stand-off distances.

Monte Carlo simulation of OLS and linear mixed model inference of phenotypic effects on gene expression.

Science.gov (United States)

Walker, Jeffrey A

2016-01-01

Self-contained tests estimate and test the association between a phenotype and mean expression level in a gene set defined a priori . Many self-contained gene set analysis methods have been developed but the performance of these methods for phenotypes that are continuous rather than discrete and with multiple nuisance covariates has not been well studied. Here, I use Monte Carlo simulation to evaluate the performance of both novel and previously published (and readily available via R) methods for inferring effects of a continuous predictor on mean expression in the presence of nuisance covariates. The motivating data are a high-profile dataset which was used to show opposing effects of hedonic and eudaimonic well-being (or happiness) on the mean expression level of a set of genes that has been correlated with social adversity (the CTRA gene set). The original analysis of these data used a linear model (GLS) of fixed effects with correlated error to infer effects of Hedonia and Eudaimonia on mean CTRA expression. The standardized effects of Hedonia and Eudaimonia on CTRA gene set expression estimated by GLS were compared to estimates using multivariate (OLS) linear models and generalized estimating equation (GEE) models. The OLS estimates were tested using O'Brien's OLS test, Anderson's permutation [Formula: see text]-test, two permutation F -tests (including GlobalAncova), and a rotation z -test (Roast). The GEE estimates were tested using a Wald test with robust standard errors. The performance (Type I, II, S, and M errors) of all tests was investigated using a Monte Carlo simulation of data explicitly modeled on the re-analyzed dataset. GLS estimates are inconsistent between data sets, and, in each dataset, at least one coefficient is large and highly statistically significant. By contrast, effects estimated by OLS or GEE are very small, especially relative to the standard errors. Bootstrap and permutation GLS distributions suggest that the GLS results in

Modeling multi-source flooding disaster and developing simulation framework in Delta

Science.gov (United States)

Liu, Y.; Cui, X.; Zhang, W.

2016-12-01

Most Delta regions of the world are densely populated and with advanced economies. However, due to impact of the multi-source flooding (upstream flood, rainstorm waterlogging, storm surge flood), the Delta regions is very vulnerable. The academic circles attach great importance to the multi-source flooding disaster in these areas. The Pearl River Delta urban agglomeration in south China is selected as the research area. Based on analysis of natural and environmental characteristics data of the Delta urban agglomeration(remote sensing data, land use data, topographic map, etc.), hydrological monitoring data, research of the uneven distribution and process of regional rainfall, the relationship between the underlying surface and the parameters of runoff, effect of flood storage pattern, we use an automatic or semi-automatic method for dividing spatial units to reflect the runoff characteristics in urban agglomeration, and develop an Multi-model Ensemble System in changing environment, including urban hydrologic model, parallel computational 1D&2D hydrodynamic model, storm surge forecast model and other professional models, the system will have the abilities like real-time setting a variety of boundary conditions, fast and real-time calculation, dynamic presentation of results, powerful statistical analysis function. The model could be optimized and improved by a variety of verification methods. This work was supported by the National Natural Science Foundation of China (41471427); Special Basic Research Key Fund for Central Public Scientific Research Institutes.

Simulated Analysis of Linear Reversible Enzyme Inhibition with SCILAB

Science.gov (United States)

Antuch, Manuel; Ramos, Yaquelin; Álvarez, Rubén

2014-01-01

SCILAB is a lesser-known program (than MATLAB) for numeric simulations and has the advantage of being free software. A challenging software-based activity to analyze the most common linear reversible inhibition types with SCILAB is described. Students establish typical values for the concentration of enzyme, substrate, and inhibitor to simulate…

Effect of delta wing on the particle flow in a novel gas supersonic separator

DEFF Research Database (Denmark)

Wen, Chuang; Yang, Yan; Walther, Jens Honore

2016-01-01

The present work presents numerical simulations of the complex particle motion in a supersonic separator with a delta wing located in the supersonic flow. The effect of the delta wing on the strong swirling flow is analysed using the Discrete Particle Method. The results show that the delta wings...

Monte Carlo simulations of the stability of delta-Pu

DEFF Research Database (Denmark)

Landa, A.; Soderlind, P.; Ruban, Andrei

2003-01-01

The transition temperature (T-c) for delta-Pu has been calculated for the first time. A Monte Carlo method is employed for this purpose and the effective cluster interactions are obtained from first-principles calculations incorporated with the Connolly-Williams and generalized perturbation methods...

F-15 PCA (Propulsion Controlled Aircraft) Simulation Cockpit

Science.gov (United States)

1990-01-01

The F-15 PCA (Propulsion Controlled Aircraft) simulation was used from 1990 to 1993. It was used for the development of propulsion algorithms and piloting techniques (using throttles only) to be used for emergency flight control in the advent of a major flight control system failure on a multi-engine aircraft. Following this program with the Dryden F-15, similiar capabilities were developed for other aircraft, such as the B-720, Lear 24, B-727, C-402, and B-747.

Naturalness in low-scale SUSY models and "non-linear" MSSM

CERN Document Server

Antoniadis, I; Ghilencea, D M

2014-01-01

In MSSM models with various boundary conditions for the soft breaking terms (m_{soft}) and for a higgs mass of 126 GeV, there is a (minimal) electroweak fine-tuning Delta\\approx 800 to 1000 for the constrained MSSM and Delta\\approx 500 for non-universal gaugino masses. These values, often regarded as unacceptably large, may indicate a problem of supersymmetry (SUSY) breaking, rather than of SUSY itself. A minimal modification of these models is to lower the SUSY breaking scale in the hidden sector (\\sqrt f) to few TeV, which we show to restore naturalness to more acceptable levels Delta\\approx 80 for the most conservative case of low tan_beta and ultraviolet boundary conditions as in the constrained MSSM. This is done without introducing additional fields in the visible sector, unlike other models that attempt to reduce Delta. In the present case Delta is reduced due to additional (effective) quartic higgs couplings proportional to the ratio m_{soft}/(\\sqrt f) of the visible to the hidden sector SUSY breaking...

Fast simulation of non-linear pulsed ultrasound fields using an angular spectrum approach

DEFF Research Database (Denmark)

Du, Yigang; Jensen, Jørgen Arendt

2013-01-01

A fast non-linear pulsed ultrasound field simulation is presented. It is implemented based on an angular spectrum approach (ASA), which analytically solves the non-linear wave equation. The ASA solution to the Westervelt equation is derived in detail. The calculation speed is significantly...... increased compared to a numerical solution using an operator splitting method (OSM). The ASA has been modified and extended to pulsed non-linear ultrasound fields in combination with Field II, where any array transducer with arbitrary geometry, excitation, focusing and apodization can be simulated...... with a center frequency of 5 MHz. The speed is increased approximately by a factor of 140 and the calculation time is 12 min with a standard PC, when simulating the second harmonic pulse at the focal point. For the second harmonic point spread function the full width error is 1.5% at 6 dB and 6.4% at 12 d...

Feature-space-based FMRI analysis using the optimal linear transformation.

Science.gov (United States)

Sun, Fengrong; Morris, Drew; Lee, Wayne; Taylor, Margot J; Mills, Travis; Babyn, Paul S

2010-09-01

The optimal linear transformation (OLT), an image analysis technique of feature space, was first presented in the field of MRI. This paper proposes a method of extending OLT from MRI to functional MRI (fMRI) to improve the activation-detection performance over conventional approaches of fMRI analysis. In this method, first, ideal hemodynamic response time series for different stimuli were generated by convolving the theoretical hemodynamic response model with the stimulus timing. Second, constructing hypothetical signature vectors for different activity patterns of interest by virtue of the ideal hemodynamic responses, OLT was used to extract features of fMRI data. The resultant feature space had particular geometric clustering properties. It was then classified into different groups, each pertaining to an activity pattern of interest; the applied signature vector for each group was obtained by averaging. Third, using the applied signature vectors, OLT was applied again to generate fMRI composite images with high SNRs for the desired activity patterns. Simulations and a blocked fMRI experiment were employed for the method to be verified and compared with the general linear model (GLM)-based analysis. The simulation studies and the experimental results indicated the superiority of the proposed method over the GLM-based analysis in detecting brain activities.

Global full-f gyrokinetic simulations of plasma turbulence

International Nuclear Information System (INIS)

Grandgirard, V; Sarazin, Y; Angelino, P; Bottino, A; Crouseilles, N; Darmet, G; Dif-Pradalier, G; Garbet, X; Ghendrih, Ph; Jolliet, S; Latu, G; Sonnendruecker, E; Villard, L

2007-01-01

Critical physical issues can be specifically tackled with the global full-f gyrokinetic code GYSELA. Three main results are presented. First, the self-consistent treatment of equilibrium and fluctuations highlights the competition between two compensation mechanisms for the curvature driven vertical charge separation, namely, parallel flow and polarization. The impact of the latter on the turbulent transport is discussed. In the non-linear regime, the benchmark with the Particle-In-Cell code ORB5 looks satisfactory. Second, the transport scaling with ρ * is found to depend both on ρ * itself and on the distance to the linear threshold. Finally, a statistical steady-state turbulent regime is achieved in a reduced version of GYSELA by prescribing a constant heat source

Simulation of non-linear ultrasound fields

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt; Fox, Paul D.; Wilhjelm, Jens E.

2002-01-01

-linear propagation. The speed of sound is calculated from the instantaneous pressure of the pulse and the nonlinearity B/A parameter of the medium. The harmonic field is found by introducing a number of virtual planes in front of the aperture and then propagating the pulse using Burgers' solution between the planes....... Simulations on the acoustical axis of an array transducer were performed and compared to measurements made in a water tank. A 3 MHz convex array transducer with a pitch of 0.53 mm and a height of 13 mm was used. The electronic focus was at 45 mm and 16 elements were used for emission. The emitted pressure...... was 1.4 MPa measured 6 mm from the aperture by a Force Institute MH25-5 needle hydrophone in a water bath. The build-up of higher harmonics can here be predicted accurately up to the 5th harmonic. The second harmonic is simulated with an accuracy of ±2.6 dB and the third harmonic with ±2 dB compared...

Linear simulations of the cylindrical Richtmyer-Meshkov instability in magnetohydrodynamics

KAUST Repository

Bakhsh, Abeer; Gao, Song; Samtaney, Ravi; Wheatley, V.

2016-01-01

fusion and suppression by means of a magnetic field, we investigate the RMI via linear MHD simulations in cylindrical geometry. The physical setup is that of a Chisnell-type converging shock interacting with a density interface with either axial

PCDD/F and Aromatic Emissions from Simulated Forest and Grassland Fires

Science.gov (United States)

Emissions of polychlorinated dibenzodioxin and polychlorinated dibenzofuran (PCDD/F) from simulated grassland and forest fires were quantitatively sampled to derive emission factors in support of PCDD/F inventory development. Grasses from Kentucky and Minnesota; forest shrubs fro...

Neurosurgery simulation using non-linear finite element modeling and haptic interaction

Science.gov (United States)

Lee, Huai-Ping; Audette, Michel; Joldes, Grand R.; Enquobahrie, Andinet

2012-02-01

Real-time surgical simulation is becoming an important component of surgical training. To meet the realtime requirement, however, the accuracy of the biomechancial modeling of soft tissue is often compromised due to computing resource constraints. Furthermore, haptic integration presents an additional challenge with its requirement for a high update rate. As a result, most real-time surgical simulation systems employ a linear elasticity model, simplified numerical methods such as the boundary element method or spring-particle systems, and coarse volumetric meshes. However, these systems are not clinically realistic. We present here an ongoing work aimed at developing an efficient and physically realistic neurosurgery simulator using a non-linear finite element method (FEM) with haptic interaction. Real-time finite element analysis is achieved by utilizing the total Lagrangian explicit dynamic (TLED) formulation and GPU acceleration of per-node and per-element operations. We employ a virtual coupling method for separating deformable body simulation and collision detection from haptic rendering, which needs to be updated at a much higher rate than the visual simulation. The system provides accurate biomechancial modeling of soft tissue while retaining a real-time performance with haptic interaction. However, our experiments showed that the stability of the simulator depends heavily on the material property of the tissue and the speed of colliding objects. Hence, additional efforts including dynamic relaxation are required to improve the stability of the system.

Design of the 12-bit Delta-Sigma Modulator using SC Technique for Vibration Sensor Output Processing

Directory of Open Access Journals (Sweden)

M. Pavlik

2012-04-01

Full Text Available The work deals with the design of the 12-bit Delta-Sigma modulator using switched capacitors (SC technique. The modulator serves to vibration sensor output processing. The first part describes the Delta-Sigma modulator parameters definition. Results of the proposed topology ideal model were presented as well. Next, the Delta-Sigma modulator circuitry on the transistor level was done. The ONSemiconductor I2T100 0.7 um CMOS technology was used for design. Then, the Delta-Sigma modulator nonidealities were simulated and implemented into the MATLAB ideal model of the modulator. The model of real Delta-Sigma modulator was derived. Consequently, modulator coefficients were optimized. Finally, the corner analysis of the Delta-Sigma modulator with the optimized coefficients was simulated. The value of SNDR = 82.2 dB (ENOB = 13.4 bits was achieved.

Container cargo simulation modeling for measuring impacts of infrastructure investment projects in Pearl River Delta

Science.gov (United States)

Li, Jia-Qi; Shibasaki, Ryuichi; Li, Bo-Wei

2010-03-01

In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement.

Noiseless Vlasov–Poisson simulations with linearly transformed particles

Energy Technology Data Exchange (ETDEWEB)

Campos Pinto, Martin, E-mail: campos@ann.jussieu.fr [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); CNRS, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); UPMC Univ. Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); Sonnendrücker, Eric, E-mail: sonnen@math.unistra.fr [IRMA, UMR 7501, Université de Strasbourg and CNRS, 7 rue René Descartes, F-67084 Strasbourg Cedex (France); Project-team CALVI, INRIA Nancy Grand Est, 7 rue René Descartes, F-67084 Strasbourg Cedex (France); Friedman, Alex, E-mail: af@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grote, David P., E-mail: grote1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lund, Steve M., E-mail: smlund@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2014-10-15

We introduce a deterministic discrete-particle simulation approach, the Linearly-Transformed Particle-In-Cell (LTPIC) method, that employs linear deformations of the particles to reduce the noise traditionally associated with particle schemes. Formally, transforming the particles is justified by local first order expansions of the characteristic flow in phase space. In practice the method amounts of using deformation matrices within the particle shape functions; these matrices are updated via local evaluations of the forward numerical flow. Because it is necessary to periodically remap the particles on a regular grid to avoid excessively deforming their shapes, the method can be seen as a development of Denavit's Forward Semi-Lagrangian (FSL) scheme (Denavit, 1972 [8]). However, it has recently been established (Campos Pinto, 2012 [20]) that the underlying Linearly-Transformed Particle scheme converges for abstract transport problems, with no need to remap the particles; deforming the particles can thus be seen as a way to significantly lower the remapping frequency needed in the FSL schemes, and hence the associated numerical diffusion. To couple the method with electrostatic field solvers, two specific charge deposition schemes are examined, and their performance compared with that of the standard deposition method. Finally, numerical 1d1v simulations involving benchmark test cases and halo formation in an initially mismatched thermal sheet beam demonstrate some advantages of our LTPIC scheme over the classical PIC and FSL methods. Benchmarked test cases also indicate that, for numerical choices involving similar computational effort, the LTPIC method is capable of accuracy comparable to or exceeding that of state-of-the-art, high-resolution Vlasov schemes.

A database of linear codes over F_13 with minimum distance bounds and new quasi-twisted codes from a heuristic search algorithm

Directory of Open Access Journals (Sweden)

Eric Z. Chen

2015-01-01

Full Text Available Error control codes have been widely used in data communications and storage systems. One central problem in coding theory is to optimize the parameters of a linear code and construct codes with best possible parameters. There are tables of best-known linear codes over finite fields of sizes up to 9. Recently, there has been a growing interest in codes over $\\mathbb{F}_{13}$ and other fields of size greater than 9. The main purpose of this work is to present a database of best-known linear codes over the field $\\mathbb{F}_{13}$ together with upper bounds on the minimum distances. To find good linear codes to establish lower bounds on minimum distances, an iterative heuristic computer search algorithm is employed to construct quasi-twisted (QT codes over the field $\\mathbb{F}_{13}$ with high minimum distances. A large number of new linear codes have been found, improving previously best-known results. Tables of $[pm, m]$ QT codes over $\\mathbb{F}_{13}$ with best-known minimum distances as well as a table of lower and upper bounds on the minimum distances for linear codes of length up to 150 and dimension up to 6 are presented.

FAST Modularization Framework for Wind Turbine Simulation: Full-System Linearization: Preprint

Energy Technology Data Exchange (ETDEWEB)

Jonkman, Jason; Jonkman, Bonnie

2016-11-01

The wind engineering community relies on multiphysics engineering software to run nonlinear time-domain simulations e.g. for design-standards-based loads analysis. Although most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear system equations is often advantageous to understand the system response and exploit well-established methods and tools for analyzing linear systems. This paper presents the development and verification of the new linearization functionality of the open-source engineering tool FAST v8 for land-based wind turbines, as well as the concepts and mathematical background needed to understand and apply it correctly.

Analytical vs. Simulation Solution Techniques for Pulse Problems in Non-linear Stochastic Dynamics

DEFF Research Database (Denmark)

Iwankiewicz, R.; Nielsen, Søren R. K.

Advantages and disadvantages of available analytical and simulation techniques for pulse problems in non-linear stochastic dynamics are discussed. First, random pulse problems, both those which do and do not lead to Markov theory, are presented. Next, the analytical and analytically-numerical tec......Advantages and disadvantages of available analytical and simulation techniques for pulse problems in non-linear stochastic dynamics are discussed. First, random pulse problems, both those which do and do not lead to Markov theory, are presented. Next, the analytical and analytically...

Simulating dynamics of {delta}{sup 13}C of CO{sub 2} in the planetary boundary layer a boreal forest region: covariation between surface fluxes and atmospheric mixing

Energy Technology Data Exchange (ETDEWEB)

Chen, Baozhang; Chen, Jing M. [Univ. of Toronto, ON (Canada). Dept. of Geography; Tans, Pieter P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Earth System Research Lab.; Huang, Lin [Environment Canada, Toronto, ON (Canada). Atmospheric Science and Technology Directorate

2006-11-15

Stable isotopes of CO{sub 2} contain unique information on the biological and physical processes that exchange CO{sub 2} between terrestrial ecosystems and the atmosphere. Ecosystem exchange of carbon isotopes with the atmosphere is correlated diurnally and seasonally with the planetary boundary layer (PBL) dynamics. The strength of this kind of covariation affects the vertical gradient of {delta}{sup 13}C and thus the global {delta}{sup 13}C distribution pattern. We need to understand the various processes involved in transport/diffusion of carbon isotope ratio in the PBL and between the PBL and the biosphere and the troposphere. In this study, we employ a one-dimensional vertical diffusion/transport atmospheric model (VDS), coupled to an ecosystem isotope model (BEPS-EASS) to simulate dynamics of {sup 13}CO{sub 2} in the PBL over a boreal forest region in the vicinity of the Fraserdale (FRD) tower (49 deg 52 min 29.9 sec N, 81 deg 34 min 12.3 sec W) in northern Ontario, Canada. The data from intensive campaigns during the growing season in 1999 at this site are used for model validation in the surface layer. The model performance, overall, is satisfactory in simulating the measured data over the whole course of the growing season. We examine the interaction of the biosphere and the atmosphere through the PBL with respect to {delta}{sup 13}C on diurnal and seasonal scales. The simulated annual mean vertical gradient of {delta}{sup 13}C in the PBL in the vicinity of the FRD tower was about 0.025% in 1999. The {delta}{sup 13}C vertical gradient exhibited strong diurnal (29%) and seasonal (71%) variations that do not exactly mimic those of CO{sub 2}. Most of the vertical gradient (96.5% {+-}) resulted from covariation between ecosystem exchange of carbon isotopes and the PBL dynamics, while the rest (3.5%{+-}) was contributed by isotopic disequilibrium between respiration and photosynthesis. This disequilibrium effect on {delta}{sup 13}C of CO{sub 2} dynamics in PBL

Simulating dynamics of (delta){sup 13}C of CO{sub 2} in the planetary boundary layer a boreal forest region: covariation between surface fluxes and atmospheric mixing

Energy Technology Data Exchange (ETDEWEB)

Chen, Baozhang; Chen, Jing M. [Univ. of Toronto, ON (Canada). Dept. of Geography; Tans, Pieter P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Earth System Research Lab.; Huang, Lin [Environment Canada, Toronto, ON (Canada). Atmospheric Science and Technology Directorate

2006-11-15

Stable isotopes of CO{sub 2} contain unique information on the biological and physical processes that exchange CO{sub 2} between terrestrial ecosystems and the atmosphere. Ecosystem exchange of carbon isotopes with the atmosphere is correlated diurnally and seasonally with the planetary boundary layer (PBL) dynamics. The strength of this kind of covariation affects the vertical gradient of (delta){sup 13}C and thus the global (delta){sup 13}C distribution pattern. We need to understand the various processes involved in transport/diffusion of carbon isotope ratio in the PBL and between the PBL and the biosphere and the troposphere. In this study, we employ a one-dimensional vertical diffusion/transport atmospheric model (VDS), coupled to an ecosystem isotope model (BEPS-EASS) to simulate dynamics of {sup 13}CO{sub 2} in the PBL over a boreal forest region in the vicinity of the Fraserdale (FRD) tower (49 deg 52 min 29.9 sec N, 81 deg 34 min 12.3 sec W) in northern Ontario, Canada. The data from intensive campaigns during the growing season in 1999 at this site are used for model validation in the surface layer. The model performance, overall, is satisfactory in simulating the measured data over the whole course of the growing season. We examine the interaction of the biosphere and the atmosphere through the PBL with respect to (delta){sup 13}C on diurnal and seasonal scales. The simulated annual mean vertical gradient of (delta){sup 13}C in the PBL in the vicinity of the FRD tower was about 0.025% in 1999. The (delta){sup 13}C vertical gradient exhibited strong diurnal (29%) and seasonal (71%) variations that do not exactly mimic those of CO{sub 2}. Most of the vertical gradient (96.5% {+-}) resulted from covariation between ecosystem exchange of carbon isotopes and the PBL dynamics, while the rest (3.5%{+-}) was contributed by isotopic disequilibrium between respiration and photosynthesis. This disequilibrium effect on (delta){sup 13}C of CO{sub 2} dynamics in PBL

Numerical simulation of electro-osmotic consolidation coupling non-linear variation of soil parameters

Science.gov (United States)

Wu, Hui; Hu, Liming; Wen, Qingbo

2017-06-01

Electro-osmotic consolidation is an effective method for soft ground improvement. A main limitation of previous numerical models on this technique is the ignorance of the non-linear variation of soil parameters. In the present study, a multi-field numerical model is developed with the consideration of the non-linear variation of soil parameters during electro-osmotic consolidation process. The numerical simulations on an axisymmetric model indicated that the non-linear variation of soil parameters showed remarkable impact on the development of the excess pore water pressure and degree of consolidation. A field experiment with complex geometry, boundary conditions, electrode configuration and voltage application was further simulated with the developed numerical model. The comparison between field and numerical data indicated that the numerical model coupling of the non-linear variation of soil parameters gave more reasonable results. The developed numerical model is capable to analyze engineering cases with complex operating conditions.

Global full-f gyrokinetic simulations of plasma turbulence

Energy Technology Data Exchange (ETDEWEB)

Grandgirard, V [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Sarazin, Y [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Angelino, P [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Bottino, A [Max Plank Institut fr Plasmaphysik, IPP-EURATOM AssociationGarching (Germany); Crouseilles, N [IRMA, Universite Louis Pasteur, 7, rue Rene Descartes, 67084 Strasbourg Cedex (France); Darmet, G [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Dif-Pradalier, G [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Garbet, X [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Ghendrih, Ph [CEA/DSM/DRFC, Association Euratom-CEA, Cadarache, 13108 St Paul-lez-Durance (France); Jolliet, S [CRPP, Association Euratom-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Latu, G [LaBRI, 341 Cours Liberation, 33405 Talence Cedex (France); Sonnendruecker, E [IRMA, Universite Louis Pasteur, 7, rue Rene Descartes, 67084 Strasbourg Cedex (France); Villard, L [CRPP, Association Euratom-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland)

2007-12-15

Critical physical issues can be specifically tackled with the global full-f gyrokinetic code GYSELA. Three main results are presented. First, the self-consistent treatment of equilibrium and fluctuations highlights the competition between two compensation mechanisms for the curvature driven vertical charge separation, namely, parallel flow and polarization. The impact of the latter on the turbulent transport is discussed. In the non-linear regime, the benchmark with the Particle-In-Cell code ORB5 looks satisfactory. Second, the transport scaling with {rho}{sub *} is found to depend both on {rho}{sub *} itself and on the distance to the linear threshold. Finally, a statistical steady-state turbulent regime is achieved in a reduced version of GYSELA by prescribing a constant heat source.

Effect of environmental change on the morphology of tidally influenced deltas over multi-decadal timescale

Science.gov (United States)

Angamuthu, Balaji; Darby, Stephen; Nicholls, Robert

2017-04-01

An understanding of the geomorphological processes affecting deltas is essential to improve our understanding of the risks that deltas face, especially as human impacts are likely to intensify in the future. Unfortunately, there is limited reliable data on river deltas, meaning that the task of demonstrating the links between morphodynamic and environmental change is challenging. This presentation aims to answer the questions of how delta morphology evolves over multi-decadal timescales under multiple drivers, focussing on tidally-influenced deltas, as some of these, such as the Ganges-Brahmaputra-Meghna (GBM) delta are heavily populated. A series of idealised model simulations over 102 years were used to explore the influence of three key drivers on delta morphodynamics, both individually and together: (i) varying combinations of water and sediment discharges from the upstream catchment, (ii) varying rates of relative sea-level rise (RSLR), and (iii) selected human interventions within the delta, such as polders, cross-dams and changing land cover. Model simulations revealed that delta progradation rates are more sensitive to variations in water discharge than variations in fluvial sediment supply. Unlike mere aggradation during RSLR, the delta front experienced aggradational progradation due to tides. As expected, the area of the simulated sub-aerial delta increases with increasing sediment discharge, but decreases with increasing water discharge. But, human modifications are important. For example, the sub-aerial delta shrinks with increasing RSLR, but it does not when the sub-aerial delta is polderised, provided the polders are restricted from erosion. However, the polders are vulnerable to flooding as they lose relative elevation and can make the delta building process unsustainable. Cross-dams built to steer zones of land accretion within the delta accomplish their local goal, but may not result in net land gain at the scale of the delta. Applying these

A simulation model of a coordinated decentralized linear supply chain

NARCIS (Netherlands)

Ashayeri, Jalal; Cannella, S.; Lopez Campos, M.; Miranda, P.A.

2015-01-01

This paper presents a simulation-based study of a coordinated, decentralized linear supply chain (SC) system. In the proposed model, any supply tier considers its successors as part of its inventory system and generates replenishment orders on the basis of its partners’ operational information. We

Simulation and linear stability of traffic jams; Kotsu jutai no senkei anteisei to simulation

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, M. [Shizuoka University, Shizuoka (Japan); Nagatani, T. [Shizuoka University, Shizuoka (Japan). Faculty of Engineering

1999-05-25

A traffic jam induced by slowing down is investigated using simulation techniques of molecular dynamics. When cars are decelerated by the presence of hindrance, two typical traffic jams occur behind the hindrance: one is an oscillating jam and the other is a homogeneous jam. When the slowing down is small, the oscillating jam occurs. If the slowing down is large, the jam is homogeneous over space and time. Also, a backward propagating soliton-like jam is observed. The linear stability theory is applied to the traffic flow. The phase boundary between the oscillating and homogeneous jams is compared with the neutral stability line obtained by the linear stability theory. (author)

Study of no-man's land physics in the total-f gyrokinetic code XGC1

Science.gov (United States)

Ku, Seung Hoe; Chang, C. S.; Lang, J.

2014-10-01

While the ``transport shortfall'' in the ``no-man's land'' has been observed often in delta-f codes, it has not yet been observed in the global total-f gyrokinetic particle code XGC1. Since understanding the interaction between the edge and core transport appears to be a critical element in the prediction for ITER performance, understanding the no-man's land issue is an important physics research topic. Simulation results using the Holland case will be presented and the physics causing the shortfall phenomenon will be discussed. Nonlinear nonlocal interaction of turbulence, secondary flows, and transport appears to be the key.

Spring-Summer Temperatures Since AD 1780 Reconstructed from Stable Oxygen Isotope Ratios in White Spruce Tree-Rings from the Mackenzie Delta, Northwestern Canada

Science.gov (United States)

Porter, Trevor J.; Pisaric, Michael F. J.; Field, Robert D.; Kokelj, Steven V.; Edwards, Thomas W. D.; deMontigny, Peter; Healy, Richard; LeGrande, Allegra N.

2013-01-01

High-latitude delta(exp 18)O archives deriving from meteoric water (e.g., tree-rings and ice-cores) can provide valuable information on past temperature variability, but stationarity of temperature signals in these archives depends on the stability of moisture source/trajectory and precipitation seasonality, both of which can be affected by atmospheric circulation changes. A tree-ring delta(exp 18)O record (AD 1780-2003) from the Mackenzie Delta is evaluated as a temperature proxy based on linear regression diagnostics. The primary source of moisture for this region is the North Pacific and, thus, North Pacific atmospheric circulation variability could potentially affect the tree-ring delta(exp 18)O-temperature signal. Over the instrumental period (AD 1892-2003), tree-ring delta(exp 18)O explained 29% of interannual variability in April-July minimum temperatures, and the explained variability increases substantially at lower-frequencies. A split-period calibration/verification analysis found the delta(exp 18)O-temperature relation was time-stable, which supported a temperature reconstruction back to AD 1780. The stability of the delta(exp 18)O-temperature signal indirectly implies the study region is insensitive to North Pacific circulation effects, since North Pacific circulation was not constant over the calibration period. Simulations from the NASA-GISS ModelE isotope-enabled general circulation model confirm that meteoric delta(exp 18)O and precipitation seasonality in the study region are likely insensitive to North Pacific circulation effects, highlighting the paleoclimatic value of tree-ring and possibly other delta(exp 18)O records from this region. Our delta(exp 18)O-based temperature reconstruction is the first of its kind in northwestern North America, and one of few worldwide, and provides a long-term context for evaluating recent climate warming in the Mackenzie Delta region.

Investigating Particle Transport and Fate in the Sacramento–San Joaquin Delta Using a Particle-Tracking Model

Directory of Open Access Journals (Sweden)

Wim J. Kimmerer

2008-02-01

Full Text Available Movements of pelagic organisms in the tidal freshwater regions of estuaries are sensitive to the movements of water. In the Sacramento-San Joaquin Delta—the tidal freshwater reach of the San Francisco Estuary—such movements are key to losses of fish and other organisms to entrainment in large water-export facilities. We used the Delta Simulation Model-2 hydrodynamic model and its particle tracking model to examine the principal determinants of entrainment losses to the export facilities and how movement of fish through the Delta may be influenced by flow. We modeled 936 scenarios for 74 different conditions of flow, diversions, tides, and removable barriers to address seven questions regarding hydrodynamics and entrainment risk in the Delta. Tide had relatively small effects on fate and residence time of particles. Release location and hydrology interacted to control particle fate and residence time. The ratio of flow into the export facilities to freshwater flow into the Delta (export:inflow or EI ratio was a useful predictor of entrainment probability if the model were allowed to run long enough to resolve particles’ ultimate fate. Agricultural diversions within the Delta increased total entrainment losses and altered local movement patterns. Removable barriers in channels of the southern Delta and gates in the Delta Cross Channel in the northern Delta had minor effects on particles released in the rivers above these channels. A simulation of losses of larval delta smelt showed substantial cumulative losses depending on both inflow and export flow. A simulation mimicking mark–recapture experiments on Chinook salmon smolts suggested that both inflow and export flow may be important factors determining survival of salmon in the upper estuary. To the extent that fish behave passively, this model is probably suitable for describing Delta-wide movement, but it is less suitable for smaller scales or alternative configurations of the Delta.

Systematic study of doping dependence on linear magnetoresistance in p-PbTe

International Nuclear Information System (INIS)

Schneider, J. M.; Chitta, V. A.; Oliveira, N. F.; Peres, M. L.; Castro, S. de; Soares, D. A. W.; Wiedmann, S.; Zeitler, U.; Abramof, E.; Rappl, P. H. O.; Mengui, U. A.

2014-01-01

We report on a large linear magnetoresistance effect observed in doped p-PbTe films. While undoped p-PbTe reveals a sublinear magnetoresistance, p-PbTe films doped with BaF 2 exhibit a transition to a nearly perfect linear magnetoresistance behaviour that is persistent up to 30 T. The linear magnetoresistance slope ΔR/ΔB is to a good approximation, independent of temperature. This is in agreement with the theory of Quantum Linear Magnetoresistance. We also performed magnetoresistance simulations using a classical model of linear magnetoresistance. We found that this model fails to explain the experimental data. A systematic study of the doping dependence reveals that the linear magnetoresistance response has a maximum for small BaF 2 doping levels and diminishes rapidly for increasing doping levels. Exploiting the huge impact of doping on the linear magnetoresistance signal could lead to new classes of devices with giant magnetoresistance behavior.

Parallel linear solvers for simulations of reactor thermal hydraulics

International Nuclear Information System (INIS)

Yan, Y.; Antal, S.P.; Edge, B.; Keyes, D.E.; Shaver, D.; Bolotnov, I.A.; Podowski, M.Z.

2011-01-01

The state-of-the-art multiphase fluid dynamics code, NPHASE-CMFD, performs multiphase flow simulations in complex domains using implicit nonlinear treatment of the governing equations and in parallel, which is a very challenging environment for the linear solver. The present work illustrates how the Portable, Extensible Toolkit for Scientific Computation (PETSc) and scalable Algebraic Multigrid (AMG) preconditioner from Hypre can be utilized to construct robust and scalable linear solvers for the Newton correction equation obtained from the discretized system of governing conservation equations in NPHASE-CMFD. The overall long-tem objective of this work is to extend the NPHASE-CMFD code into a fully-scalable solver of multiphase flow and heat transfer problems, applicable to both steady-state and stiff time-dependent phenomena in complete fuel assemblies of nuclear reactors and, eventually, the entire reactor core (such as the Virtual Reactor concept envisioned by CASL). This campaign appropriately begins with the linear algebraic equation solver, which is traditionally a bottleneck to scalability in PDE-based codes. The computational complexity of the solver is usually superlinear in problem size, whereas the rest of the code, the “physics” portion, usually has its complexity linear in the problem size. (author)

Molecular Dynamics and Metadynamics Simulations of the Cellulase Cel48F

Directory of Open Access Journals (Sweden)

Osmair Vital de Oliveira

2014-01-01

Full Text Available Molecular dynamics (MD and metadynamics techniques were used to study the cellulase Cel48F-sugar. Cellulase is enzyme that breaks cellulose fibers into small sugar units and is potentially useful in second generation alcohol production. In MD simulations, the overall structure of equilibrated Cel48F did not significantly change along the trajectory, retaining root mean square deviation below 0.15 nm. A set of 15 residues interacting with the sugar chains via hydrogen bonding throughout the simulation was observed. The free energy of dissociation (ΔGdiss. of the chains in the catalytic tunnel of Cel48F was determined by metadynamics. The ΔGdiss. values of the chains entering and leaving the wild-type Cel48F cavity were 13.9 and 62.1 kcal/mol, respectively. We also mutated the E542 and Q543 to alanine residue and obtained ΔGdiss. of 41.8 and 45.9 kcal/mol, respectively. These mutations were found to facilitate smooth dissociation of the sugar chain across the Cel48F tunnel. At the entry of the Cel48F tunnel, three residues were mutated to alanine: T110, T213, and L274. Contrary to the T110A-Cel48F, the mutants T213-Cel48F and L274-Cel48F prevented the sugar chain from passing across the leaving site. The present results can be a guideline in mutagenesis studies to improve processing by Cel48F.

Sigma-Delta Voltage to Frequency Converter With Phase Modulation Possibility

OpenAIRE

STORK, Milan

2014-01-01

Voltage to frequency converter (VFC) is an oscillator whose frequency is linearly proportional to control voltage. There are two common VFC architectures: the current steering multivibrator and the charge-balance VFC. For higher linearity, the charge-balancing method is preferred. The charge balanced VFC may be made in asynchronous or synchronous (clocked) forms. The synchronous charge balanced VFC or "sigma delta" (S-D) VFC is used when output pulses are synchroni...

Influence of different organic fertilizers on quality parameters and the delta(15)N, delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of orange fruit (Citrus sinensis L. Osbeck).

Science.gov (United States)

Rapisarda, Paolo; Camin, Federica; Fabroni, Simona; Perini, Matteo; Torrisi, Biagio; Intrigliolo, Francesco

2010-03-24

To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the delta(15)N, delta(13)C, delta(2)H, delta (34)S, and delta(18)O values of citrus fruit, a study was performed on the orange fruit cv. 'Valencia late' (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The delta(15)N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, delta(15)N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic fertilizers are of different origins, the natural abundance of (15)N in organic citrus fruit remains higher than in conventional ones. These treatments also did not effect differences in the delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of fruit.

A Novel Sigma-Delta Modulator with Fractional-Order Digital Loop Integrator

Directory of Open Access Journals (Sweden)

Chi Xu

2017-01-01

Full Text Available This paper proposes using a fractional-order digital loop integrator to improve the robust stability of Sigma-Delta modulator, thus extending the integer-order Sigma-Delta modulator to a non-integer-order (fractional-order one in the Sigma-Delta ADC design field. The proposed fractional-order Sigma-Delta modulator has reasonable noise characteristics, dynamic range, and bandwidth; moreover the signal-to-noise ratio (SNR is improved remarkably. In particular, a 2nd-order digital loop integrator and a digital PIλDμ controller are combined to work as the fractional-order digital loop integrator, which is realized using FPGA; this will reduce the ASIC analog circuit layout design and chip testing difficulties. The parameters of the proposed fractional-order Sigma-Delta modulator are tuned by using swarm intelligent algorithm, which offers opportunity to simplify the process of tuning parameters and further improve the noise performance. Simulation results are given and they demonstrate the efficiency of the proposed fractional-order Sigma-Delta modulator.

