Externally perturbed unstable systems
International Nuclear Information System (INIS)
Posch, H.A.; Narnhofer, H.; Thirring, W.
1991-01-01
We discuss computer solutions of Newton's equation of motion for unstable systems in a container with time-dependent walls. An expansion leads to the formation of a cluster and a significant increase of the temperature. The question of entropy increase for expansion and compression of the system and the related problem of the feasibility of a perpetuum mobile of the second kind are investigated. (Authors)
Perturbative approach to Markovian open quantum systems.
Li, Andy C Y; Petruccione, F; Koch, Jens
2014-05-08
The exact treatment of Markovian open quantum systems, when based on numerical diagonalization of the Liouville super-operator or averaging over quantum trajectories, is severely limited by Hilbert space size. Perturbation theory, standard in the investigation of closed quantum systems, has remained much less developed for open quantum systems where a direct application to the Lindblad master equation is desirable. We present such a perturbative treatment which will be useful for an analytical understanding of open quantum systems and for numerical calculation of system observables which would otherwise be impractical.
Euclidean null controllability of perturbed infinite delay systems with ...
African Journals Online (AJOL)
Euclidean null controllability of perturbed infinite delay systems with limited control. ... Open Access DOWNLOAD FULL TEXT ... The results are established by placing conditions on the perturbation function which guarantee that, if the linear control base system is completely Euclidean controllable, then the perturbed system ...
Quantum system lifetimes and measurement perturbations
International Nuclear Information System (INIS)
Najakov, E.
1977-05-01
The recently proposed description of quantum system decay in terms of repeated measurement perturbations is modified. The possibility of retarded reductions to a unique quantum state, due to ineffective localization of the decay products at initial time measurements, is simply taken into account. The exponential decay law is verified again. A modified equation giving the observed lifetime in terms of unperturbed quantum decay law, measurement frequency and reduction law is derived. It predicts deviations of the observed lifetime from the umperturbed one, together with a dependence on experimental procedures. The influence of different model unperturbed decay laws and reduction laws on this effect is studied
Non-perturbative description of quantum systems
Feranchuk, Ilya; Le, Van-Hoang; Ulyanenkov, Alexander
2015-01-01
This book introduces systematically the operator method for the solution of the Schrödinger equation. This method permits to describe the states of quantum systems in the entire range of parameters of Hamiltonian with a predefined accuracy. The operator method is unique compared with other non-perturbative methods due to its ability to deliver in zeroth approximation the uniformly suitable estimate for both ground and excited states of quantum system. The method has been generalized for the application to quantum statistics and quantum field theory. In this book, the numerous applications of operator method for various physical systems are demonstrated. Simple models are used to illustrate the basic principles of the method which are further used for the solution of complex problems of quantum theory for many-particle systems. The results obtained are supplemented by numerical calculations, presented as tables and figures.
Perturbation Theory for Open Two-Level Nonlinear Quantum Systems
International Nuclear Information System (INIS)
Zhang Zhijie; Jiang Dongguang; Wang Wei
2011-01-01
Perturbation theory is an important tool in quantum mechanics. In this paper, we extend the traditional perturbation theory to open nonlinear two-level systems, treating decoherence parameter γ as a perturbation. By this virtue, we give a perturbative solution to the master equation, which describes a nonlinear open quantum system. The results show that for small decoherence rate γ, the ratio of the nonlinear rate C to the tunneling coefficient V (i.e., r = C/V) determines the validity of the perturbation theory. For small ratio r, the perturbation theory is valid, otherwise it yields wrong results. (general)
Output synchronization of chaotic systems under nonvanishing perturbations
Energy Technology Data Exchange (ETDEWEB)
Lopez-Mancilla, Didier [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de los Lagos, Universidad de Guadalajara (CULagos-UdeG), Enrique Diaz de Leon s/n, 47460 Lagos de Moreno, Jal. (Mexico)], E-mail: didier@uabc.mx; Cruz-Hernandez, Cesar [Electronics and Telecommunications Department, Scientific Research and Advanced Studies of Ensenada (CICESE), Km. 107, Carretera Tijuana-Ensenada, 22860 Ensenada, B.C. (Mexico)], E-mail: ccruz@cicese.mx
2008-08-15
In this paper, an analysis for chaos synchronization under nonvanishing perturbations is presented. In particular, we use model-matching approach from nonlinear control theory for output synchronization of identical and nonidentical chaotic systems under nonvanishing perturbations in a master-slave configuration. We show that the proposed approach is indeed suitable to synchronize a class of perturbed slaves with a chaotic master system; that is the synchronization error trajectories remain bounded if the perturbations satisfy some conditions. In order to illustrate this robustness synchronization property, we present two cases of study: (i) for identical systems, a pair of coupled Roessler systems, the first like a master and the other like a perturbed slave, and (ii) for nonidentical systems, a Chua's circuit driving a Roessler/slave system with a perturbed control law, in both cases a quantitative analysis on the perturbation is included.
Output synchronization of chaotic systems under nonvanishing perturbations
International Nuclear Information System (INIS)
Lopez-Mancilla, Didier; Cruz-Hernandez, Cesar
2008-01-01
In this paper, an analysis for chaos synchronization under nonvanishing perturbations is presented. In particular, we use model-matching approach from nonlinear control theory for output synchronization of identical and nonidentical chaotic systems under nonvanishing perturbations in a master-slave configuration. We show that the proposed approach is indeed suitable to synchronize a class of perturbed slaves with a chaotic master system; that is the synchronization error trajectories remain bounded if the perturbations satisfy some conditions. In order to illustrate this robustness synchronization property, we present two cases of study: (i) for identical systems, a pair of coupled Roessler systems, the first like a master and the other like a perturbed slave, and (ii) for nonidentical systems, a Chua's circuit driving a Roessler/slave system with a perturbed control law, in both cases a quantitative analysis on the perturbation is included
Effects of Wildfire on Fluvial Sediment Regime through Perturbations in Dry-Ravel
Florsheim, J. L.; Chin, A.; Kinoshita, A. M.; Nourbakhshbeidokhti, S.; Storesund, R.; Keller, E. A.
2015-12-01
In steep chaparral ecosystems with Mediterranean climate, dry ravel is a natural process resulting from wildfire disturbance that supplies sediment to fluvial systems. When dense chaparral vegetation burns, sediment accumulated on steep hillslopes is released for dry-season transport (dry ravel) down steep hillslopes during or soon after the wildfire. Results of a field study in southern California's Transverse Ranges illustrate the effect of wildfire on fluvial sediment regime in an unregulated chaparral system. Big Sycamore Canyon in the steep Santa Monica Mountains burned during the May 2013 Springs Fire and experienced one small sediment-transporting stormflow during the following winter. We conducted pre- and post-storm field campaigns during the fall and winter following the fire to quantify the effect of wildfire on the fluvial sediment regime. We utilized a sediment mass balance approach in which: 1) sediment supply, consisting primarily of dry ravel-derived deposits composed of relatively fine grained-sediment, was measured in the upstream basin and in the hillslope-channel margin adjacent to the study reach; 2) changes in storage in the study reach were quantified by analyzing the difference between pre- and post-storm channel topography derived from Terrestrial LiDAR Scanning (TLS) and field surveys; and 3) transport from the study reach was estimated as the difference between supply and change in storage where uncertainty is estimated using calculated sediment transport as a comparison. Results demonstrate channel deposition caused by changes in the short-term post-wildfire sediment regime. The increased sediment supply and storage are associated with significant changes in morphology, channel bed-material characteristics, and ecology. These results suggest that dry-ravel processes are an important factor to consider in post-wildfire sediment management.
Monte Carlo technique for local perturbations in multiplying systems
International Nuclear Information System (INIS)
Bernnat, W.
1974-01-01
The use of the Monte Carlo method for the calculation of reactivity perturbations in multiplying systems due to changes in geometry or composition requires a correlated sampling technique to make such calculations economical or in the case of very small perturbations even feasible. The technique discussed here is suitable for local perturbations. Very small perturbation regions will be treated by an adjoint mode. The perturbation of the source distribution due to the changed system and its reaction on the reactivity worth or other values of interest is taken into account by a fission matrix method. The formulation of the method and its application are discussed. 10 references. (U.S.)
Synchronizing the noise-perturbed Lue chaotic system
International Nuclear Information System (INIS)
Zhang Yan; Chen Shihua; Zhou Hong
2009-01-01
In this paper, synchronization between unidirectionally coupled Lue chaotic systems with noise perturbation is investigated theoretically and numerically. Sufficient conditions of synchronization between these noise-perturbed systems are established by means of the so-called sliding mode control method. Some numerical simulations are also included to visualize the effectiveness and the feasibility of the developed approach.
One dimensional systems with singular perturbations
International Nuclear Information System (INIS)
Alvarez, J J; Gadella, M; Nieto, L M; Glasser, L M; Lara, L P
2011-01-01
This paper discusses some one dimensional quantum models with singular perturbations. Eventually, a mass discontinuity is added at the points that support the singular perturbations. The simplest model includes an attractive singular potential with a mass jump both located at the origin. We study the form of the only bound state. Another model exhibits a hard core at the origin plus one or more repulsive deltas with mass jumps at the points supporting these deltas. We study the location and the multiplicity of these resonances for the case of one or two deltas and settle the basis for a generalization. Finally, we consider the harmonic oscillator and the infinite square well plus a singular potential at the origin. We see how the energy of bound states is affected by the singular perturbation.
Modularity and the spread of perturbations in complex dynamical systems.
Kolchinsky, Artemy; Gates, Alexander J; Rocha, Luis M
2015-12-01
We propose a method to decompose dynamical systems based on the idea that modules constrain the spread of perturbations. We find partitions of system variables that maximize "perturbation modularity," defined as the autocovariance of coarse-grained perturbed trajectories. The measure effectively separates the fast intramodular from the slow intermodular dynamics of perturbation spreading (in this respect, it is a generalization of the "Markov stability" method of network community detection). Our approach captures variation of modular organization across different system states, time scales, and in response to different kinds of perturbations: aspects of modularity which are all relevant to real-world dynamical systems. It offers a principled alternative to detecting communities in networks of statistical dependencies between system variables (e.g., "relevance networks" or "functional networks"). Using coupled logistic maps, we demonstrate that the method uncovers hierarchical modular organization planted in a system's coupling matrix. Additionally, in homogeneously coupled map lattices, it identifies the presence of self-organized modularity that depends on the initial state, dynamical parameters, and type of perturbations. Our approach offers a powerful tool for exploring the modular organization of complex dynamical systems.
Scaling laws for perturbations in the ocean-atmosphere system following large CO2 emissions
Towles, N.; Olson, P.; Gnanadesikan, A.
2015-07-01
Scaling relationships are found for perturbations to atmosphere and ocean variables from large transient CO2 emissions. Using the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir (LOSCAR) model (Zeebe et al., 2009; Zeebe, 2012b), we calculate perturbations to atmosphere temperature, total carbon, ocean temperature, total ocean carbon, pH, alkalinity, marine-sediment carbon, and carbon-13 isotope anomalies in the ocean and atmosphere resulting from idealized CO2 emission events. The peak perturbations in the atmosphere and ocean variables are then fit to power law functions of the form of γ DαEβ, where D is the event duration, E is its total carbon emission, and γ is a coefficient. Good power law fits are obtained for most system variables for E up to 50 000 PgC and D up to 100 kyr. Although all of the peak perturbations increase with emission rate E/D, we find no evidence of emission-rate-only scaling, α + β = 0. Instead, our scaling yields α + β ≃ 1 for total ocean and atmosphere carbon and 0 < α + β < 1 for most of the other system variables.
Scaling laws for perturbations in the ocean–atmosphere system following large CO2 emissions
Directory of Open Access Journals (Sweden)
N. Towles
2015-07-01
Full Text Available Scaling relationships are found for perturbations to atmosphere and ocean variables from large transient CO2 emissions. Using the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir (LOSCAR model (Zeebe et al., 2009; Zeebe, 2012b, we calculate perturbations to atmosphere temperature, total carbon, ocean temperature, total ocean carbon, pH, alkalinity, marine-sediment carbon, and carbon-13 isotope anomalies in the ocean and atmosphere resulting from idealized CO2 emission events. The peak perturbations in the atmosphere and ocean variables are then fit to power law functions of the form of γ DαEβ, where D is the event duration, E is its total carbon emission, and γ is a coefficient. Good power law fits are obtained for most system variables for E up to 50 000 PgC and D up to 100 kyr. Although all of the peak perturbations increase with emission rate E/D, we find no evidence of emission-rate-only scaling, α + β = 0. Instead, our scaling yields α + β ≃ 1 for total ocean and atmosphere carbon and 0 < α + β < 1 for most of the other system variables.
Control system analysis for the perturbed linear accelerator rf system
Sung Il Kwon
2002-01-01
This paper addresses the modeling problem of the linear accelerator RF system in SNS. Klystrons are modeled as linear parameter varying systems. The effect of the high voltage power supply ripple on the klystron output voltage and the output phase is modeled as an additive disturbance. The cavity is modeled as a linear system and the beam current is modeled as the exogenous disturbance. The output uncertainty of the low level RF system which results from the uncertainties in the RF components and cabling is modeled as multiplicative uncertainty. Also, the feedback loop uncertainty and digital signal processing signal conditioning subsystem uncertainties are lumped together and are modeled as multiplicative uncertainty. Finally, the time delays in the loop are modeled as a lumped time delay. For the perturbed open loop system, the closed loop system performance, and stability are analyzed with the PI feedback controller.
CONTROL SYSTEM ANALYSIS FOR THE PERTURBED LINEAR ACCELERATOR RF SYSTEM
International Nuclear Information System (INIS)
SUNG-IL KWON; AMY H. REGAN
2002-01-01
This paper addresses the modeling problem of the linear accelerator RF system in SNS. Klystrons are modeled as linear parameter varying systems. The effect of the high voltage power supply ripple on the klystron output voltage and the output phase is modeled as an additive disturbance. The cavity is modeled as a linear system and the beam current is modeled as the exogenous disturbance. The output uncertainty of the low level RF system which results from the uncertainties in the RF components and cabling is modeled as multiplicative uncertainty. Also, the feedback loop uncertainty and digital signal processing signal conditioning subsystem uncertainties are lumped together and are modeled as multiplicative uncertainty. Finally, the time delays in the loop are modeled as a lumped time delay. For the perturbed open loop system, the closed loop system performance, and stability are analyzed with the PI feedback controller
Optimized Perturbation Theory for Wave Functions of Quantum Systems
International Nuclear Information System (INIS)
Hatsuda, T.; Tanaka, T.; Kunihiro, T.
1997-01-01
The notion of the optimized perturbation, which has been successfully applied to energy eigenvalues, is generalized to treat wave functions of quantum systems. The key ingredient is to construct an envelope of a set of perturbative wave functions. This leads to a condition similar to that obtained from the principle of minimal sensitivity. Applications of the method to the quantum anharmonic oscillator and the double well potential show that uniformly valid wave functions with correct asymptotic behavior are obtained in the first-order optimized perturbation even for strong couplings. copyright 1997 The American Physical Society
Performance of Power Systems under Sustained Random Perturbations
Directory of Open Access Journals (Sweden)
Humberto Verdejo
2014-01-01
Full Text Available This paper studies linear systems under sustained additive random perturbations. The stable operating point of an electric power system is replaced by an attracting stationary solution if the system is subjected to (small random additive perturbations. The invariant distribution of this stationary solution gives rise to several performance indices that measure how well the system copes with the randomness. These indices are introduced, showing how they can be used for the optimal tuning of system parameters in the presence of noise. Results on a four-generator two-area system are presented and discussed.
Invariant exchange perturbation theory for multicenter systems: Time-dependent perturbations
International Nuclear Information System (INIS)
Orlenko, E. V.; Evstafev, A. V.; Orlenko, F. E.
2015-01-01
A formalism of exchange perturbation theory (EPT) is developed for the case of interactions that explicitly depend on time. Corrections to the wave function obtained in any order of perturbation theory and represented in an invariant form include exchange contributions due to intercenter electron permutations in complex multicenter systems. For collisions of atomic systems with an arbitrary type of interaction, general expressions are obtained for the transfer (T) and scattering (S) matrices in which intercenter electron permutations between overlapping nonorthogonal states belonging to different centers (atoms) are consistently taken into account. The problem of collision of alpha particles with lithium atoms accompanied by the redistribution of electrons between centers is considered. The differential and total charge-exchange cross sections of lithium are calculated
Surface sedimentation at permeable pavement systems
DEFF Research Database (Denmark)
Støvring, Jan; Dam, Torben; Jensen, Marina Bergen
2018-01-01
Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance of restorat......Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance...
Singular perturbations introduction to system order reduction methods with applications
Shchepakina, Elena; Mortell, Michael P
2014-01-01
These lecture notes provide a fresh approach to investigating singularly perturbed systems using asymptotic and geometrical techniques. It gives many examples and step-by-step techniques, which will help beginners move to a more advanced level. Singularly perturbed systems appear naturally in the modelling of many processes that are characterized by slow and fast motions simultaneously, for example, in fluid dynamics and nonlinear mechanics. This book’s approach consists in separating out the slow motions of the system under investigation. The result is a reduced differential system of lesser order. However, it inherits the essential elements of the qualitative behaviour of the original system. Singular Perturbations differs from other literature on the subject due to its methods and wide range of applications. It is a valuable reference for specialists in the areas of applied mathematics, engineering, physics, biology, as well as advanced undergraduates for the earlier parts of the book, and graduate stude...
GENP-2, Program System for Integral Reactor Perturbation
International Nuclear Information System (INIS)
Boioli, A.; Cecchini, G.P.
1975-01-01
1 - Description of problem or function: GENP-2 is a system of programs that use 'generalized perturbation theory' to calculate the perturbations of reactor integral characteristics which can be expressed by means of ratios between linear or bilinear functionals of the real and/or adjoint fluxes (e.g. reaction rate ratios), due to cross section perturbations. 2 - Method of solution: GENP-2 consists of the following codes: DDV, SORCI, CIAP-PMN and GLOBP-2D. DDV calculates the real or adjoint fluxes and power distribution using multigroup diffusion theory in 2-dimensions. SORCI uses the fluxes from DDV to calculate the real and/or adjoint general perturbation sources. CIAP-PMN reads the sources from SORCI and uses them in the real or adjoint generalised importance calculations (2 dimensions, multi- group diffusion). GLOBP-2D uses the importance calculated by CIAP-PMN, and the fluxes calculated by DDV, in generalised perturbation expressions to calculate the perturbation in the quantity of interest. 3 - Restrictions on the complexity of the problem: DDV although variably dimensioned has the following restrictions: - max. number of mesh points 6400; - max. number of mesh points in 1-dimension 81; - max. number of regions 6400; - max. number of energy groups 100; - if power distribution calculated, product of number of groups and number of regions 2500. The other programs have the same restrictions if applicable
Eigenstructure of of singular systems. Perturbation analysis of simple eigenvalues
García Planas, María Isabel; Tarragona Romero, Sonia
2014-01-01
The problem to study small perturbations of simple eigenvalues with a change of parameters is of general interest in applied mathematics. After to introduce a systematic way to know if an eigenvalue of a singular system is simple or not, the aim of this work is to study the behavior of a simple eigenvalue of singular linear system family
Geometric singular perturbation analysis of systems with friction
DEFF Research Database (Denmark)
Bossolini, Elena
This thesis is concerned with the application of geometric singular perturbation theory to mechanical systems with friction. The mathematical background on geometric singular perturbation theory, on the blow-up method, on non-smooth dynamical systems and on regularization is presented. Thereafter......, two mechanical problems with two diﬀerent formulations of the friction force are introduced and analysed. The ﬁrst mechanical problem is a one-dimensional spring-block model describing earthquake faulting. The dynamics of earthquakes is naturally a multiple timescale problem: the timescale...... scales. The action of friction is generally explained as the loss and restoration of linkages between the surface asperities at the molecular scale. However, the consequences of friction are noticeable at much larger scales, like hundreds of kilometers. By using geometric singular perturbation theory...
Melnikov processes and chaos in randomly perturbed dynamical systems
Yagasaki, Kazuyuki
2018-07-01
We consider a wide class of randomly perturbed systems subjected to stationary Gaussian processes and show that chaotic orbits exist almost surely under some nondegenerate condition, no matter how small the random forcing terms are. This result is very contrasting to the deterministic forcing case, in which chaotic orbits exist only if the influence of the forcing terms overcomes that of the other terms in the perturbations. To obtain the result, we extend Melnikov’s method and prove that the corresponding Melnikov functions, which we call the Melnikov processes, have infinitely many zeros, so that infinitely many transverse homoclinic orbits exist. In addition, a theorem on the existence and smoothness of stable and unstable manifolds is given and the Smale–Birkhoff homoclinic theorem is extended in an appropriate form for randomly perturbed systems. We illustrate our theory for the Duffing oscillator subjected to the Ornstein–Uhlenbeck process parametrically.
Singular perturbation analysis of relaxation oscillations in reactor systems
International Nuclear Information System (INIS)
Ward, M.E.; Lee, J.C.
1987-01-01
A singular perturbation method for the analysis of large power oscillations in nuclear reactors is applied to obtain phase-plane solutions of the Ergen-Weinberg model. The system equations, recast in an appropriate form, directly give a first approximation to the closed trajectory in which the system behaviour is idealized as relaxation oscillations. Further approximations in the phase plane are determined using separate perturbation series on individual parts of the oscillation, with variations in the assignment of dependent and independent variables to consistently obtain convergent series. The accuracy of each order of the phase-plane solution increases with the magnitude of the power pulse in the actual physical situation. For realistic reactor conditions, both the trajectory and period of oscillation are well predicted using the first two terms of each perturbation series
Admissible perturbations and false instabilities in PT -symmetric quantum systems
Znojil, Miloslav
2018-03-01
One of the most characteristic mathematical features of the PT -symmetric quantum mechanics is the explicit Hamiltonian dependence of its physical Hilbert space of states H =H (H ) . Some of the most important physical consequences are discussed, with emphasis on the dynamical regime in which the system is close to phase transition. Consistent perturbation treatment of such a regime is proposed. An illustrative application of the innovated perturbation theory to a non-Hermitian but PT -symmetric user-friendly family of J -parametric "discrete anharmonic" quantum Hamiltonians H =H (λ ⃗) is provided. The models are shown to admit the standard probabilistic interpretation if and only if the parameters remain compatible with the reality of the spectrum, λ ⃗∈D(physical ) . In contradiction to conventional wisdom, the systems are then shown to be stable with respect to admissible perturbations, inside the domain D(physical ), even in the immediate vicinity of the phase-transition boundaries ∂ D(physical ) .
Sinusoidal error perturbation reveals multiple coordinate systems for sensorymotor adaptation.
Hudson, Todd E; Landy, Michael S
2016-02-01
A coordinate system is composed of an encoding, defining the dimensions of the space, and an origin. We examine the coordinate encoding used to update motor plans during sensory-motor adaptation to center-out reaches. Adaptation is induced using a novel paradigm in which feedback of reach endpoints is perturbed following a sinewave pattern over trials; the perturbed dimensions of the feedback were the axes of a Cartesian coordinate system in one session and a polar coordinate system in another session. For center-out reaches to randomly chosen target locations, reach errors observed at one target will require different corrections at other targets within Cartesian- and polar-coded systems. The sinewave adaptation technique allowed us to simultaneously adapt both dimensions of each coordinate system (x-y, or reach gain and angle), and identify the contributions of each perturbed dimension by adapting each at a distinct temporal frequency. The efficiency of this technique further allowed us to employ perturbations that were a fraction the size normally used, which avoids confounding automatic adaptive processes with deliberate adjustments made in response to obvious experimental manipulations. Subjects independently corrected errors in each coordinate in both sessions, suggesting that the nervous system encodes both a Cartesian- and polar-coordinate-based internal representation for motor adaptation. The gains and phase lags of the adaptive responses are not readily explained by current theories of sensory-motor adaptation. Copyright © 2015 Elsevier Ltd. All rights reserved.
Perturbation Biology: Inferring Signaling Networks in Cellular Systems
Miller, Martin L.; Gauthier, Nicholas P.; Jing, Xiaohong; Kaushik, Poorvi; He, Qin; Mills, Gordon; Solit, David B.; Pratilas, Christine A.; Weigt, Martin; Braunstein, Alfredo; Pagnani, Andrea; Zecchina, Riccardo; Sander, Chris
2013-01-01
We present a powerful experimental-computational technology for inferring network models that predict the response of cells to perturbations, and that may be useful in the design of combinatorial therapy against cancer. The experiments are systematic series of perturbations of cancer cell lines by targeted drugs, singly or in combination. The response to perturbation is quantified in terms of relative changes in the measured levels of proteins, phospho-proteins and cellular phenotypes such as viability. Computational network models are derived de novo, i.e., without prior knowledge of signaling pathways, and are based on simple non-linear differential equations. The prohibitively large solution space of all possible network models is explored efficiently using a probabilistic algorithm, Belief Propagation (BP), which is three orders of magnitude faster than standard Monte Carlo methods. Explicit executable models are derived for a set of perturbation experiments in SKMEL-133 melanoma cell lines, which are resistant to the therapeutically important inhibitor of RAF kinase. The resulting network models reproduce and extend known pathway biology. They empower potential discoveries of new molecular interactions and predict efficacious novel drug perturbations, such as the inhibition of PLK1, which is verified experimentally. This technology is suitable for application to larger systems in diverse areas of molecular biology. PMID:24367245
Computational singular perturbation analysis of stochastic chemical systems with stiffness
Wang, Lijin; Han, Xiaoying; Cao, Yanzhao; Najm, Habib N.
2017-04-01
Computational singular perturbation (CSP) is a useful method for analysis, reduction, and time integration of stiff ordinary differential equation systems. It has found dominant utility, in particular, in chemical reaction systems with a large range of time scales at continuum and deterministic level. On the other hand, CSP is not directly applicable to chemical reaction systems at micro or meso-scale, where stochasticity plays an non-negligible role and thus has to be taken into account. In this work we develop a novel stochastic computational singular perturbation (SCSP) analysis and time integration framework, and associated algorithm, that can be used to not only construct accurately and efficiently the numerical solutions to stiff stochastic chemical reaction systems, but also analyze the dynamics of the reduced stochastic reaction systems. The algorithm is illustrated by an application to a benchmark stochastic differential equation model, and numerical experiments are carried out to demonstrate the effectiveness of the construction.
Federal Laboratory Consortium — FUNCTION: Provides wideband in situ measurement capability of compressional wave speed and attenuation and their spatial variability in marine sediments.DESCRIPTION:...
Mapping how local perturbations influence systems-level brain dynamics.
Gollo, Leonardo L; Roberts, James A; Cocchi, Luca
2017-10-15
The human brain exhibits a distinct spatiotemporal organization that supports brain function and can be manipulated via local brain stimulation. Such perturbations to local cortical dynamics are globally integrated by distinct neural systems. However, it remains unclear how local changes in neural activity affect large-scale system dynamics. Here, we briefly review empirical and computational studies addressing how localized perturbations affect brain activity. We then systematically analyze a model of large-scale brain dynamics, assessing how localized changes in brain activity at the different sites affect whole-brain dynamics. We find that local stimulation induces changes in brain activity that can be summarized by relatively smooth tuning curves, which relate a region's effectiveness as a stimulation site to its position within the cortical hierarchy. Our results also support the notion that brain hubs, operating in a slower regime, are more resilient to focal perturbations and critically contribute to maintain stability in global brain dynamics. In contrast, perturbations of peripheral regions, characterized by faster activity, have greater impact on functional connectivity. As a parallel with this region-level result, we also find that peripheral systems such as the visual and sensorimotor networks were more affected by local perturbations than high-level systems such as the cingulo-opercular network. Our findings highlight the importance of a periphery-to-core hierarchy to determine the effect of local stimulation on the brain network. This study also provides novel resources to orient empirical work aiming at manipulating functional connectivity using non-invasive brain stimulation. Copyright © 2017 Elsevier Inc. All rights reserved.
Stochastic perturbations in open chaotic systems: random versus noisy maps.
Bódai, Tamás; Altmann, Eduardo G; Endler, Antonio
2013-04-01
We investigate the effects of random perturbations on fully chaotic open systems. Perturbations can be applied to each trajectory independently (white noise) or simultaneously to all trajectories (random map). We compare these two scenarios by generalizing the theory of open chaotic systems and introducing a time-dependent conditionally-map-invariant measure. For the same perturbation strength we show that the escape rate of the random map is always larger than that of the noisy map. In random maps we show that the escape rate κ and dimensions D of the relevant fractal sets often depend nonmonotonically on the intensity of the random perturbation. We discuss the accuracy (bias) and precision (variance) of finite-size estimators of κ and D, and show that the improvement of the precision of the estimations with the number of trajectories N is extremely slow ([proportionality]1/lnN). We also argue that the finite-size D estimators are typically biased. General theoretical results are combined with analytical calculations and numerical simulations in area-preserving baker maps.
Performance optimization of queueing systems with perturbation realization
Xia, Li
2012-04-01
After the intensive studies of queueing theory in the past decades, many excellent results in performance analysis have been obtained, and successful examples abound. However, exploring special features of queueing systems directly in performance optimization still seems to be a territory not very well cultivated. Recent progresses of perturbation analysis (PA) and sensitivity-based optimization provide a new perspective of performance optimization of queueing systems. PA utilizes the structural information of queueing systems to efficiently extract the performance sensitivity information from a sample path of system. This paper gives a brief review of PA and performance optimization of queueing systems, focusing on a fundamental concept called perturbation realization factors, which captures the special dynamic feature of a queueing system. With the perturbation realization factors as building blocks, the performance derivative formula and performance difference formula can be obtained. With performance derivatives, gradient-based optimization can be derived, while with performance difference, policy iteration and optimality equations can be derived. These two fundamental formulas provide a foundation for performance optimization of queueing systems from a sensitivity-based point of view. We hope this survey may provide some inspirations on this promising research topic. © 2011 Elsevier B.V. All rights reserved.
Relaxation periodic solutions of one singular perturbed system with delay
Kashchenko, A. A.
2017-12-01
In this paper, we consider a singularly perturbed system of two differential equations with delay, simulating two coupled oscillators with a nonlinear compactly supported feedback. We reduce studying nonlocal dynamics of initial system to studying dynamics of special finite-dimensional mappings: rough stable (unstable) cycles of these mappings correspond to exponentially orbitally stable (unstable) relaxation solutions of initial problem. We show that dynamics of initial model depends on coupling coefficient crucially. Multistability is proved.
Control of a perturbed under-actuated mechanical system
Zayane, Chadia
2015-11-05
In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed high order sliding mode control architecture including a controller and differentiator allows to track accurately the predefined trajectory and to stabilize the internal dynamics. The robustness of the proposed approach is illustrated through different perturbation and output noise configurations.
Nonlinear PI control of chaotic systems using singular perturbation theory
International Nuclear Information System (INIS)
Wang Jiang; Wang Jing; Li Huiyan
2005-01-01
In this paper, we develop the nonlinear PI controllers for a class of chaotic systems based on singular perturbation theory. The original system is decomposed into two reduced order systems, to which the nonlinear uncertain terms belongs. In order to alleviate the deterioration of these nonlinear uncertainties, the nonlinear PI controllers are applied to each subsystem and combined to construct the composite controller for the full order system. The effectiveness and feasibility of the proposed control scheme is demonstrated through numerical simulations on the chaotic Chua's circuit
Collisional dynamics of perturbed particle disks in the solar system
Roberts, W. W.; Stewart, G. R.
1987-01-01
Investigations of the collisional evolution of particulate disks subject to the gravitational perturbation of a more massive particle orbiting within the disk are underway. Both numerical N-body simulations using a novel collision algorithm and analytical kinetic theory are being employed to extend our understanding of perturbed disks in planetary rings and during the formation of the solar system. Particular problems proposed for investigation are: (1) The development and testing of general criteria for a small moonlet to clear a gap and produce observable morphological features in planetary rings; (2) The development of detailed models of collisional damping of the wavy edges observed on the Encke division of Saturn's A ring; and (3) The determination of the extent of runaway growth of the few largest planetesimals during the early stages of planetary accretion.
Systems of evolution equations and the singular perturbation method
International Nuclear Information System (INIS)
Mika, J.
Several fundamental theorems are presented important for the solution of linear evolution equations in the Banach space. The algorithm is deduced extending the solution of the system of singularly perturbed evolution equations into an asymptotic series with respect to a small positive parameter. The asymptotic convergence is shown of an approximate solution to the accurate solution. Singularly perturbed evolution equations of the resonance type were analysed. The special role is considered of the asymptotic equivalence of P1 equations obtained as the first order approximation if the spherical harmonics method is applied to the linear Boltzmann equation, and the diffusion equations of the linear transport theory where the small parameter approaches zero. (J.B.)
Singular perturbation methods for nonlinear dynamic systems with time delays
International Nuclear Information System (INIS)
Hu, H.Y.; Wang, Z.H.
2009-01-01
This review article surveys the recent advances in the dynamics and control of time-delay systems, with emphasis on the singular perturbation methods, such as the method of multiple scales, the method of averaging, and two newly developed methods, the energy analysis and the pseudo-oscillator analysis. Some examples are given to demonstrate the advantages of the methods. The comparisons with other methods show that these methods lead to easier computations and higher accurate prediction on the local dynamics of time-delay systems near a Hopf bifurcation.
Perturbation to Unified Symmetry and Adiabatic Invariants for Relativistic Hamilton Systems
International Nuclear Information System (INIS)
Zhang Mingjiang; Fang Jianhui; Lu Kai; Pang Ting; Lin Peng
2009-01-01
Based on the concept of adiabatic invariant, the perturbation to unified symmetry and adiabatic invariants for relativistic Hamilton systems are studied. The definition of the perturbation to unified symmetry for the system is presented, and the criterion of the perturbation to unified symmetry is given. Meanwhile, the Noether adiabatic invariants, the generalized Hojman adiabatic invariants, and the Mei adiabatic invariants for the perturbed system are obtained. (general)
Controlling chaos in low and high dimensional systems with periodic parametric perturbations
International Nuclear Information System (INIS)
Mirus, K.A.; Sprott, J.C.
1998-06-01
The effect of applying a periodic perturbation to an accessible parameter of various chaotic systems is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic systems can result in limit cycles for relatively small perturbations. Such perturbations can also control or significantly reduce the dimension of high-dimensional systems. Initial application to the control of fluctuations in a prototypical magnetic fusion plasma device will be reviewed
Perturbation expansions of stochastic wavefunctions for open quantum systems
Ke, Yaling; Zhao, Yi
2017-11-01
Based on the stochastic unravelling of the reduced density operator in the Feynman path integral formalism for an open quantum system in touch with harmonic environments, a new non-Markovian stochastic Schrödinger equation (NMSSE) has been established that allows for the systematic perturbation expansion in the system-bath coupling to arbitrary order. This NMSSE can be transformed in a facile manner into the other two NMSSEs, i.e., non-Markovian quantum state diffusion and time-dependent wavepacket diffusion method. Benchmarked by numerically exact results, we have conducted a comparative study of the proposed method in its lowest order approximation, with perturbative quantum master equations in the symmetric spin-boson model and the realistic Fenna-Matthews-Olson complex. It is found that our method outperforms the second-order time-convolutionless quantum master equation in the whole parameter regime and even far better than the fourth-order in the slow bath and high temperature cases. Besides, the method is applicable on an equal footing for any kind of spectral density function and is expected to be a powerful tool to explore the quantum dynamics of large-scale systems, benefiting from the wavefunction framework and the time-local appearance within a single stochastic trajectory.
Open conformal systems and perturbations of transfer operators
Pollicott, Mark
2017-01-01
The focus of this book is on open conformal dynamical systems corresponding to the escape of a point through an open Euclidean ball. The ultimate goal is to understand the asymptotic behavior of the escape rate as the radius of the ball tends to zero. In the case of hyperbolic conformal systems this has been addressed by various authors. The conformal maps considered in this book are far more general, and the analysis correspondingly more involved. The asymptotic existence of escape rates is proved and they are calculated in the context of (finite or infinite) countable alphabets, uniformly contracting conformal graph-directed Markov systems, and in particular, conformal countable alphabet iterated function systems. These results have direct applications to interval maps, meromorphic maps and rational functions. Towards this goal the authors develop, on a purely symbolic level, a theory of singular perturbations of Perron--Frobenius (transfer) operators associated with countable alphabet subshifts of finite t...
Symmetry-preserving perturbations of the Bateman Lagrangian and dissipative systems
Campoamor-Stursberg, Rutwig
2017-03-01
Perturbations of the classical Bateman Lagrangian preserving a certain subalgebra of Noether symmetries are studied, and conservative perturbations are characterized by the Lie algebra sl(2, ℝ) ⊕ so(2). Non-conservative albeit integrable perturbations are determined by the simple Lie algebra sl(2,ℝ), showing further the relation of the corresponding non-linear systems with the notion of generalized Ermakov systems.
Symmetry-preserving perturbations of the Bateman Lagrangian and dissipative systems
International Nuclear Information System (INIS)
Campoamor-Stursberg, Rutwig
2017-01-01
Perturbations of the classical Bateman Lagrangian preserving a certain subalgebra of Noether symmetries are studied, and conservative perturbations are characterized by the Lie algebra sl(2, ℝ) ⊕ so(2). Non-conservative albeit integrable perturbations are determined by the simple Lie algebra sl(2,ℝ), showing further the relation of the corresponding non-linear systems with the notion of generalized Ermakov systems.
Symmetry-preserving perturbations of the Bateman Lagrangian and dissipative systems
Energy Technology Data Exchange (ETDEWEB)
Campoamor-Stursberg, Rutwig, E-mail: rutwig@ucm.es [Faculted de Ciencias Matematicas Universidad Complutense, Instituto de Matemática Interdisciplinar and Departamento Geometría y Topología (Spain)
2017-03-15
Perturbations of the classical Bateman Lagrangian preserving a certain subalgebra of Noether symmetries are studied, and conservative perturbations are characterized by the Lie algebra sl(2, ℝ) ⊕ so(2). Non-conservative albeit integrable perturbations are determined by the simple Lie algebra sl(2,ℝ), showing further the relation of the corresponding non-linear systems with the notion of generalized Ermakov systems.
Scaling laws for perturbations in the ocean–atmosphere system following large CO2 emissions
Towles, N.; Olson, P.; Gnanadesikan, A.
2015-01-01
Scaling relationships are derived for the perturbations to atmosphere and ocean variables from large transient CO2 emissions. Using the carbon cycle model LOSCAR (Zeebe et al., 2009; Zeebe, 2012b) we calculate perturbations to atmosphere temperature and total carbon, ocean temperature, total ocean carbon, pH, and alkalinity, marine sediment carbon, plus carbon-13 isotope anomalies in the ocean and atmosphere resulting from idealized CO2 emission events. The...
Non perturbative aspects of strongly correlated electron systems
International Nuclear Information System (INIS)
Controzzi, D.
2000-01-01
In this thesis we report some selected works on Strongly Correlated Electron Systems. A common ingredient of these works is the use of non-perturbative techniques available in low dimensions. In the first part we use the Bethe Ansatz to study some properties of two families of integrable models introduced by Fateev. We calculate the Thermodynamics of the models and show how they can be interpreted as effective Landau-Ginzburg theories for coupled two-dimensional superconductors interacting with an insulating substrate. This allows us to study exactly the dependence of the critical temperature on the thickness of the insulating layer, and on the interaction between the order parameters of two different superconducting planes. In the second part of the thesis we study the optical conductivity of the sine-Gordon model using the Form Factor method and Conformal Perturbation Theory. This allows us to develop, for the first time, a complete theory of the optical conductivity of one-dimensional Mott insulators, in the Quantum Field Theory limit. (author)
Perturbed beta-gamma systems and complex geometry
Energy Technology Data Exchange (ETDEWEB)
Zeitlin, Anton M. [Department of Mathematics, Yale University, 442 Dunham Lab, 10 Hillhouse Avenue, New Haven, CT 06511 (United States)], E-mail: anton.zeitlin@yale.edu
2008-05-11
We consider the equations, arising as the conformal invariance conditions of the perturbed curved beta-gamma system. These equations have the physical meaning of Einstein equations with a B-field and a dilaton on a Hermitian manifold, where the B-field 2-form is imaginary and proportional to the canonical form associated with Hermitian metric. We show that they decompose into linear and bilinear equations and lead to the vanishing of the first Chern class of the manifold where the system is defined. We discuss the relation of these equations to the generalized Maurer-Cartan structures related to BRST operator. Finally we describe the relations of the generalized Maurer-Cartan bilinear operation and the Courant/Dorfman brackets.
Equilibrium and perturbations in plasma-vacuum systems
International Nuclear Information System (INIS)
Mercier, C.
1974-01-01
Thermonuclear plasmas must be maintained far from all material contact. In order to realize this condition, one uses in the vacuum surrounding the plasma, a metal wall supposed perfectly conducting and currents whose positions and intensities have to be suitably chosen. The problem of equilibrium consists of finding a toroidal solution of the system of equations JxB=grad P, div B=0, J=rot B, B,J, and P being respectively the magnetic field, current intensity and plasma pressure. The problem can be solved in symmetry of revolution using cylindrical coordinates. The arrangement and intensity of the currents found will not be exactly realized due to, for exemple, technical reasons. Consequently, the first problem of equilibrium is considered as a first approximation and the configuration which will be obtained under imposed real conditions is computed as perturbed equilibria [fr
A stochastic perturbation theory for non-autonomous systems
Energy Technology Data Exchange (ETDEWEB)
Moon, W., E-mail: wm275@damtp.cam.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Wettlaufer, J. S., E-mail: wettlaufer@maths.ox.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom)
2013-12-15
We develop a perturbation theory for a class of first order nonlinear non-autonomous stochastic ordinary differential equations that arise in climate physics. The perturbative procedure produces moments in terms of integral delay equations, whose order by order decay is characterized in a Floquet-like sense. Both additive and multiplicative sources of noise are discussed and the question of how the nature of the noise influences the results is addressed theoretically and numerically. By invoking the Martingale property, we rationalize the transformation of the underlying Stratonovich form of the model to an Ito form, independent of whether the noise is additive or multiplicative. The generality of the analysis is demonstrated by developing it both for a Brownian particle moving in a periodically forced quartic potential, which acts as a simple model of stochastic resonance, as well as for our more complex climate physics model. The validity of the approach is shown by comparison with numerical solutions. The particular climate dynamics problem upon which we focus involves a low-order model for the evolution of Arctic sea ice under the influence of increasing greenhouse gas forcing ΔF{sub 0}. The deterministic model, developed by Eisenman and Wettlaufer [“Nonlinear threshold behavior during the loss of Arctic sea ice,” Proc. Natl. Acad. Sci. U.S.A. 106(1), 28–32 (2009)] exhibits several transitions as ΔF{sub 0} increases and the stochastic analysis is used to understand the manner in which noise influences these transitions and the stability of the system.
Quantum system under periodic perturbation: Effect of environment
International Nuclear Information System (INIS)
Hotta, M.; Joichi, I.; Matsumoto, S.; Yoshimura, M.
1997-01-01
In many physical situations the behavior of a quantum system is affected by interaction with a larger environment. We develop, using the method of an influence functional, how to deduce the density matrix of the quantum system incorporating the effect of environment. After introducing the characterization of the environment by spectral weight, we first devise schemes to approximate the spectral weight, and then a perturbation method in field theory models, in order to approximately describe the environment. All of these approximate models may be classified as extended Ohmic models of dissipation whose differences are in the high frequency part. The quantum system we deal with in the present work is a general class of harmonic oscillators with an arbitrary time-dependent frequency. The late time behavior of the system is well described by an approximation that employs a localized friction in the dissipative part of the correlation function appearing in the influence functional. The density matrix of the quantum system is then determined in terms of a single classical solution obtained with the time-dependent frequency. With this one can compute the entropy, the energy distribution function, and other physical quantities of the system in a closed form. A specific application is made to the case of a periodically varying frequency. This dynamical system has a remarkable property when the environmental interaction is switched off: The effect of the parametric resonance gives rise to an exponential growth of the populated number in higher excitation levels, or particle production in field theory models. The effect of the environment is investigated for this dynamical system and it is demonstrated that there exists a critical strength of the friction for the parametric effect. (Abstract Truncated)
Numerical perturbative methods in the quantum theory of physical systems
International Nuclear Information System (INIS)
Adam, G.
1980-01-01
During the last two decades, development of digital electronic computers has led to the deployment of new, distinct methods in theoretical physics. These methods, based on the advances of modern numerical analysis as well as on specific equations describing physical processes, enabled to perform precise calculations of high complexity which have completed and sometimes changed our image of many physical phenomena. Our efforts have concentrated on the development of numerical methods with such intrinsic performances as to allow a successful approach of some Key issues in present theoretical physics on smaller computation systems. The basic principle of such methods is to translate, in numerical analysis language, the theory of perturbations which is suited to numerical rather than to analytical computation. This idea has been illustrated by working out two problems which arise from the time independent Schroedinger equation in the non-relativistic approximation, within both quantum systems with a small number of particles and systems with a large number of particles, respectively. In the first case, we are led to the numerical solution of some quadratic ordinary differential equations (first section of the thesis) and in the second case, to the solution of some secular equations in the Brillouin area (second section). (author)
Sedimentation process and design of settling systems
De, Alak
2017-01-01
This book is designed to serve as a comprehensive source of information of sedimentation processes and design of settling systems, especially as applied to design of such systems in civil and environmental engineering. The book begins with an introduction to sedimentation as a whole and goes on to cover the development and details of various settling theories. The book traces the chronological developments of the comprehensive knowledge of settling studies and design of settling systems from 1889.A new concept of 'Velocity Profile Theorem', tool for settling problem analysis, has been employed to the analysis of the phenomenon of short circuiting. Complete theory of tube settling has been developed and its application to the computation of residual solids from the assorted solids through the same has been demonstrated. Experimental verification of the tube settling theory has also been presented. Field-oriented compatible design and operation methodology of settling system has been developed from the detailed...
Perturbation methods and closure approximations in nonlinear systems
International Nuclear Information System (INIS)
Dubin, D.H.E.
1984-01-01
In the first section of this thesis, Hamiltonian theories of guiding center and gyro-center motion are developed using modern symplectic methods and Lie transformations. Littlejohn's techniques, combined with the theory of resonant interaction and island overlap, are used to explore the problem of adiabatic invariance and onset of stochasticity. As an example, the breakdown of invariance due to resonance between drift motion and gyromotion in a tokamak is considered. A Hamiltonian is developed for motion in a straight magnetic field with electrostatic perturbations in the gyrokinetic ordering, from which nonlinear gyrokinetic equations are constructed which have the property of phase-space preservation, useful for computer simulation. Energy invariants are found and various limits of the equations are considered. In the second section, statistical closure theories are applied to simple dynamical systems. The logistic map is used as an example because of its universal properties and simple quadratic nonlinearity. The first closure considered is the direct interaction approximation of Kraichnan, which is found to fail when applied to the logistic map because it cannot approximate the bounded support of the map's equilibrium distribution. By imposing a periodically constraint on a Langevin form of the DIA a new stable closure is developed
Soliton annihilation in the perturbed sine-Gordon system
DEFF Research Database (Denmark)
Pedersen, Niels Falsig; Samuelsen, Mogens Rugholm; Welner, D.
1984-01-01
Fluxon-antifluxon annihilation in the perturbed sine-Gordon equation with loss and driving terms is investigated. For the infinite line we find a simple analytic expression for the threshold driving term corresponding to annihilation. With the application of the results to a Josephson junction...
Chaotic behavior of a three-species Beddington-type system with impulsive perturbations
International Nuclear Information System (INIS)
Wang Weiming; Wang Hailing; Li Zhenqing
2008-01-01
In this paper, a three-species food chain system with Beddington-type functional response and impulsive perturbations on the top predator is established. Subsequently, using Maple, the influence of the impulsive perturbations on the inherent oscillation is investigated, which shows rich dynamics. The work is useful for studying the dynamic and complexity of ecosystems
On the C(R) stability of uncertain singularly perturbed systems
International Nuclear Information System (INIS)
Sun, Y.-J.
2009-01-01
In this paper, a simple criterion for the C(R) stability of uncertain singularly perturbed systems is proposed. Such a criterion can be easily checked by some algebraic inequality. The upper bound of the singular perturbation parameter ε is also given by estimating the unique positive zero of specific function. Finally, a numerical example is provided to illustrate the main result
Modified perturbation theory for strongly correlated electron systems
International Nuclear Information System (INIS)
Takagi, Osamu; Saso, Tetsuro
1999-01-01
We propose a modified scheme for calculating the single-particle excitation spectrum of the impurity Anderson model. It is based on the second order perturbation theory, but modifies the self-energy so as to reproduce the correct atomic limit and to fulfill the Friedel sum rule. Therefore, it offers a simple scheme valid over wide range of excitation energy and parameters, and would be useful also for potential application to the lattice problems. (author)
Directory of Open Access Journals (Sweden)
M. Blumenberg
2013-04-01
Full Text Available The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs, lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer, methanotrophic bacteria (35-aminobacteriohopanetetrol, cyanobacteria (bacteriohopanetetrol cyclitol ether isomer and from soil bacteria (adenosylhopane through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyanobacteria, which is indicated by a positive correlation of BHP abundances with Corg and δ15N.
International Nuclear Information System (INIS)
Kang, Li; Tang, Sanyi
2016-01-01
Highlights: • The discrete single species and multiple species models with random perturbation are proposed. • The complex dynamics and interesting bifurcation behavior have been investigated. • The reverse effects of random perturbation on discrete systems have been discussed and revealed. • The main results can be applied for pest control and resources management. - Abstract: The natural species are likely to present several interesting and complex phenomena under random perturbations, which have been confirmed by simple mathematical models. The important questions are: how the random perturbations influence the dynamics of the discrete population models with multiple steady states or multiple species interactions? and is there any different effects for single species and multiple species models with random perturbation? To address those interesting questions, we have proposed the discrete single species model with two stable equilibria and the host-parasitoid model with Holling type functional response functions to address how the random perturbation affects the dynamics. The main results indicate that the random perturbation does not change the number of blurred orbits of the single species model with two stable steady states compared with results for the classical Ricker model with same random perturbation, but it can strength the stability. However, extensive numerical investigations depict that the random perturbation does not influence the complexities of the host-parasitoid models compared with the results for the models without perturbation, while it does increase the period of periodic orbits doubly. All those confirm that the random perturbation has a reverse effect on the dynamics of the discrete single and multiple population models, which could be applied in reality including pest control and resources management.
Limit cycles via higher order perturbations for some piecewise differential systems
Buzzi, Claudio A.; Lima, Maurício Firmino Silva; Torregrosa, Joan
2018-05-01
A classical perturbation problem is the polynomial perturbation of the harmonic oscillator, (x‧ ,y‧) =(- y + εf(x , y , ε) , x + εg(x , y , ε)) . In this paper we study the limit cycles that bifurcate from the period annulus via piecewise polynomial perturbations in two zones separated by a straight line. We prove that, for polynomial perturbations of degree n , no more than Nn - 1 limit cycles appear up to a study of order N. We also show that this upper bound is reached for orders one and two. Moreover, we study this problem in some classes of piecewise Liénard differential systems providing better upper bounds for higher order perturbation in ε, showing also when they are reached. The Poincaré-Pontryagin-Melnikov theory is the main technique used to prove all the results.
Second-order generalized perturbation theory for source-driven systems
International Nuclear Information System (INIS)
Greenspan, E.; Gilai, D.; Oblow, E.M.
1978-01-01
A second-order generalized perturbation theory (GPT) for the effect of multiple system variations on a general flux functional in source-driven systems is derived. The derivation is based on a functional Taylor series in which second-order derivatives are retained. The resulting formulation accounts for the nonlinear effect of a given variation accurate to third order in the flux and adjoint perturbations. It also accounts for the effect of interaction between any number of variations. The new formulation is compared with exact perturbation theory as well as with perturbation theory for altered systems. The usefulnes of the second-order GPT formulation is illustrated by applying it to optimization problems. Its applicability to areas of cross-section sensitivity analysis and system design and evaluation is also discussed
Suppression of period-doubling and nonlinear parametric effects in periodically perturbed systems
International Nuclear Information System (INIS)
Bryant, P.; Wiesenfeld, K.
1986-01-01
We consider the effect on a generic period-doubling bifurcation of a periodic perturbation, whose frequency ω 1 is near the period-doubled frequency ω 0 /2. The perturbation is shown to always suppress the bifurcation, shifting the bifurcation point and stabilizing the behavior at the original bifurcation point. We derive an equation characterizing the response of the system to the perturbation, analysis of which reveals many interesting features of the perturbed bifurcation, including (1) the scaling law relating the shift of the bifurcation point and the amplitude of the perturbation, (2) the characteristics of the system's response as a function of bifurcation parameter, (3) parametric amplification of the perturbation signal including nonlinear effects such as gain saturation and a discontinuity in the response at a critical perturbation amplitude, (4) the effect of the detuning (ω 1 -ω 0 /2) on the bifurcation, and (5) the emergence of a closely spaced set of peaks in the response spectrum. An important application is the use of period-doubling systems as small-signal amplifiers, e.g., the superconducting Josephson parametric amplifier
Existence of Generalized Homoclinic Solutions of Lotka-Volterra System under a Small Perturbation
Mi, Yuzhen
2016-01-01
This paper investigates Lotka-Volterra system under a small perturbation vxx=-μ(1-a2u-v)v+ϵf(ϵ,v,vx,u,ux), uxx=-(1-u-a1v)u+ϵg(ϵ,v,vx,u,ux). By the Fourier series expansion technique method, the fixed point theorem, the perturbation theorem, and the reversibility, we prove that near μ=0 the system has a generalized homoclinic solution exponentially approaching a periodic solution.
Existence of Generalized Homoclinic Solutions of Lotka-Volterra System under a Small Perturbation
Directory of Open Access Journals (Sweden)
Yuzhen Mi
2016-01-01
Full Text Available This paper investigates Lotka-Volterra system under a small perturbation vxx=-μ(1-a2u-vv+ϵf(ϵ,v,vx,u,ux, uxx=-(1-u-a1vu+ϵg(ϵ,v,vx,u,ux. By the Fourier series expansion technique method, the fixed point theorem, the perturbation theorem, and the reversibility, we prove that near μ=0 the system has a generalized homoclinic solution exponentially approaching a periodic solution.
Correlations between chaos in a perturbed sine-Gordon equation and a truncated model system
International Nuclear Information System (INIS)
Bishop, A.R.; Flesch, R.; Forests, M.G.; Overman, E.A.
1990-01-01
The purpose of this paper is to present a first step toward providing coordinates and associated dynamics for low-dimensional attractors in nearly integrable partial differential equations (pdes), in particular, where the truncated system reflects salient geometric properties of the pde. This is achieved by correlating: (1) numerical results on the bifurcations to temporal chaos with spatial coherence of the damped, periodically forced sine-Gordon equation with periodic boundary conditions; (2) an interpretation of the spatial and temporal bifurcation structures of this perturbed integrable system with regard to the exact structure of the sine-Gordon phase space; (3) a model dynamical systems problem, which is itself a perturbed integrable Hamiltonian system, derived from the perturbed sine-Gordon equation by a finite mode Fourier truncation in the nonlinear Schroedinger limit; and (4) the bifurcations to chaos in the truncated phase space. In particular, a potential source of chaos in both the pde and the model ordinary differential equation systems is focused on: the existence of homoclinic orbits in the unperturbed integrable phase space and their continuation in the perturbed problem. The evidence presented here supports the thesis that the chaotic attractors of the weakly perturbed periodic sine-Gordon system consists of low-dimensional metastable attacking states together with intermediate states that are O(1) unstable and correspond to homoclinic states in the integrable phase space. It is surmised that the chaotic dynamics on these attractors is due to the perturbation of these homocline integrable configurations
Chaos in periodically forced Holling type II predator-prey system with impulsive perturbations
International Nuclear Information System (INIS)
Zhang Shuwen; Tan Dejun; Chen Lansun
2006-01-01
The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type II functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of prey. The impulsive perturbation is affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can very easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade, (5) non-unique dynamics
Chaos in periodically forced Holling type IV predator-prey system with impulsive perturbations
International Nuclear Information System (INIS)
Zhang Shuwen; Tan Dejun; Chen Lansun
2006-01-01
The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type IV functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. The impulsive perturbations are affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade
System-level perturbations of cell metabolism using CRISPR/Cas9
Energy Technology Data Exchange (ETDEWEB)
Jakočiūnas, Tadas [Technical Univ. of Denmark, Lyngby (Denmark); Jensen, Michael K. [Technical Univ. of Denmark, Lyngby (Denmark); Keasling, Jay D. [Technical Univ. of Denmark, Lyngby (Denmark); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
2017-03-30
CRISPR/Cas9 (clustered regularly interspaced palindromic repeats and the associated protein Cas9) techniques have made genome engineering and transcriptional reprogramming studies much more advanced and cost-effective. For metabolic engineering purposes, the CRISPR-based tools have been applied to single and multiplex pathway modifications and transcriptional regulations. The effectiveness of these tools allows researchers to implement genome-wide perturbations, test model-guided genome editing strategies, and perform transcriptional reprogramming perturbations in a more advanced manner than previously possible. In this mini-review we highlight recent studies adopting CRISPR/Cas9 for systems-level perturbations and model-guided metabolic engineering.
Static spin-3/2 perturbations of two-black hole system
International Nuclear Information System (INIS)
Embacher, F.; Aichelburg, P.C.
1984-01-01
We construct the most general static regular, non-gauge spin-3/2 perturbations on the Majumdar-Papapetrou background for two black holes. The construction applies a limiting procedure by combining Killing spinors and spacetime perturbations. The supercharge associated with the spin-3/2 field is proportional to the difference of the mass parameters, implying that a system of two equal black holes has zero supercharge. (Author)
Corporate Investment Dynamic Control System Based on Chaos Cycle Perturbations
Directory of Open Access Journals (Sweden)
Yanyan Gao
2014-11-01
Full Text Available It exists some issues such as the low predict accuracy and a bad convergence performance to predict business investment with BP neural network algorithm. This paper presents a predictive model of business investment based on improved artificial bee colony and chaos periodic disturbance optimizing BP neural network algorithm. At first, use Boltzmann selection strategy and group behaviour control strategy to optimize the artificial bee colony algorithm, and then use the improved algorithm to transform BP neural network algorithm’s optimized parameters into optimization process of artificial bee colony algorithm to reduce the training error of the original algorithm. Finally, use chaotic optimized Logistic mapping enables BP neural network out of the local minimum point in the training process based on secondary chaotic cycle perturbation strategies. Simulation results show that the proposed predictive model of investment in the enterprise based on improved artificial bee colony and chaos periodic disturbance optimizing BP neural network algorithm shows higher predict accuracy and better convergence than normal BP neural network algorithm.
