Two Dimensional Steady State Eddy Current Analysis of a Spinning Conducting Cylinder
2017-03-09
UNCLASSIFIED UNCLASSIFIED AD-E403 855 Technical Report ARMET-TR-16045 TWO-DIMENSIONAL STEADY-STATE EDDY CURRENT ANALYSIS OF A ...any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN...August 2014 4. TITLE AND SUBTITLE TWO-DIMENSIONAL STEADY-STATE EDDY CURRENT ANALYSIS OF A SPINNING CONDUCTING CYLINDER 5a. CONTRACT NUMBER 5b
On the existence of two-dimensional nonlinear steady states in plane Couette flow
Rincon, Francois
2007-01-01
The problem of two-dimensional steady nonlinear dynamics in plane Couette flow is revisited using homotopy from either plane Poiseuille flow or from plane Couette flow perturbed by a small symmetry-preserving identity operator. Our results show that it is not possible to obtain the nonlinear plane Couette flow solutions reported by Cherhabili and Ehrenstein [Eur. J. Mech. B/Fluids, 14, 667 (1995)] using their Poiseuille-Couette homotopy. We also demonstrate that the steady solutions obtained by Mehta and Healey [Phys. Fluids, 17, 4108 (2005)] for small symmetry-preserving perturbations are influenced by an artefact of the modified system of equations used in their paper. However, using a modified version of their model does not help to find plane Couette flow solution in the limit of vanishing symmetry-preserving perturbations either. The issue of the existence of two-dimensional nonlinear steady states in plane Couette flow remains unsettled.
Quasi-steady-state analysis of two-dimensional random intermittent search processes
Bressloff, Paul C.
2011-06-01
We use perturbation methods to analyze a two-dimensional random intermittent search process, in which a searcher alternates between a diffusive search phase and a ballistic movement phase whose velocity direction is random. A hidden target is introduced within a rectangular domain with reflecting boundaries. If the searcher moves within range of the target and is in the search phase, it has a chance of detecting the target. A quasi-steady-state analysis is applied to the corresponding Chapman-Kolmogorov equation. This generates a reduced Fokker-Planck description of the search process involving a nonzero drift term and an anisotropic diffusion tensor. In the case of a uniform direction distribution, for which there is zero drift, and isotropic diffusion, we use the method of matched asymptotics to compute the mean first passage time (MFPT) to the target, under the assumption that the detection range of the target is much smaller than the size of the domain. We show that an optimal search strategy exists, consistent with previous studies of intermittent search in a radially symmetric domain that were based on a decoupling or moment closure approximation. We also show how the decoupling approximation can break down in the case of biased search processes. Finally, we analyze the MFPT in the case of anisotropic diffusion and find that anisotropy can be useful when the searcher starts from a fixed location. © 2011 American Physical Society.
Computer model of two-dimensional solute transport and dispersion in ground water
Konikow, Leonard F.; Bredehoeft, J.D.
1978-01-01
This report presents a model that simulates solute transport in flowing ground water. The model is both general and flexible in that it can be applied to a wide range of problem types. It is applicable to one- or two-dimensional problems involving steady-state or transient flow. The model computes changes in concentration over time caused by the processes of convective transport, hydrodynamic dispersion, and mixing (or dilution) from fluid sources. The model assumes that the solute is non-reactive and that gradients of fluid density, viscosity, and temperature do not affect the velocity distribution. However, the aquifer may be heterogeneous and (or) anisotropic. The model couples the ground-water flow equation with the solute-transport equation. The digital computer program uses an alternating-direction implicit procedure to solve a finite-difference approximation to the ground-water flow equation, and it uses the method of characteristics to solve the solute-transport equation. The latter uses a particle- tracking procedure to represent convective transport and a two-step explicit procedure to solve a finite-difference equation that describes the effects of hydrodynamic dispersion, fluid sources and sinks, and divergence of velocity. This explicit procedure has several stability criteria, but the consequent time-step limitations are automatically determined by the program. The report includes a listing of the computer program, which is written in FORTRAN IV and contains about 2,000 lines. The model is based on a rectangular, block-centered, finite difference grid. It allows the specification of any number of injection or withdrawal wells and of spatially varying diffuse recharge or discharge, saturated thickness, transmissivity, boundary conditions, and initial heads and concentrations. The program also permits the designation of up to five nodes as observation points, for which a summary table of head and concentration versus time is printed at the end of the
U.S. Geological Survey, Department of the Interior — This digital data set defines the lateral boundary of the area simulated by the steady-state ground-water flow model of the Death Valley regional ground-water flow...
A two-dimensional MHD global coronal model - Steady-state streamers
Wang, A.-H.; Wu, S. T.; Suess, S. T.; Poletto, G.
1992-01-01
A 2D, time-dependent, numerical, MHD model for the simulation of coronal streamers from the solar surface to 15 solar is presented. Three examples are given; for dipole, quadrupole and hexapole (Legendre polynomials P1, P2, and P3) initial field topologies. The computed properties are density, temperature, velocity, and magnetic field. The calculation is set up as an initial-boundary value problem wherein a relaxation in time produces the steady state solution. In addition to the properties of the solutions, their accuracy is discussed. Besides solutions for dipole, quadrupole, and hexapole geometries, the model use of realistic values for the density and Alfven speed while still meeting the requirement that the flow speed be super-Alfvenic at the outer boundary by extending the outer boundary to 15 solar radii.
Zech, Alraune; Attinger, Sabine
2016-05-01
A new method is presented which allows interpreting steady-state pumping tests in heterogeneous isotropic transmissivity fields. In contrast to mean uniform flow, pumping test drawdowns in heterogeneous media cannot be described by a single effective or equivalent value of hydraulic transmissivity. An effective description of transmissivity is required, being a function of the radial distance to the well and including the parameters of log-transmissivity: mean, variance, and correlation length. Such a model is provided by the upscaling procedure radial coarse graining, which describes the transition of near-well to far-field transmissivity effectively. Based on this approach, an analytical solution for a steady-state pumping test drawdown is deduced. The so-called effective well flow solution is derived for two cases: the ensemble mean of pumping tests and the drawdown within an individual heterogeneous transmissivity field. The analytical form of the solution allows inversely estimating the parameters of aquifer heterogeneity. For comparison with the effective well flow solution, virtual pumping tests are performed and analysed for both cases, the ensemble mean drawdown and pumping tests at individual transmissivity fields. Interpretation of ensemble mean drawdowns showed proof of the upscaling method. The effective well flow solution reproduces the drawdown for two-dimensional pumping tests in heterogeneous media in contrast to Thiem's solution for homogeneous media. Multiple pumping tests conducted at different locations within an individual transmissivity field are analysed, making use of the effective well flow solution to show that all statistical parameters of aquifer heterogeneity can be inferred under field conditions. Thus, the presented method is a promising tool with which to estimate parameters of aquifer heterogeneity, in particular variance and horizontal correlation length of log-transmissivity fields from steady-state pumping test measurements.
Erpelding, Marion; Sinha, Santanu; Tallakstad, Ken Tore; Hansen, Alex; Flekkøy, Eirik Grude; Måløy, Knut Jørgen
2013-11-01
It is well known that the transient behavior during drainage or imbibition in multiphase flow in porous media strongly depends on the history and initial condition of the system. However, when the steady-state regime is reached and both drainage and imbibition take place at the pore level, the influence of the evolution history and initial preparation is an open question. Here, we present an extensive experimental and numerical work investigating the history dependence of simultaneous steady-state two-phase flow through porous media. Our experimental system consists of a Hele-Shaw cell filled with glass beads which we model numerically by a network of disordered pores transporting two immiscible fluids. From measurements of global pressure evolution, histograms of saturation, and cluster-size distributions, we find that when both phases are flowing through the porous medium, the steady state does not depend on the initial preparation of the system or on the way it has been reached.
User's manual for EVITS: a steady state fluids code for complex two-dimensional geometries
Energy Technology Data Exchange (ETDEWEB)
Domanus, H.M.
1976-07-01
A 2-D computer code, EVITS, has been developed for estimating steady state, incompressible, isothermal flow fields in complex geometries. A vorticity-stream function formulation is used along with a model to resolve viscous effects at solid boundaries. Sufficient geometry and boundary type options are included within the code so that a large number of flow situations can be specified without modifying the program. All instructions to the code are via an input dataset. Detailed instructions for preparing the user oriented input, along with examples, are included in this users' manual.
Zhou, Xiangzhi; Tsaftaris, Sotirios A; Liu, Ying; Tang, Richard; Klein, Rachel; Zuehlsdorff, Sven; Li, Debiao; Dharmakumar, Rohan
2010-04-01
To minimize image artifacts in long TR cardiac phase-resolved steady state free precession (SSFP) based blood-oxygen-level-dependent (BOLD) imaging. Nine healthy dogs (four male, five female, 20-25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath-held 2D SSFP cine sequences with various temporal resolutions (10-204 ms), bandwidths (239-930 Hz/pixel), with and without first-order motion compensation were prescribed in the basal, mid-ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact-reduction strategies. Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first-order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle. Artifact-reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP-based myocardial BOLD MRI. (c) 2010 Wiley-Liss, Inc.
Wong, Teresa; Solomatov, Viatcheslav S.
2015-12-01
The strongly temperature-dependent viscosity of rocks leads to the formation of nearly rigid lithospheric plates. Previous studies showed that a very low yield stress might be necessary to weaken and mobilize the plates, for example, due to water. However, the magnitude of the yield stress remains poorly understood. While the convective stresses below the lithosphere are relatively small, sublithospheric convection can induce large stresses in the lithosphere indirectly, through thermal thinning of the lithosphere. The magnitude of the thermal thinning, the stresses associated with it, and the critical yield stress to initiate subduction depend on several factors including the viscosity law, the Rayleigh number, and the aspect ratio of the convective cells. We conduct a systematic numerical analysis of lithospheric stresses and other convective parameters for single steady-state convection cells. Such cells can be considered as part of a multi-cell, time-dependent convective system. This allows us a better control of convective solutions and a relatively simple scaling analysis. We find that subduction initiation depends much stronger on the aspect ratio than in previous studies and speculate that plate tectonics initiation may not necessarily require significant weakening and can, at least in principle, start if a sufficiently long cell develops during planetary evolution.
Arnold, L.R.
2010-01-01
The Lost Creek Designated Ground Water Basin (Lost Creek basin) is an important alluvial aquifer for irrigation, public supply, and domestic water uses in northeastern Colorado. Beginning in 2005, the U.S. Geological Survey, in cooperation with the Lost Creek Ground Water Management District and the Colorado Water Conservation Board, collected hydrologic data and constructed a steady-state numerical groundwater flow model of the Lost Creek basin. The model builds upon the work of previous investigators to provide an updated tool for simulating the potential effects of various hydrologic stresses on groundwater flow and evaluating possible aquifer-management strategies. As part of model development, the thickness and extent of regolith sediments in the basin were mapped, and data were collected concerning aquifer recharge beneath native grassland, nonirrigated agricultural fields, irrigated agricultural fields, and ephemeral stream channels. The thickness and extent of regolith in the Lost Creek basin indicate the presence of a 2- to 7-mile-wide buried paleovalley that extends along the Lost Creek basin from south to north, where it joins the alluvial valley of the South Platte River valley. Regolith that fills the paleovalley is as much as about 190 ft thick. Average annual recharge from infiltration of precipitation on native grassland and nonirrigated agricultural fields was estimated by using the chloride mass-balance method to range from 0.1 to 0.6 inch, which represents about 1-4 percent of long-term average precipitation. Average annual recharge from infiltration of ephemeral streamflow was estimated by using apparent downward velocities of chloride peaks to range from 5.7 to 8.2 inches. Average annual recharge beneath irrigated agricultural fields was estimated by using passive-wick lysimeters and a water-balance approach to range from 0 to 11.3 inches, depending on irrigation method, soil type, crop type, and the net quantity of irrigation water applied
Shen, Shu-Huei; Guo, Wan-Yuo; Hung, Jeng-Hsiu
2007-09-01
To evaluate the value of two-dimensional fast imaging employing steady-state acquisition (2D FIESTA) cine MR with parallel imaging techniques in the diagnosis of fetal non-central nervous system (CNS) anomalies. A total of 28 pregnant women were referred for further MR evaluation on fetuses after abnormal sonographic results. A total of 33 fetal MR examinations were performed by a 1.5 T MR scanner with eight-channel phase-arrayed body coils. Single-shot fast spin-echo (SSFSE(R), GE) of three orthogonal planes and 2D FIESTA for cine fetal MR of three sagittal planes (midsagittal and 10 mm off midline on left and right) were routinely acquired. Additional planes on target organs with variable imaging frames were added if indicated. Nine of the 33 examinations (9/33; 27.3%) had motion artifacts obscuring the detail in SSFSE imaging; 2D FIESTA imaging provided motion-artifact-free imaging in all of them. Cine 2D FIESTA imaging provided additional information on the visceral peristalsis. The information helped in differentiating dilated gastrointestinal (GI) tract from other intraabdominal cystic lesions and in confirming the nature and level of GI tract obstruction. With sub-half-second temporal resolution of the 2D FIESTA sequences, fetal movement is no longer problematic. In addition to the anatomical information also provided by conventional SSFSE sequences, 2D FIESTA demonstrates information on motility and peristalsis of hollow organs and helps the diagnosis of fetal visceral anomalies. (c) 2007 Wiley-Liss, Inc.
U.S. Geological Survey, Department of the Interior — This digital geospatial data set contains the locations, values, and uncertainties of 700 hydraulic-head observations used in the steady-state, prepumped period of...
Kernodle, J.M.; Scott, W.B.
1986-01-01
As part of the Southwest Alluvial Basins study, model was constructed to simulate the alluvial aquifer system underlying the Albuquerque-Belen Basin. The model was used to simulate the steady-state flow condition assumed to have existed prior to 1960. Until this time there apparently were no long-term groundwater level changes of a significant magnitude outside the immediate vicinity of Albuquerque. Therefore, the construction of a steady-state flow model of the aquifer system based on reported hydrologic data predating 1960 was justified. During construction of the steady-state model, simulated hydraulic conductivity values were adjusted, within acceptable physical limits, until a best fit between measured or reported and computed heads at 34 control wells was achieved. The modeled area was divided into six sub-areas, or zones, within each of which hydraulic conductivity was assumed to be uniform. The model consisted of six layers for each of which simulated transmissivity was proportional to the layer thickness. Adjustments to simulated hydraulic conductivity values in the different zones resulted in final values that ranged from a low of 0.25 ft/day in the west to 50 ft/day in the eastern part of the basin. The error of the simulation, defined as the absolute difference between the computed and the measured or reported water level at the corresponding point in the physical system being modeled, ranged from 0.6 ft to 36 ft, with an average of 14.6 ft for the 34 control wells. (Author 's abstract)
Lefkoff, L.J.; Gorelick, S.M.
1987-01-01
A FORTRAN-77 computer program code that helps solve a variety of aquifer management problems involving the control of groundwater hydraulics. It is intended for use with any standard mathematical programming package that uses Mathematical Programming System input format. The computer program creates the input files to be used by the optimization program. These files contain all the hydrologic information and management objectives needed to solve the management problem. Used in conjunction with a mathematical programming code, the computer program identifies the pumping or recharge strategy that achieves a user 's management objective while maintaining groundwater hydraulic conditions within desired limits. The objective may be linear or quadratic, and may involve the minimization of pumping and recharge rates or of variable pumping costs. The problem may contain constraints on groundwater heads, gradients, and velocities for a complex, transient hydrologic system. Linear superposition of solutions to the transient, two-dimensional groundwater flow equation is used by the computer program in conjunction with the response matrix optimization method. A unit stress is applied at each decision well and transient responses at all control locations are computed using a modified version of the U.S. Geological Survey two dimensional aquifer simulation model. The program also computes discounted cost coefficients for the objective function and accounts for transient aquifer conditions. (Author 's abstract)
U.S. Geological Survey, Department of the Interior — This digital data set defines the boundary of the steady-state ground-water flow model built by IT Corporation (1996). The regional, 20-layer ground-water flow...
Juckem, Paul F.
2009-01-01
A regional, two-dimensional, areal ground-water-flow model was developed to simulate the ground-water-flow system and ground-water/surface-water interaction in the Rock River Basin. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Rock River Coalition. The objectives of the regional model were to improve understanding of the ground-water-flow system and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate ground-water/surface-water interactions, provide a framework for simulating regional ground-water-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate ground-water-flow patterns at multiple scales. The ground-water-flow model described in this report simulates the major hydrogeologic features of the modeled area, including bedrock and surficial aquifers, ground-water/surface-water interactions, and ground-water withdrawals from high-capacity wells. The steady-state model treats the ground-water-flow system as a single layer with hydraulic conductivity and base elevation zones that reflect the distribution of lithologic groups above the Precambrian bedrock and a regionally significant confining unit, the Maquoketa Formation. In the eastern part of the Basin where the shale-rich Maquoketa Formation is present, deep ground-water flow in the sandstone aquifer below the Maquoketa Formation was not simulated directly, but flow into this aquifer was incorporated into the GFLOW model from previous work in southeastern Wisconsin. Recharge was constrained primarily by stream base-flow estimates and was applied uniformly within zones guided by regional infiltration estimates for soils. The model includes average ground-water withdrawals from 1997 to 2006 for municipal wells and from 1997 to 2005 for high-capacity irrigation, industrial, and commercial wells. In addition
Einstein's steady-state cosmology
O'Raifeartaigh, Cormac
2014-09-01
Last year, a team of Irish scientists discovered an unpublished manuscript by Einstein in which he attempted to construct a "steady-state" model of the universe. Cormac O'Raifeartaigh describes the excitement of finding this previously unknown work.
Steady state magnetic field configurations for the earth's magnetotail
Hau, L.-N.; Wolf, R. A.; Voigt, G.-H.; Wu, C. C.
1989-01-01
A two-dimensional, force-balance magnetic field model is presented. The theoretical existence of a steady state magnetic field configuration that is force-balanced and consistent with slow, lossless, adiabatic, earthward convection within the limit of the ideal MHD is demonstrated. A numerical solution is obtained for a two-dimensional magnetosphere with a rectangular magnetopause and nonflaring tail. The results are consistent with the convection time sequences reported by Erickson (1985).
Steady-State Process Modelling
DEFF Research Database (Denmark)
2011-01-01
illustrate the “equation oriented” approach as well as the “sequential modular” approach to solving complex flowsheets for steady state applications. The applications include the Williams-Otto plant, the hydrodealkylation (HDA) of toluene, conversion of ethylene to ethanol and a bio-ethanol process.......This chapter covers the basic principles of steady state modelling and simulation using a number of case studies. Two principal approaches are illustrated that develop the unit operation models from first principles as well as through application of standard flowsheet simulators. The approaches...
Steady-State Process Modelling
DEFF Research Database (Denmark)
2011-01-01
This chapter covers the basic principles of steady state modelling and simulation using a number of case studies. Two principal approaches are illustrated that develop the unit operation models from first principles as well as through application of standard flowsheet simulators. The approaches i...
Steady state modeling of desiccant wheels
DEFF Research Database (Denmark)
Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin Ryhl
2014-01-01
Desiccant wheels are rotary desiccant dehumidifiers used in air conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete sys...... be taken into account in a future version of the model. More experimental data have to be gathered to implement eventual missing phenomena and validate the model for all input parameters....... systems. A steady state two-dimensional model is formulated and implemented aiming to obtain good accuracy and short computational times. Comparison with experimental data from the literature shows that the model reproduces the physical behavior of desiccant wheels. Mass diffusion in the desiccant should......Desiccant wheels are rotary desiccant dehumidifiers used in air conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete...
Steady-state properties of a finite system driven by a chemical-potential gradient
DEFF Research Database (Denmark)
Andersen, Jørgen Vitting; Mouritsen, Ole G.
1990-01-01
A two-dimensional lattice-gas model with repulsive interactions periodically infinite in one dimension and finite in the other is driven into a mass-transporting steady state by asymmetric chemical potentials applied at the open edges. By computer-simulation techniques the steady-state current...
Energy Technology Data Exchange (ETDEWEB)
1980-11-01
This national workshop on ground water and energy was conceived by the US Department of Energy's Office of Environmental Assessments. Generally, OEA needed to know what data are available on ground water, what information is still needed, and how DOE can best utilize what has already been learned. The workshop focussed on three areas: (1) ground water supply; (2) conflicts and barriers to ground water use; and (3) alternatives or solutions to the various issues relating to ground water. (ACR)
On the interpretation of recharge estimates from steady-state model calibrations.
Anderson, William P; Evans, David G
2007-01-01
Ground water recharge is often estimated through the calibration of ground water flow models. We examine the nature of calibration errors by considering some simple mathematical and numerical calculations. From these calculations, we conclude that calibrating a steady-state ground water flow model to water level extremes yields estimates of recharge that have the same value as the time-varying recharge at the time the water levels are measured. These recharge values, however, are a subdued version of the actual transient recharge signal. In addition, calibrating a steady-state ground water flow model to data collected during periods of rising water levels will produce recharge values that underestimate the actual transient recharge. Similarly, calibrating during periods of falling water levels will overestimate the actual transient recharge. We also demonstrate that average water levels can be used to estimate the actual average recharge rate provided that water level data have been collected for a sufficient amount of time.
Multimode optical fibers: steady state mode exciter.
Ikeda, M; Sugimura, A; Ikegami, T
1976-09-01
The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.
Non-Markovianity assisted Steady State Entanglement
Huelga, Susana F; Plenio, Martin B
2011-01-01
We analyze the dependence of steady state entanglement in a dimer system with a coherent exchange interaction and subject to local dephasing on the degree of Markovianity of the system-environment interaction. We demonstrate that non-Markovianity of the system-environment interaction is an essential resource that may support the formation of steady state entanglement whereas purely Markovian dynamics governed by Lindblad master equations results in separable steady states. This result illustrates possible mechanisms leading to long lived entanglement in purely decohering local environments. A feasible experimental demonstration of this non-Markovianity assisted steady state entanglement using a system of trapped ions is presented.
U.S. Geological Survey, Department of the Interior — This digital data set defines the boundary of the steady-state ground-water flow model built by IT Corporation (1996). The regional, 20-layer ground-water flow model...
Energy Technology Data Exchange (ETDEWEB)
Joan B. Blainey; Claudia C. Faunt, and Mary C. Hill
2006-05-16
This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.
DEFF Research Database (Denmark)
Bjerg, Poul Løgstrup
1996-01-01
Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588.......Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588....
DEFF Research Database (Denmark)
Bjerg, Poul Løgstrup
1996-01-01
Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588.......Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588....
Non-Markovianity-assisted steady state entanglement.
Huelga, Susana F; Rivas, Ángel; Plenio, Martin B
2012-04-20
We analyze the steady state entanglement generated in a coherently coupled dimer system subject to dephasing noise as a function of the degree of Markovianity of the evolution. By keeping fixed the effective noise strength while varying the memory time of the environment, we demonstrate that non-Markovianity is an essential, quantifiable resource that may support the formation of steady state entanglement whereas purely Markovian dynamics governed by Lindblad master equations lead to separable steady states. This result illustrates possible mechanisms leading to long-lived entanglement in purely decohering, possibly local, environments. We present a feasible experimental demonstration of this noise assisted phenomenon using a system of trapped ions.
PRO-GRADE: GIS toolkits for ground water recharge and discharge estimation.
Lin, Yu-Feng; Wang, Jihua; Valocchi, Albert J
2009-01-01
PRO-GRADE is an ESRI ArcGIS 9.2 plug-in package that consists of two separate toolkits: (1) the pattern recognition organizer for geographic information system (PRO-GIS) and (2) the ground water recharge and discharge estimator for GIS (GRADE-GIS). PRO-GIS is a collection of several existing image-processing algorithms into one user interface to offer the flexibility to extract spatial patterns according to the user's needs. GRADE-GIS is a ground water recharge and discharge estimation interface using a mass balance method that requires only hydraulic conductivity, water table, and bedrock elevation data for simulating two-dimensional steady-state unconfined aquifers. PRO-GRADE was developed to assist ongoing assessments of the water resources in Illinois and Wisconsin, and is being used to assist several ground water resource studies in several locations in the United States. The advantage of using PRO-GRADE is to enable fast production of initial recharge and discharge maps that can be further enhanced by using a follow-up ground water flow model with parameter estimation codes. PRO-GRADE leverages ArcGIS to provide a computer-assisted framework to support expert judgment in order to efficiently select alternative recharge and discharge maps that can be used as (1) guidelines for field study planning and decision making; (2) initial conditions for numerical simulation; and (3) screening for alternative model selection and prediction/parameter uncertainty evaluation. In addition, PRO-GRADE allows for more easy and rapid correlation of those maps with other hydrologically relevant geospatial data.
U.S. Geological Survey, Department of the Interior — These simulated potentiometric surface contours represent prepumping (or steady-state) conditions for model layer 1 of the Death Valley regional ground-water flow...
U.S. Geological Survey, Department of the Interior — These simulated potentiometric surface contours represent prepumping (or steady-state) conditions for model layer 16 of the Death Valley regional ground-water flow...
A steady state theory for processive cellulases
DEFF Research Database (Denmark)
Cruys-Bagger, Nicolaj; Olsen, Jens Elmerdahl; Præstgaard, Eigil;
2013-01-01
. This has significant kinetic implications, for example the maximal specific rate (Vmax/E0) for processive cellulases is much lower than the catalytic rate constant (kcat). We discuss how relationships based on this theory may be used in both comparative and mechanistic analyses of cellulases....... remains to be fully developed. In this paper, we suggest a deterministic kinetic model that relies on a processive set of enzyme reactions and a quasi steady-state assumption. It is shown that this approach is practicable in the sense that it leads to mathematically simple expressions for the steady......-state rate, and only requires data from standard assay techniques as experimental input. Specifically, it is shown that the processive reaction rate at steady state may be expressed by a hyperbolic function related to the conventional Michaelis–Menten equation. The main difference is a ‘kinetic processivity...
Multiple steady state phenomenon in martensitic transformation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Based on the basic facts that the martensitic transformation is a physical phenomenon which occurs in non-equilibrium conditions and there exists the feedback mechanism in the martensitic transformation, the dynamical processes of the isothermal and athermal martensitic transformations were analyzed by using nonlinear theory and a bifurcation theory model was established. It is shown that a multiple steady state phenomenon can take place as austenite is cooled, and the transitions of the steady state temperature between the branches of stable steady states can be considered the transformation from austenite to martensite. This model can estimate the starting temperature of the martensitic transformation and explain some experimental features of the martensitic transformation such as the effects of cooling rate, fluctuation and austenitic grain size on the martensitic transformation.
Leonard, A.R.
1960-01-01
One of the first requisites for the intelligent planning of utilization and control of water and for the administration of laws relating to its use is data on the quantity, quality, and mode of occurrence of the available supplies. The collection, evaluation and interpretation, and publication of such data are among the primary functions of the U.S. Geological Survey. Since 1895 the Congress has made appropriations to the Survey for investigation of the water resources of the Nation. In 1929 the Congress adopted the policy of dollar-for-dollar cooperation with the States and local governmental agencies in water-resources investigations of the U.S. Geological Survey. In 1937 a program of ground-water investigations was started in cooperation with the Oklahoma Geological Survey, and in 1949 this program was expanded to include cooperation with the Oklahoma Planning and Resources Board. In 1957 the State Legislature created the Oklahoma Water Resources Board as the principal State water agency and it became the principal local cooperator. The Ground Water Branch of the U.S. Geological Survey collects, analyzes, and evaluates basic information on ground-water resources and prepares interpretive reports based on those data. Cooperative ground-water work was first concentrated in the Panhandle counties. During World War II most work was related to problems of water supply for defense requirements. Since 1945 detailed investigations of ground-water availability have been made in 11 areas, chiefly in the western and central parts of the State. In addition, water levels in more than 300 wells are measured periodically, principally in the western half of the State. In Oklahoma current studies are directed toward determining the source, occurrence, and availability of ground water and toward estimating the quantity of water and rate of replenishment to specific areas and water-bearing formations. Ground water plays an important role in the economy of the State. It is
Steady-State Creep of Asphalt Concrete
Directory of Open Access Journals (Sweden)
Alibai Iskakbayev
2017-02-01
Full Text Available This paper reports the experimental investigation of the steady-state creep process for fine-grained asphalt concrete at a temperature of 20 ± 2 °С and under stress from 0.055 to 0.311 MPa under direct tension and was found to occur at a constant rate. The experimental results also determined the start, the end point, and the duration of the steady-state creep process. The dependence of these factors, in addition to the steady-state creep rate and viscosity of the asphalt concrete on stress is satisfactorily described by a power function. Furthermore, it showed that stress has a great impact on the specific characteristics of asphalt concrete: stress variation by one order causes their variation by 3–4.5 orders. The described relations are formulated for the steady-state of asphalt concrete in a complex stressed condition. The dependence is determined between stress intensity and strain rate intensity.
Locating CVBEM collocation points for steady state heat transfer problems
Hromadka, T.V.
1985-01-01
The Complex Variable Boundary Element Method or CVBEM provides a highly accurate means of developing numerical solutions to steady state two-dimensional heat transfer problems. The numerical approach exactly solves the Laplace equation and satisfies the boundary conditions at specified points on the boundary by means of collocation. The accuracy of the approximation depends upon the nodal point distribution specified by the numerical analyst. In order to develop subsequent, refined approximation functions, four techniques for selecting additional collocation points are presented. The techniques are compared as to the governing theory, representation of the error of approximation on the problem boundary, the computational costs, and the ease of use by the numerical analyst. ?? 1985.
Formulation and validation of a two-dimensional steady-state model of desiccant wheels
DEFF Research Database (Denmark)
Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin R.;
2015-01-01
Desiccant wheels are rotary desiccant dehumidifiers used in air-conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete...
U.S. Geological Survey, Department of the Interior — This digital data set defines the boundary of the ground-water flow model by D'Agnese and others (1997). This steady-state, 3-layer ground-water flow model was...
Steady State Analysis of Towed Marine Cables
Institute of Scientific and Technical Information of China (English)
WANG Fei; HUANG Guo-liang; DENG De-heng
2008-01-01
Efficient numerical schemes were presented for the steady state solutions of towed marine cables. For most of towed systems, the steady state problem can be resolved into two-point boundary-value problem, or initial value problem in some special cases where the initial values are available directly. A new technique was proposed and attempted to solve the two-point boundary-value problem rather than the conventional shooting method due to its algorithm complexity and low efficiency. First, the boundary conditions are transformed into a set of nonlinear governing equations about the initial values, then bisection method is employed to solve these nonlinear equations with the aid of 4th order Runge-Kutta method. In common sense, non-uniform (sheared) current is assumed, which varies in magnitude and direction with depth. The schemes are validated through the DE Zoysa's example, then several numerical examples are also presented to illustrate the numerical schemes.
Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3
Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.
2008-01-01
The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined
On Steady-State Tropical Cyclones
2014-01-01
circulation (Ooyama, 1969; Shapiro and Willoughby , 1982). Above the frictional boundary layer, this steady-state circulation must be along absolute angular...u′ sin λ〉 on the right-hand side of this equation. ‖According to axisymmetric balance dynamics (Ooyama, 1969; Shapiro and Willoughby , 1982), the...such as the diabatic heating rate and frictional and eddy processes (Shapiro and Willoughby , 1982; Shapiro and Montgomery, 1993; Vigh and Schubert, 2009
On Typicality in Nonequilibrium Steady States
Evans, Denis J.; Williams, Stephen R.; Searles, Debra J.; Rondoni, Lamberto
2016-08-01
From the statistical mechanical viewpoint, relaxation of macroscopic systems and response theory rest on a notion of typicality, according to which the behavior of single macroscopic objects is given by appropriate ensembles: ensemble averages of observable quantities represent the measurements performed on single objects, because " almost all" objects share the same fate. In the case of non-dissipative dynamics and relaxation toward equilibrium states, " almost all" is referred to invariant probability distributions that are absolutely continuous with respect to the Lebesgue measure. In other words, the collection of initial micro-states (single systems) that do not follow the ensemble is supposed to constitute a set of vanishing, phase space volume. This approach is problematic in the case of dissipative dynamics and relaxation to nonequilibrium steady states, because the relevant invariant distributions attribute probability 1 to sets of zero volume, while evolution commonly begins in equilibrium states, i.e., in sets of full phase space volume. We consider the relaxation of classical, thermostatted particle systems to nonequilibrium steady states. We show that the dynamical condition known as Ω T-mixing is necessary and sufficient for relaxation of ensemble averages to steady state values. Moreover, we find that the condition known as weak T-mixing applied to smooth observables is sufficient for ensemble relaxation to be independent of the initial ensemble. Lastly, we show that weak T-mixing provides a notion of typicality for dissipative dynamics that is based on the (non-invariant) Lebesgue measure, and that we call physical ergodicity.
Two-dimensional nonlinear nonequilibrium kinetic theory under steady heat conduction.
Hyeon-Deuk, Kim
2005-04-01
The two-dimensional steady-state Boltzmann equation for hard-disk molecules in the presence of a temperature gradient has been solved explicitly to second order in density and the temperature gradient. The two-dimensional equation of state and some physical quantities are calculated from it and compared with those for the two-dimensional steady-state Bhatnagar-Gross-Krook equation and information theory. We have found that the same kind of qualitative differences as the three-dimensional case among these theories still appear in the two-dimensional case.
On circulating power of steady state tokamaks
Energy Technology Data Exchange (ETDEWEB)
Itoh, Kimitaka [National Inst. for Fusion Science, Nagoya (Japan); Itoh, Sanae; Fukuyama, Atsushi; Yagi, Masatoshi
1996-03-01
Circulating power for the sustenance and profile control of the steady state tokamak plasmas is discussed. The simultaneous fulfillment of the MHD stability at high beta value, the improved confinement and the stationary equilibrium requires the rotation drive as well as the current drive. In addition to the current drive efficiency, the efficiency for the rotation drive is investigated. The direct rotation drive by the external torque, such as the case of beam injection, is not efficient enough. The mechanism and the magnitude of the spontaneous plasma rotation are studied. (author)
Energy repartition in the nonequilibrium steady state
Yan, Peng; Bauer, Gerrit E. W.; Zhang, Huaiwu
2017-01-01
The concept of temperature in nonequilibrium thermodynamics is an outstanding theoretical issue. We propose an energy repartition principle that leads to a spectral (mode-dependent) temperature in steady-state nonequilibrium systems. The general concepts are illustrated by analytic solutions of the classical Heisenberg spin chain connected to Langevin heat reservoirs with arbitrary temperature profiles. Gradients of external magnetic fields are shown to localize spin waves in a Wannier-Zeemann fashion, while magnon interactions renormalize the spectral temperature. Our generic results are applicable to other thermodynamic systems such as Newtonian liquids, elastic solids, and Josephson junctions.
Steady-state properties of driven magnetic reconnection in 2D electron magnetohydrodynamics.
Chacón, L; Simakov, Andrei N; Zocco, A
2007-12-07
We formulate a rigorous nonlinear analytical model that describes the dynamics of the diffusion (reconnection) region in driven systems in the context of electron magnetohydrodynamics (EMHD). A steady-state analysis yields allowed geometric configurations and associated reconnection rates. In addition to the well-known open X-point geometry, elongated configurations are found possible. The model predictions have been validated numerically with two-dimensional EMHD nonlinear simulations, and are in excellent agreement with previously published work.
Quasi-steady state conditions in heterogeneous aquifers during pumping tests
Zha, Yuanyuan; Yeh, Tian-Chyi J.; Shi, Liangsheng; Huang, Shao-Yang; Wang, Wenke; Wen, Jet-Chau
2017-08-01
Classical Thiem's well hydraulic theory, other aquifer test analyses, and flow modeling efforts often assume the existence of ;quasi-steady; state conditions. That is, while drawdowns due to pumping continue to grow, the hydraulic gradient in the vicinity of the pumping well does not change significantly. These conditions have built upon two-dimensional and equivalent homogeneous conceptual models, but few field data have been available to affirm the existence of these conditions. Moreover, effects of heterogeneity and three-dimensional flow on this quasi-steady state concept have not been thoroughly investigated and discussed before. In this study, we first present a quantitative definition of quasi-steady state (or steady-shape conditions) and steady state conditions based on the analytical solution of two- or three-dimensional flow induced by pumping in unbounded, homogeneous aquifers. Afterward, we use a stochastic analysis to investigate the influence of heterogeneity on the quasi-steady state concept in heterogeneous aquifers. The results of the analysis indicate that the time to reach an approximate quasi-steady state in a heterogeneous aquifer could be quite different from that estimated based on a homogeneous model. We find that heterogeneity of aquifer properties, especially hydraulic conductivity, impedes the development of the quasi-steady state condition before the flow reaching steady state. Finally, 280 drawdown-time data from the hydraulic tomographic survey conducted at a field site corroborate our finding that the quasi-steady state condition likely would not take place in heterogeneous aquifers unless pumping tests last a long period. Research significance (1) Approximate quasi-steady and steady state conditions are defined for two- or three-dimensional flow induced by pumping in unbounded, equivalent homogeneous aquifers. (2) Analysis demonstrates effects of boundary condition, well screen interval, and heterogeneity of parameters on the
Bailey, Z.C.; Imbrigiotta, T.E.
1982-01-01
An 88-square-mile segment of the White River valley contains an unconfined sand and gravel aquifer ranging-from a featheredge zero, to 120 feet in saturated thickness. Hydraulic conductivity is 340 feet per day, and transmissivity is as much as 35,000 square feet per day. The aquifer, recharged primarily by precipitation, gains same recharge through interbedded till and outwash boundaries and through losing streams. A two-dimensional digital model was used to simulate the steady-state ground-water flow system. Sensitivity analyses tested the reaction of the model to adjustments in hydraulic conductivity, steam bed leakance, and recharge. Simulated pumpage of 20-, 66-, and 122-million gallons per day reduced streamflow by 5, 15, and 30% , respectively. A real drawdown did not exceed 25 feet. Ground water was a calcium bicarbonate type having a median pH of 7.1, a mean alkalinity of 240 milligrams per liter, a mean hardness of 280 milligrams per liter, a mean dissolved oxygen concentration of 2.2 milligrams per liter, a mean redox potential of +347 millivolts, and a mean dissolved-solids concentration of 366 milligrams per liter. Iron and manganese concentrations exceeded National Drinking Water Regulations in 15 and 49% of the analyses, respectively. Temperature and concentration of dissolved organic carbon varied seasonally. Dissolved carbon and manganese varied with seasonally. Dissolved carbon and manganese varied with differing boundary material, till and bedrock. (USGS)
Magnetic sensor for steady state tokamak
Energy Technology Data Exchange (ETDEWEB)
Neyatani, Yuzuru; Mori, Katsuharu; Oguri, Shigeru; Kikuchi, Mitsuru [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment
1996-06-01
A new type of magnetic sensor has been developed for the measurement of steady state magnetic fields without DC-drift such as integration circuit. The electromagnetic force induced to the current which leads to the sensor was used for the measurement. For the high frequency component which exceeds higher than the vibration frequency of sensor, pick-up coil was used through the high pass filter. From the results using tokamak discharges, this sensor can measure the magnetic field in the tokamak discharge. During {approx}2 hours measurement, no DC drift was observed. The sensor can respond {approx}10ms of fast change of magnetic field during disruptions. We confirm the extension of measured range to control the current which leads to the sensor. (author).
Frozen steady states in active systems
Schaller, Volker; Hammerich, Benjamin; Frey, Erwin; Bausch, Andreas R
2011-01-01
Even simple active systems can show a plethora of intriguing phenomena and often we find complexity were we would have expected simplicity. One striking example is the occurrence of a quiescent or absorbing state with frozen fluctuations that at first sight seems to be impossible for active matter driven by the incessant input of energy. While such states were reported for externally driven systems through macroscopic shear or agitation, the investigation of frozen active states in inherently active systems like cytoskeletal suspensions or active gels is still at large. Using high density motility assay experiments, we demonstrate that frozen steady states can arise in active systems if active transport is coupled to growth processes. The experiments are complemented by agent-based simulations which identify the coupling between self-organization, growth and mechanical properties to be responsible for the pattern formation process.
Fluctuations When Driving Between Nonequilibrium Steady States
Riechers, P M
2016-01-01
Maintained by environmental fluxes, biological systems are thermodynamic processes that operate far from equilibrium without detailed-balance dynamics. Yet, they often exhibit well defined nonequilibrium steady states (NESSs). More importantly, critical thermodynamic functionality arises directly from transitions among their NESSs, driven by environmental switching. Here, we identify constraints on excess thermodynamic quantities that ride above the NESS housekeeping background. We do this by extending the Crooks fluctuation theorem to transitions among NESSs, without invoking an unphysical dual dynamics. This and corresponding integral fluctuation theorems determine how much work must be expended when controlling systems maintained far from equilibrium. This generalizes feedback control theory, showing that Maxwellian Demons can leverage mesoscopic-state information to take advantage of the excess energetics in NESS transitions. Altogether, these point to universal thermodynamic laws that are immediately app...
Interaction-induced mode switching in steady-state microlasers.
Ge, Li; Liu, David; Cerjan, Alexander; Rotter, Stefan; Cao, Hui; Johnson, Steven G; Türeci, Hakan E; Stone, A Douglas
2016-01-11
We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved modes maintain their identities, i.e. they do not change their spatial field patterns or lasing frequencies. For a fixed pump profile, a simple analytic criterion for the occurrence of IMS is given in terms of their self- and cross-interaction coefficients and non-interacting thresholds, which is verified for the example of a two-dimensional microdisk laser. When the spatial pump profile is varied as the pump power is increased, IMS can be induced even when it would not occur with a fixed pump profile, as we show for two coupled laser cavities. Our findings apply to steady-state lasing and are hence different from dynamical mode switching or hopping. IMS may have potential applications in robust and flexible all-optical switching.
Estimating the Ground Water Resources of Atoll Islands
Directory of Open Access Journals (Sweden)
Arne E. Olsen
2010-01-01
Full Text Available Ground water resources of atolls, already minimal due to the small surface area and low elevation of the islands, are also subject to recurring, and sometimes devastating, droughts. As ground water resources become the sole fresh water source when rain catchment supplies are exhausted, it is critical to assess current groundwater resources and predict their depletion during drought conditions. Several published models, both analytical and empirical, are available to estimate the steady-state freshwater lens thickness of small oceanic islands. None fully incorporates unique shallow geologic characteristics of atoll islands, and none incorporates time-dependent processes. In this paper, we provide a review of these models, and then present a simple algebraic model, derived from results of a comprehensive numerical modeling study of steady-state atoll island aquifer dynamics, to predict the ground water response to changes in recharge on atoll islands. The model provides an estimate thickness of the freshwater lens as a function of annual rainfall rate, island width, Thurber Discontinuity depth, upper aquifer hydraulic conductivity, presence or absence of a confining reef flat plate, and in the case of drought, time. Results compare favorably with published atoll island lens thickness observations. The algebraic model is incorporated into a spreadsheet interface for use by island water resources managers.
Impact of aquifer desaturation on steady-state river seepage
Morel-Seytoux, Hubert J.; Miracapillo, Cinzia; Mehl, Steffen
2016-02-01
Flow exchange between surface and ground water is of great importance be it for beneficial allocation and use of the water resources or for the proper exercise of water rights. That exchange can take place under a saturated or unsaturated flow regime. Which regimes occur depend on conditions in the vicinity of the interactive area. Withdrawals partially sustained by seepage may not bring about desaturation but greater amounts eventually will. The problem considered in this paper deals only with the steady-state case. It is meant as a first step toward a simple, yet accurate and physically based treatment of the transient situation. The primary purpose of the article is to provide simple criteria for determination of the initiation of desaturation in an aquifer originally in saturated hydraulic connection with a river or a recharge area. The extent of the unsaturated zone in the aquifer will increase with increasing withdrawals while at the same time the seepage rate from the river increases. However the seepage increase will stop once infiltration takes place strictly by gravity in the aquifer and is no longer opposed by the capillary rise from the water table below the riverbed. Following desaturation simple criteria are derived and simple analytical formulae provided to estimate the river seepage based on the position of the water table mound below the clogging layer and at some distance away from the river bank. They fully account for the unsaturated flow phenomena, including the existence of a drainage entry pressure. Two secondary objectives were to verify that (1) the assumption of uniform vertical flow through a clogging layer and that (2) the approximation of the water table mound below the seepage area as a flat surface were both reasonably legitimate. This approach will be especially advantageous for the implementation of the methodology in large-scale applications of integrated hydrologic models used for management.
Steady-state and non-steady state operation of counter-current chromatography devices.
Kostanyan, Artak E; Ignatova, Svetlana N; Sutherland, Ian A; Hewitson, Peter; Zakhodjaeva, Yulya A; Erastov, Andrey A
2013-11-01
Different variants of separation processes based on steady-state (continuous sample loading) and non-steady state (batch) operating modes of CCC columns have been analyzed and compared. The analysis is carried out on the basis of the modified equilibrium cell model, which takes into account both mechanisms of band broadening - interphase mass transfer and axial mixing. A full theoretical treatment of the intermittent counter-current chromatography with short sample loading time is performed. Analytical expressions are presented allowing the simulation of the intermittent counter-current chromatography separations for various experimental conditions. Chromatographic and extraction separations have been compared and advantages and disadvantages of the two methods have been evaluated. Further technical development of the CCC machines to implement counter-current extraction separations is considered.
Steady-state creep in the mantle
Directory of Open Access Journals (Sweden)
G. RANALLI
1977-06-01
Full Text Available SUMMARY - The creep equations for steady-state flow of olivine at high
pressure and temperature are compared in an attempt to elucidate the rheological
behaviour of the mantle. Results are presented in terms of applied deformation
maps and curves of effective viscosity v depth.
In the upper mantle, the transition stress between dislocation and diffusion
creep is between 10 to 102 bar (as orders of magnitude for grain sizes from
0.01 to 1 cm. The asthenosphere under continents is deeper, and has higher
viscosity, than under oceans. Predominance of one creep mechanism above the
others depends on grain size, strain rate, and volume fraction of melt; the
rheological response can be different for different geodynamic processes.
In the lower mantle, on the other hand, dislocation creep is predominant
at all realistic grain sizes and strain rates. If the effective viscosity has to be only
slightly higher than in the upper mantle, as some interpretations of glacioisostatic
rebound suggest, then the activation volume cannot be larger than
11 cm3 mole^1.
Steady State Vapor Bubble in Pool Boiling
Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.
2016-02-01
Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.
Steady State Vapor Bubble in Pool Boiling.
Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C; Maroo, Shalabh C
2016-02-03
Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.
Fluctuations When Driving Between Nonequilibrium Steady States
Riechers, Paul M.; Crutchfield, James P.
2017-08-01
Maintained by environmental fluxes, biological systems are thermodynamic processes that operate far from equilibrium without detailed-balanced dynamics. Yet, they often exhibit well defined nonequilibrium steady states (NESSs). More importantly, critical thermodynamic functionality arises directly from transitions among their NESSs, driven by environmental switching. Here, we identify the constraints on excess heat and dissipated work necessary to control a system that is kept far from equilibrium by background, uncontrolled "housekeeping" forces. We do this by extending the Crooks fluctuation theorem to transitions among NESSs, without invoking an unphysical dual dynamics. This and corresponding integral fluctuation theorems determine how much work must be expended when controlling systems maintained far from equilibrium. This generalizes thermodynamic feedback control theory, showing that Maxwellian Demons can leverage mesoscopic-state information to take advantage of the excess energetics in NESS transitions. We also generalize an approach recently used to determine the work dissipated when driving between functionally relevant configurations of an active energy-consuming complex system. Altogether, these results highlight universal thermodynamic laws that apply to the accessible degrees of freedom within the effective dynamic at any emergent level of hierarchical organization. By way of illustration, we analyze a voltage-gated sodium ion channel whose molecular conformational dynamics play a critical functional role in propagating action potentials in mammalian neuronal membranes.
Ground water and climate change
Taylor, R.G.; Scanlon, B.; Döll, P.; Rodell, M.; Beek, R. van; Wada, Y.; Longuevergne, L.; Leblanc, M.; Famiglietti, J.S.; Edmunds, M.; Konikow, L.; Green, T.R.; Chen, J.; Taniguchi, M.; Bierkens, M.F.P.; MacDonald, A.; Fan, Y.; Maxwell, R.M.; Yechieli, Y.; Gurdak, J.J.; Allen, D.M.; Shamsudduha, M.; Hiscock, K.; Yeh, Pat J.-F.; Holman, Ian; Treidel, Holger
2012-01-01
As the world’s largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate chang
Ground water and climate change
Taylor, R.G.; Scanlon, B.; Döll, P.; Rodell, M.; Beek, R. van; Wada, Y.; Longuevergne, L.; Leblanc, M.; Famiglietti, J.S.; Edmunds, M.; Konikow, L.; Green, T.R.; Chen, J.; Taniguchi, M.; Bierkens, M.F.P.; MacDonald, A.; Fan, Y.; Maxwell, R.M.; Yechieli, Y.; Gurdak, J.J.; Allen, D.M.; Shamsudduha, M.; Hiscock, K.; Yeh, Pat J.-F.; Holman, Ian; Treidel, Holger
2012-01-01
As the world’s largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate
Constrained optimal steady-state control for isolated traffic intersections
Institute of Scientific and Technical Information of China (English)
Jack HADDAD; David MAHALEL; Ilya IOSLOVICH; Per-Olof GUTMAN
2014-01-01
The steady-state or cyclic control problem for a simplified isolated traffic intersection is considered. The optimization problem for the green-red switching sequence is formulated with the help of a discrete-event max-plus model. Two steady-state control problems are formulated: optimal steady-state with green duration constraints, and optimal steady-state control with lost time. In the case when the criterion is a strictly increasing, linear function of the queue lengths, the steady-state control problems can be solved analytically. The structure of constrained optimal steady-state traffic control is revealed, and the effect of the lost time on the optimal solution is illustrated.
Wang, Jai-Ching
1994-01-01
The lateral solute segregation that results from a curved solid-liquid interface shape during steady state unidirectional solidification of a binary alloy system has been studied both analytically and numerically by Coriell, Bosivert, Rehm, and Sekerka. The system under their study is a two dimensional rectangular system. However, most real growth systems are cylindrical systems. Thus, in a previous study, we have followed Coriell etc. formalism and obtained analytical results for lateral solute segregation for an azimuthal symmetric cylindrical binary melt system during steady state solidification process. The solid-liquid interface shape is expressed as a series combination of Bessel functions. In this study a computer program has been developed to simulate the lateral solute segregation.
Oki, Delwyn S.
1998-01-01
A two-dimensional, finite-difference, ground-water flow model was developed for the central Oahu flow system, which is the largest and most productive ground-water flow system on the island. The model is based on the computer code SHARP which simulates both freshwater and saltwater flow. The ground-water model was developed using average pumping and recharge conditions during the 1950's, which was considered to be a steady-state period. For 1950's conditions, model results indicate that 62 percent (90.1 million gallons per day) of the discharge from the Schofield ground-water area flows southward and the remaining 38 percent (55.2 million gallons per day) of the discharge from Schofield flows northward. Although the contribution of recharge from infiltration of rainfall and irrigation water directly on top of the southern and northern Schofield ground-water dams was included in the model, the distribution of natural discharge from the Schofield ground-water area was estimated exclusive of the recharge on top of the dams. The model was used to investigate the long-term effects of pumping under future land-use conditions. Future recharge was conservatively estimated by assuming no recharge associated with agricultural activities. Future pumpage used in the model was based on the 1995-allocated rates. Model results indicate that the long-term effect of pumping at the 1995-allocated rates will be a reduction of water levels from present (1995) conditions in all ground-water areas of the central Oahu flow system. In the Schofield ground-water area, model results indicate that water levels could decline about 30 feet from the 1995 water-level altitude of about 275 feet. In the remaining ground-water areas of the central Oahu flow system, water levels may decline from less than 1 foot to as much as 12 feet relative to 1995 water levels. Model results indicate that the bottoms of several existing deep wells in northern and southern Oahu extend below the model
Vogel, K.L.; Reif, A.G.