Challenges, Approaches and Experiences from Asian Deltas and the Rhine-Meuse Delta : Regional Training Workshop on Delta Planning and Management

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2013-01-01

River delta's, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Ayeyarwady Delta (Myanmar), Nile (Egypt) and Ciliwung Delta (Indonesia) are developing rapidly and are characterised by large-scale urbanisation and industrialization processes. They are facing serious planning

Simulation of dynamics of a permanent magnet linear actuator

DEFF Research Database (Denmark)

Yatchev, Ivan; Ritchie, Ewen

2010-01-01

Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

Simulation study on single event burnout in linear doping buffer layer engineered power VDMOSFET

International Nuclear Information System (INIS)

Jia Yunpeng; Su Hongyuan; Hu Dongqing; Wu Yu; Jin Rui

2016-01-01

The addition of a buffer layer can improve the device's secondary breakdown voltage, thus, improving the single event burnout (SEB) threshold voltage. In this paper, an N type linear doping buffer layer is proposed. According to quasi-stationary avalanche simulation and heavy ion beam simulation, the results show that an optimized linear doping buffer layer is critical. As SEB is induced by heavy ions impacting, the electric field of an optimized linear doping buffer device is much lower than that with an optimized constant doping buffer layer at a given buffer layer thickness and the same biasing voltages. Secondary breakdown voltage and the parasitic bipolar turn-on current are much higher than those with the optimized constant doping buffer layer. So the linear buffer layer is more advantageous to improving the device's SEB performance. (paper)

The use of molecular sieves to simulate hot lesions in (18)F-fluorodeoxyglucose--positron emission tomography imaging.

Science.gov (United States)

Matheoud, R; Secco, C; Ridone, S; Inglese, E; Brambilla, M

2008-04-21

We investigated the use of a kind of zeolite, the Bowie chabazite, to produce radioactive sources of different shapes, dimensions and activity concentrations that can be used for lesion simulation in positron emission tomography (PET) imaging. The (18)F-fluorodeoxyglucose ((18)F-FDG) uptake of a group of 12 zeolites was studied as a function of their weight (120-1,520 mg) and of the activity concentration of the (18)F-FDG solution (1-37 MBq ml(-1)), using a multiple linear regression model. The reproducibility, homogeneity and stability over time of the (18)F-FDG uptake were assessed. The fit of the regression model is good (r(2) = 0.83). This relation allows the production of zeolites of a desired (18)F-FDG activity using knowledge of the concentration of the soaking solution and the weight of the zeolite. The reproducibility of the (18)F-FDG uptake after heating the zeolites is elevated (CV% = 3.68). The almost complete regeneration of the zeolites allows us to reuse them in successive experiments. The stability of the (18)F-FDG uptake on zeolites is far from ideal. When placed in a saline solution the 'activated' zeolites release the (18)F-FDG with an effective half-time of 53 min. The sealing of the zeolites in plastic film bags has been demonstrated to be effective in preventing any release of (18)F-FDG. These features, together with their variable dimensions and shapes, make them ideal (18)F-FDG sources with a fixed target-to-background ratio that can be placed anywhere in a phantom to study lesion detectability in PET imaging.

The use of molecular sieves to simulate hot lesions in 18F-fluorodeoxyglucose-positron emission tomography imaging

International Nuclear Information System (INIS)

Matheoud, R; Secco, C; Brambilla, M; Ridone, S; Inglese, E

2008-01-01

We investigated the use of a kind of zeolite, the Bowie chabazite, to produce radioactive sources of different shapes, dimensions and activity concentrations that can be used for lesion simulation in positron emission tomography (PET) imaging. The 18 F-fluorodeoxyglucose ( 18 F-FDG) uptake of a group of 12 zeolites was studied as a function of their weight (120-1520 mg) and of the activity concentration of the 18 F-FDG solution (1-37 MBq ml -1 ), using a multiple linear regression model. The reproducibility, homogeneity and stability over time of the 18 F-FDG uptake were assessed. The fit of the regression model is good (r 2 = 0.83). This relation allows the production of zeolites of a desired 18 F-FDG activity using knowledge of the concentration of the soaking solution and the weight of the zeolite. The reproducibility of the 18 F-FDG uptake after heating the zeolites is elevated (CV% = 3.68). The almost complete regeneration of the zeolites allows us to reuse them in successive experiments. The stability of the 18 F-FDG uptake on zeolites is far from ideal. When placed in a saline solution the 'activated' zeolites release the 18 F-FDG with an effective half-time of 53 min. The sealing of the zeolites in plastic film bags has been demonstrated to be effective in preventing any release of 18 F-FDG. These features, together with their variable dimensions and shapes, make them ideal 18 F-FDG sources with a fixed target-to-background ratio that can be placed anywhere in a phantom to study lesion detectability in PET imaging. (note)

Delta Plaza kohvik = Delta Plaza cafe

Index Scriptorium Estoniae

2010-01-01

Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

Linear Power-Flow Models in Multiphase Distribution Networks: Preprint

Energy Technology Data Exchange (ETDEWEB)

Bernstein, Andrey; Dall' Anese, Emiliano

2017-05-26

This paper considers multiphase unbalanced distribution systems and develops approximate power-flow models where bus-voltages, line-currents, and powers at the point of common coupling are linearly related to the nodal net power injections. The linearization approach is grounded on a fixed-point interpretation of the AC power-flow equations, and it is applicable to distribution systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. The proposed linear models can facilitate the development of computationally-affordable optimization and control applications -- from advanced distribution management systems settings to online and distributed optimization routines. Performance of the proposed models is evaluated on different test feeders.

Investigation of vortex breakdown on delta wings using Navier-Stokes equations

Science.gov (United States)

Hsu, C.-H.; Liu, C. H.

1992-01-01

An efficient finite-difference scheme solving for the three-dimensional incompressible Navier-Stokes equations is described. Numerical simulations of vortex breakdown are then carried out for a sharp-edged delta wing and a round-edged double-delta wing at high Reynolds numbers. Computed results show that several major features of vortex breakdown are qualitatively in agreement with observations made in experiments.

Beam dynamics simulation of a double pass proton linear accelerator

Directory of Open Access Journals (Sweden)

Kilean Hwang

2017-04-01

Full Text Available A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed [J. Qiang, Nucl. Instrum. Methods Phys. Res., Sect. A 795, 77 (2015NIMAER0168-900210.1016/j.nima.2015.05.056] and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fully 3D space-charge effects through the entire accelerator system.

SU-D-BRF-06: A Brachytherapy Simulator with Realistic Haptic Force Feedback and Real-Time Ultrasounds Image Simulation for Training and Teaching

International Nuclear Information System (INIS)

Beaulieu, L; Carette, A; Comtois, S; Lavigueur, M; Cardou, P; Laurendeau, D

2014-01-01

Purpose: Surgical procedures require dexterity, expertise and repetition to reach optimal patient outcomes. However, efficient training opportunities are usually limited. This work presents a simulator system with realistic haptic force-feedback and full, real-time ultrasounds image simulation. Methods: The simulator is composed of a custom-made Linear-DELTA force-feedback robotic platform. The needle tip is mounted on a force gauge at the end effector of the robot, which responds to needle insertion by providing reaction forces. 3D geometry of the tissue is using a tetrahedral finite element mesh (FEM) mimicking tissue properties. As the needle is inserted/retracted, tissue deformation is computed using a mass-tensor nonlinear visco-elastic FEM. The real-time deformation is fed to the L-DELTA to take into account the force imparted to the needle, providing feedback to the end-user when crossing tissue boundaries or needle bending. Real-time 2D US image is also generated synchronously showing anatomy, needle insertion and tissue deformation. The simulator is running on an Intel I7 6- core CPU at 3.26 MHz. 3D tissue rendering and ultrasound display are performed on a Windows 7 computer; the FEM computation and L-DELTA control are executed on a similar PC using the Neutrino real-time OS. Both machines communicate through an Ethernet link. Results: The system runs at 500 Hz for a 8333-tetrahedron tissue mesh and a 100-node angular spring needle model. This frame rate ensures a relatively smooth displacement of the needle when pushed or retracted (±20 N in all directions at speeds of up to 2 m/s). Unlike commercially-available haptic platforms, the oblong workspace of the L-DELTA robot complies with that required for brachytherapy needle displacements of 0.1m by 0.1m by 0.25m. Conclusion: We have demonstrated a real-life, realistic brachytherapy simulator developed for prostate implants (LDR/HDR). The platform could be adapted to other sites or training for other

Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

Energy Technology Data Exchange (ETDEWEB)

Zhang, H.Y., E-mail: haiyanzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, S.H., E-mail: shzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Cheng, M. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Z.X. [Beijing Institute of Aeronautica1 Materials, Beijing 100095 (China)

2010-01-15

The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

Energy Technology Data Exchange (ETDEWEB)

Theodorakis, P E [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Avgeropoulos, A [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Senda del Rey 9, 28040 Madrid (Spain); Kosmas, M [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Vlahos, C [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

2007-11-21

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

Science.gov (United States)

Theodorakis, P. E.; Avgeropoulos, A.; Freire, J. J.; Kosmas, M.; Vlahos, C.

2007-11-01

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

International Nuclear Information System (INIS)

Theodorakis, P E; Avgeropoulos, A; Freire, J J; Kosmas, M; Vlahos, C

2007-01-01

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results

δf simulation of ion neoclassical transport

International Nuclear Information System (INIS)

Wang, W.; Nakajima, N.; Okamoto, M.; Murakami, S.

1999-07-01

Ion neoclassical transport with finite orbit width dynamics is calculated over whole poloidal cross section by using accurate δf method which employs an improved like-particle collision operator and an accurate weighting scheme to solve drift kinetic equation. Ion thermal transport near magnetic axis shows a great reduction from its conventional neoclassical level due to non-standard orbit topology, like that of previous δf simulation. On other hand, the direct particle loss from confinement region may strongly increase ion energy transport near the edge. It is found that ion parallel flow near the axis is also largely reduced due to non-standard orbit topology. In the presence of steep density gradient, ion thermal conductivity is significantly reduced, and an ion particle flux is driven by self-collision alone. (author)

Joint EEG/fMRI state space model for the detection of directed interactions in human brains—a simulation study

International Nuclear Information System (INIS)

Lenz, Michael; Linke, Yannick; Timmer, Jens; Schelter, Björn; Musso, Mariachristina; Weiller, Cornelius; Tüscher, Oliver

2011-01-01

An often addressed challenge in neuroscience research is the assignment of different tasks to specific brain regions. In many cases several brain regions are activated during a single task. Therefore, one is also interested in the temporal evolution of brain activity to infer causal relations between activated brain regions. These causal relations may be described by a directed, task specific network which consists of activated brain regions as vertices and directed edges. The edges describe the causal relations. Inference of the task specific brain network from measurements like electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) is challenging, due to the low spatial resolution of the former and the low temporal resolution of the latter. Here, we present a simulation study investigating a possible combined analysis of simultaneously measured EEG and fMRI data to address the challenge specified above. A nonlinear state space model is used to distinguish between the underlying brain states and the (simulated) EEG/fMRI measurements. We make use of a modified unscented Kalman filter and a corresponding unscented smoother for the estimation of the underlying neural activity. Model parameters are estimated using an expectation-maximization algorithm, which exploits the partial linearity of our model. Inference of the brain network structure is then achieved using directed partial correlation, a measure for Granger causality. The results indicate that the convolution effect of the fMRI forward model imposes a big challenge for the parameter estimation and reduces the influence of the fMRI in combined EEG–fMRI models. It remains to be investigated whether other models or similar combinations of other modalities such as, e.g., EEG and magnetoencephalography can increase the profit of the promising idea of combining various modalities

CFD simulations of steady flows over the IAR 65o delta wing

International Nuclear Information System (INIS)

Benmeddour, A.; Mebarki, Y.; Huang, X.Z.

2004-01-01

Computational Fluid Dynamics (CFD) studies have been conducted to simulate vortical flows around the IAR 65 o delta wing with a sharp leading edge. The effects of the centerbody on the aerodynamic characteristics of the wing are also investigated. Two flow solvers have been employed to compute steady inviscid flows over with and without centerbody configurations of the wing. These two solvers are an IAR in-house code, FJ3SOLV, and the CFD-FASTRAN commercial software. The computed flow solutions of the two solvers have been compared and correlated against the IAR wind tunnel data, including Pressure Sensitive Paint (PSP) measurements. The major features of the primary vortex have been well captured and overall reasonable accuracy was obtained. In accordance with the experimental observations for the flow conditions considered, the CFD computations revealed no major global effects of the centerbody on the surface pressure distributions of the wing and on the lift coefficient. However, CFD-FASTRAN seems to predict a vortex breakdown, which is neither predicted by FJ3SOLV nor observed in the wind tunnel for the flow conditions considered. (author)

Delta antibody radioimmunoassay

Energy Technology Data Exchange (ETDEWEB)

Kselikova, M; Urbankova, J

1985-11-15

The principle and procedure are described of the radioimmunoassay of delta antibody (delta-Ab) using the ABBOTT ANTI-DELTA kit by Abbott Co. A description is given of the kit, the working procedure and the method of evaluation. The results are reported of the incidence of delta-Ab in sera of patients with viral hepatitis B, in haemophiliacs, carriers of the hepatitis B virus surface antigen (HBsAg) and blood donors. The presence was detected of delta-Ab in one HBsAg carrier. The necessity is emphasized of delta-Ab determinations in the blood of donors in view of the antibody transfer with blood and blood preparations.

Simulations of linear and Hamming codes using SageMath

Science.gov (United States)

Timur, Tahta D.; Adzkiya, Dieky; Soleha

2018-03-01

Digital data transmission over a noisy channel could distort the message being transmitted. The goal of coding theory is to ensure data integrity, that is, to find out if and where this noise has distorted the message and what the original message was. Data transmission consists of three stages: encoding, transmission, and decoding. Linear and Hamming codes are codes that we discussed in this work, where encoding algorithms are parity check and generator matrix, and decoding algorithms are nearest neighbor and syndrome. We aim to show that we can simulate these processes using SageMath software, which has built-in class of coding theory in general and linear codes in particular. First we consider the message as a binary vector of size k. This message then will be encoded to a vector with size n using given algorithms. And then a noisy channel with particular value of error probability will be created where the transmission will took place. The last task would be decoding, which will correct and revert the received message back to the original message whenever possible, that is, if the number of error occurred is smaller or equal to the correcting radius of the code. In this paper we will use two types of data for simulations, namely vector and text data.

The sensitivity of the ESA DELTA model

Science.gov (United States)

Martin, C.; Walker, R.; Klinkrad, H.

Long-term debris environment models play a vital role in furthering our understanding of the future debris environment, and in aiding the determination of a strategy to preserve the Earth orbital environment for future use. By their very nature these models have to make certain assumptions to enable informative future projections to be made. Examples of these assumptions include the projection of future traffic, including launch and explosion rates, and the methodology used to simulate break-up events. To ensure a sound basis for future projections, and consequently for assessing the effectiveness of various mitigation measures, it is essential that the sensitivity of these models to variations in key assumptions is examined. The DELTA (Debris Environment Long Term Analysis) model, developed by QinetiQ for the European Space Agency, allows the future projection of the debris environment throughout Earth orbit. Extensive analyses with this model have been performed under the auspices of the ESA Space Debris Mitigation Handbook and following the recent upgrade of the model to DELTA 3.0. This paper draws on these analyses to present the sensitivity of the DELTA model to changes in key model parameters and assumptions. Specifically the paper will address the variation in future traffic rates, including the deployment of satellite constellations, and the variation in the break-up model and criteria used to simulate future explosion and collision events.

A novel mouse PKC{delta} splice variant, PKC{delta}IX, inhibits etoposide-induced apoptosis

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung D. [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Seo, Kwang W. [Department of Internal Medicines, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Lee, Eun A.; Quang, Nguyen N. [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Cho, Hong R. [Department of Surgery, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Biomedical Research Center, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Kwon, Byungsuk, E-mail: bskwon@mail.ulsan.as.kr [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Biomedical Research Center, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of)

2011-07-01

Highlights: {yields} A novel PKC{delta} isoform, named PKC{delta}IX, that lacks the C1 domain and the ATP-binding site is ubiquitously expressed. {yields} PKC{delta}IX inhibits etoposide-induced apoptosis. {yields} PKC{delta}IX may function as an endogenous dominant negative isoform for PKC{delta}. -- Abstract: Protein kinase C (PKC) {delta} plays an important role in cellular proliferation and apoptosis. The catalytic fragment of PKC{delta} generated by caspase-dependent cleavage is essential for the initiation of etoposide-induced apoptosis. In this study, we identified a novel mouse PKC{delta} isoform named PKC{delta}IX (Genebank Accession No. (HQ840432)). PKC{delta}IX is generated by alternative splicing and is ubiquitously expressed, as seen in its full-length PKC{delta}. PKC{delta}IX lacks the C1 domain, the caspase 3 cleavage site, and the ATP binding site but preserves an almost intact c-terminal catalytic domain and a nuclear localization signal (NLS). The structural characteristics of PKC{delta}IX provided a possibility that this PKC{delta} isozyme functions as a novel dominant-negative form for PKC{delta} due to its lack of the ATP-binding domain that is required for the kinase activity of PKC{delta}. Indeed, overexpression of PKC{delta}IX significantly inhibited etoposide-induced apoptosis in NIH3T3 cells. In addition, an in vitro kinase assay showed that recombinant PKC{delta}IX protein could competitively inhibit the kinase activity of PKC{delta}. We conclude that PKC{delta}IX can function as a natural dominant-negative inhibitor of PKC{delta}in vivo.

Non-linear punctual kinetics applied to PWR reactors simulation

International Nuclear Information System (INIS)

Cysne, F.S.

1978-11-01

In order to study some kinds of nuclear reactor accidents, a simulation is made using the punctual kinetics model for the reactor core. The following integration methods are used: Hansen's method in which a linearization is made and CSMP using a variable interval fourth-order Runge Kutta method. The results were good and were compared with those obtained by the code Dinamica I which uses a finite difference integration method of backward kind. (Author) [pt

Development of a mechanical maintenance training simulator in OpenSimulator for F-16 aircraft engines

OpenAIRE

Pinheiro, André; Fernandes, Paulo; Maia, Ana; Cruz, Gonçalo; Pedrosa, Daniela; Fonseca, Benjamim; Paredes, Hugo; Martins, Paulo; Morgado, Leonel; Rafael, Jorge

2014-01-01

Mechanical maintenance of F-16 engines is carried out as a team effort involving 3–4 skilled engine technicians, but the details of its procedures and requisites change constantly, to improve safety, optimize resources, and respond to knowledge learned from field outcomes. This provides a challenge for development of training simulators, since simulated actions risk becoming obsolete rapidly and require costly reimplementation. This paper presents the development of a 3D mechanical maintenanc...

Direct Numerical Simulations of High-Speed Turbulent Boundary Layers over Riblets

Science.gov (United States)

Duan, Lian; Choudhari, Meelan, M.

2014-01-01

Direct numerical simulations (DNS) of spatially developing turbulent boundary layers over riblets with a broad range of riblet spacings are conducted to investigate the effects of riblets on skin friction at high speeds. Zero-pressure gradient boundary layers under two flow conditions (Mach 2:5 with T(sub w)/T(sub r) = 1 and Mach 7:2 with T(sub w)/T(sub r) = 0:5) are considered. The DNS results show that the drag-reduction curve (delta C(sub f)/C(sub f) vs l(sup +)(sub g )) at both supersonic speeds follows the trend of low-speed data and consists of a `viscous' regime for small riblet size, a `breakdown' regime with optimal drag reduction, and a `drag-increasing' regime for larger riblet sizes. At l l(sup +)(sub g) approx. 10 (corresponding to s+ approx 20 for the current triangular riblets), drag reduction of approximately 7% is achieved at both Mach numbers, and con rms the observations of the few existing experiments under supersonic conditions. The Mach- number dependence of the drag-reduction curve occurs for riblet sizes that are larger than the optimal size, with smaller slopes of (delta C(sub f)/C(sub f) for larger freestream Mach numbers. The Reynolds analogy holds with 2(C(sub h)=C(sub f) approximately equal to that of at plates for both drag-reducing and drag-increasing configurations.

Delta Dynamics

DEFF Research Database (Denmark)

Bendixen, Mette

. The warming air temperature affects the soil temperature and permafrost thaws and destabilizes the material in the coastal zone. In Greenland, the warming temperature lowers the surface mass balance of the Greenland Ice Sheet and more material is transported to the coastal zone. The sea ice extent is thinning...... of a fjord and the second type is a wider fan-shaped open delta. Most deltas are directly coupled to the Greenland Ice Sheet or local icecaps and are highly influenced by the dynamics in the catchments. It is demonstrated how a modern changing climate directly affects delta dynamics, and that Greenlandic...... deltas are prograding, contrary to the global trend showing eroding Arctic coasts. Moreover, it is revealed that the increasing proglacial freshwater runoff, caused by a lowering of the surface mass balance of the Greenland Ice Sheet is the main determining agent in delta progradation. The final part...

Erosion characteristics and horizontal variability for small erosion depths in the Sacramento-San Joaquin River Delta, California, USA

Science.gov (United States)

Schoellhamer, David H.; Manning, Andrew J.; Work, Paul A.

2017-01-01

Erodibility of cohesive sediment in the Sacramento-San Joaquin River Delta (Delta) was investigated with an erosion microcosm. Erosion depths in the Delta and in the microcosm were estimated to be about one floc diameter over a range of shear stresses and times comparable to half of a typical tidal cycle. Using the conventional assumption of horizontally homogeneous bed sediment, data from 27 of 34 microcosm experiments indicate that the erosion rate coefficient increased as eroded mass increased, contrary to theory. We believe that small erosion depths, erosion rate coefficient deviation from theory, and visual observation of horizontally varying biota and texture at the sediment surface indicate that erosion cannot solely be a function of depth but must also vary horizontally. We test this hypothesis by developing a simple numerical model that includes horizontal heterogeneity, use it to develop an artificial time series of suspended-sediment concentration (SSC) in an erosion microcosm, then analyze that time series assuming horizontal homogeneity. A shear vane was used to estimate that the horizontal standard deviation of critical shear stress was about 30% of the mean value at a site in the Delta. The numerical model of the erosion microcosm included a normal distribution of initial critical shear stress, a linear increase in critical shear stress with eroded mass, an exponential decrease of erosion rate coefficient with eroded mass, and a stepped increase in applied shear stress. The maximum SSC for each step increased gradually, thus confounding identification of a single well-defined critical shear stress as encountered with the empirical data. Analysis of the artificial SSC time series with the assumption of a homogeneous bed reproduced the original profile of critical shear stress, but the erosion rate coefficient increased with eroded mass, similar to the empirical data. Thus, the numerical experiment confirms the small-depth erosion hypothesis. A linear

Monte Carlo simulation of a clinical linear accelerator

International Nuclear Information System (INIS)

Lin, S.-Y.; Chu, T.-C.; Lin, J.-P.

2001-01-01

The effects of the physical parameters of an electron beam from a Siemens PRIMUS clinical linear accelerator (linac) on the dose distribution in water were investigated by Monte Carlo simulation. The EGS4 user code, OMEGA/BEAM, was used in this study. Various incident electron beams, for example, with different energies, spot sizes and distances from the point source, were simulated using the detailed linac head structure in the 6 MV photon mode. Approximately 10 million particles were collected in the scored plane, which was set under the reticle to form the so-called phase space file. The phase space file served as a source for simulating the dose distribution in water using DOSXYZ. Dose profiles at D max (1.5 cm) and PDD curves were calculated following simulating about 1 billion histories for dose profiles and 500 million histories for percent depth dose (PDD) curves in a 30x30x30 cm 3 water phantom. The simulation results were compared with the data measured by a CEA film and an ion chamber. The results show that the dose profiles are influenced by the energy and the spot size, while PDD curves are primarily influenced by the energy of the incident beam. The effect of the distance from the point source on the dose profile is not significant and is recommended to be set at infinity. We also recommend adjusting the beam energy by using PDD curves and, then, adjusting the spot size by using the dose profile to maintain the consistency of the Monte Carlo results and measured data

EEG-fMRI Bayesian framework for neural activity estimation: a simulation study

Science.gov (United States)

Croce, Pierpaolo; Basti, Alessio; Marzetti, Laura; Zappasodi, Filippo; Del Gratta, Cosimo

2016-12-01

Objective. Due to the complementary nature of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), and given the possibility of simultaneous acquisition, the joint data analysis can afford a better understanding of the underlying neural activity estimation. In this simulation study we want to show the benefit of the joint EEG-fMRI neural activity estimation in a Bayesian framework. Approach. We built a dynamic Bayesian framework in order to perform joint EEG-fMRI neural activity time course estimation. The neural activity is originated by a given brain area and detected by means of both measurement techniques. We have chosen a resting state neural activity situation to address the worst case in terms of the signal-to-noise ratio. To infer information by EEG and fMRI concurrently we used a tool belonging to the sequential Monte Carlo (SMC) methods: the particle filter (PF). Main results. First, despite a high computational cost, we showed the feasibility of such an approach. Second, we obtained an improvement in neural activity reconstruction when using both EEG and fMRI measurements. Significance. The proposed simulation shows the improvements in neural activity reconstruction with EEG-fMRI simultaneous data. The application of such an approach to real data allows a better comprehension of the neural dynamics.

BEAMPATH: a program library for beam dynamics simulation in linear accelerators

International Nuclear Information System (INIS)

Batygin, Y.K.

1992-01-01

A structured programming technique was used to develop software for space charge dominated beams investigation in linear accelerators. The method includes hierarchical program design using program independent modules and a flexible combination of modules to provide a most effective version of structure for every specific case of simulation. A modular program BEAMPATH was developed for 2D and 3D particle-in-cell simulation of beam dynamics in a structure containing RF gaps, radio-frequency quadrupoles (RFQ), multipole lenses, waveguides, bending magnets and solenoids. (author) 5 refs.; 2 figs

Elastic-constant systematics in f.c.c. metals, including lanthanides-actinides

Energy Technology Data Exchange (ETDEWEB)

Ledbetter, Hassel [Mechanical Engineering Department, University of Colorado, Boulder, Colorado 80309 (United States); Migliori, Albert [Los Alamos National Laboratory (E536), Los Alamos, New Mexico 87545 (United States)

2008-01-15

For f.c.c. metals, using Blackman's diagram of dimensionless elastic-constant ratios, we consider the systematics of physical properties and interatomic bonding. We focus especially on the lanthanides-actinides La, Ce, Yb, Th, U, Pu, those for which we know some monocrystal elastic constants. Their behavior differs from the other f.c.c. metals, and all except La show a negative Cauchy pressure, contrary to most f.c.c. metals, which show a positive Cauchy pressure. Among the lanthanides-actinides, {delta}-Pu stands apart, consistent with its many odd physical properties. Based on elastic-constant correlations, we suggest that {delta}-Pu possesses a strong s-electron interatomic-bonding component together with a covalent component. Elastically, {delta}-Pu shows properties similar to Yb. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Simulation study on single event burnout in linear doping buffer layer engineered power VDMOSFET

Science.gov (United States)

Yunpeng, Jia; Hongyuan, Su; Rui, Jin; Dongqing, Hu; Yu, Wu

2016-02-01

The addition of a buffer layer can improve the device's secondary breakdown voltage, thus, improving the single event burnout (SEB) threshold voltage. In this paper, an N type linear doping buffer layer is proposed. According to quasi-stationary avalanche simulation and heavy ion beam simulation, the results show that an optimized linear doping buffer layer is critical. As SEB is induced by heavy ions impacting, the electric field of an optimized linear doping buffer device is much lower than that with an optimized constant doping buffer layer at a given buffer layer thickness and the same biasing voltages. Secondary breakdown voltage and the parasitic bipolar turn-on current are much higher than those with the optimized constant doping buffer layer. So the linear buffer layer is more advantageous to improving the device's SEB performance. Project supported by the National Natural Science Foundation of China (No. 61176071), the Doctoral Fund of Ministry of Education of China (No. 20111103120016), and the Science and Technology Program of State Grid Corporation of China (No. SGRI-WD-71-13-006).

Anaerobic Transformation of Furfural by Methanococcus deltae (Delta)LH

Science.gov (United States)

Belay, N.; Boopathy, R.; Voskuilen, G.

1997-01-01

Methanococcus deltae (Delta)LH was grown on H(inf2)-CO(inf2) in the presence of various concentrations of furfural. Furfural at higher concentrations, namely, 20 and 25 mM, inhibited growth of this organism. At concentration of 5 and 10 mM, no inhibition of growth was observed. The other methanogens in this study were not inhibited by 10 mM furfural. Among the methanogens tested, M. deltae was capable of transforming furfural, whereas Methanobacterium thermoautotrophicum Marburg, Methanosarcina barkeri 227, Methanococcus thermolithotrophicus, and Methanobrevibacter ruminantium lacked this capability. One hundred percent removal of furfural was observed within 48 h of incubation in M. deltae cultures. The end product observed during furfural metabolism was furfuryl alcohol. An almost stoichiometric amount of furfuryl alcohol was produced by M. deltae. This transformation is likely to be of value in the detoxification of furfural and in its ultimate conversion to methane and CO(inf2) by anaerobic digestion. PMID:16535618

Delta Power Control Strategy for Multi-String Grid-Connected PV Inverters

DEFF Research Database (Denmark)

Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

2016-01-01

With a still increasing penetration level of grid-connected PV systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required...... for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control for grid-connected PV systems is presented, where the residential/commercial multi-string PV inverter configuration is adopted. This control strategy is a combination of Maximum...... for the entire PV system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the delta power control strategy, where the power reserve according to the delta power constraint is achieved under several...

Monte Carlo simulation of medical linear accelerator using primo code

International Nuclear Information System (INIS)

Omer, Mohamed Osman Mohamed Elhasan

2014-12-01

The use of monte Carlo simulation has become very important in the medical field and especially in calculation in radiotherapy. Various Monte Carlo codes were developed simulating interactions of particles and photons with matter. One of these codes is PRIMO that performs simulation of radiation transport from the primary electron source of a linac to estimate the absorbed dose in a water phantom or computerized tomography (CT). PRIMO is based on Penelope Monte Carlo code. Measurements of 6 MV photon beam PDD and profile were done for Elekta precise linear accelerator at Radiation and Isotopes Center Khartoum using computerized Blue water phantom and CC13 Ionization Chamber. accept Software was used to control the phantom to measure and verify dose distribution. Elektalinac from the list of available linacs in PRIMO was tuned to model Elekta precise linear accelerator. Beam parameter of 6.0 MeV initial electron energy, 0.20 MeV FWHM, and 0.20 cm focal spot FWHM were used, and an error of 4% between calculated and measured curves was found. The buildup region Z max was 1.40 cm and homogenous profile in cross line and in line were acquired. A number of studies were done to verily the model usability one of them is the effect of the number of histories on accuracy of the simulation and the resulted profile for the same beam parameters. The effect was noticeable and inaccuracies in the profile were reduced by increasing the number of histories. Another study was the effect of Side-step errors on the calculated dose which was compared with the measured dose for the same setting.It was in range of 2% for 5 cm shift, but it was higher in the calculated dose because of the small difference between the tuned model and measured dose curves. Future developments include simulating asymmetrical fields, calculating the dose distribution in computerized tomographic (CT) volume, studying the effect of beam modifiers on beam profile for both electron and photon beams.(Author)

$\\gamma N \\to \\Delta$ transition form factors in Quenched and $N_F=2$ QCD

CERN Document Server

Alexandrou, C; Lippert, T; Neff, H; Negele, J W; Schilling, K; Schroers, W; Tsapalis, A; Forcrand, Ph. de; Lippert, Th.

2003-01-01

Calculations of the magnetic dipole, electric quadrupole and Coulomb quadrupole amplitudes for the transition $\\gamma N\\to \\Delta$ are presented both in quenched QCD and with two flavours of degenerate dynamical quarks.

delta-vision

Data.gov (United States)

California Natural Resource Agency — Delta Vision is intended to identify a strategy for managing the Sacramento-San Joaquin Delta as a sustainable ecosystem that would continue to support environmental...

Slab albedo for linearly and quadratically anisotropic scattering kernel with modified F{sub N} method

Energy Technology Data Exchange (ETDEWEB)

Tuereci, R. Goekhan [Kirikkale Univ. (Turkey). Kirikkale Vocational School; Tuereci, D. [Ministry of Education, Ankara (Turkey). 75th year Anatolia High School

2017-11-15

One speed, time independent and homogeneous medium neutron transport equation is solved with the anisotropic scattering which includes both the linearly and the quadratically anisotropic scattering kernel. Having written Case's eigenfunctions and the orthogonality relations among of these eigenfunctions, slab albedo problem is investigated as numerically by using Modified F{sub N} method. Selected numerical results are presented in tables.

Cyclic and seasonal features in the behaviour of linear growth increment of Rayleigh-Taylor instability in equatorial F-region

International Nuclear Information System (INIS)

Farkullin, M.N.; Nikitin, M.A.; Kashchenko, N.M.

1989-01-01

Calculations of linear increment of the Rayleigh-Taylor instability for various geophysical conditions are presented. It is shwn that space-time characteristics of increment depend strongly on conditions of solar activity and seasons. The calculation results are in a good agreement with statistical regularities of F-scattering observation in equatorial F-area, which points to the Rayleigh-Taylor natur of the penomena

Growth laws for delta crevasses in the Mississippi River Delta: observations and modeling

Science.gov (United States)

Yocum, T. A.; Georgiou, I. Y.

2016-02-01

River deltas are accumulations of sedimentary deposits delivered by rivers via a network of distributary channels. Worldwide they are threatened by environmental changes, including subsidence, global sea level rise and a suite of other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions, thereby reinitiating the delta cycle. While economically efficient, there are too few analogs of small deltas aside from laboratory studies, numerical modeling studies, theoretical approaches, and limited field driven observations. Anthropogenic crevasses in the modern delta are large enough to overcome limitations of laboratory deltas, and small enough to allow for "rapid" channel and wetland development, providing an ideal setting to investigate delta development mechanics. Crevasse metrics were obtained using a combination of geospatial tools, extracting key parameters (bifurcation length and width, channel order and depth) that were non-dimensionalized and compared to river-dominated delta networks previously studied. Analysis showed that most crevasses in the MRD appear to obey delta growth laws and delta allometry relationships, suggesting that crevasses do exhibit similar planform metrics to larger Deltas; the distance to mouth bar versus bifurcation order demonstrated to be a very reasonable first order estimate of delta-top footprint. However, some crevasses exhibited different growth metrics. To better understand the hydrodynamic and geomorphic controls governing crevasse evolution in the MRD, we assess delta dynamics via a suite of field observations and numerical modeling in both well-established and newly constructed crevasses. Our analysis suggests that delta development is affected by the relative influence of external (upstream and downstream) and internal controls on the hydrodynamic and sediment transport patterns in these systems.

Non-linear gyrokinetic simulations of microturbulence in TCV electron internal transport barriers

Science.gov (United States)

Lapillonne, X.; Brunner, S.; Sauter, O.; Villard, L.; Fable, E.; Görler, T.; Jenko, F.; Merz, F.

2011-05-01

Using the local (flux-tube) version of the Eulerian code GENE (Jenko et al 2000 Phys. Plasmas 7 1904), gyrokinetic simulations of microturbulence were carried out considering parameters relevant to electron-internal transport barriers (e-ITBs) in the TCV tokamak (Sauter et al 2005 Phys. Rev. Lett. 94 105002), generated under conditions of low or negative shear. For typical density and temperature gradients measured in such barriers, the corresponding simulated fluctuation spectra appears to simultaneously contain longer wavelength trapped electron modes (TEMs, for typically k⊥ρi 0.5). The contributions to the electron particle flux from these two types of modes are, respectively, outward/inward and may cancel each other for experimentally realistic gradients. This mechanism may partly explain the feasibility of e-ITBs. The non-linear simulation results confirm the predictions of a previously developed quasi-linear model (Fable et al 2010 Plasma Phys. Control. Fusion 52 015007), namely that the stationary condition of zero particle flux is obtained through the competitive contributions of ITG and TEM. A quantitative comparison of the electron heat flux with experimental estimates is presented as well.

A task-related and resting state realistic fMRI simulator for fMRI data validation

Science.gov (United States)

Hill, Jason E.; Liu, Xiangyu; Nutter, Brian; Mitra, Sunanda

2017-02-01

After more than 25 years of published functional magnetic resonance imaging (fMRI) studies, careful scrutiny reveals that most of the reported results lack fully decisive validation. The complex nature of fMRI data generation and acquisition results in unavoidable uncertainties in the true estimation and interpretation of both task-related activation maps and resting state functional connectivity networks, despite the use of various statistical data analysis methodologies. The goal of developing the proposed STANCE (Spontaneous and Task-related Activation of Neuronally Correlated Events) simulator is to generate realistic task-related and/or resting-state 4D blood oxygenation level dependent (BOLD) signals, given the experimental paradigm and scan protocol, by using digital phantoms of twenty normal brains available from BrainWeb (http://brainweb.bic.mni.mcgill.ca/brainweb/). The proposed simulator will include estimated system and modelled physiological noise as well as motion to serve as a reference to measured brain activities. In its current form, STANCE is a MATLAB toolbox with command line functions serving as an open-source add-on to SPM8 (http://www.fil.ion.ucl.ac.uk/spm/software/spm8/). The STANCE simulator has been designed in a modular framework so that the hemodynamic response (HR) and various noise models can be iteratively improved to include evolving knowledge about such models.

Faster Simulation Methods for the Nonstationary Random Vibrations of Non-linear MDOF Systems

DEFF Research Database (Denmark)

Askar, A.; Köylüo, U.; Nielsen, Søren R.K.

1996-01-01

subject to nonstationary Gaussian white noise excitation, as an alternative to conventional direct simulation methods. These alternative simulation procedures rely on an assumption of local Gaussianity during each time step. This assumption is tantamount to various linearizations of the equations....... Such a treatment offers higher rates of convergence, faster speed and higher accuracy. These procedures are compared to the direct Monte Carlo simulation procedure, which uses a fourth order Runge-Kutta scheme with the white noise process approximated by a broad band Ruiz-Penzien broken line process...