Evolution of perturbed dynamical systems: analytical computation with time independent accuracy
Energy Technology Data Exchange (ETDEWEB)
Gurzadyan, A.V. [Russian-Armenian (Slavonic) University, Department of Mathematics and Mathematical Modelling, Yerevan (Armenia); Kocharyan, A.A. [Monash University, School of Physics and Astronomy, Clayton (Australia)
2016-12-15
An analytical method for investigation of the evolution of dynamical systems with independent on time accuracy is developed for perturbed Hamiltonian systems. The error-free estimation using of computer algebra enables the application of the method to complex multi-dimensional Hamiltonian and dissipative systems. It also opens principal opportunities for the qualitative study of chaotic trajectories. The performance of the method is demonstrated on perturbed two-oscillator systems. It can be applied to various non-linear physical and astrophysical systems, e.g. to long-term planetary dynamics. (orig.)
Numerical Modelling Approaches for Sediment Transport in Sewer Systems
DEFF Research Database (Denmark)
Mark, Ole
A study of the sediment transport processes in sewers has been carried out. Based on this study a mathematical modelling system has been developed to describe the transport processes of sediments and dissolved matter in sewer systems. The modelling system consists of three sub-models which...... constitute the basic modelling system necessary to give a discription of the most dominant physical transport processes concerning particles and dissolved matter in sewer systems: A surface model. An advection-dispersion model. A sediment transport model....
Sediment Transport Model for a Surface Irrigation System
Directory of Open Access Journals (Sweden)
Damodhara R. Mailapalli
2013-01-01
Full Text Available Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in furrow irrigation. The irrigation hydraulic model simulates flow in a furrow irrigation system using the analytically solved zero-inertial overland flow equations and 1D-Green-Ampt, 2D-Fok, and Kostiakov-Lewis infiltration equations. Performance of the sediment transport model was evaluated for bare and cropped furrow fields. The results indicated that the sediment transport model can predict the initial sediment rate adequately, but the simulated sediment rate was less accurate for the later part of the irrigation event. Sensitivity analysis of the parameters of the sediment module showed that the soil erodibility coefficient was the most influential parameter for determining sediment load in furrow irrigation. The developed modeling tool can be used as a water management tool for mitigating sediment loss from the surface irrigated fields.
Control of a perturbed under-actuated mechanical system
Zayane, Chadia; Laleg-Kirati, Taous-Meriem; Chemori, Ahmed
2015-01-01
In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed
International Nuclear Information System (INIS)
Mirus, K.A.
1998-06-01
In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high-dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses
Energy Technology Data Exchange (ETDEWEB)
Mirus, Kevin A. [Univ. of Wisconsin, Madison, WI (United States)
1998-01-01
In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high-dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses.
Mirus, Kevin Andrew
In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Rossler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high- dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses.
International Nuclear Information System (INIS)
Wu, C.W.
2003-01-01
In a recent paper, wavelet analysis is used to perturb the coupling matrix in an array of identical chaotic systems in order to improve its synchronization. When the coupling matrix is symmetric, the synchronization criterion is determined by the second smallest eigenvalue λ 2 of the coupling matrix and the problem is reduced to studying how λ 2 of the coupling matrix changes with perturbation. In the aforementioned paper, a small percentage of the wavelet coefficients are modified. However, this results in a perturbed matrix where every element is modified and nonzero. The purpose of this Letter is to present some results on the change of λ 2 due to perturbation. In particular, we show that as the number of systems n→∞, perturbations which only add local coupling will not change λ 2 . On the other hand, we show that there exists perturbations which modify an arbitrarily small percentage of matrix elements, each of which is changed by an arbitrarily small amount and yet can make λ 2 arbitrarily large. These results give conditions on what the perturbation should be in order to improve the synchronizability in an array of coupled chaotic systems. This analysis allows us to justify and explain some of the synchronization phenomena observed in a recently studied network where random coupling is added to a locally connected array. We propose to classify various classes of coupling matrices such as small world networks and scale free networks according to their synchronizability in the limit. Finally, we briefly discuss the case of time-varying coupling
Performance optimization of queueing systems with perturbation realization
Xia, Li; Cao, Xiren
2012-01-01
After the intensive studies of queueing theory in the past decades, many excellent results in performance analysis have been obtained, and successful examples abound. However, exploring special features of queueing systems directly in performance
Perturbation-induced emergence of Poisson-like behavior in non-Poisson systems
International Nuclear Information System (INIS)
Akin, Osman C; Grigolini, Paolo; Paradisi, Paolo
2009-01-01
The response of a system with ON–OFF intermittency to an external harmonic perturbation is discussed. ON–OFF intermittency is described by means of a sequence of random events, i.e., the transitions from the ON to the OFF state and vice versa. The unperturbed waiting times (WTs) between two events are assumed to satisfy a renewal condition, i.e., the WTs are statistically independent random variables. The response of a renewal model with non-Poisson ON–OFF intermittency, associated with non-exponential WT distribution, is analyzed by looking at the changes induced in the WT statistical distribution by the harmonic perturbation. The scaling properties are also studied by means of diffusion entropy analysis. It is found that, in the range of fast and relatively strong perturbation, the non-Poisson system displays a Poisson-like behavior in both WT distribution and scaling. In particular, the histogram of perturbed WTs becomes a sequence of equally spaced peaks, with intensity decaying exponentially in time. Further, the diffusion entropy detects an ordinary scaling (related to normal diffusion) instead of the expected unperturbed anomalous scaling related to the inverse power-law decay. Thus, an analysis based on the WT histogram and/or on scaling methods has to be considered with some care when dealing with perturbed intermittent systems
Balance perturbation system to improve balance compensatory responses during walking in old persons
Directory of Open Access Journals (Sweden)
Melzer Itshak
2010-07-01
Full Text Available Abstract Ageing commonly disrupts the balance control and compensatory postural responses that contribute to maintaining balance and preventing falls during perturbation of posture. This can lead to increased risk of falling in old adults (65 years old and over. Therefore, improving compensatory postural responses during walking is one of the goals in fall prevention programs. Training is often used to achieve this goal. Most fall prevention programs are usually directed towards improving voluntary postural control. Since compensatory postural responses triggered by a slip or a trip are not under direct volitional control these exercises are less expected to improve compensatory postural responses due to lack of training specificity. Thus, there is a need to investigate the use balance perturbations during walking to train more effectively compensatory postural reactions during walking. This paper describes the Balance Measure & Perturbation System (BaMPer System a system that provides small, controlled and unpredictable perturbations during treadmill walking providing valuable perturbation, which allows training compensatory postural responses during walking which thus hypothesize to improve compensatory postural responses in older adults.
International Nuclear Information System (INIS)
Biazar, J.; Eslami, M.; Aminikhah, H.
2009-01-01
In this article, an application of He's homotopy perturbation method is applied to solve systems of Volterra integral equations of the first kind. Some non-linear examples are prepared to illustrate the efficiency and simplicity of the method. Applying the method for linear systems is so easily that it does not worth to have any example.
International Nuclear Information System (INIS)
Biazar, J.; Ghazvini, H.
2009-01-01
In this paper, the He's homotopy perturbation method is applied to solve systems of Volterra integral equations of the second kind. Some examples are presented to illustrate the ability of the method for linear and non-linear such systems. The results reveal that the method is very effective and simple.
Contamination of Detained Sediment in Sustainable Urban Drainage Systems
Directory of Open Access Journals (Sweden)
Deonie Allen
2017-05-01
Full Text Available Adsorption is a key water pollution remediation measure used to achieve stormwater quality improvement in Sustainable urban Drainage Systems (SuDS. The level of contamination of detained sediment within SuDS assets is not well documented, with published investigations limited to specific contaminant occurrence in ponds, wetlands or infiltration devices (bioretention cells and generally focused on solute or suspended sediment. Guidance on contamination threshold levels and potential deposited sediment contamination information is not included in current UK SuDS design or maintenance guidance, primarily due to a lack of evidence and understanding. There is a need to understand possible deposited sediment contamination levels in SuDS, specifically in relation to sediment removal maintenance activities and potential impact on receiving waterways of conveyed sediment. Thus, the objective of the research presented herein was to identify what major elements and trace metals were observable in (the investigated SuDS assets detained sediment, the concentration of these major elements and trace metals and whether they met/surpassed ecotoxicity or contaminated land thresholds. The research presented here provides evidence of investigated SuDS sediment major element and trace metal levels to help inform guidance and maintenance needs, and presents a new methodology to identify the general cause (anthropocentric land use and extent of detained SuDS fine urban sediment contamination through use of a contamination matrix.
Perturbation of Fractional Multi-Agent Systems in Cloud Entropy Computing
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Rabha W. Ibrahim
2016-01-01
Full Text Available A perturbed multi-agent system is a scheme self-possessed of multiple networking agents within a location. This scheme can be used to discuss problems that are impossible or difficult for a specific agent to solve. Intelligence cloud entropy management systems involve functions, methods, procedural approaches, and algorithms. In this study, we introduce a new perturbed algorithm based on the fractional Poisson process. The discrete dynamics are suggested by using fractional entropy and fractional type Tsallis entropy. Moreover, we study the algorithm stability.
The multistage homotopy-perturbation method: A powerful scheme for handling the Lorenz system
International Nuclear Information System (INIS)
Chowdhury, M.S.H.; Hashim, I.; Momani, S.
2009-01-01
In this paper, a new reliable algorithm based on an adaptation of the standard homotopy-perturbation method (HPM) is presented. The HPM is treated as an algorithm in a sequence of intervals (i.e. time step) for finding accurate approximate solutions to the famous Lorenz system. Numerical comparisons between the multistage homotopy-perturbation method (MHPM) and the classical fourth-order Runge-Kutta (RK4) method reveal that the new technique is a promising tool for the nonlinear systems of ODEs.
A perturbation method in strongly correlated fermion systems
International Nuclear Information System (INIS)
Keiter, H.; Oberbach, S.; Kilic, S.
1998-01-01
We present a new expression for the grand partition function of a many-body system which contains a generalized Feenberg energy formula. In addition a form of the momentum distribution function of the Luttinger model is derived and non Fermi liquid behaviour is demonstrated. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)
Optimal Linear Responses for Markov Chains and Stochastically Perturbed Dynamical Systems
Antown, Fadi; Dragičević, Davor; Froyland, Gary
2018-03-01
The linear response of a dynamical system refers to changes to properties of the system when small external perturbations are applied. We consider the little-studied question of selecting an optimal perturbation so as to (i) maximise the linear response of the equilibrium distribution of the system, (ii) maximise the linear response of the expectation of a specified observable, and (iii) maximise the linear response of the rate of convergence of the system to the equilibrium distribution. We also consider the inhomogeneous, sequential, or time-dependent situation where the governing dynamics is not stationary and one wishes to select a sequence of small perturbations so as to maximise the overall linear response at some terminal time. We develop the theory for finite-state Markov chains, provide explicit solutions for some illustrative examples, and numerically apply our theory to stochastically perturbed dynamical systems, where the Markov chain is replaced by a matrix representation of an approximate annealed transfer operator for the random dynamical system.
Optimal perturbations for nonlinear systems using graph-based optimal transport
Grover, Piyush; Elamvazhuthi, Karthik
2018-06-01
We formulate and solve a class of finite-time transport and mixing problems in the set-oriented framework. The aim is to obtain optimal discrete-time perturbations in nonlinear dynamical systems to transport a specified initial measure on the phase space to a final measure in finite time. The measure is propagated under system dynamics in between the perturbations via the associated transfer operator. Each perturbation is described by a deterministic map in the measure space that implements a version of Monge-Kantorovich optimal transport with quadratic cost. Hence, the optimal solution minimizes a sum of quadratic costs on phase space transport due to the perturbations applied at specified times. The action of the transport map is approximated by a continuous pseudo-time flow on a graph, resulting in a tractable convex optimization problem. This problem is solved via state-of-the-art solvers to global optimality. We apply this algorithm to a problem of transport between measures supported on two disjoint almost-invariant sets in a chaotic fluid system, and to a finite-time optimal mixing problem by choosing the final measure to be uniform. In both cases, the optimal perturbations are found to exploit the phase space structures, such as lobe dynamics, leading to efficient global transport. As the time-horizon of the problem is increased, the optimal perturbations become increasingly localized. Hence, by combining the transfer operator approach with ideas from the theory of optimal mass transportation, we obtain a discrete-time graph-based algorithm for optimal transport and mixing in nonlinear systems.
Approximate solution of generalized Ginzburg-Landau-Higgs system via homotopy perturbation method
Energy Technology Data Exchange (ETDEWEB)
Lu Juhong [School of Physics and Electromechanical Engineering, Shaoguan Univ., Guangdong (China); Dept. of Information Engineering, Coll. of Lishui Professional Tech., Zhejiang (China); Zheng Chunlong [School of Physics and Electromechanical Engineering, Shaoguan Univ., Guangdong (China); Shanghai Inst. of Applied Mathematics and Mechanics, Shanghai Univ., SH (China)
2010-04-15
Using the homotopy perturbation method, a class of nonlinear generalized Ginzburg-Landau-Higgs systems (GGLH) is considered. Firstly, by introducing a homotopic transformation, the nonlinear problem is changed into a system of linear equations. Secondly, by selecting a suitable initial approximation, the approximate solution with arbitrary degree accuracy to the generalized Ginzburg-Landau-Higgs system is derived. Finally, another type of homotopic transformation to the generalized Ginzburg-Landau-Higgs system reported in previous literature is briefly discussed. (orig.)
Global Melnikov Theory in Hamiltonian Systems with General Time-Dependent Perturbations
Gidea, Marian; de la Llave, Rafael
2018-04-01
We consider a mechanical system consisting of n-penduli and a d-degree-of-freedom rotator. The phase space of the rotator defines a normally hyperbolic invariant manifold Λ _0 . We apply a time-dependent perturbation, which is not assumed to be either Hamiltonian, or periodic, or quasi-periodic, as we allow for rather general time dependence. The strength of the perturbation is given by a parameter ɛ \\in R . For all |ɛ | sufficiently small, the augmented flow—obtained by making the time into a new variable—has a normally hyperbolic locally invariant manifold \\tilde{Λ }_ɛ . For ɛ =0 , \\tilde{Λ }_0=Λ _0× R . We define a Melnikov-type vector, which gives the first-order expansion of the displacement of the stable and unstable manifolds of \\tilde{Λ }_0 under the perturbation. We provide an explicit formula for the Melnikov vector in terms of convergent improper integrals of the perturbation along homoclinic orbits of the unperturbed system. We show that if the perturbation satisfies some explicit non-degeneracy conditions, then the stable and unstable manifolds of \\tilde{Λ }_ɛ , W^s(\\tilde{Λ }_ɛ ) and W^u(\\tilde{Λ }_ɛ ) , respectively, intersect along a transverse homoclinic manifold, and, moreover, the splitting of W^s(\\tilde{Λ }_ɛ ) and W^u(\\tilde{Λ }_ɛ ) can be explicitly computed, up to the first order, in terms of the Melnikov-type vector. This implies that the excursions along some homoclinic trajectories yield a non-trivial increase of order O(ɛ ) in the action variables of the rotator, for all sufficiently small perturbations. The formulas that we obtain are independent of the unperturbed motions in Λ _0 , and give, at the same time, the effects on periodic, quasi-periodic, or general-type orbits. When the perturbation is Hamiltonian, we express the effects of the perturbation, up to the first order, in terms of a Melnikov potential. In addition, if the perturbation is periodic, we obtain that the non-degeneracy conditions on
Newcomer, Michelle E.; Hubbard, Susan S.; Fleckenstein, Jan H.; Maier, Ulrich; Schmidt, Christian; Thullner, Martin; Ulrich, Craig; Flipo, Nicolas; Rubin, Yoram
2018-03-01
Rivers in climatic zones characterized by dry and wet seasons often experience periodic transitions between losing and gaining conditions across the river-aquifer continuum. Infiltration shifts can stimulate hyporheic microbial biomass growth and cycling of riverine carbon and nitrogen leading to major exports of biogenic CO2 and N2 to rivers. In this study, we develop and test a numerical model that simulates biological-physical feedback in the hyporheic zone. We used the model to explore different initial conditions in terms of dissolved organic carbon availability, sediment characteristics, and stochastic variability in aerobic and anaerobic conditions from water table fluctuations. Our results show that while highly losing rivers have greater hyporheic CO2 and N2 production, gaining rivers allowed the greatest fraction of CO2 and N2 production to return to the river. Hyporheic aerobic respiration and denitrification contributed 0.1-2 g/m2/d of CO2 and 0.01-0.2 g/m2/d of N2; however, the suite of potential microbial behaviors varied greatly among sediment characteristics. We found that losing rivers that consistently lacked an exit pathway can store up to 100% of the entering C/N as subsurface biomass and dissolved gas. Our results demonstrate the importance of subsurface feedbacks whereby microbes and hydrology jointly control fate of C and N and are strongly linked to wet-season control of initial sediment conditions and hydrologic control of seepage direction. These results provide a new understanding of hydrobiological and sediment-based controls on hyporheic zone respiration, including a new explanation for the occurrence of anoxic microzones and large denitrification rates in gravelly riverbeds.
Cliff R. Hupp; Michael R. Schening
2000-01-01
Sedimentation is arguably the most important water-quality concern in the United States. Sediment trapping is cited frequently as a major function of riverine-forested wetlands, yet little is known about sedimcntation rates at the landscape scale in relation to site parameters, including woody vegetation type, elevation, velocity, and hydraulic connection to the river...
Enhanced Multistage Homotopy Perturbation Method: Approximate Solutions of Nonlinear Dynamic Systems
Directory of Open Access Journals (Sweden)
Daniel Olvera
2014-01-01
Full Text Available We introduce a new approach called the enhanced multistage homotopy perturbation method (EMHPM that is based on the homotopy perturbation method (HPM and the usage of time subintervals to find the approximate solution of differential equations with strong nonlinearities. We also study the convergence of our proposed EMHPM approach based on the value of the control parameter h by following the homotopy analysis method (HAM. At the end of the paper, we compare the derived EMHPM approximate solutions of some nonlinear physical systems with their corresponding numerical integration solutions obtained by using the classical fourth order Runge-Kutta method via the amplitude-time response curves.
Calculation, normalization and perturbation of quasinormal modes in coupled cavity-waveguide systems
DEFF Research Database (Denmark)
Kristensen, Philip Trøst; de Lasson, Jakob Rosenkrantz; Gregersen, Niels
2014-01-01
of divergent series to provide a framework for modeling of optical phenomena in such coupled cavity-waveguide systems. As an example, we apply the framework to study perturbative changes in the resonance frequency and Q value of a photonic crystal cavity coupled to a defect waveguide....
International Nuclear Information System (INIS)
Frank, T.D.
2006-01-01
First-order approximations of time-dependent solutions are determined for stochastic systems perturbed by time-delayed feedback forces. To this end, the theory of delay Fokker-Planck equations is applied in combination with Bayes' theorem. Applications to a time-delayed Ornstein-Uhlenbeck process and the geometric Brownian walk of financial physics are discussed
International Nuclear Information System (INIS)
Estiot, J.C.; Salvatores, M.; Palmiotti, G.
1981-01-01
We present the characteristics of SAMPO, a one dimension transport theory code system, which is used for the following types of calculation: sensitivity analysis for functional linear or bi-linear on the direct or adjoint flux and their ratios; classic perturbation analysis. First order calculations, as well higher order, can be presented
ANALYSIS OF PERTURBED MOTION STABILITY OF WHEELER VEHICLES BRAKES CONTROL SYSTEM
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V. Verbytskiyi
2011-01-01
Full Text Available The analysis of the perturbed motion stability of the brake automatic control system on the basis of Lyapunov’s second method is carried out. Using transformations of Lurie there has been ob-tained the canonical form of the system of equations of automatic control. It allowed determining the necessary and sufficient conditions of the asymptotic stability of the system irrespective of its initial condition and a definite choice of the admissible characteristic of the regulator.
Directory of Open Access Journals (Sweden)
Yun-zhi Zou
2012-01-01
Full Text Available A new class of generalized dynamical systems involving generalized f-projection operators is introduced and studied in Banach spaces. By using the fixed-point theorem due to Nadler, the equilibrium points set of this class of generalized global dynamical systems is proved to be nonempty and closed under some suitable conditions. Moreover, the solutions set of the systems with set-valued perturbation is showed to be continuous with respect to the initial value.
Directory of Open Access Journals (Sweden)
Xiao-Zheng Jin
2013-01-01
Full Text Available This paper deals with the asymptotic consensus problem for a class of multiagent systems with time-varying additive actuator faults and perturbed communications. The L2 performance of systems is also considered in the consensus controller designs. The upper and lower bounds of faults and perturbations in actuators and communications and controller gains are assumed to be unknown but can be estimated by designing some indirect adaptive laws. Based on the information from the adaptive estimation mechanism, the distributed robust adaptive sliding mode controllers are constructed to automatically compensate for the effects of faults and perturbations and to achieve any given level of L2 gain attenuation from external disturbance to consensus errors. Through Lyapunov functions and adaptive schemes, the asymptotic consensus of resulting adaptive multiagent system can be achieved with a specified performance criterion in the presence of perturbed communications and actuators. The effectiveness of the proposed design is illustrated via a decoupled longitudinal model of F-18 aircraft.
International Nuclear Information System (INIS)
Mitchell, P.I.; Vintro, L.L.; Gasco, C.; Sanchez-Cabeza, J.A.
1995-01-01
It is well established that the main source of the plutonium found in marine sediments throughout the Northern Hemisphere is global stratospheric fallout, characterized by a typical 240 Pu/ 239 Pu atom ratio of ∼0.18. Measurements of perturbations in this ratio at various sites which had been subjected to close-in fallout, mainly from surface-based testing, has confirmed the feasibility of using this ratio to distinguish plutonium from different fallout sources. In the present study, the 240 Pu/ 239 Pu ratio has been examined in samples of sediment collected at Thule (Greenland) and Palomares (Spain), where accidents involving the release and dispersion of plutonium from fractured nuclear weapons occurred in 1968 and 1966, respectively. The 240 Pu/ 239 Pu ratio was measured by high-resolution alpha spectrometry and spectral deconvolution. The analytical results showed that at Thule the mean 240 Pu/ 239 Pu atom ratio was 0.033±0.004, while at Palomares the equivalent ratio appeared to be significantly higher at 0.056±0.003. Both ratios are consistent with those reported for soils samples at the Nevada site and Nagasaki, and are clearly indicative of weapons-grade plutonium. 27 refs., 1 fig., 2 tabs
Exact-to-precision generalized perturbation theory for source-driven systems
International Nuclear Information System (INIS)
Wang Congjian; Abdel-Khalik, Hany S.
2011-01-01
Highlights: ► We present a new development in higher order generalized perturbation theory. ► The method addresses the explosion in the flux phase space, input parameters, and responses. ► The method hybridizes first-order GPT and proper orthogonal decomposition snapshots method. ► A simplified 1D and realistic 2D assembly models demonstrate applicability of the method. ► The accuracy of the method is compared to exact direct perturbations and first-order GPT. - Abstract: Presented in this manuscript are new developments to perturbation theory which are intended to extend its applicability to estimate, with quantifiable accuracy, the exact variations in all responses calculated by the model with respect to all possible perturbations in the model's input parameters. The new developments place high premium on reducing the associated computational overhead in order to enable the use of perturbation theory in routine reactor design calculations. By way of examples, these developments could be employed in core simulation to accurately estimate the few-group cross-sections variations resulting from perturbations in neutronics and thermal-hydraulics core conditions. These variations are currently being described using a look-up table approach, where thousands of assembly calculations are performed to capture few-group cross-sections variations for the downstream core calculations. Other applications include the efficient evaluation of surrogates for applications that require repeated model runs such as design optimization, inverse studies, uncertainty quantification, and online core monitoring. The theoretical background of these developments applied to source-driven systems and supporting numerical experiments are presented in this manuscript. Extension to eigenvalue problems will be presented in a future article.
Tran, Tri; Ha, Q P
2018-01-01
A perturbed cooperative-state feedback (PSF) strategy is presented for the control of interconnected systems in this paper. The subsystems of an interconnected system can exchange data via the communication network that has multiple connection topologies. The PSF strategy can resolve both issues, the sensor data losses and the communication network breaks, thanks to the two components of the control including a cooperative-state feedback and a perturbation variable, e.g., u i =K ij x j +w i . The PSF is implemented in a decentralized model predictive control scheme with a stability constraint and a non-monotonic storage function (ΔV(x(k))≥0), derived from the dissipative systems theory. Numerical simulation for the automatic generation control problem in power systems is studied to illustrate the effectiveness of the presented PSF strategy. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Application of Multistage Homotopy Perturbation Method to the Chaotic Genesio System
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M. S. H. Chowdhury
2012-01-01
Full Text Available Finding accurate solution of chaotic system by using efficient existing numerical methods is very hard for its complex dynamical behaviors. In this paper, the multistage homotopy-perturbation method (MHPM is applied to the Chaotic Genesio system. The MHPM is a simple reliable modification based on an adaptation of the standard homotopy-perturbation method (HPM. The HPM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions to the Chaotic Genesio system. Numerical comparisons between the MHPM and the classical fourth-order Runge-Kutta (RK4 solutions are made. The results reveal that the new technique is a promising tool for the nonlinear chaotic systems of ordinary differential equations.
Directory of Open Access Journals (Sweden)
Musa Danjuma SHEHU
2008-06-01
Full Text Available This paper lays emphasis on formulation of two dimensional differential games via optimal control theory and consideration of control systems whose dynamics is described by a system of Ordinary Differential equation in the form of linear equation under the influence of two controls U(. and V(.. Base on this, strategies were constructed. Hence we determine the optimal strategy for a control say U(. under a perturbation generated by the second control V(. within a given manifold M.
Renormalized perturbation theory: Vlasov-Poisson System, weak turbulence limit and gyrokinetics
International Nuclear Information System (INIS)
Zhang, Y.Z.; Mahajan, S.M.
1987-10-01
The Self-consistency of the renormalized perturbation theory is demonstrated by applying it to the Vlasov-Poisson System and showing that the theory has the correct weak turbulence limit. Energy conservation is proved to arbitrary high order for the electrostatic drift waves. The theory is applied to derive renormalized equations for a low-β gyrokinetic system. Comparison of our theory with other current theories is presented. 22 refs
PeTTSy: a computational tool for perturbation analysis of complex systems biology models.
Domijan, Mirela; Brown, Paul E; Shulgin, Boris V; Rand, David A
2016-03-10
Over the last decade sensitivity analysis techniques have been shown to be very useful to analyse complex and high dimensional Systems Biology models. However, many of the currently available toolboxes have either used parameter sampling, been focused on a restricted set of model observables of interest, studied optimisation of a objective function, or have not dealt with multiple simultaneous model parameter changes where the changes can be permanent or temporary. Here we introduce our new, freely downloadable toolbox, PeTTSy (Perturbation Theory Toolbox for Systems). PeTTSy is a package for MATLAB which implements a wide array of techniques for the perturbation theory and sensitivity analysis of large and complex ordinary differential equation (ODE) based models. PeTTSy is a comprehensive modelling framework that introduces a number of new approaches and that fully addresses analysis of oscillatory systems. It examines sensitivity analysis of the models to perturbations of parameters, where the perturbation timing, strength, length and overall shape can be controlled by the user. This can be done in a system-global setting, namely, the user can determine how many parameters to perturb, by how much and for how long. PeTTSy also offers the user the ability to explore the effect of the parameter perturbations on many different types of outputs: period, phase (timing of peak) and model solutions. PeTTSy can be employed on a wide range of mathematical models including free-running and forced oscillators and signalling systems. To enable experimental optimisation using the Fisher Information Matrix it efficiently allows one to combine multiple variants of a model (i.e. a model with multiple experimental conditions) in order to determine the value of new experiments. It is especially useful in the analysis of large and complex models involving many variables and parameters. PeTTSy is a comprehensive tool for analysing large and complex models of regulatory and
From "E-flows" to "Sed-flows": Managing the Problem of Sediment in High Altitude Hydropower Systems
Gabbud, C.; Lane, S. N.
2017-12-01
The connections between stream hydraulics, geomorphology and ecosystems in mountain rivers have been substantially perturbed by humans, for example through flow regulation related to hydropower activities. It is well known that the ecosystem impacts downstream of hydropower dams may be managed by a properly designed compensation release or environmental flows ("e-flows"), and such flows may also include sediment considerations (e.g. to break up bed armor). However, there has been much less attention given to the ecosystem impacts of water intakes (where water is extracted and transferred for storage and/or power production), even though in many mountain systems such intakes may be prevalent. Flow intakes tend to be smaller than dams and because they fill quickly in the presence of sediment delivery, they often need to be flushed, many times within a day in Alpine glaciated catchments with high sediment yields. The associated short duration "flood" flow is characterised by very high sediment concentrations, which may drastically modify downstream habitat, both during the floods but also due to subsequent accumulation of "legacy" sediment. The impacts on flora and fauna of these systems have not been well studied. In addition, there are no guidelines established that might allow the design of "e-flows" that also treat this sediment problem, something we call "sed-flows". Through an Alpine field example, we quantify the hydrological, geomorphological, and ecosystem impacts of Alpine water transfer systems. The high sediment concentrations of these flushing flows lead to very high rates of channel disturbance downstream, superimposed upon long-term and progressive bed sediment accumulation. Monthly macroinvertebrate surveys over almost a two-year period showed that reductions in the flushing rate reduced rates of disturbance substantially, and led to rapid macroinvertebrate recovery, even in the seasons (autumn and winter) when biological activity should be reduced
Ogston, A. S.; Walsh, J. P.; Hale, R. P.
2011-12-01
The relationships between sediment-transport processes, short-term sedimentary deposition, subsequent burial, and long-term accumulation are critical to understanding the morphological development of the continental margin. This study focuses on processes involved in formation and evolution of the clinoform in the Gulf of Papua, Papua New Guinea in which much of the riverine sediment accumulates, and comparison to those processes active off the Waipaoa River, New Zealand that form mid-shelf deposits and export sediment to the slope. In tidally dominated deltas, sediment discharged from the river sources must transit through an estuarine region located within the distributary channels, where particle pathways can undergo significant transformations. Within the distributaries of the Fly River tidally dominated delta, near-bed fluid-mud concentrations were observed at the estuarine turbidity maximum and sediment delivery to the nearshore was controlled by the morphology and gradient of the distributary. El Niño results in anonymously low flow and sediment discharge conditions, which limits transport of sediment from the distributaries to the nearshore zone of temporary storage. Because the sediment stored nearshore feeds the prograding clinoform, this perturbation propagates throughout the dispersal system. In wave-dominated regions, transport mechanisms actively move sediment away from the river source, separating the site of deposition and accumulation from the river mouth. River-flood and storm-wave events each create discrete deposits on the Waipaoa River shelf and data has been collected to determine their form, distribution, and relationship to factors such as flood magnitude or wave energy. In this case, transport pathways appear to be influenced by structurally controlled shelf bathymetry. In both cases, the combined fluvial and marine processes can initiate and maintain gravity-driven density flows, and although their triggers and controls differ vastly
Energy Technology Data Exchange (ETDEWEB)
Perruchot-Triboulet, S.; Sanchez, R.
1997-12-01
The modification of the isotopic composition, the temperature or even accounting for across section uncertainties in one part of a nuclear reactor core, affects the value of the effective multiplication factor. A new tool allows the analysis of the reactivity effect generated by the modification of the system. With the help of the direct and adjoint fluxes, a detailed balance of reactivity, between the compared systems, is done for each isotopic cross section. After the presentation of the direct and adjoint transport equations in the context of the multigroup code transport APOLLO2, this note describes the method, based on perturbation theory, for the analysis of the reactivity variation. An example application is also given. (author).
DEFF Research Database (Denmark)
Köyluoglu, H.U.; Nielsen, Søren R.K.; Cakmak, A.S.
1994-01-01
perturbation method using stochastic differential equations. The joint statistical moments entering the perturbation solution are determined by considering an augmented dynamic system with state variables made up of the displacement and velocity vector and their first and second derivatives with respect......The paper deals with the first and second order statistical moments of the response of linear systems with random parameters subject to random excitation modelled as white-noise multiplied by an envelope function with random parameters. The method of analysis is basically a second order...... to the random parameters of the problem. Equations for partial derivatives are obtained from the partial differentiation of the equations of motion. The zero time-lag joint statistical moment equations for the augmented state vector are derived from the Itô differential formula. General formulation is given...
Generation of hyperchaos from the Chen-Lee system via sinusoidal perturbation
Energy Technology Data Exchange (ETDEWEB)
Tam, L.M. [Department of Electromechanical Engineering, Faculty of Science and Technology, University of Macau, Av. Padre Thomas Pereira S.J., Taipa, Macau (China)], E-mail: fstlmt@umac.mo; Chen, J.H. [Department of Mechanical Engineering, Chung Hua University, Hsinchu, Taiwan (China); Chen, H.K. [Department of Mechanical Engineering, Hsiuping Institute of Technology, Taichung, Taiwan (China); Wai Meng Si Tou [Department of Electromechanical Engineering, Faculty of Science and Technology, University of Macau, Av. Padre Thomas Pereira S.J., Taipa, Macau (China)
2008-11-15
A system with more than one positive Lyapunov exponent can be classified as a hyperchaotic system. In this study, a sinusoidal perturbation was designed for generating hyperchaos from the Chen-Lee chaotic system. The hyperchaos was identified by the existence of two positive Lyapunov exponents and bifurcation diagrams. The system is hyperchaotic in several different regions of the parameters c, {epsilon}, and {omega}. It was found that this method not only can enhance or suppress chaotic behavior, but also induces chaos in non-chaotic parameter ranges. In addition, two interesting dynamical behaviors, Hopf bifurcation and intermittency, were also found in this study.
Generation of hyperchaos from the Chen-Lee system via sinusoidal perturbation
International Nuclear Information System (INIS)
Tam, L.M.; Chen, J.H.; Chen, H.K.; Wai Meng Si Tou
2008-01-01
A system with more than one positive Lyapunov exponent can be classified as a hyperchaotic system. In this study, a sinusoidal perturbation was designed for generating hyperchaos from the Chen-Lee chaotic system. The hyperchaos was identified by the existence of two positive Lyapunov exponents and bifurcation diagrams. The system is hyperchaotic in several different regions of the parameters c, ε, and ω. It was found that this method not only can enhance or suppress chaotic behavior, but also induces chaos in non-chaotic parameter ranges. In addition, two interesting dynamical behaviors, Hopf bifurcation and intermittency, were also found in this study
System-level perturbations of cell metabolism using CRISPR/Cas9
DEFF Research Database (Denmark)
Jakociunas, Tadas; Jensen, Michael Krogh; Keasling, Jay
2017-01-01
CRISPR/Cas9 (clustered regularly interspaced palindromic repeats and the associated protein Cas9) techniques have made genome engineering and transcriptional reprogramming studies more advanced and cost-effective. For metabolic engineering purposes, the CRISPR-based tools have been applied...... previously possible. In this mini-review we highlight recent studies adopting CRISPR/Cas9 for systems-level perturbations and model-guided metabolic engineering....
A robust computational technique for a system of singularly perturbed reaction–diffusion equations
Directory of Open Access Journals (Sweden)
Kumar Vinod
2014-06-01
Full Text Available In this paper, a singularly perturbed system of reaction–diffusion Boundary Value Problems (BVPs is examined. To solve such a type of problems, a Modified Initial Value Technique (MIVT is proposed on an appropriate piecewise uniform Shishkin mesh. The MIVT is shown to be of second order convergent (up to a logarithmic factor. Numerical results are presented which are in agreement with the theoretical results.
Directory of Open Access Journals (Sweden)
Abdoul R. Ghotbi
2008-01-01
Full Text Available Due to wide range of interest in use of bioeconomic models to gain insight into the scientific management of renewable resources like fisheries and forestry, homotopy perturbation method is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort prey harvesting. The results are compared with the results obtained by Adomian decomposition method. The results show that, in new model, there are less computations needed in comparison to Adomian decomposition method.
A Newton-Based Extremum Seeking MPPT Method for Photovoltaic Systems with Stochastic Perturbations
Directory of Open Access Journals (Sweden)
Heng Li
2014-01-01
Full Text Available Microcontroller based maximum power point tracking (MPPT has been the most popular MPPT approach in photovoltaic systems due to its high flexibility and efficiency in different photovoltaic systems. It is well known that PV systems typically operate under a range of uncertain environmental parameters and disturbances, which implies that MPPT controllers generally suffer from some unknown stochastic perturbations. To address this issue, a novel Newton-based stochastic extremum seeking MPPT method is proposed. Treating stochastic perturbations as excitation signals, the proposed MPPT controller has a good tolerance of stochastic perturbations in nature. Different from conventional gradient-based extremum seeking MPPT algorithm, the convergence rate of the proposed controller can be totally user-assignable rather than determined by unknown power map. The stability and convergence of the proposed controller are rigorously proved. We further discuss the effects of partial shading and PV module ageing on the proposed controller. Numerical simulations and experiments are conducted to show the effectiveness of the proposed MPPT algorithm.
A Perturbation Analysis of Harmonics Generation from Saturated Elements in Power Systems
Kumano, Teruhisa
Nonlinear phenomena such as saturation in magnetic flux give considerable effects in power system analysis. It is reported that a failure in a real 500kV system triggered islanding operation, where resultant even harmonics caused malfunctions in protective relays. It is also reported that the major origin of this wave distortion is nothing but unidirectional magnetization of the transformer iron core. Time simulation is widely used today to analyze this type of phenomena, but it has basically two shortcomings. One is that the time simulation takes two much computing time in the vicinity of inflection points in the saturation characteristic curve because certain iterative procedure such as N-R (Newton-Raphson) should be used and such methods tend to be caught in an ill conditioned numerical hunting. The other is that such simulation methods sometimes do not help intuitive understanding of the studied phenomenon because the whole nonlinear equations are treated in a matrix form and not properly divided into understandable parts as done in linear systems. This paper proposes a new computation scheme which is based on so called perturbation method. Magnetic saturation in iron cores in a generator and a transformer are taken into account. The proposed method has a special feature against the first shortcoming of the N-R based time simulation method stated above. In the proposed method no iterative process is used to reduce the equation residue but uses perturbation series, which means free from the ill condition problem. Users have only to calculate each perturbation terms one by one until he reaches necessary accuracy. In a numerical example treated in the present paper the first order perturbation can make reasonably high accuracy, which means very fast computing. In numerical study three nonlinear elements are considered. Calculated results are almost identical to the conventional Newton-Raphson based time simulation, which shows the validity of the method. The
Upper and Lower Bounds of Frequency Interval Gramians for a Class of Perturbed Linear Systems
DEFF Research Database (Denmark)
Shaker, Hamid Reza
2012-01-01
if the system is controllable or observable, but also it is required to know the degree of controllability or observability of the system. Gramian matrices were introduced to address this issue by providing a quantitative measure for controllability and observability. In many applications, the information...... of uncertain systems. In this paper, we derive upper and lower bounds of frequency interval gramians under perturbations of an A-matrix in the state-space form. These bounds are obtained by solving algebraic Riccati equations. The results are further used to obtain upper and lower bounds of the frequency...
International Nuclear Information System (INIS)
Ren-Tai, Chiang
2003-01-01
An ω-mode first-order perturbation theory is developed for analyzing the time- and space-dependent neutron behavior in Accelerator-Driven Subcritical Systems (ADSS). The generalized point-kinetics equations are systematically derived using the ω-mode first-order perturbation theory and Fredholm Alternative Theorem. Seven sets of the ω-mode eigenvalues exist with using six groups of delayed neutrons and all ω eigenvalues are negative in ADSS. Seven ω-mode adjoint and forward eigenfunctions are employed to form the point-kinetic parameters. The neutron flux is expressed as a linear combination of the products of seven ω-eigenvalue-mode shape functions and their corresponding time functions up to the first order terms, and the lowest negative ω-eigenvalue mode is the dominant mode. (author)
International Nuclear Information System (INIS)
Roberts, W.W.; Stewart, G.R.
1987-03-01
Investigations of the collisional evolution of particulate disks subject to the gravitational perturbation of a more massive particle orbiting within the disk are underway. Both numerical N-body simulations using a novel collision algorithm and analytical kinetic theory are being employed to extend our understanding of perturbed disks in planetary rings and during the formation of the solar system. Particular problems proposed for investigation are: (1) The development and testing of general criteria for a small moonlet to clear a gap and produce observable morphological features in planetary rings; (2) The development of detailed models of collisional damping of the wavy edges observed on the Encke division of Saturn's A ring; and (3) The determination of the extent of runaway growth of the few largest planetesimals during the early stages of planetary accretion
Spatial dynamics of overbank sedimentation in floodplain systems
Pierce, Aaron R.; King, S.L.
2008-01-01
Floodplains provide valuable social and ecological functions, and understanding the rates and patterns of overbank sedimentation is critical for river basin management and rehabilitation. Channelization of alluvial systems throughout the world has altered hydrological and sedimentation processes within floodplain ecosystems. In the loess belt region of the Lower Mississippi Alluvial Valley of the United States, channelization, the geology of the region, and past land-use practices have resulted in the formation of dozens of valley plugs in stream channels and the formation of shoals at the confluence of stream systems. Valley plugs completely block stream channels with sediment and debris and can result in greater deposition rates on floodplain surfaces. Presently, however, information is lacking on the rates and variability of overbank sedimentation associated with valley plugs and shoals. We quantified deposition rates and textures in floodplains along channelized streams that contained valley plugs and shoals, in addition to floodplains occurring along an unchannelized stream, to improve our understanding of overbank sedimentation associated with channelized streams. Feldspar clay marker horizons and marker poles were used to measure floodplain deposition from 2002 to 2005 and data were analyzed with geospatial statistics to determine the spatial dynamics of sedimentation within the floodplains. Mean sediment deposition rates ranged from 0.09 to 0.67??cm/y at unchannelized sites, 0.16 to 2.27??cm/y at shoal sites, and 3.44 to 6.20??cm/y at valley plug sites. Valley plug sites had greater rates of deposition, and the deposited sediments contained more coarse sand material than either shoal or unchannelized sites. A total of 59 of 183 valley plug study plots had mean deposition rates > 5??cm/y. The geospatial analyses showed that the spatial dynamics of sedimentation can be influenced by the formation of valley plugs and shoals on channelized streams; however
Wang, Yajie; Shi, Yunbo; Yu, Xiaoyu; Liu, Yongjie
2016-01-01
Currently, tracking in photovoltaic (PV) systems suffers from some problems such as high energy consumption, poor anti-interference performance, and large tracking errors. This paper presents a solar PV tracking system on the basis of an improved perturbation and observation method, which maximizes photoelectric conversion efficiency. According to the projection principle, we design a sensor module with a light-intensity-detection module for environmental light-intensity measurement. The effect of environmental factors on the system operation is reduced, and intelligent identification of the weather is realized. This system adopts the discrete-type tracking method to reduce power consumption. A mechanical structure with a level-pitch double-degree-of-freedom is designed, and attitude correction is performed by closed-loop control. A worm-and-gear mechanism is added, and the reliability, stability, and precision of the system are improved. Finally, the perturbation and observation method designed and improved by this study was tested by simulated experiments. The experiments verified that the photoelectric sensor resolution can reach 0.344°, the tracking error is less than 2.5°, the largest improvement in the charge efficiency can reach 44.5%, and the system steadily and reliably works. PMID:27327657
Directory of Open Access Journals (Sweden)
Yajie Wang
Full Text Available Currently, tracking in photovoltaic (PV systems suffers from some problems such as high energy consumption, poor anti-interference performance, and large tracking errors. This paper presents a solar PV tracking system on the basis of an improved perturbation and observation method, which maximizes photoelectric conversion efficiency. According to the projection principle, we design a sensor module with a light-intensity-detection module for environmental light-intensity measurement. The effect of environmental factors on the system operation is reduced, and intelligent identification of the weather is realized. This system adopts the discrete-type tracking method to reduce power consumption. A mechanical structure with a level-pitch double-degree-of-freedom is designed, and attitude correction is performed by closed-loop control. A worm-and-gear mechanism is added, and the reliability, stability, and precision of the system are improved. Finally, the perturbation and observation method designed and improved by this study was tested by simulated experiments. The experiments verified that the photoelectric sensor resolution can reach 0.344°, the tracking error is less than 2.5°, the largest improvement in the charge efficiency can reach 44.5%, and the system steadily and reliably works.
Wang, Yajie; Shi, Yunbo; Yu, Xiaoyu; Liu, Yongjie
2016-01-01
Currently, tracking in photovoltaic (PV) systems suffers from some problems such as high energy consumption, poor anti-interference performance, and large tracking errors. This paper presents a solar PV tracking system on the basis of an improved perturbation and observation method, which maximizes photoelectric conversion efficiency. According to the projection principle, we design a sensor module with a light-intensity-detection module for environmental light-intensity measurement. The effect of environmental factors on the system operation is reduced, and intelligent identification of the weather is realized. This system adopts the discrete-type tracking method to reduce power consumption. A mechanical structure with a level-pitch double-degree-of-freedom is designed, and attitude correction is performed by closed-loop control. A worm-and-gear mechanism is added, and the reliability, stability, and precision of the system are improved. Finally, the perturbation and observation method designed and improved by this study was tested by simulated experiments. The experiments verified that the photoelectric sensor resolution can reach 0.344°, the tracking error is less than 2.5°, the largest improvement in the charge efficiency can reach 44.5%, and the system steadily and reliably works.
International Nuclear Information System (INIS)
Awan, M.M.A.; Awan, F.G.
2017-01-01
Extraction of maximum power from PV (Photovoltaic) cell is necessary to make the PV system efficient. Maximum power can be achieved by operating the system at MPP (Maximum Power Point) (taking the operating point of PV panel to MPP) and for this purpose MPPT (Maximum Power Point Trackers) are used. There are many tracking algorithms/methods used by these trackers which includes incremental conductance, constant voltage method, constant current method, short circuit current method, PAO (Perturb and Observe) method, and open circuit voltage method but PAO is the mostly used algorithm because it is simple and easy to implement. PAO algorithm has some drawbacks, one is low tracking speed under rapid changing weather conditions and second is oscillations of PV systems operating point around MPP. Little improvement is achieved in past papers regarding these issues. In this paper, a new method named 'Decrease and Fix' method is successfully introduced as improvement in PAO algorithm to overcome these issues of tracking speed and oscillations. Decrease and fix method is the first successful attempt with PAO algorithm for stability achievement and speeding up of tracking process in photovoltaic system. Complete standalone photovoltaic system's model with improved perturb and observe algorithm is simulated in MATLAB Simulink. (author)
Green’s functions for spin boson systems: Beyond conventional perturbation theories
Energy Technology Data Exchange (ETDEWEB)
Liu, Junjie [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Xu, Hui [Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Wu, Chang-Qin [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China)
2016-12-20
Unraveling general properties of Green’s functions of quantum dissipative systems is of both experimental relevance and theoretical interest. Here, we study the spin-boson model as a prototype. By utilizing the Majorana-fermion representation together with the polaron transformation, we establish a theoretical approach to analyze Green’s functions of the spin-boson model. In contrast to conventional perturbation theories either in the tunneling energy or in the system-bath coupling strength, the proposed scheme gives reliable results over wide regimes of the coupling strength, bias, as well as temperature. To demonstrate the utility of the approach, we consider the susceptibility as well as the symmetrized spin correlation function (SSCF) which can be expressed in terms of Green’s functions. Thorough investigations are made on systems embedded in Ohmic or sub-Ohmic bosonic baths. We found the so-obtained SSCF is the same as that of the non-interacting blip approximation (NIBA) in unbiased systems while it is applicable for a wider range of temperature in the biased systems compared with the NIBA. We also show that a previous perturbation result is recovered as a weak coupling limit of the so-obtained SSCF. Furthermore, by studying the quantum criticality of the susceptibility, we confirm the validity of the quantum-to-classical mapping in the whole sub-Ohmic regime.
International Nuclear Information System (INIS)
Garcia, Juan Matias
2005-01-01
Perturbation Methods represent a powerful tool to do sensitivity analysis, and they found many aplications in nuclear engineering.As an introduction to this kind of analysis, we develope a program that apply the Generalized Perturbation Theory or GPT Method to bidimensional system of rectangular geometry.We first consider an homogeneous system of non-multiplying material and then an heterogeneous system with region of multiplying material, with the intention of make concret aplications of perturbation method to nuclear engineering problems.The program, that we called Pert, determines neutron fluxes and importance functions applying the Multigroup Diffusion Theory; and also solves the integrals required to calculate sensitivity coefficients.Using this perturbation methods we could verify the low computational cost required to make this kind of analysis and the simplicity of the equations systems involved, allowing us to make elaborates sensitivity analysis for the responses of our interest
Reliability importance analysis of Markovian systems at steady state using perturbation analysis
Energy Technology Data Exchange (ETDEWEB)
Phuc Do Van [Institut Charles Delaunay - FRE CNRS 2848, Systems Modeling and Dependability Group, Universite de technologie de Troyes, 12, rue Marie Curie, BP 2060-10010 Troyes cedex (France); Barros, Anne [Institut Charles Delaunay - FRE CNRS 2848, Systems Modeling and Dependability Group, Universite de technologie de Troyes, 12, rue Marie Curie, BP 2060-10010 Troyes cedex (France)], E-mail: anne.barros@utt.fr; Berenguer, Christophe [Institut Charles Delaunay - FRE CNRS 2848, Systems Modeling and Dependability Group, Universite de technologie de Troyes, 12, rue Marie Curie, BP 2060-10010 Troyes cedex (France)
2008-11-15
Sensitivity analysis has been primarily defined for static systems, i.e. systems described by combinatorial reliability models (fault or event trees). Several structural and probabilistic measures have been proposed to assess the components importance. For dynamic systems including inter-component and functional dependencies (cold spare, shared load, shared resources, etc.), and described by Markov models or, more generally, by discrete events dynamic systems models, the problem of sensitivity analysis remains widely open. In this paper, the perturbation method is used to estimate an importance factor, called multi-directional sensitivity measure, in the framework of Markovian systems. Some numerical examples are introduced to show why this method offers a promising tool for steady-state sensitivity analysis of Markov processes in reliability studies.
Reliability importance analysis of Markovian systems at steady state using perturbation analysis
International Nuclear Information System (INIS)
Phuc Do Van; Barros, Anne; Berenguer, Christophe
2008-01-01
Sensitivity analysis has been primarily defined for static systems, i.e. systems described by combinatorial reliability models (fault or event trees). Several structural and probabilistic measures have been proposed to assess the components importance. For dynamic systems including inter-component and functional dependencies (cold spare, shared load, shared resources, etc.), and described by Markov models or, more generally, by discrete events dynamic systems models, the problem of sensitivity analysis remains widely open. In this paper, the perturbation method is used to estimate an importance factor, called multi-directional sensitivity measure, in the framework of Markovian systems. Some numerical examples are introduced to show why this method offers a promising tool for steady-state sensitivity analysis of Markov processes in reliability studies
Vardhan, Shreya; De Tomasi, Giuseppe; Heyl, Markus; Heller, Eric J.; Pollmann, Frank
2017-07-01
We study the effects of local perturbations on the dynamics of disordered fermionic systems in order to characterize time irreversibility. We focus on three different systems: the noninteracting Anderson and Aubry-André-Harper (AAH) models and the interacting spinless disordered t -V chain. First, we consider the effect on the full many-body wave functions by measuring the Loschmidt echo (LE). We show that in the extended or ergodic phase the LE decays exponentially fast with time, while in the localized phase the decay is algebraic. We demonstrate that the exponent of the decay of the LE in the localized phase diverges proportionally to the single-particle localization length as we approach the metal-insulator transition in the AAH model. Second, we probe different phases of disordered systems by studying the time expectation value of local observables evolved with two Hamiltonians that differ by a spatially local perturbation. Remarkably, we find that many-body localized systems could lose memory of the initial state in the long-time limit, in contrast to the noninteracting localized phase where some memory is always preserved.
Asymptotic behavior of dynamical and control systems under perturbation and discretization
Grüne, Lars
2002-01-01
This book provides an approach to the study of perturbation and discretization effects on the long-time behavior of dynamical and control systems. It analyzes the impact of time and space discretizations on asymptotically stable attracting sets, attractors, asumptotically controllable sets and their respective domains of attractions and reachable sets. Combining robust stability concepts from nonlinear control theory, techniques from optimal control and differential games and methods from nonsmooth analysis, both qualitative and quantitative results are obtained and new algorithms are developed, analyzed and illustrated by examples.
Liu, Xiao
2017-03-21
Privacy risks of recommender systems have caused increasing attention. Users’ private data is often collected by probably untrusted recommender system in order to provide high-quality recommendation. Meanwhile, malicious attackers may utilize recommendation results to make inferences about other users’ private data. Existing approaches focus either on keeping users’ private data protected during recommendation computation or on preventing the inference of any single user’s data from the recommendation result. However, none is designed for both hiding users’ private data and preventing privacy inference. To achieve this goal, we propose in this paper a hybrid approach for privacy-preserving recommender systems by combining differential privacy (DP) with randomized perturbation (RP). We theoretically show the noise added by RP has limited effect on recommendation accuracy and the noise added by DP can be well controlled based on the sensitivity analysis of functions on the perturbed data. Extensive experiments on three large-scale real world datasets show that the hybrid approach generally provides more privacy protection with acceptable recommendation accuracy loss, and surprisingly sometimes achieves better privacy without sacrificing accuracy, thus validating its feasibility in practice.
Inner-shell correlations and Sturm expansions in coupled perturbation calculations of atomic systems
International Nuclear Information System (INIS)
Sherstyuk, A.I.; Solov'eva, G.S.
1995-01-01
It is shown that virtual Hartree-Fock orbitals in Sturm-type expansions can be used to calculate the response of atomic systems to an external field within the framework of the coupled perturbation theory with allowance for correlation effects. The corrected electron-electron interaction in a system with field-distorted orbitals is considered by adding a nonlocal potential to a one-electron Hartree-Fock operator within each group of equivalent elections. The remaining correlation effects are calculated by solving a system of equations for corrections to the radial functions. The system is solved iteratively, with each subsequent iteration corresponding to a correction of an increasingly higher order in the electron--electron interaction. The explicit expression derived for the polarizability contains one-and two-particle radial integrals of the Sturm functions
Review of Innovative Sediment Delivery Systems
2013-04-01
Alternative conveyor belt systems appear to be available from the growing hydraulic fracturing ( fracking , shale gas recovery) industry, which use...tons of aggregate material (with diameters up to 2 in.) per hour. This equates to roughly 150 cu yd per hr, de- pending on sand density. As fracking
An Earth system view on boundaries for human perturbation of the N and P cycles
Cornell, Sarah; de Vries, Wim
2015-04-01
The appropriation and transformation of land, water, and living resources can alter Earth system functioning, and potentially undermine the basis for the sustainability of our societies. Human activities have greatly increased the flows of reactive forms of nitrogen (N) and phosphorus (P) in the Earth system. These non-substitutable nutrient elements play a fundamental role in the human food system. Furthermore, the current mode of social and economic globalization, and its effect on the present-day energy system, also has large effects including large NOx-N emissions through combustion. Until now, this perturbation of N and P cycles has been treated largely as a local/regional issue, and managed in terms of direct impacts (water, land or air pollution). However, anthropogenic N and P cycle changes affect physical Earth system feedbacks (through greenhouse gas and aerosol changes) and biogeochemical feedbacks (via ecosystem changes, links to the carbon cycle, and altered nutrient limitation) with impacts that can be far removed from the direct sources. While some form of N and P management at the global level seems likely to be needed for continued societal development, the current local-level and sectorial management is often problematically simplistic, as seen in the tensions between divergent N management needs for climate change mitigation, air pollution control, food production, and ecosystem conservation. We require a step change in understanding complex biogeochemical, physical and socio-economic interactions in order to analyse these effects together, and inform policy trade-offs to minimize emergent systemic risks. Planetary boundaries for N and P cycle perturbation have recently been proposed. We discuss the current status of these precautionary boundaries and how we may improve on these preliminary assessments. We present an overview of the human perturbation of the global biogeochemical cycles of N and P and its interaction with the functioning of the
Dynamic behaviors of the periodic Lotka-Volterra competing system with impulsive perturbations
International Nuclear Information System (INIS)
Liu Bing; Teng Zhidong; Liu Wanbo
2007-01-01
In this paper, we investigate a classical periodic Lotka-Volterra competing system with impulsive perturbations. The conditions for the linear stability of trivial periodic solution and semi-trivial periodic solutions are given by applying Floquet theory of linear periodic impulsive equation, and we also give the conditions for the global stability of these solutions as a consequence of some abstract monotone iterative schemes introduced in this paper, which will be also used to get some sufficient conditions for persistence. By using the method of coincidence degree, the conditions for the existence of at least one strictly positive (componentwise) periodic solution are derived. The theoretical results are confirmed by a specific example and numerical simulations. It shows that the dynamic behaviors of the system we consider are quite different from the corresponding system without pulses
''Use of perturbative methods to break down the variation of reactivity between two systems''
International Nuclear Information System (INIS)
Perruchot-Triboulet, S.; Sanchez, R.
1997-01-01
The modification of the isotopic composition, the temperature or even accounting for across section uncertainties in one part of a nuclear reactor core, affects the value of the effective multiplication factor. A new tool allows the analysis of the reactivity effect generated by the modification of the system. With the help of the direct and adjoint fluxes, a detailed balance of reactivity, between the compared systems, is done for each isotopic cross section. After the presentation of the direct and adjoint transport equations in the context of the multigroup code transport APOLLO2, this note describes the method, based on perturbation theory, for the analysis of the reactivity variation. An example application is also given. (author)
Pechukas-Yukawa approach to the evolution of the quantum state of a parametrically perturbed system
Qureshi, Mumnuna A.; Zhong, Johnny; Qureshi, Zihad; Mason, Peter; Betouras, Joseph J.; Zagoskin, Alexandre M.
2018-03-01
We consider the evolution of the quantum states of a Hamiltonian that is parametrically perturbed via a term proportional to the adiabatic parameter λ (t ) . Starting with the Pechukas-Yukawa mapping of the energy eigenvalue evolution in a generalized Calogero-Sutherland model of a one-dimensional classical gas, we consider the adiabatic approximation with two different expansions of the quantum state in powers of d λ /d t and compare them with a direct numerical simulation. We show that one of these expansions (Magnus series) is especially convenient for the description of nonadiabatic evolution of the system. Applying the expansion to the exact cover 3-satisfiability problem, we obtain the occupation dynamics, which provides insight into the population of states and sources of decoherence in a quantum system.