1993-01-01
The 54-square-mile Red Clay Creek Basin, located in the lower Delaware River Basin, is underlain primarily by metamorphic rocks that range from Precambrian to Lower Paleozoic in age. Ground water flows through secondary openings in fractured crystalline rock and through primary openings below the water table in the overlying saprolite. Secondary porosity and permeability vary with hydrogeologic unit, topographic setting, and depth. Thirty-nine percent of the water-bearing zones are encountered within 100 feet of the land surface, and 79 percent are within 200 feet. The fractured crystalline rock and overlying saprolite act as a single aquifer under unconfined conditions. The water table is a subdued replica of the land surface. Local ground-water flow systems predominate in the basin, and natural ground-water discharge is to streams, comprising 62 to 71 percent of streamflow. Water budgets for 1988-90 for the 45-square-mile effective drainage area above the Woodale, Del., streamflow-measurement station show that annual precipitation ranged from 43.59 to 59.14 inches and averaged 49.81 inches, annual streamflow ranged from 15.35 to 26.33 inches and averaged 20.24 inches, and annual evapotranspiration ranged from 27.87 to 30.43 inches and averaged 28.98 inches. The crystalline rocks of the Red Clay Creek Basin were simulated two-dimensionally as a single aquifer under unconfined conditions. The model was calibrated for short-term steady-state conditions on November 2, 1990. Recharge was 8.32 inches per year. Values of aquifer hydraulic conductivity in hillside topographic settings ranged from 0.07 to 2.60 feet per day. Values of streambed hydraulic conductivity ranged from 0.08 to 26.0 feet per day. Prior to simulations where ground-water development was increased, the calibrated steady-state model was modified to approximate long-term average conditions in the basin. Base flow of 11.98 inches per year and a ground-water evapotranspiration rate of 2.17 inches per
Ground water and climate change
Taylor, Richard G.; Scanlon, Bridget; Döll, Petra; Rodell, Matt; van Beek, Rens; Wada, Yoshihide; Longuevergne, Laurent; Leblanc, Marc; Famiglietti, James S.; Edmunds, Mike; Konikow, Leonard; Green, Timothy R.; Chen, Jianyao; Taniguchi, Makoto; Bierkens, Marc F.P.; MacDonald, Alan; Fan, Ying; Maxwell, Reed M.; Yechieli, Yossi; Gurdak, Jason J.; Allen, Diana M.; Shamsudduha, Mohammad; Hiscock, Kevin; Yeh, Pat J.-F.; Holman, Ian; Treidel, Holger
2012-01-01
As the world's largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate change as more frequent and intense climate extremes (droughts and floods) increase variability in precipitation, soil moisture and surface water. Here we critically review recent research assessing the impacts of climate on ground water through natural and human-induced processes as well as through groundwater-driven feedbacks on the climate system. Furthermore, we examine the possible opportunities and challenges of using and sustaining groundwater resources in climate adaptation strategies, and highlight the lack of groundwater observations, which, at present, limits our understanding of the dynamic relationship between ground water and climate.
Ground water and climate change
Taylor, Richard G.; Scanlon, Bridget; Döll, Petra; Rodell, Matt; van Beek, Rens; Wada, Yoshihide; Longuevergne, Laurent; Leblanc, Marc; Famiglietti, James S.; Edmunds, Mike; Konikow, Leonard; Green, Timothy R.; Chen, Jianyao; Taniguchi, Makoto; Bierkens, Marc F. P.; MacDonald, Alan; Fan, Ying; Maxwell, Reed M.; Yechieli, Yossi; Gurdak, Jason J.; Allen, Diana M.; Shamsudduha, Mohammad; Hiscock, Kevin; Yeh, Pat J.-F.; Holman, Ian; Treidel, Holger
2013-04-01
As the world's largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate change as more frequent and intense climate extremes (droughts and floods) increase variability in precipitation, soil moisture and surface water. Here we critically review recent research assessing the impacts of climate on ground water through natural and human-induced processes as well as through groundwater-driven feedbacks on the climate system. Furthermore, we examine the possible opportunities and challenges of using and sustaining groundwater resources in climate adaptation strategies, and highlight the lack of groundwater observations, which, at present, limits our understanding of the dynamic relationship between ground water and climate.
Ground Water and Climate Change
Taylor, Richard G.; Scanlon, Bridget; Doell, Petra; Rodell, Matt; van Beek, Rens; Wada, Yoshihide; Longuevergne, Laurent; Leblanc, Marc; Famiglietti, James S.; Edmunds, Mike; Konikow, Leonard; Green, Timothy R.; Chen, Jianyao; Taniguchi, Makoto; Bierkens, Marc F. P.; MacDonald, Alan; Fan, Ying; Maxwell, Reed M.; Yechieli, Yossi; Gurdak, Jason J.; Allen, Diana M.; Shamsudduha, Mohammad; Hiscock, Kevin; Yeh, Pat J. -F; Holman, Ian; Treidel, Holger
2013-01-01
As the world's largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate change as more frequent and intense climate extremes (droughts and floods) increase variability in precipitation, soil moisture and surface water. Here we critically review recent research assessing the impacts of climate on ground water through natural and human-induced processes as well as through groundwater-driven feedbacks on the climate system. Furthermore, we examine the possible opportunities and challenges of using and sustaining groundwater resources in climate adaptation strategies, and highlight the lack of groundwater observations, which, at present, limits our understanding of the dynamic relationship between ground water and climate.
Particle Velocity Fluctuations in Steady State Sedimentation: Stratification Controlled Correlations
Segrè, P N
2007-01-01
The structure and dynamics of steady state sedimentation of semi-concentrated ($\\phi=0.10$) monodisperse spheres are studied in liquid fluidized beds. Laser turbidity and particle imaging methods are used to measure the particle velocity fluctuations and the steady state concentration profiles. Using a wide range of particle and system sizes, we find that the measured gradients $\
Coexistence Steady States in a Predator-Prey Model
Walker, Christoph
2010-01-01
An age-structured predator-prey system with diffusion and Holling-Tanner-type nonlinearities is considered. Regarding the intensity of the fertility of the predator as bifurcation parameter, we prove that a branch of positive coexistence steady states bifurcates from the marginal steady state with no prey. A similar result is obtained when the fertility of the prey varies.
Steady-State Performance of Kalman Filter for DPLL
Institute of Scientific and Technical Information of China (English)
QIAN Yi; CUI Xiaowei; LU Mingquan; FENG Zhenming
2009-01-01
For certain system models, the structure of the Kalman filter is equivalent to a second-order vari-able gain digital phase-locked loop (DPLL). To apply the knowledge of DPLLs to the design of Kalman filters, this paper studies the steady-state performance of Kalman filters for these system models. The results show that the steady-state Kalman gain has the same form as the DPLL gain. An approximate simple form for the steady-state Kalman gain is used to derive an expression for the equivalent loop bandwidth of the Kalman filter as a function of the process and observation noise variances. These results can be used to analyze the steady-state performance of a Kalman filter with DPLL theory or to design a Kalman filter model with the same steady-state performance as a given DPLL.
Steady State of Pedestrian Flow in Bottleneck Experiments
Liao, Weichen; Seyfried, Armin; Chraibi, Mohcine; Drzycimski, Kevin; Zheng, Xiaoping; Zhao, Ying
2015-01-01
Experiments with pedestrians could depend strongly on initial conditions. Comparisons of the results of such experiments require to distinguish carefully between transient state and steady state. In this work, a feasible algorithm - Cumulative Sum Control Chart - is proposed and improved to automatically detect steady states from density and speed time series of bottleneck experiments. The threshold of the detection parameter in the algorithm is calibrated using an autoregressive model. Comparing the detected steady states with previous manually selected ones, the modified algorithm gives more reproducible results. For the applications, three groups of bottleneck experiments are analysed and the steady states are detected. The study about pedestrian flow shows that the difference between the flows in all states and in steady state mainly depends on the ratio of pedestrian number to bottleneck width. When the ratio is higher than a critical value (approximately 115 persons/m), the flow in all states is almost ...
Steady states and stability in metabolic networks without regulation.
Ivanov, Oleksandr; van der Schaft, Arjan; Weissing, Franz J
2016-07-21
Metabolic networks are often extremely complex. Despite intensive efforts many details of these networks, e.g., exact kinetic rates and parameters of metabolic reactions, are not known, making it difficult to derive their properties. Considerable effort has been made to develop theory about properties of steady states in metabolic networks that are valid for any values of parameters. General results on uniqueness of steady states and their stability have been derived with specific assumptions on reaction kinetics, stoichiometry and network topology. For example, deep results have been obtained under the assumptions of mass-action reaction kinetics, continuous flow stirred tank reactors (CFSTR), concordant reaction networks and others. Nevertheless, a general theory about properties of steady states in metabolic networks is still missing. Here we make a step further in the quest for such a theory. Specifically, we study properties of steady states in metabolic networks with monotonic kinetics in relation to their stoichiometry (simple and general) and the number of metabolites participating in every reaction (single or many). Our approach is based on the investigation of properties of the Jacobian matrix. We show that stoichiometry, network topology, and the number of metabolites that participate in every reaction have a large influence on the number of steady states and their stability in metabolic networks. Specifically, metabolic networks with single-substrate-single-product reactions have disconnected steady states, whereas in metabolic networks with multiple-substrates-multiple-product reactions manifolds of steady states arise. Metabolic networks with simple stoichiometry have either a unique globally asymptotically stable steady state or asymptotically stable manifolds of steady states. In metabolic networks with general stoichiometry the steady states are not always stable and we provide conditions for their stability. In order to demonstrate the biological
Osserman, Robert
2011-01-01
The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o
Juday, Richard D. (Inventor)
1992-01-01
A two-dimensional vernier scale is disclosed utilizing a cartesian grid on one plate member with a polar grid on an overlying transparent plate member. The polar grid has multiple concentric circles at a fractional spacing of the spacing of the cartesian grid lines. By locating the center of the polar grid on a location on the cartesian grid, interpolation can be made of both the X and Y fractional relationship to the cartesian grid by noting which circles coincide with a cartesian grid line for the X and Y direction.
Modeled ground water age distributions
Woolfenden, Linda R.; Ginn, Timothy R.
2009-01-01
The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.
Institute of Scientific and Technical Information of China (English)
Shu-hai ZHANG; Xiao-gang DENG; Mei-liang MAO; Chi-Wang SHU
2013-01-01
The convergence to steady state solutions of the Euler equations for weighted compact nonlinear schemes (WCNS) [Deng X.and Zhang H.(2000),J.Comput.Phys.165,22-44 and Zhang S.,Jiang S.and Shu C.-W.(2008),J.Comput.Phys.227,7294-7321] is studied through numerical tests.Like most other shock capturing schemes,WCNS also suffers from the problem that the residue can not settle down to machine zero for the computation of the steady state solution which contains shock waves but hangs at the truncation error level.In this paper,the techniques studied in [Zhang S.and Shu.C.-W.(2007),J.Sci.Comput.31,273-305 and Zhang S.,Jiang S and Shu.C.-W.(2011),J.Sci.Comput.47,216-238],to improve the convergence to steady state solutions for WENO schemes,are generalized to the WCNS.Detailed numerical studies in one and two dimensional cases are performed.Numerical tests demonstrate the effectiveness of these techniques when applied to WCNS.The residue of various order WCNS can settle down to machine zero for typical cases while the small post-shock oscillations can be removed.
Steady-state decoupling and design of linear multivariable systems
Thaler, G. J.
1974-01-01
A constructive criterion for decoupling the steady states of a linear time-invariant multivariable system is presented. This criterion consists of a set of inequalities which, when satisfied, will cause the steady states of a system to be decoupled. Stability analysis and a new design technique for such systems are given. A new and simple connection between single-loop and multivariable cases is found. These results are then applied to the compensation design for NASA STOL C-8A aircraft. Both steady-state decoupling and stability are justified through computer simulations.
Enhancement of the steady-state magnetization in TROSY experiments
Energy Technology Data Exchange (ETDEWEB)
Riek, Roland [Institut fuer Molekularbiologie und Biophysik Eidgenoessische Technische Hochschule Hoenggerberg (Switzerland)], E-mail: rr@mol.biol.ethz.ch
2001-10-15
Under the condition that the longitudinal relaxation time of spin I is shorter than the longitudinal relaxation time of spin S the steady-state magnetization in [S,I]-TROSY-type experiments can be enhanced by intermediate storage of a part of the steady-state magnetization of spin I on spin S with a pulse sequence element during the relaxation delay. It is demonstrated with samples ranging in size from the 1 kDa cyclosporin to the 110 kDa {sup 15}N,{sup 2}H-labeled dihydroneopterin Aldolase that intermediate storage of steady-state magnetization in a [{sup 15}N,{sup 1}H]-TROSY experiment yields a signal gain of 10-25%. The method proposed here for intermediate storage of steady-state magnetization can be implemented in any [{sup 15}N,{sup 1}H]-TROSY-type experiments.
Steady state and time resolved spectroscopy of photoswitchable systems
Hou, Lili
2013-01-01
Steady state en time resolved spectroscopie zijn twee fundamentele methodes voor het bestuderen van fotochemische processen. In dit proefschrift zijn drie zelf-opgezette spectroscopische systemen beschreven, waarmee samen met andere spectroscopische methoden verscheidende met licht schakelbare syste
Two-dimensional optical spectroscopy
Cho, Minhaeng
2009-01-01
Discusses the principles and applications of two-dimensional vibrational and optical spectroscopy techniques. This book provides an account of basic theory required for an understanding of two-dimensional vibrational and electronic spectroscopy.
Analytic description of adaptive network topologies in a steady state.
Wieland, Stefan; Nunes, Ana
2015-06-01
In many complex systems, states and interaction structure coevolve towards a dynamic equilibrium. For the adaptive contact process, we obtain approximate expressions for the degree distributions that characterize the interaction network in such active steady states. These distributions are shown to agree quantitatively with simulations except when rewiring is much faster than state update and used to predict and to explain general properties of steady-state topologies. The method generalizes easily to other coevolutionary dynamics.
Steady-state leaching of tritiated water from silica gel
DEFF Research Database (Denmark)
Das, H.A.; Hou, Xiaolin
2009-01-01
Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion.......Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion....
Steady-state leaching of tritiated water from silica gel
DEFF Research Database (Denmark)
Das, H.A.; Hou, Xiaolin
2009-01-01
Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion.......Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion....
Dumouchelle, D.H.; Schalk, C.W.; Rowe, G.L.; De Roche, J.T.
1993-01-01
Ground water is the primary source of water in the Wright-Patterson Air Force Base area. The aquifer consists of glacial sands and gravels that fill a buried bedrock-valley system. Consolidated rocks in the area consist of poorly permeable Ordovician shale of the Richmondian stage, in the upland areas, the Brassfield Limestone of Silurian age. The valleys are filled with glacial sediments of Wisconsinan age consisting of clay-rich tills and coarse-grained outwash deposits. Estimates of hydraulic conductivity of the shales based on results of displacement/recovery tests range from 0.0016 to 12 feet per day; estimates for the glacial sediments range from less than 1 foot per day to more than 1,000 feet per day. Ground water flow from the uplands towards the valleys and the major rivers in the region, the Great Miami and the Mad Rivers. Hydraulic-head data indicate that ground water flows between the bedrock and unconsolidated deposits. Data from a gain/loss study of the Mad River System and hydrographs from nearby wells reveal that the reach of the river next to Wright-Patterson Air Force Base is a ground-water discharge area. A steady-state, three-dimensional ground-water-flow model was developed to simulate ground-water flow in the region. The model contains three layers and encompasses about 100 square miles centered on Wright-Patterson Air Force Base. Ground water enters the modeled area primarily by river leakage and underflow at the model boundary. Ground water exits the modeled area primarily by flow through the valleys at the model boundaries and through production wells. A model sensitivity analysis involving systematic changes in values of hydrologic parameters in the model indicates that the model is most sensitive to decreases in riverbed conductance and vertical conductance between the upper two layers. The analysis also indicates that the contribution of water to the buried-valley aquifer from the bedrock that forms the valley walls is about 2 to 4
Regression modeling of ground-water flow
Cooley, R.L.; Naff, R.L.
1985-01-01
Nonlinear multiple regression methods are developed to model and analyze groundwater flow systems. Complete descriptions of regression methodology as applied to groundwater flow models allow scientists and engineers engaged in flow modeling to apply the methods to a wide range of problems. Organization of the text proceeds from an introduction that discusses the general topic of groundwater flow modeling, to a review of basic statistics necessary to properly apply regression techniques, and then to the main topic: exposition and use of linear and nonlinear regression to model groundwater flow. Statistical procedures are given to analyze and use the regression models. A number of exercises and answers are included to exercise the student on nearly all the methods that are presented for modeling and statistical analysis. Three computer programs implement the more complex methods. These three are a general two-dimensional, steady-state regression model for flow in an anisotropic, heterogeneous porous medium, a program to calculate a measure of model nonlinearity with respect to the regression parameters, and a program to analyze model errors in computed dependent variables such as hydraulic head. (USGS)
Multiple steady states in coupled flow tank reactors
Hunt, Katharine L. C.; Kottalam, J.; Hatlee, Michael D.; Ross, John
1992-05-01
Coupling between continuous-flow, stirred tank reactors (CSTR's), each having multiple steady states, can produce new steady states with different concentrations of the chemical species in each of the coupled tanks. In this work, we identify a kinetic potential ψ that governs the deterministic time evolution of coupled tank reactors, when the reaction mechanism permits a single-variable description of the states of the individual tanks; examples include the iodate-arsenous acid reaction, a cubic model suggested by Noyes, and two quintic models. Stable steady states correspond to minima of ψ, and unstable steady states to maxima or saddle points; marginally stable states typically correspond to saddle-node points. We illustrate the variation in ψ due to changes in the rate constant for external material intake (k0) and for exchange between tanks (kx). For fixed k0 values, we analyze the changes in numbers and types of steady states as kx increases from zero. We show that steady states disappear by pairwise coalescence; we also show that new steady states may appear with increasing kx, when the reaction mechanism is sufficiently complex. For fixed initial conditions, the steady state ultimately reached in a mixing experiment may depend on the exchange rate constant as a function of time, kx(t) : Adiabatic mixing is obtained in the limit of slow changes in kx(t) and instantaneous mixing in the limit as kx(t)→∞ while t remains small. Analyses based on the potential ψ predict the outcome of mixing experiments for arbitrary kx(t). We show by explicit counterexamples that a prior theory developed by Noyes does not correctly predict the instability points or the transitions between steady states of coupled tanks, to be expected in mixing experiments. We further show that the outcome of such experiments is not connected to the relative stability of steady states in individual tank reactors. We find that coupling may effectively stabilize the tanks. We provide
Geomorphic and Thermal Steady State Regimes: Reality or Wishful Thinking?
Lock, J.; Furlong, K.
2003-04-01
In many tectonic geomorphic studies, it is assumed that rates of uplift within an orogen are matched by rates of exhumation producing a steady-state orogen. However, the tools used to determine exhumation are thermally driven (e.g. Fission Track, U-Th/He) and exhumation can substantially perturb the crustal thermal regime. Since knowing the thermal regime is key to determining exhumation from thermochronology, problems arise. In order to interpret a rate of exhumation we make the assumption that an area is in thermal 'steady state', which in young active orogens unlikely exists. Taiwan, the Southern Alps, Fiordland, and Nanga Parbat are relatively young mountain belts that have begun to uplift or have experienced increased rates of uplift during the past 5-10 Ma. As there is a time lag between the onset of uplift and achieving geomorphic steady state and again between reaching geomorphic steady state and thermal steady state, these orogens may be too young to have achieved this final stage. Additionally, young orogens may not have experienced a constant rate of uplift and denudation in the time over which the thermochronometers average. Certainly, in the case of the Southern Alps, present uplift rates can not have existed since uplift begun. Therefore, an apparent age is recording a transient thermal state. Even in a case where geomorphic steady state exists i.e. exhumation balances uplift, it is unlikely that a thermal steady state has been reached. This precludes the simple interpretation of exhumation rates often made. When multiple thermochronometers are used, inconsistencies can arise. For example, an increase in the rate of uplift is often observed when comparing the rates of exhumation using different thermochronometers. Our modeling shows that in some cases this phenomena is actually eliminated by considering the transient nature of the thermal regime following the onset of uplift and exhumation of an active orogen. To accurately determine exhumation rate
Soil residence time: A window into landscape morphologic steady state
Almond, P. C.; Roering, J. J.
2005-12-01
For a landscape in true morphologic steady state the erosion rate and the average residence time of the debris mantle regolith (including the soils) are everywhere equal. Where other factors influencing soil properties such as climate, organisms and parent material are relatively invariant the degree of weathering and extent of pedological development in the debris mantle regolith should be spatially invariant. The corollary to this argument, commonly exploited in soil-geomorphic analysis, is that variation in debris mantle regolith development in a landscape reflects inheritance of older geomorphic surfaces and hence departure from steady state, at least over some time and space scale. The Oregon Coast Range (OCR) experiences a constant rate of rock uplift and has escaped the effects of Pleistocene glacial and periglacial processes. Furthermore, rock uplift and denudation rates have been shown to be approximately in balance, and consequently the OCR is promoted as being a good candidate for a (flux) steady state landscape. This is, however, not a sufficient condition for morphologic steady state, which is often assumed in numerical landscape simulations. The rock underlying the OCR is relatively homogeneous turbidites of the Tyee formation, and climatic and vegetation factors are relatively uniform over large areas. The degree of weathering and pedological development of the regolith on hillslopes should therefore dominantly reflect variation in regolith residence time, such that significant variation implies non-morphologic-steady state conditions. Indeed, spatial variation in soil/regolith age indicates the extent of departure from morphologic steady state. We have observed ubiquitous but localised deep, highly weathered regoliths and soils on ridge tops in the OCR. The extent, depth, geometry and elevational distribution of these deep regolith patches combined with relative measures of their age derived from total element and meteoric 10Be inventory will enable
Nonlinear transport in a two dimensional holographic superconductor
Zeng, Hua Bi; Tian, Yu; Fan, Zhe Yong; Chen, Chiang-Mei
2016-06-01
The problem of nonlinear transport in a two-dimensional superconductor with an applied oscillating electric field is solved by the holographic method. The complex conductivity can be computed from the dynamics of the current for both the near- and nonequilibrium regimes. The limit of weak electric field corresponds to the near-equilibrium superconducting regime, where the charge response is linear and the conductivity develops a gap determined by the condensate. A larger electric field drives the system into a superconducting nonequilibrium steady state, where the nonlinear conductivity is quadratic with respect to the electric field. Increasing the amplitude of the applied electric field results in a far-from-equilibrium nonsuperconducting steady state with a universal linear conductivity of one. In the lower temperature regime we also find chaotic behavior of the superconducting gap, which results in a nonmonotonic field-dependent nonlinear conductivity.
Nonlinear Transport in a Two Dimensional Holographic Superconductor
Zeng, Hua Bi; Fan, Zhe Yong; Chen, Chiang-Mei
2016-01-01
The problem of nonlinear transport in a two dimensional superconductor with an applied oscillating electric field is solved by the holographic method. The complex conductivity can be computed from the dynamics of the current for both near- and non-equilibrium regimes. The limit of weak electric field corresponds to the near equilibrium superconducting regime, where the charge response is linear and the conductivity develops a gap determined by the condensate. A larger electric field drives the system into a superconducting non-equilibrium steady state, where the nonlinear conductivity is quadratic with respect to the electric field. Keeping increasing the amplitude of applied electric field results in a far-from-equilibrium non-superconducting steady state with a universal linear conductivity of one. In lower temperature regime we also find chaotic behavior of superconducting gap, which results in a non-monotonic field dependent nonlinear conductivity.
Radon determination in ground water
Energy Technology Data Exchange (ETDEWEB)
Segovia A, N.; Bulbulian G, S
1991-08-15
Studies on natural radioactivity in ground water were started in Mexico in San Luis Potosi state followed by samplings from deep wells and springs in the states of Mexico and Michoacan. The samples were analyzed for solubilized and {sup 226} Ra- supported {sup 222} Rn. Some of them were also studied for {sup 234} U/ {sup 238} U activity ratio. In this paper we discuss the activities obtained and their relationship with the geologic characteristics of the studied zones. (Author)
A two-dimensional analytical model of petroleum vapor intrusion
Yao, Yijun; Verginelli, Iason; Suuberg, Eric M.
2016-02-01
In this study we present an analytical solution of a two-dimensional petroleum vapor intrusion model, which incorporates a steady-state diffusion-dominated vapor transport in a homogeneous soil and piecewise first-order aerobic biodegradation limited by oxygen availability. This new model can help practitioners to easily generate two-dimensional soil gas concentration profiles for both hydrocarbons and oxygen and estimate hydrocarbon indoor air concentrations as a function of site-specific conditions such as source strength and depth, reaction rate constant, soil characteristics and building features. The soil gas concentration profiles generated by this new model are shown in good agreement with three-dimensional numerical simulations and two-dimensional measured soil gas data from a field study. This implies that for cases involving diffusion dominated soil gas transport, steady state conditions and homogenous source and soil, this analytical model can be used as a fast and easy-to-use risk screening tool by replicating the results of 3-D numerical simulations but with much less computational effort.
Stable MIMO Constrained Predictive Control with Steady state Objective Optimization
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A two-stage multi-objective optimization model-predictive control algorithms(MPC) strategy is pre sented. A domain MPC controller with input constraints is used to increase freedom for steady-state objective and enhance stabilization of the controller. A steady-state objective optimization algorithm oriented to transient process is adopted to realize optimization of objectives else than dynamic control. It is proved that .the stabilization for both dynamic control and steady-state objective optimization can be guaranteed. The theoretical results are demonstrated and discussed using a distillation tower as the model. Theoretical analysis and simulation results show that this control strategy is efficient and provides a good strategic solution to practical process control.
Structural simplification of chemical reaction networks in partial steady states.
Madelaine, Guillaume; Lhoussaine, Cédric; Niehren, Joachim; Tonello, Elisa
2016-11-01
We study the structural simplification of chemical reaction networks with partial steady state semantics assuming that the concentrations of some but not all species are constant. We present a simplification rule that can eliminate intermediate species that are in partial steady state, while preserving the dynamics of all other species. Our simplification rule can be applied to general reaction networks with some but few restrictions on the possible kinetic laws. We can also simplify reaction networks subject to conservation laws. We prove that our simplification rule is correct when applied to a module of a reaction network, as long as the partial steady state is assumed with respect to the complete network. Michaelis-Menten's simplification rule for enzymatic reactions falls out as a special case. We have implemented an algorithm that applies our simplification rules repeatedly and applied it to reaction networks from systems biology.
Quantum quasi-steady states in current transport
D'Agosta, Roberto; Zwolak, Michael; di Ventra, Massimiliano
2007-03-01
We investigate quasi-steady state solutions to transport in quantum systems by finding states which at some time minimize the change in density throughout all space and have a given current density flowing from one part of the system to another [1]. Contrary to classical dynamics, in a quantum mechanical system there are many states with a given energy and particle number which satisfy this minimization criterion. Taking as an example spinless fermions on a one-dimensional lattice, we explicitly show the phase space of a class of quasi-steady states. We also discuss the possibility of coherent and incoherent mixing of these steady state solutions leading to a new type of noise in quantum transport. [1] M. Di Ventra and T.N. Todorov J. Phys. Cond. Matt. 16, 8025 (2004).
Lattice gas dynamics: application to driven vortices in two dimensional superconductors.
Gotcheva, Violeta; Wang, Albert T J; Teitel, S
2004-06-18
A continuous time Monte Carlo lattice gas dynamics is developed to model driven steady states of vortices in two dimensional superconducting networks. Dramatic differences are found when compared to a simpler Metropolis dynamics. Subtle finite size effects are found at low temperature, with a moving smectic that becomes unstable to an anisotropic liquid on sufficiently large length scales.
Steady state decoupling and design of linear multivariable systems
Huang, J. Y.; Thaler, G. J.
1974-01-01
A constructive criterion for decoupling the steady states of linear multivariable systems is developed. The criterion consists of n(n-1) inequalities with the type numbers of the compensator transfer functions as the unknowns. These unknowns can be chosen to satisfy the inequalities and hence achieve a steady state decoupling scheme. It turns out that pure integrators in the loops play an important role. An extended root locus design method is then developed to take care of the stability and transient response. The overall procedure is applied to the compensation design for STOL C-8A aircraft in the approach mode.
Adaptive steady-state stabilization for nonlinear dynamical systems
Braun, David J.
2008-07-01
By means of LaSalle’s invariance principle, we propose an adaptive controller with the aim of stabilizing an unstable steady state for a wide class of nonlinear dynamical systems. The control technique does not require analytical knowledge of the system dynamics and operates without any explicit knowledge of the desired steady-state position. The control input is achieved using only system states with no computer analysis of the dynamics. The proposed strategy is tested on Lorentz, van der Pol, and pendulum equations.
Electric machines steady state, transients, and design with Matlab
Boldea, Ion
2009-01-01
Part I: Steady StateIntroductionElectric Energy and Electric MachinesBasic Types of Transformers and Electric MachinesLosses and EfficiencyPhysical Limitations and RatingsNameplate RatingsMethods of AnalysisState of the Art and Perspective Electric TransformersAC Coil with Magnetic Core and Transformer Principles Magnetic Materials in EMs and Their LossesElectric Conductors and Their Skin EffectsComponents of Single- and 3-Phase TransformersFlux Linkages and Inductances of Single-Phase TransformersCircuit Equations of Single-Phase Transformers With Core LossesSteady State and Equivalent Circui
Mapping current fluctuations of stochastic pumps to nonequilibrium steady states
Rotskoff, Grant M.
2017-03-01
We show that current fluctuations in a stochastic pump can be robustly mapped to fluctuations in a corresponding time-independent nonequilibrium steady state. We thus refine a recently proposed mapping so that it ensures equivalence of not only the averages, but also optimal representation of fluctuations in currents and density. Our mapping leads to a natural decomposition of the entropy production in stochastic pumps similar to the "housekeeping" heat. As a consequence of the decomposition of entropy production, the current fluctuations in weakly perturbed stochastic pumps are shown to satisfy a universal bound determined by the steady state entropy production.
Emergence of advance waves in a steady-state universe
Energy Technology Data Exchange (ETDEWEB)
Hobart, R.H.
1979-10-01
In standard Wheeler-Feynman electrodynamics advanced waves from any source are absolutely canceled by the advanced waves from the absorber responding to that source. The present work shows this cancellation fails over cosmic distances in a steady-state universe. A test of the view proposed earlier, in a paper which assumed failure of cancellation ad hoc, that zero-point fluctuations of the electromagnetic field are such emergent advanced waves, is posed. The view entails anomalous slowing of spontaneous transition rates at longer emission wavelengths; available data go against this, furnishing additional argument against the suspect assumption that the universe is steady-state.
Dong, Hattie Z; Worters, Pauline W; Wu, Holden H; Ingle, R Reeve; Vasanawala, Shreyas S; Nishimura, Dwight G
2013-08-01
Noncontrast-enhanced renal angiography techniques based on balanced steady-state free precession avoid external contrast agents, take advantage of high inherent blood signal from the T 2 / T 1 contrast mechanism, and have short steady-state free precession acquisition times. However, background suppression is limited; inflow times are inflexible; labeling region is difficult to define when tagging arterial flow; and scan times are long. To overcome these limitations, we propose the use of multiple inversion recovery preparatory pulses combined with alternating pulse repetition time balanced steady-state free precession to produce renal angiograms. Multiple inversion recovery uses selective spatial saturation followed by four nonselective inversion recovery pulses to concurrently null a wide range of background T 1 species while allowing for adjustable inflow times; alternating pulse repetition time steady-state free precession maintains vessel contrast and provides added fat suppression. The high level of suppression enables imaging in three-dimensional as well as projective two-dimensional formats, the latter of which has a scan time as short as one heartbeat. In vivo studies at 1.5 T demonstrate the superior vessel contrast of this technique.
Two-dimensional transport study of scrape off layer plasmas
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Nobuyuki [Interdisciplinary Graduate School of Advanced Energy Engineering Sciences, Kyushu University, Fukuoka (Japan); Yagi, Masatoshi; Itoh, Sanae-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics
1999-09-01
Two-dimensional transport code is developed to analyzed the heat pulse propagation in the scrape-off layer plasma. The classical and anomalous transport models are considered as a thermal diffusivity perpendicular to the magnetic field. On the other hand, the classical transport model is chosen as a thermal diffusivity parallel to the magnetic field. The heat deposition profiles are evaluated for various kinds of transport models. It is found that the heat pulse which arrives at the divertor plate due to the classical transport is largest compared with other models. The steady state temperate profiles of the electron and ion are also discussed. (author)
Plasticity, Fracture and Friction in Steady-State Plate Cutting
DEFF Research Database (Denmark)
Simonsen, Bo Cerup; Wierzbicki, Tomasz
1997-01-01
A closed form solution to the problem of steady-state wedge cutting through a ductile metal plate is presented. The considered problem is an idealization of a ship bottom raking process, i.e. a continuous cutting damage of a ship bottom by a hard knife-like rock in a grounding event. A new...
The Enlisted Steady State-Simulation (ESS-SIM) Tool
2014-07-01
1 Model design ...current inven- tories. A simulation of the transition from a current inventory toward the steady state is required for such an understanding. Model design ...described by paygrade (e.g., the Navy needs 100 E-5 OS personnel). • Longevity (length of service): Many personnel policies address longevity (e.g., Zone A
The concave river long profile: a morphodynamic steady state?
Blom, A.
2011-12-01
By definition, a morphodynamic steady state is governed by a spatially constant sediment transport rate. As the sediment transport rate is a function of shear stress associated with skin friction, the morphodynamic steady state has been considered to be governed by a spatially constant bed slope. For this reason, the typical concave river long profile has been considered to be a quasi-steady state. The river's steady state has been considered to be one with a spatially constant bed slope, with tributaries inducing a stepwise decrease in bed slope in streamwise direction. Yet, for the sediment transport rate to be spatially constant, it rather is the product of water surface slope and water depth associated with skin friction that needs to be constant. This implies that physical mechanisms that induce streamwise variation in the sediment transport rate can be compensated by a streamwise variation in bed slope so as to guarantee a spatially constant sediment transport rate. Following the river course, such physical mechanisms can be bedrock exposure, partial transport, and a spatially lagging bedform growth. At locations where tributaries increase the water discharge, the above mechanisms cause the river bed profile to be upward concave over a significant reach. At bifucations or at locations where river widening prevails, the river bed profile is upward convex.
ONLINE MONITORING STEADY STATE STABILITY LIMIT PADA SISTEM INTERKONEKSI SULSELRABAR
2015-01-01
Pada beberapa dekade terakhir, fenomena black-out (pemadaman total)akibat voltage collapse mengalami peningkatan.Hal ini disebabkan oleh peningkatan konsumen pemakai listrik yang tidak sebanding dengan peningkatan pembangkit dan pengembangan jaringan transmisi. Berdasarkan kenyataan dilapangan, ketidakstabilan steady state sangat berhubungan dengan rendahnya ketersediaan daya aktif/reaktif, level tegangan yang rendah, dan besarnya perubahan tegangan untuk perubahan beban atau daya pembangkit....
Principle of Entropy Maximization for Nonequilibrium Steady States
DEFF Research Database (Denmark)
Shapiro, Alexander; Stenby, Erling Halfdan
2002-01-01
The goal of this contribution is to find out to what extent the principle of entropy maximization, which serves as a basis for the equilibrium thermodynamics, may be generalized onto non-equilibrium steady states. We prove a theorem that, in the system of thermodynamic coordinates, where entropy...
Combined Steady-State and Dynamic Heat Exchanger Experiment
Luyben, William L.; Tuzla, Kemal; Bader, Paul N.
2009-01-01
This paper describes a heat-transfer experiment that combines steady-state analysis and dynamic control. A process-water stream is circulated through two tube-in-shell heat exchangers in series. In the first, the process water is heated by steam. In the second, it is cooled by cooling water. The equipment is pilot-plant size: heat-transfer areas…
Steady state nutrition by transpiration controlled nutrient supply
Braakhekke, W.G.; Labe, D.A.
1990-01-01
Programmed nutrient addition with a constant relative addition rate has been advocated as a suitable research technique for inducing steady state nutrition in exponentially growing plants. Transpiration controlled nutrient supply is proposed as an alternative technique for plants with a short or no
Analysis of slow transitions between nonequilibrium steady states
Mandal, Dibyendu; Jarzynski, Christopher
2016-06-01
Transitions between nonequilibrium steady states obey a generalized Clausius inequality, which becomes an equality in the quasistatic limit. For slow but finite transitions, we show that the behavior of the system is described by a response matrix whose elements are given by a far-from-equilibrium Green-Kubo formula, involving the decay of correlations evaluated in the nonequilibrium steady state. This result leads to a fluctuation-dissipation relation between the mean and variance of the nonadiabatic entropy production, Δ {{s}\\text{na}} . Furthermore, our results extend—to nonequilibrium steady states—the thermodynamic metric structure introduced by Sivak and Crooks for analyzing minimal-dissipation protocols for transitions between equilibrium states.
Steady State Dynamic Operating Behavior of Universal Motor
Directory of Open Access Journals (Sweden)
Muhammad Khan Burdi
2015-01-01
Full Text Available A detailed investigation of the universal motor is developed and used for various dynamic steady state and transient operating conditions of loads. In the investigation, output torque, motor speed, input current, input/output power and efficiency are computed, compared and analyzed for different loads. While this paper discusses the steady-state behavior of the universal motor, another companion paper, ?Transient dynamic behavior of universal motor?, will discuss its transient behavior in detail. A non-linear generalized electric machine model of the motor is considered for the analysis. This study was essential to investigate effect of output load on input current, power, speed and efficiency of the motor during operations. Previously such investigation is not known
Hydrodynamics of stratified epithelium: steady state and linearized dynamics
Yeh, Wei-Ting
2015-01-01
A theoretical model for stratified epithelium is presented. The viscoelastic properties of the tissue is assumed to be dependent on the spatial distribution of proliferative and differentiated cells. Based on this assumption, a hydrodynamic description for tissue dynamics at long-wavelength, long-time limit is developed, and the analysis reveals important insight for the dynamics of an epithelium close to its steady state. When the proliferative cells occupy a thin region close to the basal membrane, the relaxation rate towards the steady state is enhanced by cell division and cell apoptosis. On the other hand, when the region where proliferative cells reside becomes sufficiently thick, a flow induced by cell apoptosis close to the apical surface could enhance small perturbations. This destabilizing mechanism is general for continuous self-renewal multi-layered tissues, it could be related to the origin of certain tissue morphology and developing pattern.
Hydrodynamics of stratified epithelium: Steady state and linearized dynamics
Yeh, Wei-Ting; Chen, Hsuan-Yi
2016-05-01
A theoretical model for stratified epithelium is presented. The viscoelastic properties of the tissue are assumed to be dependent on the spatial distribution of proliferative and differentiated cells. Based on this assumption, a hydrodynamic description of tissue dynamics at the long-wavelength, long-time limit is developed, and the analysis reveals important insights into the dynamics of an epithelium close to its steady state. When the proliferative cells occupy a thin region close to the basal membrane, the relaxation rate towards the steady state is enhanced by cell division and cell apoptosis. On the other hand, when the region where proliferative cells reside becomes sufficiently thick, a flow induced by cell apoptosis close to the apical surface enhances small perturbations. This destabilizing mechanism is general for continuous self-renewal multilayered tissues; it could be related to the origin of certain tissue morphology, tumor growth, and the development pattern.
Nonequilibrium Steady States of a Stochastic Model System.
Zhang, Qiwei
We study the nonequilibrium steady state of a stochastic lattice gas model, originally proposed by Katz, Lebowitz and Spohn (Phys. Rev. B 28: 1655 (1983)). Firstly, we solve the model on some small lattices exactly in order to see the general dependence of the steady state upon different parameters of the model. Nextly, we derive some analytical results for infinite lattice systems by taking some suitable limits. We then present some renormalization group results for the continuum version of the model via field theoretical techniques, the supersymmetry of the critical dynamics in zero field is also explored. Finally, we report some very recent 3-D Monte Carlo simulation results, which have been obtained by applying Multi-Spin-Coding techniques on a CDC vector supercomputer - Cyber 205 at John von Neumann Center.
Task-specific stability of multifinger steady-state action.
Reschechtko, Sasha; Zatsiorsky, Vladimir M; Latash, Mark L
2015-01-01
The authors explored task-specific stability during accurate multifinger force production tasks with different numbers of instructed fingers. Subjects performed steady-state isometric force production tasks and were instructed not to interfere voluntarily with transient lifting-and-lowering perturbations applied to the index finger. The main results were (a) intertrial variance in the space of finger modes at steady states was larger within the subspace that had no effect on the total force (the uncontrolled manifold [UCM]); (b) perturbations caused large deviations of finger modes within the UCM (motor equivalence); and (c) deviations caused by the perturbation showed larger variance within the UCM. No significant effects of the number of task fingers were noted in any of the 3 indicators. The results are discussed within the frameworks of the UCM and referent configuration hypotheses. The authors conclude, in particular, that all the tasks were effectively 4-finger tasks with different involvement of task and nontask fingers.
Non-equilibrium steady states in supramolecular polymerization
Sorrenti, Alessandro; Leira-Iglesias, Jorge; Sato, Akihiro; Hermans, Thomas M.
2017-06-01
Living systems use fuel-driven supramolecular polymers such as actin to control important cell functions. Fuel molecules like ATP are used to control when and where such polymers should assemble and disassemble. The cell supplies fresh ATP to the cytosol and removes waste products to sustain steady states. Artificial fuel-driven polymers have been developed recently, but keeping them in sustained non-equilibrium steady states (NESS) has proven challenging. Here we show a supramolecular polymer that can be kept in NESS, inside a membrane reactor where ATP is added and waste removed continuously. Assembly and disassembly of our polymer is regulated by phosphorylation and dephosphorylation, respectively. Waste products lead to inhibition, causing the reaction cycle to stop. Inside the membrane reactor, however, waste can be removed leading to long-lived NESS conditions. We anticipate that our approach to obtain NESS can be applied to other stimuli-responsive materials to achieve more life-like behaviour.
Approach to steady-state transport in nanoscale conductors.
Bushong, Neil; Sai, Na; Di Ventra, Massimiliano
2005-12-01
We show, using a tight-binding model and time-dependent density-functional theory, that a quasi-steady-state current can be established dynamically in a finite nanoscale junction without any inelastic effects. This is simply due to the geometrical constriction experienced by the electron wave packets as they propagate through the junction. We also show that in this closed nonequilibrium system two local electron occupation functions can be defined on each side of the nanojunction which approach Fermi distributions with increasing number of atoms in the electrodes. The resultant conductance and current-voltage characteristics at quasi-steady state are in agreement with those calculated within the static scattering approach.
Steady-state Physics, Effective Temperature Dynamics in Holography
Kundu, Arnab
2013-01-01
Using the gauge-gravity duality, we argue that for a certain class of out-of-equilibrium steady-state systems in contact with a heat bath at a given temperature, the macroscopic physics can be captured by an effective thermodynamic description. The steady-state is obtained by applying a constant electric field that results in a stationary current flow. Within holography, we consider generic probe systems where an open string equivalence principle and an open string metric govern the effective thermodynamics. This description comes equipped with an effective temperature, which is larger than the bath temperature, and a corresponding effective entropy. For conformal or scale-invariant theories, certain scaling behaviours follow immediately. In general, in the large electric field limit, this effective temperature is also observed to obey certain generic relations with various physical parameters in the system.
Multiplying steady-state culture in multi-reactor system.
Erm, Sten; Adamberg, Kaarel; Vilu, Raivo
2014-11-01
Cultivation of microorganisms in batch experiments is fast and economical but the conditions therein change constantly, rendering quantitative data interpretation difficult. By using chemostat with controlled environmental conditions the physiological state of microorganisms is fixed; however, the unavoidable stabilization phase makes continuous methods resource consuming. Material can be spared by using micro scale devices, which however have limited analysis and process control capabilities. Described herein are a method and a system combining the high throughput of batch with the controlled environment of continuous cultivations. Microorganisms were prepared in one bioreactor followed by culture distribution into a network of bioreactors and continuation of independent steady state experiments therein. Accelerostat cultivation with statistical analysis of growth parameters demonstrated non-compromised physiological state following distribution, thus the method effectively multiplied steady state culture of microorganisms. The theoretical efficiency of the system was evaluated in inhibitory compound analysis using repeated chemostat to chemostat transfers.
Extending Molecular Theory to Steady-State Diffusing Systems
Energy Technology Data Exchange (ETDEWEB)
FRINK,LAURA J. D.; SALINGER,ANDREW G.; THOMPSON,AIDAN P.
1999-10-22
Predicting the properties of nonequilibrium systems from molecular simulations is a growing area of interest. One important class of problems involves steady state diffusion. To study these cases, a grand canonical molecular dynamics approach has been developed by Heffelfinger and van Swol [J. Chem. Phys., 101, 5274 (1994)]. With this method, the flux of particles, the chemical potential gradients, and density gradients can all be measured in the simulation. In this paper, we present a complementary approach that couples a nonlocal density functional theory (DFT) with a transport equation describing steady-state flux of the particles. We compare transport-DFT predictions to GCMD results for a variety of ideal (color diffusion), and nonideal (uphill diffusion and convective transport) systems. In all cases excellent agreement between transport-DFT and GCMD calculations is obtained with diffusion coefficients that are invariant with respect to density and external fields.
Visual steady state in relation to age and cognitive function
DEFF Research Database (Denmark)
Horwitz, Anna; Dyhr Thomsen, Mia; Wiegand, Iris
2017-01-01
examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power......, global cognition, executive function, memory, and education (p
Anthropic-principle arguments against steady-state cosmological theories
Energy Technology Data Exchange (ETDEWEB)
Tipler, F.J. (Tulane Univ., New Orleans, LA (USA))
1982-04-01
Steady-state theories are very difficult to rule out on observational grounds, particularly if they are adjusted to contain a three-degree isotropic thermal-background radiation. However, anthropic-principle arguments can be used to rule out virtually any cosmological theory which has the universe stationary in the large. For example, anthropic considerations show that the perfect cosmological principle is self-contradictory.
Oscillations and multiple steady states in active membrane transport models.
Vieira, F M; Bisch, P M
1994-01-01
The dynamic behavior of some non-linear extensions of the six-state alternating access model for active membrane transport is investigated. We use stoichio-metric network analysis to study the stability of steady states. The bifurcation analysis has been done through standard numerical methods. For the usual six-state model we have proved that there is only one steady state, which is globally asymptotically stable. When we added an autocatalytic step we found self-oscillations. For the competition between a monomer cycle and a dimer cycle, with steps of dimer formation, we have also found self-oscillations. We have also studied models involving the formation of a complex with other molecules. The addition of two steps for formation of a complex of the monomer with another molecule does not alter either the number or the stability of steady states of the basic six-state model. The model which combines the formation of a complex with an autocatalytic step shows both self-oscillations and multiple steady states. The results lead us to conclude that oscillations could be produced by active membrane transport systems if the transport cycle contains a sufficiently large number of steps (six in the present case) and is coupled to at least one autocatalytic reaction,. Oscillations are also predicted when the monomer cycle is coupled to a dimer cycle. In fact, the autocatalytic reaction can be seen as a simplification of the model involving competition between monomer and dimer cycles, which seems to be a more realistic description of biological systems. A self-regulation mechanism of the pumps, related to the multiple stationary states, is expected only for a combined effect of autocatalysis and formation of complexes with other molecules. Within the six-state model this model also leads to oscillation.
Optimal operation of Petlyuk distillation: Steady-state behavior
Ivar J. Halvorsen; Sigurd Skogestad
2001-01-01
The "Petlyuk" or "dividing-wall" or "fully thermally coupled" distillation column is an interesting alternative to the conventional cascaded binary columns for separation of multi-component mixtures. However, the industrial use has been limited, and difficulties in operation have been reported as one reason. With three product compositions controlled, the system has two degrees of freedom left for on-line optimization. We show that the steady-state optimal solution surface is quite narrow, an...
Approach to steady state transport in nanoscale conductors
2005-01-01
We show, using a tight-binding model and time-dependent density-functional theory, that a quasi-steady state current can be established dynamically in a finite nanoscale junction without any inelastic effects. This is simply due to the geometrical constriction experienced by the electron wavepackets as they propagate through the junction. We also show that in this closed non-equilibrium system two local electron occupation functions can be defined on each side of the nanojunction which approa...
The Approach to Steady State Using Homogeneous and Cartesian Coordinates
Directory of Open Access Journals (Sweden)
D. F. Gochberg
2013-01-01
Full Text Available Repeating an arbitrary sequence of RF pulses and magnetic field gradients will eventually lead to a steady-state condition in any magnetic resonance system. While numerical methods can quantify this trajectory, analytic analysis provides significantly more insight and a means for faster calculation. Recently, an analytic analysis using homogeneous coordinates was published. The current work further develops this line of thought and compares the relative merits of using a homogeneous or a Cartesian coordinate system.
Steady state equivalence among autocatalytic peroxidase-oxidase reactions
Méndez-González, José; Femat, Ricardo
2016-12-01
Peroxidase-oxidase is an enzymatic reaction that can exhibit dynamical scenarios such as bistability, sustained oscillations, and Shilnikov chaos. In this work, we apply the chemical reaction network theory approach to find kinetic constants such that the associated mass action kinetics ordinary differential equations induced by three four dimensional structurally different enzymatic reaction systems can support the same steady states for several chemical species despite differences in their chemical nature.
Multiple Color Stimulus Induced Steady State Visual Evoked Potentials
2007-11-02
evoked potentials, multiple color, FFT, bispectrum I. INTRODUCTION Visual evoked potential ( VEP ) is the electrical response of...brain under visual stimulation, which can be recorded from the scalp over the visual cortex of the brain. A distinction is made between transient VEP ...and steady-state VEP (SSVEP) based on the stimulation frequencies. The former arises when the stimulation frequencies are less than 2 Hz. However
Steady state nutrition by transpiration controlled nutrient supply
Braakhekke, W.G.; Labe, D. A.
1990-01-01
Programmed nutrient addition with a constant relative addition rate has been advocated as a suitable research technique for inducing steady state nutrition in exponentially growing plants. Transpiration controlled nutrient supply is proposed as an alternative technique for plants with a short or no exponential growth phase. A two-weeks experiment with transpiration controlled nitrogen supply to Pennisetum americanum was carried out to evaluate this method. After an adaptation phase a constant...
Steady-state solution methods for open quantum optical systems
Nation, P. D.
2015-01-01
We discuss the numerical solution methods available when solving for the steady-state density matrix of a time-independent open quantum optical system, where the system operators are expressed in a suitable basis representation as sparse matrices. In particular, we focus on the difficulties posed by the non-Hermitian structure of the Lindblad super operator, and the numerical techniques designed to mitigate these pitfalls. In addition, we introduce a doubly iterative inverse-power method that...
Evaluation of a steady-state test of foam stability
Hutzler, Stefan; Lösch, Dörte; Carey, Enda; Weaire, Denis; Hloucha, Matthias; Stubenrauch, Cosima
2011-02-01
We have evaluated a steady-state test of foam stability, based on the steady-state height of a foam produced by a constant velocity of gas flow. This test is mentioned in the book by Bikerman [Foams, Springer, Berlin, 1973] and an elementary theory was developed for it by Verbist et al. [J. Phys. Condens. Matter 8 (1996) p. 3715]. For the study, we used an aqueous solution of the cationic surfactant dodecyl trimethylammonium bromide, C12TAB, at a concentration of two times the critical micelle concentration (2 cmc). During foam generation, bubbles collapse at the top of the column which, in turn, eventually counterbalances the rate of bubble production at the bottom. The resulting balance can be described mathematically by an appropriate solution of the foam drainage equation under specified boundary conditions. Our experimental findings are in agreement with the theoretical predictions of a diverging foam height at a critical gas velocity and a finite foam height in the limit of zero velocity. We identify a critical liquid fraction below which a foam is unstable as an important parameter for characterizing foam stability. Furthermore, we deduce an effective viscosity of the liquid which flows through the foam. Currently unexplained are two experimental observations, namely sudden changes of the steady-state foam height in experiments that run over several hours and a reduction in foam height once an overflow of the foam from the containing vessel has occurred.