Fabrication of an integrated {Delta}E-E-silicon detector by wafer bonding using cobalt disilicide

Energy Technology Data Exchange (ETDEWEB)

Thungstroem, G. [Mid-Sweden Univ., Sundsvall (Sweden). Dept. of Inf. Technol.]|[Royal Institute of Technology, Department of Electronics, Electrum 229, S-164 40 Kista (Sweden); Veldhuizen, E.J. van [Uppsala University, Department of Radiation Science, Box 535, S-751 21 Uppsala (Sweden); Westerberg, L. [Uppsala University, The Svedberg Laboratory, Box 533, S-751 21 Uppsala (Sweden); Norlin, L.-O. [Royal Institute of Technology, Department of Physics, Frescativaegen 24, S-104 05 Stockholm (Sweden); Petersson, C.S. [Royal Institute of Technology, Department of Electronics, Electrum 229, S-164 40 Kista (Sweden)

1997-06-01

The problem concerning mechanical stability of thin self-supporting {Delta}E detector in a {Delta}E-E semiconductor detector telescope, has been solved by integrating both detectors into one unit. We show here a low-cost method to integrate the detectors by wafer bonding using cobalt disilicide. The {Delta}E-detector has a thickness of 6.5 {mu}m and the E detector 290 {mu}m with an area of 24.8 mm{sup 2}. The system was characterized with secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), electrical measurement, particle measurement and two-dimensional electrical simulation. (orig.).

COMMD1 regulates the delta epithelial sodium channel ({delta}ENaC) through trafficking and ubiquitination

Energy Technology Data Exchange (ETDEWEB)

Chang, Tina; Ke, Ying; Ly, Kevin [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand); McDonald, Fiona J., E-mail: fiona.mcdonald@otago.ac.nz [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand)

2011-08-05

Highlights: {yields} The COMM domain of COMMD1 mediates binding to {delta}ENaC. {yields} COMMD1 reduces the cell surface population of {delta}ENaC. {yields} COMMD1 increases the population of {delta}ENaC-ubiquitin. {yields} Both endogenous and transfected {delta}ENaC localize with COMMD1 and transferrin suggesting they are located in early/recycling endosomes. -- Abstract: The delta subunit of the epithelial sodium channel ({delta}ENaC) is a member of the ENaC/degenerin family of ion channels. {delta}ENaC is distinct from the related {alpha}-, {beta}- and {gamma}ENaC subunits, known for their role in sodium homeostasis and blood pressure control, as {delta}ENaC is expressed in brain neurons and activated by external protons. COMMD1 (copper metabolism Murr1 domain 1) was previously found to associate with and downregulate {delta}ENaC activity. Here, we show that COMMD1 interacts with {delta}ENaC through its COMM domain. Co-expression of {delta}ENaC with COMMD1 significantly reduced {delta}ENaC surface expression, and led to an increase in {delta}ENaC ubiquitination. Immunocytochemical and confocal microscopy studies show that COMMD1 promoted localization of {delta}ENaC to the early/recycling endosomal pool where the two proteins were localized together. These results suggest that COMMD1 downregulates {delta}ENaC activity by reducing {delta}ENaC surface expression through promoting internalization of surface {delta}ENaC to an intracellular recycling pool, possibly via enhanced ubiquitination.

LIAR -- A new program for the modeling and simulation of linear accelerators with high gradients and small emittances

International Nuclear Information System (INIS)

Assmann, R.; Adolphsen, C.; Bane, K.; Raubenheimer, T.O.; Siemann, R.; Thompson, K.

1996-09-01

Linear accelerators are the central components of the proposed next generation of linear colliders. They need to provide acceleration of up to 750 GeV per beam while maintaining very small normalized emittances. Standard simulation programs, mainly developed for storage rings, do not meet the specific requirements for high energy linear accelerators. The authors present a new program LIAR (LInear Accelerator Research code) that includes wakefield effects, a 4D coupled beam description, specific optimization algorithms and other advanced features. Its modular structure allows to use and to extend it easily for different purposes. They present examples of simulations for SLC and NLC

Some computer simulations based on the linear relative risk model

International Nuclear Information System (INIS)

Gilbert, E.S.

1991-10-01

This report presents the results of computer simulations designed to evaluate and compare the performance of the likelihood ratio statistic and the score statistic for making inferences about the linear relative risk mode. The work was motivated by data on workers exposed to low doses of radiation, and the report includes illustration of several procedures for obtaining confidence limits for the excess relative risk coefficient based on data from three studies of nuclear workers. The computer simulations indicate that with small sample sizes and highly skewed dose distributions, asymptotic approximations to the score statistic or to the likelihood ratio statistic may not be adequate. For testing the null hypothesis that the excess relative risk is equal to zero, the asymptotic approximation to the likelihood ratio statistic was adequate, but use of the asymptotic approximation to the score statistic rejected the null hypothesis too often. Frequently the likelihood was maximized at the lower constraint, and when this occurred, the asymptotic approximations for the likelihood ratio and score statistics did not perform well in obtaining upper confidence limits. The score statistic and likelihood ratio statistics were found to perform comparably in terms of power and width of the confidence limits. It is recommended that with modest sample sizes, confidence limits be obtained using computer simulations based on the score statistic. Although nuclear worker studies are emphasized in this report, its results are relevant for any study investigating linear dose-response functions with highly skewed exposure distributions. 22 refs., 14 tabs

Linear and non-linear simulation of joints contact surface using ...

African Journals Online (AJOL)

The joint modelling including non-linear effects needs accurate and precise study of their behaviors. When joints are under the dynamic loading, micro, macro- slip happens in contact surface which is non-linear reason of the joint contact surface. The non-linear effects of joint contact surface on total behavior of structure are ...

Impact of Simulated 1/f Noise for HI Intensity Mapping Experiments

Science.gov (United States)

Harper, S.; Dickinson, C.; Battye, R. A.; Roychowdhury, S.; Browne, I. W. A.; Ma, Y.-Z.; Olivari, L. C.; Chen, T.

2018-05-01

Cosmology has entered an era where the experimental limitations are not due to instrumental sensitivity but instead due to inherent systematic uncertainties in the instrumentation and data analysis methods. The field of HI intensity mapping (IM) is still maturing, however early attempts are already systematics limited. One such systematic limitation is 1/f noise, which largely originates within the instrumentation and manifests as multiplicative gain fluctuations. To date there has been little discussion about the possible impact of 1/f noise on upcoming single-dish HI IM experiments such as BINGO, FAST or SKA. Presented in this work are Monte-Carlo end-to-end simulations of a 30 day HI IM survey using the SKA-MID array covering a bandwidth of 950 and 1410 MHz. These simulations extend 1/f noise models to include not just temporal fluctuations but also correlated gain fluctuations across the receiver bandpass. The power spectral density of the spectral gain fluctuations are modelled as a power-law, and characterised by a parameter β. It is found that the degree of 1/f noise frequency correlation will be critical to the success of HI IM experiments. Small values of β (β HI IM survey with the SKA.

Electronic structure of Pu-Ce(-Ga) and Pu-Am(-Ga) alloys, stabilized in the {delta} phase; Structure electronique d'alliages Pu-Ce(-Ga) et Pu-Am(-Ga) stabilises en phase {delta}

Energy Technology Data Exchange (ETDEWEB)

Dormeval, M

2001-09-01

The behaviour of {delta}-plutonium, stable between 319 and 451 deg C, exhibits numerous singularities which are still a mystery for both physicists and metallurgists. This is due to its complex electronic structure, and in particular to the 5f electrons, which are at the edge between localization and delocalization. The stability domain of the {delta} phase can be extended down to room temperature by alloying with so called 'deltagen atoms' such as gallium (Ga), aluminum (A1), cerium (Ce) or americium (Am). The present work deals, one the one hand, with the influence of cerium and americium solutes regarding the localization of the 5f electrons of {delta}-plutonium, in binary Pu-Ce and Pu-Am alloys. On the other hand, the effect of two different deltagen solutes, simultaneously present, on the stability of the {delta} phase has been studied in ternary Pu-Am-Ga and Pu-Ce-Ga alloys. The electronic structure being strongly related to the crystalline organization, characterization methods such as X-Ray diffraction and EXAFS measurements were used together with electrical resistivity and magnetic susceptibility experiments. These showed that the roles of cerium and americium, supposed to be similar at the beginning of this investigation, are actually very different. Moreover, the additive effect of cerium and gallium, and, americium and gallium, has been demonstrated. Studying plutonium alloys, which are radioactive, also means following their evolution in time. The characteristics of the alloys have then been followed which allowed to detect, in Pu-Ce(-Ga) alloys, a destabilization of the {delta} phase and, to observe, in Pu-Am(-Ga) alloys, the influence of self-irradiation defects on the magnetic response. (author)

Future Deltas Utrecht University research focus area: towards sustainable management of sinking deltas

Science.gov (United States)

Stouthamer, E.; van Asselen, S.

2015-11-01

Deltas are increasingly under pressure from human impact and climate change. To deal with these pressures that threat future delta functioning, we need to understand interactions between physical, biological, chemical and social processes in deltas. This requires an integrated approach, in which knowledge on natural system functioning is combined with knowledge on spatial planning, land and water governance and legislative frameworks. In the research focus area Future Deltas of Utrecht University an interdisciplinary team from different research groups therefore works together. This allows developing integrated sustainable and resilient delta management strategies, which is urgently needed to prevent loss of vital delta services.

Kinematics and Application of a Hybrid Industrial Robot – Delta-RST

Directory of Open Access Journals (Sweden)

Ning Liu

2014-04-01

Full Text Available Serial robots and parallel robots have their own pros and cons. While hybrid robots consisting of both of them are possible and expected to retain their merits and minimize the disadvantages. The Delta-RST presented here is such a hybrid robot built up by integrating a 3-DoFs traditional Delta parallel structure and a 3-DoFs RST robotic wrist. In this paper, we focus on its kinematics analysis and its applications in industry. Firstly, the robotic system of the Delta-RST will be described briefly. Then the complete and systemic kinematics of this kind of robot will be presented in detail, followed by simulations and applications to demonstrate the correctness of the analysis, as well as the effectiveness of the developed robotic system. The closed-form kinematic analysis results are universal for similar hybrid robots constructing with the Delta parallel mechanism and serial chains.

Optimizing Within-Subject Experimental Designs for jICA of Multi-Channel ERP and fMRI

Science.gov (United States)

Mangalathu-Arumana, Jain; Liebenthal, Einat; Beardsley, Scott A.

2018-01-01

Joint independent component analysis (jICA) can be applied within subject for fusion of multi-channel event-related potentials (ERP) and functional magnetic resonance imaging (fMRI), to measure brain function at high spatiotemporal resolution (Mangalathu-Arumana et al., 2012). However, the impact of experimental design choices on jICA performance has not been systematically studied. Here, the sensitivity of jICA for recovering neural sources in individual data was evaluated as a function of imaging SNR, number of independent representations of the ERP/fMRI data, relationship between instantiations of the joint ERP/fMRI activity (linear, non-linear, uncoupled), and type of sources (varying parametrically and non-parametrically across representations of the data), using computer simulations. Neural sources were simulated with spatiotemporal and noise attributes derived from experimental data. The best performance, maximizing both cross-modal data fusion and the separation of brain sources, occurred with a moderate number of representations of the ERP/fMRI data (10–30), as in a mixed block/event related experimental design. Importantly, the type of relationship between instantiations of the ERP/fMRI activity, whether linear, non-linear or uncoupled, did not in itself impact jICA performance, and was accurately recovered in the common profiles (i.e., mixing coefficients). Thus, jICA provides an unbiased way to characterize the relationship between ERP and fMRI activity across brain regions, in individual data, rendering it potentially useful for characterizing pathological conditions in which neurovascular coupling is adversely affected. PMID:29410611

The short range effective interaction and the spectra of calcium isotopes in (f-p) space

International Nuclear Information System (INIS)

Qing-ying, Z.; Shen-wu, L.; Jian-xin, W.

1986-01-01

In this work, the authors use a new type of extremely short range interaction, the double delta interaction (DDI) to calculate the low-lying spectra of calcium isotopes /sup 41/Ca through /sup 48/Ca. The configuration space (f-p) includes configurations ( f/sub 7/2//sup n/ ) and ( f/sub 7/2//sup n-1/2p/sub 3/2/). The calculated energies are compared with experimental data for 75 levels. For comparison, they also use usual modified surface delta interaction (MSDI) to calculate the same spectra aforementioned. It is clear that the results calculated with DDI are better than with MSDI. Therefore, in the short-range effective interaction the addition of body delta force to the modified surface delta force may improve the agreement with experiment. The authors believe that the conclusion will not be changed if one enlarges the shell model space

Simulation of non-linear coaxial line using ferrite beads

International Nuclear Information System (INIS)

Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J.

2002-01-01

A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

Simulated reductions in consumption of sugar-sweetened beverages improves diet quality in Lower Mississippi Delta adults

Directory of Open Access Journals (Sweden)

Jessica L. Thomson

2011-10-01

Full Text Available Although the effects of replacing sugar-sweetened beverages (SSBs with water on energy intake and body weight have been reported, little is known about how these replacements affect diet quality.To simulate the effects of replacing SSBs with tap water on diet quality and total energy intake of Lower Mississippi Delta (LMD adults.Retrospective analysis of cross-sectional dietary intake data using a representative sample of LMD adults (n=1,689. Diet quality was measured using the Healthy Eating Index-2005 (HEI-2005 scores that were computed using the population ratio method. The effects of substituting SSBs with water on diet quality were simulated by replacing the targeted items’ nutrient profile with tap water's profile.Simulating the replacement of SSBs with tap water at 25, 50, and 100% levels resulted in 1-, 2.3-, and 3.8-point increases, respectively, in the HEI-2005 total score. Based on a mean daily intake of 2,011 kcal, 100% substitution of SSBs with tap water would result in 11% reduction in energy intake.Replacing SSBs with water could substantially improve the diet quality of the LMD adult population and potentially lead to significant weight loss overtime. Prioritizing intervention efforts to focus on the replacement of SSBs with energy-free drinks may be the most efficacious approach for conveying potentially substantial health benefits in this and similar disadvantaged populations.

Superionic conductors with the fluorite structure: a) Measurement of the ionic conductivity of SrF2 at high temperatures, b) Study of the thermodynamic properties at CaF2 by numerical simulation

International Nuclear Information System (INIS)

Evangelakis, Georges

1989-01-01

In this work we present the results of an experimental study concerning the superionic conductivity of SrF 2 and those obtained by an investigation of the thermodynamical properties of CaF 2 using molecular dynamics simulation in the superionic region. The conductivity measurements in SrF 2 have been performed at high temperatures (700-1350 K) and various frequencies (10 Hz-10 MHz). At each temperature a frequency dependence of the conductivity has been detected. The analysis of the results using complex impedance diagrams revealed that this dependence is not an intrinsic property of the material but is related to electrodes effects. The apparent activation energies associated to the different parts of the intrinsic and extrinsic conductivity regions have been determined. Unfortunately no clear conclusion relative to the conduction mechanism can be made there from. Computer simulations by molecular dynamics have been performed in CaF 2 modeled using a rigid ion potential. The diffusion coefficient, the specific heat, structure factors, mean square displacements of both anions and cations, as well as the temperature dependence of these quantities have been calculated. The good agreement found between calculated quantities and experimental results justified us in using the crude approximation of a rigid on potential. A direct computation of the superionic conductivity has been obtained for the first time using non-equilibrium molecular dynamics in the linear response regime. From the independent calculation of the diffusion coefficient and the conductivity, the Havens ratio has been deduced, Hr 0.34, in the superionic region. Its value suggests that the superionic conductivity of CaF 2 is due to a collective and correlated mechanism, a fact which has been confirmed by the MD trajectory analysis. (author) [fr

Extraction of diffuse correlation spectroscopy flow index by integration of Nth-order linear model with Monte Carlo simulation

Science.gov (United States)

Shang, Yu; Li, Ting; Chen, Lei; Lin, Yu; Toborek, Michal; Yu, Guoqiang

2014-05-01

Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (αDB) in tissues with small volume and large curvature. We proposed an algorithm integrating Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction of αDB. The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on an in vivo stroke model of mouse. Computer simulations shows that the high-order (N ≥ 5) linear algorithm was more accurate in extracting αDB (errors values of errors in extracting αDB were similar to those reconstructed from the noise-free DCS data. In addition, the errors in extracting the relative changes of αDB using both linear algorithm and semi-infinite solution were fairly small (errors < ±2.0%) and did not rely on the tissue volume/geometry. The experimental results from the in vivo stroke mice agreed with those in simulations, demonstrating the robustness of the linear algorithm. DCS with the high-order linear algorithm shows the potential for the inter-subject comparison and longitudinal monitoring of absolute BFI in a variety of tissues/organs with different volumes/geometries.

Electronic structure of Pu-Ce(-Ga) and Pu-Am(-Ga) alloys, stabilized in the {delta} phase; Structure electronique d'alliages Pu-Ce(-Ga) et Pu-Am(-Ga) stabilises en phase {delta}

Energy Technology Data Exchange (ETDEWEB)

Dormeval, M

2001-09-01

The behaviour of {delta}-plutonium, stable between 319 and 451 deg C, exhibits numerous singularities which are still a mystery for both physicists and metallurgists. This is due to its complex electronic structure, and in particular to the 5f electrons, which are at the edge between localization and delocalization. The stability domain of the {delta} phase can be extended down to room temperature by alloying with so called 'deltagen atoms' such as gallium (Ga), aluminum (A1), cerium (Ce) or americium (Am). The present work deals, one the one hand, with the influence of cerium and americium solutes regarding the localization of the 5f electrons of {delta}-plutonium, in binary Pu-Ce and Pu-Am alloys. On the other hand, the effect of two different deltagen solutes, simultaneously present, on the stability of the {delta} phase has been studied in ternary Pu-Am-Ga and Pu-Ce-Ga alloys. The electronic structure being strongly related to the crystalline organization, characterization methods such as X-Ray diffraction and EXAFS measurements were used together with electrical resistivity and magnetic susceptibility experiments. These showed that the roles of cerium and americium, supposed to be similar at the beginning of this investigation, are actually very different. Moreover, the additive effect of cerium and gallium, and, americium and gallium, has been demonstrated. Studying plutonium alloys, which are radioactive, also means following their evolution in time. The characteristics of the alloys have then been followed which allowed to detect, in Pu-Ce(-Ga) alloys, a destabilization of the {delta} phase and, to observe, in Pu-Am(-Ga) alloys, the influence of self-irradiation defects on the magnetic response. (author)

Infinite sets of conservation laws for linear and non-linear field equations

International Nuclear Information System (INIS)

Niederle, J.

1984-01-01

The work was motivated by a desire to understand group theoretically the existence of an infinite set of conservation laws for non-interacting fields and to carry over these conservation laws to the case of interacting fields. The relation between an infinite set of conservation laws of a linear field equation and the enveloping algebra of its space-time symmetry group was established. It is shown that in the case of the Korteweg-de Vries (KdV) equation to each symmetry of the corresponding linear equation delta sub(o)uxxx=u sub() determined by an element of the enveloping algebra of the space translation algebra, there corresponds a symmetry of the full KdV equation

MEMS 3-DoF gyroscope design, modeling and simulation through equivalent circuit lumped parameter model

International Nuclear Information System (INIS)

Mian, Muhammad Umer; Khir, M. H. Md.; Tang, T. B.; Dennis, John Ojur; Riaz, Kashif; Iqbal, Abid; Bazaz, Shafaat A.

2015-01-01

Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used

MEMS 3-DoF gyroscope design, modeling and simulation through equivalent circuit lumped parameter model

Energy Technology Data Exchange (ETDEWEB)

Mian, Muhammad Umer, E-mail: umermian@gmail.com; Khir, M. H. Md.; Tang, T. B. [Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Dennis, John Ojur [Department of Fundamental & Applied Sciences, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Riaz, Kashif; Iqbal, Abid [Faculty of Electronics Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhaw (Pakistan); Bazaz, Shafaat A. [Department of Computer Science, Center for Advance Studies in Engineering, Islamabad (Pakistan)

2015-07-22

Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used.

Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

DEFF Research Database (Denmark)

Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

2008-01-01

is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-state energy within standard DFT. We extend the Delta SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can...... be estimated, which is not possible in traditional Delta SCF because of very delocalized Kohn-Sham orbitals. The method is applied to N2, CO, and NO adsorbed on different metallic surfaces and compared to ordinary Delta SCF without our modification, spatially constrained DFT, and inverse...

Simulation experiment on total ionization dose effects of linear CCD

International Nuclear Information System (INIS)

Tang Benqi; Zhang Yong; Xiao Zhigang; Wang Zujun; Huang Shaoyan

2004-01-01

We carry out the ionization radiation experiment of linear CCDs operated in unbiased, biased, biased and driven mode respectively by Co-60 γ source with our self-designed test system, and offline test the Dark signal and Saturation voltage and SNR varied with total dose for TCD132D, and get some valuable results. On the basis of above work, we set forth a primary experiment approaches to simulate the total dose radiation effects of charge coupled devices. (authors)

Linear motor coil assembly and linear motor

NARCIS (Netherlands)

2009-01-01

An ironless linear motor (5) comprising a magnet track (53) and a coil assembly (50) operating in cooperation with said magnet track (53) and having a plurality of concentrated multi-turn coils (31 a-f, 41 a-d, 51 a-k), wherein the end windings (31E) of the coils (31 a-f, 41 a-e) are substantially

Connectivity in river deltas

Science.gov (United States)

Passalacqua, P.; Hiatt, M. R.; Sendrowski, A.

2016-12-01

Deltas host approximately half a billion people and are rich in ecosystem diversity and economic resources. However, human-induced activities and climatic shifts are significantly impacting deltas around the world; anthropogenic disturbance, natural subsidence, and eustatic sea-level rise are major causes of threat to deltas and in many cases have compromised their safety and sustainability, putting at risk the people that live on them. In this presentation, I will introduce a framework called Delta Connectome for studying connectivity in river deltas based on different representations of a delta as a network. Here connectivity indicates both physical connectivity (how different portions of the system interact with each other) as well as conceptual (pathways of process coupling). I will explore several network representations and show how quantifying connectivity can advance our understanding of system functioning and can be used to inform coastal management and restoration. From connectivity considerations, the delta emerges as a leaky network that evolves over time and is characterized by continuous exchanges of fluxes of matter, energy, and information. I will discuss the implications of connectivity on delta functioning, land growth, and potential for nutrient removal.

Evaluation of the Delta4 phantom for IMRT and VMAT verification

International Nuclear Information System (INIS)

Bedford, James L; Lee, Young K; Wai, Philip; South, Christopher P; Warrington, Alan P

2009-01-01

The Delta 4 diode array phantom (Scandidos, Uppsala, Sweden) was evaluated for verification of segmental intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) on an Elekta linear accelerator (Crawley UK). The device was tested for angular sensitivity by irradiating it from 36 different gantry angles, and the responses of the device to various step-and-shoot segment doses and dose rates were evaluated using an ionization chamber as a comparison. The phantom was then compared with ionization chamber and film results for two prostate and pelvic nodes IMRT plans, two head and neck IMRT plans and two lung VMAT plans. These plans were calculated using Pinnacle 3 (Philips Radiation Oncology Systems, Madison, WI). The uniformity of angular response was better than 0.5% over the range of gantry angles. The uniformity of response of the Delta 4 to different segment monitor units and dose rates was better than 0.5%. The assessment of the IMRT and VMAT plans showed that the Delta 4 measured a dose within 2.5% of the ionization chamber, and compared to film recorded a slightly larger region (range -2% to +7%) agreeing with the planned dose to within 3% and 3 mm. The Delta 4 is a complex device and requires careful benchmarking, but following the successful completion of these measurements, the Delta 4 has been introduced into clinical use. (note)

Recent scientific advances and their implications for sand management near San Francisco, California: the influences of the ebb tidal delta

Science.gov (United States)

Hanes, Daniel M.; Barnard, Patrick L.; Dallas, Kate; Elias, Edwin; Erikson, Li H.; Eshleman, Jodi; Hansen, Jeff; Hsu, Tian Jian; Shi, Fengyan

2011-01-01

Recent research in the San Francisco, California, U.S.A., coastal region has identified the importance of the ebb tidal delta to coastal processes. A process-based numerical model is found to qualitatively reproduce the equilibrium size and shape of the delta. The ebb tidal delta itself has been contracting over the past century, and the numerical model is applied to investigate the sensitivity of the delta to changes in forcing conditions. The large ebb tidal delta has a strong influence upon regional coastal processes. The prominent bathymetry of the ebb tidal delta protects some of the coast from extreme storm waves, but the delta also focuses wave energy toward the central and southern portions of Ocean Beach. Wave focusing likely contributes to a chronic erosion problem at the southern end of Ocean Beach. The ebb tidal delta in combination with non-linear waves provides a potential cross-shore sediment transport pathway that probably supplies sediment to Ocean Beach.

How to use body tilt for the simulation of linear self motion

NARCIS (Netherlands)

Groen, E.L.; Bles, W.

2004-01-01

We examined to what extent body tilt may augment the perception of visually simulated linear self acceleration. Fourteen subjects judged visual motion profiles of fore-aft motion at four different frequencies between 0.04-0.33 Hz, and at three different acceleration amplitudes (0.44, 0.88 and 1.76

Weapon system simulation in flight (WaSiF)

Science.gov (United States)

Bartoldus, Klaus H.

2005-05-01

The research and technology demonstration program was co-funded by the Ministries of Defence of five European countries under the framework of the "EUropean Cooperation for the Long term in Defence" (EUCLID) MoU to include Germany, Italy, The Netherlands, Portugal and Turkey with considerable financial contribution from the industrial entities. EADS Military Aircraft Munich has led a team of seven industries and research centers, including Aermacchi of Italy, DutchSpace and NLR of The Netherlands, OGMA and INETI of Portugal and Marmara Research Center of Turkey. The purpose of the project was the design, realization and demonstration of an embedded real time simulation system allowing the combat training of operational aircrew in a virtual air defence scenario and threat environment against computer generated forces in the air and on the ground while flying on a real aircraft. The simulated scenario is focused on air-to-air beyond visual range engagements of fighter aircraft. WaSiF represents one of the first demonstrations of an advanced embedded real time training system onboard a fighter/training aircraft. The system is integrated onboard the MB339CX aircraft. The overall flight test activity covered a wide variety of test conditions for a total of 21 test flights; the operational airborne time of the WaSiF amounted to nearly 18 hours. The demonstration and evaluation were quite positive; the five-nation aircrew was very fond of their first encounter with the virtual world in the military flight training. A common view and approach towards Network Centric Warfare is but emerging. WaSiF in a future networked configuration holds lots of promise to serve the needs of Integrated Air Defence: Common training in a virtual environment.

Delta 2.0

DEFF Research Database (Denmark)

Skott, Jeppe; Skott, Charlotte Krog; Jess, Kristine

DELTA 2.0 er en ny og helt opdateret udgave af Delta, der i ti år været brugt i matematiklærernes grund-, efter- og videreuddannelse. DELTA 2.0 er seriens almene fagdidaktik. Der er også fagdidaktiske overvejelser i de øvrige bøger i serien, men de er knyttet til specifikt matematisk indhold. DELTA...... 2.0 behandler mere generelle matematikdidaktiske problemstillinger såsom læringsteoretiske overvejelser i forbindelse med matematik, centrale aspekter af det at undervise i matematik og digitale teknologier som værktøj til at støtte elevers faglige læring af matematik....

Peat compaction in deltas : implications for Holocene delta evolution

NARCIS (Netherlands)

van Asselen, S.

2010-01-01

Many deltas contain substantial amounts of peat, which is the most compressible soil type. Therefore, peat compaction potentially leads to high amounts of subsidence in deltas. The main objective of this research was to quantify subsidence due to peat compaction in Holocene fluvial-deltaic settings

FDTD simulation of trapping nanowires with linearly polarized and radially polarized optical tweezers.

Science.gov (United States)

Li, Jing; Wu, Xiaoping

2011-10-10

In this paper a model of the trapping force on nanowires is built by three dimensional finite-difference time-domain (FDTD) and Maxwell stress tensor methods, and the tightly focused laser beam is expressed by spherical vector wave functions (VSWFs). The trapping capacities on nanoscale-diameter nanowires are discussed in terms of a strongly focused linearly polarized beam and radially polarized beam. Simulation results demonstrate that the radially polarized beam has higher trapping efficiency on nanowires with higher refractive indices than linearly polarized beam.

River salinity on a mega-delta, an unstructured grid model approach.

Science.gov (United States)

Bricheno, Lucy; Saiful Islam, Akm; Wolf, Judith

2014-05-01

With an average freshwater discharge of around 40,000 m3/s the BGM (Brahmaputra Ganges and Meghna) river system has the third largest discharge worldwide. The BGM river delta is a low-lying fertile area covering over 100,000 km2 mainly in India and Bangladesh. Approximately two-thirds of the Bangladesh people work in agriculture and these local livelihoods depend on freshwater sources directly linked to river salinity. The finite volume coastal ocean model (FVCOM) has been applied to the BGM delta in order to simulate river salinity under present and future climate conditions. Forced by a combination of regional climate model predictions, and a basin-wide river catchment model, the 3D baroclinic delta model can determine river salinity under the current climate, and make predictions for future wet and dry years. The river salinity demonstrates a strong seasonal and tidal cycle, making it important for the model to be able to capture a wide range of timescales. The unstructured mesh approach used in FVCOM is required to properly represent the delta's structure; a complex network of interconnected river channels. The model extends 250 km inland in order to capture the full extent of the tidal influence and grid resolutions of 10s of metres are required to represent narrow inland river channels. The use of FVCOM to simulate flows so far inland is a novel challenge, which also requires knowledge of the shape and cross-section of the river channels.

Formation of conjugated delta8,delta10-double bonds by delta12-oleic-acid desaturase-related enzymes: biosynthetic origin of calendic acid.

Science.gov (United States)

Cahoon, E B; Ripp, K G; Hall, S E; Kinney, A J

2001-01-26

Divergent forms of the plant Delta(12)-oleic-acid desaturase (FAD2) have previously been shown to catalyze the formation of acetylenic bonds, epoxy groups, and conjugated Delta(11),Delta(13)-double bonds by modification of an existing Delta(12)-double bond in C(18) fatty acids. Here, we report a class of FAD2-related enzymes that modifies a Delta(9)-double bond to produce the conjugated trans-Delta(8),trans-Delta(10)-double bonds found in calendic acid (18:3Delta(8trans,10trans,12cis)), the major component of the seed oil of Calendula officinalis. Using an expressed sequence tag approach, cDNAs for two closely related FAD2-like enzymes, designated CoFADX-1 and CoFADX-2, were identified from a C. officinalis developing seed cDNA library. The deduced amino acid sequences of these polypeptides share 40-50% identity with those of other FAD2 and FAD2-related enzymes. Expression of either CoFADX-1 or CoFADX-2 in somatic soybean embryos resulted in the production of calendic acid. In embryos expressing CoFADX-2, calendic acid accumulated to as high as 22% (w/w) of the total fatty acids. In addition, expression of CoFADX-1 and CoFADX-2 in Saccharomyces cerevisiae was accompanied by calendic acid accumulation when induced cells were supplied exogenous linoleic acid (18:2Delta(9cis,12cis)). These results are thus consistent with a route of calendic acid synthesis involving modification of the Delta(9)-double bond of linoleic acid. Regiospecificity for Delta(9)-double bonds is unprecedented among FAD2-related enzymes and further expands the functional diversity found in this family of enzymes.

On using the linear-quadratic model in daily clinical practice

International Nuclear Information System (INIS)

Yaes, R.J.; Patel, P.; Maruyama, Y.

1991-01-01

To facilitate its use in the clinic, Barendsen's formulation of the Linear-Quadratic (LQ) model is modified by expressing isoeffect doses in terms of the Standard Effective Dose, Ds, the isoeffective dose for the standard fractionation schedule of 2 Gy fractions given once per day, 5 days per week. For any arbitrary fractionation schedule, where total dose D is given in N fractions of size d in a total time T, the corresponding Standard Effective Dose, Ds, will be proportional to the total dose D and the proportionality constant will be called the Standard Relative Effectiveness, SRE, to distinguish it from Barendsen's Relative Effectiveness, RE. Thus, Ds = SRE.D. The constant SRE depends on the parameters of the fractionation schedule, and on the tumor or normal tissue being irradiated. For the simple LQ model with no time dependence, which is applicable to late reacting tissue, SRE = [(d + delta)/(2 + delta)], where d is the fraction size and delta = alpha/beta is the alpha/beta ratio for the tissue of interest, with both d and delta expressed in units of Gy. Application of this method to the Linear Quadratic model with a time dependence, the LQ + time model, and to low dose rate brachytherapy will be discussed. To clarify the method of calculation, and to demonstrate its simplicity, examples from the clinical literature will be used

Faster Simulation Methods for the Non-Stationary Random Vibrations of Non-Linear MDOF Systems

DEFF Research Database (Denmark)

Askar, A.; Köylüoglu, H. U.; Nielsen, Søren R. K.

subject to nonstationary Gaussian white noise excitation, as an alternative to conventional direct simulation methods. These alternative simulation procedures rely on an assumption of local Gaussianity during each time step. This assumption is tantamount to various linearizations of the equations....... Such a treatment offers higher rates of convergence, faster speed and higher accuracy. These procedures are compared to the direct Monte Carlo simulation procedure, which uses a fourth order Runge-Kutta scheme with the white noise process approximated by a broad band Ruiz-Penzien broken line process...

17 bit 4.35 mW 1 kHz Delta Sigma ADC and 256-to-1 multiplexer for remote handling instrumentation equipment

Energy Technology Data Exchange (ETDEWEB)

Verbeeck, Jens, E-mail: jens.verbeeck@esat.kuleuven.be [KU Leuven, Department ESAT-MICAS, Kasteelpark Arenberg 10, 3001 Heverlee (Belgium); KH Kempen University College, IBW-RELIC, Kleinhoefstraat 4, 2440 Geel (Belgium); Van Uffelen, Marco [Fusion for Energy, c/Josep, n° 2, Torres Diagonal Litoral, Ed. B3, 08019 Barcelona (Spain); Steyaert, Michiel [KU Leuven, Department ESAT-MICAS, Kasteelpark Arenberg 10, 3001 Heverlee (Belgium); Leroux, Paul [KU Leuven, Department ESAT-MICAS, Kasteelpark Arenberg 10, 3001 Heverlee (Belgium); KH Kempen University College, IBW-RELIC, Kleinhoefstraat 4, 2440 Geel (Belgium)

2013-10-15

Highlights: ► We present a radiation hard 17 bit-1 kHz 4.35 mW Delta Sigma ADC. ► A radiation tolerant 256-to-1 multiplexer is shown. ► We propose a generic radiation tolerant ASIC for use in an instrumentation link. ► The ASIC can interface more than hundred pressure or resistive sensors. ► All building blocks have a simulated radiation tolerance of more than 1 MGy. -- Abstract: A radiation tolerant Delta-Sigma Analog-to-Digital Converter (ADC) and multiplexer is presented. The design features a 1.5 V, 17 bit ADC consuming 4.35 mW at a sample frequency of 1 MHz. The ADC features a bandwidth of 1 kHz and utilizes a Correlated Double Sampling technique (CDS) to remove offset and 1/f noise. The circuit maintains its 17 bit resolution upon a simulated radiation dose exceeding 1 MGy and varying temperatures between 0 °C and 85 °C. Next a multiplexer is presented. It can multiplex 256 channels at a clock frequency of 128 MHz or has a data throughput of 256 MSample/s. In addition the bit period of the multiplexer varies less then 1.5% due to the influence of temperature or radiation, which proves the temperature and radiation tolerance.

Design and Task Analysis for a Game-Based Shiphandling Simulator Using an Open Source Game Engine (DELTA3D)

Science.gov (United States)

2011-09-01

Rodrigues, F. L. D. (2010).Sistema de realidade virtual para simulador visual de passadiço ( Virtual reality system for visual bridge simulator...products/shipsimulatorextremes Souza, I. (2007). Simulador de Realidade Virtual para o Treinamento de Biópsia por Agulha de Nódulos da Glândula de...Games, Shiphandling Simulator, Training, Virtual Environments, Simulation, Open Source, Brazilian Navy 16. PRICE CODE 17. SECURITY CLASSIFICATION OF

Linear Discriminant Analysis achieves high classification accuracy for the BOLD fMRI response to naturalistic movie stimuli.

Directory of Open Access Journals (Sweden)

Hendrik eMandelkow

2016-03-01

Full Text Available Naturalistic stimuli like movies evoke complex perceptual processes, which are of great interest in the study of human cognition by functional MRI (fMRI. However, conventional fMRI analysis based on statistical parametric mapping (SPM and the general linear model (GLM is hampered by a lack of accurate parametric models of the BOLD response to complex stimuli. In this situation, statistical machine-learning methods, a.k.a. multivariate pattern analysis (MVPA, have received growing attention for their ability to generate stimulus response models in a data-driven fashion. However, machine-learning methods typically require large amounts of training data as well as computational resources. In the past this has largely limited their application to fMRI experiments involving small sets of stimulus categories and small regions of interest in the brain. By contrast, the present study compares several classification algorithms known as Nearest Neighbour (NN, Gaussian Naïve Bayes (GNB, and (regularised Linear Discriminant Analysis (LDA in terms of their classification accuracy in discriminating the global fMRI response patterns evoked by a large number of naturalistic visual stimuli presented as a movie.Results show that LDA regularised by principal component analysis (PCA achieved high classification accuracies, above 90% on average for single fMRI volumes acquired 2s apart during a 300s movie (chance level 0.7% = 2s/300s. The largest source of classification errors were autocorrelations in the BOLD signal compounded by the similarity of consecutive stimuli. All classifiers performed best when given input features from a large region of interest comprising around 25% of the voxels that responded significantly to the visual stimulus. Consistent with this, the most informative principal components represented widespread distributions of co-activated brain regions that were similar between subjects and may represent functional networks. In light of these

Improved stability and performance from sigma-delta modulators using 1-bit vector quantization

DEFF Research Database (Denmark)

Risbo, Lars

1993-01-01

A novel class of sigma-delta modulators is presented. The usual scalar 1-b quantizer in a sigma-delta modulator is replaced by a 1-b vector quantizer with a N-dimensional input state-vector from the linear feedback filter. Generally, the vector quantizer changes the nonlinear dynamics...... of the modulator, and a proper choice of vector quantizer can improve both system stability and coding performance. It is shown how to construct the vector quantizer in order to limit the excursions in state-space. The proposed method is demonstrated graphically for a simple second-order modulator...