Ma, Christina Zong-Hao; Lee, Winson Chiu-Chun
2017-10-01
Maintaining postural equilibrium requires fast reactions and constant adjustments of the center of mass (CoM) position to prevent falls, especially when there is a sudden perturbation of the support surface. During this study, a newly developed wearable feedback system provided immediate vibrotactile clues to users based on plantar force measurement, in an attempt to reduce reaction time and CoM displacement in response to a perturbation of the floor. Ten healthy young adults participated in this study. They stood on a support surface, which suddenly moved in one of four horizontal directions (forward, backward, left and right), with the biofeedback system turned on or off. The testing sequence of the four perturbation directions and the two system conditions (turned on or off) was randomized. The resulting reaction time and CoM displacement were analysed. Results showed that the vibrotactile feedback system significantly improved balance control during translational perturbations. The positive results of this preliminary study highlight the potential of a plantar force measurement based biofeedback system in improving balance under perturbations of the support surface. Future system optimizations could facilitate its application in fall prevention in real life conditions, such as standing in buses or trains that suddenly decelerate or accelerate. Copyright © 2017 Elsevier B.V. All rights reserved.
Chakon, Ofir; Or, Yizhar
2017-08-01
Underactuated robotic locomotion systems are commonly represented by nonholonomic constraints where in mixed systems, these constraints are also combined with momentum evolution equations. Such systems have been analyzed in the literature by exploiting symmetries and utilizing advanced geometric methods. These works typically assume that the shape variables are directly controlled, and obtain the system's solutions only via numerical integration. In this work, we demonstrate utilization of the perturbation expansion method for analyzing a model example of mixed locomotion system—the twistcar toy vehicle, which is a variant of the well-studied roller-racer model. The system is investigated by assuming small-amplitude oscillatory inputs of either steering angle (kinematic) or steering torque (mechanical), and explicit expansions for the system's solutions under both types of actuation are obtained. These expressions enable analyzing the dependence of the system's dynamic behavior on the vehicle's structural parameters and actuation type. In particular, we study the reversal in direction of motion under steering angle oscillations about the unfolded configuration, as well as influence of the choice of actuation type on convergence properties of the motion. Some of the findings are demonstrated qualitatively by reporting preliminary motion experiments with a modular robotic prototype of the vehicle.
Rate of recovery from perturbations as a means to forecast future stability of living systems.
Ghadami, Amin; Gourgou, Eleni; Epureanu, Bogdan I
2018-06-18
Anticipating critical transitions in complex ecological and living systems is an important need because it is often difficult to restore a system to its pre-transition state once the transition occurs. Recent studies demonstrate that several indicators based on changes in ecological time series can indicate that the system is approaching an impending transition. An exciting question is, however, whether we can predict more characteristics of the future system stability using measurements taken away from the transition. We address this question by introducing a model-less forecasting method to forecast catastrophic transition of an experimental ecological system. The experiment is based on the dynamics of a yeast population, which is known to exhibit a catastrophic transition as the environment deteriorates. By measuring the system's response to perturbations prior to transition, we forecast the distance to the upcoming transition, the type of the transition (i.e., catastrophic/non-catastrophic) and the future equilibrium points within a range near the transition. Experimental results suggest a strong potential for practical applicability of this approach for ecological systems which are at risk of catastrophic transitions, where there is a pressing need for information about upcoming thresholds.
Devices, systems, and methods for detecting nucleic acids using sedimentation
Energy Technology Data Exchange (ETDEWEB)
Koh, Chung-Yan; Schaff, Ulrich Y.; Sommer, Gregory J.
2017-10-24
Embodiments of the present invention are directed toward devices, systems, and method for conducting nucleic acid purification and quantification using sedimentation. In one example, a method includes generating complexes which bind to a plurality of beads in a fluid sample, individual ones of the complexes comprising a nucleic acid molecule such as DNA or RNA and a labeling agent. The plurality of beads including the complexes may be transported through a density media, wherein the density media has a density lower than a density of the beads and higher than a density of the fluid sample, and wherein the transporting occurs, at least in part, by sedimentation. Signal may be detected from the labeling agents of the complexes.
Design of a Resonant Magnetic Perturbation ELM Suppression System for JET
International Nuclear Information System (INIS)
Agarici, G.; Becoulet, M.; Nardon, E.; Saille, A.; Thomas, P.R.; Verger, J.M.
2006-01-01
The suppression of ELMs with a Resonant Magnetic Perturbation (RMP), as demonstrated in DIIID experiments, is an attractive solution to the problem of divertor target erosion in ITER. Ideally, the RMP should be strong at the plasma edge and weak in the core, which requires the installation of the RMP coils as close as possible to the plasma. In both ITER and JET, an installation within the vacuum vessel would subject the coils to neutron irradiation, tritium contamination and all the problems of furnishing cooling and electrical services, across many interfaces. It has been proposed to install an '' ITER prototype '' RMP on JET. The nearest ex-vessel location, which avoids these difficulties and permits a suitable perturbation field, is between the poloidal field coils, P3 and P4. The proposed RMP system consists of 18 upper and 18 lower Ergodic field coils, arranged around the torus and located ∼ 2.5 m from the plasma edge. Each coil measures 0.9 m poloidally and 1.8 m toroidally, with a 30 cm cross-section and a weight near 1,4 tonne. 400 kA per coil are necessary to produce the radial magnetic field perturbation required for a plasma of 4 MA/3.4 T. Using a standard rectangular water-cooled conductor (OFHC copper plate 50 x 12.5 mm 2 with two holes inside), the coil can be built by winding 6 x 12 turns. In order to generate the required toroidal mode, n = 3, the current direction inside the coils will alternate every 3 coils. Vertical forces, up to 36 tonnes, and radial forces, up to 18 tonnes, due to the interaction between the machine main magnetic field and the coil current are withstood by a circular structure of 4 m diameter, made-out of 2 cm thick stainless-steel plates. Since the structure is toroidally continuous, the total radial forces counter balance each-other, whilst, via vertical supports, the vertical forces are taken by the 8 iron limbs of the external magnetic circuit. The installation of the coils is simplified by the circular geometry of the
Quasidynamic emergency analysis, identification and control of power system frequency perturbations
Energy Technology Data Exchange (ETDEWEB)
Jovanovic, S M [Nikola Tesla Institute, Belgrade (YU)
1990-07-01
There are several possible operating states of a power system. These are the normal operating state (both secure and insecure), the emergency state, the extreme emergency state and the restorative state. The system enters the emergency operating state if any of the operating constraints are violated. Emergency analysis attempts to compute in real time the violations of these constraints and the new (successive) disturbances which arise from the initial ones. The paper presents a quasidynamic approach to emergency state analysis, identification and control of power system frequency perturbations. A quasidynamic model is derived by simplifying the conventional long-term dynamics model of power systems in the time interval 0-5 s. The quasidynamic model is algebraic in nature, but the time variable t is incorporated into the model and is used to describe the part of the system dynamics that is of interest in the specified time interval. The paper proposes an on-line computer emergency control strategy based on the above quasidynamic model. Finally, a numerical example is given for the Yugoslav power system. (author).
Pereira, CF; Pasquini, C
2010-01-01
A flow system is proposed to produce a concentration perturbation in liquid samples, aiming at the generation of two-dimensional correlation near-infrared spectra. The system presents advantages in relation to batch systems employed for the same purpose: the experiments are accomplished in a closed system; application of perturbation is rapid and easy; and the experiments can be carried out with micro-scale volumes. The perturbation system has been evaluated in the investigation and selection...
International Nuclear Information System (INIS)
Zushi, H.; Kuzmin, A.; Hasegawa, M.; Yoshida, N.; Fujisawa, A.; Hanada, K.; Idei, H.; Nakamura, K.; Nagashima, Y.; Onchi, T.; Takagi, I.; Fukuyama, A.; Sharma, S.K.; Kobayashi, M.; Hirooka, Y.; Zhou, H.; Matsuoka, K.; Kubo, S.; Rusinov, A.; Inoue, A.; Tashima, S.; Banerjee, S.; Sakaguchi, M.; Kalinnikova, E.; Mishra, K.; Liu, X.; Ueda, Y.; Fujita, T.; Ohno, N.; Ide, Shunsuke; Hatayama, A.; Ejiri, A.; Yamaguchi, T.; Hiratsuka, J.; Togashi, H.; Takase, Y.; Mitarai, O.
2014-10-01
The global gas balance in the various types of steady discharges has been re-examined by measuring the partial pressures of hydrogen and helium, and plasma induced permeated flux at various positions. A new approach to study the dynamics of particle circulation in steady state tokamak operation SSTO has been proposed and demonstrated in QUEST with all metal walls baked at 100°C. Using perturbations of particle source H 2 and plasma-wall interaction PWI the system functions of processes of retention and release into/from the wall are determined both in time and frequency domains. The time dependent probability function of the transition between high and low recycling states has been derived. (author)
Directory of Open Access Journals (Sweden)
Jian Liu
Full Text Available In this paper, adaptive control is extended from real space to complex space, resulting in a new control scheme for a class of n-dimensional time-dependent strict-feedback complex-variable chaotic (hyperchaotic systems (CVCSs in the presence of uncertain complex parameters and perturbations, which has not been previously reported in the literature. In detail, we have developed a unified framework for designing the adaptive complex scalar controller to ensure this type of CVCSs asymptotically stable and for selecting complex update laws to estimate unknown complex parameters. In particular, combining Lyapunov functions dependent on complex-valued vectors and back-stepping technique, sufficient criteria on stabilization of CVCSs are derived in the sense of Wirtinger calculus in complex space. Finally, numerical simulation is presented to validate our theoretical results.
Liu, Jian; Liu, Kexin; Liu, Shutang
2017-01-01
In this paper, adaptive control is extended from real space to complex space, resulting in a new control scheme for a class of n-dimensional time-dependent strict-feedback complex-variable chaotic (hyperchaotic) systems (CVCSs) in the presence of uncertain complex parameters and perturbations, which has not been previously reported in the literature. In detail, we have developed a unified framework for designing the adaptive complex scalar controller to ensure this type of CVCSs asymptotically stable and for selecting complex update laws to estimate unknown complex parameters. In particular, combining Lyapunov functions dependent on complex-valued vectors and back-stepping technique, sufficient criteria on stabilization of CVCSs are derived in the sense of Wirtinger calculus in complex space. Finally, numerical simulation is presented to validate our theoretical results.
Enantioselective analysis of ibuprofen and its biotransformation products in water/sediment systems,
DEFF Research Database (Denmark)
Sundström, Maria; Escola, Monica; Radke, Michael
2015-01-01
of the sediments in the aquatic systems has neither been taken in account previously. In this study, four water-sediment systems were chosen according to anthropogenic exposure and sediment conditions. A low anthropogenic impact lake (Largen), a river receiving wastewater (Fyrisån) and two sediments (anoxic......As ibuprofen degrades enantioselectively in activated sludge, the same process is assumed to occur in surface lake-water and in river-water based biofilms. Yet, the effects of the wastewater inflow, containing non-racemic ibuprofen, into natural systems have never been studied. The role......-7 days in Tvären and B1 respectively. Largen sediments, not impacted by wastewater, degraded ibuprofen faster than Fyrisån sediments did. Yet, these two sediments sediments showed no significant difference with respect to the degradation rates of the ibuprofen enantiomers. A connection between wastewater...
Extinction and Permanence of a General Predator-Prey System with Impulsive Perturbations
Directory of Open Access Journals (Sweden)
Xianning Liu
2012-01-01
Full Text Available A general predator-prey system is studied in a scheme where there is periodic impulsive perturbations. This scheme has the potential to protect the predator from extinction but under some conditions may also serve to lead to extinction of the prey. Conditions for extinction and permanence are obtained via the comparison methods involving monotone theory of impulsive systems and multiple Liapunov functions, which establish explicit bounds on solutions. The existence of a positive periodic solution is also studied by the bifurcation theory. Application is given to a Lotka-Volterra predator-prey system with periodic impulsive immigration of the predator. It is shown that the results are quite different from the corresponding system without impulsive immigration, where extinction of the prey can never be achieved. The prey will be extinct or permanent independent of whether the system without impulsive effect immigration is permanent or not. The model and its results suggest an approach of pest control which proves more effective than the classical one.
Neptunium and manganese biocycling in nuclear legacy sediment systems
International Nuclear Information System (INIS)
Thorpe, Clare L.; Morris, Katherine; Lloyd, Jonathan R.; Denecke, Melissa A.; Law, Kathleen A.; Dardenne, Kathy; Boothman, Christopher; Bots, Pieter; Law, Gareth T.W.
2015-01-01
Understanding the behaviour of the highly radiotoxic, long half-life radionuclide neptunium in the environment is important for the management of radioactively contaminated land and the safe disposal of radioactive wastes. Recent studies have identified that microbial reduction can reduce the mobility of neptunium via reduction of soluble Np(V) to poorly soluble Np(IV), with coupling to both Mn- and Fe(III)- reduction implicated in neptunyl reduction. To further explore these processes Mn(IV) as δMnO 2 was added to sediment microcosms to create a sediment microcosm experiment “poised” under Mn-reducing conditions. Enhanced removal of Np(V) from solution occurred during Mn-reduction, and parallel X-ray absorption spectroscopy (XAS) studies confirmed Np(V) reduction to Np(IV) commensurate with microbially-mediated Mn-reduction. Molecular ecology analysis of the XAS systems, which contained up to 0.2 mM Np showed no significant impact of elevated Np concentrations on the microbial population. These results demonstrate the importance of Mn cycling on Np biogeochemistry, and clearly highlight new pathways to reductive immobilisation for this highly radiotoxic actinide. - Highlights: • Neptunium is a high radiotoxicity, alpha emitting actinide. • Biostimulation of Mn(IV)-enriched sediments leads to reductive removal of soluble Np(V) from groundwater onto sediments as Np(IV). • Np(V) reduction occurs under defined Mn-reducing conditions. • Under Mn-reducing conditions, enzymatic processes may be important for Np(V) reduction.
Rickaby, R. E.; Young, J. N.; Hermoso, M.; Heureux, A.; McCLelland, H.; Lee, R.; Eason Hubbard, M.
2012-12-01
The ocean and atmosphere carbon system has varied greatly over geological history both in response to initial evolutionary innovation, and as a driver of adaptive change. Here we establish that positive selection in Rubisco, the most abundant enzyme on the Earth responsible for all photosynthetic carbon fixation, occurred early in Earth's history, and basal to the radiation of the modern marine algal groups. Our signals of positive selection appear to be triggered by changing intracellular concentrations of carbon dioxide (CO2) due to the emergence of carbon concentrating mechanisms between 1.56 and 0.41 Ba in response to declining atmospheric CO2 . We contend that, at least in terms of carbon, phytoplankton generally were well poised to manage subsequent abrupt carbon cycle perturbations. The physiological pathways for optimising carbon acquisition across a wide range of ambient carbon dioxide concentrations had already been established and were genetically widespread across open ocean phytoplankton groups. We will further investigate some case studies from the Mesozoic and Cenozoic abrupt carbon cycle excursions using isotopic tools to probe the community photosynthetic response and demonstrate the flexibility of phytoplankton photosynthesis in the face of major perturbations. In particular, an unprecedented resolution record across the Toarcian (Early Jurassic) carbon isotope excursion in the Paris Basin reveals a selection and evolution towards a community reliant solely on diffusive carbon dioxide supply for photosynthesis at the height of the excursion at 1500-2500 ppm CO2. The continued flourishing of the phytoplankton biological pump throughout this excursion was able to remove the excess carbon injected into the water column in less than 45 kyrs.
The Heun equation and the Calogero-Moser-Sutherland system II: Perturbation and algebraic solution
Directory of Open Access Journals (Sweden)
Kouichi Takemura
2004-02-01
Full Text Available We apply a method of perturbation for the $BC_1$ Inozemtsev model from the trigonometric model and show the holomorphy of perturbation. Consequently, the convergence of eigenvalues and eigenfuncions which are expressed as formal power series is proved. We investigate also the relationship between $L^2$ space and some finite dimensional space of elliptic functions.
Adaptive strategies of remote systems operators exposed to perturbed camera-viewing conditions
Stuart, Mark A.; Manahan, Meera K.; Bierschwale, John M.; Sampaio, Carlos E.; Legendre, A. J.
1991-01-01
This report describes a preliminary investigation of the use of perturbed visual feedback during the performance of simulated space-based remote manipulation tasks. The primary objective of this NASA evaluation was to determine to what extent operators exhibit adaptive strategies which allow them to perform these specific types of remote manipulation tasks more efficiently while exposed to perturbed visual feedback. A secondary objective of this evaluation was to establish a set of preliminary guidelines for enhancing remote manipulation performance and reducing the adverse effects. These objectives were accomplished by studying the remote manipulator performance of test subjects exposed to various perturbed camera-viewing conditions while performing a simulated space-based remote manipulation task. Statistical analysis of performance and subjective data revealed that remote manipulation performance was adversely affected by the use of perturbed visual feedback and performance tended to improve with successive trials in most perturbed viewing conditions.
Puniya, Bhanwar Lal; Allen, Laura; Hochfelder, Colleen; Majumder, Mahbubul; Helikar, Tomáš
2016-01-01
Dysregulation in signal transduction pathways can lead to a variety of complex disorders, including cancer. Computational approaches such as network analysis are important tools to understand system dynamics as well as to identify critical components that could be further explored as therapeutic targets. Here, we performed perturbation analysis of a large-scale signal transduction model in extracellular environments that stimulate cell death, growth, motility, and quiescence. Each of the model’s components was perturbed under both loss-of-function and gain-of-function mutations. Using 1,300 simulations under both types of perturbations across various extracellular conditions, we identified the most and least influential components based on the magnitude of their influence on the rest of the system. Based on the premise that the most influential components might serve as better drug targets, we characterized them for biological functions, housekeeping genes, essential genes, and druggable proteins. The most influential components under all environmental conditions were enriched with several biological processes. The inositol pathway was found as most influential under inactivating perturbations, whereas the kinase and small lung cancer pathways were identified as the most influential under activating perturbations. The most influential components were enriched with essential genes and druggable proteins. Moreover, known cancer drug targets were also classified in influential components based on the affected components in the network. Additionally, the systemic perturbation analysis of the model revealed a network motif of most influential components which affect each other. Furthermore, our analysis predicted novel combinations of cancer drug targets with various effects on other most influential components. We found that the combinatorial perturbation consisting of PI3K inactivation and overactivation of IP3R1 can lead to increased activity levels of apoptosis
Effects of linuron on a rooted aquatic macrophyte in sediment-dosed test systems
Buresova, H.; Crum, S.J.H.; Belgers, J.D.M.; Adriaanse, P.I.; Arts, G.H.P.
2013-01-01
Effects of linuron on the sediment-rooted aquatic macrophyte Myriophyllum spicatum L. were studied in sediment-dosed test systems following a proposed guideline with extended test duration. Sediment, pore water, overlying water and macrophyte shoots were sampled weekly for chemical analyses. Linuron
Review on the quality of sediments from the stormwater drainage system in the urban area
Directory of Open Access Journals (Sweden)
Nawrot Nicole
2017-01-01
Full Text Available The main task of the stormwater drainage system (SDS is a safe drainage of rainwater and snowmelt from the urban area to the receiver. The flow of rain water in the drainage pipes is directly related with the formation of sediments in the whole stormwater system. In addition, pollutants from land runoff get adsorbed to the sediments. The sludge is mainly formed in those elements of SDS, wherein the flow conditions allow for sedimentation. This article provides an overview of the literature concerning the characteristics of sediments from SDS, with a particular focus on heavy metals in sediments deposited in the urban catchment area.
International Nuclear Information System (INIS)
White, J.R.
1985-04-01
This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code black for both static and time-dependent perturbation theory and data sensitivity analyses. The DEPTH-CHARGE system is of modular construction and has been implemented within the VENTURE-BURNER computational system at Oak Ridge National Laboratory. The DEPTH module (coupled with VENTURE) solves for the three adjoint functions of Depletion Perturbation Theory and calculates the desired time-dependent derivatives of the response with respect to the nuclide concentrations and nuclear data utilized in the reference model. The CHARGE code is a collection of utility routines for general data manipulation and input preparation and considerably extends the usefulness of the system through the automatic generation of adjoint sources, estimated perturbed responses, and relative data sensitivity coefficients. Combined, the DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analyses of realistic multidimensional reactor models. This current documentation incorporates minor revisions to the original DEPTH-CHARGE documentation (ORNL/CSD-78) to reflect some new capabilities within the individual codes
Directory of Open Access Journals (Sweden)
Chengdong Yang
2015-01-01
Full Text Available This paper addresses the exponential synchronization problem of a class of master-slave distributed parameter systems (DPSs with spatially variable coefficients and spatiotemporally variable nonlinear perturbation, modeled by a couple of semilinear parabolic partial differential equations (PDEs. With a locally Lipschitz constraint, the perturbation is a continuous function of time, space, and system state. Firstly, a sufficient condition for the robust exponential synchronization of the unforced semilinear master-slave PDE systems is investigated for all admissible nonlinear perturbations. Secondly, a robust distributed proportional-spatial derivative (P-sD state feedback controller is desired such that the closed-loop master-slave PDE systems achieve exponential synchronization. Using Lyapunov’s direct method and the technique of integration by parts, the main results of this paper are presented in terms of spatial differential linear matrix inequalities (SDLMIs. Finally, two numerical examples are provided to show the effectiveness of the proposed methods applied to the robust exponential synchronization problem of master-slave PDE systems with nonlinear perturbation.
Perturbative methods applied for sensitive coefficients calculations in thermal-hydraulic systems
International Nuclear Information System (INIS)
Andrade Lima, F.R. de
1993-01-01
The differential formalism and the Generalized Perturbation Theory (GPT) are applied to sensitivity analysis of thermal-hydraulics problems related to pressurized water reactor cores. The equations describing the thermal-hydraulic behavior of these reactors cores, used in COBRA-IV-I code, are conveniently written. The importance function related to the response of interest and the sensitivity coefficient of this response with respect to various selected parameters are obtained by using Differential and Generalized Perturbation Theory. The comparison among the results obtained with the application of these perturbative methods and those obtained directly with the model developed in COBRA-IV-I code shows a very good agreement. (author)
International Nuclear Information System (INIS)
Bartlett, R.; Kirtman, B.; Davidson, E.R.
1978-01-01
After noting some advantages of using perturbation theory some of the various types are related on a chart and described, including many-body nonlinear summations, quartic force-field fit for geometry, fourth-order correlation approximations, and a survey of some recent work. Alternative initial approximations in perturbation theory are also discussed. 25 references
International Nuclear Information System (INIS)
Budgor, A.B.; West, B.J.
1978-01-01
We employ the equivalence between Zwanzig's projection-operator formalism and perturbation theory to demonstrate that the approximate-solution technique of statistical linearization for nonlinear stochastic differential equations corresponds to the lowest-order β truncation in both the consolidated perturbation expansions and in the ''mass operator'' of a renormalized Green's function equation. Other consolidated equations can be obtained by selectively modifying this mass operator. We particularize the results of this paper to the Duffing anharmonic oscillator equation
Large x Behaviour and the Non-Perturbative Structure of Hadronic Systems
Energy Technology Data Exchange (ETDEWEB)
Anthony W. Thomas
2005-02-01
While the traditional interest in structure functions has been the confirmation of the predictions of perturbative QCD, this data also contains a wealth of information on how QCD works in the infrared, or confinement, region. As the challenge of the strong force now turns to the study of QCD in the non-perturbative region, such information is extremely valuable.We outline some of the key issues for both nucleon and nuclear structure functions.
Montefusco, David J; Chen, Lujia; Matmati, Nabil; Lu, Songjian; Newcomb, Benjamin; Cooper, Gregory F; Hannun, Yusuf A; Lu, Xinghua
2013-10-29
Ceramide, the central molecule of sphingolipid metabolism, is an important bioactive molecule that participates in various cellular regulatory events and that has been implicated in disease. Deciphering ceramide signaling is challenging because multiple ceramide species exist, and many of them may have distinct functions. We applied systems biology and molecular approaches to perturb ceramide metabolism in the yeast Saccharomyces cerevisiae and inferred causal relationships between ceramide species and their potential targets by combining lipidomic, genomic, and transcriptomic analyses. We found that during heat stress, distinct metabolic mechanisms controlled the abundance of different groups of ceramide species and provided experimental support for the importance of the dihydroceramidase Ydc1 in mediating the decrease in dihydroceramides during heat stress. Additionally, distinct groups of ceramide species, with different N-acyl chains and hydroxylations, regulated different sets of functionally related genes, indicating that the structural complexity of these lipids produces functional diversity. The transcriptional modules that we identified provide a resource to begin to dissect the specific functions of ceramides.
Directory of Open Access Journals (Sweden)
Xinmin Tang
2016-01-01
Full Text Available Strategic 4D trajectory conflict-free planning is recognized as one of the core technologies of next-generation air traffic control and automation systems. To resolve potential conflicts during strategic 4D conflict-free trajectory planning, a protection-zone conflict-control model based on air traffic control separation constraints was proposed, in which relationships between expected arrival time and adjusted arrival time at conflicting waypoints for aircraft queues were built and transformed into dynamic linear equations under the definition of max-plus algebra. A method for strategic deconfliction of 4D trajectory was then proposed using two strategies: arrival time adjustment and departure time adjustment. In addition, departure time and flight duration perturbations were introduced to analyze the sensitivity of the planned strategic conflict-free 4D trajectories, and a robustness index for the conflict-free 4D trajectories was calculated. Finally, the proposed method was tested for the Shanghai air traffic control terminal area. The outcomes demonstrated that the planned strategic conflict-free 4D trajectories could avoid potential conflicts, and the slack time could be used to indicate their robustness. Complexity analysis demonstrated that deconfliction using max-plus algebra is more suitable for deconfliction of 4D trajectory with random sampling period in fix air route.
Gran, Karen; Belmont, Patrick; Finnegan, Noah
2013-04-01
than modern near-channel erosion rates. Notably, depositional records from a naturally-dammed lake downstream on the upper Mississippi River show a more dramatic 10-fold increase in deposition rates from pre-agricultural times to the present. Sediment fingerprinting shows that pre-agriculture sediment loads were dominated by near-channel sediment sources. As deposition rates rose in the late 1800s and early 1900s, the sources shifted increasingly to agricultural soil erosion. In the past few decades, deposition rates have remained high, but sediment fingerprinting indicates yet another significant shift back to near-channel sources. On-going changes in basin hydrology, from both installation of agricultural drainage systems and on-going climate change have put more water in the rivers, increasing rates of near-channel bank and bluff erosion. This most recent shift in sediment sources has significant implications for turbidity management in the Minnesota River basin.
Characterization of the sediments overlying the Floridan aquifer system in Alachua County, Florida
Green, Richard; Duncan, Joel; Seal, Thomas; Weinberg, J. Michael; Rupert, Frank
1989-01-01
The primary purpose of this project is to attempt to improve the existing hydrogeologic information through lithologic and hydrogeologic characterizations of the sediments overlying the Floridan aquifer system in Alachua County. These sediments locally comprise both the intermediate aquifer system and associated confining beds and the surficial aquifer system. (PDF has 119 pages.)
International Nuclear Information System (INIS)
Hack, Thomas-Paul
2014-01-01
We quantize the linearized Einstein–Klein–Gordon system on arbitrary on-shell backgrounds in a manifestly covariant and gauge-invariant manner. For the special case of perturbations in inflation, i.e. on-shell backgrounds of Friedmann–Lemaître–Robertson–Walker type, we compare our general quantization construction with the standard approach to the quantum theory of perturbations in inflation. We find that not all local quantum observables of the linearized Einstein–Klein–Gordon system can be split into local observables of scalar and tensor type as in the standard approach. However, we argue that this subclass of observables is sufficient for measuring perturbations that vanish at spatial infinity, which is in line with standard assumptions. Finally, we comment on a recent observation that, upon standard quantization, the quantum Bardeen potentials display a non-local behaviour and argue that a similar phenomenon occurs in any local quantum field theory. It is the hope of the author that the present work may constitute a bridge between the generally applicable and thus powerful framework of algebraic quantum field theory in curved spacetimes and the standard treatment of perturbations in inflation. (paper)
Review on the quality of sediments from the stormwater drainage system in the urban area
Nawrot Nicole; Wojciechowska Ewa
2017-01-01
The main task of the stormwater drainage system (SDS) is a safe drainage of rainwater and snowmelt from the urban area to the receiver. The flow of rain water in the drainage pipes is directly related with the formation of sediments in the whole stormwater system. In addition, pollutants from land runoff get adsorbed to the sediments. The sludge is mainly formed in those elements of SDS, wherein the flow conditions allow for sedimentation. This article provides an overview of the literature c...
Soury, Hamza
2016-06-29
The Gaussian distribution is typically used to model the additive noise affecting communication systems. However, in many cases the noise cannot be modeled by a Gaussian distribution. In this thesis, we investigate the performance of different communication systems perturbed by non-Gaussian noise. Three families of noise are considered in this work, namely the generalized Gaussian noise, the Laplace noise/interference, and the impulsive noise that is modeled by an α-stable distribution. More specifically, in the first part of this thesis, the impact of an additive generalized Gaussian noise is studied by computing the average symbol error rate (SER) of one dimensional and two dimensional constellations in fading environment. We begin by the simple case of two symbols, i.e. binary phase shift keying (BPSK) constellation. From the results of this constellation, we extended the work to the average SER of an M pulse amplitude modulation (PAM). The first 2 − D constellation is the M quadrature amplitude modulation (QAM) (studied for two geometric shapes, namely square and rectangular), which is the combination of two orthogonal PAM signals (in-phase and quadrature phase PAM). In the second part, the system performance of a circular constellation, namely M phase shift keying (MPSK) is studied in conjunction with a Laplace noise with independent noise components. A closed form and an asymptotic expansion of the SER are derived for two detectors, maximum likelihood and minimum distance detectors. Next, we look at the intra cell interference of a full duplex cellular network which is shown to follow a Laplacian distribution with dependent, but uncorrelated, complex components. The densities of that interference are expressed in a closed form in order to obtain the SER of several communication systems (BPSK, PAM, QAM, and MPSK). Finally, we study the statistics of the α-stable distribution. Those statistics are expressed in closed form in terms of the Fox H function and
Linear perturbation renormalization group method for Ising-like spin systems
Directory of Open Access Journals (Sweden)
J. Sznajd
2013-03-01
Full Text Available The linear perturbation group transformation (LPRG is used to study the thermodynamics of the axial next-nearest-neighbor Ising model with four spin interactions (extended ANNNI in a field. The LPRG for weakly interacting Ising chains is presented. The method is used to study finite field para-ferrimagnetic phase transitions observed in layered uranium compounds, UAs1-xSex, UPd2Si2 or UNi2Si2. The above-mentioned systems are made of ferromagnetic layers and the spins from the nearest-neighbor and next-nearest-neighbor layers are coupled by the antiferromagnetic interactions J121-xSex the para-ferri phase transition is of the first order as expected from the symmetry reason, in UT2Si2 (T=Pd, Ni this transition seems to be a continuous one, at least in the vicinity of the multicritical point. Within the MFA, the critical character of the finite field para-ferrimagnetic transition at least at one isolated point can be described by the ANNNI model supplemented by an additional, e.g., four-spin interaction. However, in LPRG approximation for the ratio κ = J2/J1 around 0.5 there is a critical value of the field for which an isolated critical point also exists in the original ANNNI model. The positive four-spin interaction shifts the critical point towards higher fields and changes the shape of the specific heat curve. In the latter case for the fields small enough, the specific heat exhibits two-peak structure in the paramagnetic phase.
The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China
Ma, Hongbo; Nittrouer, Jeffrey A.; Naito, Kensuke; Fu, Xudong; Zhang, Yuanfeng; Moodie, Andrew J.; Wang, Yuanjian; Wu, Baosheng; Parker, Gary
2017-01-01
Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams. PMID:28508078
The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China.
Ma, Hongbo; Nittrouer, Jeffrey A; Naito, Kensuke; Fu, Xudong; Zhang, Yuanfeng; Moodie, Andrew J; Wang, Yuanjian; Wu, Baosheng; Parker, Gary
2017-05-01
Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams.
Sampling marine sediments for radionuclide monitoring
International Nuclear Information System (INIS)
Papucci, C.
1997-01-01
A description of the most common devices used for sampling marine sediments are reported. The systems are compared to evidence their intrinsic usefulness, for collecting samples in different environmental conditions or with different scientific objectives. Perturbations and artifacts introduced during the various steps of the sampling procedure are also reviewed, and suggestions are proposed for obtaining and preserving, as much as possible, the representativeness of the sediment samples. (author)
On the Perturb-and-Observe and Incremental Conductance MPPT methods for PV systems
DEFF Research Database (Denmark)
Sera, Dezso; Mathe, Laszlo; Kerekes, Tamas
2013-01-01
This paper presents a detailed analysis of the two most well-known hill-climbing MPPT algorithms, the Perturb-and-Observe (P&O) and Incremental Conductance (INC). The purpose of the analysis is to clarify some common misconceptions in the literature regarding these two trackers, therefore helping...
Singular Perturbations and Time Scales in Modeling and Control of Dynamic Systems,
1980-11-01
rTrp) (43) results in the initial value singularly perturbed matrix differential equations * providing there exist fta ’) and rT(p) uniquely...ReA(Af)ɘ then A1 is D-stable. Let us conditions may be more difficult. Our problem is assume that the network has n, inductors and nc to fmd
Behaviour of the Sedimentation in a System of Microparticles
Directory of Open Access Journals (Sweden)
Salinas-Salas G.
2012-04-01
Full Text Available This paper presents the experimental determination of the behaviour of the sedimentation velocity of systems of micro particles based on the results achieved, evaluating whether there is any difference between the value of the exponent of hindrance function, determined by Richardson and Zaki (1954, in the case of noncolloidal micro particles in order of size between 1,500 nm to 200 nm, as well as describing the behaviour of the already mentioned exponent. At the same time, exposed the experimental work developed under the standard DIN 66111 (1989, using an analytical centrifuge, as well as the analysis of data extracted from it. The data showed that there is a difference between the value proposed by Richardson and Zaki in 1954, in relation to those experimentally determined. This allows us to infer that for micro-systems smaller than 1,000 nm, there is a new value of the exponent of the hindrance function, approximately of the order of 11.5. Additionally, it was determined that there is a relation between the already mentioned exponent and the average size of micro particles that comprise the system of particles settled.
Numerical Modelling of Sediment Transport in Combined Sewer Systems
DEFF Research Database (Denmark)
Schlütter, Flemming
A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed.......A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed....
Watershed erosion modeling using the probability of sediment connectivity in a gently rolling system
Mahoney, David Tyler; Fox, James Forrest; Al Aamery, Nabil
2018-06-01
Sediment connectivity has been shown in recent years to explain how the watershed configuration controls sediment transport. However, we find no studies develop a watershed erosion modeling framework based on sediment connectivity, and few, if any, studies have quantified sediment connectivity for gently rolling systems. We develop a new predictive sediment connectivity model that relies on the intersecting probabilities for sediment supply, detachment, transport, and buffers to sediment transport, which is integrated in a watershed erosion model framework. The model predicts sediment flux temporally and spatially across a watershed using field reconnaissance results, a high-resolution digital elevation models, a hydrologic model, and shear-based erosion formulae. Model results validate the capability of the model to predict erosion pathways causing sediment connectivity. More notably, disconnectivity dominates the gently rolling watershed across all morphologic levels of the uplands, including, microtopography from low energy undulating surfaces across the landscape, swales and gullies only active in the highest events, karst sinkholes that disconnect drainage areas, and floodplains that de-couple the hillslopes from the stream corridor. Results show that sediment connectivity is predicted for about 2% or more the watershed's area 37 days of the year, with the remaining days showing very little or no connectivity. Only 12.8 ± 0.7% of the gently rolling watershed shows sediment connectivity on the wettest day of the study year. Results also highlight the importance of urban/suburban sediment pathways in gently rolling watersheds, and dynamic and longitudinal distributions of sediment connectivity might be further investigated in future work. We suggest the method herein provides the modeler with an added tool to account for sediment transport criteria and has the potential to reduce computational costs in watershed erosion modeling.
Energy Technology Data Exchange (ETDEWEB)
Bobodzhanov, A A; Safonov, V F [National Research University " Moscow Power Engineering Institute" , Moscow (Russian Federation)
2013-07-31
The paper deals with extending the Lomov regularization method to classes of singularly perturbed Fredholm-type integro-differential systems, which have not so far been studied. In these the limiting operator is discretely noninvertible. Such systems are commonly known as problems with unstable spectrum. Separating out the essential singularities in the solutions to these problems presents great difficulties. The principal one is to give an adequate description of the singularities induced by 'instability points' of the spectrum. A methodology for separating singularities by using normal forms is developed. It is applied to the above type of systems and is substantiated in these systems. Bibliography: 10 titles.
Robinson, Georgina; Caldwell, Gary S.; Wade, Matthew J.; Free, Andrew; Jones, Clifford L. W.; Stead, Selina M.
2016-12-01
Deposit-feeding invertebrates are proposed bioremediators in microbial-driven sediment-based aquaculture effluent treatment systems. We elucidate the role of the sediment reduction-oxidation (redox) regime in structuring benthic bacterial communities, having direct implications for bioremediation potential and deposit-feeder nutrition. The sea cucumber Holothuria scabra was cultured on sediments under contrasting redox regimes; fully oxygenated (oxic) and redox stratified (oxic-anoxic). Taxonomically, metabolically and functionally distinct bacterial communities developed between the redox treatments with the oxic treatment supporting the greater diversity; redox regime and dissolved oxygen levels were the main environmental drivers. Oxic sediments were colonised by nitrifying bacteria with the potential to remediate nitrogenous wastes. Percolation of oxygenated water prevented the proliferation of anaerobic sulphate-reducing bacteria, which were prevalent in the oxic-anoxic sediments. At the predictive functional level, bacteria within the oxic treatment were enriched with genes associated with xenobiotics metabolism. Oxic sediments showed the greater bioremediation potential; however, the oxic-anoxic sediments supported a greater sea cucumber biomass. Overall, the results indicate that bacterial communities present in fully oxic sediments may enhance the metabolic capacity and bioremediation potential of deposit-feeder microbial systems. This study highlights the benefits of incorporating deposit-feeding invertebrates into effluent treatment systems, particularly when the sediment is oxygenated.
International Nuclear Information System (INIS)
Sagar, B.; Connelly, M.P.; Long, P.E.
1988-05-01
The Hanford site located in southeastern Washington state was under consideration for the location of a high-level nuclear waste repository. As a part of site investigation, a borehole of depth > 3000 ft was drilled using reverse circulation drilling technique with water as the drilling fluid. After completion of drilling, seven piezometers were to be installed in the borehole with their lower ends at different depths to measure equilibrated hydraulic heads and aquifer response during future pumping tests. The hydrologic perturbations caused during the drilling, clean up, and piezometer installation process were of primary concern. A numerical model was used to predict these perturbations and determine efficiency of borehole cleanup. It was found that the boundary condition at the borehole was the most difficult to model. 9 refs., 5 figs
Balance perturbation system to improve balance compensatory responses during walking in old persons
Shapiro, Amir; Melzer, Itshak
2010-01-01
Abstract Ageing commonly disrupts the balance control and compensatory postural responses that contribute to maintaining balance and preventing falls during perturbation of posture. This can lead to increased risk of falling in old adults (65 years old and over). Therefore, improving compensatory postural responses during walking is one of the goals in fall prevention programs. Training is often used to achieve this goal. Most fall prevention programs are usually directed towards improving vo...
Directory of Open Access Journals (Sweden)
J.-H. Park
2018-05-01
Full Text Available Human activities are drastically altering water and material flows in river systems across Asia. These anthropogenic perturbations have rarely been linked to the carbon (C fluxes of Asian rivers that may account for up to 40–50 % of the global fluxes. This review aims to provide a conceptual framework for assessing the human impacts on Asian river C fluxes, along with an update on anthropogenic alterations of riverine C fluxes. Drawing on case studies conducted in three selected rivers (the Ganges, Mekong, and Yellow River and other major Asian rivers, the review focuses on the impacts of river impoundment and pollution on CO2 outgassing from the rivers draining South, Southeast, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia and Oceania. A critical examination of major conceptual models of riverine processes against observed trends suggests that to better understand altered metabolisms and C fluxes in anthropogenic land-water-scapes, or riverine landscapes modified by human activities, the traditional view of the river continuum should be complemented with concepts addressing spatial and temporal discontinuities created by human activities, such as river impoundment and pollution. Recent booms in dam construction on many large Asian rivers pose a host of environmental problems, including increased retention of sediment and associated C. A small number of studies that measured greenhouse gas (GHG emissions in dammed Asian rivers have reported contrasting impoundment effects: decreased GHG emissions from eutrophic reservoirs with enhanced primary production vs. increased emissions from the flooded vegetation and soils in the early years following dam construction or from the impounded reaches and downstream estuaries during the monsoon period. These contrasting results suggest that the rates of metabolic processes in the impounded and downstream reaches can vary greatly longitudinally
Park, Ji-Hyung; Nayna, Omme K.; Begum, Most S.; Chea, Eliyan; Hartmann, Jens; Keil, Richard G.; Kumar, Sanjeev; Lu, Xixi; Ran, Lishan; Richey, Jeffrey E.; Sarma, Vedula V. S. S.; Tareq, Shafi M.; Xuan, Do Thi; Yu, Ruihong
2018-05-01
Human activities are drastically altering water and material flows in river systems across Asia. These anthropogenic perturbations have rarely been linked to the carbon (C) fluxes of Asian rivers that may account for up to 40-50 % of the global fluxes. This review aims to provide a conceptual framework for assessing the human impacts on Asian river C fluxes, along with an update on anthropogenic alterations of riverine C fluxes. Drawing on case studies conducted in three selected rivers (the Ganges, Mekong, and Yellow River) and other major Asian rivers, the review focuses on the impacts of river impoundment and pollution on CO2 outgassing from the rivers draining South, Southeast, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia and Oceania. A critical examination of major conceptual models of riverine processes against observed trends suggests that to better understand altered metabolisms and C fluxes in anthropogenic land-water-scapes, or riverine landscapes modified by human activities, the traditional view of the river continuum should be complemented with concepts addressing spatial and temporal discontinuities created by human activities, such as river impoundment and pollution. Recent booms in dam construction on many large Asian rivers pose a host of environmental problems, including increased retention of sediment and associated C. A small number of studies that measured greenhouse gas (GHG) emissions in dammed Asian rivers have reported contrasting impoundment effects: decreased GHG emissions from eutrophic reservoirs with enhanced primary production vs. increased emissions from the flooded vegetation and soils in the early years following dam construction or from the impounded reaches and downstream estuaries during the monsoon period. These contrasting results suggest that the rates of metabolic processes in the impounded and downstream reaches can vary greatly longitudinally over time as a
International Nuclear Information System (INIS)
Wilson, E. A.; Manson, N. B.; Wei, C.
2005-01-01
The effect a perturbing field has on an electromagnetically induced transparency within a three-level Λ system is presented. The perturbing field is applied resonant between one of the lower levels of the Λ system and a fourth level. The electromagnetically induced transparency feature is split and this is measured experimentally for both single and bichromatic driving fields. In the single-driving-field case a density matrix treatment is shown to be in reasonable agreement with experiment and in both single and bichromatic cases the structure in the spectrum can be explained using a dressed-state analysis
C. Colloca TS/FM
2004-01-01
TS/FM group informs you that, for the progress of the works at the Prévessin site entrance, some perturbation of the traffic may occur during the week between the 14th and 18th of June for a short duration. Access will be assured at any time. For more information, please contact 160239. C. Colloca TS/FM
International Nuclear Information System (INIS)
Gómez-Valent, Adrià; Karimkhani, Elahe; Solà, Joan
2015-01-01
We determine the Hubble expansion and the general cosmic perturbation equations for a general system consisting of self-conserved matter, ρ m , and self-conserved dark energy (DE), ρ D . While at the background level the two components are non-interacting, they do interact at the perturbations level. We show that the coupled system of matter and DE perturbations can be transformed into a single, third order, matter perturbation equation, which reduces to the (derivative of the) standard one in the case that the DE is just a cosmological constant. As a nontrivial application we analyze a class of dynamical models whose DE density ρ D (H) consists of a constant term, C 0 , and a series of powers of the Hubble rate. These models were previously analyzed from the point of view of dynamical vacuum models, but here we treat them as self-conserved DE models with a dynamical equation of state. We fit them to the wealth of expansion history and linear structure formation data and compare their fit quality with that of the concordance ΛCDM model. Those with C 0 =0 include the so-called ''entropic-force'' and ''QCD-ghost'' DE models, as well as the pure linear model ρ D ∼H, all of which appear strongly disfavored. The models with C 0 ≠0 , in contrast, emerge as promising dynamical DE candidates whose phenomenological performance is highly competitive with the rigid Λ-term inherent to the ΛCDM
Energy Technology Data Exchange (ETDEWEB)
Gómez-Valent, Adrià; Karimkhani, Elahe; Solà, Joan, E-mail: adriagova@ecm.ub.edu, E-mail: e.karimkhani91@basu.ac.ir, E-mail: sola@ecm.ub.edu [High Energy Physics Group, Dept. ECM, and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Catalonia (Spain)
2015-12-01
We determine the Hubble expansion and the general cosmic perturbation equations for a general system consisting of self-conserved matter, ρ{sub m}, and self-conserved dark energy (DE), ρ{sub D}. While at the background level the two components are non-interacting, they do interact at the perturbations level. We show that the coupled system of matter and DE perturbations can be transformed into a single, third order, matter perturbation equation, which reduces to the (derivative of the) standard one in the case that the DE is just a cosmological constant. As a nontrivial application we analyze a class of dynamical models whose DE density ρ{sub D}(H) consists of a constant term, C{sub 0}, and a series of powers of the Hubble rate. These models were previously analyzed from the point of view of dynamical vacuum models, but here we treat them as self-conserved DE models with a dynamical equation of state. We fit them to the wealth of expansion history and linear structure formation data and compare their fit quality with that of the concordance ΛCDM model. Those with C{sub 0}=0 include the so-called ''entropic-force'' and ''QCD-ghost'' DE models, as well as the pure linear model ρ{sub D}∼H, all of which appear strongly disfavored. The models with C{sub 0}≠0 , in contrast, emerge as promising dynamical DE candidates whose phenomenological performance is highly competitive with the rigid Λ-term inherent to the ΛCDM.
Enhanced electroforced sedimentation of various solid- liquid systems
African Journals Online (AJOL)
GREGORY
2011-12-16
Dec 16, 2011 ... Application of electric field, to enhance the separation, is one of the techniques .... the material; Ce the modified consolidation coefficient and θ time. ... sedimentation of thick clay suspensions in consolidation region. Chemical ...
Understanding the sediment routing system along the Gulf of ...
Indian Academy of Sciences (India)
ment transport (Nair et al. ... Map showing geological/geomorphic setup along the GoK coast along with the sampling sites and bathymetry .... fraction for 50 samples following Stoke's law for .... to its characteristic sediment transport mecha-.
Dynamic sorption data of selected radionuclides in sediment-water-systems from the Gorleben region
International Nuclear Information System (INIS)
Klotz, D.
1993-01-01
In 48 sediment-water-systems from the Gorleben region about 300 continuous-flow-column experiments were performed with 10 radionuclides. To simulate conditions as close as possible to natural ones (as regards the bedding of sediments, speed of filtration, environment, and microbiology - if necessary) for the sediment-groundwater-systems, the ranges of retardation factors for fresh, mixed and salt water systems were specified. For the investigated sand-water-systems, a comparison of the results obtained from continuous-flow-column and batch experiments for 85Sr and 134Cs was made. (orig.) [de
Sediment Buffering and Transport in the Holocene Indus River System
Clift, P. D.; Giosan, L.; Henstock, T.; Tabrez, A. R.; Vanlaningham, S.; Alizai, A. H.; Limmer, D. R.; Danish, M.
2009-12-01
Submarine fans are the largest sediment bodies on Earth and potentially hold records of erosion that could be used to assess the response of continents to changing climate in terms of both physical erosion and chemical weathering. However, buffering between the mountain sources and the abyssal plain may make detailed correlation of climate and erosion records difficult. We investigated the nature of sediment transport in the Indus drainage in SW Asia. Through trenching in the flood plain, drilling in the delta and new seismic and coring data from the shelf and canyon we can now constrain sediment transport from source to sink since the Last Glacial Maximum (LGM). The Indus was affected by intensification of the summer monsoon during the Early Holocene and subsequent weakening since ca. 8 ka. Sediment delivery to the delta was very rapid at 12-8 ka, but slowed along with the weakening monsoon. At the LGM erosion in the Karakoram dominated the supply of sandy material, while the proportion of Lesser Himalayan flux increased with strengthening summer rainfall after 12 ka. Total load also increased at that time. Since 5 ka incision of rivers into the upper parts of the flood plain has reworked Lower Holocene sediments, although the total flux slowed. Coring in the Indus canyon shows that sediment has not reached the lower canyon since ca. 7 ka, but that sedimentation has recently been very rapid in the head of the canyon. We conclude that variations in sealevel and terrestrial climate have introduced a lag of at least 7 k.y. into the deep sea fan record and that monsoon strength is a primary control on whether sediment is stored or released in the flood plain.
Lee, S E; Kang, S H
2014-01-01
Spatially distributed sediment delivery (SEDD) models are of great interest in estimating the expected effect of changes on soil erosion and sediment yield. However, they can only be applied if the model can be calibrated using observed data. This paper presents a geographic information system (GIS)-based method to calculate the sediment discharge from basins to coastal areas. For this, an SEDD model, with a sediment rating curve method based on observed data, is proposed and validated. The model proposed here has been developed using the combined application of the revised universal soil loss equation (RUSLE) and a spatially distributed sediment delivery ratio, within Model Builder of ArcGIS's software. The model focuses on spatial variability and is useful for estimating the spatial patterns of soil loss and sediment discharge. The model consists of two modules, a soil erosion prediction component and a sediment delivery model. The integrated approach allows for relatively practical and cost-effective estimation of spatially distributed soil erosion and sediment delivery, for gauged or ungauged basins. This paper provides the first attempt at estimating sediment delivery ratio based on observed data in the monsoon region of Korea.
Spatio-temporal effects in a perturbed Sine-Gordan system: A long Josephson junction
International Nuclear Information System (INIS)
Nana, L.; Crepin Kofane, T.
2003-12-01
A collective coordinate approach is applied to study chaotic responses induced by an applied driven signal on the long Josephson junction influenced by a constant dc-driven field. We derive a nonlinear equation for a collective variable of the breather and the Melnikov method is then used to demonstrate the existence of irregular behavior in breather-fluxon-antifluxon pair transitions. Additionally, numerical simulations show that the theoretical predictions are well reproduced. Results obtained using these perturbative analysis are in good agreement with numerical simulations of the dynamics of the junction. (author)
Application of a Sediment Information System to the Three Gorges Project on Yangtze River, China
Cao, Shuyou; Liu, Xingnian; Yang, Kejun; Li, Changzhi
Based on survey and analysis of a huge number of observed entrance sediment transport data and the research results of physical and numerical modeling of Three Gorges Reservoir on the Yangtze River, a sediment information system was designed. The basis of this system includes spatial data and properties of geographic elements, and various documents involved to the Three Gorges Project (TGP). Database and knowledge base are constructed as the information bank. The running environment is constructed by the general control program to realize requirements about various sediment information. The system chooses the window software as the system software. The techniques of graphical user interfaces and groupware geographic information system are applied in this system. In this phase, the emphases of the system are development of document system, map system, and presentation system. Cross-section system of the TGP was also attached. For further improvement of the system, a prepared interface of decision supporting subsystem is finished.
International Nuclear Information System (INIS)
Kutzelnigg, Werner; Mukherjee, Debashis
2004-01-01
The k-particle irreducible Brillouin conditions IBC k and the k-particle irreducible contracted Schroedinger equations ICSE k for a closed-shell state are analyzed in terms of a Moeller-Plesset-type perturbation expansion. The zeroth order is Hartree-Fock. From the IBC 2 (1) , i.e., from the two-particle IBC to first order in the perturbation parameter μ, one gets the leading correction λ 2 (1) to the two-particle cumulant λ 2 correctly. However, in order to construct the second-order energy E 2 , one also needs the second-order diagonal correction γ D (2) to the one-particle density matrix γ. This can be obtained: (i) from the idempotency of the n-particle density matrix, i.e., essentially from the requirement of n-representability; (ii) from the ICSE 1 (2) ; or (iii) by means of perturbation theory via a unitary transformation in Fock space. Method (ii) is very unsatisfactory, because one must first solve the ICSE 3 (2) to get λ 3 (2) , which is needed in the ICSE 2 (2) to get λ 2 (2) , which, in turn, is needed in the ICSE 1 (2) to get γ (2) . Generally the (k+1)-particle approximation is needed to obtain E k correctly. One gains something, if one replaces the standard hierarchy, in which one solves the ICSE k , ignoring λ k+1 and λ k+2 , by a renormalized hierarchy, in which only λ k+2 is ignored, and λ k+1 is expressed in terms of the λ p of lower particle rank via the partial trace relation for λ k+2 . Then the k-particle approximation is needed to obtain E k correctly. This is still poorer than coupled-cluster theory, where the k-particle approximation yields E k+1 . We also study the possibility to use some simple necessary n-representability conditions, based on the non-negativity of γ (2) and two related matrices, in order to get estimates for γ D (2) in terms of λ 2 (1) . In general these estimates are rather weak, but they can become close to the best possible bounds in special situations characterized by a very sparse structure of λ 2
Lv, Zheng-Hui; Wang, Jing; Yang, Guang-Feng; Feng, Li-Juan; Mu, Jun; Zhu, Liang; Xu, Xiang-Yang
2018-02-01
In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH 4 + -N removal rate of 0.35 mg L -1 h -1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH 4 + -N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.
Torres, M. A.; Kemeny, P. C.; Fischer, W. W.; Lamb, M. P.
2017-12-01
Vast amounts of sediments are stored transiently in fluvial deposits as they move in rivers from source to sink. The timescale(s) of transient storage have the potential to set the cadence for biogeochemical reactions to occur in river sediments. However, the extent to which storage modulates the chemical composition of river sediments remains unclear. In case of the organic carbon (OC) cycle, transient sediment storage may leave an imprint in the radiocarbon (14C) content of riverine particulate OC (POC), offering a potential tool to trace the coupling of sediment storage and biogeochemical cycling in river systems. We investigated the modern and ancient budgets of sediments and POC in the Efi Haukadalsá River catchment in West Iceland to provide new empirical constraints on the role of sediment storage in the terrestrial OC cycle. This field site is attractive because the basaltic bedrock is free of rock-derived (i.e. "petrogenic") POC such that bulk 14C measurements can be interpreted more directly as constraints on catchment OC storage timescales. Additionally, Lake Haukadalsvatn at the outlet of the river catchment has captured sediment for nearly 13 ka, which offers a complementary record of the evolution of climate-sediment-OC linkages since deglaciation. New 14C measurements show that bulk POC in fine grained fluvial deposits within the Haukadalsá catchment is remarkably old (model ages between 1 and 10 ka). This evidence for "aged" POC in floodplain storage is consistent with previous measurements from Lake Haukadalsvatn, which show that POC is aged in the river system by thousands of years prior to deposition in the lake. Additionally, our estimate of the mean transit time of sediments through the river system matches the millennial-scale reservoir age of riverine POC derived from 14C, which implies a tight coupling between sediment storage and the OC cycle. We interpret the long-term increase in the 14C reservoir age of riverine POC over the last 10 ka
Parkes, R John; Sellek, Gerard; Webster, Gordon; Martin, Derek; Anders, Erik; Weightman, Andrew J; Sass, Henrik
2009-01-01
Deep subseafloor sediments may contain depressurization-sensitive, anaerobic, piezophilic prokaryotes. To test this we developed the DeepIsoBUG system, which when coupled with the HYACINTH pressure-retaining drilling and core storage system and the PRESS core cutting and processing system, enables deep sediments to be handled without depressurization (up to 25 MPa) and anaerobic prokaryotic enrichments and isolation to be conducted up to 100 MPa. Here, we describe the system and its first use...
Study of the sludge sedimentation dynamics by means of an optical system
International Nuclear Information System (INIS)
Giacoman Vallejos, G.; Ponce Caballero, C.; Quintal Franco, C.; Perez Cortes, M.
2009-01-01
Nowadays, the problem of water contamination causes the optimization of the processes carried out in wastewater treatment plants to improve the pollutants removal efficiency. In this work, an optical system was implemented to measure the sedimentation speed of sludge in wastewaters, this parameter is very important for designing mechanisms that deposit the sludge in the sediment lower levels of treatment plants. The results obtained with the optical system proposed agree with those obtained using graduate test tube techniques, and provide higher sedimentation speed accuracy. (Author)
A perturbative clustering hyper-heuristic framework for the Danish railway system
DEFF Research Database (Denmark)
M. Pour, Shahrzad; Rasmussen, Kourosh Marjani; Burke, Edmund K.
, we propose a perturbative clustering hyper-heuristic framework. The framework improves an initial solution by reassigning outliers (those tasks that are far away) to a better cluster choice at each iteration while taking balanced crews workloads into account. The framework introduces five lowlevel...... heuristics and employs an adaptive choice function as a robust learning mechanism. The results of adaptive clustering hyper-heuristic are compared with two exact and heuristic assignment algorithms from the literature and with the random hyper-heuristic framework on 12 datasets. In comparison with the exact...... formulation, the proposed framework could obtain promising results and solved the data instances up to 5000 number of tasks. In comparison with heuristic assignment and the random hyper-heuristic, the framework yielded approximately 11%, 27% and 10%,13% mprovement on total distance and the maximum distance...
International Nuclear Information System (INIS)
Lecompte, J.-C.; Buisson, Jacques.