STEADY-STATE MODEL OF SOLAR WIND ELECTRONS REVISITED
Energy Technology Data Exchange (ETDEWEB)
Yoon, Peter H.; Kim, Sunjung; Choe, G. S., E-mail: yoonp@umd.edu [School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2015-10-20
In a recent paper, Kim et al. put forth a steady-state model for the solar wind electrons. The model assumed local equilibrium between the halo electrons, characterized by an intermediate energy range, and the whistler-range fluctuations. The basic wave–particle interaction is assumed to be the cyclotron resonance. Similarly, it was assumed that a dynamical steady state is established between the highly energetic superhalo electrons and high-frequency Langmuir fluctuations. Comparisons with the measured solar wind electron velocity distribution function (VDF) during quiet times were also made, and reasonable agreements were obtained. In such a model, however, only the steady-state solution for the Fokker–Planck type of electron particle kinetic equation was considered. The present paper complements the previous analysis by considering both the steady-state particle and wave kinetic equations. It is shown that the model halo and superhalo electron VDFs, as well as the assumed wave intensity spectra for the whistler and Langmuir fluctuations, approximately satisfy the quasi-linear wave kinetic equations in an approximate sense, thus further validating the local equilibrium model constructed in the paper by Kim et al.
Steady state statistical correlations predict bistability in reaction motifs.
Chakravarty, Suchana; Barik, Debashis
2017-03-01
Various cellular decision making processes are regulated by bistable switches that take graded input signals and convert them to binary all-or-none responses. Traditionally, a bistable switch generated by a positive feedback loop is characterized either by a hysteretic signal response curve with two distinct signaling thresholds or by characterizing the bimodality of the response distribution in the bistable region. To identify the intrinsic bistability of a feedback regulated network, here we propose that bistability can be determined by correlating higher order moments and cumulants (≥2) of the joint steady state distributions of two components connected in a positive feedback loop. We performed stochastic simulations of four feedback regulated models with intrinsic bistability and we show that for a bistable switch with variation of the signal dose, the steady state variance vs. covariance adopts a signatory cusp-shaped curve. Further, we find that the (n + 1)th order cross-cumulant vs. nth order cross-cumulant adopts a closed loop structure for at least n = 3. We also propose that our method is capable of identifying systems without intrinsic bistability even though the system may show bimodality in the marginal response distribution. The proposed method can be used to analyze single cell protein data measured at steady state from experiments such as flow cytometry.
Basin stability measure of different steady states in coupled oscillators.
Rakshit, Sarbendu; Bera, Bidesh K; Majhi, Soumen; Hens, Chittaranjan; Ghosh, Dibakar
2017-04-05
In this report, we investigate the stabilization of saddle fixed points in coupled oscillators where individual oscillators exhibit the saddle fixed points. The coupled oscillators may have two structurally different types of suppressed states, namely amplitude death and oscillation death. The stabilization of saddle equilibrium point refers to the amplitude death state where oscillations are ceased and all the oscillators converge to the single stable steady state via inverse pitchfork bifurcation. Due to multistability features of oscillation death states, linear stability theory fails to analyze the stability of such states analytically, so we quantify all the states by basin stability measurement which is an universal nonlocal nonlinear concept and it interplays with the volume of basins of attractions. We also observe multi-clustered oscillation death states in a random network and measure them using basin stability framework. To explore such phenomena we choose a network of coupled Duffing-Holmes and Lorenz oscillators which are interacting through mean-field coupling. We investigate how basin stability for different steady states depends on mean-field density and coupling strength. We also analytically derive stability conditions for different steady states and confirm by rigorous bifurcation analysis.
Basin stability measure of different steady states in coupled oscillators
Rakshit, Sarbendu; Bera, Bidesh K.; Majhi, Soumen; Hens, Chittaranjan; Ghosh, Dibakar
2017-01-01
In this report, we investigate the stabilization of saddle fixed points in coupled oscillators where individual oscillators exhibit the saddle fixed points. The coupled oscillators may have two structurally different types of suppressed states, namely amplitude death and oscillation death. The stabilization of saddle equilibrium point refers to the amplitude death state where oscillations are ceased and all the oscillators converge to the single stable steady state via inverse pitchfork bifurcation. Due to multistability features of oscillation death states, linear stability theory fails to analyze the stability of such states analytically, so we quantify all the states by basin stability measurement which is an universal nonlocal nonlinear concept and it interplays with the volume of basins of attractions. We also observe multi-clustered oscillation death states in a random network and measure them using basin stability framework. To explore such phenomena we choose a network of coupled Duffing-Holmes and Lorenz oscillators which are interacting through mean-field coupling. We investigate how basin stability for different steady states depends on mean-field density and coupling strength. We also analytically derive stability conditions for different steady states and confirm by rigorous bifurcation analysis. PMID:28378760
Nonequilibrium Steady State Thermodynamics and Fluctuations for Stochastic Systems
Taniguchi, Tooru; Cohen, E. G. D.
2008-02-01
We use the work done on and the heat removed from a system to maintain it in a nonequilibrium steady state for a thermodynamic-like description of such a system as well as of its fluctuations. Based on an extended Onsager-Machlup theory for nonequilibrium steady states we indicate two ambiguities, not present in an equilibrium state, in defining such work and heat: one due to a non-uniqueness of time-reversal procedures and another due to multiple possibilities to separate heat into work and an energy difference in nonequilibrium steady states. As a consequence, for such systems, the work and heat satisfy multiple versions of the first and second laws of thermodynamics as well as of their fluctuation theorems. Unique laws and relations appear only to be obtainable for concretely defined systems, using physical arguments to choose the relevant physical quantities. This is illustrated on a number of systems, including a Brownian particle in an electric field, a driven torsion pendulum, electric circuits and an energy transfer driven by a temperature difference.
Ideal MHD Stability of ITER Steady State Scenarios with ITBs
Energy Technology Data Exchange (ETDEWEB)
F.M. Poli, C.E. Kessel, S. Jardin, J. Manickam, M. Chance, J. Chen
2011-07-27
One of ITER goals is to demonstrate feasibility of continuous operations using non-inductive current drive. Two main candidates have been identified for advanced operations: the long duration, high neutron fluency hybrid scenario and the steady state scenario, both operating at a plasma current lower than the reference ELMy scenario [1][2] to minimize the required current drive. The steady state scenario targets plasmas with current 7-10 MA in the flat-top, 50% of which will be provided by the self-generated, pressure-driven bootstrap current. It has been estimated that, in order to obtain a fusion gain Q > 5 at a current of 9 MA, it should be ΒN > 2.5 and H > 1.5 [3]. This implies the presence of an Internal Transport Barrier (ITB). This work discusses how the stability of steady state scenarios with ITBs is affected by the external heating sources and by perturbations of the equilibrium profiles.
Transient and steady-state currents in epoxy resin
Energy Technology Data Exchange (ETDEWEB)
Guillermin, Christophe [Schneider Electric Industries S.A.S., 37 quai Paul-Louis Merlin, 38050 Grenoble Cedex 9 (France); Rain, Pascal [Laboratoire d' Electrostatique et de Materiaux Dielectriques (LEMD), CNRS, 25 avenue des Martyrs, 38042 Grenoble Cedex 9 (France); Rowe, Stephen W [Schneider Electric Industries S.A.S., 37 quai Paul-Louis Merlin, 38050 Grenoble Cedex 9 (France)
2006-02-07
Charging and discharging currents have been measured in a diglycidyl ether of bisphenol-A epoxy resin with and without silica fillers, below and above its glass transition temperature T{sub g} = 65 deg. C. Both transient and steady-state current densities have been analysed. The average applied fields ranged from 3 to 35 kV mm{sup -1} with a sample thickness of 0.5 mm. Above T{sub g}, transient currents suggested a phenomenon of charge injection forming trapped space charges even at low fields. Steady-state currents confirmed that the behaviour was not Ohmic and suggested Schottky-type injection. Below T{sub g}, the current is not controlled by the metal-dielectric interface but by the conduction in the volume: the current is Ohmic at low fields and both transient and steady-state currents suggest a phenomenon of space-charge limited currents at high fields. The field threshold is similar in the filler-free and the filled resin. Values in the range 12-17 kV mm{sup -1} have been measured.
Steady states of continuous-time open quantum walks
Liu, Chaobin; Balu, Radhakrishnan
2017-07-01
Continuous-time open quantum walks (CTOQW) are introduced as the formulation of quantum dynamical semigroups of trace-preserving and completely positive linear maps (or quantum Markov semigroups) on graphs. We show that a CTOQW always converges to a steady state regardless of the initial state when a graph is connected. When the graph is both connected and regular, it is shown that the steady state is the maximally mixed state. As shown by the examples in this article, the steady states of CTOQW can be very unusual and complicated even though the underlying graphs are simple. The examples demonstrate that the structure of a graph can affect quantum coherence in CTOQW through a long-time run. Precisely, the quantum coherence persists throughout the evolution of the CTOQW when the underlying topology is certain irregular graphs (such as a path or a star as shown in the examples). In contrast, the quantum coherence will eventually vanish from the open quantum system when the underlying topology is a regular graph (such as a cycle).
Cavitation modeling for steady-state CFD simulations
Hanimann, L.; Mangani, L.; Casartelli, E.; Widmer, M.
2016-11-01
Cavitation in hydraulic turbomachines is an important phenomenon to be considered for performance predictions. Correct analysis of the cavitation onset and its effect on the flow field while diminishing the pressure level need therefore to be investigated. Even if cavitation often appears as an unsteady phenomenon, the capability to compute it in a steady state formulation for the design and assessment phase in the product development process is very useful for the engineer. In the present paper the development and corresponding application of a steady state CFD solver is presented, based on the open source toolbox OpenFOAM®. In the first part a review of different cavitation models is presented. Adopting the mixture-type cavitation approach, various models are investigated and developed in a steady state CFD RANS solver. Particular attention is given to the coupling between cavitation and turbulence models as well as on the underlying numerical procedure, especially the integration in the pressure- correction step of pressure-based solvers, which plays an important role in the stability of the procedure. The performance of the proposed model is initially assessed on simple cases available in the open literature. In a second step results for different applications are presented, ranging from airfoils to pumps.
SBWR Model for Steady-State and Transient Analysis
Directory of Open Access Journals (Sweden)
Gilberto Espinosa-Paredes
2008-01-01
Full Text Available This paper presents a model of a simplified boiling water reactor (SBWR to analyze the steady-state and transient behavior. The SBWR model is based on approximations of lumped and distributed parameters to consider neutronics and natural circulation processes. The main components of the model are vessel dome, downcomer, lower plenum, core (channel and fuel, upper plenum, pressure, and level controls. Further consideration of the model is the natural circulation path in the internal circuit of the reactor, which governs the safety performance of the SBWR. To demonstrate the applicability of the model, the predictions were compared with plant data, manufacturer_s predictions, and RELAP5 under steady-state and transient conditions of a typical BWR. In steady-state conditions, the profiles of the main variables of the SBWR core such as superficial velocity, void fraction, temperatures, and convective heat transfer coefficient are presented and analyzed. The transient behavior of SBWR was analyzed during the closure of all main steam line isolation valves (MSIVs. Our results in this transient show that the cooling system due to natural circulation in the SBWR is around 70% of the rated core flow. According to the results shown here, one of the main conclusions of this work is that the simplified model could be very helpful in the licensing process.
Domanov, Yegor A; Gorbenko, Galina P; Molotkovsky, Julian G
2004-01-01
A method has been developed allowing structural and binding parameters to be recovered by global analysis of two-dimensional array of steady-state RET data in the special case where energy acceptors distribute between aqueous and lipid phases while donors are embedded in the membrane at a known depth. To test the validity of this approach, correlation and error analyses have been performed using simulated data. To exemplify the method application to the membrane studies, energy transfer from anthrylvinyl-labeled phosphatidylcholine incorporated into mixed phosphatidylcholine/cardiolipin unilamellar vesicles to heme group of cytochrome c is analyzed.
McAda, Douglas P.; Naus, Cheryl A.
2008-01-01
In April 2001, the U.S. Geological Survey (USGS) and the New Mexico Environment Department (NMED) began a cooperative study to infer the pre-mining ground-water chemistry at the Molycorp molybdenum mine site in the Red River Valley. The Molycorp mine has been in operation since the 1920s. Because ground-water conditions prior to mining are not available, sites analogous to the pre-mining conditions at the mine site must be studied to infer those pre-mining conditions. The Straight Creek drainage basin (watershed) was selected as the primary analog site for this study because of its similar terrain and geology to the mine site, accessibility, potential for well construction, and minimal anthropogenic activity. The purpose of this report is to present results of a water-budget analysis of the debris-flow aquifer in the Straight Creek watershed. The water budget is based on mean annual conditions and is assumed to be steady state. For this study, the Straight Creek watershed was divided into sub-watersheds on the basis of locations of seismic lines, which were used to calculate cross-section area through the Straight Creek debris-flow deposits and underlying fractured and weathered bedrock (regolith). Water-budget components were calculated for areas upstream from and between the seismic lines. Components of the water budget were precipitation, evapotranspiration, surface-water flow, and ground-water flow under a steady-state mean annual condition. Watershed yield, defined as precipitation minus evapotranspiration, was separated into surface-water flow, ground-water flow through the debris-flow deposits and regolith, and ground-water flow through fractured bedrock. The approach to this calculation was to use Darcy?s Law to calculate the flow through the cross-section area of the saturated debris-flow deposits and underlying regolith as defined by the interpreted seismic data. The amount of watershed yield unaccounted for through this section then was attributed to
Fan, Fan; Luxenburger, Andreas; Painter, Gavin F; Blanchard, John S
2007-10-09
Mycobacterium tuberculosis and many other members of the Actinomycetes family produce mycothiol, i.e., 1-d-myo-inosityl-2-(N-acetyl-l-cysteinyl)amido-2-deoxy-alpha-d-glucopyranoside (MSH or AcCys-GlcN-Ins), to act against oxidative and antibiotic stress. The biosynthesis of MSH is essential for cell growth and has been proposed to proceed via a biosynthetic pathway involving four key enzymes, MshA-MshD. The MSH biosynthetic enzymes present potential targets for inhibitor design. With this as a long-term goal, we have carried out a kinetic and mechanistic characterization, using steady-state and pre-steady-state approaches, of the recombinant Mycobacterium smegmatis MshC. MshC catalyzes the ATP-dependent condensation of GlcN-Ins and cysteine to form Cys-GlcN-Ins. Initial velocity and inhibition studies show that the steady-state kinetic mechanism of MshC is a Bi Uni Uni Bi Ping Pong mechanism, with ATP binding followed by cysteine binding, release of PPi, binding of GlcN-Ins, followed by the release of Cys-GlcN-Ins and AMP. The steady-state kinetic parameters were determined to be kcat equal to 3.15 s-1, and Km values of 1.8, 0.1, and 0.16 mM for ATP, cysteine, and GlcN-Ins, respectively. A stable bisubstrate analogue, 5'-O-[N-(l-cysteinyl)sulfamonyl]adenosine, exhibits competitive inhibition versus ATP and noncompetitive inhibition versus cysteine, with an inhibition constant of approximately 306 nM versus ATP. Single-turnover reactions of the first and second half reactions were determined using rapid-quench techniques, giving rates of approximately 9.4 and approximately 5.2 s-1, respectively, consistent with the cysteinyl adenylate being a kinetically competent intermediate in the reaction by MshC.
Hydrogeology and simulation of regional ground-water-level declines in Monroe County, Michigan
Reeves, Howard W.; Wright, Kirsten V.; Nicholas, J.R.
2004-01-01
Observed ground-water-level declines from 1991 to 2003 in northern Monroe County, Michigan, are consistent with increased ground-water demands in the region. In 1991, the estimated ground-water use in the county was 20 million gallons per day, and 80 percent of this total was from quarry dewatering. In 2001, the estimated ground-water use in the county was 30 million gallons per day, and 75 percent of this total was from quarry dewatering. Prior to approximately 1990, the ground-water demands were met by capturing natural discharge from the area and by inducing leakage through glacial deposits that cover the bedrock aquifer. Increased ground-water demand after 1990 led to declines in ground-water level as the system moves toward a new steady-state. Much of the available natural discharge from the bedrock aquifer had been captured by the 1991 conditions, and the response to additional withdrawals resulted in the observed widespread decline in water levels. The causes of the observed declines were explored through the use of a regional ground-water-flow model. The model area includes portions of Lenawee, Monroe, Washtenaw, and Wayne Counties in Michigan, and portions of Fulton, Henry, and Lucas Counties in Ohio. Factors, including lowered water-table elevations because of below average precipitation during the time period (1991 - 2001) and reduction in water supply to the bedrock aquifer because of land-use changes, were found to affect the regional system, but these factors did not explain the regional decline. Potential ground-water capture for the bedrock aquifer in Monroe County is limited by the low hydraulic conductivity of the overlying glacial deposits and shales and the presence of dense saline water within the bedrock as it dips into the Michigan Basin to the west and north of the county. Hydrogeologic features of the bedrock and the overlying glacial deposits were included in the model design. An important step of characterizing the bedrock aquifer was the
Voronin, L.M.; Rice, D.E.
1996-01-01
Ground-water flow in glacial sediments and bedrock at Picatinny Arsenal, N.J., was simulated by use of a three-dimensional finite-difference ground- water-flow model. The modeled area includes a 4.3-square-mile area that extends from Picatinny Lake to the Rockaway River. Most of the study area is bounded by the natural hydrologic boundaries of the ground-water system. eophysical logs, lithologic logs, particle-size data, and core data from selected wells and surface geophysical data were analyzed to define the hydrogeologic framework. Hydrogeologic sections and thickness maps define six permeable and three low-permeability layers that are represented in the model as aquifers and confining units, respectively. Hydrologic data incorporated in the model include a rate of recharge from precipitation of 22 inches per year, estimated from long-term precipitation records and estimates of evapotranspiration. Additional recharge from infiltration along valleys was estimated from measured discharge of springs along the adjacent valley walls and from estimates of runoff from upland drainage that flows to the valley floor. Horizontal and vertical hydraulic conductivities of permeable and low-permeability layers were estimated from examination of aquifer-test data, gamma-ray logs, borehole cuttings, and previously published data. Horizontal hydraulic conductivities in glacial sediments range from 10 to 380 feet per day. Vertical hydraulic conductivities of the low-permeability layers range from 0.01 to 0.7 feet per day. The model was calibrated by simulating steady-state conditions during 1989-93 and by closely matching simulated and measured ground-water levels, vertical ground-water-head differences, and streamflow gain and loss. Simulated steady-state potentiometric- surface maps produced for the six permeable layers indicate that ground water in the unconfined material within Picatinny Arsenal flows predominantly toward the center of the valley, where it discharges to Green
Buchmiller, R.C.; Squillace, P.J.; Drustrup, R.D.
1987-01-01
The population served by ground-water supplies in Iowa (fig. L4) is estimated to be about 2,392,000, or 82 percent of the total population (U.S. Geological Survey, 1985, p. 211). The population of Iowa is distributed fairly uniformly throughout the State (fig. IB), with 59 percent residing in rural areas or towns of less than 10,000 (U.S. Bureau of the Census, 1982). Surficial aquifers, the Jordan aquifer, and aquifers that form the uppermost bedrock aquifer in a particular area are most commonly used for drinking-water supplies and usually provide ample amounts of good quality water. However, naturally occurring properties or substances such as hardness, dissolved solids, and radioactivity limit the use of water for drinking purposes in some areas of each of the five principal aquifers (fig. 2/4). Median concentrations of nitrate in all aquifers and radium-226 in all aquifers except the Jordan are within the primary drinking-water standards established by the U.S. Environmental Protection Agency (1986a). Median concentrations for dissolved solids in the surficial, Dakota, and Jordan aquifers exceed secondary drinking-water standards established by the U.S. Environmental Protection Agency (1986b).
Guide to Louisiana's ground-water resources
Stuart, C.G.; Knochenmus, D.D.; McGee, B.D.
1994-01-01
Ground water is one of the most valuable and abundant natural resources of Louisiana. Of the 4-.4 million people who live in the State, 61 percent use ground water as a source for drinking water. Most industrial and rural users and half of the irrigation users in the State rely on ground water. Quantity, however, is not the only aspect that makes ground water so valuable; quality also is important for its use. In most areas, little or no water treatment is required for drinking water and industrial purposes. Knowledge of Louisiana's ground-water resources is needed to ensure proper development and protection of this valuable resource. This report is designed to inform citizens about the availability and quality of ground water in Louisiana. It is not intended as a technical reference; rather, it is a guide to ground water and the significant role this resource plays in the state. Most of the ground water that is used in the State is withdrawn from 13 aquifers and aquifer systems: the Cockfield, Sparta, and Carrizo-Wilcox aquifersin northern Louisiana; Chicot aquifer system, Evangeline aquifer, Jasper aquifer system, and Catahoula aquifer in central and southwestern Louisiana; the Chicot equivalent, Evangeline equivalent, and Jasper equivalent aquifer systems in southeastern Louisiana; and the MississippiRiver alluvial, Red River alluvial, and upland terrace aquifers that are statewide. Ground water is affected by man's activities on the land surface, and the major ground-water concerns in Louisiana are: (1) contamination from surface disposal of hazardous waste, agricultural chemicals, and petroleum products; (2) contamination from surface wastes and saltwater through abandoned wells; (3) saltwater encroachment; and (4) local overdevelopment. Information about ground water in Louisiana is extensive and available to the public. Several State and Federal agencies provide published and unpublished material upon request.
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
of this thesis is on online comprehensive two-dimensional liquid chromatography (online LC×LC) with reverse phase in both dimensions (online RP×RP). Since online RP×RP has not been attempted before within this research group, a significant part of this thesis consists of knowledge and experience gained...
Mimicking Nonequilibrium Steady States with Time-Periodic Driving
Raz, O.; Subaşı, Y.; Jarzynski, C.
2016-04-01
Under static conditions, a system satisfying detailed balance generically relaxes to an equilibrium state in which there are no currents. To generate persistent currents, either detailed balance must be broken or the system must be driven in a time-dependent manner. A stationary system that violates detailed balance evolves to a nonequilibrium steady state (NESS) characterized by fixed currents. Conversely, a system that satisfies instantaneous detailed balance but is driven by the time-periodic variation of external parameters—also known as a stochastic pump (SP)—reaches a periodic state with nonvanishing currents. In both cases, these currents are maintained at the cost of entropy production. Are these two paradigmatic scenarios effectively equivalent? For discrete-state systems, we establish a mapping between nonequilibrium stationary states and stochastic pumps. Given a NESS characterized by a particular set of stationary probabilities, currents, and entropy production rates, we show how to construct a SP with exactly the same (time-averaged) values. The mapping works in the opposite direction as well. These results establish a proof of principle: They show that stochastic pumps are able to mimic the behavior of nonequilibrium steady states, and vice versa, within the theoretical framework of discrete-state stochastic thermodynamics. Nonequilibrium steady states and stochastic pumps are often used to model, respectively, biomolecular motors driven by chemical reactions and artificial molecular machines steered by the variation of external, macroscopic parameters. Our results loosely suggest that anything a biomolecular machine can do, an artificial molecular machine can do equally well. We illustrate this principle by showing that kinetic proofreading, a NESS mechanism that explains the low error rates in biochemical reactions, can be effectively mimicked by a constrained periodic driving.
Relaxation versus adiabatic quantum steady-state preparation
Venuti, Lorenzo Campos; Albash, Tameem; Marvian, Milad; Lidar, Daniel; Zanardi, Paolo
2017-04-01
Adiabatic preparation of the ground states of many-body Hamiltonians in the closed-system limit is at the heart of adiabatic quantum computation, but in reality systems are always open. This motivates a natural comparison between, on the one hand, adiabatic preparation of steady states of Lindbladian generators and, on the other hand, relaxation towards the same steady states subject to the final Lindbladian of the adiabatic process. In this work we thus adopt the perspective that the goal is the most efficient possible preparation of such steady states, rather than ground states. Using known rigorous bounds for the open-system adiabatic theorem and for mixing times, we are then led to a disturbing conclusion that at first appears to doom efforts to build physical quantum annealers: relaxation seems to always converge faster than adiabatic preparation. However, by carefully estimating the adiabatic preparation time for Lindbladians describing thermalization in the low-temperature limit, we show that there is, after all, room for an adiabatic speedup over relaxation. To test the analytically derived bounds for the adiabatic preparation time and the relaxation time, we numerically study three models: a dissipative quasifree fermionic chain, a single qubit coupled to a thermal bath, and the "spike" problem of n qubits coupled to a thermal bath. Via these models we find that the answer to the "which wins" question depends for each model on the temperature and the system-bath coupling strength. In the case of the "spike" problem we find that relaxation during the adiabatic evolution plays an important role in ensuring a speedup over the final-time relaxation procedure. Thus, relaxation-assisted adiabatic preparation can be more efficient than both pure adiabatic evolution and pure relaxation.
Steady-State Plasmas in KT5D Magnetized Torus
Institute of Scientific and Technical Information of China (English)
ZHU Zhenhua; LIU Wandong; WAN Baonian; ZHAO Yanping; LI Jiangang; YAN Longwen; YANG Qingwei; DING Xuantong; XU Min; YU Yi; WANG Zhijiang; LU Ronghua; WEN Yizhi; YU Changxuan; MA Jinxiu; WAN Shude
2007-01-01
Steady-state plasma generated by electron cyclotron resonance (ECR) wave in the KT5D magnetized torus was studied using a fast high-resolution camera and Langmuir probes. It was found that both the discharge patterns taken by the camera and the plasma parameters measured by the probes were very sensitive to the working gas pressure and the magnetic configuration of the torus both without and with vertical fields. There existed fast vertical motion of the plasma. Tentative discussion is presented about the observed phenomena such as the bright resonance layer at a high gas pressure and the wave absorption mechanism at a low pressure. Further explanations should be found.
Steady State Stokes Flow Interpolation for Fluid Control
DEFF Research Database (Denmark)
Bhatacharya, Haimasree; Nielsen, Michael Bang; Bridson, Robert
2012-01-01
Fluid control methods often require surface velocities interpolated throughout the interior of a shape to use the velocity as a feedback force or as a boundary condition. Prior methods for interpolation in computer graphics — velocity extrapolation in the normal direction and potential flow...... — suffer from a common problem. They fail to capture the rotational components of the velocity field, although extrapolation in the normal direction does consider the tangential component. We address this problem by casting the interpolation as a steady state Stokes flow. This type of flow captures...... the rotational components and is suitable for controlling liquid animations where tangential motion is pronounced, such as in a breaking wave...
Quantum-classical correspondence in steady states of nonadiabatic systems
Energy Technology Data Exchange (ETDEWEB)
Fujii, Mikiya; Yamashita, Koichi [Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); CREST, JST, Tokyo 113-8656 (Japan)
2015-12-31
We first present nonadiabatic path integral which is exact formulation of quantum dynamics in nonadiabatic systems. Then, by applying the stationary phase approximations to the nonadiabatic path integral, a semiclassical quantization condition, i.e., quantum-classical correspondence, for steady states of nonadiabatic systems is presented as a nonadiabatic trace formula. The present quantum-classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow degree of freedom, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels.
Full steady-state operation in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Kazarian-Vibert, F.; Litaudon, X.; Moreau, D.; Arslanbekov, R.; Hoang, G.T.; Peysson, Y.
1996-06-01
In order to produce fully non-inductive, Lower Hybrid (LH) driven discharges in a systematic and reproducible manner, new operation modes have been studied on the superconducting TORE SUPRA tokamak. It is shown that this operation mode allows to reach full steady-state within a characteristic time of a few seconds. The underlying physics is described and a detailed analysis of the experiments is made. It is shown, in particular, that this operation scenario generates stable stationary plasmas with improved confinement, so that the so-called `LHEP` regime can be extrapolated to continuous operation. (K.A.). 19 refs.
Full steady state LH scenarios in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Kazarian-Vibert, F.; Litaudon, X.; Arslanbekov, R.; Hoang, G.T.; Moreau, D.; Peysson, Y. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee
1995-12-31
Lower Hybrid discharge have been realised in Tore Supra using feed-back control of the primary circuit voltage such that the loop voltage was maintained exactly to zero near the plasma surface. This new scenario allows the plasma current to float and quickly reach an equilibrium value determined by the current drive efficiency and Lower Hybrid power. Recent experimental results show that, with the new constant flux scenario the coupled plasma and primary currents reach a steady state in less than 10 s which is a good agreement with theoretical expectations. A complete analysis of this scenario is presented. (authors). 8 refs., 3 figs.
Steady-state models of glucose-perturbed Dictyostelium discoideum
Energy Technology Data Exchange (ETDEWEB)
Wright, B.E.; Reimers, J.M.
1988-10-15
Young sorocarps of Dictyostelium discoideum were incubated in the presence of 50 mM (/sup 14/C)glucose, and nine metabolites were isolated over a period of 60 min to determine their specific radioactivity. The program TFLUX was used to construct models consisting of 17 metabolite pools and 40 reactions (excluding external pools). Net glucose uptake was 10% or less in the two experiments chosen for extensive analysis, and a single steady-state model was adequate to describe the data in both cases. Despite differences in metabolite levels, flux, and labeling kinetics, the models of glucose-perturbed metabolism confirm earlier conclusions regarding metabolic compartments.
Steady State Vacuum Ultraviolet Exposure Facility With Automated Calibration Capability
Stueber, Thomas J.; Sechkar, Edward A.; Dever, Joyce A.; Banks, Bruce A.
2000-01-01
NASA Glenn Research Center at Lewis Field designed and developed a steady state vacuum ultraviolet automated (SSVUVa) facility with in situ VUV intensity calibration capability. The automated feature enables a constant accelerated VUV radiation exposure over long periods of testing without breaking vacuum. This test facility is designed to simultaneously accommodate four isolated radiation exposure tests within the SSVUVa vacuum chamber. Computer-control of the facility for long, term continuous operation also provides control and recording of thermocouple temperatures, periodic recording of VUV lamp intensity, and monitoring of vacuum facility status. This paper discusses the design and capabilities of the SSVUVa facility.
Steady-state grain growth in UO{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Galinari, C.M.; Lameiras, F.S. [CDTN/CNEN, Belo Horizonte (Brazil)
1998-06-05
The authors have observed steady-state grain growth in sintered UO{sub 2} pellets of nuclear purity at 2,003 K under H{sub 2}. The behavior of the grain size distribution at different instants is consistent with the grain growth model proposed by one of the authors. The total number of grains was estimated using the Saltykov`s method, and the evolution is in accordance with the model proposed by Rhines and Craig. The parabolic growth law was observed for the mean intercept length with n = 0.4.
Typical pure nonequilibrium steady states and irreversibility for quantum transport.
Monnai, Takaaki; Yuasa, Kazuya
2016-07-01
It is known that each single typical pure state in an energy shell of a large isolated quantum system well represents a thermal equilibrium state of the system. We show that such typicality holds also for nonequilibrium steady states (NESS's). We consider a small quantum system coupled to multiple infinite reservoirs. In the long run, the total system reaches a unique NESS. We identify a large Hilbert space from which pure states of the system are to be sampled randomly and show that the typical pure states well describe the NESS. We also point out that the irreversible relaxation to the unique NESS is important to the typicality of the pure NESS's.
Optimising performance in steady state for a supermarket refrigeration system
DEFF Research Database (Denmark)
Green, Torben; Kinnaert, Michel; Razavi-Far, Roozbeh
2012-01-01
Using a supermarket refrigeration system as an illustrative example, the paper postulates that by appropriately utilising knowledge of plant operation, the plant wide performance can be optimised based on a small set of variables. Focusing on steady state operations, the total system performance...... is shown to predominantly be influenced by the suction pressure. Employing appropriate performance function leads to conclusions on the choice of set-point for the suction pressure that are contrary to the existing practice. Analysis of the resulting data leads to a simple method for finding optimal...
Dendritic cell-development in steady-state and inflammation
Schmid, Michael Alexander
2010-01-01
Dendritic cells (DC), the major antigen-presenting cells, continuously need to be regenerated from bone marrow (BM) hematopoietic stem and progenitor cells (HSPC). What intermediate progenitors exist on the way to DC generation and what external factors act on these in steady-state and during inflammation, has not been addressed in detail. Flt3L is a non-redundant cytokine in DC development and the generation of DCs was shown to proceed along both Flt3+ common lymphoid and common myeloid prog...
Multiple nonequilibrium steady states for one-dimensional heat flow.
Zhang, F; Isbister, D J; Evans, D J
2001-08-01
A nonequilibrium molecular dynamics model of heat flow in one-dimensional lattices is shown to have multiple steady states for any fixed heat field strength f(e) ranging from zero to a certain positive value. We demonstrate that, depending on the initial conditions, there are at least two possibilities for the system's evolution: (i) formation of a stable traveling wave (soliton), and (ii) chaotic motion throughout the entire simulation. The percentage of the soliton-generating trajectories is zero for small field strength f(e), but increases sharply to unity over a critical region of the parameter f(e).
Typical pure nonequilibrium steady states and irreversibility for quantum transport
Monnai, Takaaki; Yuasa, Kazuya
2016-07-01
It is known that each single typical pure state in an energy shell of a large isolated quantum system well represents a thermal equilibrium state of the system. We show that such typicality holds also for nonequilibrium steady states (NESS's). We consider a small quantum system coupled to multiple infinite reservoirs. In the long run, the total system reaches a unique NESS. We identify a large Hilbert space from which pure states of the system are to be sampled randomly and show that the typical pure states well describe the NESS. We also point out that the irreversible relaxation to the unique NESS is important to the typicality of the pure NESS's.
A Novel Wireless TCP and its Steady State Throughput Model
Institute of Scientific and Technical Information of China (English)
YAO Ling; JI Hong; YUE Guang-xin
2004-01-01
Unlike wired networks, random packet loss due to bit errors may cause significant performance degradation of Transmission Control Protocol (TCP). We propose and study a novel end-to-end congestion control mechanism called TCP-LD (Loss Detection) that is simple and effective for dealing with random packet loss. We also give its steady state throughput model. Both the ns2 and numerical simulation results show that our scheme can achieve significant throughput improvements without adversely affecting other concurrent TCP connections, including other concurrent Reno connections both in wired and wireless environment.
Non-steady-state aerosol filtration in nanostructured fibrous media.
Przekop, Rafal; Gradoń, Leon
2011-06-28
The filtration of aerosol particles using composites of nano- and microsized fibrous structures is a promising method for the effective separation of nanoparticles from gases. A multi-scale physical system describing the flow pattern and particle deposition at a non-steady-state condition requires an advanced method of modelling. The combination of lattice Boltzmann and Brownian dynamics was used for analysis of the particle deposition pattern in a fibrous system. The dendritic structures of deposits for neutral and charged fibres and particles are present. The efficiency of deposition, deposit morphology, porosity and fractal dimension were calculated for a selected operational condition of the process.
Nonequilibrium steady-state circulation and heat dissipation functional.
Qian, H
2001-08-01
A nonequilibrium steady-state (NESS), different from an equilibrium, is sustained by circular balance rather than detailed balance. The circular fluxes are driven by energy input and heat dissipation, accompanied by a positive entropy production. Based on a Master equation formalism for NESS, we show the circulation is intimately related to the recently studied Gallavotti-Cohen symmetry of heat dissipation functional, which in turn suggests a Boltzmann's formulalike relation between rate constants and energy in NESS. Expanding this unifying view on NESS to diffusion is discussed.
Stabilizing unstable steady states using multiple delay feedback control.
Ahlborn, Alexander; Parlitz, Ulrich
2004-12-31
Feedback control with different and independent delay times is introduced and shown to be an efficient method for stabilizing fixed points (equilibria) of dynamical systems. In comparison to other delay based chaos control methods multiple delay feedback control is superior for controlling steady states and works also for relatively large delay times (sometimes unavoidable in experiments due to system dead times). To demonstrate this approach for stabilizing unstable fixed points we present numerical simulations of Chua's circuit and a successful experimental application for stabilizing a chaotic frequency doubled Nd-doped yttrium aluminum garnet laser.
Geotechnics - the key to ground water protection
DEFF Research Database (Denmark)
Baumann, Jens; Foged, Niels; Jørgensen, Peter
2000-01-01
During the past 5 to 10 years research into ground water protection has proved that fractures in clay till may increase the hydraulic conductivity and herby the vulnerability of the ground water considerably. However, research has not identified a non-expensive and efficient method to map...
Procedures for ground-water investigations
Energy Technology Data Exchange (ETDEWEB)
1992-12-01
This manual was developed by the Pacific Northwest Laboratory (PNL) to document the procedures used to carry out and control the technical aspects of ground-water investigations at the PNL. Ground-water monitoring procedures are developed and used in accordance with the PNL Quality Assurance Program.
Hydrogeologic Setting and Ground-Water Flow in the Leetown Area, West Virginia
Kozar, Mark D.; Weary, David J.; Paybins, Katherine S.; Pierce, Herbert A.
2007-01-01
The Leetown Science Center is a research facility operated by the U.S. Geological Survey that occupies approximately 455-acres near Kearneysville, Jefferson County, West Virginia. Aquatic and fish research conducted at the Center requires adequate supplies of high-quality, cold ground water. Three large springs and three production wells currently (in 2006) supply water to the Center. The recent construction of a second research facility (National Center for Cool and Cold Water Aquaculture) operated by the U.S. Department of Agriculture and co-located on Center property has placed additional demands on available water resources in the area. A three-dimensional steady-state finite-difference ground-water flow model was developed to simulate ground-water flow in the Leetown area and was used to assess the availability of ground water to sustain current and anticipated future demands. The model also was developed to test a conceptual model of ground-water flow in the complex karst aquifer system in the Leetown area. Due to the complexity of the karst aquifer system, a multidisciplinary research study was required to define the hydrogeologic setting. Geologic mapping, surface- and borehole-geophysical surveys, stream base-flow surveys, and aquifer tests were conducted to provide the hydrogeologic data necessary to develop and calibrate the model. It would not have been possible to develop a numerical model of the study area without the intensive data collection and methods developments components of the larger, more comprehensive hydrogeologic investigation. Results of geologic mapping and surface-geophysical surveys verified the presence of several prominent thrust faults and identified additional faults and other complex geologic structures (including overturned anticlines and synclines) in the area. These geologic structures are known to control ground-water flow in the region. Results of this study indicate that cross-strike faults and fracture zones are major
Hanford site ground water protection management plan
Energy Technology Data Exchange (ETDEWEB)
1994-10-01
Ground water protection at the Hanford Site consists of preventative and remedial measures that are implemented in compliance with a variety of environmental regulations at local, state, and federal levels. These measures seek to ensure that the resource can sustain a broad range of beneficial uses. To effectively coordinate and ensure compliance with applicable regulations, the U.S. Department of Energy has issued DOE Order 5400.1 (DOE 1988a). This order requires all U.S. Department of Energy facilities to prepare separate ground water protection program descriptions and plans. This document describes the Ground Water Protection Management Plan (GPMP) for the Hanford Site located in the state of Washington. DOE Order 5400.1 specifies that the GPMP covers the following general topical areas: (1) documentation of the ground water regime; (2) design and implementation of a ground water monitoring program to support resource management and comply with applicable laws and regulations; (3) a management program for ground water protection and remediation; (4) a summary and identification of areas that may be contaminated with hazardous waste; (5) strategies for controlling hazardous waste sources; (6) a remedial action program; and (7) decontamination, decommissioning, and related remedial action requirements. Many of the above elements are currently covered by existing programs at the Hanford Site; thus, one of the primary purposes of this document is to provide a framework for coordination of existing ground water protection activities. The GPMP provides the ground water protection policy and strategies for ground water protection/management at the Hanford Site, as well as an implementation plan to improve coordination of site ground water activities.
Steady-state flow properties of amorphous materials
Jadhao, Vikram; O'Connor, Thomas; Robbins, Mark
2015-03-01
Molecular dynamics (MD) simulations are used to investigate the steady-state shear flow curves of a standard glass model: the bidisperse Lennard-Jones system. For a wide range of temperatures in the neighborhood of the glass transition temperature Tg predicted by the mode coupling theory, we compute the steady-state shear stress and viscosity as a function of the shear rate γ ˙. At temperatures near and above Tg, the stress crosses over from linear Newtonian behavior at low rates to power law shear-thinning at high rates. As T decreases below Tg, the stress shows a plateau, becoming nearly rate-independent at low γ ˙. There is a weak increase in stress that is consistent with Eyring theory for activated flow of a solid. We find that when the strain rate is reduced to extremely low values, Newtonian behavior appears once more. Insights gained from these simulations are applied to the computation of flow curves of a well-established boundary lubricant: squalane. In the elastohydrodynamic regime, squalane responds like a glassy solid with an Eyring-like response, but at low rates it has a relatively small Newtonian viscosity. Supported by the Army Research Laboratory under Grant W911NF-12-2-0022.
Transient and steady-state selection in the striatal microcircuit.
Tomkins, Adam; Vasilaki, Eleni; Beste, Christian; Gurney, Kevin; Humphries, Mark D
2013-01-01
Although the basal ganglia have been widely studied and implicated in signal processing and action selection, little information is known about the active role the striatal microcircuit plays in action selection in the basal ganglia-thalamo-cortical loops. To address this knowledge gap we use a large scale three dimensional spiking model of the striatum, combined with a rate coded model of the basal ganglia-thalamo-cortical loop, to asses the computational role the striatum plays in action selection. We identify a robust transient phenomena generated by the striatal microcircuit, which temporarily enhances the difference between two competing cortical inputs. We show that this transient is sufficient to modulate decision making in the basal ganglia-thalamo-cortical circuit. We also find that the transient selection originates from a novel adaptation effect in single striatal projection neurons, which is amenable to experimental testing. Finally, we compared transient selection with models implementing classical steady-state selection. We challenged both forms of model to account for recent reports of paradoxically enhanced response selection in Huntington's disease patients. We found that steady-state selection was uniformly impaired under all simulated Huntington's conditions, but transient selection was enhanced given a sufficient Huntington's-like increase in NMDA receptor sensitivity. Thus our models provide an intriguing hypothesis for the mechanisms underlying the paradoxical cognitive improvements in manifest Huntington's patients.
Transient and steady-state selection in the striatal microcircuit
Directory of Open Access Journals (Sweden)
Adam eTomkins
2014-01-01
Full Text Available Although the basal ganglia have been widely studied and implicated in signal processing and action selection, little information is known about the active role the striatal microcircuit plays in action selection in the basal ganglia-thalamo-cortical loops. To address this knowledge gap we use a large scale three dimensional spiking model of the striatum, combined with a rate coded model of the basal ganglia-thalamo-cortical loop, to asses the computational role the striatum plays in action selection. We identify a robust transient phenomena generated by the striatal microcircuit, which temporarily enhances the difference between two competing cortical inputs. We show that this transient is sufficient to modulate decision making in the basal ganglia-thalamo-cortical circuit. We also find that the transient selection originates from a novel adaptation effect in single striatal projection neurons, which is amenable to experimental testing. Finally, we compared transient selection with models implementing classical steady-state selection. We challenged both forms of model to account for recent reports of paradoxically enhanced response selection in Huntington's Disease patients. We found that steady-state selection was uniformly impaired under all simulated Huntington's conditions, but transient selection was enhanced given a sufficient Huntington's-like increase in NMDA receptor sensitivity. Thus our models provide an intriguing hypothesis for the mechanisms underlying the paradoxical cognitive improvements in manifest Huntington's patients.
Steady states of the parametric rotator and pendulum
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@fis.mda.cinvestav.m [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2010-11-15
We discuss several steady-state rotation and oscillation modes of the planar parametric rotator and pendulum with damping. We consider a general elliptic trajectory of the suspension point for both rotator and pendulum, for the latter at an arbitrary angle with gravity, with linear and circular trajectories as particular cases. We treat the damped, nonlinear equation of motion of the parametric rotator and pendulum perturbatively for small parametric excitation and damping, although our perturbative approach can be extended to other regimes as well. Our treatment involves only ordinary second-order differential equations with constant coefficients, and provides numerically accurate perturbative solutions in terms of elementary functions. Some of the steady-state rotation and oscillation modes studied here have not been discussed in the previous literature. Other well-known ones, such as parametric resonance and the inverted pendulum, are extended to elliptic parametric excitation tilted with respect to gravity. The results presented here should be accessible to advanced undergraduates, and of interest to graduate students and specialists in the field of nonlinear mechanics.
Classical Orbital Paramagnetism in Non-equilibrium Steady State
Indian Academy of Sciences (India)
Avinash A. Deshpande; N. Kumar
2017-09-01
We report the results of our numerical simulation of classical-dissipative dynamics of a charged particle subjected to a non-Markovian stochastic forcing. We find that the system develops a steady-state orbital magnetic moment in the presence of a static magnetic field. Very significantly, the sign of the orbital magnetic moment turns out to be paramagnetic for our choice of parameters, varied over a wide range. This is shown specifically for the case of classical dynamics driven by a Kubo–Anderson type non-Markovian noise. Natural spatial boundary condition was imposed through (1) a soft (harmonic) confining potential, and (2) a hard potential, approximating a reflecting wall. There was no noticeable qualitative difference. What appears to be crucial to the orbital magnetic effect noticed here is the non-Markovian property of the driving noise chosen. Experimental realization of this effect on the laboratory scale, and its possible implications are briefly discussed. We would like to emphasize that the above steady-state classical orbital paramagnetic moment complements, rather than contradicts the Bohr–van Leeuwen (BvL) theorem on the absence of classical orbital diamagnetism in thermodynamic equilibrium.
Steady States and Universal Conductance in a Quenched Luttinger Model
Langmann, Edwin; Lebowitz, Joel L.; Mastropietro, Vieri; Moosavi, Per
2016-05-01
We obtain exact analytical results for the evolution of a 1+1-dimensional Luttinger model prepared in a domain wall initial state, i.e., a state with different densities on its left and right sides. Such an initial state is modeled as the ground state of a translation invariant Luttinger Hamiltonian {H_{λ}} with short range non-local interaction and different chemical potentials to the left and right of the origin. The system evolves for time t > 0 via a Hamiltonian {H_{λ'}} which differs from {H_{λ}} by the strength of the interaction. Asymptotically in time, as {t to &infty}; , after taking the thermodynamic limit, the system approaches a translation invariant steady state. This final steady state carries a current I and has an effective chemical potential difference {μ+ - μ-} between right- (+) and left- (-) moving fermions obtained from the two-point correlation function. Both I and {μ+ - μ-} depend on {λ} and {λ'} . Only for the case {λ = λ' = 0} does {μ+ - μ-} equal the difference in the initial left and right chemical potentials. Nevertheless, the Landauer conductance for the final state, {G = I/(μ+ - μ-)} , has a universal value equal to the conductance quantum {e^2/h} for the spinless case.
Integrated stoichiometric, thermodynamic and kinetic modelling of steady state metabolism.
Fleming, R M T; Thiele, I; Provan, G; Nasheuer, H P
2010-06-07
The quantitative analysis of biochemical reactions and metabolites is at frontier of biological sciences. The recent availability of high-throughput technology data sets in biology has paved the way for new modelling approaches at various levels of complexity including the metabolome of a cell or an organism. Understanding the metabolism of a single cell and multi-cell organism will provide the knowledge for the rational design of growth conditions to produce commercially valuable reagents in biotechnology. Here, we demonstrate how equations representing steady state mass conservation, energy conservation, the second law of thermodynamics, and reversible enzyme kinetics can be formulated as a single system of linear equalities and inequalities, in addition to linear equalities on exponential variables. Even though the feasible set is non-convex, the reformulation is exact and amenable to large-scale numerical analysis, a prerequisite for computationally feasible genome scale modelling. Integrating flux, concentration and kinetic variables in a unified constraint-based formulation is aimed at increasing the quantitative predictive capacity of flux balance analysis. Incorporation of experimental and theoretical bounds on thermodynamic and kinetic variables ensures that the predicted steady state fluxes are both thermodynamically and biochemically feasible. The resulting in silico predictions are tested against fluxomic data for central metabolism in Escherichia coli and compare favourably with in silico prediction by flux balance analysis.
Steady-State ALPS for Real-Valued Problems
Hornby, Gregory S.
2009-01-01
The two objectives of this paper are to describe a steady-state version of the Age-Layered Population Structure (ALPS) Evolutionary Algorithm (EA) and to compare it against other GAs on real-valued problems. Motivation for this work comes from our previous success in demonstrating that a generational version of ALPS greatly improves search performance on a Genetic Programming problem. In making steady-state ALPS some modifications were made to the method for calculating age and the method for moving individuals up layers. To demonstrate that ALPS works well on real-valued problems we compare it against CMA-ES and Differential Evolution (DE) on five challenging, real-valued functions and on one real-world problem. While CMA-ES and DE outperform ALPS on the two unimodal test functions, ALPS is much better on the three multimodal test problems and on the real-world problem. Further examination shows that, unlike the other GAs, ALPS maintains a genotypically diverse population throughout the entire search process. These findings strongly suggest that the ALPS paradigm is better able to avoid premature convergence then the other GAs.
Classical Orbital Paramagnetism in Non-equilibrium Steady State
Deshpande, Avinash A.; Kumar, N.
2017-09-01
We report the results of our numerical simulation of classical-dissipative dynamics of a charged particle subjected to a non-Markovian stochastic forcing. We find that the system develops a steady-state orbital magnetic moment in the presence of a static magnetic field. Very significantly, the sign of the orbital magnetic moment turns out to be paramagnetic for our choice of parameters, varied over a wide range. This is shown specifically for the case of classical dynamics driven by a Kubo-Anderson type non-Markovian noise. Natural spatial boundary condition was imposed through (1) a soft (harmonic) confining potential, and (2) a hard potential, approximating a reflecting wall. There was no noticeable qualitative difference. What appears to be crucial to the orbital magnetic effect noticed here is the non-Markovian property of the driving noise chosen. Experimental realization of this effect on the laboratory scale, and its possible implications are briefly discussed. We would like to emphasize that the above steady-state classical orbital paramagnetic moment complements, rather than contradicts the Bohr-van Leeuwen (BvL) theorem on the absence of classical orbital diamagnetism in thermodynamic equilibrium.
Steady States and Universal Conductance in a Quenched Luttinger Model
Langmann, Edwin; Lebowitz, Joel L.; Mastropietro, Vieri; Moosavi, Per
2017-01-01
We obtain exact analytical results for the evolution of a 1+1-dimensional Luttinger model prepared in a domain wall initial state, i.e., a state with different densities on its left and right sides. Such an initial state is modeled as the ground state of a translation invariant Luttinger Hamiltonian {H_{λ}} with short range non-local interaction and different chemical potentials to the left and right of the origin. The system evolves for time t > 0 via a Hamiltonian {H_{λ'}} which differs from {H_{λ}} by the strength of the interaction. Asymptotically in time, as {t to ∞}, after taking the thermodynamic limit, the system approaches a translation invariant steady state. This final steady state carries a current I and has an effective chemical potential difference {μ+ - μ-} between right- (+) and left- (-) moving fermions obtained from the two-point correlation function. Both I and {μ+ - μ-} depend on {λ} and {λ'}. Only for the case {λ = λ' = 0} does {μ+ - μ-} equal the difference in the initial left and right chemical potentials. Nevertheless, the Landauer conductance for the final state, {G = I/(μ+ - μ-)}, has a universal value equal to the conductance quantum {e^2/h} for the spinless case.
Calculations of two-fluid magnetohydrodynamic axisymmetric steady-states
Ferraro, N. M.; Jardin, S. C.