Modeling pesticide loadings from the San Joaquin watershed into the Sacramento-San Joaquin Delta using SWAT

Science.gov (United States)

Chen, H.; Zhang, M.

2016-12-01

The Sacramento-San Joaquin Delta is an ecologically rich, hydrologically complex area that serves as the hub of California's water supply. However, pesticides have been routinely detected in the Delta waterways, with concentrations exceeding the benchmark for the protection of aquatic life. Pesticide loadings into the Delta are partially attributed to the San Joaquin watershed, a highly productive agricultural watershed located upstream. Therefore, this study aims to simulate pesticide loadings to the Delta by applying the Soil and Water Assessment Tool (SWAT) model to the San Joaquin watershed, under the support of the USDA-ARS Delta Area-Wide Pest Management Program. Pesticide use patterns in the San Joaquin watershed were characterized by combining the California Pesticide Use Reporting (PUR) database and GIS analysis. Sensitivity/uncertainty analyses and multi-site calibration were performed in the simulation of stream flow, sediment, and pesticide loads along the San Joaquin River. Model performance was evaluated using a combination of graphic and quantitative measures. Preliminary results indicated that stream flow was satisfactorily simulated along the San Joaquin River and the major eastern tributaries, whereas stream flow was less accurately simulated in the western tributaries, which are ephemeral small streams that peak during winter storm events and are mainly fed by irrigation return flow during the growing season. The most sensitive parameters to stream flow were CN2, SOL_AWC, HRU_SLP, SLSUBBSN, SLSOIL, GWQMN and GW_REVAP. Regionalization of parameters is important as the sensitivity of parameters vary significantly spatially. In terms of evaluation metric, NSE tended to overrate model performance when compared to PBIAS. Anticipated results will include (1) pesticide use pattern analysis, (2) calibration and validation of stream flow, sediment, and pesticide loads, and (3) characterization of spatial patterns and temporal trends of pesticide yield.

Modeling results for a linear simulator of a divertor

International Nuclear Information System (INIS)

Hooper, E.B.; Brown, M.D.; Byers, J.A.; Casper, T.A.; Cohen, B.I.; Cohen, R.H.; Jackson, M.C.; Kaiser, T.B.; Molvik, A.W.; Nevins, W.M.; Nilson, D.G.; Pearlstein, L.D.; Rognlien, T.D.

1993-01-01

A divertor simulator, IDEAL, has been proposed by S. Cohen to study the difficult power-handling requirements of the tokamak program in general and the ITER program in particular. Projections of the power density in the ITER divertor reach ∼ 1 Gw/m 2 along the magnetic fieldlines and > 10 MW/m 2 on a surface inclined at a shallow angle to the fieldlines. These power densities are substantially greater than can be handled reliably on the surface, so new techniques are required to reduce the power density to a reasonable level. Although the divertor physics must be demonstrated in tokamaks, a linear device could contribute to the development because of its flexibility, the easy access to the plasma and to tested components, and long pulse operation (essentially cw). However, a decision to build a simulator requires not just the recognition of its programmatic value, but also confidence that it can meet the required parameters at an affordable cost. Accordingly, as reported here, it was decided to examine the physics of the proposed device, including kinetic effects resulting from the intense heating required to reach the plasma parameters, and to conduct an independent cost estimate. The detailed role of the simulator in a divertor program is not explored in this report

A Model Stitching Architecture for Continuous Full Flight-Envelope Simulation of Fixed-Wing Aircraft and Rotorcraft from Discrete Point Linear Models

Science.gov (United States)

2016-04-01

AND ROTORCRAFT FROM DISCRETE -POINT LINEAR MODELS Eric L. Tobias and Mark B. Tischler Aviation Development Directorate Aviation and Missile...Stitching Architecture for Continuous Full Flight-Envelope Simulation of Fixed-Wing Aircraft and Rotorcraft from Discrete -Point Linear Models 5...of discrete -point linear models and trim data. The model stitching simulation architecture is applicable to any aircraft configuration readily

Predictable topography simulation of SiO2 etching by C5F8 gas combined with a plasma simulation, sheath model and chemical reaction model

International Nuclear Information System (INIS)

Takagi, S; Onoue, S; Iyanagi, K; Nishitani, K; Shinmura, T; Kanoh, M; Itoh, H; Shioyama, Y; Akiyama, T; Kishigami, D

2003-01-01

We have developed a simulation for predicting reactive ion etching (RIE) topography, which is a combination of plasma simulation, the gas reaction model, the sheath model and the surface reaction model. The simulation is applied to the SiO 2 etching process of a high-aspect-ratio contact hole using C 5 F 8 gas. A capacitively coupled plasma (CCP) reactor of an 8-in. wafer was used in the etching experiments. The baseline conditions are RF power of 1500 W and gas pressure of 4.0 Pa in a gas mixture of Ar, O 2 and C 5 F 8 . The plasma simulation reproduces the tendency that CF 2 radical density increases rapidly and the electron density decreases gradually with increasing gas flow rate of C 5 F 8 . In the RIE topography simulation, the etching profiles such as bowing and taper shape at the bottom are reproduced in deep holes with aspect ratios greater than 19. Moreover, the etching profile, the dependence of the etch depth on the etching time, and the bottom diameter can be predicted by this simulation

Non-linear gyrokinetic simulations of microturbulence in TCV electron internal transport barriers

Energy Technology Data Exchange (ETDEWEB)

Lapillonne, X; Brunner, S; Sauter, O; Villard, L [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Fable, E; Goerler, T; Jenko, F; Merz, F, E-mail: stephan.brunner@epfl.ch [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

2011-05-15

Using the local (flux-tube) version of the Eulerian code GENE (Jenko et al 2000 Phys. Plasmas 7 1904), gyrokinetic simulations of microturbulence were carried out considering parameters relevant to electron-internal transport barriers (e-ITBs) in the TCV tokamak (Sauter et al 2005 Phys. Rev. Lett. 94 105002), generated under conditions of low or negative shear. For typical density and temperature gradients measured in such barriers, the corresponding simulated fluctuation spectra appears to simultaneously contain longer wavelength trapped electron modes (TEMs, for typically k{sub p}erpendicular{rho}{sub i} < 0.5, k{sub p}erpendicular being the characteristic perpendicular wavenumber and {rho}{sub i} the ion Larmor radius) and shorter wavelength ion temperature gradient modes (ITG, k{sub p}erpendicular{rho}{sub i} > 0.5). The contributions to the electron particle flux from these two types of modes are, respectively, outward/inward and may cancel each other for experimentally realistic gradients. This mechanism may partly explain the feasibility of e-ITBs. The non-linear simulation results confirm the predictions of a previously developed quasi-linear model (Fable et al 2010 Plasma Phys. Control. Fusion 52 015007), namely that the stationary condition of zero particle flux is obtained through the competitive contributions of ITG and TEM. A quantitative comparison of the electron heat flux with experimental estimates is presented as well.

Design and numerical simulation of the electromagnetic field of linear anode layer ion source

International Nuclear Information System (INIS)

Wang Lisheng; Tang Deli; Cheng Changming

2006-01-01

The principle of anode layer ion source for etching, pre-cleaning and ion beam assisted deposition was described. The influence of the magnetic field on the performance of anode layer ion source was analyzed. Design of the magnetic loop for the linear anode layer ion source was given. The electromagnetic field distribution of the ion source was simulated by means of ANSYS code and the simulation results were in agreement with experimental ones. The numerical simulation results of the electromagnetic field are useful for improving the anode layer ion source. (authors)

The classical Pierce diode: Using particle simulations on linear and nonlinear behavior and final states

International Nuclear Information System (INIS)

Crystal, T.L.; Kuhn, S.; Birdsall, C.K.

1984-01-01

The classical Pierce diode is a simple 1-d system of two shorted metal plates, a cold beam of electrons injected from one side and a neutralizing background of rigid ions. While the plasma medium is technically stable, the finiteness of the Pierce system allows stable and unstable operation. It is usefully studied as an archetypical bounded plasma system, related e.g., to Q-machines, particle accelerators, thermionic converters. New particle simulations of the Pierce diode have successfully recovered many novel linear phenomena including the dominant linear eigenmodes (seen in the internal electrostatic fields), and the dominant and subdominant eigenfrequencies, (seen both in the internal electrostatics and in the external circuit current, J/sub ext/(t)). These simulation results conform very well to detailed predictions of a new linear analysis. The final (nonlinear) state recovered can show critical dependence on initial (linear perturbation) conditions, and can be made steady-state (d.c.) or periodic-oscillatory by simply changing the initial conditions by a factor of 10/sup -4/ or less. A third class of final state is also possible which has oscillations which seem to be nonperiodic

Linear-algebraic bath transformation for simulating complex open quantum systems

International Nuclear Information System (INIS)

Huh, Joonsuk; Mostame, Sarah; Fujita, Takatoshi; Aspuru-Guzik, Alán; Yung, Man-Hong

2014-01-01

In studying open quantum systems, the environment is often approximated as a collection of non-interacting harmonic oscillators, a configuration also known as the star-bath model. It is also well known that the star-bath can be transformed into a nearest-neighbor interacting chain of oscillators. The chain-bath model has been widely used in renormalization group approaches. The transformation can be obtained by recursion relations or orthogonal polynomials. Based on a simple linear algebraic approach, we propose a bath partition strategy to reduce the system-bath coupling strength. As a result, the non-interacting star-bath is transformed into a set of weakly coupled multiple parallel chains. The transformed bath model allows complex problems to be practically implemented on quantum simulators, and it can also be employed in various numerical simulations of open quantum dynamics. (paper)

Delta Power Control Strategy for Multistring Grid-Connected PV Inverters

DEFF Research Database (Denmark)

Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

2017-01-01

, is required for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control (DPC) for grid-connected PV systems is presented, where the multistring PV inverter configuration is adopted. This control strategy is a combination of maximum power point...... tracking (MPPT) and constant power generation (CPG) modes. In this control scheme, one PV string operating in the MPPT mode estimates the available power, whereas the other PV strings regulate the total PV power by the CPG control strategy in such a way that the delta power constraint for the entire PV...... system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the proposed DPC strategy, where the power reserve according to the delta power constraint is achieved under several operating conditions....

Monte Carlo simulations of a ferromagnetic-FeF2 system

International Nuclear Information System (INIS)

Billoni, Orlando V.; Tamarit, Francisco A.; Cannas, Sergio A.

2006-01-01

In this work, we perform Monte Carlo simulations to study the magnetization reversal mechanism in ferromagnetic thin films on FeF 2 . In particular, we emulate a bilayer AFM/FM structure, where the AFM interface corresponds to an uncompensated (100) plane. The magnetic moments are modeled by classical Heisenberg spin variables. Our analysis focus on the role of the exchange interaction J AF between the FM spins and the spins belonging to the AFM interface on the reversal mechanisms of the magnetization. By simulating hysteresis loops we study the effect of temperature on the bias field

June Solstice Equatorial Spread F in the American Sector: A Numerical Assessment of Linear Stability Aided by Incoherent Scatter Radar Measurements

Science.gov (United States)

Zhan, Weijia; S. Rodrigues, Fabiano

2018-01-01

Previous studies have suggested that weakening downward plasma drifts can produce favorable conditions for the ionospheric Generalized Rayleigh-Taylor (GRT) instability and explain the occurrence of postmidnight equatorial spread F (ESF). We evaluated this hypothesis using numerical simulations aided by measurements and attempted to explain ESF events observed in the American sector during June solstice, low solar flux conditions. We analyzed plasma drifts and ESF measurements made by the incoherent scatter radar of the Jicamarca Radio Observatory (11.95° S, 76.87° W, ˜1° dip). We found adequate measurements during a prototypical, quiet time event on 4-5 June 2008 when the downward drifts weakened and a fully developed ESF appeared. The measured drifts were used as input for the SAMI2 model. SAMI2 reproduced an "apparent" uplift of the ionosphere based on h'F measurements that was consistent with expectations and observations. SAMI2 also provided parameters for estimation of the flux tube linear growth rates of GRT instability associated with the weakening drift event. We found that the weakening drifts did produce unstable conditions with positive growth rates. The growth rates, however, were slower than those obtained for typical, premidnight ESF events and those obtained for similar drift conditions in other longitude sectors. We show, however, that departures in the wind pattern, from climatological model predictions, can produce favorable conditions for instability development. Following the hypothesis of Huba and Krall (2013) and using SAMI2 simulations, we show that equatorward winds, when combined with weakening drifts, could have contributed to the unstable conditions responsible for the postmidnight ESF events.

Suited versus unsuited analog astronaut performance using the Aouda.X space suit simulator: the DELTA experiment of MARS2013.

Science.gov (United States)

Soucek, Alexander; Ostkamp, Lutz; Paternesi, Roberta

2015-04-01

Space suit simulators are used for extravehicular activities (EVAs) during Mars analog missions. Flight planning and EVA productivity require accurate time estimates of activities to be performed with such simulators, such as experiment execution or traverse walking. We present a benchmarking methodology for the Aouda.X space suit simulator of the Austrian Space Forum. By measuring and comparing the times needed to perform a set of 10 test activities with and without Aouda.X, an average time delay was derived in the form of a multiplicative factor. This statistical value (a second-over-second time ratio) is 1.30 and shows that operations in Aouda.X take on average a third longer than the same operations without the suit. We also show that activities predominantly requiring fine motor skills are associated with larger time delays (between 1.17 and 1.59) than those requiring short-distance locomotion or short-term muscle strain (between 1.10 and 1.16). The results of the DELTA experiment performed during the MARS2013 field mission increase analog mission planning reliability and thus EVA efficiency and productivity when using Aouda.X.

Low cycle corrosion fatigue properties of F316Ti in simulated LWR primary environment

International Nuclear Information System (INIS)

Xu Xuelian; Ding Yaping; Katada, Y.; Sato, S.

1998-11-01

Environment effect on fatigue performance of materials used for Pressurized boundary, including fatigue life and crack growth rate, are of importance to nuclear safety. To predict the fatigue life of nuclear materials and to improve the design of nuclear materials, it is necessary to investigated the material fatigue performances in corrosive environment and to get the fatigue data under its environment to be used in. Low cycle corrosion fatigue (CF) performance investigation of domestic F316Ti in simulated BWR and PWR primary environment was carried out. The result shows that the high temperature water environment is one of the most important factors on CF properties. For the same material, the low cycle fatigue life in high temperature air is longer than that in simulated BWR and PWR primary environments. In high temperature water, domestic F316Ti has almost the same low cycle corrosion fatigue performance as F316 (made in Japan). All of the fatigue data are scattered within ASME best-fit curve and ASME design fatigue curve. In high strain range, there is no significant difference of the CF performance for F316Ti in both of BWR and PWR primary environments. With the decrease of strain amplitude, the difference appears gradually. The data is located at the short life side of the fatigue data in simulated BWR primary environment. Titanium is distributed uniformly in F316Ti manufactured in Fushun Steel Factory. Ni, Cr, Mo in this material are located at the high side of the alloy chemical composition range. So, F316Ti has a better CF property in high temperature water

$\\delta$-Expansion at Finite Temperature

OpenAIRE

Ramos, Rudnei O.

1996-01-01

We apply the $\\delta$-expansion perturbation scheme to the $\\lambda \\phi^{4}$ self-interacting scalar field theory in 3+1 D at finite temperature. In the $\\delta$-expansion the interaction term is written as $\\lambda (\\phi^{2})^{ 1 + \\delta}$ and $\\delta$ is considered as the perturbation parameter. We compute within this perturbative approach the renormalized mass at finite temperature at a finite order in $\\delta$. The results are compared with the usual loop-expansion at finite temperature.

Variation in leaf water delta D and delta 18O values during the evapotranspiration process

International Nuclear Information System (INIS)

Leopoldo, P.R.; Foloni, L.L.

1984-01-01

A theoretical model was developed to evaluate leaf water delta D and delta 18 O variation in relation to: leaf temperature, relative humidity converted to leaf temperature and delta D and delta 18 O values of atmospheric water vapour and soil water. (M.A.C.) [pt

Using Remote Sensing Data to Parameterize Ice Jam Modeling for a Northern Inland Delta

Directory of Open Access Journals (Sweden)

Fan Zhang

2017-04-01

Full Text Available The Slave River is a northern river in Canada, with ice being an important component of its flow regime for at least half of the year. During the spring breakup period, ice jams and ice-jam flooding can occur in the Slave River Delta, which is of benefit for the replenishment of moisture and sediment required to maintain the ecological integrity of the delta. To better understand the ice jam processes that lead to flooding, as well as the replenishment of the delta, the one-dimensional hydraulic river ice model RIVICE was implemented to simulate and explore ice jam formation in the Slave River Delta. Incoming ice volume, a crucial input parameter for RIVICE, was determined by the novel approach of using MODIS space-born remote sensing imagery. Space-borne and air-borne remote sensing data were used to parameterize the upstream ice volume available for ice jamming. Gauged data was used to complement modeling calibration and validation. HEC-RAS, another one-dimensional hydrodynamic model, was used to determine ice volumes required for equilibrium jams and the upper limit of ice volume that a jam can sustain, as well as being used as a threshold for the volumes estimated by the dynamic ice jam simulations using RIVICE. Parameter sensitivity analysis shows that morphological and hydraulic properties have great impacts on the ice jam length and water depth in the Slave River Delta.

Rise and Fall of one of World's largest deltas; the Mekong delta in Vietnam

Science.gov (United States)

Minderhoud, P. S. J.; Eslami Arab, S.; Pham, H. V.; Erkens, G.; van der Vegt, M.; Oude Essink, G.; Stouthamer, E.; Hoekstra, P.

2017-12-01

The Mekong delta is the third's largest delta in the world. It is home to almost 20 million people and an important region for the food security in South East Asia. As most deltas, the Mekong delta is the dynamic result of a balance of sediment supply, sea level rise and subsidence, hosting a system of fresh and salt water dynamics. Ongoing urbanization, industrialization and intensification of agricultural practices in the delta, during the past decades, resulted in growing domestic, agricultural and industrial demands, and have led to a dramatic increase of fresh water use. Since the year 2000, the amount of fresh groundwater extracted from the subsurface increased by 500%. This accelerated delta subsidence as the groundwater system compacts, with current sinking rates exceeding global sea level rise up to an order of magnitude. These high sinking rates have greatly altered the sediment budget of the delta and, with over 50% of the Mekong delta surface elevated less than 1 meter above sea level, greatly increase vulnerability to flooding and storm surges and ultimately, permanent inundation. Furthermore, as the increasingly larger extractions rapidly reduce the fresh groundwater reserves, groundwater salinization subsequently increases. On top of that, dry season low-flows by the Mekong river cause record salt water intrusion in the delta's estuarine system, creating major problems for rice irrigation. We present the work of three years research by the Dutch-Vietnamese `Rise and Fall' project on land subsidence and salinization in both groundwater and surface water in the Vietnamese Mekong delta.

Losing ground in mega-deltas: basin-scale response to existential threats to the Mekong Delta

Science.gov (United States)

Arias, M. E.; Kondolf, G. M.; Schmitt, R. J. P.; Carling, P. A.; Darby, S. E.; Bizzi, S.; Castelletti, A.; Cochrane, T. A.; Gibson, S.; Kummu, M.; Oeurng, C.; Rubin, Z.; Wild, T. B.

2017-12-01

The Mekong Delta is, in terms of the number of livelihoods it supports, its economic importance, and in its vulnerability to climate change and sinking lands, one of the world's critically threatened mega-deltas. Livelihoods depend on the mere existence of the delta, but also on ecosystem services provided by the delta's drainage basin spanning 795,000 km2 in six abutting countries. These ecosystem services include delivery of sand required to build delta land in the face of rising sea-levels and sediment bound nutrients, provision of spawning habitat for fish that are ultimately harvested in the delta, and hydrologic regulation driving the delta's unique flood-pulse regime. However, while the delta is mainly located in Vietnam, the basin of the Mekong River is shared among China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. In the context of the region's dynamic growth, individual countries are pushing their own development agendas, which include extensive dam building, in-channel sand mining, construction of dykes and canals, and groundwater pumping, all of which contribute to subsidence and erosion of the Delta. Our synthesis of recent research indicates that most of the Mekong's delta land will likely fall below sea-level by 2100 as result of these drivers, exacerbating the impacts of global climatic changes. In this context, local infrastructural projects and changes in land- and water-management may temporarily mitigate some negative effects, but do not address the existential threat to the delta as a whole. To prevent, or at least substantially postpone, the drowning of the Mekong Delta requires identification of the key drivers and immediate concerted management actions on the basin-scale to change the trajectory of subsidence and sediment deficit. A specific challenge is to find the institutional arrangements in this transnational context that could support the needed management changes and equitably distribute costs and impacts. The Mekong Delta is

SU-F-T-238: Analyzing the Performance of MapCHECK2 and Delta4 Quality Assurance Phantoms in IMRT and VMAT Plans

Energy Technology Data Exchange (ETDEWEB)

Lu, SH; Tsai, YC; Lan, HT; Wen, SY; Chen, LH; Kuo, SH; Wang, CW [National Taiwan University Hospital, Taipei City, Taiwan (China)

2016-06-15

Purpose: Intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) have been widely investigated for use in radiotherapy and found to have a highly conformal dose distribution. Delta{sup 4} is a novel cylindrical phantom consisting of 1069 p-type diodes with true treatments measured in the 3D target volume. The goal of this study was to compare the performance of a Delta{sup 4} diode array for IMRT and VMAT planning with ion chamber and MapCHECK2. Methods: Fifty-four IMRT (n=9) and VMAT (n=45) plans were imported to Philips Pinnacle Planning System 9.2 for recalculation with a solid water phantom, MapCHECK2, and the Delta4 phantom. To evaluate the difference between the measured and calculated dose, we used MapCHECK2 and Delta{sup 4} for a dose-map comparison and an ion chamber (PTW 31010 Semiflex 0.125 cc) for a point-dose comparison. Results: All 54 plans met the criteria of <3% difference for the point dose (at least two points) by ion chamber. The mean difference was 0.784% with a standard deviation of 1.962%. With a criteria of 3 mm/3% in a gamma analysis, the average passing rates were 96.86%±2.19% and 98.42%±1.97% for MapCHECK2 and Delta{sup 4}, respectively. The student t-test of MapCHECK2/Delta{sup 4}, ion chamber/Delta{sup 4}, and ion chamber/MapCHECK2 were 0.0008, 0.2944, and 0.0002, respectively. There was no significant difference in passing rates between MapCHECK2 and Delta{sup 4} for the IMRT plan (p = 0.25). However, a higher pass rate was observed in Delta{sup 4} (98.36%) as compared to MapCHECK2 (96.64%, p < 0.0001) for the VMAT plan. Conclusion: The Pinnacle planning system can accurately calculate doses for VMAT and IMRT plans. The Delta{sup 4} shows a similar result when compared to ion chamber and MapCHECK2, and is an efficient tool for patient-specific quality assurance, especially for rotation therapy.

An application of sedimentation simulation in Tahe oilfield

Science.gov (United States)

Tingting, He; Lei, Zhao; Xin, Tan; Dongxu, He

2017-12-01

The braided river delta develops in Triassic low oil formation in the block 9 of Tahe oilfield, but its sedimentation evolution process is unclear. By using sedimentation simulation technology, sedimentation process and distribution of braided river delta are studied based on the geological parameters including sequence stratigraphic division, initial sedimentation environment, relative lake level change and accommodation change, source supply and sedimentary transport pattern. The simulation result shows that the error rate between strata thickness of simulation and actual strata thickness is small, and the single well analysis result of simulation is highly consistent with the actual analysis, which can prove that the model is reliable. The study area belongs to braided river delta retrogradation evolution process, which provides favorable basis for fine reservoir description and prediction.

Hepatitis delta genotypes in chronic delta infection in the northeast of Spain (Catalonia).

Science.gov (United States)

Cotrina, M; Buti, M; Jardi, R; Quer, J; Rodriguez, F; Pascual, C; Esteban, R; Guardia, J

1998-06-01

Based on genetic analysis of variants obtained around the world, three genotypes of the hepatitis delta virus have been defined. Hepatitis delta virus variants have been associated with different disease patterns and geographic distributions. To determine the prevalence of hepatitis delta virus genotypes in the northeast of Spain (Catalonia) and the correlation with transmission routes and clinical disease, we studied the nucleotide divergence of the consensus sequence of HDV RNA obtained from 33 patients with chronic delta hepatitis (24 were intravenous drug users and nine had no risk factors), and four patients with acute self-limited delta infection. Serum HDV RNA was amplified by the polymerase chain reaction technique and a fragment of 350 nucleotides (nt 910 to 1259) was directly sequenced. Genetic analysis of the nucleotide consensus sequence obtained showed a high degree of conservation among sequences (93% of mean). Comparison of these sequences with those derived from different geographic areas and pertaining to genotypes I, II and III, showed a mean sequence identity of 92% with genotype I, 73% with genotype II and 61% with genotype III. At the amino acid level (aa 115 to 214), the mean identity was 87% with genotype I, 63% with genotype II and 56% with genotype III. Conserved regions included the RNA editing domain, the carboxyl terminal 19 amino acids of the hepatitis delta antigen and the polyadenylation signal of the viral mRNA. Hepatitis delta virus isolates in the northeast of Spain are exclusively genotype I, independently of the transmission route and the type of infection. No hepatitis delta virus subgenotypes were found, suggesting that the origin of hepatitis delta virus infection in our geographical area is homogeneous.

Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators

International Nuclear Information System (INIS)

Qiang, J.; Ryne, R.D.; Habib, S.; Decky, V.

1999-01-01

In this paper, we present an object-oriented three-dimensional parallel particle-in-cell code for beam dynamics simulation in linear accelerators. A two-dimensional parallel domain decomposition approach is employed within a message passing programming paradigm along with a dynamic load balancing. Implementing object-oriented software design provides the code with better maintainability, reusability, and extensibility compared with conventional structure based code. This also helps to encapsulate the details of communications syntax. Performance tests on SGI/Cray T3E-900 and SGI Origin 2000 machines show good scalability of the object-oriented code. Some important features of this code also include employing symplectic integration with linear maps of external focusing elements and using z as the independent variable, typical in accelerators. A successful application was done to simulate beam transport through three superconducting sections in the APT linac design

A Fast Monte Carlo Simulation for the International Linear Collider Detector

International Nuclear Information System (INIS)

Furse, D.

2005-01-01

The following paper contains details concerning the motivation for, implementation and performance of a Java-based fast Monte Carlo simulation for a detector designed to be used in the International Linear Collider. This simulation, presently included in the SLAC ILC group's org.lcsim package, reads in standard model or SUSY events in STDHEP file format, stochastically simulates the blurring in physics measurements caused by intrinsic detector error, and writes out an LCIO format file containing a set of final particles statistically similar to those that would have found by a full Monte Carlo simulation. In addition to the reconstructed particles themselves, descriptions of the calorimeter hit clusters and tracks that these particles would have produced are also included in the LCIO output. These output files can then be put through various analysis codes in order to characterize the effectiveness of a hypothetical detector at extracting relevant physical information about an event. Such a tool is extremely useful in preliminary detector research and development, as full simulations are extremely cumbersome and taxing on processor resources; a fast, efficient Monte Carlo can facilitate and even make possible detector physics studies that would be very impractical with the full simulation by sacrificing what is in many cases inappropriate attention to detail for valuable gains in time required for results

Flood mitigation strategies for the Red River Delta

International Nuclear Information System (INIS)

Hansson, K.; Ekenberg, L.

2002-01-01

The increase of natural disasters and especially floods are escalating economical losses. Governments of both developed and developing countries are therefore concerned with increasing post-disaster liabilities in aiding recovery, repairing infrastructure damage and compensation of victims. In particular, governments of developing countries are ill prepared to cover the financial losses of disasters. Moreover, they often experience difficulties in raising funds for the recovery process. In this article, we identify possible policy strategies for coping with complex environmental and social decisions with flood risk involved; using The Red River Delta in Vietnam as a case for investigating various strategies. The paper is concluded with an outline of a model used for policy scenario simulations as well as some very preliminary results from evaluation of three possible policy strategies for The Red River Delta. (author)

Methods for deconvolving sparse positive delta function series

International Nuclear Information System (INIS)

Trussell, H.J.; Schwalbe, L.A.

1981-01-01

Sparse delta function series occur as data in many chemical analyses and seismic methods. These original data are often sufficiently degraded by the recording instrument response that the individual delta function peaks are difficult to distinguish and measure. A method, which has been used to measure these peaks, is to fit a parameterized model by a nonlinear least-squares fitting algorithm. The deconvolution approaches described have the advantage of not requiring a parameterized point spread function, nor do they expect a fixed number of peaks. Two new methods are presented. The maximum power technique is reviewed. A maximum a posteriori technique is introduced. Results on both simulated and real data by the two methods are presented. The characteristics of the data can determine which method gives superior results. 5 figures

Deltas on the move. Making deltas cope with the effects of climate change

International Nuclear Information System (INIS)

Reker, J.; Van Winden, A.; Braakhekke, W.; Vermaat, J.; Eleveld, M.; Janssen, R.; De Reus, N.; Omzigt, N.

2006-01-01

This scoping study is the first phase of a study aimed at: (a) providing knowledge on the potential of a system-based approach to deal with the effects of climate change as an alternative for the more traditional technical measures such as dams, dikes and surge barriers. This should be shown for both rich and poor countries and should address hydrological, ecological as well as socio-economic aspects; and (b) identifying the potential to market these results worldwide. To reach these objectives four research steps are defined: (1) to make an inventory of deltas: their vulnerability to the effects of climate change; (2) development of indicators for successful use of a system-based approach; (3) to provide an overview of the potential of soft measures for these deltas; (4) to select a number of deltas with potential for marketing system-based measures and the development of strategies to link economic and ecological objectives. This scoping study addresses step 1 only. The results from step 1 will be used as a starting point for steps 2 and 3. The outputs of this scoping study are threefold: a background report (this report); a flyer with a brief description of the findings; a website with information on delta's and how these may be affected by climate change. The scoping study will roughly outline which deltas are still functioning in a more or less natural manner - or could be (re)developed in that direction - and thus would be good candidates for a system-based approach. Chapter 2 gives a description of the geomorphological and ecological processes in a delta. In addition, those aspects of climate change that can have an effect on deltas are described. The third chapter deals with human interventions in deltas and whether or not they fit within a system-based approach. In a system-based approach, as presented in Chapter 4, natural processes are given free reign where possible. Chapter 5 shows how available data on deltas could be used in such a system

A simulation study of linear coupling effects and their correction in RHIC

International Nuclear Information System (INIS)

Parzen, G.

1993-01-01

This paper describes a possible skew quadrupole correction system for linear coupling effects for the RHIC92 lattice. A simulation study has been done for this correction system. Results are given for the performance of the correction system and the required strength of the skew quadrupole corrections. The location of the correctors is discussed. For RHIC92, it appears possible to use the same 2 family correction system for all the likely choices of β*. The simulation study gives results for the residual tune splitting that remains after correction with a 2 family correction system. It also gives results for the beta functions before and after correction

Optimal Power Flow in Multiphase Radial Networks with Delta Connections: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Low, Steven H. [California Institute of Technology

2017-11-27

This paper focuses on multiphase radial distribution networks with mixed wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power-flow models are developed to facilitate the integration of delta-connected generation units/loads in the OPF problem. The first model extends traditional branch flow models - and it is referred to as extended branch flow model (EBFM). The second model leverages a linear relationship between per-phase power injections and delta connections, which holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidences indicate that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is also shown that the SDP solution under BVA has a small optimality gap, while the BVA model is accurate in the sense that it reflects actual system voltages.

In vivo metabolism of the methyl homologues of delta-8-tetrahydrocannabinol, delta-9-tetrahydrocannabinol and abn-delta-8-tetrahydrocannabinol in the mouse.

Science.gov (United States)

Brown, N K; Harvey, D J

1988-04-01

Methyl-delta-8-tetrahydrocannabinol (methyl-delta-8-THC), methyl-delta-9-THC and abn-methyl-delta-8-THC were synthesized by condensation of orcinol and (1S)-cis-verbenol and were administered to male Charles River CD-1 mice. Extracted hepatic metabolites were isolated by chromatography on Sephadex LH-20 and examined by gas chromatography/mass spectrometry as trimethylsilyl (TMS), (2H9)TMS and methyl ester/TMS derivatives. In addition, metabolic fractions were reduced with lithium aluminium deuteride to convert carboxylic acids to alcohols for structural correlation. Metabolites from methyl-delta-8-THC were similar with respect to the positions substituted to those produced by higher homologues; the major metabolite was methyl-delta-8-THC-11-oic acid. abn-Methyl-delta-8-THC was metabolized in a different manner. The location of the aromatic methyl group at the position adjacent to ring fusion appeared to inhibit metabolism at C(11) to a considerable extent and also to reduce the amount of the resulting alcohol from being oxidized to a carboxylic acid. This caused other metabolic pathways to become dominant, with the result that a compound containing a hydroxy group at the gem-methyl position was the major metabolite. Hydroxylation at this position has not been confirmed with any other cannabinoid, although it is thought to result in trace concentrations of hydroxy metabolites from some compounds. Metabolism of methyl-delta-9-THC was also similar to that of the higher homologues, with the exception that less metabolism occurred at C(8) and a higher percentage of the total metabolic fraction was accounted for by the 11-oic acid metabolite. Minor metabolites were mainly dihydroxy compounds and hydroxylated derivatives of delta-9-THC-11-oic acid.

Anthropogenic nitrogen input traced by means of {delta} {sup 15}N values in macroalgae: Results from in-situ incubation experiments

Energy Technology Data Exchange (ETDEWEB)

Deutsch, Barbara [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)]. E-mail: barbara.deutsch@io-warnemuende.de; Voss, Maren [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)

2006-08-01

The macroalgae species Fucus vesiculosus (Phaeophyta), Polysiphonia sp., and Ceramium rubrum (Rhodophyta) originally grown at an unpolluted brackish site of the southern Baltic Sea were incubated for 10 and 14 days at 12 stations along a salinity gradient in a highly polluted estuary. We have expected an adaptation of the initially low {delta} {sup 15}N values to the higher ones within the incubation period. In addition to the macroalgae the {delta} {sup 15}N values of NO{sub 3} {sup -} were measured to evaluate fractionation processes of the source nitrate. Inside the estuary, {delta} {sup 15}N-NO{sub 3} {sup -} values were 6.2-9.7 per mille , indicating anthropogenic nitrogen sources. The red macroalgae adequately reflected the nitrate isotope values in the surrounding waters, whereas for F. vesiculosus the results were not that clear. The reasons were assumed to be higher initial {delta} {sup 15}N values of F. vesiculosus and presumably a too slow nitrogen uptake and growth rate. The method of macroalgae incubations seems suitable as a simple monitoring to study the influence of anthropogenic nitrogen loading in an estuarine environment.

Improved application of independent component analysis to functional magnetic resonance imaging study via linear projection techniques.

Science.gov (United States)

Long, Zhiying; Chen, Kewei; Wu, Xia; Reiman, Eric; Peng, Danling; Yao, Li

2009-02-01

Spatial Independent component analysis (sICA) has been widely used to analyze functional magnetic resonance imaging (fMRI) data. The well accepted implicit assumption is the spatially statistical independency of intrinsic sources identified by sICA, making the sICA applications difficult for data in which there exist interdependent sources and confounding factors. This interdependency can arise, for instance, from fMRI studies investigating two tasks in a single session. In this study, we introduced a linear projection approach and considered its utilization as a tool to separate task-related components from two-task fMRI data. The robustness and feasibility of the method are substantiated through simulation on computer data and fMRI real rest data. Both simulated and real two-task fMRI experiments demonstrated that sICA in combination with the projection method succeeded in separating spatially dependent components and had better detection power than pure model-based method when estimating activation induced by each task as well as both tasks.

KAM for the non-linear Schroedinger equation a short presentation

CERN Document Server

Eliasson, H L

2006-01-01

We consider the $d$-dimensional nonlinear Schr\\"o\\-dinger equation under periodic boundary conditions:-i\\dot u=\\Delta u+V(x)*u+\\ep \\frac{\\p F}{\\p \\bar u}(x,u,\\bar u) ;\\quad u=u(t,x),\\;x\\in\\T^dwhere $V(x)=\\sum \\hat V(a)e^{i\\sc{a,x}}$ is an analytic function with $\\hat V$ real and $F$ is a real analytic function in $\\Re u$, $\\Im u$ and $x$. (This equation is a popular model for the `real' NLS equation, where instead of the convolution term $V*u$ we have the potential term $Vu$.) For $\\ep=0$ the equation is linear and has time--quasi-periodic solutions $u$,u(t,x)=\\sum_{s\\in \\AA}\\hat u_0(a)e^{i(|a|^2+\\hat V(a))t}e^{i\\sc{a,x}}, \\quad 0<|\\hat u_0(a)|\\le1,where $\\AA$ is any finite subset of $\\Z^d$. We shall treat $\\omega_a=|a|^2+\\hat V(a)$, $a\\in\\AA$, as free parameters in some domain $U\\subset\\R^{\\AA}$. This is a Hamiltonian system in infinite degrees of freedom, degenerate but with external parameters, and we shall describe a KAM-theory which, in particular, will have the following consequence: \\smallskip {\\it ...

Radar micro-Doppler of wind turbines : Simulation and analysis using rotating linear wire structures

NARCIS (Netherlands)

Krasnov, O.A.; Yarovoy, A.

2015-01-01

A simple electromagnetic model of wind-turbine's main structural elements as the linear wired structures is developed to simulate the temporal patterns of observed radar return Doppler spectra (micro-Doppler). Using the model, the micro-Doppler for different combinations of the turbines rotation

Extending the performance of KrF laser for microlithography by using novel F2 control technology

Science.gov (United States)

Zambon, Paolo; Gong, Mengxiong; Carlesi, Jason; Padmabandu, Gunasiri G.; Binder, Mike; Swanson, Ken; Das, Palash P.