1981-01-01
Neutronics and thermodynamics measuring devices realize the control and nuclear safety of the reactor and the core. They cause the emergency stop of the reactor if the informations given by the sensors are out of the normal operation tolerances. Defining and assuring a protection level sufficiently high against electromagnetic disturbances is essential for avoiding those measuring devices of giving erroneous indications in the environment where they are located. To obtain this result, one procceds according to the following three steps: a) In situ measurements of the ambient level of disturbances (oscilloscope analysis, statistical measurements). b) Measurement in laboratory of the immunity against the disturbances caused by every constituent of the device (electronic cables, connectors) and then the complete device. c) In situ simulation on the devices of the perturbations caused by the measured ambient level [fr
Organic sedimentation in modern lacustrine systems: A case study from Lake Malawi, East Africa
Ellis, Geoffrey S.; Barry J. Katz,; Christopher A. Scholz,; Peter K. Swart,
2015-01-01
This study examines the relationship between depositional environment and sedimentary organic geochemistry in Lake Malawi, East Africa, and evaluates the relative significance of the various processes that control sedimentary organic matter (OM) in lacustrine systems. Total organic carbon (TOC) concentrations in recent sediments from Lake Malawi range from 0.01 to 8.80 wt% and average 2.83 wt% for surface sediments and 2.35 wt% for shallow core sediments. Hydrogen index (HI) values as determined by Rock-Eval pyrolysis range from 0 to 756 mg HC g−1 TOC and average 205 mg HC g−1 TOC for surface sediments and 228 mg HC g−1 TOC for shallow core samples. On average, variations in primary productivity throughout the lake may account for ~33% of the TOC content in Lake Malawi sediments (as much as 1 wt% TOC), and have little or no impact on sedimentary HI values. Similarly, ~33% to 66% of the variation in TOC content in Lake Malawi sediments appears to be controlled by anoxic preservation of OM (~1–2 wt% TOC), although some component of the water depth–TOC relationship may be due to physical sediment transport processes. Furthermore, anoxic preservation has a minimal effect on HI values in Lake Malawi sediments. Dilution of OM by inorganic sediment may account for ~16% of variability in TOC content in Lake Malawi sediments (~0.5 wt% TOC). The effect of inputs of terrestrial sediment on the organic character of surface sediments in these lakes is highly variable, and appears to be more closely related to the local depositional environment than the regional flux of terrestrial OM. Total nitrogen and TOC content in surface sediments collected throughout the lake are found to be highly correlated (r2 = 0.95), indicating a well-homogenized source of OM to the lake bottom. The recurring suspension and deposition of terrestrial sediment may account for significant amounts of OM deposited in offshore regions of the lake. This process effectively separates denser
Design of the power system for dynamic resonant magnetic perturbation coils on the J-TEXT tokamak
Energy Technology Data Exchange (ETDEWEB)
Yi, B. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Ding, Y.H., E-mail: yhding@mail.hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, M.; Rao, B.; Nan, J.Y.; Zeng, W.B.; Zheng, M.Y.; Xu, H.Y.; Zhuang, G.; Pan, Y. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)
2013-10-15
Highlights: ► We introduce the dynamic resonant magnetic perturbation coils system on J-TEXT. ► Details of the design of the power supply system have been presented. ► At DC mode, two antiparallel 6-pulse phase thyristor rectifiers were chosen. ► An AC–DC–AC converter including a series resonant inverter was adopted for AC mode. ► Some engineering testing result was given in this paper. -- Abstract: A set of in-vessel saddle coils has been installed on J-TEXT tokamak. They are proposed for further researches on controlling tearing modes and driving plasma rotation by static and dynamic resonant magnetic perturbations (RMPs). The saddle coils will be energized by DC with the amplitude up to 10 kA, or AC with maximum amplitude up to 5 kA within the frequency range of 1–5 kHz. At DC mode two antiparallel 6-pulse phase thyristor rectifiers are chosen to obtain bidirectional current, while at AC mode an AC–DC–AC converter including a series resonant inverter can generate current of various amplitudes and frequencies. The paper presents the design of the power supply system, based on the definition of the power supply requirements and the feasibility of implementation of the topology and control strategy. Some simulation and experimental results are given in the end.
Piper, D Z; Ludington, Steve; Duval, J S; Taylor, H E
2006-06-01
Stream-bed sediment for the size fraction less than 150 microm, examined in 14,000 samples collected mostly from minor tributaries to the major rivers throughout the Mississippi River drainage system, is composed of 5 mineral fractions identified by factor analysis-Al-silicate minerals, quartz, calcite and dolomite, heavy minerals, and an Fe-Mn fraction. The Al-silicate fraction parallels its distribution in the regolith, emphasizing the local sediment source as a primary control to its distribution. Quartz and the heavy-mineral fraction, and associated trace elements, exhibit a complementary distribution to that of the Al-silicate fraction, with a level of enrichment in the bed sediment that is achieved through winnowing and sorting. The carbonate fraction has a distribution suggesting its dissolution during transport. Trace elements partitioned onto the Fe-Mn, possibly amorphous oxyhydride, fraction are introduced to the streams, in part, through human activity. Except for the heavy-mineral fraction, these fractions are identified in suspended sediment from the Mississippi River itself. Although comparison of the tributary bed sediment with the riverine suspended sediment is problematic, the geochemistry of the suspended sediment seems to corroborate the interpretation of the geochemistry of the bed sediment.
Huang, Yu
Solar energy becomes one of the major alternative renewable energy options for its huge abundance and accessibility. Due to the intermittent nature, the high demand of Maximum Power Point Tracking (MPPT) techniques exists when a Photovoltaic (PV) system is used to extract energy from the sunlight. This thesis proposed an advanced Perturbation and Observation (P&O) algorithm aiming for relatively practical circumstances. Firstly, a practical PV system model is studied with determining the series and shunt resistances which are neglected in some research. Moreover, in this proposed algorithm, the duty ratio of a boost DC-DC converter is the object of the perturbation deploying input impedance conversion to achieve working voltage adjustment. Based on the control strategy, the adaptive duty ratio step size P&O algorithm is proposed with major modifications made for sharp insolation change as well as low insolation scenarios. Matlab/Simulink simulation for PV model, boost converter control strategy and various MPPT process is conducted step by step. The proposed adaptive P&O algorithm is validated by the simulation results and detail analysis of sharp insolation changes, low insolation condition and continuous insolation variation.
Lodhi, Ehtisham; Lodhi, Zeeshan; Noman Shafqat, Rana; Chen, Fieda
2017-07-01
Photovoltaic (PV) system usually employed The Maximum power point tracking (MPPT) techniques for increasing its efficiency. The performance of the PV system perhaps boosts by controlling at its apex point of power, in this way maximal power can be given to load. The proficiency of a PV system usually depends upon irradiance, temperature and array architecture. PV array shows a non-linear style for V-I curve and maximal power point on V-P curve also varies with changing environmental conditions. MPPT methods grantees that a PV module is regulated at reference voltage and to produce entire usage of the maximal output power. This paper gives analysis between two widely employed Perturb and Observe (P&O) and Incremental Conductance (INC) MPPT techniques. Their performance is evaluated and compared through theoretical analysis and digital simulation on the basis of response time and efficiency under varying irradiance and temperature condition using Matlab/Simulink.
International Nuclear Information System (INIS)
Liu Xianning; Chen Lansun
2003-01-01
This paper develops the Holling type II Lotka-Volterra predator-prey system, which may inherently oscillate, by introducing periodic constant impulsive immigration of predator. Condition for the system to be extinct is given and permanence condition is established via the method of comparison involving multiple Liapunov functions. Further influences of the impulsive perturbations on the inherent oscillation are studied numerically, which shows that with the increasing of the amount of the immigration, the system experiences process of quasi-periodic oscillating→cycles→periodic doubling cascade→chaos→periodic halfing cascade→cycles, which is characterized by (1) quasi-periodic oscillating, (2) period doubling, (3) period halfing, (4) non-unique dynamics, meaning that several attractors coexist
Wang, Chengwen; Quan, Long; Zhang, Shijie; Meng, Hongjun; Lan, Yuan
2017-03-01
Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with the high stiffness control and mismatched uncertainties input problems, which hinder direct applications of many advanced control approaches in the hydraulic servo fields. In this paper, by introducing the singular value perturbation theory, the original double-dynamics coupling model of the hydraulic servomechanism was reduced to a integral chain system. So that, the popular ADRC (active disturbance rejection control) technology could be directly applied to the reduced system. In addition, the high stiffness control and mismatched uncertainties input problems are avoided. The validity of the simplified model is analyzed and proven theoretically. The standard linear ADRC algorithm is then developed based on the obtained reduced-order model. Extensive comparative co-simulations and experiments are carried out to illustrate the effectiveness of the proposed method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Bioavailability and effect of pirimicarb on Daphnia magna in a laboratory freshwater/sediment system
DEFF Research Database (Denmark)
Kusk, K.O.
1996-01-01
In tests with newborn and one-week-old Daphnia magna, 48-h EC(50) values of 21-24 mu g/L and 16 mu g/L pirimicarb, respectively, were found. Older animals thus were as sensitive to pirimicarb as newborn animals. In an experiment with sediment included in the test system, all mother animals survived...... not reduced significantly during the experiment, due to the small amount of sediment used. Accumulation in the sediment was found independent of the water concentration used. This was also the case with bioaccumulation in Daphnia magna, where a bioaccumulation factor of 31-37 was found on a dry weight basis...
New Designs of Reduced-Order Observer-Based Controllers for Singularly Perturbed Linear Systems
Directory of Open Access Journals (Sweden)
Heonjong Yoo
2017-01-01
Full Text Available The slow and fast reduced-order observers and reduced-order observer-based controllers are designed by using the two-stage feedback design technique for slow and fast subsystems. The new designs produce an arbitrary order of accuracy, while the previously known designs produce the accuracy of O(ϵ only where ϵ is a small singular perturbation parameter. Several cases of reduced-order observer designs are considered depending on the measured state space variables: only all slow variables are measured, only all fast variables are measured, and some combinations of the slow and fast variables are measured. Since the two-stage methods have been used to overcome the numerical ill-conditioning problem for Cases (III–(V, they have similar procedures. The numerical ill-conditioning problem is avoided so that independent feedback controllers can be applied to each subsystem. The design allows complete time-scale separation for both the reduced-order observer and controller through the complete and exact decomposition into slow and fast time scales. This method reduces both offline and online computations.
Green PCB Remediation from Sediment Systems (GPRSS) Project
Falker, John; Thompson, Karen; Zeitlin, Nancy; Quinn, Jacqueline; Parrish, Lewis M.
2014-01-01
An ongoing problem facing the global environment community including NASA centers is the removal and remediation of polychlorinated biphenyls (PCBs). PCBs were commonly used in a variety of materials including paints, caulking, and adhesives due to the advantageous physical and chemical properties that PCBs imparted to these various materials. Unfortunately, these properties have made the treatment of sites contaminated with these chemicals extremely difficult to deal with, due to their inherent chemical stability. The remediation of sediments contaminated with PCBs is especially difficult, primarily due to the risk of releasing the contaminant into the environment during the treatment process. Traditional treatment options involve the use of dredging and incineration of the contaminated soils/sediments, in which the chance of releasing the contaminants is greatly increased. The purpose of this project is to develop cleanup technology capable of remediating contaminated sediments in-situ, with minimum intrusion. This allows for the minimization of any potential contaminant release during the treatment process, providing a safer method for cleanup operations (as opposed to dredging/incineration) and still treating the basic problem of PCB contamination (as opposed to capping).
Feehan, S.; Ruggiero, P.; Hempel, L. A.; Anderson, D. L.; Cohn, N.
2016-12-01
Characterizing Feedbacks Between Environmental Forcing and Sediment Characteristics in Fluvial and Coastal Systems American Geophysical Union, 2016 Fall Meeting: San Francisco, CA Authors: Scott Feehan, Peter Ruggiero, Laura Hempel, and Dylan Anderson Linking transport processes and sediment characteristics within different environments along the source to sink continuum provides critical insight into the dominant feedbacks between grain size distributions and morphological evolution. This research is focused on evaluating differences in sediment size distributions across both fluvial and coastal environments in the U.S. Pacific Northwest. The Cascades' high relief is characterized by diverse flow regimes with high peak/flashy flows and sub-threshold flows occurring in relative proximity and one of the most energetic wave climates in the world. Combining analyses of both fluvial and coastal environments provides a broader understanding of the dominant forces driving differences between each system's grain size distributions, sediment transport processes, and resultant evolution. We consider sediment samples taken during a large-scale flume experiment that simulated floods representative of both high/flashy peak flows analogous to runoff dominated rivers and sub-threshold flows, analogous to spring-fed rivers. High discharge flows resulted in narrower grain size distributions while low flows where less skewed. Relative sediment size showed clear dependence on distance from source and the environments' dominant fluid motion. Grain size distributions and sediment transport rates were also quantified in both wave dominated nearshore and aeolian dominated backshore portions of Long Beach Peninsula, Washington during SEDEX2, the Sandbar-aEolian-Dune EXchange Experiment of summer 2016. The distributions showed spatial patterns in mean grain size, skewness, and kurtosis dependent on the dominant sediment transport process. The feedback between these grain size
Directory of Open Access Journals (Sweden)
Hamid Reza Karimi
2009-01-01
Full Text Available The problem of stability analysis for a class of neutral systems with mixed time-varying neutral, discrete and distributed delays and nonlinear parameter perturbations is addressed. By introducing a novel Lyapunov-Krasovskii functional and combining the descriptor model transformation, the Leibniz-Newton formula, some free-weighting matrices, and a suitable change of variables, new sufficient conditions are established for the stability of the considered system, which are neutral-delay-dependent, discrete-delay-range-dependent, and distributed-delay-dependent. The conditions are presented in terms of linear matrix inequalities (LMIs and can be efficiently solved using convex programming techniques. Two numerical examples are given to illustrate the efficiency of the proposed method.
Yeh, Shu-Hao; Engel, Gregory S.; Kais, Sabre
Recently it has been suggested that the long-lived coherences in some photosynthetic pigment-protein systems, such as the Fenna-Matthews-Olson complex, could be attributed to the mixing of the pigments' electronic and vibrational degrees of freedom. In order to verify whether this is the case and to understand its underlying mechanism, a theoretical model capable of including both the electronic excitations and intramolecular vibrational modes of the pigments is necessary. Our model simultaneously considers the electronic and vibrational degrees of freedom, treating the system-environment interactions non-perturbatively by implementing the hierarchical equations of motion approach. Here we report the simulated two-dimensional electronic spectra of vibronically coupled molecular dimers to demonstrate how the electronic coherence lifetimes can be extended by borrowing the lifetime from the vibrational coherences. Funded by Qatar National Research Fund and Qatar Environment and Energy Research Institute.
Directory of Open Access Journals (Sweden)
Pornchai Bumroongsri
2012-04-01
Full Text Available In this paper, the model predictive control (MPC algorithm for linear parameter varying (LPV systems is proposed. The proposed algorithm consists of two steps. The first step is derived by using parameter-dependent Lyapunov function and the second step is derived by using the perturbation on control input strategy. In order to achieve good control performance, the bounds on the rate of variation of the parameters are taken into account in the controller synthesis. An overall algorithm is proved to guarantee robust stability. The controller design is illustrated with two case studies of continuous stirred-tank reactors. Comparisons with other MPC algorithms for LPV systems have been undertaken. The results show that the proposed algorithm can achieve better control performance.
Directory of Open Access Journals (Sweden)
Zhaohui Chen
2013-01-01
Full Text Available The delay-dependent exponential L2-L∞ performance analysis and filter design are investigated for stochastic systems with mixed delays and nonlinear perturbations. Based on the delay partitioning and integral partitioning technique, an improved delay-dependent sufficient condition for the existence of the L2-L∞ filter is established, by choosing an appropriate Lyapunov-Krasovskii functional and constructing a new integral inequality. The full-order filter design approaches are obtained in terms of linear matrix inequalities (LMIs. By solving the LMIs and using matrix decomposition, the desired filter gains can be obtained, which ensure that the filter error system is exponentially stable with a prescribed L2-L∞ performance γ. Numerical examples are provided to illustrate the effectiveness and significant improvement of the proposed method.
Exploring uncertainty of Amazon dieback in a perturbed parameter Earth system ensemble.
Boulton, Chris A; Booth, Ben B B; Good, Peter
2017-12-01
The future of the Amazon rainforest is unknown due to uncertainties in projected climate change and the response of the forest to this change (forest resiliency). Here, we explore the effect of some uncertainties in climate and land surface processes on the future of the forest, using a perturbed physics ensemble of HadCM3C. This is the first time Amazon forest changes are presented using an ensemble exploring both land vegetation processes and physical climate feedbacks in a fully coupled modelling framework. Under three different emissions scenarios, we measure the change in the forest coverage by the end of the 21st century (the transient response) and make a novel adaptation to a previously used method known as "dry-season resilience" to predict the long-term committed response of the forest, should the state of the climate remain constant past 2100. Our analysis of this ensemble suggests that there will be a high chance of greater forest loss on longer timescales than is realized by 2100, especially for mid-range and low emissions scenarios. In both the transient and predicted committed responses, there is an increasing uncertainty in the outcome of the forest as the strength of the emissions scenarios increases. It is important to note however, that very few of the simulations produce future forest loss of the magnitude previously shown under the standard model configuration. We find that low optimum temperatures for photosynthesis and a high minimum leaf area index needed for the forest to compete for space appear to be precursors for dieback. We then decompose the uncertainty into that associated with future climate change and that associated with forest resiliency, finding that it is important to reduce the uncertainty in both of these if we are to better determine the Amazon's outcome. © 2017 John Wiley & Sons Ltd.
International Nuclear Information System (INIS)
Ecker, G.
1996-06-01
After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In the pion-nucleon system, the linear σ model is contrasted with chiral perturbation theory. The heavy-nucleon expansion is used to construct the effective pion-nucleon Lagrangian to third order in the low-energy expansion, with applications to nucleon Compton scattering. (author)
Persistence and Nonpersistence of a Predator Prey System with Stochastic Perturbation
Directory of Open Access Journals (Sweden)
Haihong Li
2014-01-01
show that this system has a unique positive solution. Then, we deduce conditions that the system is persistent in time average. Furthermore, we show the conditions that there is a stationary distribution of the system which implies that the system is permanent. After that, conditions for the system going extinct in probability are established. At last, numerical simulations are carried out to support our results.
Pereira, Claudete Fernandes; Pasquini, Celio
2010-05-01
A flow system is proposed to produce a concentration perturbation in liquid samples, aiming at the generation of two-dimensional correlation near-infrared spectra. The system presents advantages in relation to batch systems employed for the same purpose: the experiments are accomplished in a closed system; application of perturbation is rapid and easy; and the experiments can be carried out with micro-scale volumes. The perturbation system has been evaluated in the investigation and selection of relevant variables for multivariate calibration models for the determination of quality parameters of gasoline, including ethanol content, MON (motor octane number), and RON (research octane number). The main advantage of this variable selection approach is the direct association between spectral features and chemical composition, allowing easy interpretation of the regression models.
al Aamery, N. M. H.; Mahoney, D. T.; Fox, J.
2017-12-01
Future climate change projections suggest extreme impacts on watershed hydrologic systems for some regions of the world including pronounced increases in surface runoff and instream flows. Yet, there remains a lack of research focused on how future changes in hydrologic extremes, as well as relative hydrologic mean changes, impact sediment redistribution within a watershed and sediment flux from a watershed. The authors hypothesized that variations in mean and extreme changes in turn may impact sediments in depositional and erosional dominance in a manner that may not be obvious to the watershed manager. Therefore, the objectives of this study were to investigate the inner processes connecting the combined effect of extreme climate change projections on the vegetation, upland erosion, and instream processes to produce changes in sediment redistribution within watersheds. To do so, research methods were carried out by the authors including simulating sediment processes in forecast and hindcast periods for a lowland watershed system. Publically available climate realizations from several climate factors and the Soil Water Assessment Tool (SWAT) were used to predict hydrologic conditions for the South Elkhorn Watershed in central Kentucky, USA to 2050. The results of the simulated extreme and mean hydrological components were used in simulating upland erosion with the connectivity processes consideration and thereafter used in building and simulating the instream erosion and deposition of sediment processes with the consideration of surface fine grain lamina (SFGL) layer controlling the benthic ecosystem. Results are used to suggest the dominance of erosional and depositional redistribution of sediments under different scenarios associated with extreme and mean hydrologic forecasting. The results are discussed in reference to the benthic ecology of the stream system providing insight on how water managers might consider sediment redistribution in a changing climate.
Directory of Open Access Journals (Sweden)
Rozana Alik
2016-03-01
Full Text Available This paper presents a simple checking algorithm for maximum power point tracking (MPPT technique for Photovoltaic (PV system using Perturb and Observe (P&O algorithm. The main benefit of this checking algorithm is the simplicity and efficiency of the system whose duty cycle produced by the MPPT is smoother and changes faster according to maximum power point (MPP. This checking algorithm can determine the maximum power first before the P&O algorithm takes place to identify the voltage at MPP (VMPP, which is needed to calculate the duty cycle for the boost converter. To test the effectiveness of the algorithm, a simulation model of PV system has been carried out using MATLAB/Simulink under different level of irradiation; or in other words partially shaded condition of PV array. The results from the system using the proposed approach prove to have faster response and low ripple. Besides, the results are close to the desired outputs and exhibit an approximately 98.25% of the system efficiency. On the other hand, the system with conventional P&O MPPT seems to be unstable and has higher percentage of error. In summary, the proposed method is useful under varying level of irradiation with higher efficiency of the system.
Tokarz, John A; Ahn, Mi-Youn; Leng, June; Filley, Timothy R; Nies, Loring
2008-02-15
Because of the bioaccumulation of penta- and tetrapolybrominated diphenyl ether (PBDE) flame retardants in biota,the environmental biotransformation of decabromodiphenyl ether (BDE-209) is of interest. BDE-209 accounts for more than 80% by mass of PBDE production and is the dominant PBDE in sediments. Most sediments are anaerobic and reports of microbial reductive dehalogenation of hydrophobic persistent organohalogen pollutants are numerous. Reductive debromination of BDE-209 in the environment could provide a significant source of lesser-brominated PBDEs to biota. Moreover, a recent study showed that BDE-209 debrominates in sewage sludge, and another demonstrated that some halorespiring bacteria will debrominate BDE-209. To determine whether reductive debromination of BDE-209 occurs in sediments, parallel experiments were conducted using anaerobic sediment microcosms and a cosolvent-enhanced biomimetic system. In the biomimetic system, reductive debromination occurred at rates corresponding to bromine substitution levels with a BDE-209 half-life of only 18 s compared with a halflife of almost 60 days for 2,2',4,4'-tetrabromodiphenyl ether. In sediment, the measured debromination half-life of BDE-209 was well over a decade and was in good agreement with the predicted value obtained from the biomimetic experiment. Product congeners were predominantly double para-substituted. BDE-209 debrominated in sediment with a corresponding increase in nona-, octa-, hepta-, and hexa-PBDEs. Nine new PBDE congeners appeared in sediment from reductive debromination. Given the very large BDE-209 burden already in sediments globally, it is important to determine whether this transformation is a significant source of lesser-brominated PBDEs to the environment.
Directory of Open Access Journals (Sweden)
C. R. Sherwood
2018-05-01
Full Text Available We describe and demonstrate algorithms for treating cohesive and mixed sediment that have been added to the Regional Ocean Modeling System (ROMS version 3.6, as implemented in the Coupled Ocean–Atmosphere–Wave–Sediment Transport Modeling System (COAWST Subversion repository revision 1234. These include the following: floc dynamics (aggregation and disaggregation in the water column; changes in floc characteristics in the seabed; erosion and deposition of cohesive and mixed (combination of cohesive and non-cohesive sediment; and biodiffusive mixing of bed sediment. These routines supplement existing non-cohesive sediment modules, thereby increasing our ability to model fine-grained and mixed-sediment environments. Additionally, we describe changes to the sediment bed layering scheme that improve the fidelity of the modeled stratigraphic record. Finally, we provide examples of these modules implemented in idealized test cases and a realistic application.
Sedimentation and contamination patterns of dike systems along the Rhône River (France)
Seignemartin, Gabrielle; Tena, Alvaro; Piégay, Hervé; Roux, Gwenaelle; Winiarski, Thierry
2017-04-01
Humans have historically modified the Rhône River, especially in the last centuries. In the 19th century, the river was systematically embanked for flood protection purposes, and works continued along the 20th century with dike system engineering work for navigation. The Rhône was canalised and its historical course by-passed by a series of hydroelectric dams. Besides, industrial activity polluted the river. For example, high levels of PCB's were attributed to the inputs of the heavily industrialized zone downstream from Lyon. During floods, these contaminants, associated with the suspended sediment, were trapped by the engineering works and the floodplain. Currently, a master plan to reactivate the river dynamics in the alluvial margins by removing the groyne-fields and dikes in the by-passed sections is being implemented. Within this context, this work aims to assess historical dynamics of sediment and associated contaminants in the floodplain (e.g. trace metal elements), notably in the dike system, in order to evaluate the contamination risk related to bank protection removal. With this objective, a transversal methodology has been applied coupling GIS diachronic analysis (old maps, bathymetric data, Orthophotos, LIDAR, etc.) to understand the historical floodplain evolution, sediment survey to obtain sediment thickness (metal rod and Ground Penetrating Radar), and sediment sampling (manual auger and core sampling) to obtain the metal element concentrations (X-Ray Fluorescence and Inductively Coupled Plasma Mass Spectrometry). By this way, metal element patterns were defined and used as contamination tracing indicators to apprehend the contamination history but also as geochemical background indicators to define the sediment source influence. We found that sediment temporal patterns are directly related with the by-pass construction year. Spatially, fine sediment deposition predominates in the dike systems, being lower in the floodplain already disconnected in
International Nuclear Information System (INIS)
Berman, G.P.; Borgonovi, F.; Dalvit, D.A.R.
2009-01-01
We review our results on a mathematical dynamical theory for observables for open many-body quantum nonlinear bosonic systems for a very general class of Hamiltonians. We show that non-quadratic (nonlinear) terms in a Hamiltonian provide a singular 'quantum' perturbation for observables in some 'mesoscopic' region of parameters. In particular, quantum effects result in secular terms in the dynamical evolution, that grow in time. We argue that even for open quantum nonlinear systems in the deep quasi-classical region, these quantum effects can survive after decoherence and relaxation processes take place. We demonstrate that these quantum effects in open quantum systems can be observed, for example, in the frequency Fourier spectrum of the dynamical observables, or in the corresponding spectral density of noise. Estimates are presented for Bose-Einstein condensates, low temperature mechanical resonators, and nonlinear optical systems prepared in large amplitude coherent states. In particular, we show that for Bose-Einstein condensate systems the characteristic time of deviation of quantum dynamics for observables from the corresponding classical dynamics coincides with the characteristic time-scale of the well-known quantum nonlinear effect of phase diffusion.
Nonlinear perturbations of systems of partial differential equations with constant coefficients
Directory of Open Access Journals (Sweden)
Carmen J. Vanegas
2000-01-01
Full Text Available In this article, we show the existence of solutions to boundary-value problems, consisting of nonlinear systems of partial differential equations with constant coefficients. For this purpose, we use the right inverse of an associated operator and a fix point argument. As illustrations, we apply this method to Helmholtz equations and to second order systems of elliptic equations.
Functional evaluation of pollutant transformation in sediment from combined sewer system.
Shi, Xuan; Ngo, Huu Hao; Sang, Langtao; Jin, Pengkang; Wang, Xiaochang C; Wang, Guanghua
2018-07-01
In this study, a pilot combined sewer system was constructed to characterize the pollutant transformation in sewer sediment. The results showed that particulate contaminants deposited from sewage could be transformed into dissolved matter by distinct pollutant transformation pathways. Although the oxidation-reduction potential (ORP) was varied from -80 mV to -340 mV in different region of the sediment, the fermentation was the dominant process in all regions of the sediment, which induced hydrolysis and decomposition of particulate contaminants. As a result, the accumulation of dissolved organic matter and the variation of ORP values along the sediment depth led to the depth-dependent reproduction characteristics of methanogens and sulfate-reducing bacteria, which were existed in the middle and deep layer of the sediment respectively. However, the diversity of nitrifying and polyphosphate-accumulating bacteria was low in sewer sediment and those microbial communities showed a non-significant correlation with nitrogen and phosphorus contaminants, which indicated that the enrichment of nitrogen and phosphorus contaminants was mainly caused by physical deposition process. Thus, this study proposed a promising pathway to evaluate pollutant transformation and can help provide theoretical foundation for urban sewer improvement. Copyright © 2018 Elsevier Ltd. All rights reserved.
Sediment Transport Dynamic in a Meandering Fluvial System: Case Study of Chini River
Nazir, M. H. M.; Awang, S.; Shaaban, A. J.; Yahaya, N. K. E. M.; Jusoh, A. M.; Arumugam, M. A. R. M. A.; Ghani, A. A.
2016-07-01
Sedimentation in river reduces the flood carrying capacity which lead to the increasing of inundation area in the river basin. Basic sediment transport can predict the fluvial processes in natural rivers and stream through modeling approaches. However, the sediment transport dynamic in a small meandering and low-lying fluvial system is considered scarce in Malaysia. The aim of this study was to analyze the current riverbed erosion and sedimentation scenarios along the Chini River, Pekan, Pahang. The present study revealed that silt and clay has potentially been eroded several parts of the river. Sinuosity index (1.98) indicates that Chini River is very unstable and continuous erosion process in waterways has increase the riverbank instability due to the meandering factors. The riverbed erosional and depositional process in the Chini River is a sluggish process since the lake reduces the flow velocity and causes the deposited particles into the silt and clay soil at the bed of the lake. Besides, the bed layer of the lake comprised of cohesive silt and clayey composition that tend to attach the larger grain size of sediment. The present study estimated the total sediment accumulated along the Chini River is 1.72 ton. The HEC-RAS was employed in the simulations and in general the model performed well, once all parameters were set within their effective ranges.
Time-dependent perturbation of a two-state quantum mechanical system
Dion, D. R.
1974-01-01
A two- (nondegenerate) level quantum system interacting with a classical monochromatic radiation field is described. The existing work on this problem is reviewed and some novel aspects of the problems are presented.
Liu, Xiao; Liu, An; Zhang, Xiangliang; Li, Zhixu; Liu, Guanfeng; Zhao, Lei; Zhou, Xiaofang
2017-01-01
result. However, none is designed for both hiding users’ private data and preventing privacy inference. To achieve this goal, we propose in this paper a hybrid approach for privacy-preserving recommender systems by combining differential privacy (DP
Yasukawa, Kazutaka; Nakamura, Kentaro; Fujinaga, Koichiro; Ikehara, Minoru; Kato, Yasuhiro
2017-09-12
Multiple transient global warming events occurred during the early Palaeogene. Although these events, called hyperthermals, have been reported from around the globe, geologic records for the Indian Ocean are limited. In addition, the recovery processes from relatively modest hyperthermals are less constrained than those from the severest and well-studied hothouse called the Palaeocene-Eocene Thermal Maximum. In this study, we constructed a new and high-resolution geochemical dataset of deep-sea sediments clearly recording multiple Eocene hyperthermals in the Indian Ocean. We then statistically analysed the high-dimensional data matrix and extracted independent components corresponding to the biogeochemical responses to the hyperthermals. The productivity feedback commonly controls and efficiently sequesters the excess carbon in the recovery phases of the hyperthermals via an enhanced biological pump, regardless of the magnitude of the events. Meanwhile, this negative feedback is independent of nannoplankton assemblage changes generally recognised in relatively large environmental perturbations.
International Nuclear Information System (INIS)
Takahashi, M.; Bracken, P.; Cizek, J.; Paldus, J.
1995-01-01
The perturbation expansion coefficients for the ground-state energy of the half-filled one-dimensional Hubbard model with N = 4 ν + 2, (ν = 1,2,...) sites and satisfying cyclic boundary conditions were calculated in the Hueckel limit (U/β → 0), where β designates the one-electron hopping or resonance integral, and U, the two-electron on-site Coulomb integral. This was achieved by solving-order by order-the Lieb-Wu equations, a system of transcendental equations that determines the set of quasi-momenta (k i ) and spin variable τ α for this model. The exact values for these quantities were found for the N = 6 member ring up to the 20th order in terms of the coupling constant B = U/2β, as well as numerically for 10 ≤ N ≤ 50, and the N = 6 Lieb-Wu system was reduced to a system of sextic algebraic equations. These results are compared with those of the infinite system derived analytically by Misurkin and Ovchinnikov. It is further shown how the results of this article can be used for the interpolation by the root of a polynomial. It is demonstrated that a polynomial of relatively small degree provides a very good approximation for the energy in the intermediate coupling region. 20 refs., 3 tabs
Supersingular quantum perturbations
International Nuclear Information System (INIS)
Detwiler, L.C.; Klauder, J.R.
1975-01-01
A perturbation potential is called supersingular whenever generally every matrix element of the perturbation in the unperturbed eigenstates is infinite. It follows that supersingular perturbations do not have conventional perturbation expansions, say for energy eigenvalues. By invoking variational arguments, we determine the asymptotic behavior of the energy eigenvalues for asymptotically small values of the coupling constant of the supersingular perturbation
Muszynska, Agnes; Bently, Donald E.
1991-01-01
Perturbation techniques used for identification of rotating system dynamic characteristics are described. A comparison between two periodic frequency-swept perturbation methods applied in identification of fluid forces of rotating machines is presented. The description of the fluid force model identified by inputting circular periodic frequency-swept force is given. This model is based on the existence and strength of the circumferential flow, most often generated by the shaft rotation. The application of the fluid force model in rotor dynamic analysis is presented. It is shown that the rotor stability is an entire rotating system property. Some areas for further research are discussed.
On the generating function of Poincare plots defining one dimensional perturbed Hamiltonian systems
International Nuclear Information System (INIS)
Montvai, A.
1989-01-01
A simple numerical method has been devised, for deriving the generating function of an arbitrary, one dimensional Hamiltonian system represented by its Poincare plot. In this case, the plot to be numerically processed is an area preserving transformation of a two-dimensional surface onto itself. Although the method in its present form is capable of treating only this case, there are no principal restrictions excluding the analysis of systems with higher dimensionality as well. As an example, the generating function of the motion of alpha particles in a nonsymmetric, toroidal magnetic field is derived and studied numerically. (orig.)
González-Díaz, Humberto; Arrasate, Sonia; Gómez-SanJuan, Asier; Sotomayor, Nuria; Lete, Esther; Besada-Porto, Lina; Ruso, Juan M
2013-01-01
In general perturbation methods starts with a known exact solution of a problem and add "small" variation terms in order to approach to a solution for a related problem without known exact solution. Perturbation theory has been widely used in almost all areas of science. Bhor's quantum model, Heisenberg's matrix mechanincs, Feyman diagrams, and Poincare's chaos model or "butterfly effect" in complex systems are examples of perturbation theories. On the other hand, the study of Quantitative Structure-Property Relationships (QSPR) in molecular complex systems is an ideal area for the application of perturbation theory. There are several problems with exact experimental solutions (new chemical reactions, physicochemical properties, drug activity and distribution, metabolic networks, etc.) in public databases like CHEMBL. However, in all these cases, we have an even larger list of related problems without known solutions. We need to know the change in all these properties after a perturbation of initial boundary conditions. It means, when we test large sets of similar, but different, compounds and/or chemical reactions under the slightly different conditions (temperature, time, solvents, enzymes, assays, protein targets, tissues, partition systems, organisms, etc.). However, to the best of our knowledge, there is no QSPR general-purpose perturbation theory to solve this problem. In this work, firstly we review general aspects and applications of both perturbation theory and QSPR models. Secondly, we formulate a general-purpose perturbation theory for multiple-boundary QSPR problems. Last, we develop three new QSPR-Perturbation theory models. The first model classify correctly >100,000 pairs of intra-molecular carbolithiations with 75-95% of Accuracy (Ac), Sensitivity (Sn), and Specificity (Sp). The model predicts probabilities of variations in the yield and enantiomeric excess of reactions due to at least one perturbation in boundary conditions (solvent, temperature
Singular perturbation solutions of steady-state Poisson-Nernst-Planck systems.
Wang, Xiang-Sheng; He, Dongdong; Wylie, Jonathan J; Huang, Huaxiong
2014-02-01
We study the Poisson-Nernst-Planck (PNP) system with an arbitrary number of ion species with arbitrary valences in the absence of fixed charges. Assuming point charges and that the Debye length is small relative to the domain size, we derive an asymptotic formula for the steady-state solution by matching outer and boundary layer solutions. The case of two ionic species has been extensively studied, the uniqueness of the solution has been proved, and an explicit expression for the solution has been obtained. However, the case of three or more ions has received significantly less attention. Previous work has indicated that the solution may be nonunique and that even obtaining numerical solutions is a difficult task since one must solve complicated systems of nonlinear equations. By adopting a methodology that preserves the symmetries of the PNP system, we show that determining the outer solution effectively reduces to solving a single scalar transcendental equation. Due to the simple form of the transcendental equation, it can be solved numerically in a straightforward manner. Our methodology thus provides a standard procedure for solving the PNP system and we illustrate this by solving some practical examples. Despite the fact that for three ions, previous studies have indicated that multiple solutions may exist, we show that all except for one of these solutions are unphysical and thereby prove the existence and uniqueness for the three-ion case.
International Nuclear Information System (INIS)
Sakai, Shiro; Arita, Ryotaro; Aoki, Hideo
2006-01-01
We propose a new quantum Monte Carlo method especially intended to couple with the dynamical mean-field theory. The algorithm is not only much more efficient than the conventional Hirsch-Fye algorithm, but is applicable to multiorbital systems having an SU(2)-symmetric Hund's coupling as well
Energy Technology Data Exchange (ETDEWEB)
Yoon, Hyunjin; Ansong, Charles; McDermott, Jason E.; Gritsenko, Marina A.; Smith, Richard D.; Heffron, Fred; Adkins, Joshua N.
2011-06-28
Background: Systemic bacterial infections are highly regulated and complex processes that are orchestrated by numerous virulence factors. Genes that are coordinately controlled by the set of regulators required for systemic infection are potentially required for pathogenicity. Results: In this study we present a systems biology approach in which sample-matched multi-omic measurements of fourteen virulence-essential regulator mutants were coupled with computational network analysis to efficiently identify Salmonella virulence factors. Immunoblot experiments verified network-predicted virulence factors and a subset was determined to be secreted into the host cytoplasm, suggesting that they are virulence factors directly interacting with host cellular components. Two of these, SrfN and PagK2, were required for full mouse virulence and were shown to be translocated independent of either of the type III secretion systems in Salmonella or the type III injectisome-related flagellar mechanism. Conclusions: Integrating multi-omic datasets from Salmonella mutants lacking virulence regulators not only identified novel virulence factors but also defined a new class of translocated effectors involved in pathogenesis. The success of this strategy at discovery of known and novel virulence factors suggests that the approach may have applicability for other bacterial pathogens.
Gas hydrate geohazards in shallow sediments and their impact on the design of subsea systems
Energy Technology Data Exchange (ETDEWEB)
Peters, D.; Hatton, G. [Shell Global Solutions Inc., Houston, TX (United States); Mehta, A. [Shell Malaysia Exploration and Production, Sarawak (Malaysia); Hadley, C. [Shell Exploration and Production Inc., Houston, TX (United States)
2008-07-01
This paper described the challenges that exist in producing gas hydrates in deepwater and Arctic environments as a potential source of methane gas. In order to safely produce hydrocarbon reservoirs far beneath near-mudline hydrates, it is important to understand and manage the geohazard risks associated with wells that pass through hydrate-bearing sediments. Since these wells may produce for decades, the temperature of near-mudline sediments may increase above the hydrate dissociation temperature for hundreds of meters from the well. This can result in the release of large quantities of gas causing a volume change that can impact the subsea system in many ways. As the fluids of an underlying reservoir flow to the mudline, heat carried by the fluids warms nearwell sediments and dissociates hydrates, which releases gas that can displace and fracture near well soil. This gas release may be calculated with numerical simulations that model heat and mass transfer in hydrate-bearing sediments. The model simulations require information on the nature and distribution of hydrates within the sediments, the melting behaviour of the hydrates, the thermal and mechanical properties of these shallow sediments, and the amount of hydrates contained in the sediments. However, this information is costly to acquire and characterize with certainty for an offshore development. Therefore, it is important to understand what information, processes, and calculations are needed in order to ensure safe, robust systems to produce the hydrocarbon reservoirs far below the hydrates. It was concluded that the relation between the quantity of gas released and dissociated gas quantities must be well understood. The hydrate concentration is a critical reservoir parameter for reservoirs with severe geohazard risk. 6 refs., 6 figs.
Behavior, balance and distribution of sediments within irrigation systems. Application to Pakistan
International Nuclear Information System (INIS)
Vabre, Alexandre
2000-01-01
This PhD work is part of a research program between Cemagref, CEA and IWMI. It aims at studying the sediment deposition phenomena in irrigation Systems of Pakistan. Indeed, many Systems are subject to an excessive sediment deposition that widely disturbs their functioning. A pragmatic approach of the problem is chosen, and the sediment deposition description is realized through global methods. This choice is done in order to allow the developed methods and tools to be utilized directly by the irrigation managers. A global numerical modeling method (GSM) is proposed. It lies on classical laws of sediment transport but a new formalism is proposed for the expression of the deposition. It's a relationship between the sediment trapping efficiency of a reach and its sediment transport capacity. Also, criteria are defined for the definition of homogeneous reaches in the system. An outline of GSM is implemented on a sediment deposition data set of an actual System in Pakistan (Jamrao). A measurement campaign using radio-activable tracers is then carried out on this site to complete the GSM working data set Also, such a campaign with it only is a description method of the deposition phenomena in the irrigation System. The strength of the modeling approach laws is then tested on another case study of irrigation System in Pakistan (Chashma). The results are very much encouraging because the GSM model could be calibrated and validated on several actual deposition trends with quite moderate errors for such a tool. Also, the constituted data set from the tracer campaign was found minimum and sufficient to implement the GSM. Moreover, it has been possible to use the GSM for irrigation management applications. A design criterion for stable canals is proposed. And the GSM has allowed to identify an hydraulic operational scenario on an irrigation System that decreases the deposition. The perspectives of this work are to test the GSM approach on other data sets and then to
International Nuclear Information System (INIS)
Zhang Longcai; Wang Suyu; Wang Jiasu
2009-01-01
Superconducting maglev vehicle was one of the most promising applications of HTS bulks. In such a system, the HTS bulks were always exposed to AC external magnetic field, which was generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, it was observed that the guidance force of the YBCO bulk over the NdFdB guideway used in the high-temperature superconducting maglev vehicle system was decayed by the application of the AC external magnetic field. In this paper, we adopted a method to suppress the decay by altering the field-cooled height of the bulk. From the experimental results, it was found that the decay rate of the guidance force was smaller at lower field-cooled height. So we could suppress the guidance force decay of HTS bulk exposed to AC external magnetic field perturbation in the maglev vehicle system by reducing the field-cooled height of the bulk. Furthermore, all the experimental results in this paper were explained based on Bean critical-state model.
Energy Technology Data Exchange (ETDEWEB)
Zhang Longcai, E-mail: zhlcai2000@163.co [College of Air Traffic Management, Civil Aviation Flight University of China, Guanghan, Sichuan 618307 (China); Wang Suyu; Wang Jiasu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China)
2009-07-01
Superconducting maglev vehicle was one of the most promising applications of HTS bulks. In such a system, the HTS bulks were always exposed to AC external magnetic field, which was generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, it was observed that the guidance force of the YBCO bulk over the NdFdB guideway used in the high-temperature superconducting maglev vehicle system was decayed by the application of the AC external magnetic field. In this paper, we adopted a method to suppress the decay by altering the field-cooled height of the bulk. From the experimental results, it was found that the decay rate of the guidance force was smaller at lower field-cooled height. So we could suppress the guidance force decay of HTS bulk exposed to AC external magnetic field perturbation in the maglev vehicle system by reducing the field-cooled height of the bulk. Furthermore, all the experimental results in this paper were explained based on Bean critical-state model.
Energy Technology Data Exchange (ETDEWEB)
Tiehm, Andreas [Technologiezentrum Wasser (TZW), Karlsruhe (Germany). Abt. Umweltbiotechnologie und Altlasten; Kranzioch, Irene; Stoll, Claudia
2011-09-15
The microbial degradation of pollutants in the aquatic environment essentially is influenced by the prevailing redox conditions and mass exchange processes (bioavailability). Within a new project, the Technologiezentrum Wasser TZW (Karlsruhe, Federal Republic of Germany) deals with the microbial conversion under dynamic conditions such as those expected in the area of the Three Gorges Dam at the Yangtze River. In particular, molecular-biological methods (PCR, polymerase chain reaction and DGGE Denatured gradient gel electrophoresis) are used for a targeted monitoring and further developed. The focus of the investigation initially focuses on the degradation of halogenated substances which are used as main substances for understanding the mass exchange between sediment and water as well as the microbial conversion processes. An enhanced understanding of the process and the compilation of the dynamic sales performance can be defined as a target.
International Nuclear Information System (INIS)
Zhu, Wu; Fang, Jian-an; Tang, Yang; Zhang, Wenbing; Xu, Yulong
2012-01-01
In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. -- Highlights: ► Switching population utilization strategy is applied for differential evolution. ► The parameters are estimated in both deterministic and stochastic environments. ► Comparisons with five other EAs verify the effectiveness of the proposed method.
Energy Technology Data Exchange (ETDEWEB)
Zhu, Wu, E-mail: dtzhuwu@gmail.com [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Fang, Jian-an [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Tang, Yang, E-mail: yang.tang@pik-potsdam.de [Institute of Physics, Humboldt University, Berlin 12489 (Germany); Potsdam Institute for Climate Impact Research, Potsdam 14415 (Germany); Research Institute for Intelligent Control and System, Harbin Institute of Technology, Harbin 150006 (China); Zhang, Wenbing [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Xu, Yulong [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)
2012-10-01
In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. -- Highlights: ► Switching population utilization strategy is applied for differential evolution. ► The parameters are estimated in both deterministic and stochastic environments. ► Comparisons with five other EAs verify the effectiveness of the proposed method.
DEFF Research Database (Denmark)
Pedersen, Michael
1991-01-01
The stabilization problems for parabolic and hyperbolic partial differential equations with Dirichlet boundary condition are considered. The systems are stabilized by a boundary feedback in(1) The operator equation,(2) The boundary condition,(3) Both the operator equation and the boundary condition...... turns out to be a shortcut to some of the stabilization results of Lasiecka and Triggiani in [J. Differential Equations, 47 (1983), pp. 245-272], [SIAM J. Control Optim., 21(1983), pp. 766-802], and [Appl. Math. Optim., 8(1981), pp. 1-37], and it illuminates to some extent how a change of boundary...
International Nuclear Information System (INIS)
Rey, Julien
2016-01-01
Separative chemistry is a pillar of technologic development in extraction, separation and selective remediation of metals and molecules. It finds its applications in the fields of electronic, renewable energy, medicine and chemistry, which require more than ever the use of 'Strategic Metals'. The liquid-liquid extraction is a separation technique that is involved in hydrometallurgical processes for the recovery of strategic metals from primary deposits, secondary and urban mines. This work is part of global vision of optimization of liquid-liquid extraction processes used in synergy, consisting in understanding the mechanisms underlying the synergy, and generalizing these mechanisms to all synergistic extraction systems. The understanding of these mechanisms underlying synergism aims at predicting and developing new synergistic extractants mixtures.To better understand the driving forces at the origin of synergistic phenomena, a suitable methodology for the characterization of supramolecular structures of extractant in the organic phase was exploited during this thesis work. The use of techniques like Small Angle Neutron/X-ray Scattering (SAXS/ANS) and interfacial tensiometry was crucial for the understanding of the synergistic mechanisms. A thermodynamical was also proposed to estimate quantitatively the key driving forces involved in the liquid-liquid extraction mechanisms. The application of these keys of comprehension helped to design a new synergistic system for the extraction of rare earths elements from phosphoric medium. (author) [fr
Small random perturbations of infinite dimensional dynamical systems and nucleation theory
International Nuclear Information System (INIS)
Cassandro, M.; Olivieri, E.; Picco, P.
1985-06-01
We consider a stochastic differential equation with a standard space-time white noise and a double well non symmetric potential. The equation without the white noise term exhibits several equilibria two of which are stable. We study, in the double limit zero noise and thermodynamic limit the large fluctuations and compute the transition probability between the two stable equilibria (tunnelling). The unique stationary measure associated to the stochastic process described by our equation is strictly related to the Gibbs measure for a ferromagnetic spin system subject to a Kac interaction. Our double limit corresponds to the one considered by Lobowitz and Penrose in their rigorous version of the mean field theory of the first order phase transitions. The tunnelling between the two (non equivalent) equilibrium configurations is interpreted as the decay from the metastable to the stable state. Our results are in qualitative agreement with the usual nucleation theory
Directory of Open Access Journals (Sweden)
Corey M. James
2017-10-01
Full Text Available A model predictive control (MPC framework, exploiting both feedforward and feedback control loops, is employed to minimize large disturbances that occur in military water networks. Military installations’ need for resilient and efficient water supplies is often challenged by large disturbances like fires, terrorist activity, troop training rotations, and large scale leaks. This work applies the effectiveness of MPC to provide predictive capability and compensate for vast geographical differences and varying phenomena time scales using computational software and actual system dimensions and parameters. The results show that large disturbances are rapidly minimized while maintaining chlorine concentration within legal limits at the point of demand and overall water usage is minimized. The control framework also ensures pumping is minimized during peak electricity hours, so costs are kept lower than simple proportional control. Thecontrol structure implemented in this work is able to support resiliency and increased efficiency on military bases by minimizing tank holdup, effectively countering large disturbances, and efficiently managing pumping.
Energy Technology Data Exchange (ETDEWEB)
White, J.R.
1985-04-01
This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code black for both static and time-dependent perturbation theory and data sensitivity analyses. The DEPTH-CHARGE system is of modular construction and has been implemented within the VENTURE-BURNER computational system at Oak Ridge National Laboratory. The DEPTH module (coupled with VENTURE) solves for the three adjoint functions of Depletion Perturbation Theory and calculates the desired time-dependent derivatives of the response with respect to the nuclide concentrations and nuclear data utilized in the reference model. The CHARGE code is a collection of utility routines for general data manipulation and input preparation and considerably extends the usefulness of the system through the automatic generation of adjoint sources, estimated perturbed responses, and relative data sensitivity coefficients. Combined, the DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analyses of realistic multidimensional reactor models. This current documentation incorporates minor revisions to the original DEPTH-CHARGE documentation (ORNL/CSD-78) to reflect some new capabilities within the individual codes.
International Nuclear Information System (INIS)
Hausinger, Johannes; Grifoni, Milena
2010-01-01
We study the dissipative dynamics of a two-level system (TLS) exposed to strong ac driving. By combining Floquet theory with Van Vleck perturbation theory in the TLS tunneling matrix element, we diagonalize the time-dependent Hamiltonian and provide corrections to the renormalized Rabi frequency of the TLS, which are valid for both a biased and unbiased TLS and go beyond the known high-frequency and rotating-wave results. In order to mimic environmental influences on the TLS, we couple the system weakly to a thermal bath and solve analytically the corresponding Floquet-Bloch-Redfield master equation. We give a closed expression for the relaxation and dephasing rates of the TLS and discuss their behavior under variation of the driving amplitude. Further, we examine the robustness of coherent destruction of tunneling (CDT) and driving-induced tunneling oscillations (DITO). We show that also for a moderate driving frequency an almost complete suppression of tunneling can be achieved for short times and demonstrate the sensitiveness of DITO to a change of the external parameters.
The power of perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Serone, Marco [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Spada, Gabriele [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Villadoro, Giovanni [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)
2017-05-10
We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the Picard-Lefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented.
International Nuclear Information System (INIS)
Wieslander, Elinore; Knoeoes, Tommy
2003-01-01
An increasing number of patients receiving radiation therapy have metallic implants such as hip prostheses. Therefore, beams are normally set up to avoid irradiation through the implant; however, this cannot always be accomplished. In such situations, knowledge of the accuracy of the used treatment planning system (TPS) is required. Two algorithms, the pencil beam (PB) and the collapsed cone (CC), are implemented in the studied TPS. Comparisons are made with Monte Carlo simulations for 6 and 18 MV. The studied materials are steel, CoCrMo, Orthinox(a stainless steel alloy and registered trademark of Stryker Corporation), TiAlV and Ti. Monte Carlo simulated depth dose curves and dose profiles are compared to CC and PB calculated data. The CC algorithm shows overall a better agreement with Monte Carlo than the PB algorithm. Thus, it is recommended to use the CC algorithm to get the most accurate dose calculation both for the planning target volume and for tissues adjacent to the implants when beams are set up to pass through implants
Soury, Hamza
2016-01-01
derived for two detectors, maximum likelihood and minimum distance detectors. Next, we look at the intra cell interference of a full duplex cellular network which is shown to follow a Laplacian distribution with dependent, but uncorrelated, complex components. The densities of that interference are expressed in a closed form in order to obtain the SER of several communication systems (BPSK, PAM, QAM, and MPSK). Finally, we study the statistics of the α-stable distribution. Those statistics are expressed in closed form in terms of the Fox H function and used to get the SER of BPSK, PAM, and QAM constellations. An approximation and an asymptotic expansion for high signal to noise ratio are presented also and their efficiency is proved using Monte Carlo simulations. It is worth mentioning that all the error rates presented in this work are averaged over a generalized flat fading, namely the extended generalized K, which has the ability to capture most of the known fading distribution. Many special cases are treated and simpler closed form expressions of the probability of error are derived and compared to some previous reported results.
A Geographic Information System approach to modeling nutrient and sediment transport
Energy Technology Data Exchange (ETDEWEB)
Levine, D.A. [Automated Sciences Group, Inc., Oak Ridge, TN (United States); Hunsaker, C.T.; Beauchamp, J.J. [Oak Ridge National Lab., TN (United States); Timmins, S.P. [Analysas Corp., Oak Ridge, TN (United States)
1993-02-01
The objective of this study was to develop a water quality model to quantify nonpoint-source (NPS) pollution that uses a geographic information system (GIS) to link statistical modeling of nutrient and sediment delivery with the spatial arrangement of the parameters that drive the model. The model predicts annual nutrient and sediment loading and was developed, calibrated, and tested on 12 watersheds within the Lake Ray Roberts drainage basin in north Texas. Three physiographic regions are represented by these watersheds, and model success, as measured by the accuracy of load estimates, was compared within and across these regions.
International Nuclear Information System (INIS)
Ronco, Ana Maria; Montenegro, Marcela; Castillo, Paula; Urrutia, Manuel; Saez, Daniel; Hirsch, Sandra; Zepeda, Ramiro; Llanos, Miguel N.
2011-01-01
Several cardiovascular diseases (CVD) observed in adulthood have been associated with environmental influences during fetal growth. Here, we show that maternal exposure to cadmium, a ubiquitously distributed heavy metal and main component of cigarette smoke is able to induce cardiovascular morpho-functional changes in the offspring at adult age. Heart morphology and vascular reactivity were evaluated in the adult offspring of rats exposed to 30 ppm of cadmium during pregnancy. Echocardiographic examination shows altered heart morphology characterized by a concentric left ventricular hypertrophy. Also, we observed a reduced endothelium-dependent reactivity in isolated aortic rings of adult offspring, while endothelium-independent reactivity remained unaltered. These effects were associated with an increase of hem-oxygenase 1 (HO-1) expression in the aortas of adult offspring. The expression of HO-1 was higher in females than males, a finding likely related to the sex-dependent expression of the vascular cell adhesion molecule 1 (VCAM-1), which was lower in the adult female. All these long-term consequences were observed along with normal birth weights and absence of detectable levels of cadmium in fetal and adult tissues of the offspring. In placental tissues however, cadmium levels were detected and correlated with increased NF-κB expression - a transcription factor sensitive to inflammation and oxidative stress - suggesting a placentary mechanism that affect genes related to the development of the cardiovascular system. Our results provide, for the first time, direct experimental evidence supporting that exposure to cadmium during pregnancy reprograms cardiovascular development of the offspring which in turn may conduce to a long term increased risk of CVD.
Geometry of tidal inlet systems : A key factor for the net sediment transport in tidal inlets
Ridderinkhof, W.; de Swart, H. E.; van der Vegt, M.; Alebregtse, N. C.; Hoekstra, P.
2014-01-01
The net transport of sediment between the back-barrier basin and the sea is an important process for determining the stability of tidal inlet systems. Earlier studies showed that in a short basin, tidal flats favor peak ebb-currents stronger than peak flood currents, implying export of coarse
Aggregation, sedimentation, dissolution and bioavailability of quantum dots in estuarine systems.
To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly p...
International Nuclear Information System (INIS)
Kasper, R.B.; Kay, M.A.; Bruns, L.E.; Stokes, J.A.; Steinman, D.K.; Adams, J.
1980-11-01
A prototype urainium borehole logging system, developed for uranium exploration, was modified for Pu assay and testing at the site. It uses the delayed fission neutron (DFN) method. It was tested in a retired Pu facility, the 216-Z-1A Crib. General agreement between laboratory determined Pu concentrations in sediment samples and neutron flux measurements was found for the relative distribution with depth
International Nuclear Information System (INIS)
Orlenko, E. V.; Ershova, E. V.; Orlenko, F. E.
2013-01-01
The formalism of exchange perturbation theory is presented with regard to the general principles of constructing an antisymmetric vector with the use of the Young diagrams and tableaux in which the coordinate and spin parts are not separated. The form of the energy and wave function corrections coincides with earlier obtained expressions, which are reduced in the present paper to a simpler form of a symmetry-adapted perturbation operator, which preserves all intercenter exchange contributions. The exchange perturbation theory (EPT) formalism itself is presented in the standard form of invariant perturbation theory that takes into account intercenter electron permutations between overlapping nonorthogonal states. As an example of application of the formalism of invariant perturbation theory, we consider the magnetic properties of perovskite manganites La 1/3 Ca 2/3 MnO 3 that are associated with the charge and spin ordering in magnetic chains of manganese. We try to interpret the experimental results obtained from the study of the effect of doping the above alloys by the model of superexchange interaction in manganite chains that is constructed on the basis of the exchange perturbation theory (EPT) formalism. The model proposed makes it possible to carry out a quantitative analysis of the effect of substitution of manganese atoms by doping elements with different electron configurations on the electronic structure and short-range order in a magnetic chain of manganites
Geometric Hamiltonian structures and perturbation theory
International Nuclear Information System (INIS)
Omohundro, S.
1984-08-01
We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging
Directory of Open Access Journals (Sweden)
Mimi Guan
Full Text Available BACKGROUND: Elucidation of metabolic profiles during diabetes progression helps understand the pathogenesis of diabetes mellitus. In this study, urine metabonomics was used to identify time-related metabolic changes that occur during the development of diabetes mellitus and characterize the biochemical process of diabetes on a systemic, metabolic level. METHODOLOGY/PRINCIPAL FINDINGS: Urine samples were collected from diabetic rats and age-matched controls at different time points: 1, 5, 10, and 15 weeks after diabetes modeling. (1H nuclear magnetic resonance ((1H NMR spectra of the urine samples were obtained and analyzed by multivariate data analysis and quantitative statistical analysis. The metabolic patterns of diabetic groups are separated from the controls at each time point, suggesting that the metabolic profiles of diabetic rats were markedly different from the controls. Moreover, the samples from the diabetic 1-wk group are closely associated, whereas those of the diabetic 15-wk group are scattered, suggesting that the presence of various of complications contributes significantly to the pathogenesis of diabetes. Quantitative analysis indicated that urinary metabolites related to energy metabolism, tricarboxylic acid (TCA cycle, and methylamine metabolism are involved in the evolution of diabetes. CONCLUSIONS/SIGNIFICANCE: The results highlighted that the numbers of metabolic changes were related to diabetes progression, and the perturbed metabolites represent potential metabolic biomarkers and provide clues that can elucidate the mechanisms underlying the generation and development of diabetes as well as its complication.
Griffiths, Ronald E.; Topping, David J.