2009-11-01
M3D- C1 is an implicit, high-order finite element code for the solution of the time-dependent nonlinear two-fluid magnetohydrodynamic equations [S.C. Jardin, J. Breslau, N. Ferraro, A high-order implicit finite element method for integrating the two-fluid magnetohydrodynamic equations in two dimensions, J. Comp. Phys. 226 (2) (2007) 2146-2174]. This code has now been extended to allow computations in toroidal geometry. Improvements to the spatial integration and time-stepping algorithms are discussed. Steady-states of a resistive two-fluid model, self-consistently including flows, anisotropic viscosity (including gyroviscosity) and heat flux, are calculated for diverted plasmas in geometries typical of the National Spherical Torus Experiment (NSTX) [M. Ono et al., Exploration of spherical torus physics in the NSTX device, Nucl. Fusion 40 (3Y) (2000) 557-561]. These states are found by time-integrating the dynamical equations until the steady-state is reached, and are therefore stationary or statistically steady on both magnetohydrodynamic and transport time-scales. Resistively driven cross-surface flows are found to be in close agreement with Pfirsch-Schlüter theory. Poloidally varying toroidal flows are in agreement with comparable calculations [A.Y. Aydemir, Shear flows at the tokamak edge and their interaction with edge-localized modes, Phys. Plasmas 14]. New effects on core toroidal rotation due to gyroviscosity and a local particle source are observed.
Nonequilibrium many-body steady states via Keldysh formalism
Maghrebi, Mohammad F.; Gorshkov, Alexey V.
2016-01-01
Many-body systems with both coherent dynamics and dissipation constitute a rich class of models which are nevertheless much less explored than their dissipationless counterparts. The advent of numerous experimental platforms that simulate such dynamics poses an immediate challenge to systematically understand and classify these models. In particular, nontrivial many-body states emerge as steady states under nonequilibrium dynamics. While these states and their phase transitions have been studied extensively with mean-field theory, the validity of the mean-field approximation has not been systematically investigated. In this paper, we employ a field-theoretic approach based on the Keldysh formalism to study nonequilibrium phases and phase transitions in a variety of models. In all cases, a complete description via the Keldysh formalism indicates a partial or complete failure of the mean-field analysis. Furthermore, we find that an effective temperature emerges as a result of dissipation, and the universal behavior including the dynamics near the steady state is generically described by a thermodynamic universality class.
2005-12-01
choice of a steady state control is completely independent from the choice of a stabilizing control law. This separation is key for the methods we will...develop for steady state optimization in later sections. Combining the steady state with the stabilizing control , we can express the control law as u...for stabilizing control and optimization methods for steady state control, both unconstrained and constrained, we were able to produce promising results
Two dimensional unstable scar statistics.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)
2006-12-01
This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.
Juday, Richard D.
1992-01-01
Modified vernier scale gives accurate two-dimensional coordinates from maps, drawings, or cathode-ray-tube displays. Movable circular overlay rests on fixed rectangular-grid overlay. Pitch of circles nine-tenths that of grid and, for greatest accuracy, radii of circles large compared with pitch of grid. Scale enables user to interpolate between finest divisions of regularly spaced rule simply by observing which mark on auxiliary vernier rule aligns with mark on primary rule.
Optimization of ground-water withdrawal in the lower Fox River communities, Wisconsin
Walker, J.F.; Saad, D.A.; Krohelski, J.T.
1998-01-01
Pumping from closely spaced wells in the Central Brown County area and the Fox Cities area near the north shore of Lake Winnebago has resulted in the formation of deep cones of depression in the vicinity of the two pumping centers. Water-level measurements indicate there has been a steady decline in water levels in the vicinity of these two pumping centers for the past 50 years. This report describes the use of ground-water optimization modeling to efficiently allocate the ground-water resources in the Lower Fox River Valley. A 3-dimensional ground-water flow model was used along with optimization techniques to determine the optimal withdrawal rates for a variety of management alternatives. The simulations were conducted separately for the Central Brown County area and the Fox Cities area. For all simulations, the objective of the optimization was to maximize total ground-water withdrawals. The results indicate that ground water can supply nearly all of the projected 2030 demand for Central Brown County municipalities if all of the wells are managed (including the city of Green Bay), 8 new wells are installed, and the water-levels are allowed to decline to 100 ft below the bottom of the confining unit. Ground water can supply nearly all of the projected 2030 demand for the Fox Cities if the municipalities in Central Brown County convert to surface water; if Central Brown County municipalities follow the optimized strategy described above, there will be a considerable shortfall of available ground water for the Fox Cities communities. Relaxing the water-level constraint in a few wells, however, would likely result in increased availability of water. In all cases examined, optimization alternatives result in a rebound of the steady-state water levels due to projected 2030 withdrawal rates to levels at or near the bottom of the confining unit, resulting in increased well capacity. Because the simulations are steady-state, if all of the conditions of the model remain
Simulation of regional ground-water flow in the Upper Deschutes Basin, Oregon
Gannett, Marshall W.; Lite, Kenneth E.
2004-01-01
This report describes a numerical model that simulates regional ground-water flow in the upper Deschutes Basin of central Oregon. Ground water and surface water are intimately connected in the upper Deschutes Basin and most of the flow of the Deschutes River is supplied by ground water. Because of this connection, ground-water pumping and reduction of artificial recharge by lining leaking irrigation canals can reduce the amount of ground water discharging to streams and, consequently, streamflow. The model described in this report is intended to help water-management agencies and the public evaluate how the regional ground-water system and streamflow will respond to ground-water pumping, canal lining, drought, and other stresses. Ground-water flow is simulated in the model by the finite-difference method using MODFLOW and MODFLOWP. The finite-difference grid consists of 8 layers, 127 rows, and 87 columns. All major streams and most principal tributaries in the upper Deschutes Basin are included. Ground-water recharge from precipitation was estimated using a daily water-balance approach. Artificial recharge from leaking irrigation canals and on-farm losses was estimated from diversion and delivery records, seepage studies, and crop data. Ground-water pumpage for irrigation and public water supplies, and evapotranspiration are also included in the model. The model was calibrated to mean annual (1993-95) steady-state conditions using parameter-estimation techniques employing nonlinear regression. Fourteen hydraulic-conductivity parameters and two vertical conductance parameters were determined using nonlinear regression. Final parameter values are all within expected ranges. The general shape and slope of the simulated water-table surface and overall hydraulic-head distribution match the geometry determined from field measurements. The fitted standard deviation for hydraulic head is about 76 feet. The general magnitude and distribution of ground-water discharge to
Ground-Water Protection and Monitoring Program
Energy Technology Data Exchange (ETDEWEB)
Dresel, P.E.
1995-06-01
This section of the 1994 Hanford Site Environmental Report summarizes the ground-water protection and monitoring program strategy for the Hanford Site in 1994. Two of the key elements of this strategy are to (1) protect the unconfined aquifer from further contamination, and (2) conduct a monitoring program to provide early warning when contamination of ground water does occur. The monitoring program at Hanford is designed to document the distribution and movement of existing ground-water contamination and provides a historical baseline for evaluating current and future risk from exposure to the contamination and for deciding on remedial action options.
40 CFR 265.91 - Ground-water monitoring system.
2010-07-01
... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Ground-water monitoring system. 265.91... DISPOSAL FACILITIES Ground-Water Monitoring § 265.91 Ground-water monitoring system. (a) A ground-water monitoring system must be capable of yielding ground-water samples for analysis and must consist of: (1...
Steady-state organization of binary mixtures by active impurities
DEFF Research Database (Denmark)
Sabra, Mads Christian; Gilhøj, Henriette; Mouritsen, Ole G.
1998-01-01
The structural reorganization of a phase-separated binary mixture in the presence of an annealed dilution of active impurities is studied by computer-simulation techniques via a simple two-dimensional lattice-gas model. The impurities, each of which has two internal states with different affinity...
Steady States in SIRS Epidemical Model of Mobile Individuals
Zhang, Duan-Ming; He, Min-Hua; Yu, Xiao-Ling; Pan, Gui-Jun; Sun, Hong-Zhang; Su, Xiang-Ying; Sun, Fan; Yin, Yan-Ping; Li, Rui; Liu, Dan
2006-01-01
We consider an epidemical model within socially interacting mobile individuals to study the behaviors of steady states of epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations, we recover the usual epidemic behavior with critical thresholds δc and pc below which infectious disease dies out. For the population density δ far above δc, it is found that there is linear relationship between contact rate λ and the population density δ in the main. At the same time, the result obtained from mean-field approximation is compared with our numerical result, and it is found that these two results are similar by and large but not completely the same.
Relativistic Hydrodynamics and Non-Equilibrium Steady States
Spillane, Michael
2015-01-01
We review recent interest in the relativistic Riemann problem as a method for generating a non-equilibrium steady state. In the version of the problem under con- sideration, the initial conditions consist of a planar interface between two halves of a system held at different temperatures in a hydrodynamic regime. The new double shock solutions are in contrast with older solutions that involve one shock and one rarefaction wave. We use numerical simulations to show that the older solutions are preferred. Briefly we discuss the effects of a conserved charge. Finally, we discuss deforming the relativistic equations with a nonlinear term and how that deformation affects the temperature and velocity in the region connecting the asymptotic fluids.
Steady-State Density Functional Theory for Finite Bias Conductances.
Stefanucci, G; Kurth, S
2015-12-09
In the framework of density functional theory, a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the steady current as basic variables. We prove that, in a finite window around zero bias, there is a one-to-one map between the basic variables and both local potential on as well as bias across the junction. The resulting Kohn-Sham system features two exchange-correlation (xc) potentials, a local xc potential, and an xc contribution to the bias. For weakly coupled junctions the xc potentials exhibit steps in the density-current plane which are shown to be crucial to describe the Coulomb blockade diamonds. At small currents these steps emerge as the equilibrium xc discontinuity bifurcates. The formalism is applied to a model benzene junction, finding perfect agreement with the orthodox theory of Coulomb blockade.
NASA Lewis Steady-State Heat Pipe Code Architecture
Mi, Ye; Tower, Leonard K.
2013-01-01
NASA Glenn Research Center (GRC) has developed the LERCHP code. The PC-based LERCHP code can be used to predict the steady-state performance of heat pipes, including the determination of operating temperature and operating limits which might be encountered under specified conditions. The code contains a vapor flow algorithm which incorporates vapor compressibility and axially varying heat input. For the liquid flow in the wick, Darcy s formula is employed. Thermal boundary conditions and geometric structures can be defined through an interactive input interface. A variety of fluid and material options as well as user defined options can be chosen for the working fluid, wick, and pipe materials. This report documents the current effort at GRC to update the LERCHP code for operating in a Microsoft Windows (Microsoft Corporation) environment. A detailed analysis of the model is presented. The programming architecture for the numerical calculations is explained and flowcharts of the key subroutines are given
Steady State Rheological Characteristic of Semisolid Magnesium Alloy
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-15000 simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.
Quantally fed steady-state domain distributions in Stochastic Inflation
Bellini, M; Deza, R R; Bellini, Mauricio; Sisterna, Pablo D.; Deza, Roberto R.
2000-01-01
Within the framework of stochastic inflationary cosmology we derive esteady-state distributions P_c(V) of domains in comoving coordinates, under the assumption of slow-rolling and for two specific choices of the coarse-grained inflaton potential $V(\\Phi)$. We model the process as a Starobinsky-like equation in V-space plus a time-independent source term P_w(V) which carries (phenomenologically) quantum-mechanical information drawn from either of two known solutions of the Wheeler-De Witt equation: Hartle-Hawking's and Vilenkin's wave functions. The presence of the source term leads to the existence of nontrivial steady-state distributions P^w_c(V). The relative efficiencies of both mechanisms at different scales are compared for the proposed potentials.
Factorised steady states and condensation transitions in nonequilibrium systems
Indian Academy of Sciences (India)
M R Evans
2005-06-01
Systems driven out of equilibrium can often exhibit behaviour not seen in systems in thermal equilibrium – for example phase transitions in one-dimensional systems. In this talk I will review a simple model of a nonequilibrium system known as the `zero-range process' and its recent developments. The nonequilibrium stationary state of this model factorises and this property allows a detailed analysis of several `condensation' transitions wherein a finite fraction of the constituent particles condenses onto a single lattice site. I will then consider a more general class of mass transport models, encompassing continuous mass variables and discrete time updating, and present a necessary and sufficient condition for the steady state to factorise. The property of factorisation again allows an analysis of the condensation transitions which may occur.
Manifest and Subtle Cyclic Behavior in Nonequilibrium Steady States
Zia, R K P; Mandal, Dibyendu; Fox-Kemper, Baylor
2016-01-01
Many interesting phenomena in nature are described by stochastic processes with irreversible dynamics. To model these phenomena, we focus on a master equation or a Fokker-Planck equation with rates which violate detailed balance. When the system settles in a stationary state, it will be a nonequilibrium steady state (NESS), with time independent probability distribution as well as persistent probability current loops. The observable consequences of the latter are explored. In particular, cyclic behavior of some form must be present: some are prominent and manifest, while others are more obscure and subtle. We present a theoretical framework to analyze such properties, introducing the notion of "probability angular momentum" and its distribution. Using several examples, we illustrate the manifest and subtle categories and how best to distinguish between them. These techniques can be applied to reveal the NESS nature of a wide range of systems in a large variety of areas. We illustrate with one application: var...
Dust remobilization in fusion plasmas under steady state conditions
Tolias, P.; Ratynskaia, S.; De Angeli, M.; De Temmerman, G.; Ripamonti, D.; Riva, G.; Bykov, I.; Shalpegin, A.; Vignitchouk, L.; Brochard, F.; Bystrov, K.; Bardin, S.; Litnovsky, A.
2016-02-01
The first combined experimental and theoretical studies of dust remobilization by plasma forces are reported. The main theoretical aspects of remobilization in fusion devices under steady state conditions are analyzed. In particular, the dominant role of adhesive forces is highlighted and generic remobilization conditions—direct lift-up, sliding, rolling—are formulated. A novel experimental technique is proposed, based on controlled adhesion of dust grains on tungsten samples combined with detailed mapping of the dust deposition profile prior and post plasma exposure. Proof-of-principle experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are presented. The versatile environment of the linear device Pilot-PSI allowed for experiments with different magnetic field topologies and varying plasma conditions that were complemented with camera observations.
Entanglement structure of non-equilibrium steady states
Mahajan, Raghu; Mumford, Sam; Tubman, Norm; Swingle, Brian
2016-01-01
We study the problem of calculating transport properties of interacting quantum systems, specifically electrical and thermal conductivities, by computing the non-equilibrium steady state (NESS) of the system biased by contacts. Our approach is based on the structure of entanglement in the NESS. With reasonable physical assumptions, we show that a NESS close to local equilibrium is lightly entangled and can be represented via a computationally efficient tensor network. We further argue that the NESS may be found by dynamically evolving the system within a manifold of appropriate low entanglement states. A physically realistic law of dynamical evolution is Markovian open system dynamics, or the Lindblad equation. We explore this approach in a well-studied free fermion model where comparisons with the literature are possible. We study both electrical and thermal currents with and without disorder, and compute entropic quantities such as mutual information and conditional mutual information. We conclude with a di...
Stationary Distribution and Thermodynamic Relation in Nonequilibrium Steady States
Komatsu, Teruhisa S.
2010-01-01
We describe our recent attempts toward statistical mechanics and thermodynamics for nonequilibrium steady states (NESS) realized, e.g., in a heat conducting system. Our first result is a simple expression of the probability distribution (of microscopic states) of a NESS. Our second result is a natural extension of the thermodynamic Clausius relation and a definition of an accompanying entropy in NESS. This entropy coincides with the normalization constant appearing in the above mentioned microscopic expression of NESS, and has an expression similar to the Shannon entropy (with a further symmetrization). The NESS entropy proposed here is a clearly defined measurable quantity even in a system with a large degrees of freedom. We numerically measure the NESS entropy in hardsphere fluid systems with a heat current, by observing energy exchange between the system and the heat baths when the temperatures of the baths are changed according to specified protocols.
Steady-State Chemotactic Response in E. coli
Kafri, Yariv
2007-01-01
The bacterium E. coli maneuvers itself to regions with high chemoattractant concentrations by performing two stereotypical moves: `runs', in which it moves in near straight lines, and `tumbles', in which it does not advance but changes direction randomly. The duration of each move is stochastic and depends upon the chemoattractant concentration experienced in the recent past. We relate this stochastic behavior to the steady-state density of a bacterium population, and we derive the latter as a function of chemoattractant concentration. In contrast to earlier treatments, here we account for the effects of temporal correlations and variable tumbling durations. A range of behaviors obtains, that depends subtly upon several aspects of the system - memory, correlation, and tumbling stochasticity in particular.
Fast Prediction Method for Steady-State Heat Convection
Wáng, Yì
2012-03-14
A reduced model by proper orthogonal decomposition (POD) and Galerkin projection methods for steady-state heat convection is established on a nonuniform grid. It was verified by thousands of examples that the results are in good agreement with the results obtained from the finite volume method. This model can also predict the cases where model parameters far exceed the sample scope. Moreover, the calculation time needed by the model is much shorter than that needed for the finite volume method. Thus, the nonuniform POD-Galerkin projection method exhibits high accuracy, good suitability, and fast computation. It has universal significance for accurate and fast prediction. Also, the methodology can be applied to more complex modeling in chemical engineering and technology, such as reaction and turbulence. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Optimal operation of Petlyuk distillation: Steady-state behavior
Directory of Open Access Journals (Sweden)
Ivar J. Halvorsen
2001-07-01
Full Text Available The "Petlyuk" or "dividing-wall" or "fully thermally coupled" distillation column is an interesting alternative to the conventional cascaded binary columns for separation of multi-component mixtures. However, the industrial use has been limited, and difficulties in operation have been reported as one reason. With three product compositions controlled, the system has two degrees of freedom left for on-line optimization. We show that the steady-state optimal solution surface is quite narrow, and depends strongly on disturbances and design parameters. Thus it seems difficult to achieve the potential energy savings compared to conventional approaches without a good control strategy. We discuss candidate variables which may be used as feedback variables in order to keep the column operation close to optimal in a "self-optimizing" control scheme.
Full steady state LH scenarios in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Kazarian-Vilbert, F.; Litaudon, X.; Arslanbekov, R.; Hoang, G.T.; Moreau, D.; Peysson, Y. [Association EURATOM-CEA sur la fusion, Departement de Recherches sur la Fusion Controlee, Centre d`detudes de Cadarache, F-13108 Saint-Paul-Lez-Durance (France)
1996-02-01
Lower hybrid discharges have been realised in Tore Supra using feed-back control of the primary circuit voltage (V{sub oh}) such that the loop voltage was maintained exactly zero near the plasma surface. This new scenario allows the plasma current to float and quickly reach an equilibrium value determined by the current drive efficiency and Lower Hybrid power. Recent experimental results show that, with the new {open_quote}{open_quote}constant flux{close_quote}{close_quote} scenario the coupled plasma and primary currents reach a steady state in less than 10 s which is in good agreement with theoretical expectations. A complete analysis of this scenario is presented. {copyright} {ital 1996 American Institute of Physics.}
An Adsorption Equilibria Model for Steady State Analysis
Ismail, Azhar Bin
2016-02-29
The investigation of adsorption isotherms is a prime factor in the ongoing development of adsorption cycles for a spectrum of advanced, thermally-driven engineering applications, including refrigeration, natural gas storage, and desalination processes. In this work, a novel semi-empirical mathematical model has been derived that significantly enhances the prediction of the steady state uptake in adsorbent surfaces. This model, a combination of classical Langmuir and a novel modern adsorption isotherm equation, allows for a higher degree of regression of both energetically homogenous and heterogeneous adsorbent surfaces compared to several isolated classical and modern isotherm models, and has the ability to regress isotherms for all six types under the IUPAC classification. Using a unified thermodynamic framework, a single asymmetrical energy distribution function (EDF) has also been proposed that directly relates the mathematical model to the adsorption isotherm types. This fits well with the statistical rate theory approach and offers mechanistic insights into adsorption isotherms.
Progress Toward Steady-State Operation on Tore Supra
Institute of Scientific and Technical Information of China (English)
J. Jacquinot; G. T. Hoang; the Tore Supra Team
2004-01-01
Important technological and physics issues related to steady-state operation required for next step are being examined on Tore Supra, after a major upgrade of internal components in order to increase the heat extraction capability to 25 MW for 1000 s. Here, we show first experimental results, where all the plasma facing components were actively cooled during pulses exceeding four minutes, with reactor-relevant heat load. New physics was observed in non-inductively driven plasmas, including a stationary peaked radial profile of the plasma density generated by an anomalous inward pinch; and a regime characterized by sinusoidal oscillations of central electron temperature, governed by non-linear coupling between heat transport and plasma current analogous to a predator-prey mechanism.
Analysis of steady-state ductile crack growth
DEFF Research Database (Denmark)
Niordson, Christian
1999-01-01
the finite element mesh remains fixed relative to the tip of the growing crack. Fracture is modelled using two different local crack growth criteria. One is a crack opening displacement criterion, while the other is a model in which a cohesive zone is imposed in front of the crack tip along the fracture zone......The fracture strength under quasi-static steady-state crack growth in an elastic-plastic material joined by a laser weld is analyzed. Laser welding gives high mismatch between the yield stress within the weld and the yield stress in the base material. This is due to the fast termic cycle, which....... Both models predict that in general a thinner laser weld gives higher interface strength. Furthermore, both fracture criteria show, that the preferred path of the crack is close outside the weld material; a phenomenon also observed in experiments....
Modelling of pulsed and steady-state DEMO scenarios
Giruzzi, G.; Artaud, J. F.; Baruzzo, M.; Bolzonella, T.; Fable, E.; Garzotti, L.; Ivanova-Stanik, I.; Kemp, R.; King, D. B.; Schneider, M.; Stankiewicz, R.; Stępniewski, W.; Vincenzi, P.; Ward, D.; Zagórski, R.
2015-07-01
Scenario modelling for the demonstration fusion reactor (DEMO) has been carried out using a variety of simulation codes. Two DEMO concepts have been analysed: a pulsed tokamak, characterized by rather conventional physics and technology assumptions (DEMO1) and a steady-state tokamak, with moderately advanced physics and technology assumptions (DEMO2). Sensitivity to impurity concentrations, radiation, and heat transport models has been investigated. For DEMO2, the impact of current driven non-inductively by neutral beams has been studied by full Monte Carlo simulations of the fast ion distribution. The results obtained are a part of a more extensive research and development (R&D) effort carried out in the EU in order to develop a viable option for a DEMO reactor, to be adopted after ITER for fusion energy research.
Thermodynamics and phase coexistence in nonequilibrium steady states
Dickman, Ronald
2016-09-01
I review recent work focussing on whether thermodynamics can be extended to nonequilibrium steady states (NESS), in particular, the possibility of consistent definitions of temperature T and chemical potential μ for NESS. The testing-grounds are simple lattice models with stochastic dynamics. Each model includes a drive that maintains the system far from equilibrium, provoking particle and/or energy flows; for zero drive the system relaxes to equilibrium. Analysis and numerical simulation show that for spatially uniform NESS, consistent definitions of T and μ are possible via coexistence with an appropriate reservoir, if (and in general only if) a particular kind of rate (that proposed by Sasa and Tasaki) is used for exchanges of particles and energy between systems. The program fails, however, for nonuniform systems. The functions T and μ describing isolated phases cannot be used to predict the properties of coexisting phases in a single, phase-separated system.
Steady-state negative Wigner functions of nonlinear nanomechanical oscillators
Rips, Simon; Wilson-Rae, Ignacio; Hartmann, Michael J
2011-01-01
We propose a scheme to prepare nanomechanical oscillators in non-classical steady states, characterized by a pronounced negative Wigner function. In our optomechanical approach, the mechanical oscillator couples to multiple laser driven resonances of an optical cavity. By lowering the resonant frequency of the oscillator via an inhomogeneous electrostatic field, we significantly enhance its intrinsic geometric nonlinearity per phonon. This causes the motional sidebands to split into separate spectral lines for each phonon number and transitions between individual phonon Fock states can be selectively addressed. We show that this enables preparation of the nanomechanical oscillator in a single phonon Fock state. Our scheme can for example be implemented with a carbon nanotube dispersively coupled to the evanescent field of a state of the art whispering gallery mode microcavity.
Computational complexity of nonequilibrium steady states of quantum spin chains
Marzolino, Ugo; Prosen, Tomaž
2016-03-01
We study nonequilibrium steady states (NESS) of spin chains with boundary Markovian dissipation from the computational complexity point of view. We focus on X X chains whose NESS are matrix product operators, i.e., with coefficients of a tensor operator basis described by transition amplitudes in an auxiliary space. Encoding quantum algorithms in the auxiliary space, we show that estimating expectations of operators, being local in the sense that each acts on disjoint sets of few spins covering all the system, provides the answers of problems at least as hard as, and believed by many computer scientists to be much harder than, those solved by quantum computers. We draw conclusions on the hardness of the above estimations.
Petri nets for steady state analysis of metabolic systems.
Voss, Klaus; Heiner, Monika; Koch, Ina
2011-01-01
Computer assisted analysis and simulation of biochemical pathways can improve the understanding of the structure and the dynamics of cell processes considerably. The construction and quantitative analysis of kinetic models is often impeded by the lack of reliable data. However, as the topological structure of biochemical systems can be regarded to remain constant in time, a qualitative analysis of a pathway model was shown to be quite promising as it can render a lot of useful knowledge, e. g., about its structural invariants. The topic of this paper are pathways whose substances have reached a dynamic concentration equilibrium (steady state). It is argued that appreciated tools from biochemistry and also low-level Petri nets can yield only part of the desired results, whereas executable high-level net models lead to a number of valuable additional insights by combining symbolic analysis and simulation.
Steady state analysis of metabolic pathways using Petri nets.
Voss, Klaus; Heiner, Monika; Koch, Ina
2003-01-01
Computer assisted analysis and simulation of biochemical pathways can improve the understanding of the structure and the dynamics of cell processes considerably. The construction and quantitative analysis of kinetic models is often impeded by the lack of reliable data. However, as the topological structure of biochemical systems can be regarded to remain constant in time, a qualitative analysis of a pathway model was shown to be quite promising as it can render a lot of useful knowledge, e. g., about its structural invariants. The topic of this paper are pathways whose substances have reached a dynamic concentration equilibrium (steady state). It is argued that appreciated tools from biochemistry and also low-level Petri nets can yield only part of the desired results, whereas executable high-level net models lead to a number of valuable additional insights by combining symbolic analysis and simulation.
Steady State Thermal Analyses of SCEPTOR X-57 Wingtip Propulsion
Schnulo, Sydney L.; Chin, Jeffrey C.; Smith, Andrew D.; Dubois, Arthur
2017-01-01
Electric aircraft concepts enable advanced propulsion airframe integration approaches that promise increased efficiency as well as reduced emissions and noise. NASA's fully electric Maxwell X-57, developed under the SCEPTOR program, features distributed propulsion across a high aspect ratio wing. There are 14 propulsors in all: 12 high lift motor that are only active during take off and climb, and 2 larger motors positioned on the wingtips that operate over the entire mission. The power electronics involved in the wingtip propulsion are temperature sensitive and therefore require thermal management. This work focuses on the high and low fidelity heat transfer analysis methods performed to ensure that the wingtip motor inverters do not reach their temperature limits. It also explores different geometry configurations involved in the X-57 development and any thermal concerns. All analyses presented are performed at steady state under stressful operating conditions, therefore predicting temperatures which are considered the worst-case scenario to remain conservative.
Steady-state solution methods for open quantum optical systems
Nation, P D
2015-01-01
We discuss the numerical solution methods available when solving for the steady-state density matrix of a time-independent open quantum optical system, where the system operators are expressed in a suitable basis representation as sparse matrices. In particular, we focus on the difficulties posed by the non-Hermitian structure of the Lindblad super operator, and the numerical techniques designed to mitigate these pitfalls. In addition, we introduce a doubly iterative inverse-power method that can give reduced memory and runtime requirements in situations where other iterative methods are limited due to poor bandwidth and profile reduction. The relevant methods are demonstrated on several prototypical quantum optical systems where it is found that iterative methods based on iLU factorization using reverse Cuthill-Mckee ordering tend to outperform other solution techniques in terms of both memory consumption and runtime as the size of the underlying Hilbert space increases. For eigenvalue solving, Krylov iterat...
Steady-State Axisymmetric MHD Solutions with Various Boundary Conditions
Wang, Lile
2014-01-01
Axisymmetric magnetohydrodynamics (MHD) can be invoked for describing astrophysical magnetized flows and formulated to model stellar magnetospheres including main sequence stars (e.g. the Sun), compact stellar objects [e.g. magnetic white dwarfs (MWDs), radio pulsars, anomalous X-ray pulsars (AXPs), magnetars, isolated neutron stars etc.], and planets as a major step forward towards a full three-dimensional model construction. Using powerful and reliable numerical solvers based on two distinct finite-difference method (FDM) and finite-element method (FEM) schemes of algorithm, we examine axisymmetric steady-state or stationary MHD models in Throumoulopoulos & Tasso (2001), finding that their separable semi-analytic nonlinear solutions are actually not unique given their specific selection of several free functionals and chosen boundary conditions. The multiplicity of nonlinear steady MHD solutions gives rise to differences in the total energies contained in the magnetic fields and flow velocity fields as ...
Dissipative production of a maximally entangled steady state
Lin, Y; Reiter, F; Tan, T R; Bowler, R; S\\orensen, A S; Leibfried, D; Wineland, D J
2013-01-01
Entangled states are a key resource in fundamental quantum physics, quantum cryp-tography, and quantum computation [1].To date, controlled unitary interactions applied to a quantum system, so-called "quantum gates", have been the most widely used method to deterministically create entanglement [2]. These processes require high-fidelity state preparation as well as minimizing the decoherence that inevitably arises from coupling between the system and the environment and imperfect control of the system parameters. Here, on the contrary, we combine unitary processes with engineered dissipation to deterministically produce and stabilize an approximate Bell state of two trapped-ion qubits independent of their initial state. While previous works along this line involved the application of sequences of multiple time-dependent gates [3] or generated entanglement of atomic ensembles dissipatively but relied on a measurement record for steady-state entanglement [4], we implement the process in a continuous time-indepen...
Steady-state, cavity-less, multimode superradiance
Greenberg, Joel A
2012-01-01
The study of collective light-matter interactions, where the dynamics of an individual scatterer depend on the state of the entire multi-scatterer system, has recently received much attention in the areas of fundamental research and photonic technologies. Cold atomic vapors represent an exciting system for studying such effects because light-based manipulation of internal and center-of-mass atomic states lead to reduced instability thresholds and new phonomena. Previous investigations required single-mode cavities to realize strong light mediated atom-atom interactions, though, which limits the observable phenomena. Here we demonstrate steady-state, mirrorless superradiance in a cold vapor pumped by weak optical fields. Beyond a critical pumping strength, the vapor spontaneously transforms into a spatially self-organized state: a density grating forms. Scattering of the pump beams off this grating generates new optical fields that act back on the vapor to enhance the atomic organization. This system has appli...
Extending the definition of entropy to nonequilibrium steady states.
Ruelle, David P
2003-03-18
We study the nonequilibrium statistical mechanics of a finite classical system subjected to nongradient forces xi and maintained at fixed kinetic energy (Hoover-Evans isokinetic thermostat). We assume that the microscopic dynamics is sufficiently chaotic (Gallavotti-Cohen chaotic hypothesis) and that there is a natural nonequilibrium steady-state rho(xi). When xi is replaced by xi + deltaxi, one can compute the change deltarho of rho(xi) (linear response) and define an entropy change deltaS based on energy considerations. When xi is varied around a loop, the total change of S need not vanish: Outside of equilibrium the entropy has curvature. However, at equilibrium (i.e., if xi is a gradient) we show that the curvature is zero, and that the entropy S(xi + deltaxi) near equilibrium is well defined to second order in deltaxi.
Avoiding Rebound through a Steady-State Economy
DEFF Research Database (Denmark)
Nørgaard, Jørgen
2008-01-01
is considered to be limited primarily by productive capacity with little concern for ecological costs and limits. In such a development aiming at unlimited growth it would from a long term environmental perspective be close to irrelevant to reach for more efficient use of energy at the end-users, since it would...... only buy some time. From this perspective, the environmental problem with the rebound effect is not the higher energy efficiency, which pushes towards lower flows of resources through the economy, but rather the conventional economy which rebounds the savings, because of its quest for higher flows....... In this chapter, I shall take the rebound debate further by discussing the possible role of energy efficiency in a sustainable economy that is based on the notion of ‘sufficiency’. The assumption is that globally we need to achieve a ‘steady-state economy’. Considering the urgent need for better material...
Hughes, W.B.
1995-01-01
J-Field, located in the Edgewood Area of Aberdeen Proving Ground, Md, has been used since World War II to test and dispose of explosives, chemical warfare agents, and industrial chemicals resulting in ground-water, surface-water, and soil contami- nation. The U.S. Geological Survey finite-difference model was used to better understand ground-water flow at the site and to simulate the effects of remedial actions. A surficial aquifer and a confined aquifer were simulated with the model. A confining unit separates these units and is represented by leakance between the layers. The area modeled is 3.65 mi2; the model was constructed with a variably spaced 40 X 38 grid. The horizontal and lower boundaries of the model are all no-flow boundaries. Steady-state conditions were used. Ground water at the areas under investigation flows from disposal pit areas toward discharge areas in adjacent estuaries or wetlands. Simulations indicate that capping disposal areas with an impermeable cover effectively slows advective ground water flow by 0.7 to 0.5 times. Barriers to lateral ground-water flow were simulated and effectively prevented the movement of ground water toward discharge areas. Extraction wells were simulated as a way to contain ground-water contamination and to extract ground water for treatment. Two wells pumping 5 gallons per minute each at the toxic-materials disposal area and a single well pumping 2.5 gallons per minute at the riot-control-agent disposal area effectively contained contamination at these sites. A combi- nation of barriers to horizontal flow east and south of the toxic-materials disposal area, and a single extraction well pumping at 5 gallons per minute can extract contaminated ground water and prevent pumpage of marsh water.
Molecular-dynamics simulation of two-dimensional thermophoresis
Paredes; Idler; Hasmy; Castells; Botet
2000-11-01
A numerical technique is presented for the thermal force exerted on a solid particle by a gaseous medium between two flat plates at different temperatures, in the free molecular or transition flow. This is a two-dimensional molecular-dynamics simulation of hard disks in a inhomogeneous thermal environment. All steady-state features exhibited by the compressible hard-disk gas are shown to be consistent with the expected behaviors. Moreover the thermal force experienced by a large solid disk is investigated, and compared to the analytical case of cylinders moving perpendicularly to the constant temperature gradient for an infinite Knudsen number and in an infinite medium. We show precise examples of how this technique can be used simply to investigate more difficult practical problems, in particluar the influence of nonlinear gradients for large applied differences of temperature, of proximity of the walls, and of smaller Knudsen numbers.
Laguna Verde BWRs operational experience: steady-state fuel performance
Energy Technology Data Exchange (ETDEWEB)
Cuevas V, G. F.; Bravo S, J. M. [Global Nuclear Fuel - Americas, 3901 Castle Hayne Road, Wilmington, 28401 North Carolina (United States); Casillas, J. L., E-mail: gabriel.cuevas-vivas@gnf.co [General Electric Hitachi Nuclear Energy, 1989 Little Orchard St. Romm 239, San Jose, 95125 California (United States)
2010-10-15
The two BWR at Laguna Verde nuclear power station are finishing 21 and 15 years of continuous successful operation as of 2010. During Unit 1 and 2 commercial operations only Ge/GNF fuel designs have been employed; fuel lattice designs 8 x 8 and 10 x 10 were used at the reactor, with an original licensed thermal power (OLTP: 1931 MWt) and the reactor's first power up-rates of 5%. GNF fuel will be also used for the second EPU to reach 120% of OLTP in the near future. Thermal and gamma traversing in-core probes (Tip) are used for power monitoring purposes along with the Ge (now GNF-A) core monitoring system, 3-dimensional Monicore{sup TM}. GNF-A has also participated by preparing the core management plan that is regularly fine-tuned in collaboration with Comision Federal de Electricidad (CFE owner of the Laguna Verde reactors). For determination of thermal margins and eigenvalue prediction, GNF-A employs the NRC-licensed steady-state core simulator PANAC11. Tip comparisons are routinely used to adapt power distributions for a better thermal margin calculation. Over the years, several challenges have appeared in the near and long term fuel management planning such as increasing cycle length, optimization of the thermal margins, rated power increase, etc. Each challenge has been successfully overcome via operational strategy, code improvements and better fuel designs. This paper summarizes Laguna Verde Unit 1 and 2 steady-state performance from initial commercial operation, with a discussion of the nuclear and thermal-hydraulic design features, as well as of the operational strategies that set and interesting benchmark for future fuel applications, code development and operation of the BWRs. (Author)
A mathematical model of pan evaporation under steady state conditions
Lim, Wee Ho; Roderick, Michael L.; Farquhar, Graham D.
2016-09-01
In the context of changing climate, global pan evaporation records have shown a spatially-averaged trend of ∼ -2 to ∼ -3 mm a-2 over the past 30-50 years. This global phenomenon has motivated the development of the "PenPan" model (Rotstayn et al., 2006). However, the original PenPan model has yet to receive an independent experimental evaluation. Hence, we constructed an instrumented US Class A pan at Canberra Airport (Australia) and monitored it over a three-year period (2007-2010) to uncover the physics of pan evaporation under non-steady state conditions. The experimental investigations of pan evaporation enabled theoretical formulation and parameterisation of the aerodynamic function considering the wind, properties of air and (with or without) the bird guard effect. The energy balance investigation allowed for detailed formulation of the short- and long-wave radiation associated with the albedos and the emissivities of the pan water surface and the pan wall. Here, we synthesise and generalise those earlier works to develop a new model called the "PenPan-V2" model for application under steady state conditions (i.e., uses a monthly time step). Two versions (PenPan-V2C and PenPan-V2S) are tested using pan evaporation data available across the Australian continent. Both versions outperformed the original PenPan model with better representation of both the evaporation rate and the underlying physics of a US Class A pan. The results show the improved solar geometry related calculations (e.g., albedo, area) for the pan system led to a clear improvement in representing the seasonal cycle of pan evaporation. For general applications, the PenPan-V2S is simpler and suited for applications including an evaluation of long-term trends in pan evaporation.
Interpolation of steady-state concentration data by inverse modeling.
Schwede, Ronnie L; Cirpka, Olaf A
2010-01-01
In most groundwater applications, measurements of concentration are limited in number and sparsely distributed within the domain of interest. Therefore, interpolation techniques are needed to obtain most likely values of concentration at locations where no measurements are available. For further processing, for example, in environmental risk analysis, interpolated values should be given with uncertainty bounds, so that a geostatistical framework is preferable. Linear interpolation of steady-state concentration measurements is problematic because the dependence of concentration on the primary uncertain material property, the hydraulic conductivity field, is highly nonlinear, suggesting that the statistical interrelationship between concentration values at different points is also nonlinear. We suggest interpolating steady-state concentration measurements by conditioning an ensemble of the underlying log-conductivity field on the available hydrological data in a conditional Monte Carlo approach. Flow and transport simulations for each conditional conductivity field must meet the measurements within their given uncertainty. The ensemble of transport simulations based on the conditional log-conductivity fields yields conditional statistical distributions of concentration at points between observation points. This method implicitly meets physical bounds of concentration values and non-Gaussianity of their statistical distributions and obeys the nonlinearity of the underlying processes. We validate our method by artificial test cases and compare the results to kriging estimates assuming different conditional statistical distributions of concentration. Assuming a beta distribution in kriging leads to estimates of concentration with zero probability of concentrations below zero or above the maximal possible value; however, the concentrations are not forced to meet the advection-dispersion equation.
Steady-state spectroscopy of new biological probes
Abou-Zied, Osama K.
2007-02-01
The steady state absorption and fluorescence spectroscopy of 2-(2'-hydroxyphenyl)benzoxazole (HBO) and (2,2'-bipyridine)-3,3'-diol (BP(OH) II) were studied here free in solution and in human serum albumin (HSA) in order to test their applicability as new biological probes. HBO and BP(OH) II are known to undergo intramolecular proton transfers in the excited state. Their absorption and fluorescence spectra are sensitive to environmental change from hydrophilic to hydrophobic, thus allowing the opportunity to use them as environment-sensitive probes. The effect of water on the steady state spectra of the two molecules also shows unique features which may position them as water sensors in biological systems. For HBO in buffer, fluorescence is only due to the syn-keto tautomer, whereas in HSA the fluorescence is due to four species in equilibrium in the excited state (the syn-keto tautomer, the anti-enol tautomer, the solvated syn-enol tautomer, and the anion species of HBO). Analysis of the fluorescence spectra of HBO in HSA indicates that HBO is exposed to less water in the HBO:HSA complex. For the BP(OH) II molecule, unique absorption due to water was observed in the spectral region of 400-450 nm. This absorption decreases in the presence of HSA due to less accessibility to water as a result of binding to HSA. Fluorescence of BP(OH) II is due solely to the di-keto tautomer after double proton transfer in the excited state. The fluorescence peak of BP(OH) II shows a red-shift upon HSA recognition which is attributed to the hydrophobic environment inside the binding site of HSA. We discuss also the effect of probe-inclusion inside well-defined hydrophobic cavities of cyclodextrins.
Thermal use of ground water; Thermische Grundwassernutzung
Energy Technology Data Exchange (ETDEWEB)
Cathomen, N.; Stauffer, F.; Kinzelbach, W.; Osterkorn, F.
2002-07-01
This article discusses possible regional changes in ground water temperature caused by thermal use of the ground water in heat pump installations and by the infiltration of cooling water. The article reports on investigations made into the influence of ground water usage in the community of Altach in the Rhine Valley in Austria. The procedures used and the geology of the area investigated are described and the results of the measurements that were made are presented. The mathematical modelling of regional long-term heat transport is presented. The results of simulations are compared with long-term temperature measurements. The use of the results as a basis for the assessment of permissible thermal use of ground water is discussed.
GROUND WATER CONTAMINATION POTENTIAL FROM STORMWATER INFILTRATION
Prior to urbanization, ground water recharge resulted from infiltration of precipitation through pervious surfaces, including grasslands and woods. This infiltration water was relatively uncontaminated. With urbanization, the permeable soil surface area through which recharge by...
Section 10: Ground Water - Waste Characteristics & Targets
HRS Training. The waste characteristics factor category in the ground water pathway is made up of two components: the toxicity/mobility of the most hazardous substance associated with the site and the hazardous waste quantity at the site.
Section 9: Ground Water - Likelihood of Release
HRS training. the ground water pathway likelihood of release factor category reflects the likelihood that there has been, or will be, a release of hazardous substances in any of the aquifers underlying the site.
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
Two-dimensional liquid chromatography has received increasing interest due to the rise in demand for analysis of complex chemical mixtures. Separation of complex mixtures is hard to achieve as a simple consequence of the sheer number of analytes, as these samples might contain hundreds or even...... dimensions. As a consequence of the conclusions made within this thesis, the research group has, for the time being, decided against further development of online LC×LC systems, since it was not deemed ideal for the intended application, the analysis of the polar fraction of oil. Trap-and...
Chemostat-cultivated Escherichia coli at high dilution rate: multiple steady states and drift.
Majewski, R A; Domach, M M
1990-06-20
The representation of metabolic network reaction kinetics in a scaled, polynomial form can allow for the prediction of multiple steady states. The polynomial formalism is used to study chemostat-cultured Escherichia coli which has been observed to exhibit two multiple steady states under ammonium ion-limited growth conditions: a high cell density-low ammonium ion concentration steady state and a low cell density-high ammonium ion concentration steady state. Additionally, the low-cell-density steady state has been observed to drift to the high-cell-density steady state. Inspection of the steady-state rate expressions for the ammonium ion transport/assimilation network (in polynomial form) suggests that at low ammonium ion concentrations, two steady states are possible. One corresponds to heavy use of the glutamine synthetase-glutamate synthase (GLNS-GS) branch and the second to heavy use of the glutamate dehydrogenase (GDH) branch. Realization of the predicted intracellular steady states is also found to be dependent on the parameters of the transport process. Moreover, the two steady states differ in where their energy intensity lies. To explain the drift, GLNS, which is inducible under low ammonium ion concentrations, is suggested to be a "memory element." A chemostat-based model is developed to illustrate that perturbations in dilution rate can lead to drift between the two steady states provided that the disturbance in dilution rate is sufficiently large and/or long in duration.
Estimating ground water discharge by hydrograph separation.
Hannula, Steven R; Esposito, Kenneth J; Chermak, John A; Runnells, Donald D; Keith, David C; Hall, Larry E
2003-01-01
Iron Mountain is located in the West Shasta Mining District in California. An investigation of the generation of acid rock drainage and metals loading to Boulder Creek at Iron Mountain was conducted. As part of that investigation, a hydrograph separation technique was used to determine the contribution of ground water to total flow in Boulder Creek. During high-flow storm events in the winter months, peak flow in Boulder Creek can exceed 22.7 m3/sec, and comprises surface runoff, interflow, and ground water discharge. A hydrograph separation technique was used to estimate ground water discharge into Boulder Creek during high-flow conditions. Total ground water discharge to the creek approaches 0.31 m3/sec during the high-flow season. The hydrograph separation technique combined with an extensive field data set provided reasonable estimates of ground water discharge. These estimates are useful for other investigations, such as determining a corresponding metals load from the metal-rich ground water found at Iron Mountain and thus contributing to remedial alternatives.
Simulation of the ground-water-flow system in the Kalamazoo County area, Michigan
Luukkonen, Carol L.; Blumer, Stephen P.; Weaver, T.L.; Jean, Julie
2004-01-01
A ground-water-flow model was developed to investigate the ground-water resources of Kalamazoo County. Ground water is widely used as a source of water for drinking and industry in Kalamazoo County and the surrounding area. Additionally, lakes and streams are valued for their recreational and aesthetic uses. Stresses on the ground-water system, both natural and human-induced, have raised concerns about the long-term availability of ground water for people to use and for replenishment of lakes and streams. Potential changes in these stresses, including withdrawals and recharge, were simulated using a ground-water-flow model. Simulations included steady-state conditions (in which stresses remained constant and changes in storage were not included) and transient conditions (in which stresses changed in seasonal and monthly time scales and storage within the system was included). Steady-state simulations were used to investigate the long-term effects on water levels and streamflow of a reduction in recharge or an increase in pumping to projected 2010 withdrawal rates, withdrawal and application of water for irrigation, and a reduction in recharge in urban areas caused by impervious surfaces. Transient simulations were used to investigate changes in withdrawals to match seasonal and monthly patterns under various recharge conditions, and the potential effects of the use of water for irrigation over the summer months. With a reduction in recharge, simulated water levels declined over most of the model area in Kalamazoo County; with an increase in pumping, water levels declined primarily near pumping centers. Because withdrawals by wells intercept water that would have discharged possibly to a stream or lake, model simulations indicated that streamflow was reduced with increased withdrawals. With withdrawal and consumption of water for irrigation, simulated water levels declined. Assuming a reduction in recharge due to urbanization, water levels declined and flow to
Steady state, continuity, and the curious behavior of steep channels in layered rocks
Covington, M. D.; Perne, M.; Thaler, E.; Myre, J. M.
2016-12-01
Considerations of landscape steady state have substantially informed our understanding of the relationships between landscapes, tectonics, climate, and lithology. Topographic steady state, where topography is fixed in time, is a particularly important tool in the interpretation of landscape features, such as bedrock channel profiles, within a context of uplift patterns and rock strength. However, topographic steady state cannot strictly be attained in a landscape with layered rocks with non-vertical contacts. We show that an assumption of channel continuity, where channel retreat rates in the direction parallel to a contact are equal above and below the contact, provides a more general description of steady state landscapes in layered rocks, and that topographic steady state is a special case of the steady state derived from continuity. We demonstrate that modeled landscapes approach continuity steady state using 1D simulations and full landscape evolution models. Contrary to common conceptions, continuity predicts that channels will be steeper in weaker rocks in the case of subhorizontal rock layers when the stream power erosion exponent n<1. For subhorizontal layered rocks with different erodibilities, continuity also predicts larger slope contrasts than would be predicted by topographic steady state. Continuity steady state is a type of flux steady state, where uplift is balanced on average by erosion. The differences between topographic steady state and continuity steady state are most pronuced for steep channels in subhorizontal layered rocks. Consequently, cratonic and plateau settings are most likely to produce the effects predicted by continuity steady state. These settings remain relatively underexplored within the bedrock channel literature. Though examples illustrated here utilze the stream power erosion law, continuity steady state provides a general mathematical tool that can be used to explore the development of landscapes in layered rocks using any
Two-dimensional capillary origami
Energy Technology Data Exchange (ETDEWEB)
Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu
2016-01-08
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.
Effects of spatial diffusion on nonequilibrium steady states in a model for prebiotic evolution
Intoy, B. F.; Wynveen, A.; Halley, J. W.
2016-10-01
Effects of spatial diffusion in a Kauffman-like model for prebiotic evolution previously studied in a "well-mixed" limit are reported. The previous model was parametrized by a parameter p defined as the probability that a possible reaction in a network of reactions characterizing the artificial chemistry actually appears in the chemical network. In the model reported here, we numerically study a grid of such well-mixed reactors on a two-dimensional spatial lattice in which the model chemical constituents can hop between neighboring reactors at a rate controlled by a second parameter η . We report the frequency of appearance of three distinct types of nonequilibrium steady states, characterized as "diffusively alive locally dead" (DALD), "diffusively dead locally alive" (DDLA) and "diffusively alive locally alive" (DALA). The types are defined according to whether they are chemically equilibrated at each site, diffusively equilibrated between sites, or neither, respectively. With our parametrization of the definitions of these nonequilibrium states, many of the DALA states are growing rapidly in population due to the explosive population growth of a few sites, while their entropy remains well below its equilibrium value. Sharp temporal transitions occur as exploding sites appear. DALD states occur less commonly than the other types and also usually harbor a few explosively growing sites but transitions are less sharp than in DALA systems.
Influence of Carrier Transport on Diffraction Efficiency of Steady-State Photocarrier Grating
Sun, Q. M.; Wang, Y. F.; Gao, C. M.; Cui, H.
2015-06-01
A two-dimensional theoretical model of a diffractive steady-state photocarrier grating (SSPCG) has been developed. The carrier diffusion equation with a spatially periodic excitation source was solved, and an analytical expression of the carrier density distribution was obtained. Based on the band-filling theory and the Kramers-Kronig relation, the carrier-induced refractive index change of SSPCG was estimated, and the refractive index profile was determined. The diffraction efficiency of the SSPCG was calculated by multilevel rigorous coupled-wave analysis. Simulations were carried out to investigate the influence of the carrier transport properties on the diffraction efficiency of the SSPCG. The results show that a semiconductor material with a longer lifetime and a smaller diffusivity will have a higher diffraction efficiency. The spatial amplitude of the carrier density and the grating strength of the SSPCG are closely related to the grating period. For an InP-based SSPCG, the diffraction efficiency of the transmitted wave reaches its maximum value (25 %) when the grating provides a phase shift. The theoretical analysis and conclusions are helpful for material selection and experimental parameter determination of a diffractive SSPCG.
A two-dimensional mathematical model of percutaneous drug absorption
Directory of Open Access Journals (Sweden)
Kubota K
2004-06-01
Full Text Available Abstract Background When a drug is applied on the skin surface, the concentration of the drug accumulated in the skin and the amount of the drug eliminated into the blood vessel depend on the value of a parameter, r. The values of r depend on the amount of diffusion and the normalized skin-capillary clearence. It is defined as the ratio of the steady-state drug concentration at the skin-capillary boundary to that at the skin-surface in one-dimensional models. The present paper studies the effect of the parameter values, when the region of contact of the skin with the drug, is a line segment on the skin surface. Methods Though a simple one-dimensional model is often useful to describe percutaneous drug absorption, it may be better represented by multi-dimensional models. A two-dimensional mathematical model is developed for percutaneous absorption of a drug, which may be used when the diffusion of the drug in the direction parallel to the skin surface must be examined, as well as in the direction into the skin, examined in one-dimensional models. This model consists of a linear second-order parabolic equation with appropriate initial conditions and boundary conditions. These boundary conditions are of Dirichlet type, Neumann type or Robin type. A finite-difference method which maintains second-order accuracy in space along the boundary, is developed to solve the parabolic equation. Extrapolation in time is applied to improve the accuracy in time. Solution of the parabolic equation gives the concentration of the drug in the skin at a given time. Results Simulation of the numerical methods described is carried out with various values of the parameter r. The illustrations are given in the form of figures. Conclusion Based on the values of r, conclusions are drawn about (1 the flow rate of the drug, (2 the flux and the cumulative amount of drug eliminated into the receptor cell, (3 the steady-state value of the flux, (4 the time to reach the steady-state
Mantle Sulfur Cycle: A Case for Non-Steady State ?