2000-07-01

Exposure tools for 248nm lithography have reached a level of maturity comparable to those based on i-line. With this increase in maturity, there is a concomitant requirement for greater flexibility from the laser by the process engineers. Usually, these requirements pertain to energy, spectral width and repetition rate. By utilizing a combination of laser parameters, the process engineers are often able to optimize throughput, reduce cost-of-operation or achieve greater process margin. Hitherto, such flexibility of laser operation was possible only via significant changes to various laser modules. During our investigation, we found that the key measure of the laser that impacts the aforementioned parameters is its F2 concentration. By monitoring and controlling its slope efficiency, the laser's F2 concentration may be precisely controlled. Thus a laser may tune to operate under specifications as diverse as 7mJ, (Delta) (lambda) FWHM < 0.3 pm and 10mJ, (Delta) (lambda) FWHM < 0.6pm and still meet the host of requirements necessary for lithography. We discus this new F2 control technique and highlight some laser performance parameters.

Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

NARCIS (Netherlands)

Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

1999-01-01

Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia

Linear and non-linear amplification of high-mode perturbations at the ablation front in HiPER targets

Energy Technology Data Exchange (ETDEWEB)

Olazabal-Loume, M; Breil, J; Hallo, L; Ribeyre, X [CELIA, UMR 5107 Universite Bordeaux 1-CNRS-CEA, 351 cours de la Liberation, 33405 Talence (France); Sanz, J, E-mail: olazabal@celia.u-bordeaux1.f [ETSI Aeronauticos, Universidad Politecnica de Madrid, Madrid 28040 (Spain)

2011-01-15

The linear and non-linear sensitivity of the 180 kJ baseline HiPER target to high-mode perturbations, i.e. surface roughness, is addressed using two-dimensional simulations and a complementary analysis by linear and non-linear ablative Rayleigh-Taylor models. Simulations provide an assessment of an early non-linear stage leading to a significant deformation of the ablation surface for modes of maximum linear growth factor. A design using a picket prepulse evidences an improvement in the target stability inducing a delay of the non-linear behavior. Perturbation evolution and shape, evidenced by simulations of the non-linear stage, are analyzed with existing self-consistent non-linear theory.

Structural analysis of molten Na2O-NaF-SiO2 system by Raman spectroscopy and molecular dynamics simulation

International Nuclear Information System (INIS)

Sasaki, Yasushi; Urata, Hidehiro; Ishii, Kuniyoshi

2003-01-01

To determine the effect of F ions on the structure of the molten alkali silicate systems, quenched Na 2 O-SiO 2 -NaF systems were investigated by Raman spectroscopy and molecular dynamics simulation. The systematic increase of 1100cm -1 band intensity in the Raman spectra of the silicate melts accompanying the replacement of O by F provides the evidence for concomitant polymerization of melts. From the molecular dynamics simulation, it was confirmed that most of substituted F was mainly coordinated to Na + ions but not Si 4+ ions at least up to 12.5 mol% of F ion content. A small amount of F was found to be coordinated to Si as a non-bridging ion from the molecular dynamics simulation, although there was no recognizable evidence from Raman Spectroscopy. These results were consistent with the mechanism in which F associated with otherwise network-modifying Na rather than with network-forming Si. Since F was associated to Na + ions, the replace of O ion by two F ions promote the polymerization of silicate melts. (author)

Adaptive Management Methods to Protect the California Sacramento-San Joaquin Delta Water Resource

Science.gov (United States)

Bubenheim, David

2016-01-01

The California Sacramento-San Joaquin River Delta is the hub for California's water supply, conveying water from Northern to Southern California agriculture and communities while supporting important ecosystem services, agriculture, and communities in the Delta. Changes in climate, long-term drought, water quality changes, and expansion of invasive aquatic plants threatens ecosystems, impedes ecosystem restoration, and is economically, environmentally, and sociologically detrimental to the San Francisco Bay/California Delta complex. NASA Ames Research Center and the USDA-ARS partnered with the State of California and local governments to develop science-based, adaptive-management strategies for the Sacramento-San Joaquin Delta. The project combines science, operations, and economics related to integrated management scenarios for aquatic weeds to help land and waterway managers make science-informed decisions regarding management and outcomes. The team provides a comprehensive understanding of agricultural and urban land use in the Delta and the major water sheds (San Joaquin/Sacramento) supplying the Delta and interaction with drought and climate impacts on the environment, water quality, and weed growth. The team recommends conservation and modified land-use practices and aids local Delta stakeholders in developing management strategies. New remote sensing tools have been developed to enhance ability to assess conditions, inform decision support tools, and monitor management practices. Science gaps in understanding how native and invasive plants respond to altered environmental conditions are being filled and provide critical biological response parameters for Delta-SWAT simulation modeling. Operational agencies such as the California Department of Boating and Waterways provide testing and act as initial adopter of decision support tools. Methods developed by the project can become routine land and water management tools in complex river delta systems.

IMPROVING THE AERODYNAMICS OF A TRANSPORT AIRCRAFT WING USING A DELTA PLANFORM WINGTIP LEADING EDGE EXTENSION

Directory of Open Access Journals (Sweden)

D. Gueraiche

2018-01-01

Full Text Available The article explores the possibility of improving the aerodynamic properties of a supercritical-airfoil wing, typical for a modern passenger aircraft, using delta planform passive devices of large relative areas, installed along the leading edge at the wing tip. Delta extensions of various configurations were considered to be used as wingtip devices, potentially improving or completely replacing classical R. Whitcomb winglets. As a result of two- and three-dimensional CFD simulations performed on DLR-F4 wing-body prototype, the potential advantage of these devices was confirmed, particularly when they are installed in a combination with an elliptical planform, largely swept, raked winglet in terms of reducing the induced drag and increasing the aerodynamic lift-to-drag ratio at flight angles of attack. The growth in lift-to-drag ratio applying these devices owes it solely to the drop in drag, without increasing the lift force acting on the wing. In comparison to the classical winglets that lead to a general increase in lifting and lateral forces acting on the wing structure, resulting in a weight penalty, the Wingtip Ledge Edge Triangular Extension (WLETE yields the same L/D ratio increase, but with a much smaller increase in the wing loading. A study has been made of the characteristics of the local (modified airfoil in the WLETE zone in a two-dimensional flow context, and a quantitative analysis has been conducted of the influence of WLETE on both the profile and induced drag components, as well as its influence on the overall lift coefficient of the wing. The resulted synthesis of the WLETE influence on the wing L/D ratio will consist of its influence on each of these components. A comparison of the efficiency of using delta extensions against classical winglets was carried out in a multidisciplinary way, where in addition to the changes in aerodynamic coefficients of lift and drag, the increments of magnitude and distribution of the loads

The effect of quadrupole force to the spectra of nuclei in the f7/2 shell

International Nuclear Information System (INIS)

Zhang Qingying

1992-01-01

The effect of quadrupole force on the spectra of nuclei in the f 7/2 shell is tested. The nuclear spectra are calculated by using the surface delta interaction plus quadrupole interaction and the modified surface delta interaction respectively. The results calculated with the former are much better than those with the latter, the role of the isospin modified term in the modified surface delta interaction can be substituted by the quadrupole interaction term. It is also shown that the effect of quadrupole interaction in the f 7/2 shell is important although the quadrupole deformations of nuclei in this region are not large

Linearly scaling and almost Hamiltonian dielectric continuum molecular dynamics simulations through fast multipole expansions

Energy Technology Data Exchange (ETDEWEB)

Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul, E-mail: tavan@physik.uni-muenchen.de [Lehrstuhl für BioMolekulare Optik, Ludig–Maximilians Universität München, Oettingenstr. 67, 80538 München (Germany)

2015-11-14

Hamiltonian Dielectric Solvent (HADES) is a recent method [S. Bauer et al., J. Chem. Phys. 140, 104103 (2014)] which enables atomistic Hamiltonian molecular dynamics (MD) simulations of peptides and proteins in dielectric solvent continua. Such simulations become rapidly impractical for large proteins, because the computational effort of HADES scales quadratically with the number N of atoms. If one tries to achieve linear scaling by applying a fast multipole method (FMM) to the computation of the HADES electrostatics, the Hamiltonian character (conservation of total energy, linear, and angular momenta) may get lost. Here, we show that the Hamiltonian character of HADES can be almost completely preserved, if the structure-adapted fast multipole method (SAMM) as recently redesigned by Lorenzen et al. [J. Chem. Theory Comput. 10, 3244-3259 (2014)] is suitably extended and is chosen as the FMM module. By this extension, the HADES/SAMM forces become exact gradients of the HADES/SAMM energy. Their translational and rotational invariance then guarantees (within the limits of numerical accuracy) the exact conservation of the linear and angular momenta. Also, the total energy is essentially conserved—up to residual algorithmic noise, which is caused by the periodically repeated SAMM interaction list updates. These updates entail very small temporal discontinuities of the force description, because the employed SAMM approximations represent deliberately balanced compromises between accuracy and efficiency. The energy-gradient corrected version of SAMM can also be applied, of course, to MD simulations of all-atom solvent-solute systems enclosed by periodic boundary conditions. However, as we demonstrate in passing, this choice does not offer any serious advantages.

Migration in Deltas: An Integrated Analysis

Science.gov (United States)

Nicholls, Robert J.; Hutton, Craig W.; Lazar, Attila; Adger, W. Neil; Allan, Andrew; Arto, Inaki; Vincent, Katharine; Rahman, Munsur; Salehin, Mashfiqus; Sugata, Hazra; Ghosh, Tuhin; Codjoe, Sam; Appeaning-Addo, Kwasi

2017-04-01

Deltas and low-lying coastal regions have long been perceived as vulnerable to global sea-level rise, with the potential for mass displacement of exposed populations. The assumption of mass displacement of populations in deltas requires a comprehensive reassessment in the light of present and future migration in deltas, including the potential role of adaptation to influence these decisions. At present, deltas are subject to multiple drivers of environmental change and often have high population densities as they are accessible and productive ecosystems. Climate change, catchment management, subsidence and land cover change drive environmental change across all deltas. Populations in deltas are also highly mobile, with significant urbanization trends and the growth of large cities and mega-cities within or adjacent to deltas across Asia and Africa. Such migration is driven primarily by economic opportunity, yet environmental change in general, and climate change in particular, are likely to play an increasing direct and indirect role in future migration trends. The policy challenges centre on the role of migration within regional adaptation strategies to climate change; the protection of vulnerable populations; and the future of urban settlements within deltas. This paper reviews current knowledge on migration and adaptation to environmental change to discern specific issues pertinent to delta regions. It develops a new integrated methodology to assess present and future migration in deltas using the Volta delta in Ghana, Mahanadi delta in India and Ganges-Brahmaputra-Meghna delta across India and Bangladesh. The integrated method focuses on: biophysical changes and spatial distribution of vulnerability; demographic changes and migration decision-making using multiple methods and data; macro-economic trends and scenarios in the deltas; and the policies and governance structures that constrain and enable adaptation. The analysis is facilitated by a range of

Effect of Process Parameters on Friction Model in Computer Simulation of Linear Friction Welding

Directory of Open Access Journals (Sweden)

A. Yamileva

2014-07-01

Full Text Available The friction model is important part of a numerical model of linear friction welding. Its selection determines the accuracy of the results. Existing models employ the classical law of Amonton-Coulomb where the friction coefficient is either constant or linearly dependent on a single parameter. Determination of the coefficient of friction is a time consuming process that requires a lot of experiments. So the feasibility of determinating the complex dependence should be assessing by analysis of effect of approximating law for friction model on simulation results.

Partial F-tests with multiply imputed data in the linear regression framework via coefficient of determination.

Science.gov (United States)

Chaurasia, Ashok; Harel, Ofer

2015-02-10

Tests for regression coefficients such as global, local, and partial F-tests are common in applied research. In the framework of multiple imputation, there are several papers addressing tests for regression coefficients. However, for simultaneous hypothesis testing, the existing methods are computationally intensive because they involve calculation with vectors and (inversion of) matrices. In this paper, we propose a simple method based on the scalar entity, coefficient of determination, to perform (global, local, and partial) F-tests with multiply imputed data. The proposed method is evaluated using simulated data and applied to suicide prevention data. Copyright © 2014 John Wiley & Sons, Ltd.

Head simulation of linear accelerators and spectra considerations using EGS4 Monte Carlo code in a PC

Energy Technology Data Exchange (ETDEWEB)

Malatara, G; Kappas, K [Medical Physics Department, Faculty of Medicine, University of Patras, 265 00 Patras (Greece); Sphiris, N [Ethnodata S.A., Athens (Greece)

1994-12-31

In this work, a Monte Carlo EGS4 code was used to simulate radiation transport through linear accelerators to produce and score energy spectra and angular distributions of 6, 12, 15 and 25 MeV bremsstrahlung photons exiting from different accelerator treatment heads. The energy spectra was used as input for a convolution method program to calculate the tissue-maximum ratio in water. 100.000 histories are recorded in the scoring plane for each simulation. The validity of the Monte Carlo simulation and the precision to the calculated spectra have been verified experimentally and were in good agreement. We believe that the accurate simulation of the different components of the linear accelerator head is very important for the precision of the results. The results of the Monte Carlo and the Convolution Method can be compared with experimental data for verification and they are powerful and practical tools to generate accurate spectra and dosimetric data. (authors). 10 refs,5 figs, 2 tabs.

Head simulation of linear accelerators and spectra considerations using EGS4 Monte Carlo code in a PC

International Nuclear Information System (INIS)

Malatara, G.; Kappas, K.; Sphiris, N.

1994-01-01

In this work, a Monte Carlo EGS4 code was used to simulate radiation transport through linear accelerators to produce and score energy spectra and angular distributions of 6, 12, 15 and 25 MeV bremsstrahlung photons exiting from different accelerator treatment heads. The energy spectra was used as input for a convolution method program to calculate the tissue-maximum ratio in water. 100.000 histories are recorded in the scoring plane for each simulation. The validity of the Monte Carlo simulation and the precision to the calculated spectra have been verified experimentally and were in good agreement. We believe that the accurate simulation of the different components of the linear accelerator head is very important for the precision of the results. The results of the Monte Carlo and the Convolution Method can be compared with experimental data for verification and they are powerful and practical tools to generate accurate spectra and dosimetric data. (authors)

B meson spectrum and decay constant from N{sub f}=2 simulations

Energy Technology Data Exchange (ETDEWEB)

Blossier, Benoit [Lab. de Physique Theorique, CNRS et Univ. Paris-Sud XI, 91 - Orsay (France); Bulava, John [DESY, Zeuthen (Germany). NIC; Della Morte, Michele [Mainz Univ. (DE), Inst. fuer Kernphysik] (and others)

2010-12-15

We report on the status of an ALPHA Collaboration project to extract quantities for B physics phenomenology from N{sub f}=2 lattice simulations. The framework is Heavy Quark Effective Theory (HQET) expanded up to the first order of the inverse b-quark mass. The couplings of the effective theory are determined by imposing matching conditions of observables computed in HQET with their counterpart computed in QCD. That program, based on N{sub f}=2 simulations in a small physical volume with Schroedinger functional boundary conditions, is now almost finished. On the other side the analysis of configurations selected from the CLS ensembles, in order to measure HQET hadronic matrix elements, has just started recently so that only results obtained at a single lattice spacing, a=0:07 fm, is discussed. We give our first results for the b-quark mass and for the B meson decay constant. (orig.)

An ozone episode in the Pearl River Delta: Field observation and model simulation

Science.gov (United States)

Jiang, F.; Guo, H.; Wang, T. J.; Cheng, H. R.; Wang, X. M.; Simpson, I. J.; Ding, A. J.; Saunders, S. M.; Lam, S. H. M.; Blake, D. R.

2010-11-01

In the fall of 2007 concurrent air sampling field measurements were conducted for the first time in Guangzhou (at Wan Qing Sha (WQS)) and Hong Kong (at Tung Chung (TC)), two cities in the rapidly developing Pearl River Delta region of China that are only 62 km apart. This region is known to suffer from poor air quality, especially during the autumn and winter months, when the prevailing meteorological conditions bring an outflow of continental air to the region. An interesting multiday O3 pollution event (daily maximum O3 > 122 ppbv) was captured during 9-17 November at WQS, while only one O3 episode day (10 November) was observed at TC during this time. The mean O3 mixing ratios at TC and WQS during the episode were 38 ± 3 (mean ± 95% confidence interval) and 51 ± 7 ppbv, respectively, with a mean difference of 13 ppbv and a maximum hourly difference of 150 ppbv. We further divided this event into two periods: 9-11 November as Period 1 and 12-17 November as Period 2. The mixing ratios of O3 and its precursors (NOx and CO) showed significant differences between the two periods at TC. By contrast, no obvious difference was found at WQS, indicating that different air masses arrived at TC for the two periods, as opposed to similar air masses at WQS for both periods. The analysis of VOC ratios and their relationship with O3 revealed strong O3 production at WQS during Period 2, in contrast to relatively weak photochemical O3 formation at TC. The weather conditions implied regional transport of O3 pollution during Period 1 at both sites. Furthermore, a comprehensive air quality model system (Weather Research and Forecasting-Community Multiscale Air Quality model (WRF-CMAQ)) was used to simulate this O3 pollution event. The model system generally reproduced the variations of weather conditions, simulated well the continuous high O3 episode event at WQS, and captured fairly well the elevated O3 mixing ratios in Period 1 and low O3 levels in Period 2 at TC. The modeled

Electronic Structure of TIBa(sub 2)CaCu(sub 2)O(sub 7-delta)

Science.gov (United States)

Vasquez, R. P.; Novikov, D. L.; Freeman, A. J.; Siegal, M. P.

1996-01-01

The core levels of TIBa(sub 2)CaCu(sub 2)O(sub 7-delta) epitaxial films have been measured with x-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin tin orbital band structure method and measured with XPS.

Molecular Dynamics Simulations of a Linear Nanomotor Driven by Thermophoretic Forces

DEFF Research Database (Denmark)

Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

Molecular Dynamics of a Linear Nanomotor Driven by Thermophoresis Harvey A. Zambrano1, Jens H. Walther1,2 and Richard L. Jaffe3 1Department of Mechanical Engineering, Fluid Mechanics, Technical University of Denmark, DK-2800 Lyngby, Denmark; 2Computational Science and Engineering Laboratory, ETH...... future molecular machines a complete understanding of the friction forces involved on the transport process at the molecular level have to be addressed.18 In this work we perform Molecular Dynamics (MD) simulations using the MD package FASTTUBE19 to study a molecular linear motor consisting of coaxial...... the valence forces within the CNT using Morse, harmonic angle and torsion potentials.19We include a nonbonded carbon-carbon Lennard-Jones potential to describe the vdW interaction between the carbon atoms within the double wall portion of the system. We equilibrate the system at 300K for 0.1 ns, by coupling...

Design and Simulation of a PIC16F877A and LM35 Based ...

African Journals Online (AJOL)

This paper describes the design and simulation of a temperature virtual monitoring system using proteus (Labcenter electronics). The device makes use of the PIC16F877A, LM35, 2x16 LCD and other discrete components. The lm35 serve as the temperature sensor, whose output is fed into the PIC16F877A for further ...

A Delta-Sigma beamformer with integrated apodization

DEFF Research Database (Denmark)

Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Hemmsen, Martin Christian

2013-01-01

This paper presents a new design of a discrete time Delta-Sigma (ΔΣ) oversampled ultrasound beamformer which integrates individual channel apodization by means of variable feedback voltage in the Delta-Sigma analog to digital (A/D) converters. The output bit-width of each oversampled A/D converter...... remains the same as in an unmodified one. The outputs of all receiving channels are delayed and summed, and the resulting multi-bit sample stream is filtered and decimated to become an image line. The simplicity of this beamformer allows the production of high-channel-count or very compact beamformers....... The data are acquired using 12-bit flash A/D converters at a sampling rate of 70 MHz, and are then upsampled off-line to 560 MHz for input to the simulated ΔΣ beamformer. The latter generates a B-mode image which is compared to that produced by a digital beamformer that uses 10-bit A/D converters...

Simulating the performance of a distance-3 surface code in a linear ion trap

Science.gov (United States)

Trout, Colin J.; Li, Muyuan; Gutiérrez, Mauricio; Wu, Yukai; Wang, Sheng-Tao; Duan, Luming; Brown, Kenneth R.

2018-04-01

We explore the feasibility of implementing a small surface code with 9 data qubits and 8 ancilla qubits, commonly referred to as surface-17, using a linear chain of 171Yb+ ions. Two-qubit gates can be performed between any two ions in the chain with gate time increasing linearly with ion distance. Measurement of the ion state by fluorescence requires that the ancilla qubits be physically separated from the data qubits to avoid errors on the data due to scattered photons. We minimize the time required to measure one round of stabilizers by optimizing the mapping of the two-dimensional surface code to the linear chain of ions. We develop a physically motivated Pauli error model that allows for fast simulation and captures the key sources of noise in an ion trap quantum computer including gate imperfections and ion heating. Our simulations showed a consistent requirement of a two-qubit gate fidelity of ≥99.9% for the logical memory to have a better fidelity than physical two-qubit operations. Finally, we perform an analysis of the error subsets from the importance sampling method used to bound the logical error rates to gain insight into which error sources are particularly detrimental to error correction.

A survey for southern delta Scuti variable stars

International Nuclear Information System (INIS)

McInally, C.J.; Austin, R.R.D.

1978-01-01

Twenty-nine field stars have been tested photoelectrically for short-period variability. Eighteen of these stars have spectral types between A2 and F5 and are not Am stars; of these, six have been discovered to be variable and one is a suspected variable. HD 185969, with a period of 0.361 day, has the longest known period for a star of the delta Scuti type. The predominance of discovered variables with amplitudes close to the detection limit is suggestive of most stars in the instability strip being pulsators. (author)

Numerical simulation of the effects of variation of angle of attack and sweep angle on vortex breakdown over delta wings

Science.gov (United States)

Ekaterinaris, J. A.; Schiff, Lewis B.

1990-01-01

In the present investigation of the vortical flowfield structure over delta wings at high angles of attack, three-dimensional Navier-Stokes numerical simulations were conducted to predict the complex leeward flowfield characteristics; these encompass leading-edge separation, secondary separation, and vortex breakdown. Attention is given to the effect on solution accuracy of circumferential grid-resolution variations in the vicinity of the wing leading edge, and well as to the effect of turbulence modeling on the solutions. When a critical angle-of-attack was reached, bubble-type vortex breakdown was found. With further angle-of-attack increase, a change from bubble-type to spiral-type vortex breakdown was predicted by the numerical solution.

Super-delta: a new differential gene expression analysis procedure with robust data normalization.

Science.gov (United States)

Liu, Yuhang; Zhang, Jinfeng; Qiu, Xing

2017-12-21

Normalization is an important data preparation step in gene expression analyses, designed to remove various systematic noise. Sample variance is greatly reduced after normalization, hence the power of subsequent statistical analyses is likely to increase. On the other hand, variance reduction is made possible by borrowing information across all genes, including differentially expressed genes (DEGs) and outliers, which will inevitably introduce some bias. This bias typically inflates type I error; and can reduce statistical power in certain situations. In this study we propose a new differential expression analysis pipeline, dubbed as super-delta, that consists of a multivariate extension of the global normalization and a modified t-test. A robust procedure is designed to minimize the bias introduced by DEGs in the normalization step. The modified t-test is derived based on asymptotic theory for hypothesis testing that suitably pairs with the proposed robust normalization. We first compared super-delta with four commonly used normalization methods: global, median-IQR, quantile, and cyclic loess normalization in simulation studies. Super-delta was shown to have better statistical power with tighter control of type I error rate than its competitors. In many cases, the performance of super-delta is close to that of an oracle test in which datasets without technical noise were used. We then applied all methods to a collection of gene expression datasets on breast cancer patients who received neoadjuvant chemotherapy. While there is a substantial overlap of the DEGs identified by all of them, super-delta were able to identify comparatively more DEGs than its competitors. Downstream gene set enrichment analysis confirmed that all these methods selected largely consistent pathways. Detailed investigations on the relatively small differences showed that pathways identified by super-delta have better connections to breast cancer than other methods. As a new pipeline, super-delta

Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion.

Science.gov (United States)

Kwee, Thomas C; Takahara, Taro; Muro, Isao; Van Cauteren, Marc; Imai, Yutaka; Nievelstein, Rutger A J; Mali, Willem P T M; Luijten, Peter R

2010-10-01

The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 × 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects.

Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion

International Nuclear Information System (INIS)

Kwee, T.C.; Takahara, Taro; Nievelstein, R.A.J.; Mali, W.P.T.M.; Luijten, P.R.; Muro, Isao; Imai, Yutaka; Cauteren, M. Van

2010-01-01

The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 x 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects. (author)

Dirac delta representation by exact parametric equations.. Application to impulsive vibration systems

Science.gov (United States)

Chicurel-Uziel, Enrique

2007-08-01

A pair of closed parametric equations are proposed to represent the Heaviside unit step function. Differentiating the step equations results in two additional parametric equations, that are also hereby proposed, to represent the Dirac delta function. These equations are expressed in algebraic terms and are handled by means of elementary algebra and elementary calculus. The proposed delta representation complies exactly with the values of the definition. It complies also with the sifting property and the requisite unit area and its Laplace transform coincides with the most general form given in the tables. Furthermore, it leads to a very simple method of solution of impulsive vibrating systems either linear or belonging to a large class of nonlinear problems. Two example solutions are presented.

Linear response to long wavelength fluctuations using curvature simulations

Energy Technology Data Exchange (ETDEWEB)

Baldauf, Tobias; Zaldarriaga, Matias [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States); Seljak, Uroš [Physics Department, Astronomy Department and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA (United States); Senatore, Leonardo, E-mail: baldauf@ias.edu, E-mail: useljak@berkeley.edu, E-mail: senatore@stanford.edu, E-mail: matiasz@ias.edu [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA (United States)

2016-09-01

We study the local response to long wavelength fluctuations in cosmological N -body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8–20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

Mystery of the delta(980)

International Nuclear Information System (INIS)

Cahn, R.N.; Landshoff, P.V.

1986-01-01

The apparent conflict between the dominance of the decay delta->etaπ in D->deltaπ and its absence in iota->deltaπ is analyzed. Explicit models are presented in which the nearby Kanti K threshold plays an important role in resolving the conflict. (orig.)

Experimental Investigations on Leading-Edge Vortex Structures for Flow over Non-Slender Delta Wings

International Nuclear Information System (INIS)

Jin-Jun, Wang; Wang, Zhang

2008-01-01

The dye injection and hydrogen bubble visualization techniques are used to investigate the dual-vortex structure including its development, breakdown and the spatial location of vortex core over nonslender delta wings. It is concluded that the dual-vortex structure can be affected significantly by sweep angle and Reynolds number, and generated only at small angle of attack. The angle between the projection of outer vortex core on delta wing surface and the root chord line has nothing to do with the Reynolds Number and angle of attack, but has simple linear relation with the sweep angle of the model tested. (fundamental areas of phenomenology (including applications))

Non-linear 3D simulations of current-driven instabilities in jets

International Nuclear Information System (INIS)

Ivanovski, S.; Bonanno, A.

2009-01-01

We present global 3D nonlinear simulations of the Taylor instability in the presence of vertical fields. The initial configuration is in equilibrium, which is achieved by a pressure gradient or an external potential force. The non linear evolution of the system leads to a stable equilibrium with a current free toroidal field. We find the that presence of a vertical poloidal field stabilize the system if B φ ∼B z . The implication of our findings for the physics of astrophysical jets are discussed.

Niger Delta Development Commission and Sustainable ...

African Journals Online (AJOL)

Niger Delta Development Commission and Sustainable Development of Niger Delta Region of Nigeria: The Case of Rivers State. Goddey Wilson. Abstract. The study is on Niger Delta Development Commission and sustainable development of Niger Delta region of Nigeria, the case of Rivers State. The main objective of the ...

Linear Simulations of the Cylindrical Richtmyer-Meshkov Instability in Hydrodynamics and MHD

KAUST Repository

Gao, Song

2013-05-01

The Richtmyer-Meshkov instability occurs when density-stratified interfaces are impulsively accelerated, typically by a shock wave. We present a numerical method to simulate the Richtmyer-Meshkov instability in cylindrical geometry. The ideal MHD equations are linearized about a time-dependent base state to yield linear partial differential equations governing the perturbed quantities. Convergence tests demonstrate that second order accuracy is achieved for smooth flows, and the order of accuracy is between first and second order for flows with discontinuities. Numerical results are presented for cases of interfaces with positive Atwood number and purely azimuthal perturbations. In hydrodynamics, the Richtmyer-Meshkov instability growth of perturbations is followed by a Rayleigh-Taylor growth phase. In MHD, numerical results indicate that the perturbations can be suppressed for sufficiently large perturbation wavenumbers and magnetic fields.

Phonon dispersion curves determination in (delta)-phase Pu-Ga alloys

Energy Technology Data Exchange (ETDEWEB)

Wong, J; Clatterbuck, D; Occelli, F; Farber, D; Schwartz, A; Wall, M; Boro, C; Krisch, M; Beraud, A; Chiang, T; Xu, R; Hong, H; Zschack, P; Tamura, N

2006-02-07

We have designed and successfully employed a novel microbeam on large grain sample concept to conduct high resolution inelastic x-ray scattering (HRIXS) experiments to map the full phonon dispersion curves of an fcc {delta}-phase Pu-Ga alloy. This approach obviates experimental difficulties with conventional inelastic neutron scattering due to the high absorption cross section of the common {sup 239}Pu isotope and the non-availability of large (mm size) single crystal materials for Pu and its alloys. A classical Born von-Karman force constant model was used to model the experimental results, and no less than 4th nearest neighbor interactions had to be included to account for the observation. Several unusual features including, a large elastic anisotropy, a small shear elastic modulus, (C{sub 11}-C{sub 12})/2, a Kohn-like anomaly in the T{sub 1}[011] branch, and a pronounced softening of the T[111] branch towards the L point in the Brillouin are found. These features may be related to the phase transitions of plutonium and to strong coupling between the crystal structure and the 5f valence instabilities. Our results represent the first full phonon dispersions ever obtained for any Pu-bearing material, thus ending a 40-year quest for this fundamental data. The phonon data also provide a critical test for theoretical treatments of highly correlated 5f electron systems as exemplified by recent dynamical mean field theory (DMFT) calculations for {delta}-plutonium. We also conducted thermal diffuse scattering experiments to study the T(111) dispersion at low temperatures with an attempt to gain insight into bending of the T(111) branch in relationship to the {delta} {yields} {alpha}{prime} transformation.

Large old trees influence patterns of delta13C and delta15N in forests.

Science.gov (United States)

Weber, Pascale; Bol, Roland; Dixon, Liz; Bardgett, Richard D

2008-06-01

Large old trees are the dominant primary producers of native pine forest, but their influence on spatial patterns of soil properties and potential feedback to tree regeneration in their neighbourhood is poorly understood. We measured stable isotopes of carbon (delta(13)C) and nitrogen (delta(15)N) in soil and litter taken from three zones of influence (inner, middle and outer zone) around the trunk of freestanding old Scots pine (Pinus sylvestris L.) trees, to determine the trees' influence on below-ground properties. We also measured delta(15)N and delta(13)C in wood cores extracted from the old trees and from regenerating trees growing within their three zones of influence. We found a significant and positive gradient in soil delta(15)N from the inner zone, nearest to the tree centre, to the outer zone beyond the tree crown. This was probably caused by the higher input of (15)N-depleted litter below the tree crown. In contrast, the soil delta(13)C did not change along the gradient of tree influence. Distance-related trends, although weak, were visible in the wood delta(15)N and delta(13)C of regenerating trees. Moreover, the wood delta(15)N of small trees showed a weak negative relationship with soil N content in the relevant zone of influence. Our results indicate that large old trees control below-ground conditions in their immediate surroundings, and that stable isotopes might act as markers for the spatial and temporal extent of these below-ground effects. John Wiley & Sons, Ltd

An analytical framework for strategic delta planning : negotiating consent for long-term sustainable delta development

NARCIS (Netherlands)

Seijger, C.; Douven, W; Hermans, L.M.; Evers, J.; Phi, H. L.; Brunner, J.; Pols, L.; Ligtvoet, W.; Koole, S.; Slager, K.; Vermoolen, M.S.; Hasan, S.; Hoang, V. T M; van Halsema, G

2016-01-01

Sectoral planning on water, agriculture and urban development has not been able to prevent increased flood risks and environmental degradation in many deltas. Governments conceive strategic delta planning as a promising planning approach and develop strategic delta plans. Such plans are linked to

Half-space albedo problem with modified F{sub N} method for linear and quadratic anisotropic scattering

Energy Technology Data Exchange (ETDEWEB)

Tuereci, R.G. [Kirikkale Univ., Kirikkale (Turkey). Kirikkale Vocational School; Tuereci, D. [Ministry of Education, Ankara (Turkey). 75th year Anatolia High School

2017-05-15

One speed, time independent and homogeneous medium neutron transport equation can be solved with the anisotropic scattering which includes both the linear anisotropic and the quadratic anisotropic scattering properties. Having solved Case's eigenfunctions and the orthogonality relations among these eigenfunctions, some neutron transport problems such as albedo problem can be calculated as numerically by using numerical or semi-analytic methods. In this study the half-space albedo problem is investigated by using the modified F{sub N} method.

An expanded Notch-Delta model exhibiting long-range patterning and incorporating MicroRNA regulation.

Directory of Open Access Journals (Sweden)

Jerry S Chen

2014-06-01

Full Text Available Notch-Delta signaling is a fundamental cell-cell communication mechanism that governs the differentiation of many cell types. Most existing mathematical models of Notch-Delta signaling are based on a feedback loop between Notch and Delta leading to lateral inhibition of neighboring cells. These models result in a checkerboard spatial pattern whereby adjacent cells express opposing levels of Notch and Delta, leading to alternate cell fates. However, a growing body of biological evidence suggests that Notch-Delta signaling produces other patterns that are not checkerboard, and therefore a new model is needed. Here, we present an expanded Notch-Delta model that builds upon previous models, adding a local Notch activity gradient, which affects long-range patterning, and the activity of a regulatory microRNA. This model is motivated by our experiments in the ascidian Ciona intestinalis showing that the peripheral sensory neurons, whose specification is in part regulated by the coordinate activity of Notch-Delta signaling and the microRNA miR-124, exhibit a sparse spatial pattern whereby consecutive neurons may be spaced over a dozen cells apart. We perform rigorous stability and bifurcation analyses, and demonstrate that our model is able to accurately explain and reproduce the neuronal pattern in Ciona. Using Monte Carlo simulations of our model along with miR-124 transgene over-expression assays, we demonstrate that the activity of miR-124 can be incorporated into the Notch decay rate parameter of our model. Finally, we motivate the general applicability of our model to Notch-Delta signaling in other animals by providing evidence that microRNAs regulate Notch-Delta signaling in analogous cell types in other organisms, and by discussing evidence in other organisms of sparse spatial patterns in tissues where Notch-Delta signaling is active.

Catalyzing action towards the sustainability of deltas: deltas as integrated socio-ecological systems and sentinels of regional and global change

Science.gov (United States)

Foufoula-Georgiou, E.; Tessler, Z. D.; Brondizio, E.; Overeem, I.; Renaud, F.; Sebesvari, Z.; Nicholls, R. J.; Anthony, E.

2016-12-01

Deltas are highly dynamic and productive environments: they are food baskets of the world, home to biodiverse and rich ecosystems, and they play a central role in food and water security. However, they are becoming increasingly vulnerable to risks arising from human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. Our Belmont Forum DELTAS project (BF-DELTAS: Catalyzing actions towards delta sustainability) encompasses an international network of interdisciplinary research collaborators with focal areas in the Mekong, Ganges Brahmaputra, and the Amazon deltas. The project is organized around five main modules: (1) developing an analytical framework for assessing delta vulnerability and scenarios of change (Delta-SRES), (2) developing an open-acess, science-based integrative modeling framework for risk assessment and decision support (Delta-RADS), (3) developing tools to support quantitative mapping of the bio-physical and socio-economic environments of deltas and consolidate bio-physical and social data within shared data repositories (Delta-DAT), (4) developing Global Delta Vulnerability Indices (Delta-GDVI) that capture current and projected scenarios for major deltas around the world , and (5) collaborating with regional stakeholders to put the science, modeling, and data into action (Delta-ACT). In this talk, a research summary will be presented on three research domains around which significant collaborative work was developed: advancing biophysical classification of deltas, understanding deltas as coupled socio-ecological systems, and analyzing and informing social and environmental vulnerabilities in delta regions.

Computer simulation of immobilized pH gradients at acidic and alkaline extremes - A quest for extended pH intervals

Science.gov (United States)

Mosher, Richard A.; Bier, Milan; Righetti, Pier Giorgio

1986-01-01

Computer simulations of the concentration profiles of simple biprotic ampholytes with Delta pKs 1, 2, and 3, on immobilized pH gradients (IPG) at extreme pH values (pH 3-4 and pH 10-11) show markedly skewed steady-state profiles with increasing kurtosis at higher Delta pK values. Across neutrality, all the peaks are symmetric irrespective of their Delta pK values, but they show very high contribution to the conductivity of the background gel and significant alteration of the local buffering capacity. The problems of skewness, due to the exponential conductivity profiles at low and high pHs, and of gel burning due to a strong electroosmotic flow generated by the net charges in the gel matrix, also at low and high pHs, are solved by incorporating in the IPG gel a strong viscosity gradient. This is generated by a gradient of linear polyacrylamide which is trapped in the gel by the polymerization process.

Experimental validation of neutron activation simulation of a varian medical linear accelerator.