2017-11-01
Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-budget studies have estimated the sediment loads of ungaged tributaries using regional sediment-yield equations or other similar techniques. While these approaches may be valid in regions where rainfall and geology are uniform over large areas, use of sediment-yield equations may lead to poor estimations of loads in regions where rainfall events, contributing geology, and vegetation have large spatial and/or temporal variability. Previous estimates of the combined mean-annual sediment load of all ungaged tributaries to the Colorado River downstream from Glen Canyon Dam vary by over a factor of three; this range in estimated sediment loads has resulted in different researchers reaching opposite conclusions on the sign (accumulation or deficit) of the sediment budget for particular reaches of the Colorado River. To better evaluate the supply of fine sediment (sand, silt, and clay) from these tributaries to the Colorado River, eight gages were established on previously ungaged tributaries in Glen, Marble, and Grand canyons. Results from this sediment-monitoring network show that previous estimates of the annual sediment loads of these tributaries were too high and that the sediment budget for the Colorado River below Glen Canyon Dam is more negative than previously calculated by most researchers. As a result of locally intense rainfall events with footprints smaller than the receiving basin, floods from a single tributary in semi-arid regions can have large (≥ 10 ×) differences in sediment concentrations between equal magnitude flows. Because sediment loads do not
Enhanced electroforced sedimentation of various solid- liquid systems
African Journals Online (AJOL)
GREGORY
2011-12-16
Dec 16, 2011 ... liquid systems. Mohammed S. Jami1* ... significant challenges in wastewater management. ... environmental sludge and biosolids, thereby reducing the volumes to be disposed through landfills, incineration or other means.
Perturbation theory of effective Hamiltonians
International Nuclear Information System (INIS)
Brandow, B.H.
1975-01-01
This paper constitutes a review of the many papers which have used perturbation theory to derive ''effective'' or ''model'' Hamiltonians. It begins with a brief review of nondegenerate and non-many-body perturbation theory, and then considers the degenerate but non-many-body problem in some detail. It turns out that the degenerate perturbation problem is not uniquely defined, but there are some practical criteria for choosing among the various possibilities. Finally, the literature dealing with the linked-cluster aspects of open-shell many-body systems is reviewed. (U.S.)
The role of bacteria in the nutrient exchange between sediment and water in a flow-through system.
Kairesalo, T; Tuominen, L; Hartikainen, H; Rankinen, K
1995-03-01
The contribution of bacteria to phosphorus (P) and nitrogen (N ) release from, or retention in, sediment was studied in a flow-through system. "Live" and formaldehyde-"killed" sediment communities were incubated in 25-liter bottles with a continuous flow of P- or P + N-enriched water. Sediment bacteria in the killed communities were inhibited by adding formaldehyde (final concentration 0.04% v/v) to the sediment before the start of the experiment. Bacterial activity in the live sediments measured with [(3)H]thymidine and [(14)C]leucine incorporation techniques did not change essentially during the experiment period (7-8 days). Chemical mechanisms were found to be of principal importance in PO4-P retention in the sediment. In the live samples, the net retention of PO4-P was lower than in the killed samples, which was likely due to the reduced O2 conditions in the sediment as a consequence of bacterial mineralization. In total P exchange, however, bacteria increased the retention rate by recycling dissolved organic P in the sediment. In the live communities the retention of N was very efficient, and all the introduced NH4 -N and NO3-N was immobilized by sediment bacteria. Nitrogen enrichment, however, did not alter the P exchange rates. The gradual emergence of bacterial activity (and grazing) in the killed communities, subsequent to the dilution of formaldehyde concentration, enhanced the release of PO4-P and NH4-N from sediment.
Sutherland, Michael D.; Dafforn, Katherine A.; Scanes, Peter; Potts, Jaimie; Simpson, Stuart L.; Sim, Vivian X. Y.; Johnston, Emma L.
2017-11-01
The urbanisation of coastal zones is a major threat to the health of global estuaries and has been linked to increased contamination (e.g. metals) and excess organic matter. Urban stormwater networks collect and funnel contaminants into waterways at point sources (e.g. stormdrains). Under dry, low flow conditions, these stormwater contaminants can accumulate in sediments over time and result in modifications to benthic sediment biogeochemical processes. To quantify these processes, this field study measured differences in benthic metabolism (CR, GPP, NEM) and sediment-water nutrient fluxes (NH3, NOx, PO4) associated with stormdrains (0 m, 200 m and 1000 m away) and increased water-retention (embayments vs channels). Significant changes to benthic metabolism were detected with distance from stormdrains, and with differences in water-retention rates, above natural spatial and temporal variation. Oxygen consumption was ∼50% higher at stormdrains (0 m) compared to 1000 m away and >70% higher at stormdrains (0 m) located in embayments compared to channels. Oxygen production also appeared to decrease with distance from stormdrains in embayments, but patterns were variable. These changes to benthic metabolism were of a magnitude expected to influence benthic nutrient cycling, but NH3, NOx and PO4 fluxes were generally low, and highly spatially and temporally variable. Overall, metal (Cu) contamination explained most of the variation in sediment biogeochemical processes between embayments and channels, while sediment grain size explained differences in fluxes with distance from stormdrains. Importantly, although there was evidence of increased productivity associated with stormdrains, we also detected evidence of early hypoxia suggesting that systems with legacy stormwater contaminants exist on a tipping point. Future work should investigate changes to sediment processes after a major rainfall event, when large and sudden inputs of potentially toxic contaminants occur
A faster numerical scheme for a coupled system modeling soil erosion and sediment transport
Le, M.-H.; Cordier, S.; Lucas, C.; Cerdan, O.
2015-02-01
Overland flow and soil erosion play an essential role in water quality and soil degradation. Such processes, involving the interactions between water flow and the bed sediment, are classically described by a well-established system coupling the shallow water equations and the Hairsine-Rose model. Numerical approximation of this coupled system requires advanced methods to preserve some important physical and mathematical properties; in particular, the steady states and the positivity of both water depth and sediment concentration. Recently, finite volume schemes based on Roe's solver have been proposed by Heng et al. (2009) and Kim et al. (2013) for one and two-dimensional problems. In their approach, an additional and artificial restriction on the time step is required to guarantee the positivity of sediment concentration. This artificial condition can lead the computation to be costly when dealing with very shallow flow and wet/dry fronts. The main result of this paper is to propose a new and faster scheme for which only the CFL condition of the shallow water equations is sufficient to preserve the positivity of sediment concentration. In addition, the numerical procedure of the erosion part can be used with any well-balanced and positivity preserving scheme of the shallow water equations. The proposed method is tested on classical benchmarks and also on a realistic configuration.
International Nuclear Information System (INIS)
Rios Reyes, Carlos; Appasamy, Danen; Clive, Roberts
2011-01-01
The major sources of water pollution can be classified as municipal, industrial, and agricultural. Different types of polluted aqueous effluents and sediments may be produced, which contain relatively high levels of heavy metals. During the 1990s, the large-scale development of constructed wetlands around the world drew much attention from public and environmental groups. The present study looks at the use of an integrated remediation system using zeolites for the treatment of wastewater and sediments. Zeolites have been widely studied in the past 10 years due to their attractive properties such as molecular-sieving, high cation exchange capacities, and their affinity for heavy metals. Coal industry by-products-based zeolites (faujasite type) have been tested as an effective and low-cost novel alternative for wastewater treatment, particularly their removing of heavy metals. On the other hand, a preliminary laboratory-scale experiment was conducted on the use of natural zeolites (clinoptilolite type) for the retention of heavy metals from canal sediments. Experimental work revealed promising results, which could be replicated on a bigger scale. Although this has been developed for canal sediments, the remediation strategy can be adapted to different waterways such as rivers. The development of the proposed remediation system in a specific experimental site as the major part of an innovation park can provide great benefits to a population living near contaminated effluents. It provides not only opportunities for the mitigation of environmental impact, improving water quality and landscape amenity, but also allows for several recreational opportunities
Grzetic, Douglas J; Delaney, Kris T; Fredrickson, Glenn H
2018-05-28
We derive the effective Flory-Huggins parameter in polarizable polymeric systems, within a recently introduced polarizable field theory framework. The incorporation of bead polarizabilities in the model self-consistently embeds dielectric response, as well as van der Waals interactions. The latter generate a χ parameter (denoted χ̃) between any two species with polarizability contrast. Using one-loop perturbation theory, we compute corrections to the structure factor Sk and the dielectric function ϵ^(k) for a polarizable binary homopolymer blend in the one-phase region of the phase diagram. The electrostatic corrections to S(k) can be entirely accounted for by a renormalization of the excluded volume parameter B into three van der Waals-corrected parameters B AA , B AB , and B BB , which then determine χ̃. The one-loop theory not only enables the quantitative prediction of χ̃ but also provides useful insight into the dependence of χ̃ on the electrostatic environment (for example, its sensitivity to electrostatic screening). The unapproximated polarizable field theory is amenable to direct simulation via complex Langevin sampling, which we employ here to test the validity of the one-loop results. From simulations of S(k) and ϵ^(k) for a system of polarizable homopolymers, we find that the one-loop theory is best suited to high concentrations, where it performs very well. Finally, we measure χ̃N in simulations of a polarizable diblock copolymer melt and obtain excellent agreement with the one-loop theory. These constitute the first fully fluctuating simulations conducted within the polarizable field theory framework.
Directory of Open Access Journals (Sweden)
O. P. Yermolaev
2015-03-01
Full Text Available Quantitative assessments of soil loss from cultivated land and sediment redistribution along pathways from cultivated fields to river channels have been undertaken using a range of different methods and techniques, including erosion models, detailed studies of sediment redistribution in representative catchments, monitoring of gully head retreat and evaluation of sediment deposition in ponds and small reservoirs. Most of the sediment eroded from arable land is deposited between the lower portions of the cultivated slopes and the river channels. Less than 15% of the eroded sediment is delivered to the river channels. Sediment redistribution rates in the upper parts of the fluvial system have declined during the last 25 years in both the western and eastern parts of the Russian Plain, because of a major reduction of surface runoff during snowmelt and a reduction of the area of arable land in some parts of the study area.
Wong, Florence L.; Woodrow, Donald L.; McGann, Mary
2013-01-01
Heavy or high-specific gravity minerals make up a small but diagnostic component of sediment that is well suited for determining the provenance and distribution of sediment transported through estuarine and coastal systems worldwide. By this means, we see that surficial sand-sized sediment in the San Francisco Bay Coastal System comes primarily from the Sierra Nevada and associated terranes by way of the Sacramento and San Joaquin Rivers and is transported with little dilution through the San Francisco Bay and out the Golden Gate. Heavy minerals document a slight change from the strictly Sierran-Sacramento mineralogy at the confluence of the two rivers to a composition that includes minor amounts of chert and other Franciscan Complex components west of Carquinez Strait. Between Carquinez Strait and the San Francisco Bar, Sierran sediment is intermingled with Franciscan-modified Sierran sediment. The latter continues out the Gate and turns southward towards beaches of the San Francisco Peninsula. The Sierran sediment also fans out from the San Francisco Bar to merge with a Sierran province on the shelf in the Gulf of the Farallones. Beach-sand sized sediment from the Russian River is transported southward to Point Reyes where it spreads out to define a Franciscan sediment province on the shelf, but does not continue southward to contribute to the sediment in the Golden Gate area.
Eriksen, Janus J; Matthews, Devin A; Jørgensen, Poul; Gauss, Jürgen
2016-05-21
The accuracy at which total energies of open-shell atoms and organic radicals may be calculated is assessed for selected coupled cluster perturbative triples expansions, all of which augment the coupled cluster singles and doubles (CCSD) energy by a non-iterative correction for the effect of triple excitations. Namely, the second- through sixth-order models of the recently proposed CCSD(T-n) triples series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)] are compared to the acclaimed CCSD(T) model for both unrestricted as well as restricted open-shell Hartree-Fock (UHF/ROHF) reference determinants. By comparing UHF- and ROHF-based statistical results for a test set of 18 modest-sized open-shell species with comparable RHF-based results, no behavioral differences are observed for the higher-order models of the CCSD(T-n) series in their correlated descriptions of closed- and open-shell species. In particular, we find that the convergence rate throughout the series towards the coupled cluster singles, doubles, and triples (CCSDT) solution is identical for the two cases. For the CCSD(T) model, on the other hand, not only its numerical consistency, but also its established, yet fortuitous cancellation of errors breaks down in the transition from closed- to open-shell systems. The higher-order CCSD(T-n) models (orders n > 3) thus offer a consistent and significant improvement in accuracy relative to CCSDT over the CCSD(T) model, equally for RHF, UHF, and ROHF reference determinants, albeit at an increased computational cost.
Energy Technology Data Exchange (ETDEWEB)
Eriksen, Janus J., E-mail: janusje@chem.au.dk; Jørgensen, Poul [qLEAP Center for Theoretical Chemistry, Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Matthews, Devin A. [The Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712 (United States); Gauss, Jürgen [Institut für Physikalische Chemie, Johannes Gutenberg-Universität Mainz, D-55128 Mainz (Germany)
2016-05-21
The accuracy at which total energies of open-shell atoms and organic radicals may be calculated is assessed for selected coupled cluster perturbative triples expansions, all of which augment the coupled cluster singles and doubles (CCSD) energy by a non-iterative correction for the effect of triple excitations. Namely, the second- through sixth-order models of the recently proposed CCSD(T–n) triples series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)] are compared to the acclaimed CCSD(T) model for both unrestricted as well as restricted open-shell Hartree-Fock (UHF/ROHF) reference determinants. By comparing UHF- and ROHF-based statistical results for a test set of 18 modest-sized open-shell species with comparable RHF-based results, no behavioral differences are observed for the higher-order models of the CCSD(T–n) series in their correlated descriptions of closed- and open-shell species. In particular, we find that the convergence rate throughout the series towards the coupled cluster singles, doubles, and triples (CCSDT) solution is identical for the two cases. For the CCSD(T) model, on the other hand, not only its numerical consistency, but also its established, yet fortuitous cancellation of errors breaks down in the transition from closed- to open-shell systems. The higher-order CCSD(T–n) models (orders n > 3) thus offer a consistent and significant improvement in accuracy relative to CCSDT over the CCSD(T) model, equally for RHF, UHF, and ROHF reference determinants, albeit at an increased computational cost.
The main microelements and phosphorus content of sediments formed in a drinking water supply system
Directory of Open Access Journals (Sweden)
Marina Valentukeviciene
2016-11-01
Full Text Available Groundwater is the only source for drinking water supply in Lithuania. Twenty water intakes exploiting Quaternary aquifers are operating in Vilnius City. The main aim of this study was to characterize the heavy metal content of internal pipeline sediments in the water supply network. It also provides a new insight into the accumulation of phosphorus and its variation in pipeline sediments in the study area. The results of this research reflect the level of heavy metals that accumulated during the water supply process. The main microelements detected were lead, nickel, zinc and copper. The research results will be useful for conducting preliminary evaluations of possible microelement accumulation in other similar water supply systems. The evaluation of water supply sediments is considered as one of the most important activities associated with a water safety approach. The results of this research indicate the dependence between phosphorus accumulation and Pb, Cr, Zn, Ni and Cu quantities in the internal sediments of water supply pipelines.
Natural equilibria and anthropic effects on sediment transport in big river systems: The Nile case
Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Vezzoli, Giovanni; Villa, Igor
2014-05-01
knowledge of the Nile sediment system not only has wide paleoclimatic, paleoceanographic and archaeological implications, including a better understanding of Quaternary environmental changes in northern Africa, water circulation and sapropel development in the Mediterranean Sea, and impact on the Egyptian civilization by natural phenomena, but is also strongly needed to mitigate undesirable impacts of human activities on natural equilibria and to improve watershed, reservoir and coastal management. Mineralogical data (Shukri, 1950) integrated by new petrographic, heavy-mineral and geochemical analyses (Padoan et al., 2011) show how sediments derived from Archean gneisses exposed through northern Uganda and from Panafrican basements drained by Ethiopian tributaries of River Sobat become progressively enriched in quartz at the expense of unstable components across the Sudd and Machar Marshes (grey shaded area). Petrographic, mineralogical, and isotopic signatures are gradually homogenized along both the Bahr el Jebel/Bahr ez Zeraf and the Sobat and remain finally unchanged down to Khartoum, which suggests massive sediment dumping in the marshes. This explains why White Nile sediment contribution to the main Nile downstream Khartoum is virtually negligible (Garzanti et al., 2006). Garzanti, E., Andò, S., Vezzoli, G., Abdel Megid, A.A., El Kammar, A., 2006. Petrology of Nile River sands (Ethiopian and Sudan): sediment budgets and erosion patterns. Earth Planet. Sci. Lett., 252, 327-341. Padoan, M., Garzanti, E., Harlavan, Y., Villa, I.M., 2011. Tracing Nile sediment sources by Sr and Nd isotope signatures (Uganda, Ethiopia, Sudan). Geochim. Cosmochim. Acta, 75, 3627-3644. Said, R., 1993. The River Nile, Oxford, Pergamon, 1993, 320 p. Shukri, N.M., 1950. The mineralogy of some Nile sediments. Quart. J. Geol. Soc. London, 105, 511-534. Williams, M.A.J., Faure, H., 1980. The Sahara and the Nile. Balkema, Rotterdam. Woodward, J.C., Macklin, M.G., Krom, M.D., Williams, M.A.J., 2007
Hamers, Adrian S.
2018-05-01
We extend the formalism of a previous paper to include the effects of flybys and instantaneous perturbations such as supernovae on the long-term secular evolution of hierarchical multiple systems with an arbitrary number of bodies and hierarchy, provided that the system is composed of nested binary orbits. To model secular encounters, we expand the Hamiltonian in terms of the ratio of the separation of the perturber with respect to the barycentre of the multiple system, to the separation of the widest orbit. Subsequently, we integrate over the perturber orbit numerically or analytically. We verify our method for secular encounters and illustrate it with an example. Furthermore, we describe a method to compute instantaneous orbital changes to multiple systems, such as asymmetric supernovae and impulsive encounters. The secular code, with implementation of the extensions described in this paper, is publicly available within AMUSE, and we provide a number of simple example scripts to illustrate its usage for secular and impulsive encounters and asymmetric supernovae. The extensions presented in this paper are a next step towards efficiently modelling the evolution of complex multiple systems embedded in star clusters.
International Nuclear Information System (INIS)
Brandow, B.H.
1977-01-01
The Brueckner--Goldstone form of linked-cluster perturbation theory is derived, together with its open-shell analog, by an elementary time-independent approach. This serves to focus attention on the physical interpretation of the results. The open-shell expansion is used to provide a straightforward justification for the effective π-electron Hamiltonians of planar organic molecules
The boundary structure in the analysis of reversibly interacting systems by sedimentation velocity.
Zhao, Huaying; Balbo, Andrea; Brown, Patrick H; Schuck, Peter
2011-05-01
Sedimentation velocity (SV) experiments of heterogeneous interacting systems exhibit characteristic boundary structures that can usually be very easily recognized and quantified. For slowly interacting systems, the boundaries represent concentrations of macromolecular species sedimenting at different rates, and they can be interpreted directly with population models based solely on the mass action law. For fast reactions, migration and chemical reactions are coupled, and different, but equally easily discernable boundary structures appear. However, these features have not been commonly utilized for data analysis, for the lack of an intuitive and computationally simple model. The recently introduced effective particle theory (EPT) provides a suitable framework. Here, we review the motivation and theoretical basis of EPT, and explore practical aspects for its application. We introduce an EPT-based design tool for SV experiments of heterogeneous interactions in the software SEDPHAT. As a practical tool for the first step of data analysis, we describe how the boundary resolution of the sedimentation coefficient distribution c(s) can be further improved with a Bayesian adjustment of maximum entropy regularization to the case of heterogeneous interactions between molecules that have been previously studied separately. This can facilitate extracting the characteristic boundary features by integration of c(s). In a second step, these are assembled into isotherms as a function of total loading concentrations and fitted with EPT. Methods for addressing concentration errors in isotherms are discussed. Finally, in an experimental model system of alpha-chymotrypsin interacting with soybean trypsin inhibitor, we show that EPT provides an excellent description of the experimental sedimentation boundary structure of fast interacting systems. Published by Elsevier Inc.
Rufino, Marta M.; Baptista, Paulo; Pereira, Fábio; Gaspar, Miguel B.
2018-01-01
In the current work we propose a new method to sample surface sediment during bivalve fishing surveys. Fishing institutes all around the word carry out regular surveys with the aim of monitoring the stocks of commercial species. These surveys comprise often more than one hundred of sampling stations and cover large geographical areas. Although superficial sediment grain sizes are among the main drivers of benthic communities and provide crucial information for studies on coastal dynamics, overall there is a strong lack of this type of data, possibly, because traditional surface sediment sampling methods use grabs, that require considerable time and effort to be carried out on regular basis or on large areas. In face of these aspects, we developed an easy and un-expensive method to sample superficial sediments, during bivalve fisheries monitoring surveys, without increasing survey time or human resources. The method was successfully evaluated and validated during a typical bivalve survey carried out on the Northwest coast of Portugal, confirming that it had any interference with the survey objectives. Furthermore, the method was validated by collecting samples using a traditional Van Veen grabs (traditional method), which showed a similar grain size composition to the ones collected by the new method, on the same localities. We recommend that the procedure is implemented on regular bivalve fishing surveys, together with an image analysis system to analyse the collected samples. The new method will provide substantial quantity of data on surface sediment in coastal areas, using a non-expensive and efficient manner, with a high potential application in different fields of research.
Achete, Fernanda; Van der Wegen, Mick; Roelvink, Jan Adriaan; Jaffe, Bruce E.
2017-01-01
Suspended sediment concentration is an important estuarine health indicator. Estuarine ecosystems rely on the maintenance of habitat conditions, which are changing due to direct human impact and climate change. This study aims to evaluate the impact of climate change relative to engineering measures on estuarine fine sediment dynamics and sediment budgets. We use the highly engineered San Francisco Bay-Delta system as a case study. We apply a process-based modeling approach (Delft3D-FM) to assess the changes in hydrodynamics and sediment dynamics resulting from climate change and engineering scenarios. The scenarios consider a direct human impact (shift in water pumping location), climate change (sea level rise and suspended sediment concentration decrease), and abrupt disasters (island flooding, possibly as the results of an earthquake). Levee failure has the largest impact on the hydrodynamics of the system. Reduction in sediment input from the watershed has the greatest impact on turbidity levels, which are key to primary production and define habitat conditions for endemic species. Sea level rise leads to more sediment suspension and a net sediment export if little room for accommodation is left in the system due to continuous engineering works. Mitigation measures like levee reinforcement are effective for addressing direct human impacts, but less effective for a persistent, widespread, and increasing threat like sea level rise. Progressive adaptive mitigation measures to the changes in sediment and flow dynamics resulting from sea level rise may be a more effective strategy. Our approach shows that a validated process-based model is a useful tool to address long-term (decades to centuries) changes in sediment dynamics in highly engineered estuarine systems. In addition, our modeling approach provides a useful basis for long-term, process-based studies addressing ecosystem dynamics and health.
Daniel Bowker; Jeff Stringer; Chris Barton; Songlin Fei
2011-01-01
Sediment mobilized by forest harvest machine traffic contributes substantially to the degradation of headwater stream systems. This study monitored forest harvest machine traffic to analyze how it affects sediment delivery to stream channels. Harvest machines were outfitted with global positioning system (GPS) dataloggers, recording machine movements and working status...
Buruaem, Lucas Moreira; de Castro, Ítalo Braga; Hortellani, Marcos Antonio; Taniguchi, Satie; Fillmann, Gilberto; Sasaki, Silvio Tarou; Varella Petti, Mônica Angélica; Sarkis, Jorge Eduardo de Souza; Bícego, Márcia Caruso; Maranho, Luciane Alves; Davanso, Marcela Bergo; Nonato, Edmundo Ferraz; Cesar, Augusto; Costa-Lotufo, Leticia Veras; Abessa, Denis Moledo de Souza
2013-09-01
Santos-São Vicente Estuarine System is a highly populated coastal zone in Brazil and where it is located the major port of Latin America. Historically, port activities, industrial and domestic effluents discharges have constituted the main sources of contaminants to estuarine system. This study aimed to assess the recent status of sediment quality from 5 zones of Port of Santos by applying a lines-of-evidence approach through integrating results of: (1) acute toxicity of whole sediment and chronic toxicity of liquid phases; (2) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes and butyltins; (3) benthic community descriptors. Results revealed a gradient of increasing contamination for metals and organic compounds, alongside with their geochemical carriers. Sediment liquid phases were more toxic compared to whole sediment. Low number of species and individuals indicated the impoverishment of benthic community. The use of site-specific sediment quality guidelines was more appropriate to predict sediment toxicity. The integration of results through Sediment Quality Triad approach and principal component analysis allowed observing the effects of natural stressors and dredging on sediment quality and benthic distribution. Even with recent governmental efforts to control, pollution is still relevant in Port of Santos and a threat to local ecosystems.
Salles, Tristan; Ding, Xuesong; Webster, Jody M; Vila-Concejo, Ana; Brocard, Gilles; Pall, Jodie
2018-03-27
Understanding the effects of climatic variability on sediment dynamics is hindered by limited ability of current models to simulate long-term evolution of sediment transfer from source to sink and associated morphological changes. We present a new approach based on a reduced-complexity model which computes over geological time: sediment transport from landmasses to coasts, reworking of marine sediments by longshore currents, and development of coral reef systems. Our framework links together the main sedimentary processes driving mixed siliciclastic-carbonate system dynamics. It offers a methodology for objective and quantitative sediment fate estimations over regional and millennial time-scales. A simulation of the Holocene evolution of the Great Barrier Reef shows: (1) how high sediment loads from catchments erosion prevented coral growth during the early transgression phase and favoured sediment gravity-flows in the deepest parts of the northern region basin floor (prior to 8 ka before present (BP)); (2) how the fine balance between climate, sea-level, and margin physiography enabled coral reefs to thrive under limited shelf sedimentation rates after ~6 ka BP; and, (3) how since 3 ka BP, with the decrease of accommodation space, reduced of vertical growth led to the lateral extension of reefs consistent with available observational data.
Terminal zone glacial sediment transfer at a temperate overdeepened glacier system
Swift, D. A.; Cook, S. J.; Graham, D. J.; Midgley, N. G.; Fallick, A. E.; Storrar, R.; Toubes Rodrigo, M.; Evans, D. J. A.
2018-01-01
Continuity of sediment transfer through glacial systems is essential to maintain subglacial bedrock erosion, yet transfer at temperate glaciers with overdeepened beds, where subglacial fluvial sediment transport should be greatly limited by adverse slopes, remains poorly understood. Complex multiple transfer processes in temperate overdeepened systems has been indicated by the presence of large frontal moraine systems, supraglacial debris of mixed transport origin, thick basal ice sequences, and englacial thrusts and eskers. At Svínafellsjökull, thrusts comprising decimetre-thick debris-rich bands of stratified facies ice of basal origin, with a coarser size distribution and higher clast content than that observed in basal ice layers, contribute substantially to the transfer of subglacial material in the terminal zone. Entrainment and transfer of material occurs by simple shear along the upper surface of bands and by strain-induced deformation of stratified and firnified glacier ice below. Thrust material includes rounded and well-rounded clasts that are also striated, indicating that fluvial bedload is deposited as subglacial channels approach the overdeepening and then entrained along thrusts. Substantial transfer also occurs within basal ice, with facies type and debris content dependent on the hydrological connectedness of the adverse slope. A process model of transfer at glaciers with terminal overdeepenings is proposed, in which the geometry of the overdeepening influences spatial patterns of ice deformation, hydrology, and basal ice formation. We conclude that the significance of thrusting in maintaining sediment transfer continuity has likely been overlooked by glacier sediment budgets and glacial landscape evolution studies.
Sheela, A M; Letha, J; Joseph, Sabu; Thomas, Jobin
2013-04-01
Texture plays an important role in the identification of polluted stretch in a lake system. The organic matter as well as toxic elements get accumulated in the finer sediments. The aim of the work is to show the spatio-temporal distribution of texture of the lake sediment (Akkulam-Veli lake, Kerala) and to identify the hot spot areas of contamination. Hot spot areas vary with seasons. During PRM, (premonsoon), the upstream portion of the Akkulam lake is the hot spot. During MON (monsoon), the downstream portion of the Akkulam lake and the upstream portion of the Veli lake are the hot spots. During POM (postmonsoon), hot spot area is the downstream portion of the Akkulam lake. This methodology can be used for the quick identification of hot spots in water bodies.
Developments in perturbation theory
International Nuclear Information System (INIS)
Greenspan, E.
1976-01-01
Included are sections dealing with perturbation expressions for reactivity, methods for the calculation of perturbed fluxes, integral transport theory formulations for reactivity, generalized perturbation theory, sensitivity and optimization studies, multigroup calculations of bilinear functionals, and solution of inhomogeneous Boltzmann equations with singular operators
Cruz, Anna P. S.; Barbosa, Catia F.; Ayres-Neto, Arthur; Munayco, Pablo; Scorzelli, Rosa B.; Amorim, Nívea Santos; Albuquerque, Ana L. S.; Seoane, José C. S.
2018-02-01
In order to investigate the chemical and magnetic characteristics of sediments of the western boundary upwelling system of Southwest Atlantic we analyzed magnetic susceptibility, grain size distribution, total organic carbon, heavy mineral abundance, Fe associated with Mössbauer spectra, and Fe and Mn of pore water to evaluate the deposition patterns of sediments. Four box-cores were collected along a cross-shelf transect. Brazil Current and coastal plume exert a primary control at the inner and outer shelf cores, which exhibited similar depositional patterns characterized by a high abundance of heavy minerals (mean 0.21% and 0.08%, respectively) and very fine sand, whereas middle shelf cores presented low abundances of heavy minerals (mean 0.03%) and medium silt. The inner shelf was dominated by sub-angular grains, while in middle and outer shelf cores well-rounded grains were found. The increasing Fe3+:Fe2+ ratio from the inner to the outer shelf reflects farther distance to the sediment source. The outer shelf presented well-rounded minerals, indicating abrasive processes as a result of transport by the Brazil Current from the source areas. In the middle shelf, cold-water intrusion of the South Atlantic Central Water contributes to the primary productivity, resulting in higher deposition of fine sediment and organic carbon accumulation. The high input of organic carbon and the decreased grain size are indicative of changes in the hydrodynamics and primary productivity fueled by the western boundary upwelling system, which promotes loss of magnetization due to the induction of diagenesis of iron oxide minerals.
Application of linear and higher perturbation theory in reactor physics
International Nuclear Information System (INIS)
Woerner, D.
1978-01-01
For small perturbations in the material composition of a reactor according to the first approximation of perturbation theory the eigenvalue perturbation is proportional to the perturbation of the system. This assumption is true for the neutron flux not influenced by the perturbance. The two-dimensional code LINESTO developed for such problems in this paper on the basis of diffusion theory determines the relative change of the multiplication constant. For perturbations varying the neutron flux in the space of energy and position the eigenvalue perturbation is also influenced by this changed neutron flux. In such cases linear perturbation theory yields larger errors. Starting from the methods of calculus of variations there is additionally developed in this paper a perturbation method of calculation permitting in a quick and simple manner to assess the influence of flux perturbation on the eigenvalue perturbation. While the source of perturbations is evaluated in isotropic approximation of diffusion theory the associated inhomogeneous equation may be used to determine the flux perturbation by means of diffusion or transport theory. Possibilities of application and limitations of this method are studied in further systematic investigations on local perturbations. It is shown that with the integrated code system developed in this paper a number of local perturbations may be checked requiring little computing time. With it flux perturbations in first approximation and perturbations of the multiplication constant in second approximation can be evaluated. (orig./RW) [de
Bayesian analysis for erosion modelling of sediments in combined sewer systems.
Kanso, A; Chebbo, G; Tassin, B
2005-01-01
Previous research has confirmed that the sediments at the bed of combined sewer systems are the main source of particulate and organic pollution during rain events contributing to combined sewer overflows. However, existing urban stormwater models utilize inappropriate sediment transport formulas initially developed from alluvial hydrodynamics. Recently, a model has been formulated and profoundly assessed based on laboratory experiments to simulate the erosion of sediments in sewer pipes taking into account the increase in strength with depth in the weak layer of deposits. In order to objectively evaluate this model, this paper presents a Bayesian analysis of the model using field data collected in sewer pipes in Paris under known hydraulic conditions. The test has been performed using a MCMC sampling method for calibration and uncertainty assessment. Results demonstrate the capacity of the model to reproduce erosion as a direct response to the increase in bed shear stress. This is due to the model description of the erosional strength in the deposits and to the shape of the measured bed shear stress. However, large uncertainties in some of the model parameters suggest that the model could be over-parameterised and necessitates a large amount of informative data for its calibration.
Directory of Open Access Journals (Sweden)
Tina Treude
2017-04-01
Full Text Available The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ13C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO42-m-2 day-1 in untreated cores to 5.7 mmol SO42-m-2 day-1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2–C6 n-alkanes passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n-alkanes (C10–C38 decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (
Mishra, Sonakshi; Wefers, Peggy; Schmidt, Mark; Knittel, Katrin; Krüger, Martin; Stagars, Marion H; Treude, Tina
2017-01-01
The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ 13 C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO 4 2- m -2 day -1 in untreated cores to 5.7 mmol SO 4 2- m -2 day -1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2-C6 n -alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n -alkanes (C10-C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core.
Tracking the 10Be-26Al source-area signal in sediment-routing systems of arid central Australia
Struck, Martin; Jansen, John D.; Fujioka, Toshiyuki; Codilean, Alexandru T.; Fink, David; Fülöp, Réka-Hajnalka; Wilcken, Klaus M.; Price, David M.; Kotevski, Steven; Fifield, L. Keith; Chappell, John
2018-05-01
Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ˜ 100 000 km2) in central Australia with the aim of tracking downstream variations in 10Be-26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 10Be-26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ˜ 6-11 m Myr-1 and silcrete-dominant areas erode as slow as ˜ 0.2 m Myr-1. 10Be-26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ˜ 400-800 kyr and up to ˜ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be-26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i) high sediment supply rates, (ii) high mean runoff, and (iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i) low sediment supply and (ii) juxtaposition of sediment storages with notably different exposure histories.
International Nuclear Information System (INIS)
Ragbirsingh, Y.; Norville, W.
2005-01-01
The Gulf of Paria is a semi-enclosed shallow basin with increasing coastal development activities along Trinidad's west coast. Sediments present a host for trace metal pollutants from overlying waters, therefore determination of their content is critical in evaluating and detecting sources of marine pollution. This paper presents a Geographic Information System (GIS) analysis of geochemical assessment for trace metals in coastal sediments of the Gulf of Paria. This GIS approach facilitates interpretation of the spatial relationships among key environmental processes. The GIS development involves the integration of spatial and attribute data pertaining to bathymetry, current systems, topography, rivers, land use/land cover and coastal sediments. It employs spatial interpolation and retrieval operations to analyze the total trace metal concentrations of aluminum, copper and lead in the sediments and the clay-enriched sediments, to determine whether they are related to sediment type or are affected by the discharge from anthropogenic sources. Spatial distribution modeling of element concentrations are produced to indicate contamination plumes from possible anthropogenic sources such as rivers entering the Gulf of Paria, and to reveal potential hot spots and dispersion patterns. A direct spatial correlation between clay-enriched sediments and high concentrations of aluminum and lead is detected, however regions of high concentrations of copper and lead indicate a relationship to anthropogenic sources. The effectiveness of GIS for visualization, spatial query and overlay of geochemical analysis is demonstrated [es
McGann, Mary; Erikson, Li H.; Wan, Elmira; Powell, Charles; Maddocks, Rosalie F.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.
2013-01-01
Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes. The biota will be spatially distributed according to its response to environmental parameters such as water temperature, salinity, dissolved oxygen, organic carbon content, grain size, and intensity of currents and tidal flow, whereas the presence of anthropogenic and volcanic constituents will reflect proximity to source areas and whether they are fluvially- or aerially-transported. Because each of these constituents have a unique environmental signature, they are a more precise proxy for that source area than the conventional sedimentary process indicators. This San Francisco Bay Coastal System study demonstrates that by applying a multi-proxy approach, the primary sites of sediment transport can be identified. Many of these sites are far from where the constituents originated, showing that sediment transport is widespread in the region. Although not often used, identifying and interpreting the distribution of naturally-occurring and allochthonous biologic, anthropogenic, and volcanic sediment constituents is a powerful tool to aid in the investigation of sediment transport pathways in other coastal systems.
Energy Technology Data Exchange (ETDEWEB)
Jimenez, B.; Mendez, J.M.; Barrios, J.A.; Salgado, G.; Sheinbaum, C.
2003-07-01
Combined sewer systems generate sediments that have characteristics similar to those of primary sludge. Mexico City has such a system composed of a network of pipes, regulation structures (dams, basins) and open channels. The annual generation of sediments is estimated in 2.8 Mm{sup 3}, which includes 0.41 Mm{sup 3} of sludge. As a result, the total capacity for transporting water is reduced considerably, making necessary to extract yearly an approximate 0.85 Mm{sup 3} of those materials and to send them to a final disposal site with a capacity that is being exhausted. As part of the local Governmental effort, this project evaluates the quality of sediments from 6 dams, 4 regulation basins, 2 open channels, and 3 transfer stations. Also, sludge from 20 wastewater treatment plants was sampled. The results showed an important presence of lead and hydrocarbons in some sediments, and some sludge samples contained arsenic and nickel above the limits. Moreover, microbial levels exceeded the limits in all the sediments and sludge samples. Erosion was linked to the generation of an important amount of sediments based on lead concentration. A classification was established to determine the degree of contamination of the sediments as well as the required treatment to allow their potential reuse. (author)
Wang, N.; Besser, J.M.; Buckler, D.R.; Honegger, J.L.; Ingersoll, C.G.; Johnson, B. Thomas; Kurtzweil, M.L.; MacGregor, J.; McKee, M.J.
2005-01-01
The fate and toxicity of a polyethoxylated tallowamine (POEA) surfactant system, MON 0818, was evaluated in water–sediment microcosms during a 4-d laboratory study. A surfactant solution of 8 mg l−1 nominal concentration was added to each of nine 72-l aquaria with or without a 3-cm layer of one of two natural sediments (total organic carbon (TOC) 1.5% or 3.0%). Control well water was added to each of nine additional 72-l aquaria with or without sediment. Water samples were collected from the microcosms after 2, 6, 24, 48, 72, and 96 h of aging to conduct 48-h toxicity tests with Daphnia magna and to determine surfactant concentrations. Elevated mortality of D. magna (43–83%) was observed in overlying water sampled from water-only microcosms throughout the 96-h aging period, whereas elevated mortality (23–97%) was only observed in overlying water sampled from water–sediment microcosms during the first 24 h of aging. Measured concentrations of MON 0818 in water-only microcosms remained relatively constant (4–6 mg l−1) during the 96-h period, whereas the concentrations in overlying water from microcosms containing either of the two types of sediment dissipated rapidly, with half-lives of 13 h in the 3.0% TOC sediment and 18 h in the 1.5% TOC sediment. Both toxicity and the concentration of MON 0818 in overlying water decreased more rapidly in microcosms containing sediment with the higher percent TOC and clay and with a higher microbial biomass. Mortality of D. magna was significantly correlated with surfactant concentrations in the overlying water. These results indicate that the toxicity of the POEA surfactant in water rapidly declines in the presence of sediment due to a reduction in the surfactant concentration in the overlying water above the sediment.
DEFF Research Database (Denmark)
Sim, Anna K.; Thomsen, Kristina Jørkov; Murray, K.J.
2014-01-01
Two fluvial sediment cores taken from a floodplain of the Hawkesbury-Nepean River system in the Sydney region, eastern Australia are dated using Optically Stimulated Luminescence (OSL) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14C...... in an average apparent age overestimation of ~200 years, which is significant for these samples, but negligible for sediments older than a few thousand years. The intention is that the chronology obtained in this study will be used in conjunction with a proxy flood record, derived from floodplain sediments...
Autonomous bed-sediment imaging-systems for revealing temporal variability of grain size
Buscombe, Daniel; Rubin, David M.; Lacy, Jessica R.; Storlazzi, Curt D.; Hatcher, Gerald; Chezar, Henry; Wyland, Robert; Sherwood, Christopher R.
2014-01-01
We describe a remotely operated video microscope system, designed to provide high-resolution images of seabed sediments. Two versions were developed, which differ in how they raise the camera from the seabed. The first used hydraulics and the second used the energy associated with wave orbital motion. Images were analyzed using automated frequency-domain methods, which following a rigorous partially supervised quality control procedure, yielded estimates to within 20% of the true size as determined by on-screen manual measurements of grains. Long-term grain-size variability at a sandy inner shelf site offshore of Santa Cruz, California, USA, was investigated using the hydraulic system. Eighteen months of high frequency (min to h), high-resolution (μm) images were collected, and grain size distributions compiled. The data constitutes the longest known high-frequency record of seabed-grain size at this sample frequency, at any location. Short-term grain-size variability of sand in an energetic surf zone at Praa Sands, Cornwall, UK was investigated using the ‘wave-powered’ system. The data are the first high-frequency record of grain size at a single location of a highly mobile and evolving bed in a natural surf zone. Using this technology, it is now possible to measure bed-sediment-grain size at a time-scale comparable with flow conditions. Results suggest models of sediment transport at sandy, wave-dominated, nearshore locations should allow for substantial changes in grain-size distribution over time-scales as short as a few hours.
Li, Shu; Huang, Zheng; Wang, Yi; Liu, Yu-Qing; Luo, Ran; Shang, Jing-Ge; Liao, Qian-Jia-Hua
2018-02-01
In this study, the migration of antibiotics (norfloxacin, NOR; and sulfamethoxazole, SMX) under simulated resuspension conditions across the sediment-water interface were quantified for two locations in China: point A, located in Meiliang Bay of Lake Taihu, and point B, located in Dapukou of Lake Taihu. The concentrations of suspended solids (SS) in the overlying water amounted to 100, 500, and 1000 mg/L during background, moderate, and strong simulated wind-wave disturbances, respectively. At each SS level, the initial concentrations of the two antibiotics were set to 1, 5, and 10 mg/L. The results showed that both resuspended SS and the initial concentration of antibiotics could influence the migration of NOR in the water-sediment system. Specifically, both higher SS and initial antibiotic concentrations were associated with higher rates of migration and accumulation of NOR from water to sediment. In contrast, the migration of SMX in the water-sediment system was not impacted by SS or initial antibiotic concentration. The adsorption capacities of sediments for NOR and SMX were significantly different at both locations, possibly reflecting differences in cation exchange capacity (CEC) and organic material (OM) contents. In general, higher CEC and OM values were found in sediments with a higher adsorption capacity for the antibiotics. When CEC and OM values of sediments were higher, the adsorption capacity reached up to 51.73 mg/kg. Large differences in the migration from water to sediment were observed for the two antibiotics, with NOR migration rates higher than those of SMX. The accumulation of NOR in surface sediment during resuspension was about 14 times higher than that of SMX. The main reason for this is that the chemical adsorption of NOR is seldom reversible. Overall, this study demonstrates that resuspension of NOR and SMX attached to sediments under simulated wind-wave disturbances can promote the migration of the antibiotics from water to sediment
Sediment transport in the San Francisco Bay Coastal System: An overview
Barnard, Patrick L.; Schoellhamer, David H.; Jaffe, Bruce E.; Lester J. McKee,
2013-01-01
The papers in this special issue feature state-of-the-art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal-estuarine systems. Here we focus on the San Francisco Bay Coastal System, extending from the lower San Joaquin-Sacramento Delta, through the Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~ 8 x 109 m3/day, in addition to the transport of mud, sand, biogenic material, nutrients, and pollutants. Despite this physical, biological and chemical connection, resource management and prior research have often treated the Delta, Bay and adjacent ocean as separate entities, compartmentalized by artificial geographic or political boundaries. The body of work herein presents a comprehensive analysis of system-wide behavior, extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining-impact research of G.K. Gilbert in the early 20th century.
Lawton, T. F.; Molina-Garza, R. S.; Barboza-Gudiño, R.; Rogers, R. D.
2013-05-01
Major sediment dispersal systems on western Pangea evolved in concert with thermal uplift, rift and drift phases of the Gulf of Mexico Basin, and were influenced by development of a continental arc on Pangea's western margin. Existing literature and preliminary data from fieldwork, sandstone petrology and detrital zircon analysis reveal how major drainages in Mexico changed from Late Triassic through Late Jurassic time and offer predictions for the ultimate destinations of sand-rich detritus along the Gulf and paleo-Pacific margins. Late Triassic rivers drained away from and across the present site of the Gulf of Mexico, which was then the location of a major thermal dome, the Texas uplift of recent literature. These high-discharge rivers with relatively mature sediment composition fed a large-volume submarine fan system on the paleo-Pacific continental margin of Mexico. Predictably, detrital zircon age populations are diverse and record sources as far away as the Amazonian craton. This enormous fluvial system was cut off abruptly near the Triassic-Jurassic boundary by extensive reorganization of continental drainages. Early and Middle Jurassic drainage systems had local headwaters and deposited sediment in extensional basins associated with arc magmatism. Redbeds accumulated across northern and eastern Mexico and Chiapas in long, narrow basins whose locations and dimensions are recorded primarily by inverted antiformal massifs. The Jurassic continental successions overlie Upper Triassic strata and local subvolcanic plutons; they contain interbedded volcanic rocks and thus have been interpreted as part of the Nazas continental-margin arc. The detritus of these fluvial systems is volcanic-lithic; syndepositional grain ages are common in the detrital zircon populations, which are mixed with Oaxaquia-derived Permo-Triassic and Grenville age populations. By this time, interior Pangea no longer supplied sediment to the paleo-Pacific margin, possibly because the
Water and sediment analysis of touristic places in Guarapuava, PR using a portable EDXRF system
International Nuclear Information System (INIS)
Antunes Junior, Osmar R.; Biasi, Gabriel E.V.; Melquiades, Fabio L.; Lopes, Fabio; Appoloni, Carlos R.
2009-01-01
The use of the Energy Dispersive X Ray Fluorescence (EDXRF) have increasingly been applied for in situ trace metal analysis in different kinds of samples. Results of a monitoring sampling, in the winter and summer of 2008, respectively, from 6 touristic places in Guarapuava, PR city are presented. The work consisted on the use of a portable EDXRF system constituted by a X-ray tube to excite the samples, a Si-Pin detector, a holder for the excitation-detection system and samples positioning, with the standard data acquisition electronics to register the spectra. The water samples were filtered in membranes for suspended particulate matter retention. After this, APDC precipitation methodology was applied for sample preconcentration with posterior filtering in membranes. So, the dissolved and non dissolved metal fractions were determined separately. Sediment samples were dried at 60 C for 24h and sieved through 60 mesh. Micromatter standards were used for sensitivity determination for membranes samples. For sediments 5 multi-element standards were used and calibration curves were constructed. For water membrane measurements, Fe concentration was quantified from 0.026±0.004 to 5.1±1.0, in mg L -1 . For sediments, considering all the sampling locations, Mn, Cu, Sr, Y and Nb were identified qualitatively, and it was possible to quantify the following range of elements and concentrations, mg Kg -1 : Ca (1977 - 10162), Ti (12494 - 22320), Fe (36972 - 88452), Zn (73 - 185) and Zr (158 - 960). The performance of the equipment was very good and the results are quite satisfactory for portable equipment. (author)
Perturbative treatment of nuclear rotations
International Nuclear Information System (INIS)
Civitarese, O.
1980-01-01
In this work, it is described the case corresponding to perturbative quantum treatment of a fermion system in free rotation and the divergences which resulted from the 'break' in symmetry, associated by the adoption of a deformed basis as a non pertubed solution. (A.C.A.S.) [pt
Directory of Open Access Journals (Sweden)
Sirada Pinjai
2013-01-01
Full Text Available This paper is concerned with the problem of robust exponential stability for linear parameter-dependent (LPD neutral systems with mixed time-varying delays and nonlinear perturbations. Based on a new parameter-dependent Lyapunov-Krasovskii functional, Leibniz-Newton formula, decomposition technique of coefficient matrix, free-weighting matrices, Cauchy’s inequality, modified version of Jensen’s inequality, model transformation, and linear matrix inequality technique, new delay-dependent robust exponential stability criteria are established in terms of linear matrix inequalities (LMIs. Numerical examples are given to show the effectiveness and less conservativeness of the proposed methods.
Perturbation methods for power and reactivity reconstruction
International Nuclear Information System (INIS)
Palmiotti, G.; Salvatores, M.; Estiot, J.C.; Broccoli, U.; Bruna, G.; Gomit, J.M.
1987-01-01
This paper deals with recent developments and applications in perturbation methods. Two types of methods are used. The first one is an explicit method, which allows the explicit reconstruction of a perturbed flux using a linear combination of a library of functions. In our application, these functions are the harmonics (i.e. the high order eigenfunctions of the system). The second type is based on the Generalized Perturbation Theory GPT and needs the calculation of an importance function for each integral parameter of interest. Recent developments of a particularly useful high order formulation allows to obtain satisfactory results also for very large perturbations
Geomorphic Approach to Regional Sediment Management in Engineered and Restored Fluvial Systems
National Research Council Canada - National Science Library
Thorne, Colin
2001-01-01
This document reviews contemporary practice in regional sediment management. It examines whether catchment wide sediment issues have been considered in the design of engineering and restoration/rehabilitation projects...
Base case and perturbation scenarios
Energy Technology Data Exchange (ETDEWEB)
Edmunds, T
1998-10-01
quantitative scoring system for issue areas were applied under the base case, a tractable quantitative decision model incorporating scenarios and their likelihoods could be developed and appli& in the decision process. LLNL has developed four perturbation scenarios that address the following issues: l} low economic growth, 2) high natural gas prices, 3) dysfunctional markets, and 4) a preference for green power. We have proposed a plausible scenario that addresses each issue for discussion and consideration by the CEC. In addition, we have provided an example application of the four perturbation scenarios in a qualitative framework for evaluation of issue areas developed for the PIEPC program. A description of each of the perturbation scenarios and a discussion of how they could effect decisions about today' s R&D funding is included. The scenarios attempt to cover a broad spectrum of plausible outcomes in a deregulated market environment. Nowever, Vhey are not a comprehensive and rigorously defined list of the most probable scenarios, but rather a qualitative inference based upon knowledge and expertise in the energy field.
Aidarkhanova, A K; Lukashenko, S N; Larionova, N V; Polevik, V V
2018-04-01
This paper provides research data on levels and character of radionuclide contamination distribution in the «sediments- water - plants » system of objects of the Semipalatinsk test site (STS). As the research objects there were chosen water bodies of man-made origin which located at the territory of "Experimental Field", "Balapan", "Telkem" and "Sary-Uzen" testing sites. For research the sampling of bottom sediments, water, lakeside and water plants was taken. Collected samples were used to determine concentration of anthropogenic radionuclides 90 Sr, 239+240 Pu, 241 Am, 137 Cs. The distribution coefficient (K d ) was calculated as the ratio of the content of radionuclides in the sediments to the content in water, and the concentration ratio (F V ) was calculated as the ratio of radionuclide content in plants to the content in sediments or soil. Copyright © 2018 Elsevier Ltd. All rights reserved.
Zhao, Xiao; Liu, Wen; Fu, Jie; Cai, Zhengqing; O'Reilly, S E; Zhao, Dongye
2016-08-15
This work examined effects of model oil dispersants on dispersion, sorption and photodegradation of petroleum hydrocarbons in simulated marine systems. Three dispersants (Corexit 9500A, Corexit 9527A and SPC 1000) were used to prepare dispersed water accommodated oil (DWAO). While higher doses of dispersants dispersed more n-alkanes and PAHs, Corexit 9500A preferentially dispersed C11-C20 n-alkanes, whereas Corexit 9527A was more favorable for smaller alkanes (C10-C16), and SPC 1000 for C12-C28 n-alkanes. Sorption of petroleum hydrocarbons on sediment was proportional to TPH types/fractions in the DWAOs. Addition of 18mg/L of Corexit 9500A increased sediment uptake of 2-3 ring PAHs, while higher dispersant doses reduced the uptake, due to micelle-enhanced solubilization effects. Both dispersed n-alkanes and PAHs were susceptible to photodegradation under simulated sunlight. For PAHs, both photodegradation and photo-facilitated alkylation were concurrently taking place. The information can facilitate sounder assessment of fate and distribution of dispersed oil hydrocarbons in marine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.
Catianis, Irina; Secrieru, Dan; Pojar, Iulian; Grosu, Dumitru; Scrieciu, Albert; Pavel, Ana Bianca; Vasiliu, Dan
2018-03-01
Razim Lake is the biggest of Romania's freshwater lakes and along with other basins as Golovita, Zmeica and Sinoie constitutes a system of great ecological significance, playing also an essential role in the supply of water for irrigation, fishery exploitation, farming, flood prevention, recreational navigation and water tourism. Due to their importance, the environmental conditions in the Razim - Sinoie coastal lakes have attracted an increased public attention in contemporary society. To assess the levels, dissemination and potential sources of contamination in the above-mentioned lagoon system, random sampling was used to collect water and sediment samples from every lake and several analytical techniques were performed to investigate their environmental characteristics. The results obtained from this study indicated that, in water, concentrations of various physico-chemical parameters are, mostly, in agreement with correlated environmental standards. Slight variations and/or occasional exceeding of the maximum admissible limits were generally limited to small areas showing levels that would not warrant special concern. In sediments, the mean concentrations of some specific trace metals were below the levels of potential effect. Benthic samples revealed 31 taxa belonging to 16 zoo-benthal subdivisions. The results of this study showed good ecological status despite local several natural and anthropogenic stressors as fishery exploitation, farming, recreational navigation and water tourism.
Adsorption - desorption equilibria of some radionuclides in sediment - sea water system
International Nuclear Information System (INIS)
El-Assy, N.B.; Fattah, A.T.A.; El-Shinawy, R.M.K.; Essa, M.W.A.
1991-01-01
Chemical and physical properties of Suez Canal bottom sediments (SCBS) and sea water at port Tawfeek area, the south entrance of Suez canal, have been studied. The SCBS was separated into its size fractions (natural sediment, sand, silt and clay). These different sediment fractions were allowed to be in equilibrium with 89 Sr, 60 Co and 134 Cs solutions. Desorption studies were carried out on these contaminated sediments. (author) 16 refs.; 1 fig.; 1 tab
Tidal and meteorological forcing of sediment transport in tributary mudflat channels.
Ralston, David K; Stacey, Mark T
2007-06-01
Field observations of flow and sediment transport in a tributary channel through intertidal mudflats indicate that suspended sediment was closely linked to advection and dispersion of a tidal salinity front. During calm weather when tidal forcing was dominant, high concentrations of suspended sediment advected up the mudflat channel in the narrow region between salty water from San Francisco Bay and much fresher runoff from the small local watershed. Salinity and suspended sediment dispersed at similar rates through each tidal inundation, such that during receding ebbs the sediment pulse had spread spatially and maximum concentrations had decreased. Net sediment transport was moderately onshore during the calm weather, as asymmetries in stratification due to tidal straining of the salinity front enhanced deposition, particularly during weaker neap tidal forcing. Sediment transport by tidal forcing was periodically altered by winter storms. During storms, strong winds from the south generated wind waves and temporarily increased suspended sediment concentrations. Increased discharge down the tributary channels due to precipitation had more lasting impact on sediment transport, supplying both buoyancy and fine sediment to the system. Net sediment transport depended on the balance between calm weather tidal forcing and perturbations by episodic storms. Net transport in the tributary channel was generally off-shore during storms and during calm weather spring tides, and on-shore during calm weather neap tides.
Ion transport in deep-sea sediments
International Nuclear Information System (INIS)
Heath, G.R.
1979-01-01
Initial assessment of the ability of deep-sea clays to contain nuclear waste is optimistic. Yet, the investigators have no delusions about the complexity of the natural geochemical system and the perturbations that may result from emplacement of thermally-hot waste cannisters. Even though they may never be able to predict the exact nature of all these perturbations, containment of the nuclides by the waste form/cannister system until most of the heat has decayed, and burial of the waste to a sufficient depth that the altered zone can be treated as a black box source of dissolved nuclides to the enclosing unperturbed sediment, encourage them to believe that ion migration in the deep seabed can be modeled accurately and that our preliminary estimates of migration rates are likely to be reasonably realistic
Eriksen, Janus J; Matthews, Devin A; Jørgensen, Poul; Gauss, Jürgen
2016-05-21
We extend our assessment of the potential of perturbative coupled cluster (CC) expansions for a test set of open-shell atoms and organic radicals to the description of quadruple excitations. Namely, the second- through sixth-order models of the recently proposed CCSDT(Q-n) quadruples series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)] are compared to the prominent CCSDT(Q) and ΛCCSDT(Q) models. From a comparison of the models in terms of their recovery of total CC singles, doubles, triples, and quadruples (CCSDTQ) energies, we find that the performance of the CCSDT(Q-n) models is independent of the reference used (unrestricted or restricted (open-shell) Hartree-Fock), in contrast to the CCSDT(Q) and ΛCCSDT(Q) models, for which the accuracy is strongly dependent on the spin of the molecular ground state. By further comparing the ability of the models to recover relative CCSDTQ total atomization energies, the discrepancy between them is found to be even more pronounced, stressing how a balanced description of both closed- and open-shell species-as found in the CCSDT(Q-n) models-is indeed of paramount importance if any perturbative CC model is to be of chemical relevance for high-accuracy applications. In particular, the third-order CCSDT(Q-3) model is found to offer an encouraging alternative to the existing choices of quadruples models used in modern computational thermochemistry, since the model is still only of moderate cost, albeit markedly more costly than, e.g., the CCSDT(Q) and ΛCCSDT(Q) models.
Conceptualising and mapping coupled estuary, coast and inner shelf sediment systems
French, Jon; Burningham, Helene; Thornhill, Gillian; Whitehouse, Richard; Nicholls, Robert J.
2016-03-01
Whilst understanding and predicting the effects of coastal change are primarily modelling problems, it is essential that we have appropriate conceptual frameworks for (1) the formalisation of existing knowledge; (2) the formulation of relevant scientific questions and management issues; (3) the implementation and deployment of predictive models; and (4) meaningful engagement involvement of stakeholders. Important progress continues to be made on the modelling front, but our conceptual frameworks have not evolved at a similar pace. Accordingly, this paper presents a new approach that re-engages with formal systems analysis and provides a mesoscale geomorphological context within which the coastal management challenges of the 21st century can be more effectively addressed. Coastal and Estuarine System Mapping (CESM) is founded on an ontology of landforms and human interventions that is partly inspired by the coastal tract concept and its temporal hierarchy of sediment sharing systems, but places greater emphasis on a hierarchy of spatial scales. This extends from coastal regions, through landform complexes, to landforms, the morphological adjustment of which is constrained by diverse forms of human intervention. Crucially, CESM integrates open coastal environments with estuaries and relevant portions of the inner shelf that have previously been treated separately. In contrast to the nesting of littoral cells that has hitherto framed shoreline management planning, CESM charts a complex web of interactions, of which a sub-set of mass transfer pathways defines the sediment budget, and a multitude of human interventions constrains natural landform behaviour. Conducted within a geospatial framework, CESM constitutes a form of knowledge formalisation in which disparate sources of information (published research, imagery, mapping, raw data etc.) are generalised into usable knowledge. The resulting system maps provide a framework for the development and application of
Tomilova, I. V.; Bordovitsyna, T. V.