Cartigny, Pierre; Labidi, Jabrane
2016-04-01
Data published over the last 5 years show that the early inference that mantle is isotopically homogeneous is no more valid. Instead, new generation data on lavas range over a significant 34S/32S variability of up to 5‰ with δ 34S values often correlated to Sr- and Nd-isotope compositions. This new set of data also reveals the Earth's mantle to have a sub-chondritic 34S/32S ratio, by about ˜ 1‰. We will present at the conference our published and unpublished data on samples characterizing the different mantle components (i.e. EM1, EM2, HIMU and LOMU). All illustrate 34S-enrichments compared to MORB with Δ 33S and Δ 36S values indistinguishable from CDT or chondrites at the 0.03‰ level. These data are consistent with the recycling of subducted components carrying sulfur with Δ 33S and Δ 36S-values close to zero. Archean rocks commonly display Δ 33S and Δ 36S values deviating from zero by 1 to 10 ‰. The lack of variations for Δ 33S and Δ 36S values in present day lava argue against the sampling of any subducted protolith of Archean age in their mantle source. Instead, our data are consistent with the occurrence of Proterozoic subducted sulfur in the source of the EM1, EM2, LOMU and HIMU endmember at the St-Helena island. This is in agreement with the age of those components early derived through the use of the Pb isotope systematic. Currently, the negative δ 34S-values of the depleted mantle seem to be associated with mostly positive values of enriched components. This would be inconsistent with the concept a steady state of sulfur. Assuming that the overall observations of recycled sulfur are not biased, the origin of such a non-steady state remains unclear. It could be related to the relatively compatible behavior of sulfur during partial melting, as the residue of present-day melting can be shown to always contain significant amounts of sulfide (50{%} of what is observed in a fertile source). This typical behavior likely prevents an efficient
The Budyko functions under non-steady-state conditions
Moussa, Roger; Lhomme, Jean-Paul
2016-12-01
The Budyko functions relate the evaporation ratio E / P (E is evaporation and P precipitation) to the aridity index Φ = Ep / P (Ep is potential evaporation) and are valid on long timescales under steady-state conditions. A new physically based formulation (noted as Moussa-Lhomme, ML) is proposed to extend the Budyko framework under non-steady-state conditions taking into account the change in terrestrial water storage ΔS. The variation in storage amount ΔS is taken as negative when withdrawn from the area at stake and used for evaporation and positive otherwise, when removed from the precipitation and stored in the area. The ML formulation introduces a dimensionless parameter HE = -ΔS / Ep and can be applied with any Budyko function. It represents a generic framework, easy to use at various time steps (year, season or month), with the only data required being Ep, P and ΔS. For the particular case where the Fu-Zhang equation is used, the ML formulation with ΔS ≤ 0 is similar to the analytical solution of Greve et al. (2016) in the standard Budyko space (Ep / P, E / P), a simple relationship existing between their respective parameters. The ML formulation is extended to the space [Ep / (P - ΔS), E / (P - ΔS)] and compared to the formulations of Chen et al. (2013) and Du et al. (2016). The ML (or Greve et al., 2016) feasible domain has a similar upper limit to that of Chen et al. (2013) and Du et al. (2016), but its lower boundary is different. Moreover, the domain of variation of Ep / (P - ΔS) differs: for ΔS ≤ 0, it is bounded by an upper limit 1 / HE in the ML formulation, while it is only bounded by a lower limit in Chen et al.'s (2013) and Du et al.'s (2016) formulations. The ML formulation can also be conducted using the dimensionless parameter HP = -ΔS / P instead of HE, which yields another form of the equations.
Two-dimensional quantum repeaters
Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.
2016-11-01
The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.
Two-dimensional capillary origami
Brubaker, N. D.; Lega, J.
2016-01-01
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid.
Two-dimensional cubic convolution.
Reichenbach, Stephen E; Geng, Frank
2003-01-01
The paper develops two-dimensional (2D), nonseparable, piecewise cubic convolution (PCC) for image interpolation. Traditionally, PCC has been implemented based on a one-dimensional (1D) derivation with a separable generalization to two dimensions. However, typical scenes and imaging systems are not separable, so the traditional approach is suboptimal. We develop a closed-form derivation for a two-parameter, 2D PCC kernel with support [-2,2] x [-2,2] that is constrained for continuity, smoothness, symmetry, and flat-field response. Our analyses, using several image models, including Markov random fields, demonstrate that the 2D PCC yields small improvements in interpolation fidelity over the traditional, separable approach. The constraints on the derivation can be relaxed to provide greater flexibility and performance.
Yongky, Andrew; Lee, Jongchan; Le, Tung; Mulukutla, Bhanu Chandra; Daoutidis, Prodromos; Hu, Wei-Shou
2015-07-01
Continuous culture for the production of biopharmaceutical proteins offers the possibility of steady state operations and thus more consistent product quality and increased productivity. Under some conditions, multiplicity of steady states has been observed in continuous cultures of mammalian cells, wherein with the same dilution rate and feed nutrient composition, steady states with very different cell and product concentrations may be reached. At those different steady states, cells may exhibit a high glycolysis flux with high lactate production and low cell concentration, or a low glycolysis flux with low lactate and high cell concentration. These different steady states, with different cell concentration, also have different productivity. Developing a mechanistic understanding of the occurrence of steady state multiplicity and devising a strategy to steer the culture toward the desired steady state is critical. We establish a multi-scale kinetic model that integrates a mechanistic intracellular metabolic model and cell growth model in a continuous bioreactor. We show that steady state multiplicity exists in a range of dilution rate in continuous culture as a result of the bistable behavior in glycolysis. The insights from the model were used to devise strategies to guide the culture to the desired steady state in the multiple steady state region. The model provides a guideline principle in the design of continuous culture processes of mammalian cells.
Senior, Lisa A.; Goode, Daniel J.
1999-01-01
areas in three drainages, the Wissahickon, Towamencin, and Neshaminy Creeks.Ground-water flow was simulated for different pumping patterns representing past and current conditions. The three-dimensional numerical flow model (MODFLOW) was automatically calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. Model calibration indicates that estimated recharge is 8.2 inches (208 millimeters) and the regional anisotropy ratio for the sedimentary-rock aquifer is about 11 to 1, with permeability greatest along strike. The regional anisotropy is caused by up- and down-dip termination of high-permeability bed-oriented features, which were not explicitly simulated in the regional-scale model. The calibrated flow model was used to compare flow directions and capture zones in Lansdale for conditions corresponding to relatively high pumping rates in 1994 and to lower pumping rates in 1997. Comparison of the 1994 and 1997 simulations indicates that wells pumped at the lower 1997 rates captured less ground water from known sites of contamination than wells pumped at the 1994 rates. Ground-water flow rates away from Lansdale increased as pumpage decreased in 1997.A preliminary evaluation of the relation between ground-water chemistry and conditions favorable for the degradation of chlorinated solvents was based on measurements of dissolved-oxygen concentration and other chemical constituents in water samples from 92 wells. About 18 percent of the samples contained less than or equal to 5 milligrams per liter dissolved oxygen, a concentration that indicates reducing conditions favorable for degradation of chlorinated solvents.
Quasi-steady state aerodynamics of the cheetah tail
Directory of Open Access Journals (Sweden)
Amir Patel
2016-08-01
Full Text Available During high-speed pursuit of prey, the cheetah (Acinonyx jubatus has been observed to swing its tail while manoeuvring (e.g. turning or braking but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.
Quasi-steady state aerodynamics of the cheetah tail
Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily
2016-01-01
ABSTRACT During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. PMID:27412267
The Path of Carbon in Photosynthesis XX. The Steady State
Calvin, M.; Massini, Peter
1952-09-01
The separation of the phenomenon of photosynthesis in green plants into a photochemical reaction and into the light-dependent reduction of carbon dioxide is discussed, The reduction of carbon dioxide and the fate of the assimilated carbon were investigated with the help of the tracer technique (exposure of the planks to the radioactive C{sup 14}O{sub 2}) and of paper chromatography. A reaction cycle is proposed in which phosphoglyceric acid is the first isolable assimilations product. Analyses of the algal extracts which had assimilated radioactive carbon dioxide in a stationary condition ('steady-state' photosynthesis) for a long time provided further information concerning the proposed cycle and permitted the approximate estimation, for a number of compounds of what fraction of each compound was taking part in the cycle. The earlier supposition that light influences the respiration cycle was confirmed. The possibility of the assistance of {alpha}-lipoic acid, or of a related substance, in this influence and in the photosynthesis cycle, is discussed.
Quasi-steady state aerodynamics of the cheetah tail.
Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily
2016-08-15
During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.
Stable Gene Regulatory Network Modeling From Steady-State Data
Directory of Open Access Journals (Sweden)
Joy Edward Larvie
2016-04-01
Full Text Available Gene regulatory networks represent an abstract mapping of gene regulations in living cells. They aim to capture dependencies among molecular entities such as transcription factors, proteins and metabolites. In most applications, the regulatory network structure is unknown, and has to be reverse engineered from experimental data consisting of expression levels of the genes usually measured as messenger RNA concentrations in microarray experiments. Steady-state gene expression data are obtained from measurements of the variations in expression activity following the application of small perturbations to equilibrium states in genetic perturbation experiments. In this paper, the least absolute shrinkage and selection operator-vector autoregressive (LASSO-VAR originally proposed for the analysis of economic time series data is adapted to include a stability constraint for the recovery of a sparse and stable regulatory network that describes data obtained from noisy perturbation experiments. The approach is applied to real experimental data obtained for the SOS pathway in Escherichia coli and the cell cycle pathway for yeast Saccharomyces cerevisiae. Significant features of this method are the ability to recover networks without inputting prior knowledge of the network topology, and the ability to be efficiently applied to large scale networks due to the convex nature of the method.
Regulation of steady-state neutrophil homeostasis by macrophages
Gordy, Claire; Pua, Heather; Sempowski, Gregory D.
2011-01-01
The timely clearance of apoptotic neutrophils from inflammation sites is an important function of macrophages; however, the role of macrophages in maintaining neutrophil homeostasis under steady-state conditions is less well understood. By conditionally deleting the antiapoptotic gene cellular FLICE-like inhibitory protein (C-FLIP) in myeloid cells, we have generated a novel mouse model deficient in marginal zone and bone marrow stromal macrophages. These mice develop severe neutrophilia, splenomegaly, extramedullary hematopoiesis, decreased body weight, and increased production of granulocyte colony-stimulating factor (G-CSF) and IL-1β, but not IL-17. c-FLIPf/f LysM-Cre mice exhibit delayed clearance of circulating neutrophils, suggesting that failure of macrophages to efficiently clear apoptotic neutrophils causes production of cytokines that drive excess granulopoiesis. Further, blocking G-CSF but not IL-1R signaling in vivo rescues this neutrophilia, suggesting that a G-CSF–dependent, IL-1β–independent pathway plays a role in promoting neutrophil production in mice with defective clearance of apoptotic cells. PMID:20980680
Attentional modulation of auditory steady-state responses.
Directory of Open Access Journals (Sweden)
Yatin Mahajan
Full Text Available Auditory selective attention enables task-relevant auditory events to be enhanced and irrelevant ones suppressed. In the present study we used a frequency tagging paradigm to investigate the effects of attention on auditory steady state responses (ASSR. The ASSR was elicited by simultaneously presenting two different streams of white noise, amplitude modulated at either 16 and 23.5 Hz or 32.5 and 40 Hz. The two different frequencies were presented to each ear and participants were instructed to selectively attend to one ear or the other (confirmed by behavioral evidence. The results revealed that modulation of ASSR by selective attention depended on the modulation frequencies used and whether the activation was contralateral or ipsilateral. Attention enhanced the ASSR for contralateral activation from either ear for 16 Hz and suppressed the ASSR for ipsilateral activation for 16 Hz and 23.5 Hz. For modulation frequencies of 32.5 or 40 Hz attention did not affect the ASSR. We propose that the pattern of enhancement and inhibition may be due to binaural suppressive effects on ipsilateral stimulation and the dominance of contralateral hemisphere during dichotic listening. In addition to the influence of cortical processing asymmetries, these results may also reflect a bias towards inhibitory ipsilateral and excitatory contralateral activation present at the level of inferior colliculus. That the effect of attention was clearest for the lower modulation frequencies suggests that such effects are likely mediated by cortical brain structures or by those in close proximity to cortex.
Nonequilibrium steady states of ideal bosonic and fermionic quantum gases
Vorberg, Daniel; Wustmann, Waltraut; Schomerus, Henning; Ketzmerick, Roland; Eckardt, André
2015-12-01
We investigate nonequilibrium steady states of driven-dissipative ideal quantum gases of both bosons and fermions. We focus on systems of sharp particle number that are driven out of equilibrium either by the coupling to several heat baths of different temperature or by time-periodic driving in combination with the coupling to a heat bath. Within the framework of (Floquet-)Born-Markov theory, several analytical and numerical methods are described in detail. This includes a mean-field theory in terms of occupation numbers, an augmented mean-field theory taking into account also nontrivial two-particle correlations, and quantum-jump-type Monte Carlo simulations. For the case of the ideal Fermi gas, these methods are applied to simple lattice models and the possibility of achieving exotic states via bath engineering is pointed out. The largest part of this work is devoted to bosonic quantum gases and the phenomenon of Bose selection, a nonequilibrium generalization of Bose condensation, where multiple single-particle states are selected to acquire a large occupation [Phys. Rev. Lett. 111, 240405 (2013), 10.1103/PhysRevLett.111.240405]. In this context, among others, we provide a theory for transitions where the set of selected states changes, describe an efficient algorithm for finding the set of selected states, investigate beyond-mean-field effects, and identify the dominant mechanisms for heat transport in the Bose-selected state.
Steady-state and dynamic network modes for perceptual expectation.
Choi, Uk-Su; Sung, Yul-Wan; Ogawa, Seiji
2017-01-12
Perceptual expectation can attenuate repetition suppression, the stimulus-induced neuronal response generated by repeated stimulation, suggesting that repetition suppression is a top-down modulatory phenomenon. However, it is still unclear which high-level brain areas are involved and how they interact with low-level brain areas. Further, the temporal range over which perceptual expectation can effectively attenuate repetition suppression effects remains unclear. To elucidate the details of this top-down modulatory process, we used two short and long inter-stimulus intervals for a perceptual expectation paradigm of paired stimulation. We found that top-down modulation enhanced the response to the unexpected stimulus when repetition suppression was weak and that the effect disappeared at 1,000 ms prior to stimulus exposure. The high-level areas involved in this process included the left inferior frontal gyrus (IFG_L) and left parietal lobule (IPL_L). We also found two systems providing modulatory input to the right fusiform face area (FFA_R): one from IFG_L and the other from IPL_L. Most importantly, we identified two states of networks through which perceptual expectation modulates sensory responses: one is a dynamic state and the other is a steady state. Our results provide the first functional magnetic resonance imaging (fMRI) evidence of temporally nested networks in brain processing.
Glaucoma affects steady state VEP contrast thresholds before psychophysics.
Vaegan; Rahman, Anmar M A; Sanderson, Gordon F
2008-07-01
Frequency doubling technology (FDT) is a recent psychophysical test for glaucoma. It measures the contrast threshold to low spatial frequency, high temporal frequency sinusoidal luminance profile bars. We wanted to confirm, with stricter controls, Vaegan and Hollow's report that contrast thresholds of steady state visual evoked potentials (ssVEPs) to a stimulus resembling the central field of the FDT test was more sensitive to glaucoma than the subjective threshold to the same stimulus and to start to optimize the technique. A double masked trial using 57 eyes of 42 subjects. Both thresholds were estimated by modified binary search. In psychophysical testing, subjects were given a two alternative forced choice task. In ssVEP testing a significant signal in any one of eight channels was deemed to be a detection. In some subjects electrode positions were compared, both eyes were tested, tests were repeated to estimate reliability, stimulus frequencies were varied or full contrast functions were obtained. Thresholds and percent abnormal increased as a function of glaucoma severity for ssVEPs but not for psychophysics. Both threshold measures were reliable. Interocular correlations were low. SsVEP amplitude against contrast functions had similar thresholds to those found by modified binary search. The data was too irregular for individual thresholds to be estimated from a fitted exponential. Amplitudes were greatest at 7 to 10 Hz, psychophysical thresholds at 18.29 Hz, when formal controls were used, as they had in a less controlled previous study at 7.14 Hz.
ADI type preconditioners for the steady state inhomogeneous Vlasov equation
Gasteiger, Markus; Ostermann, Alexander; Tskhakaya, David
2016-01-01
The purpose of the current work is to find numerical solutions of the steady state inhomogeneous Vlasov equation. This problem has a wide range of applications in the kinetic simulation of non-thermal plasmas. However, the direct application of either time stepping schemes or iterative methods (such as Krylov based methods like GMRES or relexation schemes) is computationally expensive. In the former case the slowest timescale in the system forces us to perform a long time integration while in the latter case a large number of iterations is required. In this paper we propose a preconditioner based on an ADI type splitting method. This preconditioner is then combined with both GMRES and Richardson iteration. The resulting numerical schemes scale almost ideally (i.e. the computational effort is proportional to the number of grid points). Numerical simulations conducted show that this can result in a speedup of close to two orders of magnitude (even for intermediate grid sizes) with respect to the not preconditio...
Full steady-state operation in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Kazarian-Vibert, F.; Litaudon, X.; Moreau, D.; Arslanbekov, R.; Hoang, G.T.; Peysson, Y. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee
1996-12-01
In order to produce fully non-inductive, lower hybrid (LH) driven discharges in a systematic and reproducible manner, new operation modes have been studied on the superconducting Tore Supra tokamak. To cope with some uncertainties in the LH current drive efficiency (e.g. profile dependences), the plasma current is not imposed a priori, but evolves freely until the equilibrium (which depends on the LH power level) is reached. The voltage applied on the primary circuit no longer controls the plasma current. In an `open loop` scenario in which this voltage is present and constant, the timescale required to attain the equilibrium is the longest characteristic time of the coupled plasma-poloidal field coils system ({approx} 60 s). In order to obtain a stationary state faster, a new feedback scheme has been implemented in which the primary circuit voltage is controlled in such a way that the flux consumption vanishes. It is shown that this operation mode allows full steady-state to be reached within a characteristic time of a few seconds. The underlying physics is described and a detailed analysis of the experiments is made. It is shown, in particular, that this operation scenario generates stable stationary plasmas with improved confinement, so that the so-called `LHEP` regime can be extrapolated to continuous operation. (Author).
Grand canonical steady-state simulation of nucleation
Horsch, Martin
2009-01-01
Grand canonical molecular dynamics (GCMD) is applied to the nucleation process in a metastable phase near the spinodal, where nucleation occurs almost instantaneously and is limited to a very short time interval. With a variant of Maxwell's demon, proposed by McDonald [Am. J. Phys. 31: 31 (1963)], all nuclei exceeding a specified size are removed. In such a steady-state simulation, the nucleation process is sampled over an arbitrary timespan and all properties of the metastable state, including the nucleation rate, can be obtained with an increased precision. As an example, a series of GCMD simulations with McDonald's demon is carried out for homogeneous vapor to liquid nucleation of the truncated-shifted Lennard-Jones (tsLJ) fluid, covering the entire relevant temperature range. The results are in agreement with direct non-equilibrium MD simulation in the canonical ensemble. It is confirmed for supersaturated vapors of the tsLJ fluid that the classical nucleation theory underpredicts the nucleation rate by t...
Nonequilibrium steady states of ideal bosonic and fermionic quantum gases.
Vorberg, Daniel; Wustmann, Waltraut; Schomerus, Henning; Ketzmerick, Roland; Eckardt, André
2015-12-01
We investigate nonequilibrium steady states of driven-dissipative ideal quantum gases of both bosons and fermions. We focus on systems of sharp particle number that are driven out of equilibrium either by the coupling to several heat baths of different temperature or by time-periodic driving in combination with the coupling to a heat bath. Within the framework of (Floquet-)Born-Markov theory, several analytical and numerical methods are described in detail. This includes a mean-field theory in terms of occupation numbers, an augmented mean-field theory taking into account also nontrivial two-particle correlations, and quantum-jump-type Monte Carlo simulations. For the case of the ideal Fermi gas, these methods are applied to simple lattice models and the possibility of achieving exotic states via bath engineering is pointed out. The largest part of this work is devoted to bosonic quantum gases and the phenomenon of Bose selection, a nonequilibrium generalization of Bose condensation, where multiple single-particle states are selected to acquire a large occupation [Phys. Rev. Lett. 111, 240405 (2013)]. In this context, among others, we provide a theory for transitions where the set of selected states changes, describe an efficient algorithm for finding the set of selected states, investigate beyond-mean-field effects, and identify the dominant mechanisms for heat transport in the Bose-selected state.
Steady State Response Analysis of a Tubular Piezoelectric Print Head.
Chang, Jiaqing; Liu, Yaxin; Huang, Bo
2016-01-12
In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes' thicknesses on the system deformation status is provided.
Development of the ITER Advanced Steady State and Hybrid Scenarios
Energy Technology Data Exchange (ETDEWEB)
C.E. Kessel, D. Campbell, T. Casper, Y. Gribov, and J. Snipes
2010-09-24
Full discharge simulations are performed to examine the plasma current rampup, flattop and rampdown phases self-consistently with the poloidal field (PF) coils and their limitations, plasma transport evolution, and heating/current drive (H/CD) sources. Steady state scenarios are found that obtain 100% non-inductive current with Ip = 7.3-10.0 MA, βN ~ 2.5 for H98 = 1.6, Q’s range from 3 to 6, n/nGr = 0.75-1.0, and NB, IC, EC, and LH source have been examined. The scenarios remain within CS/PF coil limits by advancing the pre-magnetization by 40 Wb. Hybrid scenarios have been identified with 35-40% non-inductive current for Ip = 12.5 MA, H98 ~ 1.25, with q(0) reaching 1 at or after the end of rampup. The equilibrium operating space for the hybrid shows a large range of scenarios can be accommodated, and access 925-1300 s flattop burn durations.
A theory of nonequilibrium steady states in quantum chaotic systems
Wang, Pei
2017-09-01
Nonequilibrium steady state (NESS) is a quasistationary state, in which exist currents that continuously produce entropy, but the local observables are stationary everywhere. We propose a theory of NESS under the framework of quantum chaos. In an isolated quantum system whose density matrix follows a unitary evolution, there exist initial states for which the thermodynamic limit and the long-time limit are noncommutative. The density matrix \\hat ρ of these states displays a universal structure. Suppose that \\renewcommand{\\ket}[1]{{\\vert #1 >}} \\ketα and \\renewcommand{\\ket}[1]{{\\vert #1 >}} \\ketβ are different eigenstates of the Hamiltonian with energies E_α and E_β , respectively. \\renewcommand{\\bra}[1]{} \\braα\\hat ρ \\ketβ behaves as a random number which has zero mean. In thermodynamic limit, the variance of \\renewcommand{\\bra}[1]{} \\braα\\hat ρ \\ketβ is a smooth function of ≤ft\\vert E_α-E_β\\right\\vert , scaling as 1/≤ft\\vert E_α-E_β\\right\\vert 2 in the limit ≤ft\\vert E_α-E_β\\right\\vert \\to 0 . If and only if this scaling law is obeyed, the initial state evolves into NESS in the long time limit. We present numerical evidence of our hypothesis in a few chaotic models. Furthermore, we find that our hypothesis indicates the eigenstate thermalization hypothesis (ETH) for current operators in a bipartite system.
Steady-state evolution of debris disks around A stars
Wyatt, M C; Su, K Y L; Rieke, G H; Greaves, J S; Beichman, C A; Bryden, G
2007-01-01
In this paper a simple analytical model for the steady-state evolution of debris disks due to collisions is confronted with Spitzer observations of main sequence A stars. All stars are assumed to have planetesimal belts with a distribution of initial masses and radii. In the model disk mass is constant until the largest planetesimals reach collisional equilibrium whereupon the mass falls off oc 1/t. We find that the detection statistics and trends seen at both 24 and 70um can be fitted well by the model. While there is no need to invoke stochastic evolution or delayed stirring to explain the statistics, a moderate rate of stochastic events is not ruled out. Potentially anomalous systems are identified by a high dust luminosity compared with the maximum permissible in the model (HD3003, HD38678, HD115892, HD172555). Their planetesimals may have unusual properties (high strength or low eccentricity) or this dust could be transient. While transient phenomena are also favored for a few systems in the literature, ...
Classical quasi-steady state reduction-A mathematical characterization
Goeke, Alexandra; Walcher, Sebastian; Zerz, Eva
2017-04-01
We discuss parameter dependent polynomial ordinary differential equations that model chemical reaction networks. By classical quasi-steady state (QSS) reduction we understand the following familiar (heuristically motivated) mathematical procedure: Set the rate of change for certain (a priori chosen) variables equal to zero and use the resulting algebraic equations to obtain a system of smaller dimension for the remaining variables. This procedure will generally be valid only for certain parameter ranges. We start by showing that the reduction is accurate if and only if the corresponding parameter is what we call a QSS parameter value, and that the reduction is approximately accurate if and only if the corresponding parameter is close to a QSS parameter value. The QSS parameter values can be characterized by polynomial equations and inequations, hence parameter ranges for which QSS reduction is valid are accessible in an algorithmic manner. A defining characteristic of a QSS parameter value is that the algebraic variety defined by the QSS relations is invariant for the differential equation. A closer investigation of the associated systems shows the existence of further invariant sets; here singular perturbations enter the picture in a natural manner. We compare QSS reduction and singular perturbation reduction, and show that, while they do not agree in general, they do, up to lowest order in a small parameter, for a quite large and relevant class of examples. This observation, in turn, allows the computation of QSS reductions even in cases where an explicit resolution of the polynomial equations is not possible.
Visual steady state in relation to age and cognitive function
Dyhr Thomsen, Mia; Wiegand, Iris; Horwitz, Henrik; Klemp, Marc; Nikolic, Miki; Rask, Lene; Lauritzen, Martin; Benedek, Krisztina
2017-01-01
Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age. PMID:28245274
Non-steady state population kinetics of intravenous phenytoin.
Frame, B; Beal, S L
1998-08-01
This observational study explored the effects of demographics, sickness, and polypharmacy on the non-steady state population pharmacokinetics of intravenous phenytoin. One hundred fifteen patients were studied. Models were developed using the NONMEM program with hybrid first-order conditional estimation. A Michaelis-Menten model with delayed induction was preferred over a Michaelis-Menten model without induction, a Michaelis-Menten model with immediate induction, or a linear model with delayed induction. When the data were fit to a Michaelis-Menten model with delayed induction, the volume of distribution (Vd) was found to depend on weight and serum albumin. The Vd was estimated to be 0.95 l/kg, assuming an albumin level of 3 g/dl. The Michaelis-Menten constant (km) was estimated to be 7.9 mg/l. The baseline maximum metabolic rate was 580 mg/day for a 70-kg patient. The average time to onset of induction was 59.5 hours. If a fever developed after induction began, it increased the extent of induction. This model was evaluated retrospectively in 26 additional patients, yielding a mean prediction error of -0.4 mg/l (-3.0-2.2 mg/l) and a mean absolute prediction error of 4.7 mg/l (3.2-6.2 mg/l) based on two-level feedback. Given the large interindividual variances in maximum metabolic rate, phenytoin levels should be measured frequently.
Dynamic steady-state of periodically-driven quantum systems
Yudin, V I; Basalaev, M Yu; Kovalenko, D
2015-01-01
Using the density matrix formalism, we prove an existence theorem of the periodic steady-state for an arbitrary periodically-driven system. This state has the same period as the modulated external influence, and it is realized as an asymptotic solution ($t$$\\to$$+\\infty$) due to relaxation processes. The presented derivation simultaneously contains a simple computational algorithm non-using both Floquet and Fourier theories, i.e. our method automatically guarantees a full account of all frequency components. The description is accompanied by the examples demonstrating a simplicity and high efficiency of our method. In particular, for three-level $\\Lambda$-system we calculate the lineshape and field-induced shift of the dark resonance formed by the field with periodically modulated phase. For two-level atom we obtain the analytical expressions for signal of the direct frequency comb spectroscopy with rectangular light pulses. In this case it was shown the radical dependence of the spectroscopy lineshape on pul...
Models of steady state cooling flows in elliptical galaxies
Vedder, Peter W.; Trester, Jeffrey J.; Canizares, Claude R.
1988-01-01
A comprehensive set of steady state models for spherically symmetric cooling flows in early-type galaxies is presented. It is found that a reduction of the supernova (SN) rate in ellipticals produces a decrease in the X-ray luminosity of galactic cooling flows and a steepening of the surface brightness profile. The mean X-ray temperature of the cooling flow is not affected noticeably by a change in the SN rate. The external pressure around a galaxy does not markedly change the luminosity of the gas within the galaxy but does change the mean temperature of the gas. The presence of a dark matter halo in a galaxy only changes the mean X-ray temperature slightly. The addition of a distribution of mass sinks which remove material from the general accretion flow reduces L(X) very slightly, flattens the surface brightness profile, and reduces the central surface brightness level to values close to those actually observed. A reduction in the stellar mass-loss rate only slightly reduces the X-ray luminosity of the cooling flow and flattens the surface brightness by a small amount.
Multiple repetition time balanced steady-state free precession imaging.
Cukur, Tolga; Nishimura, Dwight G
2009-07-01
Although balanced steady-state free precession (bSSFP) imaging yields high signal-to-noise ratio (SNR) efficiency, the bright lipid signal is often undesirable. The bSSFP spectrum can be shaped to suppress the fat signal with scan-efficient alternating repetition time (ATR) bSSFP. However, the level of suppression is limited, and the pass-band is narrow due to its nonuniform shape. A multiple repetition time (TR) bSSFP scheme is proposed that creates a broad stop-band with a scan efficiency comparable with ATR-SSFP. Furthermore, the pass-band signal uniformity is improved, resulting in fewer shading/banding artifacts. When data acquisition occurs in more than a single TR within the multiple-TR period, the echoes can be combined to significantly improve the level of suppression. The signal characteristics of the proposed technique were compared with bSSFP and ATR-SSFP. The multiple-TR method generates identical contrast to bSSFP, and achieves up to an order of magnitude higher stop-band suppression than ATR-SSFP. In vivo studies at 1.5 T and 3 T demonstrate the superior fat-suppression performance of multiple-TR bSSFP.
Kinematical Analysis along Maximal Lactate Steady State Swimming Intensity
Directory of Open Access Journals (Sweden)
Pedro Figueiredo, Rafael Nazario, Marisa Sousa, Jailton Gregório Pelarigo, João Paulo Vilas-Boas, Ricardo Fernandes
2014-09-01
Full Text Available The purpose of this study was to conduct a kinematical analysis during swimming at the intensity corresponding to maximal lactate steady state (MLSS. Thirteen long distance swimmers performed, in different days, an intermittent incremental protocol of n x 200 m until exhaustion and two to four 30-min submaximal constant speed bouts to determine the MLSS. The video analysis, using APAS System (Ariel Dynamics Inc., USA, allowed determining the following relevant swimming determinants (in five moments of the 30-min test: 0, 25, 50, 75, and 100%: stroke rate, stroke length, trunk incline, intracyclic velocity variation, propelling efficiency, index of coordination and the time allotted to propulsion per distance unit. An ANOVA for repeated measures was used to compare the parameters mean values along each moment of analysis. Stoke rate tended to increase and stroke length to decrease along the test; a tendency to decrease was also found for intracyclic velocity variation and propelling efficiency whereas the index of coordination and the propulsive impulse remained stable during the MLSS test. It can be concluded that the MLSS is not only an intensity to maintain without a significant increase of blood lactate concentration, but a concomitant stability for some biomechanical parameters exists (after an initial adaptation. However, efficiency indicators seem to be more sensitive to changes occurring during swimming at this threshold intensity.
The inductive, steady-state sustainment of stable spheromaks
Hossack, A. C.; Jarboe, T. R.; Morgan, K. D.; Sutherland, D. A.; Hansen, C. J.; Everson, C. J.; Penna, J. M.; Nelson, B. A.
2016-10-01
Inductive helicity injection current drive with imposed perturbations has led to the breakthrough of spheromak sustainment while maintaining stability. Sustained spheromaks show coherent, imposed plasma motion and low plasma-generated mode activity, indicating stability. Additionally, record current gain of 3.9 has been achieved with evidence of pressure confinement. The Helicity Injected Torus - Steady Inductive (HIT-SI) experiment studies efficient, steady-state current drive for magnetic confinement plasmas using a novel experimental method which is ideal for low aspect ratio, toroidal geometries and is compatible with closed flux surfaces. Analysis of surface magnetic probes indicates large n = 0 and 1 toroidal Fourier mode amplitudes and little energy in higher modes. Biorthogonal decomposition shows that almost all of the n = 1 energy is imposed by the injectors, rather than plasma-generated. Ion Doppler spectroscopy (IDS) measurements show coherent, imposed plasma motion of +/-2.5 cm in the region inside r 10 cm (a = 23 cm) and the size of the separate spheromak is consistent with that predicted by Imposed-dynamo Current Drive (IDCD). Coherent motion indicates that the spheromak is stable and a lack of plasma-generated n = 1 energy indicates that the maximum q is maintained below 1 for stability during sustainment.
Steady state relativistic stellar dynamics around a massive black hole
Bar-Or, Ben
2015-01-01
A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the "loss-cone", which take them directly into the MBH, or close enough to interact strongly with it. The resulting phenomena: tidal heating and tidal disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, are of interest as they can produce observable signatures and thereby reveal the existence of the MBH, affect its mass and spin evolution, probe strong gravity, and provide information on stars and gas near the MBH. The continuous loss of stars and the processes that resupply them shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss-cone of a non-spinning MBH in steady-state analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclos...
Ising game: Nonequilibrium steady states of resource-allocation systems
Xin, C.; Yang, G.; Huang, J. P.
2017-04-01
Resource-allocation systems are ubiquitous in the human society. But how external fields affect the state of such systems remains poorly explored due to the lack of a suitable model. Because the behavior of spins pursuing energy minimization required by physical laws is similar to that of humans chasing payoff maximization studied in game theory, here we combine the Ising model with the market-directed resource-allocation game, yielding an Ising game. Based on the Ising game, we show theoretical, simulative and experimental evidences for a formula, which offers a clear expression of nonequilibrium steady states (NESSs). Interestingly, the formula also reveals a convertible relationship between the external field (exogenous factor) and resource ratio (endogenous factor), and a class of saturation as the external field exceeds certain limits. This work suggests that the Ising game could be a suitable model for studying external-field effects on resource-allocation systems, and it could provide guidance both for seeking more relations between NESSs and equilibrium states and for regulating human systems by choosing NESSs appropriately.
The Path of Carbon in Photosynthesis. XX. The Steady State
Energy Technology Data Exchange (ETDEWEB)
Calvin, M.; Massini, Peter
1952-09-01
The separation of the phenomenon of photosynthesis in green plants into a photochemical reaction and into the light-dependent reduction of carbon dioxide is discussed, The reduction of carbon dioxide and the fate of the assimilated carbon were investigated with the help of the tracer technique (exposure of the planks to the radioactive C{sup 14}O{sub 2}) and of paper chromatography. A reaction cycle is proposed in which phosphoglyceric acid is the first isolable assimilations product. Analyses of the algal extracts which had assimilated radioactive carbon dioxide in a stationary condition ('steady-state' photosynthesis) for a long time provided further information concerning the proposed cycle and permitted the approximate estimation, for a number of compounds of what fraction of each compound was taking part in the cycle. The earlier supposition that light influences the respiration cycle was confirmed. The possibility of the assistance of {alpha}-lipoic acid, or of a related substance, in this influence and in the photosynthesis cycle, is discussed.
Artificial recharge of humic ground water.
Alborzfar, M; Villumsen, A; Grøn, C
2001-01-01
The purpose of this study was to investigate the efficiency of soil in removing natural organic matter from humic ground waters using artificial recharge. The study site, in western Denmark, was a 10,000 ml football field of which 2,000 m2 served as an infiltration field. The impact of the artificial recharge was studied by monitoring the water level and the quality of the underlying shallow aquifer. The humic ground water contained mainly humic adds with an organic carbon (OC) concentration of 100 to 200 mg C L(-1). A total of 5,000 mS of humic ground water were sprinkled onto the infiltration field at an average rate of 4.25 mm h(-1). This resulted in a rise in the water table of the shallow aquifer. The organic matter concentration of the water in the shallow aquifer, however, remained below 2.7 mg C L(-1). The organic matter concentration of the pore water in the unsaturated zone was measured at the end of the experiment. The organic matter concentration of the pore water decreased from 105 mg C L(-1) at 0.5 m to 20 mg C L(-1) at 2.5 m under the infiltration field indicating that the soil removed the organic matter from the humic ground water. From these results we conclude that artificial recharge is a possible method for humic ground water treatment.
Ground Water Quality of Selected Wells
Directory of Open Access Journals (Sweden)
Mosher R. Ahmed
2013-05-01
Full Text Available In order to characterize ground water quality in Zaweta district / Dohuk governorate, eight wells are selected to represent their water quality. Monthly samples are collected from the wells for the period from October 2005 to April 2006. The samples are tested for conductivity, total dissolved solids, pH, total hardness, chloride, alkalinity and nitrate according to the standard methods. The results of statistical analysis showed significant difference among the wells water quality in the measured parameters. Ground water quality of Zaweta district has high dissolved ions due to the nature of studied area rocks. Total dissolved solids of more than 1000 mg/l made the wells Gre-Qassroka, Kora and Swaratoka need to be treated to make taste palatable. Additionally high electrical conductivity and TDS made Zaweta ground water have a slight to moderate restriction to crop growth. The high alkalinity of Zaweta ground water indicated stabilized pH. The water quality of all the wells is found excessively hard. The nitrate concentration of Zaweta ground water ranged between 0.19-42.4 mg/l below the guidelines for WHO and the maximum nitrate concentration is recorded in Kora well .
Steady-state propagation of interface corner crack
DEFF Research Database (Denmark)
Veluri, Badrinath; Jensen, Henrik Myhre
2013-01-01
by estimating the fracture mechanics parameters that includes the strain energy release rate, crack front profiles and the three-dimensional mode-mixity along the interface crack front. A numerical approach was then applied for coupling the far field solutions based on the Finite Element Method to the near...... field (crack tip) solutions based on the J-integral. The adopted two-dimensional numerical approach for the calculation of fracture mechanical properties was compared with three-dimensional models for quarter-circular and straight sided crack front shapes. A quantitative approach was formulated based...
Two-Dimensional turbulence in the inverse cascade range
Yakhot, V
1999-01-01
A theory of two-dimensional turbulence in the inverse energy cascade range is presented. Strong time-dependence of the large-scale features of the flow ($\\bar{u^{2}}\\propto t$) results in decoupling of the large-scale dynamics from statistically steady-state small-scale random processes. This time-dependence is also a reason for the localness of the pressure-gradient terms in the equations governing the small-scale velocity difference PDF's. The derived expressions for the pressure gradient contributions lead to a gaussian statistics of transverse velocity differences. The solution for the PDF of longitudinal velocity differences is based on a smallness of the energy flux in two-dimensional turbulence. The theory makes a few quantitative predictions which can be tested experimentally. One of the most surprising results, derived in this paper, is that the small-scale transverse velocity differences are governed by a linear Langevin-like equation, strirred by a non-local universal gaussian random force. This ex...
Institute of Scientific and Technical Information of China (English)
无
1998-01-01
The Landau-Lifshitz equation of the ferromagnetic spin chain with Gilbert damping term is considered.which is described by δS/δt=S×ΔS-λS×（S×ΔS），All spatial nonhomogenuos steady-state solutions.which are the form S=R1 cos(lr)+ R2 sin(lr)Al∈R,wherer |R1|=|R2|=1 and R1⊥R2,are proposed,Moreover the instability of the spatial nonhomogenuos steady-state solutions Sl(r)(l≠0) is investigated.Every perturbation of the spatial nonhomogenuos steady-state tends to a spatial homogeneous steady-state as t→∞.Thus the hetercolinic orbits,which connect the spatial nonhomogenuos steady-state and the spatial homogeneous steady-state,are exist.Filially numerical experiments are provided.
Reagent removal of manganese from ground water
Brayalovsky, G.; Migalaty, E.; Naschetnikova, O.
2017-06-01
The study is aimed at the technology development of treating drinking water from ground waters with high manganese content and oxidizability. Current technologies, physical/chemical mechanisms and factors affecting in ground treatment efficiency are reviewed. Research has been conducted on manganese compound removal from ground waters with high manganese content (5 ppm) and oxidizability. The studies were carried out on granular sorbent industrial ODM-2F filters (0.7-1.5 mm fraction). It was determined that conventional reagent oxidization technologies followed by filtration do not allow us to obtain the manganese content below 0.1 ppm when treating ground waters with high oxidizability. The innovative oxidation-based manganese removal technology with continuous introduction of reaction catalytic agent is suggested. This technology is effective in alkalization up to pH 8.8-9. Potassium permanganate was used as a catalytic agent, sodium hypochlorite was an oxidizer and cauistic soda served an alkalifying agent.
Ground-water quality atlas of Wisconsin
Kammerer, Phil A.
1981-01-01
This report summarizes data on ground-water quality stored in the U.S. Geological Survey's computer system (WATSTORE). The summary includes water quality data for 2,443 single-aquifer wells, which tap one of the State's three major aquifers (sand and gravel, Silurian dolomite, and sandstone). Data for dissolved solids, hardness, alkalinity, calcium, magnesium, sodium, potassium, iron, manganese, sulfate, chloride, fluoride, and nitrate are summarized by aquifer and by county, and locations of wells for which data are available 1 are shown for each aquifer. Calcium, magnesium, and bicarbonate (the principal component of alkalinity) are the major dissolved constituents in Wisconsin's ground water. High iron concentrations and hardness cause ground-water quality problems in much of the State. Statewide ,summaries of trace constituent (selected trace metals; arsenic, boron, and organic carbon) concentrations show that these constituents impair water quality in only a few isolated wells.
Recharge estimation for transient ground water modeling.
Jyrkama, Mikko I; Sykes, Jon F; Normani, Stefano D
2002-01-01
Reliable ground water models require both an accurate physical representation of the system and appropriate boundary conditions. While physical attributes are generally considered static, boundary conditions, such as ground water recharge rates, can be highly variable in both space and time. A practical methodology incorporating the hydrologic model HELP3 in conjunction with a geographic information system was developed to generate a physically based and highly detailed recharge boundary condition for ground water modeling. The approach uses daily precipitation and temperature records in addition to land use/land cover and soils data. The importance of the method in transient ground water modeling is demonstrated by applying it to a MODFLOW modeling study in New Jersey. In addition to improved model calibration, the results from the study clearly indicate the importance of using a physically based and highly detailed recharge boundary condition in ground water quality modeling, where the detailed knowledge of the evolution of the ground water flowpaths is imperative. The simulated water table is within 0.5 m of the observed values using the method, while the water levels can differ by as much as 2 m using uniform recharge conditions. The results also show that the combination of temperature and precipitation plays an important role in the amount and timing of recharge in cooler climates. A sensitivity analysis further reveals that increasing the leaf area index, the evaporative zone depth, or the curve number in the model will result in decreased recharge rates over time, with the curve number having the greatest impact.
Xia, Jiangyan; Wang, Hongjun; Guo, Jianfei; Zhang, Zhijie; Coder, Brandon; Su, Dong-Ming
2012-06-01
The hymic medulla plays an essential role in the generation of central tolerance by eliminating self-reactive T-cell clones through thymic negative selection and developing natural regulatory T cells. Age-related FoxN1 decline induces disruption of medullary thymic epithelial cells (mTECs). However, it is unknown whether this perturbs central tolerance to increase autoimmune predisposition in the elderly. Using a loxP-floxed-FoxN1 (FoxN1(flox)) mouse model, which exhibits a spontaneous ubiquitous deletion of FoxN1 with age to accelerate thymic aging, we investigated whether disruption of steady-state thymic medulla results in an increase of autoimmune-prone associated with age. We demonstrated age-associated ubiquitous loss of FoxN1(flox)-formed two-dimensional thymic epithelial cysts were primarily located in the medulla. This resulted in disruption of thymic medullary steady state, with evidence of perturbed negative selection, including reduced expression of the autoimmune regulator (Aire) gene and disrupted accumulation of thymic dendritic cells in the medulla, which are required for negative selection. These provoke autoimmune phenotypes, including increased inflammatory cell infiltration in multiple organs in these mice. This finding in an animal model provides a mechanistic explanation of increased susceptibility to autoimmunity in aged humans, although they may not show clinic manifestations without induction.
Qualitative Analysis on a Reaction-Diffusion Prey Predator Model and the Corresponding Steady-States
Institute of Scientific and Technical Information of China (English)
Qunyi BIE; Rui PENG
2009-01-01
The authors study a diffusive prey-predator model subject to the homogeneous Neumann boundary condition and give some qualitative descriptions of solutions to this reaction-diffusion system and its corresponding steady-state problem.The local and global stability of the positive constant steady-state are discussed,and then some results for nonexistence of positive non-constant steady-states are derived.
Steady-state probability density function in wave turbulence under large volume limit
Institute of Scientific and Technical Information of China (English)
Yeontaek Choia; Sang Gyu Job
2011-01-01
We investigate the possibility for two-mode probability density function (PDF) to have a non-zero flux steady state solution. We take the large volume limit so that the space of modes becomes continuous. It is shown that in this limit all the steady-state two- or higher-mode PDFs are the product of one-mode PDFs. The flux of this steady-state solution turns out to be zero for any finite mode PDF.
NON-CONSTANT POSITIVE STEADY-STATES OF A PREDATOR-PREY-MUTUALIST MODEL
Institute of Scientific and Technical Information of China (English)
CHEN WENYAN; WANG MINGXIN
2004-01-01
In this paper, the authors deal with the non-constant positive steady-states of a predator-prey-mutualist model with homogeneous Neumann boundary condition. They first give a priori estimates (positive upper and lower bounds) of positive steady-states,and then study the non-existence, the global existence and bifurcation of non-constant positive steady-states as some parameters are varied. Finally the asymptotic behavior of such solutions as d3 →∞ is discussed.
Directory of Open Access Journals (Sweden)
Zaidon M. Shakoor
2013-05-01
Full Text Available In this research, two models are developed to simulate the steady state fixed bed reactor used for styrene production by ethylbenzene dehydrogenation. The first is one-dimensional model, considered axial gradient only while the second is two-dimensional model considered axial and radial gradients for same variables.The developed mathematical models consisted of nonlinear simultaneous equations in multiple dependent variables. A complete description of the reactor bed involves partial, ordinary differential and algebraic equations (PDEs, ODEs and AEs describing the temperatures, concentrations and pressure drop across the reactor was given. The model equations are solved by finite differences method. The reactor models were coded with Mat lab 6.5 program and various numerical techniques were used to obtain the desired solution.The simulation data for both models were validated with industrial reactor results with a very good concordance.
Classifying Two-dimensional Hyporeductive Triple Algebras
Issa, A Nourou
2010-01-01
Two-dimensional real hyporeductive triple algebras (h.t.a.) are investigated. A classification of such algebras is presented. As a consequence, a classification of two-dimensional real Lie triple algebras (i.e. generalized Lie triple systems) and two-dimensional real Bol algebras is given.
Hopf and steady state bifurcation analysis in a ratio-dependent predator-prey model
Zhang, Lai; Liu, Jia; Banerjee, Malay
2017-03-01
In this paper, we perform spatiotemporal bifurcation analysis in a ratio-dependent predator-prey model and derive explicit conditions for the existence of non-constant steady states that emerge through steady state bifurcation from related constant steady states. These explicit conditions are numerically verified in details and further compared to those conditions ensuring Turing instability. We find that (1) Turing domain is identical to the parametric domain where there exists only steady state bifurcation, which implies that Turing patterns are stable non-constant steady states, but the opposite is not necessarily true; (2) In non-Turing domain, steady state bifurcation and Hopf bifurcation act in concert to determine the emergent spatial patterns, that is, non-constant steady state emerges through steady state bifurcation but it may be unstable if the destabilising effect of Hopf bifurcation counteracts the stabilising effect of diffusion, leading to non-stationary spatial patterns; (3) Coupling diffusion into an ODE model can significantly enrich population dynamics by inducing alternative non-constant steady states (four different states are observed, two stable and two unstable), in particular when diffusion interacts with different types of bifurcation; (4) Diffusion can promote species coexistence by saving species which otherwise goes to extinction in the absence of diffusion.
A new perspective on steady-state cosmology: from Einstein to Hoyle
O'Raifeartaigh, Cormac
2015-01-01
We recently reported the discovery of an unpublished manuscript by Albert Einstein in which he attempted a 'steady-state' model of the universe, i.e., a cosmic model in which the expanding universe remains essentially unchanged due to a continuous formation of matter from empty space. The manuscript was apparently written in early 1931, many years before the steady-state models of Fred Hoyle, Hermann Bondi and Thomas Gold. We compare Einstein's steady-state cosmology with that of Hoyle, Bondi and Gold and consider the reasons Einstein abandoned his model. The relevance of steady-state models for today's cosmology is briefly reviewed.
On the number of steady states in a multiple futile cycle.
Wang, Liming; Sontag, Eduardo D
2008-07-01
The multisite phosphorylation-dephosphorylation cycle is a motif repeatedly used in cell signaling. This motif itself can generate a variety of dynamic behaviors like bistability and ultrasensitivity without direct positive feedbacks. In this paper, we study the number of positive steady states of a general multisite phosphorylation-dephosphorylation cycle, and how the number of positive steady states varies by changing the biological parameters. We show analytically that (1) for some parameter ranges, there are at least n + 1 (if n is even) or n (if n is odd) steady states; (2) there never are more than 2n - 1 steady states (in particular, this implies that for n = 2, including single levels of MAPK cascades, there are at most three steady states); (3) for parameters near the standard Michaelis-Menten quasi-steady state conditions, there are at most n + 1 steady states; and (4) for parameters far from the standard Michaelis-Menten quasi-steady state conditions, there is at most one steady state.
Simulation and Analysis on Multiple Steady States of an Industrial Acetic Acid Dehydration System
Institute of Scientific and Technical Information of China (English)
李绍军; 黄定伟
2011-01-01
In this work, an industrial acetic acid dehydration system via heterogeneous azeotropic distillation is simulated by Aspen Plus software. Residue curves are used to analyze the distillating behavior, and appropriate operating region of the system is determined. Based on steady states simulation, a sensitivity analysis is carried out to detect the output multiple steady states in the system. Different solution branches are observered when the flow rates of the feed stream and the organic reflux stream are selected as manipulated variables. The performance of the column under different steady states is different. A method is oroposed to achieve the desired steady state.
Ho, Pang-Yen; Chuang, Guo-Syong; Chao, An-Chong; Li, Hsing-Ya
2005-05-01
The capacity of complex biochemical reaction networks (consisting of 11 coupled non-linear ordinary differential equations) to show multiple steady states, was investigated. The system involved esterification of ethanol and oleic acid by lipase in an isothermal continuous stirred tank reactor (CSTR). The Deficiency One Algorithm and the Subnetwork Analysis were applied to determine the steady state multiplicity. A set of rate constants and two corresponding steady states are computed. The phenomena of bistability, hysteresis and bifurcation are discussed. Moreover, the capacity of steady state multiplicity is extended to the family of the studied reaction networks.
Auditory steady-state responses for estimating moderate hearing loss.