Science.gov (United States)

Morato, S; Juste, B; Miro, R; Verdu, G; Diez, S

2016-08-01

This work presents a Monte Carlo simulation using the last version of MCNP, v. 6.1.1, of a Varian CLinAc emitting a 15MeV photon beam. The main objective of the work is to estimate the photoneutron production and activated products inside the medical linear accelerator head. To that, the Varian LinAc head was modelled in detail using the manufacturer information, and the model was generated with a CAD software and exported as a mesh to be included in the particle transport simulation. The model includes the transport of photoneutrons generated by primary photons and the (n, γ) reactions which can result in activation products. The validation of this study was done using experimental measures. Activation products have been identified by in situ gamma spectroscopy placed at the jaws exit of the LinAc shortly after termination of a high energy photon beam irradiation. Comparison between experimental and simulation results shows good agreement.

Measuring and predicting Delta(vap)H298 values of ionic liquids.

Science.gov (United States)

Deyko, Alexey; Lovelock, Kevin R J; Corfield, Jo-Anne; Taylor, Alasdair W; Gooden, Peter N; Villar-Garcia, Ignacio J; Licence, Peter; Jones, Robert G; Krasovskiy, Vladimir G; Chernikova, Elena A; Kustov, Leonid M

2009-10-14

We report the enthalpies of vaporisation (measured using temperature programmed desorption by mass spectrometry) of twelve ionic liquids (ILs), covering four imidazolium, [C(m)C(n)Im]+, five pyrrolidinium, [C(n)C(m)Pyrr]+, two pyridinium, [C(n)Py]+, and a dication, [C3(C1Im)2]2+ based IL. These cations were paired with a range of anions: [BF4]-, [FeCl4]-, [N(CN)2]-, [PF3(C2F5)3]- ([FAP]-), [(CF3SO2)2N]- ([Tf2N]-) and [SCN]-. Using these results, plus those for a further eight imidazolium based ILs published earlier (which include the anions [CF3SO3]- ([TfO]-), [PF6]- and [EtSO4]-), we show that the enthalpies of vaporisation can be decomposed into three components. The first component is the Coulombic interaction between the ions, DeltaU(Cou,R), which is a function of the IL molar volume, V(m), and a parameter R(r) which quantifies the relative change in anion-cation distance on evaporation from the liquid phase to the ion pair in the gas phase. The second and third components are the van der Waals contributions from the anion, DeltaH(vdw,A), and the cation, DeltaH(vdw,C). We derive a universal value for R(r), and individual values of DeltaH(vdw,A) and DeltaH(vdw,C) for each of the anions and cations considered in this study. Given the molar volume, it is possible to estimate the enthalpies of vaporisation of ILs composed of any combination of the ions considered here; values for fourteen ILs which have not yet been studied experimentally are given.

Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

Directory of Open Access Journals (Sweden)

J. H. Nienhuis

2017-09-01

Full Text Available The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal dynamics or allogenic (external forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

Delta Morphodynamics Matters! Ecosystem Services, Poverty and Morphodynamic Change in the Ganges-Brahmaputra Mega-Delta

Science.gov (United States)

Nicholls, R. J.; Adger, N.; Allan, A.; Darby, S. E.; Hutton, C.; Matthews, Z.; Rahman, M.; Whitehead, P. G.; Wolf, J.

2013-12-01

The world's deltas are probably the most vulnerable type of coastal environment, and they face multiple stresses in the coming decades. These stresses include, amongst others, local drivers due to land subsidence, population growth and urbanisation within the deltas, regional drivers due to changes in catchment management (e.g. upstream land use and dam construction), as well as global climate change impacts such as sea-level rise. At the same time, the ecosystem services of river deltas support high population densities, with around 14% of the global population inhabiting deltas. A large proportion of these people experience extremes of poverty and they are therefore severely exposed to vulnerability from environmental and ecological stress and degradation. In areas close to or below the poverty boundary, both subsistence and cash elements of the economy tend to rely disproportionately heavily on ecosystem services which underpin livelihoods. Therefore, to sustainably manage delta environments they must be viewed as complex social-environmental systems where change is only partially driven by physical drivers such as sea level rise and climate change, and human-induced development activities are also critical. Here we outline a new conceptual framework for the development of methods to understand and characterise the key drivers of change in ecosystem services that affect the environment and economic status of populous deltas, focusing specifically on the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The GBM delta is characterised by densely populated coastal lowlands with significant poverty, with livelihoods supported to a large extent by natural ecosystems such as the Sunderbahns (the largest mangrove forest in the world). However, the GBM delta is under severe development pressure due to many growing cities. At present the importance of ecosystems services to poverty and livelihoods is poorly understood. This is due to due to the complexity of interactions

Chiral model for nucleon and delta

International Nuclear Information System (INIS)

Birse, M.C.; Banerjee, M.K.

1985-01-01

We propose a model of the nucleon and delta based on the idea that strong QCD forces on length scales approx.0.2--1 fm result in hidden chiral SU(2) x SU(2) symmetry and that there is a separation of roles between these forces which are also responsible for binding quarks in hadrons and the forces which produce absolute confinement. This leads us to study a linear sigma model describing the interactions of quarks, sigma mesons, and pions. We have solved this model in the semiclassical (mean-field) approximation for the hedgehog baryon state. We refer to this solution as a chiral soliton. In the semiclassical approximation the hedgehog state is a linear combination of N and Δ. We project this state onto states of good spin and isospin to calculate matrix elements of various operators in these states. Our results are in reasonable agreement with the observed properties of the nucleon. The mesonic contributions to g/sub A/ and sigma(πN) are about two to three times too large, suggesting the need for quantum corrections

Delta-Beta Thalassaemia in a Pathan Family.

Science.gov (United States)

Ahmad, Saqib Qayyum; Zafar, Saerah Iffat; Malik, Hamid Saeed; Ahmed, Suhaib

2017-11-01

Delta-beta-thalassaemia (δβ-thalassaemia) is a rare type of thalassaemia which mostly results from deletion of δ and β genes with preservation of γ genes. δβ-thalassaemia is classified into (δβ)+ and (δβ)0 types. The (δβ)0-thalassemia is further divided into GγAγ(δβ)0-thalassaemia and Gγ(Aγδβ)0-thalassaemia. In heterozygous state, (δβ)0mutations give rise to phenotype resembling β-thalassaemia trait but with raised Hb-F, ranging from 5 to 20%, without a rise in Hb-A2. In homozygotes, the clinical picture is usually that of thalassaemia intermedia and the patients have 100% Hb-F. Workup of a 1-year child suffering from pallor, chronic ill health, and splenomegaly referred to our laboratory with the suspicion of β-thalassaemia, ultimately resulted in a diagnosis on polymerase chain reaction as having homozygous inversion/deletion Gγ(Aγδβ)0-thalassaemia. Her family members were also investigated.

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

Energy Technology Data Exchange (ETDEWEB)

Yao, De-Liang [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Siemens, D. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Bernard, V. [Groupe de Physique Théorique, Institut de Physique Nucléaire, UMR 8606,CNRS, University Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex (France); Epelbaum, E. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Gasparyan, A.M. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); SSC RF ITEP, Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Gegelia, J. [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Tbilisi State University, 0186 Tbilisi (Georgia); Krebs, H. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Meißner, Ulf-G. [Helmholtz Institut für Strahlen- und Kernphysik andBethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-05-05

We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S- and P-partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.

Bathymetric survey and digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California

Science.gov (United States)

Snyder, Alexander G.; Lacy, Jessica R.; Stevens, Andrew W.; Carlson, Emily M.

2016-06-10

The U.S. Geological Survey conducted a bathymetric survey in Little Holland Tract, a flooded agricultural tract, in the northern Sacramento-San Joaquin Delta (the “Delta”) during the summer of 2015. The new bathymetric data were combined with existing data to generate a digital elevation model (DEM) at 1-meter resolution. Little Holland Tract (LHT) was historically diked off for agricultural uses and has been tidally inundated since an accidental levee breach in 1983. Shallow tidal regions such as LHT have the potential to improve habitat quality in the Delta. The DEM of LHT was developed to support ongoing studies of habitat quality in the area and to provide a baseline for evaluating future geomorphic change. The new data comprise 138,407 linear meters of real-time-kinematic (RTK) Global Positioning System (GPS) elevation data, including both bathymetric data collected from personal watercraft and topographic elevations collected on foot at low tide. A benchmark (LHT15_b1) was established for geodetic control of the survey. Data quality was evaluated both by comparing results among surveying platforms, which showed systematic offsets of 1.6 centimeters (cm) or less, and by error propagation, which yielded a mean vertical uncertainty of 6.7 cm. Based on the DEM and time-series measurements of water depth, the mean tidal prism of LHT was determined to be 2,826,000 cubic meters. The bathymetric data and DEM are available at http://dx.doi.org/10.5066/F7RX9954. 

Pleiotropy analysis of quantitative traits at gene level by multivariate functional linear models.

Science.gov (United States)

Wang, Yifan; Liu, Aiyi; Mills, James L; Boehnke, Michael; Wilson, Alexander F; Bailey-Wilson, Joan E; Xiong, Momiao; Wu, Colin O; Fan, Ruzong

2015-05-01

In genetics, pleiotropy describes the genetic effect of a single gene on multiple phenotypic traits. A common approach is to analyze the phenotypic traits separately using univariate analyses and combine the test results through multiple comparisons. This approach may lead to low power. Multivariate functional linear models are developed to connect genetic variant data to multiple quantitative traits adjusting for covariates for a unified analysis. Three types of approximate F-distribution tests based on Pillai-Bartlett trace, Hotelling-Lawley trace, and Wilks's Lambda are introduced to test for association between multiple quantitative traits and multiple genetic variants in one genetic region. The approximate F-distribution tests provide much more significant results than those of F-tests of univariate analysis and optimal sequence kernel association test (SKAT-O). Extensive simulations were performed to evaluate the false positive rates and power performance of the proposed models and tests. We show that the approximate F-distribution tests control the type I error rates very well. Overall, simultaneous analysis of multiple traits can increase power performance compared to an individual test of each trait. The proposed methods were applied to analyze (1) four lipid traits in eight European cohorts, and (2) three biochemical traits in the Trinity Students Study. The approximate F-distribution tests provide much more significant results than those of F-tests of univariate analysis and SKAT-O for the three biochemical traits. The approximate F-distribution tests of the proposed functional linear models are more sensitive than those of the traditional multivariate linear models that in turn are more sensitive than SKAT-O in the univariate case. The analysis of the four lipid traits and the three biochemical traits detects more association than SKAT-O in the univariate case. © 2015 WILEY PERIODICALS, INC.

Dinâmica não-linear e exercício físico: conceitos e aplicações Non-linear dynamics and physical exercise: concepts and applications

Directory of Open Access Journals (Sweden)

Antônio Pakenas

2007-10-01

Full Text Available Médicos, fisiologistas, bioquímicos, psicólogos e até profissionais envolvidos com exercício físico estão recentemente aumentando seus interesses pela dinâmica não-linear, uma teoria científica desenvolvida principalmente por matemáticos, que é genericamente conhecida por Teoria da Complexidade. Embora poucos trabalhos em Educação Física e Esporte utilizem esse paradigma para solucionar seus problemas, nota-se um crescente interesse por esse mesmo enfoque, principalmente em relação aos efeitos do exercício físico sobre mudanças na variabilidade e complexidade de séries temporais fisiológicas. Geralmente, tais mudanças se revelam na forma de queda em seu comportamento temporal, denotando diminuição na complexidade do organismo ou de componentes envolvidos especificamente na sua regulação. De acordo com a Teoria da Complexidade, por enfatizar interações não-lineares existentes em sistemas biológicos, verifica-se que não é importante apenas a elevação (supercompensação de componentes do organismo com a prática de exercícios físicos, mas também aqueles que atrofiam (descompensação paralelamente, porque podem contribuir para a ocorrência de perda de sincronia na funcionalidade desses sistemas. Assim, em oposição à ênfase que se dá no treinamento físico à repetição monótona de atividade física intensa e voltada para efeitos específicos positivos, que invariavelmente leva à simplificação do organismo, recomenda-se maior variação qualitativa e quantitativa nos exercícios praticados. O objetivo é preservar sua complexidade natural ou impedir que ocorra diminuição rápida com o envelhecimento. A presente revisão tem por objetivo, além de descrever a possível perda de complexidade com o treinamento físico, discutir alguns conceitos da Teoria da Complexidade de modo introdutório, com particular ênfase em tópicos envolvendo saúde e desempenho físico.Physicians, physiologists

Plasma simulation of electron avalanche in a linear thyratron

International Nuclear Information System (INIS)

Kushner, M.J.

1985-01-01

Thyratrons typically operate at sufficiently small PD (pressure x electrode separation) that holdoff is obtained by operating on the near side of the Paschen curve, and by shielding the slot in the control grid so there is no straight line path for electrons to reach the anode from the cathode. Electron avalanche is initiated by pulsing the control grid to a high voltage. Upon collapse of voltage in the cathode-control grid space, the discharge is sustained by penetration of potential through the control grid slot into the cathode-control grid region. To better understand the electron avalanche process in multi-grid and slotted structures such as thyratrons, a plasma simulation code has been constructed. This effort is in support of a companion program in which a linear thyratron is being electrically and spectroscopically characterized

Stimulation of a turbofan engine for evaluation of multivariable optimal control concepts. [(computerized simulation)

Science.gov (United States)

Seldner, K.

1976-01-01

The development of control systems for jet engines requires a real-time computer simulation. The simulation provides an effective tool for evaluating control concepts and problem areas prior to actual engine testing. The development and use of a real-time simulation of the Pratt and Whitney F100-PW100 turbofan engine is described. The simulation was used in a multi-variable optimal controls research program using linear quadratic regulator theory. The simulation is used to generate linear engine models at selected operating points and evaluate the control algorithm. To reduce the complexity of the design, it is desirable to reduce the order of the linear model. A technique to reduce the order of the model; is discussed. Selected results between high and low order models are compared. The LQR control algorithms can be programmed on digital computer. This computer will control the engine simulation over the desired flight envelope.

Enhanced vortex pinning and critical current density in proton-irradiated YBa2Cu3O(7-delta) thin films

Science.gov (United States)

Venturini, E. L.; Siegal, M. P.; White, A. E.; Hou, S. Y.; Phillips, J. M.

1992-11-01

The appropriate fluence of 2.0 MeV H(sup +) ions has been shown previously to enhance the critical current density J(sub c) by a factor of two at a magnetic field of 0.9 tesla in 1000 (Angstrom) thick epitaxial films of YBa(2)Cu(3)O(7-delta) grown by the ex situ BaF2 process. The as-grown films exhibit single crystal-like behavior in both atomic ordering and J(sub c) versus temperature and magnetic field. TRIM simulations suggest that H(sup +) irradiation generates mainly point defects throughout the crystal structure. We show here that such defects produce both a large enhancement of J(sub c) for fields above 1 tesla and a significant increase in the apparent vortex pinning potential deduced from magnetization relaxation data.

Future Change to Tide-Influenced Deltas

Science.gov (United States)

Nienhuis, Jaap H.; Hoitink, A. J. F. (Ton); Törnqvist, Torbjörn E.

2018-04-01

Tides tend to widen deltaic channels and shape delta morphology. Here we present a predictive approach to assess a priori the effect of fluvial discharge and tides on deltaic channels. We show that downstream channel widening can be quantified by the ratio of the tide-driven discharge and the fluvial discharge, along with a second metric representing flow velocities. A test of our new theory on a selection of 72 deltas globally shows good correspondence to a wide range of environments, including wave-dominated deltas, river-dominated deltas, and alluvial estuaries. By quantitatively relating tides and fluvial discharge to delta morphology, we offer a first-order prediction of deltaic change that may be expected from altered delta hydrology. For example, we expect that reduced fluvial discharge in response to dam construction will lead to increased tidal intrusion followed by enhanced tide-driven sediment import into deltas, with implications for navigation and other human needs.

Numerical simulation of linear fiction welding (LFW) processes

Science.gov (United States)

Fratini, L.; La Spisa, D.

2011-05-01

Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining "unweldable" materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries. LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. This paper is a comparative test between the numerical model in two dimensions, i.e. in plane strain conditions, and in three dimensions of a LFW process of AISI1045 steel specimens. It must be observed that the 3D model assures a faithful simulation of the actual threedimensional material flow, even if the two-dimensional simulation computational times are very short, a few hours instead of several ones as the 3D model. The obtained results were compared with experimental values found out in the scientific literature.

Numerical simulation of linear fiction welding (LFW) processes

International Nuclear Information System (INIS)

Fratini, L.; La Spisa, D.

2011-01-01

Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining ''unweldable'' materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries.LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. This paper is a comparative test between the numerical model in two dimensions, i.e. in plane strain conditions, and in three dimensions of a LFW process of AISI1045 steel specimens. It must be observed that the 3D model assures a faithful simulation of the actual threedimensional material flow, even if the two-dimensional simulation computational times are very short, a few hours instead of several ones as the 3D model. The obtained results were compared with experimental values found out in the scientific literature.

Catalytic strategies of the hepatitis delta virus ribozyme as probed by molecular dynamics simulations

Czech Academy of Sciences Publication Activity Database

Krasovská, Maryna V.; Sefcikova, J.; Špačková, Naďa; Šponer, Jiří; Walter, N. G.

2005-01-01

Roč. 22, č. 6 (2005), s. 774 ISSN 0739-1102. [Albany 2005. Conversation /14./. 14.06.2005-18.06.2005, Albany] Institutional research plan: CEZ:AV0Z50040507 Keywords : catalytic strategies * hepatitis delta virus Subject RIV: BO - Biophysics

From Natural to Design River Deltas

Science.gov (United States)

Giosan, Liviu

2016-04-01

Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

Delta isobars in neutron stars

Directory of Open Access Journals (Sweden)

Pagliara Giuseppe

2015-01-01

Full Text Available The appearance of delta isobars in beta-stable matter is regulated by the behavior of the symmetry energy at densities larger than saturation density. We show that by taking into account recent constraints on the density derivative of the symmetry energy and the theoretical and experimental results on the excitations of delta isobars in nuclei, delta isobars are necessary ingredients for the equations of state used for studying neutron stars. We analyze the effect of the appearance of deltas on the structure of neutron stars: as in the case of hyperons, matter containing delta is too soft for allowing the existence of 2M⊙ neutron stars. Quark stars on the other hand, could reach very massive configurations and they could form from a process of conversion of hadronic stars in which an initial seed of strangeness appears through hyperons.

Simulation of the Impacts of Urbanization on Winter Meteorological Fields over the Pearl River Delta Region

Directory of Open Access Journals (Sweden)

Naixing Luo

2017-01-01

Full Text Available The influences of urbanization on weather in Guangdong Province, China, were studied using the Weather Research and Forecasting model from 31 December 2009 through 3 January 2010. Model outputs were compared with extensive monitoring of meteorological data to examine the simulation ability. Model results between tests (with and without land-use change show that the urbanization had major effects on meteorological fields across nearly the entire Pearl River Delta region and particularly in urban areas. Studied fields (wind speed, temperature, precipitation, and sensible and latent heat fluxes were affected by the urbanization of the PRD region. The major influences occurred in urban areas, where wind speeds decreased greatly, while the daytime surface upward sensible heat flux clearly increased. Unlike the sensible heat flux, the latent heat flux had a nonmonotonic increase or decrease. As a consequence of the two heat fluxes, 2-m temperature varied with location and time. Change of precipitation was complex. The main rain band became more concentrated, while precipitation decreased upwind of the urban area and increased downwind.

D2 Delta Robot Structural Design and Kinematics Analysis

Science.gov (United States)

Yang, Xudong; wang, Song; Dong, Yu; Yang, Hai

2017-12-01

In this paper, a new type of Delta robot with only two degrees of freedom is proposed on the basis of multi - degree - of - freedom delta robot. In order to meet our application requirements, we have carried out structural design and analysis of the robot. Through SolidWorks modeling, combined with 3D printing technology to determine the final robot structure. In order to achieve the precise control of the robot, the kinematics analysis of the robot was carried out. The SimMechanics toolbox of MATLAB is used to establish the mechanism model, and the kinematics mathematical model is used to simulate the robot motion control in Matlab environment. Finally, according to the design mechanism, the working space of the robot is drawn by the graphic method, which lays the foundation for the motion control of the subsequent robot.

Simulation model of the F/A-18 high angle-of-attack research vehicle utilized for the design of advanced control laws

Science.gov (United States)

Strickland, Mark E.; Bundick, W. Thomas; Messina, Michael D.; Hoffler, Keith D.; Carzoo, Susan W.; Yeager, Jessie C.; Beissner, Fred L., Jr.

1996-01-01

The 'f18harv' six degree-of-freedom nonlinear batch simulation used to support research in advanced control laws and flight dynamics issues as part of NASA's High Alpha Technology Program is described in this report. This simulation models an F/A-18 airplane modified to incorporate a multi-axis thrust-vectoring system for augmented pitch and yaw control power and actuated forebody strakes for enhanced aerodynamic yaw control power. The modified configuration is known as the High Alpha Research Vehicle (HARV). The 'f18harv' simulation was an outgrowth of the 'f18bas' simulation which modeled the basic F/A-18 with a preliminary version of a thrust-vectoring system designed for the HARV. The preliminary version consisted of two thrust-vectoring vanes per engine nozzle compared with the three vanes per engine actually employed on the F/A-18 HARV. The modeled flight envelope is extensive in that the aerodynamic database covers an angle-of-attack range of -10 degrees to +90 degrees, sideslip range of -20 degrees to +20 degrees, a Mach Number range between 0.0 and 2.0, and an altitude range between 0 and 60,000 feet.

A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator

DEFF Research Database (Denmark)

Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre

The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub-threshol......The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub...

Dynamical systems and linear algebra

OpenAIRE

Colonius, Fritz (Prof.)

2007-01-01

Dynamical systems and linear algebra / F. Colonius, W. Kliemann. - In: Handbook of linear algebra / ed. by Leslie Hogben. - Boca Raton : Chapman & Hall/CRC, 2007. - S. 56,1-56,22. - (Discrete mathematics and its applications)

Delta-tilde interpretation of standard linear mixed model results

DEFF Research Database (Denmark)

Brockhoff, Per Bruun; Amorim, Isabel de Sousa; Kuznetsova, Alexandra

2016-01-01

effects relative to the residual error and to choose the proper effect size measure. For multi-attribute bar plots of F-statistics this amounts, in balanced settings, to a simple transformation of the bar heights to get them transformed into depicting what can be seen as approximately the average pairwise...... data set and compared to actual d-prime calculations based on Thurstonian regression modeling through the ordinal package. For more challenging cases we offer a generic "plug-in" implementation of a version of the method as part of the R-package SensMixed. We discuss and clarify the bias mechanisms...

Convex Relaxation of OPF in Multiphase Radial Networks with Wye and Delta Connections

Energy Technology Data Exchange (ETDEWEB)

Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Low, Steven [California Institute of Technology

2017-08-01

This panel presentation focuses on multiphase radial distribution networks with wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power flow models are developed to facilitate the integration of delta-connected loads or generation resources in the OPF problem. The first model is referred to as the extended branch flow model (EBFM). The second model leverages a linear relationship between phase-to-ground power injections and delta connections that holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that the proposed SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidence also indicates that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is further shown that the SDP solution under BVA has a small optimality gap, and the BVA model is accurate in the sense that it reproduces actual system voltages.

Solution of the linear transport equation, monoenergetic in multiregions with anisotopic scattering by the method F sub(N)

International Nuclear Information System (INIS)

Pontedeiro, E.M.B.D.; Maiorino, J.R.

1982-01-01

The linear equation transport, monoenergetic, with anysotropic scattering, in multiregions, by F sub(N) method, is resolved. The mathematical analysis used for this method consists in to use parcially the expansion method in singular autofunctions, or Case's method, aiming to derive a set of integral equations coupled to the angular distribution in the boundaries and interfaces, and then to approximate these distributions by polynomics of N order, aiming to derive, with the use of these boundary and continuity conditions in the interfaces, a set of algebric equations for the coef. of polynomical approximation. With the goal to obtain numerical results, a computer code (FNAM-1) with options for the number of regions, boundary conditions, F sub(N) approx order, were developed. Numerical results were then obtained for various sample problems and compared with the results published in the literature with the objective to demonstrate the precision and applicability of the F sub(N) method. (E.G.) [pt

Improved γ-linolenic acid production in Mucor circinelloides by homologous overexpressing of delta-12 and delta-6 desaturases.

Science.gov (United States)

Zhang, Yao; Luan, Xiao; Zhang, Huaiyuan; Garre, Victoriano; Song, Yuanda; Ratledge, Colin

2017-06-21

γ-Linolenic acid (GLA) is important because of its nutritional value and medicinal applications. Although the biosynthetic pathways of some plant and microbial GLA have been deciphered, current understanding of the correlation between desaturases and GLA synthesis in oleaginous fungi is incomplete. In previous work, we found that a large amount of oleic acid (OA) had not been converted to linoleic acid (LA) or GLA in Mucor circinelloides CBS 277.49, which may be due to inadequate activities of the delta-12 or delta-6 desaturases, and thus leading to the accumulation of OA and LA. Thus, it is necessary to explore the main contributing factor during the process of GLA biosynthesis in M. circinelloides. To enhance GLA production in M. circinelloides, homologous overexpression of delta-12 and two delta-6 desaturases (named delta-6-1 and delta-6-2, respectively) were analyzed. When delta-6 desaturase were overexpressed in M. circinelloides, up to 43% GLA was produced in the total fatty acids, and the yield of GLA reached 180 mg/l, which were, respectively, 38 and 33% higher than the control strain. These findings revealed that delta-6 desaturase (especially for delta-6-1 desaturase) plays an important role in GLA synthesis by M. circinelloides. The strain overexpressing delta-6-1 desaturase may have potential application in microbial GLA production.

Frontal EEG delta/alpha ratio and screening for post-stroke cognitive deficits: the power of four electrodes.

Science.gov (United States)

Schleiger, Emma; Sheikh, Nabeel; Rowland, Tennille; Wong, Andrew; Read, Stephen; Finnigan, Simon

2014-10-01

This study analysed correlations between post-stroke, quantitative electroencephalographic (QEEG) indices, and cognition-specific, functional outcome measures. Results were compared between QEEG indices calculated from the standard 19 versus 4 frontal (or 4 posterior) electrodes to assess the feasibility and efficacy of employing a reduced electrode montage. Resting-state EEG was recorded at the bedside within 62-101 h after onset of symptoms of middle cerebral artery, ischaemic stroke (confirmed radiologically). Relative power for delta, theta, alpha and beta, delta/alpha ratio (DAR) and pairwise-derived brain symmetry index (pdBSI) were averaged; over all electrodes (global), over F3, F4, F7, F8 (frontal) and P3, P4, T5, T6 (posterior). The functional independence measure and functional assessment measure (FIM-FAM) was administered at mean 105 days post-stroke. Total (30 items) and cognition-specific (5 items) FIM-FAM scores were correlated with QEEG indices using Spearman's coefficient, with a Bonferroni correction. Twenty-five patients were recruited, 4 died within 3 months and 1 was lost to follow-up. Hence 20 cases (10 female; 9 left hemisphere; mean age 68 years, range 38-84) were analysed. Two QEEG indices demonstrated highly-significant correlations with cognitive outcomes: frontal DAR (ρ = -0.664, p ≤ 0.001) and global, relative alpha power (ρ = 0.67, p ≤ 0.001). After correction there were no other significant correlations. Alpha activity - particularly frontally - may index post-stroke attentional capacity, which appears to be a key determinant of functional and cognitive outcomes. Likewise frontal delta pathophysiology influences such outcomes. Pending further studies, DAR from 4 frontal electrodes may inform early screening for post-MCA stroke cognitive deficits, and thereby, clinical decisions. Copyright © 2014 Elsevier B.V. All rights reserved.

PROPERTIES OF INTERSTELLAR TURBULENCE FROM GRADIENTS OF LINEAR POLARIZATION MAPS

International Nuclear Information System (INIS)

Burkhart, Blakesley; Lazarian, A.; Gaensler, B. M.

2012-01-01

Faraday rotation of linearly polarized radio signals provides a very sensitive probe of fluctuations in the interstellar magnetic field and ionized gas density resulting from magnetohydrodynamic (MHD) turbulence. We used a set of statistical tools to analyze images of the spatial gradient of linearly polarized radio emission (|∇P|) for both observational data from a test image of the Southern Galactic Plane Survey (SGPS) and isothermal three-dimensional simulations of MHD turbulence. Visually, in both observations and simulations, a complex network of filamentary structures is seen. Our analysis shows that the filaments in |∇P| can be produced both by interacting shocks and random fluctuations characterizing the non-differentiable field of MHD turbulence. The latter dominates for subsonic turbulence, while the former is only present in supersonic turbulence. We show that supersonic and subsonic turbulence exhibit different distributions as well as different morphologies in the maps of |∇P|. Particularly, filaments produced by shocks show a characteristic 'double jump' profile at the sites of shock fronts resulting from delta function-like increases in the density and/or magnetic field, while those produced by subsonic turbulence show a single jump profile. In order to quantitatively characterize these differences, we use the topology tool known as the genus curve as well as the probability distribution function moments of the image distribution. We find that higher values for the moments correspond to cases of |∇P| with larger sonic Mach numbers. The genus analysis of the supersonic simulations of |∇P| reveals a 'swiss cheese' topology, while the subsonic cases have characteristics of a 'clump' topology. Based on the analysis of the genus and the higher order moments, the SGPS test region data have a distribution and morphology that match subsonic- to transonic-type turbulence, which confirms what is now expected for the warm ionized medium.

PROPERTIES OF INTERSTELLAR TURBULENCE FROM GRADIENTS OF LINEAR POLARIZATION MAPS

Energy Technology Data Exchange (ETDEWEB)

Burkhart, Blakesley; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, 475 N. Charter St., WI 53711 (United States); Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

2012-04-20

Faraday rotation of linearly polarized radio signals provides a very sensitive probe of fluctuations in the interstellar magnetic field and ionized gas density resulting from magnetohydrodynamic (MHD) turbulence. We used a set of statistical tools to analyze images of the spatial gradient of linearly polarized radio emission (|{nabla}P|) for both observational data from a test image of the Southern Galactic Plane Survey (SGPS) and isothermal three-dimensional simulations of MHD turbulence. Visually, in both observations and simulations, a complex network of filamentary structures is seen. Our analysis shows that the filaments in |{nabla}P| can be produced both by interacting shocks and random fluctuations characterizing the non-differentiable field of MHD turbulence. The latter dominates for subsonic turbulence, while the former is only present in supersonic turbulence. We show that supersonic and subsonic turbulence exhibit different distributions as well as different morphologies in the maps of |{nabla}P|. Particularly, filaments produced by shocks show a characteristic 'double jump' profile at the sites of shock fronts resulting from delta function-like increases in the density and/or magnetic field, while those produced by subsonic turbulence show a single jump profile. In order to quantitatively characterize these differences, we use the topology tool known as the genus curve as well as the probability distribution function moments of the image distribution. We find that higher values for the moments correspond to cases of |{nabla}P| with larger sonic Mach numbers. The genus analysis of the supersonic simulations of |{nabla}P| reveals a 'swiss cheese' topology, while the subsonic cases have characteristics of a 'clump' topology. Based on the analysis of the genus and the higher order moments, the SGPS test region data have a distribution and morphology that match subsonic- to transonic-type turbulence, which confirms what is now

Combined Simulation of a Micro Permanent Magnetic Linear Contactless Displacement Sensor

Directory of Open Access Journals (Sweden)

Jing Gao

2010-09-01

Full Text Available The permanent magnetic linear contactless displacement (PLCD sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS measurements is designed and simulated with the CST EM STUDIO® software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth.

Dynamical simulation of a linear sigma model near the critical point

Energy Technology Data Exchange (ETDEWEB)

Wesp, Christian; Meistrenko, Alex; Greiner, Carsten [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt, Max-von-Laue-Strasse 1, D-60438 Frankfurt (Germany); Hees, Hendrik van [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt (Germany)

2014-07-01

The intention of this study is the search for signatures of the chiral phase transition. To investigate the impact of fluctuations, e.g. of the baryon number, on the transition or a critical point, the linear sigma model is treated in a dynamical 3+1D numerical simulation. Chiral fields are approximated as classical fields, quarks are described by quasi particles in a Vlasov equation. Additional dynamic is implemented by quark-quark and quark-sigma-field interaction. For a consistent description of field-particle interactions, a new Monte-Carlo-Langevin-like formalism has been developed and is discussed.

The evolution of a subaqueous delta in the Anthropocene: A stratigraphic investigation of the Brazos River delta, TX USA

Science.gov (United States)

Carlin, Joseph A.; Dellapenna, Timothy M.

2015-12-01

Globally, deltas are increasingly threatened by anthropogenic activities. As a result, deltas now evolve through the combined effects of natural and human-induced processes occurring throughout the fluvial-deltaic system. The Brazos River delta, located along the Texas coast in the northwestern Gulf of Mexico, and its watershed have been impacted by direct and indirect human activities since the late 19th century. This provides an opportunity to investigate how such alterations have shaped the evolution of a delta in the Anthropocene, a time when humans are drivers of geological change. Historic alteration to the delta and watershed include extensive agricultural activity, jetty construction at the mouth in the late 1890s, mouth diversion ~10 km to the southwest in 1929, and reservoir construction throughout the early and mid 20th Century. Three subaerial deltaic geometries provided the framework to connect subaerial deltaic responses, to the anthropogenic alterations, to the resulting stratigraphic characteristics observed in the subaqueous delta. This study utilized high-resolution geophysical data (swath bathymetry, side scan sonar, CHIRP subbottom profiling) on the subaqueous delta to investigate the subaqueous delta stratigraphy and infer the processes that shaped the deltaic record over time. The results showed distinct areas across the subaqueous delta that were dominated by erosion and deposition. Erosional areas corresponded to earlier growth phase depocenters being exposed at the surface, while the depositional areas corresponded to areas with the most recent growth phase depocenter overlying the earlier depocenters. These results highlight that the subaqueous depocenter has migrated westward over time, consistent with the observed changes to the subaerial delta. Additionally, the data showed that evidence for these past growth phases and depocenters may be preserved within the subaqueous delta, even after subaerial portions of the delta returned to pre

Cross-verification of the GENE and XGC codes in preparation for their coupling

Science.gov (United States)

Jenko, Frank; Merlo, Gabriele; Bhattacharjee, Amitava; Chang, Cs; Dominski, Julien; Ku, Seunghoe; Parker, Scott; Lanti, Emmanuel

2017-10-01

A high-fidelity Whole Device Model (WDM) of a magnetically confined plasma is a crucial tool for planning and optimizing the design of future fusion reactors, including ITER. Aiming at building such a tool, in the framework of the Exascale Computing Project (ECP) the two existing gyrokinetic codes GENE (Eulerian delta-f) and XGC (PIC full-f) will be coupled, thus enabling to carry out first principle kinetic WDM simulations. In preparation for this ultimate goal, a benchmark between the two codes is carried out looking at ITG modes in the adiabatic electron limit. This verification exercise is also joined by the global Lagrangian PIC code ORB5. Linear and nonlinear comparisons have been carried out, neglecting for simplicity collisions and sources. A very good agreement is recovered on frequency, growth rate and mode structure of linear modes. A similarly excellent agreement is also observed comparing the evolution of the heat flux and of the background temperature profile during nonlinear simulations. Work supported by the US DOE under the Exascale Computing Project (17-SC-20-SC).

Simulation of tungsten armour cracking due to small ELMs in ITER

Energy Technology Data Exchange (ETDEWEB)

Pestchanyi, S., E-mail: sergey.pestchanyi@ihm.fzk.de [Forschungszentrum Karlsruhe, IHM (Germany); Garkusha, I. [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Landman, I. [Forschungszentrum Karlsruhe, IHM (Germany)

2010-12-15

Simulations of tungsten armour cracking under small ELM-like plasma heat load, which does not cause surface melting, have been performed using the PEGASUS-3D code. A dedicated series of experiments have been performed in the QSPA-Kh50 facility for measurements of the unknown tungsten thermophysical properties and for verification of the PEGASUS-3D simulation results. The simulations revealed that a cellular crack network with average mesh size {Lambda} {approx} 0.5 mm formed after first ELMs and the pattern does not change further. With increasing number of repetitive ELMs loads, the average crack width {Delta}(n) has a maximum value {Delta}{sub m}. The ratio of {Delta}{sub m}/{Lambda} is equal to the tungsten thermal expansion at the maximum surface temperature. {Delta}(n) tends to this value exponentially. The number of ELMs n{sub m} needed for {Delta} stabilization depends on the ELMs energy density and time duration, n{sub m} {approx} 300 for the simulated ELMs of 0.45 MJ/m{sup 2} and 0.25 ms duration. The PEGASUS-3D code is prepared for simulations of tungsten armour damage under action of ELMs of various energy deposition and time duration. These parameters of ELMs depend on ITER regimes of operation and on how successful will be the efforts on ELMs mitigation.

Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity.

Science.gov (United States)

Darby, Stephen E; Hackney, Christopher R; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R; Best, James L; Nicholas, Andrew P; Aalto, Rolf

2016-11-10

The world's rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being 'drowned' by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world's great deltas. We demonstrate that spatial variations in the Mekong's suspended sediment load are correlated (r = 0.765, P sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world's major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

Relationship between symmetry of porphyrinic pi-conjugated systems and singlet oxygen (1Delta g) yields: low-symmetry tetraazaporphyrin derivatives.