2017-08-01
Results of investigation into the resonant structure of perturbations and long-term orbital evolution of space vehicles of GLONASS and GPS global navigating satellite systems (GNSS) under assumption that all of them have lost control on 08/01/2015 are presented. It is demonstrated that the majority of the examined objects are in the range of action of the secular resonances of various types. In addition, practically all satellites of the GPS system are within the scope of the 2:1 orbital resonance with rotation of the Earth. Results of the MEGNO analysis demonstrate that the motion of all objects of the GLONASS system during the 100-year period is regular, whereas the motion of the majority of objects of the GPS system is subject to chaotization.
International Nuclear Information System (INIS)
Dominicis, C. de
1961-01-01
The grand partition function Z (α,β) of a quantum system is studied, using diagrammatic representations of the perturbation expansion. For a fermions system, it is possible to show, by proper resummation, without approximations but under some 'regularity hypothesis', that Log Z (α,β) takes a form where, besides trivial dependences, α and β only appear through a statistical factor F k - = [1 + e -α+βε k 0 -βW k ] -1 . W k is a (real) self-consistent potential, generalized to all orders and can be defined by a stationary condition on Log Z (α,β) under variations of F k - . The thermodynamical quantities take a form analogous to the expressions Landau introduced for the Fermi liquids. The zero temperature limit (for isotropic systems) gives back Goldstone expressions for the ground state of a system. (author) [fr
International Nuclear Information System (INIS)
Jin, Yusuke; Konno, Yoshihiro; Nagao, Jiro
2014-01-01
A pressurized subsampling system was developed for pressured gas hydrate (GH)-bearing sediments, which have been stored under pressure. The system subsamples small amounts of GH sediments from cores (approximately 50 mm in diameter and 300 mm in height) without pressure release to atmospheric conditions. The maximum size of the subsamples is 12.5 mm in diameter and 20 mm in height. Moreover, our system transfers the subsample into a pressure vessel, and seals the pressure vessel by screwing in a plug under hydraulic pressure conditions. In this study, we demonstrated pressurized subsampling from artificial xenon-hydrate sediments and nondestructive microscale imaging of the subsample, using a microfocus X-ray computed tomography (CT) system. In addition, we estimated porosity and hydrate saturation from two-dimensional X-ray CT images of the subsamples
International Nuclear Information System (INIS)
Collins, J.C.
1985-01-01
Progress in quantum chromodynamics in the past year is reviewed in these specific areas: proof of factorization for hadron-hadron collisions, fast calculation of higher order graphs, perturbative Monte Carlo calculations for hadron-hadron scattering, applicability of perturbative methods to heavy quark production, and understanding of the small-x problem. 22 refs
Long-term impacts due to sediment supply changes towards the San Francisco Bay-Delta system
Achete, F.; Van der Wegen, M. V.; Jaffe, B. E.
2012-12-01
The Sacramento-San Joaquin Delta and Watershed is the main source of fresh water and sediment to San Francisco Bay. Mid 19th century hydraulic mining in the catchment caused an excessive supply of sediment. After mining activities stopped, in the first part of the 20th century several hydraulic structures were built deviating fresh water and trapping sediment upstream. The main purpose of most of these structures is water storage for irrigation and/or water supply Wright and Schoellhamer (2004) show that from 1957 to 2001 the sediment load carried to San Francisco Bay has decreased by about one half. The lack of sediments may lead to a different erosion/deposition pattern in the Bay-Delta system causing problems like mud flat erosion, shift in navigation channel, land subsidence and changing habitat for endemic species. The objective of this work is to identify and quantify morphological shifts in the Bay-Delta system due to variation in fresh water and sediment supply. In this study, we couple the Delta and Bay in a unique model network (the Delta-Bay model). This coupling allows tracking of sediment from Sacramento via the Delta and Bay and through the Golden Gate, making it possible to identify erosion and deposition areas. The numerical model applied is an unstructured, process-based model (D-Flow Flexible Mesh developed by Deltares). It simulates the hydrodynamics and morphodynamics of the area on a detailed, 64000-node mesh (10-200m mesh length scale) on a timescale of minutes. The morphological impact is assessed for multiple scenarios with different input of sediment and fresh water. A statistical analysis is performed to account for uncertainty of model parameters and climate change impacts. The fresh water discharge already has a strong natural seasonal and inter-annual variation. The human impact by foreseen different water pumping strategies due to the peripheral canal will be considered. Jaffe et al. (2007) has shown that substantial morphological
Perturbative and constructive renormalization
International Nuclear Information System (INIS)
Veiga, P.A. Faria da
2000-01-01
These notes are a survey of the material treated in a series of lectures delivered at the X Summer School Jorge Andre Swieca. They are concerned with renormalization in Quantum Field Theories. At the level of perturbation series, we review classical results as Feynman graphs, ultraviolet and infrared divergences of Feynman integrals. Weinberg's theorem and Hepp's theorem, the renormalization group and the Callan-Symanzik equation, the large order behavior and the divergence of most perturbation series. Out of the perturbative regime, as an example of a constructive method, we review Borel summability and point out how it is possible to circumvent the perturbation diseases. These lectures are a preparation for the joint course given by professor V. Rivasseau at the same school, where more sophisticated non-perturbative analytical methods based on rigorous renormalization group techniques are presented, aiming at furthering our understanding about the subject and bringing field theoretical models to a satisfactory mathematical level. (author)
Impact of particles on sediment accumulation in a drinking water distribution system.
Vreeburg, J H G; Schippers, D; Verberk, J Q J C; van Dijk, J C
2008-10-01
Discolouration of drinking water is one of the main reasons customers complain to their water company. Though corrosion of cast iron is often seen as the main source for this problem, the particles originating from the treatment plant play an important and potentially dominant role in the generation of a discolouration risk in drinking water distribution systems. To investigate this thesis a study was performed in a drinking water distribution system. In two similar isolated network areas the effect of particles on discolouration risk was studied with particle counting, the Resuspension Potential Method (RPM) and assessment of the total accumulated sediment. In the 'Control Area', supplied with normal drinking water, the discolouration risk was regenerated within 1.5 year. In the 'Research Area', supplied with particle-free water, this will take 10-15 years. An obvious remedy for controlling the discolouration risk is to improve the treatment with respect to the short peaks that are caused by particle breakthrough.
International Nuclear Information System (INIS)
Zhu Minqiang; Wu Rengui; Yu Dagan; Chen Anping; Shen Kefeng
2003-01-01
Based upon the research of basin fills at the Bayantala basin, the genetic facies of host sediments have been ascertained and the target beds and their range are delineated. The sand bodies of the Upper Member of Tengge'er Formation deposited in fan delta front is favorable to the formation of uranium mineralization of phreatic-interlayer oxidation. The Saihantala Fm deposited in fluvial system can be divided into Lower Member and Upper Member based on depositional microfacies and paleoclimate. The Lower Member of braided system is the most important target bed enriched in organic matter where basal-channel-type uranium mineralization occurs. Features of alteration and mineralization suggest that the early-stage and the late-stage uranium mineralization are related to phreatic oxidation and interlayer oxidation (roll-type) respectively. Meanwhile, the secondary reduction has superimposed over the earlier mineralization in the area caused by hydrocarbons raising along faults
Nitrogen and phosphorus in cascade multi-system tropical reservoirs: water and sediment
Directory of Open Access Journals (Sweden)
Pompêo Marcelo
2017-09-01
Full Text Available The aim of this research was to analyze the horizontal spatial heterogeneity of both water and superficial sediment quality among and within the reservoirs of the Cantareira System (CS, focusing on concentrations of N and P, attributed to the dumping of raw domestic sewage into water bodies, which is the main cause of water pollution in São Paulo State (Brazil. The CS is a multi-system complex composed of five interconnected reservoirs, with water transported by gravity through 48 km of tunnels and channels. From the last reservoir of the CS, with an output of 33 m3 s−1, the water is conducted to a water treatment plant, producing half of the water consumed by 19 million people inhabiting São Paulo city. The upstream reservoirs are more eutrophic than the downstream ones. Data also suggest that the low phytoplankton biomass (ranging from 0.9 to 14.4 μg dm−3 is regulated by the low nutrient availability, mainly of phosphorus (TP ranging from below the detection limit, <9.0 μg dm−3, to 47.3 μg dm−3. For water, the DIN/TP ratios values range from 19 to 380. The upstream reservoirs function as nutrient accumulators and the sediment is the main compartment in which P and N are stored. Although the reservoirs are located in different river basins and are not in sequence along the same river, the results suggest a marked gradient between the reservoirs, with features similar to those of cascade reservoirs. The large volumes flowing through the canals and tunnels could explain the observed pattern. The CS reservoirs can therefore be considered multi-system reservoirs in cascade, constituting a particular case of multi-system reservoirs.
Salgado, Iván; Mera-Hernández, Manuel; Chairez, Isaac
2017-11-01
This study addresses the problem of designing an output-based controller to stabilize multi-input multi-output (MIMO) systems in the presence of parametric disturbances as well as uncertainties in the state model and output noise measurements. The controller design includes a linear state transformation which separates uncertainties matched to the control input and the unmatched ones. A differential neural network (DNN) observer produces a nonlinear approximation of the matched perturbation and the unknown states simultaneously in the transformed coordinates. This study proposes the use of the Attractive Ellipsoid Method (AEM) to optimize the gains of the controller and the gain observer in the DNN structure. As a consequence, the obtained control input minimizes the convergence zone for the estimation error. Moreover, the control design uses the estimated disturbance provided by the DNN to obtain a better performance in the stabilization task in comparison with a quasi-minimal output feedback controller based on a Luenberger observer and a sliding mode controller. Numerical results pointed out the advantages obtained by the nonlinear control based on the DNN observer. The first example deals with the stabilization of an academic linear MIMO perturbed system and the second example stabilizes the trajectories of a DC-motor into a predefined operation point. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Tan, Zeli; Leung, L. Ruby; Li, Hongyi; Tesfa, Teklu; Vanmaercke, Matthias; Poesen, Jean; Zhang, Xuesong; Lu, Hui; Hartmann, Jens
2017-12-01
Although sediment yield (SY) from water erosion is ubiquitous and its environmental consequences are well recognized, its impacts on the global carbon cycle remain largely uncertain. This knowledge gap is partly due to the lack of soil erosion modeling in Earth System Models (ESMs), which are important tools used to understand the global carbon cycle and explore its changes. This study analyzed sediment and particulate organic carbon yield (CY) data from 1,081 and 38 small catchments (0.1-200 km2), respectively, in different environments across the globe. Using multiple statistical analysis techniques, we explored environmental factors and hydrological processes important for SY and CY modeling in ESMs. Our results show clear correlations of high SY with traditional agriculture, seismicity and heavy storms, as well as strong correlations between SY and annual peak runoff. These highlight the potential limitation of SY models that represent only interrill and rill erosion because shallow overland flow and rill flow have limited transport capacity due to their hydraulic geometry to produce high SY. Further, our results suggest that SY modeling in ESMs should be implemented at the event scale to produce the catastrophic mass transport during episodic events. Several environmental factors such as seismicity and land management that are often not considered in current catchment-scale SY models can be important in controlling global SY. Our analyses show that SY is likely the primary control on CY in small catchments and a statistically significant empirical relationship is established to calculate SY and CY jointly in ESMs.
Directory of Open Access Journals (Sweden)
María del Refugio Castañeda-Chávez
2018-01-01
Full Text Available Organochlorine pesticides are used in agricultural areas and health campaigns, which reach the coastal environment through rivers, drains, runoffs, and atmospheric transport. In aquatic environments, they are adsorbed by particles of organic matter, depositing themselves in sediments in the bottom of these bodies, in which benthic organisms of commercial interest for human consumption inhabit. The objective of this research was to evaluate the concentration of organochlorine pesticides in sediment from the Alvarado lagoon system in Veracruz, Mexico. In 20 out of 41 sampling sites analyzed, 11 banned organochlorine pesticides were identified, such as hexachlorocyclohexane (HCH, lindane, aldrin, dieldrin, and endrin. The highest concentrations were as follows: aldrin: 46.05 ng g−1; β-HCH: 42.11 ng g−1; α-HCH: 38.44 ng g−1; gamma γ-HCH (lindane: 34.20 ng g−1; δ-HCH: 31.61 ng g−1; methoxychlor: 29.40 ng g−1; heptachlor epoxide: 25.70 ng g−1; heptachlor: 24.11 ng g−1; dieldrin: 22.13 ng g−1; endrin: 21.23 ng g−1; endrin aldehyde: 12.40 ng g−1. Concentrations reported are prohibited in international standards. There is a strong need to further evaluate, with scientific studies, the level of concentration reported by impact of compounds widely used in agricultural livestock activities.
Energy Technology Data Exchange (ETDEWEB)
Tan, Zeli [Pacific Northwest National Laboratory, Richland WA USA; Leung, L. Ruby [Pacific Northwest National Laboratory, Richland WA USA; Li, Hongyi [Montana State University, Bozeman MT USA; Tesfa, Teklu [Pacific Northwest National Laboratory, Richland WA USA; Vanmaercke, Matthias [Département de Géographie, Université de Liège, Liege Belgium; Poesen, Jean [Department of Earth and Environmental Sciences, Division of Geography, KU Leuven, Leuven Belgium; Zhang, Xuesong [Pacific Northwest National Laboratory, Richland WA USA; Lu, Hui [Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing China; Hartmann, Jens [Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg Germany
2017-12-01
Although sediment yield (SY) from water erosion is ubiquitous and its environmental consequences are well recognized, its impacts on the global carbon cycle remain largely uncertain. This knowledge gap is partly due to the lack of soil erosion modeling in Earth System Models (ESMs), which are important tools used to understand the global carbon cycle and explore its changes. This study analyzed sediment and particulate organic carbon yield (CY) data from 1081 and 38 small catchments (0.1-200 km27 ), respectively, in different environments across the globe. Using multiple statistical analysis techniques, we explored environmental factors and hydrological processes important for SY and CY modeling in ESMs. Our results show clear correlations of high SY with traditional agriculture, seismicity and heavy storms, as well as strong correlations between SY and annual peak runoff. These highlight the potential limitation of SY models that represent only interrill and rill erosion because shallow overland flow and rill flow have limited transport capacity due to their hydraulic geometry to produce high SY. Further, our results suggest that SY modeling in ESMs should be implemented at the event scale to produce the catastrophic mass transport during episodic events. Several environmental factors such as seismicity and land management that are often not considered in current catchment-scale SY models can be important in controlling global SY. Our analyses show that SY is likely the primary control on CY in small catchments and a statistically significant empirical relationship is established to calculate SY and CY jointly in ESMs.
Directory of Open Access Journals (Sweden)
S.Z.Mohammad Noor
2016-06-01
Full Text Available This paper presents an implementation of Single-phase Single stage String inverter for Grid connected Photovoltaic (PV system. The proposed system uses Modified Perturb and Observe (P&O algorithm implemented using Fuzzy Logic Control (FLC as Maximum Power Point Tracking (MPPT. The inverter is designed for 340W system using two series of STP170s24/Ac PV modules. The MPPT unit keeps tracking the maximum power from the PV array by changing the modulation index and the phase angle of inverter’s output voltage. The simulation model is developed using Matlab/Simulink to evaluate the performance of the converter. Selected experimental results are also presented in this paper.
International Nuclear Information System (INIS)
Chunye Lin; Shaoqing Liu; Mengchang He; Ruiping Li
2013-01-01
The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg -1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r 2 = 0.959-0.988) and the concentrations of Fe, Al, and Mn (r 2 = 0.768-0.870). The total concentration ΣREE ranged from 73.5 to 203.5 mg kg -1 , with an average of 156.0 mg kg -1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (ΣLREE) to heavy REEs (ΣHREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area. (author)
Application of systems analysis to the disposal of high level waste in deep ocean sediments
International Nuclear Information System (INIS)
De Marsily, G.; Dorp, F. van
1982-01-01
Emplacement in deep ocean sediments is one of the disposal options being considered for solidified high level radioactive waste. Task groups set up within the framework of the NEA Seabed Working Group have been studying many aspects of this option since 1976. The methods of systems analysis have been applied to enable the various parts of the problem to be assessed within an integrated framework. This paper describes the progress made by the Systems Analysis Task Group towards the development of an overall system model. The Task Group began by separating the problem into elements and defining the interfaces between these elements. A simple overall system model was then developed and used in both a preliminary assessment and a sensitivity analysis to identify the most important parameters. These preliminary analyses used a very simple model of the overall system and therefore the results cannot be used to draw any conclusions as to the acceptability of the sub-seabed disposal option. However they served to show the utility of the systems analysis method. The work of the other task groups will focus on the important parameters so that improved results can be fed back into an improved system model. Subsequent iterations will eventually provide an input to an acceptability decision. (Auth.)
International Nuclear Information System (INIS)
Stachowski, Ademir F.A.; Lapolli, André L.; Carbonari, Artur W.; Saxena, Rajendra N.
2017-01-01
This work reports results from the automation of data acquisition for a gamma-gamma perturbed angular correlation (PAC) spectrometer located in the hyperfine interactions laboratory (LIH) of IPEN. A PAC spectrometer comprises usually four scintillation detectors (BaF_3 for example) and carries out time measurements from gamma rays of any two combinations of detectors in coincidence. Gamma rays come from the decay of probe nuclei embedded into the material to be studied. Measurements are generally performed as a function of temperature. The fourth-detectors PAC spectrometer was automated in Java language because it is a multi platform and object oriented programming language, having, therefore, portability and longer lifetime due to the ease of implementation of peripherals. Finally, the software has a friendly and intuitive interface with the user being able to operate the hardware manually or automatically with time acquisitions up to 100 consecutive hours. Before each acquisition, the software sets the temperature, waits for temperature stability and records data in different files. Moreover, the software also saves in a file all information of relevant parameters during acquisition. (author)
Energy Technology Data Exchange (ETDEWEB)
Stachowski, Ademir F.A.; Lapolli, André L.; Carbonari, Artur W.; Saxena, Rajendra N., E-mail: alapolli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2017-11-01
This work reports results from the automation of data acquisition for a gamma-gamma perturbed angular correlation (PAC) spectrometer located in the hyperfine interactions laboratory (LIH) of IPEN. A PAC spectrometer comprises usually four scintillation detectors (BaF{sub 3} for example) and carries out time measurements from gamma rays of any two combinations of detectors in coincidence. Gamma rays come from the decay of probe nuclei embedded into the material to be studied. Measurements are generally performed as a function of temperature. The fourth-detectors PAC spectrometer was automated in Java language because it is a multi platform and object oriented programming language, having, therefore, portability and longer lifetime due to the ease of implementation of peripherals. Finally, the software has a friendly and intuitive interface with the user being able to operate the hardware manually or automatically with time acquisitions up to 100 consecutive hours. Before each acquisition, the software sets the temperature, waits for temperature stability and records data in different files. Moreover, the software also saves in a file all information of relevant parameters during acquisition. (author)
Mobilisation, alteration, and redistribution of monosulfidic sediments in inland river systems.
Cheetham, M D; Wong, V N L; Bush, R T; Sullivan, L A; Ward, N J; Zawadzki, A
2012-12-15
The accumulation of monosulfidic sediments in inland waterways is emerging as a major environmental issue. Mobilisation and suspension of monosulfidic sediments can result in deoxygenation, acidification of the water column and mobilisation of trace metals. The controls on monosulfidic sediment mobilisation and the critical thresholds for its scour and entrainment have not been established. This study examines the effect of a minor flood event (average return interval of 5 years) on sulfidic sediment scour in the Wakool River in southern NSW, Australia. Five profiles were sampled within a small (~300 m) reach before and after a minor flood event to determine the degree of sediment scour and transport. The results indicate substantial scour of both monosulfidic sediments and underlying bed sediments (approximately 2100 m(3)). Changes in the sediment geochemistry suggest large concentrations of monosulfidic sediments had been suspended in the water column, partially-oxidised and redeposited. This is supported by (210)Pb results from one of the profiles. These results suggest that these monosulfidic sediments can move as bed load during minor flood events. Copyright © 2012 Elsevier Ltd. All rights reserved.
Multi-timescale sediment responses across a human impacted river-estuary system
Chen, Yining; Chen, Nengwang; Li, Yan; Hong, Huasheng
2018-05-01
Hydrological processes regulating sediment transport from land to sea have been widely studied. However, anthropogenic factors controlling the river flow-sediment regime and subsequent response of the estuary are still poorly understood. Here we conducted a multi-timescale analysis on flow and sediment discharges during the period 1967-2014 for the two tributaries of the Jiulong River in Southeast China. The long-term flow-sediment relationship remained linear in the North River throughout the period, while the linearity showed a remarkable change after 1995 in the West River, largely due to construction of dams and reservoirs in the upland watershed. Over short timescales, rainstorm events caused the changes of suspended sediment concentration (SSC) in the rivers. Regression analysis using synchronous SSC data in a wet season (2009) revealed a delayed response (average 5 days) of the estuary to river input, and a box-model analysis established a quantitative relationship to further describe the response of the estuary to the river sediment input over multiple timescales. The short-term response is determined by both the vertical SSC-salinity changes and the sediment trapping rate in the estuary. However, over the long term, the reduction of riverine sediment yield increased marine sediments trapped into the estuary. The results of this study indicate that human activities (e.g., dams) have substantially altered sediment delivery patterns and river-estuary interactions at multiple timescales.
Sediment Flux and Storage in a Rural Southeastern Piedmont River System
Jackson, C. R.; Martin, J. K.
2001-12-01
A sediment budget was developed for a representative rural southeastern Piedmont watershed to provide information on the relative importance of sediment sources. Sediment issues in the southeastern Piedmont are complicated by the so-called legacy sediment produced by poor farming practices during the cotton-farming era, approximately 1810-1930. The Murder Creek basin near Monticello, GA was chosen because: it featured forestry and agriculture as the principal land uses; a USGS gage provided a flow record; and the creek deposited in a reservoir built in 1948. Suspended load export was calculated using a sediment rating curve and the USGS flow time series. Bed load export was determined by estimating the volume of sediment deposited in the reservoir since construction. Unpaved road erosion was estimated using the WEPP model, and other surface erosion was estimated using USLE and delivery ratios. Historical floodplain storage was determined by coring floodplain deposits, measuring the depth to the pre-historic/historic sediment interface, and multiplying by the area of the floodplain. Recent accretion rates were estimated using dendrogeomorphology. Results showed that the practices of the cotton farming era deposited an average of 1.6 meters of sediment on the floodplains. This depth was relatively uniform across the watershed. The cotton-farming sediment in storage exceeds the current annual export by a factor of about 5000. Approximately half of the current export comes from current inputs, and half comes from remobilized floodplain sediments.
Perturbative QCD and exclusive processes
International Nuclear Information System (INIS)
Bennett, J.; Hawes, F.; Zhao, M.; Zyla, P.
1991-01-01
The authors discuss perturbation theory as applied to particle physics calculations. In particle physics one is generally interested in the scattering amplitude for a system going from some initial state to a final state. The intermediate state or states are unknown. To get the scattering amplitude it is necessary to sum the contributions from processes which pass through all possible intermediate states. Intermediate states involve the exchange of intermediate vector bosons between the particles, and with this interaction is associated a coupling constant α. Each additional boson exchange involves an additional contribution of α to the coupling. If α is less than 1, one can see that the relative contribution of higher order processes is less and less important as α falls. In QCD the gluons serve as the intermediate vector bosons exchanged by quarks and gluons, and the interaction constant is not really a constant, but depends upon the distance between the particles. At short distances the coupling is small, and one can assume perturbative expansions may converge rapidly. Exclusive scattering processes, as opposed to inclusive, are those in which all of the final state products are detected. The authors then discuss the application of perturbative QCD to the deuteron. The issues of chiral conservation and color transparancy are also discussed, in the scheme of large Q 2 interations, where perturbative QCD should be applicable
Energy Technology Data Exchange (ETDEWEB)
Satterley, A.K. [Univ. Innsbruck (Austria). Inst. fuer Geologie und Palaeontologie
1996-03-01
This study addresses the origin of the famous Lofer cycles by looking at the sedimentology of an entire depositional system. More than 700 m of platform Lofer cycles at the Steinernes Meer are analyzed, and the transition from those peritidal Lofer cycles through cyclic and noncyclic sediments of the adjacent Hochkoenig reef complex to the Hochkoenig reef slope and both Koessen and Hallstatt basin successions is outlined. This paper stresses the notion of a dynamic balance between random deposition and reworking within an unpredictable and complex sedimentary system, rather than orderly sedimentation in response to orbital forcing. The role of random vertical tectonic downdropping is considered here but has rarely been fully considered in previous studies of cyclic carbonates. It may not be realistic to assume that subsidence over time can be accurately represented by a smooth trace in areas where subsidence is partly or wholly fault controlled. Throughout this paper, the term periodic is used to indicate events with a specific temporal recurrence interval. Aperiodic is used to describe temporally recurrent events that lack a controlled recurrence interval. Aperiodic events described in this paper could also be loosely considered random.
Modern Sedimentation off the Kaoping River, SW Taiwan: A Comparison with Eel River's S2S System
Huh, C.; Lin, H.; Lin, S.
2006-12-01
The Kaoping (KP) River in SW Taiwan has a watershed area of 3257 km2 and an annual sediment discharge of 49 MT. Although the sediment yield of the KP River basin (1.5×104 ton km-2 yr^{- 1}) is the 4th highest among Taiwan's catchment basins, it is nearly one order of magnitude higher than that of the Eel River's basin (~1.8×103 ton km-2 yr-1; the highest in the U.S.). The KP canyon extends almost immediately seaward from the river's mouth and terminates in the northwestern corner of the South China Sea. The head of the canyon is characterized by high and steep walls exceeding 600 m. The KP river's source-to-sink system offers a dramatic case of mountainous rivers at active margins for S2S study. Here we report some results about modern sedimentation in KP river's dispersal system. Seventy-six sediment cores collected from an area of ~3000 km2 were analyzed for fallout nuclides 7Be, 137Cs and 210Pb by gamma spectrometry. From profiles of excess 210Pb and 137Cs sediment accumulation rates in the coring sites were estimated, which vary from 0.06 to 1.6 cm/yr, with the highest rates (>1 cm/yr) distributed in the upper slope (exported out of the study area via the KP canyon to the deep sea by gravity-driven turbidity or hyperpycnal flows.
Virus-Bacterium Interactions in Water and Sediment of West African Inland Aquatic Systems
Bettarel, Yvan; Bouvy, Marc; Dumont, Claire; Sime-Ngando, Télesphore
2006-01-01
The ecology of virioplankton in tropical aquatic ecosystems is poorly documented, and in particular, there are no references concerning African continental waters in the literature. In this study, we examined virus-bacterium interactions in the pelagic and benthic zones of seven contrasting shallow inland waters in Senegal, including one hypersaline lake. SYBR Gold-stained samples revealed that in the surface layers of the sites, the numbers of viruses were in the same range as the numbers of viruses reported previously for productive temperate systems. Despite high bacterial production rates, the percentages of visibly infected cells (as determined by transmission electron microscopy) were similar to the lowest percentages (range, 0.3 to 1.1%; mean, 0.5%) found previously at pelagic freshwater or marine sites, presumably because of the local environmental and climatic conditions. Since the percentages of lysogenic bacteria were consistently less than 8% for pelagic and benthic samples, lysogeny did not appear to be a dominant strategy for virus propagation at these sites. In the benthic samples, viruses were highly concentrated, but paradoxically, no bacteria were visibly infected. This suggests that sediment provides good conditions for virus preservation but ironically is an unfavorable environment for proliferation. In addition, given the comparable size distributions of viruses in the water and sediment samples, our results support the paradigm that aquatic viruses are ubiquitous and may have moved between the two compartments of the shallow systems examined. Overall, this study provides additional information about the relevance of viruses in tropical areas and indicates that the intensity of virus-bacterium interactions in benthic habitats may lower than the intensity in the adjacent bodies of water. PMID:16885276
Tracking the 10Be–26Al source-area signal in sediment-routing systems of arid central Australia
Directory of Open Access Journals (Sweden)
M. Struck
2018-05-01
Full Text Available Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems ( ∼ 100 000 km2 in central Australia with the aim of tracking downstream variations in 10Be–26Al inventories and identifying the factors responsible for these variations. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55 from source areas, we show that 10Be–26Al inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream, a distinct lithological signal is retained. Post-orogenic ranges yield catchment erosion rates of ∼ 6–11 m Myr−1 and silcrete-dominant areas erode as slow as ∼ 0.2 m Myr−1. 10Be–26Al inventories in stream sediments indicate that cumulative-burial terms increase downstream to mostly ∼ 400–800 kyr and up to ∼ 1.1 Myr. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 10Be–26Al source-area signal differs according to geomorphic setting. Signal preservation is favoured by (i high sediment supply rates, (ii high mean runoff, and (iii a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of (i low sediment supply and (ii juxtaposition of sediment storages with notably different exposure
International Nuclear Information System (INIS)
Mueller, A.H.
1986-03-01
A brief review of some of the recent progress in perturbative QCD is given (heavy quark production, small-x physics, minijets and related topics, classical simulations in high energy reactions, coherence and the string effect)
Godfrey, Andrew E.; Everitt, Benjamin L.; Duque, José F. Martín
2008-12-01
The Fremont River drains about 1000 km 2 of Mancos Shale badlands, which provide a large percentage of the total sediment load of its middle and lower reaches. Factors controlling sediment movement include: weathering that produces thin paralithic soils, mass movement events that move the soil onto locations susceptible to fluvial transport, intense precipitation events that move the sediment along rills and across local pediments, and finally Fremont River floods that move the sediment to the main-stem Colorado River. A forty-year erosion-pin study has shown that down-slope creep moves the weathered shale crust an average of 5.9 cm/yr. Weather records and our monitoring show that wet winters add large slab failures and mudflows. Recent sediment-trap studies show that about 95% of sediment movement across pediments is accomplished by high-intensity summer convective storms. Between 1890 and 1910, a series of large autumn floods swept down the Fremont River, eroding its floodplain and transforming it from a narrow and meandering channel to a broad, braided one. Beginning about 1940, the Fremont's channel began to narrow. Sequential aerial photos and cross-sections suggest that floodplain construction since about 1966 has stored about 4000 to 8000 m 3 of sediment per kilometer per year. These data suggest that it will take two centuries to restore the floodplain to its pre-1890 condition, which is in line with geologic studies elsewhere on the Colorado Plateau. The various landscape elements of slope, pediment, and floodplain are semi-independent actors in sediment delivery, each with its own style. Accelerated mass movement on the slopes has an approximate 20-year recurrence. Sediment movement from slope across pediments to master stream is episodic and recurs more frequently. The slope-to-pediment portion of the system appears well connected. However, sediment transport through the floodplain is not well connected in the decadal time scale, but increases in the
Generalized chiral perturbation theory
International Nuclear Information System (INIS)
Knecht, M.; Stern, J.
1994-01-01
The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT (Chiral Perturbation Theory), relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard χPT become possible. Emphasis is put on physical aspects rather than on formal developments of GχPT. (author). 31 refs
Sorption Characteristics of Sediments in the Upper Mississippi River System Above Lake Pepin
National Research Council Canada - National Science Library
James, W
1999-01-01
This technical note examines equilibrium phosphorus processes and sorption characteristics for sediments collected from the Minnesota River, immediately upstream from its confluence with the Upper Mississippi River (UMR...
Yoneda, J.; Masui, A.; Konno, Y.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Tenma, N.; Nagao, J.
2014-12-01
Natural gas hydrate-bearing pressure core sediments have been sheared in compression using a newly developed Transparent Acrylic Cell Triaxial Testing (TACTT) system to investigate the geophysical and geomechanical behavior of sediments recovered from the deep seabed in the Eastern Nankai Trough, the first Japanese offshore production test region. The sediments were recovered by hybrid pressure core system (hybrid PCS) and pressure cores were cut by pressure core analysis tools (PCATs) on board. These pressure cores were transferred to the AIST Hokkaido centre and trimmed by pressure core non-destructive analysis tools (PNATs) for TACTT system which maintained the pressure and temperature conditions within the hydrate stability boundary, through the entire process of core handling from drilling to the end of laboratory testing. An image processing technique was used to capture the motion of sediment in a transparent acrylic cell, and digital photographs were obtained at every 0.1% of vertical strain during the test. Analysis of the optical images showed that sediments with 63% hydrate saturation exhibited brittle failure, although nonhydrate-bearing sediments exhibited ductile failure. In addition, the increase in shear strength with hydrate saturation increase of natural gas hydrate is in agreement with previous data from synthetic gas hydrate. This research was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) that carries out Japan's Methane Hydrate R&D Program by the Ministry of Economy, Trade and Industry (METI).
Energy Technology Data Exchange (ETDEWEB)
Qin, Ning [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); He, Wei; Kong, Xiang-Zhen; Liu, Wen-Xiu; He, Qi-Shuang; Yang, Bin; Wang, Qing-Mei; Yang, Chen; Jiang, Yu-Jiao [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Jorgensen, Sven Erik [Section of Toxicology and Environmental Chemistry, Institute A, University of Copenhagen, University Park 2, DK 2100, Copenhagen Ø (Denmark); Xu, Fu-Liu, E-mail: xufl@urban.pku.edu.cn [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Zhao, Xiao-Li, E-mail: zhaoxiaoli_zxl@126.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)
2014-10-15
The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the water, suspended particular matter (SPM) and sediment from Lake Chaohu were measured with a gas chromatograph–mass spectrometer (GC–MS). The spatial–temporal distributions and the SPM–water partition of PAHs and their influencing factors were investigated. The potential sources and contributions of PAHs in the sediment were estimated by positive matrix factorization (PMF) and probabilistic stable isotopic analysis (PSIA). The results showed that the average residual levels of total PAHs (PAH16) in the water, SPM and sediment were 170.7 ± 70.8 ng/L, 210.7 ± 160.7 ng/L and 908.5 ± 1878.1 ng/g dry weight, respectively. The same spatial distribution trend of PAH16 in the water, SPM and sediment was found from high to low: river inflows > western lake > eastern lake > water source area. There was an obvious seasonal trend of PAH16 in the water, while no obvious seasonal trend was found in the SPM. The residues and distributions of PAHs in the water, SPM and sediment relied heavily on carbon content. Significant Pearson correlations were found between LogK{sub oc} and LogK{sub ow} as well as some hydro-meteorological factors. Three major sources of PAHs including coal and biomass combustions, and vehicle emissions were identified. - Highlights: • Highest residual level of total PAHs in the SPM was detected. • Similar spatial trend of PAH16 in the water, SPM and sediment. • PAHs distributions in the water-sediment system relied heavily on organic carbon. • Correlations between LogK{sub oc} and LogK{sub ow} as well as hydro-meteorological factors. • Coal and biomass combustions and vehicle emissions were three major sources of PAHs.
Gardner, J.V.; Dean, W.E.; Dartnell, P.
1997-01-01
A north-south transect of 17 cores was constructed along the eastern boundary of the California Current system from 33?? to 42?? N to investigate the changes in biogenic sedimentation over the past 30 kyr. Percentages and mass accumulation rates of CaCO3, Corg, and biogenic opal were assembled at 500 to 1000 years/sample to provide relatively high resolution. Time-space maps reveal a complex pattern of changes that do not follow a simple glacial-interglacial two-mode model. Biogenic sedimentation shows responses that are sometimes time-transgressive and sometimes coeval, and most of the responses show more consistency within a limited geographic area than any temporal consistency. Reconstructed conditions during late oxygen isotope stage 3 were more like early Holocene conditions than any other time during the last 30 kyr. Coastal upwelling and productivity during oxygen isotope stage 3 were relatively strong along the central California margin but were weak along the northern California margin. Precipitation increased during the last glacial interval in the central California region, and the waters of the southern California margin had relatively low productivity. Productivity on the southern Oregon margin was relatively low at the beginning of the last glacial interval, but by about 20 ka, productivity in this area significantly increased. This change suggests that the center of the divergence of the West Wind Drift shifted south at this time. The end of the last glacial interval was characterized by increased productivity in the southern California margin and increased upwelling along the central California margin but upwelling remained weak along the northern California margin. A sudden (biosphere as the northern latitudes were reforested following retreat of the glaciers. The Holocene has been a period of relatively high productivity in the southern California margin, relatively strong coastal upwelling along the central California margin, relatively weak
International Nuclear Information System (INIS)
Fitoussi, Caroline
2006-06-01
The recent observation of a 60 Fe peak in a deep-sea ferro-manganese crust has been interpreted as due to a supernova explosion relatively close to the solar system 2.8 ± 0.4 Myr ago. To confirm this interpretation with better time-resolved measurements, and the simultaneous access, on the same sample, to other isotopes and geochemical phases, marine sediments seem to be a tool of choice. The objective of this work was to search for isotopic anomalies which would be characteristic for residues of this supernova. More specifically, 129 I, 60 Fe, and 26 Al have been investigated, being measured by Accelerator Mass Spectrometry (AMS). Quantifying these nuclides' fluxes would help constrain stellar nucleosynthesis models. These residues are isotopes initially produced during hydrostatic and/or explosive nucleosynthesis. The physical conditions during the explosion (temperature, neutron density) are such that supernovae are thought to be good candidates for the astrophysical site of the r-process. The 129 I study showed that measurement of pre-anthropogenic 129 I/ 127 I ratios need a very strict control of the various potential 129 I sources, especially when working with small quantities (micrograms) of iodine. This study revealed that the expected pre-anthropogenic 129 I/ 127 I ratio for pre-nuclear samples in the marine environment shows a large discrepancy between theoretical calculations and experimental measurements. 60 Fe and 26 Al measurements allow us to conclude that, in the authigenic phase of the marine sediments, there is no 60 Fe anomaly in the time interval defined by the signal found on the Fe-Mn crust (from 2.4 to 3.2 Myr), and no 26 Al anomaly from 2.6 to 3.2 Myr. (author)
Sassi, M.; Duran-Matute, M.; van Kessel, Th.; Gerkema, Th.
2015-01-01
In multiple tidal-inlet systems such as the Dutch Wadden Sea, the exchange of sediments between the coastal lagoon and the adjacent sea is controlled by the combined effect of the tides, wind-driven flows, and density-driven flows. We investigate the variability of residual (tidally averaged) fluxes
Berg, van den M.W.
1995-01-01
River sediments of the Meuse, Rhine and local Belgian systems have been preserved in various parts of the Roer Valley rift. Age-altitude positions of Meuse terraces provide a detailed record of neotectonic regional uplift. It shows accelerations and decelerations superimposed on a long-term average
International Nuclear Information System (INIS)
Paulo Alves de Lima Ferreira; Eduardo Siegle; Michel Michaelovitch de Mahiques; Rubens Cesar Lopes Figueira; Carlos Augusto Franca Schettini
2015-01-01
This study aimed the validation of the model of diffusion-convection (MDC) of 137 Cs for the calculation of recent sedimentation rates in 13 sedimentary cores of two Brazilian coastal systems, the Cananeia-Iguape and Santos-Sao Vicente estuarine systems. The MDC covers key factors responsible for 137 Cs vertical migration in sediments: its diffusion to the interstitial water and the vertical convection of this water through the sediments. This study successfully validated the MDC use to determine sedimentation rates, which was statistically validated not only with 210 Pb xs (unsupported 210 Pb) models, widely used in oceanographic studies, but also by literature values for those regions. (author)
Zonta, Roberto; Botter, Margherita; Cassin, Daniele; Bellucci, Luca Giorgio; Pini, Roberto; Dominik, Janusz
2018-05-01
Sediments of the Venice Lagoon down to 50 cm depth were investigated to assess sediment texture and metal contamination status, before the construction and activation of the MOSE system, which is intended to prevent the periodical flood events affecting the lagoon and the city of Venice. 380 cores were collected in shallow-water areas of the lagoon, and analysed along their vertical profile to determine grain-size distribution and concentrations of some major and trace elements (Al, As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn), total carbon and organic carbon. Radionuclide analyses (137Cs, 210Pb) were performed on 15 cores in an attempt to establish sediment chronology and determine radionuclide inventories in erosional and depositional areas. On the whole-lagoon scale, strong depletion of particles water dynamics and resuspension of sediment due to anthropogenic activities. The apparent sediment accumulation rate determined with 210Pbxs in depositional areas was estimated at 0.2-0.4 cm y-1. In the majority of cores, 210Pbxs inventories were lower than expected from atmospheric fallout, suggesting its export along with fine particles. The different sediment characteristics in terms of grain-size distribution and organic carbon content observed in the upper layer with respect to the deeper ones reflect the modification of the sedimentary balance in recent years. The loss of fine particles, even from sediments in depositional areas of the northern part of the lagoon, may herald changes in local sediment texture leading to a further depletion of morphodiversity, which in turn may lead to the reduction or loss of important lagoon habitats. On the whole-lagoon scale, the prevalently lithogenic elements (Al, As, Cr, Fe, Mn, Ni) decreased towards the top of the cores, reflecting the depletion of fine particles in the upper sediment layer due to winnowing in non-confined lagoon areas. In contrast, partly anthropogenic elements (Cu, Hg, Pb, Zn) increased up to the subsurface
Energy Technology Data Exchange (ETDEWEB)
Kefford, Ben J., E-mail: ben.kefford@rmit.edu.a [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Zalizniak, Liliana [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Dunlop, Jason E. [Department of Environment and Resource Management (DERM), 120 Meiers Rd, Indooroopilly, Queensland 4068 (Australia); Smart Water Research Facility, Griffith University, Queensland (Australia); Nugegoda, Dayanthi [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Choy, Satish C. [Department of Environment and Resource Management (DERM), 120 Meiers Rd, Indooroopilly, Queensland 4068 (Australia)
2010-02-15
The effects of suspended and deposited sediments on the macroinvertebrates are well documented in upland streams but not in slower flowing lowland rivers. Using species found in lowland lotic environments, we experimentally evaluate mechanisms for sediments to affect macroinvertebrates, and in one experiment whether salinity alters the effect of suspended sediments. Suspended kaolin clay reduced feeding of Ischnura heterosticta (Odonata: Coenagrionidae) at high turbidity (1000-1500 NTU) but had no effects on feeding of Hemianax papuensis (Odonata: Aeshnidae) and Micronecta australiensis (Hemiptera: Corixidae). In freshwater (0.1 mS/cm), survival of Ischnura aurora was poor in clear water, but improved with suspended kaolin. Growth and feeding of I. aurora were unaffected by suspended sediments and salinity. Burial (1-5 mm) of eggs with kaolin or sand reduced hatching in Physa acuta (Gastropoda: Physidae), Gyraulus tasmanica (Gastropoda: Planorbidae) and Chironomus cloacalis (Diptera: Chironomidae). Settling sediments may pose greater risk to lowland lotic invertebrates than suspended sediments. - Sediment deposition may be more directly detrimental to macroinvertebrates of lowland rivers than suspended sediments.
Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment cont...
EVALUATION OF THE STATE-OF-THE-ART CONTAMINATED SEDIMENT TRANSPORT AND FATE MODELING SYSTEM
Modeling approaches for evaluating the transport and fate of sediment and associated contaminants are briefly reviewed. The main emphasis is on: 1) the application of EFDC (Environmental Fluid Dynamics Code), the state-of-the-art contaminated sediment transport and fate public do...
Dicus, C. M.; Snyder, G. T.; Dickens, G. R.
2004-12-01
Site 1230 of the Ocean Drilling Program targeted the chemistry and microbiology of an active deep-water gas hydrate system in the Peru Trench. The site is noteworthy because, at nearly 6000 m water depth, it lies well below the carbonate compensation depth and the sediments comprise mostly terrigenous clays and biogenic silica. Shipboard work at this site delineated a prominent sulfate-methane transition (SMT) at 8-10 m below seafloor (mbsf) as well as some carbonate horizons. In this study, we present calcium and strontium data for pore waters and sediments at this site, including across the SMT. Concentration profiles show that dissolved Ca2+ diffuses downward from the seafloor toward the SMT, where a sharp inflection indicates consumption of Ca2+ into an authigenic phase. Dissolved Sr2+, on the other hand, diffuses upward from depth toward the SMT. Again, however, a prominent inflection suggests removal of Sr2+ to sediment. The inferences from pore water profiles are borne out by sediment chemistry. Large peaks in the calcium and strontium content of sediment mark the SMT. The calcium and strontium fronts reach ˜2700 and ˜5 mmol/kg, respectively, at 9 mbsf, which are much greater than average background values of ˜10 and ˜1 mmol/kg. These authigenic fronts are primarily composed of carbonate minerals, as determined by acetic acid extractions and x-ray diffraction. Because the calcium and strontium fronts coincide with both the SMT and changes in dissolved chemistry, it is proposed that the carbonates are currently forming as follows: methane rising from the underlying gas hydrate system reacts with dissolved sulfate through anaerobic oxidation of methane which releases HCO3- and alkalinity and causes carbonate precipitation. The overall process has been observed elsewhere; the Peru Trench is interesting, however, because the process leads to carbonate in sediments otherwise devoid of carbonate.
Kinouchi, T.; Omata, T.; Wei, L.; Liu, T.; Araya, M.
2013-12-01
Due to the accident of the Fukushima Dai-ichi Nuclear Power Plant on March 2011, a huge amount of radionuclides including Cesium-134 and Cesium-137 was deposited over the main island of Japan and the Pacific Ocean, resulting in further transfer and diffusion of Cesium through the atmospheric flow, watershed hydrological processes, and terrestrial ecosystem. Particularly, for the transfer of Cesium-134 and Cesium-137, sediments eroded and transported by the rainfall-runoff processes play an important role as Cesium tends to be strongly adsorbed to soil particles such as clay and silt. In this study, we focus on the transport of sediment and adsorbed Cesium in the watershed-scale hydrologic system to predict the long-term change of distribution of Cesium and its discharge to rivers and ocean. We coupled a physically-based distributed hydrological model with the modules of erosion and transport of sediments and adsorbed Cesium, and applied the coupled model to the Abukuma River watershed, which is located over the area of higher deposition of Cesium. In the model, complex land use and land cover distributions, and the effect of human activities such as irrigation, dam control and urban drainage system are taken into accounts. Simulation was conducted for the period of March 2011 until August 2012, with initial spatial distribution of Cesium-134 and Cesium-137 obtained by the airborne survey. Simulated flow rates and sediment concentrations agreed well with observed, and found that since the accident, two major storms in July and September 2011 transported about 50% of total sediments transported during the simulated periods. Cesium concentration in the sediment was reproduced well except for the difference in the initial periods. This difference is attributable to the uncertainty arisen from the initial distribution of Cesium in the soil and the transfer of Cesium from the forest canopy.
Directory of Open Access Journals (Sweden)
Peng Xu
sediments under closed-circuit. The coupled P-SMFC system has shown good potential for the efficient removal of internal nitrogen.
New Approaches and Applications for Monte Carlo Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Aufiero, Manuele; Bidaud, Adrien; Kotlyar, Dan; Leppänen, Jaakko; Palmiotti, Giuseppe; Salvatores, Massimo; Sen, Sonat; Shwageraus, Eugene; Fratoni, Massimiliano
2017-02-01
This paper presents some of the recent and new advancements in the extension of Monte Carlo Perturbation Theory methodologies and application. In particular, the discussed problems involve Brunup calculation, perturbation calculation based on continuous energy functions, and Monte Carlo Perturbation Theory in loosely coupled systems.
International Nuclear Information System (INIS)
Dasnieres de Veigy, A.; Ouvry, S.; Paris-6 Univ., 75
1992-06-01
The problem of the statistical mechanics of an anyon gas is addressed. A perturbative analysis in the anyonic coupling constant α is reviewed, and the thermodynamical potential is computed at first and second order. An adequate second quantized formalism (field theory at finite temperature) is proposed. At first order in perturbation theory, the results are strikingly simple: only the second virial coefficient close to bosonic statistics is corrected. At second order, however, the complexity of the anyon model appears. One can compute exactly the perturbative correction to each cluster coefficient. However, and contrary to first order, a closed expression for the equation of state seems out of reach. As an illustration, the perturbative expressions of a 3 , a 4 , a 5 and a 6 are given at second order. Finally, using the same formalism, the equation of state of an anyon gas in a constant magnetic field is analyzed at first order in perturbation theory. (K.A.) 16 refs.; 3 figs.; 7 tabs
Stability under persistent perturbation by white noise
International Nuclear Information System (INIS)
Kalyakin, L
2014-01-01
Deterministic dynamical system which has an asymptotical stable equilibrium is considered under persistent perturbation by white noise. It is well known that if the perturbation does not vanish in the equilibrium position then there is not Lyapunov's stability. The trajectories of the perturbed system diverge from the equilibrium to arbitrarily large distances with probability 1 in finite time. New concept of stability on a large time interval is discussed. The length of interval agrees the reciprocal quantity of the perturbation parameter. The measure of stability is the expectation of the square distance from the trajectory till the equilibrium position. The method of parabolic equation is applied to both estimate the expectation and prove such stability. The main breakthrough is the barrier function derived for the parabolic equation. The barrier is constructed by using the Lyapunov function of the unperturbed system
High-density fluid-perturbation theory based on an inverse 12th-power hard-sphere reference system
International Nuclear Information System (INIS)
Ross, M.
1979-01-01
A variational theory is developed that is accurate at normal liquid densities and densities up to 4 times that of the argon triple point. This theory uses the inverse 12th-power potential as a reference system. The properties of this reference system are expressed in terms of hard-sphere packing fractions by using a modified form of hard-space variational theory. As a result of this ''bootstrapping,'' a variational procedure may be followed that employs the inverse 12th-power system as a reference but uses the hard-sphere packing fraction as the scaling parameter with which to minimize the Helmholtz free energy
Systems analysis approach to the disposal of high-level waste in deep ocean sediments
International Nuclear Information System (INIS)
Marsily, G. de; Hill, M.D.; Murray, C.N.; Talbert, D.M.; Van Dorp, F.; Webb, G.A.M.
1980-01-01
Among the different options being studied for disposal of high-level solidified waste, increasing attention is being paid to that of emplacement of glasses incorporating the radioactivity in deep oceanic sediments. This option has the advantage that the areas of the oceans under investigation appear to be relatively unproductive biologically, are relatively free from cataclysmic events, and are areas in which the natural processes are slow. Thus the environment is stable and predictable so that a number of barriers to the release and dispersion of radioactivity can be defined. Task Groups set up in the framework of the International Seabed Working Group have been studying many aspects of this option since 1976. In order that the various parts of the problem can be assessed within an integrated framework, the methods of systems analysis have been applied. In this paper the Systems Analysis Task Group members report the development of an overall system model. This will be used in an iterative process in which a preliminary analysis, together with a sensitivity analysis, identifies the parameters and data of most importance. The work of the other task groups will then be focussed on these parameters and data requirements so that improved results can be fed back into an improved overall systems model. The major requirements for the development of a preliminary overall systems model are that the problem should be separated into identified elements and that the interfaces between the elements should be clearly defined. The model evolved is deterministic and defines the problem elements needed to estimate doses to man
Directory of Open Access Journals (Sweden)
Nazareth Arguedas-Zumbado
2016-08-01
Full Text Available Due to a change in environmental paradigm and the production increase, this document is a proposal for remodeling the CONCREPAL’s settler located in Barranca, Costa Rica. It is presented as an eco-efficient alternative that simultaneously enables compliance with current legislation on landfill and wastewater reuse. Initially, an environmental diagnosis of the characteristics and performance of the current sedimentation tank was made. Subsequently, the design of the proposed remodeling of the treatment system, incorporating the recirculation of treated water in the breaker material production process, was developed. Finally, a life-size settler model was created in a test environment in order to start measurements tests and determine the functionality; successfully, after all tests, positive results within the range allowed by national legislation on total suspended-solids concentration (40 ± 0.01 mg/l were obtained. Thanks to the cost-benefit and environmental management analysis, a new settler system can be implemented with positive short and long term results for the company.
Perturbation analysis of linear control problems
International Nuclear Information System (INIS)
Petkov, Petko; Konstantinov, Mihail
2017-01-01
The paper presents a brief overview of the technique of splitting operators, proposed by the authors and intended for perturbation analysis of control problems involving unitary and orthogonal matrices. Combined with the technique of Lyapunov majorants and the implementation of the Banach and Schauder fixed point principles, it allows to obtain rigorous non-local perturbation bounds for a set of sensitivity analysis problems. Among them are the reduction of linear systems into orthogonal canonical forms, the feedback synthesis problem and pole assignment problem in particular, as well as other important problems in control theory and linear algebra. Key words: perturbation analysis, canonical forms, feedback synthesis
Mass generation in perturbed massless integrable models
International Nuclear Information System (INIS)
Controzzi, D.; Mussardo, G.
2005-01-01
We extend form-factor perturbation theory to non-integrable deformations of massless integrable models, in order to address the problem of mass generation in such systems. With respect to the standard renormalisation group analysis this approach is more suitable for studying the particle content of the perturbed theory. Analogously to the massive case, interesting information can be obtained already at first order, such as the identification of the operators which create a mass gap and those which induce the confinement of the massless particles in the perturbed theory
Critical behaviors of gravity under quantum perturbations
Directory of Open Access Journals (Sweden)
ZHANG Hongsheng
2014-02-01
Full Text Available Phase transition and critical phenomenon is a very interesting topic in thermodynamics and statistical mechanics. Gravity is believed to have deep and inherent relation to thermodynamics. Near the critical point,the perturbation becomes significant. Thus for ordinary matter (governed by interactions besides gravity the critical behavior will become very different if we ignore the perturbations around the critical point,such as mean field theory. We find that the critical exponents for RN-AdS spacetime keep the same values even when we consider the full quantum perturbations. This indicates a key difference between gravity and ordinary thermodynamic system.
Vilardy, Juan M.; Millán, María. S.; Pérez-Cabré, Elisabet
2017-08-01
We present the results of the noise and occlusion tests in the Gyrator domain (GD) for a joint transform correlator-based encryption system. This encryption system was recently proposed and it was implemented by using a fully phase nonzero-order joint transform correlator (JTC) and the Gyrator transform (GT). The decryption system was based on two successive GTs. In this paper, we make several numerical simulations in order to test the performance and robustness of the JTC-based encryption-decryption system in the GD when the encrypted image is corrupted by noise or occlusion. The encrypted image is affected by additive and multiplicative noise. We also test the effect of data loss due to partial occlusion of the encrypted information. Finally, we evaluate the performance and robustness of the encryption-decryption system in the GD by using the metric of the root mean square error (RMSE) between the original image and the decrypted image when the encrypted image is degraded by noise or modified by occlusion.
Szklarek, S; Wagner, I; Jurczak, T; Zalewski, M
2018-01-01
The study analyses the efficiency of a Sequentional Sedimentation-Biofiltration System (SSBS) built on the Sokolowka river in Lodz (Poland). It was constructed to purify a small urban river whose hydrological regime is dominated by stormwater and meltwater. The SSBS was constructed on a limited area as multi-zone constructed wetlands. The SSBS consists of three zones: sedimentation zone with structures added to improve sedimentation, a geochemical barrier made of limestone deposit and biofiltration zone. The purification processes of total suspended solids (TSS), total phosphorus (TP), total nitrogen (TP) and other nutrients: phosphates (PO 4 3- ), ammonium (NH 4 + ) and nitrates (NO 3 - ) of the SSBS were analyzed. Chloride (Cl - ) reduction was investigated. Monitoring conducted in the first two hydrological years after construction indicated that the SSBS removed 61.4% of TSS, 37.3% of TP, 30.4% of PO 4 3- , 46.1% of TN, 2.8% of NH4+, 44.8% of NO 3 - and 64.0% of Cl - . The sedimentation zone played a key role in removing TSS and nutrients. The geochemical barrier and biofiltration zone each significantly improved overall efficiency by 4-10% for TSS, PO 4 3- , TN, NO 3 - and Cl - . Although the system reduced the concentration of chloride, further studies are needed to determine the circulation of Cl - in constructed wetlands (CWs), and to assess its impact on purification processes. Copyright © 2017 Elsevier Ltd. All rights reserved.
James, Andrew J A; Konik, Robert M; Lecheminant, Philippe; Robinson, Neil J; Tsvelik, Alexei M
2018-02-26
We review two important non-perturbative approaches for extracting the physics of low-dimensional strongly correlated quantum systems. Firstly, we start by providing a comprehensive review of non-Abelian bosonization. This includes an introduction to the basic elements of conformal field theory as applied to systems with a current algebra, and we orient the reader by presenting a number of applications of non-Abelian bosonization to models with large symmetries. We then tie this technique into recent advances in the ability of cold atomic systems to realize complex symmetries. Secondly, we discuss truncated spectrum methods for the numerical study of systems in one and two dimensions. For one-dimensional systems we provide the reader with considerable insight into the methodology by reviewing canonical applications of the technique to the Ising model (and its variants) and the sine-Gordon model. Following this we review recent work on the development of renormalization groups, both numerical and analytical, that alleviate the effects of truncating the spectrum. Using these technologies, we consider a number of applications to one-dimensional systems: properties of carbon nanotubes, quenches in the Lieb-Liniger model, 1 + 1D quantum chromodynamics, as well as Landau-Ginzburg theories. In the final part we move our attention to consider truncated spectrum methods applied to two-dimensional systems. This involves combining truncated spectrum methods with matrix product state algorithms. We describe applications of this method to two-dimensional systems of free fermions and the quantum Ising model, including their non-equilibrium dynamics.
James, Andrew J. A.; Konik, Robert M.; Lecheminant, Philippe; Robinson, Neil J.; Tsvelik, Alexei M.
2018-04-01
We review two important non-perturbative approaches for extracting the physics of low-dimensional strongly correlated quantum systems. Firstly, we start by providing a comprehensive review of non-Abelian bosonization. This includes an introduction to the basic elements of conformal field theory as applied to systems with a current algebra, and we orient the reader by presenting a number of applications of non-Abelian bosonization to models with large symmetries. We then tie this technique into recent advances in the ability of cold atomic systems to realize complex symmetries. Secondly, we discuss truncated spectrum methods for the numerical study of systems in one and two dimensions. For one-dimensional systems we provide the reader with considerable insight into the methodology by reviewing canonical applications of the technique to the Ising model (and its variants) and the sine-Gordon model. Following this we review recent work on the development of renormalization groups, both numerical and analytical, that alleviate the effects of truncating the spectrum. Using these technologies, we consider a number of applications to one-dimensional systems: properties of carbon nanotubes, quenches in the Lieb–Liniger model, 1 + 1D quantum chromodynamics, as well as Landau–Ginzburg theories. In the final part we move our attention to consider truncated spectrum methods applied to two-dimensional systems. This involves combining truncated spectrum methods with matrix product state algorithms. We describe applications of this method to two-dimensional systems of free fermions and the quantum Ising model, including their non-equilibrium dynamics.