Swanepoel, DeWet; Erasmus, Hettie
2007-07-01
The auditory steady-state response (ASSR) has gained popularity as an alternative technique for objective audiometry but its use in less severe degrees of hearing loss has been questioned. The aim of this study was to investigate the usefulness of the ASSR in estimating moderate degrees of hearing loss. Seven subjects (12 ears) with moderate sensorineural hearing loss between 15 and 18 years of age were enrolled in the study. Forty-eight behavioural and ASSR thresholds were obtained across the frequencies of 0.5, 1, 2, and 4 kHz. ASSR thresholds were determined using a dichotic multiple frequency recording technique. Mean threshold differences varied between 2 and 8 dB (+/-7-10 dB SD) across frequencies. The highest difference and variability was recorded at 0.5 kHz. The frequencies 1-4 kHz also revealed significantly better correlations (0.74-0.88) compared to 0.5 kHz (0.31). Comparing correlation coefficients for behavioural thresholds less than 60 and 60 dB and higher revealed a significant difference. Eighty-six percent of ASSR thresholds corresponded within 5 dB of moderate to severe behavioural thresholds compared to only 29% for mild to moderate thresholds in this study. The results confirm that the ASSR can reliably estimate behavioural thresholds of 60 dB and higher, but due to increased variability, caution is recommended when estimating behavioural thresholds of less than 60 dB, especially at 0.5 kHz.
Nonequilibrium steady states in a model for prebiotic evolution
Wynveen, A.; Fedorov, I.; Halley, J. W.
2014-02-01
Some statistical features of steady states of a Kauffman-like model for prebiotic evolution are reported from computational studies. We postulate that the interesting "lifelike" states will be characterized by a nonequilibrium distribution of species and a time variable species self-correlation function. Selecting only such states from the population of final states produced by the model yields the probability of the appearance of such states as a function of a parameter p of the model. p is defined as the probability that a possible reaction in the the artificial chemistry actually appears in the network of chemical reactions. Small p corresponds to sparse networks utilizing a small fraction of the available reactions. We find that the probability of the appearance of such lifelike states exhibits a maximum as a function of p: at large p, most final states are in chemical equilibrium and hence are excluded by our criterion. At very small p, the sparseness of the network makes the probability of formation of any nontrivial dynamic final state low, yielding a low probability of production of lifelike states in this limit as well. We also report results on the diversity of the lifelike states (as defined here) that are produced. Repeated starts of the model evolution with different random number seeds in a given reaction network lead to final lifelike states which have a greater than random likelihood of resembling one another. Thus a form of "convergence" is observed. On the other hand, in different reaction networks with the same p, lifelike final states are statistically uncorrelated. In summary, the main results are (1) there is an optimal p or "sparseness" for production of lifelike states in our model—neither very dense nor very sparse networks are optimal—and (2) for a given p or sparseness, the resulting lifelike states can be extremely different. We discuss some possible implications for studies of the origin of life.
Steady state growth of E. Coli in low ammonium environment
Kim, Minsu; Deris, Barret; Zhang, Zhongge; Hwa, Terry
2011-03-01
Ammonium is the preferred nitrogen source for many microorganisms. In medium with low ammonium concentrations, enteric bacteria turn on the nitrogen responsive (ntr) genes to assimilate ammonium. Two proteins in E. coli, Glutamine synthetase (GS) and the Ammonium/methylammonium transporter AmtB play crucial roles in this regard. GS is the major ammonium assimilation enzyme below 1mM of NH4 + . AmtB is an inner membrane protein that transports NH4 + across the cell membrane against a concentration gradient. In order to study ammonium uptake at low NH4 + concentration at neutral pH, we developed a microfluidic flow chamber that maintains a homogenous nutrient environment during the course of exponential cell growth, even at very low concentration of nutrients. Cell growth can be accurately monitored using time-lapse microscopy. We followed steady state growth down to micro-molar range of NH4 + for the wild type and Δ amtB strains. The wild type strain is able to maintain the growth rate from 10mM down to a few uM of NH4 + , while the mutant exhibited reduced growth below ~ 20 ~uM of NH4 + . Simultaneous characterization of the expression levels of GS and AmtB using fluorescence reporters reveals that AmtB is turned on already at 1mM, but contributes to function only below ~ 30 ~uM in the wild-type. Down to ~ 20 ~uM of NH4 + , E.~coli can compensate the loss of AmtB by GS alone.
Human auditory steady state responses to binaural and monaural beats.
Schwarz, D W F; Taylor, P
2005-03-01
Binaural beat sensations depend upon a central combination of two different temporally encoded tones, separately presented to the two ears. We tested the feasibility to record an auditory steady state evoked response (ASSR) at the binaural beat frequency in order to find a measure for temporal coding of sound in the human EEG. We stimulated each ear with a distinct tone, both differing in frequency by 40Hz, to record a binaural beat ASSR. As control, we evoked a beat ASSR in response to both tones in the same ear. We band-pass filtered the EEG at 40Hz, averaged with respect to stimulus onset and compared ASSR amplitudes and phases, extracted from a sinusoidal non-linear regression fit to a 40Hz period average. A 40Hz binaural beat ASSR was evoked at a low mean stimulus frequency (400Hz) but became undetectable beyond 3kHz. Its amplitude was smaller than that of the acoustic beat ASSR, which was evoked at low and high frequencies. Both ASSR types had maxima at fronto-central leads and displayed a fronto-occipital phase delay of several ms. The dependence of the 40Hz binaural beat ASSR on stimuli at low, temporally coded tone frequencies suggests that it may objectively assess temporal sound coding ability. The phase shift across the electrode array is evidence for more than one origin of the 40Hz oscillations. The binaural beat ASSR is an evoked response, with novel diagnostic potential, to a signal that is not present in the stimulus, but generated within the brain.
40 CFR 257.22 - Ground-water monitoring systems.
2010-07-01
... operator. When physical obstacles preclude installation of ground-water monitoring wells at the relevant... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Ground-water monitoring systems. 257... Waste Disposal Units Ground-Water Monitoring and Corrective Action § 257.22 Ground-water......
Two-dimensional function photonic crystals
Wu, Xiang-Yao; Liu, Xiao-Jing; Liang, Yu
2016-01-01
In this paper, we have firstly proposed two-dimensional function photonic crystals, which the dielectric constants of medium columns are the functions of space coordinates $\\vec{r}$, it is different from the two-dimensional conventional photonic crystals constituting by the medium columns of dielectric constants are constants. We find the band gaps of two-dimensional function photonic crystals are different from the two-dimensional conventional photonic crystals, and when the functions form of dielectric constants are different, the band gaps structure should be changed, which can be designed into the appropriate band gaps structures by the two-dimensional function photonic crystals.
Ground-water provinces of southern Rhodesia
Dennis, Philip Eldon; Hindson, L.L.
1964-01-01
Ground-water development, utilization, and occurrence in nine ground-water provinces of Southern Rhodesia are summarized in this report. Water obtained from drilled wells for domestic and stock use has played an important part in the social and economic development of Southern Rhodesia from the beginnings of European settlement to the present. Most of the wells obtain water from fractures and weathered zones in crystalline rocks, before recently, there has been an interest in the possibility of obtaining water for irrigation from wells. Studies of the authors indicate that quantities of water sufficient for irrigation can be obtained from alluvial sediments in the S'abi Valley, from Kalahari sands in the western part of the country, are perhaps from aquifers in other areas. The ground-water provinces fall into two groups--those in the crystalline rocks and those in the noncrystalline rocks. Historically, the wells in crystalline rocks, especially the Gold belts province and the Intrusive granites province, have played a major role in supplying water for the needs of man. These provinces, together with two other less important crystalline rock provinces, form the broad arch which constitutes the central core of the country. The noncrystalline rocks overlie and flank the crystalline rocks to the southeast, northwest, and north. The noncrystalline rock provinces, especially the Alluvium-Kalahari province, contain the most productive or potentially productive ground-water reservoirs in Southern Rhodesia and offer promise of supplying water for irrigation and for other purposes.
Magnificent Ground Water Connection. [Sample Activities].
Environmental Protection Agency, Washington, DC.
Water conservation and usage is an important concept in science. This document, geared specifically to New England, provides many activities for protecting and discussing ground water situations. Sample activities for grades K-6 include: (1) All the Water in the World; (2) The Case of the Disappearing Water; (3) Deep Subjects--Wells and Ground…
Ground Water Flow No Longer A Mystery
Lehr, Jay H.; Pettyjohn, Wayne A.
1976-01-01
Examined are the physical characteristics of ground water movement. Some potential pollution problems are identified. Models are used to explain mathematical and hydraulic principles of flow toward a pumping well and an effluent stream, flow around and through lenticular beds, and effects of pumping on the water table. (Author/MR)
Depth to ground water of Nevada
U.S. Geological Survey, Department of the Interior — This is a raster-based, depth to ground-water data set for the State of Nevada. The source of this data set is a statewide water-table contour data set constructed...
Jones, Perry M.
2002-01-01
The U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources, conducted a study to characterize ground-water flow conditions between the Canisteo Mine Pit, Bovey, Minnesota, and surrounding aquifers following mine abandonment. The objective of the study was to estimate the amount of steady-state, ground-water flow between the Canisteo Mine Pit and surrounding aquifers at pit water-level altitudes below the level at which surface-water discharge from the pit may occur. Single-well hydraulic tests and stream-hydrograph analyses were conducted to estimate horizontal hydraulic conductivities and ground-water recharge rates, respectively, for glacial aquifers surrounding the mine pit. Average hydraulic conductivity values ranged from 0.05 to 5.0 ft/day for sands and clays and from 0.01 to 121 ft/day for coarse sands, gravels, and boulders. The 15-year averages for the estimated annual recharge using the winter records and the entire years of record for defining baseflow recession rates were 7.07 and 7.58 in., respectively. These recharge estimates accounted for 25 and 27 percent, respectively, of the average annual precipitation for the 1968-82 streamflow monitoring period. Ground-water flow rates into and out of the mine pit were estimated using a calibrated steady-state, ground-water flow model simulating an area of approximately 75 mi2 surrounding the mine pit. The model residuals, or difference between simulated and measured water levels, for 15 monitoring wells adjacent to the mine pit varied between +28.65 and –3.78 ft. The best-match simulated water levels were within 4 ft of measured water levels for 9 of the 15 wells, and within 2 ft for 4 of the wells. The simulated net ground-water flow into the Canisteo Mine Pit was +1.34 ft3/s, and the net ground-water flow calculated from pit water levels measured between July 5, 1999 and February 25, 2001 was +5.4 ft3/s. Simulated water levels and ground-water flow to and from the mine
On the validity of travel-time based nonlinear bioreactive transport models in steady-state flow.
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A
2015-01-01
Travel-time based models simplify the description of reactive transport by replacing the spatial coordinates with the groundwater travel time, posing a quasi one-dimensional (1-D) problem and potentially rendering the determination of multidimensional parameter fields unnecessary. While the approach is exact for strictly advective transport in steady-state flow if the reactive properties of the porous medium are uniform, its validity is unclear when local-scale mixing affects the reactive behavior. We compare a two-dimensional (2-D), spatially explicit, bioreactive, advective-dispersive transport model, considered as "virtual truth", with three 1-D travel-time based models which differ in the conceptualization of longitudinal dispersion: (i) neglecting dispersive mixing altogether, (ii) introducing a local-scale longitudinal dispersivity constant in time and space, and (iii) using an effective longitudinal dispersivity that increases linearly with distance. The reactive system considers biodegradation of dissolved organic carbon, which is introduced into a hydraulically heterogeneous domain together with oxygen and nitrate. Aerobic and denitrifying bacteria use the energy of the microbial transformations for growth. We analyze six scenarios differing in the variance of log-hydraulic conductivity and in the inflow boundary conditions (constant versus time-varying concentration). The concentrations of the 1-D models are mapped to the 2-D domain by means of the kinematic (for case i), and mean groundwater age (for cases ii & iii), respectively. The comparison between concentrations of the "virtual truth" and the 1-D approaches indicates extremely good agreement when using an effective, linearly increasing longitudinal dispersivity in the majority of the scenarios, while the other two 1-D approaches reproduce at least the concentration tendencies well. At late times, all 1-D models give valid approximations of two-dimensional transport. We conclude that the
Oxygen consumption dynamics in steady-state tumour models.
Grimes, David Robert; Fletcher, Alexander G; Partridge, Mike
2014-09-01
Oxygen levels in cancerous tissue can have a significant effect on treatment response: hypoxic tissue is both more radioresistant and more chemoresistant than well-oxygenated tissue. While recent advances in medical imaging have facilitated real-time observation of macroscopic oxygenation, the underlying physics limits the resolution to the millimetre domain, whereas oxygen tension varies over a micrometre scale. If the distribution of oxygen in the tumour micro-environment can be accurately estimated, then the effect of potential dose escalation to these hypoxic regions could be better modelled, allowing more realistic simulation of biologically adaptive treatments. Reaction-diffusion models are commonly used for modelling oxygen dynamics, with a variety of functional forms assumed for the dependence of oxygen consumption rate (OCR) on cellular status and local oxygen availability. In this work, we examine reaction-diffusion models of oxygen consumption in spherically and cylindrically symmetric geometries. We consider two different descriptions of oxygen consumption: one in which the rate of consumption is constant and one in which it varies with oxygen tension in a hyperbolic manner. In each case, we derive analytic approximations to the steady-state oxygen distribution, which are shown to closely match the numerical solutions of the equations and accurately predict the extent to which oxygen can diffuse. The derived expressions relate the limit to which oxygen can diffuse into a tissue to the OCR of that tissue. We also demonstrate that differences between these functional forms are likely to be negligible within the range of literature estimates of the hyperbolic oxygen constant, suggesting that the constant consumption rate approximation suffices for modelling oxygen dynamics for most values of OCR. These approximations also allow the rapid identification of situations where hyperbolic consumption forms can result in significant differences from constant
Isotopic composition of ground waters from Kufra (Lybia) as indicator for ground water formation
Energy Technology Data Exchange (ETDEWEB)
Swailem, F.M.; Hamza, M.S.; Aly, A.I.M. (Middle Eastern Regional Radioisotope Centre for the Arab Countries, Cairo (Egypt))
1984-02-01
The results of the isotopic composition of shallow and deep ground waters from the Kufra region indicate the fossil origin of these waters and that they are not recharged under the present climatic conditions. The virtual absence of tritium and the radiocarbon ages of these waters show that they were formed mainly in the past pluvial periods. Deuterium and oxygen-18 data indicate that the ground waters were recharged under cooler climatic conditions. These results may explain the origin of the large amounts of ground water which existed in the region.
Effects of soil heterogeneity on steady state soil water pressure head under a surface line source
Zhang, Z. Fred; Parkin, Gary W.; Kachanoski, R. Gary; Smith, James E.
2002-07-01
There are numerous analytical solutions available for flow in unsaturated homogeneous porous media. In this paper, the stream tube model for one-dimensional water movement is extended to two-dimensional (2-D) water movement from a line source as the stream plane model. As well, new solutions are derived to predict the mean and variance of pressure head of water movement under a surface line source in heterogeneous soil using the perturbation method with first-order approximation (PM1) and with second-order approximation (PM2). A variance expression was also developed based on the spectral relationship presented by Yeh et al. [1985a]. The new solutions were tested using the 2-D stream plane model with parameters A = ln(α) and Y = ln(KS) and measurements from field experiments. Results show that the mean of steady state pressure head below the line source is not only a function of the mean parameter values but also a function of the variances of A and Y and the linear cross-correlation coefficient (ρ) between A and Y. The PM2 model can predict the mean pressure head accurately in heterogeneous soils at any level of correlation between A and Y, except when both the soil variability and ρ are high. The pressure head variance estimation based on the PM1 model predicts the measured variance well only when both the soil variability and ρ are low. The field experimental results show that both the PM1 and the spectral models give reasonable predictions of the pressure head variance. Both the measured and predicted values of the variance of pressure head using the two models increase with the depth of soil. Both models show that the variance of pressure head decreases as the source strength increases, but on average, the pressure head variance was underestimated by both models.
Unenhanced steady state free precession versus traditional MR imaging for congenital heart disease
Energy Technology Data Exchange (ETDEWEB)
Chang, Dandan, E-mail: chchsister@163.com [Department of Diagnostic Radiology, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong (China); Kong, Xiangquan, E-mail: kxq0525@126.com [Department of Radiology, the Affiliated Union Hospital, Huazhong University of Science and Technology, Wuhan, Hubei (China); Zhou, Xuhui, E-mail: xiaolintongqq@126.com [Department of Diagnostic Radiology, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong (China); Li, Shurong, E-mail: 80917333@qq.com [Department of Diagnostic Radiology, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong (China); Wang, Huanjun, E-mail: 463822507@qq.com [Department of Diagnostic Radiology, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong (China)
2013-10-01
Purpose: To assess potential benefits of three dimensional (3D) steady state free precession (SSFP) magnetic resonance sequence for congenital heart disease (CHD). Materials and methods: Twenty consecutive patients with CHD (male:female ratio,14:6, mean age, 27.5 ± 8.5 years) underwent both 3D SSFP and traditional MR imaging (TMRI) [including two dimensional (2D) SSFP and contrast enhanced magnetic resonance angiography (CEMRA)]. Image quality and diagnosis were compared, and Bland–Altman analysis was used to evaluate consistency of 3D SSFP and CEMRA for diameter measurements. Results: A total of 35 intra and 81 extra cardiac anomalies were identified in all patients. The image quality of 3D SSFP and TMRI for either intra or extra cardiac anomalies of all patients scored ≥3, which allowed an establishment of diagnosis for all cases. The diagnostic sensitivity, specificity, and accuracy of 3D SSFP for the detection of intra cardiac anomalies were all 100%, whereas for extra cardiac anomalies they were 93.8%, 93.8%, 100%, respectively. Mean differences (3D SSFP minus CEMRA) for aorta and pulmonary arteries were 0.5 ± 1.2 mm and 0.0 ± 1.7 mm, respectively, showing good consistency of 3D SSFP and CEMRA for diameter measurements. Conclusion: 3D SSFP MRI can be an alternative image modality to TMRI for patients with congenital heart disease, especially for those who have renal insufficiency, breath-hold difficulty or who are allergic to contrast agent. It can also provide powerful complementary information for patients who undergo TMRI, especially at ventriculoarterial connection site.
Banks, W.S.; Smith, B.S.; Donnelly, C.A.
1996-01-01
The U.S. Army disposed chemical agents, laboratory materials, and unexploded ordnance at O-Field in the Edgewood area of Aberdeen Proving Ground, Maryland, from before World War II until at least the 1950's. Soil, ground water, surface water,and wetland sediments in the O-Field area were contaminated from the disposal activity. A ground-water-flow model of the O-Field area was constructed by the U.S. Geological Survey (USGS) in 1989 to simulate flow in the central and southern part of the Gunpowder Neck. The USGS began an additional study of the contamination in the O-Field area in cooperation with the U.S. Army in 1990 to (1) further define the hydrogeologic framework of the O-Field area, (2) characterize the hydraulic properties of the aquifers and confining units, and (3) define ground-water flow paths at O-Field based on the current data and simulations of ground-water flow. A water-table aquifer, an upper confining unit, and an upper confined aquifer comprise the shallow ground-water aquifer system of the O-Field area. A lower confining unit, through which ground-water movement is negligible, is considered a lower boundary to the shallow aquifer system. These units are all part of the Pleistocene Talbot Formation. The model developed in the previous study was redesigned using the data collected during this study and emphasized New O-Field. The current steady-state model was calibrated to water levels of June 1993. The rate of ground-water flow calculated by the model was approximately 0.48 feet per day (ft/d) and the rate determined from chlorofluorocarbon dates was approximately 0.39 ft/d.
Oki, Delwyn S.; Tribble, Gordon W.; Souza, William R.; Bolke, Edward L.
1999-01-01
Within the Kaloko-Honokohau National Historical Park, which was established in 1978, the ground-water flow system is composed of brackish water overlying saltwater. Ground-water levels measured in the Park range from about 1 to 2 feet above mean sea level, and fluctuate daily by about 0.5 to 1.5 feet in response to ocean tides. The brackish water is formed by mixing of seaward flowing fresh ground water with underlying saltwater from the ocean. The major source of fresh ground water is from subsurface flow originating from inland areas to the east of the Park. Ground-water recharge from the direct infiltration of precipitation within the Park area, which has land-surface altitudes less than 100 feet, is small because of low rainfall and high rates of evaporation. Brackish water flowing through the Park ultimately discharges to the fishponds in the Park or to the ocean. The ground water, fishponds, and anchialine ponds in the Park are hydrologically connected; thus, the water levels in the ponds mark the local position of the water table. Within the Park, ground water near the water table is brackish; measured chloride concentrations of water samples from three exploratory wells in the Park range from 2,610 to 5,910 milligrams per liter. Chromium and copper were detected in water samples from the three wells in the Park and one well upgradient of the Park at concentrations of 1 to 5 micrograms per liter. One semi-volatile organic compound, phenol, was detected in water samples from the three wells in the Park at concentrations between 4 and 10 micrograms per liter. A regional, two-dimensional (areal), freshwater-saltwater, sharp-interface ground-water flow model was used to simulate the effects of regional withdrawals on ground-water flow within the Park. For average 1978 withdrawal rates, the estimated rate of fresh ground-water discharge to the ocean within the Park is about 6.48 million gallons per day, or about 3 million gallons per day per mile of coastline
Steady State Comparisons HAWC2 v12.2 vs HAWCStab2 v2.12
DEFF Research Database (Denmark)
Verelst, David Robert; Hansen, Morten Hartvig; Pirrung, Georg
This reports presents comparison of the steady state HAWC2 [1] [2] [3] simulation results and the HAWCStab2 computations of the DTU10MW reference turbine [4] [5]. It serves as a simple validation for the HAWCStab2 [6] [7] [8] steady state computations....
Distance to achieve steady state walking speed in frail elderly persons
Lindemann, U.; Najafi, B.; Zijlstra, W.; Hauer, K.; Muche, R.; Becker, C.; Aminian, K.
2008-01-01
This study aims to determine the length of the gait initiation phase before achieving steady state walking in frail older people. Based on body fixed sensors, habitual walking was analysed in 116 community-dwelling older persons (mean age 83.1 years, 84% women). The start of steady state walking was
40 CFR Appendix D to Subpart S of... - Steady-State Short Test Equipment
2010-07-01
.... Electromagnetic signals found in an automotive service environment shall not cause malfunctions or changes in the... Short Test Equipment (I) Steady-State Test Exhaust Analysis System (a) Sampling system—(1) General requirements. The sampling system for steady-state short tests shall, at a minimum, consist of a tailpipe...
A steady-state analytical slope stability model for complex hillslopes
Talebi, A.; Troch, P.A.; Uijlenhoet, R.
2008-01-01
This paper presents a steady-state analytical hillslope stability model to study the role of topography on rain-induced shallow landslides. We combine a bivariate continuous function of the topographic surface, a steady-state hydrological model of hillslope saturated storage, and the infinite slope
A steady-state analytical slope stability model for complex hillslopes
Talebi, A.; Troch, P.A.; Uijlenhoet, R.
2008-01-01
This paper presents a steady-state analytical hillslope stability model to study the role of topography on rain-induced shallow landslides. We combine a bivariate continuous function of the topographic surface, a steady-state hydrological model of hillslope saturated storage, and the infinite slope
Highly enhanced steady-state optomechanical entanglement via cross-Kerr nonlinearity
Chakraborty, Subhadeep
2016-01-01
We study steady-state optomechanical entanglement in presence of an additional cross-Kerr coupling between the optical and mechanical mode. We find that a significant enhancement of the steady-state entanglement can be achieved at a considerably lower driving power, which is also extremely robust with respect to system parameters and environmental temperature.
Steady State Solution for the Weakly Damped Forced Korteweg—de Vries Equation
Institute of Scientific and Technical Information of China (English)
BolingGUO; GuoguangLIN
1998-01-01
The existence and uniqueness of steady state solution for the weakly damped forced KdV equation with a periodic boundary value problems are proved.It is obtained that the every solution of the weakly damped forced KdV equations converges to the steady state soluton as time t→∞。
Stream-power incision model in non-steady-state mountain ranges: An empirical approach
Institute of Scientific and Technical Information of China (English)
CHEN Yen-Chieh; SUNG Quocheng; CHEN Chao-Nan
2006-01-01
Stream-power incision model has always been applied to detecting the steady-state situation of ranges. Oblique arc-continent collision occurring during the period of Penglai Orogeny caused the Taiwan mountain belt to develop landscape of three evolution stages, namely stages of pre-steady-state (growing ranges in southern Taiwan), steady-state (ranges in central Taiwan) and post-steady-state (decaying ranges in northern Taiwan). In the analysis on streams of the Taiwan mountain belt made by exploring the relationship between the slope of bedrock channel (S) and the catchment area (A), the topographic features of the ranges at these three stages are acquired. The S-A plot of the steady-state ranges is in a linear form, revealing that the riverbed height of bedrock channel does not change over time (dz/dt =0). The slope and intercept of the straight line S-A are related to evolution time of steady-state topography and tectonic uplift rate respectively. The S-A plots of the southern and northern ranges of Taiwan mountain belt appear to be in convex and concave forms respectively, implying that the riverbed height of bedrock channel at the two ranges rises (dz/dt＞0)and falls (dz/dt＜0) over time respectively. Their tangent intercept can still reflect the tectonic uplift rate.This study develops an empirical stream-power eresion model of pre-steady-state and post-steady-state topography.
Development of synchronous generator saturation model from steady-state operating data
Energy Technology Data Exchange (ETDEWEB)
Jadric, Martin; Despalatovic, Marin; Terzic, Bozo [FESB University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split (Croatia)
2010-11-15
A new method to estimate and model the saturated synchronous reactances of hydroturbine generators from operating data is presented. For the estimation process, measurements of only the generator steady-state variables are required. First, using a specific procedure, the field to armature turns ratio is estimated from measured steady-state variables at constant power generation and various excitation conditions. Subsequently, for each set of steady-state operating data, saturated synchronous reactances are identified. Fitting surfaces, defined as polynomial functions in two variables, are later used to model these saturated reactances. It is shown that the simpler polynomial functions may be used to model saturation at the steady-state than at the dynamic conditions. The developed steady-state model is validated with measurements performed on the 34 MVA hydroturbine generator. (author)
On the use of steady-state signal equations for 2D TrueFISP imaging.
Coolen, Bram F; Heijman, Edwin; Nicolay, Klaas; Strijkers, Gustav J
2009-07-01
To explain the signal behavior in 2D-TrueFISP imaging, a slice excitation profile should be considered that describes a variation of effective flip angles and magnetization phases after excitation. These parameters can be incorporated into steady-state equations to predict the final signal within a pixel. The use of steady-state equations assumes that excitation occurs instantaneously, although in reality this is a nonlinear process. In addition, often the flip angle variation within the slice excitation profile is solely considered when using steady-state equations, while TrueFISP is especially known for its sensitivity to phase variations. The purpose of this study was therefore to evaluate the precision of steady-state equations in calculating signal intensities in 2D TrueFISP imaging. To that end, steady-state slice profiles and corresponding signal intensities were calculated as function of flip angle, RF phase advance and pulse shape. More complex Bloch simulations were considered as a gold standard, which described every excitation within the sequence until steady state was reached. They were used to analyze two different methods based on steady-state equations. In addition, measurements on phantoms were done with corresponding imaging parameters. Although the Bloch simulations described the steady-state slice profile formation better than methods based on steady-state equations, the latter performed well in predicting the steady-state signal resulting from it. In certain cases the phase variation within the slice excitation profile did not even have to be taken into account.
D'Agnese, Frank A.; O'Brien, G. M.; Faunt, C.C.; Belcher, W.R.; San Juan, C.
2002-01-01
In the early 1990's, two numerical models of the Death Valley regional ground-water flow system were developed by the U.S. Department of Energy. In general, the two models were based on the same basic hydrogeologic data set. In 1998, the U.S. Department of Energy requested that the U.S. Geological Survey develop and maintain a ground-water flow model of the Death Valley region in support of U.S. Department of Energy programs at the Nevada Test Site. The purpose of developing this 'second-generation' regional model was to enhance the knowledge an understanding of the ground-water flow system as new information and tools are developed. The U.S. Geological Survey also was encouraged by the U.S. Department of Energy to cooperate to the fullest extent with other Federal, State, and local entities in the region to take advantage of the benefits of their knowledge and expertise. The short-term objective of the Death Valley regional ground-water flow system project was to develop a steady-state representation of the predevelopment conditions of the ground-water flow system utilizing the two geologic interpretations used to develop the previous numerical models. The long-term objective of this project was to construct and calibrate a transient model that simulates the ground-water conditions of the study area over the historical record that utilizes a newly interpreted hydrogeologic conceptual model. This report describes the result of the predevelopment steady-state model construction and calibration. The Death Valley regional ground-water flow system is situated within the southern Great Basin, a subprovince of the Basin and Range physiographic province, bounded by latitudes 35 degrees north and 38 degrees 15 minutes north and by longitudes 115 and 118 degrees west. Hydrology in the region is a result of both the arid climatic conditions and the complex geology. Ground-water flow generally can be described as dominated by interbasinal flow and may be conceptualized as
Hadamard States and Two-dimensional Gravity
Salehi, H
2001-01-01
We have used a two-dimensional analog of the Hadamard state-condition to study the local constraints on the two-point function of a linear quantum field conformally coupled to a two-dimensional gravitational background. We develop a dynamical model in which the determination of the state of the quantum field is essentially related to the determination of a conformal frame. A particular conformal frame is then introduced in which a two-dimensional gravitational equation is established.
Topological defects in two-dimensional crystals
Chen, Yong; Qi, Wei-Kai
2008-01-01
By using topological current theory, we study the inner topological structure of the topological defects in two-dimensional (2D) crystal. We find that there are two elementary point defects topological current in two-dimensional crystal, one for dislocations and the other for disclinations. The topological quantization and evolution of topological defects in two-dimensional crystals are discussed. Finally, We compare our theory with Brownian-dynamics simulations in 2D Yukawa systems.
Case study on ground water flow (8)
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-02-01
The report comprises research activities made in fiscal year 1997 under the contract of Japan Nuclear Fuel Cycle Development Center and the main items are: (1) Evaluation of water permeability through discontinuous hard bedrock in deep strata in relevant with underground disposal of radioactive wastes, (2) Three dimensional analysis of permeated water in bedrock, including flow analysis in T ono district using neuro-network and modification of Evaporation Logging System, (3) Development of hydraulic tests and necessary equipment applicable to measurements of complex dielectric constants of contaminated soils using FUDR-V method, this giving information on soil component materials, (4) Investigation methods and modeling of hydraulics in deep strata, (5) Geological study of ground water using environmental isotopes such as {sup 14}C, {sup 36}Cl and {sup 4}He, particularly measurement of ages of ground water using an accelerator-mass spectrometer, and (6) Re-submerging phenomena affecting the long-term geological stability. (S. Ohno)
Artificial Ground Water Recharge with Surface Water
Heviánková, Silvie; Marschalko, Marian; Chromíková, Jitka; Kyncl, Miroslav; Korabík, Michal
2016-10-01
With regard to the adverse manifestations of the recent climatic conditions, Europe as well as the world have been facing the problem of dry periods that reduce the possibility of drawing drinking water from the underground sources. The paper aims to describe artificial ground water recharge (infiltration) that may be used to restock underground sources with surface water from natural streams. Among many conditions, it aims to specify the boundary and operational conditions of the individual aspects of the artificial ground water recharge technology. The principle of artificial infiltration lies in the design of a technical system, by means of which it is possible to conduct surplus water from one place (in this case a natural stream) into another place (an infiltration basin in this case). This way, the water begins to infiltrate into the underground resources of drinking water, while the mixed water composition corresponds to the water parameters required for drinking water.
Case study on ground water flow (8)
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-02-01
The report comprises research activities made in fiscal year 1997 under the contract of Japan Nuclear Fuel Cycle Development Center and the main items are: (1) Evaluation of water permeability through discontinuous hard bedrock in deep strata in relevant with underground disposal of radioactive wastes, (2) Three dimensional analysis of permeated water in bedrock, including flow analysis in T ono district using neuro-network and modification of Evaporation Logging System, (3) Development of hydraulic tests and necessary equipment applicable to measurements of complex dielectric constants of contaminated soils using FUDR-V method, this giving information on soil component materials, (4) Investigation methods and modeling of hydraulics in deep strata, (5) Geological study of ground water using environmental isotopes such as {sup 14}C, {sup 36}Cl and {sup 4}He, particularly measurement of ages of ground water using an accelerator-mass spectrometer, and (6) Re-submerging phenomena affecting the long-term geological stability. (S. Ohno)
Procedures for ground-water investigations
Energy Technology Data Exchange (ETDEWEB)
1989-09-01
This manual was developed by the Pacific Northwest Laboratory (PNL) to document the procedures used to carry out and control the technical aspects of ground-water investigations at the PNL. Ground-water investigations are carried out to fulfill the requirements for the US Department of Energy (DOE) to meet the requirements of DOE Orders. Investigations are also performed for various clients to meet the requirements of the Resource Conservation and Recovery Act of 1976 (RCRA) and the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA). National standards including procedures published by the American Society for Testing and Materials (ASTM) and the US Geological Survey were utilized in developing the procedures contained in this manual.
Nitrate Removal from Ground Water: A Review
Archna *; Surinder K. Sharma; Ranbir Chander Sobti
2012-01-01
Nitrate contamination of ground water resources has increased in Asia, Europe, United States, and various other parts of the world. This trend has raised concern as nitrates cause methemoglobinemia and cancer. Several treatment processes can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation. Available technical data, experience, and economics indicate that biological denitrification is more acceptable for nitrate removal than reverse osmosis and ion ex...
Ground water and the rural homeowner
Waller, Roger M.
1994-01-01
As the salesmen sang in the musical The Music Man, "You gotta know the territory." This saying is also true when planning to buy or build a house. Learn as much as possible about the land, the water supply, and the septic system of the house before buying or building. Do not just look at the construction aspects or the beauty of the home and surroundings. Be sure to consider the environmental conditions around and beneath the site as well. Try to visit the site under adverse conditions, such as during heavy rain or meltwater runoff, to observe the drainage characteristics, particularly the condition of the basement. Many of the conditions discussed in this book, such as lowered well-water levels, flooded basements, and contamination from septic systems, are so common that rural families often have to deal with one or more of them. The purpose of this book is to awaken an interest in ground water and an awareness of where it is available, how it moves, how people can adjust to its patterns to avoid problems, and how it can be protected and used wisely. This booklet provides both present and prospective rural homeowners, particularly those in the glaciated northern parts of the United States, with a basic but comprehensive description of ground water. It also presents problems one may expect to encounter with ground water and some solutions or suggestions for help with these problems.
2015-01-01
A two-dimensional single-phase model is developed for the steady-state and transient analysis of polymer electrolyte membrane fuel cells (PEMFC). Based on diluted and concentrated solution theories, viscous flow is introduced into a phenomenological multi-component modeling framework in the membrane. Characteristic variables related to the water uptake are discussed. A ButlereVolmer formulation of the current-overpotential relationship is developed based on an elementary mechanism of elect...
HT2DINV: A 2D forward and inverse code for steady-state and transient hydraulic tomography problems
Soueid Ahmed, A.; Jardani, A.; Revil, A.; Dupont, J. P.
2015-12-01
Hydraulic tomography is a technique used to characterize the spatial heterogeneities of storativity and transmissivity fields. The responses of an aquifer to a source of hydraulic stimulations are used to recover the features of the estimated fields using inverse techniques. We developed a 2D free source Matlab package for performing hydraulic tomography analysis in steady state and transient regimes. The package uses the finite elements method to solve the ground water flow equation for simple or complex geometries accounting for the anisotropy of the material properties. The inverse problem is based on implementing the geostatistical quasi-linear approach of Kitanidis combined with the adjoint-state method to compute the required sensitivity matrices. For undetermined inverse problems, the adjoint-state method provides a faster and more accurate approach for the evaluation of sensitivity matrices compared with the finite differences method. Our methodology is organized in a way that permits the end-user to activate parallel computing in order to reduce the computational burden. Three case studies are investigated demonstrating the robustness and efficiency of our approach for inverting hydraulic parameters.
Solution of the two- dimensional heat equation for a rectangular plate
Directory of Open Access Journals (Sweden)
Nurcan BAYKUŞ SAVAŞANERİL
2015-11-01
Full Text Available Laplace equation is a fundamental equation of applied mathematics. Important phenomena in engineering and physics, such as steady-state temperature distribution, electrostatic potential and fluid flow, are modeled by means of this equation. The Laplace equation which satisfies boundary values is known as the Dirichlet problem. The solutions to the Dirichlet problem form one of the most celebrated topics in the area of applied mathematics. In this study, a novel method is presented for the solution of two-dimensional heat equation for a rectangular plate. In this alternative method, the solution function of the problem is based on the Green function, and therefore on elliptic functions.
Cellular neural network analysis for two-dimensional bioheat transfer equation.
Niu, J H; Wang, H Z; Zhang, H X; Yan, J Y; Zhu, Y S
2001-09-01
The cellular neural network (CNN) method is applied to solve the Pennes bioheat transfer equation, and its feasibility is demonstrated. Numerical solutions were obtained for a cellular neural network for a two-dimensional steady-state temperature field obtained from focused and unfocused ultrasound heat sources. Transient-state temperature fields were also studied and compared with experimental results obtained elsewhere. The cellular neural networks' key features of asynchronous parallel processing, continuous-time dynamics and local interaction enable real-time temperature field estimation for clinical hyperthermia.
Friction damping of two-dimensional motion and its application in vibration control
Menq, C.-H.; Chidamparam, P.; Griffin, J. H.
1991-01-01
This paper presents an approximate method for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces. The friction force at the joint is formulated based on the Coulomb model. The single-term harmonic balance scheme, together with the receptance approach of decoupling the effect of the friction force on the structure from those of the external forces has been utilized to obtain the steady state response. The computational efficiency and accuracy of the method are demonstrated by comparing the results with long-term time solutions.
Status for the two-dimensional Navier-Stokes solver EllipSys2D
DEFF Research Database (Denmark)
Bertagnolio, F.; Sørensen, Niels N.; Johansen, J.
2001-01-01
This report sets up an evaluation of the two-dimensional Navier-Stokes solver EllipSys2D in its present state. This code is used for blade aerodynamics simulations in the Aeroelastic Design group at Risø. Two airfoils are investigated by computing theflow at several angles of attack ranging from...... the linear to the stalled region. The computational data are compared to experimental data and numerical results from other computational codes. Several numerical aspects are studied, as mesh dependency,convective scheme, steady state versus unsteady computations, transition modelling. Some general...... conclusions intended to help in using this code for numerical simulations are given....
Ultrashort light bullets described by the two-dimensional sine-Gordon equation
Leblond, Hervé; 10.1103/PHYSREVA.81.063815
2011-01-01
By using a reductive perturbation technique applied to a two-level model, this study puts forward a generic two-dimensional sine-Gordon evolution equation governing the propagation of femtosecond spatiotemporal optical solitons in Kerr media beyond the slowly varying envelope approximation. Direct numerical simulations show that, in contrast to the long-wave approximation, no collapse occurs, and that robust (2+1)-dimensional ultrashort light bullets may form from adequately chosen few-cycle input spatiotemporal wave forms. In contrast to the case of quadratic nonlinearity, the light bullets oscillate in both space and time and are therefore not steady-state lumps.
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Topology optimization of two-dimensional waveguides
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard; Sigmund, Ole
2003-01-01
In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....
Basko, M. M.
2016-08-01
Theoretical investigation has been performed on the conversion efficiency (CE) into the 13.5-nm extreme ultraviolet (EUV) radiation in a scheme where spherical microspheres of tin (Sn) are simultaneously irradiated by two laser pulses with substantially different wavelengths. The low-intensity short-wavelength pulse is used to control the rate of mass ablation and the size of the EUV source, while the high-intensity long-wavelength pulse provides efficient generation of the EUV light at λ=13.5 nm. The problem of full optimization for maximizing the CE is formulated and solved numerically by performing two-dimensional radiation-hydrodynamics simulations with the RALEF-2D code under the conditions of steady-state laser illumination. It is shown that, within the implemented theoretical model, steady-state CE values approaching 9% are feasible; in a transient peak, the maximum instantaneous CE of 11.5% was calculated for the optimized laser-target configuration. The physical factors, bringing down the fully optimized steady-state CE to about one half of the absolute theoretical maximum of CE≈20 % for the uniform static Sn plasma, are analyzed in detail.
Energy Technology Data Exchange (ETDEWEB)
Yoon, Sam Hyun; Ha, Doo Hoe; Kwak, Jin Young [College of Medicine, Pochon CHA University, Sungnam (Korea, Republic of); Lee, Young Soo [Pundang CHA General Hospital, College of Medicine, Pochon CHA University, Seoul (Korea, Republic of)
2000-10-01
To assess the usefulness of three-dimensional Fourier transformation constructive interference in steady state (CISS) for the evaluation of chondromalacia. In 110 knee joints which underwent both MR imaging and arthroscopy, the findings were retrospectively reviewed. MR imaging sequences included two-dimensional dual-echo turbo spin-echo imaging along the sagittal and coronal planes, two-dimensional fast low-angle shot (FLASH) with magnetization transfer along the axial plane, and three-dimensional CISS along the sagittal plane. After the cartilage surfaces of each joint were divided into eight areas (each medial and lateral area of patellar facets, trochlear surfaces, femoral condyles, and tibial plateaux), a total of 880 areas were assessed. Using both combined two-dimensional (2-D turbo spin-echo and FLASH) and CISS imaging during different sessions, each chondromalacia case was assigned one of five grades. Arthroscopy revealed the presence of chondromalacia in 162 areas. This was first grade in 77 areas, second grade in 38, third grade in 21, and fourth grade in 26. The sensitivity, specificity, and accuracy of 2-D and CISS imaging were 48.1%, 93.7% and 85.3%, and 45.7%, 95.3% and 86.1%, respectively. Agreement between MR and arthroscopic staging occurred in 81.48% of 2-D imaging procedures and 82.16% of CISS procedures. If a difference of one grade was accepted, these proportions rose to 84.32% and 85.22%, respectively, though this increase was statistically insignificant. Though CISS imaging was less sensitive than 2-D imaging in the grading of chondromalacia, additional CISS imaging can help improve the accuracy of this grading.
Pre-steady-state Kinetics for Hydrolysis of Insoluble Cellulose by Cellobiohydrolase Cel7A
DEFF Research Database (Denmark)
Cruys-Bagger, Nicolaj; Olsen, Jens Elmerdahl; Præstgaard, Eigil;
2012-01-01
The transient kinetic behavior of enzyme reactions prior to the establishment of steady state is a major source of mechanistic information, yet this approach has not been utilized for cellulases acting on their natural substrate, insoluble cellulose. Here, we elucidate the pre-steady-state regime...... for the exo-acting cellulase Cel7A using amperometric biosensors and an explicit model for processive hydrolysis of cellulose. This analysis allows the identification of a pseudo-steady-state period and quantification of a processivity number as well as rate constants for the formation of a threaded enzyme...
Simulation of Multi-Steady States in Low Temperature Gas Discharge
Institute of Scientific and Technical Information of China (English)
李弘; 胡希伟
2004-01-01
This article presents hydrodynamics simulation of multi-steady states and mode transition by DC-beam-injected gas discharge, and provides a model approach to hysteresis and distinct forms of multi-steady states. The critical transition conditions of the three discharge modes (temperature limited mode, Langmuir mode, and space charge limited mode) are estimated to be dependent on the gas pressure and the filament temperature. Various forms of the multi-steady states in gas discharge can be uniformly explained by the displacement of the mutant positions. The simulation results are in a good agreement with those of the experiments.
Absolute Steady-State Thermal Conductivity Measurements by Use of a Transient Hot-Wire System
Roder, Hans M.; Perkins, Richard A.; Laesecke, Arno; Nieto de Castro, Carlos A.
2000-01-01
A transient hot-wire apparatus was used to measure the thermal conductivity of argon with both steady-state and transient methods. The effects of wire diameter, eccentricity of the wire in the cavity, axial conduction, and natural convection were accounted for in the analysis of the steady-state measurements. Based on measurements on argon, the relative uncertainty at the 95 % level of confidence of the new steady-state measurements is 2 % at low densities. Using the same hot wires, the relat...
Estimating time to steady state using the effective rate of drug accumulation.
Panebianco, Deborah L; Maes, Andrea
2011-01-01
Unless all of a drug is eliminated during each dosing interval, the plasma concentrations within a dosing interval will increase until the time course of change in plasma concentrations becomes invariant from one dosing interval to the next, resulting in steady state. A simple method for estimating drug concentration time to steady state based on multiple dose area under the plasma concentration-time curve and effective rate of drug accumulation is presented. Several point estimates and confidence intervals for time to 90% of steady state are compared, and a recommendation is made on how to summarize and present the results. Copyright © 2009 John Wiley & Sons, Ltd.
Guardia, M J; Gambhir, A; Europa, A F; Ramkrishna, D; Hu, W S
2000-01-01
Hybridoma cells utilize a pair of complementary and partially substitutable substrates, glucose and glutamine, for growth. It has been shown that cellular metabolism shifts under different culture conditions. When those cultures at different metabolic states are switched to a continuous mode, they reach different steady states under the same operating conditions. A cybernetic model was constructed to describe the complementary and partial substitutable nature of substrate utilization. The model successfully predicted the metabolic shift and multiple steady-state behavior. The results are consistent with the experimental observation that the history of the culture affects the resulting steady state.
Assessment of ground water pollution in the residential areas of ...
African Journals Online (AJOL)
Assessment of ground water pollution in the residential areas of Ewekoro and Shagamu ... of the ground water distribution of the settlements around cement factories in ... The concentrations of lead and cadmium are above the World Health ...
Simulation of ground-water flow in the vicinity of Hyde Park landfill, Niagara Falls, New York
Maslia, M.L.; Johnston, R.H.
1982-01-01
The Hyde Park landfill is a 15-acre chemical waste disposal site located north of Niagara Falls, New York. Underlying the site in descending order are: (1) low permeability glacial till, (2) a moderately permeable fractured rock aquifer--the Lockport Dolomite, and (3) a low permeability unit--the Rochester Shale. The site is bounded on three sides by ground-water drains; the Niagara River Gorge, the Niagara Power Project canal, and the power project conduits. A finite element model was used to simulate ground-water flow along an east-west section through the Hyde Park site (from the power project conduits to the Niagara Gorge). Steady-state conditions were simulated with an average annual recharge rate of 5 inches per year. The calibrated model simulated measured water levels within 5 feet in the glacial till and upper unit of the Lockport Dolomite and approximated the configuration of the water table. Based on simulation, ground-water flow near the Hyde Park site can be summarized as follows: 1. Specific discharge (Darcy velocity) ranges from about 0.01 to 0.1 foot per day in the upper unit of the Lockport Dolomite to less than 0.00001 foot per day in the Rochester Shale. Real velocities are highest in the upper unit of the Lockport, ranging from about 1.5 to 4.8 feet per day. 2. A ground-water divide exists east of the landfill, indicating that all ground water originating near or flowing beneath the landfill will flow toward and discharge in the gorge. 3. The zone of highest velocities (and presumably greatest potential for transporting chemical contaminants) includes the upper unit of the Lockport and part of the lower unit of the Lockport Dolomite between the landfill and the gorge. The time required for ground water to move from the landfill to the gorge in the Lockport Dolomite is estimated to be 5 to 7 years.
40 CFR 258.51 - Ground-water monitoring systems.
2010-07-01
... preclude installation of ground-water monitoring wells at the relevant point of compliance at existing... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Ground-water monitoring systems. 258... CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Ground-Water Monitoring and Corrective Action § 258.51...
U.S. Geological Survey, Department of the Interior — This digital data set represents ground-water discharged from the Death Valley regional ground-water flow system (DVRFS) through pumped wells. Pumping from wells in...
Pool, D.R.; Dickinson, Jesse E.
2007-01-01
A numerical ground-water model was developed to simulate seasonal and long-term variations in ground-water flow in the Sierra Vista subwatershed, Arizona, United States, and Sonora, Mexico, portions of the Upper San Pedro Basin. This model includes the simulation of details of the groundwater flow system that were not simulated by previous models, such as ground-water flow in the sedimentary rocks that surround and underlie the alluvial basin deposits, withdrawals for dewatering purposes at the Tombstone mine, discharge to springs in the Huachuca Mountains, thick low-permeability intervals of silt and clay that separate the ground-water flow system into deep-confined and shallow-unconfined systems, ephemeral-channel recharge, and seasonal variations in ground-water discharge by wells and evapotranspiration. Steady-state and transient conditions during 1902-2003 were simulated by using a five-layer numerical ground- water flow model representing multiple hydrogeologic units. Hydraulic properties of model layers, streamflow, and evapotranspiration rates were estimated as part of the calibration process by using observed water levels, vertical hydraulic gradients, streamflow, and estimated evapotranspiration rates as constraints. Simulations approximate observed water-level trends throughout most of the model area and streamflow trends at the Charleston streamflow-gaging station on the San Pedro River. Differences in observed and simulated water levels, streamflow, and evapotranspiration could be reduced through simulation of climate-related variations in recharge rates and recharge from flood-flow infiltration.
Characterization of Climax granite ground water
Energy Technology Data Exchange (ETDEWEB)
Isherwood, D.; Harrar, J.; Raber, E.
1982-08-01
The Climax ground water fails to match the commonly held views regarding the nature of deep granitic ground waters. It is neither dilute nor in equilibrium with the granite. Ground-water samples were taken for chemical analysis from five sites in the fractured Climax granite at the Nevada Test Site. The waters are high in total dissolved solids (1200 to 2160 mg/L) and rich in sodium (56 to 250 mg/L), calcium (114 to 283 mg/L) and sulfate (325 to 1060 mg/L). Two of the samples contained relatively high amounts of uranium (1.8 and 18.5 mg/L), whereas the other three contained uranium below the level of detection (< 0.1 mg/L). The pH is in the neutral range (7.3 to 8.2). The differences in composition between samples (as seen in the wide range of values for the major constituents and total dissolved solids) suggest the samples came from different, independent fracture systems. However, the apparent trend of increasing sodium with depth at the expense of calcium and magnesium suggests a common evolutionary chemical process, if not an interconnected system. The waters appear to be less oxidizing with depth (+ 410 mV at 420 m below the surface vs + 86 mV at 565 m). However, with Eh measurements on only two samples, this correlation is questionable. Isotopic analyses show that the waters are of meteoric origin and that the source of the sulfate is probably the pyrite in the fracture-fill material. Analysis of the measured water characteristics using the chemical equilibrium computer program EQ3 indicates that the waters are not in equilibrium with the local mineral assemblage. The solutions appear to be supersaturated with respect to the mineral calcite, quartz, kaolinite, muscovite, k-feldspar, and many others.
Institute of Scientific and Technical Information of China (English)
YANGXiao-Xue; LUOJin-Ming
2004-01-01
We present the explicit analytical expressions of the steady-state probability amplitudes and populations of atom levels in N-photon electromagnetically induced transparency for an arbitrary positive integer N.
Potential multiple steady-states in the long-term carbon cycle
Tennenbaum, Stephen; Schwartzman, David
2013-01-01
Modelers of the long term carbon cycle in Earth history have previously assumed there is only one stable climatic steady state. Here we investigate the possibility of multiple steady states. We find them in Abiotic World, lacking any biotic influence, resulting from possible variations in planetary albedo in different temperature, atmospheric carbon dioxide level regimes, with the same weathering forcing balancing a volcanic source to the atmosphere, ocean pool. In Plant World modeling relevant to the Phanerozoic, we include the additional effects of biotic enhancement of weathering on land, organic carbon burial, oxidation of reduced organic carbon in terrestrial sediments and the variation of biotic productivity with temperature, finding a second stable steady state appearing between twenty and fifty degrees C. The very warm early Triassic climate may be the prime candidate for an upper temperature steady state. Given our results, the anthropogenic driven rise of atmospheric carbon dioxide could potentially...
Nonexistence of nonconstant steady-state solutions in a triangular cross-diffusion model
Lou, Yuan; Tao, Youshan; Winkler, Michael
2017-05-01
In this paper we study the Shigesada-Kawasaki-Teramoto model for two competing species with triangular cross-diffusion. We determine explicit parameter ranges within which the model exclusively possesses constant steady state solutions.