Science.gov (United States)

Ishii, Kazuyuki; Itoya, Hatsumi; Miwa, Hideya; Fujitsuka, Mamoru; Ito, Osamu; Kobayashi, Nagao

2005-07-07

We have investigated the excited-state properties and singlet oxygen ((1)Delta(g)) generation mechanism in phthalocyanines (4M; M = H(2), Mg, or Zn) and in low-symmetry metal-free, magnesium, and zinc tetraazaporphyrins (TAPs), that is, monobenzo-substituted (1M), adjacently dibenzo-substituted (2AdM), oppositely dibenzo-substituted (2OpM), and tribenzo-substituted (3M) TAP derivatives, whose pi conjugated systems were altered by fusing benzo rings. The S(1)(x) and S(1)(y) states (these lowest excited singlet states are degenerate in D(4)(h) symmetry) split in the low-symmetry TAP derivatives. The excited-state energies were quantitatively determined from the electronic absorption spectra. The lowest excited triplet (T(1)(x)) energies were also determined from phosphorescence spectra, while the second lowest excited triplet (T(1)(y)) states were evaluated by using the energy splitting between the T(1)(x) and T(1)(y) states previously reported (Miwa, H.; Ishii, K.; Kobayashi, N. Chem. Eur. J. 2004, 10, 4422-4435). The singlet oxygen quantum yields (Phi(Delta)) are strongly dependent on the pi conjugated system. In particular, while the Phi(Delta) value of 2AdH(2) is smallest in our system, that of 2OpH(2), an isomer of 2AdH(2), is larger than that of 4Zn, in contrast to the heavy atom effect. The relationship between the molecular structure and Phi(Delta) values can be transformed into a relationship between the S(1)(x) --> T(1)(y) intersystem crossing rate constant (k(ISC)) and the energy difference between the S(1)(x) and T(1)(y) states (DeltaE(S)(x)(T)(y)). In each of the Zn, Mg, and metal-free compounds, the Phi(Delta)/tau(F) values (tau(F): fluorescence lifetime), which are related to the k(ISC) values, are proportional to exp(-DeltaE(S)(x)(T)(y)), indicating that singlet oxygen ((1)Delta(g)) is produced via the T(1)(y) state and that the S(1)(x) --> T(1)(y) ISC process follows the energy-gap law. From the viewpoint of photodynamic therapy, our methodology

Laguncularia recemosa (L.) Gaertner f. (Family Combretaceae ...

African Journals Online (AJOL)

jen

ABSTRACT: The morphology, phytochemistry, ecology and distribution of Laguncularia racemosa (L.) Gaertner f., (basionym: Conocarpus racemosa L.), in the Niger Delta area was investigated in this study. The data showed that Laguncularia racemosa is a small tree or shrub 30 cm in diameter and about 6 m in height,.

Systematic analysis of spectroscopic characteristics of the lanthanide and actinide ions with the 4f{sup N−1}5d and 5f{sup N−1}6d electronic configurations in a free state

Energy Technology Data Exchange (ETDEWEB)

Ma, C.-G. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Brik, M.G., E-mail: brik@fi.tartu.ee [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Tian, Y.; Li, Q.-X. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China)

2014-08-01

Highlights: • Calculated spectroscopic parameters of f{sup N−1}d configurations of the 4f and 5f ions. • Relations between the Slater parameters, spin–orbit constant, atomic number were found. • Barycenters of the electronic configuration energies were calculated. • Obtained relations reduce the number of independent terms in a free ion Hamiltonian. - Abstract: Systematic consideration of the spectroscopic properties of the f{sup N−1}d excited electronic configurations of the di-, tri- and tetravalent lanthanide and actinide ions in a free state is presented. Variations of the Hartree–Fock calculated Slater parameters for the f{sup N−1}d electron configurations, spin–orbit (SO) interaction constant ζ for the f and d electrons, and averaged values of the second, fourth and sixth powers of the 4f, 5f, 5d, 6d electrons’ radial coordinate across both series were considered; functional dependencies between the mentioned quantities were obtained. It has been shown that the Coulomb interaction parameters F{sup 2}(ff), F{sup 4}(ff), and F{sup 6}(ff) for the f{sup N−1} core increase linearly with the atomic number Z, whereas the direct and exchange Coulomb parameters F{sup 2}(fd), F{sup 4}(fd), G{sup 1}(fd), G{sup 3}(fd), G{sup 5}(fd) for the f{sup N−1}d configuration decrease linearly with Z. Since the SO interaction constant ζ{sup 1/4} is also proportional to Z, it was possible to find linear relationships between the Coulomb interaction parameters and SO constants for the f and d electrons, which effectively reduce the number of independent parameters in the free ion Hamiltonian. The constraining relations between the free ion Hamiltonian’s parameters obtained in the present paper can be used for simulations of the f–d transition spectra of these ions in various crystals.

Head orientation prediction: delta quaternions versus quaternions.

Science.gov (United States)

Himberg, Henry; Motai, Yuichi

2009-12-01

Display lag in simulation environments with helmet-mounted displays causes a loss of immersion that degrades the value of virtual/augmented reality training simulators. Simulators use predictive tracking to compensate for display lag, preparing display updates based on the anticipated head motion. This paper proposes a new method for predicting head orientation using a delta quaternion (DQ)-based extended Kalman filter (EKF) and compares the performance to a quaternion EKF. The proposed framework operates on the change in quaternion between consecutive data frames (the DQ), which avoids the heavy computational burden of the quaternion motion equation. Head velocity is estimated from the DQ by an EKF and then used to predict future head orientation. We have tested the new framework with captured head motion data and compared it with the computationally expensive quaternion filter. Experimental results indicate that the proposed DQ method provides the accuracy of the quaternion method without the heavy computational burden.

deltaPlotR: An R Package for Di?erential Item Functioning Analysis with Ango? s Delta Plot

OpenAIRE

David Magis; Bruno Facon

2014-01-01

Angoff's delta plot is a straightforward and not computationally intensive method to identify differential item functioning (DIF) among dichotomously scored items. This approach was recently improved by proposing an optimal threshold selection and by considering several item purification processes. Moreover, to support practical DIF analyses with the delta plot and these improvements, the R package deltaPlotR was also developed. The purpose of this paper is twofold: to outline the delta plot ...

Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California

Science.gov (United States)

Perry, Russell W.; Romine, Jason G.; Pope, Adam C.; Evans, Scott D.

2018-02-27

bias in Delta Simulation Model 2 (DSM2) flow predictions at the junction of the Sacramento River, DCC, and Georgiana Slough. Because DSM2 was being used to simulate California WaterFix operations, understanding the extent of bias relative to USGS streamgages was important since fish routing models were based on flow data at streamgages. We determined that river flow predicted by DSM2 was biased for Georgiana Slough and the Sacramento River. Therefore, for subsequent analysis, we bias-corrected the DSM2 flow predictions using measured stream flows as predictor variables.In the third analysis, we evaluated the effect of the NDD on the daily probability of fish entering Georgiana Slough and the DCC. We applied an existing model to predict entrainment from 15-minute flow simulations for an 82-year time series of flows simulated by DSM2 under the Proposed Action (PA), where the North Delta Diversion is implemented under California WaterFix, and the No Action Alternative (NAA), where the diversion is not implemented. To estimate the daily fraction of fish entering each river channel, entrainment probabilities were averaged over each day. To evaluate the two scenarios, we then compared mean annual entrainment probabilities by month, water year classification, and three different assumed run timings. Overall, the probability of remaining in the Sacramento River was lower under the PA scenario, but the magnitude of the difference was small (3/s. At flows greater than 41,000 ft3/s, we hypothesize that entrainment into the interior Delta is relatively constant, which would have caused little difference between scenarios at higher flows.

Preface: Introductory Remarks: Linear Scaling Methods

Science.gov (United States)

Bowler, D. R.; Fattebert, J.-L.; Gillan, M. J.; Haynes, P. D.; Skylaris, C.-K.

2008-07-01

problems, there was another important theme: extending functionality. The search for greater accuracy has given an implementation of density functional designed to model van der Waals interactions accurately as well as local correlation, TDDFT and QMC and GW methods which, while not explicitly O(N), take advantage of localisation. All speakers at the workshop were invited to contribute to this issue, but not all were able to do this. Hence it is useful to give a complete list of the talks presented, with the names of the sessions; however, many talks fell within more than one area. This is an exciting time for linear scaling methods, which are already starting to contribute significantly to important scientific problems. Applications to nanostructures and biomolecules A DFT study on the structural stability of Ge 3D nanostructures on Si(001) using CONQUEST Tsuyoshi Miyazaki, D R Bowler, M J Gillan, T Otsuka and T Ohno Large scale electronic structure calculation theory and several applications Takeo Fujiwara and Takeo Hoshi ONETEP:Linear-scaling DFT with plane waves Chris-Kriton Skylaris, Peter D Haynes, Arash A Mostofi, Mike C Payne Maximally-localised Wannier functions as building blocks for large-scale electronic structure calculations Arash A Mostofi and Nicola Marzari A linear scaling three dimensional fragment method for ab initio calculations Lin-Wang Wang, Zhengji Zhao, Juan Meza Peta-scalable reactive Molecular dynamics simulation of mechanochemical processes Aiichiro Nakano, Rajiv K. Kalia, Ken-ichi Nomura, Fuyuki Shimojo and Priya Vashishta Recent developments and applications of the real-space multigrid (RMG) method Jerzy Bernholc, M Hodak, W Lu, and F Ribeiro Energy minimisation functionals and algorithms CONQUEST: A linear scaling DFT Code David R Bowler, Tsuyoshi Miyazaki, Antonio Torralba, Veronika Brazdova, Milica Todorovic, Takao Otsuka and Mike Gillan Kernel optimisation and the physical significance of optimised local orbitals in the ONETEP code Peter

A review of recent results on spread F theory

International Nuclear Information System (INIS)

Ossakow, S.L.

1979-01-01

Ionospheric Spread F was discovered some four decades ago. Yet only in the past few years has significant progress been made in the theoretical explanation of such phenomena. In particular, considerable effort has been expended to explain equatorial Spread F and the attendant satellite signal propagation scintillation phenomena. The present review dwells mainly in this low latitude area. The various linear plasma instabilities thought to initiate equatorial Spread F are discussed. Recent theoretical and numerical simulation studies of the nonlinear evolution of the collisional Rayleigh-Taylor instability in equatorial Spread F are reviewed. Also, analytical studies of rising equatorial Spread F bubbles in the collisional and collisionless Rayleigh-Taylor regime are discussed, as well as the nohlinear saturation of instabilities in these two regimes. Current theories on very small scale (< approx 10 meters) size irregularities observed by radar backscatter during equatorial Spread F and their relation to the larger wavelength scintillation causing irregularities are discussed. Application of turbulence theory to equatorial Spread F phenomena is reviewed. Remaining problems to be dealt with at equatorial latitudes are summarized. (Auth.)

Experiment study and FEM simulation on erythrocytes under linear stretching of optical micromanipulation

Science.gov (United States)

Liu, Ying; Song, Huadong; Zhu, Panpan; Lu, Hao; Tang, Qi

2017-08-01

The elasticity of erythrocytes is an important criterion to evaluate the quality of blood. This paper presents a novel research on erythrocytes' elasticity with the application of optical tweezers and the finite element method (FEM) during blood storage. In this work, the erythrocytes with different in vitro times were linearly stretched by trapping force using optical tweezers and the time dependent elasticity of erythrocytes was investigated. The experimental results indicate that the membrane shear moduli of erythrocytes increased with the increasing in vitro time, namely the elasticity was decreasing. Simultaneously, an erythrocyte shell model with two parameters (membrane thickness h and membrane shear modulus H) was built to simulate the linear stretching states of erythrocytes by the FEM, and the simulations conform to the results obtained in the experiment. The evolution process was found that the erythrocytes membrane thicknesses were decreasing. The analysis assumes that the partial proteins and lipid bilayer of erythrocyte membrane were decomposed during the in vitro preservation of blood, which results in thin thickness, weak bending resistance, and losing elasticity of erythrocyte membrane. This study implies that the FEM can be employed to investigate the inward mechanical property changes of erythrocyte in different environments, which also can be a guideline for studying the erythrocyte mechanical state suffered from different diseases.

Structural and dynamical properties of the porins OmpF and OmpC: insights from molecular simulations

International Nuclear Information System (INIS)

Kumar, Amit; Hajjar, Eric; Ruggerone, Paolo; Ceccarelli, Matteo

2010-01-01

In this paper we investigate the structural and dynamical properties of the two major porins (OmpF and OmpC) in Escherichia coli, using molecular dynamics (MD) simulations. In particular we characterized the atomic fluctuations, correlated motions, temperature dependence, solvent-accessible cross-sectional area and water dynamics in the key regions of the two channels. Our in-depth analysis allows us to highlight the importance of both the key conserved and substituted residues between OmpF and OmpC. The latter is characterized by a narrower and longer constriction region with respect to OmpF. OmpC also showed a higher stability upon increasing temperature. We then present the results of transport properties by using accelerated MD simulations to probe the diffusion of norfloxacin (a fluoroquinolone antibiotic) through the two porins OmpF/OmpC. Our study constitutes a step forward towards understanding the structure-function relationship of the two porins' channels. This will benefit the research of antibacterials with improved permeation properties and nanopores that aim to use these porins as sensing systems.

Delta hedging strategies comparison

DEFF Research Database (Denmark)

De Giovanni, Domenico; Ortobelli, S.; Rachev, S.T.

2008-01-01

In this paper we implement dynamic delta hedging strategies based on several option pricing models. We analyze different subordinated option pricing models and we examine delta hedging costs using ex-post daily prices of S&P 500. Furthermore, we compare the performance of each subordinated model...

Direct drive acceleration of planar targets with the Nike KrF laser

Energy Technology Data Exchange (ETDEWEB)

Pawley, C.J.; Sethian, J.D.; Bodner, S.E. [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.] [and others

1999-02-01

Nike is a multi-kilojoule KrF laser with very high beam uniformity ({Delta}I/I<0.2% with all 36 overlapped beams), and the capability to accelerate relatively thick targets on a low adiabat under conditions scalable to direct drive ICF. In a first set of experiments we determined the effect of the imprinting by varying the uniformity of the foot of the laser pulse and measuring the growth of the subsequent Rayleigh-Taylor instability. We found that the lower the imprint, the longer the mass modulations take to reach a given level. This is in quantitative agreement with our 2-D hydrodynamics simulations. The results are promising for direct drive with a very uniform laser. (orig.) 4 refs.

Numerical simulation of anisotropic preheating ablative Rayleigh-Taylor instability

International Nuclear Information System (INIS)

Wang Lifeng; Ye Wenhua; Li Yingjun

2010-01-01

The linear growth rate of the anisotropic preheating ablative Rayleigh-Taylor instability (ARTI) is studied by numerical simulations. The preheating model κ(T)=κ SH [1+f(T)] is applied, where f(T) is the preheating function interpreting the preheating tongue effect in the cold plasma ahead of the ablative front. An arbitrary coefficient D is introduced in the energy equation to study the influence of transverse thermal conductivity on the growth of the ARTI. We find that enhancing diffusion in a plane transverse to the mean longitudinal flow can strongly reduce the growth of the instability. Numerical simulations exhibit a significant stabilization of the ablation front by improving the transverse thermal conduction. Our results are in general agreement with the theory analysis and numerical simulations by Masse. (authors)

Tabulated square-shaped source model for linear accelerator electron beam simulation.

Science.gov (United States)

Khaledi, Navid; Aghamiri, Mahmood Reza; Aslian, Hossein; Ameri, Ahmad

2017-01-01

Using this source model, the Monte Carlo (MC) computation becomes much faster for electron beams. The aim of this study was to present a source model that makes linear accelerator (LINAC) electron beam geometry simulation less complex. In this study, a tabulated square-shaped source with transversal and axial distribution biasing and semi-Gaussian spectrum was investigated. A low energy photon spectrum was added to the semi-Gaussian beam to correct the bremsstrahlung X-ray contamination. After running the MC code multiple times and optimizing all spectrums for four electron energies in three different medical LINACs (Elekta, Siemens, and Varian), the characteristics of a beam passing through a 10 cm × 10 cm applicator were obtained. The percentage depth dose and dose profiles at two different depths were measured and simulated. The maximum difference between simulated and measured percentage of depth doses and dose profiles was 1.8% and 4%, respectively. The low energy electron and photon spectrum and the Gaussian spectrum peak energy and associated full width at half of maximum and transversal distribution weightings were obtained for each electron beam. The proposed method yielded a maximum computation time 702 times faster than a complete head simulation. Our study demonstrates that there was an excellent agreement between the results of our proposed model and measured data; furthermore, an optimum calculation speed was achieved because there was no need to define geometry and materials in the LINAC head.

The Enabling Delta Life Initiative - Global Programme of Action on Deltas - Programme description

NARCIS (Netherlands)

Driel, van W.F.; Skyllerstedt, S.; Wosten, J.H.M.

2014-01-01

Being ‘hotspots’ of human activity with generally high population densities, deltas are vulnerable to changes induced by a range of driving forces, both natural and anthropogenic. In addition to already existing challenges, uncertainty of the possible impacts of climate change, low lying deltas

Critical points for finite Fibonacci chains of point delta-interactions and orthogonal polynomials

International Nuclear Information System (INIS)

De Prunele, E

2011-01-01

For a one-dimensional Schroedinger operator with a finite number n of point delta-interactions with a common intensity, the parameters are the intensity, the n - 1 intercenter distances and the mass. Critical points are points in the parameters space of the Hamiltonian where one bound state appears or disappears. The study of critical points for Hamiltonians with point delta-interactions arranged along a Fibonacci chain is shown to be closely related to the study of the so-called Fibonacci operator, a discrete one-dimensional Schroedinger-type operator, which occurs in the context of tight binding Hamiltonians. These critical points are the zeros of orthogonal polynomials previously studied in the context of special diatomic linear chains with elastic nearest-neighbor interaction. Properties of the zeros (location, asymptotic behavior, gaps, ...) are investigated. The perturbation series from the solvable periodic case is determined. The measure which yields orthogonality is investigated numerically from the zeros. It is shown that the transmission coefficient at zero energy can be expressed in terms of the orthogonal polynomials and their associated polynomials. In particular, it is shown that when the number of point delta-interactions is equal to a Fibonacci number minus 1, i.e. when the intervals between point delta-interactions form a palindrome, all the Fibonacci chains at critical points are completely transparent at zero energy. (paper)

A simulation-based goodness-of-fit test for random effects in generalized linear mixed models

DEFF Research Database (Denmark)

Waagepetersen, Rasmus

2006-01-01

The goodness-of-fit of the distribution of random effects in a generalized linear mixed model is assessed using a conditional simulation of the random effects conditional on the observations. Provided that the specified joint model for random effects and observations is correct, the marginal...... distribution of the simulated random effects coincides with the assumed random effects distribution. In practice, the specified model depends on some unknown parameter which is replaced by an estimate. We obtain a correction for this by deriving the asymptotic distribution of the empirical distribution...

A simulation-based goodness-of-fit test for random effects in generalized linear mixed models

DEFF Research Database (Denmark)

Waagepetersen, Rasmus Plenge

The goodness-of-fit of the distribution of random effects in a generalized linear mixed model is assessed using a conditional simulation of the random effects conditional on the observations. Provided that the specified joint model for random effects and observations is correct, the marginal...... distribution of the simulated random effects coincides with the assumed random effects distribution. In practice the specified model depends on some unknown parameter which is replaced by an estimate. We obtain a correction for this by deriving the asymptotic distribution of the empirical distribution function...

Photoconductivity properties of {delta}-Si doped InGaAs quantum well

Energy Technology Data Exchange (ETDEWEB)

Campo, Junior, V Leira; Marega, Junior, E; Rossi, J C; Lubyshev, D I; Gonzalez Borrero, P P; Basmaji, P [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica

1996-12-31

Full text. The semiconductors thin films with doping level near Anderson transition have high photo sensitivity in the photo conductivity regime. The maximum sensitivity of these photodetectors occurs under illumination when the system transform from semi-insulating to semi-metal. The ratio between deep and shallow levels concentration in this case should be near the unity with a total impurity concentration near 10{sup 15} cm{sup -3}, that difficult to control at the bulk doping. The frequency response in these devices are limited by absorption thickness ({approx}500-300 nm). In present work we report the results of visible-infrared photo detector (PD) preparation by using molecular beam epitaxy. For development of frequency response and wavelength range increase to infrared area we use {delta}-doped In{sub 0.2} Ga{sub 0.8} As quantum well. The doping level in {delta}-Si layer on the middle of QW was 2 x 10{sup 12} cm{sup -3}, that was enough for shift of deep levels-shallow levels concentration ratio to anderson transition in the area near QW. At the illumination all photoexcited carriers was collected by QW. The deepness of photo sensitivity space area is limiters by few nanometers near the QW, that increase the frequency properties of PD. Photo current spectra show high sensibility ({Delta}) (R/R=15%) at cut-off frequency up 1.25 eV. This explain strong optical absorption by QW in the infrared area. The future work will focalized on introducing {delta}-doped In Ga As superlattice for linearization of PD spectrum characteristics. (author)

Effect of linear and non-linear blade modelling techniques on simulated fatigue and extreme loads using Bladed

Science.gov (United States)

Beardsell, Alec; Collier, William; Han, Tao

2016-09-01

There is a trend in the wind industry towards ever larger and more flexible turbine blades. Blade tip deflections in modern blades now commonly exceed 10% of blade length. Historically, the dynamic response of wind turbine blades has been analysed using linear models of blade deflection which include the assumption of small deflections. For modern flexible blades, this assumption is becoming less valid. In order to continue to simulate dynamic turbine performance accurately, routine use of non-linear models of blade deflection may be required. This can be achieved by representing the blade as a connected series of individual flexible linear bodies - referred to in this paper as the multi-part approach. In this paper, Bladed is used to compare load predictions using single-part and multi-part blade models for several turbines. The study examines the impact on fatigue and extreme loads and blade deflection through reduced sets of load calculations based on IEC 61400-1 ed. 3. Damage equivalent load changes of up to 16% and extreme load changes of up to 29% are observed at some turbine load locations. It is found that there is no general pattern in the loading differences observed between single-part and multi-part blade models. Rather, changes in fatigue and extreme loads with a multi-part blade model depend on the characteristics of the individual turbine and blade. Key underlying causes of damage equivalent load change are identified as differences in edgewise- torsional coupling between the multi-part and single-part models, and increased edgewise rotor mode damping in the multi-part model. Similarly, a causal link is identified between torsional blade dynamics and changes in ultimate load results.

Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

Directory of Open Access Journals (Sweden)

Chen Qin

2013-01-01

Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

Standard molar enthalpies of formation of hydroxy-, chlor-, and bromapatite

Energy Technology Data Exchange (ETDEWEB)

Cruz, Fernando J.A.L. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal); Minas da Piedade, Manuel E. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisbon (Portugal); Calado, Jorge C.G. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal)]. E-mail: jcalado@ist.utl.pt

2005-10-15

The standard (p{sup 0} =0.1MPa) molar enthalpies of formation in the crystalline state of hydroxyapatite, chlorapatite and a preliminary value for bromapatite, at T=298.15K, were determined by reaction-solution calorimetry as: {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2},cr]=-(13399+/-11)kJ.mol{sup -1},{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Cl{sub 2},cr]=-(13231+/-82)kJ.mol{sup -1},and{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Br{sub 2},cr]=-(13063+/-81)kJ.mol{sup -1}. A critical assessment of these results and of previously published data is made. Finally, the standard molar enthalpy of formation of iodapatite is estimated as {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}I{sub 2},cr]=-12949kJ.mol{sup -1}, from a linear correlation of {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}X{sub 2},cr] (X=OH, F, Cl, Br) against the corresponding {delta}{sub f}H{sub m}{sup 0} [CaX{sub 2},cr].

Twin Tail/Delta Wing Configuration Buffet Due to Unsteady Vortex Breakdown Flow

Science.gov (United States)

Kandil, Osama A.; Sheta, Essam F.; Massey, Steven J.

1996-01-01

The buffet response of the twin-tail configuration of the F/A-18 aircraft; a multidisciplinary problem, is investigated using three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations. The second set is the coupled aeroelastic equations for bending and torsional twin-tail responses. The third set is the grid-displacement equations which are used to update the grid coordinates due to the tail deflections. The computational model consists of a 76 deg-swept back, sharp edged delta wing of aspect ratio of one and a swept-back F/A-18 twin-tails. The configuration is pitched at 32 deg angle of attack and the freestream Mach number and Reynolds number are 0.2 and 0.75 x 10(exp 6) respectively. The problem is solved for the initial flow conditions with the twin tail kept rigid. Next, the aeroelastic equations of the tails are turned on along with the grid-displacement equations to solve for the uncoupled bending and torsional tails response due to the unsteady loads produced by the vortex breakdown flow of the vortex cores of the delta wing. Two lateral locations of the twin tail are investigated. These locations are called the midspan and inboard locations.

Modeling the detectability of vesicoureteral reflux using microwave radiometry

Energy Technology Data Exchange (ETDEWEB)

Arunachalam, Kavitha [Department of Engineering Design, Indian Institute of Technology Madras, Chennai (India); Maccarini, Paolo F; Stauffer, Paul R [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); De Luca, Valeria [Department of Information Tech and Electrical Eng., ETH Zurich (Switzerland); Bardati, Fernando [Department of Computer Science, Systems and Production, University of Rome, Tor Vergata, Roma (Italy); Snow, Brent W, E-mail: akavitha@iitm.ac.i [University of Utah and Primary Children' s Medical Center, Salt Lake City, UT (United States)

2010-09-21

We present the modeling efforts on antenna design, frequency selection and receiver sensitivity estimation to detect vesicoureteral reflux (VUR) using microwave (MW) radiometry as warm urine from the bladder maintained at fever range temperature using a MW hyperthermia device reflows into the kidneys. The radiometer center frequency (f{sub c}), frequency band ({Delta}f) and aperture radius (r{sub a}) of the physical antenna for kidney temperature monitoring are determined using a simplified universal antenna model with a circular aperture. Anatomical information extracted from the computed tomography (CT) images of children aged 4-6 years is used to construct a layered 3D tissue model. Radiometric antenna efficiency is evaluated in terms of the ratio of the power collected from the target at depth to the total power received by the antenna ({eta}). The power ratio of the theoretical antenna is used to design a microstrip log spiral antenna with directional radiation pattern over f{sub c} {+-} {Delta}f/2. Power received by the log spiral from the deep target is enhanced using a thin low-loss dielectric matching layer. A cylindrical metal cup is proposed to shield the antenna from electromagnetic interference (EMI). Transient thermal simulations are carried out to determine the minimum detectable change in the antenna brightness temperature ({delta}T{sub B}) for 15-25 mL urine refluxes at 40-42 {sup 0}C located 35 mm from the skin surface. Theoretical antenna simulations indicate maximum {eta} over 1.1-1.6 GHz for r{sub a} = 30-40 mm. Simulations of the 35 mm radius tapered log spiral yielded a higher power ratio over f{sub c} {+-} {Delta}f/2 for the 35-40 mm deep targets in the presence of an optimal matching layer. Radiometric temperature calculations indicate {delta}T{sub B} {>=} 0.1 K for the 15 mL urine at 40 {sup 0}C and 35 mm depth. Higher {eta} and {delta}T{sub B} were observed for the antenna and matching layer inside the metal cup. Reflection measurements

Numerical Simulation of the Time Evolution of Small-Scale Irregularities in the F-Layer Ionospheric Plasma

Directory of Open Access Journals (Sweden)

O. V. Mingalev

2011-01-01

Full Text Available Dynamics of magnetic field-aligned small-scale irregularities in the electron concentration, existing in the F-layer ionospheric plasma, is investigated with the help of a mathematical model. The plasma is assumed to be a rarefied compound consisting of electrons and positive ions and being in a strong, external magnetic field. In the applied model, kinetic processes in the plasma are simulated by using the Vlasov-Poisson system of equations. The system of equations is numerically solved applying a macroparticle method. The time evolution of a plasma irregularity, having initial cross-section dimension commensurable with a Debye length, is simulated during the period sufficient for the irregularity to decay completely. The results of simulation indicate that the small-scale irregularity, created initially in the F-region ionosphere, decays accomplishing periodic damped vibrations, with the process being collisionless.

Three-point phase correlations: A new measure of non-linear large-scale structure

CERN Document Server

Wolstenhulme, Richard; Obreschkow, Danail

2015-01-01

We derive an analytical expression for a novel large-scale structure observable: the line correlation function. The line correlation function, which is constructed from the three-point correlation function of the phase of the density field, is a robust statistical measure allowing the extraction of information in the non-linear and non-Gaussian regime. We show that, in perturbation theory, the line correlation is sensitive to the coupling kernel F_2, which governs the non-linear gravitational evolution of the density field. We compare our analytical expression with results from numerical simulations and find a very good agreement for separations r>20 Mpc/h. Fitting formulae for the power spectrum and the non-linear coupling kernel at small scales allow us to extend our prediction into the strongly non-linear regime. We discuss the advantages of the line correlation relative to standard statistical measures like the bispectrum. Unlike the latter, the line correlation is independent of the linear bias. Furtherm...

Enabling immersive simulation.

Energy Technology Data Exchange (ETDEWEB)

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

2009-02-01

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

Stable Operation and Electricity Generating Characteristics of a Single-Cylinder Free Piston Engine Linear Generator: Simulation and Experiments

Directory of Open Access Journals (Sweden)

Huihua Feng

2015-01-01

Full Text Available We present a novel design of a single-cylinder free piston engine linear generator (FPELG incorporating a linear motor as a rebound device. A systematic simulation model of this FPELG system was built containing a kinematic and dynamic model of the piston and mover, a magneto-electric model of the linear generator, a thermodynamic model of the single-cylinder engine, and a friction model between the piston ring and cylinder liner. Simulations were performed to understand the relationships between pre-set motor parameters and the running performance of the FPELG. From the simulation results, it was found that a motor rebound force with a parabolic profile had clear advantages over a force with a triangular profile, such as a higher running frequency and peak cylinder pressure, faster piston motion, etc. The rebound position and the amplitude of rebound force were also determined by simulations. The energy conversion characteristics of the generator were obtained from our FPELG test rig. The parameters of intake pressure, motor frequency, and load resistance were varied over certain ranges, and relationships among these three parameters were obtained. The electricity-generating characteristic parameters include output power and system efficiency, which can measure the quality of matching the controllable parameters. The output power can reach 25.9 W and the system efficiency can reach 13.7%. The results in terms of matching parameters and electricity-generating characteristics should be useful to future research in adapting these engines to various operating modes.

Skinfold creep under load of caliper. Linear visco- and poroelastic model simulations.

Science.gov (United States)

Nowak, Joanna; Nowak, Bartosz; Kaczmarek, Mariusz

2015-01-01

This paper addresses the diagnostic idea proposed in [11] to measure the parameter called rate of creep of axillary fold of tissue using modified Harpenden skinfold caliper in order to distinguish normal and edematous tissue. Our simulations are intended to help understanding the creep phenomenon and creep rate parameter as a sensitive indicator of edema existence. The parametric analysis shows the tissue behavior under the external load as well as its sensitivity to changes of crucial hydro-mechanical tissue parameters, e.g., permeability or stiffness. The linear viscoelastic and poroelastic models of normal (single phase) and oedematous tissue (twophase: swelled tissue with excess of interstitial fluid) implemented in COMSOL Multiphysics environment are used. Simulations are performed within the range of small strains for a simplified fold geometry, material characterization and boundary conditions. The predicted creep is the result of viscosity (viscoelastic model) or pore fluid displacement (poroelastic model) in tissue. The tissue deformations, interstitial fluid pressure as well as interstitial fluid velocity are discussed in parametric analysis with respect to elasticity modulus, relaxation time or permeability of tissue. The creep rate determined within the models of tissue is compared and referred to the diagnostic idea in [11]. The results obtained from the two linear models of subcutaneous tissue indicate that the form of creep curve and the creep rate are sensitive to material parameters which characterize the tissue. However, the adopted modelling assumptions point to a limited applicability of the creep rate as the discriminant of oedema.

SU-F-T-294: The Analysis of Gamma Criteria for Delta4 Dosimetry Using Statistical Process Control

Energy Technology Data Exchange (ETDEWEB)

Cho, S; Ahn, S; Kim, J; Park, K; Choi, W; Lee, H; Lee, E; Yoon, J; Keum, K [Yonsei Univeristy, Seoul (Korea, Republic of)

2016-06-15

Purpose: To evaluate the sensitivity of gamma criteria for patient-specific volumetric modulated arc therapy(VMAT) quality assurance of the Delta{sup 4} dosimetry program using the statistical process control(SPC) methodology. Methods: The authors selected 20 patient-specific VMAT QA cases which were undertaken MapCHECK and ArcCHECK with gamma pass rate better than 97%. The QAs data were collected Delta4 Phantom+ and Elekta Agility six megavolts without using an angle incrementer. The gamma index(GI) were calculated in 2D planes with normalizing deviation to local dose(local gamma). The sensitivity of the GI methodology using criterion of 3%/3mm, 3%/2mm and 2%/3mm was analyzed with using process acceptability indices. We used local confidence(LC) level, the upper control limit(UCL) and lower control limit(LCL) of I-MR chart for process capability index(Cp) and a process acceptability index (Cpk). Results: The lower local confidence levels of 3%/3mm, 3%/2mm and 2%/3mm were 92.0%, 83.6% and 78.8% respectively. All of the calculated Cp and Cpk values that used LC level were under 1.0 in this study. The calculated LCLs of I-MR charts were 89.5%, 79.0% and 70.5% respectively. These values were higher than 1.0 which means good quality of QA. For the generally used lower limit of 90%, we acquired over 1.3 of Cp value for the gamma index of 3%/3mm and lower than 1.0 in the rest of GI. Conclusion: We applied SPC methodology to evaluate the sensitivity of gamma criteria and could see the lower control limits of VMAT QA for the Delta 4 dosimetry and could see that Delta 4 phantom+ dosimetry more affected by the position error and the I-MR chart derived values are more suitable for establishing lower limits. Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (No. 2015R1D1A1A01060463)

SU-F-T-294: The Analysis of Gamma Criteria for Delta4 Dosimetry Using Statistical Process Control

International Nuclear Information System (INIS)

Cho, S; Ahn, S; Kim, J; Park, K; Choi, W; Lee, H; Lee, E; Yoon, J; Keum, K

2016-01-01

Purpose: To evaluate the sensitivity of gamma criteria for patient-specific volumetric modulated arc therapy(VMAT) quality assurance of the Delta 4 dosimetry program using the statistical process control(SPC) methodology. Methods: The authors selected 20 patient-specific VMAT QA cases which were undertaken MapCHECK and ArcCHECK with gamma pass rate better than 97%. The QAs data were collected Delta4 Phantom+ and Elekta Agility six megavolts without using an angle incrementer. The gamma index(GI) were calculated in 2D planes with normalizing deviation to local dose(local gamma). The sensitivity of the GI methodology using criterion of 3%/3mm, 3%/2mm and 2%/3mm was analyzed with using process acceptability indices. We used local confidence(LC) level, the upper control limit(UCL) and lower control limit(LCL) of I-MR chart for process capability index(Cp) and a process acceptability index (Cpk). Results: The lower local confidence levels of 3%/3mm, 3%/2mm and 2%/3mm were 92.0%, 83.6% and 78.8% respectively. All of the calculated Cp and Cpk values that used LC level were under 1.0 in this study. The calculated LCLs of I-MR charts were 89.5%, 79.0% and 70.5% respectively. These values were higher than 1.0 which means good quality of QA. For the generally used lower limit of 90%, we acquired over 1.3 of Cp value for the gamma index of 3%/3mm and lower than 1.0 in the rest of GI. Conclusion: We applied SPC methodology to evaluate the sensitivity of gamma criteria and could see the lower control limits of VMAT QA for the Delta 4 dosimetry and could see that Delta 4 phantom+ dosimetry more affected by the position error and the I-MR chart derived values are more suitable for establishing lower limits. Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (No. 2015R1D1A1A01060463)

Possible factors determining the non-linearity in the VO2-power output relationship in humans: theoretical studies.

Science.gov (United States)

Korzeniewski, Bernard; Zoladz, Jerzy A

2003-08-01

At low power output exercise (below lactate threshold), the oxygen uptake increases linearly with power output, but at high power output exercise (above lactate threshold) some additional oxygen consumption causes a non-linearity in the overall VO(2) (oxygen uptake rate)-power output relationship. The functional significance of this phenomenon for human exercise tolerance is very important, but the mechanisms underlying it remain unknown. In the present work, a computer model of oxidative phosphorylation in intact skeletal muscle developed previously is used to examine the background of this relationship in different modes of exercise. Our simulations demonstrate that the non-linearity in the VO(2)-power output relationship and the difference in the magnitude of this non-linearity between incremental exercise mode and square-wave exercise mode (constant power output exercise) can be generated by introducing into the model some hypothetical factor F (group of associated factors) that accumulate(s) in time during exercise. The performed computer simulations, based on this assumption, give proper time courses of changes in VO(2) and [PCr] after an onset of work of different intensities, including the slow component in VO(2), well matching the experimental results. Moreover, if it is assumed that the exercise terminates because of fatigue when the amount/intensity of F exceed some threshold value, the model allows the generation of a proper shape of the well-known power-duration curve. This fact suggests that the phenomenon of the non-linearity of the VO(2)-power output relationship and the magnitude of this non-linearity in different modes of exercise is determined by some factor(s) responsible for muscle fatigue.

Watershed-Scale Modeling of Land-Use and Altered Environment Impacts on Aquatic Weed Growth in the Delta

Science.gov (United States)

Bubenheim, David; Potter, Christopher; Zhang, Minghua

2016-01-01

model component. Plant response to the range of water quality factors, response times, and altered temperature and light regimes of the Delta have required gap-filling studies to provide model parameters. Delta-SWAT provides a tool for evaluating temporal and spatial effects of land-use and altered environments in the Delta and contributing watersheds on aquatic weed growth. Using Delta-SWAT for simulation modeling allows evaluation of historic and current conditions as well as consideration potential climate change and management practice outcomes. Delta-SWAT adds to the scientific understanding of dynamics in the Delta and enhances development of science-informed, management strategies and practices.

Particle-in-Cell Code BEAMPATH for Beam Dynamics Simulations in Linear Accelerators and Beamlines

International Nuclear Information System (INIS)

Batygin, Y.

2004-01-01

A code library BEAMPATH for 2 - dimensional and 3 - dimensional space charge dominated beam dynamics study in linear particle accelerators and beam transport lines is developed. The program is used for particle-in-cell simulation of axial-symmetric, quadrupole-symmetric and z-uniform beams in a channel containing RF gaps, radio-frequency quadrupoles, multipole lenses, solenoids and bending magnets. The programming method includes hierarchical program design using program-independent modules and a flexible combination of modules to provide the most effective version of the structure for every specific case of simulation. Numerical techniques as well as the results of beam dynamics studies are presented

Particle-in-Cell Code BEAMPATH for Beam Dynamics Simulations in Linear Accelerators and Beamlines

Energy Technology Data Exchange (ETDEWEB)

Batygin, Y.