Keenan, Alexandra B; Jenkins, Sherry L; Jagodnik, Kathleen M; Koplev, Simon; He, Edward; Torre, Denis; Wang, Zichen; Dohlman, Anders B; Silverstein, Moshe C; Lachmann, Alexander; Kuleshov, Maxim V; Ma'ayan, Avi; Stathias, Vasileios; Terryn, Raymond; Cooper, Daniel; Forlin, Michele; Koleti, Amar; Vidovic, Dusica; Chung, Caty; Schürer, Stephan C; Vasiliauskas, Jouzas; Pilarczyk, Marcin; Shamsaei, Behrouz; Fazel, Mehdi; Ren, Yan; Niu, Wen; Clark, Nicholas A; White, Shana; Mahi, Naim; Zhang, Lixia; Kouril, Michal; Reichard, John F; Sivaganesan, Siva; Medvedovic, Mario; Meller, Jaroslaw; Koch, Rick J; Birtwistle, Marc R; Iyengar, Ravi; Sobie, Eric A; Azeloglu, Evren U; Kaye, Julia; Osterloh, Jeannette; Haston, Kelly; Kalra, Jaslin; Finkbiener, Steve; Li, Jonathan; Milani, Pamela; Adam, Miriam; Escalante-Chong, Renan; Sachs, Karen; Lenail, Alex; Ramamoorthy, Divya; Fraenkel, Ernest; Daigle, Gavin; Hussain, Uzma; Coye, Alyssa; Rothstein, Jeffrey; Sareen, Dhruv; Ornelas, Loren; Banuelos, Maria; Mandefro, Berhan; Ho, Ritchie; Svendsen, Clive N; Lim, Ryan G; Stocksdale, Jennifer; Casale, Malcolm S; Thompson, Terri G; Wu, Jie; Thompson, Leslie M; Dardov, Victoria; Venkatraman, Vidya; Matlock, Andrea; Van Eyk, Jennifer E; Jaffe, Jacob D; Papanastasiou, Malvina; Subramanian, Aravind; Golub, Todd R; Erickson, Sean D; Fallahi-Sichani, Mohammad; Hafner, Marc; Gray, Nathanael S; Lin, Jia-Ren; Mills, Caitlin E; Muhlich, Jeremy L; Niepel, Mario; Shamu, Caroline E; Williams, Elizabeth H; Wrobel, David; Sorger, Peter K; Heiser, Laura M; Gray, Joe W; Korkola, James E; Mills, Gordon B; LaBarge, Mark; Feiler, Heidi S; Dane, Mark A; Bucher, Elmar; Nederlof, Michel; Sudar, Damir; Gross, Sean; Kilburn, David F; Smith, Rebecca; Devlin, Kaylyn; Margolis, Ron; Derr, Leslie; Lee, Albert; Pillai, Ajay
2018-01-24
The Library of Integrated Network-Based Cellular Signatures (LINCS) is an NIH Common Fund program that catalogs how human cells globally respond to chemical, genetic, and disease perturbations. Resources generated by LINCS include experimental and computational methods, visualization tools, molecular and imaging data, and signatures. By assembling an integrated picture of the range of responses of human cells exposed to many perturbations, the LINCS program aims to better understand human disease and to advance the development of new therapies. Perturbations under study include drugs, genetic perturbations, tissue micro-environments, antibodies, and disease-causing mutations. Responses to perturbations are measured by transcript profiling, mass spectrometry, cell imaging, and biochemical methods, among other assays. The LINCS program focuses on cellular physiology shared among tissues and cell types relevant to an array of diseases, including cancer, heart disease, and neurodegenerative disorders. This Perspective describes LINCS technologies, datasets, tools, and approaches to data accessibility and reusability. Copyright © 2017 Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Muhammad Irham
2016-08-01
Full Text Available Dynamic interactions of hydrological and geomorphological processes in the fluvial system result in accumulated deposit on the bed because the capacity to carry sediment has been exceeded. The bed load of the Aceh fluvial system is primarily generated by mechanical weathering resulting in boulders, pebbles, and sand, which roll or bounce along the river bed forming temporary deposits as bars on the insides of meander bends, as a result of a loss of transport energy in the system. This dynamic controls the style and range of deposits in the Aceh River. This study focuses on the spatial distribution of bed-load transport of the Aceh River. Understanding the spatial distribution of deposits facilitates the reconstruction of the changes in controlling factors during accumulation of deposits. One of the methods can be done by sieve analysis of sediment, where the method illuminates the distribution of sediment changes associated with channel morphology under different flow regimes. Hence, the purpose of this mini review is to investigate how the sediment along the river meander spatially dispersed. The results demonstrate that channel deposits in the Aceh River are formed from four different type of materials: pebble deposited along upstream left bank; sand located on the upstream, downstream, and along meander belts; and silt and clay located along the cut bank of meander bends. Because of different depositional pattern, the distribution of the sediment along the river can be used as a surrogate to identify bank stability, as well as to predict critical geometry for meander bend initiation
Cumulants in perturbation expansions for non-equilibrium field theory
International Nuclear Information System (INIS)
Fauser, R.
1995-11-01
The formulation of perturbation expansions for a quantum field theory of strongly interacting systems in a general non-equilibrium state is discussed. Non-vanishing initial correlations are included in the formulation of the perturbation expansion in terms of cumulants. The cumulants are shown to be the suitable candidate for summing up the perturbation expansion. Also a linked-cluster theorem for the perturbation series with cumulants is presented. Finally a generating functional of the perturbation series with initial correlations is studied. We apply the methods to a simple model of a fermion-boson system. (orig.)
Bucci, Lorenzo; Lavagna, Michèle; Guzzetti, Davide; Howell, Kathleen C.
2018-06-01
Interest on Large Space Structures (LSS), orbiting in strategic and possibly long-term stable locations, is nowadays increasing in the space community. LSS can serve as strategic outpost to support a variety of manned and unmanned mission, or may carry scientific payloads for astronomical observations. The paper focuses on analysing LSS in the Earth-Moon system, exploring dynamical structures that are available within a multi-body gravitational environment. Coupling between attitude and orbital dynamics is investigated, with particular interest on the gravity gradient torque exerted by the two massive attractors. First, natural periodic orbit-attitude solutions are obtained; a LSS that exploits such solutions would benefit of a naturally periodic body rotation synchronous with the orbital motion, easing the effort of the attitude control system to satisfy pointing requirements. Then, the solar radiation pressure is introduced into the fully coupled dynamical model and its effects investigated, discovering novel periodic attitude solutions. Benefits of periodic behaviours that incorporate solar radiation pressure are discussed, and analysed via the variation of some parameters (e.g reflection/absorption coefficients, position of the centre of pressure). As a final step to refine the current perturbed orbit-attitude model, a structure flexibility is also superimposed to a reference orbit-attitude rigid body motion via a simple, yet effective model. The coupling of structural vibrations and attitude motion is preliminarily explored, and allows identification of possible challenges, that may be faced to position a LSS in a periodic orbit within the Earth-Moon system.
Strings as perturbations of evolving spin networks
International Nuclear Information System (INIS)
Smolin, Lee
2000-01-01
One step in the construction of a background independent formulation of string theory is detailed, in which it is shown how perturbative strings may arise as small fluctuations around histories in a formulation of non-perturbative dynamics of spin networks due to Markopoulou. In this formulation the dynamics of spin network states and their generalizations is described in terms of histories which have discrete analogues of the causal structure and many fingered time of Lorentzian spacetimes. Perturbations of these histories turn out to be described in terms of spin systems defined on 2-dimensional timelike surfaces embedded in the discrete spacetime. When the history has a classical limit which is Minkowski spacetime, the action of the perturbation theory is given to leading order by the spacetime area of the surface, as in bosonic string theory. This map between a non-perturbative formulation of quantum gravity and a 1+1 dimensional theory generalizes to a large class of theories in which the group SU(2) i s extended to any quantum group or supergroup. It is argued that a necessary condition for the non-perturbative theory to have a good classical limit is that the resulting 1+1 dimensional theory defines a consistent and stable perturbative string theory
The Humboldt Current System: Ecosystem components and processes, fisheries, and sediment studies
Montecino, Vivian; Lange, Carina B.
2009-12-01
In the Humboldt Current System (HCS), biological and non-biological components, ecosystem processes, and fisheries are known to be affected by multi-decadal, inter-annual, annual, and intra-seasonal scales. The interplay between atmospheric variability, the poleward undercurrent, the shallow oxygen minimum zone (OMZ), and the fertilizing effect of coastal upwelling and overall high primary production rates drive bio-physical interactions, the carbon biomass, and fluxes of gases and particulate and dissolved matter through the water column. Coastal upwelling (permanent and seasonally modulated off Peru and northern Chile, and markedly seasonal between 30°S and 40°S) is the key process responsible for the high biological productivity in the HCS. At present, the western coast of South America produces more fish per unit area than any other region in the world ocean (i.e. ∼7.5 × 10 6 t of anchoveta were landed in 2007). Climate changes on different temporal scales lead to alterations in the distribution ranges of anchoveta and sardine populations and shifts in their dominance throughout the HCS. The factors affecting the coastal marine ecosystem that reverberate in the fisheries are crucial from a social perspective, since the economic consequences of mismanagement can be severe. Fish remains are often well-preserved in sediment settings under the hypoxic conditions of the OMZ off Peru and Chile, and reveal multi-decadal variability and centennial-scale changes in fish populations. Sediment studies from the Chilean continental margin encompassing the last 20,000 years of deposition reveal changes in sub-surface conditions in the HCS during deglaciation, interpreted to include: a major reorganization of the OMZ; a deglacial increase in denitrification decoupled from local marine productivity; and higher deglacial and Holocene paleoproductivities compared to the Last Glacial Maximum in central-south Chile (35-37°S) while this scheme is reversed for north
The main microelements and phosphorus content of sediments formed in a drinking water supply system
Marina Valentukeviciene; Ramune Zurauskiene; Jonas Satkunas
2016-01-01
Groundwater is the only source for drinking water supply in Lithuania. Twenty water intakes exploiting Quaternary aquifers are operating in Vilnius City. The main aim of this study was to characterize the heavy metal content of internal pipeline sediments in the water supply network. It also provides a new insight into the accumulation of phosphorus and its variation in pipeline sediments in the study area. The results of this research reflect the level of heavy metals that accumulated during...
Preheating curvaton perturbations
International Nuclear Information System (INIS)
Bastero-Gil, M.; Di Clemente, V.; King, S.F.
2005-01-01
We discuss the potentially important role played by preheating in certain variants of the curvaton mechanism in which isocurvature perturbations of a D-flat (and F-flat) direction become converted to curvature perturbations during reheating. We discover that parametric resonance of the isocurvature components amplifies the superhorizon fluctuations by a significant amount. As an example of these effects we develop a particle physics motivated model which involves hybrid inflation with the waterfall field N being responsible for generating the μ term, the right-handed neutrino mass scale, and the Peccei-Quinn symmetry breaking scale. The role of the curvaton field can be played either by usual Higgs field, or the lightest right-handed sneutrino. Our new results show that it is possible to achieve the correct curvature perturbations for initial values of the curvaton fields of order the weak scale. In this model we show that the prediction for the spectral index of the final curvature perturbation only depends on the mass of the curvaton during inflation, where consistency with current observational data requires the ratio of this mass to the Hubble constant to be 0.3
String perturbation theory diverges
International Nuclear Information System (INIS)
Gross, D.J.; Periwal, V.
1988-01-01
We prove that perturbation theory for the bosonic string diverges for arbitrary values of the coupling constant and is not Borel summable. This divergence is independent of the existence of the infinities that occur in the theory due to the presence of tachyons and dilaton tadpoles. We discuss the physical implications of such a divergence
International Nuclear Information System (INIS)
Suslov, I.M.
2005-01-01
Various perturbation series are factorially divergent. The behavior of their high-order terms can be determined by Lipatov's method, which involves the use of instanton configurations of appropriate functional integrals. When the Lipatov asymptotic form is known and several lowest order terms of the perturbation series are found by direct calculation of diagrams, one can gain insight into the behavior of the remaining terms of the series, which can be resummed to solve various strong-coupling problems in a certain approximation. This approach is demonstrated by determining the Gell-Mann-Low functions in φ 4 theory, QED, and QCD with arbitrary coupling constants. An overview of the mathematical theory of divergent series is presented, and interpretation of perturbation series is discussed. Explicit derivations of the Lipatov asymptotic form are presented for some basic problems in theoretical physics. A solution is proposed to the problem of renormalon contributions, which hampered progress in this field in the late 1970s. Practical perturbation-series summation schemes are described both for a coupling constant of order unity and in the strong-coupling limit. An interpretation of the Borel integral is given for 'non-Borel-summable' series. Higher order corrections to the Lipatov asymptotic form are discussed
Instantaneous stochastic perturbation theory
International Nuclear Information System (INIS)
Lüscher, Martin
2015-01-01
A form of stochastic perturbation theory is described, where the representative stochastic fields are generated instantaneously rather than through a Markov process. The correctness of the procedure is established to all orders of the expansion and for a wide class of field theories that includes all common formulations of lattice QCD.
Cosmological perturbations in antigravity
Oltean, Marius; Brandenberger, Robert
2014-10-01
We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely signed conformal couplings to Einstein gravity. It is motivated from the minimal conformal extension of the standard model, such that one of these scalar fields is the Higgs while the other is a new particle, the dilaton, introduced to make the Higgs mass conformally symmetric. At the background level, the theory admits novel geodesically complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a big crunch to a big bang. For simplicity, we consider scalar perturbations in the absence of anisotropies, with potential set to zero and without any radiation. We show that despite the necessarily wrong-signed kinetic term of the dilaton in the full action, these perturbations are neither ghostlike nor tachyonic in the limit of strongly repulsive gravity. On this basis, we argue—pending a future analysis of vector and tensor perturbations—that, with respect to perturbative stability, the cosmological solutions of this theory are viable.
Solan, Eilon; Vieille, Nicolas
2015-01-01
We study irreducible time-homogenous Markov chains with finite state space in discrete time. We obtain results on the sensitivity of the stationary distribution and other statistical quantities with respect to perturbations of the transition matrix. We define a new closeness relation between transition matrices, and use graph-theoretic techniques, in contrast with the matrix analysis techniques previously used.
Scalar cosmological perturbations
International Nuclear Information System (INIS)
Uggla, Claes; Wainwright, John
2012-01-01
Scalar perturbations of Friedmann-Lemaitre cosmologies can be analyzed in a variety of ways using Einstein's field equations, the Ricci and Bianchi identities, or the conservation equations for the stress-energy tensor, and possibly introducing a timelike reference congruence. The common ground is the use of gauge invariants derived from the metric tensor, the stress-energy tensor, or from vectors associated with a reference congruence, as basic variables. Although there is a complication in that there is no unique choice of gauge invariants, we will show that this can be used to advantage. With this in mind our first goal is to present an efficient way of constructing dimensionless gauge invariants associated with the tensors that are involved, and of determining their inter-relationships. Our second goal is to give a unified treatment of the various ways of writing the governing equations in dimensionless form using gauge-invariant variables, showing how simplicity can be achieved by a suitable choice of variables and normalization factors. Our third goal is to elucidate the connection between the metric-based approach and the so-called 1 + 3 gauge-invariant approach to cosmological perturbations. We restrict our considerations to linear perturbations, but our intent is to set the stage for the extension to second-order perturbations. (paper)
Generalized perturbation series
International Nuclear Information System (INIS)
Baird, L.C.; Stinchcomb, G.
1973-01-01
An approximate solution of the Green's function equation may be used to generate an exact solution of the Schroedinger equation. This is accomplished through an iterative procedure. The procedure is equivalent to a perturbation expansion if the approximate Green's function is exact with respect to some reference potential
DEFF Research Database (Denmark)
jora, Renata; Schechter, Joseph; Naeem Shahid, M.
2009-01-01
We study the effects of the perturbation which violates the permutation symmetry of three Majorana neutrinos but preserves the well known (23) interchange symmetry. This is done in the presenceof an arbitrary Majorana phase which serves to insure the degeneracy of the three neutrinos at the unper...... at the unperturbed level....
Post van der Burg, Max; Jenni, Karen E.; Nieman, Timothy L.; Eash, Josh D.; Knutsen, Gregory A.
2014-01-01
Sedimentation has been identified as an important stressor across a range of wetland systems. The U.S. Fish and Wildlife Service has the responsibility of maintaining wetlands within its National Wildlife Refuge System for use by migratory waterbirds and other wildlife. Many of these wetlands could be negatively affected by accelerated rates of sedimentation, especially those located in agricultural parts of the landscape. In this report we document the results of a decision analysis project designed to help U.S. Fish and Wildlife Service staff at the Agassiz National Wildlife Refuge (herein referred to as the Refuge) determine a strategy for managing and mitigating the negative effects of sediment loading within Refuge wetlands. The Refuge’s largest wetland, Agassiz Pool, has accumulated so much sediment that it has become dominated by hybrid cattail (Typha × glauca), and the ability of the staff to control water levels in the Agassiz Pool has been substantially reduced. This project consisted of a workshop with Refuge staff, local and regional stakeholders, and several technical and scientific experts. At the workshop we established Refuge management and stakeholder objectives, a range of possible management strategies, and assessed the consequences of those strategies. After deliberating a range of actions, the staff chose to consider the following three strategies: (1) an inexpensive strategy, which largely focused on using outreach to reduce external sediment inputs to the Refuge; (2) the most expensive option, which built on the first option and relied on additional infrastructure changes to the Refuge to increase management capacity; and (3) a strategy that was less expensive than strategy 2 and relied mostly on existing infrastructure to improve management capacity. Despite the fact that our assessments were qualitative, Refuge staff decided they had enough information to select the third strategy. Following our qualitative assessment, we discussed
Liu, James T; Hsu, Ray T; Yang, Rick J; Wang, Ya Ping; Wu, Hui; Du, Xiaoqin; Li, Anchun; Chien, Steven C; Lee, Jay; Yang, Shouye; Zhu, Jianrong; Su, Chih-Chieh; Chang, Yi; Huh, Chih-An
2018-03-09
Globally mud areas on continental shelves are conduits for the dispersal of fluvial-sourced sediment. We address fundamental issues in sediment dynamics focusing on how mud is retained on the seabed on shallow inner shelves and what are the sources of mud. Through a process-based comprehensive study that integrates dynamics, provenance, and sedimentology, here we show that the key mechanism to keep mud on the seabed is the water-column stratification that forms a dynamic barrier in the vertical that restricts the upward mixing of suspended sediment. We studied the 1000 km-long mud belt that extends from the mouth of the Changjiang (Yangtze) River along the coast of Zhejiang and Fujian Provinces of China and ends on the west coast of Taiwan. This mud belt system is dynamically attached to the fluvial sources, of which the Changjiang River is the primary source. Winter is the constructive phase when active deposition takes place of fine-grained sediment carried mainly by the Changjiang plume driven by Zhe-Min Coastal Currents southwestward along the coast.
Giatsis, Christos; Md Yusoff, Fatimah; Verreth, Johan; Verdegem, Marc
2018-01-01
The experimental set-up of this study mimicked recirculating aquaculture systems (RAS) where water quality parameters such as dissolved oxygen, pH, temperature, and turbidity were controlled and wastes produced by fish and feeding were converted to inorganic forms. A key process in the RAS was the conversion of ammonia to nitrite and nitrite to nitrate through nitrification. It was hypothesized that algae inclusion in RAS would improve the ammonia removal from the water; thereby improving RAS water quality and stability. To test this hypothesis, the stability of the microbiota community composition in a freshwater RAS with (RAS+A) or without algae (RAS-A) was challenged by introducing an acute pH drop (from pH 7 to 4 during three hours) to the system. Stigeoclonium nanum, a periphytic freshwater microalga was used in this study. No significant effect of the algae presence was found on the resistance to the acute pH drop on ammonia conversion to nitrite and nitrite conversion to nitrate. Also the resilience of the ammonia conversion to the pH drop disruption was not affected by the addition of algae. This could be due to the low biomass of algae achieved in the RAS. However, with regard to the conversion step of nitrite to nitrate, RAS+A was significantly more resilient than RAS-A. In terms of overall bacterial communities, the composition and predictive function of the bacterial communities was significantly different between RAS+A and RAS-A. PMID:29659617
Directory of Open Access Journals (Sweden)
Li Wang
2017-02-01
Full Text Available The ability to obtain appropriate parameters for an advanced pressurized water reactor (PWR unit model is of great significance for power system analysis. The attributes of that ability include the following: nonlinear relationships, long transition time, intercoupled parameters and difficult obtainment from practical test, posed complexity and difficult parameter identification. In this paper, a model and a parameter identification method for the PWR primary loop system were investigated. A parameter identification process was proposed, using a particle swarm optimization (PSO algorithm that is based on random perturbation (RP-PSO. The identification process included model variable initialization based on the differential equations of each sub-module and program setting method, parameter obtainment through sub-module identification in the Matlab/Simulink Software (Math Works Inc., Natick, MA, USA as well as adaptation analysis for an integrated model. A lot of parameter identification work was carried out, the results of which verified the effectiveness of the method. It was found that the change of some parameters, like the fuel temperature and coolant temperature feedback coefficients, changed the model gain, of which the trajectory sensitivities were not zero. Thus, obtaining their appropriate values had significant effects on the simulation results. The trajectory sensitivities of some parameters in the core neutron dynamic module were interrelated, causing the parameters to be difficult to identify. The model parameter sensitivity could be different, which would be influenced by the model input conditions, reflecting the parameter identifiability difficulty degree for various input conditions.
International Nuclear Information System (INIS)
Dawson, R.; Duursma, E.K.
1976-01-01
The distribution of the radioisotopes 36 Cl, 54 Mn, 59 Fe, 60 Co, 65 Zn, 90 Sr, 106 Ru, 109 Cd, 110 mAg, 137 Cs, 144 Ce, 147 Pm and 204 Tl between sea water, Mediterranean sediment in suspension, and the phytoplankton species Phaeodactylum tricornutum was studied by using a competitive technique in which the various phases were separated by dialysis membranes. The radioisotopes were introduced into the sea water compartment and the radionuclide uptake by sediment and phytoplankton occurred in the adjoining compartments after the isotopes had diffused through the membranes. The diffusion through membranes is time dependent and related to the hydrated ion radii of the elements in solution. Chelation of the elements by organic matter from sewage may hamper this diffusion, although the complexing molecules themselves can pass through the membrane. The laboratory experiments showed that the uptake of radionuclides by sediments and phytoplankton in suspension did not occur independently of each other but in competition relative to the different affinities to the sediment and phytoplankton and relative to the concentrations of the particulate materials themselves. On examination of the distribution coefficients, the isotopes 90Sr, 110m Ag, 204 Ti and in particular 109 Cd, had higher affinities towards Phaeodactylum tricornutum than towards the Mediterranean sediment. The isotopes 54 Mn, 60 Co and 137 Cs had lower distribution coefficients with the phytoplankton than with sediment and in the case of 59 Fe, 65 Zn, l06 Ru, l 4 Ce and 147 Pm, the distribution coefficients were similar for both phytoplankton and sediment. Taking into account that many more factors play a role in the natural aquatic environment, the distribution pattern between water, plankton and sediment in suspension can be approximated by calculating the percentage distribution in the 3 phases. Those percentages are dependent on 2 parameters, being the distribution coefficients and the concentrations of the
International Nuclear Information System (INIS)
Del Ben, Mauro; Hutter, Jürg; VandeVondele, Joost
2015-01-01
The forces acting on the atoms as well as the stress tensor are crucial ingredients for calculating the structural and dynamical properties of systems in the condensed phase. Here, these derivatives of the total energy are evaluated for the second-order Møller-Plesset perturbation energy (MP2) in the framework of the resolution of identity Gaussian and plane waves method, in a way that is fully consistent with how the total energy is computed. This consistency is non-trivial, given the different ways employed to compute Coulomb, exchange, and canonical four center integrals, and allows, for example, for energy conserving dynamics in various ensembles. Based on this formalism, a massively parallel algorithm has been developed for finite and extended system. The designed parallel algorithm displays, with respect to the system size, cubic, quartic, and quintic requirements, respectively, for the memory, communication, and computation. All these requirements are reduced with an increasing number of processes, and the measured performance shows excellent parallel scalability and efficiency up to thousands of nodes. Additionally, the computationally more demanding quintic scaling steps can be accelerated by employing graphics processing units (GPU’s) showing, for large systems, a gain of almost a factor two compared to the standard central processing unit-only case. In this way, the evaluation of the derivatives of the RI-MP2 energy can be performed within a few minutes for systems containing hundreds of atoms and thousands of basis functions. With good time to solution, the implementation thus opens the possibility to perform molecular dynamics (MD) simulations in various ensembles (microcanonical ensemble and isobaric-isothermal ensemble) at the MP2 level of theory. Geometry optimization, full cell relaxation, and energy conserving MD simulations have been performed for a variety of molecular crystals including NH 3 , CO 2 , formic acid, and benzene
Del Ben, Mauro; Hutter, Jürg; VandeVondele, Joost
2015-09-01
The forces acting on the atoms as well as the stress tensor are crucial ingredients for calculating the structural and dynamical properties of systems in the condensed phase. Here, these derivatives of the total energy are evaluated for the second-order Møller-Plesset perturbation energy (MP2) in the framework of the resolution of identity Gaussian and plane waves method, in a way that is fully consistent with how the total energy is computed. This consistency is non-trivial, given the different ways employed to compute Coulomb, exchange, and canonical four center integrals, and allows, for example, for energy conserving dynamics in various ensembles. Based on this formalism, a massively parallel algorithm has been developed for finite and extended system. The designed parallel algorithm displays, with respect to the system size, cubic, quartic, and quintic requirements, respectively, for the memory, communication, and computation. All these requirements are reduced with an increasing number of processes, and the measured performance shows excellent parallel scalability and efficiency up to thousands of nodes. Additionally, the computationally more demanding quintic scaling steps can be accelerated by employing graphics processing units (GPU's) showing, for large systems, a gain of almost a factor two compared to the standard central processing unit-only case. In this way, the evaluation of the derivatives of the RI-MP2 energy can be performed within a few minutes for systems containing hundreds of atoms and thousands of basis functions. With good time to solution, the implementation thus opens the possibility to perform molecular dynamics (MD) simulations in various ensembles (microcanonical ensemble and isobaric-isothermal ensemble) at the MP2 level of theory. Geometry optimization, full cell relaxation, and energy conserving MD simulations have been performed for a variety of molecular crystals including NH3, CO2, formic acid, and benzene.
International Nuclear Information System (INIS)
Johnson, K.I.; Neitzel, D.A.
1987-03-01
Biofouling surveillance and control techniques are evaluated for their applicability to sediment and corrosion fouling and suggestions are given to improve their effectiveness. Alternate techniques to better detect and control sedimentation and corrosion are also evaluated. Environmental conditions that allow biofouling, sedimentation, and corrosion to occur are summarized. A correlation between sediment and corrosion is identified and the causes are described. Environmental regulations, especially those in the Clean Water Act of 1977, are reviewed to identify those that may limit or prevent the use of surveillance and control techniques described in this report. Flow velocity is the major design factor that determines whether or not biofouling, sedimentation, and corrosion will occur. Monitoring flow conditions can provide early warning of conditions that will allow fouling to occur. Visual inspection is the most common and most effective technique for identifying the cause and extent of fouling in the open-cycle water system. Most biofouling control techniques in current use are not effective against sediment and corrosion. Frequent, high-velocity flushing of cooling loops may effectively remove sediment and reduce under-sediment corrosion. Alternate biocide treatments such as targeted chlorination or the use of ozone or 2,2-dibromo-3-nitrilo propionamide (DBNPA) may also be effective in reducing under-sediment corrosion
Fungal diversity in deep-sea sediments of a hydrothermal vent system in the Southwest Indian Ridge
Xu, Wei; Gong, Lin-feng; Pang, Ka-Lai; Luo, Zhu-Hua
2018-01-01
Deep-sea hydrothermal sediment is known to support remarkably diverse microbial consortia. In deep sea environments, fungal communities remain less studied despite their known taxonomic and functional diversity. High-throughput sequencing methods have augmented our capacity to assess eukaryotic diversity and their functions in microbial ecology. Here we provide the first description of the fungal community diversity found in deep sea sediments collected at the Southwest Indian Ridge (SWIR) using culture-dependent and high-throughput sequencing approaches. A total of 138 fungal isolates were cultured from seven different sediment samples using various nutrient media, and these isolates were identified to 14 fungal taxa, including 11 Ascomycota taxa (7 genera) and 3 Basidiomycota taxa (2 genera) based on internal transcribed spacers (ITS1, ITS2 and 5.8S) of rDNA. Using illumina HiSeq sequencing, a total of 757,467 fungal ITS2 tags were recovered from the samples and clustered into 723 operational taxonomic units (OTUs) belonging to 79 taxa (Ascomycota and Basidiomycota contributed to 99% of all samples) based on 97% sequence similarity. Results from both approaches suggest that there is a high fungal diversity in the deep-sea sediments collected in the SWIR and fungal communities were shown to be slightly different by location, although all were collected from adjacent sites at the SWIR. This study provides baseline data of the fungal diversity and biogeography, and a glimpse to the microbial ecology associated with the deep-sea sediments of the hydrothermal vent system of the Southwest Indian Ridge.
Directory of Open Access Journals (Sweden)
Beth N. Orcutt
2017-04-01
Full Text Available Weathered crude oil sank to the seafloor following the 'Deepwater Horizon' disaster in 2010, removing this oil from further physical and photo-chemical degradation processes and leaving benthic processes as the mechanisms for altering and remediating this hydrocarbon source. To quantify potential microbial oil degradation rates at the seafloor, and associated changes in sediment microbial community structure and pore fluid composition, we used a benthic lander system to deploy novel sediment flow-through chambers at a natural hydrocarbon seep in the Gulf of Mexico (at a depth of 1226 m in lease block GC600 roughly 265 km southwest of the 'Deepwater Horizon' wellhead (at 1500 m depth. Sediment amended with 20% unweathered crude oil had elevated rates of sulfate reduction over the course of the 5-month-long experiment as compared to an unamended control, yielding potential rates of sulfate reduction (600–800 mmol m–2 d–1 among the highest measured in hydrocarbon-influenced seafloor sediment. Oil amendment also stimulated methane production towards the end of the experiment, and led to slightly higher cell densities without significant changes in microbial community structure, based on 16S rRNA gene sequence libraries and fatty acid profiles. Assuming a link between sulfate reduction and hydrocarbon degradation, these results suggest that electron acceptor availability may become limiting in heavily oiled deep-sea environments, resulting in minimal degradation of deposited oil. This study provides unique data on seafloor sediment responses to oil deposition, and reveals the value of using observatories to fill the gap in understanding deep-sea microbial processes, especially for ephemeral and stochastic events such as oil spills.
Kubota, T.; Silva, I. C.; Hasnawir, H.
2009-12-01
precipitation. C: constant, given as 8000 in Fukuoka (Kyushu, Japan), as 3750 in Sierra Madere Oriental (Nuevo Leon, Mexico), as 9000 in southern Sulawesi(Indonesia). Consequently, the forecast-warning system which has enough accuracy of 80% against sediment runoffs or debris flows for both wide range region with meteorological conditions and narrow region with the critical rain standard are established. However, in the region with lower soil permeability we may revise the standard rain by the compensation with the soil moisture content response such as increasing rate.
Directory of Open Access Journals (Sweden)
Abdimajid Osman
Full Text Available Platelet concentrates (PCs are prepared at blood banks for transfusion to patients in certain clinical conditions associated with a low platelet count. To prevent transfusion-transmitted infections via PCs, different pathogen reduction (PR systems have been developed that inactivate the nucleic acids of contaminating pathogens by chemical cross-linking, a mechanism that may also affect platelets' nucleic acids. We previously reported that treatment of stored platelets with the PR system Intercept significantly reduced the level of half of the microRNAs that were monitored, induced platelet activation and compromised the platelet response to physiological agonists. Using genome-wide differential expression (DE RNA sequencing (RNA-Seq, we now report that Intercept markedly perturbs the mRNA transcriptome of human platelets and alters the expression level of >800 mRNAs (P<0.05 compared to other PR systems and control platelets. Of these, 400 genes were deregulated with DE corresponding to fold changes (FC ≥ 2. At the p-value < 0.001, as many as 147 genes were deregulated by ≥ 2-fold in Intercept-treated platelets, compared to none in the other groups. Finally, integrated analysis combining expression data for microRNA (miRNA and mRNA, and involving prediction of miRNA-mRNA interactions, disclosed several positive and inverse correlations between miRNAs and mRNAs in stored platelets. In conclusion, this study demonstrates that Intercept markedly deregulates the platelet mRNA transcriptome, concomitant with reduced levels of mRNA-regulatory miRNAs. These findings should enlighten authorities worldwide when considering the implementation of PR systems, that target nucleic acids and are not specific to pathogens, for the management of blood products.
Sediment quality and ecorisk assessment factors for a major river system
International Nuclear Information System (INIS)
Johnson, V.G.; Wagner, J.J.; Cutshall, N.H.
1993-08-01
Sediment-related water quality and risk assessment parameters for the Columbia River were developed using heavy metal loading and concentration data from Lake Roosevelt (river km 1120) to the mouth and adjacent coastal zone. Correlation of Pb, Zn, Hg, and Cd concentrations in downstream sediments with refinery operations in British Columbia suggest that solutes with K d 's > 10 5 reach about 1 to 5 μg/g per metric ton/year of input. A low-suspended load (upriver avg. <10 mg/L) and high particle-surface reactivity account for the high clay-fraction contaminant concentrations. In addition, a sediment exposure path was demonstrated based on analysis of post-shutdown biodynamics of a heavy metal radiotracer. The slow decline in sediment was attributed to resuspension, bioturbation, and anthropogenic disturbances. The above findings suggest that conservative sediment quality criteria should be used to restrict additional contaminant loading in the upper drainage basin. The issuance of an advisory for Lake Roosevelt, due in part to Hg accumulation in large sport fish, suggests more restrictive controls are needed. A monitoring strategy for assessing human exposure potential and the ecological health of the river is proposed
Mobile ankle and knee perturbator.
Andersen, Jacob Buus; Sinkjaer, Thomas
2003-10-01
A mobile ankle and knee perturbator has been developed. It consists of a functional joint with an integrated clutch. Four Bowden wires connect the joint to a powerful motor and a double pneumatic cylinder. When needed during any time of the gait cycle, it is possible to impose an ankle rotation by engaging the clutch and rotating the ankle or knee joint with a predefined displacement. The system is designed to investigate electrophysiological and biomechanical features of the human ankle or knee joint during gait.
Reduction of some perturbed Keplerian problems
Energy Technology Data Exchange (ETDEWEB)
Inarrea, Manuel [Universidad de La Rioja, Area de Fisica, 26006 Logrono (Spain); Lanchares, Victor [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain)] e-mail: vlancha@dmc.unirioja.es; Palacian, Jesus F. [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain); Pascual, Ana I. [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain); Salas, J. Pablo [Universidad de La Rioja, Area de Fisica, 26006 Logrono (Spain); Yanguas, Patricia [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain)
2006-01-01
Perturbed Hamiltonian Keplerian systems enjoying some discrete and continuous symmetries can be brought to a one degree of freedom system containing the main qualitative features of the original one. This reduced system is defined in a compact set of the plane where the qualitative dynamics can be studied in a systematic way.
Reduction of some perturbed Keplerian problems
International Nuclear Information System (INIS)
Inarrea, Manuel; Lanchares, Victor; Palacian, Jesus F.; Pascual, Ana I.; Salas, J. Pablo; Yanguas, Patricia
2006-01-01
Perturbed Hamiltonian Keplerian systems enjoying some discrete and continuous symmetries can be brought to a one degree of freedom system containing the main qualitative features of the original one. This reduced system is defined in a compact set of the plane where the qualitative dynamics can be studied in a systematic way
Studying the perturbative Reggeon
International Nuclear Information System (INIS)
Griffiths, S.; Ross, D.A.
2000-01-01
We consider the flavour non-singlet Reggeon within the context of perturbative QCD. This consists of ladders built out of ''reggeized'' quarks. We propose a method for the numerical solution of the integro-differential equation for the amplitude describing the exchange of such a Reggeon. The solution is known to have a sharp rise at low values of Bjorken-x when applied to non-singlet quantities in deep-inelastic scattering. We show that when the running of the coupling is taken into account this sharp rise is further enhanced, although the Q 2 dependence is suppressed by the introduction of the running coupling. We also investigate the effects of simulating non-perturbative physics by introducing a constituent mass for the soft quarks and an effective mass for the soft gluons exchanged in the t-channel. (orig.)
Renormalized Lie perturbation theory
International Nuclear Information System (INIS)
Rosengaus, E.; Dewar, R.L.
1981-07-01
A Lie operator method for constructing action-angle transformations continuously connected to the identity is developed for area preserving mappings. By a simple change of variable from action to angular frequency a perturbation expansion is obtained in which the small denominators have been renormalized. The method is shown to lead to the same series as the Lagrangian perturbation method of Greene and Percival, which converges on KAM surfaces. The method is not superconvergent, but yields simple recursion relations which allow automatic algebraic manipulation techniques to be used to develop the series to high order. It is argued that the operator method can be justified by analytically continuing from the complex angular frequency plane onto the real line. The resulting picture is one where preserved primary KAM surfaces are continuously connected to one another
Nonperturbative perturbation theory
International Nuclear Information System (INIS)
Bender, C.M.
1989-01-01
In this talk we describe a recently proposed graphical perturbative calculational scheme for quantum field theory. The basic idea is to expand in the power of the interaction term. For example, to solve a λφ 4 theory in d-dimensional space-time, we introduce a small parameter δ and consider a λ(φ 2 ) 1+δ field theory. We show how to expand such a theory as a series in powers of δ. The resulting perturbation series appears to have a finite radius of convergence and numerical results for low-dimensional models are good. We have computed the two-point and four-point Green's functions to second order in powers of δ and the 2n-point Green's functions (n>2) to order δ. We explain how to renormalize the theory and show that, to first order in powers of δ, when δ>0 and d≥4 the theory is free. This conclusion remains valid to second order in powers of δ, and we believe that it remains valid to all orders in powers of δ. The new perturbative scheme is consistent with global supersymmetry invariance. We examine a two-dimensional supersymmetric quantum field theory in which we do not know of any other means for doing analytical calculations. We illustrate the power of this new technique by computing the ground-state energy density E to second order in this new perturbation theory. We show that there is a beautiful and delicate cancellation between infinite classes of graphs which leads to the result that E=0. (orig.)
Perturbed asymptotically linear problems
Bartolo, R.; Candela, A. M.; Salvatore, A.
2012-01-01
The aim of this paper is investigating the existence of solutions of some semilinear elliptic problems on open bounded domains when the nonlinearity is subcritical and asymptotically linear at infinity and there is a perturbation term which is just continuous. Also in the case when the problem has not a variational structure, suitable procedures and estimates allow us to prove that the number of distinct crtitical levels of the functional associated to the unperturbed problem is "stable" unde...
Twisting perturbed parafermions
Directory of Open Access Journals (Sweden)
A.V. Belitsky
2017-07-01
Full Text Available The near-collinear expansion of scattering amplitudes in maximally supersymmetric Yang–Mills theory at strong coupling is governed by the dynamics of stings propagating on the five sphere. The pentagon transitions in the operator product expansion which systematize the series get reformulated in terms of matrix elements of branch-point twist operators in the two-dimensional O(6 nonlinear sigma model. The facts that the latter is an asymptotically free field theory and that there exists no local realization of twist fields prevents one from explicit calculation of their scaling dimensions and operator product expansion coefficients. This complication is bypassed making use of the equivalence of the sigma model to the infinite-level limit of WZNW models perturbed by current–current interactions, such that one can use conformal symmetry and conformal perturbation theory for systematic calculations. Presently, to set up the formalism, we consider the O(3 sigma model which is reformulated as perturbed parafermions.
Smith, Loren M.; Euliss, Ned H. "Chip"
2010-01-01
In the wetland science field, sediment deposition is often thought of as being beneficial especially when one thinks of coastal estuarine systems. For example, sediments deposited from streams and rivers are necessary to naturally build and maintain tidal marshes. These sediments come from eroded upland soils in the interior of the continent. When these sediments are diverted from natural coastal deposition areas, such as occurs from river channelization, we lose marshes through subsidence as is happening throughout coastal Louisiana. However, the value of eroded soils is all a matter of hydrogeomorphic perspective.
Rodrigues, M O; Abrantes, N; Gonçalves, F J M; Nogueira, H; Marques, J C; Gonçalves, A M M
2018-08-15
Microplastics (particles with a sizemicroplastics in freshwater systems is less understood than in marine environment. Hence, the present study aims to provide new insights into microplastics abundances and distribution in Antuã River (Portugal) by applying the isolation method of wet peroxide oxidation with addition of zinc chloride to water and sediment samples collected in March and October 2016, in three sampling sites. The abundance of microplastics in water ranged from 5 to 8.3mgm -3 or 58-193itemsm -3 in March and from 5.8-51.7mgm -3 or 71-1265itemsm -3 in October. In sediments, the abundance ranged from 13.5-52.7mgkg -1 or 100-629itemskg -1 in March and from 2.6-71.4mgkg -1 or 18-514itemskg -1 in October. The water and sediment samples with the greatest abundances were from São João da Madeira and Aguincheira, respectively. Spatio-temporal distribution showed different pattern according to methodological approaches, seasonal and hydrodynamic conditions and the proximity to urban/industry areas. Analysis of plastics by Fourier transform infrared spectroscopy underline polyethylene and polypropylene as the most common polymer types identified in this work. The low medium high oxidation ratio was 56:22:22 (%) in March and 61:31:8 (%) in October. Foams and fibers were the most abundant type in São João da Madeira, while fibers and fragments were the most abundant in Aguincheira and Estarreja in water and sediment samples, respectively. This study emphasizes the importance of rivers as carriage systems of microplastics. Further studies should be performed to identify point sources in order to mitigate the microplastics contamination in aquatic systems. Copyright © 2018 Elsevier B.V. All rights reserved.
Perturbation theory for continuous stochastic equations
International Nuclear Information System (INIS)
Chechetkin, V.R.; Lutovinov, V.S.
1987-01-01
The various general perturbational schemes for continuous stochastic equations are considered. These schemes have many analogous features with the iterational solution of Schwinger equation for S-matrix. The following problems are discussed: continuous stochastic evolution equations for probability distribution functionals, evolution equations for equal time correlators, perturbation theory for Gaussian and Poissonian additive noise, perturbation theory for birth and death processes, stochastic properties of systems with multiplicative noise. The general results are illustrated by diffusion-controlled reactions, fluctuations in closed systems with chemical processes, propagation of waves in random media in parabolic equation approximation, and non-equilibrium phase transitions in systems with Poissonian breeding centers. The rate of irreversible reaction X + X → A (Smoluchowski process) is calculated with the use of general theory based on continuous stochastic equations for birth and death processes. The threshold criterion and range of fluctuational region for synergetic phase transition in system with Poissonian breeding centers are also considered. (author)
Bertsch, R.; Poeppl, R. E.; Glade, T.
2012-04-01
In the recent past the concept of connectivity gained increased significance for the understanding of the linkage between different subsystems within river channels and catchments. Based on fine sediment (reservation in this fraction.
Luo, Ping; Roca, Alejandro; Tiede, Karen; Privett, Katie; Jiang, Jiachao; Pinkstone, John; Ma, Guibin; Veinot, Jonathan; Boxall, Alisatair
2018-02-01
Novel applications of nanotechnology may lead to the release of engineered nanoparticles (ENPs), which result in concerns over their potential environmental hazardous impact. It is essential for the research workers to be able to quantitatively characterise ENPs in the environment and subsequently to assist the risk assessment of the ENPs. This study hence explored the application of nanoparticle tracking system (NTA) to quantitatively describe the behaviour of the ENPs in natural sediment-water systems. The NTA allows the measurement of both particle number concentration (PNC) and particle size distribution (PSD) of the ENPs. The developed NTA method was applied to a range of gold and magnetite ENPs with a selection of surface properties. The results showed that the positively-charged ENPs interacted more strongly with the sediment than neutral and negatively-charged ENPs. It was also found that the citrate coated Au ENPs had a higher distribution percentage (53%) than 11-mercaptoundecanoic acid coated Au ENPs (20%) and citrate coated magnetite ENPs (21%). The principles of the electrostatic interactions between hard (and soft) acids and bases (HSAB) are used to explain such behaviours; the hard base coating (i.e. citrate ions) will interact more strongly with hard acid (i.e. magnetite) than soft acid (i.e. gold). The results indicate that NTA is a complementary method to existing approaches to characterise the fate and behaviour of ENPs in natural sediment. Copyright © 2017. Published by Elsevier B.V.
Computer fan performance enhancement via acoustic perturbations
Energy Technology Data Exchange (ETDEWEB)
Greenblatt, David, E-mail: davidg@technion.ac.il [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel); Avraham, Tzahi; Golan, Maayan [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel)
2012-04-15
Highlights: Black-Right-Pointing-Pointer Computer fan effectiveness was increased by introducing acoustic perturbations. Black-Right-Pointing-Pointer Acoustic perturbations controlled blade boundary layer separation. Black-Right-Pointing-Pointer Optimum frequencies corresponded with airfoils studies. Black-Right-Pointing-Pointer Exploitation of flow instabilities was responsible for performance improvements. Black-Right-Pointing-Pointer Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin-Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Secondary isocurvature perturbations from acoustic reheating
Ota, Atsuhisa; Yamaguchi, Masahide
2018-06-01
The superhorizon (iso)curvature perturbations are conserved if the following conditions are satisfied: (i) (each) non adiabatic pressure perturbation is zero, (ii) the gradient terms are ignored, that is, at the leading order of the gradient expansion (iii) (each) total energy momentum tensor is conserved. We consider the case with the violation of the last two requirements and discuss the generation of secondary isocurvature perturbations during the late time universe. Second order gradient terms are not necessarily ignored even if we are interested in the long wavelength modes because of the convolutions which may pick products of short wavelength perturbations up. We then introduce second order conserved quantities on superhorizon scales under the conditions (i) and (iii) even in the presence of the gradient terms by employing the full second order cosmological perturbation theory. We also discuss the violation of the condition (iii), that is, the energy momentum tensor is conserved for the total system but not for each component fluid. As an example, we explicitly evaluate second order heat conduction between baryons and photons due to the weak Compton scattering, which dominates during the period just before recombination. We show that such secondary effects can be recast into the isocurvature perturbations on superhorizon scales if the local type primordial non Gaussianity exists a priori.
Computer fan performance enhancement via acoustic perturbations
International Nuclear Information System (INIS)
Greenblatt, David; Avraham, Tzahi; Golan, Maayan
2012-01-01
Highlights: ► Computer fan effectiveness was increased by introducing acoustic perturbations. ► Acoustic perturbations controlled blade boundary layer separation. ► Optimum frequencies corresponded with airfoils studies. ► Exploitation of flow instabilities was responsible for performance improvements. ► Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin–Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Sediment impacts on marine sponges.
Bell, James J; McGrath, Emily; Biggerstaff, Andrew; Bates, Tracey; Bennett, Holly; Marlow, Joseph; Shaffer, Megan
2015-05-15
Changes in sediment input to marine systems can influence benthic environments in many ways. Sponges are important components of benthic ecosystems world-wide and as sessile suspension feeders are likely to be impacted by changes in sediment levels. Despite this, little is known about how sponges respond to changes in settled and suspended sediment. Here we review the known impacts of sedimentation on sponges and their adaptive capabilities, whilst highlighting gaps in our understanding of sediment impacts on sponges. Although the literature clearly shows that sponges are influenced by sediment in a variety of ways, most studies confer that sponges are able to tolerate, and in some cases thrive, in sedimented environments. Critical gaps exist in our understanding of the physiological responses of sponges to sediment, adaptive mechanisms, tolerance limits, and the particularly the effect of sediment on early life history stages. Copyright © 2015 Elsevier Ltd. All rights reserved.
Qualitative reasoning for biological network inference from systematic perturbation experiments.
Badaloni, Silvana; Di Camillo, Barbara; Sambo, Francesco
2012-01-01
The systematic perturbation of the components of a biological system has been proven among the most informative experimental setups for the identification of causal relations between the components. In this paper, we present Systematic Perturbation-Qualitative Reasoning (SPQR), a novel Qualitative Reasoning approach to automate the interpretation of the results of systematic perturbation experiments. Our method is based on a qualitative abstraction of the experimental data: for each perturbation experiment, measured values of the observed variables are modeled as lower, equal or higher than the measurements in the wild type condition, when no perturbation is applied. The algorithm exploits a set of IF-THEN rules to infer causal relations between the variables, analyzing the patterns of propagation of the perturbation signals through the biological network, and is specifically designed to minimize the rate of false positives among the inferred relations. Tested on both simulated and real perturbation data, SPQR indeed exhibits a significantly higher precision than the state of the art.
Directory of Open Access Journals (Sweden)
V. A. Коrshnyak
2016-08-01
Abstract The authors show that in modern biology, life is seen as the ability of living matter, and namely in medicine – the ability of human body, to maintain the existence in natural environment. From this perspective, it is extremely necessary to synchronize the activity of body structures among themselves taking into account the changes of environmental factors. Achieving the harmony between the body activity and environmental changes is carried out using an external pacemaker of life processes’ activity, the role of which is performed by the geomagnetic field (GMF. This became possible due to the fact that the life processes are cyclical, i.e. they possess rhythmic characteristics, and GMF is an electromagnetic field which is changing its characteristics rhythmically. The material for the present study were the data obtained during the neurological examination of 20 healthy people and 100 patients with remote consequences of CTBI which were treated in the clinic of autonomic nervous system pathology of the SI "Institute of neurology, psychiatry and narcology of the NAMS of Ukraine". The results investigations have showed that geomagnetic perturbations, which modify the GMF parameters, exacerbate the disorders of VNS in patients with remote after effects of CTBI. It is associated with the increased desynchronization of the activity of suprasegmental structures of VNS and with breach of brain vascular system’s status that occurs during a magnetic storm. The acupuncture that is aimed at restoring of synchronization of activity of suprasegmental structures of VNS significantly reduces its sensitivity to the geomagnetic disturbances. Keywords: magnetic storm, closed head injury, autonomic nervous system.
Quik, J.T.K.; Meent, van de D.; Koelmans, A.A.
2014-01-01
Parameters and simplified model approaches for describing the fate of engineered nanoparticles (ENPs) are crucial to advance the risk assessment of these materials. Sedimentation behavior of ENPs in natural waters has been shown to follow apparent first order behavior, a ‘black box’ phenomenon that
Solim, S U; Wanganeo, A
2009-01-01
Phosphorus (P) release rates from bottom sediments are high (20.6 mg/m(2)/day) in Dal Lake (India), a polymictic hyper-eutrophic lake. These gross release rates occur over a period of 72 days during summer only. Likewise, a net internal load of 11.3 tons was obtained from mass balance estimates. Significant proportion i.e. approximately 80% of 287.3 tons/yr of nitrate nitrogen (NO(3)-N) load is either eliminated by denitrification or gets entrapped for a short period in high macrophyte biomass of 3.2 kg/m(2) f.w., which eventually get decomposed and nitrogen (N) is released back. These processes result in low lake water NO(3)-N concentrations which potentially influence sediment phosphorus (P) release. Especially, nitrate nitrogen (NO(3)-N) 500 microg/L in the lake waters were associated with high P concentrations. Phosphorus was also observed to increase significantly in relation to temperature and pH, and it seems likely that release of phosphorus and ammonical nitrogen (NH(4)-N) depend on decomposition of rich reserves of organic matter (893 tons d.w. in superficial 10-cm bottom sediment layer). Lake P concentrations were significantly predicted by a multivariate regression model developed for the lake. This study describes significance of various lake water variables in relation to P-release from bottom sediments.
"Phonon" scattering beyond perturbation theory
Qiu, WuJie; Ke, XueZhi; Xi, LiLi; Wu, LiHua; Yang, Jiong; Zhang, WenQing
2016-02-01
Searching and designing materials with intrinsically low lattice thermal conductivity (LTC) have attracted extensive consideration in thermoelectrics and thermal management community. The concept of part-crystalline part-liquid state, or even part-crystalline part-amorphous state, has recently been proposed to describe the exotic structure of materials with chemical- bond hierarchy, in which a set of atoms is weakly bonded to the rest species while the other sublattices retain relatively strong rigidity. The whole system inherently manifests the coexistence of rigid crystalline sublattices and fluctuating noncrystalline substructures. Representative materials in the unusual state can be classified into two categories, i.e., caged and non-caged ones. LTCs in both systems deviate from the traditional T -1 relationship ( T, the absolute temperature), which can hardly be described by small-parameter-based perturbation approaches. Beyond the classical perturbation theory, an extra rattling-like scattering should be considered to interpret the liquid-like and sublattice-amorphization-induced heat transport. Such a kind of compounds could be promising high-performance thermoelectric materials, due to the extremely low LTCs. Other physical properties for these part-crystalline substances should also exhibit certain novelty and deserve further exploration.
Chen, Huai; Zhu, Lijun; Wang, Jianzhong; Fan, Hongxia; Wang, Zhihuan
2017-07-01
This study focuses on detecting trends in annual runoff volume and sediment load in the Yangtze river-lake system. Times series of annual runoff volume and sediment load at 19 hydrological gauging stations for the period 1956-2013 were collected. Based on the Mann-Kendall test at the 1% significance level, annual sediment loads in the Yangtze River, the Dongting Lake and the Poyang Lake were detected with significantly descending trends. The power spectrum estimation indicated predominant oscillations with periods of 8 and 20 years are embedded in the runoff volume series, probably related to the El Niño Southern Oscillation (2-7 years) and Pacific Decadal Oscillation (20-30 years). Based on dominant components (capturing more than roughly 90% total energy) extracted by the proper orthogonal decomposition method, total change ratios of runoff volume and sediment load during the last 58 years were evaluated. For sediment load, the mean CRT value in the Yangtze River is about -65%, and those in the Dongting Lake and the Poyang Lake are -92.2% and -87.9% respectively. Particularly, the CRT value of the sediment load in the channel inflow of the Dongting Lake is even -99.7%. The Three Gorges Dam has intercepted a large amount of sediment load and decreased the sediment load downstream.
International Nuclear Information System (INIS)
Figueiredo, Marcia A.O.; Eide, Ingvar; Reynier, Marcia; Villas-Bôas, Alexandre B.; Tâmega, Frederico T.S.
2015-01-01
Highlights: • Collection of rhodoliths and calcareous algae from Campos Basin, Brazil. • Impact of sediment mimicking drill cuttings on photosynthetic efficiency. • Exposure–response for photosynthetic efficiency as function of sediment coverage. • Factorial design and multivariate regression used for a structured approach. - Abstract: The impact of sediment coverage on two rhodolith-forming calcareous algae species collected at 100 m water depth off the coast of Brazil was studied in an experimental flow-through system. Natural sediment mimicking drill cuttings with respect to size distribution was used. Sediment coverage and photosynthetic efficiency (maximum quantum yield of charge separation in photosystem II, ϕ PSIImax ) were measured as functions of light intensity, flow rate and added amount of sediment once a week for nine weeks. Statistical experimental design and multivariate data analysis provided statistically significant regression models which subsequently were used to establish exposure–response relationship for photosynthetic efficiency as function of sediment coverage. For example, at 70% sediment coverage the photosynthetic efficiency was reduced 50% after 1–2 weeks of exposure, most likely due to reduced gas exchange. The exposure–response relationship can be used to establish threshold levels and impact categories for environmental monitoring
Laurent, Dimitri; Picot, Marie; Marsset, Tania; Droz, Laurence; Rabineau, Marina; Granjeon, Didier; Molliex, Stéphane
2017-04-01
The geometry and internal functioning of turbidite systems are relatively well-constrained today. However, the respective role of autogenic (topographic compensation, dynamics of turbidity currents…) and allogenic factors (tectonics, sea-level, climate) governing their architectural evolution is still under debate. The geometry of the Quaternary Congo Fan is characterized by successive sedimentary prograding/retrograding cycles bounded by upfan avulsions, reflecting a periodic control of sedimentation (Picot et al., 2016). Multi-proxy studies revealed a strong interplay between autogenic control and climate forcing as evidenced by changes in fluvial sediment supplies consistent with arid and humid periods in the Congo River Basin. In the light of these results, the aim of this study is to investigate the relative impact of internal and external forcing factors controlling, both in time and space, the formation and evolution of depocenters of the Congo Deep-Sea Fan since 210 ka. This work represents the first attempt to model in 3D the stratigraphic architecture of the Congo turbidite system using DionisosFlow (IFP-EN), a diffusion process-based software. It allows the simulation of sediment transport and the 3D geometry reproduction of sedimentary units based on physical processes such as sea level changes, tectonics, sediment supply and transport. According to the modeling results, the role of topographic compensation in the deep-sea fan geometry is secondary compared to climate changes in the drainage basin. It appears that a periodic variation of sediment discharge and water flow is necessary to simulate the timing and volume of prograding/retrograding sedimentary cycles and more particularly the upfan avulsion events. The best-fit simulations show that the overriding factor for such changes corresponds to the expansion of the vegetation cover in the catchment basin associated to the Milankovitch cycle of precession which controlled the West African Monsoon
Mwanamoki, Paola M; Devarajan, Naresh; Thevenon, Florian; Birane, Niane; de Alencastro, Luiz Felippe; Grandjean, Dominique; Mpiana, Pius T; Prabakar, Kandasamy; Mubedi, Josué I; Kabele, Christophe G; Wildi, Walter; Poté, John
2014-09-01
This paper discusses the occurrence and spatial distribution of metals and persistent organic pollutants (POPs: including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), Polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in sediments from a river-reservoir system. Surface sediments were sampled from thirteen sites of the Congo River Basin and Lake Ma Vallée, both situated in the vicinity of the capital city Kinshasa (Congo Democratic Republic). Sediment qualities were evaluated using toxicity test based on exposing Ostracods to the sediment samples. The highest metal concentrations were observed in sediments subjected to anthropogenic influences, urban runoff and domestic and industrial wastewaters, discharge into the Congo River basin. Ostracods exposed to the sediments resulted in 100% mortality rates after 6d of incubation, indicating the ultimate toxicity of these sediments as well as potential environmental risks. The POPs and PAHs levels in all sediment samples were low, with maximum concentration found in the sediments (area of pool Malebo): OCP value ranged from 0.02 to 2.50 with ∑OCPs: 3.3μgkg(-1); PCB ranged from 0.07 to 0.99 with Total PCBs (∑7×4.3): 15.31μgkg(-1); PAH value ranged from 0.12 to 9.39 with ∑PAHs: 63.89μgkg(-1). Our results indicate that the deterioration of urban river-reservoir water quality result mainly from urban stormwater runoff, untreated industrial effluents which discharge into the river-reservoirs, human activities and uncontrolled urbanization. This study represents useful tools incorporated to evaluate sediment quality in river-reservoir systems which can be applied to similar aquatic environments. Copyright © 2014 Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Dominicis, C. de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1961-07-01
The grand partition function Z ({alpha},{beta}) of a quantum system is studied, using diagrammatic representations of the perturbation expansion. For a fermions system, it is possible to show, by proper resummation, without approximations but under some 'regularity hypothesis', that Log Z ({alpha},{beta}) takes a form where, besides trivial dependences, {alpha} and {beta} only appear through a statistical factor F{sub k}{sup -} = [1 + e{sup -{alpha}}{sup +{beta}}{sup {epsilon}{sub k}{sup 0}}{sup -{beta}}{sup W{sub k}}]{sup -1}. W{sub k} is a (real) self-consistent potential, generalized to all orders and can be defined by a stationary condition on Log Z ({alpha},{beta}) under variations of F{sub k}{sup -}. The thermodynamical quantities take a form analogous to the expressions Landau introduced for the Fermi liquids. The zero temperature limit (for isotropic systems) gives back Goldstone expressions for the ground state of a system. (author) [French] La grande fonction de partition Z ({alpha},{beta}) d'un systeme quantique est etudiee en utilisant des representations diagrammatiques du developpement en serie des perturbations. Pour un systeme de fermions on peut, par des resommations adequates, sans approximations mais sous reserve d'une 'hypothese de regularite', mettre Log Z ({alpha},{beta}) sous une forme ou, en dehors de dependances triviales, {alpha} et {beta} n'interviennent que par l'intermediaire d'un facteur statistique F{sub k}{sup -} = [1 + e{sup -{alpha}}{sup +{beta}}{sup {epsilon}{sub k}{sup 0}}{sup -{beta}}{sup W{sub k}}]{sup -1}. W{sub k} est ici un potentiel self-consistant (reel) generalise a tous les ordres et peut etre defini par une condition de stationnarite de Log Z ({alpha},{beta}) pour des variations de F{sub k}{sup -}. Les grandeurs thermodynamiques prennent une forme analogue aux expressions que LANDAU a introduites pour les liquides de FERMI. A la limite de la temperature nulle (et pour un
Energy Technology Data Exchange (ETDEWEB)
Dominicis, C de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1961-07-01
The grand partition function Z ({alpha},{beta}) of a quantum system is studied, using diagrammatic representations of the perturbation expansion. For a fermions system, it is possible to show, by proper resummation, without approximations but under some 'regularity hypothesis', that Log Z ({alpha},{beta}) takes a form where, besides trivial dependences, {alpha} and {beta} only appear through a statistical factor F{sub k}{sup -} = [1 + e{sup -{alpha}}{sup +{beta}}{sup {epsilon}{sub k}{sup 0}}{sup -{beta}}{sup W{sub k}}]{sup -1}. W{sub k} is a (real) self-consistent potential, generalized to all orders and can be defined by a stationary condition on Log Z ({alpha},{beta}) under variations of F{sub k}{sup -}. The thermodynamical quantities take a form analogous to the expressions Landau introduced for the Fermi liquids. The zero temperature limit (for isotropic systems) gives back Goldstone expressions for the ground state of a system. (author) [French] La grande fonction de partition Z ({alpha},{beta}) d'un systeme quantique est etudiee en utilisant des representations diagrammatiques du developpement en serie des perturbations. Pour un systeme de fermions on peut, par des resommations adequates, sans approximations mais sous reserve d'une 'hypothese de regularite', mettre Log Z ({alpha},{beta}) sous une forme ou, en dehors de dependances triviales, {alpha} et {beta} n'interviennent que par l'intermediaire d'un facteur statistique F{sub k}{sup -} = [1 + e{sup -{alpha}}{sup +{beta}}{sup {epsilon}{sub k}{sup 0}}{sup -{beta}}{sup W{sub k}}]{sup -1}. W{sub k} est ici un potentiel self-consistant (reel) generalise a tous les ordres et peut etre defini par une condition de stationnarite de Log Z ({alpha},{beta}) pour des variations de F{sub k}{sup -}. Les grandeurs thermodynamiques prennent une forme analogue aux expressions que LANDAU a introduites pour les liquides de FERMI. A la limite de la temperature nulle (et pour un systeme isotrope) on retrouve terme a terme les
Tomar, Namrata; De, Rajat K.