Lunin, Andrei; Grudiev, Alexej
2011-01-01
Analytical solutions are derived for transient and steady state gradient distributions in the travelling wave accelerating structures with arbitrary variation of parameters over the structure length. The results of both the unloaded and beam loaded cases are presented.
Steady State Condition in the Measurement of VO2and VCO2by Indirect Calorimetry.
Cadena, M; Sacristan, E; Infante, O; Escalante, B; Rodriguez, F
2005-01-01
Resting Metabolic Rate (RMR) is computed using VO2and VCO2short time 15-minute window measurement with Indirect Calorimetry (IC) instruments designed with mixing chamber. Steady state condition using a 10% variation coefficient criteria is the main objective to achieve metabolic long time prediction reliability. This study address how susceptible is the steady state VO2, VCO2measurement condition to the clino-orthostatic physiological maneuver. 30 young healthy subjects were analyzed. Only 18 passed the 10% variation coefficient inclusive criteria. They were exposed to 10 minutes clino-stage and 10 minutes orthostage. The hypothesis tests show not statistical significance (p< 0.1) in the average and variance analysis. It is concluded that the steady state is not influenced by the patient position IC test, probably because IC mixing chamber instruments are insensitive to detect a mayor physiological dynamics changes that can modify the steady state definition.
Absolute Steady-State Thermal Conductivity Measurements by Use of a Transient Hot-Wire System.
Roder, H M; Perkins, R A; Laesecke, A; Nieto de Castro, C A
2000-01-01
A transient hot-wire apparatus was used to measure the thermal conductivity of argon with both steady-state and transient methods. The effects of wire diameter, eccentricity of the wire in the cavity, axial conduction, and natural convection were accounted for in the analysis of the steady-state measurements. Based on measurements on argon, the relative uncertainty at the 95 % level of confidence of the new steady-state measurements is 2 % at low densities. Using the same hot wires, the relative uncertainty of the transient measurements is 1 % at the 95 % level of confidence. This is the first report of thermal conductivity measurements made by two different methods in the same apparatus. The steady-state method is shown to complement normal transient measurements at low densities, particularly for fluids where the thermophysical properties at low densities are not known with high accuracy.
A twin study of the trough plasma steady-state concentration of metformin
DEFF Research Database (Denmark)
Stage, Tore B; Damkier, Per; Pedersen, Rasmus S;
2015-01-01
OBJECTIVE: The aim of this study was to determine the intrapair similarity in trough steady-state plasma concentrations of metformin in monozygotic and dizygotic twin pairs. METHODS: We included 16 twin pairs (eight monozygotic and eight dizygotic twin pairs) for this study after contacting 524...... twin pairs. They were dosed with metformin to steady state (1 g twice daily) for 6 days and on day 7, the trough concentration of metformin was determined 12 h after the last dose. RESULTS: There was no strong intrapair similarity in trough steady-state plasma concentrations of metformin in either...... dizygotic or monozygotic twin pairs. CONCLUSION: The trough steady-state plasma concentration of metformin does not appear to be tightly genetically regulated. The interpretation of this finding is limited by the small sample size....
Kim, Jin Il; Song, Hyun-Seob; Sunkara, Sunil R; Lali, Arvind; Ramkrishna, Doraiswami
2012-01-01
We demonstrate strong experimental support for the cybernetic model based on maximizing carbon uptake rate in describing the microorganism's regulatory behavior by verifying exacting predictions of steady state multiplicity in a chemostat. Experiments with a feed mixture of glucose and pyruvate show multiple steady state behavior as predicted by the cybernetic model. When multiplicity occurs at a dilution (growth) rate, it results in hysteretic behavior following switches in dilution rate from above and below. This phenomenon is caused by transient paths leading to different steady states through dynamic maximization of the carbon uptake rate. Thus steady state multiplicity is a manifestation of the nonlinearity arising from cybernetic mechanisms rather than of the nonlinear kinetics. The predicted metabolic multiplicity would extend to intracellular states such as enzyme levels and fluxes to be verified in future experiments.
Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X
Energy Technology Data Exchange (ETDEWEB)
Bosch, H.-S. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Wolf, R. C. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Andreeva, T. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Cardella, A [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Erckmann, V. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Gantenbein, G [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Hathiramani, D [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Kasparek, W [Universitat Stuttgart, Institute fur Plasmaforschung, Germany; Klinger, T. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Koenig, R [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Kornejew, P [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Laqua, H P [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Lechte, C [Universitat Stuttgart, Institute fur Plasmaforschung, Germany; Michel, G [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Peacock, A. [Max-Planck-Institut fur Plasmaphysik, EURATOM Association, Garching, Germany; Sunn Pedersen, T [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Thumm, M [Karlsruhe Institute for Technology, IHM, EURATOM Association, Karlsruhe, Germany; Turkin, Yu. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Wegener, Lutz [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Werner, A. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Zhang, D [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Beidler, C. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Bozhenkov, S. [EURATOM-Association, Max Planck Institute of Plasma Physics, Greifswald, Germany; Brown, T. [Princeton Plasma Physics Laboratory (PPPL); Geiger, J. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Harris, Jeffrey H [ORNL; Heitzenroeder, P. [Princeton Plasma Physics Laboratory (PPPL); Lumsdaine, Arnold [ORNL; Maassberg, H. [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Marushchenko, N B [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Neilson, G. H. [Princeton Plasma Physics Laboratory (PPPL); Otte, M [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Rummel, Thomas [Max-Planck-Institute for Plasmaphysik, EURATOM-Association, Greifswald, Germany; Spong, Donald A [ORNL; Tretter, Jorg [Max Planck Institute for Plasma Physics, Garching, Germany
2013-01-01
The next step in the Wendelstein stellarator line is the large superconducting device Wendelstein 7-X, currently under construction in Greifswald, Germany. Steady-state operation is an intrinsic feature of stellarators, and one key element of the Wendelstein 7-X mission is to demonstrate steady-state operation under plasma conditions relevant for a fusion power plant. Steady-state operation of a fusion device, on the one hand, requires the implementation of special technologies, giving rise to technical challenges during the design, fabrication and assembly of such a device. On the other hand, also the physics development of steady-state operation at high plasma performance poses a challenge and careful preparation. The electron cyclotron resonance heating system, diagnostics, experiment control and data acquisition are prepared for plasma operation lasting 30 min. This requires many new technological approaches for plasma heating and diagnostics as well as new concepts for experiment control and data acquisition.
Steady state of active systems is characterized by unique effective temperature
Nandi, Saroj Kumar
2016-01-01
Understanding the properties of active matter systems, consisting of particles capable of taking up and dissipating energy and thus driven out of equilibrium, is important as it provides the possibility of a unified framework to analyze a diverse class of biological systems. Analysis of a large number of such systems shows an extension of equilibrium-like ideas are, sometimes, capable of capturing the steady state properties and a thermodynamic formulation of the problem might be possible. Investigating the detailed steady state properties and how the systems depart from equilibrium is important for such a formulation. Here we address the question through the framework of mode-coupling theory for dense active systems. We obtain a generic nonequilirbium theory for such systems and then taking the steady state limit of the theory we show that the system is characterized by a unique effective temperature, unlike other driven systems like a glass under shear. We discuss the differences of the steady states of an ...
ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.
This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo." The pattern evok...
A closed-loop control scheme for steering steady states of glycolysis and glycogenolysis pathway.
Panja, Surajit; Patra, Sourav; Mukherjee, Anirban; Basu, Madhumita; Sengupta, Sanghamitra; Dutta, Pranab K
2013-01-01
Biochemical networks normally operate in the neighborhood of one of its multiple steady states. It may reach from one steady state to other within a finite time span. In this paper, a closed-loop control scheme is proposed to steer states of the glycolysis and glycogenolysis (GG) pathway from one of its steady states to other. The GG pathway is modeled in the synergism and saturation system formalism, known as S-system. This S-system model is linearized into the controllable Brunovsky canonical form using a feedback linearization technique. For closed-loop control, the linear-quadratic regulator (LQR) and the linear-quadratic gaussian (LQG) regulator are invoked to design a controller for tracking prespecified steady states. In the feedback linearization technique, a global diffeomorphism function is proposed that facilitates in achieving the regulation requirement. The robustness of the regulated GG pathway is studied considering input perturbation and with measurement noise.
Optimization of steady-state ¹³C-labeling experiments for metabolic flux analysis.
Kruger, Nicholas J; Masakapalli, Shyam K; Ratcliffe, R George
2014-01-01
While steady-state (13)C metabolic flux analysis is a powerful method for deducing multiple fluxes in the central metabolic network of heterotrophic and mixotrophic plant tissues, it is also time-consuming and technically challenging. Key steps in the design and interpretation of steady-state (13)C labeling experiments are illustrated with a generic protocol based on applications to plant cell suspension cultures.
Zheng, Zhenzhen; Chou, Ching-Shan; Yi, Tau-Mu; Nie, Qing
2011-10-01
Cell polarization, in which substances previously uniformly distributed become asymmetric due to external or/and internal stimulation, is a fundamental process underlying cell mobility, cell division, and other polarized functions. The yeast cell S. cerevisiae has been a model system to study cell polarization. During mating, yeast cells sense shallow external spatial gradients and respond by creating steeper internal gradients of protein aligned with the external cue. The complex spatial dynamics during yeast mating polarization consists of positive feedback, degradation, global negative feedback control, and cooperative effects in protein synthesis. Understanding such complex regulations and interactions is critical to studying many important characteristics in cell polarization including signal amplification, tracking dynamic signals, and potential trade-off between achieving both objectives in a robust fashion. In this paper, we study some of these questions by analyzing several models with different spatial complexity: two compartments, three compartments, and continuum in space. The step-wise approach allows detailed characterization of properties of the steady state of the system, providing more insights for biological regulations during cell polarization. For cases without membrane diffusion, our study reveals that increasing the number of spatial compartments results in an increase in the number of steady-state solutions, in particular, the number of stable steady-state solutions, with the continuum models possessing infinitely many steady-state solutions. Through both analysis and simulations, we find that stronger positive feedback, reduced diffusion, and a shallower ligand gradient all result in more steady-state solutions, although most of these are not optimally aligned with the gradient. We explore in the different settings the relationship between the number of steady-state solutions and the extent and accuracy of the polarization. Taken together
Non equilibrium steady states: fluctuations and large deviations of the density and of the current
Derrida, B.
2007-01-01
These lecture notes give a short review of methods such as the matrix ansatz, the additivity principle or the macroscopic fluctuation theory, developed recently in the theory of non-equilibrium phenomena. They show how these methods allow to calculate the fluctuations and large deviations of the density and of the current in non-equilibrium steady states of systems like exclusion processes. The properties of these fluctuations and large deviation functions in non-equilibrium steady states (fo...
Steady-state entanglement of a Bose-Einstein condensate and a nanomechanical resonator
Asjad, Muhammad; 10.1103/PhysRevA.84.033606
2011-01-01
We analyze the steady-state entanglement between Bose-Einstein condensate trapped inside an optical cavity with a moving end mirror (nanomechanical resonator) driven by a single mode laser. The quantized laser field mediates the interaction between the Bose-Einstein condensate and nanomechanical resonator. In particular, we study the influence of temperature on the entanglement of the coupled system, and note that the steady-state entanglement is fragile with respect to temperature.
Rosenblatt, Marcus; Timmer, Jens; Kaschek, Daniel
2016-01-01
Ordinary differential equation models have become a wide-spread approach to analyze dynamical systems and understand underlying mechanisms. Model parameters are often unknown and have to be estimated from experimental data, e.g., by maximum-likelihood estimation. In particular, models of biological systems contain a large number of parameters. To reduce the dimensionality of the parameter space, steady-state information is incorporated in the parameter estimation process. For non-linear models, analytical steady-state calculation typically leads to higher-order polynomial equations for which no closed-form solutions can be obtained. This can be circumvented by solving the steady-state equations for kinetic parameters, which results in a linear equation system with comparatively simple solutions. At the same time multiplicity of steady-state solutions is avoided, which otherwise is problematic for optimization. When solved for kinetic parameters, however, steady-state constraints tend to become negative for particular model specifications, thus, generating new types of optimization problems. Here, we present an algorithm based on graph theory that derives non-negative, analytical steady-state expressions by stepwise removal of cyclic dependencies between dynamical variables. The algorithm avoids multiple steady-state solutions by construction. We show that our method is applicable to most common classes of biochemical reaction networks containing inhibition terms, mass-action and Hill-type kinetic equations. Comparing the performance of parameter estimation for different analytical and numerical methods of incorporating steady-state information, we show that our approach is especially well-tailored to guarantee a high success rate of optimization.
Steady-state existence of passive vector fields under the Kraichnan model.
Arponen, Heikki
2010-03-01
The steady-state existence problem for Kraichnan advected passive vector models is considered for isotropic and anisotropic initial values in arbitrary dimension. The models include the magnetohydrodynamic (MHD) equations, linear pressure model, and linearized Navier-Stokes (LNS) equations. In addition to reproducing the previously known results for the MHD model, we obtain the values of the Kraichnan model roughness parameter xi for which the LNS steady state exists.
Multiple steady states with distinct cellular metabolism in continuous culture of mammalian cells.
Europa, A F; Gambhir, A; Fu, P C; Hu, W S
2000-01-01
Mammalian cells have the ability to proliferate under different nutrient environments by utilizing different combinations of the nutrients, especially glucose and the amino acids. Under the conditions often used in in vitro cultivation, the cells consume glucose and amino acids in great excess of what is needed for making up biomass and products. They also produce large amounts of metabolites with lactate, ammonia, and some non-essential amino acids such as alanine as the most dominant ones. By controlling glucose and glutamine at low levels, cellular metabolism can be altered and can result in reduced glucose and glutamine consumption as well as in reduced metabolite formation. Using a fed-batch reactor to manipulate glucose at a low level (as compared to a typical batch culture), cell metabolism was altered to a state with substantially reduced lactate production. The culture was then switched to a continuous mode and allowed to reach a steady-state. At this steady-state, the concentrations of cells and antibody were substantially higher than a control culture that was initiated from a batch culture without first altering cellular metabolism. The lactate and other metabolite concentrations were also substantially reduced as compared to the control culture. This newly observed steady-state was achieved at the same dilution rate and feed medium as the control culture. The paths leading to the two steady-states, however, were different. These results demonstrate steady-state multiplicity. At this new steady-state, not only was glucose metabolism altered, but the metabolism of amino acids was altered as well. The amino acid metabolism in the new steady-state was more balanced, and the excretion of non-essential amino acids and ammonia was substantially lower. This approach of reaching a more desirable steady-state with higher concentrations of cells and product opens a new avenue for high-density- and high-productivity-cell culture.
Finite element modelling of creep process - steady state stresses and strains
Directory of Open Access Journals (Sweden)
Sedmak Aleksandar S.
2014-01-01
Full Text Available Finite element modelling of steady state creep process has been described. Using an analogy of visco-plastic problem with a described procedure, the finite element method has been used to calculate steady state stresses and strains in 2D problems. An example of application of such a procedure have been presented, using real life problem - cylindrical pipe with longitudinal crack at high temperature, under internal pressure, and estimating its residual life, based on the C*integral evaluation.
Institute of Scientific and Technical Information of China (English)
H. Tamai; Y. Kamada; A. Sakasai; S. Ishida; G. Kurita; M. Matsukawa; K. Urata; S. Sakurai; K. Tsuchiya; A. Morioka; Y. M. Miura; K. Kizu
2004-01-01
Plasma control on high-βN steady-state operation for JT-60 superconducting modification is discussed. Accessibility to high-βN exceeding the free-boundary limit is investigated with the stabilising wall of reduced-activated ferritic steel and the active feedback control of the in-vessel non-axisymmetric field coils. Taking the merit of superconducting magnet, advanced plasma control for steady-state high performance operation could be expected.
Low, Dennis J.; Goode, Daniel J.; Risser, Dennis W.
2000-01-01
to water can range from flowing at land surface to more than 71 feet below land surface. Potentiometric maps based on measured water levels at the Gettysburg Elevator Plant indicate ground water flows from west to east, towards Rock Creek. Multiple-well aquifer tests indicate the system is heterogeneous and flow is primarily in dipping beds that contain discrete secondary openings separated by less permeable beds. Water levels in wells open to the pumped bed, as projected along the dipping stratigraphy, are drawn down more than water levels in wells not open to the pumped bed. Ground-water flow was simulated for steady-state conditions prior to pumping and long-term average pumping conditions. The three-dimensional numerical flow model (MODFLOW) was calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. An effective areal recharge rate of 7 inches was used in model calibration. The calibrated flow model was used to evaluate the effectiveness of the current onsite and offsite extraction well system. The simulation results generally indicate that the extraction system effectively captures much of the ground-water recharge at the Gettysburg Elevator Plant and, hence, contaminated ground-water migrating from the site. Some of the extraction wells pump at low rates and have very small contributing areas. Results indicate some areal recharge onsite will move to offsite extraction wells.
Steady state effects in a two-pulse diffusion-weighted sequence
Energy Technology Data Exchange (ETDEWEB)
Zubkov, Mikhail; Stait-Gardner, Timothy; Price, William S. [Nanoscale Organisation and Dynamics Group, School of Science and Health, University of Western Sydney, Sydney (Australia); Stilbs, Peter [Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm (Sweden)
2015-04-21
In conventional nuclear magnetic resonance (NMR) diffusion measurements a significant amount of experimental time is used up by magnetization recovery, serving to prevent the formation of the steady state, as in the latter case the manifestation of diffusion is modulated by multiple applications of the pulse sequence and conventional diffusion coefficient inference procedures are generally not applicable. Here, an analytical expression for diffusion-related effects in a two-pulse NMR experiment (e.g., pulsed-gradient spin echo) in the steady state mode (with repetition times less than the longitudinal relaxation time of the sample) is derived by employing a Fourier series expansion within the solution of the Bloch-Torrey equations. Considerations are given for the transition conditions between the full relaxation and the steady state experiment description. The diffusion coefficient of a polymer solution (polyethylene glycol) is measured by a two-pulse sequence in the full relaxation mode and for a range of repetition times, approaching the rapid steady state experiment. The precision of the fitting employing the presented steady state solution by far exceeds that of the conventional fitting. Additionally, numerical simulations are performed yielding results strongly supporting the proposed description of the NMR diffusion measurements in the steady state.
Steady State Analysis of Convex Combination of Affine Projection Adaptive Filters
Directory of Open Access Journals (Sweden)
S. Radhika
2015-05-01
Full Text Available The aim of the study is to propose an adaptive algorithm using convex combinational approach to have both fast convergence and less steady state error simultaneously. For this purpose, we have used two affine projection adaptive filters with complementary nature (both in step size and projection order as the component filters. The first component filter has high projection order and large step size which makes it to have fast convergence at the cost of more steady state error. The second component filter has slow convergence and less steady state error due to the selection of small step size and projection order. Both are combined using convex combiner so as to have best final output with fast convergence and less steady state error. Each of the component filters are updated using their own error signals and stochastic gradient approach is used to update the convex combiner so as to have minimum overall error. By using energy conservation argument, analytical treatment of the combination stage is made in stationary environment. It is found that during initial stage the proposed scheme converges to the fast filter which has good convergence later it converges to either of the two (whichever has less steady state error and towards the end, the final output converges to slow filter which is superior in lesser steady state error. Experimental results proved that the proposed algorithm has adopted the best features of the component filters.
On multiple alternating steady states induced by periodic spin phase perturbation waveforms.
Buračas, Giedrius T; Jung, Youngkyoo; Lee, Jongho; Buxton, Richard B; Wong, Eric C; Liu, Thomas T
2012-05-01
Direct measurement of neural currents by means of MRI can potentially open a high temporal resolution (10-100 ms) window applicable for monitoring dynamics of neuronal activity without loss of the high spatial resolution afforded by MRI. Previously, we have shown that the alternating balanced steady state imaging affords high sensitivity to weak periodic currents owing to its amplification of periodic spin phase perturbations. This technique, however, requires precise synchronization of such perturbations to the radiofrequency pulses. Herein, we extend alternating balanced steady state imaging to multiple balanced alternating steady states for estimation of neural current waveforms. Simulations and phantom experiments show that the off-resonance profile of the multiple alternating steady state signal carries information about the frequency content of driving waveforms. In addition, the method is less sensitive than alternating balanced steady state to precise waveform timing relative to radiofrequency pulses. Thus, multiple alternating steady state technique is potentially applicable to MR imaging of the waveforms of periodic neuronal activity.
Lei, Frede; Olsson, Lisbeth; Jørgensen, Sten Bay
2003-06-30
The steady-state behavior of a glucose-limited, aerobic, continuous cultivation of Saccharomyces cerevisiae CEN.PK113-7D was investigated around the critical dilution rate. Oxido-reductive steady states were obtained at dilution rates up to 0.09 h(-1) lower than the critical dilution rate by operating the bioreactor as a productostat, where the dilution rate was controlled on the basis of an ethanol measurement. Thus, the experimental investigations revealed that multiple steady states exist in a region of dilution rates below the critical dilution rate. The existence of multiple steady states was attributed to two distinct physiological effects occurring when growth changed from oxidative to oxido-reductive: (i) a decrease in the efficiency of ATP production and utilization (at ethanol concentrations below 3 g/L) and (ii) repression of the oxidative metabolism (at higher ethanol concentrations). The first effect was best observed at low ethanol concentrations, where multiple steady states were observed even when no repression of the oxidative metabolism was evident, i.e., the oxidative capacity was constant. However, at higher ethanol concentrations repression of the oxidative metabolism was observed (the oxidative capacity decreased), and this resulted in a broader range of dilution rates where multiple steady states could be found.
Bacteriophages as surface and ground water tracers
Directory of Open Access Journals (Sweden)
P. Rossi
1998-01-01
Full Text Available Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra. In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.
Bacteriophages as surface and ground water tracers
Rossi, P.; Dörfliger, N.; Kennedy, K.; Müller, I.; Aragno, M.
Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra). In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.
Ground-water models: Validate or invalidate
Bredehoeft, J.D.; Konikow, L.F.
1993-01-01
The word validation has a clear meaning to both the scientific community and the general public. Within the scientific community the validation of scientific theory has been the subject of philosophical debate. The philosopher of science, Karl Popper, argued that scientific theory cannot be validated, only invalidated. Popper’s view is not the only opinion in this debate; however, many scientists today agree with Popper (including the authors). To the general public, proclaiming that a ground-water model is validated carries with it an aura of correctness that we do not believe many of us who model would claim. We can place all the caveats we wish, but the public has its own understanding of what the word implies. Using the word valid with respect to models misleads the public; verification carries with it similar connotations as far as the public is concerned. Our point is this: using the terms validation and verification are misleading, at best. These terms should be abandoned by the ground-water community.
Two Dimensional Plasmonic Cavities on Moire Surfaces
Balci, Sinan; Kocabas, Askin; Karabiyik, Mustafa; Kocabas, Coskun; Aydinli, Atilla
2010-03-01
We investigate surface plasmon polariton (SPP) cavitiy modes on two dimensional Moire surfaces in the visible spectrum. Two dimensional hexagonal Moire surface can be recorded on a photoresist layer using Interference lithography (IL). Two sequential exposures at slightly different angles in IL generate one dimensional Moire surfaces. Further sequential exposure for the same sample at slightly different angles after turning the sample 60 degrees around its own axis generates two dimensional hexagonal Moire cavity. Spectroscopic reflection measurements have shown plasmonic band gaps and cavity states at all the azimuthal angles (omnidirectional cavity and band gap formation) investigated. The plasmonic band gap edge and the cavity states energies show six fold symmetry on the two dimensional Moire surface as measured in reflection measurements.
Two-dimensional function photonic crystals
Liu, Xiao-Jing; Liang, Yu; Ma, Ji; Zhang, Si-Qi; Li, Hong; Wu, Xiang-Yao; Wu, Yi-Heng
2017-01-01
In this paper, we have studied two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , that can become true easily by electro-optical effect and optical kerr effect. We calculated the band gap structures of TE and TM waves, and found the TE (TM) wave band gaps of function photonic crystals are wider (narrower) than the conventional photonic crystals. For the two-dimensional function photonic crystals, when the dielectric constant functions change, the band gaps numbers, width and position should be changed, and the band gap structures of two-dimensional function photonic crystals can be adjusted flexibly, the needed band gap structures can be designed by the two-dimensional function photonic crystals, and it can be of help to design optical devices.
Two-Dimensional Planetary Surface Lander
Hemmati, H.; Sengupta, A.; Castillo, J.; McElrath, T.; Roberts, T.; Willis, P.
2014-06-01
A systems engineering study was conducted to leverage a new two-dimensional (2D) lander concept with a low per unit cost to enable scientific study at multiple locations with a single entry system as the delivery vehicle.
Positive Steady States of a Prey-predator Model with Diffusion and Non-monotone Conversion Rate
Institute of Scientific and Technical Information of China (English)
Rui PENG; Ming Xin WANG; Wen Yan CHEN
2007-01-01
In this paper,we study the positive steady states of a prey-predator model with di .usion throughout and a non-monotone conversion rate under the homogeneous Dirichlet boundary condition. We obtain some results of the existence and non-existence of positive steady states.The stability and uniqueness of positive steady states are also discussed.
Kosman, Daniel J.
2009-01-01
The steady-state is a fundamental aspect of biochemical pathways in cells; indeed, the concept of steady-state is a definition of life itself. In a simple enzyme kinetic scheme, the steady-state condition is easy to define analytically but experimentally often difficult to capture because of its evanescent quality; the initial, constant velocity…
Modeling analysis of ground water recharge potential on alluvial fans using limited data.
Munévar, A; Mariño, M A
1999-01-01
A modeling approach is developed to evaluate the potential for artificial recharge on alluvial fans in the Salinas Valley, California, using limited data of soil texture, soil hydraulic properties, and interwell stratigraphy. Promising areas for surface recharge are identified and mapped on a broad-scale using soil surveys, geologic investigations, permeability tests, and seasonal ground water response to rainfall and runoff. Two-dimensional representations of the vadose zone at selected sites are then constructed from drillers'logs and soil material types are estimated. Next, hydraulic properties are assigned to each soil material type by comparing them to laboratory-tested cores of similar soils taken from one site. Finally, water flow through the vadose zone is modeled in two dimensions at seven sites using a transient, finite-difference, variably saturated flow model. Average infiltration rates range from 0.84 to 1.54 cm/hr and recharge efficiency, the percentage of infiltrated water that reaches the water table, varies from 51% to 79%. Infiltration rates and recharge efficiency are found to be relatively insensitive to recharge basin ponding depth due to the thickness of the vadose zones modeled (31 to 84 m). The impact of artificial recharge on the Salinas Valley ground water basin is investigated by simulating the regional ground water response to surface spreading and streamflow augmentation with a recently calibrated, finite-element, ground water-surface water model for the basin. It was determined that a combined approach of surface recharge and streamflow augmentation significantly reduces the state of ground water overdraft and, to a lesser extent, reduces the rate of sea water intrusion.
Steady state, erosional continuity, and the topography of landscapes developed in layered rocks
Perne, Matija; Covington, Matthew D.; Thaler, Evan A.; Myre, Joseph M.
2017-01-01
The concept of topographic steady state has substantially informed our understanding of the relationships between landscapes, tectonics, climate, and lithology. In topographic steady state, erosion rates are equal everywhere, and steepness adjusts to enable equal erosion rates in rocks of different strengths. This conceptual model makes an implicit assumption of vertical contacts between different rock types. Here we hypothesize that landscapes in layered rocks will be driven toward a state of erosional continuity, where retreat rates on either side of a contact are equal in a direction parallel to the contact rather than in the vertical direction. For vertical contacts, erosional continuity is the same as topographic steady state, whereas for horizontal contacts it is equivalent to equal rates of horizontal retreat on either side of a rock contact. Using analytical solutions and numerical simulations, we show that erosional continuity predicts the form of flux steady-state landscapes that develop in simulations with horizontally layered rocks. For stream power erosion, the nature of continuity steady state depends on the exponent, n, in the erosion model. For n = 1, the landscape cannot maintain continuity. For cases where n ≠ 1, continuity is maintained, and steepness is a function of erodibility that is predicted by the theory. The landscape in continuity steady state can be quite different from that predicted by topographic steady state. For n < 1 continuity predicts that channels incising subhorizontal layers will be steeper in the weaker rock layers. For subhorizontal layered rocks with different erodibilities, continuity also predicts larger slope contrasts than in topographic steady state. Therefore, the relationship between steepness and erodibility within a sequence of layered rocks is a function of contact dip. For the subhorizontal limit, the history of layers exposed at base level also influences the steepness-erodibility relationship. If uplift rate
2014-01-01
Background A key problem in the analysis of mathematical models of molecular networks is the determination of their steady states. The present paper addresses this problem for Boolean network models, an increasingly popular modeling paradigm for networks lacking detailed kinetic information. For small models, the problem can be solved by exhaustive enumeration of all state transitions. But for larger models this is not feasible, since the size of the phase space grows exponentially with the dimension of the network. The dimension of published models is growing to over 100, so that efficient methods for steady state determination are essential. Several methods have been proposed for large networks, some of them heuristic. While these methods represent a substantial improvement in scalability over exhaustive enumeration, the problem for large networks is still unsolved in general. Results This paper presents an algorithm that consists of two main parts. The first is a graph theoretic reduction of the wiring diagram of the network, while preserving all information about steady states. The second part formulates the determination of all steady states of a Boolean network as a problem of finding all solutions to a system of polynomial equations over the finite number system with two elements. This problem can be solved with existing computer algebra software. This algorithm compares favorably with several existing algorithms for steady state determination. One advantage is that it is not heuristic or reliant on sampling, but rather determines algorithmically and exactly all steady states of a Boolean network. The code for the algorithm, as well as the test suite of benchmark networks, is available upon request from the corresponding author. Conclusions The algorithm presented in this paper reliably determines all steady states of sparse Boolean networks with up to 1000 nodes. The algorithm is effective at analyzing virtually all published models even those of moderate
Veliz-Cuba, Alan; Aguilar, Boris; Hinkelmann, Franziska; Laubenbacher, Reinhard
2014-06-26
A key problem in the analysis of mathematical models of molecular networks is the determination of their steady states. The present paper addresses this problem for Boolean network models, an increasingly popular modeling paradigm for networks lacking detailed kinetic information. For small models, the problem can be solved by exhaustive enumeration of all state transitions. But for larger models this is not feasible, since the size of the phase space grows exponentially with the dimension of the network. The dimension of published models is growing to over 100, so that efficient methods for steady state determination are essential. Several methods have been proposed for large networks, some of them heuristic. While these methods represent a substantial improvement in scalability over exhaustive enumeration, the problem for large networks is still unsolved in general. This paper presents an algorithm that consists of two main parts. The first is a graph theoretic reduction of the wiring diagram of the network, while preserving all information about steady states. The second part formulates the determination of all steady states of a Boolean network as a problem of finding all solutions to a system of polynomial equations over the finite number system with two elements. This problem can be solved with existing computer algebra software. This algorithm compares favorably with several existing algorithms for steady state determination. One advantage is that it is not heuristic or reliant on sampling, but rather determines algorithmically and exactly all steady states of a Boolean network. The code for the algorithm, as well as the test suite of benchmark networks, is available upon request from the corresponding author. The algorithm presented in this paper reliably determines all steady states of sparse Boolean networks with up to 1000 nodes. The algorithm is effective at analyzing virtually all published models even those of moderate connectivity. The problem for
CHEMICAL QUALITY CHARACTERISTICS OF TEHRAN GROUND WATER
Directory of Open Access Journals (Sweden)
K. Imandel
1994-06-01
Full Text Available For better understanding of Tehran ground water, samples were taken randomly from 340 out of 655 deep & semi deep wells in 1993, which dug by Tehran Water Supply and Sewage Engineering Company. 260 Water specimens were examined chemically and physically and compared with the 1993 World Health Organization (WHO and Food and Agriculture Organization (FAO criteria and analyzed statistically. Logarithmic diagram of arithmetic mean of 53 deep wells which are now connected to Tehran water supply system showed Sodium- Sulphate category. Main chemical components of water are closely adjusted to the international standards and no overdoses were observed in any cases. Logarithmic diagram of arithmetic mean of 72 deep wells, which were rsed for the Tehran’s orbital town's drinking water, showed that chemical components of the water were Calcic-Chloride category and there were not observed any increases within the other compounds.
Animating ground water levels with Excel.
Shikaze, Steven G; Crowe, Allan S
2003-01-01
This note describes the use of Microsoft Excel macros (programs written in Excel's internal language, Visual Basic for Applications) to create simple onscreen animations of transient ground water data within Excel. Compared to many specialized visualization software packages, the use of Excel macros is much cheaper, much simpler, and can rapidly be learned. The Excel macro can also be used to create individual GIF files for each animation frame. This series of frames can then be used to create an AVI video file using any of a number of graphics packages, such as Corel PhotoPaint. The technique is demonstrated through a macro that animates changes in the elevation of a water table along a transect over several years.
Warner, James W.
1979-01-01
Diisopropylmethylphosphonate (DIMP) is an organic compound produced as a by-product of the manufacture and detoxification of GB nerve gas. Ground-water contamination by DIMP from the disposal of wastes into unlined surface ponds at the Rocky Mountain Arsenal occurred from 1952 to 1956. A digital-transport model was used to determine the effects on ground-water movement and on DIMP concentrations in the ground water of a bentonite barrier in the aquifer near the northern boundary of the arsenal. The transport model is based on an iterative-alternating-direction-implicit mathematical solution of the ground-water-flow equation coupled with a method-of-characteristics solution of the solute-transport equation. The model assumes conservative (nonreactive) transient transport of DIMP and steady-state ground-water flow. In the model simulations, a bentonite barrier was assumed that was impermeable and penetrated the entire saturated thickness of the aquifer. Ground water intercepted by the barrier was assumed to be pumped by wells located south (upgradient) of the barrier, to be treated to remove DIMP, and to be recharged by pits or wells to the aquifer north (downgradient) of the barrier. The amount of DIMP transported across the northern boundary of the arsenal was substantially reduced by a ground-water-barrier system of this type. For a 1,500-foot-long bentonite barrier located along the northern boundary of the arsenal near D Street, about 50 percent of the DIMP that would otherwise cross the boundary would be intercepted by the barrier. This barrier configuration and location were proposed by the U.S. Army. Of the ground water with DIMP concentrations greater than 500 micrograms per liter, the safe DIMP-concentration level determined by the U.S. Army, about 72 percent would be intercepted by the barrier system. The amount of DIMP underflow intercepted may be increased to 65 percent by doubling the pumpage, or to 73 percent by doubling the length of the barrier
Gedeon, M.; Mallants, D.
2012-04-01
Radionuclide concentration predictions in aquifers play an important role in estimating impact of planned surface disposal of radioactive waste in Belgium, developed by the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF), who also coordinates and leads the corresponding research. Long-term concentration predictions are based on a steady-state flow solution obtained by a cascade of multi-scale models from the catchment to the detailed (site) scale performed in MODFLOW. To test the concept and accuracy of the groundwater flow solution and conservativeness of the concentration predictions obtained therewith, a transient model, considered more realistic, was set up in a sub-domain of the intermediate scale steady-state model. Besides the modelling domain reduction, the transient model was and exact copy of the steady-state model, having the infiltration as the only time-varying parameter. The transient model was run for a twenty-year period, whereas the results were compared to the steady-state results based on infiltration value and observations averaged over the same period. The comparison of the steady-state and transient flow solutions includes the analyses of the goodness of fit, the parameter sensitivities, relative importance of the individual observations and one-percent sensitivity maps. The steady-state and transient flow solutions were subsequently translated into a site-scale transport model, used to predict the radionuclide concentrations in a hypothetical well in the aquifers. The translation of the flow solutions between the models of distinct scales was performed using the Local grid refinement method available in MODFLOW. In the site-scale models, MT3DMS transport simulations were performed to obtain respective concentration predictions in a hypothetical well, situated at 70 meters from the disposal tumuli. The equilibrium concentrations based on a constant source flux achieved using a steady-state solution were then
Archelas, Alain; Zhao, Wei; Faure, Bruno; Iacazio, Gilles; Kotik, Michael
2016-02-01
A detailed kinetic study based on steady-state and pre-steady-state measurements is described for the highly enantioselective epoxide hydrolase Kau2. The enzyme, which is a member of the α/β-hydrolase fold family, preferentially reacts with the (S,S)-enantiomer of trans-stilbene oxide (TSO) with an E value of ∼200. The enzyme follows a classical two-step catalytic mechanism with formation of an alkyl-enzyme intermediate in the first step and hydrolysis of this intermediate in a rate-limiting second step. Tryptophan fluorescence quenching during TSO conversion appears to correlate with alkylation of the enzyme. The steady-state data are consistent with (S,S) and (R,R)-TSO being two competing substrates with marked differences in k(cat) and K(M) values. The high enantiopreference of the epoxide hydrolase is best explained by pronounced differences in the second-order alkylation rate constant (k2/K(S)) and the alkyl-enzyme hydrolysis rate k3 between the (S,S) and (R,R)-enantiomers of TSO. Our data suggest that during conversion of (S,S)-TSO the two active site tyrosines, Tyr(157) and Tyr(259), serve mainly as electrophilic catalysts in the alkylation half-reaction, polarizing the oxirane oxygen of the bound epoxide through hydrogen bond formation, however, without fully donating their hydrogens to the forming alkyl-enzyme intermediate.
Interpolation by two-dimensional cubic convolution
Shi, Jiazheng; Reichenbach, Stephen E.
2003-08-01
This paper presents results of image interpolation with an improved method for two-dimensional cubic convolution. Convolution with a piecewise cubic is one of the most popular methods for image reconstruction, but the traditional approach uses a separable two-dimensional convolution kernel that is based on a one-dimensional derivation. The traditional, separable method is sub-optimal for the usual case of non-separable images. The improved method in this paper implements the most general non-separable, two-dimensional, piecewise-cubic interpolator with constraints for symmetry, continuity, and smoothness. The improved method of two-dimensional cubic convolution has three parameters that can be tuned to yield maximal fidelity for specific scene ensembles characterized by autocorrelation or power-spectrum. This paper illustrates examples for several scene models (a circular disk of parametric size, a square pulse with parametric rotation, and a Markov random field with parametric spatial detail) and actual images -- presenting the optimal parameters and the resulting fidelity for each model. In these examples, improved two-dimensional cubic convolution is superior to several other popular small-kernel interpolation methods.
Foster, Carl; Farland, Courtney V.; Guidotti, Flavia; Harbin, Michelle; Roberts, Brianna; Schuette, Jeff; Tuuri, Andrew; Doberstein, Scott T.; Porcari, John P.
2015-01-01
High intensity interval training (HIIT) has become an increasingly popular form of exercise due to its potentially large effects on exercise capacity and small time requirement. This study compared the effects of two HIIT protocols vs steady-state training on aerobic and anaerobic capacity following 8-weeks of training. Fifty-five untrained college-aged subjects were randomly assigned to three training groups (3x weekly). Steady-state (n = 19) exercised (cycle ergometer) 20 minutes at 90% of ventilatory threshold (VT). Tabata (n = 21) completed eight intervals of 20s at 170% VO2max/10s rest. Meyer (n = 15) completed 13 sets of 30s (20 min) @ 100% PVO2 max/ 60s recovery, average PO = 90% VT. Each subject did 24 training sessions during 8 weeks. Results: There were significant (p HIIT protocols are time efficient, they are not superior to conventional exercise training in sedentary young adults. Key points Steady state training equivalent to HIIT in untrained students Mild interval training presents very similar physiologic challenge compared to steady state training HIIT (particularly very high intensity variants were less enjoyable than steady state or mild interval training Enjoyment of training decreases across the course of an 8 week experimental training program PMID:26664271
Foster, Carl; Farland, Courtney V; Guidotti, Flavia; Harbin, Michelle; Roberts, Brianna; Schuette, Jeff; Tuuri, Andrew; Doberstein, Scott T; Porcari, John P
2015-12-01
High intensity interval training (HIIT) has become an increasingly popular form of exercise due to its potentially large effects on exercise capacity and small time requirement. This study compared the effects of two HIIT protocols vs steady-state training on aerobic and anaerobic capacity following 8-weeks of training. Fifty-five untrained college-aged subjects were randomly assigned to three training groups (3x weekly). Steady-state (n = 19) exercised (cycle ergometer) 20 minutes at 90% of ventilatory threshold (VT). Tabata (n = 21) completed eight intervals of 20s at 170% VO2max/10s rest. Meyer (n = 15) completed 13 sets of 30s (20 min) @ 100% PVO2 max/ 60s recovery, average PO = 90% VT. Each subject did 24 training sessions during 8 weeks. There were significant (p training group, as well as significant increases in peak (+8, + 9 and +5%) & mean (+4, +7 and +6%) power during Wingate testing, but no significant differences between groups. Measures of the enjoyment of the training program indicated that the Tabata protocol was significantly less enjoyable (p training in sedentary young adults. Key pointsSteady state training equivalent to HIIT in untrained studentsMild interval training presents very similar physiologic challenge compared to steady state trainingHIIT (particularly very high intensity variants were less enjoyable than steady state or mild interval trainingEnjoyment of training decreases across the course of an 8 week experimental training program.
Diehl, S; Zambrano, J; Carlsson, B
2016-01-01
A reduced model of a completely stirred-tank bioreactor coupled to a settling tank with recycle is analyzed in its steady states. In the reactor, the concentrations of one dominant particulate biomass and one soluble substrate component are modelled. While the biomass decay rate is assumed to be constant, growth kinetics can depend on both substrate and biomass concentrations, and optionally model substrate inhibition. Compressive and hindered settling phenomena are included using the Bürger-Diehl settler model, which consists of a partial differential equation. Steady-state solutions of this partial differential equation are obtained from an ordinary differential equation, making steady-state analysis of the entire plant difficult. A key result showing that the ordinary differential equation can be replaced with an approximate algebraic equation simplifies model analysis. This algebraic equation takes the location of the sludge-blanket during normal operation into account, allowing for the limiting flux capacity caused by compressive settling to easily be included in the steady-state mass balance equations for the entire plant system. This novel approach grants the possibility of more realistic solutions than other previously published reduced models, comprised of yet simpler settler assumptions. The steady-state concentrations, solids residence time, and the wastage flow ratio are functions of the recycle ratio. Solutions are shown for various growth kinetics; with different values of biomass decay rate, influent volumetric flow, and substrate concentration.
Halász, Adám M; Lai, Hong-Jian; McCabe Pryor, Meghan; Radhakrishnan, Krishnan; Edwards, Jeremy S
2013-01-01
True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady-state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here, we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher-dimensional space. We show that the linearized version of the steady-state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1.
Matlock, D.T.
1981-01-01
Simulative ground-water flow models for Vekol Valley, the Waterman Wash area, and the Bosque area were developed for use in evaluating alternatives for developing a ground-water supply for the Ak-Chin Indian Community. The hydraulic properties of the basin-fill deposits used in the models were estimated primarily from aquifer tests made by the U.S. Geological Survey. Annual recharge to Vekol Valley and the Waterman Wash area is negligible in comparison to the quantity of water in storage and the quantity proposed to be pumped. The models are based on a three-dimensional, block-centered, finite-difference scheme. The Vekol Valley model was calibrated for steady-state onditions, and the Waterman Wash area model was calibrated for steady-state and transient conditions. The sensitivity of calibrated heads to changes in transmissivity was also investigated. An uncalibrated storage-depletion model was developed for the Bosque area. Simulated water levels for steady-state conditions average within 5 feet of measured values for Vekoi Valley and within 6 feet for the Waterman Wash area. Simulated water levels for transient conditions in the Waterman Wash area average within 8 feet of measured values for 15 years of analysis and within 15 feet for 24 years. Water-level declines simulated by the Waterman Wash area model average within 17 feet of those measured during the 24-year period, 1951-75.
TWO-DIMENSIONAL TOPOLOGY OF COSMOLOGICAL REIONIZATION
Energy Technology Data Exchange (ETDEWEB)
Wang, Yougang; Xu, Yidong; Chen, Xuelei [Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 China (China); Park, Changbom [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); Kim, Juhan, E-mail: wangyg@bao.ac.cn, E-mail: cbp@kias.re.kr [Center for Advanced Computation, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)
2015-11-20
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two-dimensional genus curve for the early, middle, and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometre Array.
Two dimensional topology of cosmological reionization
Wang, Yougang; Xu, Yidong; Chen, Xuelei; Kim, Juhan
2015-01-01
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two dimensional genus curve for the early, middle and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometer Array.
Two-dimensional x-ray diffraction
He, Bob B
2009-01-01
Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea
Matching Two-dimensional Gel Electrophoresis' Spots
DEFF Research Database (Denmark)
Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza
2012-01-01
This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar......This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches...
Mobility anisotropy of two-dimensional semiconductors
Lang, Haifeng; Zhang, Shuqing; Liu, Zhirong
2016-12-01
The carrier mobility of anisotropic two-dimensional semiconductors under longitudinal acoustic phonon scattering was theoretically studied using deformation potential theory. Based on the Boltzmann equation with the relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was derived, showing that the influence of effective mass on mobility anisotropy is larger than those of deformation potential constant or elastic modulus. Parameters were collected for various anisotropic two-dimensional materials (black phosphorus, Hittorf's phosphorus, BC2N , MXene, TiS3, and GeCH3) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio is overestimated by the previously described method.
Towards two-dimensional search engines
Ermann, Leonardo; Chepelianskii, Alexei D.; Shepelyansky, Dima L.
2011-01-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Statistical properties of inf...
Time Reversibility, Correlation Decay and the Steady State Fluctuation Relation for Dissipation
Directory of Open Access Journals (Sweden)
Denis J. Evans
2013-04-01
Full Text Available Steady state fluctuation relations for nonequilibrium systems are under intense investigation because of their important practical implications in nanotechnology and biology. However the precise conditions under which they hold need clarification. Using the dissipation function, which is related to the entropy production of linear irreversible thermodynamics, we show time reversibility, ergodic consistency and a recently introduced form of correlation decay, called T-mixing, are sufficient conditions for steady state fluctuation relations to hold. Our results are not restricted to a particular model and show that the steady state fluctuation relation for the dissipation function holds near or far from equilibrium subject to these conditions. The dissipation function thus plays a comparable role in nonequilibrium systems to thermodynamic potentials in equilibrium systems.
Steady-state pharmacokinetics of metformin is independent of the OCT1 genotype in healthy volunteers
DEFF Research Database (Denmark)
Christensen, Mette Marie Hougaard; Højlund, Kurt; Hother-Nielsen, Ole
2015-01-01
PURPOSE: The aim of the study was to determine the steady-state pharmacokinetics of metformin in healthy volunteers with different numbers of reduced-function alleles in the organic cation transporter 1 gene (OCT1). METHODS: The study was conducted as part of a randomized cross-over trial. Thirty......-four healthy volunteers with known OCT1 genotypes (12 with two wild-type alleles, 13 with one and 9 with two reduced-function alleles) were included. In one of the study periods, they were titrated to steady-state with 1 g metformin twice daily. RESULTS: Neither AUC(0-12), C(max) nor Cl(renal) were...... volunteers, we found no impact of different OCT1 genotypes on metformin steady-state pharmacokinetics....
Steady-state evaporator models of Solar Sea Power Plants. Part I
Energy Technology Data Exchange (ETDEWEB)
Hetyei, S. A.; Neuman, C. P.
1976-08-01
Previously, a methodology was developed for modeling the dynamic and steady-state behavior of Solar Sea Power Plants (SSPP). Here, the pertinent physical laws of heat transfer and mass balance are applied to develop a lumped parameter, steady-state model for tube-and-shell evaporators incorporating falling films. This model is analyzed to investigate the assumption of constant heat transfer coefficients in modeling the steady-state behavior of smooth-tube evaporators operated in the turbulent flow regime. It is concluded that, for all practical purposes, the local heat transfer coefficient on the working fluid side of the evaporator tube is constant for both fixed and +-10% changes in the inlet working fluid flow rate. The overall objective is to develop simulation models of a complete SSPP as tools of design and optimization.
Current Control in ITER Steady State Plasmas With Neutral Beam Steering
Energy Technology Data Exchange (ETDEWEB)
R.V. Budny
2009-09-10
Predictions of quasi steady state DT plasmas in ITER are generated using the PTRANSP code. The plasma temperatures, densities, boundary shape, and total current (9 - 10 MA) anticipated for ITER steady state plasmas are specified. Current drive by negative ion neutral beam injection, lower-hybrid, and electron cyclotron resonance are calculated. Four modes of operation with different combinations of current drive are studied. For each mode, scans with the NNBI aimed at differing heights in the plasma are performed to study effects of current control on the q profile. The timeevolution of the currents and q are calculated to evaluate long duration transients. Quasi steady state, strongly reversed q profiles are predicted for some beam injection angles if the current drive and bootstrap currents are sufficiently large.
Mu, Baojie; Li, Yaoyu; Seem, John E.
2016-08-01
A major class of extremum seeking control (ESC) is based on the use of periodic dither perturbation of plant input for extracting the gradient information. Presence of the dither input into the steady state operation is undesirable in practice due to the possible excessive wear of actuators. It is thus beneficial to stop the dithering action after the ESC reaches its steady state. In this paper, we propose a method for automatically discriminating between the steady state and the transient state modes of extremum seeking control process using the sinusoidal detection techniques. Some design guidelines are proposed for the parameter selection of the relevant sinusoidal detection scheme. The proposed scheme is validated with simulation study on dynamic virtual plant of two building HVAC systems.
DEFF Research Database (Denmark)
Gastrup, Sandra; Stage, Tore Bjerregaard; Fruekilde, Palle Bach Nielsen
2016-01-01
AIM: Patients receiving lamotrigine therapy frequently use paracetamol concomitantly. While one study suggests a possible, clinically relevant drug-drug interaction, practical recommendations of the concomitant use are inconsistent. We performed a systematic pharmacokinetic study in healthy...... volunteers to quantify the effect of 4-day treatment of paracetamol on the metabolism of steady-state lamotrigine. METHODS: Twelve healthy, male volunteers participated in an open-label, sequential interaction study. Lamotrigine was titrated to steady state (100 mg daily) over 36 days, and blood and urine...... sampling was performed in a non-randomised order with and without paracetamol (1 g four times daily). The primary endpoint was change in steady-state area under the plasma concentration-time curve of lamotrigine. Secondary endpoints were changes in total apparent oral clearance, renal clearance...
Breakdown of the resistor-network model for steady-state hopping conduction
Energy Technology Data Exchange (ETDEWEB)
Emin, D. [Sandia National Labs., Albuquerque, NM (United States); Kuper, C.G. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Physics
1996-05-01
General master equations are used to study steady-state hopping transport in a disordered solid. We express a site`s occupancy in terms of its quasi-electrochemical potential (QECP); currents flow between sites whose QECP`s differ. Coupled nonlinear circuit equations for the QECP`s result from the steady-state condition and the boundary condition that the total QECP drop is the applied emf. When the site-to-site QECP differences are much smaller than the thermal energy, K{sub B}t, the effect of current flow on site occupancies is ignorable. These equations then reduce to those of a resistance network. However, the resistor-network model fails: (a) at low temperatures, (b) with increasing disorder, and (c) with increasing emf. We therefore study hopping conduction beyond this approximation. Exact examples show the importance of current-induced charge redistribution in non-ohmic steady-state flow.
Sickle cell disease painful crisis and steady state differentiation by proton magnetic resonance.
Fernández, Adolfo A; Cabal, Carlos A; Lores, Manuel A; Losada, Jorge; Pérez, Enrique R
2009-01-01
The delay time of the Hb S polymerization process was investigated in 63 patients with sickle cell disease during steady state and 10 during painful crisis starting from spin-spin proton magnetic resonance (PMR) time behavior measured at 36 degrees C and during spontaneous deoxygenation. We found a significant decrease of delay time as a result of the crisis (36 +/- 10%) and two well-differentiated ranges of values for each state: 273-354 min for steady state and 166-229 min for crisis with an uncertainty region of 15%. It is possible to use PMR as an objective and quantitative method in order to differentiate both clinical conditions of the sickle cell patient, but a more clear differentiation can be established comparing the delay time (td) value of one patient during crisis with his own td value during steady state.