2004-10-28

A code library BEAMPATH for 2 - dimensional and 3 - dimensional space charge dominated beam dynamics study in linear particle accelerators and beam transport lines is developed. The program is used for particle-in-cell simulation of axial-symmetric, quadrupole-symmetric and z-uniform beams in a channel containing RF gaps, radio-frequency quadrupoles, multipole lenses, solenoids and bending magnets. The programming method includes hierarchical program design using program-independent modules and a flexible combination of modules to provide the most effective version of the structure for every specific case of simulation. Numerical techniques as well as the results of beam dynamics studies are presented.

Linear nonradial pulsation theory. Lecture 7

International Nuclear Information System (INIS)

Cox, A.N.

1983-01-01

Many of the upper main-sequence stars pulsate in spheroidal nonradial modes. We know this to be true in numerous cases, as we have tabulated for the #betta# Cephei and delta Scuti variables in previous lectures. However, we cannot identify the actual mode for any star except for the low-order pressure p and f modes of our sun. It remains a great challenge to clearly state what really is occurring, in the process we learn more about how stars evolve and pulsate

Safety Assessment of Advanced Imaging Sequences II: Simulations

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt

2016-01-01

.6%, when using the impulse response of the probe estimated from an independent measurement. The accuracy is increased to between -22% to 24.5% for MI and between -33.2% to 27.0% for Ispta.3, when using the pressure response measured at a single point to scale the simulation. The spatial distribution of MI...... Mechanical Index (MI) and Ispta.3 as required by FDA. The method is performed on four different imaging schemes and compared to measurements conducted using the SARUS experimental scanner. The sequences include focused emissions with an F-number of 2 with 64 elements that generate highly non-linear fields....... The simulation time is between 0.67 ms to 2.8 ms per emission and imaging point, making it possible to simulate even complex emission sequences in less than 1 s for a single spatial position. The linear simulations yield a relative accuracy on MI between -12.1% to 52.3% and for Ispta.3 between -38.6% to 62...

Simulated East-west differences in F-region peak electron density at Far East mid-latitude region

Science.gov (United States)

Ren, Z.; Wan, W.

2017-12-01

In the present work, using Three-Dimensional Theoretical Ionospheric Model of the Earth in Institute of Geology and Geophysics, Chinese Academy of Sciences (TIME3D-IGGCAS), we simulated the east-west differences in Fregion peak electron density (NmF2) at Far East mid-latitude region.We found that, after removing the longitudinal variations of neutral parameters, TIME3D-IGGCAS can better represent the observed relative east-west difference (Rew) features. Rew is mainly negative (West NmF2 > East NmF2) at noon and positive (East NmF2 >West NmF2) at evening-night. The magnitude of daytime negative Rew is weak at local winter and strong at local summer, and the daytime Rew show two negative peaks around two equinoxes. With the increasing of solar flux level, the magnitude of Rew mainly become larger, and two daytime negative peaks slight shifts to June Solstice. With the decreasing of geographical latitude, Rew mainly become positive, and two daytime negative peaks slight shifts to June Solstice. Our simulation also suggested that the thermospheric zonal wind combined with the geomagnetic field configuration play a pivotal role in the formation of the ionospheric east-west differences at Far East midlatitude region.

Acoustic fMRI noise : Linear time-invariant system model

NARCIS (Netherlands)

Sierra, Carlos V. Rizzo; Versluis, Maarten J.; Hoogduin, Johannes M.; Duifhuis, Hendrikus (Diek)

Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic

Multiple Linear Regression Model Based on Neural Network and Its Application in the MBR Simulation

Directory of Open Access Journals (Sweden)

Chunqing Li

2012-01-01

Full Text Available The computer simulation of the membrane bioreactor MBR has become the research focus of the MBR simulation. In order to compensate for the defects, for example, long test period, high cost, invisible equipment seal, and so forth, on the basis of conducting in-depth study of the mathematical model of the MBR, combining with neural network theory, this paper proposed a three-dimensional simulation system for MBR wastewater treatment, with fast speed, high efficiency, and good visualization. The system is researched and developed with the hybrid programming of VC++ programming language and OpenGL, with a multifactor linear regression model of affecting MBR membrane fluxes based on neural network, applying modeling method of integer instead of float and quad tree recursion. The experiments show that the three-dimensional simulation system, using the above models and methods, has the inspiration and reference for the future research and application of the MBR simulation technology.

Resting-state EEG delta power is associated with psychological pain in adults with a history of depression.

Science.gov (United States)

Meerwijk, Esther L; Ford, Judith M; Weiss, Sandra J

2015-02-01

Psychological pain is a prominent symptom of clinical depression. We asked if frontal alpha asymmetry, frontal EEG power, and frontal fractal dimension asymmetry predicted psychological pain in adults with a history of depression. Resting-state frontal EEG (F3/F4) was recorded while participants (N=35) sat upright with their eyes closed. Frontal delta power predicted psychological pain while controlling for depressive symptoms, with participants who exhibited less power experiencing greater psychological pain. Frontal fractal dimension asymmetry, a nonlinear measure of complexity, also predicted psychological pain, such that greater left than right complexity was associated with greater psychological pain. Frontal alpha asymmetry did not contribute unique variance to any regression model of psychological pain. As resting-state delta power is associated with the brain's default mode network, results suggest that the default mode network was less activated during high psychological pain. Findings are consistent with a state of arousal associated with psychological pain. Copyright © 2015 Elsevier B.V. All rights reserved.

Non-linear diffusion and pattern formation in vortex matter

Science.gov (United States)

Wijngaarden, Rinke J.; Surdeanu, R.; Huijbregtse, J. M.; Rector, J. H.; Dam, B.; Griessen, R.; Einfeld, J.; Woerdenweber, R.

2000-03-01

Penetration of magnetic flux in YBa_2Cu_3O7 superconducting thin films and crystals in externally applied magnetic fields is visualized with a magneto-optical technique. A variety of flux patterns due to non-linear vortex behavior is observed: 1. Roughening of the flux front^1 with scaling exponents identical to those observed in burning paper^2. Two regimes are found where respectively spatial disorder and temporal disorder dominate. In the latter regime Kardar-Parisi-Zhang behavior is found. 2. Roughening of the flux profile similar to the Oslo model for rice-piles. 3. Fractal penetration of flux^3 with Hausdorff dimension depending on the critical current anisotropy. 4. Penetration as 'flux-rivers'. 5. The occurrence of commensurate and incommensurate channels in films with anti-dots as predicted in numerical simulations by Reichhardt, Olson and Nori^4. By comparison with numerical simulations, it is shown that most of the observed behavior can be explained in terms of non-linear diffusion of vortices. ^1R. Surdeanu, R.J. Wijngaarden, E. Visser, J.M. Huijbregtse, J.H. Rector, B. Dam and R. Griessen, Phys.Rev. Lett. 83 (1999) 2054 ^2J. Maunuksela, M. Myllys, O.-P. Kähkönen, J. Timonen, N. Provatas, M.J. Alava, T. Ala-Nissila, Phys. Rev. Lett. 79, 1515 (1997) ^3R. Surdeanu, R.J. Wijngaarden, B. Dam, J. Rector, R. Griessen, C. Rossel, Z.F. Ren and J.H. Wang, Phys Rev B 58 (1998) 12467 ^4C. Reichhardt, C.J. Olson and F. Nori, Phys. Rev. B 58, 6534 (1998)

A primer on linear models

CERN Document Server

Monahan, John F

2008-01-01

Preface Examples of the General Linear Model Introduction One-Sample Problem Simple Linear Regression Multiple Regression One-Way ANOVA First Discussion The Two-Way Nested Model Two-Way Crossed Model Analysis of Covariance Autoregression Discussion The Linear Least Squares Problem The Normal Equations The Geometry of Least Squares Reparameterization Gram-Schmidt Orthonormalization Estimability and Least Squares Estimators Assumptions for the Linear Mean Model Confounding, Identifiability, and Estimability Estimability and Least Squares Estimators F

Delta Semantics Defined By Petri Nets

DEFF Research Database (Denmark)

Jensen, Kurt; Kyng, Morten; Madsen, Ole Lehrmann

and the possibility of using predicates to specify state changes. In this paper a formal semantics for Delta is defined and analysed using Petri nets. Petri nets was chosen because the ideas behind Petri nets and Delta concide on several points. A number of proposals for changes in Delta, which resulted from...

Determining the Cause for Low Flowrates during Am/Cm Simulant Testing in F-Area

International Nuclear Information System (INIS)

Lambert, D.P.

2003-01-01

30,000 gallons of Americium/Curium (Am/Cm) slurry was transferred from F-Canyon to Tank 51H over an 18 hour period. This was the first continuous transfer of waste from F-Canyon to a waste tank. Prior to the successful Am/Cm transfer, the facility had experienced difficulties in transferring simulated solutions. A team of personnel from several divisions worked in well-coordinated fashion to determine a cost effective means to identify and mitigate the obstacles to the transfer. The team successfully diagnosed the causes of the problem, replicated the observed behavior in laboratory tests and computer modeling, and recommended controls and changes to facility operations. A successful simulant transfer demonstrated readiness for the Am/Cm transfer. This report summarizes the results of the investigation to determine the cause for the poor flow rate experienced during simulant testing in F-Area. Flow rates as low as 3 gallons per minute (gpm) occurred at the end of the transfer. This report includes an explanation for the low flow rate and recommends controls to prevent the reoccurrence. We recommend the following controls to prevent the reoccurrence of slow flows. 1. Control the temperature of the contents of the simulant and real waste storage tanks near ambient during preparation and storage. Temperature control will minimize the inadvertent evaporation of the slurry and minimize any negative impacts of a high temperature during precipitation and storage of the slurry. 2. Avoid any evolution that can inadvertently concentrate the solutions. Well mixed storage tanks and the proper jet or pump operation are necessary to ensure a uniform slurry transfer and avoid concentrating a heel in Tank 13.3. 3. Minimize the air purge rate in the storage tanks after preparation of the simulant and actual waste. The purge leads to slow evaporation of the slurry as well as addition of carbonates, from carbon dioxide sorption. 4. Replace evaporative losses by adding inhibited water

Simulation models for tokamak plasmas

International Nuclear Information System (INIS)

Dimits, A.M.; Cohen, B.I.

1992-01-01

Two developments in the nonlinear simulation of tokamak plasmas are described: (A) Simulation algorithms that use quasiballooning coordinates have been implemented in a 3D fluid code and a 3D partially linearized (Δf) particle code. In quasiballooning coordinates, one of the coordinate directions is closely aligned with that of the magnetic field, allowing both optimal use of the grid resolution for structures highly elongated along the magnetic field as well as implementation of the correct periodicity conditions with no discontinuities in the toroidal direction. (B) Progress on the implementation of a likeparticle collision operator suitable for use in partially linearized particle codes is reported. The binary collision approach is shown to be unusable for this purpose. The algorithm under development is a complete version of the test-particle plus source-field approach that was suggested and partially implemented by Xu and Rosenbluth

The in vivo therapeutic efficacy of the oncolytic adenovirus Delta24-RGD is mediated by tumor-specific immunity.

Directory of Open Access Journals (Sweden)

Anne Kleijn

Full Text Available The oncolytic adenovirus Delta24-RGD represents a new promising therapeutic agent for patients with a malignant glioma and is currently under investigation in clinical phase I/II trials. Earlier preclinical studies showed that Delta24-RGD is able to effectively lyse tumor cells, yielding promising results in various immune-deficient glioma models. However, the role of the immune response in oncolytic adenovirus therapy for glioma has never been explored. To this end, we assessed Delta24-RGD treatment in an immune-competent orthotopic mouse model for glioma and evaluated immune responses against tumor and virus. Delta24-RGD treatment led to long-term survival in 50% of mice and this effect was completely lost upon administration of the immunosuppressive agent dexamethasone. Delta24-RGD enhanced intra-tumoral infiltration of F4/80+ macrophages, CD4+ and CD8+ T-cells, and increased the local production of pro-inflammatory cytokines and chemokines. In treated mice, T cell responses were directed to the virus as well as to the tumor cells, which was reflected in the presence of protective immunological memory in mice that underwent tumor rechallenge. Together, these data provide evidence that the immune system plays a vital role in the therapeutic efficacy of oncolytic adenovirus therapy of glioma, and may provide angles to future improvements on Delta24-RGD therapy.

Direct and indirect influences of the weaver ant Oecophylla smaragdina on citrus farmers pest perceptions and management practices in the Mekong Delta, Vietnam.

NARCIS (Netherlands)

Mele, van P.; Cuc, N.T.T.; Huis, van A.

2002-01-01

In the Mekong Delta, Vietnam, the predatory weaver ant Oecophylla smaragdina was abundant in about 75␘f the sweet orange and 25␘f the Tieu mandarin orchards. With a three-level scale (low, moderate, high), farmers assessed the incidence, severity and yield loss of fruit caused by major pests. With

Cliff´s Delta Calculator: A non-parametric effect size program for two groups of observations

Directory of Open Access Journals (Sweden)

Guillermo Macbeth

2011-05-01

Full Text Available The Cliff´s Delta statistic is an effect size measure that quantifies the amount of difference between two non-parametric variables beyond p-values interpretation. This measure can be understood as a useful complementary analysis for the corresponding hypothesis testing. During the last two decades the use of effect size measures has been strongly encouraged by methodologists and leading institutions of behavioral sciences. The aim of this contribution is to introduce the Cliff´s Delta Calculator software that performs such analysis and offers some interpretation tips. Differences and similarities with the parametric case are analysed and illustrated. The implementation of this free program is fully described and compared with other calculators. Alternative algorithmic approaches are mathematically analysed and a basic linear algebra proof of its equivalence is formally presented. Two worked examples in cognitive psychology are commented. A visual interpretation of Cliff´s Delta is suggested. Availability, installation and applications of the program are presented and discussed.

Anomalous electron transport in Hall-effect thrusters: Comparison between quasi-linear kinetic theory and particle-in-cell simulations

Science.gov (United States)

Lafleur, T.; Martorelli, R.; Chabert, P.; Bourdon, A.

2018-06-01

Kinetic drift instabilities have been implicated as a possible mechanism leading to anomalous electron cross-field transport in E × B discharges, such as Hall-effect thrusters. Such instabilities, which are driven by the large disparity in electron and ion drift velocities, present a significant challenge to modelling efforts without resorting to time-consuming particle-in-cell (PIC) simulations. Here, we test aspects of quasi-linear kinetic theory with 2D PIC simulations with the aim of developing a self-consistent treatment of these instabilities. The specific quantities of interest are the instability growth rate (which determines the spatial and temporal evolution of the instability amplitude), and the instability-enhanced electron-ion friction force (which leads to "anomalous" electron transport). By using the self-consistently obtained electron distribution functions from the PIC simulations (which are in general non-Maxwellian), we find that the predictions of the quasi-linear kinetic theory are in good agreement with the simulation results. By contrast, the use of Maxwellian distributions leads to a growth rate and electron-ion friction force that is around 2-4 times higher, and consequently significantly overestimates the electron transport. A possible method for self-consistently modelling the distribution functions without requiring PIC simulations is discussed.

Houtman Abrolhos Isotope (delta 18O, delta 13C) Data for 1795 to 1994

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — DESCRIPTION: VARIABLES AND UNITS: Column #1: core depth in mm Column #2: delta C-13 vs V-PDB Column #3: delta O-18 vs V-PDB Column #4: assigned date in years A.D....

Estimation of crosstalk in LED fNIRS by photon propagation Monte Carlo simulation

Science.gov (United States)

Iwano, Takayuki; Umeyama, Shinji

2015-12-01

fNIRS (functional near-Infrared spectroscopy) can measure brain activity non-invasively and has advantages such as low cost and portability. While the conventional fNIRS has used laser light, LED light fNIRS is recently becoming common in use. Using LED for fNIRS, equipment can be more inexpensive and more portable. LED light, however, has a wider illumination spectrum than laser light, which may change crosstalk between the calculated concentration change of oxygenated and deoxygenated hemoglobins. The crosstalk is caused by difference in light path length in the head tissues depending on wavelengths used. We conducted Monte Carlo simulations of photon propagation in the tissue layers of head (scalp, skull, CSF, gray matter, and white matter) to estimate the light path length in each layers. Based on the estimated path lengths, the crosstalk in fNIRS using LED light was calculated. Our results showed that LED light more increases the crosstalk than laser light does when certain combinations of wavelengths were adopted. Even in such cases, the crosstalk increased by using LED light can be effectively suppressed by replacing the value of extinction coefficients used in the hemoglobin calculation to their weighted average over illumination spectrum.

Multisatellite systems with linear structure and their application for continuous coverage of the earth

Science.gov (United States)

Saulskiy, V. K.

2005-01-01

Multisatellite systems with linear structure (SLS) are defined, and their application for a continuous global or zonal coverage of the Earth’s surface is justified. It is demonstrated that in some cases these systems turned out to be better than usually recommended kinematically regular systems by G.V. Mozhaev, delta systems of J.G. Walker, and polar systems suggested by F.W. Gobets, L. Rider, and W.S. Adams. When a comparison is made using the criterion of a minimum radius of one-satellite coverage circle, the SLS beat the other systems for the majority of satellite numbers from the range 20 63, if the global continuous single coverage of the Earth is required. In the case of a zonal continuous single coverage of the latitude belt ±65°, the SLS are preferable at almost all numbers of satellites from 38 to 100, and further at any values up to 200 excluding 144.

Delta infection evidenced by radioimmunoanalysis in selected collectives

Energy Technology Data Exchange (ETDEWEB)

Kselikova, M; Horejsi, J; Urbankova, J

1987-01-01

The presence of the Delta agent within the population was tested by means of the Delta-antibody radioimmunoassay using competitive kits of the firms ABBOTT (ABBOTT-ANTI-DELTA) and SORIN (AB-DELTAK). The Delta-antibody was found in 3.2% HBV patients, 5% HBsAg carriers, and in 20.8% of specific anti-Hbs-immunoglobulin. In hemophiliacs and blood donors no Delta-antibody was seen.

Delta infection evidenced by radioimmunoanalysis in selected collectives

International Nuclear Information System (INIS)

Kselikova, M.; Horejsi, J.; Urbankova, J.

1987-01-01

The presence of the Delta agent within the population was tested by means of the Delta-antibody radioimmunoassay using competitive kits of the firms ABBOTT (ABBOTT-ANTI-DELTA) and SORIN (AB-DELTAK). The Delta-antibody was found in 3.2% HBV patients, 5% HBsAg carriers, and in 20.8% of specific anti-Hbs-immunoglobulin. In hemophiliacs and blood donors no Delta-antibody was seen. (author)

Numerical Simulation of Anisotropic Preheating Ablative Rayleigh–Taylor Instability

International Nuclear Information System (INIS)

Li-Feng, Wang; Wen-Hua, Ye; Ying-Jun, Li

2010-01-01

The linear growth rate of the anisotropic preheating ablative Rayleigh–Taylor instability (ARTI) is studied by numerical simulations. The preheating model κ(T) = κ SH [1 + f(T)] is applied, where f(T) is the preheating function interpreting the preheating tongue effect in the cold plasma ahead of the ablative front. An arbitrary coefficient D is introduced in the energy equation to study the influence of transverse thermal conductivity on the growth of the ARTI. We find that enhancing diffusion in a plane transverse to the mean longitudinal flow can strongly reduce the growth of the instability. Numerical simulations exhibit a significant stabilization of the ablation front by improving the transverse thermal conduction. Our results are in general agreement with the theory analysis and numerical simulations by Masse [Phys. Rev. Lett. 98 (2007) 245001]. (physics of gases, plasmas, and electric discharges)

Dermal absorption of the insecticide lindane (1 delta, 2 delta, 3 beta, 4 delta, 5 delta, 6 beta-hexachlorocyclohexane) in rats and rhesus monkeys: Effect of anatomical site

International Nuclear Information System (INIS)

Moody, R.P.; Ritter, L.

1989-01-01

Dermal absorption of the insecticide lindane (1 delta, 2 delta, 3 beta, 4 delta, 5 delta, 6 beta-hexachlorocyclohexane) was determined in rats and rhesus monkeys. Lindane is in widespread use as a 1% cream or lotion scabicide formulation and as a 1% miticide shampoo for body lice control in humans. Results obtained following our in vivo dermal absorption procedure demonstrated that 18 +/- 4.1%, 34 +/- 5.2%, and 54 +/- 26.3% of the applied dose was absorbed following topical applications at a rate of 1.5 micrograms/cm2 (6.2 micrograms/100 microliters of acetone) of the 14C-labeled pesticide to 4.2-cm2 regions of the forearm (n = 8), forehead (n = 7), and palm (n = 4) of rhesus monkeys, respectively. Dose sites were washed with soapy water 24 h posttreatment. Comparative studies in rats (n = 5) dosed middorsally demonstrated 31 +/- 9.5% absorption. Statistical analysis of the 14C excretion kinetics demonstrated slower clearance of lindane from rats than monkey forearm, forehead, or palm. Intramuscular (im) injections of 14C-lindane gave 52 +/- 7.1% recovery in monkey (n = 8) and 64 +/- 5.9% in rats (n = 5), suggesting body storage of this lipophilic chemical

Thermal performance study of a box type solar cooker: evaluation of second figure of merit, F2

International Nuclear Information System (INIS)

Subudh Kumar

2006-01-01

The thermal performance of a box type solar cooker can be evaluated through the determination of two figures of merit-F 1 and F 2 . The F 1 is defined as the ratio of optical efficiency factor (η o ) the overall heat loss coefficient (U L ) and F 2 relates to the effectiveness of heat exchange between cooker interiors and contents of the pots. The values of F 1 and F 2 can be found experimentally from the stagnation (no-load) and load (water) tests respectively. The sensible heating curve (a plot between pot water temperature and time) from the load test is used for determination of F 2 . An accurate determination of F 2 is necessary for making the correct and reliable assessment of solar cooker performance. In the present work, the thermal analysis has been carried out to simulate the sensible heating curves for different loads of water in the commercially available, fibre body double-glazed box type solar cooker (size 0.245 m 2 ) by using the heat balance equation. The comparison between the simulated and experimental sensible heating curves is presented. The close agreement in the results shows that the simulated heating curve can be employed for predicting the thermal performance (or F 2 ) of the solar cooker. The F 2 for different loads of water in the solar cooker have been obtained using the computer simulation, while considering the variable overall heat loss coefficient U L (a function of pot water temperature). The results indicate that F 2 increases linearly up to a load of 1.5 kg. Thereafter, the increase in the value of F 2 decreases gradually with the load

Determination of the positions and residues of the. delta. /sup + +/ and. delta. /sup 0/ poles. [Phase shifts,coulomb corrections

Energy Technology Data Exchange (ETDEWEB)

Vasan, S S [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics

1976-04-19

The poles and the associated residues in the ..pi..N P/sub 33/ amplitude corresponding to the resonances ..delta../sup + +/ and ..delta../sup 0/ are determined by fitting the ..pi../sup +/p and ..pi../sup -/p hadronic phase shifts from the Carter 73 analysis. The ..delta../sup + +/ and ..delta../sup 0/ pole positions are determined also from the nuclear phase shifts, these being the phase shifts made up of the hadronic phase shifts plus the Coulomb corrections. The pole positions obtained from the two sets of phase shifts are different, the differences being larger in the case of the ..delta../sup + +/.

Preparing the Dutch delta for future droughts: model based support in the national Delta Programme

Science.gov (United States)

ter Maat, Judith; Haasnoot, Marjolijn; van der Vat, Marnix; Hunink, Joachim; Prinsen, Geert; Visser, Martijn

2014-05-01

changing conditions. The plan commits to short term actions, and identifies signpost indicators and trigger values to assess if next actions of the identified policy pathways need to be implemented or if reassessment of the plan is needed. For example, river discharges could be measured to monitor changes in low discharges as a result of climate change, and assess whether policy options such as diverting more water the main fresh water lake (IJsselmeer) need to be implemented sooner or later or not at all. The adaptive plan of the Delta Programme will be presented in 2014. First lessons of this part of the Delta Programme can already be drawn: Both the complex and meta-model had its own purpose in each phase. The meta-model was particularly useful for identifying promising policy options and for consultation of stakeholders due to the instant response. The complex model had much more opportunities to assess impacts of regional policy actions, and was supported by regional stakeholders that recognized their areas better in this model. Different sector impact assessment modules are also included in the workflow of the complex model. However, the complex model has a long runtime (i.e. three days for 1 year simulation or more than 100 days for 35 year time series simulation), which makes it less suitable to support the dynamic policy process on instant demand and interactively.

Hydrodynamic modelling of a tidal delta wetland using an enhanced quasi-2D model

Science.gov (United States)

Wester, Sjoerd J.; Grimson, Rafael; Minotti, Priscilla G.; Booija, Martijn J.; Brugnach, Marcela

2018-04-01

Knowledge about the hydrological regime of wetlands is key to understand their physical and biological properties. Modelling hydrological and hydrodynamic processes within a wetland is therefore becoming increasingly important. 3D models have successfully modelled wetland dynamics but depend on very detailed bathymetry and land topography. Many 1D and 2D models of river deltas highly simplify the interaction between the river and wetland area or simply neglect the wetland area. This study proposes an enhanced quasi-2D modelling strategy that captures the interaction between river discharge and moon tides and the resulting hydrodynamics, while using the scarce data available. The water flow equations are discretised with an interconnected irregular cell scheme, in which a simplification of the 1D Saint-Venant equations is used to define the water flow between cells. The spatial structure of wetlands is based on the ecogeomorphology in complex estuarine deltas. The islands within the delta are modelled with levee cells, creek cells and an interior cell representing a shallow marsh wetland. The model is calibrated for an average year and the model performance is evaluated for another average year and additionally an extreme dry three-month period and an extreme wet three-month period. The calibration and evaluation are done based on two water level measurement stations and two discharge measurement stations, all located in the main rivers. Additional calibration is carried out with field water level measurements in a wetland area. Accurate simulations are obtained for both calibration and evaluation with high correlations between observed and simulated water levels and simulated discharges in the same order of magnitude as observed discharges. Calibration against field measurements showed that the model can successfully simulate the overflow mechanism in wetland areas. A sensitivity analysis for several wetland parameters showed that these parameters are all

Vacuum energies due to delta-like currents: multipole interactions

International Nuclear Information System (INIS)

Barone, F.A.; Borges, K.; Flores-Hidalgo, G.

2009-01-01

Full text. This work is devoted to a study about the quantum description of multipoles distributions by the use of external static currents concentrated along specific regions of space. For this task we consider models of bosonic quantum fields (scalar and electromagnetic fields) interacting with external currents which simulate the presence of charges, dipoles and quadrupoles distributions along D-dimensional static branes. Along the work we consider models in d+D+1 dimensions described by a quantum field coupled with an external current composed by two parts: the first one concentrated along a D-brane and the other one concentrated at a given point of space. This last part represents a point-like test-charge which is used to investigate the force field produced by the former one. Specifically, we consider models for the scalar field, with and without mass, coupled to currents describing distributions of charges, dipoles and quadrupoles currents along D-branes. These currents are given, respectively, by a Dirac's delta function, a directional derivative of a Dirac's delta function and the second derivative of a Dirac's delta function (coupled with a second rank tensor). We also extend the previous results for the electromagnetic case in order to bring them to more realistic contexts. We show that, as expected, there is an overall minus sing in comparing the results obtained for the scalar and electromagnetic fields. (author)

The Concentration Dependence of the (Delta)s Term in the Gibbs Free Energy Function: Application to Reversible Reactions in Biochemistry

Science.gov (United States)

Gary, Ronald K.

2004-01-01

The concentration dependence of (delta)S term in the Gibbs free energy function is described in relation to its application to reversible reactions in biochemistry. An intuitive and non-mathematical argument for the concentration dependence of the (delta)S term in the Gibbs free energy equation is derived and the applicability of the equation to…

78 FR 21491 - DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption...

Science.gov (United States)

2013-04-10

... SMALL BUSINESS ADMINISTRATION [License No. 02/02-0662, 02/02-0661] DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that DeltaPoint Capital IV, L.P. and DeltaPoint...

Mida pakub Delta? / Teele Kurm

Index Scriptorium Estoniae

Kurm, Teele

2011-01-01

Politsei- ja Piirivalveamet võtab kasutusele ühise Siseministeeriumi infotehnoloogia- ja arenduskeskuse ning Webmedia AS koostööna loodud dokumendihaldussüsteemi Delta. Kust sai Delta oma nime? Projekti "Dokumendihaldussüsteemi juurutamine Siseministeeriumi haldusalas" eesmärgid

Modeling ionospheric foF 2 response during geomagnetic storms using neural network and linear regression techniques

Science.gov (United States)

Tshisaphungo, Mpho; Habarulema, John Bosco; McKinnell, Lee-Anne

2018-06-01

In this paper, the modeling of the ionospheric foF 2 changes during geomagnetic storms by means of neural network (NN) and linear regression (LR) techniques is presented. The results will lead to a valuable tool to model the complex ionospheric changes during disturbed days in an operational space weather monitoring and forecasting environment. The storm-time foF 2 data during 1996-2014 from Grahamstown (33.3°S, 26.5°E), South Africa ionosonde station was used in modeling. In this paper, six storms were reserved to validate the models and hence not used in the modeling process. We found that the performance of both NN and LR models is comparable during selected storms which fell within the data period (1996-2014) used in modeling. However, when validated on storm periods beyond 1996-2014, the NN model gives a better performance (R = 0.62) compared to LR model (R = 0.56) for a storm that reached a minimum Dst index of -155 nT during 19-23 December 2015. We also found that both NN and LR models are capable of capturing the ionospheric foF 2 responses during two great geomagnetic storms (28 October-1 November 2003 and 6-12 November 2004) which have been demonstrated to be difficult storms to model in previous studies.

Analisis Risiko Finansial Dengan Metode Simulasi Monte Carlo (Studi Kasus: Pt. Phase Delta Control

Directory of Open Access Journals (Sweden)

Atikah Aghdhi Pratiwi

2016-10-01

Full Text Available Basically, the purpose of a company is make a profit and enrich the owners of the company. This is manifested by development and achievement of good performance, both in financial and operational perspective. But in reality, not all of companies can achieve good performance. One of them is because exposure of risk. This could threaten achievement of the objectives and existence of the company. Therefore, companies need to have an idea related to possible condition and financial projection in future periods that are affected by risk. One of the possible method is Monte Carlo Simulation. Research will be conducted at PT. Phase Delta Control with historical data related to production/sales volume, cost of production and selling price. Historical data will be used as Monte Carlo Simulation with random numbers that describe probability of each risk variables describing reality. The main result is estimated profitability of PT. Phase Delta Control in given period. Profit estimation will be uncertain variable due to some uncertainty

The Simulation and Correction to the Brain Deformation Based on the Linear Elastic Model in IGS

Institute of Scientific and Technical Information of China (English)

MU Xiao-lan; SONG Zhi-jian

2004-01-01

@@ The brain deformation is a vital factor affecting the precision of the IGS and it becomes a hotspot to simulate and correct the brain deformation recently.The research organizations, which firstly resolved the brain deformation with the physical models, have the Image Processing and Analysis department of Yale University, Biomedical Modeling Lab of Vanderbilt University and so on. The former uses the linear elastic model; the latter uses the consolidation model.The linear elastic model only needs to drive the model using the surface displacement of exposed brain cortex,which is more convenient to be measured in the clinic.

Impacts of Irrigation Practices on Groundwater Recharge in Mississippi Delta Using coupled SWAT-MODFLOW Model

Science.gov (United States)

Gao, F.; Feng, G.; Han, M.; Jenkins, J.; Ouyang, Y.

2017-12-01

The Lower Mississippi River alluvial plain (refers to as MS Delta), located in the northwest state of Mississippi, is one of the most productive agricultural region in the U.S. The primary crops grown in this region are soybean, corn, cotton, and rice. Approximately 80% water from the alluvial aquifer in MS Delta are withdrawn for irrigation, which makes it the most used aquifer in the State. As a result, groundwater level has declined > 6 m since 1970, which threaten the sustainability of irrigated agriculture in this region. The objectives of this study were to: 1) couple the SWAT and MODFLOW then calibrate and validate the incorporated model outputs for stream flow, groundwater level and evapotranspiration (ET) in MS Delta; 2) simulate the groundwater recharge as affected by a) conventional irrigation scheme, b) no irrigation scheme, c) ET based and soil moisture based full irrigation schedules using all groundwater, and d) ET and soil moisture based full irrigation schedule using different percentages of surface and ground water. Results indicated that the coupled model performed well during the calibration and validation for daily stream flow at three USGS gauge stations. (R2=0.7; Nash-Sutcliffe efficiency (NSE) varied from 0.6 to 0.7; Root Mean Square Error (RMSE) ranged from 20 to 27 m3/s). The values of determination coefficient R2 for groundwater level were 0.95 for calibration and 0.88 for validation, their NSE values were 0.99 and 0.93, respectively. The values of RMSE for groundwater level during the calibration and validation period were 0.51 and 0.59 m. The values of R2, NSE and RMSE between SWAT-MODFLOW simulated actual evapotranspiration (ET) and remote sensing evapotranspiration (ET) were 0.52, 0.51 and 28.1 mm. The simulated total average monthly groundwater recharge had lower values of 19 mm/month in the crop season than 30 mm/month in the crop off-growing season. The SWAT-MODFLOW can be a useful tool for not only simulating the recharge in MS

The dynamics of a nonlinear relationship between crude oil spot and futures prices. A multivariate threshold regression approach

International Nuclear Information System (INIS)

Huang, Bwo-Nung; Yang, C.W.; Hwang, M.J.

2009-01-01

This paper segments daily data from January of 1986 to April of 2007 into three periods based on certain important events. Both periods I and II indicate that the spot prices in general are higher than futures prices as was well-known in the literature. Only period-III (2001/9/11-2007/4/30) displays a reverse phenomenon: futures prices, in general, exceed spot prices. When the absolute value of a basis (futures-spot) is greater than the threshold value in the arbitrage area (regime 1 and 3), at least one of the error correction coefficients, representing adjustment towards equilibrium, is statistically significant. That is, there exists a tendency in the oil market in which prices move toward equilibrium. With respect to the short-run dynamic interaction between spot price change ((delta)s t ) and futures price change ((delta)f t ), our results indicate that when the spot price is higher than futures price, and the basis is less than certain threshold value (regime 3), there exists at least one causal relationship between (delta)s t and (delta)f t . Conversely, when the futures price is higher than spot price and the basis is higher than certain threshold value (regime 1), there exists at least one causal relationship between (delta)s t and (delta)f t . Finally, we use the method suggested by Diebold and Mariano [Diebold, Francis X., Mariano, Roberto S., 1995. Comparing predictive accuracy. Journal of Business and Economic Statistics 13 (3), 253-263] to compare the predictive power between the linear and nonlinear models. Our empirical results indicate that the in-sample prediction of the nonlinear model is clearly superior to that of the linear model. (author)

Changes in the areal extents of the Athabasca River, Birch River, and Cree Creek Deltas, 1950-2014, Peace-Athabasca Delta, Canada

Science.gov (United States)

Timoney, Kevin; Lee, Peter

2016-04-01

Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.

An analytical framework for strategic delta planning

NARCIS (Netherlands)

Seijger, C.; Douven, W.; Halsema, van G.; Hermans, L.; Evers, J.; Phi, H.L.; Khan, M.F.; Brunner, J.; Pols, L.; Ligtvoet, W.; Koole, S.; Slager, K.; Vermoolen, M.S.; Hasan, S.; Thi Minh Hoang, Vo

2017-01-01

Sectoral planning on water, agriculture and urban development has not been able to prevent increased flood risks and environmental degradation in many deltas. Governments conceive strategic delta planning as a promising planning approach and develop strategic delta plans. Such plans are linked to

Binding of sodium dodecyl sulfate with linear and branched polyethyleneimines in aqueous solution at different pH values.

Science.gov (United States)

Wang, Hao; Wang, Yilin; Yan, Haike; Zhang, Jin; Thomas, Robert K

2006-02-14

Isothermal titration microcalorimetry (ITC), conductivity, and turbidity measurements have been carried out to study the interaction of sodium dodecyl sulfate (SDS) with polyethyleneimines (PEI) including linear PEI and branched PEI at different pH values of 3, 7, and 10. In all cases, the polymers show a remarkable affinity toward SDS. At pH 3, the polymer PEI is a strong polycation, and the binding is dominated by electrostatic 1:1 charge neutralization with the anionic surfactant. At pH 7, the electrostatic attraction between SDS and PEI is weak, and the hydrophobic interaction becomes stronger. At the natural pH of 10, PEI is essentially nonionic and binds SDS in the form of polymer-bound surfactant aggregates. The charge neutralization concentration (C1) of SDS for the PEI-SDS complex can be derived from the curves of variation of the enthalpy, conductivity, and turbidity with SDS concentration. There is good agreement between the results from the three methods and all show a decrease with increasing pH. The total interaction enthalpies (deltaH(total)) of PEI with SDS are obtained from the observed enthalpy curves and the difference enthalpy (deltaH*) between the total enthalpy of branched PEI with SDS, and the total enthalpy of linear PEI with SDS can be derived from the obtained deltaH(total). The difference deltaH* increases dramatically as pH increases, which indicates that the interactions are different for linear PEI and branched PEI at high pH values. A schematic map of the different states of aggregation is presented.

Fatigue damage estimation in non-linear systems using a combination of Monte Carlo simulation and the First Order Reliability Method

DEFF Research Database (Denmark)

Jensen, Jørgen Juncher

2015-01-01

For non-linear systems the estimation of fatigue damage under stochastic loadings can be rather time-consuming. Usually Monte Carlo simulation (MCS) is applied, but the coefficient-of-variation (COV) can be large if only a small set of simulations can be done due to otherwise excessive CPU time...

Spatio-temporal distributions of delta¹⁸O, delta D and salinity in the Arabian Sea: Identifying processes and controls

Digital Repository Service at National Institute of Oceanography (India)

Deshpande, R.D; Muraleedharan, P.M.; Singh, R.L.; Kumar, B.; Rao, M.S.; Dave, M.; Sivakumar, K.U.; Gupta, S.K.

the geographic distributions of the delta^18O and S; (2) in spite of a large scatter, a statistically significant delta^18O–S relationship can be identified in much of the investigated part of the AS; (3) the delta^18O– delta...