2013-01-01
Response of an immune system to a pathogen attack depends on the balance between the host immune defense and the virulence of the pathogen. Investigation of molecular interactions between the proteins of a host and a pathogen helps in identifying the pathogenic proteins. It is necessary to understand the dynamics of a normally behaved host system to evaluate the capacity of its immune system upon pathogen attack. In this study, we have compared the behavior of an unperturbed and pathogen perturbed host system. Moreover, we have developed a formalism under Flux Balance Analysis (FBA) for the optimization of conflicting objective functions. We have constructed an integrated pathway system, which includes Staphylococcal Superantigen (SAg) expression regulatory pathway and TCR signaling pathway of Homo sapiens. We have implemented the method on this pathway system and observed the behavior of host signaling molecules upon pathogen attack. The entire study has been divided into six different cases, based on the perturbed/unperturbed conditions. In other words, we have investigated unperturbed and pathogen perturbed human TCR signaling pathway, with different combinations of optimization of concentrations of regulatory and signaling molecules. One of these cases has aimed at finding out whether minimization of the toxin production in a pathogen leads to the change in the concentration levels of the proteins coded by TCR signaling pathway genes in the infected host. Based on the computed results, we have hypothesized that the balance between TCR signaling inhibitory and stimulatory molecules can keep TCR signaling system into resting/stimulating state, depending upon the perturbation. The proposed integrated host-pathogen interaction pathway model has accurately reflected the experimental evidences, which we have used for validation purpose. The significance of this kind of investigation lies in revealing the susceptible interaction points that can take back the
Local perturbations perturb—exponentially–locally
International Nuclear Information System (INIS)
De Roeck, W.; Schütz, M.
2015-01-01
We elaborate on the principle that for gapped quantum spin systems with local interaction, “local perturbations [in the Hamiltonian] perturb locally [the groundstate].” This principle was established by Bachmann et al. [Commun. Math. Phys. 309, 835–871 (2012)], relying on the “spectral flow technique” or “quasi-adiabatic continuation” [M. B. Hastings, Phys. Rev. B 69, 104431 (2004)] to obtain locality estimates with sub-exponential decay in the distance to the spatial support of the perturbation. We use ideas of Hamza et al. [J. Math. Phys. 50, 095213 (2009)] to obtain similarly a transformation between gapped eigenvectors and their perturbations that is local with exponential decay. This allows to improve locality bounds on the effect of perturbations on the low lying states in certain gapped models with a unique “bulk ground state” or “topological quantum order.” We also give some estimate on the exponential decay of correlations in models with impurities where some relevant correlations decay faster than one would naively infer from the global gap of the system, as one also expects in disordered systems with a localized groundstate
Dim, Chidozie Izuchukwu Princeton; Onuoha, K. Mosto; Okeugo, Chukwudike Gabriel; Ozumba, Bertram Maduka
2017-06-01
Sequence stratigraphic studies have been carried out using subsurface well and 2D seismic data in the Late Cretaceous and Early Paleogene sediments of Anambra and proximal onshore section of Niger Delta Basin in the Southeastern Nigeria. The aim was to establish the stratigraphic framework for better understanding of the reservoir, source and seal rock presence and distribution in the basin. Thirteen stratigraphic bounding surfaces (consisting of six maximum flooding surfaces - MFSs and seven sequence boundaries - SBs) were recognized and calibrated using a newly modified chronostratigraphic chart. Stratigraphic surfaces were matched with corresponding foraminiferal and palynological biozones, aiding correlation across wells in this study. Well log sequence stratigraphic correlation reveals that stratal packages within the basin are segmented into six depositional sequences occurring from Late Cretaceous to Early Paleogene age. Generated gross depositional environment maps at various MFSs show that sediment packages deposited within shelfal to deep marine settings, reflect continuous rise and fall of sea levels within a regressive cycle. Each of these sequences consist of three system tracts (lowstand system tract - LST, transgressive system tract - TST and highstand system tract - HST) that are associated with mainly progradational and retrogradational sediment stacking patterns. Well correlation reveals that the sand and shale units of the LSTs, HSTs and TSTs, that constitute the reservoir and source/seal packages respectively are laterally continuous and thicken basinwards, due to structural influences. Result from interpretation of seismic section reveals the presence of hanging wall, footwall, horst block and collapsed crest structures. These structural features generally aid migration and offer entrapment mechanism for hydrocarbon accumulation. The combination of these reservoirs, sources, seals and trap elements form a good petroleum system that is viable
Non-Perturbative Renormalization
Mastropietro, Vieri
2008-01-01
The notion of renormalization is at the core of several spectacular achievements of contemporary physics, and in the last years powerful techniques have been developed allowing to put renormalization on a firm mathematical basis. This book provides a self-consistent and accessible introduction to the sophisticated tools used in the modern theory of non-perturbative renormalization, allowing an unified and rigorous treatment of Quantum Field Theory, Statistical Physics and Condensed Matter models. In particular the first part of this book is devoted to Constructive Quantum Field Theory, providi
Perturbative quantum chromodynamics
1989-01-01
This book will be of great interest to advanced students and researchers in the area of high energy theoretical physics. Being the most complete and updated review volume on Perturbative QCD, it serves as an extremely useful textbook or reference book. Some of the reviews in this volume are the best that have been written on the subject anywhere. Contents: Factorization of Hard Processes in QCD (J C Collins, D E Soper & G Sterman); Exclusive Processes in Quantum Chromodynamics (S J Brodsky & G P Lepage); Coherence and Physics of QCD Jets (Yu L Dokshitzer, V A Khoze & S I Troyan); Pomeron in Qu
Perturbative quantum chromodynamics
International Nuclear Information System (INIS)
Radyushkin, A.V.
1987-01-01
The latest achievements in perturbative quantum chromodynamics (QCD) relating to the progress in factorization of small and large distances are presented. The following problems are concerned: Development of the theory of Sudakov effects on the basis of mean contour formalism. Development of nonlocal condensate formalism. Calculation of hadron wave functions and hadron distribution functions using QCD method of sum rules. Development of the theory of Regge behaviour in QCD, behaviour of structure functions at small x. Study of polarization effects in hadron processes with high momentum transfer
Botello, A V; Villanueva, F S; Rivera, R F; Velandia, A L; de la Lanza, G E
2018-03-06
This study focused on dating of a sediment core from the Alvarado Lagoon System, Veracruz, Mexico, calculating the sedimentation rate by using 210 Pb to determine the tendency towards pollution by polycyclic aromatic hydrocarbons, organochlorides, the metals Cd, Cr, Cu, Hg, Ni, Pb, and V, and organic matter content. The activity of total Pb and supported Pb in the samples was 83.1 and 29.5 Bq kg -1 , respectively, whereas the average estimated sedimentation rate was 0.48 ± 0.09 cm per year -1 . The organic matter values exhibited linear behavior throughout the historical profile, with values under 2.5%. Metal concentrations followed the order V > Cr > Ni > Cu > Pb > Hg > Cd. Variations found in Cr, Ni, Pb, and V concentrations are basically due to three meteorological phenomena that hit the region: hurricanes Gladys, Hilda, and Janet in September of 1955. V, Ni, and Hg input comes from anthropogenic and lithogenic sources. The presence of individual polycyclic aromatic hydrocarbons showed no ascending accumulation pattern over time, nor did it show any significant statistical correlation to OM. As for the organochlorine pesticides, 63.61% of the total sum of these compounds were from the ciclodienics family. Concentration of p,p'-DDT was observed only in the earliest profile, from 1929.
International Nuclear Information System (INIS)
Luiz-Silva, Wanilson; Machado, Wilson; Matos, Rosa H.R.
2008-01-01
This paper records for the first time the contamination history and identifies the sources of 38 elements in sediments from the Santos-Cubatao Estuarine System (SE Brazil), at one of the most industrialized areas in Latin America. The compositions of samples from a 260 cm long sediment core collected in the Morrao River estuary were determined by ICP-MS. Enrichment factors, principal component analysis, correlation matrixes, and the characterization of geochemical signatures permitted a consistent data evaluation. Contaminant elements such as Cr, Mn, Ni, Zn, Ga, Ag, Cd, Sn, Sb, Pb, and Bi were associated with steel plant-derived Fe concentrations, while Be, Ca, Sc, Co, Cu, Sr, Y, Zr, Nb, Hf, Ta, Th, and U were associated with fertilizer industry-derived P concentrations. An overlap of sedimentary Fe distribution and local steel plant production indicated that Fe is a reliable marker of the contamination history, allowing the estimation of sedimentation rates over a period of 45 years of industrial activities. (author)
Perturbed effects at radiation physics
International Nuclear Information System (INIS)
Külahcı, Fatih; Şen, Zekâi
2013-01-01
Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed
Zaharia, C.
2017-08-01
Nowadays, wastewater (WW) treatment facilities are considered significant exposure pathways for solid particles, and also significant concerns of any quality conscious manufacturer. Most solid particles have some forms of organic coating either used as active material or to suspend and/or stabilize different present solid materials, having increase in toxicity that must be reduced, or sometimes even totally eliminated, especially if effluent is either discharged directly to surface water, or distributed through industrial water supplies. Representatives providing innovative technologies, comprehensive supports and expertise in wastewater and sludge treatment field are known, each one using modern treatment technology and facilities. Mechanical treatment is indispensable in primary treatment steps of both municipal and industrial WW applications, its main goal being separation of floating, settling and suspended materials (especially into a primary sedimentation-based treatment step). The aim of this work is to present comparatively the performance in solids removal of conventional mechanical WW treatment stages, especially those based on primary sedimentation, or sedimentation-like operations applied for Romanian urban WW treatment plants (serving two towns with ca 18,000 inhabitants), industrial WW treatment plants (deserving industries of vegetal food processing and organic chemicals’ manufacturing) and additional information on valorisation of separated solid material and improvement possibilities.
[Dynamics of 95Zr in simulated marine water-sediment-organisms system].
Wang, Chunlin; Shi, Jianjun; Sun, Pingyue; Li, Mingyun
2003-06-01
To provide scientific evidence to evaluate the behavior of 95Zr in ocean ecosystem, the dynamic model of the transference, accumulation and disappearance of 95Zr among the simulated marine water, sediment and organisms was investigated using Nassarius semiplicatus and Boleophthalums pectinirostris as experimental stuffs. The result showed that 95Zr(Bq.g-1 or Bq.ml-1) in the marine water was decreased more than 90% in the first 4 h, and then descended gradually. 95Zr in sediment was increased in the peak in 48 h and then declined. The radioactivity percent of 95Zr in the shell and muslce of Nassarius semiplicatus was 68.7% and 31.30% respectively, while the radioactivity percent was 22.80%, 12.64%, 34.82%, 10.31%, 4.48%, 11.55% and 3.71%, respectively in the fill, fin, viscera, skull, skin, vertebra and muscle of Boleophthalmus pectinirostris. Nassarius semiplicatus had a greater concentrating capability of 95Zr than Boleophthalmus pectinirostris. The order of the 95Zr concentration was found to be sediment > Nassarius semiplicatus > water > Boleophthalmus pectinirostris. A dynamic model of closed four-compartment was constructed with exponent function.
Non-perturbative versus perturbative renormalization of lattice operators
International Nuclear Information System (INIS)
Goeckeler, M.; Technische Hochschule Aachen; Horsley, R.; Ilgenfritz, E.M.; Oelrich, H.; Forschungszentrum Juelich GmbH; Schierholz, G.; Forschungszentrum Juelich GmbH; Perlt, H.; Schiller, A.; Rakow, P.
1995-09-01
Our objective is to compute the moments of the deep-inelastic structure functions of the nucleon on the lattice. A major source of uncertainty is the renormalization of the lattice operators that enter the calculation. In this talk we compare the renormalization constants of the most relevant twist-two bilinear quark operators which we have computed non-perturbatively and perturbatively to one loop order. Furthermore, we discuss the use of tadpole improved perturbation theory. (orig.)
International Nuclear Information System (INIS)
Hortellani, Marcos Antonio
2003-01-01
The distribution of mercury contamination in the Santos - Sao Vicente Estuarine System was observed through the analysis of seventy seven surface sediments samples collected in two series. In different periods and points, since the Channel of Piacaguera, the head of the system, , through the estuarine arms of Santos and Sao Vicente as far as the Bay of Santos, about 30 Km downstream, and in different mangrove areas, including industrial and harbor influence zones. The obtained values ranged from 0.03 to 1.19 μg g -1 About 90% of the samples of the first series collected among 1997-1998 and 50% of the second series collected among 1999-2000 presented levels of Hg > 0,13 μg g -1 ,limit considered by the Canadian legislation and adopted by CETESB, below which doesn't happen adverse effect in the biological community. And about 35% of samples of the first series and 11 % of the second series presented concentrations of Hg > 0.698 μg g -1 probable level of occurrence of adverse effect in the biological community. These results indicate an increase of the mercury levels caused by the industrial, port and urban activities. The mercury concentration in sediments was determined by using an Atomic Absorption Spectrophotometer, coupling with a flow injection system by a cold vapor generation, using a manual injection valve (FIA-CVAAS). The estimate of the uncertainties associated to this procedure was calculated. The following elements were also determined: Fe, Al, Zn, Ni, Pb, Cd, Cr and Co in 46 samples of the second series, by atomic absorption spectrometry. In order to verify possible relationship among all the investigated elements in the samples sediments, was carried out a statistical study, using the SPSS-8.0 software. Pearson correlation and Principal Component's analysis were used for with the objective to identify of major relationship for additional exploration of the general behavior of the data. (author)
Physico-chemical properties of perturbed water: facts and enigmas
Vittorio Elia
2012-01-01
Background The study of extremely diluted and agitated substances and solutions is strictly linked with the analysis of properties of water perturbed using different systems. This study is about the determination of the physical-chemical parameters of water, after the perturbations described. Methods The perturbed water was obtained using the three different protocols: Ã‚Â· EDS (Extremely Diluted Solutions). Obtained through an iterative process of ...
Perturbation studies on KAHTER
Energy Technology Data Exchange (ETDEWEB)
Rueckert, M.; Jonas, H.; Neef, R. D.
1974-10-15
The paper describes experimental and analytical results by both transport theory and diffusion theory calculations of perturbation tests in the KAHTER pebble bed critical experiment. The fission-weighted adjoint flux is measured from in-core detector responses by introducing a Cf-source into the core. Adjoint-weighted reactivities are calculated and compared to reactivity measurements for the introduction of a fuel and graphite pebble onto the top of the critical pile, the central rod worth, and the effect of replacing B4C with varying amounts of HfC in the central rod. In addition, analytical studies were made of the sensitivity of criticality to the fuel to graphite pebble ratio as measured in tests and of the effect of the upper void cavity as simulated in tests by placing cadmium layer across the top of the pebble pile to force a zero flux boundary condition.
Introduction to perturbation methods
Holmes, M
1995-01-01
This book is an introductory graduate text dealing with many of the perturbation methods currently used by applied mathematicians, scientists, and engineers. The author has based his book on a graduate course he has taught several times over the last ten years to students in applied mathematics, engineering sciences, and physics. The only prerequisite for the course is a background in differential equations. Each chapter begins with an introductory development involving ordinary differential equations. The book covers traditional topics, such as boundary layers and multiple scales. However, it also contains material arising from current research interest. This includes homogenization, slender body theory, symbolic computing, and discrete equations. One of the more important features of this book is contained in the exercises. Many are derived from problems of up- to-date research and are from a wide range of application areas.
Perturbation theory with instantons
International Nuclear Information System (INIS)
Carruthers, P.; Pinsky, S.S.; Zachariasen, F.
1977-05-01
''Perturbation theory'' rules are developed for calculating the effect of instantons in a pure Yang-Mills theory with no fermions, in the ''dilute gas'' approximation in which the N-instanton solution is assumed to be the sum of N widely separated one-instanton solutions. These rules are then used to compute the gluon propagator and proper vertex function including all orders of the instanton interaction but only to lowest order in the gluon coupling. It is to be expected that such an approximation is valid only for momenta q larger than the physical mass μ. The result is that in this regime instantons cause variations in the propagator and vertex of the form (μ 2 /q 2 )/sup -8π 2 b/ where b is the coefficient in the expansion of the β function: β = bg 3 +...
Curvature perturbations from dimensional decoupling
Giovannini, Massimo
2005-01-01
The scalar modes of the geometry induced by dimensional decoupling are investigated. In the context of the low energy string effective action, solutions can be found where the spatial part of the background geometry is the direct product of two maximally symmetric Euclidean manifolds whose related scale factors evolve at a dual rate so that the expanding dimensions first accelerate and then decelerate while the internal dimensions always contract. After introducing the perturbative treatment of the inhomogeneities, a class of five-dimensional geometries is discussed in detail. Quasi-normal modes of the system are derived and the numerical solution for the evolution of the metric inhomogeneities shows that the fluctuations of the internal dimensions provide a term that can be interpreted, in analogy with the well-known four-dimensional situation, as a non-adiabatic pressure density variation. Implications of this result are discussed with particular attention to string cosmological scenarios.
Zhao, Jian-Liang; Ying, Guang-Guo; Yang, Bin; Liu, Shan; Zhou, Li-Jun; Chen, Zhi-Feng; Lai, Hua-Jie
2011-10-01
This paper reports screening of multiple hormonal activities (estrogenic and androgenic activities, antiestrogenic and antiandrogenic activities) for surface water and sediment from the Pearl River system (Liuxi, Zhujiang, and Shijing rivers) in South China, using in vitro recombinant yeast bioassays. The detection frequencies for estrogenic and antiandrogenic activities were both 100% in surface water and 81 and 93% in sediment, respectively. The levels of estrogenic activity were 0.23 to 324 ng 17β-estradiol equivalent concentration (EEQ)/L in surface water and 0 to 101 ng EEQ/g in sediment. Antiandrogenic activities were in the range of 20.4 to 935 × 10(3) ng flutamide equivalent concentration (FEQ)/L in surface water and 0 to 154 × 10(3) ng FEQ/g in sediment. Moreover, estrogenic activity and antiandrogenic activity in sediment showed good correlation (R(2) = 0.7187), suggesting that the agonists of estrogen receptor and the antagonists of androgen receptor co-occurred in sediment. The detection frequencies for androgenic and antiestrogenic activities were 41 and 29% in surface water and 61 and 4% in sediment, respectively. The levels of androgenic activities were 0 to 45.4 ng dihydrotestosterone equivalent concentration (DEQ)/L in surface water, and the potency was very weak in the only detected sediment site. The levels of antiestrogenic activity were 0 to 1,296 × 10(3) ng tamoxifen equivalent concentration (TEQ)/L in surface water and 0 to 89.5 × 10(3) ng TEQ/g in sediment. The Shijing River displayed higher levels of hormonal activities than the Zhujiang and Liuxi rivers, indicating that the Shijing River had been suffering from heavy contamination with endocrine-disrupting chemicals. The equivalent concentrations of hormonal activities in some sites were greater than the lowest-observed-effect concentrations reported in the literature, suggesting potential adverse effects on aquatic organisms. Copyright © 2011 SETAC.
Singular perturbation of simple eigenvalues
International Nuclear Information System (INIS)
Greenlee, W.M.
1976-01-01
Two operator theoretic theorems which generalize those of asymptotic regular perturbation theory and which apply to singular perturbation problems are proved. Application of these theorems to concrete problems is involved, but the perturbation expansions for eigenvalues and eigenvectors are developed in terms of solutions of linear operator equations. The method of correctors, as well as traditional boundary layer techniques, can be used to apply these theorems. The current formulation should be applicable to highly singular ''hard core'' potential perturbations of the radial equation of quantum mechanics. The theorems are applied to a comparatively simple model problem whose analysis is basic to that of the quantum mechanical problem
International Nuclear Information System (INIS)
Pham Manh Hoai; Nguyen Thuy Ngoc; Nguyen Hung Minh; Pham Hung Viet; Berg, Michael; Alder, Alfredo C.; Giger, Walter
2010-01-01
The occurrence, temporal trend, sources and toxicity of PCBs and organochlorine pesticides were investigated in sediment samples from the sewer system of Hanoi City, including the rivers Nhue, To Lich, Lu, Set, Kim Nguu and the Yen So Lake. In general, the concentrations of the pollutants followed the order DDTs > PCBs > HCHs (β-HCH) > HCB. However, the pollution pattern was different for the DDTs and PCBs when the sampling locations were individually evaluated. The concentrations of the DDTs, PCBs, HCHs, and HCB ranged from 4.4 to 1100, 1.3 to 384, <0.2 to 36 and <0.2 to 22 ng/g d.w., respectively. These levels are higher than at any other location in Vietnam. Compared to measurements from 1997, the DDTs, PCBs, β-HCH and HCB levels show an increasing trend with DDT/DDE ratios, indicating very recent inputs into the environment although these persistent compounds are banned in Vietnam since 1995. - Organochlorine pesticides and PCBs were studied in sediments of the sewer system in Hanoi.
Barnard, Patrick L.; Erikson, Li H.; Elias, Edwin P.L.; Dartnell, Peter; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.
2013-01-01
The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7–8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.
Mubedi, Josué Ilunga; Devarajan, Naresh; Le Faucheur, Séverine; Mputu, John Kayembe; Atibu, Emmanuel K; Sivalingam, Periyasamy; Prabakar, Kandasamy; Mpiana, Pius T; Wildi, Walter; Poté, John
2013-10-01
Physicochemical and ecotoxicological analyses have been performed to assess the quality of sediments receiving untreated hospital effluents from Indian and Democratic Republic of Congo (DRC) hospitals. The sediments were collected monthly and characterized for grain size, organic matter, total organic carbon, total carbon, nitrogen, phosphorus, toxic metals and ecotoxicity. The results highlight the high concentration of toxic metals from the Indian hospital effluent receiving systems, especially for Cr, Cu, As, Zn and Hg. On the other hand, the metal concentrations in the sediment receiving system from DRC are low (e.g. maximum Hg and Zn concentration were 0.46 and 48.84 mg kg(-1) respectively). Ostracods exposed to sediment samples H2 (September month sample) and H3 (June and September month samples) were found dead after 6d of exposure whereas the higher mortality rate for Congo sediments was 23% but was accompanied with 33 ± 7% of growth inhibition. The results of this study show the variation of sediment composition on toxic metal levels as well as toxicity related to both, the type of hospitals and the sampling period. Additionally, hospital effluent disposal practices at the study sites can lead to the pollution of water resources and may generate risks for aquatic organisms and human health. Copyright © 2013 Elsevier Ltd. All rights reserved.
Geometric perturbation theory and plasma physics
International Nuclear Information System (INIS)
Omohundro, S.M.
1985-01-01
Modern differential geometric techniques are used to unify the physical asymptotics underlying mechanics, wave theory, and statistical mechanics. The approach gives new insights into the structure of physical theories and is suited to the needs of modern large-scale computer simulation and symbol manipulation systems. A coordinate-free formulation of non-singular perturbation theory is given, from which a new Hamiltonian perturbation structure is derived and related to the unperturbed structure in five different ways. The theory of perturbations in the presence of symmetry is developed, and the method of averaging is related to reduction by a circle-group action. The pseudo-forces and magnetic Poisson bracket terms due to reduction are given a natural asymptotic interpretation. Similar terms due to changing reference frames are related to the method of variation of parameters, which is also given a Hamiltonian formulation. These methods are used to answer a long-standing question posed by Kruskal about nearly periodic systems. The answer leads to a new secular perturbation theory that contains no adhoc elements, which is then applied to gyromotion. Eikonal wave theory is given a Hamiltonian formulation that generalizes Whitham's Lagrangian approach. The evolution of wave action density on ray phase space is given a Hamiltonian structure using a Lie-Poisson bracket. The relationship between dissipative and Hamiltonian systems is discussed. A theory motivated by free electron lasers gives new restrictions on the change of area of projected parallelepipeds under canonical transformations
Perturbation theory for arbitrary coupling strength?
Mahapatra, Bimal P.; Pradhan, Noubihary
2018-03-01
We present a new formulation of perturbation theory for quantum systems, designated here as: “mean field perturbation theory” (MFPT), which is free from power-series-expansion in any physical parameter, including the coupling strength. Its application is thereby extended to deal with interactions of arbitrary strength and to compute system-properties having non-analytic dependence on the coupling, thus overcoming the primary limitations of the “standard formulation of perturbation theory” (SFPT). MFPT is defined by developing perturbation about a chosen input Hamiltonian, which is exactly solvable but which acquires the nonlinearity and the analytic structure (in the coupling strength) of the original interaction through a self-consistent, feedback mechanism. We demonstrate Borel-summability of MFPT for the case of the quartic- and sextic-anharmonic oscillators and the quartic double-well oscillator (QDWO) by obtaining uniformly accurate results for the ground state of the above systems for arbitrary physical values of the coupling strength. The results obtained for the QDWO may be of particular significance since “renormalon”-free, unambiguous results are achieved for its spectrum in contrast to the well-known failure of SFPT in this case.
Mechanical perturbation control of cardiac alternans
Hazim, Azzam; Belhamadia, Youssef; Dubljevic, Stevan
2018-05-01
Cardiac alternans is a disturbance in heart rhythm that is linked to the onset of lethal cardiac arrhythmias. Mechanical perturbation control has been recently used to suppress alternans in cardiac tissue of relevant size. In this control strategy, cardiac tissue mechanics are perturbed via active tension generated by the heart's electrical activity, which alters the tissue's electric wave profile through mechanoelectric coupling. We analyze the effects of mechanical perturbation on the dynamics of a map model that couples the membrane voltage and active tension systems at the cellular level. Therefore, a two-dimensional iterative map of the heart beat-to-beat dynamics is introduced, and a stability analysis of the system of coupled maps is performed in the presence of a mechanical perturbation algorithm. To this end, a bidirectional coupling between the membrane voltage and active tension systems in a single cardiac cell is provided, and a discrete form of the proposed control algorithm, that can be incorporated in the coupled maps, is derived. In addition, a realistic electromechanical model of cardiac tissue is employed to explore the feasibility of suppressing alternans at cellular and tissue levels. Electrical activity is represented in two detailed ionic models, the Luo-Rudy 1 and the Fox models, while two active contractile tension models, namely a smooth variant of the Nash-Panfilov model and the Niederer-Hunter-Smith model, are used to represent mechanical activity in the heart. The Mooney-Rivlin passive elasticity model is employed to describe passive mechanical behavior of the myocardium.
International Nuclear Information System (INIS)
Harada, Masayasu
2009-01-01
Chiral perturbation theory has been used for great number of phenomenological analyses in low energy QCD as well as the lattice QCD analyses since the creation of the theory by Weinberg in 1979 followed by its consolidation by Gasser and Leutwyler in 1984 and 85. The theory is now the highly established one as the approach based on the effective field theory to search for Green function including quantum correlations in the frame of the systematic expansion technique using Lagrangian which includes all of the terms allowed by the symmetry. This review has been intended to describe how systematically physical quantities are calculated in the framework of the chiral symmetry. Consequently many of the various phenomenological analyses are not taken up here for which other reports are to be referred. Further views are foreseen to be developed based on the theory in addition to numbers of results reported up to the present. Finally π-π scattering is taken up to discuss to what energy scale the theory is available. (S. Funahashi)
International Nuclear Information System (INIS)
Fabris, J.D.
1977-01-01
The electric quadrupolar interaction in some hafnium complexes, measured at the metal nucleus level is studied. For that purpose, the technique of γ-γ perturbed angular correlation is used: the frequencies of quadrupolar interaction are compared with some hafnium α-hydroxicarboxilates, namely glycolate, lactate, mandelate and benzylate; the influence of the temperature on the quadrupolar coupling on the hafnium tetramandelate is studied; finally, the effects associated with the capture of thermal neutrons by hafnium tetramandelate are examined locally at the nuclear level. The first group of results shows significant differences in a series of complexes derived from glycolic acid. On the other hand, the substitution of the protons in hafnium tetramandelate structure by some alkaline cations permits to verify a correlation between the variations in the quadrupolar coupling and the electronegativities of the substituent elements. Measurements at high temperatures show that this complex is thermally stable at 100 and 150 0 C. It is possible to see the appearance of two distinct sites for the probe nucleus, after heating the sample at 100 0 C for prolonged time. This fact is attributed to a probable interconversion among the postulated structural isomers for the octacoordinated compounds. Finally, measurements of angular correlation on the irradiated complex show that there is an effective destruction of the target molecule by neutron capture [pt
Perturbative quantum chromodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1979-12-01
The application of QCD to hadron dynamics at short distances, where asymptotic freedom allows a systematic perturbative approach, is addressed. The main theme of the approach is to incorporate systematically the effects of the hadronic wave function in large momentum transfer exclusive and inclusive reactions. Although it is conventional to treat the hadron as a classical source of on-shell quarks, there are important dynamical effects due to hadronic constituent structure which lead to a broader testing ground for QCD. QCD predictions are discussed for exclusive processes and form factors at large momentum transfer in which the short-distance behavior and the finite compositeness of the hadronic wave functions play crucial roles. Many of the standard tests of QCD are reviewed including the predictions for R = sigma/sub e + e - →had//sigma/sub e + e - →μ + μ - /, the structure functions of hadrons and photons, jet phenomena, and the QCD corrections to deep inelastic processes. The exclusive-inclusive connection in QCD, the effects of power-law scale-breaking contributions, and the important role of the available energy in controlling logarithmic scale violations are also discussed. 150 references, 44 figures
Lattice regularized chiral perturbation theory
International Nuclear Information System (INIS)
Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.
2004-01-01
Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term
CERN. Geneva
2013-01-01
Perturbative QCD is the general theoretical framework for describing hard scattering processes yielding multiparticle production at hadron colliders. In these lectures, we shall introduce fundamental features of perturbative QCD and describe its application to several high energy collider processes, including jet production in electron-positron annihilation, deep inelastic scattering, Higgs boson and gauge boson production at the LHC.
Propagation of Ion Acoustic Perturbations
DEFF Research Database (Denmark)
Pécseli, Hans
1975-01-01
Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....
On summation of perturbation expansions
International Nuclear Information System (INIS)
Horzela, A.
1985-04-01
The problem of the restoration of physical quantities defined by divergent perturbation expansions is analysed. The Pad'e and Borel summability is proved for alternating perturbation expansions with factorially growing coefficients. The proof is based on the methods of the classical moments theory. 17 refs. (author)
Continual integral in perturbation theory
International Nuclear Information System (INIS)
Slavnov, A.A.
1975-01-01
It is shown that all results obtained by means of continual integration within the framework of perturbation theory are completely equivalent to those obtained by the usual diagram technique and are therfore just as rigorous. A rigorous justification is given for the rules for operating with continual integrals in perturbation theory. (author)
Dietrich, S.; Kleisinger, C.; Hillebrand, G.; Claus, E.; Schwartz, R.; Carls, I.; Winterscheid, A.; Schubert, B.
2016-12-01
Experiments to trace transport of sediments and suspended particulate matter on a river scale are an expensive and difficult venture, since it causes a lot of official requirements. In spring 2015, polychlorinated biphenyls (PCB) were released during restoration works at a bridge in the upper part of the Elbe River, near the Czech-German border. In this study, the particle-bound PCB-transport is applied as a tracer for monitoring transport pathways of suspended solids (SS) along a whole river stretch over 700 km length. The incident was monitored by concentration measurements of seven indicator PCB congeners along the inland part of the Elbe River as well as in the Elbe estuary. Data from 15 monitoring stations (settling tanks) as well as from two longitudinal campaigns (grab samples) along the river in July and August 2015 are considered. The total PCB load is calculated for all stations on the basis of monthly contaminant concentrations and daily suspended sediment concentrations. Monte-Carlo simulations assess the uncertainties of the calculated load. 1D water levels and GIS analysis were used to locate temporal storage areas for the SS. It is shown that the ratio of high versus low chlorinated PCB congeners is a suitable tracer to distinguish the PCB load of the incident from the long-term background signal. Furthermore, the reduction of total PCB load within the upper Elbe indicates that roughly 24% of the SS were transported with the water by wash load. Approximately 600 km downstream of the incident site, the PCB-marked wash load was first identified in July 2015. PCB load transported intermittently in suspension was detected roughly 400 km downstream of the incident site by August 2015. In the Elbe Estuary, PCB-marked SS were only found upstream of the steep slope of water depth (approx. 4 to 15 m) within Hamburg harbor that acts as a major sediment sink. Here, SS from the inland Elbe are mixed with lowly contaminated marine material, which may mask the
MCNP Perturbation Capability for Monte Carlo Criticality Calculations
International Nuclear Information System (INIS)
Hendricks, J.S.; Carter, L.L.; McKinney, G.W.
1999-01-01
The differential operator perturbation capability in MCNP4B has been extended to automatically calculate perturbation estimates for the track length estimate of k eff in MCNP4B. The additional corrections required in certain cases for MCNP4B are no longer needed. Calculating the effect of small design changes on the criticality of nuclear systems with MCNP is now straightforward
Singularly perturbed volterra integro-differential equations | Bijura ...
African Journals Online (AJOL)
Several investigations have been made on singularly perturbed integral equations. This paper aims at presenting an algorithm for the construction of asymptotic solutions and then provide a proof asymptotic correctness to singularly perturbed systems of Volterra integro-differential equations. Mathematics Subject
Generalizing genetical genomics : getting added value from environmental perturbation
Li, Yang; Breitling, Rainer; Jansen, Ritsert C.
2008-01-01
Genetical genomics is a useful approach for studying the effect of genetic perturbations on biological systems at the molecular level. However, molecular networks depend on the environmental conditions and, thus, a comprehensive understanding of biological systems requires studying them across
On dark energy isocurvature perturbation
International Nuclear Information System (INIS)
Liu, Jie; Zhang, Xinmin; Li, Mingzhe
2011-01-01
Determining the equation of state of dark energy with astronomical observations is crucially important to understand the nature of dark energy. In performing a likelihood analysis of the data, especially of the cosmic microwave background and large scale structure data the dark energy perturbations have to be taken into account both for theoretical consistency and for numerical accuracy. Usually, one assumes in the global fitting analysis that the dark energy perturbations are adiabatic. In this paper, we study the dark energy isocurvature perturbation analytically and discuss its implications for the cosmic microwave background radiation and large scale structure. Furthermore, with the current astronomical observational data and by employing Markov Chain Monte Carlo method, we perform a global analysis of cosmological parameters assuming general initial conditions for the dark energy perturbations. The results show that the dark energy isocurvature perturbations are very weakly constrained and that purely adiabatic initial conditions are consistent with the data
DEFF Research Database (Denmark)
Liu, Zhou
Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2......, 4 and 5, respectively. It is not the intention of the book to give a broad review of the literature on this very wide topic. The book tries to pick up information which is of engineering importance. An obstacle to the study of sedimentation is the scale effect in model tests. Whenever small...
International Nuclear Information System (INIS)
Arthur, Robson C.J.; Oliveira, Roberto A.S.; Bacchi, Osny O.S.; Correchel, Vladia; Santos, Dileia S.; Sparovek, Gerd
2007-01-01
With the increasing of occupation of the Brazilian Cerrado a series of environmental problems followed by the deforestation as soil erosion and soil compaction are appearing, and many of than are being related to the CT used. The NT cropping system which is being adopted more recently in the 'cerrado' region, has revealed benefic to the soil, mainly in terms of soil erosion control. The objective of the present work was to analyze the effect of the No Tillage NT and Conventional Tillage CT systems on the erosion process and to measure the efficiency of the riparian forest in trapping the sediments produced by erosion coming from crop areas cultivated by both systems trough the technique of 137Cs 'fallout' redistribution analysis. The study was carried out in Goiatuba/GO in two sampling dowslope transects located in areas of CT and NT cropping systems. Samples were taken from five points in transects of 200 and 140 meters long respectively, as well as from three soil profiles of a 30 m transect in the downstream riparian forests of each area. Incremental depth samples were also taken from two pits inside each transect in the forest down to 40 and 60 cm depth for the CT and NT respectively. The soil samples were air dried and sieved and the 137 Cs activity was analyzed for in a gamma ray detector (GEM-20180P, EG and ORTEC) coupled to a multichannel analyzer at CENA/USP. The results indicate variation of 137 Cs in soil profiles and high erosion rates for both cropping areas also indicate a movement of sediments from the two cropping areas to the riparian forest. (author)
Directory of Open Access Journals (Sweden)
Eric S Walsh
Full Text Available Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxyphenol (TCS, in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC (transport and fate proxy was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry and sand (transport and fate proxy were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary, which was validated with independent test samples. This decision-support tool performed well at the sub-estuary extent and provided the means to identify areas of concern and prioritize bay-wide sampling.
Energy Technology Data Exchange (ETDEWEB)
Silva, Larissa S.; Fávaro, Déborah I.T., E-mail: defavaro@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (LAN-CRPq/IPEN/CNEN-SP), São Paulo(Brazil). Lab. de Análise por Ativação Neutrônica; Ferreira, Francisco J. [Companhia Ambiental do Estado de São Paulo (ELAI/CETESB), Sao Paulo, SP (Brazil). Setor de Química Inorgânica
2017-07-01
Concentration and distribution of trace and rare earth elements in bottom sediment samples collected in the Billings System (including Rio Grande and Guarapiranga Reservoirs) were assessed by using Instrumental Neutron Activation (INAA). To evaluate the sources of anthropogenic contamination the enrichment factor (FE) and the geoacumulation index (IGeo) were calculated using NASC and Guarapiranga Park Soil as Reference Values. Results were compared to the concentration guideline values established by CCME (Canadian Council of Ministers of the Environment) environmental agency for As, Cr and Zn, and values in other published studies. Most points exceeded TEL values and, in some points, PEL values for these elements, indicating poor sediment quality in these reservoirs. In general terms, the elements As, Cr, Sb and Zn through EF and IGeo calculations present enrichment at all points analyzed, in both collection campaigns, except for the Rio Grande Reservoir points. The region where the reservoirs are located receive untreated sewage as well as pollution from urban occupation, industrial and mining activities, making it difficult to accurately identify the pollution sources. This study found higher concentrations of the elements analyzed in the Billings Reservoir, indicating a greater contamination level in relation to the other reservoirs. (author)
International Nuclear Information System (INIS)
Silva, Larissa S.; Fávaro, Déborah I.T.; Ferreira, Francisco J.
2017-01-01
Concentration and distribution of trace and rare earth elements in bottom sediment samples collected in the Billings System (including Rio Grande and Guarapiranga Reservoirs) were assessed by using Instrumental Neutron Activation (INAA). To evaluate the sources of anthropogenic contamination the enrichment factor (FE) and the geoacumulation index (IGeo) were calculated using NASC and Guarapiranga Park Soil as Reference Values. Results were compared to the concentration guideline values established by CCME (Canadian Council of Ministers of the Environment) environmental agency for As, Cr and Zn, and values in other published studies. Most points exceeded TEL values and, in some points, PEL values for these elements, indicating poor sediment quality in these reservoirs. In general terms, the elements As, Cr, Sb and Zn through EF and IGeo calculations present enrichment at all points analyzed, in both collection campaigns, except for the Rio Grande Reservoir points. The region where the reservoirs are located receive untreated sewage as well as pollution from urban occupation, industrial and mining activities, making it difficult to accurately identify the pollution sources. This study found higher concentrations of the elements analyzed in the Billings Reservoir, indicating a greater contamination level in relation to the other reservoirs. (author)
Enantio-selective molecular dynamics of (±)-o,p-DDT uptake and degradation in water-sediment system.
Ali, Imran; Alharbi, Omar M L; Alothman, Zeid A; Alwarthan, Abdulrahman
2018-01-01
Enantio-selective molecular dynamics of (±)-o,p-DDT uptake and degradation in water-sediment system is described. Both uptake and degradation processes of (-)-o,p-DDT were slightly higher than (+)-o,p-DDT enantiomer. The optimized parameters for uptake were 7.0μgL -1 concentration of o,p-DDT, 60min contact time, 5.0pH, 6.0gL -1 amount of reverine sediment and 25°C temperature. The maximum degradation of both (-)- and (+)-o,p-DDT was obtained with 16 days, 0.4μgL -1 concentration of o,p-DDT, pH 7 and 35°C temperature. Both uptake and degraded process followed first order rate reaction. Thermodynamic parameters indicated exothermic nature of uptake and degradation processes. Both uptake and degradation were slightly higher for (-)-enantiomer in comparison to (+)-enantiomer of o,p-DDT. It was concluded that both uptake and degradation processes are responsible for the removal of o,p-DDT from nature but uptake plays a crucial role. The percentage degradations of (-)- and (+)-o,p-DDT were 30.1 and 29.5, respectively. This study may be useful to manage o,p-DDT contamination of our earth's ecosystem. Copyright © 2017. Published by Elsevier Inc.
Underwater Sediment Sampling Research
2017-01-01
impacted sediments was found to be directly related to the concentration of crude oil detected in the sediment pore waters . Applying this mathematical...Kurt.A.Hansen@uscg.mil. 16. Abstract (MAXIMUM 200 WORDS ) The USCG R&D Center sought to develop a bench top system to determine the amount of total...scattered. The approach here is to sample the interstitial water between the grains of sand and attempt to determine the amount of oil in and on
International Nuclear Information System (INIS)
Zhang Kai; Wang Jizhong; Liang Bo; Zeng, Eddy Y.
2011-01-01
Sediment samples collected from downstream of the Dongjiang River, a highly urbanized river network within the Pearl River Delta of South China, were analyzed for 28 polycyclic aromatic hydrocarbons (PAHs). Total concentrations of 28 PAHs, 16 priority PAHs designated by the United States Environmental Protection Agency (USEPA) and the seven carcinogenic PAHs classified by the USEPA ranged from 480 to 4600, 100 to 3400 and 10 to 1700 ng/g dry weight, respectively. Principal component analysis-based stepwise multivariate linear regression showed that sediment PAHs were predominantly derived from coal combustion, refined fossil fuel combustion and oil spills, accounting for 37%, 32% and 23%, respectively, of the total loading. The levels of sediment PAHs remained steady from 2002 to 2008, during which fossil fuel consumption had doubled, probably reflecting efforts to control PAH emissions from fossil fuel combustion. Finally, use of natural gas and liquefied petroleum gas in automobiles should be encouraged to improve environmental quality. - Highlights: → PAHs in sediment showed similar input sources as those in air particles. → Combustion of fossil fuel is the predominant source for sediment PAHs. → Local efforts to control PAHs emissions from fossil fuel combustion were effective. → Promotion of natural gas and liquefied petroleum gas can reduce emissions of PAHs. - Occurrence of PAHs in surface sediments from a highly urbanized river system is assessed in relation to energy consumption patterns.
Batalla, Ramon J; Vericat, Damià
2011-04-01
Sediment flows naturally through the drainage network, from source areas to deposition zones. Sedimentary disequilibrium in rivers and coastlines is related to the imbalance within the fluvial system caused mostly by dams, instream mining, and changes in land use. This phenomenon is also responsible for ecological perturbations in rivers and streams. A broad need exists to establish comprehensive management strategies (soft measures) that would go beyond site-specific engineering practices (technical measures) typically taken to solve particular problems. Long-term programs are also required to monitor sediment transport in river basins, in order to assess the magnitude and variability of sediment transfer and potential deficits. This paper shows examples of rivers with important sediment disequilibrium in the Ebro and adjacent basins. These basins, like most in the Iberian Peninsula, experience sediment discontinuity in the catchment-river-coast system. Reservoir siltation is the main quantitative issue. Land use change and especially gravel mining downstream from dams accentuate the process. We also present and discuss recent developments on water and sediment management undertaken to improve the morphosedimentary dynamics of rivers. Copyright © 2010 SETAC.
Disformal transformation of cosmological perturbations
Directory of Open Access Journals (Sweden)
Masato Minamitsuji
2014-10-01
Full Text Available We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (nonconservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame.
Disformal transformation of cosmological perturbations
International Nuclear Information System (INIS)
Minamitsuji, Masato
2014-01-01
We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (non)conservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame
McGorum, Bruce C; Pirie, R Scott; Eaton, Samantha L; Keen, John A; Cumyn, Elizabeth M; Arnott, Danielle M; Chen, Wenzhang; Lamont, Douglas J; Graham, Laura C; Llavero Hurtado, Maica; Pemberton, Alan; Wishart, Thomas M
2015-11-01
Equine grass sickness (EGS) is an acute, predominantly fatal, multiple system neuropathy of grazing horses with reported incidence rates of ∼2%. An apparently identical disease occurs in multiple species, including but not limited to cats, dogs, and rabbits. Although the precise etiology remains unclear, ultrastructural findings have suggested that the primary lesion lies in the glycoprotein biosynthetic pathway of specific neuronal populations. The goal of this study was therefore to identify the molecular processes underpinning neurodegeneration in EGS. Here, we use a bottom-up approach beginning with the application of modern proteomic tools to the analysis of cranial (superior) cervical ganglion (CCG, a consistently affected tissue) from EGS-affected patients and appropriate control cases postmortem. In what appears to be the proteomic application of modern proteomic tools to equine neuronal tissues and/or to an inherent neurodegenerative disease of large animals (not a model of human disease), we identified 2,311 proteins in CCG extracts, with 320 proteins increased and 186 decreased by greater than 20% relative to controls. Further examination of selected proteomic candidates by quantitative fluorescent Western blotting (QFWB) and subcellular expression profiling by immunohistochemistry highlighted a previously unreported dysregulation in proteins commonly associated with protein misfolding/aggregation responses seen in a myriad of human neurodegenerative conditions, including but not limited to amyloid precursor protein (APP), microtubule associated protein (Tau), and multiple components of the ubiquitin proteasome system (UPS). Differentially expressed proteins eligible for in silico pathway analysis clustered predominantly into the following biofunctions: (1) diseases and disorders, including; neurological disease and skeletal and muscular disorders and (2) molecular and cellular functions, including cellular assembly and organization, cell
George, Richard J.
1992-01-01
Hydraulic properties of deeply weathered basement rocks and variably weathered sedimentary materials were measured by pumping and slug-test methods. Results from over 200 bores in 13 catchments, and eight pumping-test sites across the eastern and central wheatbelt of Western Australia were analysed. Measurements were made in each of the major lithological units, and emphasis placed on a ubiquitous basal saprolite aquifer. Comparisons were made between alternative drilling and analytical procedures to determine the most appropriate methods of investigation. Aquifers with an average hydraulic conductivity of 0.55 m day -1 occur in variably weathered Cainozoic sediments and poorly weathered saprolite grits (0.57 m day -1). These aquifers are separated by an aquitard (0.065 m day -1) comprising the mottled and pallid zones of the deeply weathered profile. Locally higher values of hydraulic conductivity occur in the saprolite aquifer, although after prolonged periods of pumping the values decrease until they are similar to those obtained from the slug-test methods. Hydraulic conductivities measured in bores drilled with rotary auger rigs were approximately an order of magnitude lower than those measured in the same material with bores drilled by the rotary air-blast method. Wheatbelt aquifers range from predominantly unconfined (Cainozoic sediments), to confined (saprolite grit aquifer). The poorly weathered saprolite grit aquifer has moderate to high transmissivities (4-50 m 2 day -1) and is capable of producing from less than 5 to over 230 kl day -1 of ground water, which is often of a quality suitable for livestock. Yields are influenced by the variability in the permeability of isovolumetrically weathered materials from which the aquifer is derived. The overlying aquitard has a low transmissivity (< 1 m 2 day -1), especially when deeply weathered, indurated and silicified. The transmissivity of the variably weathered sedimentary materials ranges from less than 0.5 m
Existence of localizing solutions in plasticity via the geometric singular perturbation theory
Lee, Min-Gi; Tzavaras, Athanasios
2017-01-01
system has fast and slow time scales, forming a singularly perturbed problem. Geometric singular perturbation theory is applied to this problem to achieve an invariant surface. The flow on the invariant surface is analyzed via the Poincaré
Cosmological perturbations beyond linear order
CERN. Geneva
2013-01-01
Cosmological perturbation theory is the standard tool to understand the formation of the large scale structure in the Universe. However, its degree of applicability is limited by the growth of the amplitude of the matter perturbations with time. This problem can be tackled with by using N-body simulations or analytical techniques that go beyond the linear calculation. In my talk, I'll summarise some recent efforts in the latter that ameliorate the bad convergence of the standard perturbative expansion. The new techniques allow better analytical control on observables (as the matter power spectrum) over scales very relevant to understand the expansion history and formation of structure in the Universe.
Instabilities in mimetic matter perturbations
Energy Technology Data Exchange (ETDEWEB)
Firouzjahi, Hassan; Gorji, Mohammad Ali [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Mansoori, Seyed Ali Hosseini, E-mail: firouz@ipm.ir, E-mail: gorji@ipm.ir, E-mail: shosseini@shahroodut.ac.ir, E-mail: shossein@ipm.ir [Physics Department, Shahrood University of Technology, P.O. Box 3619995161 Shahrood (Iran, Islamic Republic of)
2017-07-01
We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.
The theory of singular perturbations
De Jager, E M
1996-01-01
The subject of this textbook is the mathematical theory of singular perturbations, which despite its respectable history is still in a state of vigorous development. Singular perturbations of cumulative and of boundary layer type are presented. Attention has been given to composite expansions of solutions of initial and boundary value problems for ordinary and partial differential equations, linear as well as quasilinear; also turning points are discussed. The main emphasis lies on several methods of approximation for solutions of singularly perturbed differential equations and on the mathemat
Unique Fock quantization of scalar cosmological perturbations
Fernández-Méndez, Mikel; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.
2012-05-01
We investigate the ambiguities in the Fock quantization of the scalar perturbations of a Friedmann-Lemaître-Robertson-Walker model with a massive scalar field as matter content. We consider the case of compact spatial sections (thus avoiding infrared divergences), with the topology of a three-sphere. After expanding the perturbations in series of eigenfunctions of the Laplace-Beltrami operator, the Hamiltonian of the system is written up to quadratic order in them. We fix the gauge of the local degrees of freedom in two different ways, reaching in both cases the same qualitative results. A canonical transformation, which includes the scaling of the matter-field perturbations by the scale factor of the geometry, is performed in order to arrive at a convenient formulation of the system. We then study the quantization of these perturbations in the classical background determined by the homogeneous variables. Based on previous work, we introduce a Fock representation for the perturbations in which: (a) the complex structure is invariant under the isometries of the spatial sections and (b) the field dynamics is implemented as a unitary operator. These two properties select not only a unique unitary equivalence class of representations, but also a preferred field description, picking up a canonical pair of field variables among all those that can be obtained by means of a time-dependent scaling of the matter field (completed into a linear canonical transformation). Finally, we present an equivalent quantization constructed in terms of gauge-invariant quantities. We prove that this quantization can be attained by a mode-by-mode time-dependent linear canonical transformation which admits a unitary implementation, so that it is also uniquely determined.
Erkens, G.; Toonen, W.H.J.; Cohen, K.M.; Prins, M.A.
2013-01-01
During sediment transport downstream, river systems mix sediments from different parts of their catchments. During deposition, sediments are often unmixed again in different depositional environments (facies). During fluvial transport, between erosion and deposition of sediment, the sediment is
Where does cosmological perturbation theory break down?
International Nuclear Information System (INIS)
Armendariz-Picon, Cristian; Fontanini, Michele; Penco, Riccardo; Trodden, Mark
2009-01-01
It is often assumed that initial conditions for the evolution of a cosmological mode should be set at the time its physical wavelength reaches a cut-off of the order of the Planck length. Beyond that scale, trans-Planckian corrections to the dispersion relation are supposed to become dominant, leading to the breakdown of cosmological perturbation theory. In this paper, we apply the effective field theory approach to the coupled metric-inflaton system in order to calculate the corrections to the power spectrum of scalar and tensor perturbations induced by higher-dimension operators at short wavelengths. These corrections can be interpreted as modifications of the dispersion relation, and thus open a window to probe the validity of cosmological perturbation theory. Both for scalars and tensors, the modifications become important when the Hubble parameter is of the order of the Planck mass, or when the physical wave number of a cosmological perturbation mode approaches the square of the Planck mass divided by the Hubble constant. Thus, the cut-off length at which such a breakdown occurs is finite, but much smaller than the Planck length.
Radionuclides in water/suspended matter/sediment systems, and assessment of radiation burden
International Nuclear Information System (INIS)
1988-01-01
The 'General Instructions and Reference Values' (ABG) for calculating the radiation dose to the population from radioactive effluents discharged into the atmosphere or surface waters is the basis for assessing the dose commitment of the population with reference to the main exposure pathways. The ABG, however, contains little information on the deposition of radioactive substances with suspended matter in a river. Therefore, a number of specific studies have been carried out by various research institutes on behalf of the then competent Ministry of the Interior. The results are summarized in the book, methods and measuring programs are explained, and a full documentation of measured data and model parameters derived is given and discussed. The conclusions to be drawn from the field or laboratory analyses are set out, and are put together to build a more differentiating and hence more realistic model for assessing the radiation exposure of man due to contamination of sediments and sewage sludge. (orig./HP) With 83 figs., 52 tabs [de
Energy Technology Data Exchange (ETDEWEB)
Fitoussi, Caroline [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, (CSNSM) IN2P3/CNRS, Campus d' Orsay, Bat 108, 91405 Orsay (France)
2006-06-15
The recent observation of a {sup 60}Fe peak in a deep-sea ferro-manganese crust has been interpreted as due to a supernova explosion relatively close to the solar system 2.8 {+-} 0.4 Myr ago. To confirm this interpretation with better time-resolved measurements, and the simultaneous access, on the same sample, to other isotopes and geochemical phases, marine sediments seem to be a tool of choice. The objective of this work was to search for isotopic anomalies which would be characteristic for residues of this supernova. More specifically, {sup 129}I, {sup 60}Fe, and {sup 26}Al have been investigated, being measured by Accelerator Mass Spectrometry (AMS). Quantifying these nuclides' fluxes would help constrain stellar nucleosynthesis models. These residues are isotopes initially produced during hydrostatic and/or explosive nucleosynthesis. The physical conditions during the explosion (temperature, neutron density) are such that supernovae are thought to be good candidates for the astrophysical site of the r-process. The {sup 129}I study showed that measurement of pre-anthropogenic {sup 129}I/{sup 127}I ratios need a very strict control of the various potential {sup 129}I sources, especially when working with small quantities (micrograms) of iodine. This study revealed that the expected pre-anthropogenic {sup 129}I/{sup 127}I ratio for pre-nuclear samples in the marine environment shows a large discrepancy between theoretical calculations and experimental measurements. {sup 60}Fe and {sup 26}Al measurements allow us to conclude that, in the authigenic phase of the marine sediments, there is no {sup 60}Fe anomaly in the time interval defined by the signal found on the Fe-Mn crust (from 2.4 to 3.2 Myr), and no {sup 26}Al anomaly from 2.6 to 3.2 Myr. (author)