Characterising Steady-State Topologies of SIS Dynamics on Adaptive Networks
Wieland, Stefan; Parisi, Andrea; Nunes, Ana
2012-01-01
Disease awareness in epidemiology can be modelled with adaptive contact networks, where the interplay of disease dynamics and network alteration often adds new phases to the standard models (Gross et al. 2006, Shaw et al. 2008) and, in stochastic simulations, lets network topology settle down to a steady state that can be static (in the frozen phase) or dynamic (in the endemic phase). We show for the SIS model that, in the endemic phase, this steady state does not depend on the initial network topology, only on the disease and rewiring parameters and on the link density of the network, which is conserved. We give an analytic description of the structure of this co-evolving network of infection through its steady-state degree distribution.
Institute of Scientific and Technical Information of China (English)
王自东; 胡汉起
1997-01-01
The nonlinear dynamics equations of the time dependence of the perturbation amplitude of the solid/ liquid interface during unidirectional solidification of a dilute binary alloy are established. The solutions to these equations are obtained, and the condition of the initial steady state growth of the cellular and dendritic structure after the planar solid/liquid interface bifurcates (mGc> G) with the increase of the growth rate is given. The condition of the steady state growth of fine cellular and dendritic structure in the beginning after the coarse dendrites bifurcate ( mGc<Γw2 + G) under the rapid solidification is obtained. The relationship of the steady state cell and dendrite tip radius, the perturbation amplitude and wavelength at the solid/liquid interface is presented.
Influence of Micro-Grid in Steady State Performance of Primary Distribution System
Directory of Open Access Journals (Sweden)
K. Buayai
2013-06-01
Full Text Available Steady state analysis of primary distribution system is an integral part of Micro Grid (MG planning, design and operation of distribution system. In order to maximize performance and ensure secured operation of distribution system with MG, it is important to perform various analytical studies, both in static and dynamic domains. Static studies are the first step and static performance can be established by looking at a number of stead state aspects such as total power losses, voltage profile, feeder current and load ability of the system. This study presents such first step static analytical studies based on distribution load flow to see various steady state performances of primary distribution system due to the integration of MG. A 33-bus test distribution system has been used to present steady state performances. Results clearly show some useful contribution of MG in improving distribution system performance.
Pre-Steady-State Kinetic Analysis of Single-Nucleotide Incorporation by DNA Polymerases.
Su, Yan; Peter Guengerich, F
2016-06-01
Pre-steady-state kinetic analysis is a powerful and widely used method to obtain multiple kinetic parameters. This protocol provides a step-by-step procedure for pre-steady-state kinetic analysis of single-nucleotide incorporation by a DNA polymerase. It describes the experimental details of DNA substrate annealing, reaction mixture preparation, handling of the RQF-3 rapid quench-flow instrument, denaturing polyacrylamide DNA gel preparation, electrophoresis, quantitation, and data analysis. The core and unique part of this protocol is the rationale for preparation of the reaction mixture (the ratio of the polymerase to the DNA substrate) and methods for conducting pre-steady-state assays on an RQF-3 rapid quench-flow instrument, as well as data interpretation after analysis. In addition, the methods for the DNA substrate annealing and DNA polyacrylamide gel preparation, electrophoresis, quantitation and analysis are suitable for use in other studies. © 2016 by John Wiley & Sons, Inc.
Open Markov processes: A compositional perspective on non-equilibrium steady states in biology
Pollard, Blake S
2016-01-01
In recent work, Baez, Fong and the author introduced a framework for describing Markov processes equipped with a detailed balanced equilibrium as open systems of a certain type. These `open Markov processes' serve as the building blocks for more complicated processes. In this paper, we describe the potential application of this framework in the modeling of biological systems as open systems maintained away from equilibrium. We show that non-equilibrium steady states emerge in open systems of this type, even when the rates of the underlying process are such that a detailed balanced equilibrium is permitted. It is shown that these non-equilibrium steady states minimize a quadratic form which we call `dissipation.' In some circumstances, the dissipation is approximately equal to the rate of change of relative entropy plus a correction term. On the other hand, Prigogine's principle of minimum entropy production generally fails for non-equilibrium steady states. We use a simple model of membrane transport to illus...
Mechanism of Non-Steady State Dissolution of Goethite in the Presence of Siderophores
Reichard, P. U.; Kretzschmar, R.; Kraemer, S. M.
2003-12-01
Iron is an essential micronutrient for almost all known organisms. Bacteria, fungi, and graminaceous plants are capable of exuding siderophores as part of an iron acquisition strategy. The production of these strong iron chelating ligands is induced by iron limited conditions. Grasses under iron stress, for example, exude phytosiderophores into the rhizosphere in a special diurnal rhythm (Roemheld and Marschner 1986). A few hours after sunrise the exudation starts, culminates around noon and is shut down again until about 4 hours after noon. The phytosiderophores diffuse into the rhizosphere (Marschner et al. 1986) and are passively back transported to the plants by advective flow induced by high transpiration around noon. Despite a fairly short residence time of the phytosiderophores in the rhizosphere, it is a very effective strategy for iron acquisition. To investigate the effect of such pulse inputs of siderophores on iron acquisition, we studied the dissolution mechanism of goethite (alpha-FeOOH), a mineral phase common in soils, under non-steady state conditions. In consideration of the chemical complexity of the rhizosphere, we also investigated the effect of other organic ligands commonly found in the rhizosphere (e. g. oxalate) on the dissolution kinetics. The dissolution experiments were conducted in batch reactors with a constant goethite solids concentration of 2.5 g/l, an ionic strength of 0.01 M, a pH of 6 and 100 microM oxalate. To induce non-steady state conditions, 3 mM phytosiderophores were added to a batch after the goethite-oxalate suspension reacted for a certain time period. Before the siderophore was added to the goethite-oxalate suspension, no dissolution of iron was observed. But, with the addition of the siderophore, a high rate was observed for the iron mobilization under these non-steady state conditions that subsequently was followed by a slow steady state dissolution rate. The results of these non-steady state experiments are very
Steady-State Density Functional Theory for Non-equilibrium Quantum Systems
Shuanglong, Liu
Recently, electron transport properties of molecular junctions under finite bias voltages have attracted a lot of attention because of the potential application of molecular electronic devices. When a molecular junction is under zero bias voltage at zero temperature, it is in equilibrium ground state and all its properties can be solved by ground-state density functional theory (GS-DFT) where ground-state electron density determines everything. Under finite bias voltage, the molecular junction is in non-equilibrium steady state. According to Hershfield's non-equilibrium statistics, a system in non-equilibrium steady state corresponds to an effective equilibrium system. This correspondence provides the basis for the steady-state density functional theory (SS-DFT) which will be developed in this thesis. (Abstract shortened by UMI.).
Energy Technology Data Exchange (ETDEWEB)
Wang, Qian [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Bincheng, E-mail: bcli@ioe.ac.cn [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)
2015-09-28
Spatially resolved steady-state photocarrier radiometric (PCR) imaging technique is developed to characterize the electronic transport properties of silicon wafers. Based on a nonlinear PCR theory, simulations are performed to investigate the effects of electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) on the steady-state PCR intensity profiles. The electronic transport parameters of an n-type silicon wafer are simultaneously determined by fitting the measured steady-state PCR intensity profiles to the three-dimensional nonlinear PCR model. The determined transport parameters are in good agreement with the results obtained by the conventional modulated PCR technique with multiple pump beam radii.
Energy Technology Data Exchange (ETDEWEB)
Reisenauer, A.E.
1979-12-01
A system of computer codes to aid in the preparation and evaluation of ground-water model input, as well as in the computer codes and auxillary programs developed and adapted for use in modeling major ground-water aquifers is described. The ground-water model is interactive, rather than a batch-type model. Interactive models have been demonstrated to be superior to batch in the ground-water field. For example, looking through reams of numerical lists can be avoided with the much superior graphical output forms or summary type numerical output. The system of computer codes permits the flexibility to develop rapidly the model-required data files from engineering data and geologic maps, as well as efficiently manipulating the voluminous data generated. Central to these codes is the Ground-water Model, which given the boundary value problem, produces either the steady-state or transient time plane solutions. A sizeable part of the codes available provide rapid evaluation of the results. Besides contouring the new water potentials, the model allows graphical review of streamlines of flow, travel times, and detailed comparisons of surfaces or points at designated wells. Use of the graphics scopes provide immediate, but temporary displays which can be used for evaluation of input and output and which can be reproduced easily on hard copy devices, such as a line printer, Calcomp plotter and image photographs.
Ground-water resources of Cambodia
Rasmussen, William Charles; Bradford, Gary M.
1977-01-01
available information is on the central lowlands and contiguous low plateaus, as the mountainous areas on the west and the high plateaus on the east are relatively unexplored with respect to their ground-water availability. No persistent artesian aquifer has been identified nor have any large potential ground-water sources been found .although much of the country yet remains to be explored by test drilling. Well irrigation for garden produce is feasible on a modest scale in many localities throughout Cambodia. It does not seem likely, however, that large-scale irrigation from wells will come about in the future. Ground water may be regarded as a widely available supplemental source to surface water for domestic, small-scale industrial, and irrigation use.
Luukkonen, Carol L.; Westjohn, David B.
2000-01-01
The cities of Kingsford and Iron Mountain are in the southwestern part of Dickinson County in the Upper Peninsula of Michigan. Residents and businesses in these cites rely primarily on ground water from aquifers in glacial deposits. Glacial deposits generally consist of an upper terrace sand-and-gravel unit and a lower outwash sand-and-gravel unit, separated by lacustrine silt and clay and eolian silt layers. These units are not regionally continuous, and are absent in some areas. Glacial deposits overlie Precambrian bedrock units that are generally impermeable. Precambrian bedrock consists of metasedimentary (Michigamme Slate, Vulcan Iron Formation, and Randville Dolomite) and metavolcanic (Badwater Greenstone and Quinnesec Formation) rocks. Where glacial deposits are too thin to compose an aquifer usable for public or residential water supply, Precambrian bedrock is relied upon for water supply. Typically a few hundred feet of bedrock must be open to a wellbore to provide adequate water for domestic users. Ground-water flow in the glacial deposits is primarily toward the Menominee River and follows the direction of the regional topographic slope and the bedrock surface. To protect the quality of ground water, Kingsford and Iron Mountain are developing Wellhead Protection Plans to delineate areas that contribute water to public-supply wells. Because of the complexity of hydrogeology in this area and historical land-use practices, a steady-state ground-water-flow model was prepared to represent the ground-water-flow system and to delineate contributing areas to public-supply wells. Results of steady-state simulations indicate close agreement between simulated and observed water levels and between water flowing into and out of the model area. The 10-year contributing areas for Kingsford's public-supply wells encompass about 0.11 square miles and consist of elongated areas to the east of the well fields. The 10-year contributing areas for Iron Mountain's public
Transient and steady-state velocity of domain walls for a complete range of drive fields
Bourne, H. C., Jr.; Bartran, D. S.
1974-01-01
Approximate analytic solutions for transient and steady-state 180 deg domain wall motion in bulk magnetic material are obtained from the dynamic torque equations with a Gilbert damping term. The results for the Walker region in which the transient solution approaches the familiar Walker steady-state solution are presented in a slightly new form for completeness. An analytic solution corresponding to larger drive fields predicts an oscillatory motion with an average value which decreases with drive field for reasonable values of the damping parameter. These results agree with those obtained by a computer solution of the torque equation and those obtained with the assumption of a very large anisotropy field.
Realization of minute-long steady-state H-mode discharges on EAST
Xianzu, GONG; Baonian, WAN; Jiangang, LI; Jinping, QIAN; Erzhong, LI; Fukun, LIU; Yanping, ZHAO; Mao, WANG; Handong, XU; A, M. GAROFALO; Annika, EKEDAH; Siye, DING; Juan, HUANG; Ling, ZHANG; Qing, ZANG; Haiqing, LIU; Long, ZENG; Shiyao, LIN; Biao, SHEN; Bin, ZHANG; Linming, SHAO; Bingjia, XIAO; Jiansheng, HU; Chundong, HU; Liqun, HU; Liang, WANG; Youwen, SUN; Guosheng, XU; Yunfeng, LIANG; Nong, XIANG; EAST Team
2017-03-01
In the 2016 EAST experimental campaign, a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive, through an integrated control of the wall conditioning, plasma configuration, divertor heat flux, particle exhaust, impurity management, and effective coupling of multiple RF heating and current drive sources at high injected power. The plasma current (I p ∼ 0.45 MA) was fully-noninductively driven (V loop technology studies on EAST, and will benefit the physics basis for steady state operation of ITER and CFETR.
Characterization of polyester films used in capacitors. 1: Transient and steady-state conductivity
Thielen, A.; Niezette, J.; Feyder, G.; Vanderschueren, J.
1994-10-01
Charging and discharging currents flowing through polyethylene terephthalate (PET) ultrathin films (1.5 - 12 micrometers) were measured by the use of a two-electrode configuration involving opposite lateral contacts. A study of the influence of electrification time, applied electric field, film thickness, nature of electrodes, and water content was carried out on both transient and steady-state conduction. The transient behavior can be interpreted in terms of dipolar orientation and relaxation processes while steady-state conductivity can be mainly accounted for in terms of Schottky emission. A comparison between PET and polyethylene naphthalate films is also reported.
Wang, Chong; Qiu, Zhi-Ping
2014-04-01
A new numerical technique named interval finite difference method is proposed for the steady-state temperature field prediction with uncertainties in both physical parameters and boundary conditions. Interval variables are used to quantitatively describe the uncertain parameters with limited information. Based on different Taylor and Neumann series, two kinds of parameter perturbation methods are presented to approximately yield the ranges of the uncertain temperature field. By comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method for solving steady-state heat conduction problem with uncertain-but-bounded parameters. [Figure not available: see fulltext.
Steady-State Numerical Modeling of Size Effects in Wire Drawing
DEFF Research Database (Denmark)
Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof
2016-01-01
Wire drawing processes at micron scale receive increased interest as micro wires are increasingly required in micro electrical components. At the micron scale, size effects become important and have to be taken into consideration. The goal is to optimize the semi-cone angle of the tool in terms...... of drawing force. The present study employs a steady-state modelling technique that omits the transient regime, thus creating a basis for comprehensive parameter studies. The steady-state procedure is based on the streamline integration method presented by Dean and Hutchinson [1]. This approach allows...
UNIVERSAL THEORY OF STEADY-STATE ONE-DIMENSIONAL PHOTOREFRACTIVE SOLITONS
Institute of Scientific and Technical Information of China (English)
刘劲松
2001-01-01
A universal theory of steady-state one-dimensional photorefractive spatial solitons is developed which applies to the steady-state one-dimensional photorefractive solitons under various realizations, including the screening solitons in a biased photorefractive medium, the photovoltaic solitons in open- and closed-circuit photovoltaic-photorefractive media and the screening-photovoltaic solitons in biased photovoltaic-photorefractive media. Previous theories advanced individually elsewhere for these solitons can be obtained by simplifying the universal theory under the appropriate conditions.
Constructive interference in steady-state/FIESTA-C clinical applications in neuroimaging.
Kulkarni, Makarand; Kulkami, Makarand
2011-04-01
High spatial resolution is one of the major problems in neuroimaging, particularly in cranial and spinal nerve imaging. Constructive interference in steady-state/fast imaging employing steady-state acquisition with phase cycling is a robust sequence in imaging the cranial and spinal nerve pathologies. This pictorial review is a concise article about the applications of this sequence in neuroimaging with clinical examples. © 2011 The Author. Journal of Medical Imaging and Radiation Oncology © 2011 The Royal Australian and New Zealand College of Radiologists.
Non-equilibrium steady states: fluctuations and large deviations of the density and of the current
Derrida, Bernard
2007-07-01
These lecture notes give a short review of methods such as the matrix ansatz, the additivity principle or the macroscopic fluctuation theory, developed recently in the theory of non-equilibrium phenomena. They show how these methods allow us to calculate the fluctuations and large deviations of the density and the current in non-equilibrium steady states of systems like exclusion processes. The properties of these fluctuations and large deviation functions in non-equilibrium steady states (for example, non-Gaussian fluctuations of density or non-convexity of the large deviation function which generalizes the notion of free energy) are compared with those of systems at equilibrium.
A quaternionic map for the steady states of the Heisenberg spin-chain
Energy Technology Data Exchange (ETDEWEB)
Mehta, Mitaxi P., E-mail: mitaxi.mehta@ahduni.edu.in [IICT, Ahmedabad University, Opp. IIM, Navrangpura, Ahmedabad (India); Dutta, Souvik; Tiwari, Shubhanshu [BITS-Pilani, K.K. Birla Goa campus, Goa (India)
2014-01-17
We show that the steady states of the classical Heisenberg XXX spin-chain in an external magnetic field can be found by iterations of a quaternionic map. A restricted model, e.g., the xy spin-chain is known to have spatially chaotic steady states and the phase space occupied by these chaotic states is known to go through discrete changes as the field strength is varied. The same phenomenon is studied for the xxx spin-chain. It is seen that in this model the phase space volume varies smoothly with the external field.
Existence and stabilizability of steady-state for semilinear pulse-width sampler controlled system
Directory of Open Access Journals (Sweden)
JinRong Wang
2011-01-01
Full Text Available In this paper, we study the steady-state of a semilinear pulse-width sampler controlled system on infinite dimensional spaces. Firstly, by virtue of Schauder's fixed point theorem, the existence of periodic solutions is given. Secondly, utilizing a generalized Gronwall inequality given by us and the Banach fixed point theorem, the existence and stabilizability of a steady-state for the semilinear control system with pulse-width sampler is also obtained. At last, an example is given for demonstration.
SUPERENERGY-2: a multiassembly, steady-state computer code for LMFBR core thermal-hydraulic analysis
Energy Technology Data Exchange (ETDEWEB)
Basehore, K.L.; Todreas, N.E.
1980-08-01
Core thermal-hydraulic design and performance analyses for Liquid Metal Fast Breeder Reactors (LMFBRs) require repeated detailed multiassembly calculations to determine radial temperature profiles and subchannel outlet temperatures for various core configurations and subassembly structural analyses. At steady-state, detailed core-wide temperature profiles are required for core restraint calculations and subassembly structural analysis. In addition, sodium outlet temperatures are routinely needed for each reactor operating cycle. The SUPERENERGY-2 thermal-hydraulic code was designed specifically to meet these designer needs. It is applicable only to steady-state, forced-convection flow in LMFBR core geometries.
EFFICIENT STEADY-STATE ANALYSIS METHOD FOR CLOSED-LOOP PWM SWITCHING CONVERTERS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Since the early70s,many s mall-signal fre-quency-domain modeling technique have been de-veloped to study the dynamic perfor mances and sta-bilities ofPWMs witching converters around thestatic operating point.However,the accuracy of thederived models relies on accurate deter mination ofthe steady state operating point,and usually manyperfor mances of circuits are given based on steady-state,so it is very essential to analyze the steadystate of circuits.Analysis methods for steadystate ofnonlinear circuits ca...
S3C: EBT Steady-State Shooting code description and user's guide
Energy Technology Data Exchange (ETDEWEB)
Downum, W.B.
1983-09-01
The Oak Ridge National Laboratory (ORNL) one-dimensional (1-D) Steady-State Shooting code (S3C) for ELMO Bumpy Torus (EBT) plasmas is described. Benchmark calculations finding the steady-state density and electron and ion temperature profiles for a known neutral density profile and known external energy sources are carried out. Good agreement is obtained with results from the ORNL Radially Resolved Time Dependent 1-D Transport code for an EBT-Q type reactor. The program logic is described, along with the physics models in each code block and the variable names used. Sample input and output files are listed, along with the main code.
DEFF Research Database (Denmark)
Deng, Yu-Jia; Wiberg, Gustav Karl Henrik; Zana, Alessandro
2017-01-01
-state conditions. As a benchmark, the ORR activity is compared with those of polycrystalline Pt and a commercial Pt/C catalyst. The results show that, under transient conditions, the catalytic performance of the THH Pt NPs and Pt/C are approximately the same and about 2 times lower than that of polycrystalline Pt....... However, under steady-state conditions the THH Pt NPs perform considerably better than Pt/C. Under steady-state conditions THH Pt NPs are even slightly more active than polycrystalline Pt...
Steady-State Kinetic Analysis of DNA Polymerase Single-Nucleotide Incorporation Products
O'Flaherty, Derek K.
2014-01-01
This unit describes the experimental procedures for the steady-state kinetic analysis of DNA synthesis across DNA nucleotides (native or modified) by DNA polymerases. In vitro primer extension experiments with a single nucleoside triphosphate species followed by denaturing polyacrylamide gel electrophoresis of the extended products is described. Data analysis procedures and fitting to steady-state kinetic models is presented to highlight the kinetic differences involved in the bypass of damaged versus undamaged DNA. Moreover, explanations concerning problems encountered in these experiments are addressed. This approach provides useful quantitative parameters for the processing of damaged DNA by DNA polymerases. PMID:25501593
Steady-state creep of complexly reinforced shallow metal-composite shells
Yankovskii, A. P.
2010-05-01
The problem of deformation of shallow shells of variable thickness reinforced with fibers of constant cross section, whose all phases operate under the conditions of steady-state creep, is formulated. The system of resolving equations and the corresponding boundary conditions are analyzed, and the procedure for solving this problem is developed. A way of approximate solution of such problems in the case of transient creep is indicated. The particular calculations performed show that the compliance of thin-walled structures, under the conditions of steady-state creep, greatly depends on the structure of reinforcement.
Arbitrary Steady-State Solutions with the K-epsilon Model
Rumsey, Christopher L.; Pettersson Reif, B. A.; Gatski, Thomas B.
2006-01-01
Widely-used forms of the K-epsilon turbulence model are shown to yield arbitrary steady-state converged solutions that are highly dependent on numerical considerations such as initial conditions and solution procedure. These solutions contain pseudo-laminar regions of varying size. By applying a nullcline analysis to the equation set, it is possible to clearly demonstrate the reasons for the anomalous behavior. In summary, the degenerate solution acts as a stable fixed point under certain conditions, causing the numerical method to converge there. The analysis also suggests a methodology for preventing the anomalous behavior in steady-state computations.
Piezoelectricity in Two-Dimensional Materials
Wu, Tao
2015-02-25
Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.
Kronecker Product of Two-dimensional Arrays
Institute of Scientific and Technical Information of China (English)
Lei Hu
2006-01-01
Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays. Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.
Two-Dimensional Toda-Heisenberg Lattice
Directory of Open Access Journals (Sweden)
Vadim E. Vekslerchik
2013-06-01
Full Text Available We consider a nonlinear model that is a combination of the anisotropic two-dimensional classical Heisenberg and Toda-like lattices. In the framework of the Hirota direct approach, we present the field equations of this model as a bilinear system, which is closely related to the Ablowitz-Ladik hierarchy, and derive its N-soliton solutions.
A novel two dimensional particle velocity sensor
Pjetri, Olti; Wiegerink, Remco J.; Lammerink, Theo S.; Krijnen, Gijs J.
2013-01-01
In this paper we present a two wire, two-dimensional particle velocity sensor. The miniature sensor of size 1.0x2.5x0.525 mm, consisting of only two crossed wires, shows excellent directional sensitivity in both directions, thus requiring no directivity calibration, and is relatively easy to fabrica
Two-dimensional microstrip detector for neutrons
Energy Technology Data Exchange (ETDEWEB)
Oed, A. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.
Two-dimensional magma-repository interactions
Bokhove, O.
2001-01-01
Two-dimensional simulations of magma-repository interactions reveal that the three phases --a shock tube, shock reflection and amplification, and shock attenuation and decay phase-- in a one-dimensional flow tube model have a precursor. This newly identified phase ``zero'' consists of the impact of
Two-dimensional subwavelength plasmonic lattice solitons
Ye, F; Hu, B; Panoiu, N C
2010-01-01
We present a theoretical study of plasmonic lattice solitons (PLSs) formed in two-dimensional (2D) arrays of metallic nanowires embedded into a nonlinear medium with Kerr nonlinearity. We analyze two classes of 2D PLSs families, namely, fundamental and vortical PLSs in both focusing and defocusing media. Their existence, stability, and subwavelength spatial confinement are studied in detai
A two-dimensional Dirac fermion microscope
DEFF Research Database (Denmark)
Bøggild, Peter; Caridad, Jose; Stampfer, Christoph
2017-01-01
in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...
General database for ground water site information.
de Dreuzy, Jean-Raynald; Bodin, Jacques; Le Grand, Hervé; Davy, Philippe; Boulanger, Damien; Battais, Annick; Bour, Olivier; Gouze, Philippe; Porel, Gilles
2006-01-01
In most cases, analysis and modeling of flow and transport dynamics in ground water systems require long-term, high-quality, and multisource data sets. This paper discusses the structure of a multisite database (the H+ database) developed within the scope of the ERO program (French Environmental Research Observatory, http://www.ore.fr). The database provides an interface between field experimentalists and modelers, which can be used on a daily basis. The database structure enables the storage of a large number of data and data types collected from a given site or multiple-site network. The database is well suited to the integration, backup, and retrieval of data for flow and transport modeling in heterogeneous aquifers. It relies on the definition of standards and uses a templated structure, such that any type of geolocalized data obtained from wells, hydrological stations, and meteorological stations can be handled. New types of platforms other than wells, hydrological stations, and meteorological stations, and new types of experiments and/or parameters could easily be added without modifying the database structure. Thus, we propose that the database structure could be used as a template for designing databases for complex sites. An example application is the H+ database, which gathers data collected from a network of hydrogeological sites associated with the French Environmental Research Observatory.
Fractal Dimension of Cohesive Sediment Flocs at Steady State under Seven Shear Flow Conditions
Energy Technology Data Exchange (ETDEWEB)
Zhu, Zhongfan; Yu, Jingshan; Wang, Hongrui; Dou, Jie; Wang, Cheng
2015-08-01
The morphological properties of kaolin flocs were investigated in a Couetteflow experiment at the steady state under seven shear flow conditions (shear rates of 5.36, 9.17, 14, 24, 31, 41 and 53 s-1). These properties include a one-dimensional (1-D) fractal dimension (D1), a two-dimensional (2-D) fractal dimension (D2), a perimeter-based fractal dimension (Dpf) and an aspect ratio (AR). They were calculated based on the projected area (A), equivalent size, perimeter (P) and length (L) of the major axis of the floc determined through sample observation and an image analysis system. The parameter D2, which characterizes the relationship between the projected area and the length of the major axis using a power function, , increased from 1.73 ± 0.03, 1.72 ± 0.03, and 1.75 ± 0.04 in the low shear rate group (G = 5.36, 9.17, and 14 s-1) to 1.92 ± 0.03, 1.82 ± 0.02, 1.85 ± 0.02, and 1.81 ± 0.02 in the high shear rate group (24, 31, 41 and 53 s-1), respectively. The parameter D1 characterizes the relationship between the perimeter and length of the major axis by the function and decreased from 1.52 ± 0.02, 1.48 ± 0.02, 1.55 ± 0.02, and 1.63 ± 0.02 in the low shear group (5.36, 9.17, 14 and 24 s-1) to 1.45 ± 0.02, 1.39 ± 0.02, and 1.39 ± 0.02 in the high shear group (31, 41 and 53 s-1), respectively. The results indicate that with increasing shear rates, the flocs become less elongated and that their boundary lines become tighter and more regular, caused by more breakages and possible restructurings of the flocs. The parameter Dpf, which is related to the perimeter and the projected area through the function , decreased as the shear rate increased approximately linearly. The parameter AR, which is the ratio of the length of the major axis and equivalent diameter, decreased from 1.56, 1.59, 1.53 and 1.51 in the low shear rate group to 1.43, 1.47 and 1.48 in the high shear rate group. These changes in Dpf and AR show that the flocs become less convoluted and
Fractal Dimension of Cohesive Sediment Flocs at Steady State under Seven Shear Flow Conditions
Directory of Open Access Journals (Sweden)
Zhongfan Zhu
2015-08-01
Full Text Available The morphological properties of kaolin flocs were investigated in a Couette-flow experiment at the steady state under seven shear flow conditions (shear rates of 5.36, 9.17, 14, 24, 31, 41 and 53 s−1. These properties include a one-dimensional (1-D fractal dimension (D1, a two-dimensional (2-D fractal dimension (D2, a perimeter-based fractal dimension (Dpf and an aspect ratio (AR. They were calculated based on the projected area (A, equivalent size, perimeter (P and length (L of the major axis of the floc determined through sample observation and an image analysis system. The parameter D2, which characterizes the relationship between the projected area and the length of the major axis using a power function, , increased from 1.73 ± 0.03, 1.72 ± 0.03, and 1.75 ± 0.04 in the low shear rate group (G = 5.36, 9.17, and 14 s−1 to 1.92 ± 0.03, 1.82 ± 0.02, 1.85 ± 0.02, and 1.81 ± 0.02 in the high shear rate group (24, 31, 41 and 53 s−1, respectively. The parameter D1 characterizes the relationship between the perimeter and length of the major axis by the function and decreased from 1.52 ± 0.02, 1.48 ± 0.02, 1.55 ± 0.02, and 1.63 ± 0.02 in the low shear group (5.36, 9.17, 14 and 24 s−1 to 1.45 ± 0.02, 1.39 ± 0.02, and 1.39 ± 0.02 in the high shear group (31, 41 and 53 s−1, respectively. The results indicate that with increasing shear rates, the flocs become less elongated and that their boundary lines become tighter and more regular, caused by more breakages and possible restructurings of the flocs. The parameter Dpf, which is related to the perimeter and the projected area through the function , decreased as the shear rate increased almost linearly. The parameter AR, which is the ratio of the length of the major axis and equivalent diameter, decreased from 1.56, 1.59, 1.53 and 1.51 in the low shear rate group to 1.43, 1.47 and 1.48 in the high shear rate group. These changes in Dpf and AR show that the flocs become less
Design of a steady-state detector for fault detection and diagnosis of a residential air conditioner
Energy Technology Data Exchange (ETDEWEB)
Kim, Minsung [Geothermal Energy Research Center, Korea Institute of Energy Research, Daejeon 305-343 (Korea); Yoon, Seok Ho; Domanski, Piotr A.; Vance Payne, W. [HVAC and R Equipment Performance Group, National Institute of Standards and Technology, 100 Bureau Drive, MS 8631, Gaithersburg, MD 20899 (United States)
2008-08-15
This paper presents a general methodology for developing a steady-state detector for a vapor compression system based on a moving window and using standard deviations of seven measurements selected as features. The feature thresholds and optimized moving window size were based upon steady-state no-fault tests and startup transient tests. The study showed that evaporator superheat and condenser subcooling were sufficient for determining the onset of steady-state during the startup transient. However, they misidentified steady-state during indoor temperature change tests where evaporator saturation temperature and air temperature change across the evaporator were needed for proper steady-state identification. Hence, the paper recommends including all fault detection and diagnosis (FDD) features in the steady-state detector to ensure the robustness of the detector because different features may play key roles with different transients. (author)
Addition of multimodal therapy to standard management of steady state sickle cell disease.
Okpala, Iheanyi; Ezenwosu, Osita; Ikefuna, Anthony; Duru, Augustine; Chukwu, Barth; Madu, Anazoeze; Nwagha, Theresa; Ocheni, Sunday; Ibegbulam, Obike; Emodi, Ifeoma; Anike, Uche; Nonyelu, Charles; Anigbo, Chukwudi; Agu, Kingsley; Ajuba, Ifeoma; Chukwura, Awele; Ugwu, Ogechukwu; Ololo, Uche
2013-01-01
Most people on folic acid to boost erythropoiesis and prophylactic antimicrobials, the standard management of steady state sickle cell disease (SCD), have unacceptable numbers of crises. The objective of this study was to evaluate the effects of adding multimodal therapy with potassium thiocyanate and omega-3 fatty acids to the standard management of steady state SCD. Pre- and post-treatment numbers of crises and other disease indices were compared in 16 HbSS individuals on folic acid and paludrine after 12 months of adding eicosapentaenoic acid 15 mg/kg/day, docosahexaenoic acid 10 mg/kg/day, and potassium thiocyanate 1-2 mL/day, each milliliter of which contained 250 mg of thiocyanate and 100 micrograms of iodine to prevent hypothyroidism: a possible side-effect due to competitive inhibition of the transport of iodide into the thyroid gland by thiocyanate. Median number of crises reduced from 3/yr to 1/yr (P < 0.0001). There was no evidence of impaired thyroid function. Plasma level of tri-iodothyronine improved (P < 0.0001). Steady state full blood count and bilirubin level did not change significantly. The findings suggest that addition of potassium thiocyanate and eicosapentaenoic and docosahexaenoic acids to standard management of steady state SCD reduces the number of crises. This observation needs to be evaluated in larger studies.
Steady-State Response of Periodically Supported Structures to a Moving Load
Metrikine, A.V.; Wolfert, A.F.M.; Vrouwenvelder, A.C.W.M.
1999-01-01
Steady-state vibrations of periodically supported structures under a moving load are analytically investigated. The following three structures are considered: an overhead power line for a train, a long suspended bridge and a railway track. The study is based on the application of so-called 'periodic
A Steady State Visually Evoked Potential Investigation of Memory and Ageing
Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard
2009-01-01
Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and…
Variational Principle for Non-Equilibrium Steady States of the XX Model
Matsui, T
2003-01-01
We show that non-equilibrium steady states of the one dimensional exactly solved XY model can be characterized by the variational principle of free energy of a long range interaction and that they cannot be a KMS state for any C$^*$-dynamical system.
Steady State Visual Evoked Potential Based Brain-Computer Interface for Cognitive Assessment
DEFF Research Database (Denmark)
Westergren, Nicolai; Bendtsen, Rasmus L.; Kjær, Troels W.
2016-01-01
decline is important. Cognitive decline may be detected using fullyautomated computerized assessment. Such systems will provide inexpensive and widely available screenings of cognitive ability. The aim of this pilot study is to develop a real time steady state visual evoked potential (SSVEP) based brain...
Energy Technology Data Exchange (ETDEWEB)
HU, T.A.
2000-04-27
This work is to assess the steady-state flammability level at normal and off-normal ventilation conditions in the tank dome space for 177 double-shell and single-shell tanks at Hanford. Hydrogen generation rate was calculated for 177 tanks using rate equation model developed recently.
Abnormal Attention in Autism Shown by Steady-State Visual Evoked Potentials.
Belmonte, Matthew
2000-01-01
Eight males with autism were required to shift attention between rapidly flashed targets alternating between left and right visual hemifields. When targets were separated by less than 700 ms, steady-state brain electrical response in both hemispheres was augmented and background EEG decreased for rightward shifts as compared with leftward shifts.…
Radioactivity computation of steady-state and pulsed fusion reactors operation
Energy Technology Data Exchange (ETDEWEB)
Attaya, H.
1994-06-01
Different mathematical methods are used to calculate the nuclear transmutation in steady-state and pulsed neutron irradiation. These methods are the Schuer decomposition, the eigenvector decomposition, and the Pade approximation of the matrix exponential function. In the case of the linear decay chain approximation, a simple algorithm is used to evaluate the transition matrices.
DEFF Research Database (Denmark)
Wagner, Manfred H.; Rolon-Garrido, Victor H.; Nielsen, Jens Kromann
2008-01-01
The transient and steady-state elongational viscosity data of three bidisperse polystyrene blends were investigated recently by Nielsen et al. [J. Rheol. 50, 453-476 (2006)]. The blends contain a monodisperse high molar mass component (M-L= 390 kg/ mol) in a matrix of a monodisperse small molar m...
Steady State Crack Propagation in Layered Material Systems Displaying Visco-plastic Behaviour
DEFF Research Database (Denmark)
Nielsen, Kim Lau
2012-01-01
The steady state fracture toughness of elastic visco-plastic materials is studied numerically, using both a conventional and a higher order model. Focus is on the combined effect of strain hardening, strain gradient hardening and strain rate hardening on cracking in layered material systems...
DEFF Research Database (Denmark)
Kwok, Kawai; Boccaccini, Dino; Persson, Åsa Helen;
2016-01-01
The effective steady-state creep response of porous metals is studied by numerical homogenization and analytical modeling in this paper. The numerical homogenization is based on finite element models of three-dimensional microstructures directly reconstructed from tomographic images. The effects ...... model, and closely matched by the Gibson-Ashby compression and the Ramakrishnan-Arunchalam creep models. [All rights reserved Elsevier]....
A comparison of steady-state ARIES and pulsed PULSAR tokamak power plants
Energy Technology Data Exchange (ETDEWEB)
Bathke, C.G.
1994-07-01
The multi-institutional ARIES study has completed a series of three steady-state and two pulsed cost-optimized conceptual designs of commercial tokamak fusion power plants that vary the level of assumed advances in technology and physics. The cost benefits of various design options are compared quantitatively. Possible means to improve the economic competitiveness of fusion are suggested.
Pharmacokinetic Steady-States Highlight Interesting Target-Mediated Disposition Properties.
Gabrielsson, Johan; Peletier, Lambertus A
2017-05-01
In this paper, we derive explicit expressions for the concentrations of ligand L, target R and ligand-target complex RL at steady state for the classical model describing target-mediated drug disposition, in the presence of a constant-rate infusion of ligand. We demonstrate that graphing the steady-state values of ligand, target and ligand-target complex, we obtain striking and often singular patterns, which yield a great deal of insight and understanding about the underlying processes. Deriving explicit expressions for the dependence of L, R and RL on the infusion rate, and displaying graphs of the relations between L, R and RL, we give qualitative and quantitive information for the experimentalist about the processes involved. Understanding target turnover is pivotal for optimising these processes when target-mediated drug disposition (TMDD) prevails. By a combination of mathematical analysis and simulations, we also show that the evolution of the three concentration profiles towards their respective steady-states can be quite complex, especially for lower infusion rates. We also show how parameter estimates obtained from iv bolus studies can be used to derive steady-state concentrations of ligand, target and complex. The latter may serve as a template for future experimental designs.
DEFF Research Database (Denmark)
Christrup, Lona Louring; Bonde, J; Rasmussen, S N
1992-01-01
Single-dose and steady state pharmacokinetics of diltiazem administered in two different oral formulations were assessed with particular reference to rate and extent of absorption. Following single dose administration a significant difference in tmax was observed (2.9 +/- 1.9 and 6.8 +/- 2.6 hr r...
Institute of Scientific and Technical Information of China (English)
2008-01-01
Nonlinear parametric vibration of axially accelerating viscoelastic beams is inves-tigated via an approximate analytical method with numerical confirmations. Based on nonlinear models of a finite-small-stretching slender beam moving at a speed with a periodic fluctuation, a solvability condition is established via the method of multiple scales for subharmonic resonance. Therefore, the amplitudes of steady-state periodic responses and their existence conditions are derived. The amplitudes of stable steady-state responses increase with the amplitude of the axial speed fluctuation, and decrease with the viscosity coefficient and the nonlinear coefficient. The minimum of the detuning parameter which causes the existence of a stable steady-state periodic response decreases with the amplitude of the axial speed fluctuation, and increases with the viscosity coefficient. Nu-merical solutions are sought via the finite difference scheme for a nonlinear par-tial-differential equation and a nonlinear integro-partial-differential equation. The calculation results qualitatively confirm the effects of the related parameters pre-dicted by the approximate analysis on the amplitude and the existence condition of the stable steady-state periodic responses. Quantitative comparisons demonstrate that the approximate analysis results have rather high precision.
Energy Technology Data Exchange (ETDEWEB)
Conceicao, Carlos Antonio Levi da; Troyman, Antonio Carlos Ramos [Universidade Federal, Rio de Janeiro, RJ (Brazil). Programa de Engenharia Oceanica
1995-07-01
Surface panel method has been applied to the propeller analysis. For the propeller modeling, the boss and blades surfaces have been discretized in quadrilateral panels with dipoles and sources constant distributions. The surface of the blade wakes have been represented by panels with dipole constant distributions. This discussion focused only the propeller under steady state operation.
Transient and Steady-State Responses of an Asymmetric Nonlinear Oscillator
Directory of Open Access Journals (Sweden)
Alex Elías-Zúñiga
2013-01-01
oscillator that describes the motion of a damped, forced system supported symmetrically by simple shear springs on a smooth inclined bearing surface. We also use the percentage overshoot value to study the influence of damping and nonlinearity on the transient and steady-state oscillatory amplitudes.
Energy Technology Data Exchange (ETDEWEB)
HU, T.A.
2005-10-27
Assess the steady-state flammability level at normal and off-normal ventilation conditions. The hydrogen generation rate was calculated for 177 tanks using the rate equation model. Flammability calculations based on hydrogen, ammonia, and methane were performed for 177 tanks for various scenarios.
Calculation of the rate of coagulation of hydrophobic colloids in the non-steady state
Roebersen, G.J.; Wiersema, P.H.
1974-01-01
In accurate coagulation measurements, the observed coagulation rate should be extrapolated to time zero to find the rate of formation of doublets from singlet particles. In the theoretical calculation of coagulation rates, generally a steady state is assumed. At the onset of coagulation, however, a
Pre-steady-state Kinetics for Hydrolysis of Insoluble Cellulose by Cellobiohydrolase Cel7A*
Cruys-Bagger, Nicolaj; Elmerdahl, Jens; Praestgaard, Eigil; Tatsumi, Hirosuke; Spodsberg, Nikolaj; Borch, Kim; Westh, Peter
2012-01-01
The transient kinetic behavior of enzyme reactions prior to the establishment of steady state is a major source of mechanistic information, yet this approach has not been utilized for cellulases acting on their natural substrate, insoluble cellulose. Here, we elucidate the pre-steady-state regime for the exo-acting cellulase Cel7A using amperometric biosensors and an explicit model for processive hydrolysis of cellulose. This analysis allows the identification of a pseudo-steady-state period and quantification of a processivity number as well as rate constants for the formation of a threaded enzyme complex, processive hydrolysis, and dissociation, respectively. These kinetic parameters elucidate limiting factors in the cellulolytic process. We concluded, for example, that Cel7A cleaves about four glycosidic bonds/s during processive hydrolysis. However, the results suggest that stalling the processive movement and low off-rates result in a specific activity at pseudo-steady state that is 10–25-fold lower. It follows that the dissociation of the enzyme-substrate complex (half-time of ∼30 s) is rate-limiting for the investigated system. We suggest that this approach can be useful in attempts to unveil fundamental reasons for the distinctive variability in hydrolytic activity found in different cellulase-substrate systems. PMID:22493488
Three dimensional neutronic/thermal-hydraulic coupled simulation of MSR in steady state condition
Energy Technology Data Exchange (ETDEWEB)
Zhou, Jianjun; Wang, Chenglong [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); An, Hongzhen [Nuclear and Radiation Safety Center, Ministry of Environmental Protection of the People' s Republic of China, Beijing 100082 (China); Zhang, Daling, E-mail: dlzhang@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Qiu, Suizheng; Su, Guanghui; Tian, Wenxi; Wu, Yingwei [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China)
2014-02-15
Highlights: • Developed a three dimensional coupled code for MSR. • Investigated the neutron distribution and thermal-hydraulic characters of the core under steady state condition. • Analyzed the influence of inlet temperature and inlet velocity to thermal-hydraulics characteristics of the reactor. - Abstract: MSR (molten salt reactor) uses liquid molten salt as the coolant and fuel solvent, making it the only liquid reactor among the six generation IV reactor types. As a liquid reactor the physical properties of the reactor are significantly influenced by the fuel salt flow therefore conventional analysis methods applied in solid fuel reactors are not applicable for this type of reactors. The present work developed a three dimensional neutronic/thermal-hydraulic coupled code and applied it to investigate the thermal-hydraulic characteristics of the core in steady state condition based on neutron diffusion theory and numerical heat transfer. The code consists of two group neutron diffusion equations for fast and thermal neutron fluxes and six group balance equations for delayed neutron precursors. The temperature distribution, neutron fluxes and delayed neutron precursors distribution of the core in steady state conditions was studied, and the result analyzed when inlet temperature and velocity were changed. From simulation it was found that the inlet temperature has little influence to neutron distribution however inlet velocity affects the delayed neutron distribution in steady state condition. The results provide some valuable information in design and research of this kind of reactor.
Steady-State Crack Growth in Rate-Sensitive Single Crystals
DEFF Research Database (Denmark)
Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof
2016-01-01
The characteristics of the active plastic zone surrounding a crack growingin a single crystal (FCC, BCC, and HCP) at constant velocity is investigated for ModeI loading under plane strain assumptions. The framework builds upon a steady-state relation bringing the desired solution out in a frame...
Steady-state testing of an advanced solar-assisted heat pump
Energy Technology Data Exchange (ETDEWEB)
Catan, M.A.
1982-06-01
A prototype water-to-air solar assisted heat pump (SAHP) has been tested under steady state conditions. The results of the tests indicate that the nominal goal for the hardware portion of the contract was achieved and surpassed. The tests show some areas of potential improvement, which are discussed.
Steady-State PMU Compliance Test under C37.118.1a-2014
DEFF Research Database (Denmark)
Ghiga, Radu; Wu, Qiuwei; Martin, Kenneth E.;
2016-01-01
This paper presents a flexible testing method and the steady-state compliance of PMUs under the C37.118.1a amendment. The work is focused on the changes made to the standard for the harmonic rejection and out-of-band interference tests for which the ROCOF Error limits have been suspended. The pap...
Thin Film Equations with Soluble Surfactant and Gravity: Modeling and Stability of Steady States
Escher, Joachim; Laurençot, Philippe; Walker, Christoph
2010-01-01
A thin film on a horizontal solid substrate and coated with a soluble surfactant is considered. The governing degenerate parabolic equations for the film height and the surfactant concentrations on the surface and in the bulk are derived using a lubrication approximation when gravity is taken into account. It is shown that the steady states are asymptotically stable.
Current Pressure Transducer Application of Model-based Prognostics Using Steady State Conditions
Teubert, Christopher; Daigle, Matthew J.
2014-01-01
Prognostics is the process of predicting a system's future states, health degradation/wear, and remaining useful life (RUL). This information plays an important role in preventing failure, reducing downtime, scheduling maintenance, and improving system utility. Prognostics relies heavily on wear estimation. In some components, the sensors used to estimate wear may not be fast enough to capture brief transient states that are indicative of wear. For this reason it is beneficial to be capable of detecting and estimating the extent of component wear using steady-state measurements. This paper details a method for estimating component wear using steady-state measurements, describes how this is used to predict future states, and presents a case study of a current/pressure (I/P) Transducer. I/P Transducer nominal and off-nominal behaviors are characterized using a physics-based model, and validated against expected and observed component behavior. This model is used to map observed steady-state responses to corresponding fault parameter values in the form of a lookup table. This method was chosen because of its fast, efficient nature, and its ability to be applied to both linear and non-linear systems. Using measurements of the steady state output, and the lookup table, wear is estimated. A regression is used to estimate the wear propagation parameter and characterize the damage progression function, which are used to predict future states and the remaining useful life of the system.
Steady-state properties of a totally asymmetric exclusion process with particles of arbitrary size
Lakatos, Greg; Chou, Tom
2003-03-01
The steady-state currents and densities of a one-dimensional totally asymmetric exclusion process (TASEP) with particles that occlude an integer number (d) of lattice sites are computed using various mean field approximations and Monte Carlo simulations. TASEP's featuring particles of arbitrary size are relevant for modeling systems such as mRNA translation, vesicle locomotion along microtubules, and protein sliding along DNA. We conjecture that the nonequilibrium steady-state properties separate into low density, high density, an maximal current phases similar to those of the standard (d=1) TASEP. A simple mean field approximation for steady-state particle currents and densities is found to be inaccurate. However, we find local equilibrium particle distributions derived from a discrete Tonks gas partition function yield apparently exact currents within the maximal current phase. For the boundary-limited phases, the equilibrium Tonks gas distribution cannot be used to predict currents, phase boundaries, or the order of the phase transitions. However, we employ a refined mean field approach to find apparently exact expressions for the steady state currents, boundary densities, and phase diagrams of the d>= 1 TASEP. Extensive Monte Carlo simulations are performed to support our analytic, mean field results.
Out-of-equilibrium energy flow and steady state configurations in AdS/CFT
Megias, Eugenio
2015-01-01
We study out-of-equilibrium energy flow in a strongly coupled system by using the AdS/CFT correspondence. In particular, we describe the appearance of a steady state connecting two asymptotic equilibrium systems. We obtain results within the linear response regime.
Energy Technology Data Exchange (ETDEWEB)
HU TA
2009-10-26
Assess the steady-state flammability level at normal and off-normal ventilation conditions. The hydrogen generation rate was calculated for 177 tanks using the rate equation model. Flammability calculations based on hydrogen, ammonia, and methane were performed for 177 tanks for various scenarios.
Thermal shock behaviour of blisters on W surface during combined steady-state/pulsed plasma loading
Jia, Y. Z.; Liu, W.; Xu, B.; Luo, G.-N.; Li, C.; Qu, S. L.; Morgan, T. W.; De Temmerman, G.
2015-09-01
The thermal shock behaviour of blister-covered W surfaces during combined steady-state/pulsed plasma loading was studied by scanning electron microscopy and electron backscatter diffraction. The W samples were first exposed to steady-state D plasma to induce blisters on the surface, and then the blistered surfaces were exposed to steady-state/pulsed plasma. Growth and cracking of blisters were observed after the exposure to the steady-state/pulsed plasma, while no obvious damage occurred on the surface area not covered with blisters. The results confirm that blisters induced by D plasma might represent weak spots on the W surface when exposed to transient heat load of ELMs. The cracks on blisters were different from the cracks due to the transient heat loads reported before, and they were assumed to be caused by stress and strain due to the gas expansion inside the blisters during the plasma pulses. Moreover, most of cracks were found to appear on the blisters formed on grains with surface orientation near [1 1 1].
Experimental study of vaporization effect on steady state and dynamic behavior of catalytic pellets
Kulikov, A.V.; Kuzin, N.A.; Shigarov, A.B.; Kirillov, V.A.; Westerterp, K.R.; Kronberg, Alexandre E.
2001-01-01
The impact of the combined evaporation of the liquid phase and reaction on single catalyst pellet performance has been studied experimentally. The exothermic, catalyzed hydrogenation of α-methylstyrene (AMS) to cumene has been employed as a model reaction. Steady state and dynamic experiments have
Computing Bifurcation Diagrams of Steady State KuramotoSivashinsky Equation by Difference Method
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Utilizing difference formulae, we obtained the discrete systems of steady state Kuramoto-Sivashinsky (K-S) equation. Applied Newton's method and continuation technology to the systems, the bifurcated solutions are derived, and the bifurcation diagrams are constructed. All the results are successful and satisfactory.
The total quasi-steady-state approximation for fully competitive enzyme reactions
DEFF Research Database (Denmark)
Pedersen, Morten Gram; Bersani, A.M.; Bersani, E.
2007-01-01
The validity of the Michaelis-Menten-Briggs-Haldane approximation for single enzyme reactions has recently been improved by the formalism of the total quasi-steady-state approximation. This approach is here extended to fully competitive systems, and a criterion for its validity is provided. We show...
Formulation of Non-steady-state Dust Formation Process in Astrophysical Environments
Nozawa, Takaya
2013-01-01
The non-steady-state formation of small clusters and the growth of grains accompanied by chemical reactions are formulated under the consideration that the collision of key gas species (key molecule) controls the kinetics of dust formation process. The formula allows us to evaluate the size distribution and condensation efficiency of dust formed in astrophysical environments. We apply the formulation to the formation of C and MgSiO3 grains in the ejecta of supernovae, as an example, to investigate how the non-steady effect influences the formation process, condensation efficiency f_{con}, and average radius a_{ave} of newly formed grains in comparison with the results calculated with the steady-state nucleation rate. We show that the steady-state nucleation rate is a good approximation if the collision timescale of key molecule tau_{coll} is much smaller than the timescale tau_{sat} with which the supersaturation ratio increases; otherwise the effect of the non-steady state becomes remarkable, leading to a lo...